projects/linux·blob master · refs

947 lines · 23.0 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * jump label support
4 *
5 * Copyright (C) 2009 Jason Baron <[email protected]>
6 * Copyright (C) 2011 Peter Zijlstra
7 *
8 */
9#include <linux/memory.h>
10#include <linux/uaccess.h>
11#include <linux/module.h>
12#include <linux/list.h>
13#include <linux/slab.h>
14#include <linux/sort.h>
15#include <linux/err.h>
16#include <linux/static_key.h>
17#include <linux/jump_label_ratelimit.h>
18#include <linux/bug.h>
19#include <linux/cpu.h>
20#include <asm/sections.h>
21
22/* mutex to protect coming/going of the jump_label table */
23static DEFINE_MUTEX(jump_label_mutex);
24
25void jump_label_lock(void)
26{
27 mutex_lock(&jump_label_mutex);
28}
29
30void jump_label_unlock(void)
31{
32 mutex_unlock(&jump_label_mutex);
33}
34
35static int jump_label_cmp(const void *a, const void *b)
36{
37 const struct jump_entry *jea = a;
38 const struct jump_entry *jeb = b;
39
40 /*
41 * Entrires are sorted by key.
42 */
43 if (jump_entry_key(jea) < jump_entry_key(jeb))
44 return -1;
45
46 if (jump_entry_key(jea) > jump_entry_key(jeb))
47 return 1;
48
49 /*
50 * In the batching mode, entries should also be sorted by the code
51 * inside the already sorted list of entries, enabling a bsearch in
52 * the vector.
53 */
54 if (jump_entry_code(jea) < jump_entry_code(jeb))
55 return -1;
56
57 if (jump_entry_code(jea) > jump_entry_code(jeb))
58 return 1;
59
60 return 0;
61}
62
63static void jump_label_swap(void *a, void *b, int size)
64{
65 long delta = (unsigned long)a - (unsigned long)b;
66 struct jump_entry *jea = a;
67 struct jump_entry *jeb = b;
68 struct jump_entry tmp = *jea;
69
70 jea->code = jeb->code - delta;
71 jea->target = jeb->target - delta;
72 jea->key = jeb->key - delta;
73
74 jeb->code = tmp.code + delta;
75 jeb->target = tmp.target + delta;
76 jeb->key = tmp.key + delta;
77}
78
79static void
80jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
81{
82 unsigned long size;
83 void *swapfn = NULL;
84
85 if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE))
86 swapfn = jump_label_swap;
87
88 size = (((unsigned long)stop - (unsigned long)start)
89 / sizeof(struct jump_entry));
90 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn);
91}
92
93static void jump_label_update(struct static_key *key);
94
95/*
96 * There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h.
97 * The use of 'atomic_read()' requires atomic.h and its problematic for some
98 * kernel headers such as kernel.h and others. Since static_key_count() is not
99 * used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok
100 * to have it be a function here. Similarly, for 'static_key_enable()' and
101 * 'static_key_disable()', which require bug.h. This should allow jump_label.h
102 * to be included from most/all places for CONFIG_JUMP_LABEL.
103 */
104int static_key_count(struct static_key *key)
105{
106 /*
107 * -1 means the first static_key_slow_inc() is in progress.
108 * static_key_enabled() must return true, so return 1 here.
109 */
110 int n = atomic_read(&key->enabled);
111
112 return n >= 0 ? n : 1;
113}
114EXPORT_SYMBOL_GPL(static_key_count);
115
116/*
117 * static_key_fast_inc_not_disabled - adds a user for a static key
118 * @key: static key that must be already enabled
119 *
120 * The caller must make sure that the static key can't get disabled while
121 * in this function. It doesn't patch jump labels, only adds a user to
122 * an already enabled static key.
123 *
124 * Returns true if the increment was done. Unlike refcount_t the ref counter
125 * is not saturated, but will fail to increment on overflow.
126 */
127bool static_key_fast_inc_not_disabled(struct static_key *key)
128{
129 int v;
130
131 STATIC_KEY_CHECK_USE(key);
132 /*
133 * Negative key->enabled has a special meaning: it sends
134 * static_key_slow_inc/dec() down the slow path, and it is non-zero
135 * so it counts as "enabled" in jump_label_update().
136 *
137 * The INT_MAX overflow condition is either used by the networking
138 * code to reset or detected in the slow path of
139 * static_key_slow_inc_cpuslocked().
140 */
141 v = atomic_read(&key->enabled);
142 do {
143 if (v <= 0 || v == INT_MAX)
144 return false;
145 } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1)));
146
147 return true;
148}
149EXPORT_SYMBOL_GPL(static_key_fast_inc_not_disabled);
150
151bool static_key_slow_inc_cpuslocked(struct static_key *key)
152{
153 lockdep_assert_cpus_held();
154
155 /*
156 * Careful if we get concurrent static_key_slow_inc/dec() calls;
157 * later calls must wait for the first one to _finish_ the
158 * jump_label_update() process. At the same time, however,
159 * the jump_label_update() call below wants to see
160 * static_key_enabled(&key) for jumps to be updated properly.
161 */
162 if (static_key_fast_inc_not_disabled(key))
163 return true;
164
165 guard(mutex)(&jump_label_mutex);
166 /* Try to mark it as 'enabling in progress. */
167 if (!atomic_cmpxchg(&key->enabled, 0, -1)) {
168 jump_label_update(key);
169 /*
170 * Ensure that when static_key_fast_inc_not_disabled() or
171 * static_key_dec_not_one() observe the positive value,
172 * they must also observe all the text changes.
173 */
174 atomic_set_release(&key->enabled, 1);
175 } else {
176 /*
177 * While holding the mutex this should never observe
178 * anything else than a value >= 1 and succeed
179 */
180 if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key)))
181 return false;
182 }
183 return true;
184}
185
186bool static_key_slow_inc(struct static_key *key)
187{
188 bool ret;
189
190 cpus_read_lock();
191 ret = static_key_slow_inc_cpuslocked(key);
192 cpus_read_unlock();
193 return ret;
194}
195EXPORT_SYMBOL_GPL(static_key_slow_inc);
196
197void static_key_enable_cpuslocked(struct static_key *key)
198{
199 STATIC_KEY_CHECK_USE(key);
200 lockdep_assert_cpus_held();
201
202 if (atomic_read(&key->enabled) > 0) {
203 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
204 return;
205 }
206
207 jump_label_lock();
208 if (atomic_read(&key->enabled) == 0) {
209 atomic_set(&key->enabled, -1);
210 jump_label_update(key);
211 /*
212 * See static_key_slow_inc().
213 */
214 atomic_set_release(&key->enabled, 1);
215 }
216 jump_label_unlock();
217}
218EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
219
220void static_key_enable(struct static_key *key)
221{
222 cpus_read_lock();
223 static_key_enable_cpuslocked(key);
224 cpus_read_unlock();
225}
226EXPORT_SYMBOL_GPL(static_key_enable);
227
228void static_key_disable_cpuslocked(struct static_key *key)
229{
230 STATIC_KEY_CHECK_USE(key);
231 lockdep_assert_cpus_held();
232
233 if (atomic_read(&key->enabled) != 1) {
234 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
235 return;
236 }
237
238 jump_label_lock();
239 if (atomic_cmpxchg(&key->enabled, 1, 0) == 1)
240 jump_label_update(key);
241 jump_label_unlock();
242}
243EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
244
245void static_key_disable(struct static_key *key)
246{
247 cpus_read_lock();
248 static_key_disable_cpuslocked(key);
249 cpus_read_unlock();
250}
251EXPORT_SYMBOL_GPL(static_key_disable);
252
253static bool static_key_dec_not_one(struct static_key *key)
254{
255 int v;
256
257 /*
258 * Go into the slow path if key::enabled is less than or equal than
259 * one. One is valid to shut down the key, anything less than one
260 * is an imbalance, which is handled at the call site.
261 *
262 * That includes the special case of '-1' which is set in
263 * static_key_slow_inc_cpuslocked(), but that's harmless as it is
264 * fully serialized in the slow path below. By the time this task
265 * acquires the jump label lock the value is back to one and the
266 * retry under the lock must succeed.
267 */
268 v = atomic_read(&key->enabled);
269 do {
270 /*
271 * Warn about the '-1' case though; since that means a
272 * decrement is concurrent with a first (0->1) increment. IOW
273 * people are trying to disable something that wasn't yet fully
274 * enabled. This suggests an ordering problem on the user side.
275 */
276 WARN_ON_ONCE(v < 0);
277
278 /*
279 * Warn about underflow, and lie about success in an attempt to
280 * not make things worse.
281 */
282 if (WARN_ON_ONCE(v == 0))
283 return true;
284
285 if (v <= 1)
286 return false;
287 } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v - 1)));
288
289 return true;
290}
291
292static void __static_key_slow_dec_cpuslocked(struct static_key *key)
293{
294 lockdep_assert_cpus_held();
295 int val;
296
297 if (static_key_dec_not_one(key))
298 return;
299
300 guard(mutex)(&jump_label_mutex);
301 val = atomic_read(&key->enabled);
302 /*
303 * It should be impossible to observe -1 with jump_label_mutex held,
304 * see static_key_slow_inc_cpuslocked().
305 */
306 if (WARN_ON_ONCE(val == -1))
307 return;
308 /*
309 * Cannot already be 0, something went sideways.
310 */
311 if (WARN_ON_ONCE(val == 0))
312 return;
313
314 if (atomic_dec_and_test(&key->enabled))
315 jump_label_update(key);
316}
317
318static void __static_key_slow_dec(struct static_key *key)
319{
320 cpus_read_lock();
321 __static_key_slow_dec_cpuslocked(key);
322 cpus_read_unlock();
323}
324
325void jump_label_update_timeout(struct work_struct *work)
326{
327 struct static_key_deferred *key =
328 container_of(work, struct static_key_deferred, work.work);
329 __static_key_slow_dec(&key->key);
330}
331EXPORT_SYMBOL_GPL(jump_label_update_timeout);
332
333void static_key_slow_dec(struct static_key *key)
334{
335 STATIC_KEY_CHECK_USE(key);
336 __static_key_slow_dec(key);
337}
338EXPORT_SYMBOL_GPL(static_key_slow_dec);
339
340void static_key_slow_dec_cpuslocked(struct static_key *key)
341{
342 STATIC_KEY_CHECK_USE(key);
343 __static_key_slow_dec_cpuslocked(key);
344}
345
346void __static_key_slow_dec_deferred(struct static_key *key,
347 struct delayed_work *work,
348 unsigned long timeout)
349{
350 STATIC_KEY_CHECK_USE(key);
351
352 if (static_key_dec_not_one(key))
353 return;
354
355 schedule_delayed_work(work, timeout);
356}
357EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
358
359void __static_key_deferred_flush(void *key, struct delayed_work *work)
360{
361 STATIC_KEY_CHECK_USE(key);
362 flush_delayed_work(work);
363}
364EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
365
366void jump_label_rate_limit(struct static_key_deferred *key,
367 unsigned long rl)
368{
369 STATIC_KEY_CHECK_USE(key);
370 key->timeout = rl;
371 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
372}
373EXPORT_SYMBOL_GPL(jump_label_rate_limit);
374
375static int addr_conflict(struct jump_entry *entry, void *start, void *end)
376{
377 if (jump_entry_code(entry) <= (unsigned long)end &&
378 jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start)
379 return 1;
380
381 return 0;
382}
383
384static int __jump_label_text_reserved(struct jump_entry *iter_start,
385 struct jump_entry *iter_stop, void *start, void *end, bool init)
386{
387 struct jump_entry *iter;
388
389 iter = iter_start;
390 while (iter < iter_stop) {
391 if (init || !jump_entry_is_init(iter)) {
392 if (addr_conflict(iter, start, end))
393 return 1;
394 }
395 iter++;
396 }
397
398 return 0;
399}
400
401#ifndef arch_jump_label_transform_static
402static void arch_jump_label_transform_static(struct jump_entry *entry,
403 enum jump_label_type type)
404{
405 /* nothing to do on most architectures */
406}
407#endif
408
409static inline struct jump_entry *static_key_entries(struct static_key *key)
410{
411 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
412 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
413}
414
415static inline bool static_key_type(struct static_key *key)
416{
417 return key->type & JUMP_TYPE_TRUE;
418}
419
420static inline bool static_key_linked(struct static_key *key)
421{
422 return key->type & JUMP_TYPE_LINKED;
423}
424
425static inline void static_key_clear_linked(struct static_key *key)
426{
427 key->type &= ~JUMP_TYPE_LINKED;
428}
429
430static inline void static_key_set_linked(struct static_key *key)
431{
432 key->type |= JUMP_TYPE_LINKED;
433}
434
435/***
436 * A 'struct static_key' uses a union such that it either points directly
437 * to a table of 'struct jump_entry' or to a linked list of modules which in
438 * turn point to 'struct jump_entry' tables.
439 *
440 * The two lower bits of the pointer are used to keep track of which pointer
441 * type is in use and to store the initial branch direction, we use an access
442 * function which preserves these bits.
443 */
444static void static_key_set_entries(struct static_key *key,
445 struct jump_entry *entries)
446{
447 unsigned long type;
448
449 WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
450 type = key->type & JUMP_TYPE_MASK;
451 key->entries = entries;
452 key->type |= type;
453}
454
455static enum jump_label_type jump_label_type(struct jump_entry *entry)
456{
457 struct static_key *key = jump_entry_key(entry);
458 bool enabled = static_key_enabled(key);
459 bool branch = jump_entry_is_branch(entry);
460
461 /* See the comment in linux/jump_label.h */
462 return enabled ^ branch;
463}
464
465static bool jump_label_can_update(struct jump_entry *entry, bool init)
466{
467 /*
468 * Cannot update code that was in an init text area.
469 */
470 if (!init && jump_entry_is_init(entry))
471 return false;
472
473 if (!kernel_text_address(jump_entry_code(entry))) {
474 /*
475 * This skips patching built-in __exit, which
476 * is part of init_section_contains() but is
477 * not part of kernel_text_address().
478 *
479 * Skipping built-in __exit is fine since it
480 * will never be executed.
481 */
482 WARN_ONCE(!jump_entry_is_init(entry),
483 "can't patch jump_label at %pS",
484 (void *)jump_entry_code(entry));
485 return false;
486 }
487
488 return true;
489}
490
491#ifndef HAVE_JUMP_LABEL_BATCH
492static void __jump_label_update(struct static_key *key,
493 struct jump_entry *entry,
494 struct jump_entry *stop,
495 bool init)
496{
497 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
498 if (jump_label_can_update(entry, init))
499 arch_jump_label_transform(entry, jump_label_type(entry));
500 }
501}
502#else
503static void __jump_label_update(struct static_key *key,
504 struct jump_entry *entry,
505 struct jump_entry *stop,
506 bool init)
507{
508 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
509
510 if (!jump_label_can_update(entry, init))
511 continue;
512
513 if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) {
514 /*
515 * Queue is full: Apply the current queue and try again.
516 */
517 arch_jump_label_transform_apply();
518 BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry)));
519 }
520 }
521 arch_jump_label_transform_apply();
522}
523#endif
524
525void __init jump_label_init(void)
526{
527 struct jump_entry *iter_start = __start___jump_table;
528 struct jump_entry *iter_stop = __stop___jump_table;
529 struct static_key *key = NULL;
530 struct jump_entry *iter;
531
532 if (static_key_initialized)
533 return;
534
535 cpus_read_lock();
536 jump_label_lock();
537 jump_label_sort_entries(iter_start, iter_stop);
538
539 for (iter = iter_start; iter < iter_stop; iter++) {
540 struct static_key *iterk;
541 bool in_init;
542
543 /* rewrite NOPs */
544 if (jump_label_type(iter) == JUMP_LABEL_NOP)
545 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
546
547 in_init = init_section_contains((void *)jump_entry_code(iter), 1);
548 jump_entry_set_init(iter, in_init);
549
550 iterk = jump_entry_key(iter);
551 if (iterk == key)
552 continue;
553
554 key = iterk;
555 static_key_set_entries(key, iter);
556 }
557 static_key_initialized = true;
558 jump_label_unlock();
559 cpus_read_unlock();
560}
561
562static inline bool static_key_sealed(struct static_key *key)
563{
564 return (key->type & JUMP_TYPE_LINKED) && !(key->type & ~JUMP_TYPE_MASK);
565}
566
567static inline void static_key_seal(struct static_key *key)
568{
569 unsigned long type = key->type & JUMP_TYPE_TRUE;
570 key->type = JUMP_TYPE_LINKED | type;
571}
572
573void jump_label_init_ro(void)
574{
575 struct jump_entry *iter_start = __start___jump_table;
576 struct jump_entry *iter_stop = __stop___jump_table;
577 struct jump_entry *iter;
578
579 if (WARN_ON_ONCE(!static_key_initialized))
580 return;
581
582 cpus_read_lock();
583 jump_label_lock();
584
585 for (iter = iter_start; iter < iter_stop; iter++) {
586 struct static_key *iterk = jump_entry_key(iter);
587
588 if (!is_kernel_ro_after_init((unsigned long)iterk))
589 continue;
590
591 if (static_key_sealed(iterk))
592 continue;
593
594 static_key_seal(iterk);
595 }
596
597 jump_label_unlock();
598 cpus_read_unlock();
599}
600
601#ifdef CONFIG_MODULES
602
603enum jump_label_type jump_label_init_type(struct jump_entry *entry)
604{
605 struct static_key *key = jump_entry_key(entry);
606 bool type = static_key_type(key);
607 bool branch = jump_entry_is_branch(entry);
608
609 /* See the comment in linux/jump_label.h */
610 return type ^ branch;
611}
612
613struct static_key_mod {
614 struct static_key_mod *next;
615 struct jump_entry *entries;
616 struct module *mod;
617};
618
619static inline struct static_key_mod *static_key_mod(struct static_key *key)
620{
621 WARN_ON_ONCE(!static_key_linked(key));
622 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
623}
624
625/***
626 * key->type and key->next are the same via union.
627 * This sets key->next and preserves the type bits.
628 *
629 * See additional comments above static_key_set_entries().
630 */
631static void static_key_set_mod(struct static_key *key,
632 struct static_key_mod *mod)
633{
634 unsigned long type;
635
636 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
637 type = key->type & JUMP_TYPE_MASK;
638 key->next = mod;
639 key->type |= type;
640}
641
642static int __jump_label_mod_text_reserved(void *start, void *end)
643{
644 struct module *mod;
645 int ret;
646
647 scoped_guard(rcu) {
648 mod = __module_text_address((unsigned long)start);
649 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
650 if (!try_module_get(mod))
651 mod = NULL;
652 }
653 if (!mod)
654 return 0;
655
656 ret = __jump_label_text_reserved(mod->jump_entries,
657 mod->jump_entries + mod->num_jump_entries,
658 start, end, mod->state == MODULE_STATE_COMING);
659
660 module_put(mod);
661
662 return ret;
663}
664
665static void __jump_label_mod_update(struct static_key *key)
666{
667 struct static_key_mod *mod;
668
669 for (mod = static_key_mod(key); mod; mod = mod->next) {
670 struct jump_entry *stop;
671 struct module *m;
672
673 /*
674 * NULL if the static_key is defined in a module
675 * that does not use it
676 */
677 if (!mod->entries)
678 continue;
679
680 m = mod->mod;
681 if (!m)
682 stop = __stop___jump_table;
683 else
684 stop = m->jump_entries + m->num_jump_entries;
685 __jump_label_update(key, mod->entries, stop,
686 m && m->state == MODULE_STATE_COMING);
687 }
688}
689
690static int jump_label_add_module(struct module *mod)
691{
692 struct jump_entry *iter_start = mod->jump_entries;
693 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
694 struct jump_entry *iter;
695 struct static_key *key = NULL;
696 struct static_key_mod *jlm, *jlm2;
697
698 /* if the module doesn't have jump label entries, just return */
699 if (iter_start == iter_stop)
700 return 0;
701
702 jump_label_sort_entries(iter_start, iter_stop);
703
704 for (iter = iter_start; iter < iter_stop; iter++) {
705 struct static_key *iterk;
706 bool in_init;
707
708 in_init = within_module_init(jump_entry_code(iter), mod);
709 jump_entry_set_init(iter, in_init);
710
711 iterk = jump_entry_key(iter);
712 if (iterk == key)
713 continue;
714
715 key = iterk;
716 if (within_module((unsigned long)key, mod)) {
717 static_key_set_entries(key, iter);
718 continue;
719 }
720
721 /*
722 * If the key was sealed at init, then there's no need to keep a
723 * reference to its module entries - just patch them now and be
724 * done with it.
725 */
726 if (static_key_sealed(key))
727 goto do_poke;
728
729 jlm = kzalloc_obj(struct static_key_mod);
730 if (!jlm)
731 return -ENOMEM;
732 if (!static_key_linked(key)) {
733 jlm2 = kzalloc_obj(struct static_key_mod);
734 if (!jlm2) {
735 kfree(jlm);
736 return -ENOMEM;
737 }
738 scoped_guard(rcu)
739 jlm2->mod = __module_address((unsigned long)key);
740
741 jlm2->entries = static_key_entries(key);
742 jlm2->next = NULL;
743 static_key_set_mod(key, jlm2);
744 static_key_set_linked(key);
745 }
746 jlm->mod = mod;
747 jlm->entries = iter;
748 jlm->next = static_key_mod(key);
749 static_key_set_mod(key, jlm);
750 static_key_set_linked(key);
751
752 /* Only update if we've changed from our initial state */
753do_poke:
754 if (jump_label_type(iter) != jump_label_init_type(iter))
755 __jump_label_update(key, iter, iter_stop, true);
756 }
757
758 return 0;
759}
760
761static void jump_label_del_module(struct module *mod)
762{
763 struct jump_entry *iter_start = mod->jump_entries;
764 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
765 struct jump_entry *iter;
766 struct static_key *key = NULL;
767 struct static_key_mod *jlm, **prev;
768
769 for (iter = iter_start; iter < iter_stop; iter++) {
770 if (jump_entry_key(iter) == key)
771 continue;
772
773 key = jump_entry_key(iter);
774
775 if (within_module((unsigned long)key, mod))
776 continue;
777
778 /* No @jlm allocated because key was sealed at init. */
779 if (static_key_sealed(key))
780 continue;
781
782 /* No memory during module load */
783 if (WARN_ON(!static_key_linked(key)))
784 continue;
785
786 prev = &key->next;
787 jlm = static_key_mod(key);
788
789 while (jlm && jlm->mod != mod) {
790 prev = &jlm->next;
791 jlm = jlm->next;
792 }
793
794 /* No memory during module load */
795 if (WARN_ON(!jlm))
796 continue;
797
798 if (prev == &key->next)
799 static_key_set_mod(key, jlm->next);
800 else
801 *prev = jlm->next;
802
803 kfree(jlm);
804
805 jlm = static_key_mod(key);
806 /* if only one etry is left, fold it back into the static_key */
807 if (jlm->next == NULL) {
808 static_key_set_entries(key, jlm->entries);
809 static_key_clear_linked(key);
810 kfree(jlm);
811 }
812 }
813}
814
815static int
816jump_label_module_notify(struct notifier_block *self, unsigned long val,
817 void *data)
818{
819 struct module *mod = data;
820 int ret = 0;
821
822 cpus_read_lock();
823 jump_label_lock();
824
825 switch (val) {
826 case MODULE_STATE_COMING:
827 ret = jump_label_add_module(mod);
828 if (ret) {
829 WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
830 jump_label_del_module(mod);
831 }
832 break;
833 case MODULE_STATE_GOING:
834 jump_label_del_module(mod);
835 break;
836 }
837
838 jump_label_unlock();
839 cpus_read_unlock();
840
841 return notifier_from_errno(ret);
842}
843
844static struct notifier_block jump_label_module_nb = {
845 .notifier_call = jump_label_module_notify,
846 .priority = 1, /* higher than tracepoints */
847};
848
849static __init int jump_label_init_module(void)
850{
851 return register_module_notifier(&jump_label_module_nb);
852}
853early_initcall(jump_label_init_module);
854
855#endif /* CONFIG_MODULES */
856
857/***
858 * jump_label_text_reserved - check if addr range is reserved
859 * @start: start text addr
860 * @end: end text addr
861 *
862 * checks if the text addr located between @start and @end
863 * overlaps with any of the jump label patch addresses. Code
864 * that wants to modify kernel text should first verify that
865 * it does not overlap with any of the jump label addresses.
866 * Caller must hold jump_label_mutex.
867 *
868 * returns 1 if there is an overlap, 0 otherwise
869 */
870int jump_label_text_reserved(void *start, void *end)
871{
872 bool init = system_state < SYSTEM_RUNNING;
873 int ret = __jump_label_text_reserved(__start___jump_table,
874 __stop___jump_table, start, end, init);
875
876 if (ret)
877 return ret;
878
879#ifdef CONFIG_MODULES
880 ret = __jump_label_mod_text_reserved(start, end);
881#endif
882 return ret;
883}
884
885static void jump_label_update(struct static_key *key)
886{
887 struct jump_entry *stop = __stop___jump_table;
888 bool init = system_state < SYSTEM_RUNNING;
889 struct jump_entry *entry;
890#ifdef CONFIG_MODULES
891 struct module *mod;
892
893 if (static_key_linked(key)) {
894 __jump_label_mod_update(key);
895 return;
896 }
897
898 scoped_guard(rcu) {
899 mod = __module_address((unsigned long)key);
900 if (mod) {
901 stop = mod->jump_entries + mod->num_jump_entries;
902 init = mod->state == MODULE_STATE_COMING;
903 }
904 }
905#endif
906 entry = static_key_entries(key);
907 /* if there are no users, entry can be NULL */
908 if (entry)
909 __jump_label_update(key, entry, stop, init);
910}
911
912#ifdef CONFIG_STATIC_KEYS_SELFTEST
913static DEFINE_STATIC_KEY_TRUE(sk_true);
914static DEFINE_STATIC_KEY_FALSE(sk_false);
915
916static __init int jump_label_test(void)
917{
918 int i;
919
920 for (i = 0; i < 2; i++) {
921 WARN_ON(static_key_enabled(&sk_true.key) != true);
922 WARN_ON(static_key_enabled(&sk_false.key) != false);
923
924 WARN_ON(!static_branch_likely(&sk_true));
925 WARN_ON(!static_branch_unlikely(&sk_true));
926 WARN_ON(static_branch_likely(&sk_false));
927 WARN_ON(static_branch_unlikely(&sk_false));
928
929 static_branch_disable(&sk_true);
930 static_branch_enable(&sk_false);
931
932 WARN_ON(static_key_enabled(&sk_true.key) == true);
933 WARN_ON(static_key_enabled(&sk_false.key) == false);
934
935 WARN_ON(static_branch_likely(&sk_true));
936 WARN_ON(static_branch_unlikely(&sk_true));
937 WARN_ON(!static_branch_likely(&sk_false));
938 WARN_ON(!static_branch_unlikely(&sk_false));
939
940 static_branch_enable(&sk_true);
941 static_branch_disable(&sk_false);
942 }
943
944 return 0;
945}
946early_initcall(jump_label_test);
947#endif /* STATIC_KEYS_SELFTEST */