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
jump_label_lock(void)26 void jump_label_lock(void)
27 {
28 mutex_lock(&jump_label_mutex);
29 }
30
jump_label_unlock(void)31 void jump_label_unlock(void)
32 {
33 mutex_unlock(&jump_label_mutex);
34 }
35
jump_label_cmp(const void * a,const void * b)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 (jea->key < jeb->key)
42 return -1;
43
44 if (jea->key > jeb->key)
45 return 1;
46
47 return 0;
48 }
49
50 static void
jump_label_sort_entries(struct jump_entry * start,struct jump_entry * stop)51 jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
52 {
53 unsigned long size;
54
55 size = (((unsigned long)stop - (unsigned long)start)
56 / sizeof(struct jump_entry));
57 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
58 }
59
60 static void jump_label_update(struct static_key *key);
61
62 /*
63 * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h.
64 * The use of 'atomic_read()' requires atomic.h and its problematic for some
65 * kernel headers such as kernel.h and others. Since static_key_count() is not
66 * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok
67 * to have it be a function here. Similarly, for 'static_key_enable()' and
68 * 'static_key_disable()', which require bug.h. This should allow jump_label.h
69 * to be included from most/all places for HAVE_JUMP_LABEL.
70 */
static_key_count(struct static_key * key)71 int static_key_count(struct static_key *key)
72 {
73 /*
74 * -1 means the first static_key_slow_inc() is in progress.
75 * static_key_enabled() must return true, so return 1 here.
76 */
77 int n = atomic_read(&key->enabled);
78
79 return n >= 0 ? n : 1;
80 }
81 EXPORT_SYMBOL_GPL(static_key_count);
82
static_key_slow_inc_cpuslocked(struct static_key * key)83 void static_key_slow_inc_cpuslocked(struct static_key *key)
84 {
85 int v, v1;
86
87 STATIC_KEY_CHECK_USE(key);
88
89 /*
90 * Careful if we get concurrent static_key_slow_inc() calls;
91 * later calls must wait for the first one to _finish_ the
92 * jump_label_update() process. At the same time, however,
93 * the jump_label_update() call below wants to see
94 * static_key_enabled(&key) for jumps to be updated properly.
95 *
96 * So give a special meaning to negative key->enabled: it sends
97 * static_key_slow_inc() down the slow path, and it is non-zero
98 * so it counts as "enabled" in jump_label_update(). Note that
99 * atomic_inc_unless_negative() checks >= 0, so roll our own.
100 */
101 for (v = atomic_read(&key->enabled); v > 0; v = v1) {
102 v1 = atomic_cmpxchg(&key->enabled, v, v + 1);
103 if (likely(v1 == v))
104 return;
105 }
106
107 jump_label_lock();
108 if (atomic_read(&key->enabled) == 0) {
109 atomic_set(&key->enabled, -1);
110 jump_label_update(key);
111 /*
112 * Ensure that if the above cmpxchg loop observes our positive
113 * value, it must also observe all the text changes.
114 */
115 atomic_set_release(&key->enabled, 1);
116 } else {
117 atomic_inc(&key->enabled);
118 }
119 jump_label_unlock();
120 }
121
static_key_slow_inc(struct static_key * key)122 void static_key_slow_inc(struct static_key *key)
123 {
124 cpus_read_lock();
125 static_key_slow_inc_cpuslocked(key);
126 cpus_read_unlock();
127 }
128 EXPORT_SYMBOL_GPL(static_key_slow_inc);
129
static_key_enable_cpuslocked(struct static_key * key)130 void static_key_enable_cpuslocked(struct static_key *key)
131 {
132 STATIC_KEY_CHECK_USE(key);
133
134 if (atomic_read(&key->enabled) > 0) {
135 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
136 return;
137 }
138
139 jump_label_lock();
140 if (atomic_read(&key->enabled) == 0) {
141 atomic_set(&key->enabled, -1);
142 jump_label_update(key);
143 /*
144 * See static_key_slow_inc().
145 */
146 atomic_set_release(&key->enabled, 1);
147 }
148 jump_label_unlock();
149 }
150 EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
151
static_key_enable(struct static_key * key)152 void static_key_enable(struct static_key *key)
153 {
154 cpus_read_lock();
155 static_key_enable_cpuslocked(key);
156 cpus_read_unlock();
157 }
158 EXPORT_SYMBOL_GPL(static_key_enable);
159
static_key_disable_cpuslocked(struct static_key * key)160 void static_key_disable_cpuslocked(struct static_key *key)
161 {
162 STATIC_KEY_CHECK_USE(key);
163
164 if (atomic_read(&key->enabled) != 1) {
165 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
166 return;
167 }
168
169 jump_label_lock();
170 if (atomic_cmpxchg(&key->enabled, 1, 0))
171 jump_label_update(key);
172 jump_label_unlock();
173 }
174 EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
175
static_key_disable(struct static_key * key)176 void static_key_disable(struct static_key *key)
177 {
178 cpus_read_lock();
179 static_key_disable_cpuslocked(key);
180 cpus_read_unlock();
181 }
182 EXPORT_SYMBOL_GPL(static_key_disable);
183
__static_key_slow_dec_cpuslocked(struct static_key * key,unsigned long rate_limit,struct delayed_work * work)184 static void __static_key_slow_dec_cpuslocked(struct static_key *key,
185 unsigned long rate_limit,
186 struct delayed_work *work)
187 {
188 /*
189 * The negative count check is valid even when a negative
190 * key->enabled is in use by static_key_slow_inc(); a
191 * __static_key_slow_dec() before the first static_key_slow_inc()
192 * returns is unbalanced, because all other static_key_slow_inc()
193 * instances block while the update is in progress.
194 */
195 if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
196 WARN(atomic_read(&key->enabled) < 0,
197 "jump label: negative count!\n");
198 return;
199 }
200
201 if (rate_limit) {
202 atomic_inc(&key->enabled);
203 schedule_delayed_work(work, rate_limit);
204 } else {
205 jump_label_update(key);
206 }
207 jump_label_unlock();
208 }
209
__static_key_slow_dec(struct static_key * key,unsigned long rate_limit,struct delayed_work * work)210 static void __static_key_slow_dec(struct static_key *key,
211 unsigned long rate_limit,
212 struct delayed_work *work)
213 {
214 cpus_read_lock();
215 __static_key_slow_dec_cpuslocked(key, rate_limit, work);
216 cpus_read_unlock();
217 }
218
jump_label_update_timeout(struct work_struct * work)219 static void jump_label_update_timeout(struct work_struct *work)
220 {
221 struct static_key_deferred *key =
222 container_of(work, struct static_key_deferred, work.work);
223 __static_key_slow_dec(&key->key, 0, NULL);
224 }
225
static_key_slow_dec(struct static_key * key)226 void static_key_slow_dec(struct static_key *key)
227 {
228 STATIC_KEY_CHECK_USE(key);
229 __static_key_slow_dec(key, 0, NULL);
230 }
231 EXPORT_SYMBOL_GPL(static_key_slow_dec);
232
static_key_slow_dec_cpuslocked(struct static_key * key)233 void static_key_slow_dec_cpuslocked(struct static_key *key)
234 {
235 STATIC_KEY_CHECK_USE(key);
236 __static_key_slow_dec_cpuslocked(key, 0, NULL);
237 }
238
static_key_slow_dec_deferred(struct static_key_deferred * key)239 void static_key_slow_dec_deferred(struct static_key_deferred *key)
240 {
241 STATIC_KEY_CHECK_USE(key);
242 __static_key_slow_dec(&key->key, key->timeout, &key->work);
243 }
244 EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
245
static_key_deferred_flush(struct static_key_deferred * key)246 void static_key_deferred_flush(struct static_key_deferred *key)
247 {
248 STATIC_KEY_CHECK_USE(key);
249 flush_delayed_work(&key->work);
250 }
251 EXPORT_SYMBOL_GPL(static_key_deferred_flush);
252
jump_label_rate_limit(struct static_key_deferred * key,unsigned long rl)253 void jump_label_rate_limit(struct static_key_deferred *key,
254 unsigned long rl)
255 {
256 STATIC_KEY_CHECK_USE(key);
257 key->timeout = rl;
258 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
259 }
260 EXPORT_SYMBOL_GPL(jump_label_rate_limit);
261
addr_conflict(struct jump_entry * entry,void * start,void * end)262 static int addr_conflict(struct jump_entry *entry, void *start, void *end)
263 {
264 if (entry->code <= (unsigned long)end &&
265 entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
266 return 1;
267
268 return 0;
269 }
270
__jump_label_text_reserved(struct jump_entry * iter_start,struct jump_entry * iter_stop,void * start,void * end)271 static int __jump_label_text_reserved(struct jump_entry *iter_start,
272 struct jump_entry *iter_stop, void *start, void *end)
273 {
274 struct jump_entry *iter;
275
276 iter = iter_start;
277 while (iter < iter_stop) {
278 if (addr_conflict(iter, start, end))
279 return 1;
280 iter++;
281 }
282
283 return 0;
284 }
285
286 /*
287 * Update code which is definitely not currently executing.
288 * Architectures which need heavyweight synchronization to modify
289 * running code can override this to make the non-live update case
290 * cheaper.
291 */
arch_jump_label_transform_static(struct jump_entry * entry,enum jump_label_type type)292 void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
293 enum jump_label_type type)
294 {
295 arch_jump_label_transform(entry, type);
296 }
297
static_key_entries(struct static_key * key)298 static inline struct jump_entry *static_key_entries(struct static_key *key)
299 {
300 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
301 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
302 }
303
static_key_type(struct static_key * key)304 static inline bool static_key_type(struct static_key *key)
305 {
306 return key->type & JUMP_TYPE_TRUE;
307 }
308
static_key_linked(struct static_key * key)309 static inline bool static_key_linked(struct static_key *key)
310 {
311 return key->type & JUMP_TYPE_LINKED;
312 }
313
static_key_clear_linked(struct static_key * key)314 static inline void static_key_clear_linked(struct static_key *key)
315 {
316 key->type &= ~JUMP_TYPE_LINKED;
317 }
318
static_key_set_linked(struct static_key * key)319 static inline void static_key_set_linked(struct static_key *key)
320 {
321 key->type |= JUMP_TYPE_LINKED;
322 }
323
jump_entry_key(struct jump_entry * entry)324 static inline struct static_key *jump_entry_key(struct jump_entry *entry)
325 {
326 return (struct static_key *)((unsigned long)entry->key & ~1UL);
327 }
328
jump_entry_branch(struct jump_entry * entry)329 static bool jump_entry_branch(struct jump_entry *entry)
330 {
331 return (unsigned long)entry->key & 1UL;
332 }
333
334 /***
335 * A 'struct static_key' uses a union such that it either points directly
336 * to a table of 'struct jump_entry' or to a linked list of modules which in
337 * turn point to 'struct jump_entry' tables.
338 *
339 * The two lower bits of the pointer are used to keep track of which pointer
340 * type is in use and to store the initial branch direction, we use an access
341 * function which preserves these bits.
342 */
static_key_set_entries(struct static_key * key,struct jump_entry * entries)343 static void static_key_set_entries(struct static_key *key,
344 struct jump_entry *entries)
345 {
346 unsigned long type;
347
348 WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK);
349 type = key->type & JUMP_TYPE_MASK;
350 key->entries = entries;
351 key->type |= type;
352 }
353
jump_label_type(struct jump_entry * entry)354 static enum jump_label_type jump_label_type(struct jump_entry *entry)
355 {
356 struct static_key *key = jump_entry_key(entry);
357 bool enabled = static_key_enabled(key);
358 bool branch = jump_entry_branch(entry);
359
360 /* See the comment in linux/jump_label.h */
361 return enabled ^ branch;
362 }
363
__jump_label_update(struct static_key * key,struct jump_entry * entry,struct jump_entry * stop)364 static void __jump_label_update(struct static_key *key,
365 struct jump_entry *entry,
366 struct jump_entry *stop)
367 {
368 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
369 /*
370 * An entry->code of 0 indicates an entry which has been
371 * disabled because it was in an init text area.
372 */
373 if (entry->code) {
374 if (kernel_text_address(entry->code))
375 arch_jump_label_transform(entry, jump_label_type(entry));
376 else
377 WARN_ONCE(1, "can't patch jump_label at %pS",
378 (void *)(unsigned long)entry->code);
379 }
380 }
381 }
382
jump_label_init(void)383 void __init jump_label_init(void)
384 {
385 struct jump_entry *iter_start = __start___jump_table;
386 struct jump_entry *iter_stop = __stop___jump_table;
387 struct static_key *key = NULL;
388 struct jump_entry *iter;
389
390 /*
391 * Since we are initializing the static_key.enabled field with
392 * with the 'raw' int values (to avoid pulling in atomic.h) in
393 * jump_label.h, let's make sure that is safe. There are only two
394 * cases to check since we initialize to 0 or 1.
395 */
396 BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
397 BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
398
399 if (static_key_initialized)
400 return;
401
402 cpus_read_lock();
403 jump_label_lock();
404 jump_label_sort_entries(iter_start, iter_stop);
405
406 for (iter = iter_start; iter < iter_stop; iter++) {
407 struct static_key *iterk;
408
409 /* rewrite NOPs */
410 if (jump_label_type(iter) == JUMP_LABEL_NOP)
411 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
412
413 iterk = jump_entry_key(iter);
414 if (iterk == key)
415 continue;
416
417 key = iterk;
418 static_key_set_entries(key, iter);
419 }
420 static_key_initialized = true;
421 jump_label_unlock();
422 cpus_read_unlock();
423 }
424
425 /* Disable any jump label entries in __init/__exit code */
jump_label_invalidate_initmem(void)426 void __init jump_label_invalidate_initmem(void)
427 {
428 struct jump_entry *iter_start = __start___jump_table;
429 struct jump_entry *iter_stop = __stop___jump_table;
430 struct jump_entry *iter;
431
432 for (iter = iter_start; iter < iter_stop; iter++) {
433 if (init_section_contains((void *)(unsigned long)iter->code, 1))
434 iter->code = 0;
435 }
436 }
437
438 #ifdef CONFIG_MODULES
439
jump_label_init_type(struct jump_entry * entry)440 static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
441 {
442 struct static_key *key = jump_entry_key(entry);
443 bool type = static_key_type(key);
444 bool branch = jump_entry_branch(entry);
445
446 /* See the comment in linux/jump_label.h */
447 return type ^ branch;
448 }
449
450 struct static_key_mod {
451 struct static_key_mod *next;
452 struct jump_entry *entries;
453 struct module *mod;
454 };
455
static_key_mod(struct static_key * key)456 static inline struct static_key_mod *static_key_mod(struct static_key *key)
457 {
458 WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED));
459 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
460 }
461
462 /***
463 * key->type and key->next are the same via union.
464 * This sets key->next and preserves the type bits.
465 *
466 * See additional comments above static_key_set_entries().
467 */
static_key_set_mod(struct static_key * key,struct static_key_mod * mod)468 static void static_key_set_mod(struct static_key *key,
469 struct static_key_mod *mod)
470 {
471 unsigned long type;
472
473 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
474 type = key->type & JUMP_TYPE_MASK;
475 key->next = mod;
476 key->type |= type;
477 }
478
__jump_label_mod_text_reserved(void * start,void * end)479 static int __jump_label_mod_text_reserved(void *start, void *end)
480 {
481 struct module *mod;
482
483 preempt_disable();
484 mod = __module_text_address((unsigned long)start);
485 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
486 preempt_enable();
487
488 if (!mod)
489 return 0;
490
491
492 return __jump_label_text_reserved(mod->jump_entries,
493 mod->jump_entries + mod->num_jump_entries,
494 start, end);
495 }
496
__jump_label_mod_update(struct static_key * key)497 static void __jump_label_mod_update(struct static_key *key)
498 {
499 struct static_key_mod *mod;
500
501 for (mod = static_key_mod(key); mod; mod = mod->next) {
502 struct jump_entry *stop;
503 struct module *m;
504
505 /*
506 * NULL if the static_key is defined in a module
507 * that does not use it
508 */
509 if (!mod->entries)
510 continue;
511
512 m = mod->mod;
513 if (!m)
514 stop = __stop___jump_table;
515 else
516 stop = m->jump_entries + m->num_jump_entries;
517 __jump_label_update(key, mod->entries, stop);
518 }
519 }
520
521 /***
522 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
523 * @mod: module to patch
524 *
525 * Allow for run-time selection of the optimal nops. Before the module
526 * loads patch these with arch_get_jump_label_nop(), which is specified by
527 * the arch specific jump label code.
528 */
jump_label_apply_nops(struct module * mod)529 void jump_label_apply_nops(struct module *mod)
530 {
531 struct jump_entry *iter_start = mod->jump_entries;
532 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
533 struct jump_entry *iter;
534
535 /* if the module doesn't have jump label entries, just return */
536 if (iter_start == iter_stop)
537 return;
538
539 for (iter = iter_start; iter < iter_stop; iter++) {
540 /* Only write NOPs for arch_branch_static(). */
541 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
542 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
543 }
544 }
545
jump_label_add_module(struct module * mod)546 static int jump_label_add_module(struct module *mod)
547 {
548 struct jump_entry *iter_start = mod->jump_entries;
549 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
550 struct jump_entry *iter;
551 struct static_key *key = NULL;
552 struct static_key_mod *jlm, *jlm2;
553
554 /* if the module doesn't have jump label entries, just return */
555 if (iter_start == iter_stop)
556 return 0;
557
558 jump_label_sort_entries(iter_start, iter_stop);
559
560 for (iter = iter_start; iter < iter_stop; iter++) {
561 struct static_key *iterk;
562
563 iterk = jump_entry_key(iter);
564 if (iterk == key)
565 continue;
566
567 key = iterk;
568 if (within_module(iter->key, mod)) {
569 static_key_set_entries(key, iter);
570 continue;
571 }
572 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
573 if (!jlm)
574 return -ENOMEM;
575 if (!static_key_linked(key)) {
576 jlm2 = kzalloc(sizeof(struct static_key_mod),
577 GFP_KERNEL);
578 if (!jlm2) {
579 kfree(jlm);
580 return -ENOMEM;
581 }
582 preempt_disable();
583 jlm2->mod = __module_address((unsigned long)key);
584 preempt_enable();
585 jlm2->entries = static_key_entries(key);
586 jlm2->next = NULL;
587 static_key_set_mod(key, jlm2);
588 static_key_set_linked(key);
589 }
590 jlm->mod = mod;
591 jlm->entries = iter;
592 jlm->next = static_key_mod(key);
593 static_key_set_mod(key, jlm);
594 static_key_set_linked(key);
595
596 /* Only update if we've changed from our initial state */
597 if (jump_label_type(iter) != jump_label_init_type(iter))
598 __jump_label_update(key, iter, iter_stop);
599 }
600
601 return 0;
602 }
603
jump_label_del_module(struct module * mod)604 static void jump_label_del_module(struct module *mod)
605 {
606 struct jump_entry *iter_start = mod->jump_entries;
607 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
608 struct jump_entry *iter;
609 struct static_key *key = NULL;
610 struct static_key_mod *jlm, **prev;
611
612 for (iter = iter_start; iter < iter_stop; iter++) {
613 if (jump_entry_key(iter) == key)
614 continue;
615
616 key = jump_entry_key(iter);
617
618 if (within_module(iter->key, mod))
619 continue;
620
621 /* No memory during module load */
622 if (WARN_ON(!static_key_linked(key)))
623 continue;
624
625 prev = &key->next;
626 jlm = static_key_mod(key);
627
628 while (jlm && jlm->mod != mod) {
629 prev = &jlm->next;
630 jlm = jlm->next;
631 }
632
633 /* No memory during module load */
634 if (WARN_ON(!jlm))
635 continue;
636
637 if (prev == &key->next)
638 static_key_set_mod(key, jlm->next);
639 else
640 *prev = jlm->next;
641
642 kfree(jlm);
643
644 jlm = static_key_mod(key);
645 /* if only one etry is left, fold it back into the static_key */
646 if (jlm->next == NULL) {
647 static_key_set_entries(key, jlm->entries);
648 static_key_clear_linked(key);
649 kfree(jlm);
650 }
651 }
652 }
653
654 /* Disable any jump label entries in module init code */
jump_label_invalidate_module_init(struct module * mod)655 static void jump_label_invalidate_module_init(struct module *mod)
656 {
657 struct jump_entry *iter_start = mod->jump_entries;
658 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
659 struct jump_entry *iter;
660
661 for (iter = iter_start; iter < iter_stop; iter++) {
662 if (within_module_init(iter->code, mod))
663 iter->code = 0;
664 }
665 }
666
667 static int
jump_label_module_notify(struct notifier_block * self,unsigned long val,void * data)668 jump_label_module_notify(struct notifier_block *self, unsigned long val,
669 void *data)
670 {
671 struct module *mod = data;
672 int ret = 0;
673
674 cpus_read_lock();
675 jump_label_lock();
676
677 switch (val) {
678 case MODULE_STATE_COMING:
679 ret = jump_label_add_module(mod);
680 if (ret) {
681 WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
682 jump_label_del_module(mod);
683 }
684 break;
685 case MODULE_STATE_GOING:
686 jump_label_del_module(mod);
687 break;
688 case MODULE_STATE_LIVE:
689 jump_label_invalidate_module_init(mod);
690 break;
691 }
692
693 jump_label_unlock();
694 cpus_read_unlock();
695
696 return notifier_from_errno(ret);
697 }
698
699 static struct notifier_block jump_label_module_nb = {
700 .notifier_call = jump_label_module_notify,
701 .priority = 1, /* higher than tracepoints */
702 };
703
jump_label_init_module(void)704 static __init int jump_label_init_module(void)
705 {
706 return register_module_notifier(&jump_label_module_nb);
707 }
708 early_initcall(jump_label_init_module);
709
710 #endif /* CONFIG_MODULES */
711
712 /***
713 * jump_label_text_reserved - check if addr range is reserved
714 * @start: start text addr
715 * @end: end text addr
716 *
717 * checks if the text addr located between @start and @end
718 * overlaps with any of the jump label patch addresses. Code
719 * that wants to modify kernel text should first verify that
720 * it does not overlap with any of the jump label addresses.
721 * Caller must hold jump_label_mutex.
722 *
723 * returns 1 if there is an overlap, 0 otherwise
724 */
jump_label_text_reserved(void * start,void * end)725 int jump_label_text_reserved(void *start, void *end)
726 {
727 int ret = __jump_label_text_reserved(__start___jump_table,
728 __stop___jump_table, start, end);
729
730 if (ret)
731 return ret;
732
733 #ifdef CONFIG_MODULES
734 ret = __jump_label_mod_text_reserved(start, end);
735 #endif
736 return ret;
737 }
738
jump_label_update(struct static_key * key)739 static void jump_label_update(struct static_key *key)
740 {
741 struct jump_entry *stop = __stop___jump_table;
742 struct jump_entry *entry;
743 #ifdef CONFIG_MODULES
744 struct module *mod;
745
746 if (static_key_linked(key)) {
747 __jump_label_mod_update(key);
748 return;
749 }
750
751 preempt_disable();
752 mod = __module_address((unsigned long)key);
753 if (mod)
754 stop = mod->jump_entries + mod->num_jump_entries;
755 preempt_enable();
756 #endif
757 entry = static_key_entries(key);
758 /* if there are no users, entry can be NULL */
759 if (entry)
760 __jump_label_update(key, entry, stop);
761 }
762
763 #ifdef CONFIG_STATIC_KEYS_SELFTEST
764 static DEFINE_STATIC_KEY_TRUE(sk_true);
765 static DEFINE_STATIC_KEY_FALSE(sk_false);
766
jump_label_test(void)767 static __init int jump_label_test(void)
768 {
769 int i;
770
771 for (i = 0; i < 2; i++) {
772 WARN_ON(static_key_enabled(&sk_true.key) != true);
773 WARN_ON(static_key_enabled(&sk_false.key) != false);
774
775 WARN_ON(!static_branch_likely(&sk_true));
776 WARN_ON(!static_branch_unlikely(&sk_true));
777 WARN_ON(static_branch_likely(&sk_false));
778 WARN_ON(static_branch_unlikely(&sk_false));
779
780 static_branch_disable(&sk_true);
781 static_branch_enable(&sk_false);
782
783 WARN_ON(static_key_enabled(&sk_true.key) == true);
784 WARN_ON(static_key_enabled(&sk_false.key) == false);
785
786 WARN_ON(static_branch_likely(&sk_true));
787 WARN_ON(static_branch_unlikely(&sk_true));
788 WARN_ON(!static_branch_likely(&sk_false));
789 WARN_ON(!static_branch_unlikely(&sk_false));
790
791 static_branch_enable(&sk_true);
792 static_branch_disable(&sk_false);
793 }
794
795 return 0;
796 }
797 early_initcall(jump_label_test);
798 #endif /* STATIC_KEYS_SELFTEST */
799
800 #endif /* HAVE_JUMP_LABEL */
801