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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/uaccess.h>
11 #include <linux/module.h>
12 #include <linux/ftrace.h>
13 #include <linux/hash.h>
14 #include <linux/fs.h>
15 #include <asm/local.h>
16
17 #include "trace.h"
18 #include "trace_stat.h"
19 #include "trace_output.h"
20
21 #ifdef CONFIG_BRANCH_TRACER
22
23 static struct tracer branch_trace;
24 static int branch_tracing_enabled __read_mostly;
25 static DEFINE_MUTEX(branch_tracing_mutex);
26
27 static struct trace_array *branch_tracer;
28
29 static void
30 probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
31 {
32 struct ftrace_event_call *call = &event_branch;
33 struct trace_array *tr = branch_tracer;
34 struct trace_array_cpu *data;
35 struct ring_buffer_event *event;
36 struct trace_branch *entry;
37 struct ring_buffer *buffer;
38 unsigned long flags;
39 int cpu, pc;
40 const char *p;
41
42 /*
43 * I would love to save just the ftrace_likely_data pointer, but
44 * this code can also be used by modules. Ugly things can happen
45 * if the module is unloaded, and then we go and read the
46 * pointer. This is slower, but much safer.
47 */
48
49 if (unlikely(!tr))
50 return;
51
52 local_irq_save(flags);
53 cpu = raw_smp_processor_id();
54 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
55 if (atomic_inc_return(&data->disabled) != 1)
56 goto out;
57
58 pc = preempt_count();
59 buffer = tr->trace_buffer.buffer;
60 event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,
61 sizeof(*entry), flags, pc);
62 if (!event)
63 goto out;
64
65 entry = ring_buffer_event_data(event);
66
67 /* Strip off the path, only save the file */
68 p = f->file + strlen(f->file);
69 while (p >= f->file && *p != '/')
70 p--;
71 p++;
72
73 strncpy(entry->func, f->func, TRACE_FUNC_SIZE);
74 strncpy(entry->file, p, TRACE_FILE_SIZE);
75 entry->func[TRACE_FUNC_SIZE] = 0;
76 entry->file[TRACE_FILE_SIZE] = 0;
77 entry->line = f->line;
78 entry->correct = val == expect;
79
80 if (!call_filter_check_discard(call, entry, buffer, event))
81 __buffer_unlock_commit(buffer, event);
82
83 out:
84 atomic_dec(&data->disabled);
85 local_irq_restore(flags);
86 }
87
88 static inline
89 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
90 {
91 if (!branch_tracing_enabled)
92 return;
93
94 probe_likely_condition(f, val, expect);
95 }
96
97 int enable_branch_tracing(struct trace_array *tr)
98 {
99 mutex_lock(&branch_tracing_mutex);
100 branch_tracer = tr;
101 /*
102 * Must be seen before enabling. The reader is a condition
103 * where we do not need a matching rmb()
104 */
105 smp_wmb();
106 branch_tracing_enabled++;
107 mutex_unlock(&branch_tracing_mutex);
108
109 return 0;
110 }
111
112 void disable_branch_tracing(void)
113 {
114 mutex_lock(&branch_tracing_mutex);
115
116 if (!branch_tracing_enabled)
117 goto out_unlock;
118
119 branch_tracing_enabled--;
120
121 out_unlock:
122 mutex_unlock(&branch_tracing_mutex);
123 }
124
125 static void start_branch_trace(struct trace_array *tr)
126 {
127 enable_branch_tracing(tr);
128 }
129
130 static void stop_branch_trace(struct trace_array *tr)
131 {
132 disable_branch_tracing();
133 }
134
135 static int branch_trace_init(struct trace_array *tr)
136 {
137 start_branch_trace(tr);
138 return 0;
139 }
140
141 static void branch_trace_reset(struct trace_array *tr)
142 {
143 stop_branch_trace(tr);
144 }
145
146 static enum print_line_t trace_branch_print(struct trace_iterator *iter,
147 int flags, struct trace_event *event)
148 {
149 struct trace_branch *field;
150
151 trace_assign_type(field, iter->ent);
152
153 trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
154 field->correct ? " ok " : " MISS ",
155 field->func,
156 field->file,
157 field->line);
158
159 return trace_handle_return(&iter->seq);
160 }
161
162 static void branch_print_header(struct seq_file *s)
163 {
164 seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT"
165 " FUNC:FILE:LINE\n"
166 "# | | | | | "
167 " |\n");
168 }
169
170 static struct trace_event_functions trace_branch_funcs = {
171 .trace = trace_branch_print,
172 };
173
174 static struct trace_event trace_branch_event = {
175 .type = TRACE_BRANCH,
176 .funcs = &trace_branch_funcs,
177 };
178
179 static struct tracer branch_trace __read_mostly =
180 {
181 .name = "branch",
182 .init = branch_trace_init,
183 .reset = branch_trace_reset,
184 #ifdef CONFIG_FTRACE_SELFTEST
185 .selftest = trace_selftest_startup_branch,
186 #endif /* CONFIG_FTRACE_SELFTEST */
187 .print_header = branch_print_header,
188 };
189
190 __init static int init_branch_tracer(void)
191 {
192 int ret;
193
194 ret = register_ftrace_event(&trace_branch_event);
195 if (!ret) {
196 printk(KERN_WARNING "Warning: could not register "
197 "branch events\n");
198 return 1;
199 }
200 return register_tracer(&branch_trace);
201 }
202 core_initcall(init_branch_tracer);
203
204 #else
205 static inline
206 void trace_likely_condition(struct ftrace_branch_data *f, int val, int expect)
207 {
208 }
209 #endif /* CONFIG_BRANCH_TRACER */
210
211 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect)
212 {
213 /*
214 * I would love to have a trace point here instead, but the
215 * trace point code is so inundated with unlikely and likely
216 * conditions that the recursive nightmare that exists is too
217 * much to try to get working. At least for now.
218 */
219 trace_likely_condition(f, val, expect);
220
221 /* FIXME: Make this atomic! */
222 if (val == expect)
223 f->correct++;
224 else
225 f->incorrect++;
226 }
227 EXPORT_SYMBOL(ftrace_likely_update);
228
229 extern unsigned long __start_annotated_branch_profile[];
230 extern unsigned long __stop_annotated_branch_profile[];
231
232 static int annotated_branch_stat_headers(struct seq_file *m)
233 {
234 seq_puts(m, " correct incorrect % "
235 " Function "
236 " File Line\n"
237 " ------- --------- - "
238 " -------- "
239 " ---- ----\n");
240 return 0;
241 }
242
243 static inline long get_incorrect_percent(struct ftrace_branch_data *p)
244 {
245 long percent;
246
247 if (p->correct) {
248 percent = p->incorrect * 100;
249 percent /= p->correct + p->incorrect;
250 } else
251 percent = p->incorrect ? 100 : -1;
252
253 return percent;
254 }
255
256 static int branch_stat_show(struct seq_file *m, void *v)
257 {
258 struct ftrace_branch_data *p = v;
259 const char *f;
260 long percent;
261
262 /* Only print the file, not the path */
263 f = p->file + strlen(p->file);
264 while (f >= p->file && *f != '/')
265 f--;
266 f++;
267
268 /*
269 * The miss is overlayed on correct, and hit on incorrect.
270 */
271 percent = get_incorrect_percent(p);
272
273 seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect);
274 if (percent < 0)
275 seq_puts(m, " X ");
276 else
277 seq_printf(m, "%3ld ", percent);
278 seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
279 return 0;
280 }
281
282 static void *annotated_branch_stat_start(struct tracer_stat *trace)
283 {
284 return __start_annotated_branch_profile;
285 }
286
287 static void *
288 annotated_branch_stat_next(void *v, int idx)
289 {
290 struct ftrace_branch_data *p = v;
291
292 ++p;
293
294 if ((void *)p >= (void *)__stop_annotated_branch_profile)
295 return NULL;
296
297 return p;
298 }
299
300 static int annotated_branch_stat_cmp(void *p1, void *p2)
301 {
302 struct ftrace_branch_data *a = p1;
303 struct ftrace_branch_data *b = p2;
304
305 long percent_a, percent_b;
306
307 percent_a = get_incorrect_percent(a);
308 percent_b = get_incorrect_percent(b);
309
310 if (percent_a < percent_b)
311 return -1;
312 if (percent_a > percent_b)
313 return 1;
314
315 if (a->incorrect < b->incorrect)
316 return -1;
317 if (a->incorrect > b->incorrect)
318 return 1;
319
320 /*
321 * Since the above shows worse (incorrect) cases
322 * first, we continue that by showing best (correct)
323 * cases last.
324 */
325 if (a->correct > b->correct)
326 return -1;
327 if (a->correct < b->correct)
328 return 1;
329
330 return 0;
331 }
332
333 static struct tracer_stat annotated_branch_stats = {
334 .name = "branch_annotated",
335 .stat_start = annotated_branch_stat_start,
336 .stat_next = annotated_branch_stat_next,
337 .stat_cmp = annotated_branch_stat_cmp,
338 .stat_headers = annotated_branch_stat_headers,
339 .stat_show = branch_stat_show
340 };
341
342 __init static int init_annotated_branch_stats(void)
343 {
344 int ret;
345
346 ret = register_stat_tracer(&annotated_branch_stats);
347 if (!ret) {
348 printk(KERN_WARNING "Warning: could not register "
349 "annotated branches stats\n");
350 return 1;
351 }
352 return 0;
353 }
354 fs_initcall(init_annotated_branch_stats);
355
356 #ifdef CONFIG_PROFILE_ALL_BRANCHES
357
358 extern unsigned long __start_branch_profile[];
359 extern unsigned long __stop_branch_profile[];
360
361 static int all_branch_stat_headers(struct seq_file *m)
362 {
363 seq_puts(m, " miss hit % "
364 " Function "
365 " File Line\n"
366 " ------- --------- - "
367 " -------- "
368 " ---- ----\n");
369 return 0;
370 }
371
372 static void *all_branch_stat_start(struct tracer_stat *trace)
373 {
374 return __start_branch_profile;
375 }
376
377 static void *
378 all_branch_stat_next(void *v, int idx)
379 {
380 struct ftrace_branch_data *p = v;
381
382 ++p;
383
384 if ((void *)p >= (void *)__stop_branch_profile)
385 return NULL;
386
387 return p;
388 }
389
390 static struct tracer_stat all_branch_stats = {
391 .name = "branch_all",
392 .stat_start = all_branch_stat_start,
393 .stat_next = all_branch_stat_next,
394 .stat_headers = all_branch_stat_headers,
395 .stat_show = branch_stat_show
396 };
397
398 __init static int all_annotated_branch_stats(void)
399 {
400 int ret;
401
402 ret = register_stat_tracer(&all_branch_stats);
403 if (!ret) {
404 printk(KERN_WARNING "Warning: could not register "
405 "all branches stats\n");
406 return 1;
407 }
408 return 0;
409 }
410 fs_initcall(all_annotated_branch_stats);
411 #endif /* CONFIG_PROFILE_ALL_BRANCHES */