summaryrefslogtreecommitdiff
path: root/kernel/jump_label.c
blob: e7214093dcd143e61325956064c5f84d772aa110 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
/*
 * jump label support
 *
 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
 * Copyright (C) 2011 Peter Zijlstra
 *
 */
#include <linux/memory.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/err.h>
#include <linux/static_key.h>
#include <linux/jump_label_ratelimit.h>
#include <linux/bug.h>
#include <linux/cpu.h>

#ifdef HAVE_JUMP_LABEL

/* mutex to protect coming/going of the the jump_label table */
static DEFINE_MUTEX(jump_label_mutex);

void jump_label_lock(void)
{
	mutex_lock(&jump_label_mutex);
}

void jump_label_unlock(void)
{
	mutex_unlock(&jump_label_mutex);
}

static int jump_label_cmp(const void *a, const void *b)
{
	const struct jump_entry *jea = a;
	const struct jump_entry *jeb = b;

	if (jea->key < jeb->key)
		return -1;

	if (jea->key > jeb->key)
		return 1;

	return 0;
}

static void
jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
{
	unsigned long size;

	size = (((unsigned long)stop - (unsigned long)start)
					/ sizeof(struct jump_entry));
	sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
}

static void jump_label_update(struct static_key *key);

/*
 * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
 * The use of 'atomic_read()' requires atomic.h and its problematic for some
 * kernel headers such as kernel.h and others. Since static_key_count() is not
 * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
 * to have it be a function here. Similarly, for 'static_key_enable()' and
 * 'static_key_disable()', which require bug.h. This should allow jump_label.h
 * to be included from most/all places for HAVE_JUMP_LABEL.
 */
int static_key_count(struct static_key *key)
{
	/*
	 * -1 means the first static_key_slow_inc() is in progress.
	 *  static_key_enabled() must return true, so return 1 here.
	 */
	int n = atomic_read(&key->enabled);

	return n >= 0 ? n : 1;
}
EXPORT_SYMBOL_GPL(static_key_count);

void static_key_slow_inc_cpuslocked(struct static_key *key)
{
	int v, v1;

	STATIC_KEY_CHECK_USE(key);

	/*
	 * Careful if we get concurrent static_key_slow_inc() calls;
	 * later calls must wait for the first one to _finish_ the
	 * jump_label_update() process.  At the same time, however,
	 * the jump_label_update() call below wants to see
	 * static_key_enabled(&key) for jumps to be updated properly.
	 *
	 * So give a special meaning to negative key->enabled: it sends
	 * static_key_slow_inc() down the slow path, and it is non-zero
	 * so it counts as "enabled" in jump_label_update().  Note that
	 * atomic_inc_unless_negative() checks >= 0, so roll our own.
	 */
	for (v = atomic_read(&key->enabled); v > 0; v = v1) {
		v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
		if (likely(v1 == v))
			return;
	}

	jump_label_lock();
	if (atomic_read(&key->enabled) == 0) {
		atomic_set(&key->enabled, -1);
		jump_label_update(key);
		/*
		 * Ensure that if the above cmpxchg loop observes our positive
		 * value, it must also observe all the text changes.
		 */
		atomic_set_release(&key->enabled, 1);
	} else {
		atomic_inc(&key->enabled);
	}
	jump_label_unlock();
}

void static_key_slow_inc(struct static_key *key)
{
	cpus_read_lock();
	static_key_slow_inc_cpuslocked(key);
	cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(static_key_slow_inc);

void static_key_enable_cpuslocked(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);

	if (atomic_read(&key->enabled) > 0) {
		WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
		return;
	}

	jump_label_lock();
	if (atomic_read(&key->enabled) == 0) {
		atomic_set(&key->enabled, -1);
		jump_label_update(key);
		/*
		 * See static_key_slow_inc().
		 */
		atomic_set_release(&key->enabled, 1);
	}
	jump_label_unlock();
}
EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);

void static_key_enable(struct static_key *key)
{
	cpus_read_lock();
	static_key_enable_cpuslocked(key);
	cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(static_key_enable);

void static_key_disable_cpuslocked(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);

	if (atomic_read(&key->enabled) != 1) {
		WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
		return;
	}

	jump_label_lock();
	if (atomic_cmpxchg(&key->enabled, 1, 0))
		jump_label_update(key);
	jump_label_unlock();
}
EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);

void static_key_disable(struct static_key *key)
{
	cpus_read_lock();
	static_key_disable_cpuslocked(key);
	cpus_read_unlock();
}
EXPORT_SYMBOL_GPL(static_key_disable);

static void __static_key_slow_dec_cpuslocked(struct static_key *key,
					   unsigned long rate_limit,
					   struct delayed_work *work)
{
	/*
	 * The negative count check is valid even when a negative
	 * key->enabled is in use by static_key_slow_inc(); a
	 * __static_key_slow_dec() before the first static_key_slow_inc()
	 * returns is unbalanced, because all other static_key_slow_inc()
	 * instances block while the update is in progress.
	 */
	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
		WARN(atomic_read(&key->enabled) < 0,
		     "jump label: negative count!\n");
		return;
	}

	if (rate_limit) {
		atomic_inc(&key->enabled);
		schedule_delayed_work(work, rate_limit);
	} else {
		jump_label_update(key);
	}
	jump_label_unlock();
}

static void __static_key_slow_dec(struct static_key *key,
				  unsigned long rate_limit,
				  struct delayed_work *work)
{
	cpus_read_lock();
	__static_key_slow_dec_cpuslocked(key, rate_limit, work);
	cpus_read_unlock();
}

static void jump_label_update_timeout(struct work_struct *work)
{
	struct static_key_deferred *key =
		container_of(work, struct static_key_deferred, work.work);
	__static_key_slow_dec(&key->key, 0, NULL);
}

void static_key_slow_dec(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);
	__static_key_slow_dec(key, 0, NULL);
}
EXPORT_SYMBOL_GPL(static_key_slow_dec);

void static_key_slow_dec_cpuslocked(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);
	__static_key_slow_dec_cpuslocked(key, 0, NULL);
}

void static_key_slow_dec_deferred(struct static_key_deferred *key)
{
	STATIC_KEY_CHECK_USE(key);
	__static_key_slow_dec(&key->key, key->timeout, &key->work);
}
EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);

void static_key_deferred_flush(struct static_key_deferred *key)
{
	STATIC_KEY_CHECK_USE(key);
	flush_delayed_work(&key->work);
}
EXPORT_SYMBOL_GPL(static_key_deferred_flush);

void jump_label_rate_limit(struct static_key_deferred *key,
		unsigned long rl)
{
	STATIC_KEY_CHECK_USE(key);
	key->timeout = rl;
	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
}
EXPORT_SYMBOL_GPL(jump_label_rate_limit);

static int addr_conflict(struct jump_entry *entry, void *start, void *end)
{
	if (entry->code <= (unsigned long)end &&
		entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
		return 1;

	return 0;
}

static int __jump_label_text_reserved(struct jump_entry *iter_start,
		struct jump_entry *iter_stop, void *start, void *end)
{
	struct jump_entry *iter;

	iter = iter_start;
	while (iter < iter_stop) {
		if (addr_conflict(iter, start, end))
			return 1;
		iter++;
	}

	return 0;
}

/*
 * Update code which is definitely not currently executing.
 * Architectures which need heavyweight synchronization to modify
 * running code can override this to make the non-live update case
 * cheaper.
 */
void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
					    enum jump_label_type type)
{
	arch_jump_label_transform(entry, type);
}

static inline struct jump_entry *static_key_entries(struct static_key *key)
{
	WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
	return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
}

static inline bool static_key_type(struct static_key *key)
{
	return key->type & JUMP_TYPE_TRUE;
}

static inline bool static_key_linked(struct static_key *key)
{
	return key->type & JUMP_TYPE_LINKED;
}

static inline void static_key_clear_linked(struct static_key *key)
{
	key->type &= ~JUMP_TYPE_LINKED;
}

static inline void static_key_set_linked(struct static_key *key)
{
	key->type |= JUMP_TYPE_LINKED;
}

static inline struct static_key *jump_entry_key(struct jump_entry *entry)
{
	return (struct static_key *)((unsigned long)entry->key & ~1UL);
}

static bool jump_entry_branch(struct jump_entry *entry)
{
	return (unsigned long)entry->key & 1UL;
}

/***
 * A 'struct static_key' uses a union such that it either points directly
 * to a table of 'struct jump_entry' or to a linked list of modules which in
 * turn point to 'struct jump_entry' tables.
 *
 * The two lower bits of the pointer are used to keep track of which pointer
 * type is in use and to store the initial branch direction, we use an access
 * function which preserves these bits.
 */
static void static_key_set_entries(struct static_key *key,
				   struct jump_entry *entries)
{
	unsigned long type;

	WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
	type = key->type & JUMP_TYPE_MASK;
	key->entries = entries;
	key->type |= type;
}

static enum jump_label_type jump_label_type(struct jump_entry *entry)
{
	struct static_key *key = jump_entry_key(entry);
	bool enabled = static_key_enabled(key);
	bool branch = jump_entry_branch(entry);

	/* See the comment in linux/jump_label.h */
	return enabled ^ branch;
}

static void __jump_label_update(struct static_key *key,
				struct jump_entry *entry,
				struct jump_entry *stop)
{
	for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
		/*
		 * An entry->code of 0 indicates an entry which has been
		 * disabled because it was in an init text area.
		 */
		if (entry->code) {
			if (kernel_text_address(entry->code))
				arch_jump_label_transform(entry, jump_label_type(entry));
			else
				WARN_ONCE(1, "can't patch jump_label at %pS",
					  (void *)(unsigned long)entry->code);
		}
	}
}

void __init jump_label_init(void)
{
	struct jump_entry *iter_start = __start___jump_table;
	struct jump_entry *iter_stop = __stop___jump_table;
	struct static_key *key = NULL;
	struct jump_entry *iter;

	/*
	 * Since we are initializing the static_key.enabled field with
	 * with the 'raw' int values (to avoid pulling in atomic.h) in
	 * jump_label.h, let's make sure that is safe. There are only two
	 * cases to check since we initialize to 0 or 1.
	 */
	BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
	BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);

	if (static_key_initialized)
		return;

	cpus_read_lock();
	jump_label_lock();
	jump_label_sort_entries(iter_start, iter_stop);

	for (iter = iter_start; iter < iter_stop; iter++) {
		struct static_key *iterk;

		/* rewrite NOPs */
		if (jump_label_type(iter) == JUMP_LABEL_NOP)
			arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);

		iterk = jump_entry_key(iter);
		if (iterk == key)
			continue;

		key = iterk;
		static_key_set_entries(key, iter);
	}
	static_key_initialized = true;
	jump_label_unlock();
	cpus_read_unlock();
}

/* Disable any jump label entries in __init code */
void __init jump_label_invalidate_init(void)
{
	struct jump_entry *iter_start = __start___jump_table;
	struct jump_entry *iter_stop = __stop___jump_table;
	struct jump_entry *iter;

	for (iter = iter_start; iter < iter_stop; iter++) {
		if (init_kernel_text(iter->code))
			iter->code = 0;
	}
}

#ifdef CONFIG_MODULES

static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
{
	struct static_key *key = jump_entry_key(entry);
	bool type = static_key_type(key);
	bool branch = jump_entry_branch(entry);

	/* See the comment in linux/jump_label.h */
	return type ^ branch;
}

struct static_key_mod {
	struct static_key_mod *next;
	struct jump_entry *entries;
	struct module *mod;
};

static inline struct static_key_mod *static_key_mod(struct static_key *key)
{
	WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
	return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
}

/***
 * key->type and key->next are the same via union.
 * This sets key->next and preserves the type bits.
 *
 * See additional comments above static_key_set_entries().
 */
static void static_key_set_mod(struct static_key *key,
			       struct static_key_mod *mod)
{
	unsigned long type;

	WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
	type = key->type & JUMP_TYPE_MASK;
	key->next = mod;
	key->type |= type;
}

static int __jump_label_mod_text_reserved(void *start, void *end)
{
	struct module *mod;

	preempt_disable();
	mod = __module_text_address((unsigned long)start);
	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
	preempt_enable();

	if (!mod)
		return 0;


	return __jump_label_text_reserved(mod->jump_entries,
				mod->jump_entries + mod->num_jump_entries,
				start, end);
}

static void __jump_label_mod_update(struct static_key *key)
{
	struct static_key_mod *mod;

	for (mod = static_key_mod(key); mod; mod = mod->next) {
		struct jump_entry *stop;
		struct module *m;

		/*
		 * NULL if the static_key is defined in a module
		 * that does not use it
		 */
		if (!mod->entries)
			continue;

		m = mod->mod;
		if (!m)
			stop = __stop___jump_table;
		else
			stop = m->jump_entries + m->num_jump_entries;
		__jump_label_update(key, mod->entries, stop);
	}
}

/***
 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
 * @mod: module to patch
 *
 * Allow for run-time selection of the optimal nops. Before the module
 * loads patch these with arch_get_jump_label_nop(), which is specified by
 * the arch specific jump label code.
 */
void jump_label_apply_nops(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;

	/* if the module doesn't have jump label entries, just return */
	if (iter_start == iter_stop)
		return;

	for (iter = iter_start; iter < iter_stop; iter++) {
		/* Only write NOPs for arch_branch_static(). */
		if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
			arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
	}
}

static int jump_label_add_module(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;
	struct static_key *key = NULL;
	struct static_key_mod *jlm, *jlm2;

	/* if the module doesn't have jump label entries, just return */
	if (iter_start == iter_stop)
		return 0;

	jump_label_sort_entries(iter_start, iter_stop);

	for (iter = iter_start; iter < iter_stop; iter++) {
		struct static_key *iterk;

		iterk = jump_entry_key(iter);
		if (iterk == key)
			continue;

		key = iterk;
		if (within_module(iter->key, mod)) {
			static_key_set_entries(key, iter);
			continue;
		}
		jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
		if (!jlm)
			return -ENOMEM;
		if (!static_key_linked(key)) {
			jlm2 = kzalloc(sizeof(struct static_key_mod),
				       GFP_KERNEL);
			if (!jlm2) {
				kfree(jlm);
				return -ENOMEM;
			}
			preempt_disable();
			jlm2->mod = __module_address((unsigned long)key);
			preempt_enable();
			jlm2->entries = static_key_entries(key);
			jlm2->next = NULL;
			static_key_set_mod(key, jlm2);
			static_key_set_linked(key);
		}
		jlm->mod = mod;
		jlm->entries = iter;
		jlm->next = static_key_mod(key);
		static_key_set_mod(key, jlm);
		static_key_set_linked(key);

		/* Only update if we've changed from our initial state */
		if (jump_label_type(iter) != jump_label_init_type(iter))
			__jump_label_update(key, iter, iter_stop);
	}

	return 0;
}

static void jump_label_del_module(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;
	struct static_key *key = NULL;
	struct static_key_mod *jlm, **prev;

	for (iter = iter_start; iter < iter_stop; iter++) {
		if (jump_entry_key(iter) == key)
			continue;

		key = jump_entry_key(iter);

		if (within_module(iter->key, mod))
			continue;

		/* No memory during module load */
		if (WARN_ON(!static_key_linked(key)))
			continue;

		prev = &key->next;
		jlm = static_key_mod(key);

		while (jlm && jlm->mod != mod) {
			prev = &jlm->next;
			jlm = jlm->next;
		}

		/* No memory during module load */
		if (WARN_ON(!jlm))
			continue;

		if (prev == &key->next)
			static_key_set_mod(key, jlm->next);
		else
			*prev = jlm->next;

		kfree(jlm);

		jlm = static_key_mod(key);
		/* if only one etry is left, fold it back into the static_key */
		if (jlm->next == NULL) {
			static_key_set_entries(key, jlm->entries);
			static_key_clear_linked(key);
			kfree(jlm);
		}
	}
}

/* Disable any jump label entries in module init code */
static void jump_label_invalidate_module_init(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;

	for (iter = iter_start; iter < iter_stop; iter++) {
		if (within_module_init(iter->code, mod))
			iter->code = 0;
	}
}

static int
jump_label_module_notify(struct notifier_block *self, unsigned long val,
			 void *data)
{
	struct module *mod = data;
	int ret = 0;

	cpus_read_lock();
	jump_label_lock();

	switch (val) {
	case MODULE_STATE_COMING:
		ret = jump_label_add_module(mod);
		if (ret) {
			WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
			jump_label_del_module(mod);
		}
		break;
	case MODULE_STATE_GOING:
		jump_label_del_module(mod);
		break;
	case MODULE_STATE_LIVE:
		jump_label_invalidate_module_init(mod);
		break;
	}

	jump_label_unlock();
	cpus_read_unlock();

	return notifier_from_errno(ret);
}

static struct notifier_block jump_label_module_nb = {
	.notifier_call = jump_label_module_notify,
	.priority = 1, /* higher than tracepoints */
};

static __init int jump_label_init_module(void)
{
	return register_module_notifier(&jump_label_module_nb);
}
early_initcall(jump_label_init_module);

#endif /* CONFIG_MODULES */

/***
 * jump_label_text_reserved - check if addr range is reserved
 * @start: start text addr
 * @end: end text addr
 *
 * checks if the text addr located between @start and @end
 * overlaps with any of the jump label patch addresses. Code
 * that wants to modify kernel text should first verify that
 * it does not overlap with any of the jump label addresses.
 * Caller must hold jump_label_mutex.
 *
 * returns 1 if there is an overlap, 0 otherwise
 */
int jump_label_text_reserved(void *start, void *end)
{
	int ret = __jump_label_text_reserved(__start___jump_table,
			__stop___jump_table, start, end);

	if (ret)
		return ret;

#ifdef CONFIG_MODULES
	ret = __jump_label_mod_text_reserved(start, end);
#endif
	return ret;
}

static void jump_label_update(struct static_key *key)
{
	struct jump_entry *stop = __stop___jump_table;
	struct jump_entry *entry;
#ifdef CONFIG_MODULES
	struct module *mod;

	if (static_key_linked(key)) {
		__jump_label_mod_update(key);
		return;
	}

	preempt_disable();
	mod = __module_address((unsigned long)key);
	if (mod)
		stop = mod->jump_entries + mod->num_jump_entries;
	preempt_enable();
#endif
	entry = static_key_entries(key);
	/* if there are no users, entry can be NULL */
	if (entry)
		__jump_label_update(key, entry, stop);
}

#ifdef CONFIG_STATIC_KEYS_SELFTEST
static DEFINE_STATIC_KEY_TRUE(sk_true);
static DEFINE_STATIC_KEY_FALSE(sk_false);

static __init int jump_label_test(void)
{
	int i;

	for (i = 0; i < 2; i++) {
		WARN_ON(static_key_enabled(&sk_true.key) != true);
		WARN_ON(static_key_enabled(&sk_false.key) != false);

		WARN_ON(!static_branch_likely(&sk_true));
		WARN_ON(!static_branch_unlikely(&sk_true));
		WARN_ON(static_branch_likely(&sk_false));
		WARN_ON(static_branch_unlikely(&sk_false));

		static_branch_disable(&sk_true);
		static_branch_enable(&sk_false);

		WARN_ON(static_key_enabled(&sk_true.key) == true);
		WARN_ON(static_key_enabled(&sk_false.key) == false);

		WARN_ON(static_branch_likely(&sk_true));
		WARN_ON(static_branch_unlikely(&sk_true));
		WARN_ON(!static_branch_likely(&sk_false));
		WARN_ON(!static_branch_unlikely(&sk_false));

		static_branch_enable(&sk_true);
		static_branch_disable(&sk_false);
	}

	return 0;
}
early_initcall(jump_label_test);
#endif /* STATIC_KEYS_SELFTEST */

#endif /* HAVE_JUMP_LABEL */