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Linux/tools/perf/builtin-ftrace.c

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  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)
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)
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", "");
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 }
369 

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