Warning: That file was not part of the compilation database. It may have many parsing errors.

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * unlikely profiler
4 *
5 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
6 */
7#include <linux/kallsyms.h>
8#include <linux/seq_file.h>
9#include <linux/spinlock.h>
10#include <linux/irqflags.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
24static struct tracer branch_trace;
25static int branch_tracing_enabled __read_mostly;
26static DEFINE_MUTEX(branch_tracing_mutex);
27
28static struct trace_array *branch_tracer;
29
30static void
31probe_likely_condition(struct ftrace_likely_data *f, int val, int expect)
32{
33 struct trace_event_call *call = &event_branch;
34 struct trace_array *tr = branch_tracer;
35 struct trace_array_cpu *data;
36 struct ring_buffer_event *event;
37 struct trace_branch *entry;
38 struct ring_buffer *buffer;
39 unsigned long flags;
40 int pc;
41 const char *p;
42
43 if (current->trace_recursion & TRACE_BRANCH_BIT)
44 return;
45
46 /*
47 * I would love to save just the ftrace_likely_data pointer, but
48 * this code can also be used by modules. Ugly things can happen
49 * if the module is unloaded, and then we go and read the
50 * pointer. This is slower, but much safer.
51 */
52
53 if (unlikely(!tr))
54 return;
55
56 raw_local_irq_save(flags);
57 current->trace_recursion |= TRACE_BRANCH_BIT;
58 data = this_cpu_ptr(tr->trace_buffer.data);
59 if (atomic_read(&data->disabled))
60 goto out;
61
62 pc = preempt_count();
63 buffer = tr->trace_buffer.buffer;
64 event = trace_buffer_lock_reserve(buffer, TRACE_BRANCH,
65 sizeof(*entry), flags, pc);
66 if (!event)
67 goto out;
68
69 entry = ring_buffer_event_data(event);
70
71 /* Strip off the path, only save the file */
72 p = f->data.file + strlen(f->data.file);
73 while (p >= f->data.file && *p != '/')
74 p--;
75 p++;
76
77 strncpy(entry->func, f->data.func, TRACE_FUNC_SIZE);
78 strncpy(entry->file, p, TRACE_FILE_SIZE);
79 entry->func[TRACE_FUNC_SIZE] = 0;
80 entry->file[TRACE_FILE_SIZE] = 0;
81 entry->constant = f->constant;
82 entry->line = f->data.line;
83 entry->correct = val == expect;
84
85 if (!call_filter_check_discard(call, entry, buffer, event))
86 trace_buffer_unlock_commit_nostack(buffer, event);
87
88 out:
89 current->trace_recursion &= ~TRACE_BRANCH_BIT;
90 raw_local_irq_restore(flags);
91}
92
93static inline
94void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect)
95{
96 if (!branch_tracing_enabled)
97 return;
98
99 probe_likely_condition(f, val, expect);
100}
101
102int enable_branch_tracing(struct trace_array *tr)
103{
104 mutex_lock(&branch_tracing_mutex);
105 branch_tracer = tr;
106 /*
107 * Must be seen before enabling. The reader is a condition
108 * where we do not need a matching rmb()
109 */
110 smp_wmb();
111 branch_tracing_enabled++;
112 mutex_unlock(&branch_tracing_mutex);
113
114 return 0;
115}
116
117void disable_branch_tracing(void)
118{
119 mutex_lock(&branch_tracing_mutex);
120
121 if (!branch_tracing_enabled)
122 goto out_unlock;
123
124 branch_tracing_enabled--;
125
126 out_unlock:
127 mutex_unlock(&branch_tracing_mutex);
128}
129
130static int branch_trace_init(struct trace_array *tr)
131{
132 return enable_branch_tracing(tr);
133}
134
135static void branch_trace_reset(struct trace_array *tr)
136{
137 disable_branch_tracing();
138}
139
140static enum print_line_t trace_branch_print(struct trace_iterator *iter,
141 int flags, struct trace_event *event)
142{
143 struct trace_branch *field;
144
145 trace_assign_type(field, iter->ent);
146
147 trace_seq_printf(&iter->seq, "[%s] %s:%s:%d\n",
148 field->correct ? " ok " : " MISS ",
149 field->func,
150 field->file,
151 field->line);
152
153 return trace_handle_return(&iter->seq);
154}
155
156static void branch_print_header(struct seq_file *s)
157{
158 seq_puts(s, "# TASK-PID CPU# TIMESTAMP CORRECT"
159 " FUNC:FILE:LINE\n"
160 "# | | | | | "
161 " |\n");
162}
163
164static struct trace_event_functions trace_branch_funcs = {
165 .trace = trace_branch_print,
166};
167
168static struct trace_event trace_branch_event = {
169 .type = TRACE_BRANCH,
170 .funcs = &trace_branch_funcs,
171};
172
173static struct tracer branch_trace __read_mostly =
174{
175 .name = "branch",
176 .init = branch_trace_init,
177 .reset = branch_trace_reset,
178#ifdef CONFIG_FTRACE_SELFTEST
179 .selftest = trace_selftest_startup_branch,
180#endif /* CONFIG_FTRACE_SELFTEST */
181 .print_header = branch_print_header,
182};
183
184__init static int init_branch_tracer(void)
185{
186 int ret;
187
188 ret = register_trace_event(&trace_branch_event);
189 if (!ret) {
190 printk(KERN_WARNING "Warning: could not register "
191 "branch events\n");
192 return 1;
193 }
194 return register_tracer(&branch_trace);
195}
196core_initcall(init_branch_tracer);
197
198#else
199static inline
200void trace_likely_condition(struct ftrace_likely_data *f, int val, int expect)
201{
202}
203#endif /* CONFIG_BRANCH_TRACER */
204
205void ftrace_likely_update(struct ftrace_likely_data *f, int val,
206 int expect, int is_constant)
207{
208 /* A constant is always correct */
209 if (is_constant) {
210 f->constant++;
211 val = 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->data.correct++;
224 else
225 f->data.incorrect++;
226}
227EXPORT_SYMBOL(ftrace_likely_update);
228
229extern unsigned long __start_annotated_branch_profile[];
230extern unsigned long __stop_annotated_branch_profile[];
231
232static 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
243static 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
256static const char *branch_stat_process_file(struct ftrace_branch_data *p)
257{
258 const char *f;
259
260 /* Only print the file, not the path */
261 f = p->file + strlen(p->file);
262 while (f >= p->file && *f != '/')
263 f--;
264 return ++f;
265}
266
267static void branch_stat_show(struct seq_file *m,
268 struct ftrace_branch_data *p, const char *f)
269{
270 long percent;
271
272 /*
273 * The miss is overlayed on correct, and hit on incorrect.
274 */
275 percent = get_incorrect_percent(p);
276
277 if (percent < 0)
278 seq_puts(m, " X ");
279 else
280 seq_printf(m, "%3ld ", percent);
281
282 seq_printf(m, "%-30.30s %-20.20s %d\n", p->func, f, p->line);
283}
284
285static int branch_stat_show_normal(struct seq_file *m,
286 struct ftrace_branch_data *p, const char *f)
287{
288 seq_printf(m, "%8lu %8lu ", p->correct, p->incorrect);
289 branch_stat_show(m, p, f);
290 return 0;
291}
292
293static int annotate_branch_stat_show(struct seq_file *m, void *v)
294{
295 struct ftrace_likely_data *p = v;
296 const char *f;
297 int l;
298
299 f = branch_stat_process_file(&p->data);
300
301 if (!p->constant)
302 return branch_stat_show_normal(m, &p->data, f);
303
304 l = snprintf(NULL, 0, "/%lu", p->constant);
305 l = l > 8 ? 0 : 8 - l;
306
307 seq_printf(m, "%8lu/%lu %*lu ",
308 p->data.correct, p->constant, l, p->data.incorrect);
309 branch_stat_show(m, &p->data, f);
310 return 0;
311}
312
313static void *annotated_branch_stat_start(struct tracer_stat *trace)
314{
315 return __start_annotated_branch_profile;
316}
317
318static void *
319annotated_branch_stat_next(void *v, int idx)
320{
321 struct ftrace_likely_data *p = v;
322
323 ++p;
324
325 if ((void *)p >= (void *)__stop_annotated_branch_profile)
326 return NULL;
327
328 return p;
329}
330
331static int annotated_branch_stat_cmp(void *p1, void *p2)
332{
333 struct ftrace_branch_data *a = p1;
334 struct ftrace_branch_data *b = p2;
335
336 long percent_a, percent_b;
337
338 percent_a = get_incorrect_percent(a);
339 percent_b = get_incorrect_percent(b);
340
341 if (percent_a < percent_b)
342 return -1;
343 if (percent_a > percent_b)
344 return 1;
345
346 if (a->incorrect < b->incorrect)
347 return -1;
348 if (a->incorrect > b->incorrect)
349 return 1;
350
351 /*
352 * Since the above shows worse (incorrect) cases
353 * first, we continue that by showing best (correct)
354 * cases last.
355 */
356 if (a->correct > b->correct)
357 return -1;
358 if (a->correct < b->correct)
359 return 1;
360
361 return 0;
362}
363
364static struct tracer_stat annotated_branch_stats = {
365 .name = "branch_annotated",
366 .stat_start = annotated_branch_stat_start,
367 .stat_next = annotated_branch_stat_next,
368 .stat_cmp = annotated_branch_stat_cmp,
369 .stat_headers = annotated_branch_stat_headers,
370 .stat_show = annotate_branch_stat_show
371};
372
373__init static int init_annotated_branch_stats(void)
374{
375 int ret;
376
377 ret = register_stat_tracer(&annotated_branch_stats);
378 if (!ret) {
379 printk(KERN_WARNING "Warning: could not register "
380 "annotated branches stats\n");
381 return 1;
382 }
383 return 0;
384}
385fs_initcall(init_annotated_branch_stats);
386
387#ifdef CONFIG_PROFILE_ALL_BRANCHES
388
389extern unsigned long __start_branch_profile[];
390extern unsigned long __stop_branch_profile[];
391
392static int all_branch_stat_headers(struct seq_file *m)
393{
394 seq_puts(m, " miss hit % "
395 " Function "
396 " File Line\n"
397 " ------- --------- - "
398 " -------- "
399 " ---- ----\n");
400 return 0;
401}
402
403static void *all_branch_stat_start(struct tracer_stat *trace)
404{
405 return __start_branch_profile;
406}
407
408static void *
409all_branch_stat_next(void *v, int idx)
410{
411 struct ftrace_branch_data *p = v;
412
413 ++p;
414
415 if ((void *)p >= (void *)__stop_branch_profile)
416 return NULL;
417
418 return p;
419}
420
421static int all_branch_stat_show(struct seq_file *m, void *v)
422{
423 struct ftrace_branch_data *p = v;
424 const char *f;
425
426 f = branch_stat_process_file(p);
427 return branch_stat_show_normal(m, p, f);
428}
429
430static struct tracer_stat all_branch_stats = {
431 .name = "branch_all",
432 .stat_start = all_branch_stat_start,
433 .stat_next = all_branch_stat_next,
434 .stat_headers = all_branch_stat_headers,
435 .stat_show = all_branch_stat_show
436};
437
438__init static int all_annotated_branch_stats(void)
439{
440 int ret;
441
442 ret = register_stat_tracer(&all_branch_stats);
443 if (!ret) {
444 printk(KERN_WARNING "Warning: could not register "
445 "all branches stats\n");
446 return 1;
447 }
448 return 0;
449}
450fs_initcall(all_annotated_branch_stats);
451#endif /* CONFIG_PROFILE_ALL_BRANCHES */
452

Warning: That file was not part of the compilation database. It may have many parsing errors.