Merge branch 'sched/clock' into tracing/ftrace
[linux-2.6] / kernel / trace / trace_branch.c
1 /*
2  * unlikely profiler
3  *
4  * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
5  */
6 #include <linux/kallsyms.h>
7 #include <linux/seq_file.h>
8 #include <linux/spinlock.h>
9 #include <linux/irqflags.h>
10 #include <linux/debugfs.h>
11 #include <linux/uaccess.h>
12 #include <linux/module.h>
13 #include <linux/ftrace.h>
14 #include <linux/hash.h>
15 #include <linux/fs.h>
16 #include <asm/local.h>
17
18 #include "trace.h"
19 #include "trace_stat.h"
20 #include "trace_output.h"
21
22 #ifdef CONFIG_BRANCH_TRACER
23
24 static struct tracer branch_trace;
25 static int branch_tracing_enabled __read_mostly;
26 static DEFINE_MUTEX(branch_tracing_mutex);
27
28 static struct trace_array *branch_tracer;
29
30 static void
31 probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
32 {
33         struct trace_array *tr = branch_tracer;
34         struct ring_buffer_event *event;
35         struct trace_branch *entry;
36         unsigned long flags;
37         int cpu, pc;
38         const char *p;
39
40         /*
41          * I would love to save just the ftrace_likely_data pointer, but
42          * this code can also be used by modules. Ugly things can happen
43          * if the module is unloaded, and then we go and read the
44          * pointer.  This is slower, but much safer.
45          */
46
47         if (unlikely(!tr))
48                 return;
49
50         local_irq_save(flags);
51         cpu = raw_smp_processor_id();
52         if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
53                 goto out;
54
55         pc = preempt_count();
56         event = trace_buffer_lock_reserve(tr, TRACE_BRANCH,
57                                           sizeof(*entry), flags, pc);
58         if (!event)
59                 goto out;
60
61         entry   = ring_buffer_event_data(event);
62
63         /* Strip off the path, only save the file */
64         p = f->file + strlen(f->file);
65         while (p >= f->file && *p != '/')
66                 p--;
67         p++;
68
69         strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
70         strncpy(entry->file, p, TRACE_FILE_SIZE);
71         entry->func[TRACE_FUNC_SIZE] = 0;
72         entry->file[TRACE_FILE_SIZE] = 0;
73         entry->line = f->line;
74         entry->correct = val == expect;
75
76         ring_buffer_unlock_commit(tr->buffer, event);
77
78  out:
79         atomic_dec(&tr->data[cpu]->disabled);
80         local_irq_restore(flags);
81 }
82
83 static inline
84 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
85 {
86         if (!branch_tracing_enabled)
87                 return;
88
89         probe_likely_condition(f, val, expect);
90 }
91
92 int enable_branch_tracing(struct trace_array *tr)
93 {
94         mutex_lock(&branch_tracing_mutex);
95         branch_tracer = tr;
96         /*
97          * Must be seen before enabling. The reader is a condition
98          * where we do not need a matching rmb()
99          */
100         smp_wmb();
101         branch_tracing_enabled++;
102         mutex_unlock(&branch_tracing_mutex);
103
104         return 0;
105 }
106
107 void disable_branch_tracing(void)
108 {
109         mutex_lock(&branch_tracing_mutex);
110
111         if (!branch_tracing_enabled)
112                 goto out_unlock;
113
114         branch_tracing_enabled--;
115
116  out_unlock:
117         mutex_unlock(&branch_tracing_mutex);
118 }
119
120 static void start_branch_trace(struct trace_array *tr)
121 {
122         enable_branch_tracing(tr);
123 }
124
125 static void stop_branch_trace(struct trace_array *tr)
126 {
127         disable_branch_tracing();
128 }
129
130 static int branch_trace_init(struct trace_array *tr)
131 {
132         start_branch_trace(tr);
133         return 0;
134 }
135
136 static void branch_trace_reset(struct trace_array *tr)
137 {
138         stop_branch_trace(tr);
139 }
140
141 static enum print_line_t trace_branch_print(struct trace_iterator *iter,
142                                             int flags)
143 {
144         struct trace_branch *field;
145
146         trace_assign_type(field, iter->ent);
147
148         if (trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
149                              field->correct ? "  ok  " : " MISS ",
150                              field->func,
151                              field->file,
152                              field->line))
153                 return TRACE_TYPE_PARTIAL_LINE;
154
155         return TRACE_TYPE_HANDLED;
156 }
157
158
159 static struct trace_event trace_branch_event = {
160         .type           = TRACE_BRANCH,
161         .trace          = trace_branch_print,
162         .latency_trace  = trace_branch_print,
163 };
164
165 static struct tracer branch_trace __read_mostly =
166 {
167         .name           = "branch",
168         .init           = branch_trace_init,
169         .reset          = branch_trace_reset,
170 #ifdef CONFIG_FTRACE_SELFTEST
171         .selftest       = trace_selftest_startup_branch,
172 #endif /* CONFIG_FTRACE_SELFTEST */
173 };
174
175 __init static int init_branch_tracer(void)
176 {
177         int ret;
178
179         ret = register_ftrace_event(&trace_branch_event);
180         if (!ret) {
181                 printk(KERN_WARNING "Warning: could not register "
182                                     "branch events\n");
183                 return 1;
184         }
185         return register_tracer(&branch_trace);
186 }
187 device_initcall(init_branch_tracer);
188
189 #else
190 static inline
191 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
192 {
193 }
194 #endif /* CONFIG_BRANCH_TRACER */
195
196 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
197 {
198         /*
199          * I would love to have a trace point here instead, but the
200          * trace point code is so inundated with unlikely and likely
201          * conditions that the recursive nightmare that exists is too
202          * much to try to get working. At least for now.
203          */
204         trace_likely_condition(f, val, expect);
205
206         /* FIXME: Make this atomic! */
207         if (val == expect)
208                 f->correct++;
209         else
210                 f->incorrect++;
211 }
212 EXPORT_SYMBOL(ftrace_likely_update);
213
214 extern unsigned long __start_annotated_branch_profile[];
215 extern unsigned long __stop_annotated_branch_profile[];
216
217 static int annotated_branch_stat_headers(struct seq_file *m)
218 {
219         seq_printf(m, " correct incorrect  %% ");
220         seq_printf(m, "       Function                "
221                               "  File              Line\n"
222                               " ------- ---------  - "
223                               "       --------                "
224                               "  ----              ----\n");
225         return 0;
226 }
227
228 static inline long get_incorrect_percent(struct ftrace_branch_data *p)
229 {
230         long percent;
231
232         if (p->correct) {
233                 percent = p->incorrect * 100;
234                 percent /= p->correct + p->incorrect;
235         } else
236                 percent = p->incorrect ? 100 : -1;
237
238         return percent;
239 }
240
241 static int branch_stat_show(struct seq_file *m, void *v)
242 {
243         struct ftrace_branch_data *p = v;
244         const char *f;
245         long percent;
246
247         /* Only print the file, not the path */
248         f = p->file + strlen(p->file);
249         while (f >= p->file && *f != '/')
250                 f--;
251         f++;
252
253         /*
254          * The miss is overlayed on correct, and hit on incorrect.
255          */
256         percent = get_incorrect_percent(p);
257
258         seq_printf(m, "%8lu %8lu ",  p->correct, p->incorrect);
259         if (percent < 0)
260                 seq_printf(m, "  X ");
261         else
262                 seq_printf(m, "%3ld ", percent);
263         seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
264         return 0;
265 }
266
267 static void *annotated_branch_stat_start(void)
268 {
269         return __start_annotated_branch_profile;
270 }
271
272 static void *
273 annotated_branch_stat_next(void *v, int idx)
274 {
275         struct ftrace_branch_data *p = v;
276
277         ++p;
278
279         if ((void *)p >= (void *)__stop_annotated_branch_profile)
280                 return NULL;
281
282         return p;
283 }
284
285 static int annotated_branch_stat_cmp(void *p1, void *p2)
286 {
287         struct ftrace_branch_data *a = p1;
288         struct ftrace_branch_data *b = p2;
289
290         long percent_a, percent_b;
291
292         percent_a = get_incorrect_percent(a);
293         percent_b = get_incorrect_percent(b);
294
295         if (percent_a < percent_b)
296                 return -1;
297         if (percent_a > percent_b)
298                 return 1;
299         else
300                 return 0;
301 }
302
303 static struct tracer_stat annotated_branch_stats = {
304         .name = "branch_annotated",
305         .stat_start = annotated_branch_stat_start,
306         .stat_next = annotated_branch_stat_next,
307         .stat_cmp = annotated_branch_stat_cmp,
308         .stat_headers = annotated_branch_stat_headers,
309         .stat_show = branch_stat_show
310 };
311
312 __init static int init_annotated_branch_stats(void)
313 {
314         int ret;
315
316         ret = register_stat_tracer(&annotated_branch_stats);
317         if (!ret) {
318                 printk(KERN_WARNING "Warning: could not register "
319                                     "annotated branches stats\n");
320                 return 1;
321         }
322         return 0;
323 }
324 fs_initcall(init_annotated_branch_stats);
325
326 #ifdef CONFIG_PROFILE_ALL_BRANCHES
327
328 extern unsigned long __start_branch_profile[];
329 extern unsigned long __stop_branch_profile[];
330
331 static int all_branch_stat_headers(struct seq_file *m)
332 {
333         seq_printf(m, "   miss      hit    %% ");
334         seq_printf(m, "       Function                "
335                               "  File              Line\n"
336                               " ------- ---------  - "
337                               "       --------                "
338                               "  ----              ----\n");
339         return 0;
340 }
341
342 static void *all_branch_stat_start(void)
343 {
344         return __start_branch_profile;
345 }
346
347 static void *
348 all_branch_stat_next(void *v, int idx)
349 {
350         struct ftrace_branch_data *p = v;
351
352         ++p;
353
354         if ((void *)p >= (void *)__stop_branch_profile)
355                 return NULL;
356
357         return p;
358 }
359
360 static struct tracer_stat all_branch_stats = {
361         .name = "branch_all",
362         .stat_start = all_branch_stat_start,
363         .stat_next = all_branch_stat_next,
364         .stat_headers = all_branch_stat_headers,
365         .stat_show = branch_stat_show
366 };
367
368 __init static int all_annotated_branch_stats(void)
369 {
370         int ret;
371
372         ret = register_stat_tracer(&all_branch_stats);
373         if (!ret) {
374                 printk(KERN_WARNING "Warning: could not register "
375                                     "all branches stats\n");
376                 return 1;
377         }
378         return 0;
379 }
380 fs_initcall(all_annotated_branch_stats);
381 #endif /* CONFIG_PROFILE_ALL_BRANCHES */