kern_tslog.c

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    1 /*-
    2  * Copyright (c) 2017 Colin Percival
    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 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include <sys/param.h>
   31 #include <sys/kernel.h>
   32 #include <sys/linker.h>
   33 #include <sys/malloc.h>
   34 #include <sys/proc.h>
   35 #include <sys/sbuf.h>
   36 #include <sys/sysctl.h>
   37 #include <sys/systm.h>
   38 #include <sys/tslog.h>
   39 
   40 #include <machine/atomic.h>
   41 #include <machine/cpu.h>
   42 
   43 #ifndef TSLOGSIZE
   44 #define TSLOGSIZE 262144
   45 #endif
   46 
   47 static volatile long nrecs = 0;
   48 static struct timestamp {
   49         void * td;
   50         int type;
   51         const char * f;
   52         const char * s;
   53         uint64_t tsc;
   54 } timestamps[TSLOGSIZE];
   55 
   56 void
   57 tslog(void * td, int type, const char * f, const char * s)
   58 {
   59         uint64_t tsc = get_cyclecount();
   60         long pos;
   61 
   62         /* Grab a slot. */
   63         pos = atomic_fetchadd_long(&nrecs, 1);
   64 
   65         /* Store record. */
   66         if (pos < nitems(timestamps)) {
   67                 timestamps[pos].td = td;
   68                 timestamps[pos].type = type;
   69                 timestamps[pos].f = f;
   70                 timestamps[pos].s = s;
   71                 timestamps[pos].tsc = tsc;
   72         }
   73 }
   74 
   75 static int
   76 sysctl_debug_tslog(SYSCTL_HANDLER_ARGS)
   77 {
   78         int error;
   79         struct sbuf *sb;
   80         size_t i, limit;
   81         caddr_t loader_tslog;
   82         void * loader_tslog_buf;
   83         size_t loader_tslog_len;
   84 
   85         /*
   86          * This code can race against the code in tslog() which stores
   87          * records: Theoretically we could end up reading a record after
   88          * its slots have been reserved but before it has been written.
   89          * Since this code takes orders of magnitude longer to run than
   90          * tslog() takes to write a record, it is highly unlikely that
   91          * anyone will ever experience this race.
   92          */
   93         sb = sbuf_new_for_sysctl(NULL, NULL, 1024, req);
   94 
   95         /* Get data from the boot loader, if it provided any. */
   96         loader_tslog = preload_search_by_type("TSLOG data");
   97         if (loader_tslog != NULL) {
   98                 loader_tslog_buf = preload_fetch_addr(loader_tslog);
   99                 loader_tslog_len = preload_fetch_size(loader_tslog);
  100                 sbuf_bcat(sb, loader_tslog_buf, loader_tslog_len);
  101         }
  102 
  103         /* Add data logged within the kernel. */
  104         limit = MIN(nrecs, nitems(timestamps));
  105         for (i = 0; i < limit; i++) {
  106                 sbuf_printf(sb, "%p", timestamps[i].td);
  107                 sbuf_printf(sb, " %llu",
  108                     (unsigned long long)timestamps[i].tsc);
  109                 switch (timestamps[i].type) {
  110                 case TS_ENTER:
  111                         sbuf_printf(sb, " ENTER");
  112                         break;
  113                 case TS_EXIT:
  114                         sbuf_printf(sb, " EXIT");
  115                         break;
  116                 case TS_THREAD:
  117                         sbuf_printf(sb, " THREAD");
  118                         break;
  119                 case TS_EVENT:
  120                         sbuf_printf(sb, " EVENT");
  121                         break;
  122                 }
  123                 sbuf_printf(sb, " %s", timestamps[i].f ? timestamps[i].f : "(null)");
  124                 if (timestamps[i].s)
  125                         sbuf_printf(sb, " %s\n", timestamps[i].s);
  126                 else
  127                         sbuf_printf(sb, "\n");
  128         }
  129         error = sbuf_finish(sb);
  130         sbuf_delete(sb);
  131         return (error);
  132 }
  133 
  134 SYSCTL_PROC(_debug, OID_AUTO, tslog,
  135     CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_SKIP,
  136     0, 0, sysctl_debug_tslog, "", "Dump recorded event timestamps");
  137 
  138 MALLOC_DEFINE(M_TSLOGUSER, "tsloguser", "Strings used by userland tslog");
  139 static struct procdata {
  140         pid_t ppid;
  141         uint64_t tsc_forked;
  142         uint64_t tsc_exited;
  143         char * execname;
  144         char * namei;
  145         int reused;
  146 } procs[PID_MAX + 1];
  147 
  148 void
  149 tslog_user(pid_t pid, pid_t ppid, const char * execname, const char * namei)
  150 {
  151         uint64_t tsc = get_cyclecount();
  152 
  153         /* If we wrapped, do nothing. */
  154         if (procs[pid].reused)
  155                 return;
  156 
  157         /* If we have a ppid, we're recording a fork. */
  158         if (ppid != (pid_t)(-1)) {
  159                 /* If we have a ppid already, we wrapped. */
  160                 if (procs[pid].ppid) {
  161                         procs[pid].reused = 1;
  162                         return;
  163                 }
  164 
  165                 /* Fill in some fields. */
  166                 procs[pid].ppid = ppid;
  167                 procs[pid].tsc_forked = tsc;
  168                 return;
  169         }
  170 
  171         /* If we have an execname, record it. */
  172         if (execname != NULL) {
  173                 if (procs[pid].execname != NULL)
  174                         free(procs[pid].execname, M_TSLOGUSER);
  175                 procs[pid].execname = strdup(execname, M_TSLOGUSER);
  176                 return;
  177         }
  178 
  179         /* Record the first namei for the process. */
  180         if (namei != NULL) {
  181                 if (procs[pid].namei == NULL)
  182                         procs[pid].namei = strdup(namei, M_TSLOGUSER);
  183                 return;
  184         }
  185 
  186         /* Otherwise we're recording an exit. */
  187         procs[pid].tsc_exited = tsc;
  188 }
  189 
  190 static int
  191 sysctl_debug_tslog_user(SYSCTL_HANDLER_ARGS)
  192 {
  193         int error;
  194         struct sbuf *sb;
  195         pid_t pid;
  196 
  197         sb = sbuf_new_for_sysctl(NULL, NULL, 1024, req);
  198 
  199         /* Export the data we logged. */
  200         for (pid = 0; pid <= PID_MAX; pid++) {
  201                 sbuf_printf(sb, "%zu", (size_t)pid);
  202                 sbuf_printf(sb, " %zu", (size_t)procs[pid].ppid);
  203                 sbuf_printf(sb, " %llu",
  204                     (unsigned long long)procs[pid].tsc_forked);
  205                 sbuf_printf(sb, " %llu",
  206                     (unsigned long long)procs[pid].tsc_exited);
  207                 sbuf_printf(sb, " \"%s\"", procs[pid].execname ?
  208                     procs[pid].execname : "");
  209                 sbuf_printf(sb, " \"%s\"", procs[pid].namei ?
  210                     procs[pid].namei : "");
  211                 sbuf_printf(sb, "\n");
  212         }
  213         error = sbuf_finish(sb);
  214         sbuf_delete(sb);
  215         return (error);
  216 }
  217 
  218 SYSCTL_PROC(_debug, OID_AUTO, tslog_user,
  219     CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE|CTLFLAG_SKIP,
  220     0, 0, sysctl_debug_tslog_user,
  221     "", "Dump recorded userland event timestamps");

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

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