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 <unistd.h>
  13 #include <signal.h>
  14
  15 #include "debug.h"
  16 #include <subcmd/parse-options.h>
  17 #include "evlist.h"
  18 #include "target.h"
  19 #include "thread_map.h"
  20 #include "util/config.h"
  21
  22
  23 #define DEFAULT_TRACER  "function_graph"
  24
  25 struct perf_ftrace {
  26         struct perf_evlist *evlist;
  27         struct target target;
  28         const char *tracer;
  29 };
  30
  31 static bool done;
  32
  33 static void sig_handler(int sig __maybe_unused)
  34 {
  35         done = true;
  36 }
  37
  38 /*
  39  * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since
  40  * we asked by setting its exec_error to the function below,
  41  * ftrace__workload_exec_failed_signal.
  42  *
  43  * XXX We need to handle this more appropriately, emitting an error, etc.
  44  */
  45 static void ftrace__workload_exec_failed_signal(int signo __maybe_unused,
  46                                                 siginfo_t *info __maybe_unused,
  47                                                 void *ucontext __maybe_unused)
  48 {
  49         /* workload_exec_errno = info->si_value.sival_int; */
  50         done = true;
  51 }
  52
  53 static int write_tracing_file(const char *name, const char *val)
  54 {
  55         char *file;
  56         int fd, ret = -1;
  57         ssize_t size = strlen(val);
  58
  59         file = get_tracing_file(name);
  60         if (!file) {
  61                 pr_debug("cannot get tracing file: %s\n", name);
  62                 return -1;
  63         }
  64
  65         fd = open(file, O_WRONLY);
  66         if (fd < 0) {
  67                 pr_debug("cannot open tracing file: %s\n", name);
  68                 goto out;
  69         }
  70
  71         if (write(fd, val, size) == size)
  72                 ret = 0;
  73         else
  74                 pr_debug("write '%s' to tracing/%s failed\n", val, name);
  75
  76         close(fd);
  77 out:
  78         put_tracing_file(file);
  79         return ret;
  80 }
  81
  82 static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused)
  83 {
  84         if (write_tracing_file("tracing_on", "0") < 0)
  85                 return -1;
  86
  87         if (write_tracing_file("current_tracer", "nop") < 0)
  88                 return -1;
  89
  90         if (write_tracing_file("set_ftrace_pid", " ") < 0)
  91                 return -1;
  92
  93         return 0;
  94 }
  95
  96 static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
  97 {
  98         char *trace_file;
  99         int trace_fd;
 100         char *trace_pid;
 101         char buf[4096];
 102         struct pollfd pollfd = {
 103                 .events = POLLIN,
 104         };
 105
 106         if (geteuid() != 0) {
 107                 pr_err("ftrace only works for root!\n");
 108                 return -1;
 109         }
 110
 111         if (argc < 1)
 112                 return -1;
 113
 114         signal(SIGINT, sig_handler);
 115         signal(SIGUSR1, sig_handler);
 116         signal(SIGCHLD, sig_handler);
 117
 118         reset_tracing_files(ftrace);
 119
 120         /* reset ftrace buffer */
 121         if (write_tracing_file("trace", "0") < 0)
 122                 goto out;
 123
 124         if (perf_evlist__prepare_workload(ftrace->evlist, &ftrace->target,
 125                                           argv, false, ftrace__workload_exec_failed_signal) < 0)
 126                 goto out;
 127
 128         if (write_tracing_file("current_tracer", ftrace->tracer) < 0) {
 129                 pr_err("failed to set current_tracer to %s\n", ftrace->tracer);
 130                 goto out;
 131         }
 132
 133         if (asprintf(&trace_pid, "%d", thread_map__pid(ftrace->evlist->threads, 0)) < 0) {
 134                 pr_err("failed to allocate pid string\n");
 135                 goto out;
 136         }
 137
 138         if (write_tracing_file("set_ftrace_pid", trace_pid) < 0) {
 139                 pr_err("failed to set pid: %s\n", trace_pid);
 140                 goto out_free_pid;
 141         }
 142
 143         trace_file = get_tracing_file("trace_pipe");
 144         if (!trace_file) {
 145                 pr_err("failed to open trace_pipe\n");
 146                 goto out_free_pid;
 147         }
 148
 149         trace_fd = open(trace_file, O_RDONLY);
 150
 151         put_tracing_file(trace_file);
 152
 153         if (trace_fd < 0) {
 154                 pr_err("failed to open trace_pipe\n");
 155                 goto out_free_pid;
 156         }
 157
 158         fcntl(trace_fd, F_SETFL, O_NONBLOCK);
 159         pollfd.fd = trace_fd;
 160
 161         if (write_tracing_file("tracing_on", "1") < 0) {
 162                 pr_err("can't enable tracing\n");
 163                 goto out_close_fd;
 164         }
 165
 166         perf_evlist__start_workload(ftrace->evlist);
 167
 168         while (!done) {
 169                 if (poll(&pollfd, 1, -1) < 0)
 170                         break;
 171
 172                 if (pollfd.revents & POLLIN) {
 173                         int n = read(trace_fd, buf, sizeof(buf));
 174                         if (n < 0)
 175                                 break;
 176                         if (fwrite(buf, n, 1, stdout) != 1)
 177                                 break;
 178                 }
 179         }
 180
 181         write_tracing_file("tracing_on", "0");
 182
 183         /* read remaining buffer contents */
 184         while (true) {
 185                 int n = read(trace_fd, buf, sizeof(buf));
 186                 if (n <= 0)
 187                         break;
 188                 if (fwrite(buf, n, 1, stdout) != 1)
 189                         break;
 190         }
 191
 192 out_close_fd:
 193         close(trace_fd);
 194 out_free_pid:
 195         free(trace_pid);
 196 out:
 197         reset_tracing_files(ftrace);
 198
 199         return done ? 0 : -1;
 200 }
 201
 202 static int perf_ftrace_config(const char *var, const char *value, void *cb)
 203 {
 204         struct perf_ftrace *ftrace = cb;
 205
 206         if (prefixcmp(var, "ftrace."))
 207                 return 0;
 208
 209         if (strcmp(var, "ftrace.tracer"))
 210                 return -1;
 211
 212         if (!strcmp(value, "function_graph") ||
 213             !strcmp(value, "function")) {
 214                 ftrace->tracer = value;
 215                 return 0;
 216         }
 217
 218         pr_err("Please select \"function_graph\" (default) or \"function\"\n");
 219         return -1;
 220 }
 221
 222 int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused)
 223 {
 224         int ret;
 225         struct perf_ftrace ftrace = {
 226                 .tracer = DEFAULT_TRACER,
 227                 .target = { .uid = UINT_MAX, },
 228         };
 229         const char * const ftrace_usage[] = {
 230                 "perf ftrace [<options>] <command>",
 231                 "perf ftrace [<options>] -- <command> [<options>]",
 232                 NULL
 233         };
 234         const struct option ftrace_options[] = {
 235         OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
 236                    "tracer to use: function_graph(default) or function"),
 237         OPT_INCR('v', "verbose", &verbose,
 238                  "be more verbose"),
 239         OPT_END()
 240         };
 241
 242         ret = perf_config(perf_ftrace_config, &ftrace);
 243         if (ret < 0)
 244                 return -1;
 245
 246         argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
 247                             PARSE_OPT_STOP_AT_NON_OPTION);
 248         if (!argc)
 249                 usage_with_options(ftrace_usage, ftrace_options);
 250
 251         ftrace.evlist = perf_evlist__new();
 252         if (ftrace.evlist == NULL)
 253                 return -ENOMEM;
 254
 255         ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target);
 256         if (ret < 0)
 257                 goto out_delete_evlist;
 258
 259         ret = __cmd_ftrace(&ftrace, argc, argv);
 260
 261 out_delete_evlist:
 262         perf_evlist__delete(ftrace.evlist);
 263
 264         return ret;
 265 }