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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 int ret;
84 /*
85 * The top level array uses the "global_ops", and the files are
86 * created on boot up.
87 */
88 if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
89 return 0;
90
91 if (!tr->ops)
92 return -EINVAL;
93
94 ret = allocate_fgraph_ops(tr, tr->ops);
95 if (ret) {
96 kfree(tr->ops);
97 return ret;
98 }
99
100 ftrace_create_filter_files(tr->ops, parent);
101
102 return 0;
103}
104
105void ftrace_destroy_function_files(struct trace_array *tr)
106{
107 ftrace_destroy_filter_files(tr->ops);
108 ftrace_free_ftrace_ops(tr);
109 free_fgraph_ops(tr);
110}
111
112static ftrace_func_t select_trace_function(u32 flags_val)
113{
114 switch (flags_val & TRACE_FUNC_OPT_MASK) {
115 case TRACE_FUNC_NO_OPTS:
116 return function_trace_call;
117 case TRACE_FUNC_OPT_STACK:
118 return function_stack_trace_call;
119 case TRACE_FUNC_OPT_NO_REPEATS:
120 return function_no_repeats_trace_call;
121 case TRACE_FUNC_OPT_STACK | TRACE_FUNC_OPT_NO_REPEATS:
122 return function_stack_no_repeats_trace_call;
123 default:
124 return NULL;
125 }
126}
127
128static bool handle_func_repeats(struct trace_array *tr, u32 flags_val)
129{
130 if (!tr->last_func_repeats &&
131 (flags_val & TRACE_FUNC_OPT_NO_REPEATS)) {
132 tr->last_func_repeats = alloc_percpu(struct trace_func_repeats);
133 if (!tr->last_func_repeats)
134 return false;
135 }
136
137 return true;
138}
139
140static int function_trace_init(struct trace_array *tr)
141{
142 ftrace_func_t func;
143 /*
144 * Instance trace_arrays get their ops allocated
145 * at instance creation. Unless it failed
146 * the allocation.
147 */
148 if (!tr->ops)
149 return -ENOMEM;
150
151 func = select_trace_function(func_flags.val);
152 if (!func)
153 return -EINVAL;
154
155 if (!handle_func_repeats(tr, func_flags.val))
156 return -ENOMEM;
157
158 ftrace_init_array_ops(tr, func);
159
160 tr->array_buffer.cpu = raw_smp_processor_id();
161
162 tracing_start_cmdline_record();
163 tracing_start_function_trace(tr);
164 return 0;
165}
166
167static void function_trace_reset(struct trace_array *tr)
168{
169 tracing_stop_function_trace(tr);
170 tracing_stop_cmdline_record();
171 ftrace_reset_array_ops(tr);
172}
173
174static void function_trace_start(struct trace_array *tr)
175{
176 tracing_reset_online_cpus(&tr->array_buffer);
177}
178
179/* fregs are guaranteed not to be NULL if HAVE_DYNAMIC_FTRACE_WITH_ARGS is set */
180#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS)
181static __always_inline unsigned long
182function_get_true_parent_ip(unsigned long parent_ip, struct ftrace_regs *fregs)
183{
184 unsigned long true_parent_ip;
185 int idx = 0;
186
187 true_parent_ip = parent_ip;
188 if (unlikely(parent_ip == (unsigned long)&return_to_handler) && fregs)
189 true_parent_ip = ftrace_graph_ret_addr(current, &idx, parent_ip,
190 (unsigned long *)ftrace_regs_get_stack_pointer(fregs));
191 return true_parent_ip;
192}
193#else
194static __always_inline unsigned long
195function_get_true_parent_ip(unsigned long parent_ip, struct ftrace_regs *fregs)
196{
197 return parent_ip;
198}
199#endif
200
201static void
202function_trace_call(unsigned long ip, unsigned long parent_ip,
203 struct ftrace_ops *op, struct ftrace_regs *fregs)
204{
205 struct trace_array *tr = op->private;
206 struct trace_array_cpu *data;
207 unsigned int trace_ctx;
208 int bit;
209
210 if (unlikely(!tr->function_enabled))
211 return;
212
213 bit = ftrace_test_recursion_trylock(ip, parent_ip);
214 if (bit < 0)
215 return;
216
217 parent_ip = function_get_true_parent_ip(parent_ip, fregs);
218
219 trace_ctx = tracing_gen_ctx_dec();
220
221 data = this_cpu_ptr(tr->array_buffer.data);
222 if (!atomic_read(&data->disabled))
223 trace_function(tr, ip, parent_ip, trace_ctx);
224
225 ftrace_test_recursion_unlock(bit);
226}
227
228#ifdef CONFIG_UNWINDER_ORC
229/*
230 * Skip 2:
231 *
232 * function_stack_trace_call()
233 * ftrace_call()
234 */
235#define STACK_SKIP 2
236#else
237/*
238 * Skip 3:
239 * __trace_stack()
240 * function_stack_trace_call()
241 * ftrace_call()
242 */
243#define STACK_SKIP 3
244#endif
245
246static void
247function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
248 struct ftrace_ops *op, struct ftrace_regs *fregs)
249{
250 struct trace_array *tr = op->private;
251 struct trace_array_cpu *data;
252 unsigned long flags;
253 long disabled;
254 int cpu;
255 unsigned int trace_ctx;
256 int skip = STACK_SKIP;
257
258 if (unlikely(!tr->function_enabled))
259 return;
260
261 /*
262 * Need to use raw, since this must be called before the
263 * recursive protection is performed.
264 */
265 local_irq_save(flags);
266 parent_ip = function_get_true_parent_ip(parent_ip, fregs);
267 cpu = raw_smp_processor_id();
268 data = per_cpu_ptr(tr->array_buffer.data, cpu);
269 disabled = atomic_inc_return(&data->disabled);
270
271 if (likely(disabled == 1)) {
272 trace_ctx = tracing_gen_ctx_flags(flags);
273 trace_function(tr, ip, parent_ip, trace_ctx);
274#ifdef CONFIG_UNWINDER_FRAME_POINTER
275 if (ftrace_pids_enabled(op))
276 skip++;
277#endif
278 __trace_stack(tr, trace_ctx, skip);
279 }
280
281 atomic_dec(&data->disabled);
282 local_irq_restore(flags);
283}
284
285static inline bool is_repeat_check(struct trace_array *tr,
286 struct trace_func_repeats *last_info,
287 unsigned long ip, unsigned long parent_ip)
288{
289 if (last_info->ip == ip &&
290 last_info->parent_ip == parent_ip &&
291 last_info->count < U16_MAX) {
292 last_info->ts_last_call =
293 ring_buffer_time_stamp(tr->array_buffer.buffer);
294 last_info->count++;
295 return true;
296 }
297
298 return false;
299}
300
301static inline void process_repeats(struct trace_array *tr,
302 unsigned long ip, unsigned long parent_ip,
303 struct trace_func_repeats *last_info,
304 unsigned int trace_ctx)
305{
306 if (last_info->count) {
307 trace_last_func_repeats(tr, last_info, trace_ctx);
308 last_info->count = 0;
309 }
310
311 last_info->ip = ip;
312 last_info->parent_ip = parent_ip;
313}
314
315static void
316function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
317 struct ftrace_ops *op,
318 struct ftrace_regs *fregs)
319{
320 struct trace_func_repeats *last_info;
321 struct trace_array *tr = op->private;
322 struct trace_array_cpu *data;
323 unsigned int trace_ctx;
324 int bit;
325
326 if (unlikely(!tr->function_enabled))
327 return;
328
329 bit = ftrace_test_recursion_trylock(ip, parent_ip);
330 if (bit < 0)
331 return;
332
333 parent_ip = function_get_true_parent_ip(parent_ip, fregs);
334 data = this_cpu_ptr(tr->array_buffer.data);
335 if (atomic_read(&data->disabled))
336 goto out;
337
338 /*
339 * An interrupt may happen at any place here. But as far as I can see,
340 * the only damage that this can cause is to mess up the repetition
341 * counter without valuable data being lost.
342 * TODO: think about a solution that is better than just hoping to be
343 * lucky.
344 */
345 last_info = this_cpu_ptr(tr->last_func_repeats);
346 if (is_repeat_check(tr, last_info, ip, parent_ip))
347 goto out;
348
349 trace_ctx = tracing_gen_ctx_dec();
350 process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
351
352 trace_function(tr, ip, parent_ip, trace_ctx);
353
354out:
355 ftrace_test_recursion_unlock(bit);
356}
357
358static void
359function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
360 struct ftrace_ops *op,
361 struct ftrace_regs *fregs)
362{
363 struct trace_func_repeats *last_info;
364 struct trace_array *tr = op->private;
365 struct trace_array_cpu *data;
366 unsigned long flags;
367 long disabled;
368 int cpu;
369 unsigned int trace_ctx;
370
371 if (unlikely(!tr->function_enabled))
372 return;
373
374 /*
375 * Need to use raw, since this must be called before the
376 * recursive protection is performed.
377 */
378 local_irq_save(flags);
379 parent_ip = function_get_true_parent_ip(parent_ip, fregs);
380 cpu = raw_smp_processor_id();
381 data = per_cpu_ptr(tr->array_buffer.data, cpu);
382 disabled = atomic_inc_return(&data->disabled);
383
384 if (likely(disabled == 1)) {
385 last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
386 if (is_repeat_check(tr, last_info, ip, parent_ip))
387 goto out;
388
389 trace_ctx = tracing_gen_ctx_flags(flags);
390 process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
391
392 trace_function(tr, ip, parent_ip, trace_ctx);
393 __trace_stack(tr, trace_ctx, STACK_SKIP);
394 }
395
396 out:
397 atomic_dec(&data->disabled);
398 local_irq_restore(flags);
399}
400
401static struct tracer_opt func_opts[] = {
402#ifdef CONFIG_STACKTRACE
403 { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
404#endif
405 { TRACER_OPT(func-no-repeats, TRACE_FUNC_OPT_NO_REPEATS) },
406 { } /* Always set a last empty entry */
407};
408
409static struct tracer_flags func_flags = {
410 .val = TRACE_FUNC_NO_OPTS, /* By default: all flags disabled */
411 .opts = func_opts
412};
413
414static void tracing_start_function_trace(struct trace_array *tr)
415{
416 tr->function_enabled = 0;
417 register_ftrace_function(tr->ops);
418 tr->function_enabled = 1;
419}
420
421static void tracing_stop_function_trace(struct trace_array *tr)
422{
423 tr->function_enabled = 0;
424 unregister_ftrace_function(tr->ops);
425}
426
427static struct tracer function_trace;
428
429static int
430func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
431{
432 ftrace_func_t func;
433 u32 new_flags;
434
435 /* Do nothing if already set. */
436 if (!!set == !!(func_flags.val & bit))
437 return 0;
438
439 /* We can change this flag only when not running. */
440 if (tr->current_trace != &function_trace)
441 return 0;
442
443 new_flags = (func_flags.val & ~bit) | (set ? bit : 0);
444 func = select_trace_function(new_flags);
445 if (!func)
446 return -EINVAL;
447
448 /* Check if there's anything to change. */
449 if (tr->ops->func == func)
450 return 0;
451
452 if (!handle_func_repeats(tr, new_flags))
453 return -ENOMEM;
454
455 unregister_ftrace_function(tr->ops);
456 tr->ops->func = func;
457 register_ftrace_function(tr->ops);
458
459 return 0;
460}
461
462static struct tracer function_trace __tracer_data =
463{
464 .name = "function",
465 .init = function_trace_init,
466 .reset = function_trace_reset,
467 .start = function_trace_start,
468 .flags = &func_flags,
469 .set_flag = func_set_flag,
470 .allow_instances = true,
471#ifdef CONFIG_FTRACE_SELFTEST
472 .selftest = trace_selftest_startup_function,
473#endif
474};
475
476#ifdef CONFIG_DYNAMIC_FTRACE
477static void update_traceon_count(struct ftrace_probe_ops *ops,
478 unsigned long ip,
479 struct trace_array *tr, bool on,
480 void *data)
481{
482 struct ftrace_func_mapper *mapper = data;
483 long *count;
484 long old_count;
485
486 /*
487 * Tracing gets disabled (or enabled) once per count.
488 * This function can be called at the same time on multiple CPUs.
489 * It is fine if both disable (or enable) tracing, as disabling
490 * (or enabling) the second time doesn't do anything as the
491 * state of the tracer is already disabled (or enabled).
492 * What needs to be synchronized in this case is that the count
493 * only gets decremented once, even if the tracer is disabled
494 * (or enabled) twice, as the second one is really a nop.
495 *
496 * The memory barriers guarantee that we only decrement the
497 * counter once. First the count is read to a local variable
498 * and a read barrier is used to make sure that it is loaded
499 * before checking if the tracer is in the state we want.
500 * If the tracer is not in the state we want, then the count
501 * is guaranteed to be the old count.
502 *
503 * Next the tracer is set to the state we want (disabled or enabled)
504 * then a write memory barrier is used to make sure that
505 * the new state is visible before changing the counter by
506 * one minus the old counter. This guarantees that another CPU
507 * executing this code will see the new state before seeing
508 * the new counter value, and would not do anything if the new
509 * counter is seen.
510 *
511 * Note, there is no synchronization between this and a user
512 * setting the tracing_on file. But we currently don't care
513 * about that.
514 */
515 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
516 old_count = *count;
517
518 if (old_count <= 0)
519 return;
520
521 /* Make sure we see count before checking tracing state */
522 smp_rmb();
523
524 if (on == !!tracer_tracing_is_on(tr))
525 return;
526
527 if (on)
528 tracer_tracing_on(tr);
529 else
530 tracer_tracing_off(tr);
531
532 /* Make sure tracing state is visible before updating count */
533 smp_wmb();
534
535 *count = old_count - 1;
536}
537
538static void
539ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
540 struct trace_array *tr, struct ftrace_probe_ops *ops,
541 void *data)
542{
543 update_traceon_count(ops, ip, tr, 1, data);
544}
545
546static void
547ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
548 struct trace_array *tr, struct ftrace_probe_ops *ops,
549 void *data)
550{
551 update_traceon_count(ops, ip, tr, 0, data);
552}
553
554static void
555ftrace_traceon(unsigned long ip, unsigned long parent_ip,
556 struct trace_array *tr, struct ftrace_probe_ops *ops,
557 void *data)
558{
559 if (tracer_tracing_is_on(tr))
560 return;
561
562 tracer_tracing_on(tr);
563}
564
565static void
566ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
567 struct trace_array *tr, struct ftrace_probe_ops *ops,
568 void *data)
569{
570 if (!tracer_tracing_is_on(tr))
571 return;
572
573 tracer_tracing_off(tr);
574}
575
576#ifdef CONFIG_UNWINDER_ORC
577/*
578 * Skip 3:
579 *
580 * function_trace_probe_call()
581 * ftrace_ops_assist_func()
582 * ftrace_call()
583 */
584#define FTRACE_STACK_SKIP 3
585#else
586/*
587 * Skip 5:
588 *
589 * __trace_stack()
590 * ftrace_stacktrace()
591 * function_trace_probe_call()
592 * ftrace_ops_assist_func()
593 * ftrace_call()
594 */
595#define FTRACE_STACK_SKIP 5
596#endif
597
598static __always_inline void trace_stack(struct trace_array *tr)
599{
600 unsigned int trace_ctx;
601
602 trace_ctx = tracing_gen_ctx();
603
604 __trace_stack(tr, trace_ctx, FTRACE_STACK_SKIP);
605}
606
607static void
608ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
609 struct trace_array *tr, struct ftrace_probe_ops *ops,
610 void *data)
611{
612 trace_stack(tr);
613}
614
615static void
616ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
617 struct trace_array *tr, struct ftrace_probe_ops *ops,
618 void *data)
619{
620 struct ftrace_func_mapper *mapper = data;
621 long *count;
622 long old_count;
623 long new_count;
624
625 if (!tracing_is_on())
626 return;
627
628 /* unlimited? */
629 if (!mapper) {
630 trace_stack(tr);
631 return;
632 }
633
634 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
635
636 /*
637 * Stack traces should only execute the number of times the
638 * user specified in the counter.
639 */
640 do {
641 old_count = *count;
642
643 if (!old_count)
644 return;
645
646 new_count = old_count - 1;
647 new_count = cmpxchg(count, old_count, new_count);
648 if (new_count == old_count)
649 trace_stack(tr);
650
651 if (!tracing_is_on())
652 return;
653
654 } while (new_count != old_count);
655}
656
657static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
658 void *data)
659{
660 struct ftrace_func_mapper *mapper = data;
661 long *count = NULL;
662
663 if (mapper)
664 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
665
666 if (count) {
667 if (*count <= 0)
668 return 0;
669 (*count)--;
670 }
671
672 return 1;
673}
674
675static void
676ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
677 struct trace_array *tr, struct ftrace_probe_ops *ops,
678 void *data)
679{
680 if (update_count(ops, ip, data))
681 ftrace_dump(DUMP_ALL);
682}
683
684/* Only dump the current CPU buffer. */
685static void
686ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
687 struct trace_array *tr, struct ftrace_probe_ops *ops,
688 void *data)
689{
690 if (update_count(ops, ip, data))
691 ftrace_dump(DUMP_ORIG);
692}
693
694static int
695ftrace_probe_print(const char *name, struct seq_file *m,
696 unsigned long ip, struct ftrace_probe_ops *ops,
697 void *data)
698{
699 struct ftrace_func_mapper *mapper = data;
700 long *count = NULL;
701
702 seq_printf(m, "%ps:%s", (void *)ip, name);
703
704 if (mapper)
705 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
706
707 if (count)
708 seq_printf(m, ":count=%ld\n", *count);
709 else
710 seq_puts(m, ":unlimited\n");
711
712 return 0;
713}
714
715static int
716ftrace_traceon_print(struct seq_file *m, unsigned long ip,
717 struct ftrace_probe_ops *ops,
718 void *data)
719{
720 return ftrace_probe_print("traceon", m, ip, ops, data);
721}
722
723static int
724ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
725 struct ftrace_probe_ops *ops, void *data)
726{
727 return ftrace_probe_print("traceoff", m, ip, ops, data);
728}
729
730static int
731ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
732 struct ftrace_probe_ops *ops, void *data)
733{
734 return ftrace_probe_print("stacktrace", m, ip, ops, data);
735}
736
737static int
738ftrace_dump_print(struct seq_file *m, unsigned long ip,
739 struct ftrace_probe_ops *ops, void *data)
740{
741 return ftrace_probe_print("dump", m, ip, ops, data);
742}
743
744static int
745ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
746 struct ftrace_probe_ops *ops, void *data)
747{
748 return ftrace_probe_print("cpudump", m, ip, ops, data);
749}
750
751
752static int
753ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
754 unsigned long ip, void *init_data, void **data)
755{
756 struct ftrace_func_mapper *mapper = *data;
757
758 if (!mapper) {
759 mapper = allocate_ftrace_func_mapper();
760 if (!mapper)
761 return -ENOMEM;
762 *data = mapper;
763 }
764
765 return ftrace_func_mapper_add_ip(mapper, ip, init_data);
766}
767
768static void
769ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
770 unsigned long ip, void *data)
771{
772 struct ftrace_func_mapper *mapper = data;
773
774 if (!ip) {
775 free_ftrace_func_mapper(mapper, NULL);
776 return;
777 }
778
779 ftrace_func_mapper_remove_ip(mapper, ip);
780}
781
782static struct ftrace_probe_ops traceon_count_probe_ops = {
783 .func = ftrace_traceon_count,
784 .print = ftrace_traceon_print,
785 .init = ftrace_count_init,
786 .free = ftrace_count_free,
787};
788
789static struct ftrace_probe_ops traceoff_count_probe_ops = {
790 .func = ftrace_traceoff_count,
791 .print = ftrace_traceoff_print,
792 .init = ftrace_count_init,
793 .free = ftrace_count_free,
794};
795
796static struct ftrace_probe_ops stacktrace_count_probe_ops = {
797 .func = ftrace_stacktrace_count,
798 .print = ftrace_stacktrace_print,
799 .init = ftrace_count_init,
800 .free = ftrace_count_free,
801};
802
803static struct ftrace_probe_ops dump_probe_ops = {
804 .func = ftrace_dump_probe,
805 .print = ftrace_dump_print,
806 .init = ftrace_count_init,
807 .free = ftrace_count_free,
808};
809
810static struct ftrace_probe_ops cpudump_probe_ops = {
811 .func = ftrace_cpudump_probe,
812 .print = ftrace_cpudump_print,
813};
814
815static struct ftrace_probe_ops traceon_probe_ops = {
816 .func = ftrace_traceon,
817 .print = ftrace_traceon_print,
818};
819
820static struct ftrace_probe_ops traceoff_probe_ops = {
821 .func = ftrace_traceoff,
822 .print = ftrace_traceoff_print,
823};
824
825static struct ftrace_probe_ops stacktrace_probe_ops = {
826 .func = ftrace_stacktrace,
827 .print = ftrace_stacktrace_print,
828};
829
830static int
831ftrace_trace_probe_callback(struct trace_array *tr,
832 struct ftrace_probe_ops *ops,
833 struct ftrace_hash *hash, char *glob,
834 char *cmd, char *param, int enable)
835{
836 void *count = (void *)-1;
837 char *number;
838 int ret;
839
840 /* hash funcs only work with set_ftrace_filter */
841 if (!enable)
842 return -EINVAL;
843
844 if (glob[0] == '!')
845 return unregister_ftrace_function_probe_func(glob+1, tr, ops);
846
847 if (!param)
848 goto out_reg;
849
850 number = strsep(¶m, ":");
851
852 if (!strlen(number))
853 goto out_reg;
854
855 /*
856 * We use the callback data field (which is a pointer)
857 * as our counter.
858 */
859 ret = kstrtoul(number, 0, (unsigned long *)&count);
860 if (ret)
861 return ret;
862
863 out_reg:
864 ret = register_ftrace_function_probe(glob, tr, ops, count);
865
866 return ret < 0 ? ret : 0;
867}
868
869static int
870ftrace_trace_onoff_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 /* we register both traceon and traceoff to this callback */
879 if (strcmp(cmd, "traceon") == 0)
880 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
881 else
882 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
883
884 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
885 param, enable);
886}
887
888static int
889ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
890 char *glob, char *cmd, char *param, int enable)
891{
892 struct ftrace_probe_ops *ops;
893
894 if (!tr)
895 return -ENODEV;
896
897 ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
898
899 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
900 param, enable);
901}
902
903static int
904ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
905 char *glob, char *cmd, char *param, int enable)
906{
907 struct ftrace_probe_ops *ops;
908
909 if (!tr)
910 return -ENODEV;
911
912 ops = &dump_probe_ops;
913
914 /* Only dump once. */
915 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
916 "1", enable);
917}
918
919static int
920ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
921 char *glob, char *cmd, char *param, int enable)
922{
923 struct ftrace_probe_ops *ops;
924
925 if (!tr)
926 return -ENODEV;
927
928 ops = &cpudump_probe_ops;
929
930 /* Only dump once. */
931 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
932 "1", enable);
933}
934
935static struct ftrace_func_command ftrace_traceon_cmd = {
936 .name = "traceon",
937 .func = ftrace_trace_onoff_callback,
938};
939
940static struct ftrace_func_command ftrace_traceoff_cmd = {
941 .name = "traceoff",
942 .func = ftrace_trace_onoff_callback,
943};
944
945static struct ftrace_func_command ftrace_stacktrace_cmd = {
946 .name = "stacktrace",
947 .func = ftrace_stacktrace_callback,
948};
949
950static struct ftrace_func_command ftrace_dump_cmd = {
951 .name = "dump",
952 .func = ftrace_dump_callback,
953};
954
955static struct ftrace_func_command ftrace_cpudump_cmd = {
956 .name = "cpudump",
957 .func = ftrace_cpudump_callback,
958};
959
960static int __init init_func_cmd_traceon(void)
961{
962 int ret;
963
964 ret = register_ftrace_command(&ftrace_traceoff_cmd);
965 if (ret)
966 return ret;
967
968 ret = register_ftrace_command(&ftrace_traceon_cmd);
969 if (ret)
970 goto out_free_traceoff;
971
972 ret = register_ftrace_command(&ftrace_stacktrace_cmd);
973 if (ret)
974 goto out_free_traceon;
975
976 ret = register_ftrace_command(&ftrace_dump_cmd);
977 if (ret)
978 goto out_free_stacktrace;
979
980 ret = register_ftrace_command(&ftrace_cpudump_cmd);
981 if (ret)
982 goto out_free_dump;
983
984 return 0;
985
986 out_free_dump:
987 unregister_ftrace_command(&ftrace_dump_cmd);
988 out_free_stacktrace:
989 unregister_ftrace_command(&ftrace_stacktrace_cmd);
990 out_free_traceon:
991 unregister_ftrace_command(&ftrace_traceon_cmd);
992 out_free_traceoff:
993 unregister_ftrace_command(&ftrace_traceoff_cmd);
994
995 return ret;
996}
997#else
998static inline int init_func_cmd_traceon(void)
999{
1000 return 0;
1001}
1002#endif /* CONFIG_DYNAMIC_FTRACE */
1003
1004__init int init_function_trace(void)
1005{
1006 init_func_cmd_traceon();
1007 return register_tracer(&function_trace);
1008}
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 preempt_disable_notrace();
190
191 cpu = smp_processor_id();
192 data = per_cpu_ptr(tr->array_buffer.data, cpu);
193 if (!atomic_read(&data->disabled))
194 trace_function(tr, ip, parent_ip, trace_ctx);
195
196 ftrace_test_recursion_unlock(bit);
197 preempt_enable_notrace();
198}
199
200#ifdef CONFIG_UNWINDER_ORC
201/*
202 * Skip 2:
203 *
204 * function_stack_trace_call()
205 * ftrace_call()
206 */
207#define STACK_SKIP 2
208#else
209/*
210 * Skip 3:
211 * __trace_stack()
212 * function_stack_trace_call()
213 * ftrace_call()
214 */
215#define STACK_SKIP 3
216#endif
217
218static void
219function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
220 struct ftrace_ops *op, struct ftrace_regs *fregs)
221{
222 struct trace_array *tr = op->private;
223 struct trace_array_cpu *data;
224 unsigned long flags;
225 long disabled;
226 int cpu;
227 unsigned int trace_ctx;
228
229 if (unlikely(!tr->function_enabled))
230 return;
231
232 /*
233 * Need to use raw, since this must be called before the
234 * recursive protection is performed.
235 */
236 local_irq_save(flags);
237 cpu = raw_smp_processor_id();
238 data = per_cpu_ptr(tr->array_buffer.data, cpu);
239 disabled = atomic_inc_return(&data->disabled);
240
241 if (likely(disabled == 1)) {
242 trace_ctx = tracing_gen_ctx_flags(flags);
243 trace_function(tr, ip, parent_ip, trace_ctx);
244 __trace_stack(tr, trace_ctx, STACK_SKIP);
245 }
246
247 atomic_dec(&data->disabled);
248 local_irq_restore(flags);
249}
250
251static inline bool is_repeat_check(struct trace_array *tr,
252 struct trace_func_repeats *last_info,
253 unsigned long ip, unsigned long parent_ip)
254{
255 if (last_info->ip == ip &&
256 last_info->parent_ip == parent_ip &&
257 last_info->count < U16_MAX) {
258 last_info->ts_last_call =
259 ring_buffer_time_stamp(tr->array_buffer.buffer);
260 last_info->count++;
261 return true;
262 }
263
264 return false;
265}
266
267static inline void process_repeats(struct trace_array *tr,
268 unsigned long ip, unsigned long parent_ip,
269 struct trace_func_repeats *last_info,
270 unsigned int trace_ctx)
271{
272 if (last_info->count) {
273 trace_last_func_repeats(tr, last_info, trace_ctx);
274 last_info->count = 0;
275 }
276
277 last_info->ip = ip;
278 last_info->parent_ip = parent_ip;
279}
280
281static void
282function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
283 struct ftrace_ops *op,
284 struct ftrace_regs *fregs)
285{
286 struct trace_func_repeats *last_info;
287 struct trace_array *tr = op->private;
288 struct trace_array_cpu *data;
289 unsigned int trace_ctx;
290 unsigned long flags;
291 int bit;
292 int cpu;
293
294 if (unlikely(!tr->function_enabled))
295 return;
296
297 bit = ftrace_test_recursion_trylock(ip, parent_ip);
298 if (bit < 0)
299 return;
300
301 preempt_disable_notrace();
302
303 cpu = smp_processor_id();
304 data = per_cpu_ptr(tr->array_buffer.data, cpu);
305 if (atomic_read(&data->disabled))
306 goto out;
307
308 /*
309 * An interrupt may happen at any place here. But as far as I can see,
310 * the only damage that this can cause is to mess up the repetition
311 * counter without valuable data being lost.
312 * TODO: think about a solution that is better than just hoping to be
313 * lucky.
314 */
315 last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
316 if (is_repeat_check(tr, last_info, ip, parent_ip))
317 goto out;
318
319 local_save_flags(flags);
320 trace_ctx = tracing_gen_ctx_flags(flags);
321 process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
322
323 trace_function(tr, ip, parent_ip, trace_ctx);
324
325out:
326 ftrace_test_recursion_unlock(bit);
327 preempt_enable_notrace();
328}
329
330static void
331function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
332 struct ftrace_ops *op,
333 struct ftrace_regs *fregs)
334{
335 struct trace_func_repeats *last_info;
336 struct trace_array *tr = op->private;
337 struct trace_array_cpu *data;
338 unsigned long flags;
339 long disabled;
340 int cpu;
341 unsigned int trace_ctx;
342
343 if (unlikely(!tr->function_enabled))
344 return;
345
346 /*
347 * Need to use raw, since this must be called before the
348 * recursive protection is performed.
349 */
350 local_irq_save(flags);
351 cpu = raw_smp_processor_id();
352 data = per_cpu_ptr(tr->array_buffer.data, cpu);
353 disabled = atomic_inc_return(&data->disabled);
354
355 if (likely(disabled == 1)) {
356 last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
357 if (is_repeat_check(tr, last_info, ip, parent_ip))
358 goto out;
359
360 trace_ctx = tracing_gen_ctx_flags(flags);
361 process_repeats(tr, ip, parent_ip, last_info, trace_ctx);
362
363 trace_function(tr, ip, parent_ip, trace_ctx);
364 __trace_stack(tr, trace_ctx, STACK_SKIP);
365 }
366
367 out:
368 atomic_dec(&data->disabled);
369 local_irq_restore(flags);
370}
371
372static struct tracer_opt func_opts[] = {
373#ifdef CONFIG_STACKTRACE
374 { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
375#endif
376 { TRACER_OPT(func-no-repeats, TRACE_FUNC_OPT_NO_REPEATS) },
377 { } /* Always set a last empty entry */
378};
379
380static struct tracer_flags func_flags = {
381 .val = TRACE_FUNC_NO_OPTS, /* By default: all flags disabled */
382 .opts = func_opts
383};
384
385static void tracing_start_function_trace(struct trace_array *tr)
386{
387 tr->function_enabled = 0;
388 register_ftrace_function(tr->ops);
389 tr->function_enabled = 1;
390}
391
392static void tracing_stop_function_trace(struct trace_array *tr)
393{
394 tr->function_enabled = 0;
395 unregister_ftrace_function(tr->ops);
396}
397
398static struct tracer function_trace;
399
400static int
401func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
402{
403 ftrace_func_t func;
404 u32 new_flags;
405
406 /* Do nothing if already set. */
407 if (!!set == !!(func_flags.val & bit))
408 return 0;
409
410 /* We can change this flag only when not running. */
411 if (tr->current_trace != &function_trace)
412 return 0;
413
414 new_flags = (func_flags.val & ~bit) | (set ? bit : 0);
415 func = select_trace_function(new_flags);
416 if (!func)
417 return -EINVAL;
418
419 /* Check if there's anything to change. */
420 if (tr->ops->func == func)
421 return 0;
422
423 if (!handle_func_repeats(tr, new_flags))
424 return -ENOMEM;
425
426 unregister_ftrace_function(tr->ops);
427 tr->ops->func = func;
428 register_ftrace_function(tr->ops);
429
430 return 0;
431}
432
433static struct tracer function_trace __tracer_data =
434{
435 .name = "function",
436 .init = function_trace_init,
437 .reset = function_trace_reset,
438 .start = function_trace_start,
439 .flags = &func_flags,
440 .set_flag = func_set_flag,
441 .allow_instances = true,
442#ifdef CONFIG_FTRACE_SELFTEST
443 .selftest = trace_selftest_startup_function,
444#endif
445};
446
447#ifdef CONFIG_DYNAMIC_FTRACE
448static void update_traceon_count(struct ftrace_probe_ops *ops,
449 unsigned long ip,
450 struct trace_array *tr, bool on,
451 void *data)
452{
453 struct ftrace_func_mapper *mapper = data;
454 long *count;
455 long old_count;
456
457 /*
458 * Tracing gets disabled (or enabled) once per count.
459 * This function can be called at the same time on multiple CPUs.
460 * It is fine if both disable (or enable) tracing, as disabling
461 * (or enabling) the second time doesn't do anything as the
462 * state of the tracer is already disabled (or enabled).
463 * What needs to be synchronized in this case is that the count
464 * only gets decremented once, even if the tracer is disabled
465 * (or enabled) twice, as the second one is really a nop.
466 *
467 * The memory barriers guarantee that we only decrement the
468 * counter once. First the count is read to a local variable
469 * and a read barrier is used to make sure that it is loaded
470 * before checking if the tracer is in the state we want.
471 * If the tracer is not in the state we want, then the count
472 * is guaranteed to be the old count.
473 *
474 * Next the tracer is set to the state we want (disabled or enabled)
475 * then a write memory barrier is used to make sure that
476 * the new state is visible before changing the counter by
477 * one minus the old counter. This guarantees that another CPU
478 * executing this code will see the new state before seeing
479 * the new counter value, and would not do anything if the new
480 * counter is seen.
481 *
482 * Note, there is no synchronization between this and a user
483 * setting the tracing_on file. But we currently don't care
484 * about that.
485 */
486 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
487 old_count = *count;
488
489 if (old_count <= 0)
490 return;
491
492 /* Make sure we see count before checking tracing state */
493 smp_rmb();
494
495 if (on == !!tracer_tracing_is_on(tr))
496 return;
497
498 if (on)
499 tracer_tracing_on(tr);
500 else
501 tracer_tracing_off(tr);
502
503 /* Make sure tracing state is visible before updating count */
504 smp_wmb();
505
506 *count = old_count - 1;
507}
508
509static void
510ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
511 struct trace_array *tr, struct ftrace_probe_ops *ops,
512 void *data)
513{
514 update_traceon_count(ops, ip, tr, 1, data);
515}
516
517static void
518ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
519 struct trace_array *tr, struct ftrace_probe_ops *ops,
520 void *data)
521{
522 update_traceon_count(ops, ip, tr, 0, data);
523}
524
525static void
526ftrace_traceon(unsigned long ip, unsigned long parent_ip,
527 struct trace_array *tr, struct ftrace_probe_ops *ops,
528 void *data)
529{
530 if (tracer_tracing_is_on(tr))
531 return;
532
533 tracer_tracing_on(tr);
534}
535
536static void
537ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
538 struct trace_array *tr, struct ftrace_probe_ops *ops,
539 void *data)
540{
541 if (!tracer_tracing_is_on(tr))
542 return;
543
544 tracer_tracing_off(tr);
545}
546
547#ifdef CONFIG_UNWINDER_ORC
548/*
549 * Skip 3:
550 *
551 * function_trace_probe_call()
552 * ftrace_ops_assist_func()
553 * ftrace_call()
554 */
555#define FTRACE_STACK_SKIP 3
556#else
557/*
558 * Skip 5:
559 *
560 * __trace_stack()
561 * ftrace_stacktrace()
562 * function_trace_probe_call()
563 * ftrace_ops_assist_func()
564 * ftrace_call()
565 */
566#define FTRACE_STACK_SKIP 5
567#endif
568
569static __always_inline void trace_stack(struct trace_array *tr)
570{
571 unsigned int trace_ctx;
572
573 trace_ctx = tracing_gen_ctx();
574
575 __trace_stack(tr, trace_ctx, FTRACE_STACK_SKIP);
576}
577
578static void
579ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
580 struct trace_array *tr, struct ftrace_probe_ops *ops,
581 void *data)
582{
583 trace_stack(tr);
584}
585
586static void
587ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
588 struct trace_array *tr, struct ftrace_probe_ops *ops,
589 void *data)
590{
591 struct ftrace_func_mapper *mapper = data;
592 long *count;
593 long old_count;
594 long new_count;
595
596 if (!tracing_is_on())
597 return;
598
599 /* unlimited? */
600 if (!mapper) {
601 trace_stack(tr);
602 return;
603 }
604
605 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
606
607 /*
608 * Stack traces should only execute the number of times the
609 * user specified in the counter.
610 */
611 do {
612 old_count = *count;
613
614 if (!old_count)
615 return;
616
617 new_count = old_count - 1;
618 new_count = cmpxchg(count, old_count, new_count);
619 if (new_count == old_count)
620 trace_stack(tr);
621
622 if (!tracing_is_on())
623 return;
624
625 } while (new_count != old_count);
626}
627
628static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
629 void *data)
630{
631 struct ftrace_func_mapper *mapper = data;
632 long *count = NULL;
633
634 if (mapper)
635 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
636
637 if (count) {
638 if (*count <= 0)
639 return 0;
640 (*count)--;
641 }
642
643 return 1;
644}
645
646static void
647ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
648 struct trace_array *tr, struct ftrace_probe_ops *ops,
649 void *data)
650{
651 if (update_count(ops, ip, data))
652 ftrace_dump(DUMP_ALL);
653}
654
655/* Only dump the current CPU buffer. */
656static void
657ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
658 struct trace_array *tr, struct ftrace_probe_ops *ops,
659 void *data)
660{
661 if (update_count(ops, ip, data))
662 ftrace_dump(DUMP_ORIG);
663}
664
665static int
666ftrace_probe_print(const char *name, struct seq_file *m,
667 unsigned long ip, struct ftrace_probe_ops *ops,
668 void *data)
669{
670 struct ftrace_func_mapper *mapper = data;
671 long *count = NULL;
672
673 seq_printf(m, "%ps:%s", (void *)ip, name);
674
675 if (mapper)
676 count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
677
678 if (count)
679 seq_printf(m, ":count=%ld\n", *count);
680 else
681 seq_puts(m, ":unlimited\n");
682
683 return 0;
684}
685
686static int
687ftrace_traceon_print(struct seq_file *m, unsigned long ip,
688 struct ftrace_probe_ops *ops,
689 void *data)
690{
691 return ftrace_probe_print("traceon", m, ip, ops, data);
692}
693
694static int
695ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
696 struct ftrace_probe_ops *ops, void *data)
697{
698 return ftrace_probe_print("traceoff", m, ip, ops, data);
699}
700
701static int
702ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
703 struct ftrace_probe_ops *ops, void *data)
704{
705 return ftrace_probe_print("stacktrace", m, ip, ops, data);
706}
707
708static int
709ftrace_dump_print(struct seq_file *m, unsigned long ip,
710 struct ftrace_probe_ops *ops, void *data)
711{
712 return ftrace_probe_print("dump", m, ip, ops, data);
713}
714
715static int
716ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
717 struct ftrace_probe_ops *ops, void *data)
718{
719 return ftrace_probe_print("cpudump", m, ip, ops, data);
720}
721
722
723static int
724ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
725 unsigned long ip, void *init_data, void **data)
726{
727 struct ftrace_func_mapper *mapper = *data;
728
729 if (!mapper) {
730 mapper = allocate_ftrace_func_mapper();
731 if (!mapper)
732 return -ENOMEM;
733 *data = mapper;
734 }
735
736 return ftrace_func_mapper_add_ip(mapper, ip, init_data);
737}
738
739static void
740ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
741 unsigned long ip, void *data)
742{
743 struct ftrace_func_mapper *mapper = data;
744
745 if (!ip) {
746 free_ftrace_func_mapper(mapper, NULL);
747 return;
748 }
749
750 ftrace_func_mapper_remove_ip(mapper, ip);
751}
752
753static struct ftrace_probe_ops traceon_count_probe_ops = {
754 .func = ftrace_traceon_count,
755 .print = ftrace_traceon_print,
756 .init = ftrace_count_init,
757 .free = ftrace_count_free,
758};
759
760static struct ftrace_probe_ops traceoff_count_probe_ops = {
761 .func = ftrace_traceoff_count,
762 .print = ftrace_traceoff_print,
763 .init = ftrace_count_init,
764 .free = ftrace_count_free,
765};
766
767static struct ftrace_probe_ops stacktrace_count_probe_ops = {
768 .func = ftrace_stacktrace_count,
769 .print = ftrace_stacktrace_print,
770 .init = ftrace_count_init,
771 .free = ftrace_count_free,
772};
773
774static struct ftrace_probe_ops dump_probe_ops = {
775 .func = ftrace_dump_probe,
776 .print = ftrace_dump_print,
777 .init = ftrace_count_init,
778 .free = ftrace_count_free,
779};
780
781static struct ftrace_probe_ops cpudump_probe_ops = {
782 .func = ftrace_cpudump_probe,
783 .print = ftrace_cpudump_print,
784};
785
786static struct ftrace_probe_ops traceon_probe_ops = {
787 .func = ftrace_traceon,
788 .print = ftrace_traceon_print,
789};
790
791static struct ftrace_probe_ops traceoff_probe_ops = {
792 .func = ftrace_traceoff,
793 .print = ftrace_traceoff_print,
794};
795
796static struct ftrace_probe_ops stacktrace_probe_ops = {
797 .func = ftrace_stacktrace,
798 .print = ftrace_stacktrace_print,
799};
800
801static int
802ftrace_trace_probe_callback(struct trace_array *tr,
803 struct ftrace_probe_ops *ops,
804 struct ftrace_hash *hash, char *glob,
805 char *cmd, char *param, int enable)
806{
807 void *count = (void *)-1;
808 char *number;
809 int ret;
810
811 /* hash funcs only work with set_ftrace_filter */
812 if (!enable)
813 return -EINVAL;
814
815 if (glob[0] == '!')
816 return unregister_ftrace_function_probe_func(glob+1, tr, ops);
817
818 if (!param)
819 goto out_reg;
820
821 number = strsep(¶m, ":");
822
823 if (!strlen(number))
824 goto out_reg;
825
826 /*
827 * We use the callback data field (which is a pointer)
828 * as our counter.
829 */
830 ret = kstrtoul(number, 0, (unsigned long *)&count);
831 if (ret)
832 return ret;
833
834 out_reg:
835 ret = register_ftrace_function_probe(glob, tr, ops, count);
836
837 return ret < 0 ? ret : 0;
838}
839
840static int
841ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
842 char *glob, char *cmd, char *param, int enable)
843{
844 struct ftrace_probe_ops *ops;
845
846 if (!tr)
847 return -ENODEV;
848
849 /* we register both traceon and traceoff to this callback */
850 if (strcmp(cmd, "traceon") == 0)
851 ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
852 else
853 ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;
854
855 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
856 param, enable);
857}
858
859static int
860ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
861 char *glob, char *cmd, char *param, int enable)
862{
863 struct ftrace_probe_ops *ops;
864
865 if (!tr)
866 return -ENODEV;
867
868 ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;
869
870 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
871 param, enable);
872}
873
874static int
875ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
876 char *glob, char *cmd, char *param, int enable)
877{
878 struct ftrace_probe_ops *ops;
879
880 if (!tr)
881 return -ENODEV;
882
883 ops = &dump_probe_ops;
884
885 /* Only dump once. */
886 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
887 "1", enable);
888}
889
890static int
891ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
892 char *glob, char *cmd, char *param, int enable)
893{
894 struct ftrace_probe_ops *ops;
895
896 if (!tr)
897 return -ENODEV;
898
899 ops = &cpudump_probe_ops;
900
901 /* Only dump once. */
902 return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
903 "1", enable);
904}
905
906static struct ftrace_func_command ftrace_traceon_cmd = {
907 .name = "traceon",
908 .func = ftrace_trace_onoff_callback,
909};
910
911static struct ftrace_func_command ftrace_traceoff_cmd = {
912 .name = "traceoff",
913 .func = ftrace_trace_onoff_callback,
914};
915
916static struct ftrace_func_command ftrace_stacktrace_cmd = {
917 .name = "stacktrace",
918 .func = ftrace_stacktrace_callback,
919};
920
921static struct ftrace_func_command ftrace_dump_cmd = {
922 .name = "dump",
923 .func = ftrace_dump_callback,
924};
925
926static struct ftrace_func_command ftrace_cpudump_cmd = {
927 .name = "cpudump",
928 .func = ftrace_cpudump_callback,
929};
930
931static int __init init_func_cmd_traceon(void)
932{
933 int ret;
934
935 ret = register_ftrace_command(&ftrace_traceoff_cmd);
936 if (ret)
937 return ret;
938
939 ret = register_ftrace_command(&ftrace_traceon_cmd);
940 if (ret)
941 goto out_free_traceoff;
942
943 ret = register_ftrace_command(&ftrace_stacktrace_cmd);
944 if (ret)
945 goto out_free_traceon;
946
947 ret = register_ftrace_command(&ftrace_dump_cmd);
948 if (ret)
949 goto out_free_stacktrace;
950
951 ret = register_ftrace_command(&ftrace_cpudump_cmd);
952 if (ret)
953 goto out_free_dump;
954
955 return 0;
956
957 out_free_dump:
958 unregister_ftrace_command(&ftrace_dump_cmd);
959 out_free_stacktrace:
960 unregister_ftrace_command(&ftrace_stacktrace_cmd);
961 out_free_traceon:
962 unregister_ftrace_command(&ftrace_traceon_cmd);
963 out_free_traceoff:
964 unregister_ftrace_command(&ftrace_traceoff_cmd);
965
966 return ret;
967}
968#else
969static inline int init_func_cmd_traceon(void)
970{
971 return 0;
972}
973#endif /* CONFIG_DYNAMIC_FTRACE */
974
975__init int init_function_trace(void)
976{
977 init_func_cmd_traceon();
978 return register_tracer(&function_trace);
979}