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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2008-2014 Mathieu Desnoyers
4 */
5#include <linux/module.h>
6#include <linux/mutex.h>
7#include <linux/types.h>
8#include <linux/jhash.h>
9#include <linux/list.h>
10#include <linux/rcupdate.h>
11#include <linux/tracepoint.h>
12#include <linux/err.h>
13#include <linux/slab.h>
14#include <linux/sched/signal.h>
15#include <linux/sched/task.h>
16#include <linux/static_key.h>
17
18enum tp_func_state {
19 TP_FUNC_0,
20 TP_FUNC_1,
21 TP_FUNC_2,
22 TP_FUNC_N,
23};
24
25extern tracepoint_ptr_t __start___tracepoints_ptrs[];
26extern tracepoint_ptr_t __stop___tracepoints_ptrs[];
27
28enum tp_transition_sync {
29 TP_TRANSITION_SYNC_1_0_1,
30 TP_TRANSITION_SYNC_N_2_1,
31
32 _NR_TP_TRANSITION_SYNC,
33};
34
35struct tp_transition_snapshot {
36 unsigned long rcu;
37 unsigned long srcu_gp;
38 bool ongoing;
39};
40
41DEFINE_SRCU_FAST(tracepoint_srcu);
42EXPORT_SYMBOL_GPL(tracepoint_srcu);
43
44/* Protected by tracepoints_mutex */
45static struct tp_transition_snapshot tp_transition_snapshot[_NR_TP_TRANSITION_SYNC];
46
47static void tp_rcu_get_state(enum tp_transition_sync sync)
48{
49 struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
50
51 /* Keep the latest get_state snapshot. */
52 snapshot->rcu = get_state_synchronize_rcu();
53 snapshot->srcu_gp = start_poll_synchronize_srcu(&tracepoint_srcu);
54 snapshot->ongoing = true;
55}
56
57static void tp_rcu_cond_sync(enum tp_transition_sync sync)
58{
59 struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
60
61 if (!snapshot->ongoing)
62 return;
63 cond_synchronize_rcu(snapshot->rcu);
64 if (!poll_state_synchronize_srcu(&tracepoint_srcu, snapshot->srcu_gp))
65 synchronize_srcu(&tracepoint_srcu);
66 snapshot->ongoing = false;
67}
68
69/* Set to 1 to enable tracepoint debug output */
70static const int tracepoint_debug;
71
72#ifdef CONFIG_MODULES
73/*
74 * Tracepoint module list mutex protects the local module list.
75 */
76static DEFINE_MUTEX(tracepoint_module_list_mutex);
77
78/* Local list of struct tp_module */
79static LIST_HEAD(tracepoint_module_list);
80#endif /* CONFIG_MODULES */
81
82/*
83 * tracepoints_mutex protects the builtin and module tracepoints.
84 * tracepoints_mutex nests inside tracepoint_module_list_mutex.
85 */
86static DEFINE_MUTEX(tracepoints_mutex);
87
88/*
89 * Note about RCU :
90 * It is used to delay the free of multiple probes array until a quiescent
91 * state is reached.
92 */
93struct tp_probes {
94 struct rcu_head rcu;
95 struct tracepoint_func probes[];
96};
97
98/* Called in removal of a func but failed to allocate a new tp_funcs */
99static void tp_stub_func(void)
100{
101 return;
102}
103
104static inline void *allocate_probes(int count)
105{
106 struct tp_probes *p = kmalloc_flex(*p, probes, count);
107 return p == NULL ? NULL : p->probes;
108}
109
110static void rcu_free_old_probes(struct rcu_head *head)
111{
112 kfree(container_of(head, struct tp_probes, rcu));
113}
114
115static inline void release_probes(struct tracepoint *tp, struct tracepoint_func *old)
116{
117 if (old) {
118 struct tp_probes *tp_probes = container_of(old,
119 struct tp_probes, probes[0]);
120
121 if (tracepoint_is_faultable(tp)) {
122 call_rcu_tasks_trace(&tp_probes->rcu,
123 rcu_free_old_probes);
124 } else {
125 call_srcu(&tracepoint_srcu, &tp_probes->rcu,
126 rcu_free_old_probes);
127 }
128 }
129}
130
131static void debug_print_probes(struct tracepoint_func *funcs)
132{
133 int i;
134
135 if (!tracepoint_debug || !funcs)
136 return;
137
138 for (i = 0; funcs[i].func; i++)
139 printk(KERN_DEBUG "Probe %d : %pSb\n", i, funcs[i].func);
140}
141
142static struct tracepoint_func *
143func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
144 int prio)
145{
146 struct tracepoint_func *old, *new;
147 int iter_probes; /* Iterate over old probe array. */
148 int nr_probes = 0; /* Counter for probes */
149 int pos = -1; /* Insertion position into new array */
150
151 if (WARN_ON(!tp_func->func))
152 return ERR_PTR(-EINVAL);
153
154 debug_print_probes(*funcs);
155 old = *funcs;
156 if (old) {
157 /* (N -> N+1), (N != 0, 1) probes */
158 for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
159 if (old[iter_probes].func == tp_stub_func)
160 continue; /* Skip stub functions. */
161 if (old[iter_probes].func == tp_func->func &&
162 old[iter_probes].data == tp_func->data)
163 return ERR_PTR(-EEXIST);
164 nr_probes++;
165 }
166 }
167 /* + 2 : one for new probe, one for NULL func */
168 new = allocate_probes(nr_probes + 2);
169 if (new == NULL)
170 return ERR_PTR(-ENOMEM);
171 if (old) {
172 nr_probes = 0;
173 for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
174 if (old[iter_probes].func == tp_stub_func)
175 continue;
176 /* Insert before probes of lower priority */
177 if (pos < 0 && old[iter_probes].prio < prio)
178 pos = nr_probes++;
179 new[nr_probes++] = old[iter_probes];
180 }
181 if (pos < 0)
182 pos = nr_probes++;
183 /* nr_probes now points to the end of the new array */
184 } else {
185 pos = 0;
186 nr_probes = 1; /* must point at end of array */
187 }
188 new[pos] = *tp_func;
189 new[nr_probes].func = NULL;
190 *funcs = new;
191 debug_print_probes(*funcs);
192 return old;
193}
194
195static void *func_remove(struct tracepoint_func **funcs,
196 struct tracepoint_func *tp_func)
197{
198 int nr_probes = 0, nr_del = 0, i;
199 struct tracepoint_func *old, *new;
200
201 old = *funcs;
202
203 if (!old)
204 return ERR_PTR(-ENOENT);
205
206 debug_print_probes(*funcs);
207 /* (N -> M), (N > 1, M >= 0) probes */
208 if (tp_func->func) {
209 for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
210 if ((old[nr_probes].func == tp_func->func &&
211 old[nr_probes].data == tp_func->data) ||
212 old[nr_probes].func == tp_stub_func)
213 nr_del++;
214 }
215 }
216
217 /*
218 * If probe is NULL, then nr_probes = nr_del = 0, and then the
219 * entire entry will be removed.
220 */
221 if (nr_probes - nr_del == 0) {
222 /* N -> 0, (N > 1) */
223 *funcs = NULL;
224 debug_print_probes(*funcs);
225 return old;
226 } else {
227 int j = 0;
228 /* N -> M, (N > 1, M > 0) */
229 /* + 1 for NULL */
230 new = allocate_probes(nr_probes - nr_del + 1);
231 if (new) {
232 for (i = 0; old[i].func; i++) {
233 if ((old[i].func != tp_func->func ||
234 old[i].data != tp_func->data) &&
235 old[i].func != tp_stub_func)
236 new[j++] = old[i];
237 }
238 new[nr_probes - nr_del].func = NULL;
239 *funcs = new;
240 } else {
241 /*
242 * Failed to allocate, replace the old function
243 * with calls to tp_stub_func.
244 */
245 for (i = 0; old[i].func; i++) {
246 if (old[i].func == tp_func->func &&
247 old[i].data == tp_func->data)
248 WRITE_ONCE(old[i].func, tp_stub_func);
249 }
250 *funcs = old;
251 }
252 }
253 debug_print_probes(*funcs);
254 return old;
255}
256
257/*
258 * Count the number of functions (enum tp_func_state) in a tp_funcs array.
259 */
260static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs)
261{
262 if (!tp_funcs)
263 return TP_FUNC_0;
264 if (!tp_funcs[1].func)
265 return TP_FUNC_1;
266 if (!tp_funcs[2].func)
267 return TP_FUNC_2;
268 return TP_FUNC_N; /* 3 or more */
269}
270
271static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs)
272{
273 void *func = tp->iterator;
274
275 /* Synthetic events do not have static call sites */
276 if (!tp->static_call_key)
277 return;
278 if (nr_func_state(tp_funcs) == TP_FUNC_1)
279 func = tp_funcs[0].func;
280 __static_call_update(tp->static_call_key, tp->static_call_tramp, func);
281}
282
283/*
284 * Add the probe function to a tracepoint.
285 */
286static int tracepoint_add_func(struct tracepoint *tp,
287 struct tracepoint_func *func, int prio,
288 bool warn)
289{
290 struct tracepoint_func *old, *tp_funcs;
291 int ret;
292
293 if (tp->ext && tp->ext->regfunc && !static_key_enabled(&tp->key)) {
294 ret = tp->ext->regfunc();
295 if (ret < 0)
296 return ret;
297 }
298
299 tp_funcs = rcu_dereference_protected(tp->funcs,
300 lockdep_is_held(&tracepoints_mutex));
301 old = func_add(&tp_funcs, func, prio);
302 if (IS_ERR(old)) {
303 if (tp->ext && tp->ext->unregfunc && !static_key_enabled(&tp->key))
304 tp->ext->unregfunc();
305 WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM);
306 return PTR_ERR(old);
307 }
308
309 /*
310 * rcu_assign_pointer has as smp_store_release() which makes sure
311 * that the new probe callbacks array is consistent before setting
312 * a pointer to it. This array is referenced by __DO_TRACE from
313 * include/linux/tracepoint.h using rcu_dereference_sched().
314 */
315 switch (nr_func_state(tp_funcs)) {
316 case TP_FUNC_1: /* 0->1 */
317 /*
318 * Make sure new static func never uses old data after a
319 * 1->0->1 transition sequence.
320 */
321 tp_rcu_cond_sync(TP_TRANSITION_SYNC_1_0_1);
322 /* Set static call to first function */
323 tracepoint_update_call(tp, tp_funcs);
324 /* Both iterator and static call handle NULL tp->funcs */
325 rcu_assign_pointer(tp->funcs, tp_funcs);
326 static_branch_enable(&tp->key);
327 break;
328 case TP_FUNC_2: /* 1->2 */
329 /* Set iterator static call */
330 tracepoint_update_call(tp, tp_funcs);
331 /*
332 * Iterator callback installed before updating tp->funcs.
333 * Requires ordering between RCU assign/dereference and
334 * static call update/call.
335 */
336 fallthrough;
337 case TP_FUNC_N: /* N->N+1 (N>1) */
338 rcu_assign_pointer(tp->funcs, tp_funcs);
339 /*
340 * Make sure static func never uses incorrect data after a
341 * N->...->2->1 (N>1) transition sequence.
342 */
343 if (tp_funcs[0].data != old[0].data)
344 tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
345 break;
346 default:
347 WARN_ON_ONCE(1);
348 break;
349 }
350
351 release_probes(tp, old);
352 return 0;
353}
354
355/*
356 * Remove a probe function from a tracepoint.
357 * Note: only waiting an RCU period after setting elem->call to the empty
358 * function insures that the original callback is not used anymore. This insured
359 * by preempt_disable around the call site.
360 */
361static int tracepoint_remove_func(struct tracepoint *tp,
362 struct tracepoint_func *func)
363{
364 struct tracepoint_func *old, *tp_funcs;
365
366 tp_funcs = rcu_dereference_protected(tp->funcs,
367 lockdep_is_held(&tracepoints_mutex));
368 old = func_remove(&tp_funcs, func);
369 if (WARN_ON_ONCE(IS_ERR(old)))
370 return PTR_ERR(old);
371
372 if (tp_funcs == old)
373 /* Failed allocating new tp_funcs, replaced func with stub */
374 return 0;
375
376 switch (nr_func_state(tp_funcs)) {
377 case TP_FUNC_0: /* 1->0 */
378 /* Removed last function */
379 if (tp->ext && tp->ext->unregfunc && static_key_enabled(&tp->key))
380 tp->ext->unregfunc();
381 static_branch_disable(&tp->key);
382 /* Set iterator static call */
383 tracepoint_update_call(tp, tp_funcs);
384 /* Both iterator and static call handle NULL tp->funcs */
385 rcu_assign_pointer(tp->funcs, NULL);
386 /*
387 * Make sure new static func never uses old data after a
388 * 1->0->1 transition sequence.
389 */
390 tp_rcu_get_state(TP_TRANSITION_SYNC_1_0_1);
391 break;
392 case TP_FUNC_1: /* 2->1 */
393 rcu_assign_pointer(tp->funcs, tp_funcs);
394 /*
395 * Make sure static func never uses incorrect data after a
396 * N->...->2->1 (N>2) transition sequence. If the first
397 * element's data has changed, then force the synchronization
398 * to prevent current readers that have loaded the old data
399 * from calling the new function.
400 */
401 if (tp_funcs[0].data != old[0].data)
402 tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
403 tp_rcu_cond_sync(TP_TRANSITION_SYNC_N_2_1);
404 /* Set static call to first function */
405 tracepoint_update_call(tp, tp_funcs);
406 break;
407 case TP_FUNC_2: /* N->N-1 (N>2) */
408 fallthrough;
409 case TP_FUNC_N:
410 rcu_assign_pointer(tp->funcs, tp_funcs);
411 /*
412 * Make sure static func never uses incorrect data after a
413 * N->...->2->1 (N>2) transition sequence.
414 */
415 if (tp_funcs[0].data != old[0].data)
416 tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
417 break;
418 default:
419 WARN_ON_ONCE(1);
420 break;
421 }
422 release_probes(tp, old);
423 return 0;
424}
425
426/**
427 * tracepoint_probe_register_prio_may_exist - Connect a probe to a tracepoint with priority
428 * @tp: tracepoint
429 * @probe: probe handler
430 * @data: tracepoint data
431 * @prio: priority of this function over other registered functions
432 *
433 * Same as tracepoint_probe_register_prio() except that it will not warn
434 * if the tracepoint is already registered.
435 */
436int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe,
437 void *data, int prio)
438{
439 struct tracepoint_func tp_func;
440 int ret;
441
442 mutex_lock(&tracepoints_mutex);
443 tp_func.func = probe;
444 tp_func.data = data;
445 tp_func.prio = prio;
446 ret = tracepoint_add_func(tp, &tp_func, prio, false);
447 mutex_unlock(&tracepoints_mutex);
448 return ret;
449}
450EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist);
451
452/**
453 * tracepoint_probe_register_prio - Connect a probe to a tracepoint with priority
454 * @tp: tracepoint
455 * @probe: probe handler
456 * @data: tracepoint data
457 * @prio: priority of this function over other registered functions
458 *
459 * Returns 0 if ok, error value on error.
460 * Note: if @tp is within a module, the caller is responsible for
461 * unregistering the probe before the module is gone. This can be
462 * performed either with a tracepoint module going notifier, or from
463 * within module exit functions.
464 */
465int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe,
466 void *data, int prio)
467{
468 struct tracepoint_func tp_func;
469 int ret;
470
471 mutex_lock(&tracepoints_mutex);
472 tp_func.func = probe;
473 tp_func.data = data;
474 tp_func.prio = prio;
475 ret = tracepoint_add_func(tp, &tp_func, prio, true);
476 mutex_unlock(&tracepoints_mutex);
477 return ret;
478}
479EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio);
480
481/**
482 * tracepoint_probe_register - Connect a probe to a tracepoint
483 * @tp: tracepoint
484 * @probe: probe handler
485 * @data: tracepoint data
486 *
487 * Returns 0 if ok, error value on error.
488 * Note: if @tp is within a module, the caller is responsible for
489 * unregistering the probe before the module is gone. This can be
490 * performed either with a tracepoint module going notifier, or from
491 * within module exit functions.
492 */
493int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
494{
495 return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO);
496}
497EXPORT_SYMBOL_GPL(tracepoint_probe_register);
498
499/**
500 * tracepoint_probe_unregister - Disconnect a probe from a tracepoint
501 * @tp: tracepoint
502 * @probe: probe function pointer
503 * @data: tracepoint data
504 *
505 * Returns 0 if ok, error value on error.
506 */
507int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
508{
509 struct tracepoint_func tp_func;
510 int ret;
511
512 mutex_lock(&tracepoints_mutex);
513 tp_func.func = probe;
514 tp_func.data = data;
515 ret = tracepoint_remove_func(tp, &tp_func);
516 mutex_unlock(&tracepoints_mutex);
517 return ret;
518}
519EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
520
521static void for_each_tracepoint_range(
522 tracepoint_ptr_t *begin, tracepoint_ptr_t *end,
523 void (*fct)(struct tracepoint *tp, void *priv),
524 void *priv)
525{
526 tracepoint_ptr_t *iter;
527
528 if (!begin)
529 return;
530 for (iter = begin; iter < end; iter++)
531 fct(tracepoint_ptr_deref(iter), priv);
532}
533
534#ifdef CONFIG_MODULES
535bool trace_module_has_bad_taint(struct module *mod)
536{
537 return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
538 (1 << TAINT_UNSIGNED_MODULE) | (1 << TAINT_TEST) |
539 (1 << TAINT_LIVEPATCH));
540}
541
542static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
543
544/**
545 * register_tracepoint_module_notifier - register tracepoint coming/going notifier
546 * @nb: notifier block
547 *
548 * Notifiers registered with this function are called on module
549 * coming/going with the tracepoint_module_list_mutex held.
550 * The notifier block callback should expect a "struct tp_module" data
551 * pointer.
552 */
553int register_tracepoint_module_notifier(struct notifier_block *nb)
554{
555 struct tp_module *tp_mod;
556 int ret;
557
558 mutex_lock(&tracepoint_module_list_mutex);
559 ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb);
560 if (ret)
561 goto end;
562 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
563 (void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod);
564end:
565 mutex_unlock(&tracepoint_module_list_mutex);
566 return ret;
567}
568EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier);
569
570/**
571 * unregister_tracepoint_module_notifier - unregister tracepoint coming/going notifier
572 * @nb: notifier block
573 *
574 * The notifier block callback should expect a "struct tp_module" data
575 * pointer.
576 */
577int unregister_tracepoint_module_notifier(struct notifier_block *nb)
578{
579 struct tp_module *tp_mod;
580 int ret;
581
582 mutex_lock(&tracepoint_module_list_mutex);
583 ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb);
584 if (ret)
585 goto end;
586 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
587 (void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod);
588end:
589 mutex_unlock(&tracepoint_module_list_mutex);
590 return ret;
591
592}
593EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
594
595/*
596 * Ensure the tracer unregistered the module's probes before the module
597 * teardown is performed. Prevents leaks of probe and data pointers.
598 */
599static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv)
600{
601 WARN_ON_ONCE(tp->funcs);
602}
603
604static int tracepoint_module_coming(struct module *mod)
605{
606 struct tp_module *tp_mod;
607
608 if (!mod->num_tracepoints)
609 return 0;
610
611 /*
612 * We skip modules that taint the kernel, especially those with different
613 * module headers (for forced load), to make sure we don't cause a crash.
614 * Staging, out-of-tree, unsigned GPL, and test modules are fine.
615 */
616 if (trace_module_has_bad_taint(mod))
617 return 0;
618
619 tp_mod = kmalloc_obj(struct tp_module);
620 if (!tp_mod)
621 return -ENOMEM;
622 tp_mod->mod = mod;
623
624 mutex_lock(&tracepoint_module_list_mutex);
625 list_add_tail(&tp_mod->list, &tracepoint_module_list);
626 blocking_notifier_call_chain(&tracepoint_notify_list,
627 MODULE_STATE_COMING, tp_mod);
628 mutex_unlock(&tracepoint_module_list_mutex);
629 return 0;
630}
631
632static void tracepoint_module_going(struct module *mod)
633{
634 struct tp_module *tp_mod;
635
636 if (!mod->num_tracepoints)
637 return;
638
639 mutex_lock(&tracepoint_module_list_mutex);
640 list_for_each_entry(tp_mod, &tracepoint_module_list, list) {
641 if (tp_mod->mod == mod) {
642 blocking_notifier_call_chain(&tracepoint_notify_list,
643 MODULE_STATE_GOING, tp_mod);
644 list_del(&tp_mod->list);
645 kfree(tp_mod);
646 /*
647 * Called the going notifier before checking for
648 * quiescence.
649 */
650 for_each_tracepoint_range(mod->tracepoints_ptrs,
651 mod->tracepoints_ptrs + mod->num_tracepoints,
652 tp_module_going_check_quiescent, NULL);
653 break;
654 }
655 }
656 /*
657 * In the case of modules that were tainted at "coming", we'll simply
658 * walk through the list without finding it. We cannot use the "tainted"
659 * flag on "going", in case a module taints the kernel only after being
660 * loaded.
661 */
662 mutex_unlock(&tracepoint_module_list_mutex);
663}
664
665static int tracepoint_module_notify(struct notifier_block *self,
666 unsigned long val, void *data)
667{
668 struct module *mod = data;
669 int ret = 0;
670
671 switch (val) {
672 case MODULE_STATE_COMING:
673 ret = tracepoint_module_coming(mod);
674 break;
675 case MODULE_STATE_LIVE:
676 break;
677 case MODULE_STATE_GOING:
678 tracepoint_module_going(mod);
679 break;
680 case MODULE_STATE_UNFORMED:
681 break;
682 }
683 return notifier_from_errno(ret);
684}
685
686static struct notifier_block tracepoint_module_nb = {
687 .notifier_call = tracepoint_module_notify,
688 .priority = 0,
689};
690
691static __init int init_tracepoints(void)
692{
693 int ret;
694
695 ret = register_module_notifier(&tracepoint_module_nb);
696 if (ret)
697 pr_warn("Failed to register tracepoint module enter notifier\n");
698
699 return ret;
700}
701__initcall(init_tracepoints);
702
703/**
704 * for_each_tracepoint_in_module - iteration on all tracepoints in a module
705 * @mod: module
706 * @fct: callback
707 * @priv: private data
708 */
709void for_each_tracepoint_in_module(struct module *mod,
710 void (*fct)(struct tracepoint *tp,
711 struct module *mod, void *priv),
712 void *priv)
713{
714 tracepoint_ptr_t *begin, *end, *iter;
715
716 lockdep_assert_held(&tracepoint_module_list_mutex);
717
718 if (!mod)
719 return;
720
721 begin = mod->tracepoints_ptrs;
722 end = mod->tracepoints_ptrs + mod->num_tracepoints;
723
724 for (iter = begin; iter < end; iter++)
725 fct(tracepoint_ptr_deref(iter), mod, priv);
726}
727
728/**
729 * for_each_module_tracepoint - iteration on all tracepoints in all modules
730 * @fct: callback
731 * @priv: private data
732 */
733void for_each_module_tracepoint(void (*fct)(struct tracepoint *tp,
734 struct module *mod, void *priv),
735 void *priv)
736{
737 struct tp_module *tp_mod;
738
739 mutex_lock(&tracepoint_module_list_mutex);
740 list_for_each_entry(tp_mod, &tracepoint_module_list, list)
741 for_each_tracepoint_in_module(tp_mod->mod, fct, priv);
742 mutex_unlock(&tracepoint_module_list_mutex);
743}
744#endif /* CONFIG_MODULES */
745
746/**
747 * for_each_kernel_tracepoint - iteration on all kernel tracepoints
748 * @fct: callback
749 * @priv: private data
750 */
751void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
752 void *priv)
753{
754 for_each_tracepoint_range(__start___tracepoints_ptrs,
755 __stop___tracepoints_ptrs, fct, priv);
756}
757EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);
758
759#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
760
761/* NB: reg/unreg are called while guarded with the tracepoints_mutex */
762static int sys_tracepoint_refcount;
763
764int syscall_regfunc(void)
765{
766 struct task_struct *p, *t;
767
768 if (!sys_tracepoint_refcount) {
769 read_lock(&tasklist_lock);
770 for_each_process_thread(p, t) {
771 set_task_syscall_work(t, SYSCALL_TRACEPOINT);
772 }
773 read_unlock(&tasklist_lock);
774 }
775 sys_tracepoint_refcount++;
776
777 return 0;
778}
779
780void syscall_unregfunc(void)
781{
782 struct task_struct *p, *t;
783
784 sys_tracepoint_refcount--;
785 if (!sys_tracepoint_refcount) {
786 read_lock(&tasklist_lock);
787 for_each_process_thread(p, t) {
788 clear_task_syscall_work(t, SYSCALL_TRACEPOINT);
789 }
790 read_unlock(&tasklist_lock);
791 }
792}
793#endif