Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[sfrench/cifs-2.6.git] / kernel / jump_label.c
1 /*
2  * jump label support
3  *
4  * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
5  * Copyright (C) 2011 Peter Zijlstra
6  *
7  */
8 #include <linux/memory.h>
9 #include <linux/uaccess.h>
10 #include <linux/module.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/sort.h>
14 #include <linux/err.h>
15 #include <linux/static_key.h>
16 #include <linux/jump_label_ratelimit.h>
17 #include <linux/bug.h>
18 #include <linux/cpu.h>
19
20 #ifdef HAVE_JUMP_LABEL
21
22 /* mutex to protect coming/going of the the jump_label table */
23 static DEFINE_MUTEX(jump_label_mutex);
24
25 void jump_label_lock(void)
26 {
27         mutex_lock(&jump_label_mutex);
28 }
29
30 void jump_label_unlock(void)
31 {
32         mutex_unlock(&jump_label_mutex);
33 }
34
35 static 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         if (jea->key < jeb->key)
41                 return -1;
42
43         if (jea->key > jeb->key)
44                 return 1;
45
46         return 0;
47 }
48
49 static void
50 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
51 {
52         unsigned long size;
53
54         size = (((unsigned long)stop - (unsigned long)start)
55                                         / sizeof(struct jump_entry));
56         sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
57 }
58
59 static void jump_label_update(struct static_key *key);
60
61 /*
62  * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
63  * The use of 'atomic_read()' requires atomic.h and its problematic for some
64  * kernel headers such as kernel.h and others. Since static_key_count() is not
65  * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
66  * to have it be a function here. Similarly, for 'static_key_enable()' and
67  * 'static_key_disable()', which require bug.h. This should allow jump_label.h
68  * to be included from most/all places for HAVE_JUMP_LABEL.
69  */
70 int static_key_count(struct static_key *key)
71 {
72         /*
73          * -1 means the first static_key_slow_inc() is in progress.
74          *  static_key_enabled() must return true, so return 1 here.
75          */
76         int n = atomic_read(&key->enabled);
77
78         return n >= 0 ? n : 1;
79 }
80 EXPORT_SYMBOL_GPL(static_key_count);
81
82 static void static_key_slow_inc_cpuslocked(struct static_key *key)
83 {
84         int v, v1;
85
86         STATIC_KEY_CHECK_USE(key);
87
88         /*
89          * Careful if we get concurrent static_key_slow_inc() calls;
90          * later calls must wait for the first one to _finish_ the
91          * jump_label_update() process.  At the same time, however,
92          * the jump_label_update() call below wants to see
93          * static_key_enabled(&key) for jumps to be updated properly.
94          *
95          * So give a special meaning to negative key->enabled: it sends
96          * static_key_slow_inc() down the slow path, and it is non-zero
97          * so it counts as "enabled" in jump_label_update().  Note that
98          * atomic_inc_unless_negative() checks >= 0, so roll our own.
99          */
100         for (v = atomic_read(&key->enabled); v > 0; v = v1) {
101                 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
102                 if (likely(v1 == v))
103                         return;
104         }
105
106         jump_label_lock();
107         if (atomic_read(&key->enabled) == 0) {
108                 atomic_set(&key->enabled, -1);
109                 jump_label_update(key);
110                 /*
111                  * Ensure that if the above cmpxchg loop observes our positive
112                  * value, it must also observe all the text changes.
113                  */
114                 atomic_set_release(&key->enabled, 1);
115         } else {
116                 atomic_inc(&key->enabled);
117         }
118         jump_label_unlock();
119 }
120
121 void static_key_slow_inc(struct static_key *key)
122 {
123         cpus_read_lock();
124         static_key_slow_inc_cpuslocked(key);
125         cpus_read_unlock();
126 }
127 EXPORT_SYMBOL_GPL(static_key_slow_inc);
128
129 void static_key_enable_cpuslocked(struct static_key *key)
130 {
131         STATIC_KEY_CHECK_USE(key);
132
133         if (atomic_read(&key->enabled) > 0) {
134                 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
135                 return;
136         }
137
138         jump_label_lock();
139         if (atomic_read(&key->enabled) == 0) {
140                 atomic_set(&key->enabled, -1);
141                 jump_label_update(key);
142                 /*
143                  * See static_key_slow_inc().
144                  */
145                 atomic_set_release(&key->enabled, 1);
146         }
147         jump_label_unlock();
148 }
149 EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
150
151 void static_key_enable(struct static_key *key)
152 {
153         cpus_read_lock();
154         static_key_enable_cpuslocked(key);
155         cpus_read_unlock();
156 }
157 EXPORT_SYMBOL_GPL(static_key_enable);
158
159 void static_key_disable_cpuslocked(struct static_key *key)
160 {
161         STATIC_KEY_CHECK_USE(key);
162
163         if (atomic_read(&key->enabled) != 1) {
164                 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
165                 return;
166         }
167
168         jump_label_lock();
169         if (atomic_cmpxchg(&key->enabled, 1, 0))
170                 jump_label_update(key);
171         jump_label_unlock();
172 }
173 EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
174
175 void static_key_disable(struct static_key *key)
176 {
177         cpus_read_lock();
178         static_key_disable_cpuslocked(key);
179         cpus_read_unlock();
180 }
181 EXPORT_SYMBOL_GPL(static_key_disable);
182
183 static void static_key_slow_dec_cpuslocked(struct static_key *key,
184                                            unsigned long rate_limit,
185                                            struct delayed_work *work)
186 {
187         /*
188          * The negative count check is valid even when a negative
189          * key->enabled is in use by static_key_slow_inc(); a
190          * __static_key_slow_dec() before the first static_key_slow_inc()
191          * returns is unbalanced, because all other static_key_slow_inc()
192          * instances block while the update is in progress.
193          */
194         if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
195                 WARN(atomic_read(&key->enabled) < 0,
196                      "jump label: negative count!\n");
197                 return;
198         }
199
200         if (rate_limit) {
201                 atomic_inc(&key->enabled);
202                 schedule_delayed_work(work, rate_limit);
203         } else {
204                 jump_label_update(key);
205         }
206         jump_label_unlock();
207 }
208
209 static void __static_key_slow_dec(struct static_key *key,
210                                   unsigned long rate_limit,
211                                   struct delayed_work *work)
212 {
213         cpus_read_lock();
214         static_key_slow_dec_cpuslocked(key, rate_limit, work);
215         cpus_read_unlock();
216 }
217
218 static void jump_label_update_timeout(struct work_struct *work)
219 {
220         struct static_key_deferred *key =
221                 container_of(work, struct static_key_deferred, work.work);
222         __static_key_slow_dec(&key->key, 0, NULL);
223 }
224
225 void static_key_slow_dec(struct static_key *key)
226 {
227         STATIC_KEY_CHECK_USE(key);
228         __static_key_slow_dec(key, 0, NULL);
229 }
230 EXPORT_SYMBOL_GPL(static_key_slow_dec);
231
232 void static_key_slow_dec_deferred(struct static_key_deferred *key)
233 {
234         STATIC_KEY_CHECK_USE(key);
235         __static_key_slow_dec(&key->key, key->timeout, &key->work);
236 }
237 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
238
239 void static_key_deferred_flush(struct static_key_deferred *key)
240 {
241         STATIC_KEY_CHECK_USE(key);
242         flush_delayed_work(&key->work);
243 }
244 EXPORT_SYMBOL_GPL(static_key_deferred_flush);
245
246 void jump_label_rate_limit(struct static_key_deferred *key,
247                 unsigned long rl)
248 {
249         STATIC_KEY_CHECK_USE(key);
250         key->timeout = rl;
251         INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
252 }
253 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
254
255 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
256 {
257         if (entry->code <= (unsigned long)end &&
258                 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
259                 return 1;
260
261         return 0;
262 }
263
264 static int __jump_label_text_reserved(struct jump_entry *iter_start,
265                 struct jump_entry *iter_stop, void *start, void *end)
266 {
267         struct jump_entry *iter;
268
269         iter = iter_start;
270         while (iter < iter_stop) {
271                 if (addr_conflict(iter, start, end))
272                         return 1;
273                 iter++;
274         }
275
276         return 0;
277 }
278
279 /*
280  * Update code which is definitely not currently executing.
281  * Architectures which need heavyweight synchronization to modify
282  * running code can override this to make the non-live update case
283  * cheaper.
284  */
285 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
286                                             enum jump_label_type type)
287 {
288         arch_jump_label_transform(entry, type);
289 }
290
291 static inline struct jump_entry *static_key_entries(struct static_key *key)
292 {
293         WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
294         return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
295 }
296
297 static inline bool static_key_type(struct static_key *key)
298 {
299         return key->type & JUMP_TYPE_TRUE;
300 }
301
302 static inline bool static_key_linked(struct static_key *key)
303 {
304         return key->type & JUMP_TYPE_LINKED;
305 }
306
307 static inline void static_key_clear_linked(struct static_key *key)
308 {
309         key->type &= ~JUMP_TYPE_LINKED;
310 }
311
312 static inline void static_key_set_linked(struct static_key *key)
313 {
314         key->type |= JUMP_TYPE_LINKED;
315 }
316
317 static inline struct static_key *jump_entry_key(struct jump_entry *entry)
318 {
319         return (struct static_key *)((unsigned long)entry->key & ~1UL);
320 }
321
322 static bool jump_entry_branch(struct jump_entry *entry)
323 {
324         return (unsigned long)entry->key & 1UL;
325 }
326
327 /***
328  * A 'struct static_key' uses a union such that it either points directly
329  * to a table of 'struct jump_entry' or to a linked list of modules which in
330  * turn point to 'struct jump_entry' tables.
331  *
332  * The two lower bits of the pointer are used to keep track of which pointer
333  * type is in use and to store the initial branch direction, we use an access
334  * function which preserves these bits.
335  */
336 static void static_key_set_entries(struct static_key *key,
337                                    struct jump_entry *entries)
338 {
339         unsigned long type;
340
341         WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
342         type = key->type & JUMP_TYPE_MASK;
343         key->entries = entries;
344         key->type |= type;
345 }
346
347 static enum jump_label_type jump_label_type(struct jump_entry *entry)
348 {
349         struct static_key *key = jump_entry_key(entry);
350         bool enabled = static_key_enabled(key);
351         bool branch = jump_entry_branch(entry);
352
353         /* See the comment in linux/jump_label.h */
354         return enabled ^ branch;
355 }
356
357 static void __jump_label_update(struct static_key *key,
358                                 struct jump_entry *entry,
359                                 struct jump_entry *stop)
360 {
361         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
362                 /*
363                  * entry->code set to 0 invalidates module init text sections
364                  * kernel_text_address() verifies we are not in core kernel
365                  * init code, see jump_label_invalidate_module_init().
366                  */
367                 if (entry->code && kernel_text_address(entry->code))
368                         arch_jump_label_transform(entry, jump_label_type(entry));
369         }
370 }
371
372 void __init jump_label_init(void)
373 {
374         struct jump_entry *iter_start = __start___jump_table;
375         struct jump_entry *iter_stop = __stop___jump_table;
376         struct static_key *key = NULL;
377         struct jump_entry *iter;
378
379         /*
380          * Since we are initializing the static_key.enabled field with
381          * with the 'raw' int values (to avoid pulling in atomic.h) in
382          * jump_label.h, let's make sure that is safe. There are only two
383          * cases to check since we initialize to 0 or 1.
384          */
385         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
386         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
387
388         if (static_key_initialized)
389                 return;
390
391         cpus_read_lock();
392         jump_label_lock();
393         jump_label_sort_entries(iter_start, iter_stop);
394
395         for (iter = iter_start; iter < iter_stop; iter++) {
396                 struct static_key *iterk;
397
398                 /* rewrite NOPs */
399                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
400                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
401
402                 iterk = jump_entry_key(iter);
403                 if (iterk == key)
404                         continue;
405
406                 key = iterk;
407                 static_key_set_entries(key, iter);
408         }
409         static_key_initialized = true;
410         jump_label_unlock();
411         cpus_read_unlock();
412 }
413
414 #ifdef CONFIG_MODULES
415
416 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
417 {
418         struct static_key *key = jump_entry_key(entry);
419         bool type = static_key_type(key);
420         bool branch = jump_entry_branch(entry);
421
422         /* See the comment in linux/jump_label.h */
423         return type ^ branch;
424 }
425
426 struct static_key_mod {
427         struct static_key_mod *next;
428         struct jump_entry *entries;
429         struct module *mod;
430 };
431
432 static inline struct static_key_mod *static_key_mod(struct static_key *key)
433 {
434         WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
435         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
436 }
437
438 /***
439  * key->type and key->next are the same via union.
440  * This sets key->next and preserves the type bits.
441  *
442  * See additional comments above static_key_set_entries().
443  */
444 static void static_key_set_mod(struct static_key *key,
445                                struct static_key_mod *mod)
446 {
447         unsigned long type;
448
449         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
450         type = key->type & JUMP_TYPE_MASK;
451         key->next = mod;
452         key->type |= type;
453 }
454
455 static int __jump_label_mod_text_reserved(void *start, void *end)
456 {
457         struct module *mod;
458
459         preempt_disable();
460         mod = __module_text_address((unsigned long)start);
461         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
462         preempt_enable();
463
464         if (!mod)
465                 return 0;
466
467
468         return __jump_label_text_reserved(mod->jump_entries,
469                                 mod->jump_entries + mod->num_jump_entries,
470                                 start, end);
471 }
472
473 static void __jump_label_mod_update(struct static_key *key)
474 {
475         struct static_key_mod *mod;
476
477         for (mod = static_key_mod(key); mod; mod = mod->next) {
478                 struct jump_entry *stop;
479                 struct module *m;
480
481                 /*
482                  * NULL if the static_key is defined in a module
483                  * that does not use it
484                  */
485                 if (!mod->entries)
486                         continue;
487
488                 m = mod->mod;
489                 if (!m)
490                         stop = __stop___jump_table;
491                 else
492                         stop = m->jump_entries + m->num_jump_entries;
493                 __jump_label_update(key, mod->entries, stop);
494         }
495 }
496
497 /***
498  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
499  * @mod: module to patch
500  *
501  * Allow for run-time selection of the optimal nops. Before the module
502  * loads patch these with arch_get_jump_label_nop(), which is specified by
503  * the arch specific jump label code.
504  */
505 void jump_label_apply_nops(struct module *mod)
506 {
507         struct jump_entry *iter_start = mod->jump_entries;
508         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
509         struct jump_entry *iter;
510
511         /* if the module doesn't have jump label entries, just return */
512         if (iter_start == iter_stop)
513                 return;
514
515         for (iter = iter_start; iter < iter_stop; iter++) {
516                 /* Only write NOPs for arch_branch_static(). */
517                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
518                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
519         }
520 }
521
522 static int jump_label_add_module(struct module *mod)
523 {
524         struct jump_entry *iter_start = mod->jump_entries;
525         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
526         struct jump_entry *iter;
527         struct static_key *key = NULL;
528         struct static_key_mod *jlm, *jlm2;
529
530         /* if the module doesn't have jump label entries, just return */
531         if (iter_start == iter_stop)
532                 return 0;
533
534         jump_label_sort_entries(iter_start, iter_stop);
535
536         for (iter = iter_start; iter < iter_stop; iter++) {
537                 struct static_key *iterk;
538
539                 iterk = jump_entry_key(iter);
540                 if (iterk == key)
541                         continue;
542
543                 key = iterk;
544                 if (within_module(iter->key, mod)) {
545                         static_key_set_entries(key, iter);
546                         continue;
547                 }
548                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
549                 if (!jlm)
550                         return -ENOMEM;
551                 if (!static_key_linked(key)) {
552                         jlm2 = kzalloc(sizeof(struct static_key_mod),
553                                        GFP_KERNEL);
554                         if (!jlm2) {
555                                 kfree(jlm);
556                                 return -ENOMEM;
557                         }
558                         preempt_disable();
559                         jlm2->mod = __module_address((unsigned long)key);
560                         preempt_enable();
561                         jlm2->entries = static_key_entries(key);
562                         jlm2->next = NULL;
563                         static_key_set_mod(key, jlm2);
564                         static_key_set_linked(key);
565                 }
566                 jlm->mod = mod;
567                 jlm->entries = iter;
568                 jlm->next = static_key_mod(key);
569                 static_key_set_mod(key, jlm);
570                 static_key_set_linked(key);
571
572                 /* Only update if we've changed from our initial state */
573                 if (jump_label_type(iter) != jump_label_init_type(iter))
574                         __jump_label_update(key, iter, iter_stop);
575         }
576
577         return 0;
578 }
579
580 static void jump_label_del_module(struct module *mod)
581 {
582         struct jump_entry *iter_start = mod->jump_entries;
583         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
584         struct jump_entry *iter;
585         struct static_key *key = NULL;
586         struct static_key_mod *jlm, **prev;
587
588         for (iter = iter_start; iter < iter_stop; iter++) {
589                 if (jump_entry_key(iter) == key)
590                         continue;
591
592                 key = jump_entry_key(iter);
593
594                 if (within_module(iter->key, mod))
595                         continue;
596
597                 /* No memory during module load */
598                 if (WARN_ON(!static_key_linked(key)))
599                         continue;
600
601                 prev = &key->next;
602                 jlm = static_key_mod(key);
603
604                 while (jlm && jlm->mod != mod) {
605                         prev = &jlm->next;
606                         jlm = jlm->next;
607                 }
608
609                 /* No memory during module load */
610                 if (WARN_ON(!jlm))
611                         continue;
612
613                 if (prev == &key->next)
614                         static_key_set_mod(key, jlm->next);
615                 else
616                         *prev = jlm->next;
617
618                 kfree(jlm);
619
620                 jlm = static_key_mod(key);
621                 /* if only one etry is left, fold it back into the static_key */
622                 if (jlm->next == NULL) {
623                         static_key_set_entries(key, jlm->entries);
624                         static_key_clear_linked(key);
625                         kfree(jlm);
626                 }
627         }
628 }
629
630 static void jump_label_invalidate_module_init(struct module *mod)
631 {
632         struct jump_entry *iter_start = mod->jump_entries;
633         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
634         struct jump_entry *iter;
635
636         for (iter = iter_start; iter < iter_stop; iter++) {
637                 if (within_module_init(iter->code, mod))
638                         iter->code = 0;
639         }
640 }
641
642 static int
643 jump_label_module_notify(struct notifier_block *self, unsigned long val,
644                          void *data)
645 {
646         struct module *mod = data;
647         int ret = 0;
648
649         cpus_read_lock();
650         jump_label_lock();
651
652         switch (val) {
653         case MODULE_STATE_COMING:
654                 ret = jump_label_add_module(mod);
655                 if (ret) {
656                         WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n");
657                         jump_label_del_module(mod);
658                 }
659                 break;
660         case MODULE_STATE_GOING:
661                 jump_label_del_module(mod);
662                 break;
663         case MODULE_STATE_LIVE:
664                 jump_label_invalidate_module_init(mod);
665                 break;
666         }
667
668         jump_label_unlock();
669         cpus_read_unlock();
670
671         return notifier_from_errno(ret);
672 }
673
674 static struct notifier_block jump_label_module_nb = {
675         .notifier_call = jump_label_module_notify,
676         .priority = 1, /* higher than tracepoints */
677 };
678
679 static __init int jump_label_init_module(void)
680 {
681         return register_module_notifier(&jump_label_module_nb);
682 }
683 early_initcall(jump_label_init_module);
684
685 #endif /* CONFIG_MODULES */
686
687 /***
688  * jump_label_text_reserved - check if addr range is reserved
689  * @start: start text addr
690  * @end: end text addr
691  *
692  * checks if the text addr located between @start and @end
693  * overlaps with any of the jump label patch addresses. Code
694  * that wants to modify kernel text should first verify that
695  * it does not overlap with any of the jump label addresses.
696  * Caller must hold jump_label_mutex.
697  *
698  * returns 1 if there is an overlap, 0 otherwise
699  */
700 int jump_label_text_reserved(void *start, void *end)
701 {
702         int ret = __jump_label_text_reserved(__start___jump_table,
703                         __stop___jump_table, start, end);
704
705         if (ret)
706                 return ret;
707
708 #ifdef CONFIG_MODULES
709         ret = __jump_label_mod_text_reserved(start, end);
710 #endif
711         return ret;
712 }
713
714 static void jump_label_update(struct static_key *key)
715 {
716         struct jump_entry *stop = __stop___jump_table;
717         struct jump_entry *entry;
718 #ifdef CONFIG_MODULES
719         struct module *mod;
720
721         if (static_key_linked(key)) {
722                 __jump_label_mod_update(key);
723                 return;
724         }
725
726         preempt_disable();
727         mod = __module_address((unsigned long)key);
728         if (mod)
729                 stop = mod->jump_entries + mod->num_jump_entries;
730         preempt_enable();
731 #endif
732         entry = static_key_entries(key);
733         /* if there are no users, entry can be NULL */
734         if (entry)
735                 __jump_label_update(key, entry, stop);
736 }
737
738 #ifdef CONFIG_STATIC_KEYS_SELFTEST
739 static DEFINE_STATIC_KEY_TRUE(sk_true);
740 static DEFINE_STATIC_KEY_FALSE(sk_false);
741
742 static __init int jump_label_test(void)
743 {
744         int i;
745
746         for (i = 0; i < 2; i++) {
747                 WARN_ON(static_key_enabled(&sk_true.key) != true);
748                 WARN_ON(static_key_enabled(&sk_false.key) != false);
749
750                 WARN_ON(!static_branch_likely(&sk_true));
751                 WARN_ON(!static_branch_unlikely(&sk_true));
752                 WARN_ON(static_branch_likely(&sk_false));
753                 WARN_ON(static_branch_unlikely(&sk_false));
754
755                 static_branch_disable(&sk_true);
756                 static_branch_enable(&sk_false);
757
758                 WARN_ON(static_key_enabled(&sk_true.key) == true);
759                 WARN_ON(static_key_enabled(&sk_false.key) == false);
760
761                 WARN_ON(static_branch_likely(&sk_true));
762                 WARN_ON(static_branch_unlikely(&sk_true));
763                 WARN_ON(!static_branch_likely(&sk_false));
764                 WARN_ON(!static_branch_unlikely(&sk_false));
765
766                 static_branch_enable(&sk_true);
767                 static_branch_disable(&sk_false);
768         }
769
770         return 0;
771 }
772 late_initcall(jump_label_test);
773 #endif /* STATIC_KEYS_SELFTEST */
774
775 #endif /* HAVE_JUMP_LABEL */