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457c8996 1// SPDX-License-Identifier: GPL-2.0-only
bf5438fc
JB
2/*
3 * jump label support
4 *
5 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
90eec103 6 * Copyright (C) 2011 Peter Zijlstra
bf5438fc
JB
7 *
8 */
bf5438fc
JB
9#include <linux/memory.h>
10#include <linux/uaccess.h>
11#include <linux/module.h>
12#include <linux/list.h>
bf5438fc
JB
13#include <linux/slab.h>
14#include <linux/sort.h>
15#include <linux/err.h>
c5905afb 16#include <linux/static_key.h>
851cf6e7 17#include <linux/jump_label_ratelimit.h>
1f69bf9c 18#include <linux/bug.h>
f2545b2d 19#include <linux/cpu.h>
578ae447 20#include <asm/sections.h>
bf5438fc 21
7b7b8a2c 22/* mutex to protect coming/going of the jump_label table */
bf5438fc
JB
23static DEFINE_MUTEX(jump_label_mutex);
24
91bad2f8
JB
25void jump_label_lock(void)
26{
27 mutex_lock(&jump_label_mutex);
28}
29
30void jump_label_unlock(void)
31{
32 mutex_unlock(&jump_label_mutex);
33}
34
bf5438fc
JB
35static 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
0f133021
DBO
40 /*
41 * Entrires are sorted by key.
42 */
9ae033ac 43 if (jump_entry_key(jea) < jump_entry_key(jeb))
bf5438fc
JB
44 return -1;
45
9ae033ac 46 if (jump_entry_key(jea) > jump_entry_key(jeb))
bf5438fc
JB
47 return 1;
48
0f133021
DBO
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
bf5438fc
JB
60 return 0;
61}
62
50ff18ab
AB
63static 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
bf5438fc 79static void
d430d3d7 80jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
bf5438fc
JB
81{
82 unsigned long size;
50ff18ab
AB
83 void *swapfn = NULL;
84
85 if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE))
86 swapfn = jump_label_swap;
bf5438fc
JB
87
88 size = (((unsigned long)stop - (unsigned long)start)
89 / sizeof(struct jump_entry));
50ff18ab 90 sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn);
bf5438fc
JB
91}
92
706249c2 93static void jump_label_update(struct static_key *key);
a1efb01f 94
1f69bf9c 95/*
e9666d10 96 * There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h.
1f69bf9c
JB
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
e9666d10 99 * used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok
1f69bf9c
JB
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
e9666d10 102 * to be included from most/all places for CONFIG_JUMP_LABEL.
1f69bf9c
JB
103 */
104int 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}
114EXPORT_SYMBOL_GPL(static_key_count);
115
ce48c146 116void static_key_slow_inc_cpuslocked(struct static_key *key)
bf5438fc 117{
4c5ea0a9
PB
118 int v, v1;
119
5cdda511 120 STATIC_KEY_CHECK_USE(key);
cb538267 121 lockdep_assert_cpus_held();
4c5ea0a9
PB
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);
8b7b4128 137 if (likely(v1 == v))
4c5ea0a9
PB
138 return;
139 }
bf5438fc 140
d430d3d7 141 jump_label_lock();
4c5ea0a9
PB
142 if (atomic_read(&key->enabled) == 0) {
143 atomic_set(&key->enabled, -1);
706249c2 144 jump_label_update(key);
d0646a6f
PZ
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);
4c5ea0a9
PB
150 } else {
151 atomic_inc(&key->enabled);
152 }
d430d3d7 153 jump_label_unlock();
8b7b4128
MZ
154}
155
156void static_key_slow_inc(struct static_key *key)
157{
158 cpus_read_lock();
159 static_key_slow_inc_cpuslocked(key);
f2545b2d 160 cpus_read_unlock();
bf5438fc 161}
c5905afb 162EXPORT_SYMBOL_GPL(static_key_slow_inc);
bf5438fc 163
5a40527f 164void static_key_enable_cpuslocked(struct static_key *key)
1dbb6704 165{
5cdda511 166 STATIC_KEY_CHECK_USE(key);
cb538267 167 lockdep_assert_cpus_held();
5a40527f 168
1dbb6704
PB
169 if (atomic_read(&key->enabled) > 0) {
170 WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
171 return;
172 }
173
1dbb6704
PB
174 jump_label_lock();
175 if (atomic_read(&key->enabled) == 0) {
176 atomic_set(&key->enabled, -1);
177 jump_label_update(key);
d0646a6f
PZ
178 /*
179 * See static_key_slow_inc().
180 */
181 atomic_set_release(&key->enabled, 1);
1dbb6704
PB
182 }
183 jump_label_unlock();
5a40527f
MZ
184}
185EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked);
186
187void static_key_enable(struct static_key *key)
188{
189 cpus_read_lock();
190 static_key_enable_cpuslocked(key);
1dbb6704
PB
191 cpus_read_unlock();
192}
193EXPORT_SYMBOL_GPL(static_key_enable);
194
5a40527f 195void static_key_disable_cpuslocked(struct static_key *key)
1dbb6704 196{
5cdda511 197 STATIC_KEY_CHECK_USE(key);
cb538267 198 lockdep_assert_cpus_held();
5a40527f 199
1dbb6704
PB
200 if (atomic_read(&key->enabled) != 1) {
201 WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
202 return;
203 }
204
1dbb6704
PB
205 jump_label_lock();
206 if (atomic_cmpxchg(&key->enabled, 1, 0))
207 jump_label_update(key);
208 jump_label_unlock();
5a40527f
MZ
209}
210EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked);
211
212void static_key_disable(struct static_key *key)
213{
214 cpus_read_lock();
215 static_key_disable_cpuslocked(key);
1dbb6704
PB
216 cpus_read_unlock();
217}
218EXPORT_SYMBOL_GPL(static_key_disable);
219
b92e793b 220static bool static_key_slow_try_dec(struct static_key *key)
bf5438fc 221{
a1247d06
PZ
222 int val;
223
b92e793b
JK
224 val = atomic_fetch_add_unless(&key->enabled, -1, 1);
225 if (val == 1)
226 return false;
cb538267 227
4c5ea0a9
PB
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 */
b92e793b
JK
235 WARN(val < 0, "jump label: negative count!\n");
236 return true;
237}
238
94b5f312 239static void __static_key_slow_dec_cpuslocked(struct static_key *key)
b92e793b
JK
240{
241 lockdep_assert_cpus_held();
242
243 if (static_key_slow_try_dec(key))
d430d3d7 244 return;
bf5438fc 245
a1247d06 246 jump_label_lock();
94b5f312
JK
247 if (atomic_dec_and_test(&key->enabled))
248 jump_label_update(key);
91bad2f8 249 jump_label_unlock();
8b7b4128
MZ
250}
251
94b5f312 252static void __static_key_slow_dec(struct static_key *key)
8b7b4128
MZ
253{
254 cpus_read_lock();
94b5f312 255 __static_key_slow_dec_cpuslocked(key);
f2545b2d 256 cpus_read_unlock();
bf5438fc
JB
257}
258
ad282a81 259void jump_label_update_timeout(struct work_struct *work)
b2029520 260{
c5905afb
IM
261 struct static_key_deferred *key =
262 container_of(work, struct static_key_deferred, work.work);
94b5f312 263 __static_key_slow_dec(&key->key);
b2029520 264}
ad282a81 265EXPORT_SYMBOL_GPL(jump_label_update_timeout);
b2029520 266
c5905afb 267void static_key_slow_dec(struct static_key *key)
b2029520 268{
5cdda511 269 STATIC_KEY_CHECK_USE(key);
94b5f312 270 __static_key_slow_dec(key);
b2029520 271}
c5905afb 272EXPORT_SYMBOL_GPL(static_key_slow_dec);
b2029520 273
ce48c146
PZ
274void static_key_slow_dec_cpuslocked(struct static_key *key)
275{
276 STATIC_KEY_CHECK_USE(key);
94b5f312 277 __static_key_slow_dec_cpuslocked(key);
ce48c146
PZ
278}
279
ad282a81
JK
280void __static_key_slow_dec_deferred(struct static_key *key,
281 struct delayed_work *work,
282 unsigned long timeout)
b2029520 283{
5cdda511 284 STATIC_KEY_CHECK_USE(key);
94b5f312
JK
285
286 if (static_key_slow_try_dec(key))
287 return;
288
289 schedule_delayed_work(work, timeout);
b2029520 290}
ad282a81 291EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred);
b2029520 292
ad282a81 293void __static_key_deferred_flush(void *key, struct delayed_work *work)
b6416e61 294{
5cdda511 295 STATIC_KEY_CHECK_USE(key);
ad282a81 296 flush_delayed_work(work);
b6416e61 297}
ad282a81 298EXPORT_SYMBOL_GPL(__static_key_deferred_flush);
b6416e61 299
c5905afb 300void jump_label_rate_limit(struct static_key_deferred *key,
b2029520
GN
301 unsigned long rl)
302{
5cdda511 303 STATIC_KEY_CHECK_USE(key);
b2029520
GN
304 key->timeout = rl;
305 INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
306}
a181dc14 307EXPORT_SYMBOL_GPL(jump_label_rate_limit);
b2029520 308
4c3ef6d7
JB
309static int addr_conflict(struct jump_entry *entry, void *start, void *end)
310{
9ae033ac
AB
311 if (jump_entry_code(entry) <= (unsigned long)end &&
312 jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
4c3ef6d7
JB
313 return 1;
314
315 return 0;
316}
317
d430d3d7
JB
318static int __jump_label_text_reserved(struct jump_entry *iter_start,
319 struct jump_entry *iter_stop, void *start, void *end)
4c3ef6d7 320{
4c3ef6d7 321 struct jump_entry *iter;
4c3ef6d7 322
4c3ef6d7
JB
323 iter = iter_start;
324 while (iter < iter_stop) {
d430d3d7
JB
325 if (addr_conflict(iter, start, end))
326 return 1;
4c3ef6d7
JB
327 iter++;
328 }
329
d430d3d7
JB
330 return 0;
331}
332
706249c2 333/*
20284aa7
JF
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 */
9cdbe1cb 339void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
20284aa7
JF
340 enum jump_label_type type)
341{
706249c2 342 arch_jump_label_transform(entry, type);
20284aa7
JF
343}
344
706249c2 345static inline struct jump_entry *static_key_entries(struct static_key *key)
d430d3d7 346{
3821fd35
JB
347 WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED);
348 return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK);
4c3ef6d7
JB
349}
350
706249c2 351static inline bool static_key_type(struct static_key *key)
c5905afb 352{
3821fd35
JB
353 return key->type & JUMP_TYPE_TRUE;
354}
355
356static inline bool static_key_linked(struct static_key *key)
357{
358 return key->type & JUMP_TYPE_LINKED;
359}
360
361static inline void static_key_clear_linked(struct static_key *key)
362{
363 key->type &= ~JUMP_TYPE_LINKED;
364}
365
366static inline void static_key_set_linked(struct static_key *key)
367{
368 key->type |= JUMP_TYPE_LINKED;
a1efb01f 369}
c5905afb 370
3821fd35
JB
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 */
380static 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
706249c2 391static enum jump_label_type jump_label_type(struct jump_entry *entry)
a1efb01f 392{
706249c2 393 struct static_key *key = jump_entry_key(entry);
a1efb01f 394 bool enabled = static_key_enabled(key);
9ae033ac 395 bool branch = jump_entry_is_branch(entry);
c5905afb 396
11276d53
PZ
397 /* See the comment in linux/jump_label.h */
398 return enabled ^ branch;
c5905afb
IM
399}
400
e1aacb3f
DBO
401static 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))) {
d4ea1929
PZ
410 /*
411 * This skips patching built-in __exit, which
412 * is part of init_section_contains() but is
413 * not part of kernel_text_address().
414 *
415 * Skipping built-in __exit is fine since it
416 * will never be executed.
417 */
8f35eaa5
AM
418 WARN_ONCE(!jump_entry_is_init(entry),
419 "can't patch jump_label at %pS",
420 (void *)jump_entry_code(entry));
e1aacb3f
DBO
421 return false;
422 }
423
424 return true;
425}
426
c2ba8a15 427#ifndef HAVE_JUMP_LABEL_BATCH
706249c2
PZ
428static void __jump_label_update(struct static_key *key,
429 struct jump_entry *entry,
19483677
AB
430 struct jump_entry *stop,
431 bool init)
706249c2
PZ
432{
433 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
e1aacb3f
DBO
434 if (jump_label_can_update(entry, init))
435 arch_jump_label_transform(entry, jump_label_type(entry));
706249c2
PZ
436 }
437}
c2ba8a15
DBO
438#else
439static void __jump_label_update(struct static_key *key,
440 struct jump_entry *entry,
441 struct jump_entry *stop,
442 bool init)
443{
444 for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
445
446 if (!jump_label_can_update(entry, init))
447 continue;
448
449 if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) {
450 /*
451 * Queue is full: Apply the current queue and try again.
452 */
453 arch_jump_label_transform_apply();
454 BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry)));
455 }
456 }
457 arch_jump_label_transform_apply();
458}
459#endif
706249c2 460
97ce2c88 461void __init jump_label_init(void)
bf5438fc 462{
bf5438fc
JB
463 struct jump_entry *iter_start = __start___jump_table;
464 struct jump_entry *iter_stop = __stop___jump_table;
c5905afb 465 struct static_key *key = NULL;
bf5438fc
JB
466 struct jump_entry *iter;
467
1f69bf9c
JB
468 /*
469 * Since we are initializing the static_key.enabled field with
470 * with the 'raw' int values (to avoid pulling in atomic.h) in
471 * jump_label.h, let's make sure that is safe. There are only two
472 * cases to check since we initialize to 0 or 1.
473 */
474 BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0);
475 BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1);
476
e3f91083
KH
477 if (static_key_initialized)
478 return;
479
f2545b2d 480 cpus_read_lock();
91bad2f8 481 jump_label_lock();
d430d3d7
JB
482 jump_label_sort_entries(iter_start, iter_stop);
483
484 for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb 485 struct static_key *iterk;
37348804 486
11276d53
PZ
487 /* rewrite NOPs */
488 if (jump_label_type(iter) == JUMP_LABEL_NOP)
489 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
490
19483677
AB
491 if (init_section_contains((void *)jump_entry_code(iter), 1))
492 jump_entry_set_init(iter);
493
7dcfd915 494 iterk = jump_entry_key(iter);
37348804 495 if (iterk == key)
d430d3d7
JB
496 continue;
497
37348804 498 key = iterk;
3821fd35 499 static_key_set_entries(key, iter);
bf5438fc 500 }
c4b2c0c5 501 static_key_initialized = true;
91bad2f8 502 jump_label_unlock();
f2545b2d 503 cpus_read_unlock();
bf5438fc 504}
bf5438fc
JB
505
506#ifdef CONFIG_MODULES
507
11276d53
PZ
508static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
509{
510 struct static_key *key = jump_entry_key(entry);
511 bool type = static_key_type(key);
9ae033ac 512 bool branch = jump_entry_is_branch(entry);
11276d53
PZ
513
514 /* See the comment in linux/jump_label.h */
515 return type ^ branch;
516}
517
c5905afb
IM
518struct static_key_mod {
519 struct static_key_mod *next;
d430d3d7
JB
520 struct jump_entry *entries;
521 struct module *mod;
522};
523
3821fd35
JB
524static inline struct static_key_mod *static_key_mod(struct static_key *key)
525{
34e12b86 526 WARN_ON_ONCE(!static_key_linked(key));
3821fd35
JB
527 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
528}
529
530/***
531 * key->type and key->next are the same via union.
532 * This sets key->next and preserves the type bits.
533 *
534 * See additional comments above static_key_set_entries().
535 */
536static void static_key_set_mod(struct static_key *key,
537 struct static_key_mod *mod)
538{
539 unsigned long type;
540
541 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
542 type = key->type & JUMP_TYPE_MASK;
543 key->next = mod;
544 key->type |= type;
545}
546
d430d3d7
JB
547static int __jump_label_mod_text_reserved(void *start, void *end)
548{
549 struct module *mod;
0db6e373 550 int ret;
d430d3d7 551
bdc9f373 552 preempt_disable();
d430d3d7 553 mod = __module_text_address((unsigned long)start);
bdc9f373 554 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
0db6e373
PZ
555 if (!try_module_get(mod))
556 mod = NULL;
bdc9f373
RR
557 preempt_enable();
558
d430d3d7
JB
559 if (!mod)
560 return 0;
561
0db6e373 562 ret = __jump_label_text_reserved(mod->jump_entries,
d430d3d7
JB
563 mod->jump_entries + mod->num_jump_entries,
564 start, end);
0db6e373
PZ
565
566 module_put(mod);
567
568 return ret;
d430d3d7
JB
569}
570
706249c2 571static void __jump_label_mod_update(struct static_key *key)
d430d3d7 572{
706249c2 573 struct static_key_mod *mod;
d430d3d7 574
3821fd35
JB
575 for (mod = static_key_mod(key); mod; mod = mod->next) {
576 struct jump_entry *stop;
577 struct module *m;
578
579 /*
580 * NULL if the static_key is defined in a module
581 * that does not use it
582 */
583 if (!mod->entries)
584 continue;
7cbc5b8d 585
3821fd35
JB
586 m = mod->mod;
587 if (!m)
588 stop = __stop___jump_table;
589 else
590 stop = m->jump_entries + m->num_jump_entries;
19483677 591 __jump_label_update(key, mod->entries, stop,
77ac1c02 592 m && m->state == MODULE_STATE_COMING);
d430d3d7
JB
593 }
594}
595
596/***
597 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
598 * @mod: module to patch
599 *
600 * Allow for run-time selection of the optimal nops. Before the module
601 * loads patch these with arch_get_jump_label_nop(), which is specified by
602 * the arch specific jump label code.
603 */
604void jump_label_apply_nops(struct module *mod)
bf5438fc 605{
d430d3d7
JB
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
610 /* if the module doesn't have jump label entries, just return */
611 if (iter_start == iter_stop)
612 return;
613
11276d53
PZ
614 for (iter = iter_start; iter < iter_stop; iter++) {
615 /* Only write NOPs for arch_branch_static(). */
616 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
617 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
618 }
bf5438fc
JB
619}
620
d430d3d7 621static int jump_label_add_module(struct module *mod)
bf5438fc 622{
d430d3d7
JB
623 struct jump_entry *iter_start = mod->jump_entries;
624 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
625 struct jump_entry *iter;
c5905afb 626 struct static_key *key = NULL;
3821fd35 627 struct static_key_mod *jlm, *jlm2;
bf5438fc
JB
628
629 /* if the module doesn't have jump label entries, just return */
d430d3d7 630 if (iter_start == iter_stop)
bf5438fc
JB
631 return 0;
632
d430d3d7
JB
633 jump_label_sort_entries(iter_start, iter_stop);
634
635 for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb 636 struct static_key *iterk;
d430d3d7 637
19483677
AB
638 if (within_module_init(jump_entry_code(iter), mod))
639 jump_entry_set_init(iter);
640
7dcfd915 641 iterk = jump_entry_key(iter);
c5905afb
IM
642 if (iterk == key)
643 continue;
d430d3d7 644
c5905afb 645 key = iterk;
9ae033ac 646 if (within_module((unsigned long)key, mod)) {
3821fd35 647 static_key_set_entries(key, iter);
d430d3d7 648 continue;
bf5438fc 649 }
c5905afb 650 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
d430d3d7
JB
651 if (!jlm)
652 return -ENOMEM;
3821fd35
JB
653 if (!static_key_linked(key)) {
654 jlm2 = kzalloc(sizeof(struct static_key_mod),
655 GFP_KERNEL);
656 if (!jlm2) {
657 kfree(jlm);
658 return -ENOMEM;
659 }
660 preempt_disable();
661 jlm2->mod = __module_address((unsigned long)key);
662 preempt_enable();
663 jlm2->entries = static_key_entries(key);
664 jlm2->next = NULL;
665 static_key_set_mod(key, jlm2);
666 static_key_set_linked(key);
667 }
d430d3d7
JB
668 jlm->mod = mod;
669 jlm->entries = iter;
3821fd35
JB
670 jlm->next = static_key_mod(key);
671 static_key_set_mod(key, jlm);
672 static_key_set_linked(key);
d430d3d7 673
11276d53
PZ
674 /* Only update if we've changed from our initial state */
675 if (jump_label_type(iter) != jump_label_init_type(iter))
19483677 676 __jump_label_update(key, iter, iter_stop, true);
bf5438fc 677 }
d430d3d7 678
bf5438fc
JB
679 return 0;
680}
681
d430d3d7 682static void jump_label_del_module(struct module *mod)
bf5438fc 683{
d430d3d7
JB
684 struct jump_entry *iter_start = mod->jump_entries;
685 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
686 struct jump_entry *iter;
c5905afb
IM
687 struct static_key *key = NULL;
688 struct static_key_mod *jlm, **prev;
bf5438fc 689
d430d3d7 690 for (iter = iter_start; iter < iter_stop; iter++) {
7dcfd915 691 if (jump_entry_key(iter) == key)
d430d3d7
JB
692 continue;
693
7dcfd915 694 key = jump_entry_key(iter);
d430d3d7 695
9ae033ac 696 if (within_module((unsigned long)key, mod))
d430d3d7
JB
697 continue;
698
3821fd35
JB
699 /* No memory during module load */
700 if (WARN_ON(!static_key_linked(key)))
701 continue;
702
d430d3d7 703 prev = &key->next;
3821fd35 704 jlm = static_key_mod(key);
bf5438fc 705
d430d3d7
JB
706 while (jlm && jlm->mod != mod) {
707 prev = &jlm->next;
708 jlm = jlm->next;
709 }
710
3821fd35
JB
711 /* No memory during module load */
712 if (WARN_ON(!jlm))
713 continue;
714
715 if (prev == &key->next)
716 static_key_set_mod(key, jlm->next);
717 else
d430d3d7 718 *prev = jlm->next;
3821fd35
JB
719
720 kfree(jlm);
721
722 jlm = static_key_mod(key);
723 /* if only one etry is left, fold it back into the static_key */
724 if (jlm->next == NULL) {
725 static_key_set_entries(key, jlm->entries);
726 static_key_clear_linked(key);
d430d3d7 727 kfree(jlm);
bf5438fc
JB
728 }
729 }
730}
731
732static int
733jump_label_module_notify(struct notifier_block *self, unsigned long val,
734 void *data)
735{
736 struct module *mod = data;
737 int ret = 0;
738
f2545b2d
TG
739 cpus_read_lock();
740 jump_label_lock();
741
bf5438fc
JB
742 switch (val) {
743 case MODULE_STATE_COMING:
d430d3d7 744 ret = jump_label_add_module(mod);
3821fd35 745 if (ret) {
da260fe1 746 WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
d430d3d7 747 jump_label_del_module(mod);
3821fd35 748 }
bf5438fc
JB
749 break;
750 case MODULE_STATE_GOING:
d430d3d7 751 jump_label_del_module(mod);
bf5438fc
JB
752 break;
753 }
bf5438fc 754
f2545b2d
TG
755 jump_label_unlock();
756 cpus_read_unlock();
757
d430d3d7 758 return notifier_from_errno(ret);
bf5438fc
JB
759}
760
885885f6 761static struct notifier_block jump_label_module_nb = {
bf5438fc 762 .notifier_call = jump_label_module_notify,
d430d3d7 763 .priority = 1, /* higher than tracepoints */
bf5438fc
JB
764};
765
d430d3d7 766static __init int jump_label_init_module(void)
bf5438fc
JB
767{
768 return register_module_notifier(&jump_label_module_nb);
769}
d430d3d7 770early_initcall(jump_label_init_module);
bf5438fc
JB
771
772#endif /* CONFIG_MODULES */
773
d430d3d7
JB
774/***
775 * jump_label_text_reserved - check if addr range is reserved
776 * @start: start text addr
777 * @end: end text addr
778 *
779 * checks if the text addr located between @start and @end
780 * overlaps with any of the jump label patch addresses. Code
781 * that wants to modify kernel text should first verify that
782 * it does not overlap with any of the jump label addresses.
783 * Caller must hold jump_label_mutex.
784 *
785 * returns 1 if there is an overlap, 0 otherwise
786 */
787int jump_label_text_reserved(void *start, void *end)
788{
789 int ret = __jump_label_text_reserved(__start___jump_table,
790 __stop___jump_table, start, end);
791
792 if (ret)
793 return ret;
794
795#ifdef CONFIG_MODULES
796 ret = __jump_label_mod_text_reserved(start, end);
797#endif
798 return ret;
799}
800
706249c2 801static void jump_label_update(struct static_key *key)
d430d3d7 802{
c5905afb 803 struct jump_entry *stop = __stop___jump_table;
55d2eba8 804 bool init = system_state < SYSTEM_RUNNING;
3821fd35 805 struct jump_entry *entry;
d430d3d7 806#ifdef CONFIG_MODULES
bed831f9 807 struct module *mod;
140fe3b1 808
3821fd35
JB
809 if (static_key_linked(key)) {
810 __jump_label_mod_update(key);
811 return;
812 }
140fe3b1 813
bed831f9
PZ
814 preempt_disable();
815 mod = __module_address((unsigned long)key);
55d2eba8 816 if (mod) {
140fe3b1 817 stop = mod->jump_entries + mod->num_jump_entries;
55d2eba8
PZ
818 init = mod->state == MODULE_STATE_COMING;
819 }
bed831f9 820 preempt_enable();
d430d3d7 821#endif
3821fd35 822 entry = static_key_entries(key);
140fe3b1
XG
823 /* if there are no users, entry can be NULL */
824 if (entry)
55d2eba8 825 __jump_label_update(key, entry, stop, init);
d430d3d7
JB
826}
827
1987c947
PZ
828#ifdef CONFIG_STATIC_KEYS_SELFTEST
829static DEFINE_STATIC_KEY_TRUE(sk_true);
830static DEFINE_STATIC_KEY_FALSE(sk_false);
831
832static __init int jump_label_test(void)
833{
834 int i;
835
836 for (i = 0; i < 2; i++) {
837 WARN_ON(static_key_enabled(&sk_true.key) != true);
838 WARN_ON(static_key_enabled(&sk_false.key) != false);
839
840 WARN_ON(!static_branch_likely(&sk_true));
841 WARN_ON(!static_branch_unlikely(&sk_true));
842 WARN_ON(static_branch_likely(&sk_false));
843 WARN_ON(static_branch_unlikely(&sk_false));
844
845 static_branch_disable(&sk_true);
846 static_branch_enable(&sk_false);
847
848 WARN_ON(static_key_enabled(&sk_true.key) == true);
849 WARN_ON(static_key_enabled(&sk_false.key) == false);
850
851 WARN_ON(static_branch_likely(&sk_true));
852 WARN_ON(static_branch_unlikely(&sk_true));
853 WARN_ON(!static_branch_likely(&sk_false));
854 WARN_ON(!static_branch_unlikely(&sk_false));
855
856 static_branch_enable(&sk_true);
857 static_branch_disable(&sk_false);
858 }
859
860 return 0;
861}
92ee46ef 862early_initcall(jump_label_test);
1987c947 863#endif /* STATIC_KEYS_SELFTEST */