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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
fe9d4f57 AD |
2 | #include <linux/kdebug.h> |
3 | #include <linux/kprobes.h> | |
9984de1a | 4 | #include <linux/export.h> |
fe9d4f57 AD |
5 | #include <linux/notifier.h> |
6 | #include <linux/rcupdate.h> | |
7 | #include <linux/vmalloc.h> | |
c166f23c | 8 | #include <linux/reboot.h> |
fe9d4f57 AD |
9 | |
10 | /* | |
11 | * Notifier list for kernel code which wants to be called | |
12 | * at shutdown. This is used to stop any idling DMA operations | |
13 | * and the like. | |
14 | */ | |
15 | BLOCKING_NOTIFIER_HEAD(reboot_notifier_list); | |
16 | ||
17 | /* | |
18 | * Notifier chain core routines. The exported routines below | |
19 | * are layered on top of these, with appropriate locking added. | |
20 | */ | |
21 | ||
22 | static int notifier_chain_register(struct notifier_block **nl, | |
23 | struct notifier_block *n) | |
24 | { | |
25 | while ((*nl) != NULL) { | |
1a50cb80 XN |
26 | if (unlikely((*nl) == n)) { |
27 | WARN(1, "double register detected"); | |
28 | return 0; | |
29 | } | |
fe9d4f57 AD |
30 | if (n->priority > (*nl)->priority) |
31 | break; | |
32 | nl = &((*nl)->next); | |
33 | } | |
34 | n->next = *nl; | |
35 | rcu_assign_pointer(*nl, n); | |
36 | return 0; | |
37 | } | |
38 | ||
39 | static int notifier_chain_unregister(struct notifier_block **nl, | |
40 | struct notifier_block *n) | |
41 | { | |
42 | while ((*nl) != NULL) { | |
43 | if ((*nl) == n) { | |
44 | rcu_assign_pointer(*nl, n->next); | |
45 | return 0; | |
46 | } | |
47 | nl = &((*nl)->next); | |
48 | } | |
49 | return -ENOENT; | |
50 | } | |
51 | ||
52 | /** | |
53 | * notifier_call_chain - Informs the registered notifiers about an event. | |
54 | * @nl: Pointer to head of the blocking notifier chain | |
55 | * @val: Value passed unmodified to notifier function | |
56 | * @v: Pointer passed unmodified to notifier function | |
57 | * @nr_to_call: Number of notifier functions to be called. Don't care | |
58 | * value of this parameter is -1. | |
59 | * @nr_calls: Records the number of notifications sent. Don't care | |
60 | * value of this field is NULL. | |
61 | * @returns: notifier_call_chain returns the value returned by the | |
62 | * last notifier function called. | |
63 | */ | |
b40a2cb6 MH |
64 | static int notifier_call_chain(struct notifier_block **nl, |
65 | unsigned long val, void *v, | |
66 | int nr_to_call, int *nr_calls) | |
fe9d4f57 AD |
67 | { |
68 | int ret = NOTIFY_DONE; | |
69 | struct notifier_block *nb, *next_nb; | |
70 | ||
d11c563d | 71 | nb = rcu_dereference_raw(*nl); |
fe9d4f57 AD |
72 | |
73 | while (nb && nr_to_call) { | |
d11c563d | 74 | next_nb = rcu_dereference_raw(nb->next); |
1b2439db AV |
75 | |
76 | #ifdef CONFIG_DEBUG_NOTIFIERS | |
ab7476cf | 77 | if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) { |
1b2439db AV |
78 | WARN(1, "Invalid notifier called!"); |
79 | nb = next_nb; | |
80 | continue; | |
81 | } | |
82 | #endif | |
fe9d4f57 AD |
83 | ret = nb->notifier_call(nb, val, v); |
84 | ||
85 | if (nr_calls) | |
86 | (*nr_calls)++; | |
87 | ||
3e6daded | 88 | if (ret & NOTIFY_STOP_MASK) |
fe9d4f57 AD |
89 | break; |
90 | nb = next_nb; | |
91 | nr_to_call--; | |
92 | } | |
93 | return ret; | |
94 | } | |
b40a2cb6 | 95 | NOKPROBE_SYMBOL(notifier_call_chain); |
fe9d4f57 AD |
96 | |
97 | /* | |
98 | * Atomic notifier chain routines. Registration and unregistration | |
99 | * use a spinlock, and call_chain is synchronized by RCU (no locks). | |
100 | */ | |
101 | ||
102 | /** | |
103 | * atomic_notifier_chain_register - Add notifier to an atomic notifier chain | |
104 | * @nh: Pointer to head of the atomic notifier chain | |
105 | * @n: New entry in notifier chain | |
106 | * | |
107 | * Adds a notifier to an atomic notifier chain. | |
108 | * | |
109 | * Currently always returns zero. | |
110 | */ | |
111 | int atomic_notifier_chain_register(struct atomic_notifier_head *nh, | |
112 | struct notifier_block *n) | |
113 | { | |
114 | unsigned long flags; | |
115 | int ret; | |
116 | ||
117 | spin_lock_irqsave(&nh->lock, flags); | |
118 | ret = notifier_chain_register(&nh->head, n); | |
119 | spin_unlock_irqrestore(&nh->lock, flags); | |
120 | return ret; | |
121 | } | |
122 | EXPORT_SYMBOL_GPL(atomic_notifier_chain_register); | |
123 | ||
124 | /** | |
125 | * atomic_notifier_chain_unregister - Remove notifier from an atomic notifier chain | |
126 | * @nh: Pointer to head of the atomic notifier chain | |
127 | * @n: Entry to remove from notifier chain | |
128 | * | |
129 | * Removes a notifier from an atomic notifier chain. | |
130 | * | |
131 | * Returns zero on success or %-ENOENT on failure. | |
132 | */ | |
133 | int atomic_notifier_chain_unregister(struct atomic_notifier_head *nh, | |
134 | struct notifier_block *n) | |
135 | { | |
136 | unsigned long flags; | |
137 | int ret; | |
138 | ||
139 | spin_lock_irqsave(&nh->lock, flags); | |
140 | ret = notifier_chain_unregister(&nh->head, n); | |
141 | spin_unlock_irqrestore(&nh->lock, flags); | |
142 | synchronize_rcu(); | |
143 | return ret; | |
144 | } | |
145 | EXPORT_SYMBOL_GPL(atomic_notifier_chain_unregister); | |
146 | ||
147 | /** | |
148 | * __atomic_notifier_call_chain - Call functions in an atomic notifier chain | |
149 | * @nh: Pointer to head of the atomic notifier chain | |
150 | * @val: Value passed unmodified to notifier function | |
151 | * @v: Pointer passed unmodified to notifier function | |
152 | * @nr_to_call: See the comment for notifier_call_chain. | |
153 | * @nr_calls: See the comment for notifier_call_chain. | |
154 | * | |
155 | * Calls each function in a notifier chain in turn. The functions | |
156 | * run in an atomic context, so they must not block. | |
157 | * This routine uses RCU to synchronize with changes to the chain. | |
158 | * | |
159 | * If the return value of the notifier can be and'ed | |
160 | * with %NOTIFY_STOP_MASK then atomic_notifier_call_chain() | |
161 | * will return immediately, with the return value of | |
162 | * the notifier function which halted execution. | |
163 | * Otherwise the return value is the return value | |
164 | * of the last notifier function called. | |
165 | */ | |
b40a2cb6 MH |
166 | int __atomic_notifier_call_chain(struct atomic_notifier_head *nh, |
167 | unsigned long val, void *v, | |
168 | int nr_to_call, int *nr_calls) | |
fe9d4f57 AD |
169 | { |
170 | int ret; | |
171 | ||
172 | rcu_read_lock(); | |
173 | ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls); | |
174 | rcu_read_unlock(); | |
175 | return ret; | |
176 | } | |
177 | EXPORT_SYMBOL_GPL(__atomic_notifier_call_chain); | |
b40a2cb6 | 178 | NOKPROBE_SYMBOL(__atomic_notifier_call_chain); |
fe9d4f57 | 179 | |
b40a2cb6 MH |
180 | int atomic_notifier_call_chain(struct atomic_notifier_head *nh, |
181 | unsigned long val, void *v) | |
fe9d4f57 AD |
182 | { |
183 | return __atomic_notifier_call_chain(nh, val, v, -1, NULL); | |
184 | } | |
185 | EXPORT_SYMBOL_GPL(atomic_notifier_call_chain); | |
b40a2cb6 | 186 | NOKPROBE_SYMBOL(atomic_notifier_call_chain); |
fe9d4f57 AD |
187 | |
188 | /* | |
189 | * Blocking notifier chain routines. All access to the chain is | |
190 | * synchronized by an rwsem. | |
191 | */ | |
192 | ||
193 | /** | |
194 | * blocking_notifier_chain_register - Add notifier to a blocking notifier chain | |
195 | * @nh: Pointer to head of the blocking notifier chain | |
196 | * @n: New entry in notifier chain | |
197 | * | |
198 | * Adds a notifier to a blocking notifier chain. | |
199 | * Must be called in process context. | |
200 | * | |
201 | * Currently always returns zero. | |
202 | */ | |
203 | int blocking_notifier_chain_register(struct blocking_notifier_head *nh, | |
204 | struct notifier_block *n) | |
205 | { | |
206 | int ret; | |
207 | ||
208 | /* | |
209 | * This code gets used during boot-up, when task switching is | |
210 | * not yet working and interrupts must remain disabled. At | |
211 | * such times we must not call down_write(). | |
212 | */ | |
213 | if (unlikely(system_state == SYSTEM_BOOTING)) | |
214 | return notifier_chain_register(&nh->head, n); | |
215 | ||
216 | down_write(&nh->rwsem); | |
217 | ret = notifier_chain_register(&nh->head, n); | |
218 | up_write(&nh->rwsem); | |
219 | return ret; | |
220 | } | |
221 | EXPORT_SYMBOL_GPL(blocking_notifier_chain_register); | |
222 | ||
223 | /** | |
224 | * blocking_notifier_chain_unregister - Remove notifier from a blocking notifier chain | |
225 | * @nh: Pointer to head of the blocking notifier chain | |
226 | * @n: Entry to remove from notifier chain | |
227 | * | |
228 | * Removes a notifier from a blocking notifier chain. | |
229 | * Must be called from process context. | |
230 | * | |
231 | * Returns zero on success or %-ENOENT on failure. | |
232 | */ | |
233 | int blocking_notifier_chain_unregister(struct blocking_notifier_head *nh, | |
234 | struct notifier_block *n) | |
235 | { | |
236 | int ret; | |
237 | ||
238 | /* | |
239 | * This code gets used during boot-up, when task switching is | |
240 | * not yet working and interrupts must remain disabled. At | |
241 | * such times we must not call down_write(). | |
242 | */ | |
243 | if (unlikely(system_state == SYSTEM_BOOTING)) | |
244 | return notifier_chain_unregister(&nh->head, n); | |
245 | ||
246 | down_write(&nh->rwsem); | |
247 | ret = notifier_chain_unregister(&nh->head, n); | |
248 | up_write(&nh->rwsem); | |
249 | return ret; | |
250 | } | |
251 | EXPORT_SYMBOL_GPL(blocking_notifier_chain_unregister); | |
252 | ||
253 | /** | |
254 | * __blocking_notifier_call_chain - Call functions in a blocking notifier chain | |
255 | * @nh: Pointer to head of the blocking notifier chain | |
256 | * @val: Value passed unmodified to notifier function | |
257 | * @v: Pointer passed unmodified to notifier function | |
258 | * @nr_to_call: See comment for notifier_call_chain. | |
259 | * @nr_calls: See comment for notifier_call_chain. | |
260 | * | |
261 | * Calls each function in a notifier chain in turn. The functions | |
262 | * run in a process context, so they are allowed to block. | |
263 | * | |
264 | * If the return value of the notifier can be and'ed | |
265 | * with %NOTIFY_STOP_MASK then blocking_notifier_call_chain() | |
266 | * will return immediately, with the return value of | |
267 | * the notifier function which halted execution. | |
268 | * Otherwise the return value is the return value | |
269 | * of the last notifier function called. | |
270 | */ | |
271 | int __blocking_notifier_call_chain(struct blocking_notifier_head *nh, | |
272 | unsigned long val, void *v, | |
273 | int nr_to_call, int *nr_calls) | |
274 | { | |
275 | int ret = NOTIFY_DONE; | |
276 | ||
277 | /* | |
278 | * We check the head outside the lock, but if this access is | |
279 | * racy then it does not matter what the result of the test | |
280 | * is, we re-check the list after having taken the lock anyway: | |
281 | */ | |
8857563b | 282 | if (rcu_access_pointer(nh->head)) { |
fe9d4f57 AD |
283 | down_read(&nh->rwsem); |
284 | ret = notifier_call_chain(&nh->head, val, v, nr_to_call, | |
285 | nr_calls); | |
286 | up_read(&nh->rwsem); | |
287 | } | |
288 | return ret; | |
289 | } | |
290 | EXPORT_SYMBOL_GPL(__blocking_notifier_call_chain); | |
291 | ||
292 | int blocking_notifier_call_chain(struct blocking_notifier_head *nh, | |
293 | unsigned long val, void *v) | |
294 | { | |
295 | return __blocking_notifier_call_chain(nh, val, v, -1, NULL); | |
296 | } | |
297 | EXPORT_SYMBOL_GPL(blocking_notifier_call_chain); | |
298 | ||
299 | /* | |
300 | * Raw notifier chain routines. There is no protection; | |
301 | * the caller must provide it. Use at your own risk! | |
302 | */ | |
303 | ||
304 | /** | |
305 | * raw_notifier_chain_register - Add notifier to a raw notifier chain | |
306 | * @nh: Pointer to head of the raw notifier chain | |
307 | * @n: New entry in notifier chain | |
308 | * | |
309 | * Adds a notifier to a raw notifier chain. | |
310 | * All locking must be provided by the caller. | |
311 | * | |
312 | * Currently always returns zero. | |
313 | */ | |
314 | int raw_notifier_chain_register(struct raw_notifier_head *nh, | |
315 | struct notifier_block *n) | |
316 | { | |
317 | return notifier_chain_register(&nh->head, n); | |
318 | } | |
319 | EXPORT_SYMBOL_GPL(raw_notifier_chain_register); | |
320 | ||
321 | /** | |
322 | * raw_notifier_chain_unregister - Remove notifier from a raw notifier chain | |
323 | * @nh: Pointer to head of the raw notifier chain | |
324 | * @n: Entry to remove from notifier chain | |
325 | * | |
326 | * Removes a notifier from a raw notifier chain. | |
327 | * All locking must be provided by the caller. | |
328 | * | |
329 | * Returns zero on success or %-ENOENT on failure. | |
330 | */ | |
331 | int raw_notifier_chain_unregister(struct raw_notifier_head *nh, | |
332 | struct notifier_block *n) | |
333 | { | |
334 | return notifier_chain_unregister(&nh->head, n); | |
335 | } | |
336 | EXPORT_SYMBOL_GPL(raw_notifier_chain_unregister); | |
337 | ||
338 | /** | |
339 | * __raw_notifier_call_chain - Call functions in a raw notifier chain | |
340 | * @nh: Pointer to head of the raw notifier chain | |
341 | * @val: Value passed unmodified to notifier function | |
342 | * @v: Pointer passed unmodified to notifier function | |
343 | * @nr_to_call: See comment for notifier_call_chain. | |
344 | * @nr_calls: See comment for notifier_call_chain | |
345 | * | |
346 | * Calls each function in a notifier chain in turn. The functions | |
347 | * run in an undefined context. | |
348 | * All locking must be provided by the caller. | |
349 | * | |
350 | * If the return value of the notifier can be and'ed | |
351 | * with %NOTIFY_STOP_MASK then raw_notifier_call_chain() | |
352 | * will return immediately, with the return value of | |
353 | * the notifier function which halted execution. | |
354 | * Otherwise the return value is the return value | |
355 | * of the last notifier function called. | |
356 | */ | |
357 | int __raw_notifier_call_chain(struct raw_notifier_head *nh, | |
358 | unsigned long val, void *v, | |
359 | int nr_to_call, int *nr_calls) | |
360 | { | |
361 | return notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls); | |
362 | } | |
363 | EXPORT_SYMBOL_GPL(__raw_notifier_call_chain); | |
364 | ||
365 | int raw_notifier_call_chain(struct raw_notifier_head *nh, | |
366 | unsigned long val, void *v) | |
367 | { | |
368 | return __raw_notifier_call_chain(nh, val, v, -1, NULL); | |
369 | } | |
370 | EXPORT_SYMBOL_GPL(raw_notifier_call_chain); | |
371 | ||
83fe27ea | 372 | #ifdef CONFIG_SRCU |
fe9d4f57 AD |
373 | /* |
374 | * SRCU notifier chain routines. Registration and unregistration | |
375 | * use a mutex, and call_chain is synchronized by SRCU (no locks). | |
376 | */ | |
377 | ||
378 | /** | |
379 | * srcu_notifier_chain_register - Add notifier to an SRCU notifier chain | |
380 | * @nh: Pointer to head of the SRCU notifier chain | |
381 | * @n: New entry in notifier chain | |
382 | * | |
383 | * Adds a notifier to an SRCU notifier chain. | |
384 | * Must be called in process context. | |
385 | * | |
386 | * Currently always returns zero. | |
387 | */ | |
388 | int srcu_notifier_chain_register(struct srcu_notifier_head *nh, | |
389 | struct notifier_block *n) | |
390 | { | |
391 | int ret; | |
392 | ||
393 | /* | |
394 | * This code gets used during boot-up, when task switching is | |
395 | * not yet working and interrupts must remain disabled. At | |
396 | * such times we must not call mutex_lock(). | |
397 | */ | |
398 | if (unlikely(system_state == SYSTEM_BOOTING)) | |
399 | return notifier_chain_register(&nh->head, n); | |
400 | ||
401 | mutex_lock(&nh->mutex); | |
402 | ret = notifier_chain_register(&nh->head, n); | |
403 | mutex_unlock(&nh->mutex); | |
404 | return ret; | |
405 | } | |
406 | EXPORT_SYMBOL_GPL(srcu_notifier_chain_register); | |
407 | ||
408 | /** | |
409 | * srcu_notifier_chain_unregister - Remove notifier from an SRCU notifier chain | |
410 | * @nh: Pointer to head of the SRCU notifier chain | |
411 | * @n: Entry to remove from notifier chain | |
412 | * | |
413 | * Removes a notifier from an SRCU notifier chain. | |
414 | * Must be called from process context. | |
415 | * | |
416 | * Returns zero on success or %-ENOENT on failure. | |
417 | */ | |
418 | int srcu_notifier_chain_unregister(struct srcu_notifier_head *nh, | |
419 | struct notifier_block *n) | |
420 | { | |
421 | int ret; | |
422 | ||
423 | /* | |
424 | * This code gets used during boot-up, when task switching is | |
425 | * not yet working and interrupts must remain disabled. At | |
426 | * such times we must not call mutex_lock(). | |
427 | */ | |
428 | if (unlikely(system_state == SYSTEM_BOOTING)) | |
429 | return notifier_chain_unregister(&nh->head, n); | |
430 | ||
431 | mutex_lock(&nh->mutex); | |
432 | ret = notifier_chain_unregister(&nh->head, n); | |
433 | mutex_unlock(&nh->mutex); | |
434 | synchronize_srcu(&nh->srcu); | |
435 | return ret; | |
436 | } | |
437 | EXPORT_SYMBOL_GPL(srcu_notifier_chain_unregister); | |
438 | ||
439 | /** | |
440 | * __srcu_notifier_call_chain - Call functions in an SRCU notifier chain | |
441 | * @nh: Pointer to head of the SRCU notifier chain | |
442 | * @val: Value passed unmodified to notifier function | |
443 | * @v: Pointer passed unmodified to notifier function | |
444 | * @nr_to_call: See comment for notifier_call_chain. | |
445 | * @nr_calls: See comment for notifier_call_chain | |
446 | * | |
447 | * Calls each function in a notifier chain in turn. The functions | |
448 | * run in a process context, so they are allowed to block. | |
449 | * | |
450 | * If the return value of the notifier can be and'ed | |
451 | * with %NOTIFY_STOP_MASK then srcu_notifier_call_chain() | |
452 | * will return immediately, with the return value of | |
453 | * the notifier function which halted execution. | |
454 | * Otherwise the return value is the return value | |
455 | * of the last notifier function called. | |
456 | */ | |
457 | int __srcu_notifier_call_chain(struct srcu_notifier_head *nh, | |
458 | unsigned long val, void *v, | |
459 | int nr_to_call, int *nr_calls) | |
460 | { | |
461 | int ret; | |
462 | int idx; | |
463 | ||
464 | idx = srcu_read_lock(&nh->srcu); | |
465 | ret = notifier_call_chain(&nh->head, val, v, nr_to_call, nr_calls); | |
466 | srcu_read_unlock(&nh->srcu, idx); | |
467 | return ret; | |
468 | } | |
469 | EXPORT_SYMBOL_GPL(__srcu_notifier_call_chain); | |
470 | ||
471 | int srcu_notifier_call_chain(struct srcu_notifier_head *nh, | |
472 | unsigned long val, void *v) | |
473 | { | |
474 | return __srcu_notifier_call_chain(nh, val, v, -1, NULL); | |
475 | } | |
476 | EXPORT_SYMBOL_GPL(srcu_notifier_call_chain); | |
477 | ||
478 | /** | |
479 | * srcu_init_notifier_head - Initialize an SRCU notifier head | |
480 | * @nh: Pointer to head of the srcu notifier chain | |
481 | * | |
482 | * Unlike other sorts of notifier heads, SRCU notifier heads require | |
483 | * dynamic initialization. Be sure to call this routine before | |
484 | * calling any of the other SRCU notifier routines for this head. | |
485 | * | |
486 | * If an SRCU notifier head is deallocated, it must first be cleaned | |
487 | * up by calling srcu_cleanup_notifier_head(). Otherwise the head's | |
488 | * per-cpu data (used by the SRCU mechanism) will leak. | |
489 | */ | |
490 | void srcu_init_notifier_head(struct srcu_notifier_head *nh) | |
491 | { | |
492 | mutex_init(&nh->mutex); | |
493 | if (init_srcu_struct(&nh->srcu) < 0) | |
494 | BUG(); | |
495 | nh->head = NULL; | |
496 | } | |
497 | EXPORT_SYMBOL_GPL(srcu_init_notifier_head); | |
498 | ||
83fe27ea PK |
499 | #endif /* CONFIG_SRCU */ |
500 | ||
fe9d4f57 AD |
501 | static ATOMIC_NOTIFIER_HEAD(die_chain); |
502 | ||
b40a2cb6 | 503 | int notrace notify_die(enum die_val val, const char *str, |
fe9d4f57 AD |
504 | struct pt_regs *regs, long err, int trap, int sig) |
505 | { | |
506 | struct die_args args = { | |
507 | .regs = regs, | |
508 | .str = str, | |
509 | .err = err, | |
510 | .trapnr = trap, | |
511 | .signr = sig, | |
512 | ||
513 | }; | |
5778077d | 514 | RCU_LOCKDEP_WARN(!rcu_is_watching(), |
e727c7d7 | 515 | "notify_die called but RCU thinks we're quiescent"); |
fe9d4f57 AD |
516 | return atomic_notifier_call_chain(&die_chain, val, &args); |
517 | } | |
b40a2cb6 | 518 | NOKPROBE_SYMBOL(notify_die); |
fe9d4f57 AD |
519 | |
520 | int register_die_notifier(struct notifier_block *nb) | |
521 | { | |
763802b5 | 522 | vmalloc_sync_mappings(); |
fe9d4f57 AD |
523 | return atomic_notifier_chain_register(&die_chain, nb); |
524 | } | |
525 | EXPORT_SYMBOL_GPL(register_die_notifier); | |
526 | ||
527 | int unregister_die_notifier(struct notifier_block *nb) | |
528 | { | |
529 | return atomic_notifier_chain_unregister(&die_chain, nb); | |
530 | } | |
531 | EXPORT_SYMBOL_GPL(unregister_die_notifier); |