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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 */
21static int ftrace_function_enabled;
22
23static struct trace_array *func_trace;
24
25static void tracing_start_function_trace(void);
26static void tracing_stop_function_trace(void);
27
28static 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
39static void function_trace_reset(struct trace_array *tr)
40{
41 tracing_stop_function_trace();
42 tracing_stop_cmdline_record();
43}
44
45static void function_trace_start(struct trace_array *tr)
46{
47 tracing_reset_online_cpus(tr);
48}
49
50static void
51function_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
77static void
78function_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
108static void
109function_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
149static struct ftrace_ops trace_ops __read_mostly =
150{
151 .func = function_trace_call,
152 .flags = FTRACE_OPS_FL_GLOBAL,
153};
154
155static 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 */
162enum {
163 TRACE_FUNC_OPT_STACK = 0x1,
164};
165
166static 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
173static struct tracer_flags func_flags = {
174 .val = 0, /* By default: all flags disabled */
175 .opts = func_opts
176};
177
178static 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
195static 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
205static 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
226static 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
241static void
242ftrace_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
258static void
259ftrace_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
275static int
276ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
277 struct ftrace_probe_ops *ops, void *data);
278
279static struct ftrace_probe_ops traceon_probe_ops = {
280 .func = ftrace_traceon,
281 .print = ftrace_trace_onoff_print,
282};
283
284static struct ftrace_probe_ops traceoff_probe_ops = {
285 .func = ftrace_traceoff,
286 .print = ftrace_trace_onoff_print,
287};
288
289static int
290ftrace_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
310static int
311ftrace_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
326static int
327ftrace_trace_onoff_callback(struct ftrace_hash *hash,
328 char *glob, char *cmd, char *param, int enable)
329{
330 struct ftrace_probe_ops *ops;
331 void *count = (void *)-1;
332 char *number;
333 int ret;
334
335 /* hash funcs only work with set_ftrace_filter */
336 if (!enable)
337 return -EINVAL;
338
339 if (glob[0] == '!')
340 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
341
342 /* we register both traceon and traceoff to this callback */
343 if (strcmp(cmd, "traceon") == 0)
344 ops = &traceon_probe_ops;
345 else
346 ops = &traceoff_probe_ops;
347
348 if (!param)
349 goto out_reg;
350
351 number = strsep(¶m, ":");
352
353 if (!strlen(number))
354 goto out_reg;
355
356 /*
357 * We use the callback data field (which is a pointer)
358 * as our counter.
359 */
360 ret = strict_strtoul(number, 0, (unsigned long *)&count);
361 if (ret)
362 return ret;
363
364 out_reg:
365 ret = register_ftrace_function_probe(glob, ops, count);
366
367 return ret < 0 ? ret : 0;
368}
369
370static struct ftrace_func_command ftrace_traceon_cmd = {
371 .name = "traceon",
372 .func = ftrace_trace_onoff_callback,
373};
374
375static struct ftrace_func_command ftrace_traceoff_cmd = {
376 .name = "traceoff",
377 .func = ftrace_trace_onoff_callback,
378};
379
380static int __init init_func_cmd_traceon(void)
381{
382 int ret;
383
384 ret = register_ftrace_command(&ftrace_traceoff_cmd);
385 if (ret)
386 return ret;
387
388 ret = register_ftrace_command(&ftrace_traceon_cmd);
389 if (ret)
390 unregister_ftrace_command(&ftrace_traceoff_cmd);
391 return ret;
392}
393#else
394static inline int init_func_cmd_traceon(void)
395{
396 return 0;
397}
398#endif /* CONFIG_DYNAMIC_FTRACE */
399
400static __init int init_function_trace(void)
401{
402 init_func_cmd_traceon();
403 return register_tracer(&function_trace);
404}
405device_initcall(init_function_trace);
406