Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6] / 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/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, resched;
58         int pc;
59
60         if (unlikely(!ftrace_function_enabled))
61                 return;
62
63         pc = preempt_count();
64         resched = ftrace_preempt_disable();
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         ftrace_preempt_enable(resched);
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 };
153
154 static struct ftrace_ops trace_stack_ops __read_mostly =
155 {
156         .func = function_stack_trace_call,
157 };
158
159 /* Our two options */
160 enum {
161         TRACE_FUNC_OPT_STACK = 0x1,
162 };
163
164 static struct tracer_opt func_opts[] = {
165 #ifdef CONFIG_STACKTRACE
166         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
167 #endif
168         { } /* Always set a last empty entry */
169 };
170
171 static struct tracer_flags func_flags = {
172         .val = 0, /* By default: all flags disabled */
173         .opts = func_opts
174 };
175
176 static void tracing_start_function_trace(void)
177 {
178         ftrace_function_enabled = 0;
179
180         if (trace_flags & TRACE_ITER_PREEMPTONLY)
181                 trace_ops.func = function_trace_call_preempt_only;
182         else
183                 trace_ops.func = function_trace_call;
184
185         if (func_flags.val & TRACE_FUNC_OPT_STACK)
186                 register_ftrace_function(&trace_stack_ops);
187         else
188                 register_ftrace_function(&trace_ops);
189
190         ftrace_function_enabled = 1;
191 }
192
193 static void tracing_stop_function_trace(void)
194 {
195         ftrace_function_enabled = 0;
196         /* OK if they are not registered */
197         unregister_ftrace_function(&trace_stack_ops);
198         unregister_ftrace_function(&trace_ops);
199 }
200
201 static int func_set_flag(u32 old_flags, u32 bit, int set)
202 {
203         if (bit == TRACE_FUNC_OPT_STACK) {
204                 /* do nothing if already set */
205                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
206                         return 0;
207
208                 if (set) {
209                         unregister_ftrace_function(&trace_ops);
210                         register_ftrace_function(&trace_stack_ops);
211                 } else {
212                         unregister_ftrace_function(&trace_stack_ops);
213                         register_ftrace_function(&trace_ops);
214                 }
215
216                 return 0;
217         }
218
219         return -EINVAL;
220 }
221
222 static struct tracer function_trace __read_mostly =
223 {
224         .name           = "function",
225         .init           = function_trace_init,
226         .reset          = function_trace_reset,
227         .start          = function_trace_start,
228         .wait_pipe      = poll_wait_pipe,
229         .flags          = &func_flags,
230         .set_flag       = func_set_flag,
231 #ifdef CONFIG_FTRACE_SELFTEST
232         .selftest       = trace_selftest_startup_function,
233 #endif
234 };
235
236 #ifdef CONFIG_DYNAMIC_FTRACE
237 static void
238 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
239 {
240         long *count = (long *)data;
241
242         if (tracing_is_on())
243                 return;
244
245         if (!*count)
246                 return;
247
248         if (*count != -1)
249                 (*count)--;
250
251         tracing_on();
252 }
253
254 static void
255 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
256 {
257         long *count = (long *)data;
258
259         if (!tracing_is_on())
260                 return;
261
262         if (!*count)
263                 return;
264
265         if (*count != -1)
266                 (*count)--;
267
268         tracing_off();
269 }
270
271 static int
272 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
273                          struct ftrace_probe_ops *ops, void *data);
274
275 static struct ftrace_probe_ops traceon_probe_ops = {
276         .func                   = ftrace_traceon,
277         .print                  = ftrace_trace_onoff_print,
278 };
279
280 static struct ftrace_probe_ops traceoff_probe_ops = {
281         .func                   = ftrace_traceoff,
282         .print                  = ftrace_trace_onoff_print,
283 };
284
285 static int
286 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
287                          struct ftrace_probe_ops *ops, void *data)
288 {
289         char str[KSYM_SYMBOL_LEN];
290         long count = (long)data;
291
292         kallsyms_lookup(ip, NULL, NULL, NULL, str);
293         seq_printf(m, "%s:", str);
294
295         if (ops == &traceon_probe_ops)
296                 seq_printf(m, "traceon");
297         else
298                 seq_printf(m, "traceoff");
299
300         if (count == -1)
301                 seq_printf(m, ":unlimited\n");
302         else
303                 seq_printf(m, ":count=%ld", count);
304         seq_putc(m, '\n');
305
306         return 0;
307 }
308
309 static int
310 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
311 {
312         struct ftrace_probe_ops *ops;
313
314         /* we register both traceon and traceoff to this callback */
315         if (strcmp(cmd, "traceon") == 0)
316                 ops = &traceon_probe_ops;
317         else
318                 ops = &traceoff_probe_ops;
319
320         unregister_ftrace_function_probe_func(glob, ops);
321
322         return 0;
323 }
324
325 static int
326 ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)
327 {
328         struct ftrace_probe_ops *ops;
329         void *count = (void *)-1;
330         char *number;
331         int ret;
332
333         /* hash funcs only work with set_ftrace_filter */
334         if (!enable)
335                 return -EINVAL;
336
337         if (glob[0] == '!')
338                 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
339
340         /* we register both traceon and traceoff to this callback */
341         if (strcmp(cmd, "traceon") == 0)
342                 ops = &traceon_probe_ops;
343         else
344                 ops = &traceoff_probe_ops;
345
346         if (!param)
347                 goto out_reg;
348
349         number = strsep(&param, ":");
350
351         if (!strlen(number))
352                 goto out_reg;
353
354         /*
355          * We use the callback data field (which is a pointer)
356          * as our counter.
357          */
358         ret = strict_strtoul(number, 0, (unsigned long *)&count);
359         if (ret)
360                 return ret;
361
362  out_reg:
363         ret = register_ftrace_function_probe(glob, ops, count);
364
365         return ret;
366 }
367
368 static struct ftrace_func_command ftrace_traceon_cmd = {
369         .name                   = "traceon",
370         .func                   = ftrace_trace_onoff_callback,
371 };
372
373 static struct ftrace_func_command ftrace_traceoff_cmd = {
374         .name                   = "traceoff",
375         .func                   = ftrace_trace_onoff_callback,
376 };
377
378 static int __init init_func_cmd_traceon(void)
379 {
380         int ret;
381
382         ret = register_ftrace_command(&ftrace_traceoff_cmd);
383         if (ret)
384                 return ret;
385
386         ret = register_ftrace_command(&ftrace_traceon_cmd);
387         if (ret)
388                 unregister_ftrace_command(&ftrace_traceoff_cmd);
389         return ret;
390 }
391 #else
392 static inline int init_func_cmd_traceon(void)
393 {
394         return 0;
395 }
396 #endif /* CONFIG_DYNAMIC_FTRACE */
397
398 static __init int init_function_trace(void)
399 {
400         init_func_cmd_traceon();
401         return register_tracer(&function_trace);
402 }
403 device_initcall(init_function_trace);
404