tracing/function: Convert func_set_flag() to a switch statement
[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         switch (bit) {
221         case TRACE_FUNC_OPT_STACK:
222                 /* do nothing if already set */
223                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
224                         break;
225
226                 if (set) {
227                         unregister_ftrace_function(&trace_ops);
228                         register_ftrace_function(&trace_stack_ops);
229                 } else {
230                         unregister_ftrace_function(&trace_stack_ops);
231                         register_ftrace_function(&trace_ops);
232                 }
233
234                 break;
235         case TRACE_FUNC_OPT_PSTORE:
236                 break;
237         default:
238                 return -EINVAL;
239         }
240
241         return 0;
242 }
243
244 static struct tracer function_trace __read_mostly =
245 {
246         .name           = "function",
247         .init           = function_trace_init,
248         .reset          = function_trace_reset,
249         .start          = function_trace_start,
250         .wait_pipe      = poll_wait_pipe,
251         .flags          = &func_flags,
252         .set_flag       = func_set_flag,
253 #ifdef CONFIG_FTRACE_SELFTEST
254         .selftest       = trace_selftest_startup_function,
255 #endif
256 };
257
258 #ifdef CONFIG_DYNAMIC_FTRACE
259 static void
260 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
261 {
262         long *count = (long *)data;
263
264         if (tracing_is_on())
265                 return;
266
267         if (!*count)
268                 return;
269
270         if (*count != -1)
271                 (*count)--;
272
273         tracing_on();
274 }
275
276 static void
277 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
278 {
279         long *count = (long *)data;
280
281         if (!tracing_is_on())
282                 return;
283
284         if (!*count)
285                 return;
286
287         if (*count != -1)
288                 (*count)--;
289
290         tracing_off();
291 }
292
293 static int
294 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
295                          struct ftrace_probe_ops *ops, void *data);
296
297 static struct ftrace_probe_ops traceon_probe_ops = {
298         .func                   = ftrace_traceon,
299         .print                  = ftrace_trace_onoff_print,
300 };
301
302 static struct ftrace_probe_ops traceoff_probe_ops = {
303         .func                   = ftrace_traceoff,
304         .print                  = ftrace_trace_onoff_print,
305 };
306
307 static int
308 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
309                          struct ftrace_probe_ops *ops, void *data)
310 {
311         long count = (long)data;
312
313         seq_printf(m, "%ps:", (void *)ip);
314
315         if (ops == &traceon_probe_ops)
316                 seq_printf(m, "traceon");
317         else
318                 seq_printf(m, "traceoff");
319
320         if (count == -1)
321                 seq_printf(m, ":unlimited\n");
322         else
323                 seq_printf(m, ":count=%ld\n", count);
324
325         return 0;
326 }
327
328 static int
329 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
330 {
331         struct ftrace_probe_ops *ops;
332
333         /* we register both traceon and traceoff to this callback */
334         if (strcmp(cmd, "traceon") == 0)
335                 ops = &traceon_probe_ops;
336         else
337                 ops = &traceoff_probe_ops;
338
339         unregister_ftrace_function_probe_func(glob, ops);
340
341         return 0;
342 }
343
344 static int
345 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
346                             char *glob, char *cmd, char *param, int enable)
347 {
348         struct ftrace_probe_ops *ops;
349         void *count = (void *)-1;
350         char *number;
351         int ret;
352
353         /* hash funcs only work with set_ftrace_filter */
354         if (!enable)
355                 return -EINVAL;
356
357         if (glob[0] == '!')
358                 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
359
360         /* we register both traceon and traceoff to this callback */
361         if (strcmp(cmd, "traceon") == 0)
362                 ops = &traceon_probe_ops;
363         else
364                 ops = &traceoff_probe_ops;
365
366         if (!param)
367                 goto out_reg;
368
369         number = strsep(&param, ":");
370
371         if (!strlen(number))
372                 goto out_reg;
373
374         /*
375          * We use the callback data field (which is a pointer)
376          * as our counter.
377          */
378         ret = strict_strtoul(number, 0, (unsigned long *)&count);
379         if (ret)
380                 return ret;
381
382  out_reg:
383         ret = register_ftrace_function_probe(glob, ops, count);
384
385         return ret < 0 ? ret : 0;
386 }
387
388 static struct ftrace_func_command ftrace_traceon_cmd = {
389         .name                   = "traceon",
390         .func                   = ftrace_trace_onoff_callback,
391 };
392
393 static struct ftrace_func_command ftrace_traceoff_cmd = {
394         .name                   = "traceoff",
395         .func                   = ftrace_trace_onoff_callback,
396 };
397
398 static int __init init_func_cmd_traceon(void)
399 {
400         int ret;
401
402         ret = register_ftrace_command(&ftrace_traceoff_cmd);
403         if (ret)
404                 return ret;
405
406         ret = register_ftrace_command(&ftrace_traceon_cmd);
407         if (ret)
408                 unregister_ftrace_command(&ftrace_traceoff_cmd);
409         return ret;
410 }
411 #else
412 static inline int init_func_cmd_traceon(void)
413 {
414         return 0;
415 }
416 #endif /* CONFIG_DYNAMIC_FTRACE */
417
418 static __init int init_function_trace(void)
419 {
420         init_func_cmd_traceon();
421         return register_tracer(&function_trace);
422 }
423 device_initcall(init_function_trace);
424