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Linux/tools/perf/builtin-ftrace.c

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  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)
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)
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)
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", "");
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 

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