xref: /openbmc/linux/tools/perf/builtin-ftrace.c (revision f8e17c17)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * builtin-ftrace.c
4  *
5  * Copyright (c) 2013  LG Electronics,  Namhyung Kim <namhyung@kernel.org>
6  */
7 
8 #include "builtin.h"
9 
10 #include <errno.h>
11 #include <unistd.h>
12 #include <signal.h>
13 #include <stdlib.h>
14 #include <fcntl.h>
15 #include <poll.h>
16 #include <linux/capability.h>
17 #include <linux/string.h>
18 
19 #include "debug.h"
20 #include <subcmd/pager.h>
21 #include <subcmd/parse-options.h>
22 #include <api/fs/tracing_path.h>
23 #include "evlist.h"
24 #include "target.h"
25 #include "cpumap.h"
26 #include "thread_map.h"
27 #include "util/cap.h"
28 #include "util/config.h"
29 
30 #define DEFAULT_TRACER  "function_graph"
31 
32 struct perf_ftrace {
33 	struct evlist		*evlist;
34 	struct target		target;
35 	const char		*tracer;
36 	struct list_head	filters;
37 	struct list_head	notrace;
38 	struct list_head	graph_funcs;
39 	struct list_head	nograph_funcs;
40 	int			graph_depth;
41 };
42 
43 struct filter_entry {
44 	struct list_head	list;
45 	char			name[];
46 };
47 
48 static bool done;
49 
50 static void sig_handler(int sig __maybe_unused)
51 {
52 	done = true;
53 }
54 
55 /*
56  * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
57  * we asked by setting its exec_error to the function below,
58  * ftrace__workload_exec_failed_signal.
59  *
60  * XXX We need to handle this more appropriately, emitting an error, etc.
61  */
62 static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
63 						siginfo_t *info __maybe_unused,
64 						void *ucontext __maybe_unused)
65 {
66 	/* workload_exec_errno = info->si_value.sival_int; */
67 	done = true;
68 }
69 
70 static int __write_tracing_file(const char *name, const char *val, bool append)
71 {
72 	char *file;
73 	int fd, ret = -1;
74 	ssize_t size = strlen(val);
75 	int flags = O_WRONLY;
76 	char errbuf[512];
77 	char *val_copy;
78 
79 	file = get_tracing_file(name);
80 	if (!file) {
81 		pr_debug("cannot get tracing file: %s\n", name);
82 		return -1;
83 	}
84 
85 	if (append)
86 		flags |= O_APPEND;
87 	else
88 		flags |= O_TRUNC;
89 
90 	fd = open(file, flags);
91 	if (fd < 0) {
92 		pr_debug("cannot open tracing file: %s: %s\n",
93 			 name, str_error_r(errno, errbuf, sizeof(errbuf)));
94 		goto out;
95 	}
96 
97 	/*
98 	 * Copy the original value and append a '\n'. Without this,
99 	 * the kernel can hide possible errors.
100 	 */
101 	val_copy = strdup(val);
102 	if (!val_copy)
103 		goto out_close;
104 	val_copy[size] = '\n';
105 
106 	if (write(fd, val_copy, size + 1) == size + 1)
107 		ret = 0;
108 	else
109 		pr_debug("write '%s' to tracing/%s failed: %s\n",
110 			 val, name, str_error_r(errno, errbuf, sizeof(errbuf)));
111 
112 	free(val_copy);
113 out_close:
114 	close(fd);
115 out:
116 	put_tracing_file(file);
117 	return ret;
118 }
119 
120 static int write_tracing_file(const char *name, const char *val)
121 {
122 	return __write_tracing_file(name, val, false);
123 }
124 
125 static int append_tracing_file(const char *name, const char *val)
126 {
127 	return __write_tracing_file(name, val, true);
128 }
129 
130 static int reset_tracing_cpu(void);
131 static void reset_tracing_filters(void);
132 
133 static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
134 {
135 	if (write_tracing_file("tracing_on", "0") < 0)
136 		return -1;
137 
138 	if (write_tracing_file("current_tracer", "nop") < 0)
139 		return -1;
140 
141 	if (write_tracing_file("set_ftrace_pid", " ") < 0)
142 		return -1;
143 
144 	if (reset_tracing_cpu() < 0)
145 		return -1;
146 
147 	if (write_tracing_file("max_graph_depth", "0") < 0)
148 		return -1;
149 
150 	reset_tracing_filters();
151 	return 0;
152 }
153 
154 static int set_tracing_pid(struct perf_ftrace *ftrace)
155 {
156 	int i;
157 	char buf[16];
158 
159 	if (target__has_cpu(&ftrace->target))
160 		return 0;
161 
162 	for (i = 0; i < perf_thread_map__nr(ftrace->evlist->core.threads); i++) {
163 		scnprintf(buf, sizeof(buf), "%d",
164 			  ftrace->evlist->core.threads->map[i]);
165 		if (append_tracing_file("set_ftrace_pid", buf) < 0)
166 			return -1;
167 	}
168 	return 0;
169 }
170 
171 static int set_tracing_cpumask(struct perf_cpu_map *cpumap)
172 {
173 	char *cpumask;
174 	size_t mask_size;
175 	int ret;
176 	int last_cpu;
177 
178 	last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1);
179 	mask_size = last_cpu / 4 + 2; /* one more byte for EOS */
180 	mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */
181 
182 	cpumask = malloc(mask_size);
183 	if (cpumask == NULL) {
184 		pr_debug("failed to allocate cpu mask\n");
185 		return -1;
186 	}
187 
188 	cpu_map__snprint_mask(cpumap, cpumask, mask_size);
189 
190 	ret = write_tracing_file("tracing_cpumask", cpumask);
191 
192 	free(cpumask);
193 	return ret;
194 }
195 
196 static int set_tracing_cpu(struct perf_ftrace *ftrace)
197 {
198 	struct perf_cpu_map *cpumap = ftrace->evlist->core.cpus;
199 
200 	if (!target__has_cpu(&ftrace->target))
201 		return 0;
202 
203 	return set_tracing_cpumask(cpumap);
204 }
205 
206 static int reset_tracing_cpu(void)
207 {
208 	struct perf_cpu_map *cpumap = perf_cpu_map__new(NULL);
209 	int ret;
210 
211 	ret = set_tracing_cpumask(cpumap);
212 	perf_cpu_map__put(cpumap);
213 	return ret;
214 }
215 
216 static int __set_tracing_filter(const char *filter_file, struct list_head *funcs)
217 {
218 	struct filter_entry *pos;
219 
220 	list_for_each_entry(pos, funcs, list) {
221 		if (append_tracing_file(filter_file, pos->name) < 0)
222 			return -1;
223 	}
224 
225 	return 0;
226 }
227 
228 static int set_tracing_filters(struct perf_ftrace *ftrace)
229 {
230 	int ret;
231 
232 	ret = __set_tracing_filter("set_ftrace_filter", &ftrace->filters);
233 	if (ret < 0)
234 		return ret;
235 
236 	ret = __set_tracing_filter("set_ftrace_notrace", &ftrace->notrace);
237 	if (ret < 0)
238 		return ret;
239 
240 	ret = __set_tracing_filter("set_graph_function", &ftrace->graph_funcs);
241 	if (ret < 0)
242 		return ret;
243 
244 	/* old kernels do not have this filter */
245 	__set_tracing_filter("set_graph_notrace", &ftrace->nograph_funcs);
246 
247 	return ret;
248 }
249 
250 static void reset_tracing_filters(void)
251 {
252 	write_tracing_file("set_ftrace_filter", " ");
253 	write_tracing_file("set_ftrace_notrace", " ");
254 	write_tracing_file("set_graph_function", " ");
255 	write_tracing_file("set_graph_notrace", " ");
256 }
257 
258 static int set_tracing_depth(struct perf_ftrace *ftrace)
259 {
260 	char buf[16];
261 
262 	if (ftrace->graph_depth == 0)
263 		return 0;
264 
265 	if (ftrace->graph_depth < 0) {
266 		pr_err("invalid graph depth: %d\n", ftrace->graph_depth);
267 		return -1;
268 	}
269 
270 	snprintf(buf, sizeof(buf), "%d", ftrace->graph_depth);
271 
272 	if (write_tracing_file("max_graph_depth", buf) < 0)
273 		return -1;
274 
275 	return 0;
276 }
277 
278 static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
279 {
280 	char *trace_file;
281 	int trace_fd;
282 	char buf[4096];
283 	struct pollfd pollfd = {
284 		.events = POLLIN,
285 	};
286 
287 	if (!perf_cap__capable(CAP_SYS_ADMIN)) {
288 		pr_err("ftrace only works for %s!\n",
289 #ifdef HAVE_LIBCAP_SUPPORT
290 		"users with the SYS_ADMIN capability"
291 #else
292 		"root"
293 #endif
294 		);
295 		return -1;
296 	}
297 
298 	signal(SIGINT, sig_handler);
299 	signal(SIGUSR1, sig_handler);
300 	signal(SIGCHLD, sig_handler);
301 	signal(SIGPIPE, sig_handler);
302 
303 	if (reset_tracing_files(ftrace) < 0) {
304 		pr_err("failed to reset ftrace\n");
305 		goto out;
306 	}
307 
308 	/* reset ftrace buffer */
309 	if (write_tracing_file("trace", "0") < 0)
310 		goto out;
311 
312 	if (argc && perf_evlist__prepare_workload(ftrace->evlist,
313 				&ftrace->target, argv, false,
314 				ftrace__workload_exec_failed_signal) < 0) {
315 		goto out;
316 	}
317 
318 	if (set_tracing_pid(ftrace) < 0) {
319 		pr_err("failed to set ftrace pid\n");
320 		goto out_reset;
321 	}
322 
323 	if (set_tracing_cpu(ftrace) < 0) {
324 		pr_err("failed to set tracing cpumask\n");
325 		goto out_reset;
326 	}
327 
328 	if (set_tracing_filters(ftrace) < 0) {
329 		pr_err("failed to set tracing filters\n");
330 		goto out_reset;
331 	}
332 
333 	if (set_tracing_depth(ftrace) < 0) {
334 		pr_err("failed to set graph depth\n");
335 		goto out_reset;
336 	}
337 
338 	if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
339 		pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
340 		goto out_reset;
341 	}
342 
343 	setup_pager();
344 
345 	trace_file = get_tracing_file("trace_pipe");
346 	if (!trace_file) {
347 		pr_err("failed to open trace_pipe\n");
348 		goto out_reset;
349 	}
350 
351 	trace_fd = open(trace_file, O_RDONLY);
352 
353 	put_tracing_file(trace_file);
354 
355 	if (trace_fd < 0) {
356 		pr_err("failed to open trace_pipe\n");
357 		goto out_reset;
358 	}
359 
360 	fcntl(trace_fd, F_SETFL, O_NONBLOCK);
361 	pollfd.fd = trace_fd;
362 
363 	if (write_tracing_file("tracing_on", "1") < 0) {
364 		pr_err("can't enable tracing\n");
365 		goto out_close_fd;
366 	}
367 
368 	perf_evlist__start_workload(ftrace->evlist);
369 
370 	while (!done) {
371 		if (poll(&pollfd, 1, -1) < 0)
372 			break;
373 
374 		if (pollfd.revents & POLLIN) {
375 			int n = read(trace_fd, buf, sizeof(buf));
376 			if (n < 0)
377 				break;
378 			if (fwrite(buf, n, 1, stdout) != 1)
379 				break;
380 		}
381 	}
382 
383 	write_tracing_file("tracing_on", "0");
384 
385 	/* read remaining buffer contents */
386 	while (true) {
387 		int n = read(trace_fd, buf, sizeof(buf));
388 		if (n <= 0)
389 			break;
390 		if (fwrite(buf, n, 1, stdout) != 1)
391 			break;
392 	}
393 
394 out_close_fd:
395 	close(trace_fd);
396 out_reset:
397 	reset_tracing_files(ftrace);
398 out:
399 	return done ? 0 : -1;
400 }
401 
402 static int perf_ftrace_config(const char *var, const char *value, void *cb)
403 {
404 	struct perf_ftrace *ftrace = cb;
405 
406 	if (!strstarts(var, "ftrace."))
407 		return 0;
408 
409 	if (strcmp(var, "ftrace.tracer"))
410 		return -1;
411 
412 	if (!strcmp(value, "function_graph") ||
413 	    !strcmp(value, "function")) {
414 		ftrace->tracer = value;
415 		return 0;
416 	}
417 
418 	pr_err("Please select \"function_graph\" (default) or \"function\"\n");
419 	return -1;
420 }
421 
422 static int parse_filter_func(const struct option *opt, const char *str,
423 			     int unset __maybe_unused)
424 {
425 	struct list_head *head = opt->value;
426 	struct filter_entry *entry;
427 
428 	entry = malloc(sizeof(*entry) + strlen(str) + 1);
429 	if (entry == NULL)
430 		return -ENOMEM;
431 
432 	strcpy(entry->name, str);
433 	list_add_tail(&entry->list, head);
434 
435 	return 0;
436 }
437 
438 static void delete_filter_func(struct list_head *head)
439 {
440 	struct filter_entry *pos, *tmp;
441 
442 	list_for_each_entry_safe(pos, tmp, head, list) {
443 		list_del_init(&pos->list);
444 		free(pos);
445 	}
446 }
447 
448 int cmd_ftrace(int argc, const char **argv)
449 {
450 	int ret;
451 	struct perf_ftrace ftrace = {
452 		.tracer = DEFAULT_TRACER,
453 		.target = { .uid = UINT_MAX, },
454 	};
455 	const char * const ftrace_usage[] = {
456 		"perf ftrace [<options>] [<command>]",
457 		"perf ftrace [<options>] -- <command> [<options>]",
458 		NULL
459 	};
460 	const struct option ftrace_options[] = {
461 	OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
462 		   "tracer to use: function_graph(default) or function"),
463 	OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
464 		   "trace on existing process id"),
465 	OPT_INCR('v', "verbose", &verbose,
466 		 "be more verbose"),
467 	OPT_BOOLEAN('a', "all-cpus", &ftrace.target.system_wide,
468 		    "system-wide collection from all CPUs"),
469 	OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",
470 		    "list of cpus to monitor"),
471 	OPT_CALLBACK('T', "trace-funcs", &ftrace.filters, "func",
472 		     "trace given functions only", parse_filter_func),
473 	OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",
474 		     "do not trace given functions", parse_filter_func),
475 	OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",
476 		     "Set graph filter on given functions", parse_filter_func),
477 	OPT_CALLBACK('g', "nograph-funcs", &ftrace.nograph_funcs, "func",
478 		     "Set nograph filter on given functions", parse_filter_func),
479 	OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
480 		    "Max depth for function graph tracer"),
481 	OPT_END()
482 	};
483 
484 	INIT_LIST_HEAD(&ftrace.filters);
485 	INIT_LIST_HEAD(&ftrace.notrace);
486 	INIT_LIST_HEAD(&ftrace.graph_funcs);
487 	INIT_LIST_HEAD(&ftrace.nograph_funcs);
488 
489 	ret = perf_config(perf_ftrace_config, &ftrace);
490 	if (ret < 0)
491 		return -1;
492 
493 	argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
494 			    PARSE_OPT_STOP_AT_NON_OPTION);
495 	if (!argc && target__none(&ftrace.target))
496 		usage_with_options(ftrace_usage, ftrace_options);
497 
498 	ret = target__validate(&ftrace.target);
499 	if (ret) {
500 		char errbuf[512];
501 
502 		target__strerror(&ftrace.target, ret, errbuf, 512);
503 		pr_err("%s\n", errbuf);
504 		goto out_delete_filters;
505 	}
506 
507 	ftrace.evlist = evlist__new();
508 	if (ftrace.evlist == NULL) {
509 		ret = -ENOMEM;
510 		goto out_delete_filters;
511 	}
512 
513 	ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
514 	if (ret < 0)
515 		goto out_delete_evlist;
516 
517 	ret = __cmd_ftrace(&ftrace, argc, argv);
518 
519 out_delete_evlist:
520 	evlist__delete(ftrace.evlist);
521 
522 out_delete_filters:
523 	delete_filter_func(&ftrace.filters);
524 	delete_filter_func(&ftrace.notrace);
525 	delete_filter_func(&ftrace.graph_funcs);
526 	delete_filter_func(&ftrace.nograph_funcs);
527 
528 	return ret;
529 }
530