tracing/function: Introduce persistent trace option
[linux-3.10.git] / kernel / trace / trace_functions.c
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/pstore.h>
17 #include <linux/fs.h>
18
19 #include "trace.h"
20
21 /* function tracing enabled */
22 static int                      ftrace_function_enabled;
23
24 static struct trace_array       *func_trace;
25
26 static void tracing_start_function_trace(void);
27 static void tracing_stop_function_trace(void);
28
29 static int function_trace_init(struct trace_array *tr)
30 {
31         func_trace = tr;
32         tr->cpu = get_cpu();
33         put_cpu();
34
35         tracing_start_cmdline_record();
36         tracing_start_function_trace();
37         return 0;
38 }
39
40 static void function_trace_reset(struct trace_array *tr)
41 {
42         tracing_stop_function_trace();
43         tracing_stop_cmdline_record();
44 }
45
46 static void function_trace_start(struct trace_array *tr)
47 {
48         tracing_reset_online_cpus(tr);
49 }
50
51 static void
52 function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
53 {
54         struct trace_array *tr = func_trace;
55         struct trace_array_cpu *data;
56         unsigned long flags;
57         long disabled;
58         int cpu;
59         int pc;
60
61         if (unlikely(!ftrace_function_enabled))
62                 return;
63
64         pc = preempt_count();
65         preempt_disable_notrace();
66         local_save_flags(flags);
67         cpu = raw_smp_processor_id();
68         data = tr->data[cpu];
69         disabled = atomic_inc_return(&data->disabled);
70
71         if (likely(disabled == 1))
72                 trace_function(tr, ip, parent_ip, flags, pc);
73
74         atomic_dec(&data->disabled);
75         preempt_enable_notrace();
76 }
77
78 /* Our two options */
79 enum {
80         TRACE_FUNC_OPT_STACK    = 0x1,
81         TRACE_FUNC_OPT_PSTORE   = 0x2,
82 };
83
84 static struct tracer_flags func_flags;
85
86 static void
87 function_trace_call(unsigned long ip, unsigned long parent_ip)
88 {
89         struct trace_array *tr = func_trace;
90         struct trace_array_cpu *data;
91         unsigned long flags;
92         long disabled;
93         int cpu;
94         int pc;
95
96         if (unlikely(!ftrace_function_enabled))
97                 return;
98
99         /*
100          * Need to use raw, since this must be called before the
101          * recursive protection is performed.
102          */
103         local_irq_save(flags);
104         cpu = raw_smp_processor_id();
105         data = tr->data[cpu];
106         disabled = atomic_inc_return(&data->disabled);
107
108         if (likely(disabled == 1)) {
109                 /*
110                  * So far tracing doesn't support multiple buffers, so
111                  * we make an explicit call for now.
112                  */
113                 if (unlikely(func_flags.val & TRACE_FUNC_OPT_PSTORE))
114                         pstore_ftrace_call(ip, parent_ip);
115                 pc = preempt_count();
116                 trace_function(tr, ip, parent_ip, flags, pc);
117         }
118
119         atomic_dec(&data->disabled);
120         local_irq_restore(flags);
121 }
122
123 static void
124 function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
125 {
126         struct trace_array *tr = func_trace;
127         struct trace_array_cpu *data;
128         unsigned long flags;
129         long disabled;
130         int cpu;
131         int pc;
132
133         if (unlikely(!ftrace_function_enabled))
134                 return;
135
136         /*
137          * Need to use raw, since this must be called before the
138          * recursive protection is performed.
139          */
140         local_irq_save(flags);
141         cpu = raw_smp_processor_id();
142         data = tr->data[cpu];
143         disabled = atomic_inc_return(&data->disabled);
144
145         if (likely(disabled == 1)) {
146                 pc = preempt_count();
147                 trace_function(tr, ip, parent_ip, flags, pc);
148                 /*
149                  * skip over 5 funcs:
150                  *    __ftrace_trace_stack,
151                  *    __trace_stack,
152                  *    function_stack_trace_call
153                  *    ftrace_list_func
154                  *    ftrace_call
155                  */
156                 __trace_stack(tr, flags, 5, pc);
157         }
158
159         atomic_dec(&data->disabled);
160         local_irq_restore(flags);
161 }
162
163
164 static struct ftrace_ops trace_ops __read_mostly =
165 {
166         .func = function_trace_call,
167         .flags = FTRACE_OPS_FL_GLOBAL,
168 };
169
170 static struct ftrace_ops trace_stack_ops __read_mostly =
171 {
172         .func = function_stack_trace_call,
173         .flags = FTRACE_OPS_FL_GLOBAL,
174 };
175
176 static struct tracer_opt func_opts[] = {
177 #ifdef CONFIG_STACKTRACE
178         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
179 #endif
180 #ifdef CONFIG_PSTORE_FTRACE
181         { TRACER_OPT(func_pstore, TRACE_FUNC_OPT_PSTORE) },
182 #endif
183         { } /* Always set a last empty entry */
184 };
185
186 static struct tracer_flags func_flags = {
187         .val = 0, /* By default: all flags disabled */
188         .opts = func_opts
189 };
190
191 static void tracing_start_function_trace(void)
192 {
193         ftrace_function_enabled = 0;
194
195         if (trace_flags & TRACE_ITER_PREEMPTONLY)
196                 trace_ops.func = function_trace_call_preempt_only;
197         else
198                 trace_ops.func = function_trace_call;
199
200         if (func_flags.val & TRACE_FUNC_OPT_STACK)
201                 register_ftrace_function(&trace_stack_ops);
202         else
203                 register_ftrace_function(&trace_ops);
204
205         ftrace_function_enabled = 1;
206 }
207
208 static void tracing_stop_function_trace(void)
209 {
210         ftrace_function_enabled = 0;
211
212         if (func_flags.val & TRACE_FUNC_OPT_STACK)
213                 unregister_ftrace_function(&trace_stack_ops);
214         else
215                 unregister_ftrace_function(&trace_ops);
216 }
217
218 static int func_set_flag(u32 old_flags, u32 bit, int set)
219 {
220         if (bit == TRACE_FUNC_OPT_STACK) {
221                 /* do nothing if already set */
222                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
223                         return 0;
224
225                 if (set) {
226                         unregister_ftrace_function(&trace_ops);
227                         register_ftrace_function(&trace_stack_ops);
228                 } else {
229                         unregister_ftrace_function(&trace_stack_ops);
230                         register_ftrace_function(&trace_ops);
231                 }
232
233                 return 0;
234         } else if (bit == TRACE_FUNC_OPT_PSTORE) {
235                 return 0;
236         }
237
238         return -EINVAL;
239 }
240
241 static struct tracer function_trace __read_mostly =
242 {
243         .name           = "function",
244         .init           = function_trace_init,
245         .reset          = function_trace_reset,
246         .start          = function_trace_start,
247         .wait_pipe      = poll_wait_pipe,
248         .flags          = &func_flags,
249         .set_flag       = func_set_flag,
250 #ifdef CONFIG_FTRACE_SELFTEST
251         .selftest       = trace_selftest_startup_function,
252 #endif
253 };
254
255 #ifdef CONFIG_DYNAMIC_FTRACE
256 static void
257 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
258 {
259         long *count = (long *)data;
260
261         if (tracing_is_on())
262                 return;
263
264         if (!*count)
265                 return;
266
267         if (*count != -1)
268                 (*count)--;
269
270         tracing_on();
271 }
272
273 static void
274 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
275 {
276         long *count = (long *)data;
277
278         if (!tracing_is_on())
279                 return;
280
281         if (!*count)
282                 return;
283
284         if (*count != -1)
285                 (*count)--;
286
287         tracing_off();
288 }
289
290 static int
291 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
292                          struct ftrace_probe_ops *ops, void *data);
293
294 static struct ftrace_probe_ops traceon_probe_ops = {
295         .func                   = ftrace_traceon,
296         .print                  = ftrace_trace_onoff_print,
297 };
298
299 static struct ftrace_probe_ops traceoff_probe_ops = {
300         .func                   = ftrace_traceoff,
301         .print                  = ftrace_trace_onoff_print,
302 };
303
304 static int
305 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
306                          struct ftrace_probe_ops *ops, void *data)
307 {
308         long count = (long)data;
309
310         seq_printf(m, "%ps:", (void *)ip);
311
312         if (ops == &traceon_probe_ops)
313                 seq_printf(m, "traceon");
314         else
315                 seq_printf(m, "traceoff");
316
317         if (count == -1)
318                 seq_printf(m, ":unlimited\n");
319         else
320                 seq_printf(m, ":count=%ld\n", count);
321
322         return 0;
323 }
324
325 static int
326 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
327 {
328         struct ftrace_probe_ops *ops;
329
330         /* we register both traceon and traceoff to this callback */
331         if (strcmp(cmd, "traceon") == 0)
332                 ops = &traceon_probe_ops;
333         else
334                 ops = &traceoff_probe_ops;
335
336         unregister_ftrace_function_probe_func(glob, ops);
337
338         return 0;
339 }
340
341 static int
342 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
343                             char *glob, char *cmd, char *param, int enable)
344 {
345         struct ftrace_probe_ops *ops;
346         void *count = (void *)-1;
347         char *number;
348         int ret;
349
350         /* hash funcs only work with set_ftrace_filter */
351         if (!enable)
352                 return -EINVAL;
353
354         if (glob[0] == '!')
355                 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
356
357         /* we register both traceon and traceoff to this callback */
358         if (strcmp(cmd, "traceon") == 0)
359                 ops = &traceon_probe_ops;
360         else
361                 ops = &traceoff_probe_ops;
362
363         if (!param)
364                 goto out_reg;
365
366         number = strsep(&param, ":");
367
368         if (!strlen(number))
369                 goto out_reg;
370
371         /*
372          * We use the callback data field (which is a pointer)
373          * as our counter.
374          */
375         ret = strict_strtoul(number, 0, (unsigned long *)&count);
376         if (ret)
377                 return ret;
378
379  out_reg:
380         ret = register_ftrace_function_probe(glob, ops, count);
381
382         return ret < 0 ? ret : 0;
383 }
384
385 static struct ftrace_func_command ftrace_traceon_cmd = {
386         .name                   = "traceon",
387         .func                   = ftrace_trace_onoff_callback,
388 };
389
390 static struct ftrace_func_command ftrace_traceoff_cmd = {
391         .name                   = "traceoff",
392         .func                   = ftrace_trace_onoff_callback,
393 };
394
395 static int __init init_func_cmd_traceon(void)
396 {
397         int ret;
398
399         ret = register_ftrace_command(&ftrace_traceoff_cmd);
400         if (ret)
401                 return ret;
402
403         ret = register_ftrace_command(&ftrace_traceon_cmd);
404         if (ret)
405                 unregister_ftrace_command(&ftrace_traceoff_cmd);
406         return ret;
407 }
408 #else
409 static inline int init_func_cmd_traceon(void)
410 {
411         return 0;
412 }
413 #endif /* CONFIG_DYNAMIC_FTRACE */
414
415 static __init int init_function_trace(void)
416 {
417         init_func_cmd_traceon();
418         return register_tracer(&function_trace);
419 }
420 device_initcall(init_function_trace);
421