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1 | /* |
2 | * ring buffer based function tracer |
3 | * |
4 | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> |
5 | * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> |
6 | * |
7 | * Based on code from the latency_tracer, that is: |
8 | * |
9 | * Copyright (C) 2004-2006 Ingo Molnar |
10 | * Copyright (C) 2004 William Lee Irwin III |
11 | */ |
12 | #include <linux/ring_buffer.h> |
13 | #include <linux/debugfs.h> |
14 | #include <linux/uaccess.h> |
15 | #include <linux/ftrace.h> |
16 | #include <linux/fs.h> |
17 | |
18 | #include "trace.h" |
19 | |
20 | /* function tracing enabled */ |
21 | static int ftrace_function_enabled; |
22 | |
23 | static struct trace_array *func_trace; |
24 | |
25 | static void tracing_start_function_trace(void); |
26 | static void tracing_stop_function_trace(void); |
27 | |
28 | static int function_trace_init(struct trace_array *tr) |
29 | { |
30 | func_trace = tr; |
31 | tr->cpu = get_cpu(); |
32 | put_cpu(); |
33 | |
34 | tracing_start_cmdline_record(); |
35 | tracing_start_function_trace(); |
36 | return 0; |
37 | } |
38 | |
39 | static void function_trace_reset(struct trace_array *tr) |
40 | { |
41 | tracing_stop_function_trace(); |
42 | tracing_stop_cmdline_record(); |
43 | } |
44 | |
45 | static void function_trace_start(struct trace_array *tr) |
46 | { |
47 | tracing_reset_online_cpus(tr); |
48 | } |
49 | |
50 | static void |
51 | function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip) |
52 | { |
53 | struct trace_array *tr = func_trace; |
54 | struct trace_array_cpu *data; |
55 | unsigned long flags; |
56 | long disabled; |
57 | int cpu; |
58 | int pc; |
59 | |
60 | if (unlikely(!ftrace_function_enabled)) |
61 | return; |
62 | |
63 | pc = preempt_count(); |
64 | preempt_disable_notrace(); |
65 | local_save_flags(flags); |
66 | cpu = raw_smp_processor_id(); |
67 | data = tr->data[cpu]; |
68 | disabled = atomic_inc_return(&data->disabled); |
69 | |
70 | if (likely(disabled == 1)) |
71 | trace_function(tr, ip, parent_ip, flags, pc); |
72 | |
73 | atomic_dec(&data->disabled); |
74 | preempt_enable_notrace(); |
75 | } |
76 | |
77 | static void |
78 | function_trace_call(unsigned long ip, unsigned long parent_ip) |
79 | { |
80 | struct trace_array *tr = func_trace; |
81 | struct trace_array_cpu *data; |
82 | unsigned long flags; |
83 | long disabled; |
84 | int cpu; |
85 | int pc; |
86 | |
87 | if (unlikely(!ftrace_function_enabled)) |
88 | return; |
89 | |
90 | /* |
91 | * Need to use raw, since this must be called before the |
92 | * recursive protection is performed. |
93 | */ |
94 | local_irq_save(flags); |
95 | cpu = raw_smp_processor_id(); |
96 | data = tr->data[cpu]; |
97 | disabled = atomic_inc_return(&data->disabled); |
98 | |
99 | if (likely(disabled == 1)) { |
100 | pc = preempt_count(); |
101 | trace_function(tr, ip, parent_ip, flags, pc); |
102 | } |
103 | |
104 | atomic_dec(&data->disabled); |
105 | local_irq_restore(flags); |
106 | } |
107 | |
108 | static void |
109 | function_stack_trace_call(unsigned long ip, unsigned long parent_ip) |
110 | { |
111 | struct trace_array *tr = func_trace; |
112 | struct trace_array_cpu *data; |
113 | unsigned long flags; |
114 | long disabled; |
115 | int cpu; |
116 | int pc; |
117 | |
118 | if (unlikely(!ftrace_function_enabled)) |
119 | return; |
120 | |
121 | /* |
122 | * Need to use raw, since this must be called before the |
123 | * recursive protection is performed. |
124 | */ |
125 | local_irq_save(flags); |
126 | cpu = raw_smp_processor_id(); |
127 | data = tr->data[cpu]; |
128 | disabled = atomic_inc_return(&data->disabled); |
129 | |
130 | if (likely(disabled == 1)) { |
131 | pc = preempt_count(); |
132 | trace_function(tr, ip, parent_ip, flags, pc); |
133 | /* |
134 | * skip over 5 funcs: |
135 | * __ftrace_trace_stack, |
136 | * __trace_stack, |
137 | * function_stack_trace_call |
138 | * ftrace_list_func |
139 | * ftrace_call |
140 | */ |
141 | __trace_stack(tr, flags, 5, pc); |
142 | } |
143 | |
144 | atomic_dec(&data->disabled); |
145 | local_irq_restore(flags); |
146 | } |
147 | |
148 | |
149 | static struct ftrace_ops trace_ops __read_mostly = |
150 | { |
151 | .func = function_trace_call, |
152 | .flags = FTRACE_OPS_FL_GLOBAL, |
153 | }; |
154 | |
155 | static struct ftrace_ops trace_stack_ops __read_mostly = |
156 | { |
157 | .func = function_stack_trace_call, |
158 | .flags = FTRACE_OPS_FL_GLOBAL, |
159 | }; |
160 | |
161 | /* Our two options */ |
162 | enum { |
163 | TRACE_FUNC_OPT_STACK = 0x1, |
164 | }; |
165 | |
166 | static struct tracer_opt func_opts[] = { |
167 | #ifdef CONFIG_STACKTRACE |
168 | { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) }, |
169 | #endif |
170 | { } /* Always set a last empty entry */ |
171 | }; |
172 | |
173 | static struct tracer_flags func_flags = { |
174 | .val = 0, /* By default: all flags disabled */ |
175 | .opts = func_opts |
176 | }; |
177 | |
178 | static void tracing_start_function_trace(void) |
179 | { |
180 | ftrace_function_enabled = 0; |
181 | |
182 | if (trace_flags & TRACE_ITER_PREEMPTONLY) |
183 | trace_ops.func = function_trace_call_preempt_only; |
184 | else |
185 | trace_ops.func = function_trace_call; |
186 | |
187 | if (func_flags.val & TRACE_FUNC_OPT_STACK) |
188 | register_ftrace_function(&trace_stack_ops); |
189 | else |
190 | register_ftrace_function(&trace_ops); |
191 | |
192 | ftrace_function_enabled = 1; |
193 | } |
194 | |
195 | static void tracing_stop_function_trace(void) |
196 | { |
197 | ftrace_function_enabled = 0; |
198 | |
199 | if (func_flags.val & TRACE_FUNC_OPT_STACK) |
200 | unregister_ftrace_function(&trace_stack_ops); |
201 | else |
202 | unregister_ftrace_function(&trace_ops); |
203 | } |
204 | |
205 | static int func_set_flag(u32 old_flags, u32 bit, int set) |
206 | { |
207 | if (bit == TRACE_FUNC_OPT_STACK) { |
208 | /* do nothing if already set */ |
209 | if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK)) |
210 | return 0; |
211 | |
212 | if (set) { |
213 | unregister_ftrace_function(&trace_ops); |
214 | register_ftrace_function(&trace_stack_ops); |
215 | } else { |
216 | unregister_ftrace_function(&trace_stack_ops); |
217 | register_ftrace_function(&trace_ops); |
218 | } |
219 | |
220 | return 0; |
221 | } |
222 | |
223 | return -EINVAL; |
224 | } |
225 | |
226 | static struct tracer function_trace __read_mostly = |
227 | { |
228 | .name = "function", |
229 | .init = function_trace_init, |
230 | .reset = function_trace_reset, |
231 | .start = function_trace_start, |
232 | .wait_pipe = poll_wait_pipe, |
233 | .flags = &func_flags, |
234 | .set_flag = func_set_flag, |
235 | #ifdef CONFIG_FTRACE_SELFTEST |
236 | .selftest = trace_selftest_startup_function, |
237 | #endif |
238 | }; |
239 | |
240 | #ifdef CONFIG_DYNAMIC_FTRACE |
241 | static void |
242 | ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data) |
243 | { |
244 | long *count = (long *)data; |
245 | |
246 | if (tracing_is_on()) |
247 | return; |
248 | |
249 | if (!*count) |
250 | return; |
251 | |
252 | if (*count != -1) |
253 | (*count)--; |
254 | |
255 | tracing_on(); |
256 | } |
257 | |
258 | static void |
259 | ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data) |
260 | { |
261 | long *count = (long *)data; |
262 | |
263 | if (!tracing_is_on()) |
264 | return; |
265 | |
266 | if (!*count) |
267 | return; |
268 | |
269 | if (*count != -1) |
270 | (*count)--; |
271 | |
272 | tracing_off(); |
273 | } |
274 | |
275 | static int |
276 | ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip, |
277 | struct ftrace_probe_ops *ops, void *data); |
278 | |
279 | static struct ftrace_probe_ops traceon_probe_ops = { |
280 | .func = ftrace_traceon, |
281 | .print = ftrace_trace_onoff_print, |
282 | }; |
283 | |
284 | static struct ftrace_probe_ops traceoff_probe_ops = { |
285 | .func = ftrace_traceoff, |
286 | .print = ftrace_trace_onoff_print, |
287 | }; |
288 | |
289 | static int |
290 | ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip, |
291 | struct ftrace_probe_ops *ops, void *data) |
292 | { |
293 | long count = (long)data; |
294 | |
295 | seq_printf(m, "%ps:", (void *)ip); |
296 | |
297 | if (ops == &traceon_probe_ops) |
298 | seq_printf(m, "traceon"); |
299 | else |
300 | seq_printf(m, "traceoff"); |
301 | |
302 | if (count == -1) |
303 | seq_printf(m, ":unlimited\n"); |
304 | else |
305 | seq_printf(m, ":count=%ld\n", count); |
306 | |
307 | return 0; |
308 | } |
309 | |
310 | static int |
311 | ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param) |
312 | { |
313 | struct ftrace_probe_ops *ops; |
314 | |
315 | /* we register both traceon and traceoff to this callback */ |
316 | if (strcmp(cmd, "traceon") == 0) |
317 | ops = &traceon_probe_ops; |
318 | else |
319 | ops = &traceoff_probe_ops; |
320 | |
321 | unregister_ftrace_function_probe_func(glob, ops); |
322 | |
323 | return 0; |
324 | } |
325 | |
326 | static int |
327 | ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable) |
328 | { |
329 | struct ftrace_probe_ops *ops; |
330 | void *count = (void *)-1; |
331 | char *number; |
332 | int ret; |
333 | |
334 | /* hash funcs only work with set_ftrace_filter */ |
335 | if (!enable) |
336 | return -EINVAL; |
337 | |
338 | if (glob[0] == '!') |
339 | return ftrace_trace_onoff_unreg(glob+1, cmd, param); |
340 | |
341 | /* we register both traceon and traceoff to this callback */ |
342 | if (strcmp(cmd, "traceon") == 0) |
343 | ops = &traceon_probe_ops; |
344 | else |
345 | ops = &traceoff_probe_ops; |
346 | |
347 | if (!param) |
348 | goto out_reg; |
349 | |
350 | number = strsep(¶m, ":"); |
351 | |
352 | if (!strlen(number)) |
353 | goto out_reg; |
354 | |
355 | /* |
356 | * We use the callback data field (which is a pointer) |
357 | * as our counter. |
358 | */ |
359 | ret = strict_strtoul(number, 0, (unsigned long *)&count); |
360 | if (ret) |
361 | return ret; |
362 | |
363 | out_reg: |
364 | ret = register_ftrace_function_probe(glob, ops, count); |
365 | |
366 | return ret < 0 ? ret : 0; |
367 | } |
368 | |
369 | static struct ftrace_func_command ftrace_traceon_cmd = { |
370 | .name = "traceon", |
371 | .func = ftrace_trace_onoff_callback, |
372 | }; |
373 | |
374 | static struct ftrace_func_command ftrace_traceoff_cmd = { |
375 | .name = "traceoff", |
376 | .func = ftrace_trace_onoff_callback, |
377 | }; |
378 | |
379 | static int __init init_func_cmd_traceon(void) |
380 | { |
381 | int ret; |
382 | |
383 | ret = register_ftrace_command(&ftrace_traceoff_cmd); |
384 | if (ret) |
385 | return ret; |
386 | |
387 | ret = register_ftrace_command(&ftrace_traceon_cmd); |
388 | if (ret) |
389 | unregister_ftrace_command(&ftrace_traceoff_cmd); |
390 | return ret; |
391 | } |
392 | #else |
393 | static inline int init_func_cmd_traceon(void) |
394 | { |
395 | return 0; |
396 | } |
397 | #endif /* CONFIG_DYNAMIC_FTRACE */ |
398 | |
399 | static __init int init_function_trace(void) |
400 | { |
401 | init_func_cmd_traceon(); |
402 | return register_tracer(&function_trace); |
403 | } |
404 | device_initcall(init_function_trace); |
405 | |
406 |
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