tools/perf/builtin-ftrace.c

   1 /*
   2  * builtin-ftrace.c
   3  *
   4  * Copyright (c) 2013  LG Electronics,  Namhyung Kim <namhyung@kernel.org>
   5  *
   6  * Released under the GPL v2.
   7  */
   8
   9 #include "builtin.h"
  10 #include "perf.h"
  11
  12 #include <errno.h>
  13 #include <unistd.h>
  14 #include <signal.h>
  15 #include <fcntl.h>
  16 #include <poll.h>
  17
  18 #include "debug.h"
  19 #include <subcmd/parse-options.h>
  20 #include <api/fs/tracing_path.h>
  21 #include "evlist.h"
  22 #include "target.h"
  23 #include "cpumap.h"
  24 #include "thread_map.h"
  25 #include "util/config.h"
  26
  27
  28 #define DEFAULT_TRACER  "function_graph"
  29
  30 struct perf_ftrace {
  31         struct perf_evlist *evlist;
  32         struct target target;
  33         const char *tracer;
  34 };
  35
  36 static bool done;
  37
  38 static void sig_handler(int sig __maybe_unused)
  39 {
  40         done = true;
  41 }
  42
  43 /*
  44  * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
  45  * we asked by setting its exec_error to the function below,
  46  * ftrace__workload_exec_failed_signal.
  47  *
  48  * XXX We need to handle this more appropriately, emitting an error, etc.
  49  */
  50 static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
  51                                                 siginfo_t *info __maybe_unused,
  52                                                 void *ucontext __maybe_unused)
  53 {
  54         /* workload_exec_errno = info->si_value.sival_int; */
  55         done = true;
  56 }
  57
  58 static int __write_tracing_file(const char *name, const char *val, bool append)
  59 {
  60         char *file;
  61         int fd, ret = -1;
  62         ssize_t size = strlen(val);
  63         int flags = O_WRONLY;
  64
  65         file = get_tracing_file(name);
  66         if (!file) {
  67                 pr_debug("cannot get tracing file: %s\n", name);
  68                 return -1;
  69         }
  70
  71         if (append)
  72                 flags |= O_APPEND;
  73         else
  74                 flags |= O_TRUNC;
  75
  76         fd = open(file, flags);
  77         if (fd < 0) {
  78                 pr_debug("cannot open tracing file: %s\n", name);
  79                 goto out;
  80         }
  81
  82         if (write(fd, val, size) == size)
  83                 ret = 0;
  84         else
  85                 pr_debug("write '%s' to tracing/%s failed\n", val, name);
  86
  87         close(fd);
  88 out:
  89         put_tracing_file(file);
  90         return ret;
  91 }
  92
  93 static int write_tracing_file(const char *name, const char *val)
  94 {
  95         return __write_tracing_file(name, val, false);
  96 }
  97
  98 static int append_tracing_file(const char *name, const char *val)
  99 {
 100         return __write_tracing_file(name, val, true);
 101 }
 102
 103 static int reset_tracing_cpu(void);
 104
 105 static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
 106 {
 107         if (write_tracing_file("tracing_on", "0") < 0)
 108                 return -1;
 109
 110         if (write_tracing_file("current_tracer", "nop") < 0)
 111                 return -1;
 112
 113         if (write_tracing_file("set_ftrace_pid", " ") < 0)
 114                 return -1;
 115
 116         if (reset_tracing_cpu() < 0)
 117                 return -1;
 118
 119         return 0;
 120 }
 121
 122 static int set_tracing_pid(struct perf_ftrace *ftrace)
 123 {
 124         int i;
 125         char buf[16];
 126
 127         if (target__has_cpu(&ftrace->target))
 128                 return 0;
 129
 130         for (i = 0; i < thread_map__nr(ftrace->evlist->threads); i++) {
 131                 scnprintf(buf, sizeof(buf), "%d",
 132                           ftrace->evlist->threads->map[i]);
 133                 if (append_tracing_file("set_ftrace_pid", buf) < 0)
 134                         return -1;
 135         }
 136         return 0;
 137 }
 138
 139 static int set_tracing_cpumask(struct cpu_map *cpumap)
 140 {
 141         char *cpumask;
 142         size_t mask_size;
 143         int ret;
 144         int last_cpu;
 145
 146         last_cpu = cpu_map__cpu(cpumap, cpumap->nr - 1);
 147         mask_size = (last_cpu + 3) / 4 + 1;
 148         mask_size += last_cpu / 32; /* ',' is needed for every 32th cpus */
 149
 150         cpumask = malloc(mask_size);
 151         if (cpumask == NULL) {
 152                 pr_debug("failed to allocate cpu mask\n");
 153                 return -1;
 154         }
 155
 156         cpu_map__snprint_mask(cpumap, cpumask, mask_size);
 157
 158         ret = write_tracing_file("tracing_cpumask", cpumask);
 159
 160         free(cpumask);
 161         return ret;
 162 }
 163
 164 static int set_tracing_cpu(struct perf_ftrace *ftrace)
 165 {
 166         struct cpu_map *cpumap = ftrace->evlist->cpus;
 167
 168         if (!target__has_cpu(&ftrace->target))
 169                 return 0;
 170
 171         return set_tracing_cpumask(cpumap);
 172 }
 173
 174 static int reset_tracing_cpu(void)
 175 {
 176         struct cpu_map *cpumap = cpu_map__new(NULL);
 177         int ret;
 178
 179         ret = set_tracing_cpumask(cpumap);
 180         cpu_map__put(cpumap);
 181         return ret;
 182 }
 183
 184 static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
 185 {
 186         char *trace_file;
 187         int trace_fd;
 188         char buf[4096];
 189         struct pollfd pollfd = {
 190                 .events = POLLIN,
 191         };
 192
 193         if (geteuid() != 0) {
 194                 pr_err("ftrace only works for root!\n");
 195                 return -1;
 196         }
 197
 198         signal(SIGINT, sig_handler);
 199         signal(SIGUSR1, sig_handler);
 200         signal(SIGCHLD, sig_handler);
 201         signal(SIGPIPE, sig_handler);
 202
 203         if (reset_tracing_files(ftrace) < 0)
 204                 goto out;
 205
 206         /* reset ftrace buffer */
 207         if (write_tracing_file("trace", "0") < 0)
 208                 goto out;
 209
 210         if (argc && perf_evlist__prepare_workload(ftrace->evlist,
 211                                 &ftrace->target, argv, false,
 212                                 ftrace__workload_exec_failed_signal) < 0) {
 213                 goto out;
 214         }
 215
 216         if (set_tracing_pid(ftrace) < 0) {
 217                 pr_err("failed to set ftrace pid\n");
 218                 goto out_reset;
 219         }
 220
 221         if (set_tracing_cpu(ftrace) < 0) {
 222                 pr_err("failed to set tracing cpumask\n");
 223                 goto out_reset;
 224         }
 225
 226         if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
 227                 pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
 228                 goto out_reset;
 229         }
 230
 231         trace_file = get_tracing_file("trace_pipe");
 232         if (!trace_file) {
 233                 pr_err("failed to open trace_pipe\n");
 234                 goto out_reset;
 235         }
 236
 237         trace_fd = open(trace_file, O_RDONLY);
 238
 239         put_tracing_file(trace_file);
 240
 241         if (trace_fd < 0) {
 242                 pr_err("failed to open trace_pipe\n");
 243                 goto out_reset;
 244         }
 245
 246         fcntl(trace_fd, F_SETFL, O_NONBLOCK);
 247         pollfd.fd = trace_fd;
 248
 249         if (write_tracing_file("tracing_on", "1") < 0) {
 250                 pr_err("can't enable tracing\n");
 251                 goto out_close_fd;
 252         }
 253
 254         setup_pager();
 255
 256         perf_evlist__start_workload(ftrace->evlist);
 257
 258         while (!done) {
 259                 if (poll(&pollfd, 1, -1) < 0)
 260                         break;
 261
 262                 if (pollfd.revents & POLLIN) {
 263                         int n = read(trace_fd, buf, sizeof(buf));
 264                         if (n < 0)
 265                                 break;
 266                         if (fwrite(buf, n, 1, stdout) != 1)
 267                                 break;
 268                 }
 269         }
 270
 271         write_tracing_file("tracing_on", "0");
 272
 273         /* read remaining buffer contents */
 274         while (true) {
 275                 int n = read(trace_fd, buf, sizeof(buf));
 276                 if (n <= 0)
 277                         break;
 278                 if (fwrite(buf, n, 1, stdout) != 1)
 279                         break;
 280         }
 281
 282 out_close_fd:
 283         close(trace_fd);
 284 out_reset:
 285         reset_tracing_files(ftrace);
 286 out:
 287         return done ? 0 : -1;
 288 }
 289
 290 static int perf_ftrace_config(const char *var, const char *value, void *cb)
 291 {
 292         struct perf_ftrace *ftrace = cb;
 293
 294         if (prefixcmp(var, "ftrace."))
 295                 return 0;
 296
 297         if (strcmp(var, "ftrace.tracer"))
 298                 return -1;
 299
 300         if (!strcmp(value, "function_graph") ||
 301             !strcmp(value, "function")) {
 302                 ftrace->tracer = value;
 303                 return 0;
 304         }
 305
 306         pr_err("Please select \"function_graph\" (default) or \"function\"\n");
 307         return -1;
 308 }
 309
 310 int cmd_ftrace(int argc, const char **argv)
 311 {
 312         int ret;
 313         struct perf_ftrace ftrace = {
 314                 .tracer = DEFAULT_TRACER,
 315                 .target = { .uid = UINT_MAX, },
 316         };
 317         const char * const ftrace_usage[] = {
 318                 "perf ftrace [<options>] [<command>]",
 319                 "perf ftrace [<options>] -- <command> [<options>]",
 320                 NULL
 321         };
 322         const struct option ftrace_options[] = {
 323         OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
 324                    "tracer to use: function_graph(default) or function"),
 325         OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
 326                    "trace on existing process id"),
 327         OPT_INCR('v', "verbose", &verbose,
 328                  "be more verbose"),
 329         OPT_BOOLEAN('a', "all-cpus", &ftrace.target.system_wide,
 330                     "system-wide collection from all CPUs"),
 331         OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",
 332                     "list of cpus to monitor"),
 333         OPT_END()
 334         };
 335
 336         ret = perf_config(perf_ftrace_config, &ftrace);
 337         if (ret < 0)
 338                 return -1;
 339
 340         argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
 341                             PARSE_OPT_STOP_AT_NON_OPTION);
 342         if (!argc && target__none(&ftrace.target))
 343                 usage_with_options(ftrace_usage, ftrace_options);
 344
 345         ret = target__validate(&ftrace.target);
 346         if (ret) {
 347                 char errbuf[512];
 348
 349                 target__strerror(&ftrace.target, ret, errbuf, 512);
 350                 pr_err("%s\n", errbuf);
 351                 return -EINVAL;
 352         }
 353
 354         ftrace.evlist = perf_evlist__new();
 355         if (ftrace.evlist == NULL)
 356                 return -ENOMEM;
 357
 358         ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
 359         if (ret < 0)
 360                 goto out_delete_evlist;
 361
 362         ret = __cmd_ftrace(&ftrace, argc, argv);
 363
 364 out_delete_evlist:
 365         perf_evlist__delete(ftrace.evlist);
 366
 367         return ret;
 368 }