tools/perf/builtin-ftrace.c

   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 volatile int workload_exec_errno;
  49 static bool done;
  50
  51 static void sig_handler(int sig __maybe_unused)
  52 {
  53         done = true;
  54 }
  55
  56 /*
  57  * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
  58  * we asked by setting its exec_error to the function below,
  59  * ftrace__workload_exec_failed_signal.
  60  *
  61  * XXX We need to handle this more appropriately, emitting an error, etc.
  62  */
  63 static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
  64                                                 siginfo_t *info __maybe_unused,
  65                                                 void *ucontext __maybe_unused)
  66 {
  67         workload_exec_errno = info->si_value.sival_int;
  68         done = true;
  69 }
  70
  71 static int __write_tracing_file(const char *name, const char *val, bool append)
  72 {
  73         char *file;
  74         int fd, ret = -1;
  75         ssize_t size = strlen(val);
  76         int flags = O_WRONLY;
  77         char errbuf[512];
  78         char *val_copy;
  79
  80         file = get_tracing_file(name);
  81         if (!file) {
  82                 pr_debug("cannot get tracing file: %s\n", name);
  83                 return -1;
  84         }
  85
  86         if (append)
  87                 flags |= O_APPEND;
  88         else
  89                 flags |= O_TRUNC;
  90
  91         fd = open(file, flags);
  92         if (fd < 0) {
  93                 pr_debug("cannot open tracing file: %s: %s\n",
  94                          name, str_error_r(errno, errbuf, sizeof(errbuf)));
  95                 goto out;
  96         }
  97
  98         /*
  99          * Copy the original value and append a '\n'. Without this,
 100          * the kernel can hide possible errors.
 101          */
 102         val_copy = strdup(val);
 103         if (!val_copy)
 104                 goto out_close;
 105         val_copy[size] = '\n';
 106
 107         if (write(fd, val_copy, size + 1) == size + 1)
 108                 ret = 0;
 109         else
 110                 pr_debug("write '%s' to tracing/%s failed: %s\n",
 111                          val, name, str_error_r(errno, errbuf, sizeof(errbuf)));
 112
 113         free(val_copy);
 114 out_close:
 115         close(fd);
 116 out:
 117         put_tracing_file(file);
 118         return ret;
 119 }
 120
 121 static int write_tracing_file(const char *name, const char *val)
 122 {
 123         return __write_tracing_file(name, val, false);
 124 }
 125
 126 static int append_tracing_file(const char *name, const char *val)
 127 {
 128         return __write_tracing_file(name, val, true);
 129 }
 130
 131 static int reset_tracing_cpu(void);
 132 static void reset_tracing_filters(void);
 133
 134 static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
 135 {
 136         if (write_tracing_file("tracing_on", "0") < 0)
 137                 return -1;
 138
 139         if (write_tracing_file("current_tracer", "nop") < 0)
 140                 return -1;
 141
 142         if (write_tracing_file("set_ftrace_pid", " ") < 0)
 143                 return -1;
 144
 145         if (reset_tracing_cpu() < 0)
 146                 return -1;
 147
 148         if (write_tracing_file("max_graph_depth", "0") < 0)
 149                 return -1;
 150
 151         reset_tracing_filters();
 152         return 0;
 153 }
 154
 155 static int set_tracing_pid(struct perf_ftrace *ftrace)
 156 {
 157         int i;
 158         char buf[16];
 159
 160         if (target__has_cpu(&ftrace->target))
 161                 return 0;
 162
 163         for (i = 0; i < perf_thread_map__nr(ftrace->evlist->core.threads); i++) {
 164                 scnprintf(buf, sizeof(buf), "%d",
 165                           ftrace->evlist->core.threads->map[i]);
 166                 if (append_tracing_file("set_ftrace_pid", buf) < 0)
 167                         return -1;
 168         }
 169         return 0;
 170 }
 171
 172 static int set_tracing_cpumask(struct perf_cpu_map *cpumap)
 173 {
 174         char *cpumask;
 175         size_t mask_size;
 176         int ret;
 177         int last_cpu;
 178
 179         last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1);
 180         mask_size = last_cpu / 4 + 2; /* one more byte for EOS */
 181         mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */
 182
 183         cpumask = malloc(mask_size);
 184         if (cpumask == NULL) {
 185                 pr_debug("failed to allocate cpu mask\n");
 186                 return -1;
 187         }
 188
 189         cpu_map__snprint_mask(cpumap, cpumask, mask_size);
 190
 191         ret = write_tracing_file("tracing_cpumask", cpumask);
 192
 193         free(cpumask);
 194         return ret;
 195 }
 196
 197 static int set_tracing_cpu(struct perf_ftrace *ftrace)
 198 {
 199         struct perf_cpu_map *cpumap = ftrace->evlist->core.cpus;
 200
 201         if (!target__has_cpu(&ftrace->target))
 202                 return 0;
 203
 204         return set_tracing_cpumask(cpumap);
 205 }
 206
 207 static int reset_tracing_cpu(void)
 208 {
 209         struct perf_cpu_map *cpumap = perf_cpu_map__new(NULL);
 210         int ret;
 211
 212         ret = set_tracing_cpumask(cpumap);
 213         perf_cpu_map__put(cpumap);
 214         return ret;
 215 }
 216
 217 static int __set_tracing_filter(const char *filter_file, struct list_head *funcs)
 218 {
 219         struct filter_entry *pos;
 220
 221         list_for_each_entry(pos, funcs, list) {
 222                 if (append_tracing_file(filter_file, pos->name) < 0)
 223                         return -1;
 224         }
 225
 226         return 0;
 227 }
 228
 229 static int set_tracing_filters(struct perf_ftrace *ftrace)
 230 {
 231         int ret;
 232
 233         ret = __set_tracing_filter("set_ftrace_filter", &ftrace->filters);
 234         if (ret < 0)
 235                 return ret;
 236
 237         ret = __set_tracing_filter("set_ftrace_notrace", &ftrace->notrace);
 238         if (ret < 0)
 239                 return ret;
 240
 241         ret = __set_tracing_filter("set_graph_function", &ftrace->graph_funcs);
 242         if (ret < 0)
 243                 return ret;
 244
 245         /* old kernels do not have this filter */
 246         __set_tracing_filter("set_graph_notrace", &ftrace->nograph_funcs);
 247
 248         return ret;
 249 }
 250
 251 static void reset_tracing_filters(void)
 252 {
 253         write_tracing_file("set_ftrace_filter", " ");
 254         write_tracing_file("set_ftrace_notrace", " ");
 255         write_tracing_file("set_graph_function", " ");
 256         write_tracing_file("set_graph_notrace", " ");
 257 }
 258
 259 static int set_tracing_depth(struct perf_ftrace *ftrace)
 260 {
 261         char buf[16];
 262
 263         if (ftrace->graph_depth == 0)
 264                 return 0;
 265
 266         if (ftrace->graph_depth < 0) {
 267                 pr_err("invalid graph depth: %d\n", ftrace->graph_depth);
 268                 return -1;
 269         }
 270
 271         snprintf(buf, sizeof(buf), "%d", ftrace->graph_depth);
 272
 273         if (write_tracing_file("max_graph_depth", buf) < 0)
 274                 return -1;
 275
 276         return 0;
 277 }
 278
 279 static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
 280 {
 281         char *trace_file;
 282         int trace_fd;
 283         char buf[4096];
 284         struct pollfd pollfd = {
 285                 .events = POLLIN,
 286         };
 287
 288         if (!(perf_cap__capable(CAP_PERFMON) ||
 289               perf_cap__capable(CAP_SYS_ADMIN))) {
 290                 pr_err("ftrace only works for %s!\n",
 291 #ifdef HAVE_LIBCAP_SUPPORT
 292                 "users with the CAP_PERFMON or CAP_SYS_ADMIN capability"
 293 #else
 294                 "root"
 295 #endif
 296                 );
 297                 return -1;
 298         }
 299
 300         signal(SIGINT, sig_handler);
 301         signal(SIGUSR1, sig_handler);
 302         signal(SIGCHLD, sig_handler);
 303         signal(SIGPIPE, sig_handler);
 304
 305         if (reset_tracing_files(ftrace) < 0) {
 306                 pr_err("failed to reset ftrace\n");
 307                 goto out;
 308         }
 309
 310         /* reset ftrace buffer */
 311         if (write_tracing_file("trace", "0") < 0)
 312                 goto out;
 313
 314         if (argc && perf_evlist__prepare_workload(ftrace->evlist,
 315                                 &ftrace->target, argv, false,
 316                                 ftrace__workload_exec_failed_signal) < 0) {
 317                 goto out;
 318         }
 319
 320         if (set_tracing_pid(ftrace) < 0) {
 321                 pr_err("failed to set ftrace pid\n");
 322                 goto out_reset;
 323         }
 324
 325         if (set_tracing_cpu(ftrace) < 0) {
 326                 pr_err("failed to set tracing cpumask\n");
 327                 goto out_reset;
 328         }
 329
 330         if (set_tracing_filters(ftrace) < 0) {
 331                 pr_err("failed to set tracing filters\n");
 332                 goto out_reset;
 333         }
 334
 335         if (set_tracing_depth(ftrace) < 0) {
 336                 pr_err("failed to set graph depth\n");
 337                 goto out_reset;
 338         }
 339
 340         if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
 341                 pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
 342                 goto out_reset;
 343         }
 344
 345         setup_pager();
 346
 347         trace_file = get_tracing_file("trace_pipe");
 348         if (!trace_file) {
 349                 pr_err("failed to open trace_pipe\n");
 350                 goto out_reset;
 351         }
 352
 353         trace_fd = open(trace_file, O_RDONLY);
 354
 355         put_tracing_file(trace_file);
 356
 357         if (trace_fd < 0) {
 358                 pr_err("failed to open trace_pipe\n");
 359                 goto out_reset;
 360         }
 361
 362         fcntl(trace_fd, F_SETFL, O_NONBLOCK);
 363         pollfd.fd = trace_fd;
 364
 365         if (write_tracing_file("tracing_on", "1") < 0) {
 366                 pr_err("can't enable tracing\n");
 367                 goto out_close_fd;
 368         }
 369
 370         perf_evlist__start_workload(ftrace->evlist);
 371
 372         while (!done) {
 373                 if (poll(&pollfd, 1, -1) < 0)
 374                         break;
 375
 376                 if (pollfd.revents & POLLIN) {
 377                         int n = read(trace_fd, buf, sizeof(buf));
 378                         if (n < 0)
 379                                 break;
 380                         if (fwrite(buf, n, 1, stdout) != 1)
 381                                 break;
 382                 }
 383         }
 384
 385         write_tracing_file("tracing_on", "0");
 386
 387         if (workload_exec_errno) {
 388                 const char *emsg = str_error_r(workload_exec_errno, buf, sizeof(buf));
 389                 /* flush stdout first so below error msg appears at the end. */
 390                 fflush(stdout);
 391                 pr_err("workload failed: %s\n", emsg);
 392                 goto out_close_fd;
 393         }
 394
 395         /* read remaining buffer contents */
 396         while (true) {
 397                 int n = read(trace_fd, buf, sizeof(buf));
 398                 if (n <= 0)
 399                         break;
 400                 if (fwrite(buf, n, 1, stdout) != 1)
 401                         break;
 402         }
 403
 404 out_close_fd:
 405         close(trace_fd);
 406 out_reset:
 407         reset_tracing_files(ftrace);
 408 out:
 409         return (done && !workload_exec_errno) ? 0 : -1;
 410 }
 411
 412 static int perf_ftrace_config(const char *var, const char *value, void *cb)
 413 {
 414         struct perf_ftrace *ftrace = cb;
 415
 416         if (!strstarts(var, "ftrace."))
 417                 return 0;
 418
 419         if (strcmp(var, "ftrace.tracer"))
 420                 return -1;
 421
 422         if (!strcmp(value, "function_graph") ||
 423             !strcmp(value, "function")) {
 424                 ftrace->tracer = value;
 425                 return 0;
 426         }
 427
 428         pr_err("Please select \"function_graph\" (default) or \"function\"\n");
 429         return -1;
 430 }
 431
 432 static int parse_filter_func(const struct option *opt, const char *str,
 433                              int unset __maybe_unused)
 434 {
 435         struct list_head *head = opt->value;
 436         struct filter_entry *entry;
 437
 438         entry = malloc(sizeof(*entry) + strlen(str) + 1);
 439         if (entry == NULL)
 440                 return -ENOMEM;
 441
 442         strcpy(entry->name, str);
 443         list_add_tail(&entry->list, head);
 444
 445         return 0;
 446 }
 447
 448 static void delete_filter_func(struct list_head *head)
 449 {
 450         struct filter_entry *pos, *tmp;
 451
 452         list_for_each_entry_safe(pos, tmp, head, list) {
 453                 list_del_init(&pos->list);
 454                 free(pos);
 455         }
 456 }
 457
 458 int cmd_ftrace(int argc, const char **argv)
 459 {
 460         int ret;
 461         struct perf_ftrace ftrace = {
 462                 .tracer = DEFAULT_TRACER,
 463                 .target = { .uid = UINT_MAX, },
 464         };
 465         const char * const ftrace_usage[] = {
 466                 "perf ftrace [<options>] [<command>]",
 467                 "perf ftrace [<options>] -- <command> [<options>]",
 468                 NULL
 469         };
 470         const struct option ftrace_options[] = {
 471         OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
 472                    "tracer to use: function_graph(default) or function"),
 473         OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
 474                    "trace on existing process id"),
 475         OPT_INCR('v', "verbose", &verbose,
 476                  "be more verbose"),
 477         OPT_BOOLEAN('a', "all-cpus", &ftrace.target.system_wide,
 478                     "system-wide collection from all CPUs"),
 479         OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",
 480                     "list of cpus to monitor"),
 481         OPT_CALLBACK('T', "trace-funcs", &ftrace.filters, "func",
 482                      "trace given functions only", parse_filter_func),
 483         OPT_CALLBACK('N', "notrace-funcs", &ftrace.notrace, "func",
 484                      "do not trace given functions", parse_filter_func),
 485         OPT_CALLBACK('G', "graph-funcs", &ftrace.graph_funcs, "func",
 486                      "Set graph filter on given functions", parse_filter_func),
 487         OPT_CALLBACK('g', "nograph-funcs", &ftrace.nograph_funcs, "func",
 488                      "Set nograph filter on given functions", parse_filter_func),
 489         OPT_INTEGER('D', "graph-depth", &ftrace.graph_depth,
 490                     "Max depth for function graph tracer"),
 491         OPT_END()
 492         };
 493
 494         INIT_LIST_HEAD(&ftrace.filters);
 495         INIT_LIST_HEAD(&ftrace.notrace);
 496         INIT_LIST_HEAD(&ftrace.graph_funcs);
 497         INIT_LIST_HEAD(&ftrace.nograph_funcs);
 498
 499         ret = perf_config(perf_ftrace_config, &ftrace);
 500         if (ret < 0)
 501                 return -1;
 502
 503         argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
 504                             PARSE_OPT_STOP_AT_NON_OPTION);
 505         if (!argc && target__none(&ftrace.target))
 506                 ftrace.target.system_wide = true;
 507
 508         ret = target__validate(&ftrace.target);
 509         if (ret) {
 510                 char errbuf[512];
 511
 512                 target__strerror(&ftrace.target, ret, errbuf, 512);
 513                 pr_err("%s\n", errbuf);
 514                 goto out_delete_filters;
 515         }
 516
 517         ftrace.evlist = evlist__new();
 518         if (ftrace.evlist == NULL) {
 519                 ret = -ENOMEM;
 520                 goto out_delete_filters;
 521         }
 522
 523         ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
 524         if (ret < 0)
 525                 goto out_delete_evlist;
 526
 527         ret = __cmd_ftrace(&ftrace, argc, argv);
 528
 529 out_delete_evlist:
 530         evlist__delete(ftrace.evlist);
 531
 532 out_delete_filters:
 533         delete_filter_func(&ftrace.filters);
 534         delete_filter_func(&ftrace.notrace);
 535         delete_filter_func(&ftrace.graph_funcs);
 536         delete_filter_func(&ftrace.nograph_funcs);
 537
 538         return ret;
 539 }