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builtin-ftrace.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* builtin-ftrace.c
*
* Copyright (c) 2013 LG Electronics, Namhyung Kim <[email protected]>
* Copyright (c) 2020 Changbin Du <[email protected]>, significant enhancement.
*/
#include "builtin.h"
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <fcntl.h>
#include <math.h>
#include <poll.h>
#include <ctype.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 "strfilter.h"
#include "util/cap.h"
#include "util/config.h"
#include "util/ftrace.h"
#include "util/units.h"
#include "util/parse-sublevel-options.h"
#define DEFAULT_TRACER "function_graph"
static volatile sig_atomic_t workload_exec_errno;
static volatile sig_atomic_t done;
static void sig_handler(int sig __maybe_unused)
{
done = true;
}
/*
* 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 read_tracing_file_to_stdout(const char *name)
{
char buf[4096];
char *file;
int fd;
int ret = -1;
file = get_tracing_file(name);
if (!file) {
pr_debug("cannot get tracing file: %s\n", name);
return -1;
}
fd = open(file, O_RDONLY);
if (fd < 0) {
pr_debug("cannot open tracing file: %s: %s\n",
name, str_error_r(errno, buf, sizeof(buf)));
goto out;
}
/* read contents to stdout */
while (true) {
int n = read(fd, buf, sizeof(buf));
if (n == 0)
break;
else if (n < 0)
goto out_close;
if (fwrite(buf, n, 1, stdout) != 1)
goto out_close;
}
ret = 0;
out_close:
close(fd);
out:
put_tracing_file(file);
return ret;
}
static int read_tracing_file_by_line(const char *name,
void (*cb)(char *str, void *arg),
void *cb_arg)
{
char *line = NULL;
size_t len = 0;
char *file;
FILE *fp;
file = get_tracing_file(name);
if (!file) {
pr_debug("cannot get tracing file: %s\n", name);
return -1;
}
fp = fopen(file, "r");
if (fp == NULL) {
pr_debug("cannot open tracing file: %s\n", name);
put_tracing_file(file);
return -1;
}
while (getline(&line, &len, fp) != -1) {
cb(line, cb_arg);
}
if (line)
free(line);
fclose(fp);
put_tracing_file(file);
return 0;
}
static int write_tracing_file_int(const char *name, int value)
{
char buf[16];
snprintf(buf, sizeof(buf), "%d", value);
if (write_tracing_file(name, buf) < 0)
return -1;
return 0;
}
static int write_tracing_option_file(const char *name, const char *val)
{
char *file;
int ret;
if (asprintf(&file, "options/%s", name) < 0)
return -1;
ret = __write_tracing_file(file, val, false);
free(file);
return ret;
}
static int reset_tracing_cpu(void);
static void reset_tracing_filters(void);
static void reset_tracing_options(struct perf_ftrace *ftrace __maybe_unused)
{
write_tracing_option_file("function-fork", "0");
write_tracing_option_file("func_stack_trace", "0");
write_tracing_option_file("sleep-time", "1");
write_tracing_option_file("funcgraph-irqs", "1");
write_tracing_option_file("funcgraph-proc", "0");
write_tracing_option_file("funcgraph-abstime", "0");
write_tracing_option_file("latency-format", "0");
write_tracing_option_file("irq-info", "0");
}
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;
if (write_tracing_file("tracing_thresh", "0") < 0)
return -1;
reset_tracing_filters();
reset_tracing_options(ftrace);
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",
perf_thread_map__pid(ftrace->evlist->core.threads, 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 = perf_cpu_map__cpu(cpumap, perf_cpu_map__nr(cpumap) - 1).cpu;
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.user_requested_cpus;
if (!target__has_cpu(&ftrace->target))
return 0;
return set_tracing_cpumask(cpumap);
}
static int set_tracing_func_stack_trace(struct perf_ftrace *ftrace)
{
if (!ftrace->func_stack_trace)
return 0;
if (write_tracing_option_file("func_stack_trace", "1") < 0)
return -1;
return 0;
}
static int set_tracing_func_irqinfo(struct perf_ftrace *ftrace)
{
if (!ftrace->func_irq_info)
return 0;
if (write_tracing_option_file("irq-info", "1") < 0)
return -1;
return 0;
}
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)
{
if (ftrace->graph_depth == 0)
return 0;
if (ftrace->graph_depth < 0) {
pr_err("invalid graph depth: %d\n", ftrace->graph_depth);
return -1;
}
if (write_tracing_file_int("max_graph_depth", ftrace->graph_depth) < 0)
return -1;
return 0;
}
static int set_tracing_percpu_buffer_size(struct perf_ftrace *ftrace)
{
int ret;
if (ftrace->percpu_buffer_size == 0)
return 0;
ret = write_tracing_file_int("buffer_size_kb",
ftrace->percpu_buffer_size / 1024);
if (ret < 0)
return ret;
return 0;
}
static int set_tracing_trace_inherit(struct perf_ftrace *ftrace)
{
if (!ftrace->inherit)
return 0;
if (write_tracing_option_file("function-fork", "1") < 0)
return -1;
return 0;
}
static int set_tracing_sleep_time(struct perf_ftrace *ftrace)
{
if (!ftrace->graph_nosleep_time)
return 0;
if (write_tracing_option_file("sleep-time", "0") < 0)
return -1;
return 0;
}
static int set_tracing_funcgraph_irqs(struct perf_ftrace *ftrace)
{
if (!ftrace->graph_noirqs)
return 0;
if (write_tracing_option_file("funcgraph-irqs", "0") < 0)
return -1;
return 0;
}
static int set_tracing_funcgraph_verbose(struct perf_ftrace *ftrace)
{
if (!ftrace->graph_verbose)
return 0;
if (write_tracing_option_file("funcgraph-proc", "1") < 0)
return -1;
if (write_tracing_option_file("funcgraph-abstime", "1") < 0)
return -1;
if (write_tracing_option_file("latency-format", "1") < 0)
return -1;
return 0;
}
static int set_tracing_thresh(struct perf_ftrace *ftrace)
{
int ret;
if (ftrace->graph_thresh == 0)
return 0;
ret = write_tracing_file_int("tracing_thresh", ftrace->graph_thresh);
if (ret < 0)
return ret;
return 0;
}
static int set_tracing_options(struct perf_ftrace *ftrace)
{
if (set_tracing_pid(ftrace) < 0) {
pr_err("failed to set ftrace pid\n");
return -1;
}
if (set_tracing_cpu(ftrace) < 0) {
pr_err("failed to set tracing cpumask\n");
return -1;
}
if (set_tracing_func_stack_trace(ftrace) < 0) {
pr_err("failed to set tracing option func_stack_trace\n");
return -1;
}
if (set_tracing_func_irqinfo(ftrace) < 0) {
pr_err("failed to set tracing option irq-info\n");
return -1;
}
if (set_tracing_filters(ftrace) < 0) {
pr_err("failed to set tracing filters\n");
return -1;
}
if (set_tracing_depth(ftrace) < 0) {
pr_err("failed to set graph depth\n");
return -1;
}
if (set_tracing_percpu_buffer_size(ftrace) < 0) {
pr_err("failed to set tracing per-cpu buffer size\n");
return -1;
}
if (set_tracing_trace_inherit(ftrace) < 0) {
pr_err("failed to set tracing option function-fork\n");
return -1;
}
if (set_tracing_sleep_time(ftrace) < 0) {
pr_err("failed to set tracing option sleep-time\n");
return -1;
}
if (set_tracing_funcgraph_irqs(ftrace) < 0) {
pr_err("failed to set tracing option funcgraph-irqs\n");
return -1;
}
if (set_tracing_funcgraph_verbose(ftrace) < 0) {
pr_err("failed to set tracing option funcgraph-proc/funcgraph-abstime\n");
return -1;
}
if (set_tracing_thresh(ftrace) < 0) {
pr_err("failed to set tracing thresh\n");
return -1;
}
return 0;
}
static void select_tracer(struct perf_ftrace *ftrace)
{
bool graph = !list_empty(&ftrace->graph_funcs) ||
!list_empty(&ftrace->nograph_funcs);
bool func = !list_empty(&ftrace->filters) ||
!list_empty(&ftrace->notrace);
/* The function_graph has priority over function tracer. */
if (graph)
ftrace->tracer = "function_graph";
else if (func)
ftrace->tracer = "function";
/* Otherwise, the default tracer is used. */
pr_debug("%s tracer is used\n", ftrace->tracer);
}
static int __cmd_ftrace(struct perf_ftrace *ftrace)
{
char *trace_file;
int trace_fd;
char buf[4096];
struct pollfd pollfd = {
.events = POLLIN,
};
if (!(perf_cap__capable(CAP_PERFMON) ||
perf_cap__capable(CAP_SYS_ADMIN))) {
pr_err("ftrace only works for %s!\n",
#ifdef HAVE_LIBCAP_SUPPORT
"users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
#else
"root"
#endif
);
return -1;
}
select_tracer(ftrace);
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 (set_tracing_options(ftrace) < 0)
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;
/* display column headers */
read_tracing_file_to_stdout("trace");
if (!ftrace->target.initial_delay) {
if (write_tracing_file("tracing_on", "1") < 0) {
pr_err("can't enable tracing\n");
goto out_close_fd;
}
}
evlist__start_workload(ftrace->evlist);
if (ftrace->target.initial_delay > 0) {
usleep(ftrace->target.initial_delay * 1000);
if (write_tracing_file("tracing_on", "1") < 0) {
pr_err("can't enable tracing\n");
goto out_close_fd;
}
}
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;
/* flush output since stdout is in full buffering mode due to pager */
fflush(stdout);
}
}
write_tracing_file("tracing_on", "0");
if (workload_exec_errno) {
const char *emsg = str_error_r(workload_exec_errno, buf, sizeof(buf));
/* flush stdout first so below error msg appears at the end. */
fflush(stdout);
pr_err("workload failed: %s\n", emsg);
goto out_close_fd;
}
/* 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 && !workload_exec_errno) ? 0 : -1;
}
static void make_histogram(int buckets[], char *buf, size_t len, char *linebuf,
bool use_nsec)
{
char *p, *q;
char *unit;
double num;
int i;
/* ensure NUL termination */
buf[len] = '\0';
/* handle data line by line */
for (p = buf; (q = strchr(p, '\n')) != NULL; p = q + 1) {
*q = '\0';
/* move it to the line buffer */
strcat(linebuf, p);
/*
* parse trace output to get function duration like in
*
* # tracer: function_graph
* #
* # CPU DURATION FUNCTION CALLS
* # | | | | | | |
* 1) + 10.291 us | do_filp_open();
* 1) 4.889 us | do_filp_open();
* 1) 6.086 us | do_filp_open();
*
*/
if (linebuf[0] == '#')
goto next;
/* ignore CPU */
p = strchr(linebuf, ')');
if (p == NULL)
p = linebuf;
while (*p && !isdigit(*p) && (*p != '|'))
p++;
/* no duration */
if (*p == '\0' || *p == '|')
goto next;
num = strtod(p, &unit);
if (!unit || strncmp(unit, " us", 3))
goto next;
if (use_nsec)
num *= 1000;
i = log2(num);
if (i < 0)
i = 0;
if (i >= NUM_BUCKET)
i = NUM_BUCKET - 1;
buckets[i]++;
next:
/* empty the line buffer for the next output */
linebuf[0] = '\0';
}
/* preserve any remaining output (before newline) */
strcat(linebuf, p);
}
static void display_histogram(int buckets[], bool use_nsec)
{
int i;
int total = 0;
int bar_total = 46; /* to fit in 80 column */
char bar[] = "###############################################";
int bar_len;
for (i = 0; i < NUM_BUCKET; i++)
total += buckets[i];
if (total == 0) {
printf("No data found\n");
return;
}
printf("# %14s | %10s | %-*s |\n",
" DURATION ", "COUNT", bar_total, "GRAPH");
bar_len = buckets[0] * bar_total / total;
printf(" %4d - %-4d %s | %10d | %.*s%*s |\n",
0, 1, "us", buckets[0], bar_len, bar, bar_total - bar_len, "");
for (i = 1; i < NUM_BUCKET - 1; i++) {
int start = (1 << (i - 1));
int stop = 1 << i;
const char *unit = use_nsec ? "ns" : "us";
if (start >= 1024) {
start >>= 10;
stop >>= 10;
unit = use_nsec ? "us" : "ms";
}
bar_len = buckets[i] * bar_total / total;
printf(" %4d - %-4d %s | %10d | %.*s%*s |\n",
start, stop, unit, buckets[i], bar_len, bar,
bar_total - bar_len, "");
}
bar_len = buckets[NUM_BUCKET - 1] * bar_total / total;
printf(" %4d - %-4s %s | %10d | %.*s%*s |\n",
1, "...", use_nsec ? "ms" : " s", buckets[NUM_BUCKET - 1],
bar_len, bar, bar_total - bar_len, "");
}
static int prepare_func_latency(struct perf_ftrace *ftrace)
{
char *trace_file;
int fd;
if (ftrace->target.use_bpf)
return perf_ftrace__latency_prepare_bpf(ftrace);
if (reset_tracing_files(ftrace) < 0) {
pr_err("failed to reset ftrace\n");
return -1;
}
/* reset ftrace buffer */
if (write_tracing_file("trace", "0") < 0)
return -1;
if (set_tracing_options(ftrace) < 0)
return -1;
/* force to use the function_graph tracer to track duration */
if (write_tracing_file("current_tracer", "function_graph") < 0) {
pr_err("failed to set current_tracer to function_graph\n");
return -1;
}
trace_file = get_tracing_file("trace_pipe");
if (!trace_file) {
pr_err("failed to open trace_pipe\n");
return -1;
}
fd = open(trace_file, O_RDONLY);
if (fd < 0)
pr_err("failed to open trace_pipe\n");
put_tracing_file(trace_file);
return fd;
}
static int start_func_latency(struct perf_ftrace *ftrace)
{
if (ftrace->target.use_bpf)
return perf_ftrace__latency_start_bpf(ftrace);
if (write_tracing_file("tracing_on", "1") < 0) {
pr_err("can't enable tracing\n");
return -1;
}
return 0;
}
static int stop_func_latency(struct perf_ftrace *ftrace)
{
if (ftrace->target.use_bpf)
return perf_ftrace__latency_stop_bpf(ftrace);
write_tracing_file("tracing_on", "0");
return 0;
}
static int read_func_latency(struct perf_ftrace *ftrace, int buckets[])
{
if (ftrace->target.use_bpf)
return perf_ftrace__latency_read_bpf(ftrace, buckets);
return 0;
}
static int cleanup_func_latency(struct perf_ftrace *ftrace)
{
if (ftrace->target.use_bpf)
return perf_ftrace__latency_cleanup_bpf(ftrace);
reset_tracing_files(ftrace);
return 0;
}
static int __cmd_latency(struct perf_ftrace *ftrace)
{
int trace_fd;
char buf[4096];
char line[256];
struct pollfd pollfd = {
.events = POLLIN,
};
int buckets[NUM_BUCKET] = { };
if (!(perf_cap__capable(CAP_PERFMON) ||
perf_cap__capable(CAP_SYS_ADMIN))) {
pr_err("ftrace only works for %s!\n",
#ifdef HAVE_LIBCAP_SUPPORT
"users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
#else
"root"
#endif
);
return -1;
}
trace_fd = prepare_func_latency(ftrace);
if (trace_fd < 0)
goto out;
fcntl(trace_fd, F_SETFL, O_NONBLOCK);
pollfd.fd = trace_fd;
if (start_func_latency(ftrace) < 0)
goto out;
evlist__start_workload(ftrace->evlist);
line[0] = '\0';
while (!done) {
if (poll(&pollfd, 1, -1) < 0)
break;
if (pollfd.revents & POLLIN) {
int n = read(trace_fd, buf, sizeof(buf) - 1);
if (n < 0)
break;
make_histogram(buckets, buf, n, line, ftrace->use_nsec);
}
}
stop_func_latency(ftrace);
if (workload_exec_errno) {
const char *emsg = str_error_r(workload_exec_errno, buf, sizeof(buf));
pr_err("workload failed: %s\n", emsg);
goto out;
}
/* read remaining buffer contents */
while (!ftrace->target.use_bpf) {
int n = read(trace_fd, buf, sizeof(buf) - 1);
if (n <= 0)
break;
make_histogram(buckets, buf, n, line, ftrace->use_nsec);
}
read_func_latency(ftrace, buckets);
display_histogram(buckets, ftrace->use_nsec);
out:
close(trace_fd);
cleanup_func_latency(ftrace);
return (done && !workload_exec_errno) ? 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 void list_function_cb(char *str, void *arg)
{
struct strfilter *filter = (struct strfilter *)arg;
if (strfilter__compare(filter, str))
printf("%s", str);
}
static int opt_list_avail_functions(const struct option *opt __maybe_unused,
const char *str, int unset)
{
struct strfilter *filter;
const char *err = NULL;
int ret;
if (unset || !str)
return -1;
filter = strfilter__new(str, &err);
if (!filter)
return err ? -EINVAL : -ENOMEM;
ret = strfilter__or(filter, str, &err);
if (ret == -EINVAL) {
pr_err("Filter parse error at %td.\n", err - str + 1);
pr_err("Source: \"%s\"\n", str);
pr_err(" %*c\n", (int)(err - str + 1), '^');
strfilter__delete(filter);