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