The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ktr.c

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    1 /*-
    2  * Copyright (c) 2000 John Baldwin <jhb@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the author nor the names of any co-contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 /*
   31  * This module holds the global variables used by KTR and the ktr_tracepoint()
   32  * function that does the actual tracing.
   33  */
   34 
   35 #include <sys/cdefs.h>
   36 __FBSDID("$FreeBSD: releng/10.0/sys/kern/kern_ktr.c 246530 2013-02-08 07:29:07Z avg $");
   37 
   38 #include "opt_ddb.h"
   39 #include "opt_ktr.h"
   40 #include "opt_alq.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/queue.h>
   44 #include <sys/alq.h>
   45 #include <sys/cons.h>
   46 #include <sys/cpuset.h>
   47 #include <sys/kernel.h>
   48 #include <sys/ktr.h>
   49 #include <sys/libkern.h>
   50 #include <sys/lock.h>
   51 #include <sys/malloc.h>
   52 #include <sys/mutex.h>
   53 #include <sys/proc.h>
   54 #include <sys/smp.h>
   55 #include <sys/sysctl.h>
   56 #include <sys/systm.h>
   57 #include <sys/time.h>
   58 
   59 #include <machine/cpu.h>
   60 #ifdef __sparc64__
   61 #include <machine/ktr.h>
   62 #endif
   63 
   64 #ifdef DDB
   65 #include <ddb/ddb.h>
   66 #include <ddb/db_output.h>
   67 #endif
   68 
   69 #ifndef KTR_BOOT_ENTRIES
   70 #define KTR_BOOT_ENTRIES        1024
   71 #endif
   72 
   73 #ifndef KTR_ENTRIES
   74 #define KTR_ENTRIES     1024
   75 #endif
   76 
   77 /* Limit the allocations to something manageable. */
   78 #define KTR_ENTRIES_MAX (8 * 1024 * 1024)
   79 
   80 #ifndef KTR_MASK
   81 #define KTR_MASK        (0)
   82 #endif
   83 
   84 #ifndef KTR_CPUMASK
   85 #define KTR_CPUMASK     CPUSET_FSET
   86 #endif
   87 
   88 #ifndef KTR_TIME
   89 #define KTR_TIME        get_cyclecount()
   90 #endif
   91 
   92 #ifndef KTR_CPU
   93 #define KTR_CPU         PCPU_GET(cpuid)
   94 #endif
   95 
   96 static MALLOC_DEFINE(M_KTR, "KTR", "KTR");
   97 
   98 FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
   99 
  100 volatile int    ktr_idx = 0;
  101 int     ktr_mask = KTR_MASK;
  102 int     ktr_compile = KTR_COMPILE;
  103 int     ktr_entries = KTR_BOOT_ENTRIES;
  104 int     ktr_version = KTR_VERSION;
  105 struct  ktr_entry ktr_buf_init[KTR_BOOT_ENTRIES];
  106 struct  ktr_entry *ktr_buf = ktr_buf_init;
  107 cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
  108 static char ktr_cpumask_str[CPUSETBUFSIZ];
  109 
  110 TUNABLE_INT("debug.ktr.mask", &ktr_mask);
  111 
  112 TUNABLE_STR("debug.ktr.cpumask", ktr_cpumask_str, sizeof(ktr_cpumask_str));
  113 
  114 static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD, 0, "KTR options");
  115 
  116 SYSCTL_INT(_debug_ktr, OID_AUTO, version, CTLFLAG_RD,
  117     &ktr_version, 0, "Version of the KTR interface");
  118 
  119 SYSCTL_UINT(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
  120     &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
  121 
  122 static void
  123 ktr_cpumask_initializer(void *dummy __unused)
  124 {
  125 
  126         /*
  127          * TUNABLE_STR() runs with SI_ORDER_MIDDLE priority, thus it must be
  128          * already set, if necessary.
  129          */
  130         if (ktr_cpumask_str[0] != '\0' &&
  131             cpusetobj_strscan(&ktr_cpumask, ktr_cpumask_str) == -1)
  132                 CPU_FILL(&ktr_cpumask);
  133 }
  134 SYSINIT(ktr_cpumask_initializer, SI_SUB_TUNABLES, SI_ORDER_ANY,
  135     ktr_cpumask_initializer, NULL);
  136 
  137 static int
  138 sysctl_debug_ktr_cpumask(SYSCTL_HANDLER_ARGS)
  139 {
  140         char lktr_cpumask_str[CPUSETBUFSIZ];
  141         cpuset_t imask;
  142         int error;
  143 
  144         cpusetobj_strprint(lktr_cpumask_str, &ktr_cpumask);
  145         error = sysctl_handle_string(oidp, lktr_cpumask_str,
  146             sizeof(lktr_cpumask_str), req);
  147         if (error != 0 || req->newptr == NULL)
  148                 return (error);
  149         if (cpusetobj_strscan(&imask, lktr_cpumask_str) == -1)
  150                 return (EINVAL);
  151         CPU_COPY(&imask, &ktr_cpumask);
  152 
  153         return (error);
  154 }
  155 SYSCTL_PROC(_debug_ktr, OID_AUTO, cpumask,
  156     CTLFLAG_RW | CTLFLAG_MPSAFE | CTLTYPE_STRING, NULL, 0,
  157     sysctl_debug_ktr_cpumask, "S",
  158     "Bitmask of CPUs on which KTR logging is enabled");
  159 
  160 static int
  161 sysctl_debug_ktr_clear(SYSCTL_HANDLER_ARGS)
  162 {
  163         int clear, error;
  164 
  165         clear = 0;
  166         error = sysctl_handle_int(oidp, &clear, 0, req);
  167         if (error || !req->newptr)
  168                 return (error);
  169 
  170         if (clear) {
  171                 bzero(ktr_buf, sizeof(*ktr_buf) * ktr_entries);
  172                 ktr_idx = 0;
  173         }
  174 
  175         return (error);
  176 }
  177 SYSCTL_PROC(_debug_ktr, OID_AUTO, clear, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
  178     sysctl_debug_ktr_clear, "I", "Clear KTR Buffer");
  179 
  180 /*
  181  * This is a sysctl proc so that it is serialized as !MPSAFE along with
  182  * the other ktr sysctl procs.
  183  */
  184 static int
  185 sysctl_debug_ktr_mask(SYSCTL_HANDLER_ARGS)
  186 {
  187         int mask, error;
  188 
  189         mask = ktr_mask;
  190         error = sysctl_handle_int(oidp, &mask, 0, req);
  191         if (error || !req->newptr)
  192                 return (error);
  193         ktr_mask = mask;
  194         return (error);
  195 }
  196 
  197 SYSCTL_PROC(_debug_ktr, OID_AUTO, mask, CTLTYPE_UINT|CTLFLAG_RW, 0, 0,
  198     sysctl_debug_ktr_mask, "IU",
  199     "Bitmask of KTR event classes for which logging is enabled");
  200 
  201 #if KTR_ENTRIES > KTR_BOOT_ENTRIES
  202 /*
  203  * A simplified version of sysctl_debug_ktr_entries.
  204  * No need to care about SMP, scheduling, etc.
  205  */
  206 static void
  207 ktr_entries_initializer(void *dummy __unused)
  208 {
  209         int mask;
  210 
  211         /* Temporarily disable ktr in case malloc() is being traced. */
  212         mask = ktr_mask;
  213         ktr_mask = 0;
  214         ktr_buf = malloc(sizeof(*ktr_buf) * KTR_ENTRIES, M_KTR,
  215             M_WAITOK | M_ZERO);
  216         memcpy(ktr_buf, ktr_buf_init + ktr_idx,
  217             (KTR_BOOT_ENTRIES - ktr_idx) * sizeof(*ktr_buf));
  218         if (ktr_idx != 0)
  219                 memcpy(ktr_buf + KTR_BOOT_ENTRIES - ktr_idx, ktr_buf_init,
  220                     ktr_idx * sizeof(*ktr_buf));
  221         ktr_entries = KTR_ENTRIES;
  222         ktr_mask = mask;
  223 }
  224 SYSINIT(ktr_entries_initializer, SI_SUB_KMEM, SI_ORDER_ANY,
  225     ktr_entries_initializer, NULL);
  226 #endif
  227 
  228 static int
  229 sysctl_debug_ktr_entries(SYSCTL_HANDLER_ARGS)
  230 {
  231         int entries, error, mask;
  232         struct ktr_entry *buf, *oldbuf;
  233 
  234         entries = ktr_entries;
  235         error = sysctl_handle_int(oidp, &entries, 0, req);
  236         if (error || !req->newptr)
  237                 return (error);
  238         if (entries > KTR_ENTRIES_MAX)
  239                 return (ERANGE);
  240         /* Disable ktr temporarily. */
  241         mask = ktr_mask;
  242         atomic_store_rel_int(&ktr_mask, 0);
  243         /* Wait for threads to go idle. */
  244         if ((error = quiesce_all_cpus("ktrent", PCATCH)) != 0) {
  245                 ktr_mask = mask;
  246                 return (error);
  247         }
  248         if (ktr_buf != ktr_buf_init)
  249                 oldbuf = ktr_buf;
  250         else
  251                 oldbuf = NULL;
  252         /* Allocate a new buffer. */
  253         buf = malloc(sizeof(*buf) * entries, M_KTR, M_WAITOK | M_ZERO);
  254         /* Install the new buffer and restart ktr. */
  255         ktr_buf = buf;
  256         ktr_entries = entries;
  257         ktr_idx = 0;
  258         atomic_store_rel_int(&ktr_mask, mask);
  259         if (oldbuf != NULL)
  260                 free(oldbuf, M_KTR);
  261 
  262         return (error);
  263 }
  264 
  265 SYSCTL_PROC(_debug_ktr, OID_AUTO, entries, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
  266     sysctl_debug_ktr_entries, "I", "Number of entries in the KTR buffer");
  267 
  268 #ifdef KTR_VERBOSE
  269 int     ktr_verbose = KTR_VERBOSE;
  270 TUNABLE_INT("debug.ktr.verbose", &ktr_verbose);
  271 SYSCTL_INT(_debug_ktr, OID_AUTO, verbose, CTLFLAG_RW, &ktr_verbose, 0, "");
  272 #endif
  273 
  274 #ifdef KTR_ALQ
  275 struct alq *ktr_alq;
  276 char    ktr_alq_file[MAXPATHLEN] = "/tmp/ktr.out";
  277 int     ktr_alq_cnt = 0;
  278 int     ktr_alq_depth = KTR_ENTRIES;
  279 int     ktr_alq_enabled = 0;
  280 int     ktr_alq_failed = 0;
  281 int     ktr_alq_max = 0;
  282 
  283 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_max, CTLFLAG_RW, &ktr_alq_max, 0,
  284     "Maximum number of entries to write");
  285 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_cnt, CTLFLAG_RD, &ktr_alq_cnt, 0,
  286     "Current number of written entries");
  287 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_failed, CTLFLAG_RD, &ktr_alq_failed, 0,
  288     "Number of times we overran the buffer");
  289 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_depth, CTLFLAG_RW, &ktr_alq_depth, 0,
  290     "Number of items in the write buffer");
  291 SYSCTL_STRING(_debug_ktr, OID_AUTO, alq_file, CTLFLAG_RW, ktr_alq_file,
  292     sizeof(ktr_alq_file), "KTR logging file");
  293 
  294 static int
  295 sysctl_debug_ktr_alq_enable(SYSCTL_HANDLER_ARGS)
  296 {
  297         int error;
  298         int enable;
  299 
  300         enable = ktr_alq_enabled;
  301 
  302         error = sysctl_handle_int(oidp, &enable, 0, req);
  303         if (error || !req->newptr)
  304                 return (error);
  305 
  306         if (enable) {
  307                 if (ktr_alq_enabled)
  308                         return (0);
  309                 error = alq_open(&ktr_alq, (const char *)ktr_alq_file,
  310                     req->td->td_ucred, ALQ_DEFAULT_CMODE,
  311                     sizeof(struct ktr_entry), ktr_alq_depth);
  312                 if (error == 0) {
  313                         ktr_alq_cnt = 0;
  314                         ktr_alq_failed = 0;
  315                         ktr_alq_enabled = 1;
  316                 }
  317         } else {
  318                 if (ktr_alq_enabled == 0)
  319                         return (0);
  320                 ktr_alq_enabled = 0;
  321                 alq_close(ktr_alq);
  322                 ktr_alq = NULL;
  323         }
  324 
  325         return (error);
  326 }
  327 SYSCTL_PROC(_debug_ktr, OID_AUTO, alq_enable,
  328     CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_debug_ktr_alq_enable,
  329     "I", "Enable KTR logging");
  330 #endif
  331 
  332 void
  333 ktr_tracepoint(u_int mask, const char *file, int line, const char *format,
  334     u_long arg1, u_long arg2, u_long arg3, u_long arg4, u_long arg5,
  335     u_long arg6)
  336 {
  337         struct ktr_entry *entry;
  338 #ifdef KTR_ALQ
  339         struct ale *ale = NULL;
  340 #endif
  341         int newindex, saveindex;
  342 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  343         struct thread *td;
  344 #endif
  345         int cpu;
  346 
  347         if (panicstr)
  348                 return;
  349         if ((ktr_mask & mask) == 0 || ktr_buf == NULL)
  350                 return;
  351         cpu = KTR_CPU;
  352         if (!CPU_ISSET(cpu, &ktr_cpumask))
  353                 return;
  354 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  355         td = curthread;
  356         if (td->td_pflags & TDP_INKTR)
  357                 return;
  358         td->td_pflags |= TDP_INKTR;
  359 #endif
  360 #ifdef KTR_ALQ
  361         if (ktr_alq_enabled) {
  362                 if (td->td_critnest == 0 &&
  363                     (td->td_flags & TDF_IDLETD) == 0 &&
  364                     td != ald_thread) {
  365                         if (ktr_alq_max && ktr_alq_cnt > ktr_alq_max)
  366                                 goto done;
  367                         if ((ale = alq_get(ktr_alq, ALQ_NOWAIT)) == NULL) {
  368                                 ktr_alq_failed++;
  369                                 goto done;
  370                         }
  371                         ktr_alq_cnt++;
  372                         entry = (struct ktr_entry *)ale->ae_data;
  373                 } else {
  374                         goto done;
  375                 }
  376         } else
  377 #endif
  378         {
  379                 do {
  380                         saveindex = ktr_idx;
  381                         newindex = (saveindex + 1) % ktr_entries;
  382                 } while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
  383                 entry = &ktr_buf[saveindex];
  384         }
  385         entry->ktr_timestamp = KTR_TIME;
  386         entry->ktr_cpu = cpu;
  387         entry->ktr_thread = curthread;
  388         if (file != NULL)
  389                 while (strncmp(file, "../", 3) == 0)
  390                         file += 3;
  391         entry->ktr_file = file;
  392         entry->ktr_line = line;
  393 #ifdef KTR_VERBOSE
  394         if (ktr_verbose) {
  395 #ifdef SMP
  396                 printf("cpu%d ", cpu);
  397 #endif
  398                 if (ktr_verbose > 1) {
  399                         printf("%s.%d\t", entry->ktr_file,
  400                             entry->ktr_line);
  401                 }
  402                 printf(format, arg1, arg2, arg3, arg4, arg5, arg6);
  403                 printf("\n");
  404         }
  405 #endif
  406         entry->ktr_desc = format;
  407         entry->ktr_parms[0] = arg1;
  408         entry->ktr_parms[1] = arg2;
  409         entry->ktr_parms[2] = arg3;
  410         entry->ktr_parms[3] = arg4;
  411         entry->ktr_parms[4] = arg5;
  412         entry->ktr_parms[5] = arg6;
  413 #ifdef KTR_ALQ
  414         if (ktr_alq_enabled && ale)
  415                 alq_post(ktr_alq, ale);
  416 done:
  417 #endif
  418 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  419         td->td_pflags &= ~TDP_INKTR;
  420 #endif
  421 }
  422 
  423 #ifdef DDB
  424 
  425 struct tstate {
  426         int     cur;
  427         int     first;
  428 };
  429 static  struct tstate tstate;
  430 static  int db_ktr_verbose;
  431 static  int db_mach_vtrace(void);
  432 
  433 DB_SHOW_COMMAND(ktr, db_ktr_all)
  434 {
  435         
  436         tstate.cur = (ktr_idx - 1) % ktr_entries;
  437         tstate.first = -1;
  438         db_ktr_verbose = 0;
  439         db_ktr_verbose |= (strchr(modif, 'v') != NULL) ? 2 : 0;
  440         db_ktr_verbose |= (strchr(modif, 'V') != NULL) ? 1 : 0; /* just timestap please */
  441         if (strchr(modif, 'a') != NULL) {
  442                 db_disable_pager();
  443                 while (cncheckc() != -1)
  444                         if (db_mach_vtrace() == 0)
  445                                 break;
  446         } else {
  447                 while (!db_pager_quit)
  448                         if (db_mach_vtrace() == 0)
  449                                 break;
  450         }
  451 }
  452 
  453 static int
  454 db_mach_vtrace(void)
  455 {
  456         struct ktr_entry        *kp;
  457 
  458         if (tstate.cur == tstate.first || ktr_buf == NULL) {
  459                 db_printf("--- End of trace buffer ---\n");
  460                 return (0);
  461         }
  462         kp = &ktr_buf[tstate.cur];
  463 
  464         /* Skip over unused entries. */
  465         if (kp->ktr_desc == NULL) {
  466                 db_printf("--- End of trace buffer ---\n");
  467                 return (0);
  468         }
  469         db_printf("%d (%p", tstate.cur, kp->ktr_thread);
  470 #ifdef SMP
  471         db_printf(":cpu%d", kp->ktr_cpu);
  472 #endif
  473         db_printf(")");
  474         if (db_ktr_verbose >= 1) {
  475                 db_printf(" %10.10lld", (long long)kp->ktr_timestamp);
  476         }
  477         if (db_ktr_verbose >= 2) {
  478                 db_printf(" %s.%d", kp->ktr_file, kp->ktr_line);
  479         }
  480         db_printf(": ");
  481         db_printf(kp->ktr_desc, kp->ktr_parms[0], kp->ktr_parms[1],
  482             kp->ktr_parms[2], kp->ktr_parms[3], kp->ktr_parms[4],
  483             kp->ktr_parms[5]);
  484         db_printf("\n");
  485 
  486         if (tstate.first == -1)
  487                 tstate.first = tstate.cur;
  488 
  489         if (--tstate.cur < 0)
  490                 tstate.cur = ktr_entries - 1;
  491 
  492         return (1);
  493 }
  494 
  495 #endif  /* DDB */

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