1 files changed, 977 insertions, 0 deletions

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
new file mode 100644
index 000000000..eecc70fc3
--- /dev/null
+++ b/tools/perf/builtin-ftrace.c
@@ -0,0 +1,977 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * builtin-ftrace.c
+ *
+ * Copyright (c) 2013  LG Electronics,  Namhyung Kim <namhyung@kernel.org>
+ * Copyright (c) 2020  Changbin Du <changbin.du@gmail.com>, significant enhancement.
+ */
+
+#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 "strfilter.h"
+#include "util/cap.h"
+#include "util/config.h"
+#include "util/units.h"
+#include "util/parse-sublevel-options.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;
+	unsigned long		percpu_buffer_size;
+	bool			inherit;
+	int			func_stack_trace;
+	int			func_irq_info;
+	int			graph_nosleep_time;
+	int			graph_noirqs;
+	int			graph_verbose;
+	int			graph_thresh;
+	unsigned int		initial_delay;
+};
+
+struct filter_entry {
+	struct list_head	list;
+	char			name[];
+};
+
+static volatile int workload_exec_errno;
+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 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 = 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 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 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_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;
+	}
+
+	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_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->initial_delay) {
+		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);
+
+	if (ftrace->initial_delay) {
+		usleep(ftrace->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;
+		}
+	}
+
+	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 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);
+		return ret;
+	}
+
+	ret = read_tracing_file_by_line("available_filter_functions",
+					list_function_cb, filter);
+	strfilter__delete(filter);
+	if (ret < 0)
+		return ret;
+
+	exit(0);
+}
+
+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);
+	}
+}
+
+static int parse_buffer_size(const struct option *opt,
+			     const char *str, int unset)
+{
+	unsigned long *s = (unsigned long *)opt->value;
+	static struct parse_tag tags_size[] = {
+		{ .tag  = 'B', .mult = 1       },
+		{ .tag  = 'K', .mult = 1 << 10 },
+		{ .tag  = 'M', .mult = 1 << 20 },
+		{ .tag  = 'G', .mult = 1 << 30 },
+		{ .tag  = 0 },
+	};
+	unsigned long val;
+
+	if (unset) {
+		*s = 0;
+		return 0;
+	}
+
+	val = parse_tag_value(str, tags_size);
+	if (val != (unsigned long) -1) {
+		if (val < 1024) {
+			pr_err("buffer size too small, must larger than 1KB.");
+			return -1;
+		}
+		*s = val;
+		return 0;
+	}
+
+	return -1;
+}
+
+static int parse_func_tracer_opts(const struct option *opt,
+				  const char *str, int unset)
+{
+	int ret;
+	struct perf_ftrace *ftrace = (struct perf_ftrace *) opt->value;
+	struct sublevel_option func_tracer_opts[] = {
+		{ .name = "call-graph",	.value_ptr = &ftrace->func_stack_trace },
+		{ .name = "irq-info",	.value_ptr = &ftrace->func_irq_info },
+		{ .name = NULL, }
+	};
+
+	if (unset)
+		return 0;
+
+	ret = perf_parse_sublevel_options(str, func_tracer_opts);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int parse_graph_tracer_opts(const struct option *opt,
+				  const char *str, int unset)
+{
+	int ret;
+	struct perf_ftrace *ftrace = (struct perf_ftrace *) opt->value;
+	struct sublevel_option graph_tracer_opts[] = {
+		{ .name = "nosleep-time",	.value_ptr = &ftrace->graph_nosleep_time },
+		{ .name = "noirqs",		.value_ptr = &ftrace->graph_noirqs },
+		{ .name = "verbose",		.value_ptr = &ftrace->graph_verbose },
+		{ .name = "thresh",		.value_ptr = &ftrace->graph_thresh },
+		{ .name = "depth",		.value_ptr = &ftrace->graph_depth },
+		{ .name = NULL, }
+	};
+
+	if (unset)
+		return 0;
+
+	ret = perf_parse_sublevel_options(str, graph_tracer_opts);
+	if (ret)
+		return ret;
+
+	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);
+}
+
+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_CALLBACK_DEFAULT('F', "funcs", NULL, "[FILTER]",
+			     "Show available functions to filter",
+			     opt_list_avail_functions, "*"),
+	OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
+		   "Trace on existing process id"),
+	/* TODO: Add short option -t after -t/--tracer can be removed. */
+	OPT_STRING(0, "tid", &ftrace.target.tid, "tid",
+		   "Trace on existing thread id (exclusive to --pid)"),
+	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 using function tracer",
+		     parse_filter_func),
+	OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",
+		     "Do not trace given functions", parse_filter_func),
+	OPT_CALLBACK(0, "func-opts", &ftrace, "options",
+		     "Function tracer options, available options: call-graph,irq-info",
+		     parse_func_tracer_opts),
+	OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",
+		     "Trace given functions using function_graph tracer",
+		     parse_filter_func),
+	OPT_CALLBACK('g', "nograph-funcs", &ftrace.nograph_funcs, "func",
+		     "Set nograph filter on given functions", parse_filter_func),
+	OPT_CALLBACK(0, "graph-opts", &ftrace, "options",
+		     "Graph tracer options, available options: nosleep-time,noirqs,verbose,thresh=<n>,depth=<n>",
+		     parse_graph_tracer_opts),
+	OPT_CALLBACK('m', "buffer-size", &ftrace.percpu_buffer_size, "size",
+		     "Size of per cpu buffer, needs to use a B, K, M or G suffix.", parse_buffer_size),
+	OPT_BOOLEAN(0, "inherit", &ftrace.inherit,
+		    "Trace children processes"),
+	OPT_UINTEGER('D', "delay", &ftrace.initial_delay,
+		     "Number of milliseconds to wait before starting tracing after program start"),
+	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))
+		ftrace.target.system_wide = true;
+
+	select_tracer(&ftrace);
+
+	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;
+}