FreeBSD/Linux Kernel Cross Reference
sys/cddl/dev/dtrace/i386/dtrace_subr.c

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License, Version 1.0 only
      * (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 2005 Sun Microsystems, Inc.  All rights reserved.
     * Use is subject to license terms.
     */
    
    /*
     * Copyright (c) 2011, Joyent, Inc. All rights reserved.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/cpuset.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/kmem.h>
    #include <sys/proc.h>
    #include <sys/smp.h>
    #include <sys/dtrace_impl.h>
    #include <sys/dtrace_bsd.h>
    #include <cddl/dev/dtrace/dtrace_cddl.h>
    #include <machine/clock.h>
    #include <machine/cpufunc.h>
    #include <machine/frame.h>
    #include <machine/psl.h>
    #include <machine/trap.h>
    #include <vm/pmap.h>
    
    extern uintptr_t        kernelbase;
    
    extern void dtrace_getnanotime(struct timespec *tsp);
    extern int (*dtrace_invop_jump_addr)(struct trapframe *);
    
    int     dtrace_invop(uintptr_t, struct trapframe *, uintptr_t);
    int     dtrace_invop_start(struct trapframe *frame);
    void    dtrace_invop_init(void);
    void    dtrace_invop_uninit(void);
    
    typedef struct dtrace_invop_hdlr {
            int (*dtih_func)(uintptr_t, struct trapframe *, uintptr_t);
            struct dtrace_invop_hdlr *dtih_next;
    } dtrace_invop_hdlr_t;
    
    dtrace_invop_hdlr_t *dtrace_invop_hdlr;
    
    int
    dtrace_invop(uintptr_t addr, struct trapframe *frame, uintptr_t eax)
    {
            struct thread *td;
            dtrace_invop_hdlr_t *hdlr;
            int rval;
    
            rval = 0;
            td = curthread;
            td->t_dtrace_trapframe = frame;
            for (hdlr = dtrace_invop_hdlr; hdlr != NULL; hdlr = hdlr->dtih_next)
                    if ((rval = hdlr->dtih_func(addr, frame, eax)) != 0)
                            break;
            td->t_dtrace_trapframe = NULL;
            return (rval);
    }
    
    void
    dtrace_invop_add(int (*func)(uintptr_t, struct trapframe *, uintptr_t))
    {
            dtrace_invop_hdlr_t *hdlr;
    
            hdlr = kmem_alloc(sizeof (dtrace_invop_hdlr_t), KM_SLEEP);
            hdlr->dtih_func = func;
            hdlr->dtih_next = dtrace_invop_hdlr;
            dtrace_invop_hdlr = hdlr;
    }
    
    void
    dtrace_invop_remove(int (*func)(uintptr_t, struct trapframe *, uintptr_t))
    {
           dtrace_invop_hdlr_t *hdlr = dtrace_invop_hdlr, *prev = NULL;
   
           for (;;) {
                   if (hdlr == NULL)
                           panic("attempt to remove non-existent invop handler");
   
                   if (hdlr->dtih_func == func)
                           break;
   
                   prev = hdlr;
                   hdlr = hdlr->dtih_next;
           }
   
           if (prev == NULL) {
                   ASSERT(dtrace_invop_hdlr == hdlr);
                   dtrace_invop_hdlr = hdlr->dtih_next;
           } else {
                   ASSERT(dtrace_invop_hdlr != hdlr);
                   prev->dtih_next = hdlr->dtih_next;
           }
   
           kmem_free(hdlr, 0);
   }
   
   void
   dtrace_invop_init(void)
   {
   
           dtrace_invop_jump_addr = dtrace_invop_start;
   }
   
   void
   dtrace_invop_uninit(void)
   {
   
           dtrace_invop_jump_addr = NULL;
   }
   
   void
   dtrace_toxic_ranges(void (*func)(uintptr_t base, uintptr_t limit))
   {
           (*func)(0, kernelbase);
   }
   
   void
   dtrace_xcall(processorid_t cpu, dtrace_xcall_t func, void *arg)
   {
           cpuset_t cpus;
   
           if (cpu == DTRACE_CPUALL)
                   cpus = all_cpus;
           else
                   CPU_SETOF(cpu, &cpus);
   
           smp_rendezvous_cpus(cpus, smp_no_rendezvous_barrier, func,
               smp_no_rendezvous_barrier, arg);
   }
   
   static void
   dtrace_sync_func(void)
   {
   }
   
   void
   dtrace_sync(void)
   {
           dtrace_xcall(DTRACE_CPUALL, (dtrace_xcall_t)dtrace_sync_func, NULL);
   }
   
   #ifdef notyet
   void
   dtrace_safe_synchronous_signal(void)
   {
           kthread_t *t = curthread;
           struct regs *rp = lwptoregs(ttolwp(t));
           size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
   
           ASSERT(t->t_dtrace_on);
   
           /*
            * If we're not in the range of scratch addresses, we're not actually
            * tracing user instructions so turn off the flags. If the instruction
            * we copied out caused a synchonous trap, reset the pc back to its
            * original value and turn off the flags.
            */
           if (rp->r_pc < t->t_dtrace_scrpc ||
               rp->r_pc > t->t_dtrace_astpc + isz) {
                   t->t_dtrace_ft = 0;
           } else if (rp->r_pc == t->t_dtrace_scrpc ||
               rp->r_pc == t->t_dtrace_astpc) {
                   rp->r_pc = t->t_dtrace_pc;
                   t->t_dtrace_ft = 0;
           }
   }
   
   int
   dtrace_safe_defer_signal(void)
   {
           kthread_t *t = curthread;
           struct regs *rp = lwptoregs(ttolwp(t));
           size_t isz = t->t_dtrace_npc - t->t_dtrace_pc;
   
           ASSERT(t->t_dtrace_on);
   
           /*
            * If we're not in the range of scratch addresses, we're not actually
            * tracing user instructions so turn off the flags.
            */
           if (rp->r_pc < t->t_dtrace_scrpc ||
               rp->r_pc > t->t_dtrace_astpc + isz) {
                   t->t_dtrace_ft = 0;
                   return (0);
           }
   
           /*
            * If we have executed the original instruction, but we have performed
            * neither the jmp back to t->t_dtrace_npc nor the clean up of any
            * registers used to emulate %rip-relative instructions in 64-bit mode,
            * we'll save ourselves some effort by doing that here and taking the
            * signal right away.  We detect this condition by seeing if the program
            * counter is the range [scrpc + isz, astpc).
            */
           if (rp->r_pc >= t->t_dtrace_scrpc + isz &&
               rp->r_pc < t->t_dtrace_astpc) {
   #ifdef __amd64
                   /*
                    * If there is a scratch register and we're on the
                    * instruction immediately after the modified instruction,
                    * restore the value of that scratch register.
                    */
                   if (t->t_dtrace_reg != 0 &&
                       rp->r_pc == t->t_dtrace_scrpc + isz) {
                           switch (t->t_dtrace_reg) {
                           case REG_RAX:
                                   rp->r_rax = t->t_dtrace_regv;
                                   break;
                           case REG_RCX:
                                   rp->r_rcx = t->t_dtrace_regv;
                                   break;
                           case REG_R8:
                                   rp->r_r8 = t->t_dtrace_regv;
                                   break;
                           case REG_R9:
                                   rp->r_r9 = t->t_dtrace_regv;
                                   break;
                           }
                   }
   #endif
                   rp->r_pc = t->t_dtrace_npc;
                   t->t_dtrace_ft = 0;
                   return (0);
           }
   
           /*
            * Otherwise, make sure we'll return to the kernel after executing
            * the copied out instruction and defer the signal.
            */
           if (!t->t_dtrace_step) {
                   ASSERT(rp->r_pc < t->t_dtrace_astpc);
                   rp->r_pc += t->t_dtrace_astpc - t->t_dtrace_scrpc;
                   t->t_dtrace_step = 1;
           }
   
           t->t_dtrace_ast = 1;
   
           return (1);
   }
   #endif
   
   static int64_t  tgt_cpu_tsc;
   static int64_t  hst_cpu_tsc;
   static int64_t  tsc_skew[MAXCPU];
   static uint64_t nsec_scale;
   
   /* See below for the explanation of this macro. */
   #define SCALE_SHIFT     28
   
   static void
   dtrace_gethrtime_init_cpu(void *arg)
   {
           uintptr_t cpu = (uintptr_t) arg;
   
           if (cpu == curcpu)
                   tgt_cpu_tsc = rdtsc();
           else
                   hst_cpu_tsc = rdtsc();
   }
   
   #ifdef EARLY_AP_STARTUP
   static void
   dtrace_gethrtime_init(void *arg)
   {
           struct pcpu *pc;
           uint64_t tsc_f;
           cpuset_t map;
           int i;
   #else
   /*
    * Get the frequency and scale factor as early as possible so that they can be
    * used for boot-time tracing.
    */
   static void
   dtrace_gethrtime_init_early(void *arg)
   {
           uint64_t tsc_f;
   #endif
   
           /*
            * Get TSC frequency known at this moment.
            * This should be constant if TSC is invariant.
            * Otherwise tick->time conversion will be inaccurate, but
            * will preserve monotonic property of TSC.
            */
           tsc_f = atomic_load_acq_64(&tsc_freq);
   
           /*
            * The following line checks that nsec_scale calculated below
            * doesn't overflow 32-bit unsigned integer, so that it can multiply
            * another 32-bit integer without overflowing 64-bit.
            * Thus minimum supported TSC frequency is 62.5MHz.
            */
           KASSERT(tsc_f > (NANOSEC >> (32 - SCALE_SHIFT)),
               ("TSC frequency is too low"));
   
           /*
            * We scale up NANOSEC/tsc_f ratio to preserve as much precision
            * as possible.
            * 2^28 factor was chosen quite arbitrarily from practical
            * considerations:
            * - it supports TSC frequencies as low as 62.5MHz (see above);
            * - it provides quite good precision (e < 0.01%) up to THz
            *   (terahertz) values;
            */
           nsec_scale = ((uint64_t)NANOSEC << SCALE_SHIFT) / tsc_f;
   #ifndef EARLY_AP_STARTUP
   }
   SYSINIT(dtrace_gethrtime_init_early, SI_SUB_CPU, SI_ORDER_ANY,
       dtrace_gethrtime_init_early, NULL);
   
   static void
   dtrace_gethrtime_init(void *arg)
   {
           cpuset_t map;
           struct pcpu *pc;
           int i;
   #endif
   
           if (vm_guest != VM_GUEST_NO)
                   return;
   
           /* The current CPU is the reference one. */
           sched_pin();
           tsc_skew[curcpu] = 0;
           CPU_FOREACH(i) {
                   if (i == curcpu)
                           continue;
   
                   pc = pcpu_find(i);
                   CPU_SETOF(PCPU_GET(cpuid), &map);
                   CPU_SET(pc->pc_cpuid, &map);
   
                   smp_rendezvous_cpus(map, NULL,
                       dtrace_gethrtime_init_cpu,
                       smp_no_rendezvous_barrier, (void *)(uintptr_t) i);
   
                   tsc_skew[i] = tgt_cpu_tsc - hst_cpu_tsc;
           }
           sched_unpin();
   }
   #ifdef EARLY_AP_STARTUP
   SYSINIT(dtrace_gethrtime_init, SI_SUB_DTRACE, SI_ORDER_ANY,
       dtrace_gethrtime_init, NULL);
   #else
   SYSINIT(dtrace_gethrtime_init, SI_SUB_SMP, SI_ORDER_ANY, dtrace_gethrtime_init,
       NULL);
   #endif
   
   /*
    * DTrace needs a high resolution time function which can
    * be called from a probe context and guaranteed not to have
    * instrumented with probes itself.
    *
    * Returns nanoseconds since boot.
    */
   uint64_t
   dtrace_gethrtime(void)
   {
           uint64_t tsc;
           uint32_t lo, hi;
           register_t eflags;
   
           /*
            * We split TSC value into lower and higher 32-bit halves and separately
            * scale them with nsec_scale, then we scale them down by 2^28
            * (see nsec_scale calculations) taking into account 32-bit shift of
            * the higher half and finally add.
            */
           eflags = intr_disable();
           tsc = rdtsc() - tsc_skew[curcpu];
           intr_restore(eflags);
   
           lo = tsc;
           hi = tsc >> 32;
           return (((lo * nsec_scale) >> SCALE_SHIFT) +
               ((hi * nsec_scale) << (32 - SCALE_SHIFT)));
   }
   
   uint64_t
   dtrace_gethrestime(void)
   {
           struct timespec current_time;
   
           dtrace_getnanotime(&current_time);
   
           return (current_time.tv_sec * 1000000000ULL + current_time.tv_nsec);
   }
   
   /* Function to handle DTrace traps during probes. See i386/i386/trap.c */
   int
   dtrace_trap(struct trapframe *frame, u_int type)
   {
           uint16_t nofault;
   
           /*
            * A trap can occur while DTrace executes a probe. Before
            * executing the probe, DTrace blocks re-scheduling and sets
            * a flag in its per-cpu flags to indicate that it doesn't
            * want to fault. On returning from the probe, the no-fault
            * flag is cleared and finally re-scheduling is enabled.
            *
            * Check if DTrace has enabled 'no-fault' mode:
            */
           sched_pin();
           nofault = cpu_core[curcpu].cpuc_dtrace_flags & CPU_DTRACE_NOFAULT;
           sched_unpin();
           if (nofault) {
                   KASSERT((read_eflags() & PSL_I) == 0, ("interrupts enabled"));
   
                   /*
                    * There are only a couple of trap types that are expected.
                    * All the rest will be handled in the usual way.
                    */
                   switch (type) {
                   /* General protection fault. */
                   case T_PROTFLT:
                           /* Flag an illegal operation. */
                           cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
   
                           /*
                            * Offset the instruction pointer to the instruction
                            * following the one causing the fault.
                            */
                           frame->tf_eip += dtrace_instr_size((u_char *) frame->tf_eip);
                           return (1);
                   /* Page fault. */
                   case T_PAGEFLT:
                           /* Flag a bad address. */
                           cpu_core[curcpu].cpuc_dtrace_flags |= CPU_DTRACE_BADADDR;
                           cpu_core[curcpu].cpuc_dtrace_illval = rcr2();
   
                           /*
                            * Offset the instruction pointer to the instruction
                            * following the one causing the fault.
                            */
                           frame->tf_eip += dtrace_instr_size((u_char *) frame->tf_eip);
                           return (1);
                   default:
                           /* Handle all other traps in the usual way. */
                           break;
                   }
           }
   
           /* Handle the trap in the usual way. */
           return (0);
   }

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