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 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 }