swh:1:snp:c2847dfd741eae21606027cf29250d1ebcd63fb4
Tip revision: 2ef96a5bb12be62ef75b5828c0aab838ebb29cb8 authored by Linus Torvalds on 10 May 2020, 22:16:58 UTC
Linux 5.7-rc5
Linux 5.7-rc5
Tip revision: 2ef96a5
builtin-ftrace.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* builtin-ftrace.c
*
* Copyright (c) 2013 LG Electronics, Namhyung Kim <namhyung@kernel.org>
*/
#include "builtin.h"
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <fcntl.h>
#include <poll.h>
#include <linux/capability.h>
#include <linux/string.h>
#include "debug.h"
#include <subcmd/pager.h>
#include <subcmd/parse-options.h>
#include <api/fs/tracing_path.h>
#include "evlist.h"
#include "target.h"
#include "cpumap.h"
#include "thread_map.h"
#include "util/cap.h"
#include "util/config.h"
#define DEFAULT_TRACER "function_graph"
struct perf_ftrace {
struct evlist *evlist;
struct target target;
const char *tracer;
struct list_head filters;
struct list_head notrace;
struct list_head graph_funcs;
struct list_head nograph_funcs;
int graph_depth;
};
struct filter_entry {
struct list_head list;
char name[];
};
static bool done;
static void sig_handler(int sig __maybe_unused)
{
done = true;
}
/*
* perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
* we asked by setting its exec_error to the function below,
* ftrace__workload_exec_failed_signal.
*
* XXX We need to handle this more appropriately, emitting an error, etc.
*/
static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
siginfo_t *info __maybe_unused,
void *ucontext __maybe_unused)
{
/* workload_exec_errno = info->si_value.sival_int; */
done = true;
}
static int __write_tracing_file(const char *name, const char *val, bool append)
{
char *file;
int fd, ret = -1;
ssize_t size = strlen(val);
int flags = O_WRONLY;
char errbuf[512];
char *val_copy;
file = get_tracing_file(name);
if (!file) {
pr_debug("cannot get tracing file: %s\n", name);
return -1;
}
if (append)
flags |= O_APPEND;
else
flags |= O_TRUNC;
fd = open(file, flags);
if (fd < 0) {
pr_debug("cannot open tracing file: %s: %s\n",
name, str_error_r(errno, errbuf, sizeof(errbuf)));
goto out;
}
/*
* Copy the original value and append a '\n'. Without this,
* the kernel can hide possible errors.
*/
val_copy = strdup(val);
if (!val_copy)
goto out_close;
val_copy[size] = '\n';
if (write(fd, val_copy, size + 1) == size + 1)
ret = 0;
else
pr_debug("write '%s' to tracing/%s failed: %s\n",
val, name, str_error_r(errno, errbuf, sizeof(errbuf)));
free(val_copy);
out_close:
close(fd);
out:
put_tracing_file(file);
return ret;
}
static int write_tracing_file(const char *name, const char *val)
{
return __write_tracing_file(name, val, false);
}
static int append_tracing_file(const char *name, const char *val)
{
return __write_tracing_file(name, val, true);
}
static int reset_tracing_cpu(void);
static void reset_tracing_filters(void);
static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
{
if (write_tracing_file("tracing_on", "0") < 0)
return -1;
if (write_tracing_file("current_tracer", "nop") < 0)
return -1;
if (write_tracing_file("set_ftrace_pid", " ") < 0)
return -1;
if (reset_tracing_cpu() < 0)
return -1;
if (write_tracing_file("max_graph_depth", "0") < 0)
return -1;
reset_tracing_filters();
return 0;
}
static int set_tracing_pid(struct perf_ftrace *ftrace)
{
int i;
char buf[16];
if (target__has_cpu(&ftrace->target))
return 0;
for (i = 0; i < perf_thread_map__nr(ftrace->evlist->core.threads); i++) {
scnprintf(buf, sizeof(buf), "%d",
ftrace->evlist->core.threads->map[i]);
if (append_tracing_file("set_ftrace_pid", buf) < 0)
return -1;
}
return 0;
}
static int set_tracing_cpumask(struct perf_cpu_map *cpumap)
{
char *cpumask;
size_t mask_size;
int ret;
int last_cpu;
last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1);
mask_size = last_cpu / 4 + 2; /* one more byte for EOS */
mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */
cpumask = malloc(mask_size);
if (cpumask == NULL) {
pr_debug("failed to allocate cpu mask\n");
return -1;
}
cpu_map__snprint_mask(cpumap, cpumask, mask_size);
ret = write_tracing_file("tracing_cpumask", cpumask);
free(cpumask);
return ret;
}
static int set_tracing_cpu(struct perf_ftrace *ftrace)
{
struct perf_cpu_map *cpumap = ftrace->evlist->core.cpus;
if (!target__has_cpu(&ftrace->target))
return 0;
return set_tracing_cpumask(cpumap);
}
static int reset_tracing_cpu(void)
{
struct perf_cpu_map *cpumap = perf_cpu_map__new(NULL);
int ret;
ret = set_tracing_cpumask(cpumap);
perf_cpu_map__put(cpumap);
return ret;
}
static int __set_tracing_filter(const char *filter_file, struct list_head *funcs)
{
struct filter_entry *pos;
list_for_each_entry(pos, funcs, list) {
if (append_tracing_file(filter_file, pos->name) < 0)
return -1;
}
return 0;
}
static int set_tracing_filters(struct perf_ftrace *ftrace)
{
int ret;
ret = __set_tracing_filter("set_ftrace_filter", &ftrace->filters);
if (ret < 0)
return ret;
ret = __set_tracing_filter("set_ftrace_notrace", &ftrace->notrace);
if (ret < 0)
return ret;
ret = __set_tracing_filter("set_graph_function", &ftrace->graph_funcs);
if (ret < 0)
return ret;
/* old kernels do not have this filter */
__set_tracing_filter("set_graph_notrace", &ftrace->nograph_funcs);
return ret;
}
static void reset_tracing_filters(void)
{
write_tracing_file("set_ftrace_filter", " ");
write_tracing_file("set_ftrace_notrace", " ");
write_tracing_file("set_graph_function", " ");
write_tracing_file("set_graph_notrace", " ");
}
static int set_tracing_depth(struct perf_ftrace *ftrace)
{
char buf[16];
if (ftrace->graph_depth == 0)
return 0;
if (ftrace->graph_depth < 0) {
pr_err("invalid graph depth: %d\n", ftrace->graph_depth);
return -1;
}
snprintf(buf, sizeof(buf), "%d", ftrace->graph_depth);
if (write_tracing_file("max_graph_depth", buf) < 0)
return -1;
return 0;
}
static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
{
char *trace_file;
int trace_fd;
char buf[4096];
struct pollfd pollfd = {
.events = POLLIN,
};
if (!perf_cap__capable(CAP_SYS_ADMIN)) {
pr_err("ftrace only works for %s!\n",
#ifdef HAVE_LIBCAP_SUPPORT
"users with the SYS_ADMIN capability"
#else
"root"
#endif
);
return -1;
}
signal(SIGINT, sig_handler);
signal(SIGUSR1, sig_handler);
signal(SIGCHLD, sig_handler);
signal(SIGPIPE, sig_handler);
if (reset_tracing_files(ftrace) < 0) {
pr_err("failed to reset ftrace\n");
goto out;
}
/* reset ftrace buffer */
if (write_tracing_file("trace", "0") < 0)
goto out;
if (argc && perf_evlist__prepare_workload(ftrace->evlist,
&ftrace->target, argv, false,
ftrace__workload_exec_failed_signal) < 0) {
goto out;
}
if (set_tracing_pid(ftrace) < 0) {
pr_err("failed to set ftrace pid\n");
goto out_reset;
}
if (set_tracing_cpu(ftrace) < 0) {
pr_err("failed to set tracing cpumask\n");
goto out_reset;
}
if (set_tracing_filters(ftrace) < 0) {
pr_err("failed to set tracing filters\n");
goto out_reset;
}
if (set_tracing_depth(ftrace) < 0) {
pr_err("failed to set graph depth\n");
goto out_reset;
}
if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
goto out_reset;
}
setup_pager();
trace_file = get_tracing_file("trace_pipe");
if (!trace_file) {
pr_err("failed to open trace_pipe\n");
goto out_reset;
}
trace_fd = open(trace_file, O_RDONLY);
put_tracing_file(trace_file);
if (trace_fd < 0) {
pr_err("failed to open trace_pipe\n");
goto out_reset;
}
fcntl(trace_fd, F_SETFL, O_NONBLOCK);
pollfd.fd = trace_fd;
if (write_tracing_file("tracing_on", "1") < 0) {
pr_err("can't enable tracing\n");
goto out_close_fd;
}
perf_evlist__start_workload(ftrace->evlist);
while (!done) {
if (poll(&pollfd, 1, -1) < 0)
break;
if (pollfd.revents & POLLIN) {
int n = read(trace_fd, buf, sizeof(buf));
if (n < 0)
break;
if (fwrite(buf, n, 1, stdout) != 1)
break;
}
}
write_tracing_file("tracing_on", "0");
/* read remaining buffer contents */
while (true) {
int n = read(trace_fd, buf, sizeof(buf));
if (n <= 0)
break;
if (fwrite(buf, n, 1, stdout) != 1)
break;
}
out_close_fd:
close(trace_fd);
out_reset:
reset_tracing_files(ftrace);
out:
return done ? 0 : -1;
}
static int perf_ftrace_config(const char *var, const char *value, void *cb)
{
struct perf_ftrace *ftrace = cb;
if (!strstarts(var, "ftrace."))
return 0;
if (strcmp(var, "ftrace.tracer"))
return -1;
if (!strcmp(value, "function_graph") ||
!strcmp(value, "function")) {
ftrace->tracer = value;
return 0;
}
pr_err("Please select \"function_graph\" (default) or \"function\"\n");
return -1;
}
static int parse_filter_func(const struct option *opt, const char *str,
int unset __maybe_unused)
{
struct list_head *head = opt->value;
struct filter_entry *entry;
entry = malloc(sizeof(*entry) + strlen(str) + 1);
if (entry == NULL)
return -ENOMEM;
strcpy(entry->name, str);
list_add_tail(&entry->list, head);
return 0;
}
static void delete_filter_func(struct list_head *head)
{
struct filter_entry *pos, *tmp;
list_for_each_entry_safe(pos, tmp, head, list) {
list_del_init(&pos->list);
free(pos);
}
}
int cmd_ftrace(int argc, const char **argv)
{
int ret;
struct perf_ftrace ftrace = {
.tracer = DEFAULT_TRACER,
.target = { .uid = UINT_MAX, },
};
const char * const ftrace_usage[] = {
"perf ftrace [<options>] [<command>]",
"perf ftrace [<options>] -- <command> [<options>]",
NULL
};
const struct option ftrace_options[] = {
OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
"tracer to use: function_graph(default) or function"),
OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
"trace on existing process id"),
OPT_INCR('v', "verbose", &verbose,
"be more verbose"),
OPT_BOOLEAN('a', "all-cpus", &ftrace.target.system_wide,
"system-wide collection from all CPUs"),
OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",
"list of cpus to monitor"),
OPT_CALLBACK('T', "trace-funcs", &ftrace.filters, "func",
"trace given functions only", parse_filter_func),
OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",
"do not trace given functions", parse_filter_func),
OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",
"Set graph filter on given functions", parse_filter_func),
OPT_CALLBACK('g', "nograph-funcs", &ftrace.nograph_funcs, "func",
"Set nograph filter on given functions", parse_filter_func),
OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
"Max depth for function graph tracer"),
OPT_END()
};
INIT_LIST_HEAD(&ftrace.filters);
INIT_LIST_HEAD(&ftrace.notrace);
INIT_LIST_HEAD(&ftrace.graph_funcs);
INIT_LIST_HEAD(&ftrace.nograph_funcs);
ret = perf_config(perf_ftrace_config, &ftrace);
if (ret < 0)
return -1;
argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
PARSE_OPT_STOP_AT_NON_OPTION);
if (!argc && target__none(&ftrace.target))
usage_with_options(ftrace_usage, ftrace_options);
ret = target__validate(&ftrace.target);
if (ret) {
char errbuf[512];
target__strerror(&ftrace.target, ret, errbuf, 512);
pr_err("%s\n", errbuf);
goto out_delete_filters;
}
ftrace.evlist = evlist__new();
if (ftrace.evlist == NULL) {
ret = -ENOMEM;
goto out_delete_filters;
}
ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
if (ret < 0)
goto out_delete_evlist;
ret = __cmd_ftrace(&ftrace, argc, argv);
out_delete_evlist:
evlist__delete(ftrace.evlist);
out_delete_filters:
delete_filter_func(&ftrace.filters);
delete_filter_func(&ftrace.notrace);
delete_filter_func(&ftrace.graph_funcs);
delete_filter_func(&ftrace.nograph_funcs);
return ret;
}