FreeBSD/Linux Kernel Cross Reference
sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License (the "License").
      * You may not use this file except in compliance with the License.
      *
      * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      * or http://www.opensolaris.org/os/licensing.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     *
     * $FreeBSD$
     */
    
    /*
     * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
     * Copyright (c) 2016, Joyent, Inc. All rights reserved.
     * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
     */
    
    /*
     * DTrace - Dynamic Tracing for Solaris
     *
     * This is the implementation of the Solaris Dynamic Tracing framework
     * (DTrace).  The user-visible interface to DTrace is described at length in
     * the "Solaris Dynamic Tracing Guide".  The interfaces between the libdtrace
     * library, the in-kernel DTrace framework, and the DTrace providers are
     * described in the block comments in the <sys/dtrace.h> header file.  The
     * internal architecture of DTrace is described in the block comments in the
     * <sys/dtrace_impl.h> header file.  The comments contained within the DTrace
     * implementation very much assume mastery of all of these sources; if one has
     * an unanswered question about the implementation, one should consult them
     * first.
     *
     * The functions here are ordered roughly as follows:
     *
     *   - Probe context functions
     *   - Probe hashing functions
     *   - Non-probe context utility functions
     *   - Matching functions
     *   - Provider-to-Framework API functions
     *   - Probe management functions
     *   - DIF object functions
     *   - Format functions
     *   - Predicate functions
     *   - ECB functions
     *   - Buffer functions
     *   - Enabling functions
     *   - DOF functions
     *   - Anonymous enabling functions
     *   - Consumer state functions
     *   - Helper functions
     *   - Hook functions
     *   - Driver cookbook functions
     *
     * Each group of functions begins with a block comment labelled the "DTrace
     * [Group] Functions", allowing one to find each block by searching forward
     * on capital-f functions.
     */
    #include <sys/errno.h>
    #include <sys/param.h>
    #include <sys/types.h>
    #ifndef illumos
    #include <sys/time.h>
    #endif
    #include <sys/stat.h>
    #include <sys/conf.h>
    #include <sys/systm.h>
    #include <sys/endian.h>
    #ifdef illumos
    #include <sys/ddi.h>
    #include <sys/sunddi.h>
    #endif
    #include <sys/cpuvar.h>
    #include <sys/kmem.h>
    #ifdef illumos
    #include <sys/strsubr.h>
    #endif
    #include <sys/sysmacros.h>
    #include <sys/dtrace_impl.h>
    #include <sys/atomic.h>
    #include <sys/cmn_err.h>
    #ifdef illumos
    #include <sys/mutex_impl.h>
    #include <sys/rwlock_impl.h>
    #endif
    #include <sys/ctf_api.h>
    #ifdef illumos
    #include <sys/panic.h>
    #include <sys/priv_impl.h>
   #endif
   #ifdef illumos
   #include <sys/cred_impl.h>
   #include <sys/procfs_isa.h>
   #endif
   #include <sys/taskq.h>
   #ifdef illumos
   #include <sys/mkdev.h>
   #include <sys/kdi.h>
   #endif
   #include <sys/zone.h>
   #include <sys/socket.h>
   #include <netinet/in.h>
   #include "strtolctype.h"
   
   /* FreeBSD includes: */
   #ifndef illumos
   #include <sys/callout.h>
   #include <sys/ctype.h>
   #include <sys/eventhandler.h>
   #include <sys/limits.h>
   #include <sys/linker.h>
   #include <sys/kdb.h>
   #include <sys/jail.h>
   #include <sys/kernel.h>
   #include <sys/malloc.h>
   #include <sys/lock.h>
   #include <sys/mutex.h>
   #include <sys/ptrace.h>
   #include <sys/random.h>
   #include <sys/rwlock.h>
   #include <sys/sx.h>
   #include <sys/sysctl.h>
   
   
   #include <sys/mount.h>
   #undef AT_UID
   #undef AT_GID
   #include <sys/vnode.h>
   #include <sys/cred.h>
   
   #include <sys/dtrace_bsd.h>
   
   #include <netinet/in.h>
   
   #include "dtrace_cddl.h"
   #include "dtrace_debug.c"
   #endif
   
   #include "dtrace_xoroshiro128_plus.h"
   
   /*
    * DTrace Tunable Variables
    *
    * The following variables may be tuned by adding a line to /etc/system that
    * includes both the name of the DTrace module ("dtrace") and the name of the
    * variable.  For example:
    *
    *   set dtrace:dtrace_destructive_disallow = 1
    *
    * In general, the only variables that one should be tuning this way are those
    * that affect system-wide DTrace behavior, and for which the default behavior
    * is undesirable.  Most of these variables are tunable on a per-consumer
    * basis using DTrace options, and need not be tuned on a system-wide basis.
    * When tuning these variables, avoid pathological values; while some attempt
    * is made to verify the integrity of these variables, they are not considered
    * part of the supported interface to DTrace, and they are therefore not
    * checked comprehensively.  Further, these variables should not be tuned
    * dynamically via "mdb -kw" or other means; they should only be tuned via
    * /etc/system.
    */
   int             dtrace_destructive_disallow = 0;
   #ifndef illumos
   /* Positive logic version of dtrace_destructive_disallow for loader tunable */
   int             dtrace_allow_destructive = 1;
   #endif
   dtrace_optval_t dtrace_nonroot_maxsize = (16 * 1024 * 1024);
   size_t          dtrace_difo_maxsize = (256 * 1024);
   dtrace_optval_t dtrace_dof_maxsize = (8 * 1024 * 1024);
   size_t          dtrace_statvar_maxsize = (16 * 1024);
   size_t          dtrace_actions_max = (16 * 1024);
   size_t          dtrace_retain_max = 1024;
   dtrace_optval_t dtrace_helper_actions_max = 128;
   dtrace_optval_t dtrace_helper_providers_max = 32;
   dtrace_optval_t dtrace_dstate_defsize = (1 * 1024 * 1024);
   size_t          dtrace_strsize_default = 256;
   dtrace_optval_t dtrace_cleanrate_default = 9900990;             /* 101 hz */
   dtrace_optval_t dtrace_cleanrate_min = 200000;                  /* 5000 hz */
   dtrace_optval_t dtrace_cleanrate_max = (uint64_t)60 * NANOSEC;  /* 1/minute */
   dtrace_optval_t dtrace_aggrate_default = NANOSEC;               /* 1 hz */
   dtrace_optval_t dtrace_statusrate_default = NANOSEC;            /* 1 hz */
   dtrace_optval_t dtrace_statusrate_max = (hrtime_t)10 * NANOSEC;  /* 6/minute */
   dtrace_optval_t dtrace_switchrate_default = NANOSEC;            /* 1 hz */
   dtrace_optval_t dtrace_nspec_default = 1;
   dtrace_optval_t dtrace_specsize_default = 32 * 1024;
   dtrace_optval_t dtrace_stackframes_default = 20;
   dtrace_optval_t dtrace_ustackframes_default = 20;
   dtrace_optval_t dtrace_jstackframes_default = 50;
   dtrace_optval_t dtrace_jstackstrsize_default = 512;
   int             dtrace_msgdsize_max = 128;
   hrtime_t        dtrace_chill_max = MSEC2NSEC(500);              /* 500 ms */
   hrtime_t        dtrace_chill_interval = NANOSEC;                /* 1000 ms */
   int             dtrace_devdepth_max = 32;
   int             dtrace_err_verbose;
   hrtime_t        dtrace_deadman_interval = NANOSEC;
   hrtime_t        dtrace_deadman_timeout = (hrtime_t)10 * NANOSEC;
   hrtime_t        dtrace_deadman_user = (hrtime_t)30 * NANOSEC;
   hrtime_t        dtrace_unregister_defunct_reap = (hrtime_t)60 * NANOSEC;
   #ifndef illumos
   int             dtrace_memstr_max = 4096;
   int             dtrace_bufsize_max_frac = 128;
   #endif
   
   /*
    * DTrace External Variables
    *
    * As dtrace(7D) is a kernel module, any DTrace variables are obviously
    * available to DTrace consumers via the backtick (`) syntax.  One of these,
    * dtrace_zero, is made deliberately so:  it is provided as a source of
    * well-known, zero-filled memory.  While this variable is not documented,
    * it is used by some translators as an implementation detail.
    */
   const char      dtrace_zero[256] = { 0 };       /* zero-filled memory */
   
   /*
    * DTrace Internal Variables
    */
   #ifdef illumos
   static dev_info_t       *dtrace_devi;           /* device info */
   #endif
   #ifdef illumos
   static vmem_t           *dtrace_arena;          /* probe ID arena */
   static vmem_t           *dtrace_minor;          /* minor number arena */
   #else
   static taskq_t          *dtrace_taskq;          /* task queue */
   static struct unrhdr    *dtrace_arena;          /* Probe ID number.     */
   #endif
   static dtrace_probe_t   **dtrace_probes;        /* array of all probes */
   static int              dtrace_nprobes;         /* number of probes */
   static dtrace_provider_t *dtrace_provider;      /* provider list */
   static dtrace_meta_t    *dtrace_meta_pid;       /* user-land meta provider */
   static int              dtrace_opens;           /* number of opens */
   static int              dtrace_helpers;         /* number of helpers */
   static int              dtrace_getf;            /* number of unpriv getf()s */
   #ifdef illumos
   static void             *dtrace_softstate;      /* softstate pointer */
   #endif
   static dtrace_hash_t    *dtrace_bymod;          /* probes hashed by module */
   static dtrace_hash_t    *dtrace_byfunc;         /* probes hashed by function */
   static dtrace_hash_t    *dtrace_byname;         /* probes hashed by name */
   static dtrace_toxrange_t *dtrace_toxrange;      /* toxic range array */
   static int              dtrace_toxranges;       /* number of toxic ranges */
   static int              dtrace_toxranges_max;   /* size of toxic range array */
   static dtrace_anon_t    dtrace_anon;            /* anonymous enabling */
   static kmem_cache_t     *dtrace_state_cache;    /* cache for dynamic state */
   static uint64_t         dtrace_vtime_references; /* number of vtimestamp refs */
   static kthread_t        *dtrace_panicked;       /* panicking thread */
   static dtrace_ecb_t     *dtrace_ecb_create_cache; /* cached created ECB */
   static dtrace_genid_t   dtrace_probegen;        /* current probe generation */
   static dtrace_helpers_t *dtrace_deferred_pid;   /* deferred helper list */
   static dtrace_enabling_t *dtrace_retained;      /* list of retained enablings */
   static dtrace_genid_t   dtrace_retained_gen;    /* current retained enab gen */
   static dtrace_dynvar_t  dtrace_dynhash_sink;    /* end of dynamic hash chains */
   static int              dtrace_dynvar_failclean; /* dynvars failed to clean */
   #ifndef illumos
   static struct mtx       dtrace_unr_mtx;
   MTX_SYSINIT(dtrace_unr_mtx, &dtrace_unr_mtx, "Unique resource identifier", MTX_DEF);
   static eventhandler_tag dtrace_kld_load_tag;
   static eventhandler_tag dtrace_kld_unload_try_tag;
   #endif
   
   /*
    * DTrace Locking
    * DTrace is protected by three (relatively coarse-grained) locks:
    *
    * (1) dtrace_lock is required to manipulate essentially any DTrace state,
    *     including enabling state, probes, ECBs, consumer state, helper state,
    *     etc.  Importantly, dtrace_lock is _not_ required when in probe context;
    *     probe context is lock-free -- synchronization is handled via the
    *     dtrace_sync() cross call mechanism.
    *
    * (2) dtrace_provider_lock is required when manipulating provider state, or
    *     when provider state must be held constant.
    *
    * (3) dtrace_meta_lock is required when manipulating meta provider state, or
    *     when meta provider state must be held constant.
    *
    * The lock ordering between these three locks is dtrace_meta_lock before
    * dtrace_provider_lock before dtrace_lock.  (In particular, there are
    * several places where dtrace_provider_lock is held by the framework as it
    * calls into the providers -- which then call back into the framework,
    * grabbing dtrace_lock.)
    *
    * There are two other locks in the mix:  mod_lock and cpu_lock.  With respect
    * to dtrace_provider_lock and dtrace_lock, cpu_lock continues its historical
    * role as a coarse-grained lock; it is acquired before both of these locks.
    * With respect to dtrace_meta_lock, its behavior is stranger:  cpu_lock must
    * be acquired _between_ dtrace_meta_lock and any other DTrace locks.
    * mod_lock is similar with respect to dtrace_provider_lock in that it must be
    * acquired _between_ dtrace_provider_lock and dtrace_lock.
    */
   static kmutex_t         dtrace_lock;            /* probe state lock */
   static kmutex_t         dtrace_provider_lock;   /* provider state lock */
   static kmutex_t         dtrace_meta_lock;       /* meta-provider state lock */
   
   #ifndef illumos
   /* XXX FreeBSD hacks. */
   #define cr_suid         cr_svuid
   #define cr_sgid         cr_svgid
   #define ipaddr_t        in_addr_t
   #define mod_modname     pathname
   #define vuprintf        vprintf
   #ifndef crgetzoneid
   #define crgetzoneid(_a)        0
   #endif
   #define ttoproc(_a)     ((_a)->td_proc)
   #define SNOCD           0
   #define CPU_ON_INTR(_a) 0
   
   #define PRIV_EFFECTIVE          (1 << 0)
   #define PRIV_DTRACE_KERNEL      (1 << 1)
   #define PRIV_DTRACE_PROC        (1 << 2)
   #define PRIV_DTRACE_USER        (1 << 3)
   #define PRIV_PROC_OWNER         (1 << 4)
   #define PRIV_PROC_ZONE          (1 << 5)
   #define PRIV_ALL                ~0
   
   SYSCTL_DECL(_debug_dtrace);
   SYSCTL_DECL(_kern_dtrace);
   #endif
   
   #ifdef illumos
   #define curcpu  CPU->cpu_id
   #endif
   
   
   /*
    * DTrace Provider Variables
    *
    * These are the variables relating to DTrace as a provider (that is, the
    * provider of the BEGIN, END, and ERROR probes).
    */
   static dtrace_pattr_t   dtrace_provider_attr = {
   { DTRACE_STABILITY_STABLE, DTRACE_STABILITY_STABLE, DTRACE_CLASS_COMMON },
   { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
   { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
   { DTRACE_STABILITY_STABLE, DTRACE_STABILITY_STABLE, DTRACE_CLASS_COMMON },
   { DTRACE_STABILITY_STABLE, DTRACE_STABILITY_STABLE, DTRACE_CLASS_COMMON },
   };
   
   static void
   dtrace_nullop(void)
   {}
   
   static dtrace_pops_t dtrace_provider_ops = {
           .dtps_provide = (void (*)(void *, dtrace_probedesc_t *))dtrace_nullop,
           .dtps_provide_module =  (void (*)(void *, modctl_t *))dtrace_nullop,
           .dtps_enable =  (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
           .dtps_disable = (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
           .dtps_suspend = (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
           .dtps_resume =  (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
           .dtps_getargdesc =      NULL,
           .dtps_getargval =       NULL,
           .dtps_usermode =        NULL,
           .dtps_destroy = (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
   };
   
   static dtrace_id_t      dtrace_probeid_begin;   /* special BEGIN probe */
   static dtrace_id_t      dtrace_probeid_end;     /* special END probe */
   dtrace_id_t             dtrace_probeid_error;   /* special ERROR probe */
   
   /*
    * DTrace Helper Tracing Variables
    *
    * These variables should be set dynamically to enable helper tracing.  The
    * only variables that should be set are dtrace_helptrace_enable (which should
    * be set to a non-zero value to allocate helper tracing buffers on the next
    * open of /dev/dtrace) and dtrace_helptrace_disable (which should be set to a
    * non-zero value to deallocate helper tracing buffers on the next close of
    * /dev/dtrace).  When (and only when) helper tracing is disabled, the
    * buffer size may also be set via dtrace_helptrace_bufsize.
    */
   int                     dtrace_helptrace_enable = 0;
   int                     dtrace_helptrace_disable = 0;
   int                     dtrace_helptrace_bufsize = 16 * 1024 * 1024;
   uint32_t                dtrace_helptrace_nlocals;
   static dtrace_helptrace_t *dtrace_helptrace_buffer;
   static uint32_t         dtrace_helptrace_next = 0;
   static int              dtrace_helptrace_wrapped = 0;
   
   /*
    * DTrace Error Hashing
    *
    * On DEBUG kernels, DTrace will track the errors that has seen in a hash
    * table.  This is very useful for checking coverage of tests that are
    * expected to induce DIF or DOF processing errors, and may be useful for
    * debugging problems in the DIF code generator or in DOF generation .  The
    * error hash may be examined with the ::dtrace_errhash MDB dcmd.
    */
   #ifdef DEBUG
   static dtrace_errhash_t dtrace_errhash[DTRACE_ERRHASHSZ];
   static const char *dtrace_errlast;
   static kthread_t *dtrace_errthread;
   static kmutex_t dtrace_errlock;
   #endif
   
   /*
    * DTrace Macros and Constants
    *
    * These are various macros that are useful in various spots in the
    * implementation, along with a few random constants that have no meaning
    * outside of the implementation.  There is no real structure to this cpp
    * mishmash -- but is there ever?
    */
   #define DTRACE_HASHSTR(hash, probe)     \
           dtrace_hash_str(*((char **)((uintptr_t)(probe) + (hash)->dth_stroffs)))
   
   #define DTRACE_HASHNEXT(hash, probe)    \
           (dtrace_probe_t **)((uintptr_t)(probe) + (hash)->dth_nextoffs)
   
   #define DTRACE_HASHPREV(hash, probe)    \
           (dtrace_probe_t **)((uintptr_t)(probe) + (hash)->dth_prevoffs)
   
   #define DTRACE_HASHEQ(hash, lhs, rhs)   \
           (strcmp(*((char **)((uintptr_t)(lhs) + (hash)->dth_stroffs)), \
               *((char **)((uintptr_t)(rhs) + (hash)->dth_stroffs))) == 0)
   
   #define DTRACE_AGGHASHSIZE_SLEW         17
   
   #define DTRACE_V4MAPPED_OFFSET          (sizeof (uint32_t) * 3)
   
   /*
    * The key for a thread-local variable consists of the lower 61 bits of the
    * t_did, plus the 3 bits of the highest active interrupt above LOCK_LEVEL.
    * We add DIF_VARIABLE_MAX to t_did to assure that the thread key is never
    * equal to a variable identifier.  This is necessary (but not sufficient) to
    * assure that global associative arrays never collide with thread-local
    * variables.  To guarantee that they cannot collide, we must also define the
    * order for keying dynamic variables.  That order is:
    *
    *   [ key0 ] ... [ keyn ] [ variable-key ] [ tls-key ]
    *
    * Because the variable-key and the tls-key are in orthogonal spaces, there is
    * no way for a global variable key signature to match a thread-local key
    * signature.
    */
   #ifdef illumos
   #define DTRACE_TLS_THRKEY(where) { \
           uint_t intr = 0; \
           uint_t actv = CPU->cpu_intr_actv >> (LOCK_LEVEL + 1); \
           for (; actv; actv >>= 1) \
                   intr++; \
           ASSERT(intr < (1 << 3)); \
           (where) = ((curthread->t_did + DIF_VARIABLE_MAX) & \
               (((uint64_t)1 << 61) - 1)) | ((uint64_t)intr << 61); \
   }
   #else
   #define DTRACE_TLS_THRKEY(where) { \
           solaris_cpu_t *_c = &solaris_cpu[curcpu]; \
           uint_t intr = 0; \
           uint_t actv = _c->cpu_intr_actv; \
           for (; actv; actv >>= 1) \
                   intr++; \
           ASSERT(intr < (1 << 3)); \
           (where) = ((curthread->td_tid + DIF_VARIABLE_MAX) & \
               (((uint64_t)1 << 61) - 1)) | ((uint64_t)intr << 61); \
   }
   #endif
   
   #define DT_BSWAP_8(x)   ((x) & 0xff)
   #define DT_BSWAP_16(x)  ((DT_BSWAP_8(x) << 8) | DT_BSWAP_8((x) >> 8))
   #define DT_BSWAP_32(x)  ((DT_BSWAP_16(x) << 16) | DT_BSWAP_16((x) >> 16))
   #define DT_BSWAP_64(x)  ((DT_BSWAP_32(x) << 32) | DT_BSWAP_32((x) >> 32))
   
   #define DT_MASK_LO 0x00000000FFFFFFFFULL
   
   #define DTRACE_STORE(type, tomax, offset, what) \
           *((type *)((uintptr_t)(tomax) + (uintptr_t)offset)) = (type)(what);
   
   #if !defined(__x86) && !defined(__aarch64__)
   #define DTRACE_ALIGNCHECK(addr, size, flags)                            \
           if (addr & (size - 1)) {                                        \
                   *flags |= CPU_DTRACE_BADALIGN;                          \
                   cpu_core[curcpu].cpuc_dtrace_illval = addr;     \
                   return (0);                                             \
           }
   #else
   #define DTRACE_ALIGNCHECK(addr, size, flags)
   #endif
   
   /*
    * Test whether a range of memory starting at testaddr of size testsz falls
    * within the range of memory described by addr, sz.  We take care to avoid
    * problems with overflow and underflow of the unsigned quantities, and
    * disallow all negative sizes.  Ranges of size 0 are allowed.
    */
   #define DTRACE_INRANGE(testaddr, testsz, baseaddr, basesz) \
           ((testaddr) - (uintptr_t)(baseaddr) < (basesz) && \
           (testaddr) + (testsz) - (uintptr_t)(baseaddr) <= (basesz) && \
           (testaddr) + (testsz) >= (testaddr))
   
   #define DTRACE_RANGE_REMAIN(remp, addr, baseaddr, basesz)               \
   do {                                                                    \
           if ((remp) != NULL) {                                           \
                   *(remp) = (uintptr_t)(baseaddr) + (basesz) - (addr);    \
           }                                                               \
   } while (0)
   
   
   /*
    * Test whether alloc_sz bytes will fit in the scratch region.  We isolate
    * alloc_sz on the righthand side of the comparison in order to avoid overflow
    * or underflow in the comparison with it.  This is simpler than the INRANGE
    * check above, because we know that the dtms_scratch_ptr is valid in the
    * range.  Allocations of size zero are allowed.
    */
   #define DTRACE_INSCRATCH(mstate, alloc_sz) \
           ((mstate)->dtms_scratch_base + (mstate)->dtms_scratch_size - \
           (mstate)->dtms_scratch_ptr >= (alloc_sz))
   
   #define DTRACE_LOADFUNC(bits)                                           \
   /*CSTYLED*/                                                             \
   uint##bits##_t                                                          \
   dtrace_load##bits(uintptr_t addr)                                       \
   {                                                                       \
           size_t size = bits / NBBY;                                      \
           /*CSTYLED*/                                                     \
           uint##bits##_t rval;                                            \
           int i;                                                          \
           volatile uint16_t *flags = (volatile uint16_t *)                \
               &cpu_core[curcpu].cpuc_dtrace_flags;                        \
                                                                           \
           DTRACE_ALIGNCHECK(addr, size, flags);                           \
                                                                           \
           for (i = 0; i < dtrace_toxranges; i++) {                        \
                   if (addr >= dtrace_toxrange[i].dtt_limit)               \
                           continue;                                       \
                                                                           \
                   if (addr + size <= dtrace_toxrange[i].dtt_base)         \
                           continue;                                       \
                                                                           \
                   /*                                                      \
                    * This address falls within a toxic region; return 0.  \
                    */                                                     \
                   *flags |= CPU_DTRACE_BADADDR;                           \
                   cpu_core[curcpu].cpuc_dtrace_illval = addr;             \
                   return (0);                                             \
           }                                                               \
                                                                           \
           *flags |= CPU_DTRACE_NOFAULT;                                   \
           /*CSTYLED*/                                                     \
           rval = *((volatile uint##bits##_t *)addr);                      \
           *flags &= ~CPU_DTRACE_NOFAULT;                                  \
                                                                           \
           return (!(*flags & CPU_DTRACE_FAULT) ? rval : 0);               \
   }
   
   #ifdef _LP64
   #define dtrace_loadptr  dtrace_load64
   #else
   #define dtrace_loadptr  dtrace_load32
   #endif
   
   #define DTRACE_DYNHASH_FREE     0
   #define DTRACE_DYNHASH_SINK     1
   #define DTRACE_DYNHASH_VALID    2
   
   #define DTRACE_MATCH_NEXT       0
   #define DTRACE_MATCH_DONE       1
   #define DTRACE_ANCHORED(probe)  ((probe)->dtpr_func[0] != '\0')
   #define DTRACE_STATE_ALIGN      64
   
   #define DTRACE_FLAGS2FLT(flags)                                         \
           (((flags) & CPU_DTRACE_BADADDR) ? DTRACEFLT_BADADDR :           \
           ((flags) & CPU_DTRACE_ILLOP) ? DTRACEFLT_ILLOP :                \
           ((flags) & CPU_DTRACE_DIVZERO) ? DTRACEFLT_DIVZERO :            \
           ((flags) & CPU_DTRACE_KPRIV) ? DTRACEFLT_KPRIV :                \
           ((flags) & CPU_DTRACE_UPRIV) ? DTRACEFLT_UPRIV :                \
           ((flags) & CPU_DTRACE_TUPOFLOW) ?  DTRACEFLT_TUPOFLOW :         \
           ((flags) & CPU_DTRACE_BADALIGN) ?  DTRACEFLT_BADALIGN :         \
           ((flags) & CPU_DTRACE_NOSCRATCH) ?  DTRACEFLT_NOSCRATCH :       \
           ((flags) & CPU_DTRACE_BADSTACK) ?  DTRACEFLT_BADSTACK :         \
           DTRACEFLT_UNKNOWN)
   
   #define DTRACEACT_ISSTRING(act)                                         \
           ((act)->dta_kind == DTRACEACT_DIFEXPR &&                        \
           (act)->dta_difo->dtdo_rtype.dtdt_kind == DIF_TYPE_STRING)
   
   /* Function prototype definitions: */
   static size_t dtrace_strlen(const char *, size_t);
   static dtrace_probe_t *dtrace_probe_lookup_id(dtrace_id_t id);
   static void dtrace_enabling_provide(dtrace_provider_t *);
   static int dtrace_enabling_match(dtrace_enabling_t *, int *);
   static void dtrace_enabling_matchall(void);
   static void dtrace_enabling_reap(void);
   static dtrace_state_t *dtrace_anon_grab(void);
   static uint64_t dtrace_helper(int, dtrace_mstate_t *,
       dtrace_state_t *, uint64_t, uint64_t);
   static dtrace_helpers_t *dtrace_helpers_create(proc_t *);
   static void dtrace_buffer_drop(dtrace_buffer_t *);
   static int dtrace_buffer_consumed(dtrace_buffer_t *, hrtime_t when);
   static intptr_t dtrace_buffer_reserve(dtrace_buffer_t *, size_t, size_t,
       dtrace_state_t *, dtrace_mstate_t *);
   static int dtrace_state_option(dtrace_state_t *, dtrace_optid_t,
       dtrace_optval_t);
   static int dtrace_ecb_create_enable(dtrace_probe_t *, void *);
   static void dtrace_helper_provider_destroy(dtrace_helper_provider_t *);
   uint16_t dtrace_load16(uintptr_t);
   uint32_t dtrace_load32(uintptr_t);
   uint64_t dtrace_load64(uintptr_t);
   uint8_t dtrace_load8(uintptr_t);
   void dtrace_dynvar_clean(dtrace_dstate_t *);
   dtrace_dynvar_t *dtrace_dynvar(dtrace_dstate_t *, uint_t, dtrace_key_t *,
       size_t, dtrace_dynvar_op_t, dtrace_mstate_t *, dtrace_vstate_t *);
   uintptr_t dtrace_dif_varstr(uintptr_t, dtrace_state_t *, dtrace_mstate_t *);
   static int dtrace_priv_proc(dtrace_state_t *);
   static void dtrace_getf_barrier(void);
   static int dtrace_canload_remains(uint64_t, size_t, size_t *,
       dtrace_mstate_t *, dtrace_vstate_t *);
   static int dtrace_canstore_remains(uint64_t, size_t, size_t *,
       dtrace_mstate_t *, dtrace_vstate_t *);
   
   /*
    * DTrace Probe Context Functions
    *
    * These functions are called from probe context.  Because probe context is
    * any context in which C may be called, arbitrarily locks may be held,
    * interrupts may be disabled, we may be in arbitrary dispatched state, etc.
    * As a result, functions called from probe context may only call other DTrace
    * support functions -- they may not interact at all with the system at large.
    * (Note that the ASSERT macro is made probe-context safe by redefining it in
    * terms of dtrace_assfail(), a probe-context safe function.) If arbitrary
    * loads are to be performed from probe context, they _must_ be in terms of
    * the safe dtrace_load*() variants.
    *
    * Some functions in this block are not actually called from probe context;
    * for these functions, there will be a comment above the function reading
    * "Note:  not called from probe context."
    */
   void
   dtrace_panic(const char *format, ...)
   {
           va_list alist;
   
           va_start(alist, format);
   #ifdef __FreeBSD__
           vpanic(format, alist);
   #else
           dtrace_vpanic(format, alist);
   #endif
           va_end(alist);
   }
   
   int
   dtrace_assfail(const char *a, const char *f, int l)
   {
           dtrace_panic("assertion failed: %s, file: %s, line: %d", a, f, l);
   
           /*
            * We just need something here that even the most clever compiler
            * cannot optimize away.
            */
           return (a[(uintptr_t)f]);
   }
   
   /*
    * Atomically increment a specified error counter from probe context.
    */
   static void
   dtrace_error(uint32_t *counter)
   {
           /*
            * Most counters stored to in probe context are per-CPU counters.
            * However, there are some error conditions that are sufficiently
            * arcane that they don't merit per-CPU storage.  If these counters
            * are incremented concurrently on different CPUs, scalability will be
            * adversely affected -- but we don't expect them to be white-hot in a
            * correctly constructed enabling...
            */
           uint32_t oval, nval;
   
           do {
                   oval = *counter;
   
                   if ((nval = oval + 1) == 0) {
                           /*
                            * If the counter would wrap, set it to 1 -- assuring
                            * that the counter is never zero when we have seen
                            * errors.  (The counter must be 32-bits because we
                            * aren't guaranteed a 64-bit compare&swap operation.)
                            * To save this code both the infamy of being fingered
                            * by a priggish news story and the indignity of being
                            * the target of a neo-puritan witch trial, we're
                            * carefully avoiding any colorful description of the
                            * likelihood of this condition -- but suffice it to
                            * say that it is only slightly more likely than the
                            * overflow of predicate cache IDs, as discussed in
                            * dtrace_predicate_create().
                            */
                           nval = 1;
                   }
           } while (dtrace_cas32(counter, oval, nval) != oval);
   }
   
   /*
    * Use the DTRACE_LOADFUNC macro to define functions for each of loading a
    * uint8_t, a uint16_t, a uint32_t and a uint64_t.
    */
   /* BEGIN CSTYLED */
   DTRACE_LOADFUNC(8)
   DTRACE_LOADFUNC(16)
   DTRACE_LOADFUNC(32)
   DTRACE_LOADFUNC(64)
   /* END CSTYLED */
   
   static int
   dtrace_inscratch(uintptr_t dest, size_t size, dtrace_mstate_t *mstate)
   {
           if (dest < mstate->dtms_scratch_base)
                   return (0);
   
           if (dest + size < dest)
                   return (0);
   
           if (dest + size > mstate->dtms_scratch_ptr)
                   return (0);
   
           return (1);
   }
   
   static int
   dtrace_canstore_statvar(uint64_t addr, size_t sz, size_t *remain,
       dtrace_statvar_t **svars, int nsvars)
   {
           int i;
           size_t maxglobalsize, maxlocalsize;
   
           if (nsvars == 0)
                   return (0);
   
           maxglobalsize = dtrace_statvar_maxsize + sizeof (uint64_t);
           maxlocalsize = maxglobalsize * NCPU;
   
           for (i = 0; i < nsvars; i++) {
                   dtrace_statvar_t *svar = svars[i];
                   uint8_t scope;
                   size_t size;
   
                   if (svar == NULL || (size = svar->dtsv_size) == 0)
                           continue;
   
                   scope = svar->dtsv_var.dtdv_scope;
   
                   /*
                    * We verify that our size is valid in the spirit of providing
                    * defense in depth:  we want to prevent attackers from using
                    * DTrace to escalate an orthogonal kernel heap corruption bug
                    * into the ability to store to arbitrary locations in memory.
                    */
                   VERIFY((scope == DIFV_SCOPE_GLOBAL && size <= maxglobalsize) ||
                       (scope == DIFV_SCOPE_LOCAL && size <= maxlocalsize));
   
                   if (DTRACE_INRANGE(addr, sz, svar->dtsv_data,
                       svar->dtsv_size)) {
                           DTRACE_RANGE_REMAIN(remain, addr, svar->dtsv_data,
                               svar->dtsv_size);
                           return (1);
                   }
           }
   
           return (0);
   }
   
   /*
    * Check to see if the address is within a memory region to which a store may
    * be issued.  This includes the DTrace scratch areas, and any DTrace variable
    * region.  The caller of dtrace_canstore() is responsible for performing any
    * alignment checks that are needed before stores are actually executed.
    */
   static int
   dtrace_canstore(uint64_t addr, size_t sz, dtrace_mstate_t *mstate,
       dtrace_vstate_t *vstate)
   {
           return (dtrace_canstore_remains(addr, sz, NULL, mstate, vstate));
   }
   
   /*
    * Implementation of dtrace_canstore which communicates the upper bound of the
    * allowed memory region.
    */
   static int
   dtrace_canstore_remains(uint64_t addr, size_t sz, size_t *remain,
       dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
   {
           /*
            * First, check to see if the address is in scratch space...
            */
           if (DTRACE_INRANGE(addr, sz, mstate->dtms_scratch_base,
               mstate->dtms_scratch_size)) {
                   DTRACE_RANGE_REMAIN(remain, addr, mstate->dtms_scratch_base,
                       mstate->dtms_scratch_size);
                   return (1);
           }
   
           /*
            * Now check to see if it's a dynamic variable.  This check will pick
            * up both thread-local variables and any global dynamically-allocated
            * variables.
            */
           if (DTRACE_INRANGE(addr, sz, vstate->dtvs_dynvars.dtds_base,
               vstate->dtvs_dynvars.dtds_size)) {
                   dtrace_dstate_t *dstate = &vstate->dtvs_dynvars;
                   uintptr_t base = (uintptr_t)dstate->dtds_base +
                       (dstate->dtds_hashsize * sizeof (dtrace_dynhash_t));
                   uintptr_t chunkoffs;
                   dtrace_dynvar_t *dvar;
   
                   /*
                    * Before we assume that we can store here, we need to make
                    * sure that it isn't in our metadata -- storing to our
                    * dynamic variable metadata would corrupt our state.  For
                    * the range to not include any dynamic variable metadata,
                    * it must:
                    *
                    *      (1) Start above the hash table that is at the base of
                    *      the dynamic variable space
                    *
                    *      (2) Have a starting chunk offset that is beyond the
                    *      dtrace_dynvar_t that is at the base of every chunk
                    *
                    *      (3) Not span a chunk boundary
                    *
                    *      (4) Not be in the tuple space of a dynamic variable
                    *
                    */
                   if (addr < base)
                           return (0);
   
                   chunkoffs = (addr - base) % dstate->dtds_chunksize;
   
                   if (chunkoffs < sizeof (dtrace_dynvar_t))
                           return (0);
   
                   if (chunkoffs + sz > dstate->dtds_chunksize)
                           return (0);
   
                   dvar = (dtrace_dynvar_t *)((uintptr_t)addr - chunkoffs);
   
                   if (dvar->dtdv_hashval == DTRACE_DYNHASH_FREE)
                           return (0);
   
                   if (chunkoffs < sizeof (dtrace_dynvar_t) +
                       ((dvar->dtdv_tuple.dtt_nkeys - 1) * sizeof (dtrace_key_t)))
                           return (0);
   
                   DTRACE_RANGE_REMAIN(remain, addr, dvar, dstate->dtds_chunksize);
                   return (1);
           }
   
           /*
            * Finally, check the static local and global variables.  These checks
            * take the longest, so we perform them last.
            */
           if (dtrace_canstore_statvar(addr, sz, remain,
               vstate->dtvs_locals, vstate->dtvs_nlocals))
                   return (1);
   
           if (dtrace_canstore_statvar(addr, sz, remain,
               vstate->dtvs_globals, vstate->dtvs_nglobals))
                   return (1);
   
           return (0);
   }
   
   
   /*
    * Convenience routine to check to see if the address is within a memory
    * region in which a load may be issued given the user's privilege level;
    * if not, it sets the appropriate error flags and loads 'addr' into the
    * illegal value slot.
    *
    * DTrace subroutines (DIF_SUBR_*) should use this helper to implement
    * appropriate memory access protection.
    */
   static int
   dtrace_canload(uint64_t addr, size_t sz, dtrace_mstate_t *mstate,
       dtrace_vstate_t *vstate)
   {
           return (dtrace_canload_remains(addr, sz, NULL, mstate, vstate));
   }
   
   /*
    * Implementation of dtrace_canload which communicates the uppoer bound of the
    * allowed memory region.
    */
   static int
   dtrace_canload_remains(uint64_t addr, size_t sz, size_t *remain,
       dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
   {
           volatile uintptr_t *illval = &cpu_core[curcpu].cpuc_dtrace_illval;
           file_t *fp;
   
           /*
            * If we hold the privilege to read from kernel memory, then
            * everything is readable.
            */
           if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0) {
                   DTRACE_RANGE_REMAIN(remain, addr, addr, sz);
                   return (1);
           }
   
           /*
            * You can obviously read that which you can store.
            */
           if (dtrace_canstore_remains(addr, sz, remain, mstate, vstate))
                   return (1);
   
           /*
            * We're allowed to read from our own string table.
            */
           if (DTRACE_INRANGE(addr, sz, mstate->dtms_difo->dtdo_strtab,
               mstate->dtms_difo->dtdo_strlen)) {
                   DTRACE_RANGE_REMAIN(remain, addr,
                       mstate->dtms_difo->dtdo_strtab,
                       mstate->dtms_difo->dtdo_strlen);
                   return (1);
           }
   
           if (vstate->dtvs_state != NULL &&
               dtrace_priv_proc(vstate->dtvs_state)) {
                   proc_t *p;
   
                   /*
                    * When we have privileges to the current process, there are
                    * several context-related kernel structures that are safe to
                    * read, even absent the privilege to read from kernel memory.
                    * These reads are safe because these structures contain only
                    * state that (1) we're permitted to read, (2) is harmless or
                    * (3) contains pointers to additional kernel state that we're
                    * not permitted to read (and as such, do not present an
                    * opportunity for privilege escalation).  Finally (and
                    * critically), because of the nature of their relation with
                    * the current thread context, the memory associated with these
                    * structures cannot change over the duration of probe context,
                    * and it is therefore impossible for this memory to be
                    * deallocated and reallocated as something else while it's
                    * being operated upon.
                    */
                   if (DTRACE_INRANGE(addr, sz, curthread, sizeof (kthread_t))) {
                           DTRACE_RANGE_REMAIN(remain, addr, curthread,
                               sizeof (kthread_t));
                           return (1);
                   }
   
                   if ((p = curthread->t_procp) != NULL && DTRACE_INRANGE(addr,
                       sz, curthread->t_procp, sizeof (proc_t))) {
                           DTRACE_RANGE_REMAIN(remain, addr, curthread->t_procp,
                               sizeof (proc_t));
                           return (1);
                   }
   
                   if (curthread->t_cred != NULL && DTRACE_INRANGE(addr, sz,
                       curthread->t_cred, sizeof (cred_t))) {
                           DTRACE_RANGE_REMAIN(remain, addr, curthread->t_cred,
                               sizeof (cred_t));
                           return (1);
                   }
   
   #ifdef illumos
                   if (p != NULL && p->p_pidp != NULL && DTRACE_INRANGE(addr, sz,
                       &(p->p_pidp->pid_id), sizeof (pid_t))) {
                           DTRACE_RANGE_REMAIN(remain, addr, &(p->p_pidp->pid_id),
                               sizeof (pid_t));
                           return (1);
                   }
   
                   if (curthread->t_cpu != NULL && DTRACE_INRANGE(addr, sz,
                       curthread->t_cpu, offsetof(cpu_t, cpu_pause_thread))) {
                           DTRACE_RANGE_REMAIN(remain, addr, curthread->t_cpu,
                               offsetof(cpu_t, cpu_pause_thread));
                           return (1);
                   }
   #endif
           }
   
           if ((fp = mstate->dtms_getf) != NULL) {
                   uintptr_t psz = sizeof (void *);
                   vnode_t *vp;
                   vnodeops_t *op;
   
                   /*
                    * When getf() returns a file_t, the enabling is implicitly
                    * granted the (transient) right to read the returned file_t
                    * as well as the v_path and v_op->vnop_name of the underlying
                    * vnode.  These accesses are allowed after a successful
                    * getf() because the members that they refer to cannot change
                    * once set -- and the barrier logic in the kernel's closef()
                    * path assures that the file_t and its referenced vode_t
                    * cannot themselves be stale (that is, it impossible for
                    * either dtms_getf itself or its f_vnode member to reference
                   * freed memory).
                   */
                  if (DTRACE_INRANGE(addr, sz, fp, sizeof (file_t))) {
                          DTRACE_RANGE_REMAIN(remain, addr, fp, sizeof (file_t));
                          return (1);
                  }
  
                  if ((vp = fp->f_vnode) != NULL) {
                          size_t slen;
  #ifdef illumos
                          if (DTRACE_INRANGE(addr, sz, &vp->v_path, psz)) {
                                  DTRACE_RANGE_REMAIN(remain, addr, &vp->v_path,
                                      psz);
                                  return (1);
                          }
                          slen = strlen(vp->v_path) + 1;
                          if (DTRACE_INRANGE(addr, sz, vp->v_path, slen)) {
                                  DTRACE_RANGE_REMAIN(remain, addr, vp->v_path,
                                      slen);
                                  return (1);
                          }
  #endif
  
                          if (DTRACE_INRANGE(addr, sz, &vp->v_op, psz)) {
                                  DTRACE_RANGE_REMAIN(remain, addr, &vp->v_op,
                                      psz);
                                  return (1);
                          }
  
  #ifdef illumos
                          if ((op = vp->v_op) != NULL &&
                              DTRACE_INRANGE(addr, sz, &op->vnop_name, psz)) {
                                  DTRACE_RANGE_REMAIN(remain, addr,
                                      &op->vnop_name, psz);
                                  return (1);
                          }
  
                          if (op != NULL && op->vnop_name != NULL &&
                              DTRACE_INRANGE(addr, sz, op->vnop_name,
                              (slen = strlen(op->vnop_name) + 1))) {
                                  DTRACE_RANGE_REMAIN(remain, addr,
                                      op->vnop_name, slen);
                                  return (1);
                          }
  #endif
                  }
          }
  
          DTRACE_CPUFLAG_SET(CPU_DTRACE_KPRIV);
          *illval = addr;
          return (0);
  }
  
  /*
   * Convenience routine to check to see if a given string is within a memory
   * region in which a load may be issued given the user's privilege level;
   * this exists so that we don't need to issue unnecessary dtrace_strlen()
   * calls in the event that the user has all privileges.
   */
  static int
  dtrace_strcanload(uint64_t addr, size_t sz, size_t *remain,
      dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
  {
          size_t rsize;
  
          /*
           * If we hold the privilege to read from kernel memory, then
           * everything is readable.
           */
          if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0) {
                  DTRACE_RANGE_REMAIN(remain, addr, addr, sz);
                  return (1);
          }
  
          /*
           * Even if the caller is uninterested in querying the remaining valid
           * range, it is required to ensure that the access is allowed.
           */
          if (remain == NULL) {
                  remain = &rsize;
          }
          if (dtrace_canload_remains(addr, 0, remain, mstate, vstate)) {
                  size_t strsz;
                  /*
                   * Perform the strlen after determining the length of the
                   * memory region which is accessible.  This prevents timing
                   * information from being used to find NULs in memory which is
                   * not accessible to the caller.
                   */
                  strsz = 1 + dtrace_strlen((char *)(uintptr_t)addr,
                      MIN(sz, *remain));
                  if (strsz <= *remain) {
                          return (1);
                  }
          }
  
          return (0);
  }
  
  /*
   * Convenience routine to check to see if a given variable is within a memory
   * region in which a load may be issued given the user's privilege level.
   */
  static int
  dtrace_vcanload(void *src, dtrace_diftype_t *type, size_t *remain,
      dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
  {
          size_t sz;
          ASSERT(type->dtdt_flags & DIF_TF_BYREF);
  
          /*
           * Calculate the max size before performing any checks since even
           * DTRACE_ACCESS_KERNEL-credentialed callers expect that this function
           * return the max length via 'remain'.
           */
          if (type->dtdt_kind == DIF_TYPE_STRING) {
                  dtrace_state_t *state = vstate->dtvs_state;
  
                  if (state != NULL) {
                          sz = state->dts_options[DTRACEOPT_STRSIZE];
                  } else {
                          /*
                           * In helper context, we have a NULL state; fall back
                           * to using the system-wide default for the string size
                           * in this case.
                           */
                          sz = dtrace_strsize_default;
                  }
          } else {
                  sz = type->dtdt_size;
          }
  
          /*
           * If we hold the privilege to read from kernel memory, then
           * everything is readable.
           */
          if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0) {
                  DTRACE_RANGE_REMAIN(remain, (uintptr_t)src, src, sz);
                  return (1);
          }
  
          if (type->dtdt_kind == DIF_TYPE_STRING) {
                  return (dtrace_strcanload((uintptr_t)src, sz, remain, mstate,
                      vstate));
          }
          return (dtrace_canload_remains((uintptr_t)src, sz, remain, mstate,
              vstate));
  }
  
  /*
   * Convert a string to a signed integer using safe loads.
   *
   * NOTE: This function uses various macros from strtolctype.h to manipulate
   * digit values, etc -- these have all been checked to ensure they make
   * no additional function calls.
   */
  static int64_t
  dtrace_strtoll(char *input, int base, size_t limit)
  {
          uintptr_t pos = (uintptr_t)input;
          int64_t val = 0;
          int x;
          boolean_t neg = B_FALSE;
          char c, cc, ccc;
          uintptr_t end = pos + limit;
  
          /*
           * Consume any whitespace preceding digits.
           */
          while ((c = dtrace_load8(pos)) == ' ' || c == '\t')
                  pos++;
  
          /*
           * Handle an explicit sign if one is present.
           */
          if (c == '-' || c == '+') {
                  if (c == '-')
                          neg = B_TRUE;
                  c = dtrace_load8(++pos);
          }
  
          /*
           * Check for an explicit hexadecimal prefix ("0x" or "0X") and skip it
           * if present.
           */
          if (base == 16 && c == '' && ((cc = dtrace_load8(pos + 1)) == 'x' ||
              cc == 'X') && isxdigit(ccc = dtrace_load8(pos + 2))) {
                  pos += 2;
                  c = ccc;
          }
  
          /*
           * Read in contiguous digits until the first non-digit character.
           */
          for (; pos < end && c != '\0' && lisalnum(c) && (x = DIGIT(c)) < base;
              c = dtrace_load8(++pos))
                  val = val * base + x;
  
          return (neg ? -val : val);
  }
  
  /*
   * Compare two strings using safe loads.
   */
  static int
  dtrace_strncmp(char *s1, char *s2, size_t limit)
  {
          uint8_t c1, c2;
          volatile uint16_t *flags;
  
          if (s1 == s2 || limit == 0)
                  return (0);
  
          flags = (volatile uint16_t *)&cpu_core[curcpu].cpuc_dtrace_flags;
  
          do {
                  if (s1 == NULL) {
                          c1 = '\0';
                  } else {
                          c1 = dtrace_load8((uintptr_t)s1++);
                  }
  
                  if (s2 == NULL) {
                          c2 = '\0';
                  } else {
                          c2 = dtrace_load8((uintptr_t)s2++);
                  }
  
                  if (c1 != c2)
                          return (c1 - c2);
          } while (--limit && c1 != '\0' && !(*flags & CPU_DTRACE_FAULT));
  
          return (0);
  }
  
  /*
   * Compute strlen(s) for a string using safe memory accesses.  The additional
   * len parameter is used to specify a maximum length to ensure completion.
   */
  static size_t
  dtrace_strlen(const char *s, size_t lim)
  {
          uint_t len;
  
          for (len = 0; len != lim; len++) {
                  if (dtrace_load8((uintptr_t)s++) == '\0')
                          break;
          }
  
          return (len);
  }
  
  /*
   * Check if an address falls within a toxic region.
   */
  static int
  dtrace_istoxic(uintptr_t kaddr, size_t size)
  {
          uintptr_t taddr, tsize;
          int i;
  
          for (i = 0; i < dtrace_toxranges; i++) {
                  taddr = dtrace_toxrange[i].dtt_base;
                  tsize = dtrace_toxrange[i].dtt_limit - taddr;
  
                  if (kaddr - taddr < tsize) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                          cpu_core[curcpu].cpuc_dtrace_illval = kaddr;
                          return (1);
                  }
  
                  if (taddr - kaddr < size) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                          cpu_core[curcpu].cpuc_dtrace_illval = taddr;
                          return (1);
                  }
          }
  
          return (0);
  }
  
  /*
   * Copy src to dst using safe memory accesses.  The src is assumed to be unsafe
   * memory specified by the DIF program.  The dst is assumed to be safe memory
   * that we can store to directly because it is managed by DTrace.  As with
   * standard bcopy, overlapping copies are handled properly.
   */
  static void
  dtrace_bcopy(const void *src, void *dst, size_t len)
  {
          if (len != 0) {
                  uint8_t *s1 = dst;
                  const uint8_t *s2 = src;
  
                  if (s1 <= s2) {
                          do {
                                  *s1++ = dtrace_load8((uintptr_t)s2++);
                          } while (--len != 0);
                  } else {
                          s2 += len;
                          s1 += len;
  
                          do {
                                  *--s1 = dtrace_load8((uintptr_t)--s2);
                          } while (--len != 0);
                  }
          }
  }
  
  /*
   * Copy src to dst using safe memory accesses, up to either the specified
   * length, or the point that a nul byte is encountered.  The src is assumed to
   * be unsafe memory specified by the DIF program.  The dst is assumed to be
   * safe memory that we can store to directly because it is managed by DTrace.
   * Unlike dtrace_bcopy(), overlapping regions are not handled.
   */
  static void
  dtrace_strcpy(const void *src, void *dst, size_t len)
  {
          if (len != 0) {
                  uint8_t *s1 = dst, c;
                  const uint8_t *s2 = src;
  
                  do {
                          *s1++ = c = dtrace_load8((uintptr_t)s2++);
                  } while (--len != 0 && c != '\0');
          }
  }
  
  /*
   * Copy src to dst, deriving the size and type from the specified (BYREF)
   * variable type.  The src is assumed to be unsafe memory specified by the DIF
   * program.  The dst is assumed to be DTrace variable memory that is of the
   * specified type; we assume that we can store to directly.
   */
  static void
  dtrace_vcopy(void *src, void *dst, dtrace_diftype_t *type, size_t limit)
  {
          ASSERT(type->dtdt_flags & DIF_TF_BYREF);
  
          if (type->dtdt_kind == DIF_TYPE_STRING) {
                  dtrace_strcpy(src, dst, MIN(type->dtdt_size, limit));
          } else {
                  dtrace_bcopy(src, dst, MIN(type->dtdt_size, limit));
          }
  }
  
  /*
   * Compare s1 to s2 using safe memory accesses.  The s1 data is assumed to be
   * unsafe memory specified by the DIF program.  The s2 data is assumed to be
   * safe memory that we can access directly because it is managed by DTrace.
   */
  static int
  dtrace_bcmp(const void *s1, const void *s2, size_t len)
  {
          volatile uint16_t *flags;
  
          flags = (volatile uint16_t *)&cpu_core[curcpu].cpuc_dtrace_flags;
  
          if (s1 == s2)
                  return (0);
  
          if (s1 == NULL || s2 == NULL)
                  return (1);
  
          if (s1 != s2 && len != 0) {
                  const uint8_t *ps1 = s1;
                  const uint8_t *ps2 = s2;
  
                  do {
                          if (dtrace_load8((uintptr_t)ps1++) != *ps2++)
                                  return (1);
                  } while (--len != 0 && !(*flags & CPU_DTRACE_FAULT));
          }
          return (0);
  }
  
  /*
   * Zero the specified region using a simple byte-by-byte loop.  Note that this
   * is for safe DTrace-managed memory only.
   */
  static void
  dtrace_bzero(void *dst, size_t len)
  {
          uchar_t *cp;
  
          for (cp = dst; len != 0; len--)
                  *cp++ = 0;
  }
  
  static void
  dtrace_add_128(uint64_t *addend1, uint64_t *addend2, uint64_t *sum)
  {
          uint64_t result[2];
  
          result[0] = addend1[0] + addend2[0];
          result[1] = addend1[1] + addend2[1] +
              (result[0] < addend1[0] || result[0] < addend2[0] ? 1 : 0);
  
          sum[0] = result[0];
          sum[1] = result[1];
  }
  
  /*
   * Shift the 128-bit value in a by b. If b is positive, shift left.
   * If b is negative, shift right.
   */
  static void
  dtrace_shift_128(uint64_t *a, int b)
  {
          uint64_t mask;
  
          if (b == 0)
                  return;
  
          if (b < 0) {
                  b = -b;
                  if (b >= 64) {
                          a[0] = a[1] >> (b - 64);
                          a[1] = 0;
                  } else {
                          a[0] >>= b;
                          mask = 1LL << (64 - b);
                          mask -= 1;
                          a[0] |= ((a[1] & mask) << (64 - b));
                          a[1] >>= b;
                  }
          } else {
                  if (b >= 64) {
                          a[1] = a[0] << (b - 64);
                          a[0] = 0;
                  } else {
                          a[1] <<= b;
                          mask = a[0] >> (64 - b);
                          a[1] |= mask;
                          a[0] <<= b;
                  }
          }
  }
  
  /*
   * The basic idea is to break the 2 64-bit values into 4 32-bit values,
   * use native multiplication on those, and then re-combine into the
   * resulting 128-bit value.
   *
   * (hi1 << 32 + lo1) * (hi2 << 32 + lo2) =
   *     hi1 * hi2 << 64 +
   *     hi1 * lo2 << 32 +
   *     hi2 * lo1 << 32 +
   *     lo1 * lo2
   */
  static void
  dtrace_multiply_128(uint64_t factor1, uint64_t factor2, uint64_t *product)
  {
          uint64_t hi1, hi2, lo1, lo2;
          uint64_t tmp[2];
  
          hi1 = factor1 >> 32;
          hi2 = factor2 >> 32;
  
          lo1 = factor1 & DT_MASK_LO;
          lo2 = factor2 & DT_MASK_LO;
  
          product[0] = lo1 * lo2;
          product[1] = hi1 * hi2;
  
          tmp[0] = hi1 * lo2;
          tmp[1] = 0;
          dtrace_shift_128(tmp, 32);
          dtrace_add_128(product, tmp, product);
  
          tmp[0] = hi2 * lo1;
          tmp[1] = 0;
          dtrace_shift_128(tmp, 32);
          dtrace_add_128(product, tmp, product);
  }
  
  /*
   * This privilege check should be used by actions and subroutines to
   * verify that the user credentials of the process that enabled the
   * invoking ECB match the target credentials
   */
  static int
  dtrace_priv_proc_common_user(dtrace_state_t *state)
  {
          cred_t *cr, *s_cr = state->dts_cred.dcr_cred;
  
          /*
           * We should always have a non-NULL state cred here, since if cred
           * is null (anonymous tracing), we fast-path bypass this routine.
           */
          ASSERT(s_cr != NULL);
  
          if ((cr = CRED()) != NULL &&
              s_cr->cr_uid == cr->cr_uid &&
              s_cr->cr_uid == cr->cr_ruid &&
              s_cr->cr_uid == cr->cr_suid &&
              s_cr->cr_gid == cr->cr_gid &&
              s_cr->cr_gid == cr->cr_rgid &&
              s_cr->cr_gid == cr->cr_sgid)
                  return (1);
  
          return (0);
  }
  
  /*
   * This privilege check should be used by actions and subroutines to
   * verify that the zone of the process that enabled the invoking ECB
   * matches the target credentials
   */
  static int
  dtrace_priv_proc_common_zone(dtrace_state_t *state)
  {
  #ifdef illumos
          cred_t *cr, *s_cr = state->dts_cred.dcr_cred;
  
          /*
           * We should always have a non-NULL state cred here, since if cred
           * is null (anonymous tracing), we fast-path bypass this routine.
           */
          ASSERT(s_cr != NULL);
  
          if ((cr = CRED()) != NULL && s_cr->cr_zone == cr->cr_zone)
                  return (1);
  
          return (0);
  #else
          return (1);
  #endif
  }
  
  /*
   * This privilege check should be used by actions and subroutines to
   * verify that the process has not setuid or changed credentials.
   */
  static int
  dtrace_priv_proc_common_nocd(void)
  {
          proc_t *proc;
  
          if ((proc = ttoproc(curthread)) != NULL &&
              !(proc->p_flag & SNOCD))
                  return (1);
  
          return (0);
  }
  
  static int
  dtrace_priv_proc_destructive(dtrace_state_t *state)
  {
          int action = state->dts_cred.dcr_action;
  
          if (((action & DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE) == 0) &&
              dtrace_priv_proc_common_zone(state) == 0)
                  goto bad;
  
          if (((action & DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER) == 0) &&
              dtrace_priv_proc_common_user(state) == 0)
                  goto bad;
  
          if (((action & DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG) == 0) &&
              dtrace_priv_proc_common_nocd() == 0)
                  goto bad;
  
          return (1);
  
  bad:
          cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_UPRIV;
  
          return (0);
  }
  
  static int
  dtrace_priv_proc_control(dtrace_state_t *state)
  {
          if (state->dts_cred.dcr_action & DTRACE_CRA_PROC_CONTROL)
                  return (1);
  
          if (dtrace_priv_proc_common_zone(state) &&
              dtrace_priv_proc_common_user(state) &&
              dtrace_priv_proc_common_nocd())
                  return (1);
  
          cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_UPRIV;
  
          return (0);
  }
  
  static int
  dtrace_priv_proc(dtrace_state_t *state)
  {
          if (state->dts_cred.dcr_action & DTRACE_CRA_PROC)
                  return (1);
  
          cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_UPRIV;
  
          return (0);
  }
  
  static int
  dtrace_priv_kernel(dtrace_state_t *state)
  {
          if (state->dts_cred.dcr_action & DTRACE_CRA_KERNEL)
                  return (1);
  
          cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_KPRIV;
  
          return (0);
  }
  
  static int
  dtrace_priv_kernel_destructive(dtrace_state_t *state)
  {
          if (state->dts_cred.dcr_action & DTRACE_CRA_KERNEL_DESTRUCTIVE)
                  return (1);
  
          cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_KPRIV;
  
          return (0);
  }
  
  /*
   * Determine if the dte_cond of the specified ECB allows for processing of
   * the current probe to continue.  Note that this routine may allow continued
   * processing, but with access(es) stripped from the mstate's dtms_access
   * field.
   */
  static int
  dtrace_priv_probe(dtrace_state_t *state, dtrace_mstate_t *mstate,
      dtrace_ecb_t *ecb)
  {
          dtrace_probe_t *probe = ecb->dte_probe;
          dtrace_provider_t *prov = probe->dtpr_provider;
          dtrace_pops_t *pops = &prov->dtpv_pops;
          int mode = DTRACE_MODE_NOPRIV_DROP;
  
          ASSERT(ecb->dte_cond);
  
  #ifdef illumos
          if (pops->dtps_mode != NULL) {
                  mode = pops->dtps_mode(prov->dtpv_arg,
                      probe->dtpr_id, probe->dtpr_arg);
  
                  ASSERT((mode & DTRACE_MODE_USER) ||
                      (mode & DTRACE_MODE_KERNEL));
                  ASSERT((mode & DTRACE_MODE_NOPRIV_RESTRICT) ||
                      (mode & DTRACE_MODE_NOPRIV_DROP));
          }
  
          /*
           * If the dte_cond bits indicate that this consumer is only allowed to
           * see user-mode firings of this probe, call the provider's dtps_mode()
           * entry point to check that the probe was fired while in a user
           * context.  If that's not the case, use the policy specified by the
           * provider to determine if we drop the probe or merely restrict
           * operation.
           */
          if (ecb->dte_cond & DTRACE_COND_USERMODE) {
                  ASSERT(mode != DTRACE_MODE_NOPRIV_DROP);
  
                  if (!(mode & DTRACE_MODE_USER)) {
                          if (mode & DTRACE_MODE_NOPRIV_DROP)
                                  return (0);
  
                          mstate->dtms_access &= ~DTRACE_ACCESS_ARGS;
                  }
          }
  #endif
  
          /*
           * This is more subtle than it looks. We have to be absolutely certain
           * that CRED() isn't going to change out from under us so it's only
           * legit to examine that structure if we're in constrained situations.
           * Currently, the only times we'll this check is if a non-super-user
           * has enabled the profile or syscall providers -- providers that
           * allow visibility of all processes. For the profile case, the check
           * above will ensure that we're examining a user context.
           */
          if (ecb->dte_cond & DTRACE_COND_OWNER) {
                  cred_t *cr;
                  cred_t *s_cr = state->dts_cred.dcr_cred;
                  proc_t *proc;
  
                  ASSERT(s_cr != NULL);
  
                  if ((cr = CRED()) == NULL ||
                      s_cr->cr_uid != cr->cr_uid ||
                      s_cr->cr_uid != cr->cr_ruid ||
                      s_cr->cr_uid != cr->cr_suid ||
                      s_cr->cr_gid != cr->cr_gid ||
                      s_cr->cr_gid != cr->cr_rgid ||
                      s_cr->cr_gid != cr->cr_sgid ||
                      (proc = ttoproc(curthread)) == NULL ||
                      (proc->p_flag & SNOCD)) {
                          if (mode & DTRACE_MODE_NOPRIV_DROP)
                                  return (0);
  
  #ifdef illumos
                          mstate->dtms_access &= ~DTRACE_ACCESS_PROC;
  #endif
                  }
          }
  
  #ifdef illumos
          /*
           * If our dte_cond is set to DTRACE_COND_ZONEOWNER and we are not
           * in our zone, check to see if our mode policy is to restrict rather
           * than to drop; if to restrict, strip away both DTRACE_ACCESS_PROC
           * and DTRACE_ACCESS_ARGS
           */
          if (ecb->dte_cond & DTRACE_COND_ZONEOWNER) {
                  cred_t *cr;
                  cred_t *s_cr = state->dts_cred.dcr_cred;
  
                  ASSERT(s_cr != NULL);
  
                  if ((cr = CRED()) == NULL ||
                      s_cr->cr_zone->zone_id != cr->cr_zone->zone_id) {
                          if (mode & DTRACE_MODE_NOPRIV_DROP)
                                  return (0);
  
                          mstate->dtms_access &=
                              ~(DTRACE_ACCESS_PROC | DTRACE_ACCESS_ARGS);
                  }
          }
  #endif
  
          return (1);
  }
  
  /*
   * Note:  not called from probe context.  This function is called
   * asynchronously (and at a regular interval) from outside of probe context to
   * clean the dirty dynamic variable lists on all CPUs.  Dynamic variable
   * cleaning is explained in detail in <sys/dtrace_impl.h>.
   */
  void
  dtrace_dynvar_clean(dtrace_dstate_t *dstate)
  {
          dtrace_dynvar_t *dirty;
          dtrace_dstate_percpu_t *dcpu;
          dtrace_dynvar_t **rinsep;
          int i, j, work = 0;
  
          for (i = 0; i < NCPU; i++) {
                  dcpu = &dstate->dtds_percpu[i];
                  rinsep = &dcpu->dtdsc_rinsing;
  
                  /*
                   * If the dirty list is NULL, there is no dirty work to do.
                   */
                  if (dcpu->dtdsc_dirty == NULL)
                          continue;
  
                  if (dcpu->dtdsc_rinsing != NULL) {
                          /*
                           * If the rinsing list is non-NULL, then it is because
                           * this CPU was selected to accept another CPU's
                           * dirty list -- and since that time, dirty buffers
                           * have accumulated.  This is a highly unlikely
                           * condition, but we choose to ignore the dirty
                           * buffers -- they'll be picked up a future cleanse.
                           */
                          continue;
                  }
  
                  if (dcpu->dtdsc_clean != NULL) {
                          /*
                           * If the clean list is non-NULL, then we're in a
                           * situation where a CPU has done deallocations (we
                           * have a non-NULL dirty list) but no allocations (we
                           * also have a non-NULL clean list).  We can't simply
                           * move the dirty list into the clean list on this
                           * CPU, yet we also don't want to allow this condition
                           * to persist, lest a short clean list prevent a
                           * massive dirty list from being cleaned (which in
                           * turn could lead to otherwise avoidable dynamic
                           * drops).  To deal with this, we look for some CPU
                           * with a NULL clean list, NULL dirty list, and NULL
                           * rinsing list -- and then we borrow this CPU to
                           * rinse our dirty list.
                           */
                          for (j = 0; j < NCPU; j++) {
                                  dtrace_dstate_percpu_t *rinser;
  
                                  rinser = &dstate->dtds_percpu[j];
  
                                  if (rinser->dtdsc_rinsing != NULL)
                                          continue;
  
                                  if (rinser->dtdsc_dirty != NULL)
                                          continue;
  
                                  if (rinser->dtdsc_clean != NULL)
                                          continue;
  
                                  rinsep = &rinser->dtdsc_rinsing;
                                  break;
                          }
  
                          if (j == NCPU) {
                                  /*
                                   * We were unable to find another CPU that
                                   * could accept this dirty list -- we are
                                   * therefore unable to clean it now.
                                   */
                                  dtrace_dynvar_failclean++;
                                  continue;
                          }
                  }
  
                  work = 1;
  
                  /*
                   * Atomically move the dirty list aside.
                   */
                  do {
                          dirty = dcpu->dtdsc_dirty;
  
                          /*
                           * Before we zap the dirty list, set the rinsing list.
                           * (This allows for a potential assertion in
                           * dtrace_dynvar():  if a free dynamic variable appears
                           * on a hash chain, either the dirty list or the
                           * rinsing list for some CPU must be non-NULL.)
                           */
                          *rinsep = dirty;
                          dtrace_membar_producer();
                  } while (dtrace_casptr(&dcpu->dtdsc_dirty,
                      dirty, NULL) != dirty);
          }
  
          if (!work) {
                  /*
                   * We have no work to do; we can simply return.
                   */
                  return;
          }
  
          dtrace_sync();
  
          for (i = 0; i < NCPU; i++) {
                  dcpu = &dstate->dtds_percpu[i];
  
                  if (dcpu->dtdsc_rinsing == NULL)
                          continue;
  
                  /*
                   * We are now guaranteed that no hash chain contains a pointer
                   * into this dirty list; we can make it clean.
                   */
                  ASSERT(dcpu->dtdsc_clean == NULL);
                  dcpu->dtdsc_clean = dcpu->dtdsc_rinsing;
                  dcpu->dtdsc_rinsing = NULL;
          }
  
          /*
           * Before we actually set the state to be DTRACE_DSTATE_CLEAN, make
           * sure that all CPUs have seen all of the dtdsc_clean pointers.
           * This prevents a race whereby a CPU incorrectly decides that
           * the state should be something other than DTRACE_DSTATE_CLEAN
           * after dtrace_dynvar_clean() has completed.
           */
          dtrace_sync();
  
          dstate->dtds_state = DTRACE_DSTATE_CLEAN;
  }
  
  /*
   * Depending on the value of the op parameter, this function looks-up,
   * allocates or deallocates an arbitrarily-keyed dynamic variable.  If an
   * allocation is requested, this function will return a pointer to a
   * dtrace_dynvar_t corresponding to the allocated variable -- or NULL if no
   * variable can be allocated.  If NULL is returned, the appropriate counter
   * will be incremented.
   */
  dtrace_dynvar_t *
  dtrace_dynvar(dtrace_dstate_t *dstate, uint_t nkeys,
      dtrace_key_t *key, size_t dsize, dtrace_dynvar_op_t op,
      dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
  {
          uint64_t hashval = DTRACE_DYNHASH_VALID;
          dtrace_dynhash_t *hash = dstate->dtds_hash;
          dtrace_dynvar_t *free, *new_free, *next, *dvar, *start, *prev = NULL;
          processorid_t me = curcpu, cpu = me;
          dtrace_dstate_percpu_t *dcpu = &dstate->dtds_percpu[me];
          size_t bucket, ksize;
          size_t chunksize = dstate->dtds_chunksize;
          uintptr_t kdata, lock, nstate;
          uint_t i;
  
          ASSERT(nkeys != 0);
  
          /*
           * Hash the key.  As with aggregations, we use Jenkins' "One-at-a-time"
           * algorithm.  For the by-value portions, we perform the algorithm in
           * 16-bit chunks (as opposed to 8-bit chunks).  This speeds things up a
           * bit, and seems to have only a minute effect on distribution.  For
           * the by-reference data, we perform "One-at-a-time" iterating (safely)
           * over each referenced byte.  It's painful to do this, but it's much
           * better than pathological hash distribution.  The efficacy of the
           * hashing algorithm (and a comparison with other algorithms) may be
           * found by running the ::dtrace_dynstat MDB dcmd.
           */
          for (i = 0; i < nkeys; i++) {
                  if (key[i].dttk_size == 0) {
                          uint64_t val = key[i].dttk_value;
  
                          hashval += (val >> 48) & 0xffff;
                          hashval += (hashval << 10);
                          hashval ^= (hashval >> 6);
  
                          hashval += (val >> 32) & 0xffff;
                          hashval += (hashval << 10);
                          hashval ^= (hashval >> 6);
  
                          hashval += (val >> 16) & 0xffff;
                          hashval += (hashval << 10);
                          hashval ^= (hashval >> 6);
  
                          hashval += val & 0xffff;
                          hashval += (hashval << 10);
                          hashval ^= (hashval >> 6);
                  } else {
                          /*
                           * This is incredibly painful, but it beats the hell
                           * out of the alternative.
                           */
                          uint64_t j, size = key[i].dttk_size;
                          uintptr_t base = (uintptr_t)key[i].dttk_value;
  
                          if (!dtrace_canload(base, size, mstate, vstate))
                                  break;
  
                          for (j = 0; j < size; j++) {
                                  hashval += dtrace_load8(base + j);
                                  hashval += (hashval << 10);
                                  hashval ^= (hashval >> 6);
                          }
                  }
          }
  
          if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_FAULT))
                  return (NULL);
  
          hashval += (hashval << 3);
          hashval ^= (hashval >> 11);
          hashval += (hashval << 15);
  
          /*
           * There is a remote chance (ideally, 1 in 2^31) that our hashval
           * comes out to be one of our two sentinel hash values.  If this
           * actually happens, we set the hashval to be a value known to be a
           * non-sentinel value.
           */
          if (hashval == DTRACE_DYNHASH_FREE || hashval == DTRACE_DYNHASH_SINK)
                  hashval = DTRACE_DYNHASH_VALID;
  
          /*
           * Yes, it's painful to do a divide here.  If the cycle count becomes
           * important here, tricks can be pulled to reduce it.  (However, it's
           * critical that hash collisions be kept to an absolute minimum;
           * they're much more painful than a divide.)  It's better to have a
           * solution that generates few collisions and still keeps things
           * relatively simple.
           */
          bucket = hashval % dstate->dtds_hashsize;
  
          if (op == DTRACE_DYNVAR_DEALLOC) {
                  volatile uintptr_t *lockp = &hash[bucket].dtdh_lock;
  
                  for (;;) {
                          while ((lock = *lockp) & 1)
                                  continue;
  
                          if (dtrace_casptr((volatile void *)lockp,
                              (volatile void *)lock, (volatile void *)(lock + 1)) == (void *)lock)
                                  break;
                  }
  
                  dtrace_membar_producer();
          }
  
  top:
          prev = NULL;
          lock = hash[bucket].dtdh_lock;
  
          dtrace_membar_consumer();
  
          start = hash[bucket].dtdh_chain;
          ASSERT(start != NULL && (start->dtdv_hashval == DTRACE_DYNHASH_SINK ||
              start->dtdv_hashval != DTRACE_DYNHASH_FREE ||
              op != DTRACE_DYNVAR_DEALLOC));
  
          for (dvar = start; dvar != NULL; dvar = dvar->dtdv_next) {
                  dtrace_tuple_t *dtuple = &dvar->dtdv_tuple;
                  dtrace_key_t *dkey = &dtuple->dtt_key[0];
  
                  if (dvar->dtdv_hashval != hashval) {
                          if (dvar->dtdv_hashval == DTRACE_DYNHASH_SINK) {
                                  /*
                                   * We've reached the sink, and therefore the
                                   * end of the hash chain; we can kick out of
                                   * the loop knowing that we have seen a valid
                                   * snapshot of state.
                                   */
                                  ASSERT(dvar->dtdv_next == NULL);
                                  ASSERT(dvar == &dtrace_dynhash_sink);
                                  break;
                          }
  
                          if (dvar->dtdv_hashval == DTRACE_DYNHASH_FREE) {
                                  /*
                                   * We've gone off the rails:  somewhere along
                                   * the line, one of the members of this hash
                                   * chain was deleted.  Note that we could also
                                   * detect this by simply letting this loop run
                                   * to completion, as we would eventually hit
                                   * the end of the dirty list.  However, we
                                   * want to avoid running the length of the
                                   * dirty list unnecessarily (it might be quite
                                   * long), so we catch this as early as
                                   * possible by detecting the hash marker.  In
                                   * this case, we simply set dvar to NULL and
                                   * break; the conditional after the loop will
                                   * send us back to top.
                                   */
                                  dvar = NULL;
                                  break;
                          }
  
                          goto next;
                  }
  
                  if (dtuple->dtt_nkeys != nkeys)
                          goto next;
  
                  for (i = 0; i < nkeys; i++, dkey++) {
                          if (dkey->dttk_size != key[i].dttk_size)
                                  goto next; /* size or type mismatch */
  
                          if (dkey->dttk_size != 0) {
                                  if (dtrace_bcmp(
                                      (void *)(uintptr_t)key[i].dttk_value,
                                      (void *)(uintptr_t)dkey->dttk_value,
                                      dkey->dttk_size))
                                          goto next;
                          } else {
                                  if (dkey->dttk_value != key[i].dttk_value)
                                          goto next;
                          }
                  }
  
                  if (op != DTRACE_DYNVAR_DEALLOC)
                          return (dvar);
  
                  ASSERT(dvar->dtdv_next == NULL ||
                      dvar->dtdv_next->dtdv_hashval != DTRACE_DYNHASH_FREE);
  
                  if (prev != NULL) {
                          ASSERT(hash[bucket].dtdh_chain != dvar);
                          ASSERT(start != dvar);
                          ASSERT(prev->dtdv_next == dvar);
                          prev->dtdv_next = dvar->dtdv_next;
                  } else {
                          if (dtrace_casptr(&hash[bucket].dtdh_chain,
                              start, dvar->dtdv_next) != start) {
                                  /*
                                   * We have failed to atomically swing the
                                   * hash table head pointer, presumably because
                                   * of a conflicting allocation on another CPU.
                                   * We need to reread the hash chain and try
                                   * again.
                                   */
                                  goto top;
                          }
                  }
  
                  dtrace_membar_producer();
  
                  /*
                   * Now set the hash value to indicate that it's free.
                   */
                  ASSERT(hash[bucket].dtdh_chain != dvar);
                  dvar->dtdv_hashval = DTRACE_DYNHASH_FREE;
  
                  dtrace_membar_producer();
  
                  /*
                   * Set the next pointer to point at the dirty list, and
                   * atomically swing the dirty pointer to the newly freed dvar.
                   */
                  do {
                          next = dcpu->dtdsc_dirty;
                          dvar->dtdv_next = next;
                  } while (dtrace_casptr(&dcpu->dtdsc_dirty, next, dvar) != next);
  
                  /*
                   * Finally, unlock this hash bucket.
                   */
                  ASSERT(hash[bucket].dtdh_lock == lock);
                  ASSERT(lock & 1);
                  hash[bucket].dtdh_lock++;
  
                  return (NULL);
  next:
                  prev = dvar;
                  continue;
          }
  
          if (dvar == NULL) {
                  /*
                   * If dvar is NULL, it is because we went off the rails:
                   * one of the elements that we traversed in the hash chain
                   * was deleted while we were traversing it.  In this case,
                   * we assert that we aren't doing a dealloc (deallocs lock
                   * the hash bucket to prevent themselves from racing with
                   * one another), and retry the hash chain traversal.
                   */
                  ASSERT(op != DTRACE_DYNVAR_DEALLOC);
                  goto top;
          }
  
          if (op != DTRACE_DYNVAR_ALLOC) {
                  /*
                   * If we are not to allocate a new variable, we want to
                   * return NULL now.  Before we return, check that the value
                   * of the lock word hasn't changed.  If it has, we may have
                   * seen an inconsistent snapshot.
                   */
                  if (op == DTRACE_DYNVAR_NOALLOC) {
                          if (hash[bucket].dtdh_lock != lock)
                                  goto top;
                  } else {
                          ASSERT(op == DTRACE_DYNVAR_DEALLOC);
                          ASSERT(hash[bucket].dtdh_lock == lock);
                          ASSERT(lock & 1);
                          hash[bucket].dtdh_lock++;
                  }
  
                  return (NULL);
          }
  
          /*
           * We need to allocate a new dynamic variable.  The size we need is the
           * size of dtrace_dynvar plus the size of nkeys dtrace_key_t's plus the
           * size of any auxiliary key data (rounded up to 8-byte alignment) plus
           * the size of any referred-to data (dsize).  We then round the final
           * size up to the chunksize for allocation.
           */
          for (ksize = 0, i = 0; i < nkeys; i++)
                  ksize += P2ROUNDUP(key[i].dttk_size, sizeof (uint64_t));
  
          /*
           * This should be pretty much impossible, but could happen if, say,
           * strange DIF specified the tuple.  Ideally, this should be an
           * assertion and not an error condition -- but that requires that the
           * chunksize calculation in dtrace_difo_chunksize() be absolutely
           * bullet-proof.  (That is, it must not be able to be fooled by
           * malicious DIF.)  Given the lack of backwards branches in DIF,
           * solving this would presumably not amount to solving the Halting
           * Problem -- but it still seems awfully hard.
           */
          if (sizeof (dtrace_dynvar_t) + sizeof (dtrace_key_t) * (nkeys - 1) +
              ksize + dsize > chunksize) {
                  dcpu->dtdsc_drops++;
                  return (NULL);
          }
  
          nstate = DTRACE_DSTATE_EMPTY;
  
          do {
  retry:
                  free = dcpu->dtdsc_free;
  
                  if (free == NULL) {
                          dtrace_dynvar_t *clean = dcpu->dtdsc_clean;
                          void *rval;
  
                          if (clean == NULL) {
                                  /*
                                   * We're out of dynamic variable space on
                                   * this CPU.  Unless we have tried all CPUs,
                                   * we'll try to allocate from a different
                                   * CPU.
                                   */
                                  switch (dstate->dtds_state) {
                                  case DTRACE_DSTATE_CLEAN: {
                                          void *sp = &dstate->dtds_state;
  
                                          if (++cpu >= NCPU)
                                                  cpu = 0;
  
                                          if (dcpu->dtdsc_dirty != NULL &&
                                              nstate == DTRACE_DSTATE_EMPTY)
                                                  nstate = DTRACE_DSTATE_DIRTY;
  
                                          if (dcpu->dtdsc_rinsing != NULL)
                                                  nstate = DTRACE_DSTATE_RINSING;
  
                                          dcpu = &dstate->dtds_percpu[cpu];
  
                                          if (cpu != me)
                                                  goto retry;
  
                                          (void) dtrace_cas32(sp,
                                              DTRACE_DSTATE_CLEAN, nstate);
  
                                          /*
                                           * To increment the correct bean
                                           * counter, take another lap.
                                           */
                                          goto retry;
                                  }
  
                                  case DTRACE_DSTATE_DIRTY:
                                          dcpu->dtdsc_dirty_drops++;
                                          break;
  
                                  case DTRACE_DSTATE_RINSING:
                                          dcpu->dtdsc_rinsing_drops++;
                                          break;
  
                                  case DTRACE_DSTATE_EMPTY:
                                          dcpu->dtdsc_drops++;
                                          break;
                                  }
  
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_DROP);
                                  return (NULL);
                          }
  
                          /*
                           * The clean list appears to be non-empty.  We want to
                           * move the clean list to the free list; we start by
                           * moving the clean pointer aside.
                           */
                          if (dtrace_casptr(&dcpu->dtdsc_clean,
                              clean, NULL) != clean) {
                                  /*
                                   * We are in one of two situations:
                                   *
                                   *  (a) The clean list was switched to the
                                   *      free list by another CPU.
                                   *
                                   *  (b) The clean list was added to by the
                                   *      cleansing cyclic.
                                   *
                                   * In either of these situations, we can
                                   * just reattempt the free list allocation.
                                   */
                                  goto retry;
                          }
  
                          ASSERT(clean->dtdv_hashval == DTRACE_DYNHASH_FREE);
  
                          /*
                           * Now we'll move the clean list to our free list.
                           * It's impossible for this to fail:  the only way
                           * the free list can be updated is through this
                           * code path, and only one CPU can own the clean list.
                           * Thus, it would only be possible for this to fail if
                           * this code were racing with dtrace_dynvar_clean().
                           * (That is, if dtrace_dynvar_clean() updated the clean
                           * list, and we ended up racing to update the free
                           * list.)  This race is prevented by the dtrace_sync()
                           * in dtrace_dynvar_clean() -- which flushes the
                           * owners of the clean lists out before resetting
                           * the clean lists.
                           */
                          dcpu = &dstate->dtds_percpu[me];
                          rval = dtrace_casptr(&dcpu->dtdsc_free, NULL, clean);
                          ASSERT(rval == NULL);
                          goto retry;
                  }
  
                  dvar = free;
                  new_free = dvar->dtdv_next;
          } while (dtrace_casptr(&dcpu->dtdsc_free, free, new_free) != free);
  
          /*
           * We have now allocated a new chunk.  We copy the tuple keys into the
           * tuple array and copy any referenced key data into the data space
           * following the tuple array.  As we do this, we relocate dttk_value
           * in the final tuple to point to the key data address in the chunk.
           */
          kdata = (uintptr_t)&dvar->dtdv_tuple.dtt_key[nkeys];
          dvar->dtdv_data = (void *)(kdata + ksize);
          dvar->dtdv_tuple.dtt_nkeys = nkeys;
  
          for (i = 0; i < nkeys; i++) {
                  dtrace_key_t *dkey = &dvar->dtdv_tuple.dtt_key[i];
                  size_t kesize = key[i].dttk_size;
  
                  if (kesize != 0) {
                          dtrace_bcopy(
                              (const void *)(uintptr_t)key[i].dttk_value,
                              (void *)kdata, kesize);
                          dkey->dttk_value = kdata;
                          kdata += P2ROUNDUP(kesize, sizeof (uint64_t));
                  } else {
                          dkey->dttk_value = key[i].dttk_value;
                  }
  
                  dkey->dttk_size = kesize;
          }
  
          ASSERT(dvar->dtdv_hashval == DTRACE_DYNHASH_FREE);
          dvar->dtdv_hashval = hashval;
          dvar->dtdv_next = start;
  
          if (dtrace_casptr(&hash[bucket].dtdh_chain, start, dvar) == start)
                  return (dvar);
  
          /*
           * The cas has failed.  Either another CPU is adding an element to
           * this hash chain, or another CPU is deleting an element from this
           * hash chain.  The simplest way to deal with both of these cases
           * (though not necessarily the most efficient) is to free our
           * allocated block and re-attempt it all.  Note that the free is
           * to the dirty list and _not_ to the free list.  This is to prevent
           * races with allocators, above.
           */
          dvar->dtdv_hashval = DTRACE_DYNHASH_FREE;
  
          dtrace_membar_producer();
  
          do {
                  free = dcpu->dtdsc_dirty;
                  dvar->dtdv_next = free;
          } while (dtrace_casptr(&dcpu->dtdsc_dirty, free, dvar) != free);
  
          goto top;
  }
  
  /*ARGSUSED*/
  static void
  dtrace_aggregate_min(uint64_t *oval, uint64_t nval, uint64_t arg)
  {
          if ((int64_t)nval < (int64_t)*oval)
                  *oval = nval;
  }
  
  /*ARGSUSED*/
  static void
  dtrace_aggregate_max(uint64_t *oval, uint64_t nval, uint64_t arg)
  {
          if ((int64_t)nval > (int64_t)*oval)
                  *oval = nval;
  }
  
  static void
  dtrace_aggregate_quantize(uint64_t *quanta, uint64_t nval, uint64_t incr)
  {
          int i, zero = DTRACE_QUANTIZE_ZEROBUCKET;
          int64_t val = (int64_t)nval;
  
          if (val < 0) {
                  for (i = 0; i < zero; i++) {
                          if (val <= DTRACE_QUANTIZE_BUCKETVAL(i)) {
                                  quanta[i] += incr;
                                  return;
                          }
                  }
          } else {
                  for (i = zero + 1; i < DTRACE_QUANTIZE_NBUCKETS; i++) {
                          if (val < DTRACE_QUANTIZE_BUCKETVAL(i)) {
                                  quanta[i - 1] += incr;
                                  return;
                          }
                  }
  
                  quanta[DTRACE_QUANTIZE_NBUCKETS - 1] += incr;
                  return;
          }
  
          ASSERT(0);
  }
  
  static void
  dtrace_aggregate_lquantize(uint64_t *lquanta, uint64_t nval, uint64_t incr)
  {
          uint64_t arg = *lquanta++;
          int32_t base = DTRACE_LQUANTIZE_BASE(arg);
          uint16_t step = DTRACE_LQUANTIZE_STEP(arg);
          uint16_t levels = DTRACE_LQUANTIZE_LEVELS(arg);
          int32_t val = (int32_t)nval, level;
  
          ASSERT(step != 0);
          ASSERT(levels != 0);
  
          if (val < base) {
                  /*
                   * This is an underflow.
                   */
                  lquanta[0] += incr;
                  return;
          }
  
          level = (val - base) / step;
  
          if (level < levels) {
                  lquanta[level + 1] += incr;
                  return;
          }
  
          /*
           * This is an overflow.
           */
          lquanta[levels + 1] += incr;
  }
  
  static int
  dtrace_aggregate_llquantize_bucket(uint16_t factor, uint16_t low,
      uint16_t high, uint16_t nsteps, int64_t value)
  {
          int64_t this = 1, last, next;
          int base = 1, order;
  
          ASSERT(factor <= nsteps);
          ASSERT(nsteps % factor == 0);
  
          for (order = 0; order < low; order++)
                  this *= factor;
  
          /*
           * If our value is less than our factor taken to the power of the
           * low order of magnitude, it goes into the zeroth bucket.
           */
          if (value < (last = this))
                  return (0);
  
          for (this *= factor; order <= high; order++) {
                  int nbuckets = this > nsteps ? nsteps : this;
  
                  if ((next = this * factor) < this) {
                          /*
                           * We should not generally get log/linear quantizations
                           * with a high magnitude that allows 64-bits to
                           * overflow, but we nonetheless protect against this
                           * by explicitly checking for overflow, and clamping
                           * our value accordingly.
                           */
                          value = this - 1;
                  }
  
                  if (value < this) {
                          /*
                           * If our value lies within this order of magnitude,
                           * determine its position by taking the offset within
                           * the order of magnitude, dividing by the bucket
                           * width, and adding to our (accumulated) base.
                           */
                          return (base + (value - last) / (this / nbuckets));
                  }
  
                  base += nbuckets - (nbuckets / factor);
                  last = this;
                  this = next;
          }
  
          /*
           * Our value is greater than or equal to our factor taken to the
           * power of one plus the high magnitude -- return the top bucket.
           */
          return (base);
  }
  
  static void
  dtrace_aggregate_llquantize(uint64_t *llquanta, uint64_t nval, uint64_t incr)
  {
          uint64_t arg = *llquanta++;
          uint16_t factor = DTRACE_LLQUANTIZE_FACTOR(arg);
          uint16_t low = DTRACE_LLQUANTIZE_LOW(arg);
          uint16_t high = DTRACE_LLQUANTIZE_HIGH(arg);
          uint16_t nsteps = DTRACE_LLQUANTIZE_NSTEP(arg);
  
          llquanta[dtrace_aggregate_llquantize_bucket(factor,
              low, high, nsteps, nval)] += incr;
  }
  
  /*ARGSUSED*/
  static void
  dtrace_aggregate_avg(uint64_t *data, uint64_t nval, uint64_t arg)
  {
          data[0]++;
          data[1] += nval;
  }
  
  /*ARGSUSED*/
  static void
  dtrace_aggregate_stddev(uint64_t *data, uint64_t nval, uint64_t arg)
  {
          int64_t snval = (int64_t)nval;
          uint64_t tmp[2];
  
          data[0]++;
          data[1] += nval;
  
          /*
           * What we want to say here is:
           *
           * data[2] += nval * nval;
           *
           * But given that nval is 64-bit, we could easily overflow, so
           * we do this as 128-bit arithmetic.
           */
          if (snval < 0)
                  snval = -snval;
  
          dtrace_multiply_128((uint64_t)snval, (uint64_t)snval, tmp);
          dtrace_add_128(data + 2, tmp, data + 2);
  }
  
  /*ARGSUSED*/
  static void
  dtrace_aggregate_count(uint64_t *oval, uint64_t nval, uint64_t arg)
  {
          *oval = *oval + 1;
  }
  
  /*ARGSUSED*/
  static void
  dtrace_aggregate_sum(uint64_t *oval, uint64_t nval, uint64_t arg)
  {
          *oval += nval;
  }
  
  /*
   * Aggregate given the tuple in the principal data buffer, and the aggregating
   * action denoted by the specified dtrace_aggregation_t.  The aggregation
   * buffer is specified as the buf parameter.  This routine does not return
   * failure; if there is no space in the aggregation buffer, the data will be
   * dropped, and a corresponding counter incremented.
   */
  static void
  dtrace_aggregate(dtrace_aggregation_t *agg, dtrace_buffer_t *dbuf,
      intptr_t offset, dtrace_buffer_t *buf, uint64_t expr, uint64_t arg)
  {
          dtrace_recdesc_t *rec = &agg->dtag_action.dta_rec;
          uint32_t i, ndx, size, fsize;
          uint32_t align = sizeof (uint64_t) - 1;
          dtrace_aggbuffer_t *agb;
          dtrace_aggkey_t *key;
          uint32_t hashval = 0, limit, isstr;
          caddr_t tomax, data, kdata;
          dtrace_actkind_t action;
          dtrace_action_t *act;
          uintptr_t offs;
  
          if (buf == NULL)
                  return;
  
          if (!agg->dtag_hasarg) {
                  /*
                   * Currently, only quantize() and lquantize() take additional
                   * arguments, and they have the same semantics:  an increment
                   * value that defaults to 1 when not present.  If additional
                   * aggregating actions take arguments, the setting of the
                   * default argument value will presumably have to become more
                   * sophisticated...
                   */
                  arg = 1;
          }
  
          action = agg->dtag_action.dta_kind - DTRACEACT_AGGREGATION;
          size = rec->dtrd_offset - agg->dtag_base;
          fsize = size + rec->dtrd_size;
  
          ASSERT(dbuf->dtb_tomax != NULL);
          data = dbuf->dtb_tomax + offset + agg->dtag_base;
  
          if ((tomax = buf->dtb_tomax) == NULL) {
                  dtrace_buffer_drop(buf);
                  return;
          }
  
          /*
           * The metastructure is always at the bottom of the buffer.
           */
          agb = (dtrace_aggbuffer_t *)(tomax + buf->dtb_size -
              sizeof (dtrace_aggbuffer_t));
  
          if (buf->dtb_offset == 0) {
                  /*
                   * We just kludge up approximately 1/8th of the size to be
                   * buckets.  If this guess ends up being routinely
                   * off-the-mark, we may need to dynamically readjust this
                   * based on past performance.
                   */
                  uintptr_t hashsize = (buf->dtb_size >> 3) / sizeof (uintptr_t);
  
                  if ((uintptr_t)agb - hashsize * sizeof (dtrace_aggkey_t *) <
                      (uintptr_t)tomax || hashsize == 0) {
                          /*
                           * We've been given a ludicrously small buffer;
                           * increment our drop count and leave.
                           */
                          dtrace_buffer_drop(buf);
                          return;
                  }
  
                  /*
                   * And now, a pathetic attempt to try to get a an odd (or
                   * perchance, a prime) hash size for better hash distribution.
                   */
                  if (hashsize > (DTRACE_AGGHASHSIZE_SLEW << 3))
                          hashsize -= DTRACE_AGGHASHSIZE_SLEW;
  
                  agb->dtagb_hashsize = hashsize;
                  agb->dtagb_hash = (dtrace_aggkey_t **)((uintptr_t)agb -
                      agb->dtagb_hashsize * sizeof (dtrace_aggkey_t *));
                  agb->dtagb_free = (uintptr_t)agb->dtagb_hash;
  
                  for (i = 0; i < agb->dtagb_hashsize; i++)
                          agb->dtagb_hash[i] = NULL;
          }
  
          ASSERT(agg->dtag_first != NULL);
          ASSERT(agg->dtag_first->dta_intuple);
  
          /*
           * Calculate the hash value based on the key.  Note that we _don't_
           * include the aggid in the hashing (but we will store it as part of
           * the key).  The hashing algorithm is Bob Jenkins' "One-at-a-time"
           * algorithm: a simple, quick algorithm that has no known funnels, and
           * gets good distribution in practice.  The efficacy of the hashing
           * algorithm (and a comparison with other algorithms) may be found by
           * running the ::dtrace_aggstat MDB dcmd.
           */
          for (act = agg->dtag_first; act->dta_intuple; act = act->dta_next) {
                  i = act->dta_rec.dtrd_offset - agg->dtag_base;
                  limit = i + act->dta_rec.dtrd_size;
                  ASSERT(limit <= size);
                  isstr = DTRACEACT_ISSTRING(act);
  
                  for (; i < limit; i++) {
                          hashval += data[i];
                          hashval += (hashval << 10);
                          hashval ^= (hashval >> 6);
  
                          if (isstr && data[i] == '\0')
                                  break;
                  }
          }
  
          hashval += (hashval << 3);
          hashval ^= (hashval >> 11);
          hashval += (hashval << 15);
  
          /*
           * Yes, the divide here is expensive -- but it's generally the least
           * of the performance issues given the amount of data that we iterate
           * over to compute hash values, compare data, etc.
           */
          ndx = hashval % agb->dtagb_hashsize;
  
          for (key = agb->dtagb_hash[ndx]; key != NULL; key = key->dtak_next) {
                  ASSERT((caddr_t)key >= tomax);
                  ASSERT((caddr_t)key < tomax + buf->dtb_size);
  
                  if (hashval != key->dtak_hashval || key->dtak_size != size)
                          continue;
  
                  kdata = key->dtak_data;
                  ASSERT(kdata >= tomax && kdata < tomax + buf->dtb_size);
  
                  for (act = agg->dtag_first; act->dta_intuple;
                      act = act->dta_next) {
                          i = act->dta_rec.dtrd_offset - agg->dtag_base;
                          limit = i + act->dta_rec.dtrd_size;
                          ASSERT(limit <= size);
                          isstr = DTRACEACT_ISSTRING(act);
  
                          for (; i < limit; i++) {
                                  if (kdata[i] != data[i])
                                          goto next;
  
                                  if (isstr && data[i] == '\0')
                                          break;
                          }
                  }
  
                  if (action != key->dtak_action) {
                          /*
                           * We are aggregating on the same value in the same
                           * aggregation with two different aggregating actions.
                           * (This should have been picked up in the compiler,
                           * so we may be dealing with errant or devious DIF.)
                           * This is an error condition; we indicate as much,
                           * and return.
                           */
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                          return;
                  }
  
                  /*
                   * This is a hit:  we need to apply the aggregator to
                   * the value at this key.
                   */
                  agg->dtag_aggregate((uint64_t *)(kdata + size), expr, arg);
                  return;
  next:
                  continue;
          }
  
          /*
           * We didn't find it.  We need to allocate some zero-filled space,
           * link it into the hash table appropriately, and apply the aggregator
           * to the (zero-filled) value.
           */
          offs = buf->dtb_offset;
          while (offs & (align - 1))
                  offs += sizeof (uint32_t);
  
          /*
           * If we don't have enough room to both allocate a new key _and_
           * its associated data, increment the drop count and return.
           */
          if ((uintptr_t)tomax + offs + fsize >
              agb->dtagb_free - sizeof (dtrace_aggkey_t)) {
                  dtrace_buffer_drop(buf);
                  return;
          }
  
          /*CONSTCOND*/
          ASSERT(!(sizeof (dtrace_aggkey_t) & (sizeof (uintptr_t) - 1)));
          key = (dtrace_aggkey_t *)(agb->dtagb_free - sizeof (dtrace_aggkey_t));
          agb->dtagb_free -= sizeof (dtrace_aggkey_t);
  
          key->dtak_data = kdata = tomax + offs;
          buf->dtb_offset = offs + fsize;
  
          /*
           * Now copy the data across.
           */
          *((dtrace_aggid_t *)kdata) = agg->dtag_id;
  
          for (i = sizeof (dtrace_aggid_t); i < size; i++)
                  kdata[i] = data[i];
  
          /*
           * Because strings are not zeroed out by default, we need to iterate
           * looking for actions that store strings, and we need to explicitly
           * pad these strings out with zeroes.
           */
          for (act = agg->dtag_first; act->dta_intuple; act = act->dta_next) {
                  int nul;
  
                  if (!DTRACEACT_ISSTRING(act))
                          continue;
  
                  i = act->dta_rec.dtrd_offset - agg->dtag_base;
                  limit = i + act->dta_rec.dtrd_size;
                  ASSERT(limit <= size);
  
                  for (nul = 0; i < limit; i++) {
                          if (nul) {
                                  kdata[i] = '\0';
                                  continue;
                          }
  
                          if (data[i] != '\0')
                                  continue;
  
                          nul = 1;
                  }
          }
  
          for (i = size; i < fsize; i++)
                  kdata[i] = 0;
  
          key->dtak_hashval = hashval;
          key->dtak_size = size;
          key->dtak_action = action;
          key->dtak_next = agb->dtagb_hash[ndx];
          agb->dtagb_hash[ndx] = key;
  
          /*
           * Finally, apply the aggregator.
           */
          *((uint64_t *)(key->dtak_data + size)) = agg->dtag_initial;
          agg->dtag_aggregate((uint64_t *)(key->dtak_data + size), expr, arg);
  }
  
  /*
   * Given consumer state, this routine finds a speculation in the INACTIVE
   * state and transitions it into the ACTIVE state.  If there is no speculation
   * in the INACTIVE state, 0 is returned.  In this case, no error counter is
   * incremented -- it is up to the caller to take appropriate action.
   */
  static int
  dtrace_speculation(dtrace_state_t *state)
  {
          int i = 0;
          dtrace_speculation_state_t curstate;
          uint32_t *stat = &state->dts_speculations_unavail, count;
  
          while (i < state->dts_nspeculations) {
                  dtrace_speculation_t *spec = &state->dts_speculations[i];
  
                  curstate = spec->dtsp_state;
  
                  if (curstate != DTRACESPEC_INACTIVE) {
                          if (curstate == DTRACESPEC_COMMITTINGMANY ||
                              curstate == DTRACESPEC_COMMITTING ||
                              curstate == DTRACESPEC_DISCARDING)
                                  stat = &state->dts_speculations_busy;
                          i++;
                          continue;
                  }
  
                  if (dtrace_cas32((uint32_t *)&spec->dtsp_state,
                      curstate, DTRACESPEC_ACTIVE) == curstate)
                          return (i + 1);
          }
  
          /*
           * We couldn't find a speculation.  If we found as much as a single
           * busy speculation buffer, we'll attribute this failure as "busy"
           * instead of "unavail".
           */
          do {
                  count = *stat;
          } while (dtrace_cas32(stat, count, count + 1) != count);
  
          return (0);
  }
  
  /*
   * This routine commits an active speculation.  If the specified speculation
   * is not in a valid state to perform a commit(), this routine will silently do
   * nothing.  The state of the specified speculation is transitioned according
   * to the state transition diagram outlined in <sys/dtrace_impl.h>
   */
  static void
  dtrace_speculation_commit(dtrace_state_t *state, processorid_t cpu,
      dtrace_specid_t which)
  {
          dtrace_speculation_t *spec;
          dtrace_buffer_t *src, *dest;
          uintptr_t daddr, saddr, dlimit, slimit;
          dtrace_speculation_state_t curstate, new = 0;
          intptr_t offs;
          uint64_t timestamp;
  
          if (which == 0)
                  return;
  
          if (which > state->dts_nspeculations) {
                  cpu_core[cpu].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
                  return;
          }
  
          spec = &state->dts_speculations[which - 1];
          src = &spec->dtsp_buffer[cpu];
          dest = &state->dts_buffer[cpu];
  
          do {
                  curstate = spec->dtsp_state;
  
                  if (curstate == DTRACESPEC_COMMITTINGMANY)
                          break;
  
                  switch (curstate) {
                  case DTRACESPEC_INACTIVE:
                  case DTRACESPEC_DISCARDING:
                          return;
  
                  case DTRACESPEC_COMMITTING:
                          /*
                           * This is only possible if we are (a) commit()'ing
                           * without having done a prior speculate() on this CPU
                           * and (b) racing with another commit() on a different
                           * CPU.  There's nothing to do -- we just assert that
                           * our offset is 0.
                           */
                          ASSERT(src->dtb_offset == 0);
                          return;
  
                  case DTRACESPEC_ACTIVE:
                          new = DTRACESPEC_COMMITTING;
                          break;
  
                  case DTRACESPEC_ACTIVEONE:
                          /*
                           * This speculation is active on one CPU.  If our
                           * buffer offset is non-zero, we know that the one CPU
                           * must be us.  Otherwise, we are committing on a
                           * different CPU from the speculate(), and we must
                           * rely on being asynchronously cleaned.
                           */
                          if (src->dtb_offset != 0) {
                                  new = DTRACESPEC_COMMITTING;
                                  break;
                          }
                          /*FALLTHROUGH*/
  
                  case DTRACESPEC_ACTIVEMANY:
                          new = DTRACESPEC_COMMITTINGMANY;
                          break;
  
                  default:
                          ASSERT(0);
                  }
          } while (dtrace_cas32((uint32_t *)&spec->dtsp_state,
              curstate, new) != curstate);
  
          /*
           * We have set the state to indicate that we are committing this
           * speculation.  Now reserve the necessary space in the destination
           * buffer.
           */
          if ((offs = dtrace_buffer_reserve(dest, src->dtb_offset,
              sizeof (uint64_t), state, NULL)) < 0) {
                  dtrace_buffer_drop(dest);
                  goto out;
          }
  
          /*
           * We have sufficient space to copy the speculative buffer into the
           * primary buffer.  First, modify the speculative buffer, filling
           * in the timestamp of all entries with the curstate time.  The data
           * must have the commit() time rather than the time it was traced,
           * so that all entries in the primary buffer are in timestamp order.
           */
          timestamp = dtrace_gethrtime();
          saddr = (uintptr_t)src->dtb_tomax;
          slimit = saddr + src->dtb_offset;
          while (saddr < slimit) {
                  size_t size;
                  dtrace_rechdr_t *dtrh = (dtrace_rechdr_t *)saddr;
  
                  if (dtrh->dtrh_epid == DTRACE_EPIDNONE) {
                          saddr += sizeof (dtrace_epid_t);
                          continue;
                  }
                  ASSERT3U(dtrh->dtrh_epid, <=, state->dts_necbs);
                  size = state->dts_ecbs[dtrh->dtrh_epid - 1]->dte_size;
  
                  ASSERT3U(saddr + size, <=, slimit);
                  ASSERT3U(size, >=, sizeof (dtrace_rechdr_t));
                  ASSERT3U(DTRACE_RECORD_LOAD_TIMESTAMP(dtrh), ==, UINT64_MAX);
  
                  DTRACE_RECORD_STORE_TIMESTAMP(dtrh, timestamp);
  
                  saddr += size;
          }
  
          /*
           * Copy the buffer across.  (Note that this is a
           * highly subobtimal bcopy(); in the unlikely event that this becomes
           * a serious performance issue, a high-performance DTrace-specific
           * bcopy() should obviously be invented.)
           */
          daddr = (uintptr_t)dest->dtb_tomax + offs;
          dlimit = daddr + src->dtb_offset;
          saddr = (uintptr_t)src->dtb_tomax;
  
          /*
           * First, the aligned portion.
           */
          while (dlimit - daddr >= sizeof (uint64_t)) {
                  *((uint64_t *)daddr) = *((uint64_t *)saddr);
  
                  daddr += sizeof (uint64_t);
                  saddr += sizeof (uint64_t);
          }
  
          /*
           * Now any left-over bit...
           */
          while (dlimit - daddr)
                  *((uint8_t *)daddr++) = *((uint8_t *)saddr++);
  
          /*
           * Finally, commit the reserved space in the destination buffer.
           */
          dest->dtb_offset = offs + src->dtb_offset;
  
  out:
          /*
           * If we're lucky enough to be the only active CPU on this speculation
           * buffer, we can just set the state back to DTRACESPEC_INACTIVE.
           */
          if (curstate == DTRACESPEC_ACTIVE ||
              (curstate == DTRACESPEC_ACTIVEONE && new == DTRACESPEC_COMMITTING)) {
                  uint32_t rval = dtrace_cas32((uint32_t *)&spec->dtsp_state,
                      DTRACESPEC_COMMITTING, DTRACESPEC_INACTIVE);
  
                  ASSERT(rval == DTRACESPEC_COMMITTING);
          }
  
          src->dtb_offset = 0;
          src->dtb_xamot_drops += src->dtb_drops;
          src->dtb_drops = 0;
  }
  
  /*
   * This routine discards an active speculation.  If the specified speculation
   * is not in a valid state to perform a discard(), this routine will silently
   * do nothing.  The state of the specified speculation is transitioned
   * according to the state transition diagram outlined in <sys/dtrace_impl.h>
   */
  static void
  dtrace_speculation_discard(dtrace_state_t *state, processorid_t cpu,
      dtrace_specid_t which)
  {
          dtrace_speculation_t *spec;
          dtrace_speculation_state_t curstate, new = 0;
          dtrace_buffer_t *buf;
  
          if (which == 0)
                  return;
  
          if (which > state->dts_nspeculations) {
                  cpu_core[cpu].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
                  return;
          }
  
          spec = &state->dts_speculations[which - 1];
          buf = &spec->dtsp_buffer[cpu];
  
          do {
                  curstate = spec->dtsp_state;
  
                  switch (curstate) {
                  case DTRACESPEC_INACTIVE:
                  case DTRACESPEC_COMMITTINGMANY:
                  case DTRACESPEC_COMMITTING:
                  case DTRACESPEC_DISCARDING:
                          return;
  
                  case DTRACESPEC_ACTIVE:
                  case DTRACESPEC_ACTIVEMANY:
                          new = DTRACESPEC_DISCARDING;
                          break;
  
                  case DTRACESPEC_ACTIVEONE:
                          if (buf->dtb_offset != 0) {
                                  new = DTRACESPEC_INACTIVE;
                          } else {
                                  new = DTRACESPEC_DISCARDING;
                          }
                          break;
  
                  default:
                          ASSERT(0);
                  }
          } while (dtrace_cas32((uint32_t *)&spec->dtsp_state,
              curstate, new) != curstate);
  
          buf->dtb_offset = 0;
          buf->dtb_drops = 0;
  }
  
  /*
   * Note:  not called from probe context.  This function is called
   * asynchronously from cross call context to clean any speculations that are
   * in the COMMITTINGMANY or DISCARDING states.  These speculations may not be
   * transitioned back to the INACTIVE state until all CPUs have cleaned the
   * speculation.
   */
  static void
  dtrace_speculation_clean_here(dtrace_state_t *state)
  {
          dtrace_icookie_t cookie;
          processorid_t cpu = curcpu;
          dtrace_buffer_t *dest = &state->dts_buffer[cpu];
          dtrace_specid_t i;
  
          cookie = dtrace_interrupt_disable();
  
          if (dest->dtb_tomax == NULL) {
                  dtrace_interrupt_enable(cookie);
                  return;
          }
  
          for (i = 0; i < state->dts_nspeculations; i++) {
                  dtrace_speculation_t *spec = &state->dts_speculations[i];
                  dtrace_buffer_t *src = &spec->dtsp_buffer[cpu];
  
                  if (src->dtb_tomax == NULL)
                          continue;
  
                  if (spec->dtsp_state == DTRACESPEC_DISCARDING) {
                          src->dtb_offset = 0;
                          continue;
                  }
  
                  if (spec->dtsp_state != DTRACESPEC_COMMITTINGMANY)
                          continue;
  
                  if (src->dtb_offset == 0)
                          continue;
  
                  dtrace_speculation_commit(state, cpu, i + 1);
          }
  
          dtrace_interrupt_enable(cookie);
  }
  
  /*
   * Note:  not called from probe context.  This function is called
   * asynchronously (and at a regular interval) to clean any speculations that
   * are in the COMMITTINGMANY or DISCARDING states.  If it discovers that there
   * is work to be done, it cross calls all CPUs to perform that work;
   * COMMITMANY and DISCARDING speculations may not be transitioned back to the
   * INACTIVE state until they have been cleaned by all CPUs.
   */
  static void
  dtrace_speculation_clean(dtrace_state_t *state)
  {
          int work = 0, rv;
          dtrace_specid_t i;
  
          for (i = 0; i < state->dts_nspeculations; i++) {
                  dtrace_speculation_t *spec = &state->dts_speculations[i];
  
                  ASSERT(!spec->dtsp_cleaning);
  
                  if (spec->dtsp_state != DTRACESPEC_DISCARDING &&
                      spec->dtsp_state != DTRACESPEC_COMMITTINGMANY)
                          continue;
  
                  work++;
                  spec->dtsp_cleaning = 1;
          }
  
          if (!work)
                  return;
  
          dtrace_xcall(DTRACE_CPUALL,
              (dtrace_xcall_t)dtrace_speculation_clean_here, state);
  
          /*
           * We now know that all CPUs have committed or discarded their
           * speculation buffers, as appropriate.  We can now set the state
           * to inactive.
           */
          for (i = 0; i < state->dts_nspeculations; i++) {
                  dtrace_speculation_t *spec = &state->dts_speculations[i];
                  dtrace_speculation_state_t curstate, new;
  
                  if (!spec->dtsp_cleaning)
                          continue;
  
                  curstate = spec->dtsp_state;
                  ASSERT(curstate == DTRACESPEC_DISCARDING ||
                      curstate == DTRACESPEC_COMMITTINGMANY);
  
                  new = DTRACESPEC_INACTIVE;
  
                  rv = dtrace_cas32((uint32_t *)&spec->dtsp_state, curstate, new);
                  ASSERT(rv == curstate);
                  spec->dtsp_cleaning = 0;
          }
  }
  
  /*
   * Called as part of a speculate() to get the speculative buffer associated
   * with a given speculation.  Returns NULL if the specified speculation is not
   * in an ACTIVE state.  If the speculation is in the ACTIVEONE state -- and
   * the active CPU is not the specified CPU -- the speculation will be
   * atomically transitioned into the ACTIVEMANY state.
   */
  static dtrace_buffer_t *
  dtrace_speculation_buffer(dtrace_state_t *state, processorid_t cpuid,
      dtrace_specid_t which)
  {
          dtrace_speculation_t *spec;
          dtrace_speculation_state_t curstate, new = 0;
          dtrace_buffer_t *buf;
  
          if (which == 0)
                  return (NULL);
  
          if (which > state->dts_nspeculations) {
                  cpu_core[cpuid].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
                  return (NULL);
          }
  
          spec = &state->dts_speculations[which - 1];
          buf = &spec->dtsp_buffer[cpuid];
  
          do {
                  curstate = spec->dtsp_state;
  
                  switch (curstate) {
                  case DTRACESPEC_INACTIVE:
                  case DTRACESPEC_COMMITTINGMANY:
                  case DTRACESPEC_DISCARDING:
                          return (NULL);
  
                  case DTRACESPEC_COMMITTING:
                          ASSERT(buf->dtb_offset == 0);
                          return (NULL);
  
                  case DTRACESPEC_ACTIVEONE:
                          /*
                           * This speculation is currently active on one CPU.
                           * Check the offset in the buffer; if it's non-zero,
                           * that CPU must be us (and we leave the state alone).
                           * If it's zero, assume that we're starting on a new
                           * CPU -- and change the state to indicate that the
                           * speculation is active on more than one CPU.
                           */
                          if (buf->dtb_offset != 0)
                                  return (buf);
  
                          new = DTRACESPEC_ACTIVEMANY;
                          break;
  
                  case DTRACESPEC_ACTIVEMANY:
                          return (buf);
  
                  case DTRACESPEC_ACTIVE:
                          new = DTRACESPEC_ACTIVEONE;
                          break;
  
                  default:
                          ASSERT(0);
                  }
          } while (dtrace_cas32((uint32_t *)&spec->dtsp_state,
              curstate, new) != curstate);
  
          ASSERT(new == DTRACESPEC_ACTIVEONE || new == DTRACESPEC_ACTIVEMANY);
          return (buf);
  }
  
  /*
   * Return a string.  In the event that the user lacks the privilege to access
   * arbitrary kernel memory, we copy the string out to scratch memory so that we
   * don't fail access checking.
   *
   * dtrace_dif_variable() uses this routine as a helper for various
   * builtin values such as 'execname' and 'probefunc.'
   */
  uintptr_t
  dtrace_dif_varstr(uintptr_t addr, dtrace_state_t *state,
      dtrace_mstate_t *mstate)
  {
          uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
          uintptr_t ret;
          size_t strsz;
  
          /*
           * The easy case: this probe is allowed to read all of memory, so
           * we can just return this as a vanilla pointer.
           */
          if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0)
                  return (addr);
  
          /*
           * This is the tougher case: we copy the string in question from
           * kernel memory into scratch memory and return it that way: this
           * ensures that we won't trip up when access checking tests the
           * BYREF return value.
           */
          strsz = dtrace_strlen((char *)addr, size) + 1;
  
          if (mstate->dtms_scratch_ptr + strsz >
              mstate->dtms_scratch_base + mstate->dtms_scratch_size) {
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                  return (0);
          }
  
          dtrace_strcpy((const void *)addr, (void *)mstate->dtms_scratch_ptr,
              strsz);
          ret = mstate->dtms_scratch_ptr;
          mstate->dtms_scratch_ptr += strsz;
          return (ret);
  }
  
  /*
   * Return a string from a memoy address which is known to have one or
   * more concatenated, individually zero terminated, sub-strings.
   * In the event that the user lacks the privilege to access
   * arbitrary kernel memory, we copy the string out to scratch memory so that we
   * don't fail access checking.
   *
   * dtrace_dif_variable() uses this routine as a helper for various
   * builtin values such as 'execargs'.
   */
  static uintptr_t
  dtrace_dif_varstrz(uintptr_t addr, size_t strsz, dtrace_state_t *state,
      dtrace_mstate_t *mstate)
  {
          char *p;
          size_t i;
          uintptr_t ret;
  
          if (mstate->dtms_scratch_ptr + strsz >
              mstate->dtms_scratch_base + mstate->dtms_scratch_size) {
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                  return (0);
          }
  
          dtrace_bcopy((const void *)addr, (void *)mstate->dtms_scratch_ptr,
              strsz);
  
          /* Replace sub-string termination characters with a space. */
          for (p = (char *) mstate->dtms_scratch_ptr, i = 0; i < strsz - 1;
              p++, i++)
                  if (*p == '\0')
                          *p = ' ';
  
          ret = mstate->dtms_scratch_ptr;
          mstate->dtms_scratch_ptr += strsz;
          return (ret);
  }
  
  /*
   * This function implements the DIF emulator's variable lookups.  The emulator
   * passes a reserved variable identifier and optional built-in array index.
   */
  static uint64_t
  dtrace_dif_variable(dtrace_mstate_t *mstate, dtrace_state_t *state, uint64_t v,
      uint64_t ndx)
  {
          /*
           * If we're accessing one of the uncached arguments, we'll turn this
           * into a reference in the args array.
           */
          if (v >= DIF_VAR_ARG0 && v <= DIF_VAR_ARG9) {
                  ndx = v - DIF_VAR_ARG0;
                  v = DIF_VAR_ARGS;
          }
  
          switch (v) {
          case DIF_VAR_ARGS:
                  ASSERT(mstate->dtms_present & DTRACE_MSTATE_ARGS);
                  if (ndx >= sizeof (mstate->dtms_arg) /
                      sizeof (mstate->dtms_arg[0])) {
                          int aframes = mstate->dtms_probe->dtpr_aframes + 2;
                          dtrace_provider_t *pv;
                          uint64_t val;
  
                          pv = mstate->dtms_probe->dtpr_provider;
                          if (pv->dtpv_pops.dtps_getargval != NULL)
                                  val = pv->dtpv_pops.dtps_getargval(pv->dtpv_arg,
                                      mstate->dtms_probe->dtpr_id,
                                      mstate->dtms_probe->dtpr_arg, ndx, aframes);
                          else
                                  val = dtrace_getarg(ndx, aframes);
  
                          /*
                           * This is regrettably required to keep the compiler
                           * from tail-optimizing the call to dtrace_getarg().
                           * The condition always evaluates to true, but the
                           * compiler has no way of figuring that out a priori.
                           * (None of this would be necessary if the compiler
                           * could be relied upon to _always_ tail-optimize
                           * the call to dtrace_getarg() -- but it can't.)
                           */
                          if (mstate->dtms_probe != NULL)
                                  return (val);
  
                          ASSERT(0);
                  }
  
                  return (mstate->dtms_arg[ndx]);
  
          case DIF_VAR_REGS:
          case DIF_VAR_UREGS: {
                  struct trapframe *tframe;
  
                  if (!dtrace_priv_proc(state))
                          return (0);
  
                  if (v == DIF_VAR_REGS)
                          tframe = curthread->t_dtrace_trapframe;
                  else
                          tframe = curthread->td_frame;
  
                  if (tframe == NULL) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                          cpu_core[curcpu].cpuc_dtrace_illval = 0;
                          return (0);
                  }
  
                  return (dtrace_getreg(tframe, ndx));
          }
  
          case DIF_VAR_CURTHREAD:
                  if (!dtrace_priv_proc(state))
                          return (0);
                  return ((uint64_t)(uintptr_t)curthread);
  
          case DIF_VAR_TIMESTAMP:
                  if (!(mstate->dtms_present & DTRACE_MSTATE_TIMESTAMP)) {
                          mstate->dtms_timestamp = dtrace_gethrtime();
                          mstate->dtms_present |= DTRACE_MSTATE_TIMESTAMP;
                  }
                  return (mstate->dtms_timestamp);
  
          case DIF_VAR_VTIMESTAMP:
                  ASSERT(dtrace_vtime_references != 0);
                  return (curthread->t_dtrace_vtime);
  
          case DIF_VAR_WALLTIMESTAMP:
                  if (!(mstate->dtms_present & DTRACE_MSTATE_WALLTIMESTAMP)) {
                          mstate->dtms_walltimestamp = dtrace_gethrestime();
                          mstate->dtms_present |= DTRACE_MSTATE_WALLTIMESTAMP;
                  }
                  return (mstate->dtms_walltimestamp);
  
  #ifdef illumos
          case DIF_VAR_IPL:
                  if (!dtrace_priv_kernel(state))
                          return (0);
                  if (!(mstate->dtms_present & DTRACE_MSTATE_IPL)) {
                          mstate->dtms_ipl = dtrace_getipl();
                          mstate->dtms_present |= DTRACE_MSTATE_IPL;
                  }
                  return (mstate->dtms_ipl);
  #endif
  
          case DIF_VAR_EPID:
                  ASSERT(mstate->dtms_present & DTRACE_MSTATE_EPID);
                  return (mstate->dtms_epid);
  
          case DIF_VAR_ID:
                  ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                  return (mstate->dtms_probe->dtpr_id);
  
          case DIF_VAR_STACKDEPTH:
                  if (!dtrace_priv_kernel(state))
                          return (0);
                  if (!(mstate->dtms_present & DTRACE_MSTATE_STACKDEPTH)) {
                          int aframes = mstate->dtms_probe->dtpr_aframes + 2;
  
                          mstate->dtms_stackdepth = dtrace_getstackdepth(aframes);
                          mstate->dtms_present |= DTRACE_MSTATE_STACKDEPTH;
                  }
                  return (mstate->dtms_stackdepth);
  
          case DIF_VAR_USTACKDEPTH:
                  if (!dtrace_priv_proc(state))
                          return (0);
                  if (!(mstate->dtms_present & DTRACE_MSTATE_USTACKDEPTH)) {
                          /*
                           * See comment in DIF_VAR_PID.
                           */
                          if (DTRACE_ANCHORED(mstate->dtms_probe) &&
                              CPU_ON_INTR(CPU)) {
                                  mstate->dtms_ustackdepth = 0;
                          } else {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                  mstate->dtms_ustackdepth =
                                      dtrace_getustackdepth();
                                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          }
                          mstate->dtms_present |= DTRACE_MSTATE_USTACKDEPTH;
                  }
                  return (mstate->dtms_ustackdepth);
  
          case DIF_VAR_CALLER:
                  if (!dtrace_priv_kernel(state))
                          return (0);
                  if (!(mstate->dtms_present & DTRACE_MSTATE_CALLER)) {
                          int aframes = mstate->dtms_probe->dtpr_aframes + 2;
  
                          if (!DTRACE_ANCHORED(mstate->dtms_probe)) {
                                  /*
                                   * If this is an unanchored probe, we are
                                   * required to go through the slow path:
                                   * dtrace_caller() only guarantees correct
                                   * results for anchored probes.
                                   */
                                  pc_t caller[2] = {0, 0};
  
                                  dtrace_getpcstack(caller, 2, aframes,
                                      (uint32_t *)(uintptr_t)mstate->dtms_arg[0]);
                                  mstate->dtms_caller = caller[1];
                          } else if ((mstate->dtms_caller =
                              dtrace_caller(aframes)) == -1) {
                                  /*
                                   * We have failed to do this the quick way;
                                   * we must resort to the slower approach of
                                   * calling dtrace_getpcstack().
                                   */
                                  pc_t caller = 0;
  
                                  dtrace_getpcstack(&caller, 1, aframes, NULL);
                                  mstate->dtms_caller = caller;
                          }
  
                          mstate->dtms_present |= DTRACE_MSTATE_CALLER;
                  }
                  return (mstate->dtms_caller);
  
          case DIF_VAR_UCALLER:
                  if (!dtrace_priv_proc(state))
                          return (0);
  
                  if (!(mstate->dtms_present & DTRACE_MSTATE_UCALLER)) {
                          uint64_t ustack[3];
  
                          /*
                           * dtrace_getupcstack() fills in the first uint64_t
                           * with the current PID.  The second uint64_t will
                           * be the program counter at user-level.  The third
                           * uint64_t will contain the caller, which is what
                           * we're after.
                           */
                          ustack[2] = 0;
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          dtrace_getupcstack(ustack, 3);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          mstate->dtms_ucaller = ustack[2];
                          mstate->dtms_present |= DTRACE_MSTATE_UCALLER;
                  }
  
                  return (mstate->dtms_ucaller);
  
          case DIF_VAR_PROBEPROV:
                  ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                  return (dtrace_dif_varstr(
                      (uintptr_t)mstate->dtms_probe->dtpr_provider->dtpv_name,
                      state, mstate));
  
          case DIF_VAR_PROBEMOD:
                  ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                  return (dtrace_dif_varstr(
                      (uintptr_t)mstate->dtms_probe->dtpr_mod,
                      state, mstate));
  
          case DIF_VAR_PROBEFUNC:
                  ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                  return (dtrace_dif_varstr(
                      (uintptr_t)mstate->dtms_probe->dtpr_func,
                      state, mstate));
  
          case DIF_VAR_PROBENAME:
                  ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                  return (dtrace_dif_varstr(
                      (uintptr_t)mstate->dtms_probe->dtpr_name,
                      state, mstate));
  
          case DIF_VAR_PID:
                  if (!dtrace_priv_proc(state))
                          return (0);
  
  #ifdef illumos
                  /*
                   * Note that we are assuming that an unanchored probe is
                   * always due to a high-level interrupt.  (And we're assuming
                   * that there is only a single high level interrupt.)
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return (pid0.pid_id);
  
                  /*
                   * It is always safe to dereference one's own t_procp pointer:
                   * it always points to a valid, allocated proc structure.
                   * Further, it is always safe to dereference the p_pidp member
                   * of one's own proc structure.  (These are truisms becuase
                   * threads and processes don't clean up their own state --
                   * they leave that task to whomever reaps them.)
                   */
                  return ((uint64_t)curthread->t_procp->p_pidp->pid_id);
  #else
                  return ((uint64_t)curproc->p_pid);
  #endif
  
          case DIF_VAR_PPID:
                  if (!dtrace_priv_proc(state))
                          return (0);
  
  #ifdef illumos
                  /*
                   * See comment in DIF_VAR_PID.
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return (pid0.pid_id);
  
                  /*
                   * It is always safe to dereference one's own t_procp pointer:
                   * it always points to a valid, allocated proc structure.
                   * (This is true because threads don't clean up their own
                   * state -- they leave that task to whomever reaps them.)
                   */
                  return ((uint64_t)curthread->t_procp->p_ppid);
  #else
                  if (curproc->p_pid == proc0.p_pid)
                          return (curproc->p_pid);
                  else
                          return (curproc->p_pptr->p_pid);
  #endif
  
          case DIF_VAR_TID:
  #ifdef illumos
                  /*
                   * See comment in DIF_VAR_PID.
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return (0);
  #endif
  
                  return ((uint64_t)curthread->t_tid);
  
          case DIF_VAR_EXECARGS: {
                  struct pargs *p_args = curthread->td_proc->p_args;
  
                  if (p_args == NULL)
                          return(0);
  
                  return (dtrace_dif_varstrz(
                      (uintptr_t) p_args->ar_args, p_args->ar_length, state, mstate));
          }
  
          case DIF_VAR_EXECNAME:
  #ifdef illumos
                  if (!dtrace_priv_proc(state))
                          return (0);
  
                  /*
                   * See comment in DIF_VAR_PID.
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return ((uint64_t)(uintptr_t)p0.p_user.u_comm);
  
                  /*
                   * It is always safe to dereference one's own t_procp pointer:
                   * it always points to a valid, allocated proc structure.
                   * (This is true because threads don't clean up their own
                   * state -- they leave that task to whomever reaps them.)
                   */
                  return (dtrace_dif_varstr(
                      (uintptr_t)curthread->t_procp->p_user.u_comm,
                      state, mstate));
  #else
                  return (dtrace_dif_varstr(
                      (uintptr_t) curthread->td_proc->p_comm, state, mstate));
  #endif
  
          case DIF_VAR_ZONENAME:
  #ifdef illumos
                  if (!dtrace_priv_proc(state))
                          return (0);
  
                  /*
                   * See comment in DIF_VAR_PID.
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return ((uint64_t)(uintptr_t)p0.p_zone->zone_name);
  
                  /*
                   * It is always safe to dereference one's own t_procp pointer:
                   * it always points to a valid, allocated proc structure.
                   * (This is true because threads don't clean up their own
                   * state -- they leave that task to whomever reaps them.)
                   */
                  return (dtrace_dif_varstr(
                      (uintptr_t)curthread->t_procp->p_zone->zone_name,
                      state, mstate));
  #elif defined(__FreeBSD__)
          /*
           * On FreeBSD, we introduce compatibility to zonename by falling through
           * into jailname.
           */
          case DIF_VAR_JAILNAME:
                  if (!dtrace_priv_kernel(state))
                          return (0);
  
                  return (dtrace_dif_varstr(
                      (uintptr_t)curthread->td_ucred->cr_prison->pr_name,
                      state, mstate));
  
          case DIF_VAR_JID:
                  if (!dtrace_priv_kernel(state))
                          return (0);
  
                  return ((uint64_t)curthread->td_ucred->cr_prison->pr_id);
  #else
                  return (0);
  #endif
  
          case DIF_VAR_UID:
                  if (!dtrace_priv_proc(state))
                          return (0);
  
  #ifdef illumos
                  /*
                   * See comment in DIF_VAR_PID.
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return ((uint64_t)p0.p_cred->cr_uid);
  
                  /*
                   * It is always safe to dereference one's own t_procp pointer:
                   * it always points to a valid, allocated proc structure.
                   * (This is true because threads don't clean up their own
                   * state -- they leave that task to whomever reaps them.)
                   *
                   * Additionally, it is safe to dereference one's own process
                   * credential, since this is never NULL after process birth.
                   */
                  return ((uint64_t)curthread->t_procp->p_cred->cr_uid);
  #else
                  return ((uint64_t)curthread->td_ucred->cr_uid);
  #endif
  
          case DIF_VAR_GID:
                  if (!dtrace_priv_proc(state))
                          return (0);
  
  #ifdef illumos
                  /*
                   * See comment in DIF_VAR_PID.
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return ((uint64_t)p0.p_cred->cr_gid);
  
                  /*
                   * It is always safe to dereference one's own t_procp pointer:
                   * it always points to a valid, allocated proc structure.
                   * (This is true because threads don't clean up their own
                   * state -- they leave that task to whomever reaps them.)
                   *
                   * Additionally, it is safe to dereference one's own process
                   * credential, since this is never NULL after process birth.
                   */
                  return ((uint64_t)curthread->t_procp->p_cred->cr_gid);
  #else
                  return ((uint64_t)curthread->td_ucred->cr_gid);
  #endif
  
          case DIF_VAR_ERRNO: {
  #ifdef illumos
                  klwp_t *lwp;
                  if (!dtrace_priv_proc(state))
                          return (0);
  
                  /*
                   * See comment in DIF_VAR_PID.
                   */
                  if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                          return (0);
  
                  /*
                   * It is always safe to dereference one's own t_lwp pointer in
                   * the event that this pointer is non-NULL.  (This is true
                   * because threads and lwps don't clean up their own state --
                   * they leave that task to whomever reaps them.)
                   */
                  if ((lwp = curthread->t_lwp) == NULL)
                          return (0);
  
                  return ((uint64_t)lwp->lwp_errno);
  #else
                  return (curthread->td_errno);
  #endif
          }
  #ifndef illumos
          case DIF_VAR_CPU: {
                  return curcpu;
          }
  #endif
          default:
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                  return (0);
          }
  }
  
  
  typedef enum dtrace_json_state {
          DTRACE_JSON_REST = 1,
          DTRACE_JSON_OBJECT,
          DTRACE_JSON_STRING,
          DTRACE_JSON_STRING_ESCAPE,
          DTRACE_JSON_STRING_ESCAPE_UNICODE,
          DTRACE_JSON_COLON,
          DTRACE_JSON_COMMA,
          DTRACE_JSON_VALUE,
          DTRACE_JSON_IDENTIFIER,
          DTRACE_JSON_NUMBER,
          DTRACE_JSON_NUMBER_FRAC,
          DTRACE_JSON_NUMBER_EXP,
          DTRACE_JSON_COLLECT_OBJECT
  } dtrace_json_state_t;
  
  /*
   * This function possesses just enough knowledge about JSON to extract a single
   * value from a JSON string and store it in the scratch buffer.  It is able
   * to extract nested object values, and members of arrays by index.
   *
   * elemlist is a list of JSON keys, stored as packed NUL-terminated strings, to
   * be looked up as we descend into the object tree.  e.g.
   *
   *    foo[0].bar.baz[32] --> "foo" NUL "" NUL "bar" NUL "baz" NUL "32" NUL
   *       with nelems = 5.
   *
   * The run time of this function must be bounded above by strsize to limit the
   * amount of work done in probe context.  As such, it is implemented as a
   * simple state machine, reading one character at a time using safe loads
   * until we find the requested element, hit a parsing error or run off the
   * end of the object or string.
   *
   * As there is no way for a subroutine to return an error without interrupting
   * clause execution, we simply return NULL in the event of a missing key or any
   * other error condition.  Each NULL return in this function is commented with
   * the error condition it represents -- parsing or otherwise.
   *
   * The set of states for the state machine closely matches the JSON
   * specification (http://json.org/).  Briefly:
   *
   *   DTRACE_JSON_REST:
   *     Skip whitespace until we find either a top-level Object, moving
   *     to DTRACE_JSON_OBJECT; or an Array, moving to DTRACE_JSON_VALUE.
   *
   *   DTRACE_JSON_OBJECT:
   *     Locate the next key String in an Object.  Sets a flag to denote
   *     the next String as a key string and moves to DTRACE_JSON_STRING.
   *
   *   DTRACE_JSON_COLON:
   *     Skip whitespace until we find the colon that separates key Strings
   *     from their values.  Once found, move to DTRACE_JSON_VALUE.
   *
   *   DTRACE_JSON_VALUE:
   *     Detects the type of the next value (String, Number, Identifier, Object
   *     or Array) and routes to the states that process that type.  Here we also
   *     deal with the element selector list if we are requested to traverse down
   *     into the object tree.
   *
   *   DTRACE_JSON_COMMA:
   *     Skip whitespace until we find the comma that separates key-value pairs
   *     in Objects (returning to DTRACE_JSON_OBJECT) or values in Arrays
   *     (similarly DTRACE_JSON_VALUE).  All following literal value processing
   *     states return to this state at the end of their value, unless otherwise
   *     noted.
   *
   *   DTRACE_JSON_NUMBER, DTRACE_JSON_NUMBER_FRAC, DTRACE_JSON_NUMBER_EXP:
   *     Processes a Number literal from the JSON, including any exponent
   *     component that may be present.  Numbers are returned as strings, which
   *     may be passed to strtoll() if an integer is required.
   *
   *   DTRACE_JSON_IDENTIFIER:
   *     Processes a "true", "false" or "null" literal in the JSON.
   *
   *   DTRACE_JSON_STRING, DTRACE_JSON_STRING_ESCAPE,
   *   DTRACE_JSON_STRING_ESCAPE_UNICODE:
   *     Processes a String literal from the JSON, whether the String denotes
   *     a key, a value or part of a larger Object.  Handles all escape sequences
   *     present in the specification, including four-digit unicode characters,
   *     but merely includes the escape sequence without converting it to the
   *     actual escaped character.  If the String is flagged as a key, we
   *     move to DTRACE_JSON_COLON rather than DTRACE_JSON_COMMA.
   *
   *   DTRACE_JSON_COLLECT_OBJECT:
   *     This state collects an entire Object (or Array), correctly handling
   *     embedded strings.  If the full element selector list matches this nested
   *     object, we return the Object in full as a string.  If not, we use this
   *     state to skip to the next value at this level and continue processing.
   *
   * NOTE: This function uses various macros from strtolctype.h to manipulate
   * digit values, etc -- these have all been checked to ensure they make
   * no additional function calls.
   */
  static char *
  dtrace_json(uint64_t size, uintptr_t json, char *elemlist, int nelems,
      char *dest)
  {
          dtrace_json_state_t state = DTRACE_JSON_REST;
          int64_t array_elem = INT64_MIN;
          int64_t array_pos = 0;
          uint8_t escape_unicount = 0;
          boolean_t string_is_key = B_FALSE;
          boolean_t collect_object = B_FALSE;
          boolean_t found_key = B_FALSE;
          boolean_t in_array = B_FALSE;
          uint32_t braces = 0, brackets = 0;
          char *elem = elemlist;
          char *dd = dest;
          uintptr_t cur;
  
          for (cur = json; cur < json + size; cur++) {
                  char cc = dtrace_load8(cur);
                  if (cc == '\0')
                          return (NULL);
  
                  switch (state) {
                  case DTRACE_JSON_REST:
                          if (isspace(cc))
                                  break;
  
                          if (cc == '{') {
                                  state = DTRACE_JSON_OBJECT;
                                  break;
                          }
  
                          if (cc == '[') {
                                  in_array = B_TRUE;
                                  array_pos = 0;
                                  array_elem = dtrace_strtoll(elem, 10, size);
                                  found_key = array_elem == 0 ? B_TRUE : B_FALSE;
                                  state = DTRACE_JSON_VALUE;
                                  break;
                          }
  
                          /*
                           * ERROR: expected to find a top-level object or array.
                           */
                          return (NULL);
                  case DTRACE_JSON_OBJECT:
                          if (isspace(cc))
                                  break;
  
                          if (cc == '"') {
                                  state = DTRACE_JSON_STRING;
                                  string_is_key = B_TRUE;
                                  break;
                          }
  
                          /*
                           * ERROR: either the object did not start with a key
                           * string, or we've run off the end of the object
                           * without finding the requested key.
                           */
                          return (NULL);
                  case DTRACE_JSON_STRING:
                          if (cc == '\\') {
                                  *dd++ = '\\';
                                  state = DTRACE_JSON_STRING_ESCAPE;
                                  break;
                          }
  
                          if (cc == '"') {
                                  if (collect_object) {
                                          /*
                                           * We don't reset the dest here, as
                                           * the string is part of a larger
                                           * object being collected.
                                           */
                                          *dd++ = cc;
                                          collect_object = B_FALSE;
                                          state = DTRACE_JSON_COLLECT_OBJECT;
                                          break;
                                  }
                                  *dd = '\0';
                                  dd = dest; /* reset string buffer */
                                  if (string_is_key) {
                                          if (dtrace_strncmp(dest, elem,
                                              size) == 0)
                                                  found_key = B_TRUE;
                                  } else if (found_key) {
                                          if (nelems > 1) {
                                                  /*
                                                   * We expected an object, not
                                                   * this string.
                                                   */
                                                  return (NULL);
                                          }
                                          return (dest);
                                  }
                                  state = string_is_key ? DTRACE_JSON_COLON :
                                      DTRACE_JSON_COMMA;
                                  string_is_key = B_FALSE;
                                  break;
                          }
  
                          *dd++ = cc;
                          break;
                  case DTRACE_JSON_STRING_ESCAPE:
                          *dd++ = cc;
                          if (cc == 'u') {
                                  escape_unicount = 0;
                                  state = DTRACE_JSON_STRING_ESCAPE_UNICODE;
                          } else {
                                  state = DTRACE_JSON_STRING;
                          }
                          break;
                  case DTRACE_JSON_STRING_ESCAPE_UNICODE:
                          if (!isxdigit(cc)) {
                                  /*
                                   * ERROR: invalid unicode escape, expected
                                   * four valid hexidecimal digits.
                                   */
                                  return (NULL);
                          }
  
                          *dd++ = cc;
                          if (++escape_unicount == 4)
                                  state = DTRACE_JSON_STRING;
                          break;
                  case DTRACE_JSON_COLON:
                          if (isspace(cc))
                                  break;
  
                          if (cc == ':') {
                                  state = DTRACE_JSON_VALUE;
                                  break;
                          }
  
                          /*
                           * ERROR: expected a colon.
                           */
                          return (NULL);
                  case DTRACE_JSON_COMMA:
                          if (isspace(cc))
                                  break;
  
                          if (cc == ',') {
                                  if (in_array) {
                                          state = DTRACE_JSON_VALUE;
                                          if (++array_pos == array_elem)
                                                  found_key = B_TRUE;
                                  } else {
                                          state = DTRACE_JSON_OBJECT;
                                  }
                                  break;
                          }
  
                          /*
                           * ERROR: either we hit an unexpected character, or
                           * we reached the end of the object or array without
                           * finding the requested key.
                           */
                          return (NULL);
                  case DTRACE_JSON_IDENTIFIER:
                          if (islower(cc)) {
                                  *dd++ = cc;
                                  break;
                          }
  
                          *dd = '\0';
                          dd = dest; /* reset string buffer */
  
                          if (dtrace_strncmp(dest, "true", 5) == 0 ||
                              dtrace_strncmp(dest, "false", 6) == 0 ||
                              dtrace_strncmp(dest, "null", 5) == 0) {
                                  if (found_key) {
                                          if (nelems > 1) {
                                                  /*
                                                   * ERROR: We expected an object,
                                                   * not this identifier.
                                                   */
                                                  return (NULL);
                                          }
                                          return (dest);
                                  } else {
                                          cur--;
                                          state = DTRACE_JSON_COMMA;
                                          break;
                                  }
                          }
  
                          /*
                           * ERROR: we did not recognise the identifier as one
                           * of those in the JSON specification.
                           */
                          return (NULL);
                  case DTRACE_JSON_NUMBER:
                          if (cc == '.') {
                                  *dd++ = cc;
                                  state = DTRACE_JSON_NUMBER_FRAC;
                                  break;
                          }
  
                          if (cc == 'x' || cc == 'X') {
                                  /*
                                   * ERROR: specification explicitly excludes
                                   * hexidecimal or octal numbers.
                                   */
                                  return (NULL);
                          }
  
                          /* FALLTHRU */
                  case DTRACE_JSON_NUMBER_FRAC:
                          if (cc == 'e' || cc == 'E') {
                                  *dd++ = cc;
                                  state = DTRACE_JSON_NUMBER_EXP;
                                  break;
                          }
  
                          if (cc == '+' || cc == '-') {
                                  /*
                                   * ERROR: expect sign as part of exponent only.
                                   */
                                  return (NULL);
                          }
                          /* FALLTHRU */
                  case DTRACE_JSON_NUMBER_EXP:
                          if (isdigit(cc) || cc == '+' || cc == '-') {
                                  *dd++ = cc;
                                  break;
                          }
  
                          *dd = '\0';
                          dd = dest; /* reset string buffer */
                          if (found_key) {
                                  if (nelems > 1) {
                                          /*
                                           * ERROR: We expected an object, not
                                           * this number.
                                           */
                                          return (NULL);
                                  }
                                  return (dest);
                          }
  
                          cur--;
                          state = DTRACE_JSON_COMMA;
                          break;
                  case DTRACE_JSON_VALUE:
                          if (isspace(cc))
                                  break;
  
                          if (cc == '{' || cc == '[') {
                                  if (nelems > 1 && found_key) {
                                          in_array = cc == '[' ? B_TRUE : B_FALSE;
                                          /*
                                           * If our element selector directs us
                                           * to descend into this nested object,
                                           * then move to the next selector
                                           * element in the list and restart the
                                           * state machine.
                                           */
                                          while (*elem != '\0')
                                                  elem++;
                                          elem++; /* skip the inter-element NUL */
                                          nelems--;
                                          dd = dest;
                                          if (in_array) {
                                                  state = DTRACE_JSON_VALUE;
                                                  array_pos = 0;
                                                  array_elem = dtrace_strtoll(
                                                      elem, 10, size);
                                                  found_key = array_elem == 0 ?
                                                      B_TRUE : B_FALSE;
                                          } else {
                                                  found_key = B_FALSE;
                                                  state = DTRACE_JSON_OBJECT;
                                          }
                                          break;
                                  }
  
                                  /*
                                   * Otherwise, we wish to either skip this
                                   * nested object or return it in full.
                                   */
                                  if (cc == '[')
                                          brackets = 1;
                                  else
                                          braces = 1;
                                  *dd++ = cc;
                                  state = DTRACE_JSON_COLLECT_OBJECT;
                                  break;
                          }
  
                          if (cc == '"') {
                                  state = DTRACE_JSON_STRING;
                                  break;
                          }
  
                          if (islower(cc)) {
                                  /*
                                   * Here we deal with true, false and null.
                                   */
                                  *dd++ = cc;
                                  state = DTRACE_JSON_IDENTIFIER;
                                  break;
                          }
  
                          if (cc == '-' || isdigit(cc)) {
                                  *dd++ = cc;
                                  state = DTRACE_JSON_NUMBER;
                                  break;
                          }
  
                          /*
                           * ERROR: unexpected character at start of value.
                           */
                          return (NULL);
                  case DTRACE_JSON_COLLECT_OBJECT:
                          if (cc == '\0')
                                  /*
                                   * ERROR: unexpected end of input.
                                   */
                                  return (NULL);
  
                          *dd++ = cc;
                          if (cc == '"') {
                                  collect_object = B_TRUE;
                                  state = DTRACE_JSON_STRING;
                                  break;
                          }
  
                          if (cc == ']') {
                                  if (brackets-- == 0) {
                                          /*
                                           * ERROR: unbalanced brackets.
                                           */
                                          return (NULL);
                                  }
                          } else if (cc == '}') {
                                  if (braces-- == 0) {
                                          /*
                                           * ERROR: unbalanced braces.
                                           */
                                          return (NULL);
                                  }
                          } else if (cc == '{') {
                                  braces++;
                          } else if (cc == '[') {
                                  brackets++;
                          }
  
                          if (brackets == 0 && braces == 0) {
                                  if (found_key) {
                                          *dd = '\0';
                                          return (dest);
                                  }
                                  dd = dest; /* reset string buffer */
                                  state = DTRACE_JSON_COMMA;
                          }
                          break;
                  }
          }
          return (NULL);
  }
  
  /*
   * Emulate the execution of DTrace ID subroutines invoked by the call opcode.
   * Notice that we don't bother validating the proper number of arguments or
   * their types in the tuple stack.  This isn't needed because all argument
   * interpretation is safe because of our load safety -- the worst that can
   * happen is that a bogus program can obtain bogus results.
   */
  static void
  dtrace_dif_subr(uint_t subr, uint_t rd, uint64_t *regs,
      dtrace_key_t *tupregs, int nargs,
      dtrace_mstate_t *mstate, dtrace_state_t *state)
  {
          volatile uint16_t *flags = &cpu_core[curcpu].cpuc_dtrace_flags;
          volatile uintptr_t *illval = &cpu_core[curcpu].cpuc_dtrace_illval;
          dtrace_vstate_t *vstate = &state->dts_vstate;
  
  #ifdef illumos
          union {
                  mutex_impl_t mi;
                  uint64_t mx;
          } m;
  
          union {
                  krwlock_t ri;
                  uintptr_t rw;
          } r;
  #else
          struct thread *lowner;
          union {
                  struct lock_object *li;
                  uintptr_t lx;
          } l;
  #endif
  
          switch (subr) {
          case DIF_SUBR_RAND:
                  regs[rd] = dtrace_xoroshiro128_plus_next(
                      state->dts_rstate[curcpu]);
                  break;
  
  #ifdef illumos
          case DIF_SUBR_MUTEX_OWNED:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  m.mx = dtrace_load64(tupregs[0].dttk_value);
                  if (MUTEX_TYPE_ADAPTIVE(&m.mi))
                          regs[rd] = MUTEX_OWNER(&m.mi) != MUTEX_NO_OWNER;
                  else
                          regs[rd] = LOCK_HELD(&m.mi.m_spin.m_spinlock);
                  break;
  
          case DIF_SUBR_MUTEX_OWNER:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  m.mx = dtrace_load64(tupregs[0].dttk_value);
                  if (MUTEX_TYPE_ADAPTIVE(&m.mi) &&
                      MUTEX_OWNER(&m.mi) != MUTEX_NO_OWNER)
                          regs[rd] = (uintptr_t)MUTEX_OWNER(&m.mi);
                  else
                          regs[rd] = 0;
                  break;
  
          case DIF_SUBR_MUTEX_TYPE_ADAPTIVE:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  m.mx = dtrace_load64(tupregs[0].dttk_value);
                  regs[rd] = MUTEX_TYPE_ADAPTIVE(&m.mi);
                  break;
  
          case DIF_SUBR_MUTEX_TYPE_SPIN:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  m.mx = dtrace_load64(tupregs[0].dttk_value);
                  regs[rd] = MUTEX_TYPE_SPIN(&m.mi);
                  break;
  
          case DIF_SUBR_RW_READ_HELD: {
                  uintptr_t tmp;
  
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                  regs[rd] = _RW_READ_HELD(&r.ri, tmp);
                  break;
          }
  
          case DIF_SUBR_RW_WRITE_HELD:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (krwlock_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                  regs[rd] = _RW_WRITE_HELD(&r.ri);
                  break;
  
          case DIF_SUBR_RW_ISWRITER:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (krwlock_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                  regs[rd] = _RW_ISWRITER(&r.ri);
                  break;
  
  #else /* !illumos */
          case DIF_SUBR_MUTEX_OWNED:
                  if (!dtrace_canload(tupregs[0].dttk_value,
                          sizeof (struct lock_object), mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  break;
  
          case DIF_SUBR_MUTEX_OWNER:
                  if (!dtrace_canload(tupregs[0].dttk_value,
                          sizeof (struct lock_object), mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  regs[rd] = (uintptr_t)lowner;
                  break;
  
          case DIF_SUBR_MUTEX_TYPE_ADAPTIVE:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (struct mtx),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  regs[rd] = (LOCK_CLASS(l.li)->lc_flags & LC_SLEEPLOCK) != 0;
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  break;
  
          case DIF_SUBR_MUTEX_TYPE_SPIN:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (struct mtx),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  regs[rd] = (LOCK_CLASS(l.li)->lc_flags & LC_SPINLOCK) != 0;
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  break;
  
          case DIF_SUBR_RW_READ_HELD: 
          case DIF_SUBR_SX_SHARED_HELD: 
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner) &&
                      lowner == NULL;
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  break;
  
          case DIF_SUBR_RW_WRITE_HELD:
          case DIF_SUBR_SX_EXCLUSIVE_HELD:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  l.lx = dtrace_loadptr(tupregs[0].dttk_value);
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner) &&
                      lowner != NULL;
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  break;
  
          case DIF_SUBR_RW_ISWRITER:
          case DIF_SUBR_SX_ISEXCLUSIVE:
                  if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                      mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  l.lx = dtrace_loadptr(tupregs[0].dttk_value);
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  regs[rd] = (lowner == curthread);
                  break;
  #endif /* illumos */
  
          case DIF_SUBR_BCOPY: {
                  /*
                   * We need to be sure that the destination is in the scratch
                   * region -- no other region is allowed.
                   */
                  uintptr_t src = tupregs[0].dttk_value;
                  uintptr_t dest = tupregs[1].dttk_value;
                  size_t size = tupregs[2].dttk_value;
  
                  if (!dtrace_inscratch(dest, size, mstate)) {
                          *flags |= CPU_DTRACE_BADADDR;
                          *illval = regs[rd];
                          break;
                  }
  
                  if (!dtrace_canload(src, size, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  dtrace_bcopy((void *)src, (void *)dest, size);
                  break;
          }
  
          case DIF_SUBR_ALLOCA:
          case DIF_SUBR_COPYIN: {
                  uintptr_t dest = P2ROUNDUP(mstate->dtms_scratch_ptr, 8);
                  uint64_t size =
                      tupregs[subr == DIF_SUBR_ALLOCA ? 0 : 1].dttk_value;
                  size_t scratch_size = (dest - mstate->dtms_scratch_ptr) + size;
  
                  /*
                   * This action doesn't require any credential checks since
                   * probes will not activate in user contexts to which the
                   * enabling user does not have permissions.
                   */
  
                  /*
                   * Rounding up the user allocation size could have overflowed
                   * a large, bogus allocation (like -1ULL) to 0.
                   */
                  if (scratch_size < size ||
                      !DTRACE_INSCRATCH(mstate, scratch_size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  if (subr == DIF_SUBR_COPYIN) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          dtrace_copyin(tupregs[0].dttk_value, dest, size, flags);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  }
  
                  mstate->dtms_scratch_ptr += scratch_size;
                  regs[rd] = dest;
                  break;
          }
  
          case DIF_SUBR_COPYINTO: {
                  uint64_t size = tupregs[1].dttk_value;
                  uintptr_t dest = tupregs[2].dttk_value;
  
                  /*
                   * This action doesn't require any credential checks since
                   * probes will not activate in user contexts to which the
                   * enabling user does not have permissions.
                   */
                  if (!dtrace_inscratch(dest, size, mstate)) {
                          *flags |= CPU_DTRACE_BADADDR;
                          *illval = regs[rd];
                          break;
                  }
  
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  dtrace_copyin(tupregs[0].dttk_value, dest, size, flags);
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  break;
          }
  
          case DIF_SUBR_COPYINSTR: {
                  uintptr_t dest = mstate->dtms_scratch_ptr;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
  
                  if (nargs > 1 && tupregs[1].dttk_value < size)
                          size = tupregs[1].dttk_value + 1;
  
                  /*
                   * This action doesn't require any credential checks since
                   * probes will not activate in user contexts to which the
                   * enabling user does not have permissions.
                   */
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                  dtrace_copyinstr(tupregs[0].dttk_value, dest, size, flags);
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
  
                  ((char *)dest)[size - 1] = '\0';
                  mstate->dtms_scratch_ptr += size;
                  regs[rd] = dest;
                  break;
          }
  
  #ifdef illumos
          case DIF_SUBR_MSGSIZE:
          case DIF_SUBR_MSGDSIZE: {
                  uintptr_t baddr = tupregs[0].dttk_value, daddr;
                  uintptr_t wptr, rptr;
                  size_t count = 0;
                  int cont = 0;
  
                  while (baddr != 0 && !(*flags & CPU_DTRACE_FAULT)) {
  
                          if (!dtrace_canload(baddr, sizeof (mblk_t), mstate,
                              vstate)) {
                                  regs[rd] = 0;
                                  break;
                          }
  
                          wptr = dtrace_loadptr(baddr +
                              offsetof(mblk_t, b_wptr));
  
                          rptr = dtrace_loadptr(baddr +
                              offsetof(mblk_t, b_rptr));
  
                          if (wptr < rptr) {
                                  *flags |= CPU_DTRACE_BADADDR;
                                  *illval = tupregs[0].dttk_value;
                                  break;
                          }
  
                          daddr = dtrace_loadptr(baddr +
                              offsetof(mblk_t, b_datap));
  
                          baddr = dtrace_loadptr(baddr +
                              offsetof(mblk_t, b_cont));
  
                          /*
                           * We want to prevent against denial-of-service here,
                           * so we're only going to search the list for
                           * dtrace_msgdsize_max mblks.
                           */
                          if (cont++ > dtrace_msgdsize_max) {
                                  *flags |= CPU_DTRACE_ILLOP;
                                  break;
                          }
  
                          if (subr == DIF_SUBR_MSGDSIZE) {
                                  if (dtrace_load8(daddr +
                                      offsetof(dblk_t, db_type)) != M_DATA)
                                          continue;
                          }
  
                          count += wptr - rptr;
                  }
  
                  if (!(*flags & CPU_DTRACE_FAULT))
                          regs[rd] = count;
  
                  break;
          }
  #endif
  
          case DIF_SUBR_PROGENYOF: {
                  pid_t pid = tupregs[0].dttk_value;
                  proc_t *p;
                  int rval = 0;
  
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
  
                  for (p = curthread->t_procp; p != NULL; p = p->p_parent) {
  #ifdef illumos
                          if (p->p_pidp->pid_id == pid) {
  #else
                          if (p->p_pid == pid) {
  #endif
                                  rval = 1;
                                  break;
                          }
                  }
  
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
  
                  regs[rd] = rval;
                  break;
          }
  
          case DIF_SUBR_SPECULATION:
                  regs[rd] = dtrace_speculation(state);
                  break;
  
          case DIF_SUBR_COPYOUT: {
                  uintptr_t kaddr = tupregs[0].dttk_value;
                  uintptr_t uaddr = tupregs[1].dttk_value;
                  uint64_t size = tupregs[2].dttk_value;
  
                  if (!dtrace_destructive_disallow &&
                      dtrace_priv_proc_control(state) &&
                      !dtrace_istoxic(kaddr, size) &&
                      dtrace_canload(kaddr, size, mstate, vstate)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          dtrace_copyout(kaddr, uaddr, size, flags);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  }
                  break;
          }
  
          case DIF_SUBR_COPYOUTSTR: {
                  uintptr_t kaddr = tupregs[0].dttk_value;
                  uintptr_t uaddr = tupregs[1].dttk_value;
                  uint64_t size = tupregs[2].dttk_value;
                  size_t lim;
  
                  if (!dtrace_destructive_disallow &&
                      dtrace_priv_proc_control(state) &&
                      !dtrace_istoxic(kaddr, size) &&
                      dtrace_strcanload(kaddr, size, &lim, mstate, vstate)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          dtrace_copyoutstr(kaddr, uaddr, lim, flags);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                  }
                  break;
          }
  
          case DIF_SUBR_STRLEN: {
                  size_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  uintptr_t addr = (uintptr_t)tupregs[0].dttk_value;
                  size_t lim;
  
                  if (!dtrace_strcanload(addr, size, &lim, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  regs[rd] = dtrace_strlen((char *)addr, lim);
                  break;
          }
  
          case DIF_SUBR_STRCHR:
          case DIF_SUBR_STRRCHR: {
                  /*
                   * We're going to iterate over the string looking for the
                   * specified character.  We will iterate until we have reached
                   * the string length or we have found the character.  If this
                   * is DIF_SUBR_STRRCHR, we will look for the last occurrence
                   * of the specified character instead of the first.
                   */
                  uintptr_t addr = tupregs[0].dttk_value;
                  uintptr_t addr_limit;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  size_t lim;
                  char c, target = (char)tupregs[1].dttk_value;
  
                  if (!dtrace_strcanload(addr, size, &lim, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  addr_limit = addr + lim;
  
                  for (regs[rd] = 0; addr < addr_limit; addr++) {
                          if ((c = dtrace_load8(addr)) == target) {
                                  regs[rd] = addr;
  
                                  if (subr == DIF_SUBR_STRCHR)
                                          break;
                          }
  
                          if (c == '\0')
                                  break;
                  }
                  break;
          }
  
          case DIF_SUBR_STRSTR:
          case DIF_SUBR_INDEX:
          case DIF_SUBR_RINDEX: {
                  /*
                   * We're going to iterate over the string looking for the
                   * specified string.  We will iterate until we have reached
                   * the string length or we have found the string.  (Yes, this
                   * is done in the most naive way possible -- but considering
                   * that the string we're searching for is likely to be
                   * relatively short, the complexity of Rabin-Karp or similar
                   * hardly seems merited.)
                   */
                  char *addr = (char *)(uintptr_t)tupregs[0].dttk_value;
                  char *substr = (char *)(uintptr_t)tupregs[1].dttk_value;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  size_t len = dtrace_strlen(addr, size);
                  size_t sublen = dtrace_strlen(substr, size);
                  char *limit = addr + len, *orig = addr;
                  int notfound = subr == DIF_SUBR_STRSTR ? 0 : -1;
                  int inc = 1;
  
                  regs[rd] = notfound;
  
                  if (!dtrace_canload((uintptr_t)addr, len + 1, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  if (!dtrace_canload((uintptr_t)substr, sublen + 1, mstate,
                      vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  /*
                   * strstr() and index()/rindex() have similar semantics if
                   * both strings are the empty string: strstr() returns a
                   * pointer to the (empty) string, and index() and rindex()
                   * both return index 0 (regardless of any position argument).
                   */
                  if (sublen == 0 && len == 0) {
                          if (subr == DIF_SUBR_STRSTR)
                                  regs[rd] = (uintptr_t)addr;
                          else
                                  regs[rd] = 0;
                          break;
                  }
  
                  if (subr != DIF_SUBR_STRSTR) {
                          if (subr == DIF_SUBR_RINDEX) {
                                  limit = orig - 1;
                                  addr += len;
                                  inc = -1;
                          }
  
                          /*
                           * Both index() and rindex() take an optional position
                           * argument that denotes the starting position.
                           */
                          if (nargs == 3) {
                                  int64_t pos = (int64_t)tupregs[2].dttk_value;
  
                                  /*
                                   * If the position argument to index() is
                                   * negative, Perl implicitly clamps it at
                                   * zero.  This semantic is a little surprising
                                   * given the special meaning of negative
                                   * positions to similar Perl functions like
                                   * substr(), but it appears to reflect a
                                   * notion that index() can start from a
                                   * negative index and increment its way up to
                                   * the string.  Given this notion, Perl's
                                   * rindex() is at least self-consistent in
                                   * that it implicitly clamps positions greater
                                   * than the string length to be the string
                                   * length.  Where Perl completely loses
                                   * coherence, however, is when the specified
                                   * substring is the empty string ("").  In
                                   * this case, even if the position is
                                   * negative, rindex() returns 0 -- and even if
                                   * the position is greater than the length,
                                   * index() returns the string length.  These
                                   * semantics violate the notion that index()
                                   * should never return a value less than the
                                   * specified position and that rindex() should
                                   * never return a value greater than the
                                   * specified position.  (One assumes that
                                   * these semantics are artifacts of Perl's
                                   * implementation and not the results of
                                   * deliberate design -- it beggars belief that
                                   * even Larry Wall could desire such oddness.)
                                   * While in the abstract one would wish for
                                   * consistent position semantics across
                                   * substr(), index() and rindex() -- or at the
                                   * very least self-consistent position
                                   * semantics for index() and rindex() -- we
                                   * instead opt to keep with the extant Perl
                                   * semantics, in all their broken glory.  (Do
                                   * we have more desire to maintain Perl's
                                   * semantics than Perl does?  Probably.)
                                   */
                                  if (subr == DIF_SUBR_RINDEX) {
                                          if (pos < 0) {
                                                  if (sublen == 0)
                                                          regs[rd] = 0;
                                                  break;
                                          }
  
                                          if (pos > len)
                                                  pos = len;
                                  } else {
                                          if (pos < 0)
                                                  pos = 0;
  
                                          if (pos >= len) {
                                                  if (sublen == 0)
                                                          regs[rd] = len;
                                                  break;
                                          }
                                  }
  
                                  addr = orig + pos;
                          }
                  }
  
                  for (regs[rd] = notfound; addr != limit; addr += inc) {
                          if (dtrace_strncmp(addr, substr, sublen) == 0) {
                                  if (subr != DIF_SUBR_STRSTR) {
                                          /*
                                           * As D index() and rindex() are
                                           * modeled on Perl (and not on awk),
                                           * we return a zero-based (and not a
                                           * one-based) index.  (For you Perl
                                           * weenies: no, we're not going to add
                                           * $[ -- and shouldn't you be at a con
                                           * or something?)
                                           */
                                          regs[rd] = (uintptr_t)(addr - orig);
                                          break;
                                  }
  
                                  ASSERT(subr == DIF_SUBR_STRSTR);
                                  regs[rd] = (uintptr_t)addr;
                                  break;
                          }
                  }
  
                  break;
          }
  
          case DIF_SUBR_STRTOK: {
                  uintptr_t addr = tupregs[0].dttk_value;
                  uintptr_t tokaddr = tupregs[1].dttk_value;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  uintptr_t limit, toklimit;
                  size_t clim;
                  uint8_t c = 0, tokmap[32];       /* 256 / 8 */
                  char *dest = (char *)mstate->dtms_scratch_ptr;
                  int i;
  
                  /*
                   * Check both the token buffer and (later) the input buffer,
                   * since both could be non-scratch addresses.
                   */
                  if (!dtrace_strcanload(tokaddr, size, &clim, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
                  toklimit = tokaddr + clim;
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  if (addr == 0) {
                          /*
                           * If the address specified is NULL, we use our saved
                           * strtok pointer from the mstate.  Note that this
                           * means that the saved strtok pointer is _only_
                           * valid within multiple enablings of the same probe --
                           * it behaves like an implicit clause-local variable.
                           */
                          addr = mstate->dtms_strtok;
                          limit = mstate->dtms_strtok_limit;
                  } else {
                          /*
                           * If the user-specified address is non-NULL we must
                           * access check it.  This is the only time we have
                           * a chance to do so, since this address may reside
                           * in the string table of this clause-- future calls
                           * (when we fetch addr from mstate->dtms_strtok)
                           * would fail this access check.
                           */
                          if (!dtrace_strcanload(addr, size, &clim, mstate,
                              vstate)) {
                                  regs[rd] = 0;
                                  break;
                          }
                          limit = addr + clim;
                  }
  
                  /*
                   * First, zero the token map, and then process the token
                   * string -- setting a bit in the map for every character
                   * found in the token string.
                   */
                  for (i = 0; i < sizeof (tokmap); i++)
                          tokmap[i] = 0;
  
                  for (; tokaddr < toklimit; tokaddr++) {
                          if ((c = dtrace_load8(tokaddr)) == '\0')
                                  break;
  
                          ASSERT((c >> 3) < sizeof (tokmap));
                          tokmap[c >> 3] |= (1 << (c & 0x7));
                  }
  
                  for (; addr < limit; addr++) {
                          /*
                           * We're looking for a character that is _not_
                           * contained in the token string.
                           */
                          if ((c = dtrace_load8(addr)) == '\0')
                                  break;
  
                          if (!(tokmap[c >> 3] & (1 << (c & 0x7))))
                                  break;
                  }
  
                  if (c == '\0') {
                          /*
                           * We reached the end of the string without finding
                           * any character that was not in the token string.
                           * We return NULL in this case, and we set the saved
                           * address to NULL as well.
                           */
                          regs[rd] = 0;
                          mstate->dtms_strtok = 0;
                          mstate->dtms_strtok_limit = 0;
                          break;
                  }
  
                  /*
                   * From here on, we're copying into the destination string.
                   */
                  for (i = 0; addr < limit && i < size - 1; addr++) {
                          if ((c = dtrace_load8(addr)) == '\0')
                                  break;
  
                          if (tokmap[c >> 3] & (1 << (c & 0x7)))
                                  break;
  
                          ASSERT(i < size);
                          dest[i++] = c;
                  }
  
                  ASSERT(i < size);
                  dest[i] = '\0';
                  regs[rd] = (uintptr_t)dest;
                  mstate->dtms_scratch_ptr += size;
                  mstate->dtms_strtok = addr;
                  mstate->dtms_strtok_limit = limit;
                  break;
          }
  
          case DIF_SUBR_SUBSTR: {
                  uintptr_t s = tupregs[0].dttk_value;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  char *d = (char *)mstate->dtms_scratch_ptr;
                  int64_t index = (int64_t)tupregs[1].dttk_value;
                  int64_t remaining = (int64_t)tupregs[2].dttk_value;
                  size_t len = dtrace_strlen((char *)s, size);
                  int64_t i;
  
                  if (!dtrace_canload(s, len + 1, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  if (nargs <= 2)
                          remaining = (int64_t)size;
  
                  if (index < 0) {
                          index += len;
  
                          if (index < 0 && index + remaining > 0) {
                                  remaining += index;
                                  index = 0;
                          }
                  }
  
                  if (index >= len || index < 0) {
                          remaining = 0;
                  } else if (remaining < 0) {
                          remaining += len - index;
                  } else if (index + remaining > size) {
                          remaining = size - index;
                  }
  
                  for (i = 0; i < remaining; i++) {
                          if ((d[i] = dtrace_load8(s + index + i)) == '\0')
                                  break;
                  }
  
                  d[i] = '\0';
  
                  mstate->dtms_scratch_ptr += size;
                  regs[rd] = (uintptr_t)d;
                  break;
          }
  
          case DIF_SUBR_JSON: {
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  uintptr_t json = tupregs[0].dttk_value;
                  size_t jsonlen = dtrace_strlen((char *)json, size);
                  uintptr_t elem = tupregs[1].dttk_value;
                  size_t elemlen = dtrace_strlen((char *)elem, size);
  
                  char *dest = (char *)mstate->dtms_scratch_ptr;
                  char *elemlist = (char *)mstate->dtms_scratch_ptr + jsonlen + 1;
                  char *ee = elemlist;
                  int nelems = 1;
                  uintptr_t cur;
  
                  if (!dtrace_canload(json, jsonlen + 1, mstate, vstate) ||
                      !dtrace_canload(elem, elemlen + 1, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  if (!DTRACE_INSCRATCH(mstate, jsonlen + 1 + elemlen + 1)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  /*
                   * Read the element selector and split it up into a packed list
                   * of strings.
                   */
                  for (cur = elem; cur < elem + elemlen; cur++) {
                          char cc = dtrace_load8(cur);
  
                          if (cur == elem && cc == '[') {
                                  /*
                                   * If the first element selector key is
                                   * actually an array index then ignore the
                                   * bracket.
                                   */
                                  continue;
                          }
  
                          if (cc == ']')
                                  continue;
  
                          if (cc == '.' || cc == '[') {
                                  nelems++;
                                  cc = '\0';
                          }
  
                          *ee++ = cc;
                  }
                  *ee++ = '\0';
  
                  if ((regs[rd] = (uintptr_t)dtrace_json(size, json, elemlist,
                      nelems, dest)) != 0)
                          mstate->dtms_scratch_ptr += jsonlen + 1;
                  break;
          }
  
          case DIF_SUBR_TOUPPER:
          case DIF_SUBR_TOLOWER: {
                  uintptr_t s = tupregs[0].dttk_value;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  char *dest = (char *)mstate->dtms_scratch_ptr, c;
                  size_t len = dtrace_strlen((char *)s, size);
                  char lower, upper, convert;
                  int64_t i;
  
                  if (subr == DIF_SUBR_TOUPPER) {
                          lower = 'a';
                          upper = 'z';
                          convert = 'A';
                  } else {
                          lower = 'A';
                          upper = 'Z';
                          convert = 'a';
                  }
  
                  if (!dtrace_canload(s, len + 1, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  for (i = 0; i < size - 1; i++) {
                          if ((c = dtrace_load8(s + i)) == '\0')
                                  break;
  
                          if (c >= lower && c <= upper)
                                  c = convert + (c - lower);
  
                          dest[i] = c;
                  }
  
                  ASSERT(i < size);
                  dest[i] = '\0';
                  regs[rd] = (uintptr_t)dest;
                  mstate->dtms_scratch_ptr += size;
                  break;
          }
  
  #ifdef illumos
          case DIF_SUBR_GETMAJOR:
  #ifdef _LP64
                  regs[rd] = (tupregs[0].dttk_value >> NBITSMINOR64) & MAXMAJ64;
  #else
                  regs[rd] = (tupregs[0].dttk_value >> NBITSMINOR) & MAXMAJ;
  #endif
                  break;
  
          case DIF_SUBR_GETMINOR:
  #ifdef _LP64
                  regs[rd] = tupregs[0].dttk_value & MAXMIN64;
  #else
                  regs[rd] = tupregs[0].dttk_value & MAXMIN;
  #endif
                  break;
  
          case DIF_SUBR_DDI_PATHNAME: {
                  /*
                   * This one is a galactic mess.  We are going to roughly
                   * emulate ddi_pathname(), but it's made more complicated
                   * by the fact that we (a) want to include the minor name and
                   * (b) must proceed iteratively instead of recursively.
                   */
                  uintptr_t dest = mstate->dtms_scratch_ptr;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  char *start = (char *)dest, *end = start + size - 1;
                  uintptr_t daddr = tupregs[0].dttk_value;
                  int64_t minor = (int64_t)tupregs[1].dttk_value;
                  char *s;
                  int i, len, depth = 0;
  
                  /*
                   * Due to all the pointer jumping we do and context we must
                   * rely upon, we just mandate that the user must have kernel
                   * read privileges to use this routine.
                   */
                  if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) == 0) {
                          *flags |= CPU_DTRACE_KPRIV;
                          *illval = daddr;
                          regs[rd] = 0;
                  }
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  *end = '\0';
  
                  /*
                   * We want to have a name for the minor.  In order to do this,
                   * we need to walk the minor list from the devinfo.  We want
                   * to be sure that we don't infinitely walk a circular list,
                   * so we check for circularity by sending a scout pointer
                   * ahead two elements for every element that we iterate over;
                   * if the list is circular, these will ultimately point to the
                   * same element.  You may recognize this little trick as the
                   * answer to a stupid interview question -- one that always
                   * seems to be asked by those who had to have it laboriously
                   * explained to them, and who can't even concisely describe
                   * the conditions under which one would be forced to resort to
                   * this technique.  Needless to say, those conditions are
                   * found here -- and probably only here.  Is this the only use
                   * of this infamous trick in shipping, production code?  If it
                   * isn't, it probably should be...
                   */
                  if (minor != -1) {
                          uintptr_t maddr = dtrace_loadptr(daddr +
                              offsetof(struct dev_info, devi_minor));
  
                          uintptr_t next = offsetof(struct ddi_minor_data, next);
                          uintptr_t name = offsetof(struct ddi_minor_data,
                              d_minor) + offsetof(struct ddi_minor, name);
                          uintptr_t dev = offsetof(struct ddi_minor_data,
                              d_minor) + offsetof(struct ddi_minor, dev);
                          uintptr_t scout;
  
                          if (maddr != NULL)
                                  scout = dtrace_loadptr(maddr + next);
  
                          while (maddr != NULL && !(*flags & CPU_DTRACE_FAULT)) {
                                  uint64_t m;
  #ifdef _LP64
                                  m = dtrace_load64(maddr + dev) & MAXMIN64;
  #else
                                  m = dtrace_load32(maddr + dev) & MAXMIN;
  #endif
                                  if (m != minor) {
                                          maddr = dtrace_loadptr(maddr + next);
  
                                          if (scout == NULL)
                                                  continue;
  
                                          scout = dtrace_loadptr(scout + next);
  
                                          if (scout == NULL)
                                                  continue;
  
                                          scout = dtrace_loadptr(scout + next);
  
                                          if (scout == NULL)
                                                  continue;
  
                                          if (scout == maddr) {
                                                  *flags |= CPU_DTRACE_ILLOP;
                                                  break;
                                          }
  
                                          continue;
                                  }
  
                                  /*
                                   * We have the minor data.  Now we need to
                                   * copy the minor's name into the end of the
                                   * pathname.
                                   */
                                  s = (char *)dtrace_loadptr(maddr + name);
                                  len = dtrace_strlen(s, size);
  
                                  if (*flags & CPU_DTRACE_FAULT)
                                          break;
  
                                  if (len != 0) {
                                          if ((end -= (len + 1)) < start)
                                                  break;
  
                                          *end = ':';
                                  }
  
                                  for (i = 1; i <= len; i++)
                                          end[i] = dtrace_load8((uintptr_t)s++);
                                  break;
                          }
                  }
  
                  while (daddr != NULL && !(*flags & CPU_DTRACE_FAULT)) {
                          ddi_node_state_t devi_state;
  
                          devi_state = dtrace_load32(daddr +
                              offsetof(struct dev_info, devi_node_state));
  
                          if (*flags & CPU_DTRACE_FAULT)
                                  break;
  
                          if (devi_state >= DS_INITIALIZED) {
                                  s = (char *)dtrace_loadptr(daddr +
                                      offsetof(struct dev_info, devi_addr));
                                  len = dtrace_strlen(s, size);
  
                                  if (*flags & CPU_DTRACE_FAULT)
                                          break;
  
                                  if (len != 0) {
                                          if ((end -= (len + 1)) < start)
                                                  break;
  
                                          *end = '@';
                                  }
  
                                  for (i = 1; i <= len; i++)
                                          end[i] = dtrace_load8((uintptr_t)s++);
                          }
  
                          /*
                           * Now for the node name...
                           */
                          s = (char *)dtrace_loadptr(daddr +
                              offsetof(struct dev_info, devi_node_name));
  
                          daddr = dtrace_loadptr(daddr +
                              offsetof(struct dev_info, devi_parent));
  
                          /*
                           * If our parent is NULL (that is, if we're the root
                           * node), we're going to use the special path
                           * "devices".
                           */
                          if (daddr == 0)
                                  s = "devices";
  
                          len = dtrace_strlen(s, size);
                          if (*flags & CPU_DTRACE_FAULT)
                                  break;
  
                          if ((end -= (len + 1)) < start)
                                  break;
  
                          for (i = 1; i <= len; i++)
                                  end[i] = dtrace_load8((uintptr_t)s++);
                          *end = '/';
  
                          if (depth++ > dtrace_devdepth_max) {
                                  *flags |= CPU_DTRACE_ILLOP;
                                  break;
                          }
                  }
  
                  if (end < start)
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
  
                  if (daddr == 0) {
                          regs[rd] = (uintptr_t)end;
                          mstate->dtms_scratch_ptr += size;
                  }
  
                  break;
          }
  #endif
  
          case DIF_SUBR_STRJOIN: {
                  char *d = (char *)mstate->dtms_scratch_ptr;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  uintptr_t s1 = tupregs[0].dttk_value;
                  uintptr_t s2 = tupregs[1].dttk_value;
                  int i = 0, j = 0;
                  size_t lim1, lim2;
                  char c;
  
                  if (!dtrace_strcanload(s1, size, &lim1, mstate, vstate) ||
                      !dtrace_strcanload(s2, size, &lim2, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  for (;;) {
                          if (i >= size) {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                  regs[rd] = 0;
                                  break;
                          }
                          c = (i >= lim1) ? '\0' : dtrace_load8(s1++);
                          if ((d[i++] = c) == '\0') {
                                  i--;
                                  break;
                          }
                  }
  
                  for (;;) {
                          if (i >= size) {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                  regs[rd] = 0;
                                  break;
                          }
  
                          c = (j++ >= lim2) ? '\0' : dtrace_load8(s2++);
                          if ((d[i++] = c) == '\0')
                                  break;
                  }
  
                  if (i < size) {
                          mstate->dtms_scratch_ptr += i;
                          regs[rd] = (uintptr_t)d;
                  }
  
                  break;
          }
  
          case DIF_SUBR_STRTOLL: {
                  uintptr_t s = tupregs[0].dttk_value;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  size_t lim;
                  int base = 10;
  
                  if (nargs > 1) {
                          if ((base = tupregs[1].dttk_value) <= 1 ||
                              base > ('z' - 'a' + 1) + ('9' - '' + 1)) {
                                  *flags |= CPU_DTRACE_ILLOP;
                                  break;
                          }
                  }
  
                  if (!dtrace_strcanload(s, size, &lim, mstate, vstate)) {
                          regs[rd] = INT64_MIN;
                          break;
                  }
  
                  regs[rd] = dtrace_strtoll((char *)s, base, lim);
                  break;
          }
  
          case DIF_SUBR_LLTOSTR: {
                  int64_t i = (int64_t)tupregs[0].dttk_value;
                  uint64_t val, digit;
                  uint64_t size = 65;     /* enough room for 2^64 in binary */
                  char *end = (char *)mstate->dtms_scratch_ptr + size - 1;
                  int base = 10;
  
                  if (nargs > 1) {
                          if ((base = tupregs[1].dttk_value) <= 1 ||
                              base > ('z' - 'a' + 1) + ('9' - '' + 1)) {
                                  *flags |= CPU_DTRACE_ILLOP;
                                  break;
                          }
                  }
  
                  val = (base == 10 && i < 0) ? i * -1 : i;
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  for (*end-- = '\0'; val; val /= base) {
                          if ((digit = val % base) <= '9' - '') {
                                  *end-- = '' + digit;
                          } else {
                                  *end-- = 'a' + (digit - ('9' - '') - 1);
                          }
                  }
  
                  if (i == 0 && base == 16)
                          *end-- = '';
  
                  if (base == 16)
                          *end-- = 'x';
  
                  if (i == 0 || base == 8 || base == 16)
                          *end-- = '';
  
                  if (i < 0 && base == 10)
                          *end-- = '-';
  
                  regs[rd] = (uintptr_t)end + 1;
                  mstate->dtms_scratch_ptr += size;
                  break;
          }
  
          case DIF_SUBR_HTONS:
          case DIF_SUBR_NTOHS:
  #if BYTE_ORDER == BIG_ENDIAN
                  regs[rd] = (uint16_t)tupregs[0].dttk_value;
  #else
                  regs[rd] = DT_BSWAP_16((uint16_t)tupregs[0].dttk_value);
  #endif
                  break;
  
  
          case DIF_SUBR_HTONL:
          case DIF_SUBR_NTOHL:
  #if BYTE_ORDER == BIG_ENDIAN
                  regs[rd] = (uint32_t)tupregs[0].dttk_value;
  #else
                  regs[rd] = DT_BSWAP_32((uint32_t)tupregs[0].dttk_value);
  #endif
                  break;
  
  
          case DIF_SUBR_HTONLL:
          case DIF_SUBR_NTOHLL:
  #if BYTE_ORDER == BIG_ENDIAN
                  regs[rd] = (uint64_t)tupregs[0].dttk_value;
  #else
                  regs[rd] = DT_BSWAP_64((uint64_t)tupregs[0].dttk_value);
  #endif
                  break;
  
  
          case DIF_SUBR_DIRNAME:
          case DIF_SUBR_BASENAME: {
                  char *dest = (char *)mstate->dtms_scratch_ptr;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  uintptr_t src = tupregs[0].dttk_value;
                  int i, j, len = dtrace_strlen((char *)src, size);
                  int lastbase = -1, firstbase = -1, lastdir = -1;
                  int start, end;
  
                  if (!dtrace_canload(src, len + 1, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  /*
                   * The basename and dirname for a zero-length string is
                   * defined to be "."
                   */
                  if (len == 0) {
                          len = 1;
                          src = (uintptr_t)".";
                  }
  
                  /*
                   * Start from the back of the string, moving back toward the
                   * front until we see a character that isn't a slash.  That
                   * character is the last character in the basename.
                   */
                  for (i = len - 1; i >= 0; i--) {
                          if (dtrace_load8(src + i) != '/')
                                  break;
                  }
  
                  if (i >= 0)
                          lastbase = i;
  
                  /*
                   * Starting from the last character in the basename, move
                   * towards the front until we find a slash.  The character
                   * that we processed immediately before that is the first
                   * character in the basename.
                   */
                  for (; i >= 0; i--) {
                          if (dtrace_load8(src + i) == '/')
                                  break;
                  }
  
                  if (i >= 0)
                          firstbase = i + 1;
  
                  /*
                   * Now keep going until we find a non-slash character.  That
                   * character is the last character in the dirname.
                   */
                  for (; i >= 0; i--) {
                          if (dtrace_load8(src + i) != '/')
                                  break;
                  }
  
                  if (i >= 0)
                          lastdir = i;
  
                  ASSERT(!(lastbase == -1 && firstbase != -1));
                  ASSERT(!(firstbase == -1 && lastdir != -1));
  
                  if (lastbase == -1) {
                          /*
                           * We didn't find a non-slash character.  We know that
                           * the length is non-zero, so the whole string must be
                           * slashes.  In either the dirname or the basename
                           * case, we return '/'.
                           */
                          ASSERT(firstbase == -1);
                          firstbase = lastbase = lastdir = 0;
                  }
  
                  if (firstbase == -1) {
                          /*
                           * The entire string consists only of a basename
                           * component.  If we're looking for dirname, we need
                           * to change our string to be just "."; if we're
                           * looking for a basename, we'll just set the first
                           * character of the basename to be 0.
                           */
                          if (subr == DIF_SUBR_DIRNAME) {
                                  ASSERT(lastdir == -1);
                                  src = (uintptr_t)".";
                                  lastdir = 0;
                          } else {
                                  firstbase = 0;
                          }
                  }
  
                  if (subr == DIF_SUBR_DIRNAME) {
                          if (lastdir == -1) {
                                  /*
                                   * We know that we have a slash in the name --
                                   * or lastdir would be set to 0, above.  And
                                   * because lastdir is -1, we know that this
                                   * slash must be the first character.  (That
                                   * is, the full string must be of the form
                                   * "/basename".)  In this case, the last
                                   * character of the directory name is 0.
                                   */
                                  lastdir = 0;
                          }
  
                          start = 0;
                          end = lastdir;
                  } else {
                          ASSERT(subr == DIF_SUBR_BASENAME);
                          ASSERT(firstbase != -1 && lastbase != -1);
                          start = firstbase;
                          end = lastbase;
                  }
  
                  for (i = start, j = 0; i <= end && j < size - 1; i++, j++)
                          dest[j] = dtrace_load8(src + i);
  
                  dest[j] = '\0';
                  regs[rd] = (uintptr_t)dest;
                  mstate->dtms_scratch_ptr += size;
                  break;
          }
  
          case DIF_SUBR_GETF: {
                  uintptr_t fd = tupregs[0].dttk_value;
                  struct filedesc *fdp;
                  file_t *fp;
  
                  if (!dtrace_priv_proc(state)) {
                          regs[rd] = 0;
                          break;
                  }
                  fdp = curproc->p_fd;
                  FILEDESC_SLOCK(fdp);
                  /*
                   * XXXMJG this looks broken as no ref is taken.
                   */
                  fp = fget_noref(fdp, fd);
                  mstate->dtms_getf = fp;
                  regs[rd] = (uintptr_t)fp;
                  FILEDESC_SUNLOCK(fdp);
                  break;
          }
  
          case DIF_SUBR_CLEANPATH: {
                  char *dest = (char *)mstate->dtms_scratch_ptr, c;
                  uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                  uintptr_t src = tupregs[0].dttk_value;
                  size_t lim;
                  int i = 0, j = 0;
  #ifdef illumos
                  zone_t *z;
  #endif
  
                  if (!dtrace_strcanload(src, size, &lim, mstate, vstate)) {
                          regs[rd] = 0;
                          break;
                  }
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          regs[rd] = 0;
                          break;
                  }
  
                  /*
                   * Move forward, loading each character.
                   */
                  do {
                          c = (i >= lim) ? '\0' : dtrace_load8(src + i++);
  next:
                          if (j + 5 >= size)      /* 5 = strlen("/..c\0") */
                                  break;
  
                          if (c != '/') {
                                  dest[j++] = c;
                                  continue;
                          }
  
                          c = (i >= lim) ? '\0' : dtrace_load8(src + i++);
  
                          if (c == '/') {
                                  /*
                                   * We have two slashes -- we can just advance
                                   * to the next character.
                                   */
                                  goto next;
                          }
  
                          if (c != '.') {
                                  /*
                                   * This is not "." and it's not ".." -- we can
                                   * just store the "/" and this character and
                                   * drive on.
                                   */
                                  dest[j++] = '/';
                                  dest[j++] = c;
                                  continue;
                          }
  
                          c = (i >= lim) ? '\0' : dtrace_load8(src + i++);
  
                          if (c == '/') {
                                  /*
                                   * This is a "/./" component.  We're not going
                                   * to store anything in the destination buffer;
                                   * we're just going to go to the next component.
                                   */
                                  goto next;
                          }
  
                          if (c != '.') {
                                  /*
                                   * This is not ".." -- we can just store the
                                   * "/." and this character and continue
                                   * processing.
                                   */
                                  dest[j++] = '/';
                                  dest[j++] = '.';
                                  dest[j++] = c;
                                  continue;
                          }
  
                          c = (i >= lim) ? '\0' : dtrace_load8(src + i++);
  
                          if (c != '/' && c != '\0') {
                                  /*
                                   * This is not ".." -- it's "..[mumble]".
                                   * We'll store the "/.." and this character
                                   * and continue processing.
                                   */
                                  dest[j++] = '/';
                                  dest[j++] = '.';
                                  dest[j++] = '.';
                                  dest[j++] = c;
                                  continue;
                          }
  
                          /*
                           * This is "/../" or "/..\0".  We need to back up
                           * our destination pointer until we find a "/".
                           */
                          i--;
                          while (j != 0 && dest[--j] != '/')
                                  continue;
  
                          if (c == '\0')
                                  dest[++j] = '/';
                  } while (c != '\0');
  
                  dest[j] = '\0';
  
  #ifdef illumos
                  if (mstate->dtms_getf != NULL &&
                      !(mstate->dtms_access & DTRACE_ACCESS_KERNEL) &&
                      (z = state->dts_cred.dcr_cred->cr_zone) != kcred->cr_zone) {
                          /*
                           * If we've done a getf() as a part of this ECB and we
                           * don't have kernel access (and we're not in the global
                           * zone), check if the path we cleaned up begins with
                           * the zone's root path, and trim it off if so.  Note
                           * that this is an output cleanliness issue, not a
                           * security issue: knowing one's zone root path does
                           * not enable privilege escalation.
                           */
                          if (strstr(dest, z->zone_rootpath) == dest)
                                  dest += strlen(z->zone_rootpath) - 1;
                  }
  #endif
  
                  regs[rd] = (uintptr_t)dest;
                  mstate->dtms_scratch_ptr += size;
                  break;
          }
  
          case DIF_SUBR_INET_NTOA:
          case DIF_SUBR_INET_NTOA6:
          case DIF_SUBR_INET_NTOP: {
                  size_t size;
                  int af, argi, i;
                  char *base, *end;
  
                  if (subr == DIF_SUBR_INET_NTOP) {
                          af = (int)tupregs[0].dttk_value;
                          argi = 1;
                  } else {
                          af = subr == DIF_SUBR_INET_NTOA ? AF_INET: AF_INET6;
                          argi = 0;
                  }
  
                  if (af == AF_INET) {
                          ipaddr_t ip4;
                          uint8_t *ptr8, val;
  
                          if (!dtrace_canload(tupregs[argi].dttk_value,
                              sizeof (ipaddr_t), mstate, vstate)) {
                                  regs[rd] = 0;
                                  break;
                          }
  
                          /*
                           * Safely load the IPv4 address.
                           */
                          ip4 = dtrace_load32(tupregs[argi].dttk_value);
  
                          /*
                           * Check an IPv4 string will fit in scratch.
                           */
                          size = INET_ADDRSTRLEN;
                          if (!DTRACE_INSCRATCH(mstate, size)) {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                  regs[rd] = 0;
                                  break;
                          }
                          base = (char *)mstate->dtms_scratch_ptr;
                          end = (char *)mstate->dtms_scratch_ptr + size - 1;
  
                          /*
                           * Stringify as a dotted decimal quad.
                           */
                          *end-- = '\0';
                          ptr8 = (uint8_t *)&ip4;
                          for (i = 3; i >= 0; i--) {
                                  val = ptr8[i];
  
                                  if (val == 0) {
                                          *end-- = '';
                                  } else {
                                          for (; val; val /= 10) {
                                                  *end-- = '' + (val % 10);
                                          }
                                  }
  
                                  if (i > 0)
                                          *end-- = '.';
                          }
                          ASSERT(end + 1 >= base);
  
                  } else if (af == AF_INET6) {
                          struct in6_addr ip6;
                          int firstzero, tryzero, numzero, v6end;
                          uint16_t val;
                          const char digits[] = "0123456789abcdef";
  
                          /*
                           * Stringify using RFC 1884 convention 2 - 16 bit
                           * hexadecimal values with a zero-run compression.
                           * Lower case hexadecimal digits are used.
                           *      eg, fe80::214:4fff:fe0b:76c8.
                           * The IPv4 embedded form is returned for inet_ntop,
                           * just the IPv4 string is returned for inet_ntoa6.
                           */
  
                          if (!dtrace_canload(tupregs[argi].dttk_value,
                              sizeof (struct in6_addr), mstate, vstate)) {
                                  regs[rd] = 0;
                                  break;
                          }
  
                          /*
                           * Safely load the IPv6 address.
                           */
                          dtrace_bcopy(
                              (void *)(uintptr_t)tupregs[argi].dttk_value,
                              (void *)(uintptr_t)&ip6, sizeof (struct in6_addr));
  
                          /*
                           * Check an IPv6 string will fit in scratch.
                           */
                          size = INET6_ADDRSTRLEN;
                          if (!DTRACE_INSCRATCH(mstate, size)) {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                  regs[rd] = 0;
                                  break;
                          }
                          base = (char *)mstate->dtms_scratch_ptr;
                          end = (char *)mstate->dtms_scratch_ptr + size - 1;
                          *end-- = '\0';
  
                          /*
                           * Find the longest run of 16 bit zero values
                           * for the single allowed zero compression - "::".
                           */
                          firstzero = -1;
                          tryzero = -1;
                          numzero = 1;
                          for (i = 0; i < sizeof (struct in6_addr); i++) {
  #ifdef illumos
                                  if (ip6._S6_un._S6_u8[i] == 0 &&
  #else
                                  if (ip6.__u6_addr.__u6_addr8[i] == 0 &&
  #endif
                                      tryzero == -1 && i % 2 == 0) {
                                          tryzero = i;
                                          continue;
                                  }
  
                                  if (tryzero != -1 &&
  #ifdef illumos
                                      (ip6._S6_un._S6_u8[i] != 0 ||
  #else
                                      (ip6.__u6_addr.__u6_addr8[i] != 0 ||
  #endif
                                      i == sizeof (struct in6_addr) - 1)) {
  
                                          if (i - tryzero <= numzero) {
                                                  tryzero = -1;
                                                  continue;
                                          }
  
                                          firstzero = tryzero;
                                          numzero = i - i % 2 - tryzero;
                                          tryzero = -1;
  
  #ifdef illumos
                                          if (ip6._S6_un._S6_u8[i] == 0 &&
  #else
                                          if (ip6.__u6_addr.__u6_addr8[i] == 0 &&
  #endif
                                              i == sizeof (struct in6_addr) - 1)
                                                  numzero += 2;
                                  }
                          }
                          ASSERT(firstzero + numzero <= sizeof (struct in6_addr));
  
                          /*
                           * Check for an IPv4 embedded address.
                           */
                          v6end = sizeof (struct in6_addr) - 2;
                          if (IN6_IS_ADDR_V4MAPPED(&ip6) ||
                              IN6_IS_ADDR_V4COMPAT(&ip6)) {
                                  for (i = sizeof (struct in6_addr) - 1;
                                      i >= DTRACE_V4MAPPED_OFFSET; i--) {
                                          ASSERT(end >= base);
  
  #ifdef illumos
                                          val = ip6._S6_un._S6_u8[i];
  #else
                                          val = ip6.__u6_addr.__u6_addr8[i];
  #endif
  
                                          if (val == 0) {
                                                  *end-- = '';
                                          } else {
                                                  for (; val; val /= 10) {
                                                          *end-- = '' + val % 10;
                                                  }
                                          }
  
                                          if (i > DTRACE_V4MAPPED_OFFSET)
                                                  *end-- = '.';
                                  }
  
                                  if (subr == DIF_SUBR_INET_NTOA6)
                                          goto inetout;
  
                                  /*
                                   * Set v6end to skip the IPv4 address that
                                   * we have already stringified.
                                   */
                                  v6end = 10;
                          }
  
                          /*
                           * Build the IPv6 string by working through the
                           * address in reverse.
                           */
                          for (i = v6end; i >= 0; i -= 2) {
                                  ASSERT(end >= base);
  
                                  if (i == firstzero + numzero - 2) {
                                          *end-- = ':';
                                          *end-- = ':';
                                          i -= numzero - 2;
                                          continue;
                                  }
  
                                  if (i < 14 && i != firstzero - 2)
                                          *end-- = ':';
  
  #ifdef illumos
                                  val = (ip6._S6_un._S6_u8[i] << 8) +
                                      ip6._S6_un._S6_u8[i + 1];
  #else
                                  val = (ip6.__u6_addr.__u6_addr8[i] << 8) +
                                      ip6.__u6_addr.__u6_addr8[i + 1];
  #endif
  
                                  if (val == 0) {
                                          *end-- = '';
                                  } else {
                                          for (; val; val /= 16) {
                                                  *end-- = digits[val % 16];
                                          }
                                  }
                          }
                          ASSERT(end + 1 >= base);
  
                  } else {
                          /*
                           * The user didn't use AH_INET or AH_INET6.
                           */
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                          regs[rd] = 0;
                          break;
                  }
  
  inetout:        regs[rd] = (uintptr_t)end + 1;
                  mstate->dtms_scratch_ptr += size;
                  break;
          }
  
          case DIF_SUBR_MEMREF: {
                  uintptr_t size = 2 * sizeof(uintptr_t);
                  uintptr_t *memref = (uintptr_t *) P2ROUNDUP(mstate->dtms_scratch_ptr, sizeof(uintptr_t));
                  size_t scratch_size = ((uintptr_t) memref - mstate->dtms_scratch_ptr) + size;
  
                  /* address and length */
                  memref[0] = tupregs[0].dttk_value;
                  memref[1] = tupregs[1].dttk_value;
  
                  regs[rd] = (uintptr_t) memref;
                  mstate->dtms_scratch_ptr += scratch_size;
                  break;
          }
  
  #ifndef illumos
          case DIF_SUBR_MEMSTR: {
                  char *str = (char *)mstate->dtms_scratch_ptr;
                  uintptr_t mem = tupregs[0].dttk_value;
                  char c = tupregs[1].dttk_value;
                  size_t size = tupregs[2].dttk_value;
                  uint8_t n;
                  int i;
  
                  regs[rd] = 0;
  
                  if (size == 0)
                          break;
  
                  if (!dtrace_canload(mem, size - 1, mstate, vstate))
                          break;
  
                  if (!DTRACE_INSCRATCH(mstate, size)) {
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                          break;
                  }
  
                  if (dtrace_memstr_max != 0 && size > dtrace_memstr_max) {
                          *flags |= CPU_DTRACE_ILLOP;
                          break;
                  }
  
                  for (i = 0; i < size - 1; i++) {
                          n = dtrace_load8(mem++);
                          str[i] = (n == 0) ? c : n;
                  }
                  str[size - 1] = 0;
  
                  regs[rd] = (uintptr_t)str;
                  mstate->dtms_scratch_ptr += size;
                  break;
          }
  #endif
          }
  }
  
  /*
   * Emulate the execution of DTrace IR instructions specified by the given
   * DIF object.  This function is deliberately void of assertions as all of
   * the necessary checks are handled by a call to dtrace_difo_validate().
   */
  static uint64_t
  dtrace_dif_emulate(dtrace_difo_t *difo, dtrace_mstate_t *mstate,
      dtrace_vstate_t *vstate, dtrace_state_t *state)
  {
          const dif_instr_t *text = difo->dtdo_buf;
          const uint_t textlen = difo->dtdo_len;
          const char *strtab = difo->dtdo_strtab;
          const uint64_t *inttab = difo->dtdo_inttab;
  
          uint64_t rval = 0;
          dtrace_statvar_t *svar;
          dtrace_dstate_t *dstate = &vstate->dtvs_dynvars;
          dtrace_difv_t *v;
          volatile uint16_t *flags = &cpu_core[curcpu].cpuc_dtrace_flags;
          volatile uintptr_t *illval = &cpu_core[curcpu].cpuc_dtrace_illval;
  
          dtrace_key_t tupregs[DIF_DTR_NREGS + 2]; /* +2 for thread and id */
          uint64_t regs[DIF_DIR_NREGS];
          uint64_t *tmp;
  
          uint8_t cc_n = 0, cc_z = 0, cc_v = 0, cc_c = 0;
          int64_t cc_r;
          uint_t pc = 0, id, opc = 0;
          uint8_t ttop = 0;
          dif_instr_t instr;
          uint_t r1, r2, rd;
  
          /*
           * We stash the current DIF object into the machine state: we need it
           * for subsequent access checking.
           */
          mstate->dtms_difo = difo;
  
          regs[DIF_REG_R0] = 0;           /* %r0 is fixed at zero */
  
          while (pc < textlen && !(*flags & CPU_DTRACE_FAULT)) {
                  opc = pc;
  
                  instr = text[pc++];
                  r1 = DIF_INSTR_R1(instr);
                  r2 = DIF_INSTR_R2(instr);
                  rd = DIF_INSTR_RD(instr);
  
                  switch (DIF_INSTR_OP(instr)) {
                  case DIF_OP_OR:
                          regs[rd] = regs[r1] | regs[r2];
                          break;
                  case DIF_OP_XOR:
                          regs[rd] = regs[r1] ^ regs[r2];
                          break;
                  case DIF_OP_AND:
                          regs[rd] = regs[r1] & regs[r2];
                          break;
                  case DIF_OP_SLL:
                          regs[rd] = regs[r1] << regs[r2];
                          break;
                  case DIF_OP_SRL:
                          regs[rd] = regs[r1] >> regs[r2];
                          break;
                  case DIF_OP_SUB:
                          regs[rd] = regs[r1] - regs[r2];
                          break;
                  case DIF_OP_ADD:
                          regs[rd] = regs[r1] + regs[r2];
                          break;
                  case DIF_OP_MUL:
                          regs[rd] = regs[r1] * regs[r2];
                          break;
                  case DIF_OP_SDIV:
                          if (regs[r2] == 0) {
                                  regs[rd] = 0;
                                  *flags |= CPU_DTRACE_DIVZERO;
                          } else {
                                  regs[rd] = (int64_t)regs[r1] /
                                      (int64_t)regs[r2];
                          }
                          break;
  
                  case DIF_OP_UDIV:
                          if (regs[r2] == 0) {
                                  regs[rd] = 0;
                                  *flags |= CPU_DTRACE_DIVZERO;
                          } else {
                                  regs[rd] = regs[r1] / regs[r2];
                          }
                          break;
  
                  case DIF_OP_SREM:
                          if (regs[r2] == 0) {
                                  regs[rd] = 0;
                                  *flags |= CPU_DTRACE_DIVZERO;
                          } else {
                                  regs[rd] = (int64_t)regs[r1] %
                                      (int64_t)regs[r2];
                          }
                          break;
  
                  case DIF_OP_UREM:
                          if (regs[r2] == 0) {
                                  regs[rd] = 0;
                                  *flags |= CPU_DTRACE_DIVZERO;
                          } else {
                                  regs[rd] = regs[r1] % regs[r2];
                          }
                          break;
  
                  case DIF_OP_NOT:
                          regs[rd] = ~regs[r1];
                          break;
                  case DIF_OP_MOV:
                          regs[rd] = regs[r1];
                          break;
                  case DIF_OP_CMP:
                          cc_r = regs[r1] - regs[r2];
                          cc_n = cc_r < 0;
                          cc_z = cc_r == 0;
                          cc_v = 0;
                          cc_c = regs[r1] < regs[r2];
                          break;
                  case DIF_OP_TST:
                          cc_n = cc_v = cc_c = 0;
                          cc_z = regs[r1] == 0;
                          break;
                  case DIF_OP_BA:
                          pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BE:
                          if (cc_z)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BNE:
                          if (cc_z == 0)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BG:
                          if ((cc_z | (cc_n ^ cc_v)) == 0)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BGU:
                          if ((cc_c | cc_z) == 0)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BGE:
                          if ((cc_n ^ cc_v) == 0)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BGEU:
                          if (cc_c == 0)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BL:
                          if (cc_n ^ cc_v)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BLU:
                          if (cc_c)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BLE:
                          if (cc_z | (cc_n ^ cc_v))
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_BLEU:
                          if (cc_c | cc_z)
                                  pc = DIF_INSTR_LABEL(instr);
                          break;
                  case DIF_OP_RLDSB:
                          if (!dtrace_canload(regs[r1], 1, mstate, vstate))
                                  break;
                          /*FALLTHROUGH*/
                  case DIF_OP_LDSB:
                          regs[rd] = (int8_t)dtrace_load8(regs[r1]);
                          break;
                  case DIF_OP_RLDSH:
                          if (!dtrace_canload(regs[r1], 2, mstate, vstate))
                                  break;
                          /*FALLTHROUGH*/
                  case DIF_OP_LDSH:
                          regs[rd] = (int16_t)dtrace_load16(regs[r1]);
                          break;
                  case DIF_OP_RLDSW:
                          if (!dtrace_canload(regs[r1], 4, mstate, vstate))
                                  break;
                          /*FALLTHROUGH*/
                  case DIF_OP_LDSW:
                          regs[rd] = (int32_t)dtrace_load32(regs[r1]);
                          break;
                  case DIF_OP_RLDUB:
                          if (!dtrace_canload(regs[r1], 1, mstate, vstate))
                                  break;
                          /*FALLTHROUGH*/
                  case DIF_OP_LDUB:
                          regs[rd] = dtrace_load8(regs[r1]);
                          break;
                  case DIF_OP_RLDUH:
                          if (!dtrace_canload(regs[r1], 2, mstate, vstate))
                                  break;
                          /*FALLTHROUGH*/
                  case DIF_OP_LDUH:
                          regs[rd] = dtrace_load16(regs[r1]);
                          break;
                  case DIF_OP_RLDUW:
                          if (!dtrace_canload(regs[r1], 4, mstate, vstate))
                                  break;
                          /*FALLTHROUGH*/
                  case DIF_OP_LDUW:
                          regs[rd] = dtrace_load32(regs[r1]);
                          break;
                  case DIF_OP_RLDX:
                          if (!dtrace_canload(regs[r1], 8, mstate, vstate))
                                  break;
                          /*FALLTHROUGH*/
                  case DIF_OP_LDX:
                          regs[rd] = dtrace_load64(regs[r1]);
                          break;
                  case DIF_OP_ULDSB:
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          regs[rd] = (int8_t)
                              dtrace_fuword8((void *)(uintptr_t)regs[r1]);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          break;
                  case DIF_OP_ULDSH:
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          regs[rd] = (int16_t)
                              dtrace_fuword16((void *)(uintptr_t)regs[r1]);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          break;
                  case DIF_OP_ULDSW:
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          regs[rd] = (int32_t)
                              dtrace_fuword32((void *)(uintptr_t)regs[r1]);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          break;
                  case DIF_OP_ULDUB:
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          regs[rd] =
                              dtrace_fuword8((void *)(uintptr_t)regs[r1]);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          break;
                  case DIF_OP_ULDUH:
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          regs[rd] =
                              dtrace_fuword16((void *)(uintptr_t)regs[r1]);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          break;
                  case DIF_OP_ULDUW:
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          regs[rd] =
                              dtrace_fuword32((void *)(uintptr_t)regs[r1]);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          break;
                  case DIF_OP_ULDX:
                          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                          regs[rd] =
                              dtrace_fuword64((void *)(uintptr_t)regs[r1]);
                          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                          break;
                  case DIF_OP_RET:
                          rval = regs[rd];
                          pc = textlen;
                          break;
                  case DIF_OP_NOP:
                          break;
                  case DIF_OP_SETX:
                          regs[rd] = inttab[DIF_INSTR_INTEGER(instr)];
                          break;
                  case DIF_OP_SETS:
                          regs[rd] = (uint64_t)(uintptr_t)
                              (strtab + DIF_INSTR_STRING(instr));
                          break;
                  case DIF_OP_SCMP: {
                          size_t sz = state->dts_options[DTRACEOPT_STRSIZE];
                          uintptr_t s1 = regs[r1];
                          uintptr_t s2 = regs[r2];
                          size_t lim1, lim2;
  
                          /*
                           * If one of the strings is NULL then the limit becomes
                           * 0 which compares 0 characters in dtrace_strncmp()
                           * resulting in a false positive.  dtrace_strncmp()
                           * treats a NULL as an empty 1-char string.
                           */
                          lim1 = lim2 = 1;
  
                          if (s1 != 0 &&
                              !dtrace_strcanload(s1, sz, &lim1, mstate, vstate))
                                  break;
                          if (s2 != 0 &&
                              !dtrace_strcanload(s2, sz, &lim2, mstate, vstate))
                                  break;
  
                          cc_r = dtrace_strncmp((char *)s1, (char *)s2,
                              MIN(lim1, lim2));
  
                          cc_n = cc_r < 0;
                          cc_z = cc_r == 0;
                          cc_v = cc_c = 0;
                          break;
                  }
                  case DIF_OP_LDGA:
                          regs[rd] = dtrace_dif_variable(mstate, state,
                              r1, regs[r2]);
                          break;
                  case DIF_OP_LDGS:
                          id = DIF_INSTR_VAR(instr);
  
                          if (id >= DIF_VAR_OTHER_UBASE) {
                                  uintptr_t a;
  
                                  id -= DIF_VAR_OTHER_UBASE;
                                  svar = vstate->dtvs_globals[id];
                                  ASSERT(svar != NULL);
                                  v = &svar->dtsv_var;
  
                                  if (!(v->dtdv_type.dtdt_flags & DIF_TF_BYREF)) {
                                          regs[rd] = svar->dtsv_data;
                                          break;
                                  }
  
                                  a = (uintptr_t)svar->dtsv_data;
  
                                  if (*(uint8_t *)a == UINT8_MAX) {
                                          /*
                                           * If the 0th byte is set to UINT8_MAX
                                           * then this is to be treated as a
                                           * reference to a NULL variable.
                                           */
                                          regs[rd] = 0;
                                  } else {
                                          regs[rd] = a + sizeof (uint64_t);
                                  }
  
                                  break;
                          }
  
                          regs[rd] = dtrace_dif_variable(mstate, state, id, 0);
                          break;
  
                  case DIF_OP_STGS:
                          id = DIF_INSTR_VAR(instr);
  
                          ASSERT(id >= DIF_VAR_OTHER_UBASE);
                          id -= DIF_VAR_OTHER_UBASE;
  
                          VERIFY(id < vstate->dtvs_nglobals);
                          svar = vstate->dtvs_globals[id];
                          ASSERT(svar != NULL);
                          v = &svar->dtsv_var;
  
                          if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                  uintptr_t a = (uintptr_t)svar->dtsv_data;
                                  size_t lim;
  
                                  ASSERT(a != 0);
                                  ASSERT(svar->dtsv_size != 0);
  
                                  if (regs[rd] == 0) {
                                          *(uint8_t *)a = UINT8_MAX;
                                          break;
                                  } else {
                                          *(uint8_t *)a = 0;
                                          a += sizeof (uint64_t);
                                  }
                                  if (!dtrace_vcanload(
                                      (void *)(uintptr_t)regs[rd], &v->dtdv_type,
                                      &lim, mstate, vstate))
                                          break;
  
                                  dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                      (void *)a, &v->dtdv_type, lim);
                                  break;
                          }
  
                          svar->dtsv_data = regs[rd];
                          break;
  
                  case DIF_OP_LDTA:
                          /*
                           * There are no DTrace built-in thread-local arrays at
                           * present.  This opcode is saved for future work.
                           */
                          *flags |= CPU_DTRACE_ILLOP;
                          regs[rd] = 0;
                          break;
  
                  case DIF_OP_LDLS:
                          id = DIF_INSTR_VAR(instr);
  
                          if (id < DIF_VAR_OTHER_UBASE) {
                                  /*
                                   * For now, this has no meaning.
                                   */
                                  regs[rd] = 0;
                                  break;
                          }
  
                          id -= DIF_VAR_OTHER_UBASE;
  
                          ASSERT(id < vstate->dtvs_nlocals);
                          ASSERT(vstate->dtvs_locals != NULL);
  
                          svar = vstate->dtvs_locals[id];
                          ASSERT(svar != NULL);
                          v = &svar->dtsv_var;
  
                          if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                  uintptr_t a = (uintptr_t)svar->dtsv_data;
                                  size_t sz = v->dtdv_type.dtdt_size;
                                  size_t lim;
  
                                  sz += sizeof (uint64_t);
                                  ASSERT(svar->dtsv_size == NCPU * sz);
                                  a += curcpu * sz;
  
                                  if (*(uint8_t *)a == UINT8_MAX) {
                                          /*
                                           * If the 0th byte is set to UINT8_MAX
                                           * then this is to be treated as a
                                           * reference to a NULL variable.
                                           */
                                          regs[rd] = 0;
                                  } else {
                                          regs[rd] = a + sizeof (uint64_t);
                                  }
  
                                  break;
                          }
  
                          ASSERT(svar->dtsv_size == NCPU * sizeof (uint64_t));
                          tmp = (uint64_t *)(uintptr_t)svar->dtsv_data;
                          regs[rd] = tmp[curcpu];
                          break;
  
                  case DIF_OP_STLS:
                          id = DIF_INSTR_VAR(instr);
  
                          ASSERT(id >= DIF_VAR_OTHER_UBASE);
                          id -= DIF_VAR_OTHER_UBASE;
                          VERIFY(id < vstate->dtvs_nlocals);
  
                          ASSERT(vstate->dtvs_locals != NULL);
                          svar = vstate->dtvs_locals[id];
                          ASSERT(svar != NULL);
                          v = &svar->dtsv_var;
  
                          if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                  uintptr_t a = (uintptr_t)svar->dtsv_data;
                                  size_t sz = v->dtdv_type.dtdt_size;
                                  size_t lim;
  
                                  sz += sizeof (uint64_t);
                                  ASSERT(svar->dtsv_size == NCPU * sz);
                                  a += curcpu * sz;
  
                                  if (regs[rd] == 0) {
                                          *(uint8_t *)a = UINT8_MAX;
                                          break;
                                  } else {
                                          *(uint8_t *)a = 0;
                                          a += sizeof (uint64_t);
                                  }
  
                                  if (!dtrace_vcanload(
                                      (void *)(uintptr_t)regs[rd], &v->dtdv_type,
                                      &lim, mstate, vstate))
                                          break;
  
                                  dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                      (void *)a, &v->dtdv_type, lim);
                                  break;
                          }
  
                          ASSERT(svar->dtsv_size == NCPU * sizeof (uint64_t));
                          tmp = (uint64_t *)(uintptr_t)svar->dtsv_data;
                          tmp[curcpu] = regs[rd];
                          break;
  
                  case DIF_OP_LDTS: {
                          dtrace_dynvar_t *dvar;
                          dtrace_key_t *key;
  
                          id = DIF_INSTR_VAR(instr);
                          ASSERT(id >= DIF_VAR_OTHER_UBASE);
                          id -= DIF_VAR_OTHER_UBASE;
                          v = &vstate->dtvs_tlocals[id];
  
                          key = &tupregs[DIF_DTR_NREGS];
                          key[0].dttk_value = (uint64_t)id;
                          key[0].dttk_size = 0;
                          DTRACE_TLS_THRKEY(key[1].dttk_value);
                          key[1].dttk_size = 0;
  
                          dvar = dtrace_dynvar(dstate, 2, key,
                              sizeof (uint64_t), DTRACE_DYNVAR_NOALLOC,
                              mstate, vstate);
  
                          if (dvar == NULL) {
                                  regs[rd] = 0;
                                  break;
                          }
  
                          if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                  regs[rd] = (uint64_t)(uintptr_t)dvar->dtdv_data;
                          } else {
                                  regs[rd] = *((uint64_t *)dvar->dtdv_data);
                          }
  
                          break;
                  }
  
                  case DIF_OP_STTS: {
                          dtrace_dynvar_t *dvar;
                          dtrace_key_t *key;
  
                          id = DIF_INSTR_VAR(instr);
                          ASSERT(id >= DIF_VAR_OTHER_UBASE);
                          id -= DIF_VAR_OTHER_UBASE;
                          VERIFY(id < vstate->dtvs_ntlocals);
  
                          key = &tupregs[DIF_DTR_NREGS];
                          key[0].dttk_value = (uint64_t)id;
                          key[0].dttk_size = 0;
                          DTRACE_TLS_THRKEY(key[1].dttk_value);
                          key[1].dttk_size = 0;
                          v = &vstate->dtvs_tlocals[id];
  
                          dvar = dtrace_dynvar(dstate, 2, key,
                              v->dtdv_type.dtdt_size > sizeof (uint64_t) ?
                              v->dtdv_type.dtdt_size : sizeof (uint64_t),
                              regs[rd] ? DTRACE_DYNVAR_ALLOC :
                              DTRACE_DYNVAR_DEALLOC, mstate, vstate);
  
                          /*
                           * Given that we're storing to thread-local data,
                           * we need to flush our predicate cache.
                           */
                          curthread->t_predcache = 0;
  
                          if (dvar == NULL)
                                  break;
  
                          if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                  size_t lim;
  
                                  if (!dtrace_vcanload(
                                      (void *)(uintptr_t)regs[rd],
                                      &v->dtdv_type, &lim, mstate, vstate))
                                          break;
  
                                  dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                      dvar->dtdv_data, &v->dtdv_type, lim);
                          } else {
                                  *((uint64_t *)dvar->dtdv_data) = regs[rd];
                          }
  
                          break;
                  }
  
                  case DIF_OP_SRA:
                          regs[rd] = (int64_t)regs[r1] >> regs[r2];
                          break;
  
                  case DIF_OP_CALL:
                          dtrace_dif_subr(DIF_INSTR_SUBR(instr), rd,
                              regs, tupregs, ttop, mstate, state);
                          break;
  
                  case DIF_OP_PUSHTR:
                          if (ttop == DIF_DTR_NREGS) {
                                  *flags |= CPU_DTRACE_TUPOFLOW;
                                  break;
                          }
  
                          if (r1 == DIF_TYPE_STRING) {
                                  /*
                                   * If this is a string type and the size is 0,
                                   * we'll use the system-wide default string
                                   * size.  Note that we are _not_ looking at
                                   * the value of the DTRACEOPT_STRSIZE option;
                                   * had this been set, we would expect to have
                                   * a non-zero size value in the "pushtr".
                                   */
                                  tupregs[ttop].dttk_size =
                                      dtrace_strlen((char *)(uintptr_t)regs[rd],
                                      regs[r2] ? regs[r2] :
                                      dtrace_strsize_default) + 1;
                          } else {
                                  if (regs[r2] > LONG_MAX) {
                                          *flags |= CPU_DTRACE_ILLOP;
                                          break;
                                  }
  
                                  tupregs[ttop].dttk_size = regs[r2];
                          }
  
                          tupregs[ttop++].dttk_value = regs[rd];
                          break;
  
                  case DIF_OP_PUSHTV:
                          if (ttop == DIF_DTR_NREGS) {
                                  *flags |= CPU_DTRACE_TUPOFLOW;
                                  break;
                          }
  
                          tupregs[ttop].dttk_value = regs[rd];
                          tupregs[ttop++].dttk_size = 0;
                          break;
  
                  case DIF_OP_POPTS:
                          if (ttop != 0)
                                  ttop--;
                          break;
  
                  case DIF_OP_FLUSHTS:
                          ttop = 0;
                          break;
  
                  case DIF_OP_LDGAA:
                  case DIF_OP_LDTAA: {
                          dtrace_dynvar_t *dvar;
                          dtrace_key_t *key = tupregs;
                          uint_t nkeys = ttop;
  
                          id = DIF_INSTR_VAR(instr);
                          ASSERT(id >= DIF_VAR_OTHER_UBASE);
                          id -= DIF_VAR_OTHER_UBASE;
  
                          key[nkeys].dttk_value = (uint64_t)id;
                          key[nkeys++].dttk_size = 0;
  
                          if (DIF_INSTR_OP(instr) == DIF_OP_LDTAA) {
                                  DTRACE_TLS_THRKEY(key[nkeys].dttk_value);
                                  key[nkeys++].dttk_size = 0;
                                  VERIFY(id < vstate->dtvs_ntlocals);
                                  v = &vstate->dtvs_tlocals[id];
                          } else {
                                  VERIFY(id < vstate->dtvs_nglobals);
                                  v = &vstate->dtvs_globals[id]->dtsv_var;
                          }
  
                          dvar = dtrace_dynvar(dstate, nkeys, key,
                              v->dtdv_type.dtdt_size > sizeof (uint64_t) ?
                              v->dtdv_type.dtdt_size : sizeof (uint64_t),
                              DTRACE_DYNVAR_NOALLOC, mstate, vstate);
  
                          if (dvar == NULL) {
                                  regs[rd] = 0;
                                  break;
                          }
  
                          if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                  regs[rd] = (uint64_t)(uintptr_t)dvar->dtdv_data;
                          } else {
                                  regs[rd] = *((uint64_t *)dvar->dtdv_data);
                          }
  
                          break;
                  }
  
                  case DIF_OP_STGAA:
                  case DIF_OP_STTAA: {
                          dtrace_dynvar_t *dvar;
                          dtrace_key_t *key = tupregs;
                          uint_t nkeys = ttop;
  
                          id = DIF_INSTR_VAR(instr);
                          ASSERT(id >= DIF_VAR_OTHER_UBASE);
                          id -= DIF_VAR_OTHER_UBASE;
  
                          key[nkeys].dttk_value = (uint64_t)id;
                          key[nkeys++].dttk_size = 0;
  
                          if (DIF_INSTR_OP(instr) == DIF_OP_STTAA) {
                                  DTRACE_TLS_THRKEY(key[nkeys].dttk_value);
                                  key[nkeys++].dttk_size = 0;
                                  VERIFY(id < vstate->dtvs_ntlocals);
                                  v = &vstate->dtvs_tlocals[id];
                          } else {
                                  VERIFY(id < vstate->dtvs_nglobals);
                                  v = &vstate->dtvs_globals[id]->dtsv_var;
                          }
  
                          dvar = dtrace_dynvar(dstate, nkeys, key,
                              v->dtdv_type.dtdt_size > sizeof (uint64_t) ?
                              v->dtdv_type.dtdt_size : sizeof (uint64_t),
                              regs[rd] ? DTRACE_DYNVAR_ALLOC :
                              DTRACE_DYNVAR_DEALLOC, mstate, vstate);
  
                          if (dvar == NULL)
                                  break;
  
                          if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                  size_t lim;
  
                                  if (!dtrace_vcanload(
                                      (void *)(uintptr_t)regs[rd], &v->dtdv_type,
                                      &lim, mstate, vstate))
                                          break;
  
                                  dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                      dvar->dtdv_data, &v->dtdv_type, lim);
                          } else {
                                  *((uint64_t *)dvar->dtdv_data) = regs[rd];
                          }
  
                          break;
                  }
  
                  case DIF_OP_ALLOCS: {
                          uintptr_t ptr = P2ROUNDUP(mstate->dtms_scratch_ptr, 8);
                          size_t size = ptr - mstate->dtms_scratch_ptr + regs[r1];
  
                          /*
                           * Rounding up the user allocation size could have
                           * overflowed large, bogus allocations (like -1ULL) to
                           * 0.
                           */
                          if (size < regs[r1] ||
                              !DTRACE_INSCRATCH(mstate, size)) {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                  regs[rd] = 0;
                                  break;
                          }
  
                          dtrace_bzero((void *) mstate->dtms_scratch_ptr, size);
                          mstate->dtms_scratch_ptr += size;
                          regs[rd] = ptr;
                          break;
                  }
  
                  case DIF_OP_COPYS:
                          if (!dtrace_canstore(regs[rd], regs[r2],
                              mstate, vstate)) {
                                  *flags |= CPU_DTRACE_BADADDR;
                                  *illval = regs[rd];
                                  break;
                          }
  
                          if (!dtrace_canload(regs[r1], regs[r2], mstate, vstate))
                                  break;
  
                          dtrace_bcopy((void *)(uintptr_t)regs[r1],
                              (void *)(uintptr_t)regs[rd], (size_t)regs[r2]);
                          break;
  
                  case DIF_OP_STB:
                          if (!dtrace_canstore(regs[rd], 1, mstate, vstate)) {
                                  *flags |= CPU_DTRACE_BADADDR;
                                  *illval = regs[rd];
                                  break;
                          }
                          *((uint8_t *)(uintptr_t)regs[rd]) = (uint8_t)regs[r1];
                          break;
  
                  case DIF_OP_STH:
                          if (!dtrace_canstore(regs[rd], 2, mstate, vstate)) {
                                  *flags |= CPU_DTRACE_BADADDR;
                                  *illval = regs[rd];
                                  break;
                          }
                          if (regs[rd] & 1) {
                                  *flags |= CPU_DTRACE_BADALIGN;
                                  *illval = regs[rd];
                                  break;
                          }
                          *((uint16_t *)(uintptr_t)regs[rd]) = (uint16_t)regs[r1];
                          break;
  
                  case DIF_OP_STW:
                          if (!dtrace_canstore(regs[rd], 4, mstate, vstate)) {
                                  *flags |= CPU_DTRACE_BADADDR;
                                  *illval = regs[rd];
                                  break;
                          }
                          if (regs[rd] & 3) {
                                  *flags |= CPU_DTRACE_BADALIGN;
                                  *illval = regs[rd];
                                  break;
                          }
                          *((uint32_t *)(uintptr_t)regs[rd]) = (uint32_t)regs[r1];
                          break;
  
                  case DIF_OP_STX:
                          if (!dtrace_canstore(regs[rd], 8, mstate, vstate)) {
                                  *flags |= CPU_DTRACE_BADADDR;
                                  *illval = regs[rd];
                                  break;
                          }
                          if (regs[rd] & 7) {
                                  *flags |= CPU_DTRACE_BADALIGN;
                                  *illval = regs[rd];
                                  break;
                          }
                          *((uint64_t *)(uintptr_t)regs[rd]) = regs[r1];
                          break;
                  }
          }
  
          if (!(*flags & CPU_DTRACE_FAULT))
                  return (rval);
  
          mstate->dtms_fltoffs = opc * sizeof (dif_instr_t);
          mstate->dtms_present |= DTRACE_MSTATE_FLTOFFS;
  
          return (0);
  }
  
  static void
  dtrace_action_breakpoint(dtrace_ecb_t *ecb)
  {
          dtrace_probe_t *probe = ecb->dte_probe;
          dtrace_provider_t *prov = probe->dtpr_provider;
          char c[DTRACE_FULLNAMELEN + 80], *str;
          char *msg = "dtrace: breakpoint action at probe ";
          char *ecbmsg = " (ecb ";
          uintptr_t mask = (0xf << (sizeof (uintptr_t) * NBBY / 4));
          uintptr_t val = (uintptr_t)ecb;
          int shift = (sizeof (uintptr_t) * NBBY) - 4, i = 0;
  
          if (dtrace_destructive_disallow)
                  return;
  
          /*
           * It's impossible to be taking action on the NULL probe.
           */
          ASSERT(probe != NULL);
  
          /*
           * This is a poor man's (destitute man's?) sprintf():  we want to
           * print the provider name, module name, function name and name of
           * the probe, along with the hex address of the ECB with the breakpoint
           * action -- all of which we must place in the character buffer by
           * hand.
           */
          while (*msg != '\0')
                  c[i++] = *msg++;
  
          for (str = prov->dtpv_name; *str != '\0'; str++)
                  c[i++] = *str;
          c[i++] = ':';
  
          for (str = probe->dtpr_mod; *str != '\0'; str++)
                  c[i++] = *str;
          c[i++] = ':';
  
          for (str = probe->dtpr_func; *str != '\0'; str++)
                  c[i++] = *str;
          c[i++] = ':';
  
          for (str = probe->dtpr_name; *str != '\0'; str++)
                  c[i++] = *str;
  
          while (*ecbmsg != '\0')
                  c[i++] = *ecbmsg++;
  
          while (shift >= 0) {
                  mask = (uintptr_t)0xf << shift;
  
                  if (val >= ((uintptr_t)1 << shift))
                          c[i++] = "0123456789abcdef"[(val & mask) >> shift];
                  shift -= 4;
          }
  
          c[i++] = ')';
          c[i] = '\0';
  
  #ifdef illumos
          debug_enter(c);
  #else
          kdb_enter(KDB_WHY_DTRACE, "breakpoint action");
  #endif
  }
  
  static void
  dtrace_action_panic(dtrace_ecb_t *ecb)
  {
          dtrace_probe_t *probe = ecb->dte_probe;
  
          /*
           * It's impossible to be taking action on the NULL probe.
           */
          ASSERT(probe != NULL);
  
          if (dtrace_destructive_disallow)
                  return;
  
          if (dtrace_panicked != NULL)
                  return;
  
          if (dtrace_casptr(&dtrace_panicked, NULL, curthread) != NULL)
                  return;
  
          /*
           * We won the right to panic.  (We want to be sure that only one
           * thread calls panic() from dtrace_probe(), and that panic() is
           * called exactly once.)
           */
          dtrace_panic("dtrace: panic action at probe %s:%s:%s:%s (ecb %p)",
              probe->dtpr_provider->dtpv_name, probe->dtpr_mod,
              probe->dtpr_func, probe->dtpr_name, (void *)ecb);
  }
  
  static void
  dtrace_action_raise(uint64_t sig)
  {
          if (dtrace_destructive_disallow)
                  return;
  
          if (sig >= NSIG) {
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                  return;
          }
  
  #ifdef illumos
          /*
           * raise() has a queue depth of 1 -- we ignore all subsequent
           * invocations of the raise() action.
           */
          if (curthread->t_dtrace_sig == 0)
                  curthread->t_dtrace_sig = (uint8_t)sig;
  
          curthread->t_sig_check = 1;
          aston(curthread);
  #else
          struct proc *p = curproc;
          PROC_LOCK(p);
          kern_psignal(p, sig);
          PROC_UNLOCK(p);
  #endif
  }
  
  static void
  dtrace_action_stop(void)
  {
          if (dtrace_destructive_disallow)
                  return;
  
  #ifdef illumos
          if (!curthread->t_dtrace_stop) {
                  curthread->t_dtrace_stop = 1;
                  curthread->t_sig_check = 1;
                  aston(curthread);
          }
  #else
          struct proc *p = curproc;
          PROC_LOCK(p);
          kern_psignal(p, SIGSTOP);
          PROC_UNLOCK(p);
  #endif
  }
  
  static void
  dtrace_action_chill(dtrace_mstate_t *mstate, hrtime_t val)
  {
          hrtime_t now;
          volatile uint16_t *flags;
  #ifdef illumos
          cpu_t *cpu = CPU;
  #else
          cpu_t *cpu = &solaris_cpu[curcpu];
  #endif
  
          if (dtrace_destructive_disallow)
                  return;
  
          flags = (volatile uint16_t *)&cpu_core[curcpu].cpuc_dtrace_flags;
  
          now = dtrace_gethrtime();
  
          if (now - cpu->cpu_dtrace_chillmark > dtrace_chill_interval) {
                  /*
                   * We need to advance the mark to the current time.
                   */
                  cpu->cpu_dtrace_chillmark = now;
                  cpu->cpu_dtrace_chilled = 0;
          }
  
          /*
           * Now check to see if the requested chill time would take us over
           * the maximum amount of time allowed in the chill interval.  (Or
           * worse, if the calculation itself induces overflow.)
           */
          if (cpu->cpu_dtrace_chilled + val > dtrace_chill_max ||
              cpu->cpu_dtrace_chilled + val < cpu->cpu_dtrace_chilled) {
                  *flags |= CPU_DTRACE_ILLOP;
                  return;
          }
  
          while (dtrace_gethrtime() - now < val)
                  continue;
  
          /*
           * Normally, we assure that the value of the variable "timestamp" does
           * not change within an ECB.  The presence of chill() represents an
           * exception to this rule, however.
           */
          mstate->dtms_present &= ~DTRACE_MSTATE_TIMESTAMP;
          cpu->cpu_dtrace_chilled += val;
  }
  
  static void
  dtrace_action_ustack(dtrace_mstate_t *mstate, dtrace_state_t *state,
      uint64_t *buf, uint64_t arg)
  {
          int nframes = DTRACE_USTACK_NFRAMES(arg);
          int strsize = DTRACE_USTACK_STRSIZE(arg);
          uint64_t *pcs = &buf[1], *fps;
          char *str = (char *)&pcs[nframes];
          int size, offs = 0, i, j;
          size_t rem;
          uintptr_t old = mstate->dtms_scratch_ptr, saved;
          uint16_t *flags = &cpu_core[curcpu].cpuc_dtrace_flags;
          char *sym;
  
          /*
           * Should be taking a faster path if string space has not been
           * allocated.
           */
          ASSERT(strsize != 0);
  
          /*
           * We will first allocate some temporary space for the frame pointers.
           */
          fps = (uint64_t *)P2ROUNDUP(mstate->dtms_scratch_ptr, 8);
          size = (uintptr_t)fps - mstate->dtms_scratch_ptr +
              (nframes * sizeof (uint64_t));
  
          if (!DTRACE_INSCRATCH(mstate, size)) {
                  /*
                   * Not enough room for our frame pointers -- need to indicate
                   * that we ran out of scratch space.
                   */
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                  return;
          }
  
          mstate->dtms_scratch_ptr += size;
          saved = mstate->dtms_scratch_ptr;
  
          /*
           * Now get a stack with both program counters and frame pointers.
           */
          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
          dtrace_getufpstack(buf, fps, nframes + 1);
          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
  
          /*
           * If that faulted, we're cooked.
           */
          if (*flags & CPU_DTRACE_FAULT)
                  goto out;
  
          /*
           * Now we want to walk up the stack, calling the USTACK helper.  For
           * each iteration, we restore the scratch pointer.
           */
          for (i = 0; i < nframes; i++) {
                  mstate->dtms_scratch_ptr = saved;
  
                  if (offs >= strsize)
                          break;
  
                  sym = (char *)(uintptr_t)dtrace_helper(
                      DTRACE_HELPER_ACTION_USTACK,
                      mstate, state, pcs[i], fps[i]);
  
                  /*
                   * If we faulted while running the helper, we're going to
                   * clear the fault and null out the corresponding string.
                   */
                  if (*flags & CPU_DTRACE_FAULT) {
                          *flags &= ~CPU_DTRACE_FAULT;
                          str[offs++] = '\0';
                          continue;
                  }
  
                  if (sym == NULL) {
                          str[offs++] = '\0';
                          continue;
                  }
  
                  if (!dtrace_strcanload((uintptr_t)sym, strsize, &rem, mstate,
                      &(state->dts_vstate))) {
                          str[offs++] = '\0';
                          continue;
                  }
  
                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
  
                  /*
                   * Now copy in the string that the helper returned to us.
                   */
                  for (j = 0; offs + j < strsize && j < rem; j++) {
                          if ((str[offs + j] = sym[j]) == '\0')
                                  break;
                  }
  
                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
  
                  offs += j + 1;
          }
  
          if (offs >= strsize) {
                  /*
                   * If we didn't have room for all of the strings, we don't
                   * abort processing -- this needn't be a fatal error -- but we
                   * still want to increment a counter (dts_stkstroverflows) to
                   * allow this condition to be warned about.  (If this is from
                   * a jstack() action, it is easily tuned via jstackstrsize.)
                   */
                  dtrace_error(&state->dts_stkstroverflows);
          }
  
          while (offs < strsize)
                  str[offs++] = '\0';
  
  out:
          mstate->dtms_scratch_ptr = old;
  }
  
  static void
  dtrace_store_by_ref(dtrace_difo_t *dp, caddr_t tomax, size_t size,
      size_t *valoffsp, uint64_t *valp, uint64_t end, int intuple, int dtkind)
  {
          volatile uint16_t *flags;
          uint64_t val = *valp;
          size_t valoffs = *valoffsp;
  
          flags = (volatile uint16_t *)&cpu_core[curcpu].cpuc_dtrace_flags;
          ASSERT(dtkind == DIF_TF_BYREF || dtkind == DIF_TF_BYUREF);
  
          /*
           * If this is a string, we're going to only load until we find the zero
           * byte -- after which we'll store zero bytes.
           */
          if (dp->dtdo_rtype.dtdt_kind == DIF_TYPE_STRING) {
                  char c = '\0' + 1;
                  size_t s;
  
                  for (s = 0; s < size; s++) {
                          if (c != '\0' && dtkind == DIF_TF_BYREF) {
                                  c = dtrace_load8(val++);
                          } else if (c != '\0' && dtkind == DIF_TF_BYUREF) {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                  c = dtrace_fuword8((void *)(uintptr_t)val++);
                                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                                  if (*flags & CPU_DTRACE_FAULT)
                                          break;
                          }
  
                          DTRACE_STORE(uint8_t, tomax, valoffs++, c);
  
                          if (c == '\0' && intuple)
                                  break;
                  }
          } else {
                  uint8_t c;
                  while (valoffs < end) {
                          if (dtkind == DIF_TF_BYREF) {
                                  c = dtrace_load8(val++);
                          } else if (dtkind == DIF_TF_BYUREF) {
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                  c = dtrace_fuword8((void *)(uintptr_t)val++);
                                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                                  if (*flags & CPU_DTRACE_FAULT)
                                          break;
                          }
  
                          DTRACE_STORE(uint8_t, tomax,
                              valoffs++, c);
                  }
          }
  
          *valp = val;
          *valoffsp = valoffs;
  }
  
  /*
   * Disables interrupts and sets the per-thread inprobe flag. When DEBUG is
   * defined, we also assert that we are not recursing unless the probe ID is an
   * error probe.
   */
  static dtrace_icookie_t
  dtrace_probe_enter(dtrace_id_t id)
  {
          dtrace_icookie_t cookie;
  
          cookie = dtrace_interrupt_disable();
  
          /*
           * Unless this is an ERROR probe, we are not allowed to recurse in
           * dtrace_probe(). Recursing into DTrace probe usually means that a
           * function is instrumented that should not have been instrumented or
           * that the ordering guarantee of the records will be violated,
           * resulting in unexpected output. If there is an exception to this
           * assertion, a new case should be added.
           */
          ASSERT(curthread->t_dtrace_inprobe == 0 ||
              id == dtrace_probeid_error);
          curthread->t_dtrace_inprobe = 1;
  
          return (cookie);
  }
  
  /*
   * Clears the per-thread inprobe flag and enables interrupts.
   */
  static void
  dtrace_probe_exit(dtrace_icookie_t cookie)
  {
  
          curthread->t_dtrace_inprobe = 0;
          dtrace_interrupt_enable(cookie);
  }
  
  /*
   * If you're looking for the epicenter of DTrace, you just found it.  This
   * is the function called by the provider to fire a probe -- from which all
   * subsequent probe-context DTrace activity emanates.
   */
  void
  dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t arg1,
      uintptr_t arg2, uintptr_t arg3, uintptr_t arg4)
  {
          processorid_t cpuid;
          dtrace_icookie_t cookie;
          dtrace_probe_t *probe;
          dtrace_mstate_t mstate;
          dtrace_ecb_t *ecb;
          dtrace_action_t *act;
          intptr_t offs;
          size_t size;
          int vtime, onintr;
          volatile uint16_t *flags;
          hrtime_t now;
  
          if (KERNEL_PANICKED())
                  return;
  
  #ifdef illumos
          /*
           * Kick out immediately if this CPU is still being born (in which case
           * curthread will be set to -1) or the current thread can't allow
           * probes in its current context.
           */
          if (((uintptr_t)curthread & 1) || (curthread->t_flag & T_DONTDTRACE))
                  return;
  #endif
  
          cookie = dtrace_probe_enter(id);
          probe = dtrace_probes[id - 1];
          cpuid = curcpu;
          onintr = CPU_ON_INTR(CPU);
  
          if (!onintr && probe->dtpr_predcache != DTRACE_CACHEIDNONE &&
              probe->dtpr_predcache == curthread->t_predcache) {
                  /*
                   * We have hit in the predicate cache; we know that
                   * this predicate would evaluate to be false.
                   */
                  dtrace_probe_exit(cookie);
                  return;
          }
  
  #ifdef illumos
          if (panic_quiesce) {
  #else
          if (KERNEL_PANICKED()) {
  #endif
                  /*
                   * We don't trace anything if we're panicking.
                   */
                  dtrace_probe_exit(cookie);
                  return;
          }
  
          now = mstate.dtms_timestamp = dtrace_gethrtime();
          mstate.dtms_present = DTRACE_MSTATE_TIMESTAMP;
          vtime = dtrace_vtime_references != 0;
  
          if (vtime && curthread->t_dtrace_start)
                  curthread->t_dtrace_vtime += now - curthread->t_dtrace_start;
  
          mstate.dtms_difo = NULL;
          mstate.dtms_probe = probe;
          mstate.dtms_strtok = 0;
          mstate.dtms_arg[0] = arg0;
          mstate.dtms_arg[1] = arg1;
          mstate.dtms_arg[2] = arg2;
          mstate.dtms_arg[3] = arg3;
          mstate.dtms_arg[4] = arg4;
  
          flags = (volatile uint16_t *)&cpu_core[cpuid].cpuc_dtrace_flags;
  
          for (ecb = probe->dtpr_ecb; ecb != NULL; ecb = ecb->dte_next) {
                  dtrace_predicate_t *pred = ecb->dte_predicate;
                  dtrace_state_t *state = ecb->dte_state;
                  dtrace_buffer_t *buf = &state->dts_buffer[cpuid];
                  dtrace_buffer_t *aggbuf = &state->dts_aggbuffer[cpuid];
                  dtrace_vstate_t *vstate = &state->dts_vstate;
                  dtrace_provider_t *prov = probe->dtpr_provider;
                  uint64_t tracememsize = 0;
                  int committed = 0;
                  caddr_t tomax;
  
                  /*
                   * A little subtlety with the following (seemingly innocuous)
                   * declaration of the automatic 'val':  by looking at the
                   * code, you might think that it could be declared in the
                   * action processing loop, below.  (That is, it's only used in
                   * the action processing loop.)  However, it must be declared
                   * out of that scope because in the case of DIF expression
                   * arguments to aggregating actions, one iteration of the
                   * action loop will use the last iteration's value.
                   */
                  uint64_t val = 0;
  
                  mstate.dtms_present = DTRACE_MSTATE_ARGS | DTRACE_MSTATE_PROBE;
                  mstate.dtms_getf = NULL;
  
                  *flags &= ~CPU_DTRACE_ERROR;
  
                  if (prov == dtrace_provider) {
                          /*
                           * If dtrace itself is the provider of this probe,
                           * we're only going to continue processing the ECB if
                           * arg0 (the dtrace_state_t) is equal to the ECB's
                           * creating state.  (This prevents disjoint consumers
                           * from seeing one another's metaprobes.)
                           */
                          if (arg0 != (uint64_t)(uintptr_t)state)
                                  continue;
                  }
  
                  if (state->dts_activity != DTRACE_ACTIVITY_ACTIVE) {
                          /*
                           * We're not currently active.  If our provider isn't
                           * the dtrace pseudo provider, we're not interested.
                           */
                          if (prov != dtrace_provider)
                                  continue;
  
                          /*
                           * Now we must further check if we are in the BEGIN
                           * probe.  If we are, we will only continue processing
                           * if we're still in WARMUP -- if one BEGIN enabling
                           * has invoked the exit() action, we don't want to
                           * evaluate subsequent BEGIN enablings.
                           */
                          if (probe->dtpr_id == dtrace_probeid_begin &&
                              state->dts_activity != DTRACE_ACTIVITY_WARMUP) {
                                  ASSERT(state->dts_activity ==
                                      DTRACE_ACTIVITY_DRAINING);
                                  continue;
                          }
                  }
  
                  if (ecb->dte_cond) {
                          /*
                           * If the dte_cond bits indicate that this
                           * consumer is only allowed to see user-mode firings
                           * of this probe, call the provider's dtps_usermode()
                           * entry point to check that the probe was fired
                           * while in a user context. Skip this ECB if that's
                           * not the case.
                           */
                          if ((ecb->dte_cond & DTRACE_COND_USERMODE) &&
                              prov->dtpv_pops.dtps_usermode(prov->dtpv_arg,
                              probe->dtpr_id, probe->dtpr_arg) == 0)
                                  continue;
  
  #ifdef illumos
                          /*
                           * This is more subtle than it looks. We have to be
                           * absolutely certain that CRED() isn't going to
                           * change out from under us so it's only legit to
                           * examine that structure if we're in constrained
                           * situations. Currently, the only times we'll this
                           * check is if a non-super-user has enabled the
                           * profile or syscall providers -- providers that
                           * allow visibility of all processes. For the
                           * profile case, the check above will ensure that
                           * we're examining a user context.
                           */
                          if (ecb->dte_cond & DTRACE_COND_OWNER) {
                                  cred_t *cr;
                                  cred_t *s_cr =
                                      ecb->dte_state->dts_cred.dcr_cred;
                                  proc_t *proc;
  
                                  ASSERT(s_cr != NULL);
  
                                  if ((cr = CRED()) == NULL ||
                                      s_cr->cr_uid != cr->cr_uid ||
                                      s_cr->cr_uid != cr->cr_ruid ||
                                      s_cr->cr_uid != cr->cr_suid ||
                                      s_cr->cr_gid != cr->cr_gid ||
                                      s_cr->cr_gid != cr->cr_rgid ||
                                      s_cr->cr_gid != cr->cr_sgid ||
                                      (proc = ttoproc(curthread)) == NULL ||
                                      (proc->p_flag & SNOCD))
                                          continue;
                          }
  
                          if (ecb->dte_cond & DTRACE_COND_ZONEOWNER) {
                                  cred_t *cr;
                                  cred_t *s_cr =
                                      ecb->dte_state->dts_cred.dcr_cred;
  
                                  ASSERT(s_cr != NULL);
  
                                  if ((cr = CRED()) == NULL ||
                                      s_cr->cr_zone->zone_id !=
                                      cr->cr_zone->zone_id)
                                          continue;
                          }
  #endif
                  }
  
                  if (now - state->dts_alive > dtrace_deadman_timeout) {
                          /*
                           * We seem to be dead.  Unless we (a) have kernel
                           * destructive permissions (b) have explicitly enabled
                           * destructive actions and (c) destructive actions have
                           * not been disabled, we're going to transition into
                           * the KILLED state, from which no further processing
                           * on this state will be performed.
                           */
                          if (!dtrace_priv_kernel_destructive(state) ||
                              !state->dts_cred.dcr_destructive ||
                              dtrace_destructive_disallow) {
                                  void *activity = &state->dts_activity;
                                  dtrace_activity_t curstate;
  
                                  do {
                                          curstate = state->dts_activity;
                                  } while (dtrace_cas32(activity, curstate,
                                      DTRACE_ACTIVITY_KILLED) != curstate);
  
                                  continue;
                          }
                  }
  
                  if ((offs = dtrace_buffer_reserve(buf, ecb->dte_needed,
                      ecb->dte_alignment, state, &mstate)) < 0)
                          continue;
  
                  tomax = buf->dtb_tomax;
                  ASSERT(tomax != NULL);
  
                  if (ecb->dte_size != 0) {
                          dtrace_rechdr_t dtrh;
                          if (!(mstate.dtms_present & DTRACE_MSTATE_TIMESTAMP)) {
                                  mstate.dtms_timestamp = dtrace_gethrtime();
                                  mstate.dtms_present |= DTRACE_MSTATE_TIMESTAMP;
                          }
                          ASSERT3U(ecb->dte_size, >=, sizeof (dtrace_rechdr_t));
                          dtrh.dtrh_epid = ecb->dte_epid;
                          DTRACE_RECORD_STORE_TIMESTAMP(&dtrh,
                              mstate.dtms_timestamp);
                          *((dtrace_rechdr_t *)(tomax + offs)) = dtrh;
                  }
  
                  mstate.dtms_epid = ecb->dte_epid;
                  mstate.dtms_present |= DTRACE_MSTATE_EPID;
  
                  if (state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL)
                          mstate.dtms_access = DTRACE_ACCESS_KERNEL;
                  else
                          mstate.dtms_access = 0;
  
                  if (pred != NULL) {
                          dtrace_difo_t *dp = pred->dtp_difo;
                          uint64_t rval;
  
                          rval = dtrace_dif_emulate(dp, &mstate, vstate, state);
  
                          if (!(*flags & CPU_DTRACE_ERROR) && !rval) {
                                  dtrace_cacheid_t cid = probe->dtpr_predcache;
  
                                  if (cid != DTRACE_CACHEIDNONE && !onintr) {
                                          /*
                                           * Update the predicate cache...
                                           */
                                          ASSERT(cid == pred->dtp_cacheid);
                                          curthread->t_predcache = cid;
                                  }
  
                                  continue;
                          }
                  }
  
                  for (act = ecb->dte_action; !(*flags & CPU_DTRACE_ERROR) &&
                      act != NULL; act = act->dta_next) {
                          size_t valoffs;
                          dtrace_difo_t *dp;
                          dtrace_recdesc_t *rec = &act->dta_rec;
  
                          size = rec->dtrd_size;
                          valoffs = offs + rec->dtrd_offset;
  
                          if (DTRACEACT_ISAGG(act->dta_kind)) {
                                  uint64_t v = 0xbad;
                                  dtrace_aggregation_t *agg;
  
                                  agg = (dtrace_aggregation_t *)act;
  
                                  if ((dp = act->dta_difo) != NULL)
                                          v = dtrace_dif_emulate(dp,
                                              &mstate, vstate, state);
  
                                  if (*flags & CPU_DTRACE_ERROR)
                                          continue;
  
                                  /*
                                   * Note that we always pass the expression
                                   * value from the previous iteration of the
                                   * action loop.  This value will only be used
                                   * if there is an expression argument to the
                                   * aggregating action, denoted by the
                                   * dtag_hasarg field.
                                   */
                                  dtrace_aggregate(agg, buf,
                                      offs, aggbuf, v, val);
                                  continue;
                          }
  
                          switch (act->dta_kind) {
                          case DTRACEACT_STOP:
                                  if (dtrace_priv_proc_destructive(state))
                                          dtrace_action_stop();
                                  continue;
  
                          case DTRACEACT_BREAKPOINT:
                                  if (dtrace_priv_kernel_destructive(state))
                                          dtrace_action_breakpoint(ecb);
                                  continue;
  
                          case DTRACEACT_PANIC:
                                  if (dtrace_priv_kernel_destructive(state))
                                          dtrace_action_panic(ecb);
                                  continue;
  
                          case DTRACEACT_STACK:
                                  if (!dtrace_priv_kernel(state))
                                          continue;
  
                                  dtrace_getpcstack((pc_t *)(tomax + valoffs),
                                      size / sizeof (pc_t), probe->dtpr_aframes,
                                      DTRACE_ANCHORED(probe) ? NULL :
                                      (uint32_t *)arg0);
                                  continue;
  
                          case DTRACEACT_JSTACK:
                          case DTRACEACT_USTACK:
                                  if (!dtrace_priv_proc(state))
                                          continue;
  
                                  /*
                                   * See comment in DIF_VAR_PID.
                                   */
                                  if (DTRACE_ANCHORED(mstate.dtms_probe) &&
                                      CPU_ON_INTR(CPU)) {
                                          int depth = DTRACE_USTACK_NFRAMES(
                                              rec->dtrd_arg) + 1;
  
                                          dtrace_bzero((void *)(tomax + valoffs),
                                              DTRACE_USTACK_STRSIZE(rec->dtrd_arg)
                                              + depth * sizeof (uint64_t));
  
                                          continue;
                                  }
  
                                  if (DTRACE_USTACK_STRSIZE(rec->dtrd_arg) != 0 &&
                                      curproc->p_dtrace_helpers != NULL) {
                                          /*
                                           * This is the slow path -- we have
                                           * allocated string space, and we're
                                           * getting the stack of a process that
                                           * has helpers.  Call into a separate
                                           * routine to perform this processing.
                                           */
                                          dtrace_action_ustack(&mstate, state,
                                              (uint64_t *)(tomax + valoffs),
                                              rec->dtrd_arg);
                                          continue;
                                  }
  
                                  DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                  dtrace_getupcstack((uint64_t *)
                                      (tomax + valoffs),
                                      DTRACE_USTACK_NFRAMES(rec->dtrd_arg) + 1);
                                  DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                                  continue;
  
                          default:
                                  break;
                          }
  
                          dp = act->dta_difo;
                          ASSERT(dp != NULL);
  
                          val = dtrace_dif_emulate(dp, &mstate, vstate, state);
  
                          if (*flags & CPU_DTRACE_ERROR)
                                  continue;
  
                          switch (act->dta_kind) {
                          case DTRACEACT_SPECULATE: {
                                  dtrace_rechdr_t *dtrh;
  
                                  ASSERT(buf == &state->dts_buffer[cpuid]);
                                  buf = dtrace_speculation_buffer(state,
                                      cpuid, val);
  
                                  if (buf == NULL) {
                                          *flags |= CPU_DTRACE_DROP;
                                          continue;
                                  }
  
                                  offs = dtrace_buffer_reserve(buf,
                                      ecb->dte_needed, ecb->dte_alignment,
                                      state, NULL);
  
                                  if (offs < 0) {
                                          *flags |= CPU_DTRACE_DROP;
                                          continue;
                                  }
  
                                  tomax = buf->dtb_tomax;
                                  ASSERT(tomax != NULL);
  
                                  if (ecb->dte_size == 0)
                                          continue;
  
                                  ASSERT3U(ecb->dte_size, >=,
                                      sizeof (dtrace_rechdr_t));
                                  dtrh = ((void *)(tomax + offs));
                                  dtrh->dtrh_epid = ecb->dte_epid;
                                  /*
                                   * When the speculation is committed, all of
                                   * the records in the speculative buffer will
                                   * have their timestamps set to the commit
                                   * time.  Until then, it is set to a sentinel
                                   * value, for debugability.
                                   */
                                  DTRACE_RECORD_STORE_TIMESTAMP(dtrh, UINT64_MAX);
                                  continue;
                          }
  
                          case DTRACEACT_PRINTM: {
                                  /* The DIF returns a 'memref'. */
                                  uintptr_t *memref = (uintptr_t *)(uintptr_t) val;
  
                                  /* Get the size from the memref. */
                                  size = memref[1];
  
                                  /*
                                   * Check if the size exceeds the allocated
                                   * buffer size.
                                   */
                                  if (size + sizeof(uintptr_t) > dp->dtdo_rtype.dtdt_size) {
                                          /* Flag a drop! */
                                          *flags |= CPU_DTRACE_DROP;
                                          continue;
                                  }
  
                                  /* Store the size in the buffer first. */
                                  DTRACE_STORE(uintptr_t, tomax,
                                      valoffs, size);
  
                                  /*
                                   * Offset the buffer address to the start
                                   * of the data.
                                   */
                                  valoffs += sizeof(uintptr_t);
  
                                  /*
                                   * Reset to the memory address rather than
                                   * the memref array, then let the BYREF
                                   * code below do the work to store the 
                                   * memory data in the buffer.
                                   */
                                  val = memref[0];
                                  break;
                          }
  
                          case DTRACEACT_CHILL:
                                  if (dtrace_priv_kernel_destructive(state))
                                          dtrace_action_chill(&mstate, val);
                                  continue;
  
                          case DTRACEACT_RAISE:
                                  if (dtrace_priv_proc_destructive(state))
                                          dtrace_action_raise(val);
                                  continue;
  
                          case DTRACEACT_COMMIT:
                                  ASSERT(!committed);
  
                                  /*
                                   * We need to commit our buffer state.
                                   */
                                  if (ecb->dte_size)
                                          buf->dtb_offset = offs + ecb->dte_size;
                                  buf = &state->dts_buffer[cpuid];
                                  dtrace_speculation_commit(state, cpuid, val);
                                  committed = 1;
                                  continue;
  
                          case DTRACEACT_DISCARD:
                                  dtrace_speculation_discard(state, cpuid, val);
                                  continue;
  
                          case DTRACEACT_DIFEXPR:
                          case DTRACEACT_LIBACT:
                          case DTRACEACT_PRINTF:
                          case DTRACEACT_PRINTA:
                          case DTRACEACT_SYSTEM:
                          case DTRACEACT_FREOPEN:
                          case DTRACEACT_TRACEMEM:
                                  break;
  
                          case DTRACEACT_TRACEMEM_DYNSIZE:
                                  tracememsize = val;
                                  break;
  
                          case DTRACEACT_SYM:
                          case DTRACEACT_MOD:
                                  if (!dtrace_priv_kernel(state))
                                          continue;
                                  break;
  
                          case DTRACEACT_USYM:
                          case DTRACEACT_UMOD:
                          case DTRACEACT_UADDR: {
  #ifdef illumos
                                  struct pid *pid = curthread->t_procp->p_pidp;
  #endif
  
                                  if (!dtrace_priv_proc(state))
                                          continue;
  
                                  DTRACE_STORE(uint64_t, tomax,
  #ifdef illumos
                                      valoffs, (uint64_t)pid->pid_id);
  #else
                                      valoffs, (uint64_t) curproc->p_pid);
  #endif
                                  DTRACE_STORE(uint64_t, tomax,
                                      valoffs + sizeof (uint64_t), val);
  
                                  continue;
                          }
  
                          case DTRACEACT_EXIT: {
                                  /*
                                   * For the exit action, we are going to attempt
                                   * to atomically set our activity to be
                                   * draining.  If this fails (either because
                                   * another CPU has beat us to the exit action,
                                   * or because our current activity is something
                                   * other than ACTIVE or WARMUP), we will
                                   * continue.  This assures that the exit action
                                   * can be successfully recorded at most once
                                   * when we're in the ACTIVE state.  If we're
                                   * encountering the exit() action while in
                                   * COOLDOWN, however, we want to honor the new
                                   * status code.  (We know that we're the only
                                   * thread in COOLDOWN, so there is no race.)
                                   */
                                  void *activity = &state->dts_activity;
                                  dtrace_activity_t curstate = state->dts_activity;
  
                                  if (curstate == DTRACE_ACTIVITY_COOLDOWN)
                                          break;
  
                                  if (curstate != DTRACE_ACTIVITY_WARMUP)
                                          curstate = DTRACE_ACTIVITY_ACTIVE;
  
                                  if (dtrace_cas32(activity, curstate,
                                      DTRACE_ACTIVITY_DRAINING) != curstate) {
                                          *flags |= CPU_DTRACE_DROP;
                                          continue;
                                  }
  
                                  break;
                          }
  
                          default:
                                  ASSERT(0);
                          }
  
                          if (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF ||
                              dp->dtdo_rtype.dtdt_flags & DIF_TF_BYUREF) {
                                  uintptr_t end = valoffs + size;
  
                                  if (tracememsize != 0 &&
                                      valoffs + tracememsize < end) {
                                          end = valoffs + tracememsize;
                                          tracememsize = 0;
                                  }
  
                                  if (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF &&
                                      !dtrace_vcanload((void *)(uintptr_t)val,
                                      &dp->dtdo_rtype, NULL, &mstate, vstate))
                                          continue;
  
                                  dtrace_store_by_ref(dp, tomax, size, &valoffs,
                                      &val, end, act->dta_intuple,
                                      dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF ?
                                      DIF_TF_BYREF: DIF_TF_BYUREF);
                                  continue;
                          }
  
                          switch (size) {
                          case 0:
                                  break;
  
                          case sizeof (uint8_t):
                                  DTRACE_STORE(uint8_t, tomax, valoffs, val);
                                  break;
                          case sizeof (uint16_t):
                                  DTRACE_STORE(uint16_t, tomax, valoffs, val);
                                  break;
                          case sizeof (uint32_t):
                                  DTRACE_STORE(uint32_t, tomax, valoffs, val);
                                  break;
                          case sizeof (uint64_t):
                                  DTRACE_STORE(uint64_t, tomax, valoffs, val);
                                  break;
                          default:
                                  /*
                                   * Any other size should have been returned by
                                   * reference, not by value.
                                   */
                                  ASSERT(0);
                                  break;
                          }
                  }
  
                  if (*flags & CPU_DTRACE_DROP)
                          continue;
  
                  if (*flags & CPU_DTRACE_FAULT) {
                          int ndx;
                          dtrace_action_t *err;
  
                          buf->dtb_errors++;
  
                          if (probe->dtpr_id == dtrace_probeid_error) {
                                  /*
                                   * There's nothing we can do -- we had an
                                   * error on the error probe.  We bump an
                                   * error counter to at least indicate that
                                   * this condition happened.
                                   */
                                  dtrace_error(&state->dts_dblerrors);
                                  continue;
                          }
  
                          if (vtime) {
                                  /*
                                   * Before recursing on dtrace_probe(), we
                                   * need to explicitly clear out our start
                                   * time to prevent it from being accumulated
                                   * into t_dtrace_vtime.
                                   */
                                  curthread->t_dtrace_start = 0;
                          }
  
                          /*
                           * Iterate over the actions to figure out which action
                           * we were processing when we experienced the error.
                           * Note that act points _past_ the faulting action; if
                           * act is ecb->dte_action, the fault was in the
                           * predicate, if it's ecb->dte_action->dta_next it's
                           * in action #1, and so on.
                           */
                          for (err = ecb->dte_action, ndx = 0;
                              err != act; err = err->dta_next, ndx++)
                                  continue;
  
                          dtrace_probe_error(state, ecb->dte_epid, ndx,
                              (mstate.dtms_present & DTRACE_MSTATE_FLTOFFS) ?
                              mstate.dtms_fltoffs : -1, DTRACE_FLAGS2FLT(*flags),
                              cpu_core[cpuid].cpuc_dtrace_illval);
  
                          continue;
                  }
  
                  if (!committed)
                          buf->dtb_offset = offs + ecb->dte_size;
          }
  
          if (vtime)
                  curthread->t_dtrace_start = dtrace_gethrtime();
  
          dtrace_probe_exit(cookie);
  }
  
  /*
   * DTrace Probe Hashing Functions
   *
   * The functions in this section (and indeed, the functions in remaining
   * sections) are not _called_ from probe context.  (Any exceptions to this are
   * marked with a "Note:".)  Rather, they are called from elsewhere in the
   * DTrace framework to look-up probes in, add probes to and remove probes from
   * the DTrace probe hashes.  (Each probe is hashed by each element of the
   * probe tuple -- allowing for fast lookups, regardless of what was
   * specified.)
   */
  static uint_t
  dtrace_hash_str(const char *p)
  {
          unsigned int g;
          uint_t hval = 0;
  
          while (*p) {
                  hval = (hval << 4) + *p++;
                  if ((g = (hval & 0xf0000000)) != 0)
                          hval ^= g >> 24;
                  hval &= ~g;
          }
          return (hval);
  }
  
  static dtrace_hash_t *
  dtrace_hash_create(uintptr_t stroffs, uintptr_t nextoffs, uintptr_t prevoffs)
  {
          dtrace_hash_t *hash = kmem_zalloc(sizeof (dtrace_hash_t), KM_SLEEP);
  
          hash->dth_stroffs = stroffs;
          hash->dth_nextoffs = nextoffs;
          hash->dth_prevoffs = prevoffs;
  
          hash->dth_size = 1;
          hash->dth_mask = hash->dth_size - 1;
  
          hash->dth_tab = kmem_zalloc(hash->dth_size *
              sizeof (dtrace_hashbucket_t *), KM_SLEEP);
  
          return (hash);
  }
  
  static void
  dtrace_hash_destroy(dtrace_hash_t *hash)
  {
  #ifdef DEBUG
          int i;
  
          for (i = 0; i < hash->dth_size; i++)
                  ASSERT(hash->dth_tab[i] == NULL);
  #endif
  
          kmem_free(hash->dth_tab,
              hash->dth_size * sizeof (dtrace_hashbucket_t *));
          kmem_free(hash, sizeof (dtrace_hash_t));
  }
  
  static void
  dtrace_hash_resize(dtrace_hash_t *hash)
  {
          int size = hash->dth_size, i, ndx;
          int new_size = hash->dth_size << 1;
          int new_mask = new_size - 1;
          dtrace_hashbucket_t **new_tab, *bucket, *next;
  
          ASSERT((new_size & new_mask) == 0);
  
          new_tab = kmem_zalloc(new_size * sizeof (void *), KM_SLEEP);
  
          for (i = 0; i < size; i++) {
                  for (bucket = hash->dth_tab[i]; bucket != NULL; bucket = next) {
                          dtrace_probe_t *probe = bucket->dthb_chain;
  
                          ASSERT(probe != NULL);
                          ndx = DTRACE_HASHSTR(hash, probe) & new_mask;
  
                          next = bucket->dthb_next;
                          bucket->dthb_next = new_tab[ndx];
                          new_tab[ndx] = bucket;
                  }
          }
  
          kmem_free(hash->dth_tab, hash->dth_size * sizeof (void *));
          hash->dth_tab = new_tab;
          hash->dth_size = new_size;
          hash->dth_mask = new_mask;
  }
  
  static void
  dtrace_hash_add(dtrace_hash_t *hash, dtrace_probe_t *new)
  {
          int hashval = DTRACE_HASHSTR(hash, new);
          int ndx = hashval & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];
          dtrace_probe_t **nextp, **prevp;
  
          for (; bucket != NULL; bucket = bucket->dthb_next) {
                  if (DTRACE_HASHEQ(hash, bucket->dthb_chain, new))
                          goto add;
          }
  
          if ((hash->dth_nbuckets >> 1) > hash->dth_size) {
                  dtrace_hash_resize(hash);
                  dtrace_hash_add(hash, new);
                  return;
          }
  
          bucket = kmem_zalloc(sizeof (dtrace_hashbucket_t), KM_SLEEP);
          bucket->dthb_next = hash->dth_tab[ndx];
          hash->dth_tab[ndx] = bucket;
          hash->dth_nbuckets++;
  
  add:
          nextp = DTRACE_HASHNEXT(hash, new);
          ASSERT(*nextp == NULL && *(DTRACE_HASHPREV(hash, new)) == NULL);
          *nextp = bucket->dthb_chain;
  
          if (bucket->dthb_chain != NULL) {
                  prevp = DTRACE_HASHPREV(hash, bucket->dthb_chain);
                  ASSERT(*prevp == NULL);
                  *prevp = new;
          }
  
          bucket->dthb_chain = new;
          bucket->dthb_len++;
  }
  
  static dtrace_probe_t *
  dtrace_hash_lookup(dtrace_hash_t *hash, dtrace_probe_t *template)
  {
          int hashval = DTRACE_HASHSTR(hash, template);
          int ndx = hashval & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];
  
          for (; bucket != NULL; bucket = bucket->dthb_next) {
                  if (DTRACE_HASHEQ(hash, bucket->dthb_chain, template))
                          return (bucket->dthb_chain);
          }
  
          return (NULL);
  }
  
  static int
  dtrace_hash_collisions(dtrace_hash_t *hash, dtrace_probe_t *template)
  {
          int hashval = DTRACE_HASHSTR(hash, template);
          int ndx = hashval & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];
  
          for (; bucket != NULL; bucket = bucket->dthb_next) {
                  if (DTRACE_HASHEQ(hash, bucket->dthb_chain, template))
                          return (bucket->dthb_len);
          }
  
          return (0);
  }
  
  static void
  dtrace_hash_remove(dtrace_hash_t *hash, dtrace_probe_t *probe)
  {
          int ndx = DTRACE_HASHSTR(hash, probe) & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];
  
          dtrace_probe_t **prevp = DTRACE_HASHPREV(hash, probe);
          dtrace_probe_t **nextp = DTRACE_HASHNEXT(hash, probe);
  
          /*
           * Find the bucket that we're removing this probe from.
           */
          for (; bucket != NULL; bucket = bucket->dthb_next) {
                  if (DTRACE_HASHEQ(hash, bucket->dthb_chain, probe))
                          break;
          }
  
          ASSERT(bucket != NULL);
  
          if (*prevp == NULL) {
                  if (*nextp == NULL) {
                          /*
                           * The removed probe was the only probe on this
                           * bucket; we need to remove the bucket.
                           */
                          dtrace_hashbucket_t *b = hash->dth_tab[ndx];
  
                          ASSERT(bucket->dthb_chain == probe);
                          ASSERT(b != NULL);
  
                          if (b == bucket) {
                                  hash->dth_tab[ndx] = bucket->dthb_next;
                          } else {
                                  while (b->dthb_next != bucket)
                                          b = b->dthb_next;
                                  b->dthb_next = bucket->dthb_next;
                          }
  
                          ASSERT(hash->dth_nbuckets > 0);
                          hash->dth_nbuckets--;
                          kmem_free(bucket, sizeof (dtrace_hashbucket_t));
                          return;
                  }
  
                  bucket->dthb_chain = *nextp;
          } else {
                  *(DTRACE_HASHNEXT(hash, *prevp)) = *nextp;
          }
  
          if (*nextp != NULL)
                  *(DTRACE_HASHPREV(hash, *nextp)) = *prevp;
  }
  
  /*
   * DTrace Utility Functions
   *
   * These are random utility functions that are _not_ called from probe context.
   */
  static int
  dtrace_badattr(const dtrace_attribute_t *a)
  {
          return (a->dtat_name > DTRACE_STABILITY_MAX ||
              a->dtat_data > DTRACE_STABILITY_MAX ||
              a->dtat_class > DTRACE_CLASS_MAX);
  }
  
  /*
   * Return a duplicate copy of a string.  If the specified string is NULL,
   * this function returns a zero-length string.
   */
  static char *
  dtrace_strdup(const char *str)
  {
          char *new = kmem_zalloc((str != NULL ? strlen(str) : 0) + 1, KM_SLEEP);
  
          if (str != NULL)
                  (void) strcpy(new, str);
  
          return (new);
  }
  
  #define DTRACE_ISALPHA(c)       \
          (((c) >= 'a' && (c) <= 'z') || ((c) >= 'A' && (c) <= 'Z'))
  
  static int
  dtrace_badname(const char *s)
  {
          char c;
  
          if (s == NULL || (c = *s++) == '\0')
                  return (0);
  
          if (!DTRACE_ISALPHA(c) && c != '-' && c != '_' && c != '.')
                  return (1);
  
          while ((c = *s++) != '\0') {
                  if (!DTRACE_ISALPHA(c) && (c < '' || c > '9') &&
                      c != '-' && c != '_' && c != '.' && c != '`')
                          return (1);
          }
  
          return (0);
  }
  
  static void
  dtrace_cred2priv(cred_t *cr, uint32_t *privp, uid_t *uidp, zoneid_t *zoneidp)
  {
          uint32_t priv;
  
  #ifdef illumos
          if (cr == NULL || PRIV_POLICY_ONLY(cr, PRIV_ALL, B_FALSE)) {
                  /*
                   * For DTRACE_PRIV_ALL, the uid and zoneid don't matter.
                   */
                  priv = DTRACE_PRIV_ALL;
          } else {
                  *uidp = crgetuid(cr);
                  *zoneidp = crgetzoneid(cr);
  
                  priv = 0;
                  if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_KERNEL, B_FALSE))
                          priv |= DTRACE_PRIV_KERNEL | DTRACE_PRIV_USER;
                  else if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_USER, B_FALSE))
                          priv |= DTRACE_PRIV_USER;
                  if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_PROC, B_FALSE))
                          priv |= DTRACE_PRIV_PROC;
                  if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE))
                          priv |= DTRACE_PRIV_OWNER;
                  if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE))
                          priv |= DTRACE_PRIV_ZONEOWNER;
          }
  #else
          priv = DTRACE_PRIV_ALL;
  #endif
  
          *privp = priv;
  }
  
  #ifdef DTRACE_ERRDEBUG
  static void
  dtrace_errdebug(const char *str)
  {
          int hval = dtrace_hash_str(str) % DTRACE_ERRHASHSZ;
          int occupied = 0;
  
          mutex_enter(&dtrace_errlock);
          dtrace_errlast = str;
          dtrace_errthread = curthread;
  
          while (occupied++ < DTRACE_ERRHASHSZ) {
                  if (dtrace_errhash[hval].dter_msg == str) {
                          dtrace_errhash[hval].dter_count++;
                          goto out;
                  }
  
                  if (dtrace_errhash[hval].dter_msg != NULL) {
                          hval = (hval + 1) % DTRACE_ERRHASHSZ;
                          continue;
                  }
  
                  dtrace_errhash[hval].dter_msg = str;
                  dtrace_errhash[hval].dter_count = 1;
                  goto out;
          }
  
          panic("dtrace: undersized error hash");
  out:
          mutex_exit(&dtrace_errlock);
  }
  #endif
  
  /*
   * DTrace Matching Functions
   *
   * These functions are used to match groups of probes, given some elements of
   * a probe tuple, or some globbed expressions for elements of a probe tuple.
   */
  static int
  dtrace_match_priv(const dtrace_probe_t *prp, uint32_t priv, uid_t uid,
      zoneid_t zoneid)
  {
          if (priv != DTRACE_PRIV_ALL) {
                  uint32_t ppriv = prp->dtpr_provider->dtpv_priv.dtpp_flags;
                  uint32_t match = priv & ppriv;
  
                  /*
                   * No PRIV_DTRACE_* privileges...
                   */
                  if ((priv & (DTRACE_PRIV_PROC | DTRACE_PRIV_USER |
                      DTRACE_PRIV_KERNEL)) == 0)
                          return (0);
  
                  /*
                   * No matching bits, but there were bits to match...
                   */
                  if (match == 0 && ppriv != 0)
                          return (0);
  
                  /*
                   * Need to have permissions to the process, but don't...
                   */
                  if (((ppriv & ~match) & DTRACE_PRIV_OWNER) != 0 &&
                      uid != prp->dtpr_provider->dtpv_priv.dtpp_uid) {
                          return (0);
                  }
  
                  /*
                   * Need to be in the same zone unless we possess the
                   * privilege to examine all zones.
                   */
                  if (((ppriv & ~match) & DTRACE_PRIV_ZONEOWNER) != 0 &&
                      zoneid != prp->dtpr_provider->dtpv_priv.dtpp_zoneid) {
                          return (0);
                  }
          }
  
          return (1);
  }
  
  /*
   * dtrace_match_probe compares a dtrace_probe_t to a pre-compiled key, which
   * consists of input pattern strings and an ops-vector to evaluate them.
   * This function returns >0 for match, 0 for no match, and <0 for error.
   */
  static int
  dtrace_match_probe(const dtrace_probe_t *prp, const dtrace_probekey_t *pkp,
      uint32_t priv, uid_t uid, zoneid_t zoneid)
  {
          dtrace_provider_t *pvp = prp->dtpr_provider;
          int rv;
  
          if (pvp->dtpv_defunct)
                  return (0);
  
          if ((rv = pkp->dtpk_pmatch(pvp->dtpv_name, pkp->dtpk_prov, 0)) <= 0)
                  return (rv);
  
          if ((rv = pkp->dtpk_mmatch(prp->dtpr_mod, pkp->dtpk_mod, 0)) <= 0)
                  return (rv);
  
          if ((rv = pkp->dtpk_fmatch(prp->dtpr_func, pkp->dtpk_func, 0)) <= 0)
                  return (rv);
  
          if ((rv = pkp->dtpk_nmatch(prp->dtpr_name, pkp->dtpk_name, 0)) <= 0)
                  return (rv);
  
          if (dtrace_match_priv(prp, priv, uid, zoneid) == 0)
                  return (0);
  
          return (rv);
  }
  
  /*
   * dtrace_match_glob() is a safe kernel implementation of the gmatch(3GEN)
   * interface for matching a glob pattern 'p' to an input string 's'.  Unlike
   * libc's version, the kernel version only applies to 8-bit ASCII strings.
   * In addition, all of the recursion cases except for '*' matching have been
   * unwound.  For '*', we still implement recursive evaluation, but a depth
   * counter is maintained and matching is aborted if we recurse too deep.
   * The function returns 0 if no match, >0 if match, and <0 if recursion error.
   */
  static int
  dtrace_match_glob(const char *s, const char *p, int depth)
  {
          const char *olds;
          char s1, c;
          int gs;
  
          if (depth > DTRACE_PROBEKEY_MAXDEPTH)
                  return (-1);
  
          if (s == NULL)
                  s = ""; /* treat NULL as empty string */
  
  top:
          olds = s;
          s1 = *s++;
  
          if (p == NULL)
                  return (0);
  
          if ((c = *p++) == '\0')
                  return (s1 == '\0');
  
          switch (c) {
          case '[': {
                  int ok = 0, notflag = 0;
                  char lc = '\0';
  
                  if (s1 == '\0')
                          return (0);
  
                  if (*p == '!') {
                          notflag = 1;
                          p++;
                  }
  
                  if ((c = *p++) == '\0')
                          return (0);
  
                  do {
                          if (c == '-' && lc != '\0' && *p != ']') {
                                  if ((c = *p++) == '\0')
                                          return (0);
                                  if (c == '\\' && (c = *p++) == '\0')
                                          return (0);
  
                                  if (notflag) {
                                          if (s1 < lc || s1 > c)
                                                  ok++;
                                          else
                                                  return (0);
                                  } else if (lc <= s1 && s1 <= c)
                                          ok++;
  
                          } else if (c == '\\' && (c = *p++) == '\0')
                                  return (0);
  
                          lc = c; /* save left-hand 'c' for next iteration */
  
                          if (notflag) {
                                  if (s1 != c)
                                          ok++;
                                  else
                                          return (0);
                          } else if (s1 == c)
                                  ok++;
  
                          if ((c = *p++) == '\0')
                                  return (0);
  
                  } while (c != ']');
  
                  if (ok)
                          goto top;
  
                  return (0);
          }
  
          case '\\':
                  if ((c = *p++) == '\0')
                          return (0);
                  /*FALLTHRU*/
  
          default:
                  if (c != s1)
                          return (0);
                  /*FALLTHRU*/
  
          case '?':
                  if (s1 != '\0')
                          goto top;
                  return (0);
  
          case '*':
                  while (*p == '*')
                          p++; /* consecutive *'s are identical to a single one */
  
                  if (*p == '\0')
                          return (1);
  
                  for (s = olds; *s != '\0'; s++) {
                          if ((gs = dtrace_match_glob(s, p, depth + 1)) != 0)
                                  return (gs);
                  }
  
                  return (0);
          }
  }
  
  /*ARGSUSED*/
  static int
  dtrace_match_string(const char *s, const char *p, int depth)
  {
          return (s != NULL && strcmp(s, p) == 0);
  }
  
  /*ARGSUSED*/
  static int
  dtrace_match_nul(const char *s, const char *p, int depth)
  {
          return (1); /* always match the empty pattern */
  }
  
  /*ARGSUSED*/
  static int
  dtrace_match_nonzero(const char *s, const char *p, int depth)
  {
          return (s != NULL && s[0] != '\0');
  }
  
  static int
  dtrace_match(const dtrace_probekey_t *pkp, uint32_t priv, uid_t uid,
      zoneid_t zoneid, int (*matched)(dtrace_probe_t *, void *), void *arg)
  {
          dtrace_probe_t template, *probe;
          dtrace_hash_t *hash = NULL;
          int len, best = INT_MAX, nmatched = 0;
          dtrace_id_t i;
  
          ASSERT(MUTEX_HELD(&dtrace_lock));
  
          /*
           * If the probe ID is specified in the key, just lookup by ID and
           * invoke the match callback once if a matching probe is found.
           */
          if (pkp->dtpk_id != DTRACE_IDNONE) {
                  if ((probe = dtrace_probe_lookup_id(pkp->dtpk_id)) != NULL &&
                      dtrace_match_probe(probe, pkp, priv, uid, zoneid) > 0) {
                          (void) (*matched)(probe, arg);
                          nmatched++;
                  }
                  return (nmatched);
          }
  
          template.dtpr_mod = (char *)pkp->dtpk_mod;
          template.dtpr_func = (char *)pkp->dtpk_func;
          template.dtpr_name = (char *)pkp->dtpk_name;
  
          /*
           * We want to find the most distinct of the module name, function
           * name, and name.  So for each one that is not a glob pattern or
           * empty string, we perform a lookup in the corresponding hash and
           * use the hash table with the fewest collisions to do our search.
           */
          if (pkp->dtpk_mmatch == &dtrace_match_string &&
              (len = dtrace_hash_collisions(dtrace_bymod, &template)) < best) {
                  best = len;
                  hash = dtrace_bymod;
          }
  
          if (pkp->dtpk_fmatch == &dtrace_match_string &&
              (len = dtrace_hash_collisions(dtrace_byfunc, &template)) < best) {
                  best = len;
                  hash = dtrace_byfunc;
          }
  
          if (pkp->dtpk_nmatch == &dtrace_match_string &&
              (len = dtrace_hash_collisions(dtrace_byname, &template)) < best) {
                  best = len;
                  hash = dtrace_byname;
          }
  
          /*
           * If we did not select a hash table, iterate over every probe and
           * invoke our callback for each one that matches our input probe key.
           */
          if (hash == NULL) {
                  for (i = 0; i < dtrace_nprobes; i++) {
                          if ((probe = dtrace_probes[i]) == NULL ||
                              dtrace_match_probe(probe, pkp, priv, uid,
                              zoneid) <= 0)
                                  continue;
  
                          nmatched++;
  
                          if ((*matched)(probe, arg) != DTRACE_MATCH_NEXT)
                                  break;
                  }
  
                  return (nmatched);
          }
  
          /*
           * If we selected a hash table, iterate over each probe of the same key
           * name and invoke the callback for every probe that matches the other
           * attributes of our input probe key.
           */
          for (probe = dtrace_hash_lookup(hash, &template); probe != NULL;
              probe = *(DTRACE_HASHNEXT(hash, probe))) {
  
                  if (dtrace_match_probe(probe, pkp, priv, uid, zoneid) <= 0)
                          continue;
  
                  nmatched++;
  
                  if ((*matched)(probe, arg) != DTRACE_MATCH_NEXT)
                          break;
          }
  
          return (nmatched);
  }
  
  /*
   * Return the function pointer dtrace_probecmp() should use to compare the
   * specified pattern with a string.  For NULL or empty patterns, we select
   * dtrace_match_nul().  For glob pattern strings, we use dtrace_match_glob().
   * For non-empty non-glob strings, we use dtrace_match_string().
   */
  static dtrace_probekey_f *
  dtrace_probekey_func(const char *p)
  {
          char c;
  
          if (p == NULL || *p == '\0')
                  return (&dtrace_match_nul);
  
          while ((c = *p++) != '\0') {
                  if (c == '[' || c == '?' || c == '*' || c == '\\')
                          return (&dtrace_match_glob);
          }
  
          return (&dtrace_match_string);
  }
  
  /*
   * Build a probe comparison key for use with dtrace_match_probe() from the
   * given probe description.  By convention, a null key only matches anchored
   * probes: if each field is the empty string, reset dtpk_fmatch to
   * dtrace_match_nonzero().
   */
  static void
  dtrace_probekey(dtrace_probedesc_t *pdp, dtrace_probekey_t *pkp)
  {
          pkp->dtpk_prov = pdp->dtpd_provider;
          pkp->dtpk_pmatch = dtrace_probekey_func(pdp->dtpd_provider);
  
          pkp->dtpk_mod = pdp->dtpd_mod;
          pkp->dtpk_mmatch = dtrace_probekey_func(pdp->dtpd_mod);
  
          pkp->dtpk_func = pdp->dtpd_func;
          pkp->dtpk_fmatch = dtrace_probekey_func(pdp->dtpd_func);
  
          pkp->dtpk_name = pdp->dtpd_name;
          pkp->dtpk_nmatch = dtrace_probekey_func(pdp->dtpd_name);
  
          pkp->dtpk_id = pdp->dtpd_id;
  
          if (pkp->dtpk_id == DTRACE_IDNONE &&
              pkp->dtpk_pmatch == &dtrace_match_nul &&
              pkp->dtpk_mmatch == &dtrace_match_nul &&
              pkp->dtpk_fmatch == &dtrace_match_nul &&
              pkp->dtpk_nmatch == &dtrace_match_nul)
                  pkp->dtpk_fmatch = &dtrace_match_nonzero;
  }
  
  /*
   * DTrace Provider-to-Framework API Functions
   *
   * These functions implement much of the Provider-to-Framework API, as
   * described in <sys/dtrace.h>.  The parts of the API not in this section are
   * the functions in the API for probe management (found below), and
   * dtrace_probe() itself (found above).
   */
  
  /*
   * Register the calling provider with the DTrace framework.  This should
   * generally be called by DTrace providers in their attach(9E) entry point.
   */
  int
  dtrace_register(const char *name, const dtrace_pattr_t *pap, uint32_t priv,
      cred_t *cr, const dtrace_pops_t *pops, void *arg, dtrace_provider_id_t *idp)
  {
          dtrace_provider_t *provider;
  
          if (name == NULL || pap == NULL || pops == NULL || idp == NULL) {
                  cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                      "arguments", name ? name : "<NULL>");
                  return (EINVAL);
          }
  
          if (name[0] == '\0' || dtrace_badname(name)) {
                  cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                      "provider name", name);
                  return (EINVAL);
          }
  
          if ((pops->dtps_provide == NULL && pops->dtps_provide_module == NULL) ||
              pops->dtps_enable == NULL || pops->dtps_disable == NULL ||
              pops->dtps_destroy == NULL ||
              ((pops->dtps_resume == NULL) != (pops->dtps_suspend == NULL))) {
                  cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                      "provider ops", name);
                  return (EINVAL);
          }
  
          if (dtrace_badattr(&pap->dtpa_provider) ||
              dtrace_badattr(&pap->dtpa_mod) ||
              dtrace_badattr(&pap->dtpa_func) ||
              dtrace_badattr(&pap->dtpa_name) ||
              dtrace_badattr(&pap->dtpa_args)) {
                  cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                      "provider attributes", name);
                  return (EINVAL);
          }
  
          if (priv & ~DTRACE_PRIV_ALL) {
                  cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                      "privilege attributes", name);
                  return (EINVAL);
          }
  
          if ((priv & DTRACE_PRIV_KERNEL) &&
              (priv & (DTRACE_PRIV_USER | DTRACE_PRIV_OWNER)) &&
              pops->dtps_usermode == NULL) {
                  cmn_err(CE_WARN, "failed to register provider '%s': need "
                      "dtps_usermode() op for given privilege attributes", name);
                  return (EINVAL);
          }
  
          provider = kmem_zalloc(sizeof (dtrace_provider_t), KM_SLEEP);
          provider->dtpv_name = kmem_alloc(strlen(name) + 1, KM_SLEEP);
          (void) strcpy(provider->dtpv_name, name);
  
          provider->dtpv_attr = *pap;
          provider->dtpv_priv.dtpp_flags = priv;
          if (cr != NULL) {
                  provider->dtpv_priv.dtpp_uid = crgetuid(cr);
                  provider->dtpv_priv.dtpp_zoneid = crgetzoneid(cr);
          }
          provider->dtpv_pops = *pops;
  
          if (pops->dtps_provide == NULL) {
                  ASSERT(pops->dtps_provide_module != NULL);
                  provider->dtpv_pops.dtps_provide =
                      (void (*)(void *, dtrace_probedesc_t *))dtrace_nullop;
          }
  
          if (pops->dtps_provide_module == NULL) {
                  ASSERT(pops->dtps_provide != NULL);
                  provider->dtpv_pops.dtps_provide_module =
                      (void (*)(void *, modctl_t *))dtrace_nullop;
          }
  
          if (pops->dtps_suspend == NULL) {
                  ASSERT(pops->dtps_resume == NULL);
                  provider->dtpv_pops.dtps_suspend =
                      (void (*)(void *, dtrace_id_t, void *))dtrace_nullop;
                  provider->dtpv_pops.dtps_resume =
                      (void (*)(void *, dtrace_id_t, void *))dtrace_nullop;
          }
  
          provider->dtpv_arg = arg;
          *idp = (dtrace_provider_id_t)provider;
  
          if (pops == &dtrace_provider_ops) {
                  ASSERT(MUTEX_HELD(&dtrace_provider_lock));
                  ASSERT(MUTEX_HELD(&dtrace_lock));
                  ASSERT(dtrace_anon.dta_enabling == NULL);
  
                  /*
                   * We make sure that the DTrace provider is at the head of
                   * the provider chain.
                   */
                  provider->dtpv_next = dtrace_provider;
                  dtrace_provider = provider;
                  return (0);
          }
  
          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);
  
          /*
           * If there is at least one provider registered, we'll add this
           * provider after the first provider.
           */
          if (dtrace_provider != NULL) {
                  provider->dtpv_next = dtrace_provider->dtpv_next;
                  dtrace_provider->dtpv_next = provider;
          } else {
                  dtrace_provider = provider;
          }
  
          if (dtrace_retained != NULL) {
                  dtrace_enabling_provide(provider);
  
                  /*
                   * Now we need to call dtrace_enabling_matchall() -- which
                   * will acquire cpu_lock and dtrace_lock.  We therefore need
                   * to drop all of our locks before calling into it...
                   */
                  mutex_exit(&dtrace_lock);
                  mutex_exit(&dtrace_provider_lock);
                  dtrace_enabling_matchall();
  
                  return (0);
          }
  
          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);
  
          return (0);
  }
  
  /*
   * Unregister the specified provider from the DTrace framework.  This should
   * generally be called by DTrace providers in their detach(9E) entry point.
   */
  int
  dtrace_unregister(dtrace_provider_id_t id)
  {
          dtrace_provider_t *old = (dtrace_provider_t *)id;
          dtrace_provider_t *prev = NULL;
          int i, self = 0, noreap = 0;
          dtrace_probe_t *probe, *first = NULL;
  
          if (old->dtpv_pops.dtps_enable ==
              (void (*)(void *, dtrace_id_t, void *))dtrace_nullop) {
                  /*
                   * If DTrace itself is the provider, we're called with locks
                   * already held.
                   */
                  ASSERT(old == dtrace_provider);
  #ifdef illumos
                  ASSERT(dtrace_devi != NULL);
  #endif
                  ASSERT(MUTEX_HELD(&dtrace_provider_lock));
                  ASSERT(MUTEX_HELD(&dtrace_lock));
                  self = 1;
  
                  if (dtrace_provider->dtpv_next != NULL) {
                          /*
                           * There's another provider here; return failure.
                           */
                          return (EBUSY);
                  }
          } else {
                  mutex_enter(&dtrace_provider_lock);
  #ifdef illumos
                  mutex_enter(&mod_lock);
  #endif
                  mutex_enter(&dtrace_lock);
          }
  
          /*
           * If anyone has /dev/dtrace open, or if there are anonymous enabled
           * probes, we refuse to let providers slither away, unless this
           * provider has already been explicitly invalidated.
           */
          if (!old->dtpv_defunct &&
              (dtrace_opens || (dtrace_anon.dta_state != NULL &&
              dtrace_anon.dta_state->dts_necbs > 0))) {
                  if (!self) {
                          mutex_exit(&dtrace_lock);
  #ifdef illumos
                          mutex_exit(&mod_lock);
  #endif
                          mutex_exit(&dtrace_provider_lock);
                  }
                  return (EBUSY);
          }
  
          /*
           * Attempt to destroy the probes associated with this provider.
           */
          for (i = 0; i < dtrace_nprobes; i++) {
                  if ((probe = dtrace_probes[i]) == NULL)
                          continue;
  
                  if (probe->dtpr_provider != old)
                          continue;
  
                  if (probe->dtpr_ecb == NULL)
                          continue;
  
                  /*
                   * If we are trying to unregister a defunct provider, and the
                   * provider was made defunct within the interval dictated by
                   * dtrace_unregister_defunct_reap, we'll (asynchronously)
                   * attempt to reap our enablings.  To denote that the provider
                   * should reattempt to unregister itself at some point in the
                   * future, we will return a differentiable error code (EAGAIN
                   * instead of EBUSY) in this case.
                   */
                  if (dtrace_gethrtime() - old->dtpv_defunct >
                      dtrace_unregister_defunct_reap)
                          noreap = 1;
  
                  if (!self) {
                          mutex_exit(&dtrace_lock);
  #ifdef illumos
                          mutex_exit(&mod_lock);
  #endif
                          mutex_exit(&dtrace_provider_lock);
                  }
  
                  if (noreap)
                          return (EBUSY);
  
                  (void) taskq_dispatch(dtrace_taskq,
                      (task_func_t *)dtrace_enabling_reap, NULL, TQ_SLEEP);
  
                  return (EAGAIN);
          }
  
          /*
           * All of the probes for this provider are disabled; we can safely
           * remove all of them from their hash chains and from the probe array.
           */
          for (i = 0; i < dtrace_nprobes; i++) {
                  if ((probe = dtrace_probes[i]) == NULL)
                          continue;
  
                  if (probe->dtpr_provider != old)
                          continue;
  
                  dtrace_probes[i] = NULL;
  
                  dtrace_hash_remove(dtrace_bymod, probe);
                  dtrace_hash_remove(dtrace_byfunc, probe);
                  dtrace_hash_remove(dtrace_byname, probe);
  
                  if (first == NULL) {
                          first = probe;
                          probe->dtpr_nextmod = NULL;
                  } else {
                          probe->dtpr_nextmod = first;
                          first = probe;
                  }
          }
  
          /*
           * The provider's probes have been removed from the hash chains and
           * from the probe array.  Now issue a dtrace_sync() to be sure that
           * everyone has cleared out from any probe array processing.
           */
          dtrace_sync();
  
          for (probe = first; probe != NULL; probe = first) {
                  first = probe->dtpr_nextmod;
  
                  old->dtpv_pops.dtps_destroy(old->dtpv_arg, probe->dtpr_id,
                      probe->dtpr_arg);
                  kmem_free(probe->dtpr_mod, strlen(probe->dtpr_mod) + 1);
                  kmem_free(probe->dtpr_func, strlen(probe->dtpr_func) + 1);
                  kmem_free(probe->dtpr_name, strlen(probe->dtpr_name) + 1);
  #ifdef illumos
                  vmem_free(dtrace_arena, (void *)(uintptr_t)(probe->dtpr_id), 1);
  #else
                  free_unr(dtrace_arena, probe->dtpr_id);
  #endif
                  kmem_free(probe, sizeof (dtrace_probe_t));
          }
  
          if ((prev = dtrace_provider) == old) {
  #ifdef illumos
                  ASSERT(self || dtrace_devi == NULL);
                  ASSERT(old->dtpv_next == NULL || dtrace_devi == NULL);
  #endif
                  dtrace_provider = old->dtpv_next;
          } else {
                  while (prev != NULL && prev->dtpv_next != old)
                          prev = prev->dtpv_next;
  
                  if (prev == NULL) {
                          panic("attempt to unregister non-existent "
                              "dtrace provider %p\n", (void *)id);
                  }
  
                  prev->dtpv_next = old->dtpv_next;
          }
  
          if (!self) {
                  mutex_exit(&dtrace_lock);
  #ifdef illumos
                  mutex_exit(&mod_lock);
  #endif
                  mutex_exit(&dtrace_provider_lock);
          }
  
          kmem_free(old->dtpv_name, strlen(old->dtpv_name) + 1);
          kmem_free(old, sizeof (dtrace_provider_t));
  
          return (0);
  }
  
  /*
   * Invalidate the specified provider.  All subsequent probe lookups for the
   * specified provider will fail, but its probes will not be removed.
   */
  void
  dtrace_invalidate(dtrace_provider_id_t id)
  {
          dtrace_provider_t *pvp = (dtrace_provider_t *)id;
  
          ASSERT(pvp->dtpv_pops.dtps_enable !=
              (void (*)(void *, dtrace_id_t, void *))dtrace_nullop);
  
          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);
  
          pvp->dtpv_defunct = dtrace_gethrtime();
  
          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);
  }
  
  /*
   * Indicate whether or not DTrace has attached.
   */
  int
  dtrace_attached(void)
  {
          /*
           * dtrace_provider will be non-NULL iff the DTrace driver has
           * attached.  (It's non-NULL because DTrace is always itself a
           * provider.)
           */
          return (dtrace_provider != NULL);
  }
  
  /*
   * Remove all the unenabled probes for the given provider.  This function is
   * not unlike dtrace_unregister(), except that it doesn't remove the provider
   * -- just as many of its associated probes as it can.
   */
  int
  dtrace_condense(dtrace_provider_id_t id)
  {
          dtrace_provider_t *prov = (dtrace_provider_t *)id;
          int i;
          dtrace_probe_t *probe;
  
          /*
           * Make sure this isn't the dtrace provider itself.
           */
          ASSERT(prov->dtpv_pops.dtps_enable !=
              (void (*)(void *, dtrace_id_t, void *))dtrace_nullop);
  
          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);
  
          /*
           * Attempt to destroy the probes associated with this provider.
           */
          for (i = 0; i < dtrace_nprobes; i++) {
                  if ((probe = dtrace_probes[i]) == NULL)
                          continue;
  
                  if (probe->dtpr_provider != prov)
                          continue;
  
                  if (probe->dtpr_ecb != NULL)
                          continue;
  
                  dtrace_probes[i] = NULL;
  
                  dtrace_hash_remove(dtrace_bymod, probe);
                  dtrace_hash_remove(dtrace_byfunc, probe);
                  dtrace_hash_remove(dtrace_byname, probe);
  
                  prov->dtpv_pops.dtps_destroy(prov->dtpv_arg, i + 1,
                      probe->dtpr_arg);
                  kmem_free(probe->dtpr_mod, strlen(probe->dtpr_mod) + 1);
                  kmem_free(probe->dtpr_func, strlen(probe->dtpr_func) + 1);
                  kmem_free(probe->dtpr_name, strlen(probe->dtpr_name) + 1);
                  kmem_free(probe, sizeof (dtrace_probe_t));
  #ifdef illumos
                  vmem_free(dtrace_arena, (void *)((uintptr_t)i + 1), 1);
  #else
                  free_unr(dtrace_arena, i + 1);
  #endif
          }
  
          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);
  
          return (0);
  }
  
  /*
   * DTrace Probe Management Functions
   *
   * The functions in this section perform the DTrace probe management,
   * including functions to create probes, look-up probes, and call into the
   * providers to request that probes be provided.  Some of these functions are
   * in the Provider-to-Framework API; these functions can be identified by the
   * fact that they are not declared "static".
   */
  
  /*
   * Create a probe with the specified module name, function name, and name.
   */
  dtrace_id_t
  dtrace_probe_create(dtrace_provider_id_t prov, const char *mod,
      const char *func, const char *name, int aframes, void *arg)
  {
          dtrace_probe_t *probe, **probes;
          dtrace_provider_t *provider = (dtrace_provider_t *)prov;
          dtrace_id_t id;
  
          if (provider == dtrace_provider) {
                  ASSERT(MUTEX_HELD(&dtrace_lock));
          } else {
                  mutex_enter(&dtrace_lock);
          }
  
  #ifdef illumos
          id = (dtrace_id_t)(uintptr_t)vmem_alloc(dtrace_arena, 1,
              VM_BESTFIT | VM_SLEEP);
  #else
          id = alloc_unr(dtrace_arena);
  #endif
          probe = kmem_zalloc(sizeof (dtrace_probe_t), KM_SLEEP);
  
          probe->dtpr_id = id;
          probe->dtpr_gen = dtrace_probegen++;
          probe->dtpr_mod = dtrace_strdup(mod);
          probe->dtpr_func = dtrace_strdup(func);
          probe->dtpr_name = dtrace_strdup(name);
          probe->dtpr_arg = arg;
          probe->dtpr_aframes = aframes;
          probe->dtpr_provider = provider;
  
          dtrace_hash_add(dtrace_bymod, probe);
          dtrace_hash_add(dtrace_byfunc, probe);
          dtrace_hash_add(dtrace_byname, probe);
  
          if (id - 1 >= dtrace_nprobes) {
                  size_t osize = dtrace_nprobes * sizeof (dtrace_probe_t *);
                  size_t nsize = osize << 1;
  
                  if (nsize == 0) {
                          ASSERT(osize == 0);
                          ASSERT(dtrace_probes == NULL);
                          nsize = sizeof (dtrace_probe_t *);
                  }
  
                  probes = kmem_zalloc(nsize, KM_SLEEP);
  
                  if (dtrace_probes == NULL) {
                          ASSERT(osize == 0);
                          dtrace_probes = probes;
                          dtrace_nprobes = 1;
                  } else {
                          dtrace_probe_t **oprobes = dtrace_probes;
  
                          bcopy(oprobes, probes, osize);
                          dtrace_membar_producer();
                          dtrace_probes = probes;
  
                          dtrace_sync();
  
                          /*
                           * All CPUs are now seeing the new probes array; we can
                           * safely free the old array.
                           */
                          kmem_free(oprobes, osize);
                          dtrace_nprobes <<= 1;
                  }
  
                  ASSERT(id - 1 < dtrace_nprobes);
          }
  
          ASSERT(dtrace_probes[id - 1] == NULL);
          dtrace_probes[id - 1] = probe;
  
          if (provider != dtrace_provider)
                  mutex_exit(&dtrace_lock);
  
          return (id);
  }
  
  static dtrace_probe_t *
  dtrace_probe_lookup_id(dtrace_id_t id)
  {
          ASSERT(MUTEX_HELD(&dtrace_lock));
  
          if (id == 0 || id > dtrace_nprobes)
                  return (NULL);
  
          return (dtrace_probes[id - 1]);
  }
  
  static int
  dtrace_probe_lookup_match(dtrace_probe_t *probe, void *arg)
  {
          *((dtrace_id_t *)arg) = probe->dtpr_id;
  
          return (DTRACE_MATCH_DONE);
  }
  
  /*
   * Look up a probe based on provider and one or more of module name, function
   * name and probe name.
   */
  dtrace_id_t
  dtrace_probe_lookup(dtrace_provider_id_t prid, char *mod,
      char *func, char *name)
  {
          dtrace_probekey_t pkey;
          dtrace_id_t id;
          int match;
  
          pkey.dtpk_prov = ((dtrace_provider_t *)prid)->dtpv_name;
          pkey.dtpk_pmatch = &dtrace_match_string;
          pkey.dtpk_mod = mod;
          pkey.dtpk_mmatch = mod ? &dtrace_match_string : &dtrace_match_nul;
          pkey.dtpk_func = func;
          pkey.dtpk_fmatch = func ? &dtrace_match_string : &dtrace_match_nul;
          pkey.dtpk_name = name;
          pkey.dtpk_nmatch = name ? &dtrace_match_string : &dtrace_match_nul;
          pkey.dtpk_id = DTRACE_IDNONE;
  
          mutex_enter(&dtrace_lock);
          match = dtrace_match(&pkey, DTRACE_PRIV_ALL, 0, 0,
              dtrace_probe_lookup_match, &id);
          mutex_exit(&dtrace_lock);
  
          ASSERT(match == 1 || match == 0);
          return (match ? id : 0);
  }
  
  /*
   * Returns the probe argument associated with the specified probe.
   */
  void *
  dtrace_probe_arg(dtrace_provider_id_t id, dtrace_id_t pid)
  {
          dtrace_probe_t *probe;
          void *rval = NULL;
  
          mutex_enter(&dtrace_lock);
  
          if ((probe = dtrace_probe_lookup_id(pid)) != NULL &&
              probe->dtpr_provider == (dtrace_provider_t *)id)
                  rval = probe->dtpr_arg;
  
          mutex_exit(&dtrace_lock);
  
          return (rval);
  }
  
  /*
   * Copy a probe into a probe description.
   */
  static void
  dtrace_probe_description(const dtrace_probe_t *prp, dtrace_probedesc_t *pdp)
  {
          bzero(pdp, sizeof (dtrace_probedesc_t));
          pdp->dtpd_id = prp->dtpr_id;
  
          (void) strncpy(pdp->dtpd_provider,
              prp->dtpr_provider->dtpv_name, DTRACE_PROVNAMELEN - 1);
  
          (void) strncpy(pdp->dtpd_mod, prp->dtpr_mod, DTRACE_MODNAMELEN - 1);
          (void) strncpy(pdp->dtpd_func, prp->dtpr_func, DTRACE_FUNCNAMELEN - 1);
          (void) strncpy(pdp->dtpd_name, prp->dtpr_name, DTRACE_NAMELEN - 1);
  }
  
  /*
   * Called to indicate that a probe -- or probes -- should be provided by a
   * specfied provider.  If the specified description is NULL, the provider will
   * be told to provide all of its probes.  (This is done whenever a new
   * consumer comes along, or whenever a retained enabling is to be matched.) If
   * the specified description is non-NULL, the provider is given the
   * opportunity to dynamically provide the specified probe, allowing providers
   * to support the creation of probes on-the-fly.  (So-called _autocreated_
   * probes.)  If the provider is NULL, the operations will be applied to all
   * providers; if the provider is non-NULL the operations will only be applied
   * to the specified provider.  The dtrace_provider_lock must be held, and the
   * dtrace_lock must _not_ be held -- the provider's dtps_provide() operation
   * will need to grab the dtrace_lock when it reenters the framework through
   * dtrace_probe_lookup(), dtrace_probe_create(), etc.
   */
  static void
  dtrace_probe_provide(dtrace_probedesc_t *desc, dtrace_provider_t *prv)
  {
  #ifdef illumos
          modctl_t *ctl;
  #endif
          int all = 0;
  
          ASSERT(MUTEX_HELD(&dtrace_provider_lock));
  
          if (prv == NULL) {
                  all = 1;
                  prv = dtrace_provider;
          }
  
          do {
                  /*
                   * First, call the blanket provide operation.
                   */
                  prv->dtpv_pops.dtps_provide(prv->dtpv_arg, desc);
  
  #ifdef illumos
                  /*
                   * Now call the per-module provide operation.  We will grab
                   * mod_lock to prevent the list from being modified.  Note
                   * that this also prevents the mod_busy bits from changing.
                   * (mod_busy can only be changed with mod_lock held.)
                   */
                  mutex_enter(&mod_lock);
  
                  ctl = &modules;
                  do {
                          if (ctl->mod_busy || ctl->mod_mp == NULL)
                                  continue;
  
                          prv->dtpv_pops.dtps_provide_module(prv->dtpv_arg, ctl);
  
                  } while ((ctl = ctl->mod_next) != &modules);
  
                  mutex_exit(&mod_lock);
  #endif
          } while (all && (prv = prv->dtpv_next) != NULL);
  }
  
  #ifdef illumos
  /*
   * Iterate over each probe, and call the Framework-to-Provider API function
   * denoted by offs.
   */
  static void
  dtrace_probe_foreach(uintptr_t offs)
  {
          dtrace_provider_t *prov;
          void (*func)(void *, dtrace_id_t, void *);
          dtrace_probe_t *probe;
          dtrace_icookie_t cookie;
          int i;
  
          /*
           * We disable interrupts to walk through the probe array.  This is
           * safe -- the dtrace_sync() in dtrace_unregister() assures that we
           * won't see stale data.
           */
          cookie = dtrace_interrupt_disable();
  
          for (i = 0; i < dtrace_nprobes; i++) {
                  if ((probe = dtrace_probes[i]) == NULL)
                          continue;
  
                  if (probe->dtpr_ecb == NULL) {
                          /*
                           * This probe isn't enabled -- don't call the function.
                           */
                          continue;
                  }
  
                  prov = probe->dtpr_provider;
                  func = *((void(**)(void *, dtrace_id_t, void *))
                      ((uintptr_t)&prov->dtpv_pops + offs));
  
                  func(prov->dtpv_arg, i + 1, probe->dtpr_arg);
          }
  
          dtrace_interrupt_enable(cookie);
  }
  #endif
  
  static int
  dtrace_probe_enable(dtrace_probedesc_t *desc, dtrace_enabling_t *enab)
  {
          dtrace_probekey_t pkey;
          uint32_t priv;
          uid_t uid;
          zoneid_t zoneid;
  
          ASSERT(MUTEX_HELD(&dtrace_lock));
          dtrace_ecb_create_cache = NULL;
  
          if (desc == NULL) {
                  /*
                   * If we're passed a NULL description, we're being asked to
                   * create an ECB with a NULL probe.
                   */
                  (void) dtrace_ecb_create_enable(NULL, enab);
                  return (0);
          }
  
          dtrace_probekey(desc, &pkey);
          dtrace_cred2priv(enab->dten_vstate->dtvs_state->dts_cred.dcr_cred,
              &priv, &uid, &zoneid);
  
          return (dtrace_match(&pkey, priv, uid, zoneid, dtrace_ecb_create_enable,
              enab));
  }
  
  /*
   * DTrace Helper Provider Functions
   */
  static void
  dtrace_dofattr2attr(dtrace_attribute_t *attr, const dof_attr_t dofattr)
  {
          attr->dtat_name = DOF_ATTR_NAME(dofattr);
          attr->dtat_data = DOF_ATTR_DATA(dofattr);
          attr->dtat_class = DOF_ATTR_CLASS(dofattr);
  }
  
  static void
  dtrace_dofprov2hprov(dtrace_helper_provdesc_t *hprov,
      const dof_provider_t *dofprov, char *strtab)
  {
          hprov->dthpv_provname = strtab + dofprov->dofpv_name;
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_provider,
              dofprov->dofpv_provattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_mod,
              dofprov->dofpv_modattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_func,
              dofprov->dofpv_funcattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_name,
              dofprov->dofpv_nameattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_args,
              dofprov->dofpv_argsattr);
  }
  
  static void
  dtrace_helper_provide_one(dof_helper_t *dhp, dof_sec_t *sec, pid_t pid)
  {
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          dof_sec_t *str_sec, *prb_sec, *arg_sec, *off_sec, *enoff_sec;
          dof_provider_t *provider;
          dof_probe_t *probe;
          uint32_t *off, *enoff;
          uint8_t *arg;
          char *strtab;
          uint_t i, nprobes;
          dtrace_helper_provdesc_t dhpv;
          dtrace_helper_probedesc_t dhpb;
          dtrace_meta_t *meta = dtrace_meta_pid;
          dtrace_mops_t *mops = &meta->dtm_mops;
          void *parg;
  
          provider = (dof_provider_t *)(uintptr_t)(daddr + sec->dofs_offset);
          str_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_strtab * dof->dofh_secsize);
          prb_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_probes * dof->dofh_secsize);
          arg_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_prargs * dof->dofh_secsize);
          off_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_proffs * dof->dofh_secsize);
  
          strtab = (char *)(uintptr_t)(daddr + str_sec->dofs_offset);
          off = (uint32_t *)(uintptr_t)(daddr + off_sec->dofs_offset);
          arg = (uint8_t *)(uintptr_t)(daddr + arg_sec->dofs_offset);
          enoff = NULL;
  
          /*
           * See dtrace_helper_provider_validate().
           */
          if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1 &&
              provider->dofpv_prenoffs != DOF_SECT_NONE) {
                  enoff_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
                      provider->dofpv_prenoffs * dof->dofh_secsize);
                  enoff = (uint32_t *)(uintptr_t)(daddr + enoff_sec->dofs_offset);
          }
  
          nprobes = prb_sec->dofs_size / prb_sec->dofs_entsize;
  
          /*
           * Create the provider.
           */
          dtrace_dofprov2hprov(&dhpv, provider, strtab);
  
          if ((parg = mops->dtms_provide_pid(meta->dtm_arg, &dhpv, pid)) == NULL)
                  return;
  
          meta->dtm_count++;
  
          /*
           * Create the probes.
           */
          for (i = 0; i < nprobes; i++) {
                  probe = (dof_probe_t *)(uintptr_t)(daddr +
                      prb_sec->dofs_offset + i * prb_sec->dofs_entsize);
  
                  /* See the check in dtrace_helper_provider_validate(). */
                  if (strlen(strtab + probe->dofpr_func) >= DTRACE_FUNCNAMELEN)
                          continue;
  
                  dhpb.dthpb_mod = dhp->dofhp_mod;
                  dhpb.dthpb_func = strtab + probe->dofpr_func;
                  dhpb.dthpb_name = strtab + probe->dofpr_name;
                  dhpb.dthpb_base = probe->dofpr_addr;
                  dhpb.dthpb_offs = off + probe->dofpr_offidx;
                  dhpb.dthpb_noffs = probe->dofpr_noffs;
                  if (enoff != NULL) {
                          dhpb.dthpb_enoffs = enoff + probe->dofpr_enoffidx;
                          dhpb.dthpb_nenoffs = probe->dofpr_nenoffs;
                  } else {
                          dhpb.dthpb_enoffs = NULL;
                          dhpb.dthpb_nenoffs = 0;
                  }
                  dhpb.dthpb_args = arg + probe->dofpr_argidx;
                  dhpb.dthpb_nargc = probe->dofpr_nargc;
                  dhpb.dthpb_xargc = probe->dofpr_xargc;
                  dhpb.dthpb_ntypes = strtab + probe->dofpr_nargv;
                  dhpb.dthpb_xtypes = strtab + probe->dofpr_xargv;
  
                  mops->dtms_create_probe(meta->dtm_arg, parg, &dhpb);
          }
  }
  
  static void
  dtrace_helper_provide(dof_helper_t *dhp, pid_t pid)
  {
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          int i;
  
          ASSERT(MUTEX_HELD(&dtrace_meta_lock));
  
          for (i = 0; i < dof->dofh_secnum; i++) {
                  dof_sec_t *sec = (dof_sec_t *)(uintptr_t)(daddr +
                      dof->dofh_secoff + i * dof->dofh_secsize);
  
                  if (sec->dofs_type != DOF_SECT_PROVIDER)
                          continue;
  
                  dtrace_helper_provide_one(dhp, sec, pid);
          }
  
          /*
           * We may have just created probes, so we must now rematch against
           * any retained enablings.  Note that this call will acquire both
           * cpu_lock and dtrace_lock; the fact that we are holding
           * dtrace_meta_lock now is what defines the ordering with respect to
           * these three locks.
           */
          dtrace_enabling_matchall();
  }
  
  static void
  dtrace_helper_provider_remove_one(dof_helper_t *dhp, dof_sec_t *sec, pid_t pid)
  {
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          dof_sec_t *str_sec;
          dof_provider_t *provider;
          char *strtab;
          dtrace_helper_provdesc_t dhpv;
          dtrace_meta_t *meta = dtrace_meta_pid;
          dtrace_mops_t *mops = &meta->dtm_mops;
  
          provider = (dof_provider_t *)(uintptr_t)(daddr + sec->dofs_offset);
          str_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_strtab * dof->dofh_secsize);
  
          strtab = (char *)(uintptr_t)(daddr + str_sec->dofs_offset);
  
          /*
           * Create the provider.
           */
          dtrace_dofprov2hprov(&dhpv, provider, strtab);
  
          mops->dtms_remove_pid(meta->dtm_arg, &dhpv, pid);
  
          meta->dtm_count--;
  }
  
  static void
  dtrace_helper_provider_remove(dof_helper_t *dhp, pid_t pid)
  {
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          int i;
  
          ASSERT(MUTEX_HELD(&dtrace_meta_lock));
  
          for (i = 0; i < dof->dofh_secnum; i++) {
                  dof_sec_t *sec = (dof_sec_t *)(uintptr_t)(daddr +
                      dof->dofh_secoff + i * dof->dofh_secsize);
  
                  if (sec->dofs_type != DOF_SECT_PROVIDER)
                          continue;
  
                  dtrace_helper_provider_remove_one(dhp, sec, pid);
          }
  }
  
  /*
   * DTrace Meta Provider-to-Framework API Functions
   *
   * These functions implement the Meta Provider-to-Framework API, as described
   * in <sys/dtrace.h>.
   */
  int
  dtrace_meta_register(const char *name, const dtrace_mops_t *mops, void *arg,
      dtrace_meta_provider_id_t *idp)
  {
          dtrace_meta_t *meta;
          dtrace_helpers_t *help, *next;
          int i;
  
          *idp = DTRACE_METAPROVNONE;
  
          /*
           * We strictly don't need the name, but we hold onto it for
           * debuggability. All hail error queues!
           */
          if (name == NULL) {
                  cmn_err(CE_WARN, "failed to register meta-provider: "
                      "invalid name");
                  return (EINVAL);
          }
  
          if (mops == NULL ||
              mops->dtms_create_probe == NULL ||
              mops->dtms_provide_pid == NULL ||
              mops->dtms_remove_pid == NULL) {
                  cmn_err(CE_WARN, "failed to register meta-register %s: "
                      "invalid ops", name);
                  return (EINVAL);
          }
  
          meta = kmem_zalloc(sizeof (dtrace_meta_t), KM_SLEEP);
          meta->dtm_mops = *mops;
          meta->dtm_name = kmem_alloc(strlen(name) + 1, KM_SLEEP);
          (void) strcpy(meta->dtm_name, name);
          meta->dtm_arg = arg;
  
          mutex_enter(&dtrace_meta_lock);
          mutex_enter(&dtrace_lock);
  
          if (dtrace_meta_pid != NULL) {
                  mutex_exit(&dtrace_lock);
                  mutex_exit(&dtrace_meta_lock);
                  cmn_err(CE_WARN, "failed to register meta-register %s: "
                      "user-land meta-provider exists", name);
                  kmem_free(meta->dtm_name, strlen(meta->dtm_name) + 1);
                  kmem_free(meta, sizeof (dtrace_meta_t));
                  return (EINVAL);
          }
  
          dtrace_meta_pid = meta;
          *idp = (dtrace_meta_provider_id_t)meta;
  
          /*
           * If there are providers and probes ready to go, pass them
           * off to the new meta provider now.
           */
  
          help = dtrace_deferred_pid;
          dtrace_deferred_pid = NULL;
  
          mutex_exit(&dtrace_lock);
  
          while (help != NULL) {
                  for (i = 0; i < help->dthps_nprovs; i++) {
                          dtrace_helper_provide(&help->dthps_provs[i]->dthp_prov,
                              help->dthps_pid);
                  }
  
                  next = help->dthps_next;
                  help->dthps_next = NULL;
                  help->dthps_prev = NULL;
                  help->dthps_deferred = 0;
                  help = next;
          }
  
          mutex_exit(&dtrace_meta_lock);
  
          return (0);
  }
  
  int
  dtrace_meta_unregister(dtrace_meta_provider_id_t id)
  {
          dtrace_meta_t **pp, *old = (dtrace_meta_t *)id;
  
          mutex_enter(&dtrace_meta_lock);
          mutex_enter(&dtrace_lock);
  
          if (old == dtrace_meta_pid) {
                  pp = &dtrace_meta_pid;
          } else {
                  panic("attempt to unregister non-existent "
                      "dtrace meta-provider %p\n", (void *)old);
          }
  
          if (old->dtm_count != 0) {
                  mutex_exit(&dtrace_lock);
                  mutex_exit(&dtrace_meta_lock);
                  return (EBUSY);
          }
  
          *pp = NULL;
  
          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_meta_lock);
  
          kmem_free(old->dtm_name, strlen(old->dtm_name) + 1);
          kmem_free(old, sizeof (dtrace_meta_t));
  
          return (0);
  }
  
  
  /*
   * DTrace DIF Object Functions
   */
  static int
  dtrace_difo_err(uint_t pc, const char *format, ...)
  {
          if (dtrace_err_verbose) {
                  va_list alist;
  
                  (void) uprintf("dtrace DIF object error: [%u]: ", pc);
                  va_start(alist, format);
                  (void) vuprintf(format, alist);
                  va_end(alist);
          }
  
  #ifdef DTRACE_ERRDEBUG
          dtrace_errdebug(format);
  #endif
          return (1);
  }
  
  /*
   * Validate a DTrace DIF object by checking the IR instructions.  The following
   * rules are currently enforced by dtrace_difo_validate():
   *
   * 1. Each instruction must have a valid opcode
   * 2. Each register, string, variable, or subroutine reference must be valid
   * 3. No instruction can modify register %r0 (must be zero)
   * 4. All instruction reserved bits must be set to zero
   * 5. The last instruction must be a "ret" instruction
   * 6. All branch targets must reference a valid instruction _after_ the branch
   */
  static int
  dtrace_difo_validate(dtrace_difo_t *dp, dtrace_vstate_t *vstate, uint_t nregs,
      cred_t *cr)
  {
          int err = 0, i;
          int (*efunc)(uint_t pc, const char *, ...) = dtrace_difo_err;
          int kcheckload;
          uint_t pc;
          int maxglobal = -1, maxlocal = -1, maxtlocal = -1;
  
          kcheckload = cr == NULL ||
              (vstate->dtvs_state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL) == 0;
  
          dp->dtdo_destructive = 0;
  
          for (pc = 0; pc < dp->dtdo_len && err == 0; pc++) {
                  dif_instr_t instr = dp->dtdo_buf[pc];
  
                  uint_t r1 = DIF_INSTR_R1(instr);
                  uint_t r2 = DIF_INSTR_R2(instr);
                  uint_t rd = DIF_INSTR_RD(instr);
                  uint_t rs = DIF_INSTR_RS(instr);
                  uint_t label = DIF_INSTR_LABEL(instr);
                  uint_t v = DIF_INSTR_VAR(instr);
                  uint_t subr = DIF_INSTR_SUBR(instr);
                  uint_t type = DIF_INSTR_TYPE(instr);
                  uint_t op = DIF_INSTR_OP(instr);
  
                  switch (op) {
                  case DIF_OP_OR:
                  case DIF_OP_XOR:
                  case DIF_OP_AND:
                  case DIF_OP_SLL:
                  case DIF_OP_SRL:
                  case DIF_OP_SRA:
                  case DIF_OP_SUB:
                  case DIF_OP_ADD:
                  case DIF_OP_MUL:
                  case DIF_OP_SDIV:
                  case DIF_OP_UDIV:
                  case DIF_OP_SREM:
                  case DIF_OP_UREM:
                  case DIF_OP_COPYS:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r2);
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_NOT:
                  case DIF_OP_MOV:
                  case DIF_OP_ALLOCS:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_LDSB:
                  case DIF_OP_LDSH:
                  case DIF_OP_LDSW:
                  case DIF_OP_LDUB:
                  case DIF_OP_LDUH:
                  case DIF_OP_LDUW:
                  case DIF_OP_LDX:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          if (kcheckload)
                                  dp->dtdo_buf[pc] = DIF_INSTR_LOAD(op +
                                      DIF_OP_RLDSB - DIF_OP_LDSB, r1, rd);
                          break;
                  case DIF_OP_RLDSB:
                  case DIF_OP_RLDSH:
                  case DIF_OP_RLDSW:
                  case DIF_OP_RLDUB:
                  case DIF_OP_RLDUH:
                  case DIF_OP_RLDUW:
                  case DIF_OP_RLDX:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_ULDSB:
                  case DIF_OP_ULDSH:
                  case DIF_OP_ULDSW:
                  case DIF_OP_ULDUB:
                  case DIF_OP_ULDUH:
                  case DIF_OP_ULDUW:
                  case DIF_OP_ULDX:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_STB:
                  case DIF_OP_STH:
                  case DIF_OP_STW:
                  case DIF_OP_STX:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to 0 address\n");
                          break;
                  case DIF_OP_CMP:
                  case DIF_OP_SCMP:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r2);
                          if (rd != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          break;
                  case DIF_OP_TST:
                          if (r1 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r1);
                          if (r2 != 0 || rd != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          break;
                  case DIF_OP_BA:
                  case DIF_OP_BE:
                  case DIF_OP_BNE:
                  case DIF_OP_BG:
                  case DIF_OP_BGU:
                  case DIF_OP_BGE:
                  case DIF_OP_BGEU:
                  case DIF_OP_BL:
                  case DIF_OP_BLU:
                  case DIF_OP_BLE:
                  case DIF_OP_BLEU:
                          if (label >= dp->dtdo_len) {
                                  err += efunc(pc, "invalid branch target %u\n",
                                      label);
                          }
                          if (label <= pc) {
                                  err += efunc(pc, "backward branch to %u\n",
                                      label);
                          }
                          break;
                  case DIF_OP_RET:
                          if (r1 != 0 || r2 != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          break;
                  case DIF_OP_NOP:
                  case DIF_OP_POPTS:
                  case DIF_OP_FLUSHTS:
                          if (r1 != 0 || r2 != 0 || rd != 0)
                                  err += efunc(pc, "non-zero reserved bits\n");
                          break;
                  case DIF_OP_SETX:
                          if (DIF_INSTR_INTEGER(instr) >= dp->dtdo_intlen) {
                                  err += efunc(pc, "invalid integer ref %u\n",
                                      DIF_INSTR_INTEGER(instr));
                          }
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_SETS:
                          if (DIF_INSTR_STRING(instr) >= dp->dtdo_strlen) {
                                  err += efunc(pc, "invalid string ref %u\n",
                                      DIF_INSTR_STRING(instr));
                          }
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_LDGA:
                  case DIF_OP_LDTA:
                          if (r1 > DIF_VAR_ARRAY_MAX)
                                  err += efunc(pc, "invalid array %u\n", r1);
                          if (r2 >= nregs)
                                  err += efunc(pc, "invalid register %u\n", r2);
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_LDGS:
                  case DIF_OP_LDTS:
                  case DIF_OP_LDLS:
                  case DIF_OP_LDGAA:
                  case DIF_OP_LDTAA:
                          if (v < DIF_VAR_OTHER_MIN || v > DIF_VAR_OTHER_MAX)
                                  err += efunc(pc, "invalid variable %u\n", v);
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          if (rd == 0)
                                  err += efunc(pc, "cannot write to %%r0\n");
                          break;
                  case DIF_OP_STGS:
                  case DIF_OP_STTS:
                  case DIF_OP_STLS:
                  case DIF_OP_STGAA:
                  case DIF_OP_STTAA:
                          if (v < DIF_VAR_OTHER_UBASE || v > DIF_VAR_OTHER_MAX)
                                  err += efunc(pc, "invalid variable %u\n", v);
                          if (rs >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                          break;
                  case DIF_OP_CALL:
                          if (subr > DIF_SUBR_MAX)
                                  err += efunc(pc, "invalid subr %u\n", subr);
                          if (rd >= nregs)
                                  err += efunc(pc, "invalid register %u\n", rd);
                         if (rd == 0)
                                 err += efunc(pc, "cannot write to %%r0\n");
 
                         if (subr == DIF_SUBR_COPYOUT ||
                             subr == DIF_SUBR_COPYOUTSTR) {
                                 dp->dtdo_destructive = 1;
                         }
 
                         if (subr == DIF_SUBR_GETF) {
 #ifdef __FreeBSD__
                                 err += efunc(pc, "getf() not supported");
 #else
                                 /*
                                  * If we have a getf() we need to record that
                                  * in our state.  Note that our state can be
                                  * NULL if this is a helper -- but in that
                                  * case, the call to getf() is itself illegal,
                                  * and will be caught (slightly later) when
                                  * the helper is validated.
                                  */
                                 if (vstate->dtvs_state != NULL)
                                         vstate->dtvs_state->dts_getf++;
 #endif
                         }
 
                         break;
                 case DIF_OP_PUSHTR:
                         if (type != DIF_TYPE_STRING && type != DIF_TYPE_CTF)
                                 err += efunc(pc, "invalid ref type %u\n", type);
                         if (r2 >= nregs)
                                 err += efunc(pc, "invalid register %u\n", r2);
                         if (rs >= nregs)
                                 err += efunc(pc, "invalid register %u\n", rs);
                         break;
                 case DIF_OP_PUSHTV:
                         if (type != DIF_TYPE_CTF)
                                 err += efunc(pc, "invalid val type %u\n", type);
                         if (r2 >= nregs)
                                 err += efunc(pc, "invalid register %u\n", r2);
                         if (rs >= nregs)
                                 err += efunc(pc, "invalid register %u\n", rs);
                         break;
                 default:
                         err += efunc(pc, "invalid opcode %u\n",
                             DIF_INSTR_OP(instr));
                 }
         }
 
         if (dp->dtdo_len != 0 &&
             DIF_INSTR_OP(dp->dtdo_buf[dp->dtdo_len - 1]) != DIF_OP_RET) {
                 err += efunc(dp->dtdo_len - 1,
                     "expected 'ret' as last DIF instruction\n");
         }
 
         if (!(dp->dtdo_rtype.dtdt_flags & (DIF_TF_BYREF | DIF_TF_BYUREF))) {
                 /*
                  * If we're not returning by reference, the size must be either
                  * 0 or the size of one of the base types.
                  */
                 switch (dp->dtdo_rtype.dtdt_size) {
                 case 0:
                 case sizeof (uint8_t):
                 case sizeof (uint16_t):
                 case sizeof (uint32_t):
                 case sizeof (uint64_t):
                         break;
 
                 default:
                         err += efunc(dp->dtdo_len - 1, "bad return size\n");
                 }
         }
 
         for (i = 0; i < dp->dtdo_varlen && err == 0; i++) {
                 dtrace_difv_t *v = &dp->dtdo_vartab[i], *existing = NULL;
                 dtrace_diftype_t *vt, *et;
                 uint_t id, ndx;
 
                 if (v->dtdv_scope != DIFV_SCOPE_GLOBAL &&
                     v->dtdv_scope != DIFV_SCOPE_THREAD &&
                     v->dtdv_scope != DIFV_SCOPE_LOCAL) {
                         err += efunc(i, "unrecognized variable scope %d\n",
                             v->dtdv_scope);
                         break;
                 }
 
                 if (v->dtdv_kind != DIFV_KIND_ARRAY &&
                     v->dtdv_kind != DIFV_KIND_SCALAR) {
                         err += efunc(i, "unrecognized variable type %d\n",
                             v->dtdv_kind);
                         break;
                 }
 
                 if ((id = v->dtdv_id) > DIF_VARIABLE_MAX) {
                         err += efunc(i, "%d exceeds variable id limit\n", id);
                         break;
                 }
 
                 if (id < DIF_VAR_OTHER_UBASE)
                         continue;
 
                 /*
                  * For user-defined variables, we need to check that this
                  * definition is identical to any previous definition that we
                  * encountered.
                  */
                 ndx = id - DIF_VAR_OTHER_UBASE;
 
                 switch (v->dtdv_scope) {
                 case DIFV_SCOPE_GLOBAL:
                         if (maxglobal == -1 || ndx > maxglobal)
                                 maxglobal = ndx;
 
                         if (ndx < vstate->dtvs_nglobals) {
                                 dtrace_statvar_t *svar;
 
                                 if ((svar = vstate->dtvs_globals[ndx]) != NULL)
                                         existing = &svar->dtsv_var;
                         }
 
                         break;
 
                 case DIFV_SCOPE_THREAD:
                         if (maxtlocal == -1 || ndx > maxtlocal)
                                 maxtlocal = ndx;
 
                         if (ndx < vstate->dtvs_ntlocals)
                                 existing = &vstate->dtvs_tlocals[ndx];
                         break;
 
                 case DIFV_SCOPE_LOCAL:
                         if (maxlocal == -1 || ndx > maxlocal)
                                 maxlocal = ndx;
 
                         if (ndx < vstate->dtvs_nlocals) {
                                 dtrace_statvar_t *svar;
 
                                 if ((svar = vstate->dtvs_locals[ndx]) != NULL)
                                         existing = &svar->dtsv_var;
                         }
 
                         break;
                 }
 
                 vt = &v->dtdv_type;
 
                 if (vt->dtdt_flags & DIF_TF_BYREF) {
                         if (vt->dtdt_size == 0) {
                                 err += efunc(i, "zero-sized variable\n");
                                 break;
                         }
 
                         if ((v->dtdv_scope == DIFV_SCOPE_GLOBAL ||
                             v->dtdv_scope == DIFV_SCOPE_LOCAL) &&
                             vt->dtdt_size > dtrace_statvar_maxsize) {
                                 err += efunc(i, "oversized by-ref static\n");
                                 break;
                         }
                 }
 
                 if (existing == NULL || existing->dtdv_id == 0)
                         continue;
 
                 ASSERT(existing->dtdv_id == v->dtdv_id);
                 ASSERT(existing->dtdv_scope == v->dtdv_scope);
 
                 if (existing->dtdv_kind != v->dtdv_kind)
                         err += efunc(i, "%d changed variable kind\n", id);
 
                 et = &existing->dtdv_type;
 
                 if (vt->dtdt_flags != et->dtdt_flags) {
                         err += efunc(i, "%d changed variable type flags\n", id);
                         break;
                 }
 
                 if (vt->dtdt_size != 0 && vt->dtdt_size != et->dtdt_size) {
                         err += efunc(i, "%d changed variable type size\n", id);
                         break;
                 }
         }
 
         for (pc = 0; pc < dp->dtdo_len && err == 0; pc++) {
                 dif_instr_t instr = dp->dtdo_buf[pc];
 
                 uint_t v = DIF_INSTR_VAR(instr);
                 uint_t op = DIF_INSTR_OP(instr);
 
                 switch (op) {
                 case DIF_OP_LDGS:
                 case DIF_OP_LDGAA:
                 case DIF_OP_STGS:
                 case DIF_OP_STGAA:
                         if (v > DIF_VAR_OTHER_UBASE + maxglobal)
                                 err += efunc(pc, "invalid variable %u\n", v);
                         break;
                 case DIF_OP_LDTS:
                 case DIF_OP_LDTAA:
                 case DIF_OP_STTS:
                 case DIF_OP_STTAA:
                         if (v > DIF_VAR_OTHER_UBASE + maxtlocal)
                                 err += efunc(pc, "invalid variable %u\n", v);
                         break;
                 case DIF_OP_LDLS:
                 case DIF_OP_STLS:
                         if (v > DIF_VAR_OTHER_UBASE + maxlocal)
                                 err += efunc(pc, "invalid variable %u\n", v);
                         break;
                 default:
                         break;
                 }
         }
 
         return (err);
 }
 
 /*
  * Validate a DTrace DIF object that it is to be used as a helper.  Helpers
  * are much more constrained than normal DIFOs.  Specifically, they may
  * not:
  *
  * 1. Make calls to subroutines other than copyin(), copyinstr() or
  *    miscellaneous string routines
  * 2. Access DTrace variables other than the args[] array, and the
  *    curthread, pid, ppid, tid, execname, zonename, uid and gid variables.
  * 3. Have thread-local variables.
  * 4. Have dynamic variables.
  */
 static int
 dtrace_difo_validate_helper(dtrace_difo_t *dp)
 {
         int (*efunc)(uint_t pc, const char *, ...) = dtrace_difo_err;
         int err = 0;
         uint_t pc;
 
         for (pc = 0; pc < dp->dtdo_len; pc++) {
                 dif_instr_t instr = dp->dtdo_buf[pc];
 
                 uint_t v = DIF_INSTR_VAR(instr);
                 uint_t subr = DIF_INSTR_SUBR(instr);
                 uint_t op = DIF_INSTR_OP(instr);
 
                 switch (op) {
                 case DIF_OP_OR:
                 case DIF_OP_XOR:
                 case DIF_OP_AND:
                 case DIF_OP_SLL:
                 case DIF_OP_SRL:
                 case DIF_OP_SRA:
                 case DIF_OP_SUB:
                 case DIF_OP_ADD:
                 case DIF_OP_MUL:
                 case DIF_OP_SDIV:
                 case DIF_OP_UDIV:
                 case DIF_OP_SREM:
                 case DIF_OP_UREM:
                 case DIF_OP_COPYS:
                 case DIF_OP_NOT:
                 case DIF_OP_MOV:
                 case DIF_OP_RLDSB:
                 case DIF_OP_RLDSH:
                 case DIF_OP_RLDSW:
                 case DIF_OP_RLDUB:
                 case DIF_OP_RLDUH:
                 case DIF_OP_RLDUW:
                 case DIF_OP_RLDX:
                 case DIF_OP_ULDSB:
                 case DIF_OP_ULDSH:
                 case DIF_OP_ULDSW:
                 case DIF_OP_ULDUB:
                 case DIF_OP_ULDUH:
                 case DIF_OP_ULDUW:
                 case DIF_OP_ULDX:
                 case DIF_OP_STB:
                 case DIF_OP_STH:
                 case DIF_OP_STW:
                 case DIF_OP_STX:
                 case DIF_OP_ALLOCS:
                 case DIF_OP_CMP:
                 case DIF_OP_SCMP:
                 case DIF_OP_TST:
                 case DIF_OP_BA:
                 case DIF_OP_BE:
                 case DIF_OP_BNE:
                 case DIF_OP_BG:
                 case DIF_OP_BGU:
                 case DIF_OP_BGE:
                 case DIF_OP_BGEU:
                 case DIF_OP_BL:
                 case DIF_OP_BLU:
                 case DIF_OP_BLE:
                 case DIF_OP_BLEU:
                 case DIF_OP_RET:
                 case DIF_OP_NOP:
                 case DIF_OP_POPTS:
                 case DIF_OP_FLUSHTS:
                 case DIF_OP_SETX:
                 case DIF_OP_SETS:
                 case DIF_OP_LDGA:
                 case DIF_OP_LDLS:
                 case DIF_OP_STGS:
                 case DIF_OP_STLS:
                 case DIF_OP_PUSHTR:
                 case DIF_OP_PUSHTV:
                         break;
 
                 case DIF_OP_LDGS:
                         if (v >= DIF_VAR_OTHER_UBASE)
                                 break;
 
                         if (v >= DIF_VAR_ARG0 && v <= DIF_VAR_ARG9)
                                 break;
 
                         if (v == DIF_VAR_CURTHREAD || v == DIF_VAR_PID ||
                             v == DIF_VAR_PPID || v == DIF_VAR_TID ||
                             v == DIF_VAR_EXECARGS ||
                             v == DIF_VAR_EXECNAME || v == DIF_VAR_ZONENAME ||
                             v == DIF_VAR_UID || v == DIF_VAR_GID)
                                 break;
 
                         err += efunc(pc, "illegal variable %u\n", v);
                         break;
 
                 case DIF_OP_LDTA:
                 case DIF_OP_LDTS:
                 case DIF_OP_LDGAA:
                 case DIF_OP_LDTAA:
                         err += efunc(pc, "illegal dynamic variable load\n");
                         break;
 
                 case DIF_OP_STTS:
                 case DIF_OP_STGAA:
                 case DIF_OP_STTAA:
                         err += efunc(pc, "illegal dynamic variable store\n");
                         break;
 
                 case DIF_OP_CALL:
                         if (subr == DIF_SUBR_ALLOCA ||
                             subr == DIF_SUBR_BCOPY ||
                             subr == DIF_SUBR_COPYIN ||
                             subr == DIF_SUBR_COPYINTO ||
                             subr == DIF_SUBR_COPYINSTR ||
                             subr == DIF_SUBR_INDEX ||
                             subr == DIF_SUBR_INET_NTOA ||
                             subr == DIF_SUBR_INET_NTOA6 ||
                             subr == DIF_SUBR_INET_NTOP ||
                             subr == DIF_SUBR_JSON ||
                             subr == DIF_SUBR_LLTOSTR ||
                             subr == DIF_SUBR_STRTOLL ||
                             subr == DIF_SUBR_RINDEX ||
                             subr == DIF_SUBR_STRCHR ||
                             subr == DIF_SUBR_STRJOIN ||
                             subr == DIF_SUBR_STRRCHR ||
                             subr == DIF_SUBR_STRSTR ||
                             subr == DIF_SUBR_HTONS ||
                             subr == DIF_SUBR_HTONL ||
                             subr == DIF_SUBR_HTONLL ||
                             subr == DIF_SUBR_NTOHS ||
                             subr == DIF_SUBR_NTOHL ||
                             subr == DIF_SUBR_NTOHLL ||
                             subr == DIF_SUBR_MEMREF)
                                 break;
 #ifdef __FreeBSD__
                         if (subr == DIF_SUBR_MEMSTR)
                                 break;
 #endif
 
                         err += efunc(pc, "invalid subr %u\n", subr);
                         break;
 
                 default:
                         err += efunc(pc, "invalid opcode %u\n",
                             DIF_INSTR_OP(instr));
                 }
         }
 
         return (err);
 }
 
 /*
  * Returns 1 if the expression in the DIF object can be cached on a per-thread
  * basis; 0 if not.
  */
 static int
 dtrace_difo_cacheable(dtrace_difo_t *dp)
 {
         int i;
 
         if (dp == NULL)
                 return (0);
 
         for (i = 0; i < dp->dtdo_varlen; i++) {
                 dtrace_difv_t *v = &dp->dtdo_vartab[i];
 
                 if (v->dtdv_scope != DIFV_SCOPE_GLOBAL)
                         continue;
 
                 switch (v->dtdv_id) {
                 case DIF_VAR_CURTHREAD:
                 case DIF_VAR_PID:
                 case DIF_VAR_TID:
                 case DIF_VAR_EXECARGS:
                 case DIF_VAR_EXECNAME:
                 case DIF_VAR_ZONENAME:
                         break;
 
                 default:
                         return (0);
                 }
         }
 
         /*
          * This DIF object may be cacheable.  Now we need to look for any
          * array loading instructions, any memory loading instructions, or
          * any stores to thread-local variables.
          */
         for (i = 0; i < dp->dtdo_len; i++) {
                 uint_t op = DIF_INSTR_OP(dp->dtdo_buf[i]);
 
                 if ((op >= DIF_OP_LDSB && op <= DIF_OP_LDX) ||
                     (op >= DIF_OP_ULDSB && op <= DIF_OP_ULDX) ||
                     (op >= DIF_OP_RLDSB && op <= DIF_OP_RLDX) ||
                     op == DIF_OP_LDGA || op == DIF_OP_STTS)
                         return (0);
         }
 
         return (1);
 }
 
 static void
 dtrace_difo_hold(dtrace_difo_t *dp)
 {
         int i;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         dp->dtdo_refcnt++;
         ASSERT(dp->dtdo_refcnt != 0);
 
         /*
          * We need to check this DIF object for references to the variable
          * DIF_VAR_VTIMESTAMP.
          */
         for (i = 0; i < dp->dtdo_varlen; i++) {
                 dtrace_difv_t *v = &dp->dtdo_vartab[i];
 
                 if (v->dtdv_id != DIF_VAR_VTIMESTAMP)
                         continue;
 
                 if (dtrace_vtime_references++ == 0)
                         dtrace_vtime_enable();
         }
 }
 
 /*
  * This routine calculates the dynamic variable chunksize for a given DIF
  * object.  The calculation is not fool-proof, and can probably be tricked by
  * malicious DIF -- but it works for all compiler-generated DIF.  Because this
  * calculation is likely imperfect, dtrace_dynvar() is able to gracefully fail
  * if a dynamic variable size exceeds the chunksize.
  */
 static void
 dtrace_difo_chunksize(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
 {
         uint64_t sval = 0;
         dtrace_key_t tupregs[DIF_DTR_NREGS + 2]; /* +2 for thread and id */
         const dif_instr_t *text = dp->dtdo_buf;
         uint_t pc, srd = 0;
         uint_t ttop = 0;
         size_t size, ksize;
         uint_t id, i;
 
         for (pc = 0; pc < dp->dtdo_len; pc++) {
                 dif_instr_t instr = text[pc];
                 uint_t op = DIF_INSTR_OP(instr);
                 uint_t rd = DIF_INSTR_RD(instr);
                 uint_t r1 = DIF_INSTR_R1(instr);
                 uint_t nkeys = 0;
                 uchar_t scope = 0;
 
                 dtrace_key_t *key = tupregs;
 
                 switch (op) {
                 case DIF_OP_SETX:
                         sval = dp->dtdo_inttab[DIF_INSTR_INTEGER(instr)];
                         srd = rd;
                         continue;
 
                 case DIF_OP_STTS:
                         key = &tupregs[DIF_DTR_NREGS];
                         key[0].dttk_size = 0;
                         key[1].dttk_size = 0;
                         nkeys = 2;
                         scope = DIFV_SCOPE_THREAD;
                         break;
 
                 case DIF_OP_STGAA:
                 case DIF_OP_STTAA:
                         nkeys = ttop;
 
                         if (DIF_INSTR_OP(instr) == DIF_OP_STTAA)
                                 key[nkeys++].dttk_size = 0;
 
                         key[nkeys++].dttk_size = 0;
 
                         if (op == DIF_OP_STTAA) {
                                 scope = DIFV_SCOPE_THREAD;
                         } else {
                                 scope = DIFV_SCOPE_GLOBAL;
                         }
 
                         break;
 
                 case DIF_OP_PUSHTR:
                         if (ttop == DIF_DTR_NREGS)
                                 return;
 
                         if ((srd == 0 || sval == 0) && r1 == DIF_TYPE_STRING) {
                                 /*
                                  * If the register for the size of the "pushtr"
                                  * is %r0 (or the value is 0) and the type is
                                  * a string, we'll use the system-wide default
                                  * string size.
                                  */
                                 tupregs[ttop++].dttk_size =
                                     dtrace_strsize_default;
                         } else {
                                 if (srd == 0)
                                         return;
 
                                 if (sval > LONG_MAX)
                                         return;
 
                                 tupregs[ttop++].dttk_size = sval;
                         }
 
                         break;
 
                 case DIF_OP_PUSHTV:
                         if (ttop == DIF_DTR_NREGS)
                                 return;
 
                         tupregs[ttop++].dttk_size = 0;
                         break;
 
                 case DIF_OP_FLUSHTS:
                         ttop = 0;
                         break;
 
                 case DIF_OP_POPTS:
                         if (ttop != 0)
                                 ttop--;
                         break;
                 }
 
                 sval = 0;
                 srd = 0;
 
                 if (nkeys == 0)
                         continue;
 
                 /*
                  * We have a dynamic variable allocation; calculate its size.
                  */
                 for (ksize = 0, i = 0; i < nkeys; i++)
                         ksize += P2ROUNDUP(key[i].dttk_size, sizeof (uint64_t));
 
                 size = sizeof (dtrace_dynvar_t);
                 size += sizeof (dtrace_key_t) * (nkeys - 1);
                 size += ksize;
 
                 /*
                  * Now we need to determine the size of the stored data.
                  */
                 id = DIF_INSTR_VAR(instr);
 
                 for (i = 0; i < dp->dtdo_varlen; i++) {
                         dtrace_difv_t *v = &dp->dtdo_vartab[i];
 
                         if (v->dtdv_id == id && v->dtdv_scope == scope) {
                                 size += v->dtdv_type.dtdt_size;
                                 break;
                         }
                 }
 
                 if (i == dp->dtdo_varlen)
                         return;
 
                 /*
                  * We have the size.  If this is larger than the chunk size
                  * for our dynamic variable state, reset the chunk size.
                  */
                 size = P2ROUNDUP(size, sizeof (uint64_t));
 
                 /*
                  * Before setting the chunk size, check that we're not going
                  * to set it to a negative value...
                  */
                 if (size > LONG_MAX)
                         return;
 
                 /*
                  * ...and make certain that we didn't badly overflow.
                  */
                 if (size < ksize || size < sizeof (dtrace_dynvar_t))
                         return;
 
                 if (size > vstate->dtvs_dynvars.dtds_chunksize)
                         vstate->dtvs_dynvars.dtds_chunksize = size;
         }
 }
 
 static void
 dtrace_difo_init(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
 {
         int i, oldsvars, osz, nsz, otlocals, ntlocals;
         uint_t id;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(dp->dtdo_buf != NULL && dp->dtdo_len != 0);
 
         for (i = 0; i < dp->dtdo_varlen; i++) {
                 dtrace_difv_t *v = &dp->dtdo_vartab[i];
                 dtrace_statvar_t *svar, ***svarp = NULL;
                 size_t dsize = 0;
                 uint8_t scope = v->dtdv_scope;
                 int *np = NULL;
 
                 if ((id = v->dtdv_id) < DIF_VAR_OTHER_UBASE)
                         continue;
 
                 id -= DIF_VAR_OTHER_UBASE;
 
                 switch (scope) {
                 case DIFV_SCOPE_THREAD:
                         while (id >= (otlocals = vstate->dtvs_ntlocals)) {
                                 dtrace_difv_t *tlocals;
 
                                 if ((ntlocals = (otlocals << 1)) == 0)
                                         ntlocals = 1;
 
                                 osz = otlocals * sizeof (dtrace_difv_t);
                                 nsz = ntlocals * sizeof (dtrace_difv_t);
 
                                 tlocals = kmem_zalloc(nsz, KM_SLEEP);
 
                                 if (osz != 0) {
                                         bcopy(vstate->dtvs_tlocals,
                                             tlocals, osz);
                                         kmem_free(vstate->dtvs_tlocals, osz);
                                 }
 
                                 vstate->dtvs_tlocals = tlocals;
                                 vstate->dtvs_ntlocals = ntlocals;
                         }
 
                         vstate->dtvs_tlocals[id] = *v;
                         continue;
 
                 case DIFV_SCOPE_LOCAL:
                         np = &vstate->dtvs_nlocals;
                         svarp = &vstate->dtvs_locals;
 
                         if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF)
                                 dsize = NCPU * (v->dtdv_type.dtdt_size +
                                     sizeof (uint64_t));
                         else
                                 dsize = NCPU * sizeof (uint64_t);
 
                         break;
 
                 case DIFV_SCOPE_GLOBAL:
                         np = &vstate->dtvs_nglobals;
                         svarp = &vstate->dtvs_globals;
 
                         if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF)
                                 dsize = v->dtdv_type.dtdt_size +
                                     sizeof (uint64_t);
 
                         break;
 
                 default:
                         ASSERT(0);
                 }
 
                 while (id >= (oldsvars = *np)) {
                         dtrace_statvar_t **statics;
                         int newsvars, oldsize, newsize;
 
                         if ((newsvars = (oldsvars << 1)) == 0)
                                 newsvars = 1;
 
                         oldsize = oldsvars * sizeof (dtrace_statvar_t *);
                         newsize = newsvars * sizeof (dtrace_statvar_t *);
 
                         statics = kmem_zalloc(newsize, KM_SLEEP);
 
                         if (oldsize != 0) {
                                 bcopy(*svarp, statics, oldsize);
                                 kmem_free(*svarp, oldsize);
                         }
 
                         *svarp = statics;
                         *np = newsvars;
                 }
 
                 if ((svar = (*svarp)[id]) == NULL) {
                         svar = kmem_zalloc(sizeof (dtrace_statvar_t), KM_SLEEP);
                         svar->dtsv_var = *v;
 
                         if ((svar->dtsv_size = dsize) != 0) {
                                 svar->dtsv_data = (uint64_t)(uintptr_t)
                                     kmem_zalloc(dsize, KM_SLEEP);
                         }
 
                         (*svarp)[id] = svar;
                 }
 
                 svar->dtsv_refcnt++;
         }
 
         dtrace_difo_chunksize(dp, vstate);
         dtrace_difo_hold(dp);
 }
 
 static dtrace_difo_t *
 dtrace_difo_duplicate(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
 {
         dtrace_difo_t *new;
         size_t sz;
 
         ASSERT(dp->dtdo_buf != NULL);
         ASSERT(dp->dtdo_refcnt != 0);
 
         new = kmem_zalloc(sizeof (dtrace_difo_t), KM_SLEEP);
 
         ASSERT(dp->dtdo_buf != NULL);
         sz = dp->dtdo_len * sizeof (dif_instr_t);
         new->dtdo_buf = kmem_alloc(sz, KM_SLEEP);
         bcopy(dp->dtdo_buf, new->dtdo_buf, sz);
         new->dtdo_len = dp->dtdo_len;
 
         if (dp->dtdo_strtab != NULL) {
                 ASSERT(dp->dtdo_strlen != 0);
                 new->dtdo_strtab = kmem_alloc(dp->dtdo_strlen, KM_SLEEP);
                 bcopy(dp->dtdo_strtab, new->dtdo_strtab, dp->dtdo_strlen);
                 new->dtdo_strlen = dp->dtdo_strlen;
         }
 
         if (dp->dtdo_inttab != NULL) {
                 ASSERT(dp->dtdo_intlen != 0);
                 sz = dp->dtdo_intlen * sizeof (uint64_t);
                 new->dtdo_inttab = kmem_alloc(sz, KM_SLEEP);
                 bcopy(dp->dtdo_inttab, new->dtdo_inttab, sz);
                 new->dtdo_intlen = dp->dtdo_intlen;
         }
 
         if (dp->dtdo_vartab != NULL) {
                 ASSERT(dp->dtdo_varlen != 0);
                 sz = dp->dtdo_varlen * sizeof (dtrace_difv_t);
                 new->dtdo_vartab = kmem_alloc(sz, KM_SLEEP);
                 bcopy(dp->dtdo_vartab, new->dtdo_vartab, sz);
                 new->dtdo_varlen = dp->dtdo_varlen;
         }
 
         dtrace_difo_init(new, vstate);
         return (new);
 }
 
 static void
 dtrace_difo_destroy(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
 {
         int i;
 
         ASSERT(dp->dtdo_refcnt == 0);
 
         for (i = 0; i < dp->dtdo_varlen; i++) {
                 dtrace_difv_t *v = &dp->dtdo_vartab[i];
                 dtrace_statvar_t *svar, **svarp = NULL;
                 uint_t id;
                 uint8_t scope = v->dtdv_scope;
                 int *np = NULL;
 
                 switch (scope) {
                 case DIFV_SCOPE_THREAD:
                         continue;
 
                 case DIFV_SCOPE_LOCAL:
                         np = &vstate->dtvs_nlocals;
                         svarp = vstate->dtvs_locals;
                         break;
 
                 case DIFV_SCOPE_GLOBAL:
                         np = &vstate->dtvs_nglobals;
                         svarp = vstate->dtvs_globals;
                         break;
 
                 default:
                         ASSERT(0);
                 }
 
                 if ((id = v->dtdv_id) < DIF_VAR_OTHER_UBASE)
                         continue;
 
                 id -= DIF_VAR_OTHER_UBASE;
                 ASSERT(id < *np);
 
                 svar = svarp[id];
                 ASSERT(svar != NULL);
                 ASSERT(svar->dtsv_refcnt > 0);
 
                 if (--svar->dtsv_refcnt > 0)
                         continue;
 
                 if (svar->dtsv_size != 0) {
                         ASSERT(svar->dtsv_data != 0);
                         kmem_free((void *)(uintptr_t)svar->dtsv_data,
                             svar->dtsv_size);
                 }
 
                 kmem_free(svar, sizeof (dtrace_statvar_t));
                 svarp[id] = NULL;
         }
 
         if (dp->dtdo_buf != NULL)
                 kmem_free(dp->dtdo_buf, dp->dtdo_len * sizeof (dif_instr_t));
         if (dp->dtdo_inttab != NULL)
                 kmem_free(dp->dtdo_inttab, dp->dtdo_intlen * sizeof (uint64_t));
         if (dp->dtdo_strtab != NULL)
                 kmem_free(dp->dtdo_strtab, dp->dtdo_strlen);
         if (dp->dtdo_vartab != NULL)
                 kmem_free(dp->dtdo_vartab, dp->dtdo_varlen * sizeof (dtrace_difv_t));
 
         kmem_free(dp, sizeof (dtrace_difo_t));
 }
 
 static void
 dtrace_difo_release(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
 {
         int i;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(dp->dtdo_refcnt != 0);
 
         for (i = 0; i < dp->dtdo_varlen; i++) {
                 dtrace_difv_t *v = &dp->dtdo_vartab[i];
 
                 if (v->dtdv_id != DIF_VAR_VTIMESTAMP)
                         continue;
 
                 ASSERT(dtrace_vtime_references > 0);
                 if (--dtrace_vtime_references == 0)
                         dtrace_vtime_disable();
         }
 
         if (--dp->dtdo_refcnt == 0)
                 dtrace_difo_destroy(dp, vstate);
 }
 
 /*
  * DTrace Format Functions
  */
 static uint16_t
 dtrace_format_add(dtrace_state_t *state, char *str)
 {
         char *fmt, **new;
         uint16_t ndx, len = strlen(str) + 1;
 
         fmt = kmem_zalloc(len, KM_SLEEP);
         bcopy(str, fmt, len);
 
         for (ndx = 0; ndx < state->dts_nformats; ndx++) {
                 if (state->dts_formats[ndx] == NULL) {
                         state->dts_formats[ndx] = fmt;
                         return (ndx + 1);
                 }
         }
 
         if (state->dts_nformats == USHRT_MAX) {
                 /*
                  * This is only likely if a denial-of-service attack is being
                  * attempted.  As such, it's okay to fail silently here.
                  */
                 kmem_free(fmt, len);
                 return (0);
         }
 
         /*
          * For simplicity, we always resize the formats array to be exactly the
          * number of formats.
          */
         ndx = state->dts_nformats++;
         new = kmem_alloc((ndx + 1) * sizeof (char *), KM_SLEEP);
 
         if (state->dts_formats != NULL) {
                 ASSERT(ndx != 0);
                 bcopy(state->dts_formats, new, ndx * sizeof (char *));
                 kmem_free(state->dts_formats, ndx * sizeof (char *));
         }
 
         state->dts_formats = new;
         state->dts_formats[ndx] = fmt;
 
         return (ndx + 1);
 }
 
 static void
 dtrace_format_remove(dtrace_state_t *state, uint16_t format)
 {
         char *fmt;
 
         ASSERT(state->dts_formats != NULL);
         ASSERT(format <= state->dts_nformats);
         ASSERT(state->dts_formats[format - 1] != NULL);
 
         fmt = state->dts_formats[format - 1];
         kmem_free(fmt, strlen(fmt) + 1);
         state->dts_formats[format - 1] = NULL;
 }
 
 static void
 dtrace_format_destroy(dtrace_state_t *state)
 {
         int i;
 
         if (state->dts_nformats == 0) {
                 ASSERT(state->dts_formats == NULL);
                 return;
         }
 
         ASSERT(state->dts_formats != NULL);
 
         for (i = 0; i < state->dts_nformats; i++) {
                 char *fmt = state->dts_formats[i];
 
                 if (fmt == NULL)
                         continue;
 
                 kmem_free(fmt, strlen(fmt) + 1);
         }
 
         kmem_free(state->dts_formats, state->dts_nformats * sizeof (char *));
         state->dts_nformats = 0;
         state->dts_formats = NULL;
 }
 
 /*
  * DTrace Predicate Functions
  */
 static dtrace_predicate_t *
 dtrace_predicate_create(dtrace_difo_t *dp)
 {
         dtrace_predicate_t *pred;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(dp->dtdo_refcnt != 0);
 
         pred = kmem_zalloc(sizeof (dtrace_predicate_t), KM_SLEEP);
         pred->dtp_difo = dp;
         pred->dtp_refcnt = 1;
 
         if (!dtrace_difo_cacheable(dp))
                 return (pred);
 
         if (dtrace_predcache_id == DTRACE_CACHEIDNONE) {
                 /*
                  * This is only theoretically possible -- we have had 2^32
                  * cacheable predicates on this machine.  We cannot allow any
                  * more predicates to become cacheable:  as unlikely as it is,
                  * there may be a thread caching a (now stale) predicate cache
                  * ID. (N.B.: the temptation is being successfully resisted to
                  * have this cmn_err() "Holy shit -- we executed this code!")
                  */
                 return (pred);
         }
 
         pred->dtp_cacheid = dtrace_predcache_id++;
 
         return (pred);
 }
 
 static void
 dtrace_predicate_hold(dtrace_predicate_t *pred)
 {
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(pred->dtp_difo != NULL && pred->dtp_difo->dtdo_refcnt != 0);
         ASSERT(pred->dtp_refcnt > 0);
 
         pred->dtp_refcnt++;
 }
 
 static void
 dtrace_predicate_release(dtrace_predicate_t *pred, dtrace_vstate_t *vstate)
 {
         dtrace_difo_t *dp = pred->dtp_difo;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(dp != NULL && dp->dtdo_refcnt != 0);
         ASSERT(pred->dtp_refcnt > 0);
 
         if (--pred->dtp_refcnt == 0) {
                 dtrace_difo_release(pred->dtp_difo, vstate);
                 kmem_free(pred, sizeof (dtrace_predicate_t));
         }
 }
 
 /*
  * DTrace Action Description Functions
  */
 static dtrace_actdesc_t *
 dtrace_actdesc_create(dtrace_actkind_t kind, uint32_t ntuple,
     uint64_t uarg, uint64_t arg)
 {
         dtrace_actdesc_t *act;
 
 #ifdef illumos
         ASSERT(!DTRACEACT_ISPRINTFLIKE(kind) || (arg != NULL &&
             arg >= KERNELBASE) || (arg == NULL && kind == DTRACEACT_PRINTA));
 #endif
 
         act = kmem_zalloc(sizeof (dtrace_actdesc_t), KM_SLEEP);
         act->dtad_kind = kind;
         act->dtad_ntuple = ntuple;
         act->dtad_uarg = uarg;
         act->dtad_arg = arg;
         act->dtad_refcnt = 1;
 
         return (act);
 }
 
 static void
 dtrace_actdesc_hold(dtrace_actdesc_t *act)
 {
         ASSERT(act->dtad_refcnt >= 1);
         act->dtad_refcnt++;
 }
 
 static void
 dtrace_actdesc_release(dtrace_actdesc_t *act, dtrace_vstate_t *vstate)
 {
         dtrace_actkind_t kind = act->dtad_kind;
         dtrace_difo_t *dp;
 
         ASSERT(act->dtad_refcnt >= 1);
 
         if (--act->dtad_refcnt != 0)
                 return;
 
         if ((dp = act->dtad_difo) != NULL)
                 dtrace_difo_release(dp, vstate);
 
         if (DTRACEACT_ISPRINTFLIKE(kind)) {
                 char *str = (char *)(uintptr_t)act->dtad_arg;
 
 #ifdef illumos
                 ASSERT((str != NULL && (uintptr_t)str >= KERNELBASE) ||
                     (str == NULL && act->dtad_kind == DTRACEACT_PRINTA));
 #endif
 
                 if (str != NULL)
                         kmem_free(str, strlen(str) + 1);
         }
 
         kmem_free(act, sizeof (dtrace_actdesc_t));
 }
 
 /*
  * DTrace ECB Functions
  */
 static dtrace_ecb_t *
 dtrace_ecb_add(dtrace_state_t *state, dtrace_probe_t *probe)
 {
         dtrace_ecb_t *ecb;
         dtrace_epid_t epid;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         ecb = kmem_zalloc(sizeof (dtrace_ecb_t), KM_SLEEP);
         ecb->dte_predicate = NULL;
         ecb->dte_probe = probe;
 
         /*
          * The default size is the size of the default action: recording
          * the header.
          */
         ecb->dte_size = ecb->dte_needed = sizeof (dtrace_rechdr_t);
         ecb->dte_alignment = sizeof (dtrace_epid_t);
 
         epid = state->dts_epid++;
 
         if (epid - 1 >= state->dts_necbs) {
                 dtrace_ecb_t **oecbs = state->dts_ecbs, **ecbs;
                 int necbs = state->dts_necbs << 1;
 
                 ASSERT(epid == state->dts_necbs + 1);
 
                 if (necbs == 0) {
                         ASSERT(oecbs == NULL);
                         necbs = 1;
                 }
 
                 ecbs = kmem_zalloc(necbs * sizeof (*ecbs), KM_SLEEP);
 
                 if (oecbs != NULL)
                         bcopy(oecbs, ecbs, state->dts_necbs * sizeof (*ecbs));
 
                 dtrace_membar_producer();
                 state->dts_ecbs = ecbs;
 
                 if (oecbs != NULL) {
                         /*
                          * If this state is active, we must dtrace_sync()
                          * before we can free the old dts_ecbs array:  we're
                          * coming in hot, and there may be active ring
                          * buffer processing (which indexes into the dts_ecbs
                          * array) on another CPU.
                          */
                         if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE)
                                 dtrace_sync();
 
                         kmem_free(oecbs, state->dts_necbs * sizeof (*ecbs));
                 }
 
                 dtrace_membar_producer();
                 state->dts_necbs = necbs;
         }
 
         ecb->dte_state = state;
 
         ASSERT(state->dts_ecbs[epid - 1] == NULL);
         dtrace_membar_producer();
         state->dts_ecbs[(ecb->dte_epid = epid) - 1] = ecb;
 
         return (ecb);
 }
 
 static void
 dtrace_ecb_enable(dtrace_ecb_t *ecb)
 {
         dtrace_probe_t *probe = ecb->dte_probe;
 
         ASSERT(MUTEX_HELD(&cpu_lock));
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(ecb->dte_next == NULL);
 
         if (probe == NULL) {
                 /*
                  * This is the NULL probe -- there's nothing to do.
                  */
                 return;
         }
 
         if (probe->dtpr_ecb == NULL) {
                 dtrace_provider_t *prov = probe->dtpr_provider;
 
                 /*
                  * We're the first ECB on this probe.
                  */
                 probe->dtpr_ecb = probe->dtpr_ecb_last = ecb;
 
                 if (ecb->dte_predicate != NULL)
                         probe->dtpr_predcache = ecb->dte_predicate->dtp_cacheid;
 
                 prov->dtpv_pops.dtps_enable(prov->dtpv_arg,
                     probe->dtpr_id, probe->dtpr_arg);
         } else {
                 /*
                  * This probe is already active.  Swing the last pointer to
                  * point to the new ECB, and issue a dtrace_sync() to assure
                  * that all CPUs have seen the change.
                  */
                 ASSERT(probe->dtpr_ecb_last != NULL);
                 probe->dtpr_ecb_last->dte_next = ecb;
                 probe->dtpr_ecb_last = ecb;
                 probe->dtpr_predcache = 0;
 
                 dtrace_sync();
         }
 }
 
 static int
 dtrace_ecb_resize(dtrace_ecb_t *ecb)
 {
         dtrace_action_t *act;
         uint32_t curneeded = UINT32_MAX;
         uint32_t aggbase = UINT32_MAX;
 
         /*
          * If we record anything, we always record the dtrace_rechdr_t.  (And
          * we always record it first.)
          */
         ecb->dte_size = sizeof (dtrace_rechdr_t);
         ecb->dte_alignment = sizeof (dtrace_epid_t);
 
         for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                 dtrace_recdesc_t *rec = &act->dta_rec;
                 ASSERT(rec->dtrd_size > 0 || rec->dtrd_alignment == 1);
 
                 ecb->dte_alignment = MAX(ecb->dte_alignment,
                     rec->dtrd_alignment);
 
                 if (DTRACEACT_ISAGG(act->dta_kind)) {
                         dtrace_aggregation_t *agg = (dtrace_aggregation_t *)act;
 
                         ASSERT(rec->dtrd_size != 0);
                         ASSERT(agg->dtag_first != NULL);
                         ASSERT(act->dta_prev->dta_intuple);
                         ASSERT(aggbase != UINT32_MAX);
                         ASSERT(curneeded != UINT32_MAX);
 
                         agg->dtag_base = aggbase;
 
                         curneeded = P2ROUNDUP(curneeded, rec->dtrd_alignment);
                         rec->dtrd_offset = curneeded;
                         if (curneeded + rec->dtrd_size < curneeded)
                                 return (EINVAL);
                         curneeded += rec->dtrd_size;
                         ecb->dte_needed = MAX(ecb->dte_needed, curneeded);
 
                         aggbase = UINT32_MAX;
                         curneeded = UINT32_MAX;
                 } else if (act->dta_intuple) {
                         if (curneeded == UINT32_MAX) {
                                 /*
                                  * This is the first record in a tuple.  Align
                                  * curneeded to be at offset 4 in an 8-byte
                                  * aligned block.
                                  */
                                 ASSERT(act->dta_prev == NULL ||
                                     !act->dta_prev->dta_intuple);
                                 ASSERT3U(aggbase, ==, UINT32_MAX);
                                 curneeded = P2PHASEUP(ecb->dte_size,
                                     sizeof (uint64_t), sizeof (dtrace_aggid_t));
 
                                 aggbase = curneeded - sizeof (dtrace_aggid_t);
                                 ASSERT(IS_P2ALIGNED(aggbase,
                                     sizeof (uint64_t)));
                         }
                         curneeded = P2ROUNDUP(curneeded, rec->dtrd_alignment);
                         rec->dtrd_offset = curneeded;
                         if (curneeded + rec->dtrd_size < curneeded)
                                 return (EINVAL);
                         curneeded += rec->dtrd_size;
                 } else {
                         /* tuples must be followed by an aggregation */
                         ASSERT(act->dta_prev == NULL ||
                             !act->dta_prev->dta_intuple);
 
                         ecb->dte_size = P2ROUNDUP(ecb->dte_size,
                             rec->dtrd_alignment);
                         rec->dtrd_offset = ecb->dte_size;
                         if (ecb->dte_size + rec->dtrd_size < ecb->dte_size)
                                 return (EINVAL);
                         ecb->dte_size += rec->dtrd_size;
                         ecb->dte_needed = MAX(ecb->dte_needed, ecb->dte_size);
                 }
         }
 
         if ((act = ecb->dte_action) != NULL &&
             !(act->dta_kind == DTRACEACT_SPECULATE && act->dta_next == NULL) &&
             ecb->dte_size == sizeof (dtrace_rechdr_t)) {
                 /*
                  * If the size is still sizeof (dtrace_rechdr_t), then all
                  * actions store no data; set the size to 0.
                  */
                 ecb->dte_size = 0;
         }
 
         ecb->dte_size = P2ROUNDUP(ecb->dte_size, sizeof (dtrace_epid_t));
         ecb->dte_needed = P2ROUNDUP(ecb->dte_needed, (sizeof (dtrace_epid_t)));
         ecb->dte_state->dts_needed = MAX(ecb->dte_state->dts_needed,
             ecb->dte_needed);
         return (0);
 }
 
 static dtrace_action_t *
 dtrace_ecb_aggregation_create(dtrace_ecb_t *ecb, dtrace_actdesc_t *desc)
 {
         dtrace_aggregation_t *agg;
         size_t size = sizeof (uint64_t);
         int ntuple = desc->dtad_ntuple;
         dtrace_action_t *act;
         dtrace_recdesc_t *frec;
         dtrace_aggid_t aggid;
         dtrace_state_t *state = ecb->dte_state;
 
         agg = kmem_zalloc(sizeof (dtrace_aggregation_t), KM_SLEEP);
         agg->dtag_ecb = ecb;
 
         ASSERT(DTRACEACT_ISAGG(desc->dtad_kind));
 
         switch (desc->dtad_kind) {
         case DTRACEAGG_MIN:
                 agg->dtag_initial = INT64_MAX;
                 agg->dtag_aggregate = dtrace_aggregate_min;
                 break;
 
         case DTRACEAGG_MAX:
                 agg->dtag_initial = INT64_MIN;
                 agg->dtag_aggregate = dtrace_aggregate_max;
                 break;
 
         case DTRACEAGG_COUNT:
                 agg->dtag_aggregate = dtrace_aggregate_count;
                 break;
 
         case DTRACEAGG_QUANTIZE:
                 agg->dtag_aggregate = dtrace_aggregate_quantize;
                 size = (((sizeof (uint64_t) * NBBY) - 1) * 2 + 1) *
                     sizeof (uint64_t);
                 break;
 
         case DTRACEAGG_LQUANTIZE: {
                 uint16_t step = DTRACE_LQUANTIZE_STEP(desc->dtad_arg);
                 uint16_t levels = DTRACE_LQUANTIZE_LEVELS(desc->dtad_arg);
 
                 agg->dtag_initial = desc->dtad_arg;
                 agg->dtag_aggregate = dtrace_aggregate_lquantize;
 
                 if (step == 0 || levels == 0)
                         goto err;
 
                 size = levels * sizeof (uint64_t) + 3 * sizeof (uint64_t);
                 break;
         }
 
         case DTRACEAGG_LLQUANTIZE: {
                 uint16_t factor = DTRACE_LLQUANTIZE_FACTOR(desc->dtad_arg);
                 uint16_t low = DTRACE_LLQUANTIZE_LOW(desc->dtad_arg);
                 uint16_t high = DTRACE_LLQUANTIZE_HIGH(desc->dtad_arg);
                 uint16_t nsteps = DTRACE_LLQUANTIZE_NSTEP(desc->dtad_arg);
                 int64_t v;
 
                 agg->dtag_initial = desc->dtad_arg;
                 agg->dtag_aggregate = dtrace_aggregate_llquantize;
 
                 if (factor < 2 || low >= high || nsteps < factor)
                         goto err;
 
                 /*
                  * Now check that the number of steps evenly divides a power
                  * of the factor.  (This assures both integer bucket size and
                  * linearity within each magnitude.)
                  */
                 for (v = factor; v < nsteps; v *= factor)
                         continue;
 
                 if ((v % nsteps) || (nsteps % factor))
                         goto err;
 
                 size = (dtrace_aggregate_llquantize_bucket(factor,
                     low, high, nsteps, INT64_MAX) + 2) * sizeof (uint64_t);
                 break;
         }
 
         case DTRACEAGG_AVG:
                 agg->dtag_aggregate = dtrace_aggregate_avg;
                 size = sizeof (uint64_t) * 2;
                 break;
 
         case DTRACEAGG_STDDEV:
                 agg->dtag_aggregate = dtrace_aggregate_stddev;
                 size = sizeof (uint64_t) * 4;
                 break;
 
         case DTRACEAGG_SUM:
                 agg->dtag_aggregate = dtrace_aggregate_sum;
                 break;
 
         default:
                 goto err;
         }
 
         agg->dtag_action.dta_rec.dtrd_size = size;
 
         if (ntuple == 0)
                 goto err;
 
         /*
          * We must make sure that we have enough actions for the n-tuple.
          */
         for (act = ecb->dte_action_last; act != NULL; act = act->dta_prev) {
                 if (DTRACEACT_ISAGG(act->dta_kind))
                         break;
 
                 if (--ntuple == 0) {
                         /*
                          * This is the action with which our n-tuple begins.
                          */
                         agg->dtag_first = act;
                         goto success;
                 }
         }
 
         /*
          * This n-tuple is short by ntuple elements.  Return failure.
          */
         ASSERT(ntuple != 0);
 err:
         kmem_free(agg, sizeof (dtrace_aggregation_t));
         return (NULL);
 
 success:
         /*
          * If the last action in the tuple has a size of zero, it's actually
          * an expression argument for the aggregating action.
          */
         ASSERT(ecb->dte_action_last != NULL);
         act = ecb->dte_action_last;
 
         if (act->dta_kind == DTRACEACT_DIFEXPR) {
                 ASSERT(act->dta_difo != NULL);
 
                 if (act->dta_difo->dtdo_rtype.dtdt_size == 0)
                         agg->dtag_hasarg = 1;
         }
 
         /*
          * We need to allocate an id for this aggregation.
          */
 #ifdef illumos
         aggid = (dtrace_aggid_t)(uintptr_t)vmem_alloc(state->dts_aggid_arena, 1,
             VM_BESTFIT | VM_SLEEP);
 #else
         aggid = alloc_unr(state->dts_aggid_arena);
 #endif
 
         if (aggid - 1 >= state->dts_naggregations) {
                 dtrace_aggregation_t **oaggs = state->dts_aggregations;
                 dtrace_aggregation_t **aggs;
                 int naggs = state->dts_naggregations << 1;
                 int onaggs = state->dts_naggregations;
 
                 ASSERT(aggid == state->dts_naggregations + 1);
 
                 if (naggs == 0) {
                         ASSERT(oaggs == NULL);
                         naggs = 1;
                 }
 
                 aggs = kmem_zalloc(naggs * sizeof (*aggs), KM_SLEEP);
 
                 if (oaggs != NULL) {
                         bcopy(oaggs, aggs, onaggs * sizeof (*aggs));
                         kmem_free(oaggs, onaggs * sizeof (*aggs));
                 }
 
                 state->dts_aggregations = aggs;
                 state->dts_naggregations = naggs;
         }
 
         ASSERT(state->dts_aggregations[aggid - 1] == NULL);
         state->dts_aggregations[(agg->dtag_id = aggid) - 1] = agg;
 
         frec = &agg->dtag_first->dta_rec;
         if (frec->dtrd_alignment < sizeof (dtrace_aggid_t))
                 frec->dtrd_alignment = sizeof (dtrace_aggid_t);
 
         for (act = agg->dtag_first; act != NULL; act = act->dta_next) {
                 ASSERT(!act->dta_intuple);
                 act->dta_intuple = 1;
         }
 
         return (&agg->dtag_action);
 }
 
 static void
 dtrace_ecb_aggregation_destroy(dtrace_ecb_t *ecb, dtrace_action_t *act)
 {
         dtrace_aggregation_t *agg = (dtrace_aggregation_t *)act;
         dtrace_state_t *state = ecb->dte_state;
         dtrace_aggid_t aggid = agg->dtag_id;
 
         ASSERT(DTRACEACT_ISAGG(act->dta_kind));
 #ifdef illumos
         vmem_free(state->dts_aggid_arena, (void *)(uintptr_t)aggid, 1);
 #else
         free_unr(state->dts_aggid_arena, aggid);
 #endif
 
         ASSERT(state->dts_aggregations[aggid - 1] == agg);
         state->dts_aggregations[aggid - 1] = NULL;
 
         kmem_free(agg, sizeof (dtrace_aggregation_t));
 }
 
 static int
 dtrace_ecb_action_add(dtrace_ecb_t *ecb, dtrace_actdesc_t *desc)
 {
         dtrace_action_t *action, *last;
         dtrace_difo_t *dp = desc->dtad_difo;
         uint32_t size = 0, align = sizeof (uint8_t), mask;
         uint16_t format = 0;
         dtrace_recdesc_t *rec;
         dtrace_state_t *state = ecb->dte_state;
         dtrace_optval_t *opt = state->dts_options, nframes = 0, strsize;
         uint64_t arg = desc->dtad_arg;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(ecb->dte_action == NULL || ecb->dte_action->dta_refcnt == 1);
 
         if (DTRACEACT_ISAGG(desc->dtad_kind)) {
                 /*
                  * If this is an aggregating action, there must be neither
                  * a speculate nor a commit on the action chain.
                  */
                 dtrace_action_t *act;
 
                 for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                         if (act->dta_kind == DTRACEACT_COMMIT)
                                 return (EINVAL);
 
                         if (act->dta_kind == DTRACEACT_SPECULATE)
                                 return (EINVAL);
                 }
 
                 action = dtrace_ecb_aggregation_create(ecb, desc);
 
                 if (action == NULL)
                         return (EINVAL);
         } else {
                 if (DTRACEACT_ISDESTRUCTIVE(desc->dtad_kind) ||
                     (desc->dtad_kind == DTRACEACT_DIFEXPR &&
                     dp != NULL && dp->dtdo_destructive)) {
                         state->dts_destructive = 1;
                 }
 
                 switch (desc->dtad_kind) {
                 case DTRACEACT_PRINTF:
                 case DTRACEACT_PRINTA:
                 case DTRACEACT_SYSTEM:
                 case DTRACEACT_FREOPEN:
                 case DTRACEACT_DIFEXPR:
                         /*
                          * We know that our arg is a string -- turn it into a
                          * format.
                          */
                         if (arg == 0) {
                                 ASSERT(desc->dtad_kind == DTRACEACT_PRINTA ||
                                     desc->dtad_kind == DTRACEACT_DIFEXPR);
                                 format = 0;
                         } else {
                                 ASSERT(arg != 0);
 #ifdef illumos
                                 ASSERT(arg > KERNELBASE);
 #endif
                                 format = dtrace_format_add(state,
                                     (char *)(uintptr_t)arg);
                         }
 
                         /*FALLTHROUGH*/
                 case DTRACEACT_LIBACT:
                 case DTRACEACT_TRACEMEM:
                 case DTRACEACT_TRACEMEM_DYNSIZE:
                         if (dp == NULL)
                                 return (EINVAL);
 
                         if ((size = dp->dtdo_rtype.dtdt_size) != 0)
                                 break;
 
                         if (dp->dtdo_rtype.dtdt_kind == DIF_TYPE_STRING) {
                                 if (!(dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                         return (EINVAL);
 
                                 size = opt[DTRACEOPT_STRSIZE];
                         }
 
                         break;
 
                 case DTRACEACT_STACK:
                         if ((nframes = arg) == 0) {
                                 nframes = opt[DTRACEOPT_STACKFRAMES];
                                 ASSERT(nframes > 0);
                                 arg = nframes;
                         }
 
                         size = nframes * sizeof (pc_t);
                         break;
 
                 case DTRACEACT_JSTACK:
                         if ((strsize = DTRACE_USTACK_STRSIZE(arg)) == 0)
                                 strsize = opt[DTRACEOPT_JSTACKSTRSIZE];
 
                         if ((nframes = DTRACE_USTACK_NFRAMES(arg)) == 0)
                                 nframes = opt[DTRACEOPT_JSTACKFRAMES];
 
                         arg = DTRACE_USTACK_ARG(nframes, strsize);
 
                         /*FALLTHROUGH*/
                 case DTRACEACT_USTACK:
                         if (desc->dtad_kind != DTRACEACT_JSTACK &&
                             (nframes = DTRACE_USTACK_NFRAMES(arg)) == 0) {
                                 strsize = DTRACE_USTACK_STRSIZE(arg);
                                 nframes = opt[DTRACEOPT_USTACKFRAMES];
                                 ASSERT(nframes > 0);
                                 arg = DTRACE_USTACK_ARG(nframes, strsize);
                         }
 
                         /*
                          * Save a slot for the pid.
                          */
                         size = (nframes + 1) * sizeof (uint64_t);
                         size += DTRACE_USTACK_STRSIZE(arg);
                         size = P2ROUNDUP(size, (uint32_t)(sizeof (uintptr_t)));
 
                         break;
 
                 case DTRACEACT_SYM:
                 case DTRACEACT_MOD:
                         if (dp == NULL || ((size = dp->dtdo_rtype.dtdt_size) !=
                             sizeof (uint64_t)) ||
                             (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                 return (EINVAL);
                         break;
 
                 case DTRACEACT_USYM:
                 case DTRACEACT_UMOD:
                 case DTRACEACT_UADDR:
                         if (dp == NULL ||
                             (dp->dtdo_rtype.dtdt_size != sizeof (uint64_t)) ||
                             (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                 return (EINVAL);
 
                         /*
                          * We have a slot for the pid, plus a slot for the
                          * argument.  To keep things simple (aligned with
                          * bitness-neutral sizing), we store each as a 64-bit
                          * quantity.
                          */
                         size = 2 * sizeof (uint64_t);
                         break;
 
                 case DTRACEACT_STOP:
                 case DTRACEACT_BREAKPOINT:
                 case DTRACEACT_PANIC:
                         break;
 
                 case DTRACEACT_CHILL:
                 case DTRACEACT_DISCARD:
                 case DTRACEACT_RAISE:
                         if (dp == NULL)
                                 return (EINVAL);
                         break;
 
                 case DTRACEACT_EXIT:
                         if (dp == NULL ||
                             (size = dp->dtdo_rtype.dtdt_size) != sizeof (int) ||
                             (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                 return (EINVAL);
                         break;
 
                 case DTRACEACT_SPECULATE:
                         if (ecb->dte_size > sizeof (dtrace_rechdr_t))
                                 return (EINVAL);
 
                         if (dp == NULL)
                                 return (EINVAL);
 
                         state->dts_speculates = 1;
                         break;
 
                 case DTRACEACT_PRINTM:
                         size = dp->dtdo_rtype.dtdt_size;
                         break;
 
                 case DTRACEACT_COMMIT: {
                         dtrace_action_t *act = ecb->dte_action;
 
                         for (; act != NULL; act = act->dta_next) {
                                 if (act->dta_kind == DTRACEACT_COMMIT)
                                         return (EINVAL);
                         }
 
                         if (dp == NULL)
                                 return (EINVAL);
                         break;
                 }
 
                 default:
                         return (EINVAL);
                 }
 
                 if (size != 0 || desc->dtad_kind == DTRACEACT_SPECULATE) {
                         /*
                          * If this is a data-storing action or a speculate,
                          * we must be sure that there isn't a commit on the
                          * action chain.
                          */
                         dtrace_action_t *act = ecb->dte_action;
 
                         for (; act != NULL; act = act->dta_next) {
                                 if (act->dta_kind == DTRACEACT_COMMIT)
                                         return (EINVAL);
                         }
                 }
 
                 action = kmem_zalloc(sizeof (dtrace_action_t), KM_SLEEP);
                 action->dta_rec.dtrd_size = size;
         }
 
         action->dta_refcnt = 1;
         rec = &action->dta_rec;
         size = rec->dtrd_size;
 
         for (mask = sizeof (uint64_t) - 1; size != 0 && mask > 0; mask >>= 1) {
                 if (!(size & mask)) {
                         align = mask + 1;
                         break;
                 }
         }
 
         action->dta_kind = desc->dtad_kind;
 
         if ((action->dta_difo = dp) != NULL)
                 dtrace_difo_hold(dp);
 
         rec->dtrd_action = action->dta_kind;
         rec->dtrd_arg = arg;
         rec->dtrd_uarg = desc->dtad_uarg;
         rec->dtrd_alignment = (uint16_t)align;
         rec->dtrd_format = format;
 
         if ((last = ecb->dte_action_last) != NULL) {
                 ASSERT(ecb->dte_action != NULL);
                 action->dta_prev = last;
                 last->dta_next = action;
         } else {
                 ASSERT(ecb->dte_action == NULL);
                 ecb->dte_action = action;
         }
 
         ecb->dte_action_last = action;
 
         return (0);
 }
 
 static void
 dtrace_ecb_action_remove(dtrace_ecb_t *ecb)
 {
         dtrace_action_t *act = ecb->dte_action, *next;
         dtrace_vstate_t *vstate = &ecb->dte_state->dts_vstate;
         dtrace_difo_t *dp;
         uint16_t format;
 
         if (act != NULL && act->dta_refcnt > 1) {
                 ASSERT(act->dta_next == NULL || act->dta_next->dta_refcnt == 1);
                 act->dta_refcnt--;
         } else {
                 for (; act != NULL; act = next) {
                         next = act->dta_next;
                         ASSERT(next != NULL || act == ecb->dte_action_last);
                         ASSERT(act->dta_refcnt == 1);
 
                         if ((format = act->dta_rec.dtrd_format) != 0)
                                 dtrace_format_remove(ecb->dte_state, format);
 
                         if ((dp = act->dta_difo) != NULL)
                                 dtrace_difo_release(dp, vstate);
 
                         if (DTRACEACT_ISAGG(act->dta_kind)) {
                                 dtrace_ecb_aggregation_destroy(ecb, act);
                         } else {
                                 kmem_free(act, sizeof (dtrace_action_t));
                         }
                 }
         }
 
         ecb->dte_action = NULL;
         ecb->dte_action_last = NULL;
         ecb->dte_size = 0;
 }
 
 static void
 dtrace_ecb_disable(dtrace_ecb_t *ecb)
 {
         /*
          * We disable the ECB by removing it from its probe.
          */
         dtrace_ecb_t *pecb, *prev = NULL;
         dtrace_probe_t *probe = ecb->dte_probe;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if (probe == NULL) {
                 /*
                  * This is the NULL probe; there is nothing to disable.
                  */
                 return;
         }
 
         for (pecb = probe->dtpr_ecb; pecb != NULL; pecb = pecb->dte_next) {
                 if (pecb == ecb)
                         break;
                 prev = pecb;
         }
 
         ASSERT(pecb != NULL);
 
         if (prev == NULL) {
                 probe->dtpr_ecb = ecb->dte_next;
         } else {
                 prev->dte_next = ecb->dte_next;
         }
 
         if (ecb == probe->dtpr_ecb_last) {
                 ASSERT(ecb->dte_next == NULL);
                 probe->dtpr_ecb_last = prev;
         }
 
         /*
          * The ECB has been disconnected from the probe; now sync to assure
          * that all CPUs have seen the change before returning.
          */
         dtrace_sync();
 
         if (probe->dtpr_ecb == NULL) {
                 /*
                  * That was the last ECB on the probe; clear the predicate
                  * cache ID for the probe, disable it and sync one more time
                  * to assure that we'll never hit it again.
                  */
                 dtrace_provider_t *prov = probe->dtpr_provider;
 
                 ASSERT(ecb->dte_next == NULL);
                 ASSERT(probe->dtpr_ecb_last == NULL);
                 probe->dtpr_predcache = DTRACE_CACHEIDNONE;
                 prov->dtpv_pops.dtps_disable(prov->dtpv_arg,
                     probe->dtpr_id, probe->dtpr_arg);
                 dtrace_sync();
         } else {
                 /*
                  * There is at least one ECB remaining on the probe.  If there
                  * is _exactly_ one, set the probe's predicate cache ID to be
                  * the predicate cache ID of the remaining ECB.
                  */
                 ASSERT(probe->dtpr_ecb_last != NULL);
                 ASSERT(probe->dtpr_predcache == DTRACE_CACHEIDNONE);
 
                 if (probe->dtpr_ecb == probe->dtpr_ecb_last) {
                         dtrace_predicate_t *p = probe->dtpr_ecb->dte_predicate;
 
                         ASSERT(probe->dtpr_ecb->dte_next == NULL);
 
                         if (p != NULL)
                                 probe->dtpr_predcache = p->dtp_cacheid;
                 }
 
                 ecb->dte_next = NULL;
         }
 }
 
 static void
 dtrace_ecb_destroy(dtrace_ecb_t *ecb)
 {
         dtrace_state_t *state = ecb->dte_state;
         dtrace_vstate_t *vstate = &state->dts_vstate;
         dtrace_predicate_t *pred;
         dtrace_epid_t epid = ecb->dte_epid;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(ecb->dte_next == NULL);
         ASSERT(ecb->dte_probe == NULL || ecb->dte_probe->dtpr_ecb != ecb);
 
         if ((pred = ecb->dte_predicate) != NULL)
                 dtrace_predicate_release(pred, vstate);
 
         dtrace_ecb_action_remove(ecb);
 
         ASSERT(state->dts_ecbs[epid - 1] == ecb);
         state->dts_ecbs[epid - 1] = NULL;
 
         kmem_free(ecb, sizeof (dtrace_ecb_t));
 }
 
 static dtrace_ecb_t *
 dtrace_ecb_create(dtrace_state_t *state, dtrace_probe_t *probe,
     dtrace_enabling_t *enab)
 {
         dtrace_ecb_t *ecb;
         dtrace_predicate_t *pred;
         dtrace_actdesc_t *act;
         dtrace_provider_t *prov;
         dtrace_ecbdesc_t *desc = enab->dten_current;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(state != NULL);
 
         ecb = dtrace_ecb_add(state, probe);
         ecb->dte_uarg = desc->dted_uarg;
 
         if ((pred = desc->dted_pred.dtpdd_predicate) != NULL) {
                 dtrace_predicate_hold(pred);
                 ecb->dte_predicate = pred;
         }
 
         if (probe != NULL) {
                 /*
                  * If the provider shows more leg than the consumer is old
                  * enough to see, we need to enable the appropriate implicit
                  * predicate bits to prevent the ecb from activating at
                  * revealing times.
                  *
                  * Providers specifying DTRACE_PRIV_USER at register time
                  * are stating that they need the /proc-style privilege
                  * model to be enforced, and this is what DTRACE_COND_OWNER
                  * and DTRACE_COND_ZONEOWNER will then do at probe time.
                  */
                 prov = probe->dtpr_provider;
                 if (!(state->dts_cred.dcr_visible & DTRACE_CRV_ALLPROC) &&
                     (prov->dtpv_priv.dtpp_flags & DTRACE_PRIV_USER))
                         ecb->dte_cond |= DTRACE_COND_OWNER;
 
                 if (!(state->dts_cred.dcr_visible & DTRACE_CRV_ALLZONE) &&
                     (prov->dtpv_priv.dtpp_flags & DTRACE_PRIV_USER))
                         ecb->dte_cond |= DTRACE_COND_ZONEOWNER;
 
                 /*
                  * If the provider shows us kernel innards and the user
                  * is lacking sufficient privilege, enable the
                  * DTRACE_COND_USERMODE implicit predicate.
                  */
                 if (!(state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL) &&
                     (prov->dtpv_priv.dtpp_flags & DTRACE_PRIV_KERNEL))
                         ecb->dte_cond |= DTRACE_COND_USERMODE;
         }
 
         if (dtrace_ecb_create_cache != NULL) {
                 /*
                  * If we have a cached ecb, we'll use its action list instead
                  * of creating our own (saving both time and space).
                  */
                 dtrace_ecb_t *cached = dtrace_ecb_create_cache;
                 dtrace_action_t *act = cached->dte_action;
 
                 if (act != NULL) {
                         ASSERT(act->dta_refcnt > 0);
                         act->dta_refcnt++;
                         ecb->dte_action = act;
                         ecb->dte_action_last = cached->dte_action_last;
                         ecb->dte_needed = cached->dte_needed;
                         ecb->dte_size = cached->dte_size;
                         ecb->dte_alignment = cached->dte_alignment;
                 }
 
                 return (ecb);
         }
 
         for (act = desc->dted_action; act != NULL; act = act->dtad_next) {
                 if ((enab->dten_error = dtrace_ecb_action_add(ecb, act)) != 0) {
                         dtrace_ecb_destroy(ecb);
                         return (NULL);
                 }
         }
 
         if ((enab->dten_error = dtrace_ecb_resize(ecb)) != 0) {
                 dtrace_ecb_destroy(ecb);
                 return (NULL);
         }
 
         return (dtrace_ecb_create_cache = ecb);
 }
 
 static int
 dtrace_ecb_create_enable(dtrace_probe_t *probe, void *arg)
 {
         dtrace_ecb_t *ecb;
         dtrace_enabling_t *enab = arg;
         dtrace_state_t *state = enab->dten_vstate->dtvs_state;
 
         ASSERT(state != NULL);
 
         if (probe != NULL && probe->dtpr_gen < enab->dten_probegen) {
                 /*
                  * This probe was created in a generation for which this
                  * enabling has previously created ECBs; we don't want to
                  * enable it again, so just kick out.
                  */
                 return (DTRACE_MATCH_NEXT);
         }
 
         if ((ecb = dtrace_ecb_create(state, probe, enab)) == NULL)
                 return (DTRACE_MATCH_DONE);
 
         dtrace_ecb_enable(ecb);
         return (DTRACE_MATCH_NEXT);
 }
 
 static dtrace_ecb_t *
 dtrace_epid2ecb(dtrace_state_t *state, dtrace_epid_t id)
 {
         dtrace_ecb_t *ecb;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if (id == 0 || id > state->dts_necbs)
                 return (NULL);
 
         ASSERT(state->dts_necbs > 0 && state->dts_ecbs != NULL);
         ASSERT((ecb = state->dts_ecbs[id - 1]) == NULL || ecb->dte_epid == id);
 
         return (state->dts_ecbs[id - 1]);
 }
 
 static dtrace_aggregation_t *
 dtrace_aggid2agg(dtrace_state_t *state, dtrace_aggid_t id)
 {
         dtrace_aggregation_t *agg;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if (id == 0 || id > state->dts_naggregations)
                 return (NULL);
 
         ASSERT(state->dts_naggregations > 0 && state->dts_aggregations != NULL);
         ASSERT((agg = state->dts_aggregations[id - 1]) == NULL ||
             agg->dtag_id == id);
 
         return (state->dts_aggregations[id - 1]);
 }
 
 /*
  * DTrace Buffer Functions
  *
  * The following functions manipulate DTrace buffers.  Most of these functions
  * are called in the context of establishing or processing consumer state;
  * exceptions are explicitly noted.
  */
 
 /*
  * Note:  called from cross call context.  This function switches the two
  * buffers on a given CPU.  The atomicity of this operation is assured by
  * disabling interrupts while the actual switch takes place; the disabling of
  * interrupts serializes the execution with any execution of dtrace_probe() on
  * the same CPU.
  */
 static void
 dtrace_buffer_switch(dtrace_buffer_t *buf)
 {
         caddr_t tomax = buf->dtb_tomax;
         caddr_t xamot = buf->dtb_xamot;
         dtrace_icookie_t cookie;
         hrtime_t now;
 
         ASSERT(!(buf->dtb_flags & DTRACEBUF_NOSWITCH));
         ASSERT(!(buf->dtb_flags & DTRACEBUF_RING));
 
         cookie = dtrace_interrupt_disable();
         now = dtrace_gethrtime();
         buf->dtb_tomax = xamot;
         buf->dtb_xamot = tomax;
         buf->dtb_xamot_drops = buf->dtb_drops;
         buf->dtb_xamot_offset = buf->dtb_offset;
         buf->dtb_xamot_errors = buf->dtb_errors;
         buf->dtb_xamot_flags = buf->dtb_flags;
         buf->dtb_offset = 0;
         buf->dtb_drops = 0;
         buf->dtb_errors = 0;
         buf->dtb_flags &= ~(DTRACEBUF_ERROR | DTRACEBUF_DROPPED);
         buf->dtb_interval = now - buf->dtb_switched;
         buf->dtb_switched = now;
         dtrace_interrupt_enable(cookie);
 }
 
 /*
  * Note:  called from cross call context.  This function activates a buffer
  * on a CPU.  As with dtrace_buffer_switch(), the atomicity of the operation
  * is guaranteed by the disabling of interrupts.
  */
 static void
 dtrace_buffer_activate(dtrace_state_t *state)
 {
         dtrace_buffer_t *buf;
         dtrace_icookie_t cookie = dtrace_interrupt_disable();
 
         buf = &state->dts_buffer[curcpu];
 
         if (buf->dtb_tomax != NULL) {
                 /*
                  * We might like to assert that the buffer is marked inactive,
                  * but this isn't necessarily true:  the buffer for the CPU
                  * that processes the BEGIN probe has its buffer activated
                  * manually.  In this case, we take the (harmless) action
                  * re-clearing the bit INACTIVE bit.
                  */
                 buf->dtb_flags &= ~DTRACEBUF_INACTIVE;
         }
 
         dtrace_interrupt_enable(cookie);
 }
 
 #ifdef __FreeBSD__
 /*
  * Activate the specified per-CPU buffer.  This is used instead of
  * dtrace_buffer_activate() when APs have not yet started, i.e. when
  * activating anonymous state.
  */
 static void
 dtrace_buffer_activate_cpu(dtrace_state_t *state, int cpu)
 {
 
         if (state->dts_buffer[cpu].dtb_tomax != NULL)
                 state->dts_buffer[cpu].dtb_flags &= ~DTRACEBUF_INACTIVE;
 }
 #endif
 
 static int
 dtrace_buffer_alloc(dtrace_buffer_t *bufs, size_t size, int flags,
     processorid_t cpu, int *factor)
 {
 #ifdef illumos
         cpu_t *cp;
 #endif
         dtrace_buffer_t *buf;
         int allocated = 0, desired = 0;
 
 #ifdef illumos
         ASSERT(MUTEX_HELD(&cpu_lock));
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         *factor = 1;
 
         if (size > dtrace_nonroot_maxsize &&
             !PRIV_POLICY_CHOICE(CRED(), PRIV_ALL, B_FALSE))
                 return (EFBIG);
 
         cp = cpu_list;
 
         do {
                 if (cpu != DTRACE_CPUALL && cpu != cp->cpu_id)
                         continue;
 
                 buf = &bufs[cp->cpu_id];
 
                 /*
                  * If there is already a buffer allocated for this CPU, it
                  * is only possible that this is a DR event.  In this case,
                  */
                 if (buf->dtb_tomax != NULL) {
                         ASSERT(buf->dtb_size == size);
                         continue;
                 }
 
                 ASSERT(buf->dtb_xamot == NULL);
 
                 if ((buf->dtb_tomax = kmem_zalloc(size,
                     KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                         goto err;
 
                 buf->dtb_size = size;
                 buf->dtb_flags = flags;
                 buf->dtb_offset = 0;
                 buf->dtb_drops = 0;
 
                 if (flags & DTRACEBUF_NOSWITCH)
                         continue;
 
                 if ((buf->dtb_xamot = kmem_zalloc(size,
                     KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                         goto err;
         } while ((cp = cp->cpu_next) != cpu_list);
 
         return (0);
 
 err:
         cp = cpu_list;
 
         do {
                 if (cpu != DTRACE_CPUALL && cpu != cp->cpu_id)
                         continue;
 
                 buf = &bufs[cp->cpu_id];
                 desired += 2;
 
                 if (buf->dtb_xamot != NULL) {
                         ASSERT(buf->dtb_tomax != NULL);
                         ASSERT(buf->dtb_size == size);
                         kmem_free(buf->dtb_xamot, size);
                         allocated++;
                 }
 
                 if (buf->dtb_tomax != NULL) {
                         ASSERT(buf->dtb_size == size);
                         kmem_free(buf->dtb_tomax, size);
                         allocated++;
                 }
 
                 buf->dtb_tomax = NULL;
                 buf->dtb_xamot = NULL;
                 buf->dtb_size = 0;
         } while ((cp = cp->cpu_next) != cpu_list);
 #else
         int i;
 
         *factor = 1;
 #if defined(__aarch64__) || defined(__amd64__) || defined(__arm__) || \
     defined(__mips__) || defined(__powerpc__) || defined(__riscv)
         /*
          * FreeBSD isn't good at limiting the amount of memory we
          * ask to malloc, so let's place a limit here before trying
          * to do something that might well end in tears at bedtime.
          */
         int bufsize_percpu_frac = dtrace_bufsize_max_frac * mp_ncpus;
         if (size > physmem * PAGE_SIZE / bufsize_percpu_frac)
                 return (ENOMEM);
 #endif
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         CPU_FOREACH(i) {
                 if (cpu != DTRACE_CPUALL && cpu != i)
                         continue;
 
                 buf = &bufs[i];
 
                 /*
                  * If there is already a buffer allocated for this CPU, it
                  * is only possible that this is a DR event.  In this case,
                  * the buffer size must match our specified size.
                  */
                 if (buf->dtb_tomax != NULL) {
                         ASSERT(buf->dtb_size == size);
                         continue;
                 }
 
                 ASSERT(buf->dtb_xamot == NULL);
 
                 if ((buf->dtb_tomax = kmem_zalloc(size,
                     KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                         goto err;
 
                 buf->dtb_size = size;
                 buf->dtb_flags = flags;
                 buf->dtb_offset = 0;
                 buf->dtb_drops = 0;
 
                 if (flags & DTRACEBUF_NOSWITCH)
                         continue;
 
                 if ((buf->dtb_xamot = kmem_zalloc(size,
                     KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                         goto err;
         }
 
         return (0);
 
 err:
         /*
          * Error allocating memory, so free the buffers that were
          * allocated before the failed allocation.
          */
         CPU_FOREACH(i) {
                 if (cpu != DTRACE_CPUALL && cpu != i)
                         continue;
 
                 buf = &bufs[i];
                 desired += 2;
 
                 if (buf->dtb_xamot != NULL) {
                         ASSERT(buf->dtb_tomax != NULL);
                         ASSERT(buf->dtb_size == size);
                         kmem_free(buf->dtb_xamot, size);
                         allocated++;
                 }
 
                 if (buf->dtb_tomax != NULL) {
                         ASSERT(buf->dtb_size == size);
                         kmem_free(buf->dtb_tomax, size);
                         allocated++;
                 }
 
                 buf->dtb_tomax = NULL;
                 buf->dtb_xamot = NULL;
                 buf->dtb_size = 0;
 
         }
 #endif
         *factor = desired / (allocated > 0 ? allocated : 1);
 
         return (ENOMEM);
 }
 
 /*
  * Note:  called from probe context.  This function just increments the drop
  * count on a buffer.  It has been made a function to allow for the
  * possibility of understanding the source of mysterious drop counts.  (A
  * problem for which one may be particularly disappointed that DTrace cannot
  * be used to understand DTrace.)
  */
 static void
 dtrace_buffer_drop(dtrace_buffer_t *buf)
 {
         buf->dtb_drops++;
 }
 
 /*
  * Note:  called from probe context.  This function is called to reserve space
  * in a buffer.  If mstate is non-NULL, sets the scratch base and size in the
  * mstate.  Returns the new offset in the buffer, or a negative value if an
  * error has occurred.
  */
 static intptr_t
 dtrace_buffer_reserve(dtrace_buffer_t *buf, size_t needed, size_t align,
     dtrace_state_t *state, dtrace_mstate_t *mstate)
 {
         intptr_t offs = buf->dtb_offset, soffs;
         intptr_t woffs;
         caddr_t tomax;
         size_t total;
 
         if (buf->dtb_flags & DTRACEBUF_INACTIVE)
                 return (-1);
 
         if ((tomax = buf->dtb_tomax) == NULL) {
                 dtrace_buffer_drop(buf);
                 return (-1);
         }
 
         if (!(buf->dtb_flags & (DTRACEBUF_RING | DTRACEBUF_FILL))) {
                 while (offs & (align - 1)) {
                         /*
                          * Assert that our alignment is off by a number which
                          * is itself sizeof (uint32_t) aligned.
                          */
                         ASSERT(!((align - (offs & (align - 1))) &
                             (sizeof (uint32_t) - 1)));
                         DTRACE_STORE(uint32_t, tomax, offs, DTRACE_EPIDNONE);
                         offs += sizeof (uint32_t);
                 }
 
                 if ((soffs = offs + needed) > buf->dtb_size) {
                         dtrace_buffer_drop(buf);
                         return (-1);
                 }
 
                 if (mstate == NULL)
                         return (offs);
 
                 mstate->dtms_scratch_base = (uintptr_t)tomax + soffs;
                 mstate->dtms_scratch_size = buf->dtb_size - soffs;
                 mstate->dtms_scratch_ptr = mstate->dtms_scratch_base;
 
                 return (offs);
         }
 
         if (buf->dtb_flags & DTRACEBUF_FILL) {
                 if (state->dts_activity != DTRACE_ACTIVITY_COOLDOWN &&
                     (buf->dtb_flags & DTRACEBUF_FULL))
                         return (-1);
                 goto out;
         }
 
         total = needed + (offs & (align - 1));
 
         /*
          * For a ring buffer, life is quite a bit more complicated.  Before
          * we can store any padding, we need to adjust our wrapping offset.
          * (If we've never before wrapped or we're not about to, no adjustment
          * is required.)
          */
         if ((buf->dtb_flags & DTRACEBUF_WRAPPED) ||
             offs + total > buf->dtb_size) {
                 woffs = buf->dtb_xamot_offset;
 
                 if (offs + total > buf->dtb_size) {
                         /*
                          * We can't fit in the end of the buffer.  First, a
                          * sanity check that we can fit in the buffer at all.
                          */
                         if (total > buf->dtb_size) {
                                 dtrace_buffer_drop(buf);
                                 return (-1);
                         }
 
                         /*
                          * We're going to be storing at the top of the buffer,
                          * so now we need to deal with the wrapped offset.  We
                          * only reset our wrapped offset to 0 if it is
                          * currently greater than the current offset.  If it
                          * is less than the current offset, it is because a
                          * previous allocation induced a wrap -- but the
                          * allocation didn't subsequently take the space due
                          * to an error or false predicate evaluation.  In this
                          * case, we'll just leave the wrapped offset alone: if
                          * the wrapped offset hasn't been advanced far enough
                          * for this allocation, it will be adjusted in the
                          * lower loop.
                          */
                         if (buf->dtb_flags & DTRACEBUF_WRAPPED) {
                                 if (woffs >= offs)
                                         woffs = 0;
                         } else {
                                 woffs = 0;
                         }
 
                         /*
                          * Now we know that we're going to be storing to the
                          * top of the buffer and that there is room for us
                          * there.  We need to clear the buffer from the current
                          * offset to the end (there may be old gunk there).
                          */
                         while (offs < buf->dtb_size)
                                 tomax[offs++] = 0;
 
                         /*
                          * We need to set our offset to zero.  And because we
                          * are wrapping, we need to set the bit indicating as
                          * much.  We can also adjust our needed space back
                          * down to the space required by the ECB -- we know
                          * that the top of the buffer is aligned.
                          */
                         offs = 0;
                         total = needed;
                         buf->dtb_flags |= DTRACEBUF_WRAPPED;
                 } else {
                         /*
                          * There is room for us in the buffer, so we simply
                          * need to check the wrapped offset.
                          */
                         if (woffs < offs) {
                                 /*
                                  * The wrapped offset is less than the offset.
                                  * This can happen if we allocated buffer space
                                  * that induced a wrap, but then we didn't
                                  * subsequently take the space due to an error
                                  * or false predicate evaluation.  This is
                                  * okay; we know that _this_ allocation isn't
                                  * going to induce a wrap.  We still can't
                                  * reset the wrapped offset to be zero,
                                  * however: the space may have been trashed in
                                  * the previous failed probe attempt.  But at
                                  * least the wrapped offset doesn't need to
                                  * be adjusted at all...
                                  */
                                 goto out;
                         }
                 }
 
                 while (offs + total > woffs) {
                         dtrace_epid_t epid = *(uint32_t *)(tomax + woffs);
                         size_t size;
 
                         if (epid == DTRACE_EPIDNONE) {
                                 size = sizeof (uint32_t);
                         } else {
                                 ASSERT3U(epid, <=, state->dts_necbs);
                                 ASSERT(state->dts_ecbs[epid - 1] != NULL);
 
                                 size = state->dts_ecbs[epid - 1]->dte_size;
                         }
 
                         ASSERT(woffs + size <= buf->dtb_size);
                         ASSERT(size != 0);
 
                         if (woffs + size == buf->dtb_size) {
                                 /*
                                  * We've reached the end of the buffer; we want
                                  * to set the wrapped offset to 0 and break
                                  * out.  However, if the offs is 0, then we're
                                  * in a strange edge-condition:  the amount of
                                  * space that we want to reserve plus the size
                                  * of the record that we're overwriting is
                                  * greater than the size of the buffer.  This
                                  * is problematic because if we reserve the
                                  * space but subsequently don't consume it (due
                                  * to a failed predicate or error) the wrapped
                                  * offset will be 0 -- yet the EPID at offset 0
                                  * will not be committed.  This situation is
                                  * relatively easy to deal with:  if we're in
                                  * this case, the buffer is indistinguishable
                                  * from one that hasn't wrapped; we need only
                                  * finish the job by clearing the wrapped bit,
                                  * explicitly setting the offset to be 0, and
                                  * zero'ing out the old data in the buffer.
                                  */
                                 if (offs == 0) {
                                         buf->dtb_flags &= ~DTRACEBUF_WRAPPED;
                                         buf->dtb_offset = 0;
                                         woffs = total;
 
                                         while (woffs < buf->dtb_size)
                                                 tomax[woffs++] = 0;
                                 }
 
                                 woffs = 0;
                                 break;
                         }
 
                         woffs += size;
                 }
 
                 /*
                  * We have a wrapped offset.  It may be that the wrapped offset
                  * has become zero -- that's okay.
                  */
                 buf->dtb_xamot_offset = woffs;
         }
 
 out:
         /*
          * Now we can plow the buffer with any necessary padding.
          */
         while (offs & (align - 1)) {
                 /*
                  * Assert that our alignment is off by a number which
                  * is itself sizeof (uint32_t) aligned.
                  */
                 ASSERT(!((align - (offs & (align - 1))) &
                     (sizeof (uint32_t) - 1)));
                 DTRACE_STORE(uint32_t, tomax, offs, DTRACE_EPIDNONE);
                 offs += sizeof (uint32_t);
         }
 
         if (buf->dtb_flags & DTRACEBUF_FILL) {
                 if (offs + needed > buf->dtb_size - state->dts_reserve) {
                         buf->dtb_flags |= DTRACEBUF_FULL;
                         return (-1);
                 }
         }
 
         if (mstate == NULL)
                 return (offs);
 
         /*
          * For ring buffers and fill buffers, the scratch space is always
          * the inactive buffer.
          */
         mstate->dtms_scratch_base = (uintptr_t)buf->dtb_xamot;
         mstate->dtms_scratch_size = buf->dtb_size;
         mstate->dtms_scratch_ptr = mstate->dtms_scratch_base;
 
         return (offs);
 }
 
 static void
 dtrace_buffer_polish(dtrace_buffer_t *buf)
 {
         ASSERT(buf->dtb_flags & DTRACEBUF_RING);
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if (!(buf->dtb_flags & DTRACEBUF_WRAPPED))
                 return;
 
         /*
          * We need to polish the ring buffer.  There are three cases:
          *
          * - The first (and presumably most common) is that there is no gap
          *   between the buffer offset and the wrapped offset.  In this case,
          *   there is nothing in the buffer that isn't valid data; we can
          *   mark the buffer as polished and return.
          *
          * - The second (less common than the first but still more common
          *   than the third) is that there is a gap between the buffer offset
          *   and the wrapped offset, and the wrapped offset is larger than the
          *   buffer offset.  This can happen because of an alignment issue, or
          *   can happen because of a call to dtrace_buffer_reserve() that
          *   didn't subsequently consume the buffer space.  In this case,
          *   we need to zero the data from the buffer offset to the wrapped
          *   offset.
          *
          * - The third (and least common) is that there is a gap between the
          *   buffer offset and the wrapped offset, but the wrapped offset is
          *   _less_ than the buffer offset.  This can only happen because a
          *   call to dtrace_buffer_reserve() induced a wrap, but the space
          *   was not subsequently consumed.  In this case, we need to zero the
          *   space from the offset to the end of the buffer _and_ from the
          *   top of the buffer to the wrapped offset.
          */
         if (buf->dtb_offset < buf->dtb_xamot_offset) {
                 bzero(buf->dtb_tomax + buf->dtb_offset,
                     buf->dtb_xamot_offset - buf->dtb_offset);
         }
 
         if (buf->dtb_offset > buf->dtb_xamot_offset) {
                 bzero(buf->dtb_tomax + buf->dtb_offset,
                     buf->dtb_size - buf->dtb_offset);
                 bzero(buf->dtb_tomax, buf->dtb_xamot_offset);
         }
 }
 
 /*
  * This routine determines if data generated at the specified time has likely
  * been entirely consumed at user-level.  This routine is called to determine
  * if an ECB on a defunct probe (but for an active enabling) can be safely
  * disabled and destroyed.
  */
 static int
 dtrace_buffer_consumed(dtrace_buffer_t *bufs, hrtime_t when)
 {
         int i;
 
         for (i = 0; i < NCPU; i++) {
                 dtrace_buffer_t *buf = &bufs[i];
 
                 if (buf->dtb_size == 0)
                         continue;
 
                 if (buf->dtb_flags & DTRACEBUF_RING)
                         return (0);
 
                 if (!buf->dtb_switched && buf->dtb_offset != 0)
                         return (0);
 
                 if (buf->dtb_switched - buf->dtb_interval < when)
                         return (0);
         }
 
         return (1);
 }
 
 static void
 dtrace_buffer_free(dtrace_buffer_t *bufs)
 {
         int i;
 
         for (i = 0; i < NCPU; i++) {
                 dtrace_buffer_t *buf = &bufs[i];
 
                 if (buf->dtb_tomax == NULL) {
                         ASSERT(buf->dtb_xamot == NULL);
                         ASSERT(buf->dtb_size == 0);
                         continue;
                 }
 
                 if (buf->dtb_xamot != NULL) {
                         ASSERT(!(buf->dtb_flags & DTRACEBUF_NOSWITCH));
                         kmem_free(buf->dtb_xamot, buf->dtb_size);
                 }
 
                 kmem_free(buf->dtb_tomax, buf->dtb_size);
                 buf->dtb_size = 0;
                 buf->dtb_tomax = NULL;
                 buf->dtb_xamot = NULL;
         }
 }
 
 /*
  * DTrace Enabling Functions
  */
 static dtrace_enabling_t *
 dtrace_enabling_create(dtrace_vstate_t *vstate)
 {
         dtrace_enabling_t *enab;
 
         enab = kmem_zalloc(sizeof (dtrace_enabling_t), KM_SLEEP);
         enab->dten_vstate = vstate;
 
         return (enab);
 }
 
 static void
 dtrace_enabling_add(dtrace_enabling_t *enab, dtrace_ecbdesc_t *ecb)
 {
         dtrace_ecbdesc_t **ndesc;
         size_t osize, nsize;
 
         /*
          * We can't add to enablings after we've enabled them, or after we've
          * retained them.
          */
         ASSERT(enab->dten_probegen == 0);
         ASSERT(enab->dten_next == NULL && enab->dten_prev == NULL);
 
         if (enab->dten_ndesc < enab->dten_maxdesc) {
                 enab->dten_desc[enab->dten_ndesc++] = ecb;
                 return;
         }
 
         osize = enab->dten_maxdesc * sizeof (dtrace_enabling_t *);
 
         if (enab->dten_maxdesc == 0) {
                 enab->dten_maxdesc = 1;
         } else {
                 enab->dten_maxdesc <<= 1;
         }
 
         ASSERT(enab->dten_ndesc < enab->dten_maxdesc);
 
         nsize = enab->dten_maxdesc * sizeof (dtrace_enabling_t *);
         ndesc = kmem_zalloc(nsize, KM_SLEEP);
         bcopy(enab->dten_desc, ndesc, osize);
         if (enab->dten_desc != NULL)
                 kmem_free(enab->dten_desc, osize);
 
         enab->dten_desc = ndesc;
         enab->dten_desc[enab->dten_ndesc++] = ecb;
 }
 
 static void
 dtrace_enabling_addlike(dtrace_enabling_t *enab, dtrace_ecbdesc_t *ecb,
     dtrace_probedesc_t *pd)
 {
         dtrace_ecbdesc_t *new;
         dtrace_predicate_t *pred;
         dtrace_actdesc_t *act;
 
         /*
          * We're going to create a new ECB description that matches the
          * specified ECB in every way, but has the specified probe description.
          */
         new = kmem_zalloc(sizeof (dtrace_ecbdesc_t), KM_SLEEP);
 
         if ((pred = ecb->dted_pred.dtpdd_predicate) != NULL)
                 dtrace_predicate_hold(pred);
 
         for (act = ecb->dted_action; act != NULL; act = act->dtad_next)
                 dtrace_actdesc_hold(act);
 
         new->dted_action = ecb->dted_action;
         new->dted_pred = ecb->dted_pred;
         new->dted_probe = *pd;
         new->dted_uarg = ecb->dted_uarg;
 
         dtrace_enabling_add(enab, new);
 }
 
 static void
 dtrace_enabling_dump(dtrace_enabling_t *enab)
 {
         int i;
 
         for (i = 0; i < enab->dten_ndesc; i++) {
                 dtrace_probedesc_t *desc = &enab->dten_desc[i]->dted_probe;
 
 #ifdef __FreeBSD__
                 printf("dtrace: enabling probe %d (%s:%s:%s:%s)\n", i,
                     desc->dtpd_provider, desc->dtpd_mod,
                     desc->dtpd_func, desc->dtpd_name);
 #else
                 cmn_err(CE_NOTE, "enabling probe %d (%s:%s:%s:%s)", i,
                     desc->dtpd_provider, desc->dtpd_mod,
                     desc->dtpd_func, desc->dtpd_name);
 #endif
         }
 }
 
 static void
 dtrace_enabling_destroy(dtrace_enabling_t *enab)
 {
         int i;
         dtrace_ecbdesc_t *ep;
         dtrace_vstate_t *vstate = enab->dten_vstate;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         for (i = 0; i < enab->dten_ndesc; i++) {
                 dtrace_actdesc_t *act, *next;
                 dtrace_predicate_t *pred;
 
                 ep = enab->dten_desc[i];
 
                 if ((pred = ep->dted_pred.dtpdd_predicate) != NULL)
                         dtrace_predicate_release(pred, vstate);
 
                 for (act = ep->dted_action; act != NULL; act = next) {
                         next = act->dtad_next;
                         dtrace_actdesc_release(act, vstate);
                 }
 
                 kmem_free(ep, sizeof (dtrace_ecbdesc_t));
         }
 
         if (enab->dten_desc != NULL)
                 kmem_free(enab->dten_desc,
                     enab->dten_maxdesc * sizeof (dtrace_enabling_t *));
 
         /*
          * If this was a retained enabling, decrement the dts_nretained count
          * and take it off of the dtrace_retained list.
          */
         if (enab->dten_prev != NULL || enab->dten_next != NULL ||
             dtrace_retained == enab) {
                 ASSERT(enab->dten_vstate->dtvs_state != NULL);
                 ASSERT(enab->dten_vstate->dtvs_state->dts_nretained > 0);
                 enab->dten_vstate->dtvs_state->dts_nretained--;
                 dtrace_retained_gen++;
         }
 
         if (enab->dten_prev == NULL) {
                 if (dtrace_retained == enab) {
                         dtrace_retained = enab->dten_next;
 
                         if (dtrace_retained != NULL)
                                 dtrace_retained->dten_prev = NULL;
                 }
         } else {
                 ASSERT(enab != dtrace_retained);
                 ASSERT(dtrace_retained != NULL);
                 enab->dten_prev->dten_next = enab->dten_next;
         }
 
         if (enab->dten_next != NULL) {
                 ASSERT(dtrace_retained != NULL);
                 enab->dten_next->dten_prev = enab->dten_prev;
         }
 
         kmem_free(enab, sizeof (dtrace_enabling_t));
 }
 
 static int
 dtrace_enabling_retain(dtrace_enabling_t *enab)
 {
         dtrace_state_t *state;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(enab->dten_next == NULL && enab->dten_prev == NULL);
         ASSERT(enab->dten_vstate != NULL);
 
         state = enab->dten_vstate->dtvs_state;
         ASSERT(state != NULL);
 
         /*
          * We only allow each state to retain dtrace_retain_max enablings.
          */
         if (state->dts_nretained >= dtrace_retain_max)
                 return (ENOSPC);
 
         state->dts_nretained++;
         dtrace_retained_gen++;
 
         if (dtrace_retained == NULL) {
                 dtrace_retained = enab;
                 return (0);
         }
 
         enab->dten_next = dtrace_retained;
         dtrace_retained->dten_prev = enab;
         dtrace_retained = enab;
 
         return (0);
 }
 
 static int
 dtrace_enabling_replicate(dtrace_state_t *state, dtrace_probedesc_t *match,
     dtrace_probedesc_t *create)
 {
         dtrace_enabling_t *new, *enab;
         int found = 0, err = ENOENT;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(strlen(match->dtpd_provider) < DTRACE_PROVNAMELEN);
         ASSERT(strlen(match->dtpd_mod) < DTRACE_MODNAMELEN);
         ASSERT(strlen(match->dtpd_func) < DTRACE_FUNCNAMELEN);
         ASSERT(strlen(match->dtpd_name) < DTRACE_NAMELEN);
 
         new = dtrace_enabling_create(&state->dts_vstate);
 
         /*
          * Iterate over all retained enablings, looking for enablings that
          * match the specified state.
          */
         for (enab = dtrace_retained; enab != NULL; enab = enab->dten_next) {
                 int i;
 
                 /*
                  * dtvs_state can only be NULL for helper enablings -- and
                  * helper enablings can't be retained.
                  */
                 ASSERT(enab->dten_vstate->dtvs_state != NULL);
 
                 if (enab->dten_vstate->dtvs_state != state)
                         continue;
 
                 /*
                  * Now iterate over each probe description; we're looking for
                  * an exact match to the specified probe description.
                  */
                 for (i = 0; i < enab->dten_ndesc; i++) {
                         dtrace_ecbdesc_t *ep = enab->dten_desc[i];
                         dtrace_probedesc_t *pd = &ep->dted_probe;
 
                         if (strcmp(pd->dtpd_provider, match->dtpd_provider))
                                 continue;
 
                         if (strcmp(pd->dtpd_mod, match->dtpd_mod))
                                 continue;
 
                         if (strcmp(pd->dtpd_func, match->dtpd_func))
                                 continue;
 
                         if (strcmp(pd->dtpd_name, match->dtpd_name))
                                 continue;
 
                         /*
                          * We have a winning probe!  Add it to our growing
                          * enabling.
                          */
                         found = 1;
                         dtrace_enabling_addlike(new, ep, create);
                 }
         }
 
         if (!found || (err = dtrace_enabling_retain(new)) != 0) {
                 dtrace_enabling_destroy(new);
                 return (err);
         }
 
         return (0);
 }
 
 static void
 dtrace_enabling_retract(dtrace_state_t *state)
 {
         dtrace_enabling_t *enab, *next;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         /*
          * Iterate over all retained enablings, destroy the enablings retained
          * for the specified state.
          */
         for (enab = dtrace_retained; enab != NULL; enab = next) {
                 next = enab->dten_next;
 
                 /*
                  * dtvs_state can only be NULL for helper enablings -- and
                  * helper enablings can't be retained.
                  */
                 ASSERT(enab->dten_vstate->dtvs_state != NULL);
 
                 if (enab->dten_vstate->dtvs_state == state) {
                         ASSERT(state->dts_nretained > 0);
                         dtrace_enabling_destroy(enab);
                 }
         }
 
         ASSERT(state->dts_nretained == 0);
 }
 
 static int
 dtrace_enabling_match(dtrace_enabling_t *enab, int *nmatched)
 {
         int i = 0;
         int matched = 0;
 
         ASSERT(MUTEX_HELD(&cpu_lock));
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         for (i = 0; i < enab->dten_ndesc; i++) {
                 dtrace_ecbdesc_t *ep = enab->dten_desc[i];
 
                 enab->dten_current = ep;
                 enab->dten_error = 0;
 
                 matched += dtrace_probe_enable(&ep->dted_probe, enab);
 
                 if (enab->dten_error != 0) {
                         /*
                          * If we get an error half-way through enabling the
                          * probes, we kick out -- perhaps with some number of
                          * them enabled.  Leaving enabled probes enabled may
                          * be slightly confusing for user-level, but we expect
                          * that no one will attempt to actually drive on in
                          * the face of such errors.  If this is an anonymous
                          * enabling (indicated with a NULL nmatched pointer),
                          * we cmn_err() a message.  We aren't expecting to
                          * get such an error -- such as it can exist at all,
                          * it would be a result of corrupted DOF in the driver
                          * properties.
                          */
                         if (nmatched == NULL) {
                                 cmn_err(CE_WARN, "dtrace_enabling_match() "
                                     "error on %p: %d", (void *)ep,
                                     enab->dten_error);
                         }
 
                         return (enab->dten_error);
                 }
         }
 
         enab->dten_probegen = dtrace_probegen;
         if (nmatched != NULL)
                 *nmatched = matched;
 
         return (0);
 }
 
 static void
 dtrace_enabling_matchall(void)
 {
         dtrace_enabling_t *enab;
 
         mutex_enter(&cpu_lock);
         mutex_enter(&dtrace_lock);
 
         /*
          * Iterate over all retained enablings to see if any probes match
          * against them.  We only perform this operation on enablings for which
          * we have sufficient permissions by virtue of being in the global zone
          * or in the same zone as the DTrace client.  Because we can be called
          * after dtrace_detach() has been called, we cannot assert that there
          * are retained enablings.  We can safely load from dtrace_retained,
          * however:  the taskq_destroy() at the end of dtrace_detach() will
          * block pending our completion.
          */
         for (enab = dtrace_retained; enab != NULL; enab = enab->dten_next) {
 #ifdef illumos
                 cred_t *cr = enab->dten_vstate->dtvs_state->dts_cred.dcr_cred;
 
                 if (INGLOBALZONE(curproc) ||
                     cr != NULL && getzoneid() == crgetzoneid(cr))
 #endif
                         (void) dtrace_enabling_match(enab, NULL);
         }
 
         mutex_exit(&dtrace_lock);
         mutex_exit(&cpu_lock);
 }
 
 /*
  * If an enabling is to be enabled without having matched probes (that is, if
  * dtrace_state_go() is to be called on the underlying dtrace_state_t), the
  * enabling must be _primed_ by creating an ECB for every ECB description.
  * This must be done to assure that we know the number of speculations, the
  * number of aggregations, the minimum buffer size needed, etc. before we
  * transition out of DTRACE_ACTIVITY_INACTIVE.  To do this without actually
  * enabling any probes, we create ECBs for every ECB decription, but with a
  * NULL probe -- which is exactly what this function does.
  */
 static void
 dtrace_enabling_prime(dtrace_state_t *state)
 {
         dtrace_enabling_t *enab;
         int i;
 
         for (enab = dtrace_retained; enab != NULL; enab = enab->dten_next) {
                 ASSERT(enab->dten_vstate->dtvs_state != NULL);
 
                 if (enab->dten_vstate->dtvs_state != state)
                         continue;
 
                 /*
                  * We don't want to prime an enabling more than once, lest
                  * we allow a malicious user to induce resource exhaustion.
                  * (The ECBs that result from priming an enabling aren't
                  * leaked -- but they also aren't deallocated until the
                  * consumer state is destroyed.)
                  */
                 if (enab->dten_primed)
                         continue;
 
                 for (i = 0; i < enab->dten_ndesc; i++) {
                         enab->dten_current = enab->dten_desc[i];
                         (void) dtrace_probe_enable(NULL, enab);
                 }
 
                 enab->dten_primed = 1;
         }
 }
 
 /*
  * Called to indicate that probes should be provided due to retained
  * enablings.  This is implemented in terms of dtrace_probe_provide(), but it
  * must take an initial lap through the enabling calling the dtps_provide()
  * entry point explicitly to allow for autocreated probes.
  */
 static void
 dtrace_enabling_provide(dtrace_provider_t *prv)
 {
         int i, all = 0;
         dtrace_probedesc_t desc;
         dtrace_genid_t gen;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(MUTEX_HELD(&dtrace_provider_lock));
 
         if (prv == NULL) {
                 all = 1;
                 prv = dtrace_provider;
         }
 
         do {
                 dtrace_enabling_t *enab;
                 void *parg = prv->dtpv_arg;
 
 retry:
                 gen = dtrace_retained_gen;
                 for (enab = dtrace_retained; enab != NULL;
                     enab = enab->dten_next) {
                         for (i = 0; i < enab->dten_ndesc; i++) {
                                 desc = enab->dten_desc[i]->dted_probe;
                                 mutex_exit(&dtrace_lock);
                                 prv->dtpv_pops.dtps_provide(parg, &desc);
                                 mutex_enter(&dtrace_lock);
                                 /*
                                  * Process the retained enablings again if
                                  * they have changed while we weren't holding
                                  * dtrace_lock.
                                  */
                                 if (gen != dtrace_retained_gen)
                                         goto retry;
                         }
                 }
         } while (all && (prv = prv->dtpv_next) != NULL);
 
         mutex_exit(&dtrace_lock);
         dtrace_probe_provide(NULL, all ? NULL : prv);
         mutex_enter(&dtrace_lock);
 }
 
 /*
  * Called to reap ECBs that are attached to probes from defunct providers.
  */
 static void
 dtrace_enabling_reap(void)
 {
         dtrace_provider_t *prov;
         dtrace_probe_t *probe;
         dtrace_ecb_t *ecb;
         hrtime_t when;
         int i;
 
         mutex_enter(&cpu_lock);
         mutex_enter(&dtrace_lock);
 
         for (i = 0; i < dtrace_nprobes; i++) {
                 if ((probe = dtrace_probes[i]) == NULL)
                         continue;
 
                 if (probe->dtpr_ecb == NULL)
                         continue;
 
                 prov = probe->dtpr_provider;
 
                 if ((when = prov->dtpv_defunct) == 0)
                         continue;
 
                 /*
                  * We have ECBs on a defunct provider:  we want to reap these
                  * ECBs to allow the provider to unregister.  The destruction
                  * of these ECBs must be done carefully:  if we destroy the ECB
                  * and the consumer later wishes to consume an EPID that
                  * corresponds to the destroyed ECB (and if the EPID metadata
                  * has not been previously consumed), the consumer will abort
                  * processing on the unknown EPID.  To reduce (but not, sadly,
                  * eliminate) the possibility of this, we will only destroy an
                  * ECB for a defunct provider if, for the state that
                  * corresponds to the ECB:
                  *
                  *  (a) There is no speculative tracing (which can effectively
                  *      cache an EPID for an arbitrary amount of time).
                  *
                  *  (b) The principal buffers have been switched twice since the
                  *      provider became defunct.
                  *
                  *  (c) The aggregation buffers are of zero size or have been
                  *      switched twice since the provider became defunct.
                  *
                  * We use dts_speculates to determine (a) and call a function
                  * (dtrace_buffer_consumed()) to determine (b) and (c).  Note
                  * that as soon as we've been unable to destroy one of the ECBs
                  * associated with the probe, we quit trying -- reaping is only
                  * fruitful in as much as we can destroy all ECBs associated
                  * with the defunct provider's probes.
                  */
                 while ((ecb = probe->dtpr_ecb) != NULL) {
                         dtrace_state_t *state = ecb->dte_state;
                         dtrace_buffer_t *buf = state->dts_buffer;
                         dtrace_buffer_t *aggbuf = state->dts_aggbuffer;
 
                         if (state->dts_speculates)
                                 break;
 
                         if (!dtrace_buffer_consumed(buf, when))
                                 break;
 
                         if (!dtrace_buffer_consumed(aggbuf, when))
                                 break;
 
                         dtrace_ecb_disable(ecb);
                         ASSERT(probe->dtpr_ecb != ecb);
                         dtrace_ecb_destroy(ecb);
                 }
         }
 
         mutex_exit(&dtrace_lock);
         mutex_exit(&cpu_lock);
 }
 
 /*
  * DTrace DOF Functions
  */
 /*ARGSUSED*/
 static void
 dtrace_dof_error(dof_hdr_t *dof, const char *str)
 {
         if (dtrace_err_verbose)
                 cmn_err(CE_WARN, "failed to process DOF: %s", str);
 
 #ifdef DTRACE_ERRDEBUG
         dtrace_errdebug(str);
 #endif
 }
 
 /*
  * Create DOF out of a currently enabled state.  Right now, we only create
  * DOF containing the run-time options -- but this could be expanded to create
  * complete DOF representing the enabled state.
  */
 static dof_hdr_t *
 dtrace_dof_create(dtrace_state_t *state)
 {
         dof_hdr_t *dof;
         dof_sec_t *sec;
         dof_optdesc_t *opt;
         int i, len = sizeof (dof_hdr_t) +
             roundup(sizeof (dof_sec_t), sizeof (uint64_t)) +
             sizeof (dof_optdesc_t) * DTRACEOPT_MAX;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         dof = kmem_zalloc(len, KM_SLEEP);
         dof->dofh_ident[DOF_ID_MAG0] = DOF_MAG_MAG0;
         dof->dofh_ident[DOF_ID_MAG1] = DOF_MAG_MAG1;
         dof->dofh_ident[DOF_ID_MAG2] = DOF_MAG_MAG2;
         dof->dofh_ident[DOF_ID_MAG3] = DOF_MAG_MAG3;
 
         dof->dofh_ident[DOF_ID_MODEL] = DOF_MODEL_NATIVE;
         dof->dofh_ident[DOF_ID_ENCODING] = DOF_ENCODE_NATIVE;
         dof->dofh_ident[DOF_ID_VERSION] = DOF_VERSION;
         dof->dofh_ident[DOF_ID_DIFVERS] = DIF_VERSION;
         dof->dofh_ident[DOF_ID_DIFIREG] = DIF_DIR_NREGS;
         dof->dofh_ident[DOF_ID_DIFTREG] = DIF_DTR_NREGS;
 
         dof->dofh_flags = 0;
         dof->dofh_hdrsize = sizeof (dof_hdr_t);
         dof->dofh_secsize = sizeof (dof_sec_t);
         dof->dofh_secnum = 1;   /* only DOF_SECT_OPTDESC */
         dof->dofh_secoff = sizeof (dof_hdr_t);
         dof->dofh_loadsz = len;
         dof->dofh_filesz = len;
         dof->dofh_pad = 0;
 
         /*
          * Fill in the option section header...
          */
         sec = (dof_sec_t *)((uintptr_t)dof + sizeof (dof_hdr_t));
         sec->dofs_type = DOF_SECT_OPTDESC;
         sec->dofs_align = sizeof (uint64_t);
         sec->dofs_flags = DOF_SECF_LOAD;
         sec->dofs_entsize = sizeof (dof_optdesc_t);
 
         opt = (dof_optdesc_t *)((uintptr_t)sec +
             roundup(sizeof (dof_sec_t), sizeof (uint64_t)));
 
         sec->dofs_offset = (uintptr_t)opt - (uintptr_t)dof;
         sec->dofs_size = sizeof (dof_optdesc_t) * DTRACEOPT_MAX;
 
         for (i = 0; i < DTRACEOPT_MAX; i++) {
                 opt[i].dofo_option = i;
                 opt[i].dofo_strtab = DOF_SECIDX_NONE;
                 opt[i].dofo_value = state->dts_options[i];
         }
 
         return (dof);
 }
 
 static dof_hdr_t *
 dtrace_dof_copyin(uintptr_t uarg, int *errp)
 {
         dof_hdr_t hdr, *dof;
 
         ASSERT(!MUTEX_HELD(&dtrace_lock));
 
         /*
          * First, we're going to copyin() the sizeof (dof_hdr_t).
          */
         if (copyin((void *)uarg, &hdr, sizeof (hdr)) != 0) {
                 dtrace_dof_error(NULL, "failed to copyin DOF header");
                 *errp = EFAULT;
                 return (NULL);
         }
 
         /*
          * Now we'll allocate the entire DOF and copy it in -- provided
          * that the length isn't outrageous.
          */
         if (hdr.dofh_loadsz >= dtrace_dof_maxsize) {
                 dtrace_dof_error(&hdr, "load size exceeds maximum");
                 *errp = E2BIG;
                 return (NULL);
         }
 
         if (hdr.dofh_loadsz < sizeof (hdr)) {
                 dtrace_dof_error(&hdr, "invalid load size");
                 *errp = EINVAL;
                 return (NULL);
         }
 
         dof = kmem_alloc(hdr.dofh_loadsz, KM_SLEEP);
 
         if (copyin((void *)uarg, dof, hdr.dofh_loadsz) != 0 ||
             dof->dofh_loadsz != hdr.dofh_loadsz) {
                 kmem_free(dof, hdr.dofh_loadsz);
                 *errp = EFAULT;
                 return (NULL);
         }
 
         return (dof);
 }
 
 #ifdef __FreeBSD__
 static dof_hdr_t *
 dtrace_dof_copyin_proc(struct proc *p, uintptr_t uarg, int *errp)
 {
         dof_hdr_t hdr, *dof;
         struct thread *td;
         size_t loadsz;
 
         ASSERT(!MUTEX_HELD(&dtrace_lock));
 
         td = curthread;
 
         /*
          * First, we're going to copyin() the sizeof (dof_hdr_t).
          */
         if (proc_readmem(td, p, uarg, &hdr, sizeof(hdr)) != sizeof(hdr)) {
                 dtrace_dof_error(NULL, "failed to copyin DOF header");
                 *errp = EFAULT;
                 return (NULL);
         }
 
         /*
          * Now we'll allocate the entire DOF and copy it in -- provided
          * that the length isn't outrageous.
          */
         if (hdr.dofh_loadsz >= dtrace_dof_maxsize) {
                 dtrace_dof_error(&hdr, "load size exceeds maximum");
                 *errp = E2BIG;
                 return (NULL);
         }
         loadsz = (size_t)hdr.dofh_loadsz;
 
         if (loadsz < sizeof (hdr)) {
                 dtrace_dof_error(&hdr, "invalid load size");
                 *errp = EINVAL;
                 return (NULL);
         }
 
         dof = kmem_alloc(loadsz, KM_SLEEP);
 
         if (proc_readmem(td, p, uarg, dof, loadsz) != loadsz ||
             dof->dofh_loadsz != loadsz) {
                 kmem_free(dof, hdr.dofh_loadsz);
                 *errp = EFAULT;
                 return (NULL);
         }
 
         return (dof);
 }
 
 static __inline uchar_t
 dtrace_dof_char(char c)
 {
 
         switch (c) {
         case '':
         case '1':
         case '2':
         case '3':
         case '4':
         case '5':
         case '6':
         case '7':
         case '8':
         case '9':
                 return (c - '');
         case 'A':
         case 'B':
         case 'C':
         case 'D':
         case 'E':
         case 'F':
                 return (c - 'A' + 10);
         case 'a':
         case 'b':
         case 'c':
         case 'd':
         case 'e':
         case 'f':
                 return (c - 'a' + 10);
         }
         /* Should not reach here. */
         return (UCHAR_MAX);
 }
 #endif /* __FreeBSD__ */
 
 static dof_hdr_t *
 dtrace_dof_property(const char *name)
 {
 #ifdef __FreeBSD__
         uint8_t *dofbuf;
         u_char *data, *eol;
         caddr_t doffile;
         size_t bytes, len, i;
         dof_hdr_t *dof;
         u_char c1, c2;
 
         dof = NULL;
 
         doffile = preload_search_by_type("dtrace_dof");
         if (doffile == NULL)
                 return (NULL);
 
         data = preload_fetch_addr(doffile);
         len = preload_fetch_size(doffile);
         for (;;) {
                 /* Look for the end of the line. All lines end in a newline. */
                 eol = memchr(data, '\n', len);
                 if (eol == NULL)
                         return (NULL);
 
                 if (strncmp(name, data, strlen(name)) == 0)
                         break;
 
                 eol++; /* skip past the newline */
                 len -= eol - data;
                 data = eol;
         }
 
         /* We've found the data corresponding to the specified key. */
 
         data += strlen(name) + 1; /* skip past the '=' */
         len = eol - data;
         if (len % 2 != 0) {
                 dtrace_dof_error(NULL, "invalid DOF encoding length");
                 goto doferr;
         }
         bytes = len / 2;
         if (bytes < sizeof(dof_hdr_t)) {
                 dtrace_dof_error(NULL, "truncated header");
                 goto doferr;
         }
 
         /*
          * Each byte is represented by the two ASCII characters in its hex
          * representation.
          */
         dofbuf = malloc(bytes, M_SOLARIS, M_WAITOK);
         for (i = 0; i < bytes; i++) {
                 c1 = dtrace_dof_char(data[i * 2]);
                 c2 = dtrace_dof_char(data[i * 2 + 1]);
                 if (c1 == UCHAR_MAX || c2 == UCHAR_MAX) {
                         dtrace_dof_error(NULL, "invalid hex char in DOF");
                         goto doferr;
                 }
                 dofbuf[i] = c1 * 16 + c2;
         }
 
         dof = (dof_hdr_t *)dofbuf;
         if (bytes < dof->dofh_loadsz) {
                 dtrace_dof_error(NULL, "truncated DOF");
                 goto doferr;
         }
 
         if (dof->dofh_loadsz >= dtrace_dof_maxsize) {
                 dtrace_dof_error(NULL, "oversized DOF");
                 goto doferr;
         }
 
         return (dof);
 
 doferr:
         free(dof, M_SOLARIS);
         return (NULL);
 #else /* __FreeBSD__ */
         uchar_t *buf;
         uint64_t loadsz;
         unsigned int len, i;
         dof_hdr_t *dof;
 
         /*
          * Unfortunately, array of values in .conf files are always (and
          * only) interpreted to be integer arrays.  We must read our DOF
          * as an integer array, and then squeeze it into a byte array.
          */
         if (ddi_prop_lookup_int_array(DDI_DEV_T_ANY, dtrace_devi, 0,
             (char *)name, (int **)&buf, &len) != DDI_PROP_SUCCESS)
                 return (NULL);
 
         for (i = 0; i < len; i++)
                 buf[i] = (uchar_t)(((int *)buf)[i]);
 
         if (len < sizeof (dof_hdr_t)) {
                 ddi_prop_free(buf);
                 dtrace_dof_error(NULL, "truncated header");
                 return (NULL);
         }
 
         if (len < (loadsz = ((dof_hdr_t *)buf)->dofh_loadsz)) {
                 ddi_prop_free(buf);
                 dtrace_dof_error(NULL, "truncated DOF");
                 return (NULL);
         }
 
         if (loadsz >= dtrace_dof_maxsize) {
                 ddi_prop_free(buf);
                 dtrace_dof_error(NULL, "oversized DOF");
                 return (NULL);
         }
 
         dof = kmem_alloc(loadsz, KM_SLEEP);
         bcopy(buf, dof, loadsz);
         ddi_prop_free(buf);
 
         return (dof);
 #endif /* !__FreeBSD__ */
 }
 
 static void
 dtrace_dof_destroy(dof_hdr_t *dof)
 {
         kmem_free(dof, dof->dofh_loadsz);
 }
 
 /*
  * Return the dof_sec_t pointer corresponding to a given section index.  If the
  * index is not valid, dtrace_dof_error() is called and NULL is returned.  If
  * a type other than DOF_SECT_NONE is specified, the header is checked against
  * this type and NULL is returned if the types do not match.
  */
 static dof_sec_t *
 dtrace_dof_sect(dof_hdr_t *dof, uint32_t type, dof_secidx_t i)
 {
         dof_sec_t *sec = (dof_sec_t *)(uintptr_t)
             ((uintptr_t)dof + dof->dofh_secoff + i * dof->dofh_secsize);
 
         if (i >= dof->dofh_secnum) {
                 dtrace_dof_error(dof, "referenced section index is invalid");
                 return (NULL);
         }
 
         if (!(sec->dofs_flags & DOF_SECF_LOAD)) {
                 dtrace_dof_error(dof, "referenced section is not loadable");
                 return (NULL);
         }
 
         if (type != DOF_SECT_NONE && type != sec->dofs_type) {
                 dtrace_dof_error(dof, "referenced section is the wrong type");
                 return (NULL);
         }
 
         return (sec);
 }
 
 static dtrace_probedesc_t *
 dtrace_dof_probedesc(dof_hdr_t *dof, dof_sec_t *sec, dtrace_probedesc_t *desc)
 {
         dof_probedesc_t *probe;
         dof_sec_t *strtab;
         uintptr_t daddr = (uintptr_t)dof;
         uintptr_t str;
         size_t size;
 
         if (sec->dofs_type != DOF_SECT_PROBEDESC) {
                 dtrace_dof_error(dof, "invalid probe section");
                 return (NULL);
         }
 
         if (sec->dofs_align != sizeof (dof_secidx_t)) {
                 dtrace_dof_error(dof, "bad alignment in probe description");
                 return (NULL);
         }
 
         if (sec->dofs_offset + sizeof (dof_probedesc_t) > dof->dofh_loadsz) {
                 dtrace_dof_error(dof, "truncated probe description");
                 return (NULL);
         }
 
         probe = (dof_probedesc_t *)(uintptr_t)(daddr + sec->dofs_offset);
         strtab = dtrace_dof_sect(dof, DOF_SECT_STRTAB, probe->dofp_strtab);
 
         if (strtab == NULL)
                 return (NULL);
 
         str = daddr + strtab->dofs_offset;
         size = strtab->dofs_size;
 
         if (probe->dofp_provider >= strtab->dofs_size) {
                 dtrace_dof_error(dof, "corrupt probe provider");
                 return (NULL);
         }
 
         (void) strncpy(desc->dtpd_provider,
             (char *)(str + probe->dofp_provider),
             MIN(DTRACE_PROVNAMELEN - 1, size - probe->dofp_provider));
 
         if (probe->dofp_mod >= strtab->dofs_size) {
                 dtrace_dof_error(dof, "corrupt probe module");
                 return (NULL);
         }
 
         (void) strncpy(desc->dtpd_mod, (char *)(str + probe->dofp_mod),
             MIN(DTRACE_MODNAMELEN - 1, size - probe->dofp_mod));
 
         if (probe->dofp_func >= strtab->dofs_size) {
                 dtrace_dof_error(dof, "corrupt probe function");
                 return (NULL);
         }
 
         (void) strncpy(desc->dtpd_func, (char *)(str + probe->dofp_func),
             MIN(DTRACE_FUNCNAMELEN - 1, size - probe->dofp_func));
 
         if (probe->dofp_name >= strtab->dofs_size) {
                 dtrace_dof_error(dof, "corrupt probe name");
                 return (NULL);
         }
 
         (void) strncpy(desc->dtpd_name, (char *)(str + probe->dofp_name),
             MIN(DTRACE_NAMELEN - 1, size - probe->dofp_name));
 
         return (desc);
 }
 
 static dtrace_difo_t *
 dtrace_dof_difo(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
     cred_t *cr)
 {
         dtrace_difo_t *dp;
         size_t ttl = 0;
         dof_difohdr_t *dofd;
         uintptr_t daddr = (uintptr_t)dof;
         size_t max = dtrace_difo_maxsize;
         int i, l, n;
 
         static const struct {
                 int section;
                 int bufoffs;
                 int lenoffs;
                 int entsize;
                 int align;
                 const char *msg;
         } difo[] = {
                 { DOF_SECT_DIF, offsetof(dtrace_difo_t, dtdo_buf),
                 offsetof(dtrace_difo_t, dtdo_len), sizeof (dif_instr_t),
                 sizeof (dif_instr_t), "multiple DIF sections" },
 
                 { DOF_SECT_INTTAB, offsetof(dtrace_difo_t, dtdo_inttab),
                 offsetof(dtrace_difo_t, dtdo_intlen), sizeof (uint64_t),
                 sizeof (uint64_t), "multiple integer tables" },
 
                 { DOF_SECT_STRTAB, offsetof(dtrace_difo_t, dtdo_strtab),
                 offsetof(dtrace_difo_t, dtdo_strlen), 0,
                 sizeof (char), "multiple string tables" },
 
                 { DOF_SECT_VARTAB, offsetof(dtrace_difo_t, dtdo_vartab),
                 offsetof(dtrace_difo_t, dtdo_varlen), sizeof (dtrace_difv_t),
                 sizeof (uint_t), "multiple variable tables" },
 
                 { DOF_SECT_NONE, 0, 0, 0, 0, NULL }
         };
 
         if (sec->dofs_type != DOF_SECT_DIFOHDR) {
                 dtrace_dof_error(dof, "invalid DIFO header section");
                 return (NULL);
         }
 
         if (sec->dofs_align != sizeof (dof_secidx_t)) {
                 dtrace_dof_error(dof, "bad alignment in DIFO header");
                 return (NULL);
         }
 
         if (sec->dofs_size < sizeof (dof_difohdr_t) ||
             sec->dofs_size % sizeof (dof_secidx_t)) {
                 dtrace_dof_error(dof, "bad size in DIFO header");
                 return (NULL);
         }
 
         dofd = (dof_difohdr_t *)(uintptr_t)(daddr + sec->dofs_offset);
         n = (sec->dofs_size - sizeof (*dofd)) / sizeof (dof_secidx_t) + 1;
 
         dp = kmem_zalloc(sizeof (dtrace_difo_t), KM_SLEEP);
         dp->dtdo_rtype = dofd->dofd_rtype;
 
         for (l = 0; l < n; l++) {
                 dof_sec_t *subsec;
                 void **bufp;
                 uint32_t *lenp;
 
                 if ((subsec = dtrace_dof_sect(dof, DOF_SECT_NONE,
                     dofd->dofd_links[l])) == NULL)
                         goto err; /* invalid section link */
 
                 if (ttl + subsec->dofs_size > max) {
                         dtrace_dof_error(dof, "exceeds maximum size");
                         goto err;
                 }
 
                 ttl += subsec->dofs_size;
 
                 for (i = 0; difo[i].section != DOF_SECT_NONE; i++) {
                         if (subsec->dofs_type != difo[i].section)
                                 continue;
 
                         if (!(subsec->dofs_flags & DOF_SECF_LOAD)) {
                                 dtrace_dof_error(dof, "section not loaded");
                                 goto err;
                         }
 
                         if (subsec->dofs_align != difo[i].align) {
                                 dtrace_dof_error(dof, "bad alignment");
                                 goto err;
                         }
 
                         bufp = (void **)((uintptr_t)dp + difo[i].bufoffs);
                         lenp = (uint32_t *)((uintptr_t)dp + difo[i].lenoffs);
 
                         if (*bufp != NULL) {
                                 dtrace_dof_error(dof, difo[i].msg);
                                 goto err;
                         }
 
                         if (difo[i].entsize != subsec->dofs_entsize) {
                                 dtrace_dof_error(dof, "entry size mismatch");
                                 goto err;
                         }
 
                         if (subsec->dofs_entsize != 0 &&
                             (subsec->dofs_size % subsec->dofs_entsize) != 0) {
                                 dtrace_dof_error(dof, "corrupt entry size");
                                 goto err;
                         }
 
                         *lenp = subsec->dofs_size;
                         *bufp = kmem_alloc(subsec->dofs_size, KM_SLEEP);
                         bcopy((char *)(uintptr_t)(daddr + subsec->dofs_offset),
                             *bufp, subsec->dofs_size);
 
                         if (subsec->dofs_entsize != 0)
                                 *lenp /= subsec->dofs_entsize;
 
                         break;
                 }
 
                 /*
                  * If we encounter a loadable DIFO sub-section that is not
                  * known to us, assume this is a broken program and fail.
                  */
                 if (difo[i].section == DOF_SECT_NONE &&
                     (subsec->dofs_flags & DOF_SECF_LOAD)) {
                         dtrace_dof_error(dof, "unrecognized DIFO subsection");
                         goto err;
                 }
         }
 
         if (dp->dtdo_buf == NULL) {
                 /*
                  * We can't have a DIF object without DIF text.
                  */
                 dtrace_dof_error(dof, "missing DIF text");
                 goto err;
         }
 
         /*
          * Before we validate the DIF object, run through the variable table
          * looking for the strings -- if any of their size are under, we'll set
          * their size to be the system-wide default string size.  Note that
          * this should _not_ happen if the "strsize" option has been set --
          * in this case, the compiler should have set the size to reflect the
          * setting of the option.
          */
         for (i = 0; i < dp->dtdo_varlen; i++) {
                 dtrace_difv_t *v = &dp->dtdo_vartab[i];
                 dtrace_diftype_t *t = &v->dtdv_type;
 
                 if (v->dtdv_id < DIF_VAR_OTHER_UBASE)
                         continue;
 
                 if (t->dtdt_kind == DIF_TYPE_STRING && t->dtdt_size == 0)
                         t->dtdt_size = dtrace_strsize_default;
         }
 
         if (dtrace_difo_validate(dp, vstate, DIF_DIR_NREGS, cr) != 0)
                 goto err;
 
         dtrace_difo_init(dp, vstate);
         return (dp);
 
 err:
         kmem_free(dp->dtdo_buf, dp->dtdo_len * sizeof (dif_instr_t));
         kmem_free(dp->dtdo_inttab, dp->dtdo_intlen * sizeof (uint64_t));
         kmem_free(dp->dtdo_strtab, dp->dtdo_strlen);
         kmem_free(dp->dtdo_vartab, dp->dtdo_varlen * sizeof (dtrace_difv_t));
 
         kmem_free(dp, sizeof (dtrace_difo_t));
         return (NULL);
 }
 
 static dtrace_predicate_t *
 dtrace_dof_predicate(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
     cred_t *cr)
 {
         dtrace_difo_t *dp;
 
         if ((dp = dtrace_dof_difo(dof, sec, vstate, cr)) == NULL)
                 return (NULL);
 
         return (dtrace_predicate_create(dp));
 }
 
 static dtrace_actdesc_t *
 dtrace_dof_actdesc(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
     cred_t *cr)
 {
         dtrace_actdesc_t *act, *first = NULL, *last = NULL, *next;
         dof_actdesc_t *desc;
         dof_sec_t *difosec;
         size_t offs;
         uintptr_t daddr = (uintptr_t)dof;
         uint64_t arg;
         dtrace_actkind_t kind;
 
         if (sec->dofs_type != DOF_SECT_ACTDESC) {
                 dtrace_dof_error(dof, "invalid action section");
                 return (NULL);
         }
 
         if (sec->dofs_offset + sizeof (dof_actdesc_t) > dof->dofh_loadsz) {
                 dtrace_dof_error(dof, "truncated action description");
                 return (NULL);
         }
 
         if (sec->dofs_align != sizeof (uint64_t)) {
                 dtrace_dof_error(dof, "bad alignment in action description");
                 return (NULL);
         }
 
         if (sec->dofs_size < sec->dofs_entsize) {
                 dtrace_dof_error(dof, "section entry size exceeds total size");
                 return (NULL);
         }
 
         if (sec->dofs_entsize != sizeof (dof_actdesc_t)) {
                 dtrace_dof_error(dof, "bad entry size in action description");
                 return (NULL);
         }
 
         if (sec->dofs_size / sec->dofs_entsize > dtrace_actions_max) {
                 dtrace_dof_error(dof, "actions exceed dtrace_actions_max");
                 return (NULL);
         }
 
         for (offs = 0; offs < sec->dofs_size; offs += sec->dofs_entsize) {
                 desc = (dof_actdesc_t *)(daddr +
                     (uintptr_t)sec->dofs_offset + offs);
                 kind = (dtrace_actkind_t)desc->dofa_kind;
 
                 if ((DTRACEACT_ISPRINTFLIKE(kind) &&
                     (kind != DTRACEACT_PRINTA ||
                     desc->dofa_strtab != DOF_SECIDX_NONE)) ||
                     (kind == DTRACEACT_DIFEXPR &&
                     desc->dofa_strtab != DOF_SECIDX_NONE)) {
                         dof_sec_t *strtab;
                         char *str, *fmt;
                         uint64_t i;
 
                         /*
                          * The argument to these actions is an index into the
                          * DOF string table.  For printf()-like actions, this
                          * is the format string.  For print(), this is the
                          * CTF type of the expression result.
                          */
                         if ((strtab = dtrace_dof_sect(dof,
                             DOF_SECT_STRTAB, desc->dofa_strtab)) == NULL)
                                 goto err;
 
                         str = (char *)((uintptr_t)dof +
                             (uintptr_t)strtab->dofs_offset);
 
                         for (i = desc->dofa_arg; i < strtab->dofs_size; i++) {
                                 if (str[i] == '\0')
                                         break;
                         }
 
                         if (i >= strtab->dofs_size) {
                                 dtrace_dof_error(dof, "bogus format string");
                                 goto err;
                         }
 
                         if (i == desc->dofa_arg) {
                                 dtrace_dof_error(dof, "empty format string");
                                 goto err;
                         }
 
                         i -= desc->dofa_arg;
                         fmt = kmem_alloc(i + 1, KM_SLEEP);
                         bcopy(&str[desc->dofa_arg], fmt, i + 1);
                         arg = (uint64_t)(uintptr_t)fmt;
                 } else {
                         if (kind == DTRACEACT_PRINTA) {
                                 ASSERT(desc->dofa_strtab == DOF_SECIDX_NONE);
                                 arg = 0;
                         } else {
                                 arg = desc->dofa_arg;
                         }
                 }
 
                 act = dtrace_actdesc_create(kind, desc->dofa_ntuple,
                     desc->dofa_uarg, arg);
 
                 if (last != NULL) {
                         last->dtad_next = act;
                 } else {
                         first = act;
                 }
 
                 last = act;
 
                 if (desc->dofa_difo == DOF_SECIDX_NONE)
                         continue;
 
                 if ((difosec = dtrace_dof_sect(dof,
                     DOF_SECT_DIFOHDR, desc->dofa_difo)) == NULL)
                         goto err;
 
                 act->dtad_difo = dtrace_dof_difo(dof, difosec, vstate, cr);
 
                 if (act->dtad_difo == NULL)
                         goto err;
         }
 
         ASSERT(first != NULL);
         return (first);
 
 err:
         for (act = first; act != NULL; act = next) {
                 next = act->dtad_next;
                 dtrace_actdesc_release(act, vstate);
         }
 
         return (NULL);
 }
 
 static dtrace_ecbdesc_t *
 dtrace_dof_ecbdesc(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
     cred_t *cr)
 {
         dtrace_ecbdesc_t *ep;
         dof_ecbdesc_t *ecb;
         dtrace_probedesc_t *desc;
         dtrace_predicate_t *pred = NULL;
 
         if (sec->dofs_size < sizeof (dof_ecbdesc_t)) {
                 dtrace_dof_error(dof, "truncated ECB description");
                 return (NULL);
         }
 
         if (sec->dofs_align != sizeof (uint64_t)) {
                 dtrace_dof_error(dof, "bad alignment in ECB description");
                 return (NULL);
         }
 
         ecb = (dof_ecbdesc_t *)((uintptr_t)dof + (uintptr_t)sec->dofs_offset);
         sec = dtrace_dof_sect(dof, DOF_SECT_PROBEDESC, ecb->dofe_probes);
 
         if (sec == NULL)
                 return (NULL);
 
         ep = kmem_zalloc(sizeof (dtrace_ecbdesc_t), KM_SLEEP);
         ep->dted_uarg = ecb->dofe_uarg;
         desc = &ep->dted_probe;
 
         if (dtrace_dof_probedesc(dof, sec, desc) == NULL)
                 goto err;
 
         if (ecb->dofe_pred != DOF_SECIDX_NONE) {
                 if ((sec = dtrace_dof_sect(dof,
                     DOF_SECT_DIFOHDR, ecb->dofe_pred)) == NULL)
                         goto err;
 
                 if ((pred = dtrace_dof_predicate(dof, sec, vstate, cr)) == NULL)
                         goto err;
 
                 ep->dted_pred.dtpdd_predicate = pred;
         }
 
         if (ecb->dofe_actions != DOF_SECIDX_NONE) {
                 if ((sec = dtrace_dof_sect(dof,
                     DOF_SECT_ACTDESC, ecb->dofe_actions)) == NULL)
                         goto err;
 
                 ep->dted_action = dtrace_dof_actdesc(dof, sec, vstate, cr);
 
                 if (ep->dted_action == NULL)
                         goto err;
         }
 
         return (ep);
 
 err:
         if (pred != NULL)
                 dtrace_predicate_release(pred, vstate);
         kmem_free(ep, sizeof (dtrace_ecbdesc_t));
         return (NULL);
 }
 
 /*
  * Apply the relocations from the specified 'sec' (a DOF_SECT_URELHDR) to the
  * specified DOF.  SETX relocations are computed using 'ubase', the base load
  * address of the object containing the DOF, and DOFREL relocations are relative
  * to the relocation offset within the DOF.
  */
 static int
 dtrace_dof_relocate(dof_hdr_t *dof, dof_sec_t *sec, uint64_t ubase,
     uint64_t udaddr)
 {
         uintptr_t daddr = (uintptr_t)dof;
         uintptr_t ts_end;
         dof_relohdr_t *dofr =
             (dof_relohdr_t *)(uintptr_t)(daddr + sec->dofs_offset);
         dof_sec_t *ss, *rs, *ts;
         dof_relodesc_t *r;
         uint_t i, n;
 
         if (sec->dofs_size < sizeof (dof_relohdr_t) ||
             sec->dofs_align != sizeof (dof_secidx_t)) {
                 dtrace_dof_error(dof, "invalid relocation header");
                 return (-1);
         }
 
         ss = dtrace_dof_sect(dof, DOF_SECT_STRTAB, dofr->dofr_strtab);
         rs = dtrace_dof_sect(dof, DOF_SECT_RELTAB, dofr->dofr_relsec);
         ts = dtrace_dof_sect(dof, DOF_SECT_NONE, dofr->dofr_tgtsec);
         ts_end = (uintptr_t)ts + sizeof (dof_sec_t);
 
         if (ss == NULL || rs == NULL || ts == NULL)
                 return (-1); /* dtrace_dof_error() has been called already */
 
         if (rs->dofs_entsize < sizeof (dof_relodesc_t) ||
             rs->dofs_align != sizeof (uint64_t)) {
                 dtrace_dof_error(dof, "invalid relocation section");
                 return (-1);
         }
 
         r = (dof_relodesc_t *)(uintptr_t)(daddr + rs->dofs_offset);
         n = rs->dofs_size / rs->dofs_entsize;
 
         for (i = 0; i < n; i++) {
                 uintptr_t taddr = daddr + ts->dofs_offset + r->dofr_offset;
 
                 switch (r->dofr_type) {
                 case DOF_RELO_NONE:
                         break;
                 case DOF_RELO_SETX:
                 case DOF_RELO_DOFREL:
                         if (r->dofr_offset >= ts->dofs_size || r->dofr_offset +
                             sizeof (uint64_t) > ts->dofs_size) {
                                 dtrace_dof_error(dof, "bad relocation offset");
                                 return (-1);
                         }
 
                         if (taddr >= (uintptr_t)ts && taddr < ts_end) {
                                 dtrace_dof_error(dof, "bad relocation offset");
                                 return (-1);
                         }
 
                         if (!IS_P2ALIGNED(taddr, sizeof (uint64_t))) {
                                 dtrace_dof_error(dof, "misaligned setx relo");
                                 return (-1);
                         }
 
                         if (r->dofr_type == DOF_RELO_SETX)
                                 *(uint64_t *)taddr += ubase;
                         else
                                 *(uint64_t *)taddr +=
                                     udaddr + ts->dofs_offset + r->dofr_offset;
                         break;
                 default:
                         dtrace_dof_error(dof, "invalid relocation type");
                         return (-1);
                 }
 
                 r = (dof_relodesc_t *)((uintptr_t)r + rs->dofs_entsize);
         }
 
         return (0);
 }
 
 /*
  * The dof_hdr_t passed to dtrace_dof_slurp() should be a partially validated
  * header:  it should be at the front of a memory region that is at least
  * sizeof (dof_hdr_t) in size -- and then at least dof_hdr.dofh_loadsz in
  * size.  It need not be validated in any other way.
  */
 static int
 dtrace_dof_slurp(dof_hdr_t *dof, dtrace_vstate_t *vstate, cred_t *cr,
     dtrace_enabling_t **enabp, uint64_t ubase, uint64_t udaddr, int noprobes)
 {
         uint64_t len = dof->dofh_loadsz, seclen;
         uintptr_t daddr = (uintptr_t)dof;
         dtrace_ecbdesc_t *ep;
         dtrace_enabling_t *enab;
         uint_t i;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(dof->dofh_loadsz >= sizeof (dof_hdr_t));
 
         /*
          * Check the DOF header identification bytes.  In addition to checking
          * valid settings, we also verify that unused bits/bytes are zeroed so
          * we can use them later without fear of regressing existing binaries.
          */
         if (bcmp(&dof->dofh_ident[DOF_ID_MAG0],
             DOF_MAG_STRING, DOF_MAG_STRLEN) != 0) {
                 dtrace_dof_error(dof, "DOF magic string mismatch");
                 return (-1);
         }
 
         if (dof->dofh_ident[DOF_ID_MODEL] != DOF_MODEL_ILP32 &&
             dof->dofh_ident[DOF_ID_MODEL] != DOF_MODEL_LP64) {
                 dtrace_dof_error(dof, "DOF has invalid data model");
                 return (-1);
         }
 
         if (dof->dofh_ident[DOF_ID_ENCODING] != DOF_ENCODE_NATIVE) {
                 dtrace_dof_error(dof, "DOF encoding mismatch");
                 return (-1);
         }
 
         if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1 &&
             dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_2) {
                 dtrace_dof_error(dof, "DOF version mismatch");
                 return (-1);
         }
 
         if (dof->dofh_ident[DOF_ID_DIFVERS] != DIF_VERSION_2) {
                 dtrace_dof_error(dof, "DOF uses unsupported instruction set");
                 return (-1);
         }
 
         if (dof->dofh_ident[DOF_ID_DIFIREG] > DIF_DIR_NREGS) {
                 dtrace_dof_error(dof, "DOF uses too many integer registers");
                 return (-1);
         }
 
         if (dof->dofh_ident[DOF_ID_DIFTREG] > DIF_DTR_NREGS) {
                 dtrace_dof_error(dof, "DOF uses too many tuple registers");
                 return (-1);
         }
 
         for (i = DOF_ID_PAD; i < DOF_ID_SIZE; i++) {
                 if (dof->dofh_ident[i] != 0) {
                         dtrace_dof_error(dof, "DOF has invalid ident byte set");
                         return (-1);
                 }
         }
 
         if (dof->dofh_flags & ~DOF_FL_VALID) {
                 dtrace_dof_error(dof, "DOF has invalid flag bits set");
                 return (-1);
         }
 
         if (dof->dofh_secsize == 0) {
                 dtrace_dof_error(dof, "zero section header size");
                 return (-1);
         }
 
         /*
          * Check that the section headers don't exceed the amount of DOF
          * data.  Note that we cast the section size and number of sections
          * to uint64_t's to prevent possible overflow in the multiplication.
          */
         seclen = (uint64_t)dof->dofh_secnum * (uint64_t)dof->dofh_secsize;
 
         if (dof->dofh_secoff > len || seclen > len ||
             dof->dofh_secoff + seclen > len) {
                 dtrace_dof_error(dof, "truncated section headers");
                 return (-1);
         }
 
         if (!IS_P2ALIGNED(dof->dofh_secoff, sizeof (uint64_t))) {
                 dtrace_dof_error(dof, "misaligned section headers");
                 return (-1);
         }
 
         if (!IS_P2ALIGNED(dof->dofh_secsize, sizeof (uint64_t))) {
                 dtrace_dof_error(dof, "misaligned section size");
                 return (-1);
         }
 
         /*
          * Take an initial pass through the section headers to be sure that
          * the headers don't have stray offsets.  If the 'noprobes' flag is
          * set, do not permit sections relating to providers, probes, or args.
          */
         for (i = 0; i < dof->dofh_secnum; i++) {
                 dof_sec_t *sec = (dof_sec_t *)(daddr +
                     (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);
 
                 if (noprobes) {
                         switch (sec->dofs_type) {
                         case DOF_SECT_PROVIDER:
                         case DOF_SECT_PROBES:
                         case DOF_SECT_PRARGS:
                         case DOF_SECT_PROFFS:
                                 dtrace_dof_error(dof, "illegal sections "
                                     "for enabling");
                                 return (-1);
                         }
                 }
 
                 if (DOF_SEC_ISLOADABLE(sec->dofs_type) &&
                     !(sec->dofs_flags & DOF_SECF_LOAD)) {
                         dtrace_dof_error(dof, "loadable section with load "
                             "flag unset");
                         return (-1);
                 }
 
                 if (!(sec->dofs_flags & DOF_SECF_LOAD))
                         continue; /* just ignore non-loadable sections */
 
                 if (!ISP2(sec->dofs_align)) {
                         dtrace_dof_error(dof, "bad section alignment");
                         return (-1);
                 }
 
                 if (sec->dofs_offset & (sec->dofs_align - 1)) {
                         dtrace_dof_error(dof, "misaligned section");
                         return (-1);
                 }
 
                 if (sec->dofs_offset > len || sec->dofs_size > len ||
                     sec->dofs_offset + sec->dofs_size > len) {
                         dtrace_dof_error(dof, "corrupt section header");
                         return (-1);
                 }
 
                 if (sec->dofs_type == DOF_SECT_STRTAB && *((char *)daddr +
                     sec->dofs_offset + sec->dofs_size - 1) != '\0') {
                         dtrace_dof_error(dof, "non-terminating string table");
                         return (-1);
                 }
         }
 
         /*
          * Take a second pass through the sections and locate and perform any
          * relocations that are present.  We do this after the first pass to
          * be sure that all sections have had their headers validated.
          */
         for (i = 0; i < dof->dofh_secnum; i++) {
                 dof_sec_t *sec = (dof_sec_t *)(daddr +
                     (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);
 
                 if (!(sec->dofs_flags & DOF_SECF_LOAD))
                         continue; /* skip sections that are not loadable */
 
                 switch (sec->dofs_type) {
                 case DOF_SECT_URELHDR:
                         if (dtrace_dof_relocate(dof, sec, ubase, udaddr) != 0)
                                 return (-1);
                         break;
                 }
         }
 
         if ((enab = *enabp) == NULL)
                 enab = *enabp = dtrace_enabling_create(vstate);
 
         for (i = 0; i < dof->dofh_secnum; i++) {
                 dof_sec_t *sec = (dof_sec_t *)(daddr +
                     (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);
 
                 if (sec->dofs_type != DOF_SECT_ECBDESC)
                         continue;
 
                 if ((ep = dtrace_dof_ecbdesc(dof, sec, vstate, cr)) == NULL) {
                         dtrace_enabling_destroy(enab);
                         *enabp = NULL;
                         return (-1);
                 }
 
                 dtrace_enabling_add(enab, ep);
         }
 
         return (0);
 }
 
 /*
  * Process DOF for any options.  This routine assumes that the DOF has been
  * at least processed by dtrace_dof_slurp().
  */
 static int
 dtrace_dof_options(dof_hdr_t *dof, dtrace_state_t *state)
 {
         int i, rval;
         uint32_t entsize;
         size_t offs;
         dof_optdesc_t *desc;
 
         for (i = 0; i < dof->dofh_secnum; i++) {
                 dof_sec_t *sec = (dof_sec_t *)((uintptr_t)dof +
                     (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);
 
                 if (sec->dofs_type != DOF_SECT_OPTDESC)
                         continue;
 
                 if (sec->dofs_align != sizeof (uint64_t)) {
                         dtrace_dof_error(dof, "bad alignment in "
                             "option description");
                         return (EINVAL);
                 }
 
                 if ((entsize = sec->dofs_entsize) == 0) {
                         dtrace_dof_error(dof, "zeroed option entry size");
                         return (EINVAL);
                 }
 
                 if (entsize < sizeof (dof_optdesc_t)) {
                         dtrace_dof_error(dof, "bad option entry size");
                         return (EINVAL);
                 }
 
                 for (offs = 0; offs < sec->dofs_size; offs += entsize) {
                         desc = (dof_optdesc_t *)((uintptr_t)dof +
                             (uintptr_t)sec->dofs_offset + offs);
 
                         if (desc->dofo_strtab != DOF_SECIDX_NONE) {
                                 dtrace_dof_error(dof, "non-zero option string");
                                 return (EINVAL);
                         }
 
                         if (desc->dofo_value == DTRACEOPT_UNSET) {
                                 dtrace_dof_error(dof, "unset option");
                                 return (EINVAL);
                         }
 
                         if ((rval = dtrace_state_option(state,
                             desc->dofo_option, desc->dofo_value)) != 0) {
                                 dtrace_dof_error(dof, "rejected option");
                                 return (rval);
                         }
                 }
         }
 
         return (0);
 }
 
 /*
  * DTrace Consumer State Functions
  */
 static int
 dtrace_dstate_init(dtrace_dstate_t *dstate, size_t size)
 {
         size_t hashsize, maxper, min, chunksize = dstate->dtds_chunksize;
         void *base;
         uintptr_t limit;
         dtrace_dynvar_t *dvar, *next, *start;
         int i;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(dstate->dtds_base == NULL && dstate->dtds_percpu == NULL);
 
         bzero(dstate, sizeof (dtrace_dstate_t));
 
         if ((dstate->dtds_chunksize = chunksize) == 0)
                 dstate->dtds_chunksize = DTRACE_DYNVAR_CHUNKSIZE;
 
         VERIFY(dstate->dtds_chunksize < LONG_MAX);
 
         if (size < (min = dstate->dtds_chunksize + sizeof (dtrace_dynhash_t)))
                 size = min;
 
         if ((base = kmem_zalloc(size, KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                 return (ENOMEM);
 
         dstate->dtds_size = size;
         dstate->dtds_base = base;
         dstate->dtds_percpu = kmem_cache_alloc(dtrace_state_cache, KM_SLEEP);
         bzero(dstate->dtds_percpu, NCPU * sizeof (dtrace_dstate_percpu_t));
 
         hashsize = size / (dstate->dtds_chunksize + sizeof (dtrace_dynhash_t));
 
         if (hashsize != 1 && (hashsize & 1))
                 hashsize--;
 
         dstate->dtds_hashsize = hashsize;
         dstate->dtds_hash = dstate->dtds_base;
 
         /*
          * Set all of our hash buckets to point to the single sink, and (if
          * it hasn't already been set), set the sink's hash value to be the
          * sink sentinel value.  The sink is needed for dynamic variable
          * lookups to know that they have iterated over an entire, valid hash
          * chain.
          */
         for (i = 0; i < hashsize; i++)
                 dstate->dtds_hash[i].dtdh_chain = &dtrace_dynhash_sink;
 
         if (dtrace_dynhash_sink.dtdv_hashval != DTRACE_DYNHASH_SINK)
                 dtrace_dynhash_sink.dtdv_hashval = DTRACE_DYNHASH_SINK;
 
         /*
          * Determine number of active CPUs.  Divide free list evenly among
          * active CPUs.
          */
         start = (dtrace_dynvar_t *)
             ((uintptr_t)base + hashsize * sizeof (dtrace_dynhash_t));
         limit = (uintptr_t)base + size;
 
         VERIFY((uintptr_t)start < limit);
         VERIFY((uintptr_t)start >= (uintptr_t)base);
 
         maxper = (limit - (uintptr_t)start) / NCPU;
         maxper = (maxper / dstate->dtds_chunksize) * dstate->dtds_chunksize;
 
 #ifndef illumos
         CPU_FOREACH(i) {
 #else
         for (i = 0; i < NCPU; i++) {
 #endif
                 dstate->dtds_percpu[i].dtdsc_free = dvar = start;
 
                 /*
                  * If we don't even have enough chunks to make it once through
                  * NCPUs, we're just going to allocate everything to the first
                  * CPU.  And if we're on the last CPU, we're going to allocate
                  * whatever is left over.  In either case, we set the limit to
                  * be the limit of the dynamic variable space.
                  */
                 if (maxper == 0 || i == NCPU - 1) {
                         limit = (uintptr_t)base + size;
                         start = NULL;
                 } else {
                         limit = (uintptr_t)start + maxper;
                         start = (dtrace_dynvar_t *)limit;
                 }
 
                 VERIFY(limit <= (uintptr_t)base + size);
 
                 for (;;) {
                         next = (dtrace_dynvar_t *)((uintptr_t)dvar +
                             dstate->dtds_chunksize);
 
                         if ((uintptr_t)next + dstate->dtds_chunksize >= limit)
                                 break;
 
                         VERIFY((uintptr_t)dvar >= (uintptr_t)base &&
                             (uintptr_t)dvar <= (uintptr_t)base + size);
                         dvar->dtdv_next = next;
                         dvar = next;
                 }
 
                 if (maxper == 0)
                         break;
         }
 
         return (0);
 }
 
 static void
 dtrace_dstate_fini(dtrace_dstate_t *dstate)
 {
         ASSERT(MUTEX_HELD(&cpu_lock));
 
         if (dstate->dtds_base == NULL)
                 return;
 
         kmem_free(dstate->dtds_base, dstate->dtds_size);
         kmem_cache_free(dtrace_state_cache, dstate->dtds_percpu);
 }
 
 static void
 dtrace_vstate_fini(dtrace_vstate_t *vstate)
 {
         /*
          * Logical XOR, where are you?
          */
         ASSERT((vstate->dtvs_nglobals == 0) ^ (vstate->dtvs_globals != NULL));
 
         if (vstate->dtvs_nglobals > 0) {
                 kmem_free(vstate->dtvs_globals, vstate->dtvs_nglobals *
                     sizeof (dtrace_statvar_t *));
         }
 
         if (vstate->dtvs_ntlocals > 0) {
                 kmem_free(vstate->dtvs_tlocals, vstate->dtvs_ntlocals *
                     sizeof (dtrace_difv_t));
         }
 
         ASSERT((vstate->dtvs_nlocals == 0) ^ (vstate->dtvs_locals != NULL));
 
         if (vstate->dtvs_nlocals > 0) {
                 kmem_free(vstate->dtvs_locals, vstate->dtvs_nlocals *
                     sizeof (dtrace_statvar_t *));
         }
 }
 
 #ifdef illumos
 static void
 dtrace_state_clean(dtrace_state_t *state)
 {
         if (state->dts_activity == DTRACE_ACTIVITY_INACTIVE)
                 return;
 
         dtrace_dynvar_clean(&state->dts_vstate.dtvs_dynvars);
         dtrace_speculation_clean(state);
 }
 
 static void
 dtrace_state_deadman(dtrace_state_t *state)
 {
         hrtime_t now;
 
         dtrace_sync();
 
         now = dtrace_gethrtime();
 
         if (state != dtrace_anon.dta_state &&
             now - state->dts_laststatus >= dtrace_deadman_user)
                 return;
 
         /*
          * We must be sure that dts_alive never appears to be less than the
          * value upon entry to dtrace_state_deadman(), and because we lack a
          * dtrace_cas64(), we cannot store to it atomically.  We thus instead
          * store INT64_MAX to it, followed by a memory barrier, followed by
          * the new value.  This assures that dts_alive never appears to be
          * less than its true value, regardless of the order in which the
          * stores to the underlying storage are issued.
          */
         state->dts_alive = INT64_MAX;
         dtrace_membar_producer();
         state->dts_alive = now;
 }
 #else   /* !illumos */
 static void
 dtrace_state_clean(void *arg)
 {
         dtrace_state_t *state = arg;
         dtrace_optval_t *opt = state->dts_options;
 
         if (state->dts_activity == DTRACE_ACTIVITY_INACTIVE)
                 return;
 
         dtrace_dynvar_clean(&state->dts_vstate.dtvs_dynvars);
         dtrace_speculation_clean(state);
 
         callout_reset(&state->dts_cleaner, hz * opt[DTRACEOPT_CLEANRATE] / NANOSEC,
             dtrace_state_clean, state);
 }
 
 static void
 dtrace_state_deadman(void *arg)
 {
         dtrace_state_t *state = arg;
         hrtime_t now;
 
         dtrace_sync();
 
         dtrace_debug_output();
 
         now = dtrace_gethrtime();
 
         if (state != dtrace_anon.dta_state &&
             now - state->dts_laststatus >= dtrace_deadman_user)
                 return;
 
         /*
          * We must be sure that dts_alive never appears to be less than the
          * value upon entry to dtrace_state_deadman(), and because we lack a
          * dtrace_cas64(), we cannot store to it atomically.  We thus instead
          * store INT64_MAX to it, followed by a memory barrier, followed by
          * the new value.  This assures that dts_alive never appears to be
          * less than its true value, regardless of the order in which the
          * stores to the underlying storage are issued.
          */
         state->dts_alive = INT64_MAX;
         dtrace_membar_producer();
         state->dts_alive = now;
 
         callout_reset(&state->dts_deadman, hz * dtrace_deadman_interval / NANOSEC,
             dtrace_state_deadman, state);
 }
 #endif  /* illumos */
 
 static dtrace_state_t *
 #ifdef illumos
 dtrace_state_create(dev_t *devp, cred_t *cr)
 #else
 dtrace_state_create(struct cdev *dev, struct ucred *cred __unused)
 #endif
 {
 #ifdef illumos
         minor_t minor;
         major_t major;
 #else
         cred_t *cr = NULL;
         int m = 0;
 #endif
         char c[30];
         dtrace_state_t *state;
         dtrace_optval_t *opt;
         int bufsize = NCPU * sizeof (dtrace_buffer_t), i;
         int cpu_it;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(MUTEX_HELD(&cpu_lock));
 
 #ifdef illumos
         minor = (minor_t)(uintptr_t)vmem_alloc(dtrace_minor, 1,
             VM_BESTFIT | VM_SLEEP);
 
         if (ddi_soft_state_zalloc(dtrace_softstate, minor) != DDI_SUCCESS) {
                 vmem_free(dtrace_minor, (void *)(uintptr_t)minor, 1);
                 return (NULL);
         }
 
         state = ddi_get_soft_state(dtrace_softstate, minor);
 #else
         if (dev != NULL) {
                 cr = dev->si_cred;
                 m = dev2unit(dev);
         }
 
         /* Allocate memory for the state. */
         state = kmem_zalloc(sizeof(dtrace_state_t), KM_SLEEP);
 #endif
 
         state->dts_epid = DTRACE_EPIDNONE + 1;
 
         (void) snprintf(c, sizeof (c), "dtrace_aggid_%d", m);
 #ifdef illumos
         state->dts_aggid_arena = vmem_create(c, (void *)1, UINT32_MAX, 1,
             NULL, NULL, NULL, 0, VM_SLEEP | VMC_IDENTIFIER);
 
         if (devp != NULL) {
                 major = getemajor(*devp);
         } else {
                 major = ddi_driver_major(dtrace_devi);
         }
 
         state->dts_dev = makedevice(major, minor);
 
         if (devp != NULL)
                 *devp = state->dts_dev;
 #else
         state->dts_aggid_arena = new_unrhdr(1, INT_MAX, &dtrace_unr_mtx);
         state->dts_dev = dev;
 #endif
 
         /*
          * We allocate NCPU buffers.  On the one hand, this can be quite
          * a bit of memory per instance (nearly 36K on a Starcat).  On the
          * other hand, it saves an additional memory reference in the probe
          * path.
          */
         state->dts_buffer = kmem_zalloc(bufsize, KM_SLEEP);
         state->dts_aggbuffer = kmem_zalloc(bufsize, KM_SLEEP);
 
         /*
          * Allocate and initialise the per-process per-CPU random state.
          * SI_SUB_RANDOM < SI_SUB_DTRACE_ANON therefore entropy device is
          * assumed to be seeded at this point (if from Fortuna seed file).
          */
         arc4random_buf(&state->dts_rstate[0], 2 * sizeof(uint64_t));
         for (cpu_it = 1; cpu_it < NCPU; cpu_it++) {
                 /*
                  * Each CPU is assigned a 2^64 period, non-overlapping
                  * subsequence.
                  */
                 dtrace_xoroshiro128_plus_jump(state->dts_rstate[cpu_it-1],
                     state->dts_rstate[cpu_it]); 
         }
 
 #ifdef illumos
         state->dts_cleaner = CYCLIC_NONE;
         state->dts_deadman = CYCLIC_NONE;
 #else
         callout_init(&state->dts_cleaner, 1);
         callout_init(&state->dts_deadman, 1);
 #endif
         state->dts_vstate.dtvs_state = state;
 
         for (i = 0; i < DTRACEOPT_MAX; i++)
                 state->dts_options[i] = DTRACEOPT_UNSET;
 
         /*
          * Set the default options.
          */
         opt = state->dts_options;
         opt[DTRACEOPT_BUFPOLICY] = DTRACEOPT_BUFPOLICY_SWITCH;
         opt[DTRACEOPT_BUFRESIZE] = DTRACEOPT_BUFRESIZE_AUTO;
         opt[DTRACEOPT_NSPEC] = dtrace_nspec_default;
         opt[DTRACEOPT_SPECSIZE] = dtrace_specsize_default;
         opt[DTRACEOPT_CPU] = (dtrace_optval_t)DTRACE_CPUALL;
         opt[DTRACEOPT_STRSIZE] = dtrace_strsize_default;
         opt[DTRACEOPT_STACKFRAMES] = dtrace_stackframes_default;
         opt[DTRACEOPT_USTACKFRAMES] = dtrace_ustackframes_default;
         opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_default;
         opt[DTRACEOPT_AGGRATE] = dtrace_aggrate_default;
         opt[DTRACEOPT_SWITCHRATE] = dtrace_switchrate_default;
         opt[DTRACEOPT_STATUSRATE] = dtrace_statusrate_default;
         opt[DTRACEOPT_JSTACKFRAMES] = dtrace_jstackframes_default;
         opt[DTRACEOPT_JSTACKSTRSIZE] = dtrace_jstackstrsize_default;
 
         state->dts_activity = DTRACE_ACTIVITY_INACTIVE;
 
         /*
          * Depending on the user credentials, we set flag bits which alter probe
          * visibility or the amount of destructiveness allowed.  In the case of
          * actual anonymous tracing, or the possession of all privileges, all of
          * the normal checks are bypassed.
          */
         if (cr == NULL || PRIV_POLICY_ONLY(cr, PRIV_ALL, B_FALSE)) {
                 state->dts_cred.dcr_visible = DTRACE_CRV_ALL;
                 state->dts_cred.dcr_action = DTRACE_CRA_ALL;
         } else {
                 /*
                  * Set up the credentials for this instantiation.  We take a
                  * hold on the credential to prevent it from disappearing on
                  * us; this in turn prevents the zone_t referenced by this
                  * credential from disappearing.  This means that we can
                  * examine the credential and the zone from probe context.
                  */
                 crhold(cr);
                 state->dts_cred.dcr_cred = cr;
 
                 /*
                  * CRA_PROC means "we have *some* privilege for dtrace" and
                  * unlocks the use of variables like pid, zonename, etc.
                  */
                 if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_USER, B_FALSE) ||
                     PRIV_POLICY_ONLY(cr, PRIV_DTRACE_PROC, B_FALSE)) {
                         state->dts_cred.dcr_action |= DTRACE_CRA_PROC;
                 }
 
                 /*
                  * dtrace_user allows use of syscall and profile providers.
                  * If the user also has proc_owner and/or proc_zone, we
                  * extend the scope to include additional visibility and
                  * destructive power.
                  */
                 if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_USER, B_FALSE)) {
                         if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE)) {
                                 state->dts_cred.dcr_visible |=
                                     DTRACE_CRV_ALLPROC;
 
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER;
                         }
 
                         if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE)) {
                                 state->dts_cred.dcr_visible |=
                                     DTRACE_CRV_ALLZONE;
 
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE;
                         }
 
                         /*
                          * If we have all privs in whatever zone this is,
                          * we can do destructive things to processes which
                          * have altered credentials.
                          */
 #ifdef illumos
                         if (priv_isequalset(priv_getset(cr, PRIV_EFFECTIVE),
                             cr->cr_zone->zone_privset)) {
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG;
                         }
 #endif
                 }
 
                 /*
                  * Holding the dtrace_kernel privilege also implies that
                  * the user has the dtrace_user privilege from a visibility
                  * perspective.  But without further privileges, some
                  * destructive actions are not available.
                  */
                 if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_KERNEL, B_FALSE)) {
                         /*
                          * Make all probes in all zones visible.  However,
                          * this doesn't mean that all actions become available
                          * to all zones.
                          */
                         state->dts_cred.dcr_visible |= DTRACE_CRV_KERNEL |
                             DTRACE_CRV_ALLPROC | DTRACE_CRV_ALLZONE;
 
                         state->dts_cred.dcr_action |= DTRACE_CRA_KERNEL |
                             DTRACE_CRA_PROC;
                         /*
                          * Holding proc_owner means that destructive actions
                          * for *this* zone are allowed.
                          */
                         if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE))
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER;
 
                         /*
                          * Holding proc_zone means that destructive actions
                          * for this user/group ID in all zones is allowed.
                          */
                         if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE))
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE;
 
 #ifdef illumos
                         /*
                          * If we have all privs in whatever zone this is,
                          * we can do destructive things to processes which
                          * have altered credentials.
                          */
                         if (priv_isequalset(priv_getset(cr, PRIV_EFFECTIVE),
                             cr->cr_zone->zone_privset)) {
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG;
                         }
 #endif
                 }
 
                 /*
                  * Holding the dtrace_proc privilege gives control over fasttrap
                  * and pid providers.  We need to grant wider destructive
                  * privileges in the event that the user has proc_owner and/or
                  * proc_zone.
                  */
                 if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_PROC, B_FALSE)) {
                         if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE))
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER;
 
                         if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE))
                                 state->dts_cred.dcr_action |=
                                     DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE;
                 }
         }
 
         return (state);
 }
 
 static int
 dtrace_state_buffer(dtrace_state_t *state, dtrace_buffer_t *buf, int which)
 {
         dtrace_optval_t *opt = state->dts_options, size;
         processorid_t cpu = 0;
         int flags = 0, rval, factor, divisor = 1;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(MUTEX_HELD(&cpu_lock));
         ASSERT(which < DTRACEOPT_MAX);
         ASSERT(state->dts_activity == DTRACE_ACTIVITY_INACTIVE ||
             (state == dtrace_anon.dta_state &&
             state->dts_activity == DTRACE_ACTIVITY_ACTIVE));
 
         if (opt[which] == DTRACEOPT_UNSET || opt[which] == 0)
                 return (0);
 
         if (opt[DTRACEOPT_CPU] != DTRACEOPT_UNSET)
                 cpu = opt[DTRACEOPT_CPU];
 
         if (which == DTRACEOPT_SPECSIZE)
                 flags |= DTRACEBUF_NOSWITCH;
 
         if (which == DTRACEOPT_BUFSIZE) {
                 if (opt[DTRACEOPT_BUFPOLICY] == DTRACEOPT_BUFPOLICY_RING)
                         flags |= DTRACEBUF_RING;
 
                 if (opt[DTRACEOPT_BUFPOLICY] == DTRACEOPT_BUFPOLICY_FILL)
                         flags |= DTRACEBUF_FILL;
 
                 if (state != dtrace_anon.dta_state ||
                     state->dts_activity != DTRACE_ACTIVITY_ACTIVE)
                         flags |= DTRACEBUF_INACTIVE;
         }
 
         for (size = opt[which]; size >= sizeof (uint64_t); size /= divisor) {
                 /*
                  * The size must be 8-byte aligned.  If the size is not 8-byte
                  * aligned, drop it down by the difference.
                  */
                 if (size & (sizeof (uint64_t) - 1))
                         size -= size & (sizeof (uint64_t) - 1);
 
                 if (size < state->dts_reserve) {
                         /*
                          * Buffers always must be large enough to accommodate
                          * their prereserved space.  We return E2BIG instead
                          * of ENOMEM in this case to allow for user-level
                          * software to differentiate the cases.
                          */
                         return (E2BIG);
                 }
 
                 rval = dtrace_buffer_alloc(buf, size, flags, cpu, &factor);
 
                 if (rval != ENOMEM) {
                         opt[which] = size;
                         return (rval);
                 }
 
                 if (opt[DTRACEOPT_BUFRESIZE] == DTRACEOPT_BUFRESIZE_MANUAL)
                         return (rval);
 
                 for (divisor = 2; divisor < factor; divisor <<= 1)
                         continue;
         }
 
         return (ENOMEM);
 }
 
 static int
 dtrace_state_buffers(dtrace_state_t *state)
 {
         dtrace_speculation_t *spec = state->dts_speculations;
         int rval, i;
 
         if ((rval = dtrace_state_buffer(state, state->dts_buffer,
             DTRACEOPT_BUFSIZE)) != 0)
                 return (rval);
 
         if ((rval = dtrace_state_buffer(state, state->dts_aggbuffer,
             DTRACEOPT_AGGSIZE)) != 0)
                 return (rval);
 
         for (i = 0; i < state->dts_nspeculations; i++) {
                 if ((rval = dtrace_state_buffer(state,
                     spec[i].dtsp_buffer, DTRACEOPT_SPECSIZE)) != 0)
                         return (rval);
         }
 
         return (0);
 }
 
 static void
 dtrace_state_prereserve(dtrace_state_t *state)
 {
         dtrace_ecb_t *ecb;
         dtrace_probe_t *probe;
 
         state->dts_reserve = 0;
 
         if (state->dts_options[DTRACEOPT_BUFPOLICY] != DTRACEOPT_BUFPOLICY_FILL)
                 return;
 
         /*
          * If our buffer policy is a "fill" buffer policy, we need to set the
          * prereserved space to be the space required by the END probes.
          */
         probe = dtrace_probes[dtrace_probeid_end - 1];
         ASSERT(probe != NULL);
 
         for (ecb = probe->dtpr_ecb; ecb != NULL; ecb = ecb->dte_next) {
                 if (ecb->dte_state != state)
                         continue;
 
                 state->dts_reserve += ecb->dte_needed + ecb->dte_alignment;
         }
 }
 
 static int
 dtrace_state_go(dtrace_state_t *state, processorid_t *cpu)
 {
         dtrace_optval_t *opt = state->dts_options, sz, nspec;
         dtrace_speculation_t *spec;
         dtrace_buffer_t *buf;
 #ifdef illumos
         cyc_handler_t hdlr;
         cyc_time_t when;
 #endif
         int rval = 0, i, bufsize = NCPU * sizeof (dtrace_buffer_t);
         dtrace_icookie_t cookie;
 
         mutex_enter(&cpu_lock);
         mutex_enter(&dtrace_lock);
 
         if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE) {
                 rval = EBUSY;
                 goto out;
         }
 
         /*
          * Before we can perform any checks, we must prime all of the
          * retained enablings that correspond to this state.
          */
         dtrace_enabling_prime(state);
 
         if (state->dts_destructive && !state->dts_cred.dcr_destructive) {
                 rval = EACCES;
                 goto out;
         }
 
         dtrace_state_prereserve(state);
 
         /*
          * Now we want to do is try to allocate our speculations.
          * We do not automatically resize the number of speculations; if
          * this fails, we will fail the operation.
          */
         nspec = opt[DTRACEOPT_NSPEC];
         ASSERT(nspec != DTRACEOPT_UNSET);
 
         if (nspec > INT_MAX) {
                 rval = ENOMEM;
                 goto out;
         }
 
         spec = kmem_zalloc(nspec * sizeof (dtrace_speculation_t),
             KM_NOSLEEP | KM_NORMALPRI);
 
         if (spec == NULL) {
                 rval = ENOMEM;
                 goto out;
         }
 
         state->dts_speculations = spec;
         state->dts_nspeculations = (int)nspec;
 
         for (i = 0; i < nspec; i++) {
                 if ((buf = kmem_zalloc(bufsize,
                     KM_NOSLEEP | KM_NORMALPRI)) == NULL) {
                         rval = ENOMEM;
                         goto err;
                 }
 
                 spec[i].dtsp_buffer = buf;
         }
 
         if (opt[DTRACEOPT_GRABANON] != DTRACEOPT_UNSET) {
                 if (dtrace_anon.dta_state == NULL) {
                         rval = ENOENT;
                         goto out;
                 }
 
                 if (state->dts_necbs != 0) {
                         rval = EALREADY;
                         goto out;
                 }
 
                 state->dts_anon = dtrace_anon_grab();
                 ASSERT(state->dts_anon != NULL);
                 state = state->dts_anon;
 
                 /*
                  * We want "grabanon" to be set in the grabbed state, so we'll
                  * copy that option value from the grabbing state into the
                  * grabbed state.
                  */
                 state->dts_options[DTRACEOPT_GRABANON] =
                     opt[DTRACEOPT_GRABANON];
 
                 *cpu = dtrace_anon.dta_beganon;
 
                 /*
                  * If the anonymous state is active (as it almost certainly
                  * is if the anonymous enabling ultimately matched anything),
                  * we don't allow any further option processing -- but we
                  * don't return failure.
                  */
                 if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE)
                         goto out;
         }
 
         if (opt[DTRACEOPT_AGGSIZE] != DTRACEOPT_UNSET &&
             opt[DTRACEOPT_AGGSIZE] != 0) {
                 if (state->dts_aggregations == NULL) {
                         /*
                          * We're not going to create an aggregation buffer
                          * because we don't have any ECBs that contain
                          * aggregations -- set this option to 0.
                          */
                         opt[DTRACEOPT_AGGSIZE] = 0;
                 } else {
                         /*
                          * If we have an aggregation buffer, we must also have
                          * a buffer to use as scratch.
                          */
                         if (opt[DTRACEOPT_BUFSIZE] == DTRACEOPT_UNSET ||
                             opt[DTRACEOPT_BUFSIZE] < state->dts_needed) {
                                 opt[DTRACEOPT_BUFSIZE] = state->dts_needed;
                         }
                 }
         }
 
         if (opt[DTRACEOPT_SPECSIZE] != DTRACEOPT_UNSET &&
             opt[DTRACEOPT_SPECSIZE] != 0) {
                 if (!state->dts_speculates) {
                         /*
                          * We're not going to create speculation buffers
                          * because we don't have any ECBs that actually
                          * speculate -- set the speculation size to 0.
                          */
                         opt[DTRACEOPT_SPECSIZE] = 0;
                 }
         }
 
         /*
          * The bare minimum size for any buffer that we're actually going to
          * do anything to is sizeof (uint64_t).
          */
         sz = sizeof (uint64_t);
 
         if ((state->dts_needed != 0 && opt[DTRACEOPT_BUFSIZE] < sz) ||
             (state->dts_speculates && opt[DTRACEOPT_SPECSIZE] < sz) ||
             (state->dts_aggregations != NULL && opt[DTRACEOPT_AGGSIZE] < sz)) {
                 /*
                  * A buffer size has been explicitly set to 0 (or to a size
                  * that will be adjusted to 0) and we need the space -- we
                  * need to return failure.  We return ENOSPC to differentiate
                  * it from failing to allocate a buffer due to failure to meet
                  * the reserve (for which we return E2BIG).
                  */
                 rval = ENOSPC;
                 goto out;
         }
 
         if ((rval = dtrace_state_buffers(state)) != 0)
                 goto err;
 
         if ((sz = opt[DTRACEOPT_DYNVARSIZE]) == DTRACEOPT_UNSET)
                 sz = dtrace_dstate_defsize;
 
         do {
                 rval = dtrace_dstate_init(&state->dts_vstate.dtvs_dynvars, sz);
 
                 if (rval == 0)
                         break;
 
                 if (opt[DTRACEOPT_BUFRESIZE] == DTRACEOPT_BUFRESIZE_MANUAL)
                         goto err;
         } while (sz >>= 1);
 
         opt[DTRACEOPT_DYNVARSIZE] = sz;
 
         if (rval != 0)
                 goto err;
 
         if (opt[DTRACEOPT_STATUSRATE] > dtrace_statusrate_max)
                 opt[DTRACEOPT_STATUSRATE] = dtrace_statusrate_max;
 
         if (opt[DTRACEOPT_CLEANRATE] == 0)
                 opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_max;
 
         if (opt[DTRACEOPT_CLEANRATE] < dtrace_cleanrate_min)
                 opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_min;
 
         if (opt[DTRACEOPT_CLEANRATE] > dtrace_cleanrate_max)
                 opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_max;
 
         state->dts_alive = state->dts_laststatus = dtrace_gethrtime();
 #ifdef illumos
         hdlr.cyh_func = (cyc_func_t)dtrace_state_clean;
         hdlr.cyh_arg = state;
         hdlr.cyh_level = CY_LOW_LEVEL;
 
         when.cyt_when = 0;
         when.cyt_interval = opt[DTRACEOPT_CLEANRATE];
 
         state->dts_cleaner = cyclic_add(&hdlr, &when);
 
         hdlr.cyh_func = (cyc_func_t)dtrace_state_deadman;
         hdlr.cyh_arg = state;
         hdlr.cyh_level = CY_LOW_LEVEL;
 
         when.cyt_when = 0;
         when.cyt_interval = dtrace_deadman_interval;
 
         state->dts_deadman = cyclic_add(&hdlr, &when);
 #else
         callout_reset(&state->dts_cleaner, hz * opt[DTRACEOPT_CLEANRATE] / NANOSEC,
             dtrace_state_clean, state);
         callout_reset(&state->dts_deadman, hz * dtrace_deadman_interval / NANOSEC,
             dtrace_state_deadman, state);
 #endif
 
         state->dts_activity = DTRACE_ACTIVITY_WARMUP;
 
 #ifdef illumos
         if (state->dts_getf != 0 &&
             !(state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL)) {
                 /*
                  * We don't have kernel privs but we have at least one call
                  * to getf(); we need to bump our zone's count, and (if
                  * this is the first enabling to have an unprivileged call
                  * to getf()) we need to hook into closef().
                  */
                 state->dts_cred.dcr_cred->cr_zone->zone_dtrace_getf++;
 
                 if (dtrace_getf++ == 0) {
                         ASSERT(dtrace_closef == NULL);
                         dtrace_closef = dtrace_getf_barrier;
                 }
         }
 #endif
 
         /*
          * Now it's time to actually fire the BEGIN probe.  We need to disable
          * interrupts here both to record the CPU on which we fired the BEGIN
          * probe (the data from this CPU will be processed first at user
          * level) and to manually activate the buffer for this CPU.
          */
         cookie = dtrace_interrupt_disable();
         *cpu = curcpu;
         ASSERT(state->dts_buffer[*cpu].dtb_flags & DTRACEBUF_INACTIVE);
         state->dts_buffer[*cpu].dtb_flags &= ~DTRACEBUF_INACTIVE;
 
         dtrace_probe(dtrace_probeid_begin,
             (uint64_t)(uintptr_t)state, 0, 0, 0, 0);
         dtrace_interrupt_enable(cookie);
         /*
          * We may have had an exit action from a BEGIN probe; only change our
          * state to ACTIVE if we're still in WARMUP.
          */
         ASSERT(state->dts_activity == DTRACE_ACTIVITY_WARMUP ||
             state->dts_activity == DTRACE_ACTIVITY_DRAINING);
 
         if (state->dts_activity == DTRACE_ACTIVITY_WARMUP)
                 state->dts_activity = DTRACE_ACTIVITY_ACTIVE;
 
 #ifdef __FreeBSD__
         /*
          * We enable anonymous tracing before APs are started, so we must
          * activate buffers using the current CPU.
          */
         if (state == dtrace_anon.dta_state)
                 for (int i = 0; i < NCPU; i++)
                         dtrace_buffer_activate_cpu(state, i);
         else
                 dtrace_xcall(DTRACE_CPUALL,
                     (dtrace_xcall_t)dtrace_buffer_activate, state);
 #else
         /*
          * Regardless of whether or not now we're in ACTIVE or DRAINING, we
          * want each CPU to transition its principal buffer out of the
          * INACTIVE state.  Doing this assures that no CPU will suddenly begin
          * processing an ECB halfway down a probe's ECB chain; all CPUs will
          * atomically transition from processing none of a state's ECBs to
          * processing all of them.
          */
         dtrace_xcall(DTRACE_CPUALL,
             (dtrace_xcall_t)dtrace_buffer_activate, state);
 #endif
         goto out;
 
 err:
         dtrace_buffer_free(state->dts_buffer);
         dtrace_buffer_free(state->dts_aggbuffer);
 
         if ((nspec = state->dts_nspeculations) == 0) {
                 ASSERT(state->dts_speculations == NULL);
                 goto out;
         }
 
         spec = state->dts_speculations;
         ASSERT(spec != NULL);
 
         for (i = 0; i < state->dts_nspeculations; i++) {
                 if ((buf = spec[i].dtsp_buffer) == NULL)
                         break;
 
                 dtrace_buffer_free(buf);
                 kmem_free(buf, bufsize);
         }
 
         kmem_free(spec, nspec * sizeof (dtrace_speculation_t));
         state->dts_nspeculations = 0;
         state->dts_speculations = NULL;
 
 out:
         mutex_exit(&dtrace_lock);
         mutex_exit(&cpu_lock);
 
         return (rval);
 }
 
 static int
 dtrace_state_stop(dtrace_state_t *state, processorid_t *cpu)
 {
         dtrace_icookie_t cookie;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if (state->dts_activity != DTRACE_ACTIVITY_ACTIVE &&
             state->dts_activity != DTRACE_ACTIVITY_DRAINING)
                 return (EINVAL);
 
         /*
          * We'll set the activity to DTRACE_ACTIVITY_DRAINING, and issue a sync
          * to be sure that every CPU has seen it.  See below for the details
          * on why this is done.
          */
         state->dts_activity = DTRACE_ACTIVITY_DRAINING;
         dtrace_sync();
 
         /*
          * By this point, it is impossible for any CPU to be still processing
          * with DTRACE_ACTIVITY_ACTIVE.  We can thus set our activity to
          * DTRACE_ACTIVITY_COOLDOWN and know that we're not racing with any
          * other CPU in dtrace_buffer_reserve().  This allows dtrace_probe()
          * and callees to know that the activity is DTRACE_ACTIVITY_COOLDOWN
          * iff we're in the END probe.
          */
         state->dts_activity = DTRACE_ACTIVITY_COOLDOWN;
         dtrace_sync();
         ASSERT(state->dts_activity == DTRACE_ACTIVITY_COOLDOWN);
 
         /*
          * Finally, we can release the reserve and call the END probe.  We
          * disable interrupts across calling the END probe to allow us to
          * return the CPU on which we actually called the END probe.  This
          * allows user-land to be sure that this CPU's principal buffer is
          * processed last.
          */
         state->dts_reserve = 0;
 
         cookie = dtrace_interrupt_disable();
         *cpu = curcpu;
         dtrace_probe(dtrace_probeid_end,
             (uint64_t)(uintptr_t)state, 0, 0, 0, 0);
         dtrace_interrupt_enable(cookie);
 
         state->dts_activity = DTRACE_ACTIVITY_STOPPED;
         dtrace_sync();
 
 #ifdef illumos
         if (state->dts_getf != 0 &&
             !(state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL)) {
                 /*
                  * We don't have kernel privs but we have at least one call
                  * to getf(); we need to lower our zone's count, and (if
                  * this is the last enabling to have an unprivileged call
                  * to getf()) we need to clear the closef() hook.
                  */
                 ASSERT(state->dts_cred.dcr_cred->cr_zone->zone_dtrace_getf > 0);
                 ASSERT(dtrace_closef == dtrace_getf_barrier);
                 ASSERT(dtrace_getf > 0);
 
                 state->dts_cred.dcr_cred->cr_zone->zone_dtrace_getf--;
 
                 if (--dtrace_getf == 0)
                         dtrace_closef = NULL;
         }
 #endif
 
         return (0);
 }
 
 static int
 dtrace_state_option(dtrace_state_t *state, dtrace_optid_t option,
     dtrace_optval_t val)
 {
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE)
                 return (EBUSY);
 
         if (option >= DTRACEOPT_MAX)
                 return (EINVAL);
 
         if (option != DTRACEOPT_CPU && val < 0)
                 return (EINVAL);
 
         switch (option) {
         case DTRACEOPT_DESTRUCTIVE:
                 if (dtrace_destructive_disallow)
                         return (EACCES);
 
                 state->dts_cred.dcr_destructive = 1;
                 break;
 
         case DTRACEOPT_BUFSIZE:
         case DTRACEOPT_DYNVARSIZE:
         case DTRACEOPT_AGGSIZE:
         case DTRACEOPT_SPECSIZE:
         case DTRACEOPT_STRSIZE:
                 if (val < 0)
                         return (EINVAL);
 
                 if (val >= LONG_MAX) {
                         /*
                          * If this is an otherwise negative value, set it to
                          * the highest multiple of 128m less than LONG_MAX.
                          * Technically, we're adjusting the size without
                          * regard to the buffer resizing policy, but in fact,
                          * this has no effect -- if we set the buffer size to
                          * ~LONG_MAX and the buffer policy is ultimately set to
                          * be "manual", the buffer allocation is guaranteed to
                          * fail, if only because the allocation requires two
                          * buffers.  (We set the the size to the highest
                          * multiple of 128m because it ensures that the size
                          * will remain a multiple of a megabyte when
                          * repeatedly halved -- all the way down to 15m.)
                          */
                         val = LONG_MAX - (1 << 27) + 1;
                 }
         }
 
         state->dts_options[option] = val;
 
         return (0);
 }
 
 static void
 dtrace_state_destroy(dtrace_state_t *state)
 {
         dtrace_ecb_t *ecb;
         dtrace_vstate_t *vstate = &state->dts_vstate;
 #ifdef illumos
         minor_t minor = getminor(state->dts_dev);
 #endif
         int i, bufsize = NCPU * sizeof (dtrace_buffer_t);
         dtrace_speculation_t *spec = state->dts_speculations;
         int nspec = state->dts_nspeculations;
         uint32_t match;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(MUTEX_HELD(&cpu_lock));
 
         /*
          * First, retract any retained enablings for this state.
          */
         dtrace_enabling_retract(state);
         ASSERT(state->dts_nretained == 0);
 
         if (state->dts_activity == DTRACE_ACTIVITY_ACTIVE ||
             state->dts_activity == DTRACE_ACTIVITY_DRAINING) {
                 /*
                  * We have managed to come into dtrace_state_destroy() on a
                  * hot enabling -- almost certainly because of a disorderly
                  * shutdown of a consumer.  (That is, a consumer that is
                  * exiting without having called dtrace_stop().) In this case,
                  * we're going to set our activity to be KILLED, and then
                  * issue a sync to be sure that everyone is out of probe
                  * context before we start blowing away ECBs.
                  */
                 state->dts_activity = DTRACE_ACTIVITY_KILLED;
                 dtrace_sync();
         }
 
         /*
          * Release the credential hold we took in dtrace_state_create().
          */
         if (state->dts_cred.dcr_cred != NULL)
                 crfree(state->dts_cred.dcr_cred);
 
         /*
          * Now we can safely disable and destroy any enabled probes.  Because
          * any DTRACE_PRIV_KERNEL probes may actually be slowing our progress
          * (especially if they're all enabled), we take two passes through the
          * ECBs:  in the first, we disable just DTRACE_PRIV_KERNEL probes, and
          * in the second we disable whatever is left over.
          */
         for (match = DTRACE_PRIV_KERNEL; ; match = 0) {
                 for (i = 0; i < state->dts_necbs; i++) {
                         if ((ecb = state->dts_ecbs[i]) == NULL)
                                 continue;
 
                         if (match && ecb->dte_probe != NULL) {
                                 dtrace_probe_t *probe = ecb->dte_probe;
                                 dtrace_provider_t *prov = probe->dtpr_provider;
 
                                 if (!(prov->dtpv_priv.dtpp_flags & match))
                                         continue;
                         }
 
                         dtrace_ecb_disable(ecb);
                         dtrace_ecb_destroy(ecb);
                 }
 
                 if (!match)
                         break;
         }
 
         /*
          * Before we free the buffers, perform one more sync to assure that
          * every CPU is out of probe context.
          */
         dtrace_sync();
 
         dtrace_buffer_free(state->dts_buffer);
         dtrace_buffer_free(state->dts_aggbuffer);
 
         for (i = 0; i < nspec; i++)
                 dtrace_buffer_free(spec[i].dtsp_buffer);
 
 #ifdef illumos
         if (state->dts_cleaner != CYCLIC_NONE)
                 cyclic_remove(state->dts_cleaner);
 
         if (state->dts_deadman != CYCLIC_NONE)
                 cyclic_remove(state->dts_deadman);
 #else
         callout_stop(&state->dts_cleaner);
         callout_drain(&state->dts_cleaner);
         callout_stop(&state->dts_deadman);
         callout_drain(&state->dts_deadman);
 #endif
 
         dtrace_dstate_fini(&vstate->dtvs_dynvars);
         dtrace_vstate_fini(vstate);
         if (state->dts_ecbs != NULL)
                 kmem_free(state->dts_ecbs, state->dts_necbs * sizeof (dtrace_ecb_t *));
 
         if (state->dts_aggregations != NULL) {
 #ifdef DEBUG
                 for (i = 0; i < state->dts_naggregations; i++)
                         ASSERT(state->dts_aggregations[i] == NULL);
 #endif
                 ASSERT(state->dts_naggregations > 0);
                 kmem_free(state->dts_aggregations,
                     state->dts_naggregations * sizeof (dtrace_aggregation_t *));
         }
 
         kmem_free(state->dts_buffer, bufsize);
         kmem_free(state->dts_aggbuffer, bufsize);
 
         for (i = 0; i < nspec; i++)
                 kmem_free(spec[i].dtsp_buffer, bufsize);
 
         if (spec != NULL)
                 kmem_free(spec, nspec * sizeof (dtrace_speculation_t));
 
         dtrace_format_destroy(state);
 
         if (state->dts_aggid_arena != NULL) {
 #ifdef illumos
                 vmem_destroy(state->dts_aggid_arena);
 #else
                 delete_unrhdr(state->dts_aggid_arena);
 #endif
                 state->dts_aggid_arena = NULL;
         }
 #ifdef illumos
         ddi_soft_state_free(dtrace_softstate, minor);
         vmem_free(dtrace_minor, (void *)(uintptr_t)minor, 1);
 #endif
 }
 
 /*
  * DTrace Anonymous Enabling Functions
  */
 static dtrace_state_t *
 dtrace_anon_grab(void)
 {
         dtrace_state_t *state;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if ((state = dtrace_anon.dta_state) == NULL) {
                 ASSERT(dtrace_anon.dta_enabling == NULL);
                 return (NULL);
         }
 
         ASSERT(dtrace_anon.dta_enabling != NULL);
         ASSERT(dtrace_retained != NULL);
 
         dtrace_enabling_destroy(dtrace_anon.dta_enabling);
         dtrace_anon.dta_enabling = NULL;
         dtrace_anon.dta_state = NULL;
 
         return (state);
 }
 
 static void
 dtrace_anon_property(void)
 {
         int i, rv;
         dtrace_state_t *state;
         dof_hdr_t *dof;
         char c[32];             /* enough for "dof-data-" + digits */
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(MUTEX_HELD(&cpu_lock));
 
         for (i = 0; ; i++) {
                 (void) snprintf(c, sizeof (c), "dof-data-%d", i);
 
                 dtrace_err_verbose = 1;
 
                 if ((dof = dtrace_dof_property(c)) == NULL) {
                         dtrace_err_verbose = 0;
                         break;
                 }
 
 #ifdef illumos
                 /*
                  * We want to create anonymous state, so we need to transition
                  * the kernel debugger to indicate that DTrace is active.  If
                  * this fails (e.g. because the debugger has modified text in
                  * some way), we won't continue with the processing.
                  */
                 if (kdi_dtrace_set(KDI_DTSET_DTRACE_ACTIVATE) != 0) {
                         cmn_err(CE_NOTE, "kernel debugger active; anonymous "
                             "enabling ignored.");
                         dtrace_dof_destroy(dof);
                         break;
                 }
 #endif
 
                 /*
                  * If we haven't allocated an anonymous state, we'll do so now.
                  */
                 if ((state = dtrace_anon.dta_state) == NULL) {
                         state = dtrace_state_create(NULL, NULL);
                         dtrace_anon.dta_state = state;
 
                         if (state == NULL) {
                                 /*
                                  * This basically shouldn't happen:  the only
                                  * failure mode from dtrace_state_create() is a
                                  * failure of ddi_soft_state_zalloc() that
                                  * itself should never happen.  Still, the
                                  * interface allows for a failure mode, and
                                  * we want to fail as gracefully as possible:
                                  * we'll emit an error message and cease
                                  * processing anonymous state in this case.
                                  */
                                 cmn_err(CE_WARN, "failed to create "
                                     "anonymous state");
                                 dtrace_dof_destroy(dof);
                                 break;
                         }
                 }
 
                 rv = dtrace_dof_slurp(dof, &state->dts_vstate, CRED(),
                     &dtrace_anon.dta_enabling, 0, 0, B_TRUE);
 
                 if (rv == 0)
                         rv = dtrace_dof_options(dof, state);
 
                 dtrace_err_verbose = 0;
                 dtrace_dof_destroy(dof);
 
                 if (rv != 0) {
                         /*
                          * This is malformed DOF; chuck any anonymous state
                          * that we created.
                          */
                         ASSERT(dtrace_anon.dta_enabling == NULL);
                         dtrace_state_destroy(state);
                         dtrace_anon.dta_state = NULL;
                         break;
                 }
 
                 ASSERT(dtrace_anon.dta_enabling != NULL);
         }
 
         if (dtrace_anon.dta_enabling != NULL) {
                 int rval;
 
                 /*
                  * dtrace_enabling_retain() can only fail because we are
                  * trying to retain more enablings than are allowed -- but
                  * we only have one anonymous enabling, and we are guaranteed
                  * to be allowed at least one retained enabling; we assert
                  * that dtrace_enabling_retain() returns success.
                  */
                 rval = dtrace_enabling_retain(dtrace_anon.dta_enabling);
                 ASSERT(rval == 0);
 
                 dtrace_enabling_dump(dtrace_anon.dta_enabling);
         }
 }
 
 /*
  * DTrace Helper Functions
  */
 static void
 dtrace_helper_trace(dtrace_helper_action_t *helper,
     dtrace_mstate_t *mstate, dtrace_vstate_t *vstate, int where)
 {
         uint32_t size, next, nnext, i;
         dtrace_helptrace_t *ent, *buffer;
         uint16_t flags = cpu_core[curcpu].cpuc_dtrace_flags;
 
         if ((buffer = dtrace_helptrace_buffer) == NULL)
                 return;
 
         ASSERT(vstate->dtvs_nlocals <= dtrace_helptrace_nlocals);
 
         /*
          * What would a tracing framework be without its own tracing
          * framework?  (Well, a hell of a lot simpler, for starters...)
          */
         size = sizeof (dtrace_helptrace_t) + dtrace_helptrace_nlocals *
             sizeof (uint64_t) - sizeof (uint64_t);
 
         /*
          * Iterate until we can allocate a slot in the trace buffer.
          */
         do {
                 next = dtrace_helptrace_next;
 
                 if (next + size < dtrace_helptrace_bufsize) {
                         nnext = next + size;
                 } else {
                         nnext = size;
                 }
         } while (dtrace_cas32(&dtrace_helptrace_next, next, nnext) != next);
 
         /*
          * We have our slot; fill it in.
          */
         if (nnext == size) {
                 dtrace_helptrace_wrapped++;
                 next = 0;
         }
 
         ent = (dtrace_helptrace_t *)((uintptr_t)buffer + next);
         ent->dtht_helper = helper;
         ent->dtht_where = where;
         ent->dtht_nlocals = vstate->dtvs_nlocals;
 
         ent->dtht_fltoffs = (mstate->dtms_present & DTRACE_MSTATE_FLTOFFS) ?
             mstate->dtms_fltoffs : -1;
         ent->dtht_fault = DTRACE_FLAGS2FLT(flags);
         ent->dtht_illval = cpu_core[curcpu].cpuc_dtrace_illval;
 
         for (i = 0; i < vstate->dtvs_nlocals; i++) {
                 dtrace_statvar_t *svar;
 
                 if ((svar = vstate->dtvs_locals[i]) == NULL)
                         continue;
 
                 ASSERT(svar->dtsv_size >= NCPU * sizeof (uint64_t));
                 ent->dtht_locals[i] =
                     ((uint64_t *)(uintptr_t)svar->dtsv_data)[curcpu];
         }
 }
 
 static uint64_t
 dtrace_helper(int which, dtrace_mstate_t *mstate,
     dtrace_state_t *state, uint64_t arg0, uint64_t arg1)
 {
         uint16_t *flags = &cpu_core[curcpu].cpuc_dtrace_flags;
         uint64_t sarg0 = mstate->dtms_arg[0];
         uint64_t sarg1 = mstate->dtms_arg[1];
         uint64_t rval = 0;
         dtrace_helpers_t *helpers = curproc->p_dtrace_helpers;
         dtrace_helper_action_t *helper;
         dtrace_vstate_t *vstate;
         dtrace_difo_t *pred;
         int i, trace = dtrace_helptrace_buffer != NULL;
 
         ASSERT(which >= 0 && which < DTRACE_NHELPER_ACTIONS);
 
         if (helpers == NULL)
                 return (0);
 
         if ((helper = helpers->dthps_actions[which]) == NULL)
                 return (0);
 
         vstate = &helpers->dthps_vstate;
         mstate->dtms_arg[0] = arg0;
         mstate->dtms_arg[1] = arg1;
 
         /*
          * Now iterate over each helper.  If its predicate evaluates to 'true',
          * we'll call the corresponding actions.  Note that the below calls
          * to dtrace_dif_emulate() may set faults in machine state.  This is
          * okay:  our caller (the outer dtrace_dif_emulate()) will simply plow
          * the stored DIF offset with its own (which is the desired behavior).
          * Also, note the calls to dtrace_dif_emulate() may allocate scratch
          * from machine state; this is okay, too.
          */
         for (; helper != NULL; helper = helper->dtha_next) {
                 if ((pred = helper->dtha_predicate) != NULL) {
                         if (trace)
                                 dtrace_helper_trace(helper, mstate, vstate, 0);
 
                         if (!dtrace_dif_emulate(pred, mstate, vstate, state))
                                 goto next;
 
                         if (*flags & CPU_DTRACE_FAULT)
                                 goto err;
                 }
 
                 for (i = 0; i < helper->dtha_nactions; i++) {
                         if (trace)
                                 dtrace_helper_trace(helper,
                                     mstate, vstate, i + 1);
 
                         rval = dtrace_dif_emulate(helper->dtha_actions[i],
                             mstate, vstate, state);
 
                         if (*flags & CPU_DTRACE_FAULT)
                                 goto err;
                 }
 
 next:
                 if (trace)
                         dtrace_helper_trace(helper, mstate, vstate,
                             DTRACE_HELPTRACE_NEXT);
         }
 
         if (trace)
                 dtrace_helper_trace(helper, mstate, vstate,
                     DTRACE_HELPTRACE_DONE);
 
         /*
          * Restore the arg0 that we saved upon entry.
          */
         mstate->dtms_arg[0] = sarg0;
         mstate->dtms_arg[1] = sarg1;
 
         return (rval);
 
 err:
         if (trace)
                 dtrace_helper_trace(helper, mstate, vstate,
                     DTRACE_HELPTRACE_ERR);
 
         /*
          * Restore the arg0 that we saved upon entry.
          */
         mstate->dtms_arg[0] = sarg0;
         mstate->dtms_arg[1] = sarg1;
 
         return (0);
 }
 
 static void
 dtrace_helper_action_destroy(dtrace_helper_action_t *helper,
     dtrace_vstate_t *vstate)
 {
         int i;
 
         if (helper->dtha_predicate != NULL)
                 dtrace_difo_release(helper->dtha_predicate, vstate);
 
         for (i = 0; i < helper->dtha_nactions; i++) {
                 ASSERT(helper->dtha_actions[i] != NULL);
                 dtrace_difo_release(helper->dtha_actions[i], vstate);
         }
 
         kmem_free(helper->dtha_actions,
             helper->dtha_nactions * sizeof (dtrace_difo_t *));
         kmem_free(helper, sizeof (dtrace_helper_action_t));
 }
 
 static int
 dtrace_helper_destroygen(dtrace_helpers_t *help, int gen)
 {
         proc_t *p = curproc;
         dtrace_vstate_t *vstate;
         int i;
 
         if (help == NULL)
                 help = p->p_dtrace_helpers;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if (help == NULL || gen > help->dthps_generation)
                 return (EINVAL);
 
         vstate = &help->dthps_vstate;
 
         for (i = 0; i < DTRACE_NHELPER_ACTIONS; i++) {
                 dtrace_helper_action_t *last = NULL, *h, *next;
 
                 for (h = help->dthps_actions[i]; h != NULL; h = next) {
                         next = h->dtha_next;
 
                         if (h->dtha_generation == gen) {
                                 if (last != NULL) {
                                         last->dtha_next = next;
                                 } else {
                                         help->dthps_actions[i] = next;
                                 }
 
                                 dtrace_helper_action_destroy(h, vstate);
                         } else {
                                 last = h;
                         }
                 }
         }
 
         /*
          * Interate until we've cleared out all helper providers with the
          * given generation number.
          */
         for (;;) {
                 dtrace_helper_provider_t *prov;
 
                 /*
                  * Look for a helper provider with the right generation. We
                  * have to start back at the beginning of the list each time
                  * because we drop dtrace_lock. It's unlikely that we'll make
                  * more than two passes.
                  */
                 for (i = 0; i < help->dthps_nprovs; i++) {
                         prov = help->dthps_provs[i];
 
                         if (prov->dthp_generation == gen)
                                 break;
                 }
 
                 /*
                  * If there were no matches, we're done.
                  */
                 if (i == help->dthps_nprovs)
                         break;
 
                 /*
                  * Move the last helper provider into this slot.
                  */
                 help->dthps_nprovs--;
                 help->dthps_provs[i] = help->dthps_provs[help->dthps_nprovs];
                 help->dthps_provs[help->dthps_nprovs] = NULL;
 
                 mutex_exit(&dtrace_lock);
 
                 /*
                  * If we have a meta provider, remove this helper provider.
                  */
                 mutex_enter(&dtrace_meta_lock);
                 if (dtrace_meta_pid != NULL) {
                         ASSERT(dtrace_deferred_pid == NULL);
                         dtrace_helper_provider_remove(&prov->dthp_prov,
                             p->p_pid);
                 }
                 mutex_exit(&dtrace_meta_lock);
 
                 dtrace_helper_provider_destroy(prov);
 
                 mutex_enter(&dtrace_lock);
         }
 
         return (0);
 }
 
 static int
 dtrace_helper_validate(dtrace_helper_action_t *helper)
 {
         int err = 0, i;
         dtrace_difo_t *dp;
 
         if ((dp = helper->dtha_predicate) != NULL)
                 err += dtrace_difo_validate_helper(dp);
 
         for (i = 0; i < helper->dtha_nactions; i++)
                 err += dtrace_difo_validate_helper(helper->dtha_actions[i]);
 
         return (err == 0);
 }
 
 static int
 dtrace_helper_action_add(int which, dtrace_ecbdesc_t *ep,
     dtrace_helpers_t *help)
 {
         dtrace_helper_action_t *helper, *last;
         dtrace_actdesc_t *act;
         dtrace_vstate_t *vstate;
         dtrace_predicate_t *pred;
         int count = 0, nactions = 0, i;
 
         if (which < 0 || which >= DTRACE_NHELPER_ACTIONS)
                 return (EINVAL);
 
         last = help->dthps_actions[which];
         vstate = &help->dthps_vstate;
 
         for (count = 0; last != NULL; last = last->dtha_next) {
                 count++;
                 if (last->dtha_next == NULL)
                         break;
         }
 
         /*
          * If we already have dtrace_helper_actions_max helper actions for this
          * helper action type, we'll refuse to add a new one.
          */
         if (count >= dtrace_helper_actions_max)
                 return (ENOSPC);
 
         helper = kmem_zalloc(sizeof (dtrace_helper_action_t), KM_SLEEP);
         helper->dtha_generation = help->dthps_generation;
 
         if ((pred = ep->dted_pred.dtpdd_predicate) != NULL) {
                 ASSERT(pred->dtp_difo != NULL);
                 dtrace_difo_hold(pred->dtp_difo);
                 helper->dtha_predicate = pred->dtp_difo;
         }
 
         for (act = ep->dted_action; act != NULL; act = act->dtad_next) {
                 if (act->dtad_kind != DTRACEACT_DIFEXPR)
                         goto err;
 
                 if (act->dtad_difo == NULL)
                         goto err;
 
                 nactions++;
         }
 
         helper->dtha_actions = kmem_zalloc(sizeof (dtrace_difo_t *) *
             (helper->dtha_nactions = nactions), KM_SLEEP);
 
         for (act = ep->dted_action, i = 0; act != NULL; act = act->dtad_next) {
                 dtrace_difo_hold(act->dtad_difo);
                 helper->dtha_actions[i++] = act->dtad_difo;
         }
 
         if (!dtrace_helper_validate(helper))
                 goto err;
 
         if (last == NULL) {
                 help->dthps_actions[which] = helper;
         } else {
                 last->dtha_next = helper;
         }
 
         if (vstate->dtvs_nlocals > dtrace_helptrace_nlocals) {
                 dtrace_helptrace_nlocals = vstate->dtvs_nlocals;
                 dtrace_helptrace_next = 0;
         }
 
         return (0);
 err:
         dtrace_helper_action_destroy(helper, vstate);
         return (EINVAL);
 }
 
 static void
 dtrace_helper_provider_register(proc_t *p, dtrace_helpers_t *help,
     dof_helper_t *dofhp)
 {
         ASSERT(MUTEX_NOT_HELD(&dtrace_lock));
 
         mutex_enter(&dtrace_meta_lock);
         mutex_enter(&dtrace_lock);
 
         if (!dtrace_attached() || dtrace_meta_pid == NULL) {
                 /*
                  * If the dtrace module is loaded but not attached, or if
                  * there aren't isn't a meta provider registered to deal with
                  * these provider descriptions, we need to postpone creating
                  * the actual providers until later.
                  */
 
                 if (help->dthps_next == NULL && help->dthps_prev == NULL &&
                     dtrace_deferred_pid != help) {
                         help->dthps_deferred = 1;
                         help->dthps_pid = p->p_pid;
                         help->dthps_next = dtrace_deferred_pid;
                         help->dthps_prev = NULL;
                         if (dtrace_deferred_pid != NULL)
                                 dtrace_deferred_pid->dthps_prev = help;
                         dtrace_deferred_pid = help;
                 }
 
                 mutex_exit(&dtrace_lock);
 
         } else if (dofhp != NULL) {
                 /*
                  * If the dtrace module is loaded and we have a particular
                  * helper provider description, pass that off to the
                  * meta provider.
                  */
 
                 mutex_exit(&dtrace_lock);
 
                 dtrace_helper_provide(dofhp, p->p_pid);
 
         } else {
                 /*
                  * Otherwise, just pass all the helper provider descriptions
                  * off to the meta provider.
                  */
 
                 int i;
                 mutex_exit(&dtrace_lock);
 
                 for (i = 0; i < help->dthps_nprovs; i++) {
                         dtrace_helper_provide(&help->dthps_provs[i]->dthp_prov,
                             p->p_pid);
                 }
         }
 
         mutex_exit(&dtrace_meta_lock);
 }
 
 static int
 dtrace_helper_provider_add(dof_helper_t *dofhp, dtrace_helpers_t *help, int gen)
 {
         dtrace_helper_provider_t *hprov, **tmp_provs;
         uint_t tmp_maxprovs, i;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(help != NULL);
 
         /*
          * If we already have dtrace_helper_providers_max helper providers,
          * we're refuse to add a new one.
          */
         if (help->dthps_nprovs >= dtrace_helper_providers_max)
                 return (ENOSPC);
 
         /*
          * Check to make sure this isn't a duplicate.
          */
         for (i = 0; i < help->dthps_nprovs; i++) {
                 if (dofhp->dofhp_addr ==
                     help->dthps_provs[i]->dthp_prov.dofhp_addr)
                         return (EALREADY);
         }
 
         hprov = kmem_zalloc(sizeof (dtrace_helper_provider_t), KM_SLEEP);
         hprov->dthp_prov = *dofhp;
         hprov->dthp_ref = 1;
         hprov->dthp_generation = gen;
 
         /*
          * Allocate a bigger table for helper providers if it's already full.
          */
         if (help->dthps_maxprovs == help->dthps_nprovs) {
                 tmp_maxprovs = help->dthps_maxprovs;
                 tmp_provs = help->dthps_provs;
 
                 if (help->dthps_maxprovs == 0)
                         help->dthps_maxprovs = 2;
                 else
                         help->dthps_maxprovs *= 2;
                 if (help->dthps_maxprovs > dtrace_helper_providers_max)
                         help->dthps_maxprovs = dtrace_helper_providers_max;
 
                 ASSERT(tmp_maxprovs < help->dthps_maxprovs);
 
                 help->dthps_provs = kmem_zalloc(help->dthps_maxprovs *
                     sizeof (dtrace_helper_provider_t *), KM_SLEEP);
 
                 if (tmp_provs != NULL) {
                         bcopy(tmp_provs, help->dthps_provs, tmp_maxprovs *
                             sizeof (dtrace_helper_provider_t *));
                         kmem_free(tmp_provs, tmp_maxprovs *
                             sizeof (dtrace_helper_provider_t *));
                 }
         }
 
         help->dthps_provs[help->dthps_nprovs] = hprov;
         help->dthps_nprovs++;
 
         return (0);
 }
 
 static void
 dtrace_helper_provider_destroy(dtrace_helper_provider_t *hprov)
 {
         mutex_enter(&dtrace_lock);
 
         if (--hprov->dthp_ref == 0) {
                 dof_hdr_t *dof;
                 mutex_exit(&dtrace_lock);
                 dof = (dof_hdr_t *)(uintptr_t)hprov->dthp_prov.dofhp_dof;
                 dtrace_dof_destroy(dof);
                 kmem_free(hprov, sizeof (dtrace_helper_provider_t));
         } else {
                 mutex_exit(&dtrace_lock);
         }
 }
 
 static int
 dtrace_helper_provider_validate(dof_hdr_t *dof, dof_sec_t *sec)
 {
         uintptr_t daddr = (uintptr_t)dof;
         dof_sec_t *str_sec, *prb_sec, *arg_sec, *off_sec, *enoff_sec;
         dof_provider_t *provider;
         dof_probe_t *probe;
         uint8_t *arg;
         char *strtab, *typestr;
         dof_stridx_t typeidx;
         size_t typesz;
         uint_t nprobes, j, k;
 
         ASSERT(sec->dofs_type == DOF_SECT_PROVIDER);
 
         if (sec->dofs_offset & (sizeof (uint_t) - 1)) {
                 dtrace_dof_error(dof, "misaligned section offset");
                 return (-1);
         }
 
         /*
          * The section needs to be large enough to contain the DOF provider
          * structure appropriate for the given version.
          */
         if (sec->dofs_size <
             ((dof->dofh_ident[DOF_ID_VERSION] == DOF_VERSION_1) ?
             offsetof(dof_provider_t, dofpv_prenoffs) :
             sizeof (dof_provider_t))) {
                 dtrace_dof_error(dof, "provider section too small");
                 return (-1);
         }
 
         provider = (dof_provider_t *)(uintptr_t)(daddr + sec->dofs_offset);
         str_sec = dtrace_dof_sect(dof, DOF_SECT_STRTAB, provider->dofpv_strtab);
         prb_sec = dtrace_dof_sect(dof, DOF_SECT_PROBES, provider->dofpv_probes);
         arg_sec = dtrace_dof_sect(dof, DOF_SECT_PRARGS, provider->dofpv_prargs);
         off_sec = dtrace_dof_sect(dof, DOF_SECT_PROFFS, provider->dofpv_proffs);
 
         if (str_sec == NULL || prb_sec == NULL ||
             arg_sec == NULL || off_sec == NULL)
                 return (-1);
 
         enoff_sec = NULL;
 
         if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1 &&
             provider->dofpv_prenoffs != DOF_SECT_NONE &&
             (enoff_sec = dtrace_dof_sect(dof, DOF_SECT_PRENOFFS,
             provider->dofpv_prenoffs)) == NULL)
                 return (-1);
 
         strtab = (char *)(uintptr_t)(daddr + str_sec->dofs_offset);
 
         if (provider->dofpv_name >= str_sec->dofs_size ||
             strlen(strtab + provider->dofpv_name) >= DTRACE_PROVNAMELEN) {
                 dtrace_dof_error(dof, "invalid provider name");
                 return (-1);
         }
 
         if (prb_sec->dofs_entsize == 0 ||
             prb_sec->dofs_entsize > prb_sec->dofs_size) {
                 dtrace_dof_error(dof, "invalid entry size");
                 return (-1);
         }
 
         if (prb_sec->dofs_entsize & (sizeof (uintptr_t) - 1)) {
                 dtrace_dof_error(dof, "misaligned entry size");
                 return (-1);
         }
 
         if (off_sec->dofs_entsize != sizeof (uint32_t)) {
                 dtrace_dof_error(dof, "invalid entry size");
                 return (-1);
         }
 
         if (off_sec->dofs_offset & (sizeof (uint32_t) - 1)) {
                 dtrace_dof_error(dof, "misaligned section offset");
                 return (-1);
         }
 
         if (arg_sec->dofs_entsize != sizeof (uint8_t)) {
                 dtrace_dof_error(dof, "invalid entry size");
                 return (-1);
         }
 
         arg = (uint8_t *)(uintptr_t)(daddr + arg_sec->dofs_offset);
 
         nprobes = prb_sec->dofs_size / prb_sec->dofs_entsize;
 
         /*
          * Take a pass through the probes to check for errors.
          */
         for (j = 0; j < nprobes; j++) {
                 probe = (dof_probe_t *)(uintptr_t)(daddr +
                     prb_sec->dofs_offset + j * prb_sec->dofs_entsize);
 
                 if (probe->dofpr_func >= str_sec->dofs_size) {
                         dtrace_dof_error(dof, "invalid function name");
                         return (-1);
                 }
 
                 if (strlen(strtab + probe->dofpr_func) >= DTRACE_FUNCNAMELEN) {
                         dtrace_dof_error(dof, "function name too long");
                         /*
                          * Keep going if the function name is too long.
                          * Unlike provider and probe names, we cannot reasonably
                          * impose restrictions on function names, since they're
                          * a property of the code being instrumented. We will
                          * skip this probe in dtrace_helper_provide_one().
                          */
                 }
 
                 if (probe->dofpr_name >= str_sec->dofs_size ||
                     strlen(strtab + probe->dofpr_name) >= DTRACE_NAMELEN) {
                         dtrace_dof_error(dof, "invalid probe name");
                         return (-1);
                 }
 
                 /*
                  * The offset count must not wrap the index, and the offsets
                  * must also not overflow the section's data.
                  */
                 if (probe->dofpr_offidx + probe->dofpr_noffs <
                     probe->dofpr_offidx ||
                     (probe->dofpr_offidx + probe->dofpr_noffs) *
                     off_sec->dofs_entsize > off_sec->dofs_size) {
                         dtrace_dof_error(dof, "invalid probe offset");
                         return (-1);
                 }
 
                 if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1) {
                         /*
                          * If there's no is-enabled offset section, make sure
                          * there aren't any is-enabled offsets. Otherwise
                          * perform the same checks as for probe offsets
                          * (immediately above).
                          */
                         if (enoff_sec == NULL) {
                                 if (probe->dofpr_enoffidx != 0 ||
                                     probe->dofpr_nenoffs != 0) {
                                         dtrace_dof_error(dof, "is-enabled "
                                             "offsets with null section");
                                         return (-1);
                                 }
                         } else if (probe->dofpr_enoffidx +
                             probe->dofpr_nenoffs < probe->dofpr_enoffidx ||
                             (probe->dofpr_enoffidx + probe->dofpr_nenoffs) *
                             enoff_sec->dofs_entsize > enoff_sec->dofs_size) {
                                 dtrace_dof_error(dof, "invalid is-enabled "
                                     "offset");
                                 return (-1);
                         }
 
                         if (probe->dofpr_noffs + probe->dofpr_nenoffs == 0) {
                                 dtrace_dof_error(dof, "zero probe and "
                                     "is-enabled offsets");
                                 return (-1);
                         }
                 } else if (probe->dofpr_noffs == 0) {
                         dtrace_dof_error(dof, "zero probe offsets");
                         return (-1);
                 }
 
                 if (probe->dofpr_argidx + probe->dofpr_xargc <
                     probe->dofpr_argidx ||
                     (probe->dofpr_argidx + probe->dofpr_xargc) *
                     arg_sec->dofs_entsize > arg_sec->dofs_size) {
                         dtrace_dof_error(dof, "invalid args");
                         return (-1);
                 }
 
                 typeidx = probe->dofpr_nargv;
                 typestr = strtab + probe->dofpr_nargv;
                 for (k = 0; k < probe->dofpr_nargc; k++) {
                         if (typeidx >= str_sec->dofs_size) {
                                 dtrace_dof_error(dof, "bad "
                                     "native argument type");
                                 return (-1);
                         }
 
                         typesz = strlen(typestr) + 1;
                         if (typesz > DTRACE_ARGTYPELEN) {
                                 dtrace_dof_error(dof, "native "
                                     "argument type too long");
                                 return (-1);
                         }
                         typeidx += typesz;
                         typestr += typesz;
                 }
 
                 typeidx = probe->dofpr_xargv;
                 typestr = strtab + probe->dofpr_xargv;
                 for (k = 0; k < probe->dofpr_xargc; k++) {
                         if (arg[probe->dofpr_argidx + k] > probe->dofpr_nargc) {
                                 dtrace_dof_error(dof, "bad "
                                     "native argument index");
                                 return (-1);
                         }
 
                         if (typeidx >= str_sec->dofs_size) {
                                 dtrace_dof_error(dof, "bad "
                                     "translated argument type");
                                 return (-1);
                         }
 
                         typesz = strlen(typestr) + 1;
                         if (typesz > DTRACE_ARGTYPELEN) {
                                 dtrace_dof_error(dof, "translated argument "
                                     "type too long");
                                 return (-1);
                         }
 
                         typeidx += typesz;
                         typestr += typesz;
                 }
         }
 
         return (0);
 }
 
 static int
 dtrace_helper_slurp(dof_hdr_t *dof, dof_helper_t *dhp, struct proc *p)
 {
         dtrace_helpers_t *help;
         dtrace_vstate_t *vstate;
         dtrace_enabling_t *enab = NULL;
         int i, gen, rv, nhelpers = 0, nprovs = 0, destroy = 1;
         uintptr_t daddr = (uintptr_t)dof;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
 
         if ((help = p->p_dtrace_helpers) == NULL)
                 help = dtrace_helpers_create(p);
 
         vstate = &help->dthps_vstate;
 
         if ((rv = dtrace_dof_slurp(dof, vstate, NULL, &enab, dhp->dofhp_addr,
             dhp->dofhp_dof, B_FALSE)) != 0) {
                 dtrace_dof_destroy(dof);
                 return (rv);
         }
 
         /*
          * Look for helper providers and validate their descriptions.
          */
         for (i = 0; i < dof->dofh_secnum; i++) {
                 dof_sec_t *sec = (dof_sec_t *)(uintptr_t)(daddr +
                     dof->dofh_secoff + i * dof->dofh_secsize);
 
                 if (sec->dofs_type != DOF_SECT_PROVIDER)
                         continue;
 
                 if (dtrace_helper_provider_validate(dof, sec) != 0) {
                         dtrace_enabling_destroy(enab);
                         dtrace_dof_destroy(dof);
                         return (-1);
                 }
 
                 nprovs++;
         }
 
         /*
          * Now we need to walk through the ECB descriptions in the enabling.
          */
         for (i = 0; i < enab->dten_ndesc; i++) {
                 dtrace_ecbdesc_t *ep = enab->dten_desc[i];
                 dtrace_probedesc_t *desc = &ep->dted_probe;
 
                 if (strcmp(desc->dtpd_provider, "dtrace") != 0)
                         continue;
 
                 if (strcmp(desc->dtpd_mod, "helper") != 0)
                         continue;
 
                 if (strcmp(desc->dtpd_func, "ustack") != 0)
                         continue;
 
                 if ((rv = dtrace_helper_action_add(DTRACE_HELPER_ACTION_USTACK,
                     ep, help)) != 0) {
                         /*
                          * Adding this helper action failed -- we are now going
                          * to rip out the entire generation and return failure.
                          */
                         (void) dtrace_helper_destroygen(help,
                             help->dthps_generation);
                         dtrace_enabling_destroy(enab);
                         dtrace_dof_destroy(dof);
                         return (-1);
                 }
 
                 nhelpers++;
         }
 
         if (nhelpers < enab->dten_ndesc)
                 dtrace_dof_error(dof, "unmatched helpers");
 
         gen = help->dthps_generation++;
         dtrace_enabling_destroy(enab);
 
         if (nprovs > 0) {
                 /*
                  * Now that this is in-kernel, we change the sense of the
                  * members:  dofhp_dof denotes the in-kernel copy of the DOF
                  * and dofhp_addr denotes the address at user-level.
                  */
                 dhp->dofhp_addr = dhp->dofhp_dof;
                 dhp->dofhp_dof = (uint64_t)(uintptr_t)dof;
 
                 if (dtrace_helper_provider_add(dhp, help, gen) == 0) {
                         mutex_exit(&dtrace_lock);
                         dtrace_helper_provider_register(p, help, dhp);
                         mutex_enter(&dtrace_lock);
 
                         destroy = 0;
                 }
         }
 
         if (destroy)
                 dtrace_dof_destroy(dof);
 
         return (gen);
 }
 
 static dtrace_helpers_t *
 dtrace_helpers_create(proc_t *p)
 {
         dtrace_helpers_t *help;
 
         ASSERT(MUTEX_HELD(&dtrace_lock));
         ASSERT(p->p_dtrace_helpers == NULL);
 
         help = kmem_zalloc(sizeof (dtrace_helpers_t), KM_SLEEP);
         help->dthps_actions = kmem_zalloc(sizeof (dtrace_helper_action_t *) *
             DTRACE_NHELPER_ACTIONS, KM_SLEEP);
 
         p->p_dtrace_helpers = help;
         dtrace_helpers++;
 
         return (help);
 }
 
 #ifdef illumos
 static
 #endif
 void
 dtrace_helpers_destroy(proc_t *p)
 {
         dtrace_helpers_t *help;
         dtrace_vstate_t *vstate;
 #ifdef illumos
         proc_t *p = curproc;
 #endif
         int i;
 
         mutex_enter(&dtrace_lock);
 
         ASSERT(p->p_dtrace_helpers != NULL);
         ASSERT(dtrace_helpers > 0);
 
         help = p->p_dtrace_helpers;
         vstate = &help->dthps_vstate;
 
         /*
          * We're now going to lose the help from this process.
          */
         p->p_dtrace_helpers = NULL;
         dtrace_sync();
 
         /*
          * Destory the helper actions.
          */
         for (i = 0; i < DTRACE_NHELPER_ACTIONS; i++) {
                 dtrace_helper_action_t *h, *next;
 
                 for (h = help->dthps_actions[i]; h != NULL; h = next) {
                         next = h->dtha_next;
                         dtrace_helper_action_destroy(h, vstate);
                         h = next;
                 }
         }
 
         mutex_exit(&dtrace_lock);
 
         /*
          * Destroy the helper providers.
          */
         if (help->dthps_maxprovs > 0) {
                 mutex_enter(&dtrace_meta_lock);
                 if (dtrace_meta_pid != NULL) {
                         ASSERT(dtrace_deferred_pid == NULL);
 
                         for (i = 0; i < help->dthps_nprovs; i++) {
                                 dtrace_helper_provider_remove(
                                     &help->dthps_provs[i]->dthp_prov, p->p_pid);
                         }
                 } else {
                         mutex_enter(&dtrace_lock);
                         ASSERT(help->dthps_deferred == 0 ||
                             help->dthps_next != NULL ||
                             help->dthps_prev != NULL ||
                             help == dtrace_deferred_pid);
 
                         /*
                          * Remove the helper from the deferred list.
                          */
                         if (help->dthps_next != NULL)
                                 help->dthps_next->dthps_prev = help->dthps_prev;
                         if (help->dthps_prev != NULL)
                                 help->dthps_prev->dthps_next = help->dthps_next;
                         if (dtrace_deferred_pid == help) {
                                 dtrace_deferred_pid = help->dthps_next;
                                 ASSERT(help->dthps_prev == NULL);
                         }
 
                         mutex_exit(&dtrace_lock);
                 }
 
                 mutex_exit(&dtrace_meta_lock);
 
                 for (i = 0; i < help->dthps_nprovs; i++) {
                         dtrace_helper_provider_destroy(help->dthps_provs[i]);
                 }
 
                 kmem_free(help->dthps_provs, help->dthps_maxprovs *
                     sizeof (dtrace_helper_provider_t *));
         }
 
         mutex_enter(&dtrace_lock);
 
         dtrace_vstate_fini(&help->dthps_vstate);
         kmem_free(help->dthps_actions,
             sizeof (dtrace_helper_action_t *) * DTRACE_NHELPER_ACTIONS);
         kmem_free(help, sizeof (dtrace_helpers_t));
 
         --dtrace_helpers;
         mutex_exit(&dtrace_lock);
 }
 
 #ifdef illumos
 static
 #endif
 void
 dtrace_helpers_duplicate(proc_t *from, proc_t *to)
 {
         dtrace_helpers_t *help, *newhelp;
         dtrace_helper_action_t *helper, *new, *last;
         dtrace_difo_t *dp;
         dtrace_vstate_t *vstate;
         int i, j, sz, hasprovs = 0;
 
         mutex_enter(&dtrace_lock);
         ASSERT(from->p_dtrace_helpers != NULL);
         ASSERT(dtrace_helpers > 0);
 
         help = from->p_dtrace_helpers;
         newhelp = dtrace_helpers_create(to);
         ASSERT(to->p_dtrace_helpers != NULL);
 
         newhelp->dthps_generation = help->dthps_generation;
         vstate = &newhelp->dthps_vstate;
 
         /*
          * Duplicate the helper actions.
          */
         for (i = 0; i < DTRACE_NHELPER_ACTIONS; i++) {
                 if ((helper = help->dthps_actions[i]) == NULL)
                         continue;
 
                 for (last = NULL; helper != NULL; helper = helper->dtha_next) {
                         new = kmem_zalloc(sizeof (dtrace_helper_action_t),
                             KM_SLEEP);
                         new->dtha_generation = helper->dtha_generation;
 
                         if ((dp = helper->dtha_predicate) != NULL) {
                                 dp = dtrace_difo_duplicate(dp, vstate);
                                 new->dtha_predicate = dp;
                         }
 
                         new->dtha_nactions = helper->dtha_nactions;
                         sz = sizeof (dtrace_difo_t *) * new->dtha_nactions;
                         new->dtha_actions = kmem_alloc(sz, KM_SLEEP);
 
                         for (j = 0; j < new->dtha_nactions; j++) {
                                 dtrace_difo_t *dp = helper->dtha_actions[j];
 
                                 ASSERT(dp != NULL);
                                 dp = dtrace_difo_duplicate(dp, vstate);
                                 new->dtha_actions[j] = dp;
                         }
 
                         if (last != NULL) {
                                 last->dtha_next = new;
                         } else {
                                 newhelp->dthps_actions[i] = new;
                         }
 
                         last = new;
                 }
         }
 
         /*
          * Duplicate the helper providers and register them with the
          * DTrace framework.
          */
         if (help->dthps_nprovs > 0) {
                 newhelp->dthps_nprovs = help->dthps_nprovs;
                 newhelp->dthps_maxprovs = help->dthps_nprovs;
                 newhelp->dthps_provs = kmem_alloc(newhelp->dthps_nprovs *
                     sizeof (dtrace_helper_provider_t *), KM_SLEEP);
                 for (i = 0; i < newhelp->dthps_nprovs; i++) {
                         newhelp->dthps_provs[i] = help->dthps_provs[i];
                         newhelp->dthps_provs[i]->dthp_ref++;
                 }
 
                 hasprovs = 1;
         }
 
         mutex_exit(&dtrace_lock);
 
         if (hasprovs)
                 dtrace_helper_provider_register(to, newhelp, NULL);
 }
 
 /*
  * DTrace Hook Functions
  */
 static void
 dtrace_module_loaded(modctl_t *ctl)
 {
         dtrace_provider_t *prv;
 
         mutex_enter(&dtrace_provider_lock);
 #ifdef illumos
         mutex_enter(&mod_lock);
 #endif
 
 #ifdef illumos
         ASSERT(ctl->mod_busy);
 #endif
 
         /*
          * We're going to call each providers per-module provide operation
          * specifying only this module.
          */
         for (prv = dtrace_provider; prv != NULL; prv = prv->dtpv_next)
                 prv->dtpv_pops.dtps_provide_module(prv->dtpv_arg, ctl);
 
 #ifdef illumos
         mutex_exit(&mod_lock);
 #endif
         mutex_exit(&dtrace_provider_lock);
 
         /*
          * If we have any retained enablings, we need to match against them.
          * Enabling probes requires that cpu_lock be held, and we cannot hold
          * cpu_lock here -- it is legal for cpu_lock to be held when loading a
          * module.  (In particular, this happens when loading scheduling
          * classes.)  So if we have any retained enablings, we need to dispatch
          * our task queue to do the match for us.
          */
         mutex_enter(&dtrace_lock);
 
         if (dtrace_retained == NULL) {
                 mutex_exit(&dtrace_lock);
                 return;
         }
 
         (void) taskq_dispatch(dtrace_taskq,
             (task_func_t *)dtrace_enabling_matchall, NULL, TQ_SLEEP);
 
         mutex_exit(&dtrace_lock);
 
         /*
          * And now, for a little heuristic sleaze:  in general, we want to
          * match modules as soon as they load.  However, we cannot guarantee
          * this, because it would lead us to the lock ordering violation
          * outlined above.  The common case, of course, is that cpu_lock is
          * _not_ held -- so we delay here for a clock tick, hoping that that's
          * long enough for the task queue to do its work.  If it's not, it's
          * not a serious problem -- it just means that the module that we
          * just loaded may not be immediately instrumentable.
          */
         delay(1);
 }
 
 static void
 #ifdef illumos
 dtrace_module_unloaded(modctl_t *ctl)
 #else
 dtrace_module_unloaded(modctl_t *ctl, int *error)
 #endif
 {
         dtrace_probe_t template, *probe, *first, *next;
         dtrace_provider_t *prov;
 #ifndef illumos
         char modname[DTRACE_MODNAMELEN];
         size_t len;
 #endif
 
 #ifdef illumos
         template.dtpr_mod = ctl->mod_modname;
 #else
         /* Handle the fact that ctl->filename may end in ".ko". */
         strlcpy(modname, ctl->filename, sizeof(modname));
         len = strlen(ctl->filename);
         if (len > 3 && strcmp(modname + len - 3, ".ko") == 0)
                 modname[len - 3] = '\0';
         template.dtpr_mod = modname;
 #endif
 
         mutex_enter(&dtrace_provider_lock);
 #ifdef illumos
         mutex_enter(&mod_lock);
 #endif
         mutex_enter(&dtrace_lock);
 
 #ifndef illumos
         if (ctl->nenabled > 0) {
                 /* Don't allow unloads if a probe is enabled. */
                 mutex_exit(&dtrace_provider_lock);
                 mutex_exit(&dtrace_lock);
                 *error = -1;
                 printf(
         "kldunload: attempt to unload module that has DTrace probes enabled\n");
                 return;
         }
 #endif
 
         if (dtrace_bymod == NULL) {
                 /*
                  * The DTrace module is loaded (obviously) but not attached;
                  * we don't have any work to do.
                  */
                 mutex_exit(&dtrace_provider_lock);
 #ifdef illumos
                 mutex_exit(&mod_lock);
 #endif
                 mutex_exit(&dtrace_lock);
                 return;
         }
 
         for (probe = first = dtrace_hash_lookup(dtrace_bymod, &template);
             probe != NULL; probe = probe->dtpr_nextmod) {
                 if (probe->dtpr_ecb != NULL) {
                         mutex_exit(&dtrace_provider_lock);
 #ifdef illumos
                         mutex_exit(&mod_lock);
 #endif
                         mutex_exit(&dtrace_lock);
 
                         /*
                          * This shouldn't _actually_ be possible -- we're
                          * unloading a module that has an enabled probe in it.
                          * (It's normally up to the provider to make sure that
                          * this can't happen.)  However, because dtps_enable()
                          * doesn't have a failure mode, there can be an
                          * enable/unload race.  Upshot:  we don't want to
                          * assert, but we're not going to disable the
                          * probe, either.
                          */
                         if (dtrace_err_verbose) {
 #ifdef illumos
                                 cmn_err(CE_WARN, "unloaded module '%s' had "
                                     "enabled probes", ctl->mod_modname);
 #else
                                 cmn_err(CE_WARN, "unloaded module '%s' had "
                                     "enabled probes", modname);
 #endif
                         }
 
                         return;
                 }
         }
 
         probe = first;
 
         for (first = NULL; probe != NULL; probe = next) {
                 ASSERT(dtrace_probes[probe->dtpr_id - 1] == probe);
 
                 dtrace_probes[probe->dtpr_id - 1] = NULL;
 
                 next = probe->dtpr_nextmod;
                 dtrace_hash_remove(dtrace_bymod, probe);
                 dtrace_hash_remove(dtrace_byfunc, probe);
                 dtrace_hash_remove(dtrace_byname, probe);
 
                 if (first == NULL) {
                         first = probe;
                         probe->dtpr_nextmod = NULL;
                 } else {
                         probe->dtpr_nextmod = first;
                         first = probe;
                 }
         }
 
         /*
          * We've removed all of the module's probes from the hash chains and
          * from the probe array.  Now issue a dtrace_sync() to be sure that
          * everyone has cleared out from any probe array processing.
          */
         dtrace_sync();
 
         for (probe = first; probe != NULL; probe = first) {
                 first = probe->dtpr_nextmod;
                 prov = probe->dtpr_provider;
                 prov->dtpv_pops.dtps_destroy(prov->dtpv_arg, probe->dtpr_id,
                     probe->dtpr_arg);
                 kmem_free(probe->dtpr_mod, strlen(probe->dtpr_mod) + 1);
                 kmem_free(probe->dtpr_func, strlen(probe->dtpr_func) + 1);
                 kmem_free(probe->dtpr_name, strlen(probe->dtpr_name) + 1);
 #ifdef illumos
                 vmem_free(dtrace_arena, (void *)(uintptr_t)probe->dtpr_id, 1);
 #else
                 free_unr(dtrace_arena, probe->dtpr_id);
 #endif
                 kmem_free(probe, sizeof (dtrace_probe_t));
         }
 
         mutex_exit(&dtrace_lock);
 #ifdef illumos
         mutex_exit(&mod_lock);
 #endif
         mutex_exit(&dtrace_provider_lock);
 }
 
 #ifndef illumos
 static void
 dtrace_kld_load(void *arg __unused, linker_file_t lf)
 {
 
         dtrace_module_loaded(lf);
 }
 
 static void
 dtrace_kld_unload_try(void *arg __unused, linker_file_t lf, int *error)
 {
 
         if (*error != 0)
                 /* We already have an error, so don't do anything. */
                 return;
         dtrace_module_unloaded(lf, error);
 }
 #endif
 
 #ifdef illumos
 static void
 dtrace_suspend(void)
 {
         dtrace_probe_foreach(offsetof(dtrace_pops_t, dtps_suspend));
 }
 
 static void
 dtrace_resume(void)
 {
         dtrace_probe_foreach(offsetof(dtrace_pops_t, dtps_resume));
 }
 #endif
 
 static int
 dtrace_cpu_setup(cpu_setup_t what, processorid_t cpu)
 {
         ASSERT(MUTEX_HELD(&cpu_lock));
         mutex_enter(&dtrace_lock);
 
         switch (what) {
         case CPU_CONFIG: {
                 dtrace_state_t *state;
                 dtrace_optval_t *opt, rs, c;
 
                 /*
                  * For now, we only allocate a new buffer for anonymous state.
                  */
                 if ((state = dtrace_anon.dta_state) == NULL)
                         break;
 
                 if (state->dts_activity != DTRACE_ACTIVITY_ACTIVE)
                         break;
 
                 opt = state->dts_options;
                 c = opt[DTRACEOPT_CPU];
 
                 if (c != DTRACE_CPUALL && c != DTRACEOPT_UNSET && c != cpu)
                         break;
 
                 /*
                  * Regardless of what the actual policy is, we're going to
                  * temporarily set our resize policy to be manual.  We're
                  * also going to temporarily set our CPU option to denote
                  * the newly configured CPU.
                  */
                 rs = opt[DTRACEOPT_BUFRESIZE];
                 opt[DTRACEOPT_BUFRESIZE] = DTRACEOPT_BUFRESIZE_MANUAL;
                 opt[DTRACEOPT_CPU] = (dtrace_optval_t)cpu;
 
                 (void) dtrace_state_buffers(state);
 
                 opt[DTRACEOPT_BUFRESIZE] = rs;
                 opt[DTRACEOPT_CPU] = c;
 
                 break;
         }
 
         case CPU_UNCONFIG:
                 /*
                  * We don't free the buffer in the CPU_UNCONFIG case.  (The
                  * buffer will be freed when the consumer exits.)
                  */
                 break;
 
         default:
                 break;
         }
 
         mutex_exit(&dtrace_lock);
         return (0);
 }
 
 #ifdef illumos
 static void
 dtrace_cpu_setup_initial(processorid_t cpu)
 {
         (void) dtrace_cpu_setup(CPU_CONFIG, cpu);
 }
 #endif
 
 static void
 dtrace_toxrange_add(uintptr_t base, uintptr_t limit)
 {
         if (dtrace_toxranges >= dtrace_toxranges_max) {
                 int osize, nsize;
                 dtrace_toxrange_t *range;
 
                 osize = dtrace_toxranges_max * sizeof (dtrace_toxrange_t);
 
                 if (osize == 0) {
                         ASSERT(dtrace_toxrange == NULL);
                         ASSERT(dtrace_toxranges_max == 0);
                         dtrace_toxranges_max = 1;
                 } else {
                         dtrace_toxranges_max <<= 1;
                 }
 
                 nsize = dtrace_toxranges_max * sizeof (dtrace_toxrange_t);
                 range = kmem_zalloc(nsize, KM_SLEEP);
 
                 if (dtrace_toxrange != NULL) {
                         ASSERT(osize != 0);
                         bcopy(dtrace_toxrange, range, osize);
                         kmem_free(dtrace_toxrange, osize);
                 }
 
                 dtrace_toxrange = range;
         }
 
         ASSERT(dtrace_toxrange[dtrace_toxranges].dtt_base == 0);
         ASSERT(dtrace_toxrange[dtrace_toxranges].dtt_limit == 0);
 
         dtrace_toxrange[dtrace_toxranges].dtt_base = base;
         dtrace_toxrange[dtrace_toxranges].dtt_limit = limit;
         dtrace_toxranges++;
 }
 
 static void
 dtrace_getf_barrier(void)
 {
 #ifdef illumos
         /*
          * When we have unprivileged (that is, non-DTRACE_CRV_KERNEL) enablings
          * that contain calls to getf(), this routine will be called on every
          * closef() before either the underlying vnode is released or the
          * file_t itself is freed.  By the time we are here, it is essential
          * that the file_t can no longer be accessed from a call to getf()
          * in probe context -- that assures that a dtrace_sync() can be used
          * to clear out any enablings referring to the old structures.
          */
         if (curthread->t_procp->p_zone->zone_dtrace_getf != 0 ||
             kcred->cr_zone->zone_dtrace_getf != 0)
                 dtrace_sync();
 #endif
 }
 
 /*
  * DTrace Driver Cookbook Functions
  */
 #ifdef illumos
 /*ARGSUSED*/
 static int
 dtrace_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
 {
         dtrace_provider_id_t id;
         dtrace_state_t *state = NULL;
         dtrace_enabling_t *enab;
 
         mutex_enter(&cpu_lock);
         mutex_enter(&dtrace_provider_lock);
         mutex_enter(&dtrace_lock);
 
         if (ddi_soft_state_init(&dtrace_softstate,
             sizeof (dtrace_state_t), 0) != 0) {
                 cmn_err(CE_NOTE, "/dev/dtrace failed to initialize soft state");
                 mutex_exit(&cpu_lock);
                 mutex_exit(&dtrace_provider_lock);
                 mutex_exit(&dtrace_lock);
                 return (DDI_FAILURE);
         }
 
         if (ddi_create_minor_node(devi, DTRACEMNR_DTRACE, S_IFCHR,
             DTRACEMNRN_DTRACE, DDI_PSEUDO, NULL) == DDI_FAILURE ||
             ddi_create_minor_node(devi, DTRACEMNR_HELPER, S_IFCHR,
             DTRACEMNRN_HELPER, DDI_PSEUDO, NULL) == DDI_FAILURE) {
                 cmn_err(CE_NOTE, "/dev/dtrace couldn't create minor nodes");
                 ddi_remove_minor_node(devi, NULL);
                 ddi_soft_state_fini(&dtrace_softstate);
                 mutex_exit(&cpu_lock);
                 mutex_exit(&dtrace_provider_lock);
                 mutex_exit(&dtrace_lock);
                 return (DDI_FAILURE);
         }
 
         ddi_report_dev(devi);
         dtrace_devi = devi;
 
         dtrace_modload = dtrace_module_loaded;
         dtrace_modunload = dtrace_module_unloaded;
         dtrace_cpu_init = dtrace_cpu_setup_initial;
         dtrace_helpers_cleanup = dtrace_helpers_destroy;
         dtrace_helpers_fork = dtrace_helpers_duplicate;
         dtrace_cpustart_init = dtrace_suspend;
         dtrace_cpustart_fini = dtrace_resume;
         dtrace_debugger_init = dtrace_suspend;
         dtrace_debugger_fini = dtrace_resume;
 
         register_cpu_setup_func((cpu_setup_func_t *)dtrace_cpu_setup, NULL);
 
         ASSERT(MUTEX_HELD(&cpu_lock));
 
         dtrace_arena = vmem_create("dtrace", (void *)1, UINT32_MAX, 1,
             NULL, NULL, NULL, 0, VM_SLEEP | VMC_IDENTIFIER);
         dtrace_minor = vmem_create("dtrace_minor", (void *)DTRACEMNRN_CLONE,
             UINT32_MAX - DTRACEMNRN_CLONE, 1, NULL, NULL, NULL, 0,
             VM_SLEEP | VMC_IDENTIFIER);
         dtrace_taskq = taskq_create("dtrace_taskq", 1, maxclsyspri,
             1, INT_MAX, 0);
 
         dtrace_state_cache = kmem_cache_create("dtrace_state_cache",
             sizeof (dtrace_dstate_percpu_t) * NCPU, DTRACE_STATE_ALIGN,
             NULL, NULL, NULL, NULL, NULL, 0);
 
         ASSERT(MUTEX_HELD(&cpu_lock));
         dtrace_bymod = dtrace_hash_create(offsetof(dtrace_probe_t, dtpr_mod),
             offsetof(dtrace_probe_t, dtpr_nextmod),
             offsetof(dtrace_probe_t, dtpr_prevmod));
 
         dtrace_byfunc = dtrace_hash_create(offsetof(dtrace_probe_t, dtpr_func),
             offsetof(dtrace_probe_t, dtpr_nextfunc),
             offsetof(dtrace_probe_t, dtpr_prevfunc));
 
         dtrace_byname = dtrace_hash_create(offsetof(dtrace_probe_t, dtpr_name),
             offsetof(dtrace_probe_t, dtpr_nextname),
             offsetof(dtrace_probe_t, dtpr_prevname));
 
         if (dtrace_retain_max < 1) {
                 cmn_err(CE_WARN, "illegal value (%zu) for dtrace_retain_max; "
                     "setting to 1", dtrace_retain_max);
                 dtrace_retain_max = 1;
         }
 
         /*
          * Now discover our toxic ranges.
          */
         dtrace_toxic_ranges(dtrace_toxrange_add);
 
         /*
          * Before we register ourselves as a provider to our own framework,
          * we would like to assert that dtrace_provider is NULL -- but that's
          * not true if we were loaded as a dependency of a DTrace provider.
          * Once we've registered, we can assert that dtrace_provider is our
          * pseudo provider.
          */
         (void) dtrace_register("dtrace", &dtrace_provider_attr,
             DTRACE_PRIV_NONE, 0, &dtrace_provider_ops, NULL, &id);
 
         ASSERT(dtrace_provider != NULL);
         ASSERT((dtrace_provider_id_t)dtrace_provider == id);
 
         dtrace_probeid_begin = dtrace_probe_create((dtrace_provider_id_t)
             dtrace_provider, NULL, NULL, "BEGIN", 0, NULL);
         dtrace_probeid_end = dtrace_probe_create((dtrace_provider_id_t)
             dtrace_provider, NULL, NULL, "END", 0, NULL);
         dtrace_probeid_error = dtrace_probe_create((dtrace_provider_id_t)
             dtrace_provider, NULL, NULL, "ERROR", 1, NULL);
 
         dtrace_anon_property();
         mutex_exit(&cpu_lock);
 
         /*
          * If there are already providers, we must ask them to provide their
          * probes, and then match any anonymous enabling against them.  Note
          * that there should be no other retained enablings at this time:
          * the only retained enablings at this time should be the anonymous
          * enabling.
          */
         if (dtrace_anon.dta_enabling != NULL) {
                 ASSERT(dtrace_retained == dtrace_anon.dta_enabling);
 
                 dtrace_enabling_provide(NULL);
                 state = dtrace_anon.dta_state;
 
                 /*
                  * We couldn't hold cpu_lock across the above call to
                  * dtrace_enabling_provide(), but we must hold it to actually
                  * enable the probes.  We have to drop all of our locks, pick
                  * up cpu_lock, and regain our locks before matching the
                  * retained anonymous enabling.
                  */
                 mutex_exit(&dtrace_lock);
                 mutex_exit(&dtrace_provider_lock);
 
                 mutex_enter(&cpu_lock);
                 mutex_enter(&dtrace_provider_lock);
                 mutex_enter(&dtrace_lock);
 
                 if ((enab = dtrace_anon.dta_enabling) != NULL)
                         (void) dtrace_enabling_match(enab, NULL);
 
                 mutex_exit(&cpu_lock);
         }
 
         mutex_exit(&dtrace_lock);
         mutex_exit(&dtrace_provider_lock);
 
         if (state != NULL) {
                 /*
                  * If we created any anonymous state, set it going now.
                  */
                 (void) dtrace_state_go(state, &dtrace_anon.dta_beganon);
         }
 
         return (DDI_SUCCESS);
 }
 #endif  /* illumos */
 
 #ifndef illumos
 static void dtrace_dtr(void *);
 #endif
 
 /*ARGSUSED*/
 static int
 #ifdef illumos
 dtrace_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
 #else
 dtrace_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
 #endif
 {
         dtrace_state_t *state;
         uint32_t priv;
         uid_t uid;
         zoneid_t zoneid;
 
 #ifdef illumos
         if (getminor(*devp) == DTRACEMNRN_HELPER)
                 return (0);
 
         /*
          * If this wasn't an open with the "helper" minor, then it must be
          * the "dtrace" minor.
          */
         if (getminor(*devp) == DTRACEMNRN_DTRACE)
                 return (ENXIO);
 #else
         cred_t *cred_p = NULL;
         cred_p = dev->si_cred;
 
         /*
          * If no DTRACE_PRIV_* bits are set in the credential, then the
          * caller lacks sufficient permission to do anything with DTrace.
          */
         dtrace_cred2priv(cred_p, &priv, &uid, &zoneid);
         if (priv == DTRACE_PRIV_NONE) {
 #endif
 
                 return (EACCES);
         }
 
         /*
          * Ask all providers to provide all their probes.
          */
         mutex_enter(&dtrace_provider_lock);
         dtrace_probe_provide(NULL, NULL);
         mutex_exit(&dtrace_provider_lock);
 
         mutex_enter(&cpu_lock);
         mutex_enter(&dtrace_lock);
         dtrace_opens++;
         dtrace_membar_producer();
 
 #ifdef illumos
         /*
          * If the kernel debugger is active (that is, if the kernel debugger
          * modified text in some way), we won't allow the open.
          */
         if (kdi_dtrace_set(KDI_DTSET_DTRACE_ACTIVATE) != 0) {
                 dtrace_opens--;
                 mutex_exit(&cpu_lock);
                 mutex_exit(&dtrace_lock);
                 return (EBUSY);
         }
 
         if (dtrace_helptrace_enable && dtrace_helptrace_buffer == NULL) {
                 /*
                  * If DTrace helper tracing is enabled, we need to allocate the
                  * trace buffer and initialize the values.
                  */
                 dtrace_helptrace_buffer =
                     kmem_zalloc(dtrace_helptrace_bufsize, KM_SLEEP);
                 dtrace_helptrace_next = 0;
                 dtrace_helptrace_wrapped = 0;
                 dtrace_helptrace_enable = 0;
         }
 
         state = dtrace_state_create(devp, cred_p);
 #else
         state = dtrace_state_create(dev, NULL);
         devfs_set_cdevpriv(state, dtrace_dtr);
 #endif
 
         mutex_exit(&cpu_lock);
 
         if (state == NULL) {
 #ifdef illumos
                 if (--dtrace_opens == 0 && dtrace_anon.dta_enabling == NULL)
                         (void) kdi_dtrace_set(KDI_DTSET_DTRACE_DEACTIVATE);
 #else
                 --dtrace_opens;
 #endif
                 mutex_exit(&dtrace_lock);
                 return (EAGAIN);
         }
 
         mutex_exit(&dtrace_lock);
 
         return (0);
 }
 
 /*ARGSUSED*/
 #ifdef illumos
 static int
 dtrace_close(dev_t dev, int flag, int otyp, cred_t *cred_p)
 #else
 static void
 dtrace_dtr(void *data)
 #endif
 {
 #ifdef illumos
         minor_t minor = getminor(dev);
         dtrace_state_t *state;
 #endif
         dtrace_helptrace_t *buf = NULL;
 
 #ifdef illumos
         if (minor == DTRACEMNRN_HELPER)
                 return (0);
 
         state = ddi_get_soft_state(dtrace_softstate, minor);
 #else
         dtrace_state_t *state = data;
 #endif
 
         mutex_enter(&cpu_lock);
         mutex_enter(&dtrace_lock);
 
 #ifdef illumos
         if (state->dts_anon)
 #else
         if (state != NULL && state->dts_anon)
 #endif
         {
                 /*
                  * There is anonymous state. Destroy that first.
                  */
                 ASSERT(dtrace_anon.dta_state == NULL);
                 dtrace_state_destroy(state->dts_anon);
         }
 
         if (dtrace_helptrace_disable) {
                 /*
                  * If we have been told to disable helper tracing, set the
                  * buffer to NULL before calling into dtrace_state_destroy();
                  * we take advantage of its dtrace_sync() to know that no
                  * CPU is in probe context with enabled helper tracing
                  * after it returns.
                  */
                 buf = dtrace_helptrace_buffer;
                 dtrace_helptrace_buffer = NULL;
         }
 
 #ifdef illumos
         dtrace_state_destroy(state);
 #else
         if (state != NULL) {
                 dtrace_state_destroy(state);
                 kmem_free(state, 0);
         }
 #endif
         ASSERT(dtrace_opens > 0);
 
 #ifdef illumos
         /*
          * Only relinquish control of the kernel debugger interface when there
          * are no consumers and no anonymous enablings.
          */
         if (--dtrace_opens == 0 && dtrace_anon.dta_enabling == NULL)
                 (void) kdi_dtrace_set(KDI_DTSET_DTRACE_DEACTIVATE);
 #else
         --dtrace_opens;
 #endif
 
         if (buf != NULL) {
                 kmem_free(buf, dtrace_helptrace_bufsize);
                 dtrace_helptrace_disable = 0;
         }
 
         mutex_exit(&dtrace_lock);
         mutex_exit(&cpu_lock);
 
 #ifdef illumos
         return (0);
 #endif
 }
 
 #ifdef illumos
 /*ARGSUSED*/
 static int
 dtrace_ioctl_helper(int cmd, intptr_t arg, int *rv)
 {
         int rval;
         dof_helper_t help, *dhp = NULL;
 
         switch (cmd) {
         case DTRACEHIOC_ADDDOF:
                 if (copyin((void *)arg, &help, sizeof (help)) != 0) {
                         dtrace_dof_error(NULL, "failed to copyin DOF helper");
                         return (EFAULT);
                 }
 
                 dhp = &help;
                 arg = (intptr_t)help.dofhp_dof;
                 /*FALLTHROUGH*/
 
         case DTRACEHIOC_ADD: {
                 dof_hdr_t *dof = dtrace_dof_copyin(arg, &rval);
 
                 if (dof == NULL)
                         return (rval);
 
                 mutex_enter(&dtrace_lock);
 
                 /*
                  * dtrace_helper_slurp() takes responsibility for the dof --
                  * it may free it now or it may save it and free it later.
                  */
                 if ((rval = dtrace_helper_slurp(dof, dhp)) != -1) {
                         *rv = rval;
                         rval = 0;
                 } else {
                         rval = EINVAL;
                 }
 
                 mutex_exit(&dtrace_lock);
                 return (rval);
         }
 
         case DTRACEHIOC_REMOVE: {
                 mutex_enter(&dtrace_lock);
                 rval = dtrace_helper_destroygen(NULL, arg);
                 mutex_exit(&dtrace_lock);
 
                 return (rval);
         }
 
         default:
                 break;
         }
 
         return (ENOTTY);
 }
 
 /*ARGSUSED*/
 static int
 dtrace_ioctl(dev_t dev, int cmd, intptr_t arg, int md, cred_t *cr, int *rv)
 {
         minor_t minor = getminor(dev);
         dtrace_state_t *state;
         int rval;
 
         if (minor == DTRACEMNRN_HELPER)
                 return (dtrace_ioctl_helper(cmd, arg, rv));
 
         state = ddi_get_soft_state(dtrace_softstate, minor);
 
         if (state->dts_anon) {
                 ASSERT(dtrace_anon.dta_state == NULL);
                 state = state->dts_anon;
         }
 
         switch (cmd) {
         case DTRACEIOC_PROVIDER: {
                 dtrace_providerdesc_t pvd;
                 dtrace_provider_t *pvp;
 
                 if (copyin((void *)arg, &pvd, sizeof (pvd)) != 0)
                         return (EFAULT);
 
                 pvd.dtvd_name[DTRACE_PROVNAMELEN - 1] = '\0';
                 mutex_enter(&dtrace_provider_lock);
 
                 for (pvp = dtrace_provider; pvp != NULL; pvp = pvp->dtpv_next) {
                         if (strcmp(pvp->dtpv_name, pvd.dtvd_name) == 0)
                                 break;
                 }
 
                 mutex_exit(&dtrace_provider_lock);
 
                 if (pvp == NULL)
                         return (ESRCH);
 
                 bcopy(&pvp->dtpv_priv, &pvd.dtvd_priv, sizeof (dtrace_ppriv_t));
                 bcopy(&pvp->dtpv_attr, &pvd.dtvd_attr, sizeof (dtrace_pattr_t));
 
                 if (copyout(&pvd, (void *)arg, sizeof (pvd)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_EPROBE: {
                 dtrace_eprobedesc_t epdesc;
                 dtrace_ecb_t *ecb;
                 dtrace_action_t *act;
                 void *buf;
                 size_t size;
                 uintptr_t dest;
                 int nrecs;
 
                 if (copyin((void *)arg, &epdesc, sizeof (epdesc)) != 0)
                         return (EFAULT);
 
                 mutex_enter(&dtrace_lock);
 
                 if ((ecb = dtrace_epid2ecb(state, epdesc.dtepd_epid)) == NULL) {
                         mutex_exit(&dtrace_lock);
                         return (EINVAL);
                 }
 
                 if (ecb->dte_probe == NULL) {
                         mutex_exit(&dtrace_lock);
                         return (EINVAL);
                 }
 
                 epdesc.dtepd_probeid = ecb->dte_probe->dtpr_id;
                 epdesc.dtepd_uarg = ecb->dte_uarg;
                 epdesc.dtepd_size = ecb->dte_size;
 
                 nrecs = epdesc.dtepd_nrecs;
                 epdesc.dtepd_nrecs = 0;
                 for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                         if (DTRACEACT_ISAGG(act->dta_kind) || act->dta_intuple)
                                 continue;
 
                         epdesc.dtepd_nrecs++;
                 }
 
                 /*
                  * Now that we have the size, we need to allocate a temporary
                  * buffer in which to store the complete description.  We need
                  * the temporary buffer to be able to drop dtrace_lock()
                  * across the copyout(), below.
                  */
                 size = sizeof (dtrace_eprobedesc_t) +
                     (epdesc.dtepd_nrecs * sizeof (dtrace_recdesc_t));
 
                 buf = kmem_alloc(size, KM_SLEEP);
                 dest = (uintptr_t)buf;
 
                 bcopy(&epdesc, (void *)dest, sizeof (epdesc));
                 dest += offsetof(dtrace_eprobedesc_t, dtepd_rec[0]);
 
                 for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                         if (DTRACEACT_ISAGG(act->dta_kind) || act->dta_intuple)
                                 continue;
 
                         if (nrecs-- == 0)
                                 break;
 
                         bcopy(&act->dta_rec, (void *)dest,
                             sizeof (dtrace_recdesc_t));
                         dest += sizeof (dtrace_recdesc_t);
                 }
 
                 mutex_exit(&dtrace_lock);
 
                 if (copyout(buf, (void *)arg, dest - (uintptr_t)buf) != 0) {
                         kmem_free(buf, size);
                         return (EFAULT);
                 }
 
                 kmem_free(buf, size);
                 return (0);
         }
 
         case DTRACEIOC_AGGDESC: {
                 dtrace_aggdesc_t aggdesc;
                 dtrace_action_t *act;
                 dtrace_aggregation_t *agg;
                 int nrecs;
                 uint32_t offs;
                 dtrace_recdesc_t *lrec;
                 void *buf;
                 size_t size;
                 uintptr_t dest;
 
                 if (copyin((void *)arg, &aggdesc, sizeof (aggdesc)) != 0)
                         return (EFAULT);
 
                 mutex_enter(&dtrace_lock);
 
                 if ((agg = dtrace_aggid2agg(state, aggdesc.dtagd_id)) == NULL) {
                         mutex_exit(&dtrace_lock);
                         return (EINVAL);
                 }
 
                 aggdesc.dtagd_epid = agg->dtag_ecb->dte_epid;
 
                 nrecs = aggdesc.dtagd_nrecs;
                 aggdesc.dtagd_nrecs = 0;
 
                 offs = agg->dtag_base;
                 lrec = &agg->dtag_action.dta_rec;
                 aggdesc.dtagd_size = lrec->dtrd_offset + lrec->dtrd_size - offs;
 
                 for (act = agg->dtag_first; ; act = act->dta_next) {
                         ASSERT(act->dta_intuple ||
                             DTRACEACT_ISAGG(act->dta_kind));
 
                         /*
                          * If this action has a record size of zero, it
                          * denotes an argument to the aggregating action.
                          * Because the presence of this record doesn't (or
                          * shouldn't) affect the way the data is interpreted,
                          * we don't copy it out to save user-level the
                          * confusion of dealing with a zero-length record.
                          */
                         if (act->dta_rec.dtrd_size == 0) {
                                 ASSERT(agg->dtag_hasarg);
                                 continue;
                         }
 
                         aggdesc.dtagd_nrecs++;
 
                         if (act == &agg->dtag_action)
                                 break;
                 }
 
                 /*
                  * Now that we have the size, we need to allocate a temporary
                  * buffer in which to store the complete description.  We need
                  * the temporary buffer to be able to drop dtrace_lock()
                  * across the copyout(), below.
                  */
                 size = sizeof (dtrace_aggdesc_t) +
                     (aggdesc.dtagd_nrecs * sizeof (dtrace_recdesc_t));
 
                 buf = kmem_alloc(size, KM_SLEEP);
                 dest = (uintptr_t)buf;
 
                 bcopy(&aggdesc, (void *)dest, sizeof (aggdesc));
                 dest += offsetof(dtrace_aggdesc_t, dtagd_rec[0]);
 
                 for (act = agg->dtag_first; ; act = act->dta_next) {
                         dtrace_recdesc_t rec = act->dta_rec;
 
                         /*
                          * See the comment in the above loop for why we pass
                          * over zero-length records.
                          */
                         if (rec.dtrd_size == 0) {
                                 ASSERT(agg->dtag_hasarg);
                                 continue;
                         }
 
                         if (nrecs-- == 0)
                                 break;
 
                         rec.dtrd_offset -= offs;
                         bcopy(&rec, (void *)dest, sizeof (rec));
                         dest += sizeof (dtrace_recdesc_t);
 
                         if (act == &agg->dtag_action)
                                 break;
                 }
 
                 mutex_exit(&dtrace_lock);
 
                 if (copyout(buf, (void *)arg, dest - (uintptr_t)buf) != 0) {
                         kmem_free(buf, size);
                         return (EFAULT);
                 }
 
                 kmem_free(buf, size);
                 return (0);
         }
 
         case DTRACEIOC_ENABLE: {
                 dof_hdr_t *dof;
                 dtrace_enabling_t *enab = NULL;
                 dtrace_vstate_t *vstate;
                 int err = 0;
 
                 *rv = 0;
 
                 /*
                  * If a NULL argument has been passed, we take this as our
                  * cue to reevaluate our enablings.
                  */
                 if (arg == NULL) {
                         dtrace_enabling_matchall();
 
                         return (0);
                 }
 
                 if ((dof = dtrace_dof_copyin(arg, &rval)) == NULL)
                         return (rval);
 
                 mutex_enter(&cpu_lock);
                 mutex_enter(&dtrace_lock);
                 vstate = &state->dts_vstate;
 
                 if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE) {
                         mutex_exit(&dtrace_lock);
                         mutex_exit(&cpu_lock);
                         dtrace_dof_destroy(dof);
                         return (EBUSY);
                 }
 
                 if (dtrace_dof_slurp(dof, vstate, cr, &enab, 0, B_TRUE) != 0) {
                         mutex_exit(&dtrace_lock);
                         mutex_exit(&cpu_lock);
                         dtrace_dof_destroy(dof);
                         return (EINVAL);
                 }
 
                 if ((rval = dtrace_dof_options(dof, state)) != 0) {
                         dtrace_enabling_destroy(enab);
                         mutex_exit(&dtrace_lock);
                         mutex_exit(&cpu_lock);
                         dtrace_dof_destroy(dof);
                         return (rval);
                 }
 
                 if ((err = dtrace_enabling_match(enab, rv)) == 0) {
                         err = dtrace_enabling_retain(enab);
                 } else {
                         dtrace_enabling_destroy(enab);
                 }
 
                 mutex_exit(&cpu_lock);
                 mutex_exit(&dtrace_lock);
                 dtrace_dof_destroy(dof);
 
                 return (err);
         }
 
         case DTRACEIOC_REPLICATE: {
                 dtrace_repldesc_t desc;
                 dtrace_probedesc_t *match = &desc.dtrpd_match;
                 dtrace_probedesc_t *create = &desc.dtrpd_create;
                 int err;
 
                 if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                         return (EFAULT);
 
                 match->dtpd_provider[DTRACE_PROVNAMELEN - 1] = '\0';
                 match->dtpd_mod[DTRACE_MODNAMELEN - 1] = '\0';
                 match->dtpd_func[DTRACE_FUNCNAMELEN - 1] = '\0';
                 match->dtpd_name[DTRACE_NAMELEN - 1] = '\0';
 
                 create->dtpd_provider[DTRACE_PROVNAMELEN - 1] = '\0';
                 create->dtpd_mod[DTRACE_MODNAMELEN - 1] = '\0';
                 create->dtpd_func[DTRACE_FUNCNAMELEN - 1] = '\0';
                 create->dtpd_name[DTRACE_NAMELEN - 1] = '\0';
 
                 mutex_enter(&dtrace_lock);
                 err = dtrace_enabling_replicate(state, match, create);
                 mutex_exit(&dtrace_lock);
 
                 return (err);
         }
 
         case DTRACEIOC_PROBEMATCH:
         case DTRACEIOC_PROBES: {
                 dtrace_probe_t *probe = NULL;
                 dtrace_probedesc_t desc;
                 dtrace_probekey_t pkey;
                 dtrace_id_t i;
                 int m = 0;
                 uint32_t priv;
                 uid_t uid;
                 zoneid_t zoneid;
 
                 if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                         return (EFAULT);
 
                 desc.dtpd_provider[DTRACE_PROVNAMELEN - 1] = '\0';
                 desc.dtpd_mod[DTRACE_MODNAMELEN - 1] = '\0';
                 desc.dtpd_func[DTRACE_FUNCNAMELEN - 1] = '\0';
                 desc.dtpd_name[DTRACE_NAMELEN - 1] = '\0';
 
                 /*
                  * Before we attempt to match this probe, we want to give
                  * all providers the opportunity to provide it.
                  */
                 if (desc.dtpd_id == DTRACE_IDNONE) {
                         mutex_enter(&dtrace_provider_lock);
                         dtrace_probe_provide(&desc, NULL);
                         mutex_exit(&dtrace_provider_lock);
                         desc.dtpd_id++;
                 }
 
                 if (cmd == DTRACEIOC_PROBEMATCH)  {
                         dtrace_probekey(&desc, &pkey);
                         pkey.dtpk_id = DTRACE_IDNONE;
                 }
 
                 dtrace_cred2priv(cr, &priv, &uid, &zoneid);
 
                 mutex_enter(&dtrace_lock);
 
                 if (cmd == DTRACEIOC_PROBEMATCH) {
                         for (i = desc.dtpd_id; i <= dtrace_nprobes; i++) {
                                 if ((probe = dtrace_probes[i - 1]) != NULL &&
                                     (m = dtrace_match_probe(probe, &pkey,
                                     priv, uid, zoneid)) != 0)
                                         break;
                         }
 
                         if (m < 0) {
                                 mutex_exit(&dtrace_lock);
                                 return (EINVAL);
                         }
 
                 } else {
                         for (i = desc.dtpd_id; i <= dtrace_nprobes; i++) {
                                 if ((probe = dtrace_probes[i - 1]) != NULL &&
                                     dtrace_match_priv(probe, priv, uid, zoneid))
                                         break;
                         }
                 }
 
                 if (probe == NULL) {
                         mutex_exit(&dtrace_lock);
                         return (ESRCH);
                 }
 
                 dtrace_probe_description(probe, &desc);
                 mutex_exit(&dtrace_lock);
 
                 if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_PROBEARG: {
                 dtrace_argdesc_t desc;
                 dtrace_probe_t *probe;
                 dtrace_provider_t *prov;
 
                 if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                         return (EFAULT);
 
                 if (desc.dtargd_id == DTRACE_IDNONE)
                         return (EINVAL);
 
                 if (desc.dtargd_ndx == DTRACE_ARGNONE)
                         return (EINVAL);
 
                 mutex_enter(&dtrace_provider_lock);
                 mutex_enter(&mod_lock);
                 mutex_enter(&dtrace_lock);
 
                 if (desc.dtargd_id > dtrace_nprobes) {
                         mutex_exit(&dtrace_lock);
                         mutex_exit(&mod_lock);
                         mutex_exit(&dtrace_provider_lock);
                         return (EINVAL);
                 }
 
                 if ((probe = dtrace_probes[desc.dtargd_id - 1]) == NULL) {
                         mutex_exit(&dtrace_lock);
                         mutex_exit(&mod_lock);
                         mutex_exit(&dtrace_provider_lock);
                         return (EINVAL);
                 }
 
                 mutex_exit(&dtrace_lock);
 
                 prov = probe->dtpr_provider;
 
                 if (prov->dtpv_pops.dtps_getargdesc == NULL) {
                         /*
                          * There isn't any typed information for this probe.
                          * Set the argument number to DTRACE_ARGNONE.
                          */
                         desc.dtargd_ndx = DTRACE_ARGNONE;
                 } else {
                         desc.dtargd_native[0] = '\0';
                         desc.dtargd_xlate[0] = '\0';
                         desc.dtargd_mapping = desc.dtargd_ndx;
 
                         prov->dtpv_pops.dtps_getargdesc(prov->dtpv_arg,
                             probe->dtpr_id, probe->dtpr_arg, &desc);
                 }
 
                 mutex_exit(&mod_lock);
                 mutex_exit(&dtrace_provider_lock);
 
                 if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_GO: {
                 processorid_t cpuid;
                 rval = dtrace_state_go(state, &cpuid);
 
                 if (rval != 0)
                         return (rval);
 
                 if (copyout(&cpuid, (void *)arg, sizeof (cpuid)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_STOP: {
                 processorid_t cpuid;
 
                 mutex_enter(&dtrace_lock);
                 rval = dtrace_state_stop(state, &cpuid);
                 mutex_exit(&dtrace_lock);
 
                 if (rval != 0)
                         return (rval);
 
                 if (copyout(&cpuid, (void *)arg, sizeof (cpuid)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_DOFGET: {
                 dof_hdr_t hdr, *dof;
                 uint64_t len;
 
                 if (copyin((void *)arg, &hdr, sizeof (hdr)) != 0)
                         return (EFAULT);
 
                 mutex_enter(&dtrace_lock);
                 dof = dtrace_dof_create(state);
                 mutex_exit(&dtrace_lock);
 
                 len = MIN(hdr.dofh_loadsz, dof->dofh_loadsz);
                 rval = copyout(dof, (void *)arg, len);
                 dtrace_dof_destroy(dof);
 
                 return (rval == 0 ? 0 : EFAULT);
         }
 
         case DTRACEIOC_AGGSNAP:
         case DTRACEIOC_BUFSNAP: {
                 dtrace_bufdesc_t desc;
                 caddr_t cached;
                 dtrace_buffer_t *buf;
 
                 if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                         return (EFAULT);
 
                 if (desc.dtbd_cpu < 0 || desc.dtbd_cpu >= NCPU)
                         return (EINVAL);
 
                 mutex_enter(&dtrace_lock);
 
                 if (cmd == DTRACEIOC_BUFSNAP) {
                         buf = &state->dts_buffer[desc.dtbd_cpu];
                 } else {
                         buf = &state->dts_aggbuffer[desc.dtbd_cpu];
                 }
 
                 if (buf->dtb_flags & (DTRACEBUF_RING | DTRACEBUF_FILL)) {
                         size_t sz = buf->dtb_offset;
 
                         if (state->dts_activity != DTRACE_ACTIVITY_STOPPED) {
                                 mutex_exit(&dtrace_lock);
                                 return (EBUSY);
                         }
 
                         /*
                          * If this buffer has already been consumed, we're
                          * going to indicate that there's nothing left here
                          * to consume.
                          */
                         if (buf->dtb_flags & DTRACEBUF_CONSUMED) {
                                 mutex_exit(&dtrace_lock);
 
                                 desc.dtbd_size = 0;
                                 desc.dtbd_drops = 0;
                                 desc.dtbd_errors = 0;
                                 desc.dtbd_oldest = 0;
                                 sz = sizeof (desc);
 
                                 if (copyout(&desc, (void *)arg, sz) != 0)
                                         return (EFAULT);
 
                                 return (0);
                         }
 
                         /*
                          * If this is a ring buffer that has wrapped, we want
                          * to copy the whole thing out.
                          */
                         if (buf->dtb_flags & DTRACEBUF_WRAPPED) {
                                 dtrace_buffer_polish(buf);
                                 sz = buf->dtb_size;
                         }
 
                         if (copyout(buf->dtb_tomax, desc.dtbd_data, sz) != 0) {
                                 mutex_exit(&dtrace_lock);
                                 return (EFAULT);
                         }
 
                         desc.dtbd_size = sz;
                         desc.dtbd_drops = buf->dtb_drops;
                         desc.dtbd_errors = buf->dtb_errors;
                         desc.dtbd_oldest = buf->dtb_xamot_offset;
                         desc.dtbd_timestamp = dtrace_gethrtime();
 
                         mutex_exit(&dtrace_lock);
 
                         if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                                 return (EFAULT);
 
                         buf->dtb_flags |= DTRACEBUF_CONSUMED;
 
                         return (0);
                 }
 
                 if (buf->dtb_tomax == NULL) {
                         ASSERT(buf->dtb_xamot == NULL);
                         mutex_exit(&dtrace_lock);
                         return (ENOENT);
                 }
 
                 cached = buf->dtb_tomax;
                 ASSERT(!(buf->dtb_flags & DTRACEBUF_NOSWITCH));
 
                 dtrace_xcall(desc.dtbd_cpu,
                     (dtrace_xcall_t)dtrace_buffer_switch, buf);
 
                 state->dts_errors += buf->dtb_xamot_errors;
 
                 /*
                  * If the buffers did not actually switch, then the cross call
                  * did not take place -- presumably because the given CPU is
                  * not in the ready set.  If this is the case, we'll return
                  * ENOENT.
                  */
                 if (buf->dtb_tomax == cached) {
                         ASSERT(buf->dtb_xamot != cached);
                         mutex_exit(&dtrace_lock);
                         return (ENOENT);
                 }
 
                 ASSERT(cached == buf->dtb_xamot);
 
                 /*
                  * We have our snapshot; now copy it out.
                  */
                 if (copyout(buf->dtb_xamot, desc.dtbd_data,
                     buf->dtb_xamot_offset) != 0) {
                         mutex_exit(&dtrace_lock);
                         return (EFAULT);
                 }
 
                 desc.dtbd_size = buf->dtb_xamot_offset;
                 desc.dtbd_drops = buf->dtb_xamot_drops;
                 desc.dtbd_errors = buf->dtb_xamot_errors;
                 desc.dtbd_oldest = 0;
                 desc.dtbd_timestamp = buf->dtb_switched;
 
                 mutex_exit(&dtrace_lock);
 
                 /*
                  * Finally, copy out the buffer description.
                  */
                 if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_CONF: {
                 dtrace_conf_t conf;
 
                 bzero(&conf, sizeof (conf));
                 conf.dtc_difversion = DIF_VERSION;
                 conf.dtc_difintregs = DIF_DIR_NREGS;
                 conf.dtc_diftupregs = DIF_DTR_NREGS;
                 conf.dtc_ctfmodel = CTF_MODEL_NATIVE;
 
                 if (copyout(&conf, (void *)arg, sizeof (conf)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_STATUS: {
                 dtrace_status_t stat;
                 dtrace_dstate_t *dstate;
                 int i, j;
                 uint64_t nerrs;
 
                 /*
                  * See the comment in dtrace_state_deadman() for the reason
                  * for setting dts_laststatus to INT64_MAX before setting
                  * it to the correct value.
                  */
                 state->dts_laststatus = INT64_MAX;
                 dtrace_membar_producer();
                 state->dts_laststatus = dtrace_gethrtime();
 
                 bzero(&stat, sizeof (stat));
 
                 mutex_enter(&dtrace_lock);
 
                 if (state->dts_activity == DTRACE_ACTIVITY_INACTIVE) {
                         mutex_exit(&dtrace_lock);
                         return (ENOENT);
                 }
 
                 if (state->dts_activity == DTRACE_ACTIVITY_DRAINING)
                         stat.dtst_exiting = 1;
 
                 nerrs = state->dts_errors;
                 dstate = &state->dts_vstate.dtvs_dynvars;
 
                 for (i = 0; i < NCPU; i++) {
                         dtrace_dstate_percpu_t *dcpu = &dstate->dtds_percpu[i];
 
                         stat.dtst_dyndrops += dcpu->dtdsc_drops;
                         stat.dtst_dyndrops_dirty += dcpu->dtdsc_dirty_drops;
                         stat.dtst_dyndrops_rinsing += dcpu->dtdsc_rinsing_drops;
 
                         if (state->dts_buffer[i].dtb_flags & DTRACEBUF_FULL)
                                 stat.dtst_filled++;
 
                         nerrs += state->dts_buffer[i].dtb_errors;
 
                         for (j = 0; j < state->dts_nspeculations; j++) {
                                 dtrace_speculation_t *spec;
                                 dtrace_buffer_t *buf;
 
                                 spec = &state->dts_speculations[j];
                                 buf = &spec->dtsp_buffer[i];
                                 stat.dtst_specdrops += buf->dtb_xamot_drops;
                         }
                 }
 
                 stat.dtst_specdrops_busy = state->dts_speculations_busy;
                 stat.dtst_specdrops_unavail = state->dts_speculations_unavail;
                 stat.dtst_stkstroverflows = state->dts_stkstroverflows;
                 stat.dtst_dblerrors = state->dts_dblerrors;
                 stat.dtst_killed =
                     (state->dts_activity == DTRACE_ACTIVITY_KILLED);
                 stat.dtst_errors = nerrs;
 
                 mutex_exit(&dtrace_lock);
 
                 if (copyout(&stat, (void *)arg, sizeof (stat)) != 0)
                         return (EFAULT);
 
                 return (0);
         }
 
         case DTRACEIOC_FORMAT: {
                 dtrace_fmtdesc_t fmt;
                 char *str;
                 int len;
 
                 if (copyin((void *)arg, &fmt, sizeof (fmt)) != 0)
                         return (EFAULT);
 
                 mutex_enter(&dtrace_lock);
 
                 if (fmt.dtfd_format == 0 ||
                     fmt.dtfd_format > state->dts_nformats) {
                         mutex_exit(&dtrace_lock);
                         return (EINVAL);
                 }
 
                 /*
                  * Format strings are allocated contiguously and they are
                  * never freed; if a format index is less than the number
                  * of formats, we can assert that the format map is non-NULL
                  * and that the format for the specified index is non-NULL.
                  */
                 ASSERT(state->dts_formats != NULL);
                 str = state->dts_formats[fmt.dtfd_format - 1];
                 ASSERT(str != NULL);
 
                 len = strlen(str) + 1;
 
                 if (len > fmt.dtfd_length) {
                         fmt.dtfd_length = len;
 
                         if (copyout(&fmt, (void *)arg, sizeof (fmt)) != 0) {
                                 mutex_exit(&dtrace_lock);
                                 return (EINVAL);
                         }
                 } else {
                         if (copyout(str, fmt.dtfd_string, len) != 0) {
                                 mutex_exit(&dtrace_lock);
                                 return (EINVAL);
                         }
                 }
 
                 mutex_exit(&dtrace_lock);
                 return (0);
         }
 
         default:
                 break;
         }
 
         return (ENOTTY);
 }
 
 /*ARGSUSED*/
 static int
 dtrace_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
 {
         dtrace_state_t *state;
 
         switch (cmd) {
         case DDI_DETACH:
                 break;
 
         case DDI_SUSPEND:
                 return (DDI_SUCCESS);
 
         default:
                 return (DDI_FAILURE);
         }
 
         mutex_enter(&cpu_lock);
         mutex_enter(&dtrace_provider_lock);
         mutex_enter(&dtrace_lock);
 
         ASSERT(dtrace_opens == 0);
 
         if (dtrace_helpers > 0) {
                 mutex_exit(&dtrace_provider_lock);
                 mutex_exit(&dtrace_lock);
                 mutex_exit(&cpu_lock);
                 return (DDI_FAILURE);
         }
 
         if (dtrace_unregister((dtrace_provider_id_t)dtrace_provider) != 0) {
                 mutex_exit(&dtrace_provider_lock);
                 mutex_exit(&dtrace_lock);
                 mutex_exit(&cpu_lock);
                 return (DDI_FAILURE);
         }
 
         dtrace_provider = NULL;
 
         if ((state = dtrace_anon_grab()) != NULL) {
                 /*
                  * If there were ECBs on this state, the provider should
                  * have not been allowed to detach; assert that there is
                  * none.
                  */
                 ASSERT(state->dts_necbs == 0);
                 dtrace_state_destroy(state);
 
                 /*
                  * If we're being detached with anonymous state, we need to
                  * indicate to the kernel debugger that DTrace is now inactive.
                  */
                 (void) kdi_dtrace_set(KDI_DTSET_DTRACE_DEACTIVATE);
         }
 
         bzero(&dtrace_anon, sizeof (dtrace_anon_t));
         unregister_cpu_setup_func((cpu_setup_func_t *)dtrace_cpu_setup, NULL);
         dtrace_cpu_init = NULL;
         dtrace_helpers_cleanup = NULL;
         dtrace_helpers_fork = NULL;
         dtrace_cpustart_init = NULL;
         dtrace_cpustart_fini = NULL;
         dtrace_debugger_init = NULL;
         dtrace_debugger_fini = NULL;
         dtrace_modload = NULL;
         dtrace_modunload = NULL;
 
         ASSERT(dtrace_getf == 0);
         ASSERT(dtrace_closef == NULL);
 
         mutex_exit(&cpu_lock);
 
         kmem_free(dtrace_probes, dtrace_nprobes * sizeof (dtrace_probe_t *));
         dtrace_probes = NULL;
         dtrace_nprobes = 0;
 
         dtrace_hash_destroy(dtrace_bymod);
         dtrace_hash_destroy(dtrace_byfunc);
         dtrace_hash_destroy(dtrace_byname);
         dtrace_bymod = NULL;
         dtrace_byfunc = NULL;
         dtrace_byname = NULL;
 
         kmem_cache_destroy(dtrace_state_cache);
         vmem_destroy(dtrace_minor);
         vmem_destroy(dtrace_arena);
 
         if (dtrace_toxrange != NULL) {
                 kmem_free(dtrace_toxrange,
                     dtrace_toxranges_max * sizeof (dtrace_toxrange_t));
                 dtrace_toxrange = NULL;
                 dtrace_toxranges = 0;
                 dtrace_toxranges_max = 0;
         }
 
         ddi_remove_minor_node(dtrace_devi, NULL);
         dtrace_devi = NULL;
 
         ddi_soft_state_fini(&dtrace_softstate);
 
         ASSERT(dtrace_vtime_references == 0);
         ASSERT(dtrace_opens == 0);
         ASSERT(dtrace_retained == NULL);
 
         mutex_exit(&dtrace_lock);
         mutex_exit(&dtrace_provider_lock);
 
         /*
          * We don't destroy the task queue until after we have dropped our
          * locks (taskq_destroy() may block on running tasks).  To prevent
          * attempting to do work after we have effectively detached but before
          * the task queue has been destroyed, all tasks dispatched via the
          * task queue must check that DTrace is still attached before
          * performing any operation.
          */
         taskq_destroy(dtrace_taskq);
         dtrace_taskq = NULL;
 
         return (DDI_SUCCESS);
 }
 #endif
 
 #ifdef illumos
 /*ARGSUSED*/
 static int
 dtrace_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
 {
         int error;
 
         switch (infocmd) {
         case DDI_INFO_DEVT2DEVINFO:
                 *result = (void *)dtrace_devi;
                 error = DDI_SUCCESS;
                 break;
         case DDI_INFO_DEVT2INSTANCE:
                 *result = (void *)0;
                 error = DDI_SUCCESS;
                 break;
         default:
                 error = DDI_FAILURE;
         }
         return (error);
 }
 #endif
 
 #ifdef illumos
 static struct cb_ops dtrace_cb_ops = {
         dtrace_open,            /* open */
         dtrace_close,           /* close */
         nulldev,                /* strategy */
         nulldev,                /* print */
         nodev,                  /* dump */
         nodev,                  /* read */
         nodev,                  /* write */
         dtrace_ioctl,           /* ioctl */
         nodev,                  /* devmap */
         nodev,                  /* mmap */
         nodev,                  /* segmap */
         nochpoll,               /* poll */
         ddi_prop_op,            /* cb_prop_op */
         0,                      /* streamtab  */
         D_NEW | D_MP            /* Driver compatibility flag */
 };
 
 static struct dev_ops dtrace_ops = {
         DEVO_REV,               /* devo_rev */
         0,                      /* refcnt */
         dtrace_info,            /* get_dev_info */
         nulldev,                /* identify */
         nulldev,                /* probe */
         dtrace_attach,          /* attach */
         dtrace_detach,          /* detach */
         nodev,                  /* reset */
         &dtrace_cb_ops,         /* driver operations */
         NULL,                   /* bus operations */
         nodev                   /* dev power */
 };
 
 static struct modldrv modldrv = {
         &mod_driverops,         /* module type (this is a pseudo driver) */
         "Dynamic Tracing",      /* name of module */
         &dtrace_ops,            /* driver ops */
 };
 
 static struct modlinkage modlinkage = {
         MODREV_1,
         (void *)&modldrv,
         NULL
 };
 
 int
 _init(void)
 {
         return (mod_install(&modlinkage));
 }
 
 int
 _info(struct modinfo *modinfop)
 {
         return (mod_info(&modlinkage, modinfop));
 }
 
 int
 _fini(void)
 {
         return (mod_remove(&modlinkage));
 }
 #else
 
 static d_ioctl_t        dtrace_ioctl;
 static d_ioctl_t        dtrace_ioctl_helper;
 static void             dtrace_load(void *);
 static int              dtrace_unload(void);
 static struct cdev      *dtrace_dev;
 static struct cdev      *helper_dev;
 
 void dtrace_invop_init(void);
 void dtrace_invop_uninit(void);
 
 static struct cdevsw dtrace_cdevsw = {
         .d_version      = D_VERSION,
         .d_ioctl        = dtrace_ioctl,
         .d_open         = dtrace_open,
         .d_name         = "dtrace",
 };
 
 static struct cdevsw helper_cdevsw = {
         .d_version      = D_VERSION,
         .d_ioctl        = dtrace_ioctl_helper,
         .d_name         = "helper",
 };
 
 #include <dtrace_anon.c>
 #include <dtrace_ioctl.c>
 #include <dtrace_load.c>
 #include <dtrace_modevent.c>
 #include <dtrace_sysctl.c>
 #include <dtrace_unload.c>
 #include <dtrace_vtime.c>
 #include <dtrace_hacks.c>
 #include <dtrace_isa.c>
 
 SYSINIT(dtrace_load, SI_SUB_DTRACE, SI_ORDER_FIRST, dtrace_load, NULL);
 SYSUNINIT(dtrace_unload, SI_SUB_DTRACE, SI_ORDER_FIRST, dtrace_unload, NULL);
 SYSINIT(dtrace_anon_init, SI_SUB_DTRACE_ANON, SI_ORDER_FIRST, dtrace_anon_init, NULL);
 
 DEV_MODULE(dtrace, dtrace_modevent, NULL);
 MODULE_VERSION(dtrace, 1);
 MODULE_DEPEND(dtrace, opensolaris, 1, 1, 1);
 #endif