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TOMOYO Linux Cross Reference
Linux/kernel/jump_label.c

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  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 #include <asm/sections.h>
 20 
 21 #ifdef HAVE_JUMP_LABEL
 22 
 23 /* mutex to protect coming/going of the the jump_label table */
 24 static DEFINE_MUTEX(jump_label_mutex);
 25 
 26 void jump_label_lock(void)
 27 {
 28         mutex_lock(&jump_label_mutex);
 29 }
 30 
 31 void jump_label_unlock(void)
 32 {
 33         mutex_unlock(&jump_label_mutex);
 34 }
 35 
 36 static int jump_label_cmp(const void *a, const void *b)
 37 {
 38         const struct jump_entry *jea = a;
 39         const struct jump_entry *jeb = b;
 40 
 41         if (jump_entry_key(jea) < jump_entry_key(jeb))
 42                 return -1;
 43 
 44         if (jump_entry_key(jea) > jump_entry_key(jeb))
 45                 return 1;
 46 
 47         return 0;
 48 }
 49 
 50 static void jump_label_swap(void *a, void *b, int size)
 51 {
 52         long delta = (unsigned long)a - (unsigned long)b;
 53         struct jump_entry *jea = a;
 54         struct jump_entry *jeb = b;
 55         struct jump_entry tmp = *jea;
 56 
 57         jea->code       = jeb->code - delta;
 58         jea->target     = jeb->target - delta;
 59         jea->key        = jeb->key - delta;
 60 
 61         jeb->code       = tmp.code + delta;
 62         jeb->target     = tmp.target + delta;
 63         jeb->key        = tmp.key + delta;
 64 }
 65 
 66 static void
 67 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
 68 {
 69         unsigned long size;
 70         void *swapfn = NULL;
 71 
 72         if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE))
 73                 swapfn = jump_label_swap;
 74 
 75         size = (((unsigned long)stop - (unsigned long)start)
 76                                         / sizeof(struct jump_entry));
 77         sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn);
 78 }
 79 
 80 static void jump_label_update(struct static_key *key);
 81 
 82 /*
 83  * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
 84  * The use of 'atomic_read()' requires atomic.h and its problematic for some
 85  * kernel headers such as kernel.h and others. Since static_key_count() is not
 86  * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
 87  * to have it be a function here. Similarly, for 'static_key_enable()' and
 88  * 'static_key_disable()', which require bug.h. This should allow jump_label.h
 89  * to be included from most/all places for HAVE_JUMP_LABEL.
 90  */
 91 int static_key_count(struct static_key *key)
 92 {
 93         /*
 94          * -1 means the first static_key_slow_inc() is in progress.
 95          *  static_key_enabled() must return true, so return 1 here.
 96          */
 97         int n = atomic_read(&key->enabled);
 98 
 99         return n >= 0 ? n : 1;
100 }
101 EXPORT_SYMBOL_GPL(static_key_count);
102 
103 void static_key_slow_inc_cpuslocked(struct static_key *key)
104 {
105         int v, v1;
106 
107         STATIC_KEY_CHECK_USE(key);
108         lockdep_assert_cpus_held();
109 
110         /*
111          * Careful if we get concurrent static_key_slow_inc() calls;
112          * later calls must wait for the first one to _finish_ the
113          * jump_label_update() process.  At the same time, however,
114          * the jump_label_update() call below wants to see
115          * static_key_enabled(&key) for jumps to be updated properly.
116          *
117          * So give a special meaning to negative key->enabled: it sends
118          * static_key_slow_inc() down the slow path, and it is non-zero
119          * so it counts as "enabled" in jump_label_update().  Note that
120          * atomic_inc_unless_negative() checks >= 0, so roll our own.
121          */
122         for (v = atomic_read(&key->enabled); v > 0; v = v1) {
123                 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
124                 if (likely(v1 == v))
125                         return;
126         }
127 
128         jump_label_lock();
129         if (atomic_read(&key->enabled) == 0) {
130                 atomic_set(&key->enabled, -1);
131                 jump_label_update(key);
132                 /*
133                  * Ensure that if the above cmpxchg loop observes our positive
134                  * value, it must also observe all the text changes.
135                  */
136                 atomic_set_release(&key->enabled, 1);
137         } else {
138                 atomic_inc(&key->enabled);
139         }
140         jump_label_unlock();
141 }
142 
143 void static_key_slow_inc(struct static_key *key)
144 {
145         cpus_read_lock();
146         static_key_slow_inc_cpuslocked(key);
147         cpus_read_unlock();
148 }
149 EXPORT_SYMBOL_GPL(static_key_slow_inc);
150 
151 void static_key_enable_cpuslocked(struct static_key *key)
152 {
153         STATIC_KEY_CHECK_USE(key);
154         lockdep_assert_cpus_held();
155 
156         if (atomic_read(&key->enabled) > 0) {
157                 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
158                 return;
159         }
160 
161         jump_label_lock();
162         if (atomic_read(&key->enabled) == 0) {
163                 atomic_set(&key->enabled, -1);
164                 jump_label_update(key);
165                 /*
166                  * See static_key_slow_inc().
167                  */
168                 atomic_set_release(&key->enabled, 1);
169         }
170         jump_label_unlock();
171 }
172 EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
173 
174 void static_key_enable(struct static_key *key)
175 {
176         cpus_read_lock();
177         static_key_enable_cpuslocked(key);
178         cpus_read_unlock();
179 }
180 EXPORT_SYMBOL_GPL(static_key_enable);
181 
182 void static_key_disable_cpuslocked(struct static_key *key)
183 {
184         STATIC_KEY_CHECK_USE(key);
185         lockdep_assert_cpus_held();
186 
187         if (atomic_read(&key->enabled) != 1) {
188                 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
189                 return;
190         }
191 
192         jump_label_lock();
193         if (atomic_cmpxchg(&key->enabled, 1, 0))
194                 jump_label_update(key);
195         jump_label_unlock();
196 }
197 EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
198 
199 void static_key_disable(struct static_key *key)
200 {
201         cpus_read_lock();
202         static_key_disable_cpuslocked(key);
203         cpus_read_unlock();
204 }
205 EXPORT_SYMBOL_GPL(static_key_disable);
206 
207 static void __static_key_slow_dec_cpuslocked(struct static_key *key,
208                                            unsigned long rate_limit,
209                                            struct delayed_work *work)
210 {
211         lockdep_assert_cpus_held();
212 
213         /*
214          * The negative count check is valid even when a negative
215          * key->enabled is in use by static_key_slow_inc(); a
216          * __static_key_slow_dec() before the first static_key_slow_inc()
217          * returns is unbalanced, because all other static_key_slow_inc()
218          * instances block while the update is in progress.
219          */
220         if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
221                 WARN(atomic_read(&key->enabled) < 0,
222                      "jump label: negative count!\n");
223                 return;
224         }
225 
226         if (rate_limit) {
227                 atomic_inc(&key->enabled);
228                 schedule_delayed_work(work, rate_limit);
229         } else {
230                 jump_label_update(key);
231         }
232         jump_label_unlock();
233 }
234 
235 static void __static_key_slow_dec(struct static_key *key,
236                                   unsigned long rate_limit,
237                                   struct delayed_work *work)
238 {
239         cpus_read_lock();
240         __static_key_slow_dec_cpuslocked(key, rate_limit, work);
241         cpus_read_unlock();
242 }
243 
244 static void jump_label_update_timeout(struct work_struct *work)
245 {
246         struct static_key_deferred *key =
247                 container_of(work, struct static_key_deferred, work.work);
248         __static_key_slow_dec(&key->key, 0, NULL);
249 }
250 
251 void static_key_slow_dec(struct static_key *key)
252 {
253         STATIC_KEY_CHECK_USE(key);
254         __static_key_slow_dec(key, 0, NULL);
255 }
256 EXPORT_SYMBOL_GPL(static_key_slow_dec);
257 
258 void static_key_slow_dec_cpuslocked(struct static_key *key)
259 {
260         STATIC_KEY_CHECK_USE(key);
261         __static_key_slow_dec_cpuslocked(key, 0, NULL);
262 }
263 
264 void static_key_slow_dec_deferred(struct static_key_deferred *key)
265 {
266         STATIC_KEY_CHECK_USE(key);
267         __static_key_slow_dec(&key->key, key->timeout, &key->work);
268 }
269 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
270 
271 void static_key_deferred_flush(struct static_key_deferred *key)
272 {
273         STATIC_KEY_CHECK_USE(key);
274         flush_delayed_work(&key->work);
275 }
276 EXPORT_SYMBOL_GPL(static_key_deferred_flush);
277 
278 void jump_label_rate_limit(struct static_key_deferred *key,
279                 unsigned long rl)
280 {
281         STATIC_KEY_CHECK_USE(key);
282         key->timeout = rl;
283         INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
284 }
285 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
286 
287 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
288 {
289         if (jump_entry_code(entry) <= (unsigned long)end &&
290             jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
291                 return 1;
292 
293         return 0;
294 }
295 
296 static int __jump_label_text_reserved(struct jump_entry *iter_start,
297                 struct jump_entry *iter_stop, void *start, void *end)
298 {
299         struct jump_entry *iter;
300 
301         iter = iter_start;
302         while (iter < iter_stop) {
303                 if (addr_conflict(iter, start, end))
304                         return 1;
305                 iter++;
306         }
307 
308         return 0;
309 }
310 
311 /*
312  * Update code which is definitely not currently executing.
313  * Architectures which need heavyweight synchronization to modify
314  * running code can override this to make the non-live update case
315  * cheaper.
316  */
317 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
318                                             enum jump_label_type type)
319 {
320         arch_jump_label_transform(entry, type);
321 }
322 
323 static inline struct jump_entry *static_key_entries(struct static_key *key)
324 {
325         WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
326         return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
327 }
328 
329 static inline bool static_key_type(struct static_key *key)
330 {
331         return key->type & JUMP_TYPE_TRUE;
332 }
333 
334 static inline bool static_key_linked(struct static_key *key)
335 {
336         return key->type & JUMP_TYPE_LINKED;
337 }
338 
339 static inline void static_key_clear_linked(struct static_key *key)
340 {
341         key->type &= ~JUMP_TYPE_LINKED;
342 }
343 
344 static inline void static_key_set_linked(struct static_key *key)
345 {
346         key->type |= JUMP_TYPE_LINKED;
347 }
348 
349 /***
350  * A 'struct static_key' uses a union such that it either points directly
351  * to a table of 'struct jump_entry' or to a linked list of modules which in
352  * turn point to 'struct jump_entry' tables.
353  *
354  * The two lower bits of the pointer are used to keep track of which pointer
355  * type is in use and to store the initial branch direction, we use an access
356  * function which preserves these bits.
357  */
358 static void static_key_set_entries(struct static_key *key,
359                                    struct jump_entry *entries)
360 {
361         unsigned long type;
362 
363         WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
364         type = key->type & JUMP_TYPE_MASK;
365         key->entries = entries;
366         key->type |= type;
367 }
368 
369 static enum jump_label_type jump_label_type(struct jump_entry *entry)
370 {
371         struct static_key *key = jump_entry_key(entry);
372         bool enabled = static_key_enabled(key);
373         bool branch = jump_entry_is_branch(entry);
374 
375         /* See the comment in linux/jump_label.h */
376         return enabled ^ branch;
377 }
378 
379 static void __jump_label_update(struct static_key *key,
380                                 struct jump_entry *entry,
381                                 struct jump_entry *stop,
382                                 bool init)
383 {
384         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
385                 /*
386                  * An entry->code of 0 indicates an entry which has been
387                  * disabled because it was in an init text area.
388                  */
389                 if (init || !jump_entry_is_init(entry)) {
390                         if (kernel_text_address(jump_entry_code(entry)))
391                                 arch_jump_label_transform(entry, jump_label_type(entry));
392                         else
393                                 WARN_ONCE(1, "can't patch jump_label at %pS",
394                                           (void *)jump_entry_code(entry));
395                 }
396         }
397 }
398 
399 void __init jump_label_init(void)
400 {
401         struct jump_entry *iter_start = __start___jump_table;
402         struct jump_entry *iter_stop = __stop___jump_table;
403         struct static_key *key = NULL;
404         struct jump_entry *iter;
405 
406         /*
407          * Since we are initializing the static_key.enabled field with
408          * with the 'raw' int values (to avoid pulling in atomic.h) in
409          * jump_label.h, let's make sure that is safe. There are only two
410          * cases to check since we initialize to 0 or 1.
411          */
412         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
413         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
414 
415         if (static_key_initialized)
416                 return;
417 
418         cpus_read_lock();
419         jump_label_lock();
420         jump_label_sort_entries(iter_start, iter_stop);
421 
422         for (iter = iter_start; iter < iter_stop; iter++) {
423                 struct static_key *iterk;
424 
425                 /* rewrite NOPs */
426                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
427                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
428 
429                 if (init_section_contains((void *)jump_entry_code(iter), 1))
430                         jump_entry_set_init(iter);
431 
432                 iterk = jump_entry_key(iter);
433                 if (iterk == key)
434                         continue;
435 
436                 key = iterk;
437                 static_key_set_entries(key, iter);
438         }
439         static_key_initialized = true;
440         jump_label_unlock();
441         cpus_read_unlock();
442 }
443 
444 #ifdef CONFIG_MODULES
445 
446 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
447 {
448         struct static_key *key = jump_entry_key(entry);
449         bool type = static_key_type(key);
450         bool branch = jump_entry_is_branch(entry);
451 
452         /* See the comment in linux/jump_label.h */
453         return type ^ branch;
454 }
455 
456 struct static_key_mod {
457         struct static_key_mod *next;
458         struct jump_entry *entries;
459         struct module *mod;
460 };
461 
462 static inline struct static_key_mod *static_key_mod(struct static_key *key)
463 {
464         WARN_ON_ONCE(!static_key_linked(key));
465         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
466 }
467 
468 /***
469  * key->type and key->next are the same via union.
470  * This sets key->next and preserves the type bits.
471  *
472  * See additional comments above static_key_set_entries().
473  */
474 static void static_key_set_mod(struct static_key *key,
475                                struct static_key_mod *mod)
476 {
477         unsigned long type;
478 
479         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
480         type = key->type & JUMP_TYPE_MASK;
481         key->next = mod;
482         key->type |= type;
483 }
484 
485 static int __jump_label_mod_text_reserved(void *start, void *end)
486 {
487         struct module *mod;
488 
489         preempt_disable();
490         mod = __module_text_address((unsigned long)start);
491         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
492         preempt_enable();
493 
494         if (!mod)
495                 return 0;
496 
497 
498         return __jump_label_text_reserved(mod->jump_entries,
499                                 mod->jump_entries + mod->num_jump_entries,
500                                 start, end);
501 }
502 
503 static void __jump_label_mod_update(struct static_key *key)
504 {
505         struct static_key_mod *mod;
506 
507         for (mod = static_key_mod(key); mod; mod = mod->next) {
508                 struct jump_entry *stop;
509                 struct module *m;
510 
511                 /*
512                  * NULL if the static_key is defined in a module
513                  * that does not use it
514                  */
515                 if (!mod->entries)
516                         continue;
517 
518                 m = mod->mod;
519                 if (!m)
520                         stop = __stop___jump_table;
521                 else
522                         stop = m->jump_entries + m->num_jump_entries;
523                 __jump_label_update(key, mod->entries, stop,
524                                     m && m->state == MODULE_STATE_COMING);
525         }
526 }
527 
528 /***
529  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
530  * @mod: module to patch
531  *
532  * Allow for run-time selection of the optimal nops. Before the module
533  * loads patch these with arch_get_jump_label_nop(), which is specified by
534  * the arch specific jump label code.
535  */
536 void jump_label_apply_nops(struct module *mod)
537 {
538         struct jump_entry *iter_start = mod->jump_entries;
539         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
540         struct jump_entry *iter;
541 
542         /* if the module doesn't have jump label entries, just return */
543         if (iter_start == iter_stop)
544                 return;
545 
546         for (iter = iter_start; iter < iter_stop; iter++) {
547                 /* Only write NOPs for arch_branch_static(). */
548                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
549                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
550         }
551 }
552 
553 static int jump_label_add_module(struct module *mod)
554 {
555         struct jump_entry *iter_start = mod->jump_entries;
556         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
557         struct jump_entry *iter;
558         struct static_key *key = NULL;
559         struct static_key_mod *jlm, *jlm2;
560 
561         /* if the module doesn't have jump label entries, just return */
562         if (iter_start == iter_stop)
563                 return 0;
564 
565         jump_label_sort_entries(iter_start, iter_stop);
566 
567         for (iter = iter_start; iter < iter_stop; iter++) {
568                 struct static_key *iterk;
569 
570                 if (within_module_init(jump_entry_code(iter), mod))
571                         jump_entry_set_init(iter);
572 
573                 iterk = jump_entry_key(iter);
574                 if (iterk == key)
575                         continue;
576 
577                 key = iterk;
578                 if (within_module((unsigned long)key, mod)) {
579                         static_key_set_entries(key, iter);
580                         continue;
581                 }
582                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
583                 if (!jlm)
584                         return -ENOMEM;
585                 if (!static_key_linked(key)) {
586                         jlm2 = kzalloc(sizeof(struct static_key_mod),
587                                        GFP_KERNEL);
588                         if (!jlm2) {
589                                 kfree(jlm);
590                                 return -ENOMEM;
591                         }
592                         preempt_disable();
593                         jlm2->mod = __module_address((unsigned long)key);
594                         preempt_enable();
595                         jlm2->entries = static_key_entries(key);
596                         jlm2->next = NULL;
597                         static_key_set_mod(key, jlm2);
598                         static_key_set_linked(key);
599                 }
600                 jlm->mod = mod;
601                 jlm->entries = iter;
602                 jlm->next = static_key_mod(key);
603                 static_key_set_mod(key, jlm);
604                 static_key_set_linked(key);
605 
606                 /* Only update if we've changed from our initial state */
607                 if (jump_label_type(iter) != jump_label_init_type(iter))
608                         __jump_label_update(key, iter, iter_stop, true);
609         }
610 
611         return 0;
612 }
613 
614 static void jump_label_del_module(struct module *mod)
615 {
616         struct jump_entry *iter_start = mod->jump_entries;
617         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
618         struct jump_entry *iter;
619         struct static_key *key = NULL;
620         struct static_key_mod *jlm, **prev;
621 
622         for (iter = iter_start; iter < iter_stop; iter++) {
623                 if (jump_entry_key(iter) == key)
624                         continue;
625 
626                 key = jump_entry_key(iter);
627 
628                 if (within_module((unsigned long)key, mod))
629                         continue;
630 
631                 /* No memory during module load */
632                 if (WARN_ON(!static_key_linked(key)))
633                         continue;
634 
635                 prev = &key->next;
636                 jlm = static_key_mod(key);
637 
638                 while (jlm && jlm->mod != mod) {
639                         prev = &jlm->next;
640                         jlm = jlm->next;
641                 }
642 
643                 /* No memory during module load */
644                 if (WARN_ON(!jlm))
645                         continue;
646 
647                 if (prev == &key->next)
648                         static_key_set_mod(key, jlm->next);
649                 else
650                         *prev = jlm->next;
651 
652                 kfree(jlm);
653 
654                 jlm = static_key_mod(key);
655                 /* if only one etry is left, fold it back into the static_key */
656                 if (jlm->next == NULL) {
657                         static_key_set_entries(key, jlm->entries);
658                         static_key_clear_linked(key);
659                         kfree(jlm);
660                 }
661         }
662 }
663 
664 static int
665 jump_label_module_notify(struct notifier_block *self, unsigned long val,
666                          void *data)
667 {
668         struct module *mod = data;
669         int ret = 0;
670 
671         cpus_read_lock();
672         jump_label_lock();
673 
674         switch (val) {
675         case MODULE_STATE_COMING:
676                 ret = jump_label_add_module(mod);
677                 if (ret) {
678                         WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
679                         jump_label_del_module(mod);
680                 }
681                 break;
682         case MODULE_STATE_GOING:
683                 jump_label_del_module(mod);
684                 break;
685         }
686 
687         jump_label_unlock();
688         cpus_read_unlock();
689 
690         return notifier_from_errno(ret);
691 }
692 
693 static struct notifier_block jump_label_module_nb = {
694         .notifier_call = jump_label_module_notify,
695         .priority = 1, /* higher than tracepoints */
696 };
697 
698 static __init int jump_label_init_module(void)
699 {
700         return register_module_notifier(&jump_label_module_nb);
701 }
702 early_initcall(jump_label_init_module);
703 
704 #endif /* CONFIG_MODULES */
705 
706 /***
707  * jump_label_text_reserved - check if addr range is reserved
708  * @start: start text addr
709  * @end: end text addr
710  *
711  * checks if the text addr located between @start and @end
712  * overlaps with any of the jump label patch addresses. Code
713  * that wants to modify kernel text should first verify that
714  * it does not overlap with any of the jump label addresses.
715  * Caller must hold jump_label_mutex.
716  *
717  * returns 1 if there is an overlap, 0 otherwise
718  */
719 int jump_label_text_reserved(void *start, void *end)
720 {
721         int ret = __jump_label_text_reserved(__start___jump_table,
722                         __stop___jump_table, start, end);
723 
724         if (ret)
725                 return ret;
726 
727 #ifdef CONFIG_MODULES
728         ret = __jump_label_mod_text_reserved(start, end);
729 #endif
730         return ret;
731 }
732 
733 static void jump_label_update(struct static_key *key)
734 {
735         struct jump_entry *stop = __stop___jump_table;
736         struct jump_entry *entry;
737 #ifdef CONFIG_MODULES
738         struct module *mod;
739 
740         if (static_key_linked(key)) {
741                 __jump_label_mod_update(key);
742                 return;
743         }
744 
745         preempt_disable();
746         mod = __module_address((unsigned long)key);
747         if (mod)
748                 stop = mod->jump_entries + mod->num_jump_entries;
749         preempt_enable();
750 #endif
751         entry = static_key_entries(key);
752         /* if there are no users, entry can be NULL */
753         if (entry)
754                 __jump_label_update(key, entry, stop,
755                                     system_state < SYSTEM_RUNNING);
756 }
757 
758 #ifdef CONFIG_STATIC_KEYS_SELFTEST
759 static DEFINE_STATIC_KEY_TRUE(sk_true);
760 static DEFINE_STATIC_KEY_FALSE(sk_false);
761 
762 static __init int jump_label_test(void)
763 {
764         int i;
765 
766         for (i = 0; i < 2; i++) {
767                 WARN_ON(static_key_enabled(&sk_true.key) != true);
768                 WARN_ON(static_key_enabled(&sk_false.key) != false);
769 
770                 WARN_ON(!static_branch_likely(&sk_true));
771                 WARN_ON(!static_branch_unlikely(&sk_true));
772                 WARN_ON(static_branch_likely(&sk_false));
773                 WARN_ON(static_branch_unlikely(&sk_false));
774 
775                 static_branch_disable(&sk_true);
776                 static_branch_enable(&sk_false);
777 
778                 WARN_ON(static_key_enabled(&sk_true.key) == true);
779                 WARN_ON(static_key_enabled(&sk_false.key) == false);
780 
781                 WARN_ON(static_branch_likely(&sk_true));
782                 WARN_ON(static_branch_unlikely(&sk_true));
783                 WARN_ON(!static_branch_likely(&sk_false));
784                 WARN_ON(!static_branch_unlikely(&sk_false));
785 
786                 static_branch_enable(&sk_true);
787                 static_branch_disable(&sk_false);
788         }
789 
790         return 0;
791 }
792 early_initcall(jump_label_test);
793 #endif /* STATIC_KEYS_SELFTEST */
794 
795 #endif /* HAVE_JUMP_LABEL */
796 

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