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d01f4e8d NK |
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 | ||
21 | ||
22 | #define DEFAULT_TRACER "function_graph" | |
23 | ||
24 | struct perf_ftrace { | |
25 | struct perf_evlist *evlist; | |
26 | struct target target; | |
27 | const char *tracer; | |
28 | }; | |
29 | ||
30 | static bool done; | |
31 | ||
32 | static void sig_handler(int sig __maybe_unused) | |
33 | { | |
34 | done = true; | |
35 | } | |
36 | ||
37 | /* | |
38 | * perf_evlist__prepare_workload will send a SIGUSR1 if the fork fails, since | |
39 | * we asked by setting its exec_error to the function below, | |
40 | * ftrace__workload_exec_failed_signal. | |
41 | * | |
42 | * XXX We need to handle this more appropriately, emitting an error, etc. | |
43 | */ | |
44 | static void ftrace__workload_exec_failed_signal(int signo __maybe_unused, | |
45 | siginfo_t *info __maybe_unused, | |
46 | void *ucontext __maybe_unused) | |
47 | { | |
48 | /* workload_exec_errno = info->si_value.sival_int; */ | |
49 | done = true; | |
50 | } | |
51 | ||
52 | static int write_tracing_file(const char *name, const char *val) | |
53 | { | |
54 | char *file; | |
55 | int fd, ret = -1; | |
56 | ssize_t size = strlen(val); | |
57 | ||
58 | file = get_tracing_file(name); | |
59 | if (!file) { | |
60 | pr_debug("cannot get tracing file: %s\n", name); | |
61 | return -1; | |
62 | } | |
63 | ||
64 | fd = open(file, O_WRONLY); | |
65 | if (fd < 0) { | |
66 | pr_debug("cannot open tracing file: %s\n", name); | |
67 | goto out; | |
68 | } | |
69 | ||
70 | if (write(fd, val, size) == size) | |
71 | ret = 0; | |
72 | else | |
73 | pr_debug("write '%s' to tracing/%s failed\n", val, name); | |
74 | ||
75 | close(fd); | |
76 | out: | |
77 | put_tracing_file(file); | |
78 | return ret; | |
79 | } | |
80 | ||
81 | static int reset_tracing_files(struct perf_ftrace *ftrace __maybe_unused) | |
82 | { | |
83 | if (write_tracing_file("tracing_on", "0") < 0) | |
84 | return -1; | |
85 | ||
86 | if (write_tracing_file("current_tracer", "nop") < 0) | |
87 | return -1; | |
88 | ||
89 | if (write_tracing_file("set_ftrace_pid", " ") < 0) | |
90 | return -1; | |
91 | ||
92 | return 0; | |
93 | } | |
94 | ||
95 | static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv) | |
96 | { | |
97 | char *trace_file; | |
98 | int trace_fd; | |
99 | char *trace_pid; | |
100 | char buf[4096]; | |
101 | struct pollfd pollfd = { | |
102 | .events = POLLIN, | |
103 | }; | |
104 | ||
105 | if (geteuid() != 0) { | |
106 | pr_err("ftrace only works for root!\n"); | |
107 | return -1; | |
108 | } | |
109 | ||
110 | if (argc < 1) | |
111 | return -1; | |
112 | ||
113 | signal(SIGINT, sig_handler); | |
114 | signal(SIGUSR1, sig_handler); | |
115 | signal(SIGCHLD, sig_handler); | |
116 | ||
117 | reset_tracing_files(ftrace); | |
118 | ||
119 | /* reset ftrace buffer */ | |
120 | if (write_tracing_file("trace", "0") < 0) | |
121 | goto out; | |
122 | ||
123 | if (perf_evlist__prepare_workload(ftrace->evlist, &ftrace->target, | |
124 | argv, false, ftrace__workload_exec_failed_signal) < 0) | |
125 | goto out; | |
126 | ||
127 | if (write_tracing_file("current_tracer", ftrace->tracer) < 0) { | |
128 | pr_err("failed to set current_tracer to %s\n", ftrace->tracer); | |
129 | goto out; | |
130 | } | |
131 | ||
132 | if (asprintf(&trace_pid, "%d", thread_map__pid(ftrace->evlist->threads, 0)) < 0) { | |
133 | pr_err("failed to allocate pid string\n"); | |
134 | goto out; | |
135 | } | |
136 | ||
137 | if (write_tracing_file("set_ftrace_pid", trace_pid) < 0) { | |
138 | pr_err("failed to set pid: %s\n", trace_pid); | |
139 | goto out_free_pid; | |
140 | } | |
141 | ||
142 | trace_file = get_tracing_file("trace_pipe"); | |
143 | if (!trace_file) { | |
144 | pr_err("failed to open trace_pipe\n"); | |
145 | goto out_free_pid; | |
146 | } | |
147 | ||
148 | trace_fd = open(trace_file, O_RDONLY); | |
149 | ||
150 | put_tracing_file(trace_file); | |
151 | ||
152 | if (trace_fd < 0) { | |
153 | pr_err("failed to open trace_pipe\n"); | |
154 | goto out_free_pid; | |
155 | } | |
156 | ||
157 | fcntl(trace_fd, F_SETFL, O_NONBLOCK); | |
158 | pollfd.fd = trace_fd; | |
159 | ||
160 | if (write_tracing_file("tracing_on", "1") < 0) { | |
161 | pr_err("can't enable tracing\n"); | |
162 | goto out_close_fd; | |
163 | } | |
164 | ||
165 | perf_evlist__start_workload(ftrace->evlist); | |
166 | ||
167 | while (!done) { | |
168 | if (poll(&pollfd, 1, -1) < 0) | |
169 | break; | |
170 | ||
171 | if (pollfd.revents & POLLIN) { | |
172 | int n = read(trace_fd, buf, sizeof(buf)); | |
173 | if (n < 0) | |
174 | break; | |
175 | if (fwrite(buf, n, 1, stdout) != 1) | |
176 | break; | |
177 | } | |
178 | } | |
179 | ||
180 | write_tracing_file("tracing_on", "0"); | |
181 | ||
182 | /* read remaining buffer contents */ | |
183 | while (true) { | |
184 | int n = read(trace_fd, buf, sizeof(buf)); | |
185 | if (n <= 0) | |
186 | break; | |
187 | if (fwrite(buf, n, 1, stdout) != 1) | |
188 | break; | |
189 | } | |
190 | ||
191 | out_close_fd: | |
192 | close(trace_fd); | |
193 | out_free_pid: | |
194 | free(trace_pid); | |
195 | out: | |
196 | reset_tracing_files(ftrace); | |
197 | ||
198 | return done ? 0 : -1; | |
199 | } | |
200 | ||
201 | int cmd_ftrace(int argc, const char **argv, const char *prefix __maybe_unused) | |
202 | { | |
203 | int ret; | |
204 | struct perf_ftrace ftrace = { | |
205 | .target = { .uid = UINT_MAX, }, | |
206 | }; | |
207 | const char * const ftrace_usage[] = { | |
208 | "perf ftrace [<options>] <command>", | |
209 | "perf ftrace [<options>] -- <command> [<options>]", | |
210 | NULL | |
211 | }; | |
212 | const struct option ftrace_options[] = { | |
213 | OPT_STRING('t', "tracer", &ftrace.tracer, "tracer", | |
214 | "tracer to use: function_graph or function"), | |
215 | OPT_INCR('v', "verbose", &verbose, | |
216 | "be more verbose"), | |
217 | OPT_END() | |
218 | }; | |
219 | ||
220 | argc = parse_options(argc, argv, ftrace_options, ftrace_usage, | |
221 | PARSE_OPT_STOP_AT_NON_OPTION); | |
222 | if (!argc) | |
223 | usage_with_options(ftrace_usage, ftrace_options); | |
224 | ||
225 | ftrace.evlist = perf_evlist__new(); | |
226 | if (ftrace.evlist == NULL) | |
227 | return -ENOMEM; | |
228 | ||
229 | ret = perf_evlist__create_maps(ftrace.evlist, &ftrace.target); | |
230 | if (ret < 0) | |
231 | goto out_delete_evlist; | |
232 | ||
233 | if (ftrace.tracer == NULL) | |
234 | ftrace.tracer = DEFAULT_TRACER; | |
235 | ||
236 | ret = __cmd_ftrace(&ftrace, argc, argv); | |
237 | ||
238 | out_delete_evlist: | |
239 | perf_evlist__delete(ftrace.evlist); | |
240 | ||
241 | return ret; | |
242 | } |