kern_ktr.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2000 John Baldwin <jhb@FreeBSD.org>
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  */
   27 
   28 /*
   29  * This module holds the global variables used by KTR and the ktr_tracepoint()
   30  * function that does the actual tracing.
   31  */
   32 
   33 #include <sys/cdefs.h>
   34 __FBSDID("$FreeBSD$");
   35 
   36 #include "opt_ddb.h"
   37 #include "opt_ktr.h"
   38 #include "opt_alq.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/queue.h>
   42 #include <sys/alq.h>
   43 #include <sys/cons.h>
   44 #include <sys/cpuset.h>
   45 #include <sys/kdb.h>
   46 #include <sys/kernel.h>
   47 #include <sys/ktr.h>
   48 #include <sys/libkern.h>
   49 #include <sys/lock.h>
   50 #include <sys/malloc.h>
   51 #include <sys/mutex.h>
   52 #include <sys/proc.h>
   53 #include <sys/smp.h>
   54 #include <sys/sysctl.h>
   55 #include <sys/systm.h>
   56 #include <sys/time.h>
   57 
   58 #include <machine/cpu.h>
   59 
   60 #ifdef DDB
   61 #include <ddb/ddb.h>
   62 #include <ddb/db_output.h>
   63 #endif
   64 
   65 #ifndef KTR_BOOT_ENTRIES
   66 #define KTR_BOOT_ENTRIES        1024
   67 #endif
   68 
   69 #ifndef KTR_ENTRIES
   70 #define KTR_ENTRIES     1024
   71 #endif
   72 
   73 /* Limit the allocations to something manageable. */
   74 #define KTR_ENTRIES_MAX (8 * 1024 * 1024)
   75 
   76 #ifndef KTR_MASK
   77 #define KTR_MASK        (0)
   78 #endif
   79 
   80 #ifndef KTR_CPUMASK
   81 #define KTR_CPUMASK     CPUSET_FSET
   82 #endif
   83 
   84 #ifndef KTR_TIME
   85 #define KTR_TIME        get_cyclecount()
   86 #endif
   87 
   88 #ifndef KTR_CPU
   89 #define KTR_CPU         PCPU_GET(cpuid)
   90 #endif
   91 
   92 static MALLOC_DEFINE(M_KTR, "KTR", "KTR");
   93 
   94 FEATURE(ktr, "Kernel support for KTR kernel tracing facility");
   95 
   96 volatile int    ktr_idx = 0;
   97 uint64_t ktr_mask = KTR_MASK;
   98 uint64_t ktr_compile = KTR_COMPILE;
   99 int     ktr_entries = KTR_BOOT_ENTRIES;
  100 int     ktr_version = KTR_VERSION;
  101 struct  ktr_entry ktr_buf_init[KTR_BOOT_ENTRIES];
  102 struct  ktr_entry *ktr_buf = ktr_buf_init;
  103 cpuset_t ktr_cpumask = CPUSET_T_INITIALIZER(KTR_CPUMASK);
  104 
  105 static SYSCTL_NODE(_debug, OID_AUTO, ktr, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
  106     "KTR options");
  107 
  108 SYSCTL_INT(_debug_ktr, OID_AUTO, version, CTLFLAG_RD,
  109     &ktr_version, 0, "Version of the KTR interface");
  110 
  111 SYSCTL_UQUAD(_debug_ktr, OID_AUTO, compile, CTLFLAG_RD,
  112     &ktr_compile, 0, "Bitmask of KTR event classes compiled into the kernel");
  113 
  114 static int
  115 sysctl_debug_ktr_cpumask(SYSCTL_HANDLER_ARGS)
  116 {
  117         char lktr_cpumask_str[CPUSETBUFSIZ];
  118         cpuset_t imask;
  119         int error;
  120 
  121         cpusetobj_strprint(lktr_cpumask_str, &ktr_cpumask);
  122         error = sysctl_handle_string(oidp, lktr_cpumask_str,
  123             sizeof(lktr_cpumask_str), req);
  124         if (error != 0 || req->newptr == NULL)
  125                 return (error);
  126         if (cpusetobj_strscan(&imask, lktr_cpumask_str) == -1)
  127                 return (EINVAL);
  128         CPU_COPY(&imask, &ktr_cpumask);
  129 
  130         return (error);
  131 }
  132 SYSCTL_PROC(_debug_ktr, OID_AUTO, cpumask,
  133     CTLFLAG_RWTUN | CTLFLAG_MPSAFE | CTLTYPE_STRING, NULL, 0,
  134     sysctl_debug_ktr_cpumask, "S",
  135     "Bitmask of CPUs on which KTR logging is enabled");
  136 
  137 static int
  138 sysctl_debug_ktr_clear(SYSCTL_HANDLER_ARGS)
  139 {
  140         int clear, error;
  141 
  142         clear = 0;
  143         error = sysctl_handle_int(oidp, &clear, 0, req);
  144         if (error || !req->newptr)
  145                 return (error);
  146 
  147         if (clear) {
  148                 bzero(ktr_buf, sizeof(*ktr_buf) * ktr_entries);
  149                 ktr_idx = 0;
  150         }
  151 
  152         return (error);
  153 }
  154 SYSCTL_PROC(_debug_ktr, OID_AUTO, clear,
  155     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, 0,
  156     sysctl_debug_ktr_clear, "I",
  157     "Clear KTR Buffer");
  158 
  159 /*
  160  * This is a sysctl proc so that it is serialized as !MPSAFE along with
  161  * the other ktr sysctl procs.
  162  */
  163 static int
  164 sysctl_debug_ktr_mask(SYSCTL_HANDLER_ARGS)
  165 {
  166         uint64_t mask;
  167         int error;
  168 
  169         mask = ktr_mask;
  170         error = sysctl_handle_64(oidp, &mask, 0, req);
  171         if (error || !req->newptr)
  172                 return (error);
  173         ktr_mask = mask;
  174         return (error);
  175 }
  176 
  177 SYSCTL_PROC(_debug_ktr, OID_AUTO, mask,
  178     CTLTYPE_U64 | CTLFLAG_RWTUN | CTLFLAG_NEEDGIANT,
  179     0, 0, sysctl_debug_ktr_mask, "QU",
  180     "Bitmask of KTR event classes for which logging is enabled");
  181 
  182 #if KTR_ENTRIES > KTR_BOOT_ENTRIES
  183 /*
  184  * A simplified version of sysctl_debug_ktr_entries.
  185  * No need to care about SMP, scheduling, etc.
  186  */
  187 static void
  188 ktr_entries_initializer(void *dummy __unused)
  189 {
  190         uint64_t mask;
  191 
  192         /* Temporarily disable ktr in case malloc() is being traced. */
  193         mask = ktr_mask;
  194         ktr_mask = 0;
  195         ktr_buf = malloc(sizeof(*ktr_buf) * KTR_ENTRIES, M_KTR,
  196             M_WAITOK | M_ZERO);
  197         memcpy(ktr_buf, ktr_buf_init + ktr_idx,
  198             (KTR_BOOT_ENTRIES - ktr_idx) * sizeof(*ktr_buf));
  199         if (ktr_idx != 0) {
  200                 memcpy(ktr_buf + KTR_BOOT_ENTRIES - ktr_idx, ktr_buf_init,
  201                     ktr_idx * sizeof(*ktr_buf));
  202                 ktr_idx = KTR_BOOT_ENTRIES;
  203         }
  204         ktr_entries = KTR_ENTRIES;
  205         ktr_mask = mask;
  206 }
  207 SYSINIT(ktr_entries_initializer, SI_SUB_KMEM, SI_ORDER_ANY,
  208     ktr_entries_initializer, NULL);
  209 #endif
  210 
  211 static int
  212 sysctl_debug_ktr_entries(SYSCTL_HANDLER_ARGS)
  213 {
  214         uint64_t mask;
  215         int entries, error;
  216         struct ktr_entry *buf, *oldbuf;
  217 
  218         entries = ktr_entries;
  219         error = sysctl_handle_int(oidp, &entries, 0, req);
  220         if (error || !req->newptr)
  221                 return (error);
  222         if (entries > KTR_ENTRIES_MAX)
  223                 return (ERANGE);
  224         /* Disable ktr temporarily. */
  225         mask = ktr_mask;
  226         ktr_mask = 0;
  227         /* Wait for threads to go idle. */
  228         if ((error = quiesce_all_cpus("ktrent", PCATCH)) != 0) {
  229                 ktr_mask = mask;
  230                 return (error);
  231         }
  232         if (ktr_buf != ktr_buf_init)
  233                 oldbuf = ktr_buf;
  234         else
  235                 oldbuf = NULL;
  236         /* Allocate a new buffer. */
  237         buf = malloc(sizeof(*buf) * entries, M_KTR, M_WAITOK | M_ZERO);
  238         /* Install the new buffer and restart ktr. */
  239         ktr_buf = buf;
  240         ktr_entries = entries;
  241         ktr_idx = 0;
  242         ktr_mask = mask;
  243         if (oldbuf != NULL)
  244                 free(oldbuf, M_KTR);
  245 
  246         return (error);
  247 }
  248 
  249 SYSCTL_PROC(_debug_ktr, OID_AUTO, entries,
  250     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT,
  251     0, 0, sysctl_debug_ktr_entries, "I",
  252     "Number of entries in the KTR buffer");
  253 
  254 #ifdef KTR_VERBOSE
  255 int     ktr_verbose = KTR_VERBOSE;
  256 TUNABLE_INT("debug.ktr.verbose", &ktr_verbose);
  257 SYSCTL_INT(_debug_ktr, OID_AUTO, verbose, CTLFLAG_RW, &ktr_verbose, 0, "");
  258 #endif
  259 
  260 #ifdef KTR_ALQ
  261 struct alq *ktr_alq;
  262 char    ktr_alq_file[MAXPATHLEN] = "/tmp/ktr.out";
  263 int     ktr_alq_cnt = 0;
  264 int     ktr_alq_depth = KTR_ENTRIES;
  265 int     ktr_alq_enabled = 0;
  266 int     ktr_alq_failed = 0;
  267 int     ktr_alq_max = 0;
  268 
  269 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_max, CTLFLAG_RW, &ktr_alq_max, 0,
  270     "Maximum number of entries to write");
  271 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_cnt, CTLFLAG_RD, &ktr_alq_cnt, 0,
  272     "Current number of written entries");
  273 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_failed, CTLFLAG_RD, &ktr_alq_failed, 0,
  274     "Number of times we overran the buffer");
  275 SYSCTL_INT(_debug_ktr, OID_AUTO, alq_depth, CTLFLAG_RW, &ktr_alq_depth, 0,
  276     "Number of items in the write buffer");
  277 SYSCTL_STRING(_debug_ktr, OID_AUTO, alq_file, CTLFLAG_RW, ktr_alq_file,
  278     sizeof(ktr_alq_file), "KTR logging file");
  279 
  280 static int
  281 sysctl_debug_ktr_alq_enable(SYSCTL_HANDLER_ARGS)
  282 {
  283         int error;
  284         int enable;
  285 
  286         enable = ktr_alq_enabled;
  287 
  288         error = sysctl_handle_int(oidp, &enable, 0, req);
  289         if (error || !req->newptr)
  290                 return (error);
  291 
  292         if (enable) {
  293                 if (ktr_alq_enabled)
  294                         return (0);
  295                 error = alq_open(&ktr_alq, (const char *)ktr_alq_file,
  296                     req->td->td_ucred, ALQ_DEFAULT_CMODE,
  297                     sizeof(struct ktr_entry), ktr_alq_depth);
  298                 if (error == 0) {
  299                         ktr_alq_cnt = 0;
  300                         ktr_alq_failed = 0;
  301                         ktr_alq_enabled = 1;
  302                 }
  303         } else {
  304                 if (ktr_alq_enabled == 0)
  305                         return (0);
  306                 ktr_alq_enabled = 0;
  307                 alq_close(ktr_alq);
  308                 ktr_alq = NULL;
  309         }
  310 
  311         return (error);
  312 }
  313 SYSCTL_PROC(_debug_ktr, OID_AUTO, alq_enable,
  314     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, 0,
  315     sysctl_debug_ktr_alq_enable, "I",
  316     "Enable KTR logging");
  317 #endif
  318 
  319 void
  320 ktr_tracepoint(uint64_t mask, const char *file, int line, const char *format,
  321     u_long arg1, u_long arg2, u_long arg3, u_long arg4, u_long arg5,
  322     u_long arg6)
  323 {
  324         struct ktr_entry *entry;
  325 #ifdef KTR_ALQ
  326         struct ale *ale = NULL;
  327 #endif
  328         int newindex, saveindex;
  329 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  330         struct thread *td;
  331 #endif
  332         int cpu;
  333 
  334         if (KERNEL_PANICKED() || kdb_active)
  335                 return;
  336         if ((ktr_mask & mask) == 0 || ktr_buf == NULL)
  337                 return;
  338         cpu = KTR_CPU;
  339         if (!CPU_ISSET(cpu, &ktr_cpumask))
  340                 return;
  341 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  342         td = curthread;
  343         if (td->td_pflags & TDP_INKTR)
  344                 return;
  345         td->td_pflags |= TDP_INKTR;
  346 #endif
  347 #ifdef KTR_ALQ
  348         if (ktr_alq_enabled) {
  349                 if (td->td_critnest == 0 &&
  350                     (TD_IS_IDLETHREAD(td)) == 0 &&
  351                     td != ald_thread) {
  352                         if (ktr_alq_max && ktr_alq_cnt > ktr_alq_max)
  353                                 goto done;
  354                         if ((ale = alq_get(ktr_alq, ALQ_NOWAIT)) == NULL) {
  355                                 ktr_alq_failed++;
  356                                 goto done;
  357                         }
  358                         ktr_alq_cnt++;
  359                         entry = (struct ktr_entry *)ale->ae_data;
  360                 } else {
  361                         goto done;
  362                 }
  363         } else
  364 #endif
  365         {
  366                 do {
  367                         saveindex = ktr_idx;
  368                         newindex = (saveindex + 1) % ktr_entries;
  369                 } while (atomic_cmpset_rel_int(&ktr_idx, saveindex, newindex) == 0);
  370                 entry = &ktr_buf[saveindex];
  371         }
  372         entry->ktr_timestamp = KTR_TIME;
  373         entry->ktr_cpu = cpu;
  374         entry->ktr_thread = curthread;
  375         if (file != NULL)
  376                 while (strncmp(file, "../", 3) == 0)
  377                         file += 3;
  378         entry->ktr_file = file;
  379         entry->ktr_line = line;
  380 #ifdef KTR_VERBOSE
  381         if (ktr_verbose) {
  382 #ifdef SMP
  383                 printf("cpu%d ", cpu);
  384 #endif
  385                 if (ktr_verbose > 1) {
  386                         printf("%s.%d\t", entry->ktr_file,
  387                             entry->ktr_line);
  388                 }
  389                 printf(format, arg1, arg2, arg3, arg4, arg5, arg6);
  390                 printf("\n");
  391         }
  392 #endif
  393         entry->ktr_desc = format;
  394         entry->ktr_parms[0] = arg1;
  395         entry->ktr_parms[1] = arg2;
  396         entry->ktr_parms[2] = arg3;
  397         entry->ktr_parms[3] = arg4;
  398         entry->ktr_parms[4] = arg5;
  399         entry->ktr_parms[5] = arg6;
  400 #ifdef KTR_ALQ
  401         if (ktr_alq_enabled && ale)
  402                 alq_post(ktr_alq, ale);
  403 done:
  404 #endif
  405 #if defined(KTR_VERBOSE) || defined(KTR_ALQ)
  406         td->td_pflags &= ~TDP_INKTR;
  407 #endif
  408 }
  409 
  410 #ifdef DDB
  411 
  412 struct tstate {
  413         int     cur;
  414         int     first;
  415 };
  416 static  struct tstate tstate;
  417 static  int db_ktr_verbose;
  418 static  int db_mach_vtrace(void);
  419 
  420 DB_SHOW_COMMAND_FLAGS(ktr, db_ktr_all, DB_CMD_MEMSAFE)
  421 {
  422 
  423         tstate.cur = (ktr_idx - 1) % ktr_entries;
  424         tstate.first = -1;
  425         db_ktr_verbose = 0;
  426         db_ktr_verbose |= (strchr(modif, 'v') != NULL) ? 2 : 0;
  427         db_ktr_verbose |= (strchr(modif, 'V') != NULL) ? 1 : 0; /* just timestamp please */
  428         if (strchr(modif, 'a') != NULL) {
  429                 db_disable_pager();
  430                 while (cncheckc() == -1)
  431                         if (db_mach_vtrace() == 0)
  432                                 break;
  433         } else {
  434                 while (!db_pager_quit)
  435                         if (db_mach_vtrace() == 0)
  436                                 break;
  437         }
  438 }
  439 
  440 static int
  441 db_mach_vtrace(void)
  442 {
  443         struct ktr_entry        *kp;
  444 
  445         if (tstate.cur == tstate.first || ktr_buf == NULL) {
  446                 db_printf("--- End of trace buffer ---\n");
  447                 return (0);
  448         }
  449         kp = &ktr_buf[tstate.cur];
  450 
  451         /* Skip over unused entries. */
  452         if (kp->ktr_desc == NULL) {
  453                 db_printf("--- End of trace buffer ---\n");
  454                 return (0);
  455         }
  456         db_printf("%d (%p", tstate.cur, kp->ktr_thread);
  457 #ifdef SMP
  458         db_printf(":cpu%d", kp->ktr_cpu);
  459 #endif
  460         db_printf(")");
  461         if (db_ktr_verbose >= 1) {
  462                 db_printf(" %10.10lld", (long long)kp->ktr_timestamp);
  463         }
  464         if (db_ktr_verbose >= 2) {
  465                 db_printf(" %s.%d", kp->ktr_file, kp->ktr_line);
  466         }
  467         db_printf(": ");
  468         db_printf(kp->ktr_desc, kp->ktr_parms[0], kp->ktr_parms[1],
  469             kp->ktr_parms[2], kp->ktr_parms[3], kp->ktr_parms[4],
  470             kp->ktr_parms[5]);
  471         db_printf("\n");
  472 
  473         if (tstate.first == -1)
  474                 tstate.first = tstate.cur;
  475 
  476         if (--tstate.cur < 0)
  477                 tstate.cur = ktr_entries - 1;
  478 
  479         return (1);
  480 }
  481 
  482 #endif  /* DDB */
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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_ktr.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_ktr.c
