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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * ring buffer based function tracer
4 *
5 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
6 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
7 *
8 * Based on code from the latency_tracer, that is:
9 *
10 * Copyright (C) 2004-2006 Ingo Molnar
11 * Copyright (C) 2004 Nadia Yvette Chambers
12 */
13#include <linux/ring_buffer.h>
14#include <linux/debugfs.h>
15#include <linux/uaccess.h>
16#include <linux/ftrace.h>
17#include <linux/slab.h>
18#include <linux/fs.h>
19
20#include "trace.h"
21
22static void tracing_start_function_trace(struct trace_array *tr);
23static void tracing_stop_function_trace(struct trace_array *tr);
24static void
25function_trace_call(unsigned long ip, unsigned long parent_ip,
26 struct ftrace_ops *op, struct ftrace_regs *fregs);
27static void
28function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
29 struct ftrace_ops *op, struct ftrace_regs *fregs);
30static void
31function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
32 struct ftrace_ops *op, struct ftrace_regs *fregs);
33static void
34function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
35 struct ftrace_ops *op,
36 struct ftrace_regs *fregs);
37static struct tracer_flags func_flags;
38
39/* Our option */
40enum {
41
42 TRACE_FUNC_NO_OPTS = 0x0, /* No flags set. */
43 TRACE_FUNC_OPT_STACK = 0x1,
44 TRACE_FUNC_OPT_NO_REPEATS = 0x2,
45
46 /* Update this to next highest bit. */
47 TRACE_FUNC_OPT_HIGHEST_BIT = 0x4
48};
49
50#define TRACE_FUNC_OPT_MASK (TRACE_FUNC_OPT_HIGHEST_BIT - 1)
51
52int ftrace_allocate_ftrace_ops(struct trace_array *tr)
53{
54 struct ftrace_ops *ops;
55
56 /* The top level array uses the "global_ops" */
57 if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
58 return 0;
59
60 ops = kzalloc(sizeof(*ops), GFP_KERNEL);
61 if (!ops)
62 return -ENOMEM;
63
64 /* Currently only the non stack version is supported */
65 ops->func = function_trace_call;
66 ops->flags = FTRACE_OPS_FL_PID;
67
68 tr->ops = ops;
69 ops->private = tr;
70
71 return 0;
72}
73
74void ftrace_free_ftrace_ops(struct trace_array *tr)
75{
76 kfree(tr->ops);
77 tr->ops = NULL;
78}
79
80int ftrace_create_function_files(struct trace_array *tr,
81 struct dentry *parent)
82{
83 /*
84 * The top level array uses the "global_ops", and the files are
85 * created on boot up.
86 */
87 if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
88 return 0;
89
90 if (!tr->ops)
91 return -EINVAL;
92
93 ftrace_create_filter_files(tr->ops, parent);
94
95 return 0;
96}
97
98void ftrace_destroy_function_files(struct trace_array *tr)
99{
100 ftrace_destroy_filter_files(tr->ops);
101 ftrace_free_ftrace_ops(tr);
102}
103
104static ftrace_func_t select_trace_function(u32 flags_val)
105{
106 switch (flags_val & TRACE_FUNC_OPT_MASK) {
107 case TRACE_FUNC_NO_OPTS:
108 return function_trace_call;
109 case TRACE_FUNC_OPT_STACK:
110 return function_stack_trace_call;
111 case TRACE_FUNC_OPT_NO_REPEATS:
112 return function_no_repeats_trace_call;
113 case TRACE_FUNC_OPT_STACK | TRACE_FUNC_OPT_NO_REPEATS:
114 return function_stack_no_repeats_trace_call;
115 default:
116 return NULL;
117 }
118}
119
120static bool handle_func_repeats(struct trace_array *tr, u32 flags_val)
121{
122 if (!tr->last_func_repeats &&
123 (flags_val & TRACE_FUNC_OPT_NO_REPEATS)) {
124 tr->last_func_repeats = alloc_percpu(struct trace_func_repeats);
125 if (!tr->last_func_repeats)
126 return false;
127 }
128
129 return true;
130}
131
132static int function_trace_init(struct trace_array *tr)
133{
134 ftrace_func_t func;
135 /*
136 * Instance trace_arrays get their ops allocated
137 * at instance creation. Unless it failed
138 * the allocation.
139 */
140 if (!tr->ops)
141 return -ENOMEM;
142
143 func = select_trace_function(func_flags.val);
144 if (!func)
145 return -EINVAL;
146
147 if (!handle_func_repeats(tr, func_flags.val))
148 return -ENOMEM;
149
150 ftrace_init_array_ops(tr, func);
151
152 tr->array_buffer.cpu = raw_smp_processor_id();
153
154 tracing_start_cmdline_record();
155 tracing_start_function_trace(tr);
156 return 0;
157}
158
159static void function_trace_reset(struct trace_array *tr)
160{
161 tracing_stop_function_trace(tr);
162 tracing_stop_cmdline_record();
163 ftrace_reset_array_ops(tr);
164}
165
166static void function_trace_start(struct trace_array *tr)
167{
168 tracing_reset_online_cpus(&tr->array_buffer);
169}
170
171static void
172function_trace_call(unsigned long ip, unsigned long parent_ip,
173 struct ftrace_ops *op, struct ftrace_regs *fregs)
174{
175 struct trace_array *tr = op->private;
176 struct trace_array_cpu *data;
177 unsigned int trace_ctx;
178 int bit;
179 int cpu;
180
181 if (unlikely(!tr->function_enabled))
182 return;
183
184 bit = ftrace_test_recursion_trylock(ip, parent_ip);
185 if (bit < 0)
186 return;
187
188 trace_ctx = tracing_gen_ctx();
189
190 cpu = smp_processor_id();
191 data = per_cpu_ptr(tr->array_buffer.data, cpu);
192 if (!atomic_read(&data->disabled))
193 trace_function(tr, ip, parent_ip, trace_ctx);
194
195 ftrace_test_recursion_unlock(bit);
196}
197
198#ifdef CONFIG_UNWINDER_ORC
199/*
200 * Skip 2:
201 *
202 * function_stack_trace_call()
203 * ftrace_call()
204 */
205#define STACK_SKIP 2
206#else
207/*
208 * Skip 3:
209 * __trace_stack()
210 * function_stack_trace_call()
211 * ftrace_call()
212 */
213#define STACK_SKIP 3
214#endif
215
216static void
217function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
218 struct ftrace_ops *op, struct ftrace_regs *fregs)
219{
220 struct trace_array *tr = op->private;
221 struct trace_array_cpu *data;
222 unsigned long flags;
223 long disabled;
224 int cpu;
225 unsigned int trace_ctx;
226
227 if (unlikely(!tr->function_enabled))
228 return;
229
230 /*
231 * Need to use raw, since this must be called before the
232 * recursive protection is performed.
233 */
234 local_irq_save(flags);
235 cpu = raw_smp_processor_id();
236 data = per_cpu_ptr(tr->array_buffer.data, cpu);
237 disabled = atomic_inc_return(&data->disabled);
238
239 if (likely(disabled == 1)) {
240 trace_ctx = tracing_gen_ctx_flags(flags);
241 trace_function(tr, ip, parent_ip, trace_ctx);
242 __trace_stack(tr, trace_ctx, STACK_SKIP);
243 }
244
245 atomic_dec(&data->disabled);
246 local_irq_restore(flags);
247}
248
249static inline bool is_repeat_check(struct trace_array *tr,
250 struct trace_func_repeats *last_info,
251 unsigned long ip, unsigned long parent_ip)
252{
253 if (last_info->ip == ip &&
254 last_info->parent_ip == parent_ip &&
255 last_info->count < U16_MAX) {
256 last_info->ts_last_call =
257 ring_buffer_time_stamp(tr->array_buffer.buffer);
258 last_info->count++;
259 return true;
260 }
261
262 return false;
263}
264
265static inline void process_repeats(struct trace_array *tr,
266 unsigned long ip, unsigned long parent_ip,
267 struct trace_func_repeats *last_info,
268 unsigned int trace_ctx)
269{
270 if (last_info->count) {
271 trace_last_func_repeats(tr, last_info, trace_ctx);
272 last_info->count = 0;
273 }
274
275 last_info->ip = ip;
276 last_info->parent_ip = parent_ip;
277}
278
279static void
280function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
281 struct ftrace_ops *op,
282 struct ftrace_regs *fregs)
283{
284 struct trace_func_repeats *last_info;
285 struct trace_array *tr = op->private;
286 struct trace_array_cpu *data;
287 unsigned int trace_ctx;
288 unsigned long flags;
289 int bit;
290 int cpu;
291
292 if (unlikely(!tr->function_enabled))
293 return;
294
295 bit = ftrace_test_recursion_trylock(ip, parent_ip);
296 if (bit < 0)
297 return;
298
299 cpu = smp_processor_id();
300 data = per_cpu_ptr(tr->array_buffer.data, cpu);
301 if (atomic_read(&data->disabled))
302 goto out;
303
304 /*
305 * An interrupt may happen at any place here. But as far as I can see,
306 * the only damage that this can cause is to mess up the repetition
307 * counter without valuable data being lost.
308 * TODO: think about a solution that is better than just hoping to be
309 * lucky.
310 */
311 last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
312 if (is_repeat_check(tr, last_info, ip, parent_ip))
313 goto out;
314
315 local_save_flags(flags);
316 trace_ctx = tracing_gen_ctx_flags(flags);
317 process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
318
319 trace_function(tr, ip, parent_ip, trace_ctx);
320
321out:
322 ftrace_test_recursion_unlock(bit);
323}
324
325static void
326function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
327 struct ftrace_ops *op,
328 struct ftrace_regs *fregs)
329{
330 struct trace_func_repeats *last_info;
331 struct trace_array *tr = op->private;
332 struct trace_array_cpu *data;
333 unsigned long flags;
334 long disabled;
335 int cpu;
336 unsigned int trace_ctx;
337
338 if (unlikely(!tr->function_enabled))
339 return;
340
341 /*
342 * Need to use raw, since this must be called before the
343 * recursive protection is performed.
344 */
345 local_irq_save(flags);
346 cpu = raw_smp_processor_id();
347 data = per_cpu_ptr(tr->array_buffer.data, cpu);
348 disabled = atomic_inc_return(&data->disabled);
349
350 if (likely(disabled == 1)) {
351 last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
352 if (is_repeat_check(tr, last_info, ip, parent_ip))
353 goto out;
354
355 trace_ctx = tracing_gen_ctx_flags(flags);
356 process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
357
358 trace_function(tr, ip, parent_ip, trace_ctx);
359 __trace_stack(tr, trace_ctx, STACK_SKIP);
360 }
361
362 out:
363 atomic_dec(&data->disabled);
364 local_irq_restore(flags);
365}
366
367static struct tracer_opt func_opts[] = {
368#ifdef CONFIG_STACKTRACE
369 { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
370#endif
371 { TRACER_OPT(func-no-repeats, TRACE_FUNC_OPT_NO_REPEATS) },
372 { } /* Always set a last empty entry */
373};
374
375static struct tracer_flags func_flags = {
376 .val = TRACE_FUNC_NO_OPTS, /* By default: all flags disabled */
377 .opts = func_opts
378};
379
380static void tracing_start_function_trace(struct trace_array *tr)
381{
382 tr->function_enabled = 0;
383 register_ftrace_function(tr->ops);
384 tr->function_enabled = 1;
385}
386
387static void tracing_stop_function_trace(struct trace_array *tr)
388{
389 tr->function_enabled = 0;
390 unregister_ftrace_function(tr->ops);
391}
392
393static struct tracer function_trace;
394
395static int
396func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
397{
398 ftrace_func_t func;
399 u32 new_flags;
400
401 /* Do nothing if already set. */
402 if (!!set == !!(func_flags.val & bit))
403 return 0;
404
405 /* We can change this flag only when not running. */
406 if (tr->current_trace != &function_trace)
407 return 0;
408
409 new_flags = (func_flags.val & ~bit) | (set ? bit : 0);
410 func = select_trace_function(new_flags);
411 if (!func)
412 return -EINVAL;
413
414 /* Check if there's anything to change. */
415 if (tr->ops->func == func)
416 return 0;
417
418 if (!handle_func_repeats(tr, new_flags))
419 return -ENOMEM;
420
421 unregister_ftrace_function(tr->ops);
422 tr->ops->func = func;
423 register_ftrace_function(tr->ops);
424
425 return 0;
426}
427
428static struct tracer function_trace __tracer_data =
429{
430 .name = "function",
431 .init = function_trace_init,
432 .reset = function_trace_reset,
433 .start = function_trace_start,
434 .flags = &func_flags,
435 .set_flag = func_set_flag,
436 .allow_instances = true,
437#ifdef CONFIG_FTRACE_SELFTEST
438 .selftest = trace_selftest_startup_function,
439#endif
440};
441
442#ifdef CONFIG_DYNAMIC_FTRACE
443static void update_traceon_count(struct ftrace_probe_ops *ops,
444 unsigned long ip,
445 struct trace_array *tr, bool on,
446 void *data)
447{
448 struct ftrace_func_mapper *mapper = data;
449 long *count;
450 long old_count;
451
452 /*
453 * Tracing gets disabled (or enabled) once per count.
454 * This function can be called at the same time on multiple CPUs.
455 * It is fine if both disable (or enable) tracing, as disabling
456 * (or enabling) the second time doesn't do anything as the
457 * state of the tracer is already disabled (or enabled).
458 * What needs to be synchronized in this case is that the count
459 * only gets decremented once, even if the tracer is disabled
460 * (or enabled) twice, as the second one is really a nop.
461 *
462 * The memory barriers guarantee that we only decrement the
463 * counter once. First the count is read to a local variable
464 * and a read barrier is used to make sure that it is loaded
465 * before checking if the tracer is in the state we want.
466 * If the tracer is not in the state we want, then the count
467 * is guaranteed to be the old count.
468 *
469 * Next the tracer is set to the state we want (disabled or enabled)
470 * then a write memory barrier is used to make sure that
471 * the new state is visible before changing the counter by
472 * one minus the old counter. This guarantees that another CPU
473 * executing this code will see the new state before seeing
474 * the new counter value, and would not do anything if the new
475 * counter is seen.
476 *
477 * Note, there is no synchronization between this and a user
478 * setting the tracing_on file. But we currently don't care
479 * about that.
480 */
481 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
482 old_count = *count;
483
484 if (old_count <= 0)
485 return;
486
487 /* Make sure we see count before checking tracing state */
488 smp_rmb();
489
490 if (on == !!tracer_tracing_is_on(tr))
491 return;
492
493 if (on)
494 tracer_tracing_on(tr);
495 else
496 tracer_tracing_off(tr);
497
498 /* Make sure tracing state is visible before updating count */
499 smp_wmb();
500
501 *count = old_count - 1;
502}
503
504static void
505ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
506 struct trace_array *tr, struct ftrace_probe_ops *ops,
507 void *data)
508{
509 update_traceon_count(ops, ip, tr, 1, data);
510}
511
512static void
513ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
514 struct trace_array *tr, struct ftrace_probe_ops *ops,
515 void *data)
516{
517 update_traceon_count(ops, ip, tr, 0, data);
518}
519
520static void
521ftrace_traceon(unsigned long ip, unsigned long parent_ip,
522 struct trace_array *tr, struct ftrace_probe_ops *ops,
523 void *data)
524{
525 if (tracer_tracing_is_on(tr))
526 return;
527
528 tracer_tracing_on(tr);
529}
530
531static void
532ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
533 struct trace_array *tr, struct ftrace_probe_ops *ops,
534 void *data)
535{
536 if (!tracer_tracing_is_on(tr))
537 return;
538
539 tracer_tracing_off(tr);
540}
541
542#ifdef CONFIG_UNWINDER_ORC
543/*
544 * Skip 3:
545 *
546 * function_trace_probe_call()
547 * ftrace_ops_assist_func()
548 * ftrace_call()
549 */
550#define FTRACE_STACK_SKIP 3
551#else
552/*
553 * Skip 5:
554 *
555 * __trace_stack()
556 * ftrace_stacktrace()
557 * function_trace_probe_call()
558 * ftrace_ops_assist_func()
559 * ftrace_call()
560 */
561#define FTRACE_STACK_SKIP 5
562#endif
563
564static __always_inline void trace_stack(struct trace_array *tr)
565{
566 unsigned int trace_ctx;
567
568 trace_ctx = tracing_gen_ctx();
569
570 __trace_stack(tr, trace_ctx, FTRACE_STACK_SKIP);
571}
572
573static void
574ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
575 struct trace_array *tr, struct ftrace_probe_ops *ops,
576 void *data)
577{
578 trace_stack(tr);
579}
580
581static void
582ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
583 struct trace_array *tr, struct ftrace_probe_ops *ops,
584 void *data)
585{
586 struct ftrace_func_mapper *mapper = data;
587 long *count;
588 long old_count;
589 long new_count;
590
591 if (!tracing_is_on())
592 return;
593
594 /* unlimited? */
595 if (!mapper) {
596 trace_stack(tr);
597 return;
598 }
599
600 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
601
602 /*
603 * Stack traces should only execute the number of times the
604 * user specified in the counter.
605 */
606 do {
607 old_count = *count;
608
609 if (!old_count)
610 return;
611
612 new_count = old_count - 1;
613 new_count = cmpxchg(count, old_count, new_count);
614 if (new_count == old_count)
615 trace_stack(tr);
616
617 if (!tracing_is_on())
618 return;
619
620 } while (new_count != old_count);
621}
622
623static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
624 void *data)
625{
626 struct ftrace_func_mapper *mapper = data;
627 long *count = NULL;
628
629 if (mapper)
630 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
631
632 if (count) {
633 if (*count <= 0)
634 return 0;
635 (*count)--;
636 }
637
638 return 1;
639}
640
641static void
642ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
643 struct trace_array *tr, struct ftrace_probe_ops *ops,
644 void *data)
645{
646 if (update_count(ops, ip, data))
647 ftrace_dump(DUMP_ALL);
648}
649
650/* Only dump the current CPU buffer. */
651static void
652ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
653 struct trace_array *tr, struct ftrace_probe_ops *ops,
654 void *data)
655{
656 if (update_count(ops, ip, data))
657 ftrace_dump(DUMP_ORIG);
658}
659
660static int
661ftrace_probe_print(const char *name, struct seq_file *m,
662 unsigned long ip, struct ftrace_probe_ops *ops,
663 void *data)
664{
665 struct ftrace_func_mapper *mapper = data;
666 long *count = NULL;
667
668 seq_printf(m, "%ps:%s", (void *)ip, name);
669
670 if (mapper)
671 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
672
673 if (count)
674 seq_printf(m, ":count=%ld\n", *count);
675 else
676 seq_puts(m, ":unlimited\n");
677
678 return 0;
679}
680
681static int
682ftrace_traceon_print(struct seq_file *m, unsigned long ip,
683 struct ftrace_probe_ops *ops,
684 void *data)
685{
686 return ftrace_probe_print("traceon", m, ip, ops, data);
687}
688
689static int
690ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
691 struct ftrace_probe_ops *ops, void *data)
692{
693 return ftrace_probe_print("traceoff", m, ip, ops, data);
694}
695
696static int
697ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
698 struct ftrace_probe_ops *ops, void *data)
699{
700 return ftrace_probe_print("stacktrace", m, ip, ops, data);
701}
702
703static int
704ftrace_dump_print(struct seq_file *m, unsigned long ip,
705 struct ftrace_probe_ops *ops, void *data)
706{
707 return ftrace_probe_print("dump", m, ip, ops, data);
708}
709
710static int
711ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
712 struct ftrace_probe_ops *ops, void *data)
713{
714 return ftrace_probe_print("cpudump", m, ip, ops, data);
715}
716
717
718static int
719ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
720 unsigned long ip, void *init_data, void **data)
721{
722 struct ftrace_func_mapper *mapper = *data;
723
724 if (!mapper) {
725 mapper = allocate_ftrace_func_mapper();
726 if (!mapper)
727 return -ENOMEM;
728 *data = mapper;
729 }
730
731 return ftrace_func_mapper_add_ip(mapper, ip, init_data);
732}
733
734static void
735ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
736 unsigned long ip, void *data)
737{
738 struct ftrace_func_mapper *mapper = data;
739
740 if (!ip) {
741 free_ftrace_func_mapper(mapper, NULL);
742 return;
743 }
744
745 ftrace_func_mapper_remove_ip(mapper, ip);
746}
747
748static struct ftrace_probe_ops traceon_count_probe_ops = {
749 .func = ftrace_traceon_count,
750 .print = ftrace_traceon_print,
751 .init = ftrace_count_init,
752 .free = ftrace_count_free,
753};
754
755static struct ftrace_probe_ops traceoff_count_probe_ops = {
756 .func = ftrace_traceoff_count,
757 .print = ftrace_traceoff_print,
758 .init = ftrace_count_init,
759 .free = ftrace_count_free,
760};
761
762static struct ftrace_probe_ops stacktrace_count_probe_ops = {
763 .func = ftrace_stacktrace_count,
764 .print = ftrace_stacktrace_print,
765 .init = ftrace_count_init,
766 .free = ftrace_count_free,
767};
768
769static struct ftrace_probe_ops dump_probe_ops = {
770 .func = ftrace_dump_probe,
771 .print = ftrace_dump_print,
772 .init = ftrace_count_init,
773 .free = ftrace_count_free,
774};
775
776static struct ftrace_probe_ops cpudump_probe_ops = {
777 .func = ftrace_cpudump_probe,
778 .print = ftrace_cpudump_print,
779};
780
781static struct ftrace_probe_ops traceon_probe_ops = {
782 .func = ftrace_traceon,
783 .print = ftrace_traceon_print,
784};
785
786static struct ftrace_probe_ops traceoff_probe_ops = {
787 .func = ftrace_traceoff,
788 .print = ftrace_traceoff_print,
789};
790
791static struct ftrace_probe_ops stacktrace_probe_ops = {
792 .func = ftrace_stacktrace,
793 .print = ftrace_stacktrace_print,
794};
795
796static int
797ftrace_trace_probe_callback(struct trace_array *tr,
798 struct ftrace_probe_ops *ops,
799 struct ftrace_hash *hash, char *glob,
800 char *cmd, char *param, int enable)
801{
802 void *count = (void *)-1;
803 char *number;
804 int ret;
805
806 /* hash funcs only work with set_ftrace_filter */
807 if (!enable)
808 return -EINVAL;
809
810 if (glob[0] == '!')
811 return unregister_ftrace_function_probe_func(glob+1, tr, ops);
812
813 if (!param)
814 goto out_reg;
815
816 number = strsep(¶m, ":");
817
818 if (!strlen(number))
819 goto out_reg;
820
821 /*
822 * We use the callback data field (which is a pointer)
823 * as our counter.
824 */
825 ret = kstrtoul(number, 0, (unsigned long *)&count);
826 if (ret)
827 return ret;
828
829 out_reg:
830 ret = register_ftrace_function_probe(glob, tr, ops, count);
831
832 return ret < 0 ? ret : 0;
833}
834
835static int
836ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
837 char *glob, char *cmd, char *param, int enable)
838{
839 struct ftrace_probe_ops *ops;
840
841 if (!tr)
842 return -ENODEV;
843
844 /* we register both traceon and traceoff to this callback */
845 if (strcmp(cmd, "traceon") == 0)
846 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
847 else
848 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
849
850 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
851 param, enable);
852}
853
854static int
855ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
856 char *glob, char *cmd, char *param, int enable)
857{
858 struct ftrace_probe_ops *ops;
859
860 if (!tr)
861 return -ENODEV;
862
863 ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
864
865 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
866 param, enable);
867}
868
869static int
870ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
871 char *glob, char *cmd, char *param, int enable)
872{
873 struct ftrace_probe_ops *ops;
874
875 if (!tr)
876 return -ENODEV;
877
878 ops = &dump_probe_ops;
879
880 /* Only dump once. */
881 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
882 "1", enable);
883}
884
885static int
886ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
887 char *glob, char *cmd, char *param, int enable)
888{
889 struct ftrace_probe_ops *ops;
890
891 if (!tr)
892 return -ENODEV;
893
894 ops = &cpudump_probe_ops;
895
896 /* Only dump once. */
897 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
898 "1", enable);
899}
900
901static struct ftrace_func_command ftrace_traceon_cmd = {
902 .name = "traceon",
903 .func = ftrace_trace_onoff_callback,
904};
905
906static struct ftrace_func_command ftrace_traceoff_cmd = {
907 .name = "traceoff",
908 .func = ftrace_trace_onoff_callback,
909};
910
911static struct ftrace_func_command ftrace_stacktrace_cmd = {
912 .name = "stacktrace",
913 .func = ftrace_stacktrace_callback,
914};
915
916static struct ftrace_func_command ftrace_dump_cmd = {
917 .name = "dump",
918 .func = ftrace_dump_callback,
919};
920
921static struct ftrace_func_command ftrace_cpudump_cmd = {
922 .name = "cpudump",
923 .func = ftrace_cpudump_callback,
924};
925
926static int __init init_func_cmd_traceon(void)
927{
928 int ret;
929
930 ret = register_ftrace_command(&ftrace_traceoff_cmd);
931 if (ret)
932 return ret;
933
934 ret = register_ftrace_command(&ftrace_traceon_cmd);
935 if (ret)
936 goto out_free_traceoff;
937
938 ret = register_ftrace_command(&ftrace_stacktrace_cmd);
939 if (ret)
940 goto out_free_traceon;
941
942 ret = register_ftrace_command(&ftrace_dump_cmd);
943 if (ret)
944 goto out_free_stacktrace;
945
946 ret = register_ftrace_command(&ftrace_cpudump_cmd);
947 if (ret)
948 goto out_free_dump;
949
950 return 0;
951
952 out_free_dump:
953 unregister_ftrace_command(&ftrace_dump_cmd);
954 out_free_stacktrace:
955 unregister_ftrace_command(&ftrace_stacktrace_cmd);
956 out_free_traceon:
957 unregister_ftrace_command(&ftrace_traceon_cmd);
958 out_free_traceoff:
959 unregister_ftrace_command(&ftrace_traceoff_cmd);
960
961 return ret;
962}
963#else
964static inline int init_func_cmd_traceon(void)
965{
966 return 0;
967}
968#endif /* CONFIG_DYNAMIC_FTRACE */
969
970__init int init_function_trace(void)
971{
972 init_func_cmd_traceon();
973 return register_tracer(&function_trace);
974}
1/*
2 * ring buffer based function tracer
3 *
4 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
5 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
6 *
7 * Based on code from the latency_tracer, that is:
8 *
9 * Copyright (C) 2004-2006 Ingo Molnar
10 * Copyright (C) 2004 Nadia Yvette Chambers
11 */
12#include <linux/ring_buffer.h>
13#include <linux/debugfs.h>
14#include <linux/uaccess.h>
15#include <linux/ftrace.h>
16#include <linux/slab.h>
17#include <linux/fs.h>
18
19#include "trace.h"
20
21static void tracing_start_function_trace(struct trace_array *tr);
22static void tracing_stop_function_trace(struct trace_array *tr);
23static void
24function_trace_call(unsigned long ip, unsigned long parent_ip,
25 struct ftrace_ops *op, struct pt_regs *pt_regs);
26static void
27function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
28 struct ftrace_ops *op, struct pt_regs *pt_regs);
29static struct tracer_flags func_flags;
30
31/* Our option */
32enum {
33 TRACE_FUNC_OPT_STACK = 0x1,
34};
35
36static int allocate_ftrace_ops(struct trace_array *tr)
37{
38 struct ftrace_ops *ops;
39
40 ops = kzalloc(sizeof(*ops), GFP_KERNEL);
41 if (!ops)
42 return -ENOMEM;
43
44 /* Currently only the non stack verision is supported */
45 ops->func = function_trace_call;
46 ops->flags = FTRACE_OPS_FL_RECURSION_SAFE;
47
48 tr->ops = ops;
49 ops->private = tr;
50 return 0;
51}
52
53
54int ftrace_create_function_files(struct trace_array *tr,
55 struct dentry *parent)
56{
57 int ret;
58
59 /*
60 * The top level array uses the "global_ops", and the files are
61 * created on boot up.
62 */
63 if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
64 return 0;
65
66 ret = allocate_ftrace_ops(tr);
67 if (ret)
68 return ret;
69
70 ftrace_create_filter_files(tr->ops, parent);
71
72 return 0;
73}
74
75void ftrace_destroy_function_files(struct trace_array *tr)
76{
77 ftrace_destroy_filter_files(tr->ops);
78 kfree(tr->ops);
79 tr->ops = NULL;
80}
81
82static int function_trace_init(struct trace_array *tr)
83{
84 ftrace_func_t func;
85
86 /*
87 * Instance trace_arrays get their ops allocated
88 * at instance creation. Unless it failed
89 * the allocation.
90 */
91 if (!tr->ops)
92 return -ENOMEM;
93
94 /* Currently only the global instance can do stack tracing */
95 if (tr->flags & TRACE_ARRAY_FL_GLOBAL &&
96 func_flags.val & TRACE_FUNC_OPT_STACK)
97 func = function_stack_trace_call;
98 else
99 func = function_trace_call;
100
101 ftrace_init_array_ops(tr, func);
102
103 tr->trace_buffer.cpu = get_cpu();
104 put_cpu();
105
106 tracing_start_cmdline_record();
107 tracing_start_function_trace(tr);
108 return 0;
109}
110
111static void function_trace_reset(struct trace_array *tr)
112{
113 tracing_stop_function_trace(tr);
114 tracing_stop_cmdline_record();
115 ftrace_reset_array_ops(tr);
116}
117
118static void function_trace_start(struct trace_array *tr)
119{
120 tracing_reset_online_cpus(&tr->trace_buffer);
121}
122
123static void
124function_trace_call(unsigned long ip, unsigned long parent_ip,
125 struct ftrace_ops *op, struct pt_regs *pt_regs)
126{
127 struct trace_array *tr = op->private;
128 struct trace_array_cpu *data;
129 unsigned long flags;
130 int bit;
131 int cpu;
132 int pc;
133
134 if (unlikely(!tr->function_enabled))
135 return;
136
137 pc = preempt_count();
138 preempt_disable_notrace();
139
140 bit = trace_test_and_set_recursion(TRACE_FTRACE_START, TRACE_FTRACE_MAX);
141 if (bit < 0)
142 goto out;
143
144 cpu = smp_processor_id();
145 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
146 if (!atomic_read(&data->disabled)) {
147 local_save_flags(flags);
148 trace_function(tr, ip, parent_ip, flags, pc);
149 }
150 trace_clear_recursion(bit);
151
152 out:
153 preempt_enable_notrace();
154}
155
156static void
157function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
158 struct ftrace_ops *op, struct pt_regs *pt_regs)
159{
160 struct trace_array *tr = op->private;
161 struct trace_array_cpu *data;
162 unsigned long flags;
163 long disabled;
164 int cpu;
165 int pc;
166
167 if (unlikely(!tr->function_enabled))
168 return;
169
170 /*
171 * Need to use raw, since this must be called before the
172 * recursive protection is performed.
173 */
174 local_irq_save(flags);
175 cpu = raw_smp_processor_id();
176 data = per_cpu_ptr(tr->trace_buffer.data, cpu);
177 disabled = atomic_inc_return(&data->disabled);
178
179 if (likely(disabled == 1)) {
180 pc = preempt_count();
181 trace_function(tr, ip, parent_ip, flags, pc);
182 /*
183 * skip over 5 funcs:
184 * __ftrace_trace_stack,
185 * __trace_stack,
186 * function_stack_trace_call
187 * ftrace_list_func
188 * ftrace_call
189 */
190 __trace_stack(tr, flags, 5, pc);
191 }
192
193 atomic_dec(&data->disabled);
194 local_irq_restore(flags);
195}
196
197static struct tracer_opt func_opts[] = {
198#ifdef CONFIG_STACKTRACE
199 { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
200#endif
201 { } /* Always set a last empty entry */
202};
203
204static struct tracer_flags func_flags = {
205 .val = 0, /* By default: all flags disabled */
206 .opts = func_opts
207};
208
209static void tracing_start_function_trace(struct trace_array *tr)
210{
211 tr->function_enabled = 0;
212 register_ftrace_function(tr->ops);
213 tr->function_enabled = 1;
214}
215
216static void tracing_stop_function_trace(struct trace_array *tr)
217{
218 tr->function_enabled = 0;
219 unregister_ftrace_function(tr->ops);
220}
221
222static struct tracer function_trace;
223
224static int
225func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
226{
227 switch (bit) {
228 case TRACE_FUNC_OPT_STACK:
229 /* do nothing if already set */
230 if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
231 break;
232
233 /* We can change this flag when not running. */
234 if (tr->current_trace != &function_trace)
235 break;
236
237 unregister_ftrace_function(tr->ops);
238
239 if (set) {
240 tr->ops->func = function_stack_trace_call;
241 register_ftrace_function(tr->ops);
242 } else {
243 tr->ops->func = function_trace_call;
244 register_ftrace_function(tr->ops);
245 }
246
247 break;
248 default:
249 return -EINVAL;
250 }
251
252 return 0;
253}
254
255static struct tracer function_trace __tracer_data =
256{
257 .name = "function",
258 .init = function_trace_init,
259 .reset = function_trace_reset,
260 .start = function_trace_start,
261 .flags = &func_flags,
262 .set_flag = func_set_flag,
263 .allow_instances = true,
264#ifdef CONFIG_FTRACE_SELFTEST
265 .selftest = trace_selftest_startup_function,
266#endif
267};
268
269#ifdef CONFIG_DYNAMIC_FTRACE
270static void update_traceon_count(void **data, bool on)
271{
272 long *count = (long *)data;
273 long old_count = *count;
274
275 /*
276 * Tracing gets disabled (or enabled) once per count.
277 * This function can be called at the same time on multiple CPUs.
278 * It is fine if both disable (or enable) tracing, as disabling
279 * (or enabling) the second time doesn't do anything as the
280 * state of the tracer is already disabled (or enabled).
281 * What needs to be synchronized in this case is that the count
282 * only gets decremented once, even if the tracer is disabled
283 * (or enabled) twice, as the second one is really a nop.
284 *
285 * The memory barriers guarantee that we only decrement the
286 * counter once. First the count is read to a local variable
287 * and a read barrier is used to make sure that it is loaded
288 * before checking if the tracer is in the state we want.
289 * If the tracer is not in the state we want, then the count
290 * is guaranteed to be the old count.
291 *
292 * Next the tracer is set to the state we want (disabled or enabled)
293 * then a write memory barrier is used to make sure that
294 * the new state is visible before changing the counter by
295 * one minus the old counter. This guarantees that another CPU
296 * executing this code will see the new state before seeing
297 * the new counter value, and would not do anything if the new
298 * counter is seen.
299 *
300 * Note, there is no synchronization between this and a user
301 * setting the tracing_on file. But we currently don't care
302 * about that.
303 */
304 if (!old_count)
305 return;
306
307 /* Make sure we see count before checking tracing state */
308 smp_rmb();
309
310 if (on == !!tracing_is_on())
311 return;
312
313 if (on)
314 tracing_on();
315 else
316 tracing_off();
317
318 /* unlimited? */
319 if (old_count == -1)
320 return;
321
322 /* Make sure tracing state is visible before updating count */
323 smp_wmb();
324
325 *count = old_count - 1;
326}
327
328static void
329ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, void **data)
330{
331 update_traceon_count(data, 1);
332}
333
334static void
335ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, void **data)
336{
337 update_traceon_count(data, 0);
338}
339
340static void
341ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
342{
343 if (tracing_is_on())
344 return;
345
346 tracing_on();
347}
348
349static void
350ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
351{
352 if (!tracing_is_on())
353 return;
354
355 tracing_off();
356}
357
358/*
359 * Skip 4:
360 * ftrace_stacktrace()
361 * function_trace_probe_call()
362 * ftrace_ops_list_func()
363 * ftrace_call()
364 */
365#define STACK_SKIP 4
366
367static void
368ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, void **data)
369{
370 trace_dump_stack(STACK_SKIP);
371}
372
373static void
374ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, void **data)
375{
376 long *count = (long *)data;
377 long old_count;
378 long new_count;
379
380 /*
381 * Stack traces should only execute the number of times the
382 * user specified in the counter.
383 */
384 do {
385
386 if (!tracing_is_on())
387 return;
388
389 old_count = *count;
390
391 if (!old_count)
392 return;
393
394 /* unlimited? */
395 if (old_count == -1) {
396 trace_dump_stack(STACK_SKIP);
397 return;
398 }
399
400 new_count = old_count - 1;
401 new_count = cmpxchg(count, old_count, new_count);
402 if (new_count == old_count)
403 trace_dump_stack(STACK_SKIP);
404
405 } while (new_count != old_count);
406}
407
408static int update_count(void **data)
409{
410 unsigned long *count = (long *)data;
411
412 if (!*count)
413 return 0;
414
415 if (*count != -1)
416 (*count)--;
417
418 return 1;
419}
420
421static void
422ftrace_dump_probe(unsigned long ip, unsigned long parent_ip, void **data)
423{
424 if (update_count(data))
425 ftrace_dump(DUMP_ALL);
426}
427
428/* Only dump the current CPU buffer. */
429static void
430ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip, void **data)
431{
432 if (update_count(data))
433 ftrace_dump(DUMP_ORIG);
434}
435
436static int
437ftrace_probe_print(const char *name, struct seq_file *m,
438 unsigned long ip, void *data)
439{
440 long count = (long)data;
441
442 seq_printf(m, "%ps:%s", (void *)ip, name);
443
444 if (count == -1)
445 seq_puts(m, ":unlimited\n");
446 else
447 seq_printf(m, ":count=%ld\n", count);
448
449 return 0;
450}
451
452static int
453ftrace_traceon_print(struct seq_file *m, unsigned long ip,
454 struct ftrace_probe_ops *ops, void *data)
455{
456 return ftrace_probe_print("traceon", m, ip, data);
457}
458
459static int
460ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
461 struct ftrace_probe_ops *ops, void *data)
462{
463 return ftrace_probe_print("traceoff", m, ip, data);
464}
465
466static int
467ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
468 struct ftrace_probe_ops *ops, void *data)
469{
470 return ftrace_probe_print("stacktrace", m, ip, data);
471}
472
473static int
474ftrace_dump_print(struct seq_file *m, unsigned long ip,
475 struct ftrace_probe_ops *ops, void *data)
476{
477 return ftrace_probe_print("dump", m, ip, data);
478}
479
480static int
481ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
482 struct ftrace_probe_ops *ops, void *data)
483{
484 return ftrace_probe_print("cpudump", m, ip, data);
485}
486
487static struct ftrace_probe_ops traceon_count_probe_ops = {
488 .func = ftrace_traceon_count,
489 .print = ftrace_traceon_print,
490};
491
492static struct ftrace_probe_ops traceoff_count_probe_ops = {
493 .func = ftrace_traceoff_count,
494 .print = ftrace_traceoff_print,
495};
496
497static struct ftrace_probe_ops stacktrace_count_probe_ops = {
498 .func = ftrace_stacktrace_count,
499 .print = ftrace_stacktrace_print,
500};
501
502static struct ftrace_probe_ops dump_probe_ops = {
503 .func = ftrace_dump_probe,
504 .print = ftrace_dump_print,
505};
506
507static struct ftrace_probe_ops cpudump_probe_ops = {
508 .func = ftrace_cpudump_probe,
509 .print = ftrace_cpudump_print,
510};
511
512static struct ftrace_probe_ops traceon_probe_ops = {
513 .func = ftrace_traceon,
514 .print = ftrace_traceon_print,
515};
516
517static struct ftrace_probe_ops traceoff_probe_ops = {
518 .func = ftrace_traceoff,
519 .print = ftrace_traceoff_print,
520};
521
522static struct ftrace_probe_ops stacktrace_probe_ops = {
523 .func = ftrace_stacktrace,
524 .print = ftrace_stacktrace_print,
525};
526
527static int
528ftrace_trace_probe_callback(struct ftrace_probe_ops *ops,
529 struct ftrace_hash *hash, char *glob,
530 char *cmd, char *param, int enable)
531{
532 void *count = (void *)-1;
533 char *number;
534 int ret;
535
536 /* hash funcs only work with set_ftrace_filter */
537 if (!enable)
538 return -EINVAL;
539
540 if (glob[0] == '!') {
541 unregister_ftrace_function_probe_func(glob+1, ops);
542 return 0;
543 }
544
545 if (!param)
546 goto out_reg;
547
548 number = strsep(¶m, ":");
549
550 if (!strlen(number))
551 goto out_reg;
552
553 /*
554 * We use the callback data field (which is a pointer)
555 * as our counter.
556 */
557 ret = kstrtoul(number, 0, (unsigned long *)&count);
558 if (ret)
559 return ret;
560
561 out_reg:
562 ret = register_ftrace_function_probe(glob, ops, count);
563
564 return ret < 0 ? ret : 0;
565}
566
567static int
568ftrace_trace_onoff_callback(struct ftrace_hash *hash,
569 char *glob, char *cmd, char *param, int enable)
570{
571 struct ftrace_probe_ops *ops;
572
573 /* we register both traceon and traceoff to this callback */
574 if (strcmp(cmd, "traceon") == 0)
575 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
576 else
577 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
578
579 return ftrace_trace_probe_callback(ops, hash, glob, cmd,
580 param, enable);
581}
582
583static int
584ftrace_stacktrace_callback(struct ftrace_hash *hash,
585 char *glob, char *cmd, char *param, int enable)
586{
587 struct ftrace_probe_ops *ops;
588
589 ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
590
591 return ftrace_trace_probe_callback(ops, hash, glob, cmd,
592 param, enable);
593}
594
595static int
596ftrace_dump_callback(struct ftrace_hash *hash,
597 char *glob, char *cmd, char *param, int enable)
598{
599 struct ftrace_probe_ops *ops;
600
601 ops = &dump_probe_ops;
602
603 /* Only dump once. */
604 return ftrace_trace_probe_callback(ops, hash, glob, cmd,
605 "1", enable);
606}
607
608static int
609ftrace_cpudump_callback(struct ftrace_hash *hash,
610 char *glob, char *cmd, char *param, int enable)
611{
612 struct ftrace_probe_ops *ops;
613
614 ops = &cpudump_probe_ops;
615
616 /* Only dump once. */
617 return ftrace_trace_probe_callback(ops, hash, glob, cmd,
618 "1", enable);
619}
620
621static struct ftrace_func_command ftrace_traceon_cmd = {
622 .name = "traceon",
623 .func = ftrace_trace_onoff_callback,
624};
625
626static struct ftrace_func_command ftrace_traceoff_cmd = {
627 .name = "traceoff",
628 .func = ftrace_trace_onoff_callback,
629};
630
631static struct ftrace_func_command ftrace_stacktrace_cmd = {
632 .name = "stacktrace",
633 .func = ftrace_stacktrace_callback,
634};
635
636static struct ftrace_func_command ftrace_dump_cmd = {
637 .name = "dump",
638 .func = ftrace_dump_callback,
639};
640
641static struct ftrace_func_command ftrace_cpudump_cmd = {
642 .name = "cpudump",
643 .func = ftrace_cpudump_callback,
644};
645
646static int __init init_func_cmd_traceon(void)
647{
648 int ret;
649
650 ret = register_ftrace_command(&ftrace_traceoff_cmd);
651 if (ret)
652 return ret;
653
654 ret = register_ftrace_command(&ftrace_traceon_cmd);
655 if (ret)
656 goto out_free_traceoff;
657
658 ret = register_ftrace_command(&ftrace_stacktrace_cmd);
659 if (ret)
660 goto out_free_traceon;
661
662 ret = register_ftrace_command(&ftrace_dump_cmd);
663 if (ret)
664 goto out_free_stacktrace;
665
666 ret = register_ftrace_command(&ftrace_cpudump_cmd);
667 if (ret)
668 goto out_free_dump;
669
670 return 0;
671
672 out_free_dump:
673 unregister_ftrace_command(&ftrace_dump_cmd);
674 out_free_stacktrace:
675 unregister_ftrace_command(&ftrace_stacktrace_cmd);
676 out_free_traceon:
677 unregister_ftrace_command(&ftrace_traceon_cmd);
678 out_free_traceoff:
679 unregister_ftrace_command(&ftrace_traceoff_cmd);
680
681 return ret;
682}
683#else
684static inline int init_func_cmd_traceon(void)
685{
686 return 0;
687}
688#endif /* CONFIG_DYNAMIC_FTRACE */
689
690static __init int init_function_trace(void)
691{
692 init_func_cmd_traceon();
693 return register_tracer(&function_trace);
694}
695core_initcall(init_function_trace);