tracing: Replace the static global per_cpu arrays with allocated per_cpu
[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 Nadia Yvette Chambers
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 /* Our option */
51 enum {
52         TRACE_FUNC_OPT_STACK    = 0x1,
53 };
54
55 static struct tracer_flags func_flags;
56
57 static void
58 function_trace_call(unsigned long ip, unsigned long parent_ip,
59                     struct ftrace_ops *op, struct pt_regs *pt_regs)
60 {
61         struct trace_array *tr = func_trace;
62         struct trace_array_cpu *data;
63         unsigned long flags;
64         int bit;
65         int cpu;
66         int pc;
67
68         if (unlikely(!ftrace_function_enabled))
69                 return;
70
71         pc = preempt_count();
72         preempt_disable_notrace();
73
74         bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
75         if (bit < 0)
76                 goto out;
77
78         cpu = smp_processor_id();
79         data = per_cpu_ptr(tr->data, cpu);
80         if (!atomic_read(&data->disabled)) {
81                 local_save_flags(flags);
82                 trace_function(tr, ip, parent_ip, flags, pc);
83         }
84         trace_clear_recursion(bit);
85
86  out:
87         preempt_enable_notrace();
88 }
89
90 static void
91 function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
92                           struct ftrace_ops *op, struct pt_regs *pt_regs)
93 {
94         struct trace_array *tr = func_trace;
95         struct trace_array_cpu *data;
96         unsigned long flags;
97         long disabled;
98         int cpu;
99         int pc;
100
101         if (unlikely(!ftrace_function_enabled))
102                 return;
103
104         /*
105          * Need to use raw, since this must be called before the
106          * recursive protection is performed.
107          */
108         local_irq_save(flags);
109         cpu = raw_smp_processor_id();
110         data = per_cpu_ptr(tr->data, cpu);
111         disabled = atomic_inc_return(&data->disabled);
112
113         if (likely(disabled == 1)) {
114                 pc = preempt_count();
115                 trace_function(tr, ip, parent_ip, flags, pc);
116                 /*
117                  * skip over 5 funcs:
118                  *    __ftrace_trace_stack,
119                  *    __trace_stack,
120                  *    function_stack_trace_call
121                  *    ftrace_list_func
122                  *    ftrace_call
123                  */
124                 __trace_stack(tr, flags, 5, pc);
125         }
126
127         atomic_dec(&data->disabled);
128         local_irq_restore(flags);
129 }
130
131
132 static struct ftrace_ops trace_ops __read_mostly =
133 {
134         .func = function_trace_call,
135         .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
136 };
137
138 static struct ftrace_ops trace_stack_ops __read_mostly =
139 {
140         .func = function_stack_trace_call,
141         .flags = FTRACE_OPS_FL_GLOBAL | FTRACE_OPS_FL_RECURSION_SAFE,
142 };
143
144 static struct tracer_opt func_opts[] = {
145 #ifdef CONFIG_STACKTRACE
146         { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
147 #endif
148         { } /* Always set a last empty entry */
149 };
150
151 static struct tracer_flags func_flags = {
152         .val = 0, /* By default: all flags disabled */
153         .opts = func_opts
154 };
155
156 static void tracing_start_function_trace(void)
157 {
158         ftrace_function_enabled = 0;
159
160         if (func_flags.val & TRACE_FUNC_OPT_STACK)
161                 register_ftrace_function(&trace_stack_ops);
162         else
163                 register_ftrace_function(&trace_ops);
164
165         ftrace_function_enabled = 1;
166 }
167
168 static void tracing_stop_function_trace(void)
169 {
170         ftrace_function_enabled = 0;
171
172         if (func_flags.val & TRACE_FUNC_OPT_STACK)
173                 unregister_ftrace_function(&trace_stack_ops);
174         else
175                 unregister_ftrace_function(&trace_ops);
176 }
177
178 static int func_set_flag(u32 old_flags, u32 bit, int set)
179 {
180         switch (bit) {
181         case TRACE_FUNC_OPT_STACK:
182                 /* do nothing if already set */
183                 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
184                         break;
185
186                 if (set) {
187                         unregister_ftrace_function(&trace_ops);
188                         register_ftrace_function(&trace_stack_ops);
189                 } else {
190                         unregister_ftrace_function(&trace_stack_ops);
191                         register_ftrace_function(&trace_ops);
192                 }
193
194                 break;
195         default:
196                 return -EINVAL;
197         }
198
199         return 0;
200 }
201
202 static struct tracer function_trace __read_mostly =
203 {
204         .name           = "function",
205         .init           = function_trace_init,
206         .reset          = function_trace_reset,
207         .start          = function_trace_start,
208         .wait_pipe      = poll_wait_pipe,
209         .flags          = &func_flags,
210         .set_flag       = func_set_flag,
211 #ifdef CONFIG_FTRACE_SELFTEST
212         .selftest       = trace_selftest_startup_function,
213 #endif
214 };
215
216 #ifdef CONFIG_DYNAMIC_FTRACE
217 static void
218 ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
219 {
220         long *count = (long *)data;
221
222         if (tracing_is_on())
223                 return;
224
225         if (!*count)
226                 return;
227
228         if (*count != -1)
229                 (*count)--;
230
231         tracing_on();
232 }
233
234 static void
235 ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
236 {
237         long *count = (long *)data;
238
239         if (!tracing_is_on())
240                 return;
241
242         if (!*count)
243                 return;
244
245         if (*count != -1)
246                 (*count)--;
247
248         tracing_off();
249 }
250
251 static int
252 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
253                          struct ftrace_probe_ops *ops, void *data);
254
255 static struct ftrace_probe_ops traceon_probe_ops = {
256         .func                   = ftrace_traceon,
257         .print                  = ftrace_trace_onoff_print,
258 };
259
260 static struct ftrace_probe_ops traceoff_probe_ops = {
261         .func                   = ftrace_traceoff,
262         .print                  = ftrace_trace_onoff_print,
263 };
264
265 static int
266 ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
267                          struct ftrace_probe_ops *ops, void *data)
268 {
269         long count = (long)data;
270
271         seq_printf(m, "%ps:", (void *)ip);
272
273         if (ops == &traceon_probe_ops)
274                 seq_printf(m, "traceon");
275         else
276                 seq_printf(m, "traceoff");
277
278         if (count == -1)
279                 seq_printf(m, ":unlimited\n");
280         else
281                 seq_printf(m, ":count=%ld\n", count);
282
283         return 0;
284 }
285
286 static int
287 ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
288 {
289         struct ftrace_probe_ops *ops;
290
291         /* we register both traceon and traceoff to this callback */
292         if (strcmp(cmd, "traceon") == 0)
293                 ops = &traceon_probe_ops;
294         else
295                 ops = &traceoff_probe_ops;
296
297         unregister_ftrace_function_probe_func(glob, ops);
298
299         return 0;
300 }
301
302 static int
303 ftrace_trace_onoff_callback(struct ftrace_hash *hash,
304                             char *glob, char *cmd, char *param, int enable)
305 {
306         struct ftrace_probe_ops *ops;
307         void *count = (void *)-1;
308         char *number;
309         int ret;
310
311         /* hash funcs only work with set_ftrace_filter */
312         if (!enable)
313                 return -EINVAL;
314
315         if (glob[0] == '!')
316                 return ftrace_trace_onoff_unreg(glob+1, cmd, param);
317
318         /* we register both traceon and traceoff to this callback */
319         if (strcmp(cmd, "traceon") == 0)
320                 ops = &traceon_probe_ops;
321         else
322                 ops = &traceoff_probe_ops;
323
324         if (!param)
325                 goto out_reg;
326
327         number = strsep(&param, ":");
328
329         if (!strlen(number))
330                 goto out_reg;
331
332         /*
333          * We use the callback data field (which is a pointer)
334          * as our counter.
335          */
336         ret = kstrtoul(number, 0, (unsigned long *)&count);
337         if (ret)
338                 return ret;
339
340  out_reg:
341         ret = register_ftrace_function_probe(glob, ops, count);
342
343         return ret < 0 ? ret : 0;
344 }
345
346 static struct ftrace_func_command ftrace_traceon_cmd = {
347         .name                   = "traceon",
348         .func                   = ftrace_trace_onoff_callback,
349 };
350
351 static struct ftrace_func_command ftrace_traceoff_cmd = {
352         .name                   = "traceoff",
353         .func                   = ftrace_trace_onoff_callback,
354 };
355
356 static int __init init_func_cmd_traceon(void)
357 {
358         int ret;
359
360         ret = register_ftrace_command(&ftrace_traceoff_cmd);
361         if (ret)
362                 return ret;
363
364         ret = register_ftrace_command(&ftrace_traceon_cmd);
365         if (ret)
366                 unregister_ftrace_command(&ftrace_traceoff_cmd);
367         return ret;
368 }
369 #else
370 static inline int init_func_cmd_traceon(void)
371 {
372         return 0;
373 }
374 #endif /* CONFIG_DYNAMIC_FTRACE */
375
376 static __init int init_function_trace(void)
377 {
378         init_func_cmd_traceon();
379         return register_tracer(&function_trace);
380 }
381 core_initcall(init_function_trace);