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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2009, 2010 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <getopt.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include "tracefs.h"
#include "trace-local.h"
#define PROC_FILE "/proc/sys/kernel/stack_tracer_enabled"
enum stack_type {
STACK_START,
STACK_STOP,
STACK_RESET,
STACK_REPORT
};
static void test_available(void)
{
struct stat buf;
int fd;
fd = stat(PROC_FILE, &buf);
if (fd < 0)
die("stack tracer not configured on running kernel");
}
/* NOTE: this implementation only accepts new_status in the range [0..9]. */
static void change_stack_tracer_status(unsigned new_status)
{
char buf[1];
int status;
int ret;
int fd;
int n;
if (new_status > 9) {
warning("invalid status %d\n", new_status);
return;
}
ret = tracecmd_stack_tracer_status(&status);
if (ret < 0)
die("error reading %s", PROC_FILE);
if (ret > 0 && status == new_status)
return; /* nothing to do */
fd = open(PROC_FILE, O_WRONLY);
if (fd < 0)
die("writing %s", PROC_FILE);
buf[0] = new_status + '0';
n = write(fd, buf, 1);
if (n < 0)
die("writing into %s", PROC_FILE);
close(fd);
}
static void start_trace(void)
{
change_stack_tracer_status(1);
}
static void stop_trace(void)
{
change_stack_tracer_status(0);
}
static void reset_trace(void)
{
char *path;
char buf[1];
int fd;
int n;
path = tracefs_get_tracing_file("stack_max_size");
fd = open(path, O_WRONLY);
if (fd < 0)
die("writing %s", path);
buf[0] = '0';
n = write(fd, buf, 1);
if (n < 0)
die("writing into %s", path);
tracefs_put_tracing_file(path);
close(fd);
}
static void read_trace(void)
{
char *buf = NULL;
int status;
char *path;
FILE *fp;
size_t n;
int r;
if (tracecmd_stack_tracer_status(&status) <= 0)
die("Invalid stack tracer state");
if (status > 0)
printf("(stack tracer running)\n");
else
printf("(stack tracer not running)\n");
path = tracefs_get_tracing_file("stack_trace");
fp = fopen(path, "r");
if (!fp)
die("reading to '%s'", path);
tracefs_put_tracing_file(path);
while ((r = getline(&buf, &n, fp)) >= 0) {
/*
* Skip any line that starts with a '#'.
* Those talk about how to enable stack tracing
* within the debugfs system. We don't care about that.
*/
if (buf[0] != '#')
printf("%s", buf);
free(buf);
buf = NULL;
}
fclose(fp);
}
enum {
OPT_verbose = 252,
OPT_reset = 253,
OPT_stop = 254,
OPT_start = 255,
};
void trace_stack (int argc, char **argv)
{
enum stack_type trace_type = STACK_REPORT;
int c;
if (argc < 2)
usage(argv);
if (strcmp(argv[1], "stack") != 0)
usage(argv);
for (;;) {
int option_index = 0;
static struct option long_options[] = {
{"start", no_argument, NULL, OPT_start},
{"stop", no_argument, NULL, OPT_stop},
{"reset", no_argument, NULL, OPT_reset},
{"help", no_argument, NULL, '?'},
{"verbose", optional_argument, NULL, OPT_verbose},
{NULL, 0, NULL, 0}
};
c = getopt_long (argc-1, argv+1, "+h?",
long_options, &option_index);
if (c == -1)
break;
switch (c) {
case 'h':
usage(argv);
break;
case OPT_start:
trace_type = STACK_START;
break;
case OPT_stop:
trace_type = STACK_STOP;
break;
case OPT_reset:
trace_type = STACK_RESET;
break;
case OPT_verbose:
if (trace_set_verbose(optarg) < 0)
die("invalid verbose level %s", optarg);
break;
default:
usage(argv);
}
}
test_available();
switch (trace_type) {
case STACK_START:
start_trace();
break;
case STACK_STOP:
stop_trace();
break;
case STACK_RESET:
reset_trace();
break;
default:
read_trace();
break;
}
return;
}
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