The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 /*
   28  * This module holds the global variables used by KTR and the ktr_tracepoint()
   29  * function that does the actual tracing.
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_ktr.c 295098 2016-01-31 17:32:20Z andrew $");
   34 
   35 #include "opt_ddb.h"
   36 #include "opt_ktr.h"
   37 #include "opt_alq.h"
   38 
   39 #include <sys/param.h>
   40 #include <sys/queue.h>
   41 #include <sys/alq.h>
   42 #include <sys/cons.h>
   43 #include <sys/cpuset.h>
   44 #include <sys/kdb.h>
   45 #include <sys/kernel.h>
   46 #include <sys/ktr.h>
   47 #include <sys/libkern.h>
   48 #include <sys/lock.h>
   49 #include <sys/malloc.h>
   50 #include <sys/mutex.h>
   51 #include <sys/proc.h>
   52 #include <sys/smp.h>
   53 #include <sys/sysctl.h>
   54 #include <sys/systm.h>
   55 #include <sys/time.h>
   56 
   57 #include <machine/cpu.h>
   58 
   59 #ifdef DDB
   60 #include <ddb/ddb.h>
   61 #include <ddb/db_output.h>
   62 #endif
   63 
   64 #ifndef KTR_BOOT_ENTRIES
   65 #define KTR_BOOT_ENTRIES        1024
   66 #endif
   67 
   68 #ifndef KTR_ENTRIES
   69 #define KTR_ENTRIES     1024
   70 #endif
   71 
   72 /* Limit the allocations to something manageable. */
   73 #define KTR_ENTRIES_MAX (8 * 1024 * 1024)
   74 
   75 #ifndef KTR_MASK
   76 #define KTR_MASK        (0)
   77 #endif
   78 
   79 #ifndef KTR_CPUMASK
   80 #define KTR_CPUMASK     CPUSET_FSET
   81 #endif
   82 
   83 #ifndef KTR_TIME
   84 #define KTR_TIME        get_cyclecount()
   85 #endif
   86 
   87 #ifndef KTR_CPU
   88 #define KTR_CPU         PCPU_GET(cpuid)
   89 #endif
   90 
   91 static MALLOC_DEFINE(M_KTR, "KTR", "KTR");
   92 
   93 FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
   94 
   95 volatile int    ktr_idx = 0;
   96 uint64_t ktr_mask = KTR_MASK;
   97 uint64_t ktr_compile = KTR_COMPILE;
   98 int     ktr_entries = KTR_BOOT_ENTRIES;
   99 int     ktr_version = KTR_VERSION;
  100 struct  ktr_entry ktr_buf_init[KTR_BOOT_ENTRIES];
  101 struct  ktr_entry *ktr_buf = ktr_buf_init;
  102 cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
  103 
  104 static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD, 0, "KTR options");
  105 
  106 SYSCTL_INT(_debug_ktr, OID_AUTO, version, CTLFLAG_RD,
  107     &ktr_version, 0, "Version of the KTR interface");
  108 
  109 SYSCTL_UQUAD(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
  110     &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
  111 
  112 static int
  113 sysctl_debug_ktr_cpumask(SYSCTL_HANDLER_ARGS)
  114 {
  115         char lktr_cpumask_str[CPUSETBUFSIZ];
  116         cpuset_t imask;
  117         int error;
  118 
  119         cpusetobj_strprint(lktr_cpumask_str, &ktr_cpumask);
  120         error = sysctl_handle_string(oidp, lktr_cpumask_str,
  121             sizeof(lktr_cpumask_str), req);
  122         if (error != 0 || req->newptr == NULL)
  123                 return (error);
  124         if (cpusetobj_strscan(&imask, lktr_cpumask_str) == -1)
  125                 return (EINVAL);
  126         CPU_COPY(&imask, &ktr_cpumask);
  127 
  128         return (error);
  129 }
  130 SYSCTL_PROC(_debug_ktr, OID_AUTO, cpumask,
  131     CTLFLAG_RWTUN | CTLFLAG_MPSAFE | CTLTYPE_STRING, NULL, 0,
  132     sysctl_debug_ktr_cpumask, "S",
  133     "Bitmask of CPUs on which KTR logging is enabled");
  134 
  135 static int
  136 sysctl_debug_ktr_clear(SYSCTL_HANDLER_ARGS)
  137 {
  138         int clear, error;
  139 
  140         clear = 0;
  141         error = sysctl_handle_int(oidp, &clear, 0, req);
  142         if (error || !req->newptr)
  143                 return (error);
  144 
  145         if (clear) {
  146                 bzero(ktr_buf, sizeof(*ktr_buf) * ktr_entries);
  147                 ktr_idx = 0;
  148         }
  149 
  150         return (error);
  151 }
  152 SYSCTL_PROC(_debug_ktr, OID_AUTO, clear, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
  153     sysctl_debug_ktr_clear, "I", "Clear KTR Buffer");
  154 
  155 /*
  156  * This is a sysctl proc so that it is serialized as !MPSAFE along with
  157  * the other ktr sysctl procs.
  158  */
  159 static int
  160 sysctl_debug_ktr_mask(SYSCTL_HANDLER_ARGS)
  161 {
  162         uint64_t mask;
  163         int error;
  164 
  165         mask = ktr_mask;
  166         error = sysctl_handle_64(oidp, &mask, 0, req);
  167         if (error || !req->newptr)
  168                 return (error);
  169         ktr_mask = mask;
  170         return (error);
  171 }
  172 
  173 SYSCTL_PROC(_debug_ktr, OID_AUTO, mask, CTLTYPE_U64 | CTLFLAG_RWTUN, 0, 0,
  174     sysctl_debug_ktr_mask, "QU",
  175     "Bitmask of KTR event classes for which logging is enabled");
  176 
  177 #if KTR_ENTRIES > KTR_BOOT_ENTRIES
  178 /*
  179  * A simplified version of sysctl_debug_ktr_entries.
  180  * No need to care about SMP, scheduling, etc.
  181  */
  182 static void
  183 ktr_entries_initializer(void *dummy __unused)
  184 {
  185         uint64_t mask;
  186 
  187         /* Temporarily disable ktr in case malloc() is being traced. */
  188         mask = ktr_mask;
  189         ktr_mask = 0;
  190         ktr_buf = malloc(sizeof(*ktr_buf) * KTR_ENTRIES, M_KTR,
  191             M_WAITOK | M_ZERO);
  192         memcpy(ktr_buf, ktr_buf_init + ktr_idx,
  193             (KTR_BOOT_ENTRIES - ktr_idx) * sizeof(*ktr_buf));
  194         if (ktr_idx != 0) {
  195                 memcpy(ktr_buf + KTR_BOOT_ENTRIES - ktr_idx, ktr_buf_init,
  196                     ktr_idx * sizeof(*ktr_buf));
  197                 ktr_idx = KTR_BOOT_ENTRIES;
  198         }
  199         ktr_entries = KTR_ENTRIES;
  200         ktr_mask = mask;
  201 }
  202 SYSINIT(ktr_entries_initializer, SI_SUB_KMEM, SI_ORDER_ANY,
  203     ktr_entries_initializer, NULL);
  204 #endif
  205 
  206 static int
  207 sysctl_debug_ktr_entries(SYSCTL_HANDLER_ARGS)
  208 {
  209         uint64_t mask;
  210         int entries, error;
  211         struct ktr_entry *buf, *oldbuf;
  212 
  213         entries = ktr_entries;
  214         error = sysctl_handle_int(oidp, &entries, 0, req);
  215         if (error || !req->newptr)
  216                 return (error);
  217         if (entries > KTR_ENTRIES_MAX)
  218                 return (ERANGE);
  219         /* Disable ktr temporarily. */
  220         mask = ktr_mask;
  221         ktr_mask = 0;
  222         /* Wait for threads to go idle. */
  223         if ((error = quiesce_all_cpus("ktrent", PCATCH)) != 0) {
  224                 ktr_mask = mask;
  225                 return (error);
  226         }
  227         if (ktr_buf != ktr_buf_init)
  228                 oldbuf = ktr_buf;
  229         else
  230                 oldbuf = NULL;
  231         /* Allocate a new buffer. */
  232         buf = malloc(sizeof(*buf) * entries, M_KTR, M_WAITOK | M_ZERO);
  233         /* Install the new buffer and restart ktr. */
  234         ktr_buf = buf;
  235         ktr_entries = entries;
  236         ktr_idx = 0;
  237         ktr_mask = mask;
  238         if (oldbuf != NULL)
  239                 free(oldbuf, M_KTR);
  240 
  241         return (error);
  242 }
  243 
  244 SYSCTL_PROC(_debug_ktr, OID_AUTO, entries, CTLTYPE_INT|CTLFLAG_RW, 0, 0,
  245     sysctl_debug_ktr_entries, "I", "Number of entries in the KTR buffer");
  246 
  247 #ifdef KTR_VERBOSE
  248 int     ktr_verbose = KTR_VERBOSE;
  249 TUNABLE_INT("debug.ktr.verbose", &ktr_verbose);
  250 SYSCTL_INT(_debug_ktr, OID_AUTO, verbose, CTLFLAG_RW, &ktr_verbose, 0, "");
  251 #endif
  252 
  253 #ifdef KTR_ALQ
  254 struct alq *ktr_alq;
  255 char    ktr_alq_file[MAXPATHLEN] = "/tmp/ktr.out";
  256 int     ktr_alq_cnt = 0;
  257 int     ktr_alq_depth = KTR_ENTRIES;
  258 int     ktr_alq_enabled = 0;
  259 int     ktr_alq_failed = 0;
  260 int     ktr_alq_max = 0;
  261 
  262 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_max, CTLFLAG_RW, &ktr_alq_max, 0,
  263     "Maximum number of entries to write");
  264 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_cnt, CTLFLAG_RD, &ktr_alq_cnt, 0,
  265     "Current number of written entries");
  266 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_failed, CTLFLAG_RD, &ktr_alq_failed, 0,
  267     "Number of times we overran the buffer");
  268 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_depth, CTLFLAG_RW, &ktr_alq_depth, 0,
  269     "Number of items in the write buffer");
  270 SYSCTL_STRING(_debug_ktr, OID_AUTO, alq_file, CTLFLAG_RW, ktr_alq_file,
  271     sizeof(ktr_alq_file), "KTR logging file");
  272 
  273 static int
  274 sysctl_debug_ktr_alq_enable(SYSCTL_HANDLER_ARGS)
  275 {
  276         int error;
  277         int enable;
  278 
  279         enable = ktr_alq_enabled;
  280 
  281         error = sysctl_handle_int(oidp, &enable, 0, req);
  282         if (error || !req->newptr)
  283                 return (error);
  284 
  285         if (enable) {
  286                 if (ktr_alq_enabled)
  287                         return (0);
  288                 error = alq_open(&ktr_alq, (const char *)ktr_alq_file,
  289                     req->td->td_ucred, ALQ_DEFAULT_CMODE,
  290                     sizeof(struct ktr_entry), ktr_alq_depth);
  291                 if (error == 0) {
  292                         ktr_alq_cnt = 0;
  293                         ktr_alq_failed = 0;
  294                         ktr_alq_enabled = 1;
  295                 }
  296         } else {
  297                 if (ktr_alq_enabled == 0)
  298                         return (0);
  299                 ktr_alq_enabled = 0;
  300                 alq_close(ktr_alq);
  301                 ktr_alq = NULL;
  302         }
  303 
  304         return (error);
  305 }
  306 SYSCTL_PROC(_debug_ktr, OID_AUTO, alq_enable,
  307     CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_debug_ktr_alq_enable,
  308     "I", "Enable KTR logging");
  309 #endif
  310 
  311 void
  312 ktr_tracepoint(uint64_t mask, const char *file, int line, const char *format,
  313     u_long arg1, u_long arg2, u_long arg3, u_long arg4, u_long arg5,
  314     u_long arg6)
  315 {
  316         struct ktr_entry *entry;
  317 #ifdef KTR_ALQ
  318         struct ale *ale = NULL;
  319 #endif
  320         int newindex, saveindex;
  321 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  322         struct thread *td;
  323 #endif
  324         int cpu;
  325 
  326         if (panicstr || kdb_active)
  327                 return;
  328         if ((ktr_mask & mask) == 0 || ktr_buf == NULL)
  329                 return;
  330         cpu = KTR_CPU;
  331         if (!CPU_ISSET(cpu, &ktr_cpumask))
  332                 return;
  333 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  334         td = curthread;
  335         if (td->td_pflags & TDP_INKTR)
  336                 return;
  337         td->td_pflags |= TDP_INKTR;
  338 #endif
  339 #ifdef KTR_ALQ
  340         if (ktr_alq_enabled) {
  341                 if (td->td_critnest == 0 &&
  342                     (td->td_flags & TDF_IDLETD) == 0 &&
  343                     td != ald_thread) {
  344                         if (ktr_alq_max && ktr_alq_cnt > ktr_alq_max)
  345                                 goto done;
  346                         if ((ale = alq_get(ktr_alq, ALQ_NOWAIT)) == NULL) {
  347                                 ktr_alq_failed++;
  348                                 goto done;
  349                         }
  350                         ktr_alq_cnt++;
  351                         entry = (struct ktr_entry *)ale->ae_data;
  352                 } else {
  353                         goto done;
  354                 }
  355         } else
  356 #endif
  357         {
  358                 do {
  359                         saveindex = ktr_idx;
  360                         newindex = (saveindex + 1) % ktr_entries;
  361                 } while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
  362                 entry = &ktr_buf[saveindex];
  363         }
  364         entry->ktr_timestamp = KTR_TIME;
  365         entry->ktr_cpu = cpu;
  366         entry->ktr_thread = curthread;
  367         if (file != NULL)
  368                 while (strncmp(file, "../", 3) == 0)
  369                         file += 3;
  370         entry->ktr_file = file;
  371         entry->ktr_line = line;
  372 #ifdef KTR_VERBOSE
  373         if (ktr_verbose) {
  374 #ifdef SMP
  375                 printf("cpu%d ", cpu);
  376 #endif
  377                 if (ktr_verbose > 1) {
  378                         printf("%s.%d\t", entry->ktr_file,
  379                             entry->ktr_line);
  380                 }
  381                 printf(format, arg1, arg2, arg3, arg4, arg5, arg6);
  382                 printf("\n");
  383         }
  384 #endif
  385         entry->ktr_desc = format;
  386         entry->ktr_parms[0] = arg1;
  387         entry->ktr_parms[1] = arg2;
  388         entry->ktr_parms[2] = arg3;
  389         entry->ktr_parms[3] = arg4;
  390         entry->ktr_parms[4] = arg5;
  391         entry->ktr_parms[5] = arg6;
  392 #ifdef KTR_ALQ
  393         if (ktr_alq_enabled && ale)
  394                 alq_post(ktr_alq, ale);
  395 done:
  396 #endif
  397 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  398         td->td_pflags &= ~TDP_INKTR;
  399 #endif
  400 }
  401 
  402 #ifdef DDB
  403 
  404 struct tstate {
  405         int     cur;
  406         int     first;
  407 };
  408 static  struct tstate tstate;
  409 static  int db_ktr_verbose;
  410 static  int db_mach_vtrace(void);
  411 
  412 DB_SHOW_COMMAND(ktr, db_ktr_all)
  413 {
  414         
  415         tstate.cur = (ktr_idx - 1) % ktr_entries;
  416         tstate.first = -1;
  417         db_ktr_verbose = 0;
  418         db_ktr_verbose |= (strchr(modif, 'v') != NULL) ? 2 : 0;
  419         db_ktr_verbose |= (strchr(modif, 'V') != NULL) ? 1 : 0; /* just timestap please */
  420         if (strchr(modif, 'a') != NULL) {
  421                 db_disable_pager();
  422                 while (cncheckc() == -1)
  423                         if (db_mach_vtrace() == 0)
  424                                 break;
  425         } else {
  426                 while (!db_pager_quit)
  427                         if (db_mach_vtrace() == 0)
  428                                 break;
  429         }
  430 }
  431 
  432 static int
  433 db_mach_vtrace(void)
  434 {
  435         struct ktr_entry        *kp;
  436 
  437         if (tstate.cur == tstate.first || ktr_buf == NULL) {
  438                 db_printf("--- End of trace buffer ---\n");
  439                 return (0);
  440         }
  441         kp = &ktr_buf[tstate.cur];
  442 
  443         /* Skip over unused entries. */
  444         if (kp->ktr_desc == NULL) {
  445                 db_printf("--- End of trace buffer ---\n");
  446                 return (0);
  447         }
  448         db_printf("%d (%p", tstate.cur, kp->ktr_thread);
  449 #ifdef SMP
  450         db_printf(":cpu%d", kp->ktr_cpu);
  451 #endif
  452         db_printf(")");
  453         if (db_ktr_verbose >= 1) {
  454                 db_printf(" %10.10lld", (long long)kp->ktr_timestamp);
  455         }
  456         if (db_ktr_verbose >= 2) {
  457                 db_printf(" %s.%d", kp->ktr_file, kp->ktr_line);
  458         }
  459         db_printf(": ");
  460         db_printf(kp->ktr_desc, kp->ktr_parms[0], kp->ktr_parms[1],
  461             kp->ktr_parms[2], kp->ktr_parms[3], kp->ktr_parms[4],
  462             kp->ktr_parms[5]);
  463         db_printf("\n");
  464 
  465         if (tstate.first == -1)
  466                 tstate.first = tstate.cur;
  467 
  468         if (--tstate.cur < 0)
  469                 tstate.cur = ktr_entries - 1;
  470 
  471         return (1);
  472 }
  473 
  474 #endif  /* DDB */

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