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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
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
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
51
52
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
97
98
99
100
101
102
103
104int static_key_count(struct static_key *key)
105{
106
107
108
109
110 int n = atomic_read(&key->enabled);
111
112 return n >= 0 ? n : 1;
113}
114EXPORT_SYMBOL_GPL(static_key_count);
115
116void static_key_slow_inc_cpuslocked(struct static_key *key)
117{
118 int v, v1;
119
120 STATIC_KEY_CHECK_USE(key);
121 lockdep_assert_cpus_held();
122
123
124
125
126
127
128
129
130
131
132
133
134
135 for (v = atomic_read(&key->enabled); v > 0; v = v1) {
136 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
137 if (likely(v1 == v))
138 return;
139 }
140
141 jump_label_lock();
142 if (atomic_read(&key->enabled) == 0) {
143 atomic_set(&key->enabled, -1);
144 jump_label_update(key);
145
146
147
148
149 atomic_set_release(&key->enabled, 1);
150 } else {
151 atomic_inc(&key->enabled);
152 }
153 jump_label_unlock();
154}
155
156void static_key_slow_inc(struct static_key *key)
157{
158 cpus_read_lock();
159 static_key_slow_inc_cpuslocked(key);
160 cpus_read_unlock();
161}
162EXPORT_SYMBOL_GPL(static_key_slow_inc);
163
164void static_key_enable_cpuslocked(struct static_key *key)
165{
166 STATIC_KEY_CHECK_USE(key);
167 lockdep_assert_cpus_held();
168
169 if (atomic_read(&key->enabled) > 0) {
170 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
171 return;
172 }
173
174 jump_label_lock();
175 if (atomic_read(&key->enabled) == 0) {
176 atomic_set(&key->enabled, -1);
177 jump_label_update(key);
178
179
180
181 atomic_set_release(&key->enabled, 1);
182 }
183 jump_label_unlock();
184}
185EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
186
187void static_key_enable(struct static_key *key)
188{
189 cpus_read_lock();
190 static_key_enable_cpuslocked(key);
191 cpus_read_unlock();
192}
193EXPORT_SYMBOL_GPL(static_key_enable);
194
195void static_key_disable_cpuslocked(struct static_key *key)
196{
197 STATIC_KEY_CHECK_USE(key);
198 lockdep_assert_cpus_held();
199
200 if (atomic_read(&key->enabled) != 1) {
201 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
202 return;
203 }
204
205 jump_label_lock();
206 if (atomic_cmpxchg(&key->enabled, 1, 0))
207 jump_label_update(key);
208 jump_label_unlock();
209}
210EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
211
212void static_key_disable(struct static_key *key)
213{
214 cpus_read_lock();
215 static_key_disable_cpuslocked(key);
216 cpus_read_unlock();
217}
218EXPORT_SYMBOL_GPL(static_key_disable);
219
220static bool static_key_slow_try_dec(struct static_key *key)
221{
222 int val;
223
224 val = atomic_fetch_add_unless(&key->enabled, -1, 1);
225 if (val == 1)
226 return false;
227
228
229
230
231
232
233
234
235 WARN(val < 0, "jump label: negative count!\n");
236 return true;
237}
238
239static void __static_key_slow_dec_cpuslocked(struct static_key *key)
240{
241 lockdep_assert_cpus_held();
242
243 if (static_key_slow_try_dec(key))
244 return;
245
246 jump_label_lock();
247 if (atomic_dec_and_test(&key->enabled))
248 jump_label_update(key);
249 jump_label_unlock();
250}
251
252static void __static_key_slow_dec(struct static_key *key)
253{
254 cpus_read_lock();
255 __static_key_slow_dec_cpuslocked(key);
256 cpus_read_unlock();
257}
258
259void jump_label_update_timeout(struct work_struct *work)
260{
261 struct static_key_deferred *key =
262 container_of(work, struct static_key_deferred, work.work);
263 __static_key_slow_dec(&key->key);
264}
265EXPORT_SYMBOL_GPL(jump_label_update_timeout);
266
267void static_key_slow_dec(struct static_key *key)
268{
269 STATIC_KEY_CHECK_USE(key);
270 __static_key_slow_dec(key);
271}
272EXPORT_SYMBOL_GPL(static_key_slow_dec);
273
274void static_key_slow_dec_cpuslocked(struct static_key *key)
275{
276 STATIC_KEY_CHECK_USE(key);
277 __static_key_slow_dec_cpuslocked(key);
278}
279
280void __static_key_slow_dec_deferred(struct static_key *key,
281 struct delayed_work *work,
282 unsigned long timeout)
283{
284 STATIC_KEY_CHECK_USE(key);
285
286 if (static_key_slow_try_dec(key))
287 return;
288
289 schedule_delayed_work(work, timeout);
290}
291EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
292
293void __static_key_deferred_flush(void *key, struct delayed_work *work)
294{
295 STATIC_KEY_CHECK_USE(key);
296 flush_delayed_work(work);
297}
298EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
299
300void jump_label_rate_limit(struct static_key_deferred *key,
301 unsigned long rl)
302{
303 STATIC_KEY_CHECK_USE(key);
304 key->timeout = rl;
305 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
306}
307EXPORT_SYMBOL_GPL(jump_label_rate_limit);
308
309static int addr_conflict(struct jump_entry *entry, void *start, void *end)
310{
311 if (jump_entry_code(entry) <= (unsigned long)end &&
312 jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
313 return 1;
314
315 return 0;
316}
317
318static int __jump_label_text_reserved(struct jump_entry *iter_start,
319 struct jump_entry *iter_stop, void *start, void *end)
320{
321 struct jump_entry *iter;
322
323 iter = iter_start;
324 while (iter < iter_stop) {
325 if (addr_conflict(iter, start, end))
326 return 1;
327 iter++;
328 }
329
330 return 0;
331}
332
333
334
335
336
337
338
339void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
340 enum jump_label_type type)
341{
342 arch_jump_label_transform(entry, type);
343}
344
345static inline struct jump_entry *static_key_entries(struct static_key *key)
346{
347 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
348 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
349}
350
351static inline bool static_key_type(struct static_key *key)
352{
353 return key->type & JUMP_TYPE_TRUE;
354}
355
356static inline bool static_key_linked(struct static_key *key)
357{
358 return key->type & JUMP_TYPE_LINKED;
359}
360
361static inline void static_key_clear_linked(struct static_key *key)
362{
363 key->type &= ~JUMP_TYPE_LINKED;
364}
365
366static inline void static_key_set_linked(struct static_key *key)
367{
368 key->type |= JUMP_TYPE_LINKED;
369}
370
371
372
373
374
375
376
377
378
379
380static void static_key_set_entries(struct static_key *key,
381 struct jump_entry *entries)
382{
383 unsigned long type;
384
385 WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
386 type = key->type & JUMP_TYPE_MASK;
387 key->entries = entries;
388 key->type |= type;
389}
390
391static enum jump_label_type jump_label_type(struct jump_entry *entry)
392{
393 struct static_key *key = jump_entry_key(entry);
394 bool enabled = static_key_enabled(key);
395 bool branch = jump_entry_is_branch(entry);
396
397
398 return enabled ^ branch;
399}
400
401static bool jump_label_can_update(struct jump_entry *entry, bool init)
402{
403
404
405
406 if (!init && jump_entry_is_init(entry))
407 return false;
408
409 if (!kernel_text_address(jump_entry_code(entry))) {
410 WARN_ONCE(1, "can't patch jump_label at %pS", (void *)jump_entry_code(entry));
411 return false;
412 }
413
414 return true;
415}
416
417#ifndef HAVE_JUMP_LABEL_BATCH
418static void __jump_label_update(struct static_key *key,
419 struct jump_entry *entry,
420 struct jump_entry *stop,
421 bool init)
422{
423 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
424 if (jump_label_can_update(entry, init))
425 arch_jump_label_transform(entry, jump_label_type(entry));
426 }
427}
428#else
429static void __jump_label_update(struct static_key *key,
430 struct jump_entry *entry,
431 struct jump_entry *stop,
432 bool init)
433{
434 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
435
436 if (!jump_label_can_update(entry, init))
437 continue;
438
439 if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) {
440
441
442
443 arch_jump_label_transform_apply();
444 BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry)));
445 }
446 }
447 arch_jump_label_transform_apply();
448}
449#endif
450
451void __init jump_label_init(void)
452{
453 struct jump_entry *iter_start = __start___jump_table;
454 struct jump_entry *iter_stop = __stop___jump_table;
455 struct static_key *key = NULL;
456 struct jump_entry *iter;
457
458
459
460
461
462
463
464 BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
465 BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
466
467 if (static_key_initialized)
468 return;
469
470 cpus_read_lock();
471 jump_label_lock();
472 jump_label_sort_entries(iter_start, iter_stop);
473
474 for (iter = iter_start; iter < iter_stop; iter++) {
475 struct static_key *iterk;
476
477
478 if (jump_label_type(iter) == JUMP_LABEL_NOP)
479 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
480
481 if (init_section_contains((void *)jump_entry_code(iter), 1))
482 jump_entry_set_init(iter);
483
484 iterk = jump_entry_key(iter);
485 if (iterk == key)
486 continue;
487
488 key = iterk;
489 static_key_set_entries(key, iter);
490 }
491 static_key_initialized = true;
492 jump_label_unlock();
493 cpus_read_unlock();
494}
495
496#ifdef CONFIG_MODULES
497
498static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
499{
500 struct static_key *key = jump_entry_key(entry);
501 bool type = static_key_type(key);
502 bool branch = jump_entry_is_branch(entry);
503
504
505 return type ^ branch;
506}
507
508struct static_key_mod {
509 struct static_key_mod *next;
510 struct jump_entry *entries;
511 struct module *mod;
512};
513
514static inline struct static_key_mod *static_key_mod(struct static_key *key)
515{
516 WARN_ON_ONCE(!static_key_linked(key));
517 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
518}
519
520
521
522
523
524
525
526static void static_key_set_mod(struct static_key *key,
527 struct static_key_mod *mod)
528{
529 unsigned long type;
530
531 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
532 type = key->type & JUMP_TYPE_MASK;
533 key->next = mod;
534 key->type |= type;
535}
536
537static int __jump_label_mod_text_reserved(void *start, void *end)
538{
539 struct module *mod;
540
541 preempt_disable();
542 mod = __module_text_address((unsigned long)start);
543 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
544 preempt_enable();
545
546 if (!mod)
547 return 0;
548
549
550 return __jump_label_text_reserved(mod->jump_entries,
551 mod->jump_entries + mod->num_jump_entries,
552 start, end);
553}
554
555static void __jump_label_mod_update(struct static_key *key)
556{
557 struct static_key_mod *mod;
558
559 for (mod = static_key_mod(key); mod; mod = mod->next) {
560 struct jump_entry *stop;
561 struct module *m;
562
563
564
565
566
567 if (!mod->entries)
568 continue;
569
570 m = mod->mod;
571 if (!m)
572 stop = __stop___jump_table;
573 else
574 stop = m->jump_entries + m->num_jump_entries;
575 __jump_label_update(key, mod->entries, stop,
576 m && m->state == MODULE_STATE_COMING);
577 }
578}
579
580
581
582
583
584
585
586
587
588void jump_label_apply_nops(struct module *mod)
589{
590 struct jump_entry *iter_start = mod->jump_entries;
591 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
592 struct jump_entry *iter;
593
594
595 if (iter_start == iter_stop)
596 return;
597
598 for (iter = iter_start; iter < iter_stop; iter++) {
599
600 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
601 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
602 }
603}
604
605static int jump_label_add_module(struct module *mod)
606{
607 struct jump_entry *iter_start = mod->jump_entries;
608 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
609 struct jump_entry *iter;
610 struct static_key *key = NULL;
611 struct static_key_mod *jlm, *jlm2;
612
613
614 if (iter_start == iter_stop)
615 return 0;
616
617 jump_label_sort_entries(iter_start, iter_stop);
618
619 for (iter = iter_start; iter < iter_stop; iter++) {
620 struct static_key *iterk;
621
622 if (within_module_init(jump_entry_code(iter), mod))
623 jump_entry_set_init(iter);
624
625 iterk = jump_entry_key(iter);
626 if (iterk == key)
627 continue;
628
629 key = iterk;
630 if (within_module((unsigned long)key, mod)) {
631 static_key_set_entries(key, iter);
632 continue;
633 }
634 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
635 if (!jlm)
636 return -ENOMEM;
637 if (!static_key_linked(key)) {
638 jlm2 = kzalloc(sizeof(struct static_key_mod),
639 GFP_KERNEL);
640 if (!jlm2) {
641 kfree(jlm);
642 return -ENOMEM;
643 }
644 preempt_disable();
645 jlm2->mod = __module_address((unsigned long)key);
646 preempt_enable();
647 jlm2->entries = static_key_entries(key);
648 jlm2->next = NULL;
649 static_key_set_mod(key, jlm2);
650 static_key_set_linked(key);
651 }
652 jlm->mod = mod;
653 jlm->entries = iter;
654 jlm->next = static_key_mod(key);
655 static_key_set_mod(key, jlm);
656 static_key_set_linked(key);
657
658
659 if (jump_label_type(iter) != jump_label_init_type(iter))
660 __jump_label_update(key, iter, iter_stop, true);
661 }
662
663 return 0;
664}
665
666static void jump_label_del_module(struct module *mod)
667{
668 struct jump_entry *iter_start = mod->jump_entries;
669 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
670 struct jump_entry *iter;
671 struct static_key *key = NULL;
672 struct static_key_mod *jlm, **prev;
673
674 for (iter = iter_start; iter < iter_stop; iter++) {
675 if (jump_entry_key(iter) == key)
676 continue;
677
678 key = jump_entry_key(iter);
679
680 if (within_module((unsigned long)key, mod))
681 continue;
682
683
684 if (WARN_ON(!static_key_linked(key)))
685 continue;
686
687 prev = &key->next;
688 jlm = static_key_mod(key);
689
690 while (jlm && jlm->mod != mod) {
691 prev = &jlm->next;
692 jlm = jlm->next;
693 }
694
695
696 if (WARN_ON(!jlm))
697 continue;
698
699 if (prev == &key->next)
700 static_key_set_mod(key, jlm->next);
701 else
702 *prev = jlm->next;
703
704 kfree(jlm);
705
706 jlm = static_key_mod(key);
707
708 if (jlm->next == NULL) {
709 static_key_set_entries(key, jlm->entries);
710 static_key_clear_linked(key);
711 kfree(jlm);
712 }
713 }
714}
715
716static int
717jump_label_module_notify(struct notifier_block *self, unsigned long val,
718 void *data)
719{
720 struct module *mod = data;
721 int ret = 0;
722
723 cpus_read_lock();
724 jump_label_lock();
725
726 switch (val) {
727 case MODULE_STATE_COMING:
728 ret = jump_label_add_module(mod);
729 if (ret) {
730 WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
731 jump_label_del_module(mod);
732 }
733 break;
734 case MODULE_STATE_GOING:
735 jump_label_del_module(mod);
736 break;
737 }
738
739 jump_label_unlock();
740 cpus_read_unlock();
741
742 return notifier_from_errno(ret);
743}
744
745static struct notifier_block jump_label_module_nb = {
746 .notifier_call = jump_label_module_notify,
747 .priority = 1,
748};
749
750static __init int jump_label_init_module(void)
751{
752 return register_module_notifier(&jump_label_module_nb);
753}
754early_initcall(jump_label_init_module);
755
756#endif
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771int jump_label_text_reserved(void *start, void *end)
772{
773 int ret = __jump_label_text_reserved(__start___jump_table,
774 __stop___jump_table, start, end);
775
776 if (ret)
777 return ret;
778
779#ifdef CONFIG_MODULES
780 ret = __jump_label_mod_text_reserved(start, end);
781#endif
782 return ret;
783}
784
785static void jump_label_update(struct static_key *key)
786{
787 struct jump_entry *stop = __stop___jump_table;
788 struct jump_entry *entry;
789#ifdef CONFIG_MODULES
790 struct module *mod;
791
792 if (static_key_linked(key)) {
793 __jump_label_mod_update(key);
794 return;
795 }
796
797 preempt_disable();
798 mod = __module_address((unsigned long)key);
799 if (mod)
800 stop = mod->jump_entries + mod->num_jump_entries;
801 preempt_enable();
802#endif
803 entry = static_key_entries(key);
804
805 if (entry)
806 __jump_label_update(key, entry, stop,
807 system_state < SYSTEM_RUNNING);
808}
809
810#ifdef CONFIG_STATIC_KEYS_SELFTEST
811static DEFINE_STATIC_KEY_TRUE(sk_true);
812static DEFINE_STATIC_KEY_FALSE(sk_false);
813
814static __init int jump_label_test(void)
815{
816 int i;
817
818 for (i = 0; i < 2; i++) {
819 WARN_ON(static_key_enabled(&sk_true.key) != true);
820 WARN_ON(static_key_enabled(&sk_false.key) != false);
821
822 WARN_ON(!static_branch_likely(&sk_true));
823 WARN_ON(!static_branch_unlikely(&sk_true));
824 WARN_ON(static_branch_likely(&sk_false));
825 WARN_ON(static_branch_unlikely(&sk_false));
826
827 static_branch_disable(&sk_true);
828 static_branch_enable(&sk_false);
829
830 WARN_ON(static_key_enabled(&sk_true.key) == true);
831 WARN_ON(static_key_enabled(&sk_false.key) == false);
832
833 WARN_ON(static_branch_likely(&sk_true));
834 WARN_ON(static_branch_unlikely(&sk_true));
835 WARN_ON(!static_branch_likely(&sk_false));
836 WARN_ON(!static_branch_unlikely(&sk_false));
837
838 static_branch_enable(&sk_true);
839 static_branch_disable(&sk_false);
840 }
841
842 return 0;
843}
844early_initcall(jump_label_test);
845#endif
846