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[tomoyo/tomoyo-test1.git] / kernel / jump_label.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * jump label support
4  *
5  * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
6  * Copyright (C) 2011 Peter Zijlstra
7  *
8  */
9 #include <linux/memory.h>
10 #include <linux/uaccess.h>
11 #include <linux/module.h>
12 #include <linux/list.h>
13 #include <linux/slab.h>
14 #include <linux/sort.h>
15 #include <linux/err.h>
16 #include <linux/static_key.h>
17 #include <linux/jump_label_ratelimit.h>
18 #include <linux/bug.h>
19 #include <linux/cpu.h>
20 #include <asm/sections.h>
21
22 /* mutex to protect coming/going of the 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         /*
41          * Entrires are sorted by key.
42          */
43         if (jump_entry_key(jea) < jump_entry_key(jeb))
44                 return -1;
45
46         if (jump_entry_key(jea) > jump_entry_key(jeb))
47                 return 1;
48
49         /*
50          * In the batching mode, entries should also be sorted by the code
51          * inside the already sorted list of entries, enabling a bsearch in
52          * the vector.
53          */
54         if (jump_entry_code(jea) < jump_entry_code(jeb))
55                 return -1;
56
57         if (jump_entry_code(jea) > jump_entry_code(jeb))
58                 return 1;
59
60         return 0;
61 }
62
63 static 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
79 static void
80 jump_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
93 static void jump_label_update(struct static_key *key);
94
95 /*
96  * There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h.
97  * The use of 'atomic_read()' requires atomic.h and its problematic for some
98  * kernel headers such as kernel.h and others. Since static_key_count() is not
99  * used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok
100  * to have it be a function here. Similarly, for 'static_key_enable()' and
101  * 'static_key_disable()', which require bug.h. This should allow jump_label.h
102  * to be included from most/all places for CONFIG_JUMP_LABEL.
103  */
104 int static_key_count(struct static_key *key)
105 {
106         /*
107          * -1 means the first static_key_slow_inc() is in progress.
108          *  static_key_enabled() must return true, so return 1 here.
109          */
110         int n = atomic_read(&key->enabled);
111
112         return n >= 0 ? n : 1;
113 }
114 EXPORT_SYMBOL_GPL(static_key_count);
115
116 void 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          * Careful if we get concurrent static_key_slow_inc() calls;
125          * later calls must wait for the first one to _finish_ the
126          * jump_label_update() process.  At the same time, however,
127          * the jump_label_update() call below wants to see
128          * static_key_enabled(&key) for jumps to be updated properly.
129          *
130          * So give a special meaning to negative key->enabled: it sends
131          * static_key_slow_inc() down the slow path, and it is non-zero
132          * so it counts as "enabled" in jump_label_update().  Note that
133          * atomic_inc_unless_negative() checks >= 0, so roll our own.
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                  * Ensure that if the above cmpxchg loop observes our positive
147                  * value, it must also observe all the text changes.
148                  */
149                 atomic_set_release(&key->enabled, 1);
150         } else {
151                 atomic_inc(&key->enabled);
152         }
153         jump_label_unlock();
154 }
155
156 void 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 }
162 EXPORT_SYMBOL_GPL(static_key_slow_inc);
163
164 void 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                  * See static_key_slow_inc().
180                  */
181                 atomic_set_release(&key->enabled, 1);
182         }
183         jump_label_unlock();
184 }
185 EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
186
187 void static_key_enable(struct static_key *key)
188 {
189         cpus_read_lock();
190         static_key_enable_cpuslocked(key);
191         cpus_read_unlock();
192 }
193 EXPORT_SYMBOL_GPL(static_key_enable);
194
195 void 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 }
210 EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
211
212 void static_key_disable(struct static_key *key)
213 {
214         cpus_read_lock();
215         static_key_disable_cpuslocked(key);
216         cpus_read_unlock();
217 }
218 EXPORT_SYMBOL_GPL(static_key_disable);
219
220 static 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          * The negative count check is valid even when a negative
230          * key->enabled is in use by static_key_slow_inc(); a
231          * __static_key_slow_dec() before the first static_key_slow_inc()
232          * returns is unbalanced, because all other static_key_slow_inc()
233          * instances block while the update is in progress.
234          */
235         WARN(val < 0, "jump label: negative count!\n");
236         return true;
237 }
238
239 static 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
252 static 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
259 void 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 }
265 EXPORT_SYMBOL_GPL(jump_label_update_timeout);
266
267 void static_key_slow_dec(struct static_key *key)
268 {
269         STATIC_KEY_CHECK_USE(key);
270         __static_key_slow_dec(key);
271 }
272 EXPORT_SYMBOL_GPL(static_key_slow_dec);
273
274 void 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
280 void __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 }
291 EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
292
293 void __static_key_deferred_flush(void *key, struct delayed_work *work)
294 {
295         STATIC_KEY_CHECK_USE(key);
296         flush_delayed_work(work);
297 }
298 EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
299
300 void 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 }
307 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
308
309 static 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
318 static 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  * Update code which is definitely not currently executing.
335  * Architectures which need heavyweight synchronization to modify
336  * running code can override this to make the non-live update case
337  * cheaper.
338  */
339 void __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
345 static 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
351 static inline bool static_key_type(struct static_key *key)
352 {
353         return key->type & JUMP_TYPE_TRUE;
354 }
355
356 static inline bool static_key_linked(struct static_key *key)
357 {
358         return key->type & JUMP_TYPE_LINKED;
359 }
360
361 static inline void static_key_clear_linked(struct static_key *key)
362 {
363         key->type &= ~JUMP_TYPE_LINKED;
364 }
365
366 static inline void static_key_set_linked(struct static_key *key)
367 {
368         key->type |= JUMP_TYPE_LINKED;
369 }
370
371 /***
372  * A 'struct static_key' uses a union such that it either points directly
373  * to a table of 'struct jump_entry' or to a linked list of modules which in
374  * turn point to 'struct jump_entry' tables.
375  *
376  * The two lower bits of the pointer are used to keep track of which pointer
377  * type is in use and to store the initial branch direction, we use an access
378  * function which preserves these bits.
379  */
380 static 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
391 static 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         /* See the comment in linux/jump_label.h */
398         return enabled ^ branch;
399 }
400
401 static bool jump_label_can_update(struct jump_entry *entry, bool init)
402 {
403         /*
404          * Cannot update code that was in an init text area.
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(!jump_entry_is_init(entry),
411                           "can't patch jump_label at %pS",
412                           (void *)jump_entry_code(entry));
413                 return false;
414         }
415
416         return true;
417 }
418
419 #ifndef HAVE_JUMP_LABEL_BATCH
420 static void __jump_label_update(struct static_key *key,
421                                 struct jump_entry *entry,
422                                 struct jump_entry *stop,
423                                 bool init)
424 {
425         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
426                 if (jump_label_can_update(entry, init))
427                         arch_jump_label_transform(entry, jump_label_type(entry));
428         }
429 }
430 #else
431 static void __jump_label_update(struct static_key *key,
432                                 struct jump_entry *entry,
433                                 struct jump_entry *stop,
434                                 bool init)
435 {
436         for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
437
438                 if (!jump_label_can_update(entry, init))
439                         continue;
440
441                 if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) {
442                         /*
443                          * Queue is full: Apply the current queue and try again.
444                          */
445                         arch_jump_label_transform_apply();
446                         BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry)));
447                 }
448         }
449         arch_jump_label_transform_apply();
450 }
451 #endif
452
453 void __init jump_label_init(void)
454 {
455         struct jump_entry *iter_start = __start___jump_table;
456         struct jump_entry *iter_stop = __stop___jump_table;
457         struct static_key *key = NULL;
458         struct jump_entry *iter;
459
460         /*
461          * Since we are initializing the static_key.enabled field with
462          * with the 'raw' int values (to avoid pulling in atomic.h) in
463          * jump_label.h, let's make sure that is safe. There are only two
464          * cases to check since we initialize to 0 or 1.
465          */
466         BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
467         BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
468
469         if (static_key_initialized)
470                 return;
471
472         cpus_read_lock();
473         jump_label_lock();
474         jump_label_sort_entries(iter_start, iter_stop);
475
476         for (iter = iter_start; iter < iter_stop; iter++) {
477                 struct static_key *iterk;
478
479                 /* rewrite NOPs */
480                 if (jump_label_type(iter) == JUMP_LABEL_NOP)
481                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
482
483                 if (init_section_contains((void *)jump_entry_code(iter), 1))
484                         jump_entry_set_init(iter);
485
486                 iterk = jump_entry_key(iter);
487                 if (iterk == key)
488                         continue;
489
490                 key = iterk;
491                 static_key_set_entries(key, iter);
492         }
493         static_key_initialized = true;
494         jump_label_unlock();
495         cpus_read_unlock();
496 }
497
498 #ifdef CONFIG_MODULES
499
500 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
501 {
502         struct static_key *key = jump_entry_key(entry);
503         bool type = static_key_type(key);
504         bool branch = jump_entry_is_branch(entry);
505
506         /* See the comment in linux/jump_label.h */
507         return type ^ branch;
508 }
509
510 struct static_key_mod {
511         struct static_key_mod *next;
512         struct jump_entry *entries;
513         struct module *mod;
514 };
515
516 static inline struct static_key_mod *static_key_mod(struct static_key *key)
517 {
518         WARN_ON_ONCE(!static_key_linked(key));
519         return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
520 }
521
522 /***
523  * key->type and key->next are the same via union.
524  * This sets key->next and preserves the type bits.
525  *
526  * See additional comments above static_key_set_entries().
527  */
528 static void static_key_set_mod(struct static_key *key,
529                                struct static_key_mod *mod)
530 {
531         unsigned long type;
532
533         WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
534         type = key->type & JUMP_TYPE_MASK;
535         key->next = mod;
536         key->type |= type;
537 }
538
539 static int __jump_label_mod_text_reserved(void *start, void *end)
540 {
541         struct module *mod;
542
543         preempt_disable();
544         mod = __module_text_address((unsigned long)start);
545         WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
546         preempt_enable();
547
548         if (!mod)
549                 return 0;
550
551
552         return __jump_label_text_reserved(mod->jump_entries,
553                                 mod->jump_entries + mod->num_jump_entries,
554                                 start, end);
555 }
556
557 static void __jump_label_mod_update(struct static_key *key)
558 {
559         struct static_key_mod *mod;
560
561         for (mod = static_key_mod(key); mod; mod = mod->next) {
562                 struct jump_entry *stop;
563                 struct module *m;
564
565                 /*
566                  * NULL if the static_key is defined in a module
567                  * that does not use it
568                  */
569                 if (!mod->entries)
570                         continue;
571
572                 m = mod->mod;
573                 if (!m)
574                         stop = __stop___jump_table;
575                 else
576                         stop = m->jump_entries + m->num_jump_entries;
577                 __jump_label_update(key, mod->entries, stop,
578                                     m && m->state == MODULE_STATE_COMING);
579         }
580 }
581
582 /***
583  * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
584  * @mod: module to patch
585  *
586  * Allow for run-time selection of the optimal nops. Before the module
587  * loads patch these with arch_get_jump_label_nop(), which is specified by
588  * the arch specific jump label code.
589  */
590 void jump_label_apply_nops(struct module *mod)
591 {
592         struct jump_entry *iter_start = mod->jump_entries;
593         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
594         struct jump_entry *iter;
595
596         /* if the module doesn't have jump label entries, just return */
597         if (iter_start == iter_stop)
598                 return;
599
600         for (iter = iter_start; iter < iter_stop; iter++) {
601                 /* Only write NOPs for arch_branch_static(). */
602                 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
603                         arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
604         }
605 }
606
607 static int jump_label_add_module(struct module *mod)
608 {
609         struct jump_entry *iter_start = mod->jump_entries;
610         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
611         struct jump_entry *iter;
612         struct static_key *key = NULL;
613         struct static_key_mod *jlm, *jlm2;
614
615         /* if the module doesn't have jump label entries, just return */
616         if (iter_start == iter_stop)
617                 return 0;
618
619         jump_label_sort_entries(iter_start, iter_stop);
620
621         for (iter = iter_start; iter < iter_stop; iter++) {
622                 struct static_key *iterk;
623
624                 if (within_module_init(jump_entry_code(iter), mod))
625                         jump_entry_set_init(iter);
626
627                 iterk = jump_entry_key(iter);
628                 if (iterk == key)
629                         continue;
630
631                 key = iterk;
632                 if (within_module((unsigned long)key, mod)) {
633                         static_key_set_entries(key, iter);
634                         continue;
635                 }
636                 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
637                 if (!jlm)
638                         return -ENOMEM;
639                 if (!static_key_linked(key)) {
640                         jlm2 = kzalloc(sizeof(struct static_key_mod),
641                                        GFP_KERNEL);
642                         if (!jlm2) {
643                                 kfree(jlm);
644                                 return -ENOMEM;
645                         }
646                         preempt_disable();
647                         jlm2->mod = __module_address((unsigned long)key);
648                         preempt_enable();
649                         jlm2->entries = static_key_entries(key);
650                         jlm2->next = NULL;
651                         static_key_set_mod(key, jlm2);
652                         static_key_set_linked(key);
653                 }
654                 jlm->mod = mod;
655                 jlm->entries = iter;
656                 jlm->next = static_key_mod(key);
657                 static_key_set_mod(key, jlm);
658                 static_key_set_linked(key);
659
660                 /* Only update if we've changed from our initial state */
661                 if (jump_label_type(iter) != jump_label_init_type(iter))
662                         __jump_label_update(key, iter, iter_stop, true);
663         }
664
665         return 0;
666 }
667
668 static void jump_label_del_module(struct module *mod)
669 {
670         struct jump_entry *iter_start = mod->jump_entries;
671         struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
672         struct jump_entry *iter;
673         struct static_key *key = NULL;
674         struct static_key_mod *jlm, **prev;
675
676         for (iter = iter_start; iter < iter_stop; iter++) {
677                 if (jump_entry_key(iter) == key)
678                         continue;
679
680                 key = jump_entry_key(iter);
681
682                 if (within_module((unsigned long)key, mod))
683                         continue;
684
685                 /* No memory during module load */
686                 if (WARN_ON(!static_key_linked(key)))
687                         continue;
688
689                 prev = &key->next;
690                 jlm = static_key_mod(key);
691
692                 while (jlm && jlm->mod != mod) {
693                         prev = &jlm->next;
694                         jlm = jlm->next;
695                 }
696
697                 /* No memory during module load */
698                 if (WARN_ON(!jlm))
699                         continue;
700
701                 if (prev == &key->next)
702                         static_key_set_mod(key, jlm->next);
703                 else
704                         *prev = jlm->next;
705
706                 kfree(jlm);
707
708                 jlm = static_key_mod(key);
709                 /* if only one etry is left, fold it back into the static_key */
710                 if (jlm->next == NULL) {
711                         static_key_set_entries(key, jlm->entries);
712                         static_key_clear_linked(key);
713                         kfree(jlm);
714                 }
715         }
716 }
717
718 static int
719 jump_label_module_notify(struct notifier_block *self, unsigned long val,
720                          void *data)
721 {
722         struct module *mod = data;
723         int ret = 0;
724
725         cpus_read_lock();
726         jump_label_lock();
727
728         switch (val) {
729         case MODULE_STATE_COMING:
730                 ret = jump_label_add_module(mod);
731                 if (ret) {
732                         WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
733                         jump_label_del_module(mod);
734                 }
735                 break;
736         case MODULE_STATE_GOING:
737                 jump_label_del_module(mod);
738                 break;
739         }
740
741         jump_label_unlock();
742         cpus_read_unlock();
743
744         return notifier_from_errno(ret);
745 }
746
747 static struct notifier_block jump_label_module_nb = {
748         .notifier_call = jump_label_module_notify,
749         .priority = 1, /* higher than tracepoints */
750 };
751
752 static __init int jump_label_init_module(void)
753 {
754         return register_module_notifier(&jump_label_module_nb);
755 }
756 early_initcall(jump_label_init_module);
757
758 #endif /* CONFIG_MODULES */
759
760 /***
761  * jump_label_text_reserved - check if addr range is reserved
762  * @start: start text addr
763  * @end: end text addr
764  *
765  * checks if the text addr located between @start and @end
766  * overlaps with any of the jump label patch addresses. Code
767  * that wants to modify kernel text should first verify that
768  * it does not overlap with any of the jump label addresses.
769  * Caller must hold jump_label_mutex.
770  *
771  * returns 1 if there is an overlap, 0 otherwise
772  */
773 int jump_label_text_reserved(void *start, void *end)
774 {
775         int ret = __jump_label_text_reserved(__start___jump_table,
776                         __stop___jump_table, start, end);
777
778         if (ret)
779                 return ret;
780
781 #ifdef CONFIG_MODULES
782         ret = __jump_label_mod_text_reserved(start, end);
783 #endif
784         return ret;
785 }
786
787 static void jump_label_update(struct static_key *key)
788 {
789         struct jump_entry *stop = __stop___jump_table;
790         struct jump_entry *entry;
791 #ifdef CONFIG_MODULES
792         struct module *mod;
793
794         if (static_key_linked(key)) {
795                 __jump_label_mod_update(key);
796                 return;
797         }
798
799         preempt_disable();
800         mod = __module_address((unsigned long)key);
801         if (mod)
802                 stop = mod->jump_entries + mod->num_jump_entries;
803         preempt_enable();
804 #endif
805         entry = static_key_entries(key);
806         /* if there are no users, entry can be NULL */
807         if (entry)
808                 __jump_label_update(key, entry, stop,
809                                     system_state < SYSTEM_RUNNING);
810 }
811
812 #ifdef CONFIG_STATIC_KEYS_SELFTEST
813 static DEFINE_STATIC_KEY_TRUE(sk_true);
814 static DEFINE_STATIC_KEY_FALSE(sk_false);
815
816 static __init int jump_label_test(void)
817 {
818         int i;
819
820         for (i = 0; i < 2; i++) {
821                 WARN_ON(static_key_enabled(&sk_true.key) != true);
822                 WARN_ON(static_key_enabled(&sk_false.key) != false);
823
824                 WARN_ON(!static_branch_likely(&sk_true));
825                 WARN_ON(!static_branch_unlikely(&sk_true));
826                 WARN_ON(static_branch_likely(&sk_false));
827                 WARN_ON(static_branch_unlikely(&sk_false));
828
829                 static_branch_disable(&sk_true);
830                 static_branch_enable(&sk_false);
831
832                 WARN_ON(static_key_enabled(&sk_true.key) == true);
833                 WARN_ON(static_key_enabled(&sk_false.key) == false);
834
835                 WARN_ON(static_branch_likely(&sk_true));
836                 WARN_ON(static_branch_unlikely(&sk_true));
837                 WARN_ON(!static_branch_likely(&sk_false));
838                 WARN_ON(!static_branch_unlikely(&sk_false));
839
840                 static_branch_enable(&sk_true);
841                 static_branch_disable(&sk_false);
842         }
843
844         return 0;
845 }
846 early_initcall(jump_label_test);
847 #endif /* STATIC_KEYS_SELFTEST */