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