freebsd-dev/sys/kern/kern_tslog.c
Colin Percival 52e125c2bd TSLOG: Report final execname, not first
In cases such as daemons launched via limits(1), a process may call
exec multiple times; the last name of the last binary executed is
usually (always?) more informative.

Fixes:	46dd801acb Add userland boot profiling to TSLOG
Sponsored by:	https://www.patreon.com/cperciva
2021-10-17 13:36:38 -07:00

220 lines
6.0 KiB
C

/*-
* Copyright (c) 2017 Colin Percival
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/linker.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/tslog.h>
#include <machine/atomic.h>
#include <machine/cpu.h>
#ifndef TSLOGSIZE
#define TSLOGSIZE 262144
#endif
static volatile long nrecs = 0;
static struct timestamp {
void * td;
int type;
const char * f;
const char * s;
uint64_t tsc;
} timestamps[TSLOGSIZE];
void
tslog(void * td, int type, const char * f, const char * s)
{
uint64_t tsc = get_cyclecount();
long pos;
/* Grab a slot. */
pos = atomic_fetchadd_long(&nrecs, 1);
/* Store record. */
if (pos < nitems(timestamps)) {
timestamps[pos].td = td;
timestamps[pos].type = type;
timestamps[pos].f = f;
timestamps[pos].s = s;
timestamps[pos].tsc = tsc;
}
}
static int
sysctl_debug_tslog(SYSCTL_HANDLER_ARGS)
{
int error;
struct sbuf *sb;
size_t i, limit;
caddr_t loader_tslog;
void * loader_tslog_buf;
size_t loader_tslog_len;
/*
* This code can race against the code in tslog() which stores
* records: Theoretically we could end up reading a record after
* its slots have been reserved but before it has been written.
* Since this code takes orders of magnitude longer to run than
* tslog() takes to write a record, it is highly unlikely that
* anyone will ever experience this race.
*/
sb = sbuf_new_for_sysctl(NULL, NULL, 1024, req);
/* Get data from the boot loader, if it provided any. */
loader_tslog = preload_search_by_type("TSLOG data");
if (loader_tslog != NULL) {
loader_tslog_buf = preload_fetch_addr(loader_tslog);
loader_tslog_len = preload_fetch_size(loader_tslog);
sbuf_bcat(sb, loader_tslog_buf, loader_tslog_len);
}
/* Add data logged within the kernel. */
limit = MIN(nrecs, nitems(timestamps));
for (i = 0; i < limit; i++) {
sbuf_printf(sb, "%p", timestamps[i].td);
sbuf_printf(sb, " %llu",
(unsigned long long)timestamps[i].tsc);
switch (timestamps[i].type) {
case TS_ENTER:
sbuf_printf(sb, " ENTER");
break;
case TS_EXIT:
sbuf_printf(sb, " EXIT");
break;
case TS_THREAD:
sbuf_printf(sb, " THREAD");
break;
case TS_EVENT:
sbuf_printf(sb, " EVENT");
break;
}
sbuf_printf(sb, " %s", timestamps[i].f ? timestamps[i].f : "(null)");
if (timestamps[i].s)
sbuf_printf(sb, " %s\n", timestamps[i].s);
else
sbuf_printf(sb, "\n");
}
error = sbuf_finish(sb);
sbuf_delete(sb);
return (error);
}
SYSCTL_PROC(_debug, OID_AUTO, tslog, CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE,
0, 0, sysctl_debug_tslog, "", "Dump recorded event timestamps");
MALLOC_DEFINE(M_TSLOGUSER, "tsloguser", "Strings used by userland tslog");
static struct procdata {
pid_t ppid;
uint64_t tsc_forked;
uint64_t tsc_exited;
char * execname;
char * namei;
int reused;
} procs[PID_MAX + 1];
void
tslog_user(pid_t pid, pid_t ppid, const char * execname, const char * namei)
{
uint64_t tsc = get_cyclecount();
/* If we wrapped, do nothing. */
if (procs[pid].reused)
return;
/* If we have a ppid, we're recording a fork. */
if (ppid != (pid_t)(-1)) {
/* If we have a ppid already, we wrapped. */
if (procs[pid].ppid) {
procs[pid].reused = 1;
return;
}
/* Fill in some fields. */
procs[pid].ppid = ppid;
procs[pid].tsc_forked = tsc;
return;
}
/* If we have an execname, record it. */
if (execname != NULL) {
if (procs[pid].execname != NULL)
free(procs[pid].execname, M_TSLOGUSER);
procs[pid].execname = strdup(execname, M_TSLOGUSER);
return;
}
/* Record the first namei for the process. */
if (namei != NULL) {
if (procs[pid].namei == NULL)
procs[pid].namei = strdup(namei, M_TSLOGUSER);
return;
}
/* Otherwise we're recording an exit. */
procs[pid].tsc_exited = tsc;
}
static int
sysctl_debug_tslog_user(SYSCTL_HANDLER_ARGS)
{
int error;
struct sbuf *sb;
pid_t pid;
sb = sbuf_new_for_sysctl(NULL, NULL, 1024, req);
/* Export the data we logged. */
for (pid = 0; pid <= PID_MAX; pid++) {
sbuf_printf(sb, "%zu", (size_t)pid);
sbuf_printf(sb, " %zu", (size_t)procs[pid].ppid);
sbuf_printf(sb, " %llu",
(unsigned long long)procs[pid].tsc_forked);
sbuf_printf(sb, " %llu",
(unsigned long long)procs[pid].tsc_exited);
sbuf_printf(sb, " \"%s\"", procs[pid].execname ?
procs[pid].execname : "");
sbuf_printf(sb, " \"%s\"", procs[pid].namei ?
procs[pid].namei : "");
sbuf_printf(sb, "\n");
}
error = sbuf_finish(sb);
sbuf_delete(sb);
return (error);
}
SYSCTL_PROC(_debug, OID_AUTO, tslog_user,
CTLTYPE_STRING|CTLFLAG_RD|CTLFLAG_MPSAFE, 0, 0, sysctl_debug_tslog_user,
"", "Dump recorded userland event timestamps");