Merge branch 'tracing/core-v2' into tracing-for-linus
[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 };
163
164 static struct tracer branch_trace __read_mostly =
165 {
166         .name           = "branch",
167         .init           = branch_trace_init,
168         .reset          = branch_trace_reset,
169 #ifdef CONFIG_FTRACE_SELFTEST
170         .selftest       = trace_selftest_startup_branch,
171 #endif /* CONFIG_FTRACE_SELFTEST */
172 };
173
174 __init static int init_branch_tracer(void)
175 {
176         int ret;
177
178         ret = register_ftrace_event(&trace_branch_event);
179         if (!ret) {
180                 printk(KERN_WARNING "Warning: could not register "
181                                     "branch events\n");
182                 return 1;
183         }
184         return register_tracer(&branch_trace);
185 }
186 device_initcall(init_branch_tracer);
187
188 #else
189 static inline
190 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
191 {
192 }
193 #endif /* CONFIG_BRANCH_TRACER */
194
195 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
196 {
197         /*
198          * I would love to have a trace point here instead, but the
199          * trace point code is so inundated with unlikely and likely
200          * conditions that the recursive nightmare that exists is too
201          * much to try to get working. At least for now.
202          */
203         trace_likely_condition(f, val, expect);
204
205         /* FIXME: Make this atomic! */
206         if (val == expect)
207                 f->correct++;
208         else
209                 f->incorrect++;
210 }
211 EXPORT_SYMBOL(ftrace_likely_update);
212
213 extern unsigned long __start_annotated_branch_profile[];
214 extern unsigned long __stop_annotated_branch_profile[];
215
216 static int annotated_branch_stat_headers(struct seq_file *m)
217 {
218         seq_printf(m, " correct incorrect  %% ");
219         seq_printf(m, "       Function                "
220                               "  File              Line\n"
221                               " ------- ---------  - "
222                               "       --------                "
223                               "  ----              ----\n");
224         return 0;
225 }
226
227 static inline long get_incorrect_percent(struct ftrace_branch_data *p)
228 {
229         long percent;
230
231         if (p->correct) {
232                 percent = p->incorrect * 100;
233                 percent /= p->correct + p->incorrect;
234         } else
235                 percent = p->incorrect ? 100 : -1;
236
237         return percent;
238 }
239
240 static int branch_stat_show(struct seq_file *m, void *v)
241 {
242         struct ftrace_branch_data *p = v;
243         const char *f;
244         long percent;
245
246         /* Only print the file, not the path */
247         f = p->file + strlen(p->file);
248         while (f >= p->file && *f != '/')
249                 f--;
250         f++;
251
252         /*
253          * The miss is overlayed on correct, and hit on incorrect.
254          */
255         percent = get_incorrect_percent(p);
256
257         seq_printf(m, "%8lu %8lu ",  p->correct, p->incorrect);
258         if (percent < 0)
259                 seq_printf(m, "  X ");
260         else
261                 seq_printf(m, "%3ld ", percent);
262         seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
263         return 0;
264 }
265
266 static void *annotated_branch_stat_start(void)
267 {
268         return __start_annotated_branch_profile;
269 }
270
271 static void *
272 annotated_branch_stat_next(void *v, int idx)
273 {
274         struct ftrace_branch_data *p = v;
275
276         ++p;
277
278         if ((void *)p >= (void *)__stop_annotated_branch_profile)
279                 return NULL;
280
281         return p;
282 }
283
284 static int annotated_branch_stat_cmp(void *p1, void *p2)
285 {
286         struct ftrace_branch_data *a = p1;
287         struct ftrace_branch_data *b = p2;
288
289         long percent_a, percent_b;
290
291         percent_a = get_incorrect_percent(a);
292         percent_b = get_incorrect_percent(b);
293
294         if (percent_a < percent_b)
295                 return -1;
296         if (percent_a > percent_b)
297                 return 1;
298         else
299                 return 0;
300 }
301
302 static struct tracer_stat annotated_branch_stats = {
303         .name = "branch_annotated",
304         .stat_start = annotated_branch_stat_start,
305         .stat_next = annotated_branch_stat_next,
306         .stat_cmp = annotated_branch_stat_cmp,
307         .stat_headers = annotated_branch_stat_headers,
308         .stat_show = branch_stat_show
309 };
310
311 __init static int init_annotated_branch_stats(void)
312 {
313         int ret;
314
315         ret = register_stat_tracer(&annotated_branch_stats);
316         if (!ret) {
317                 printk(KERN_WARNING "Warning: could not register "
318                                     "annotated branches stats\n");
319                 return 1;
320         }
321         return 0;
322 }
323 fs_initcall(init_annotated_branch_stats);
324
325 #ifdef CONFIG_PROFILE_ALL_BRANCHES
326
327 extern unsigned long __start_branch_profile[];
328 extern unsigned long __stop_branch_profile[];
329
330 static int all_branch_stat_headers(struct seq_file *m)
331 {
332         seq_printf(m, "   miss      hit    %% ");
333         seq_printf(m, "       Function                "
334                               "  File              Line\n"
335                               " ------- ---------  - "
336                               "       --------                "
337                               "  ----              ----\n");
338         return 0;
339 }
340
341 static void *all_branch_stat_start(void)
342 {
343         return __start_branch_profile;
344 }
345
346 static void *
347 all_branch_stat_next(void *v, int idx)
348 {
349         struct ftrace_branch_data *p = v;
350
351         ++p;
352
353         if ((void *)p >= (void *)__stop_branch_profile)
354                 return NULL;
355
356         return p;
357 }
358
359 static struct tracer_stat all_branch_stats = {
360         .name = "branch_all",
361         .stat_start = all_branch_stat_start,
362         .stat_next = all_branch_stat_next,
363         .stat_headers = all_branch_stat_headers,
364         .stat_show = branch_stat_show
365 };
366
367 __init static int all_annotated_branch_stats(void)
368 {
369         int ret;
370
371         ret = register_stat_tracer(&all_branch_stats);
372         if (!ret) {
373                 printk(KERN_WARNING "Warning: could not register "
374                                     "all branches stats\n");
375                 return 1;
376         }
377         return 0;
378 }
379 fs_initcall(all_annotated_branch_stats);
380 #endif /* CONFIG_PROFILE_ALL_BRANCHES */