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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 311 if (jump_entry_code(entry) <= (unsigned long)end &&
fa5e5dc3 312 jump_entry_code(entry) + jump_entry_size(entry) > (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))) {
38c93587
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;
5af0ea29 486 bool in_init;
37348804 487
11276d53
PZ
488 /* rewrite NOPs */
489 if (jump_label_type(iter) == JUMP_LABEL_NOP)
490 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
491
5af0ea29
PZ
492 in_init = init_section_contains((void *)jump_entry_code(iter), 1);
493 jump_entry_set_init(iter, in_init);
19483677 494
7dcfd915 495 iterk = jump_entry_key(iter);
37348804 496 if (iterk == key)
d430d3d7
JB
497 continue;
498
37348804 499 key = iterk;
3821fd35 500 static_key_set_entries(key, iter);
bf5438fc 501 }
c4b2c0c5 502 static_key_initialized = true;
91bad2f8 503 jump_label_unlock();
f2545b2d 504 cpus_read_unlock();
bf5438fc 505}
bf5438fc
JB
506
507#ifdef CONFIG_MODULES
508
11276d53
PZ
509static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
510{
511 struct static_key *key = jump_entry_key(entry);
512 bool type = static_key_type(key);
9ae033ac 513 bool branch = jump_entry_is_branch(entry);
11276d53
PZ
514
515 /* See the comment in linux/jump_label.h */
516 return type ^ branch;
517}
518
c5905afb
IM
519struct static_key_mod {
520 struct static_key_mod *next;
d430d3d7
JB
521 struct jump_entry *entries;
522 struct module *mod;
523};
524
3821fd35
JB
525static inline struct static_key_mod *static_key_mod(struct static_key *key)
526{
34e12b86 527 WARN_ON_ONCE(!static_key_linked(key));
3821fd35
JB
528 return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK);
529}
530
531/***
532 * key->type and key->next are the same via union.
533 * This sets key->next and preserves the type bits.
534 *
535 * See additional comments above static_key_set_entries().
536 */
537static void static_key_set_mod(struct static_key *key,
538 struct static_key_mod *mod)
539{
540 unsigned long type;
541
542 WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK);
543 type = key->type & JUMP_TYPE_MASK;
544 key->next = mod;
545 key->type |= type;
546}
547
d430d3d7
JB
548static int __jump_label_mod_text_reserved(void *start, void *end)
549{
550 struct module *mod;
0db6e373 551 int ret;
d430d3d7 552
bdc9f373 553 preempt_disable();
d430d3d7 554 mod = __module_text_address((unsigned long)start);
bdc9f373 555 WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
0db6e373
PZ
556 if (!try_module_get(mod))
557 mod = NULL;
bdc9f373
RR
558 preempt_enable();
559
d430d3d7
JB
560 if (!mod)
561 return 0;
562
0db6e373 563 ret = __jump_label_text_reserved(mod->jump_entries,
d430d3d7
JB
564 mod->jump_entries + mod->num_jump_entries,
565 start, end);
0db6e373
PZ
566
567 module_put(mod);
568
569 return ret;
d430d3d7
JB
570}
571
706249c2 572static void __jump_label_mod_update(struct static_key *key)
d430d3d7 573{
706249c2 574 struct static_key_mod *mod;
d430d3d7 575
3821fd35
JB
576 for (mod = static_key_mod(key); mod; mod = mod->next) {
577 struct jump_entry *stop;
578 struct module *m;
579
580 /*
581 * NULL if the static_key is defined in a module
582 * that does not use it
583 */
584 if (!mod->entries)
585 continue;
7cbc5b8d 586
3821fd35
JB
587 m = mod->mod;
588 if (!m)
589 stop = __stop___jump_table;
590 else
591 stop = m->jump_entries + m->num_jump_entries;
19483677 592 __jump_label_update(key, mod->entries, stop,
77ac1c02 593 m && m->state == MODULE_STATE_COMING);
d430d3d7
JB
594 }
595}
596
597/***
598 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
599 * @mod: module to patch
600 *
601 * Allow for run-time selection of the optimal nops. Before the module
602 * loads patch these with arch_get_jump_label_nop(), which is specified by
603 * the arch specific jump label code.
604 */
605void jump_label_apply_nops(struct module *mod)
bf5438fc 606{
d430d3d7
JB
607 struct jump_entry *iter_start = mod->jump_entries;
608 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
609 struct jump_entry *iter;
610
611 /* if the module doesn't have jump label entries, just return */
612 if (iter_start == iter_stop)
613 return;
614
11276d53
PZ
615 for (iter = iter_start; iter < iter_stop; iter++) {
616 /* Only write NOPs for arch_branch_static(). */
617 if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
618 arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
619 }
bf5438fc
JB
620}
621
d430d3d7 622static int jump_label_add_module(struct module *mod)
bf5438fc 623{
d430d3d7
JB
624 struct jump_entry *iter_start = mod->jump_entries;
625 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
626 struct jump_entry *iter;
c5905afb 627 struct static_key *key = NULL;
3821fd35 628 struct static_key_mod *jlm, *jlm2;
bf5438fc
JB
629
630 /* if the module doesn't have jump label entries, just return */
d430d3d7 631 if (iter_start == iter_stop)
bf5438fc
JB
632 return 0;
633
d430d3d7
JB
634 jump_label_sort_entries(iter_start, iter_stop);
635
636 for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb 637 struct static_key *iterk;
5af0ea29 638 bool in_init;
d430d3d7 639
5af0ea29
PZ
640 in_init = within_module_init(jump_entry_code(iter), mod);
641 jump_entry_set_init(iter, in_init);
19483677 642
7dcfd915 643 iterk = jump_entry_key(iter);
c5905afb
IM
644 if (iterk == key)
645 continue;
d430d3d7 646
c5905afb 647 key = iterk;
9ae033ac 648 if (within_module((unsigned long)key, mod)) {
3821fd35 649 static_key_set_entries(key, iter);
d430d3d7 650 continue;
bf5438fc 651 }
c5905afb 652 jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
d430d3d7
JB
653 if (!jlm)
654 return -ENOMEM;
3821fd35
JB
655 if (!static_key_linked(key)) {
656 jlm2 = kzalloc(sizeof(struct static_key_mod),
657 GFP_KERNEL);
658 if (!jlm2) {
659 kfree(jlm);
660 return -ENOMEM;
661 }
662 preempt_disable();
663 jlm2->mod = __module_address((unsigned long)key);
664 preempt_enable();
665 jlm2->entries = static_key_entries(key);
666 jlm2->next = NULL;
667 static_key_set_mod(key, jlm2);
668 static_key_set_linked(key);
669 }
d430d3d7
JB
670 jlm->mod = mod;
671 jlm->entries = iter;
3821fd35
JB
672 jlm->next = static_key_mod(key);
673 static_key_set_mod(key, jlm);
674 static_key_set_linked(key);
d430d3d7 675
11276d53
PZ
676 /* Only update if we've changed from our initial state */
677 if (jump_label_type(iter) != jump_label_init_type(iter))
19483677 678 __jump_label_update(key, iter, iter_stop, true);
bf5438fc 679 }
d430d3d7 680
bf5438fc
JB
681 return 0;
682}
683
d430d3d7 684static void jump_label_del_module(struct module *mod)
bf5438fc 685{
d430d3d7
JB
686 struct jump_entry *iter_start = mod->jump_entries;
687 struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
688 struct jump_entry *iter;
c5905afb
IM
689 struct static_key *key = NULL;
690 struct static_key_mod *jlm, **prev;
bf5438fc 691
d430d3d7 692 for (iter = iter_start; iter < iter_stop; iter++) {
7dcfd915 693 if (jump_entry_key(iter) == key)
d430d3d7
JB
694 continue;
695
7dcfd915 696 key = jump_entry_key(iter);
d430d3d7 697
9ae033ac 698 if (within_module((unsigned long)key, mod))
d430d3d7
JB
699 continue;
700
3821fd35
JB
701 /* No memory during module load */
702 if (WARN_ON(!static_key_linked(key)))
703 continue;
704
d430d3d7 705 prev = &key->next;
3821fd35 706 jlm = static_key_mod(key);
bf5438fc 707
d430d3d7
JB
708 while (jlm && jlm->mod != mod) {
709 prev = &jlm->next;
710 jlm = jlm->next;
711 }
712
3821fd35
JB
713 /* No memory during module load */
714 if (WARN_ON(!jlm))
715 continue;
716
717 if (prev == &key->next)
718 static_key_set_mod(key, jlm->next);
719 else
d430d3d7 720 *prev = jlm->next;
3821fd35
JB
721
722 kfree(jlm);
723
724 jlm = static_key_mod(key);
725 /* if only one etry is left, fold it back into the static_key */
726 if (jlm->next == NULL) {
727 static_key_set_entries(key, jlm->entries);
728 static_key_clear_linked(key);
d430d3d7 729 kfree(jlm);
bf5438fc
JB
730 }
731 }
732}
733
734static int
735jump_label_module_notify(struct notifier_block *self, unsigned long val,
736 void *data)
737{
738 struct module *mod = data;
739 int ret = 0;
740
f2545b2d
TG
741 cpus_read_lock();
742 jump_label_lock();
743
bf5438fc
JB
744 switch (val) {
745 case MODULE_STATE_COMING:
d430d3d7 746 ret = jump_label_add_module(mod);
3821fd35 747 if (ret) {
da260fe1 748 WARN(1, "Failed to allocate memory: jump_label may not work properly.\n");
d430d3d7 749 jump_label_del_module(mod);
3821fd35 750 }
bf5438fc
JB
751 break;
752 case MODULE_STATE_GOING:
d430d3d7 753 jump_label_del_module(mod);
bf5438fc
JB
754 break;
755 }
bf5438fc 756
f2545b2d
TG
757 jump_label_unlock();
758 cpus_read_unlock();
759
d430d3d7 760 return notifier_from_errno(ret);
bf5438fc
JB
761}
762
885885f6 763static struct notifier_block jump_label_module_nb = {
bf5438fc 764 .notifier_call = jump_label_module_notify,
d430d3d7 765 .priority = 1, /* higher than tracepoints */
bf5438fc
JB
766};
767
d430d3d7 768static __init int jump_label_init_module(void)
bf5438fc
JB
769{
770 return register_module_notifier(&jump_label_module_nb);
771}
d430d3d7 772early_initcall(jump_label_init_module);
bf5438fc
JB
773
774#endif /* CONFIG_MODULES */
775
d430d3d7
JB
776/***
777 * jump_label_text_reserved - check if addr range is reserved
778 * @start: start text addr
779 * @end: end text addr
780 *
781 * checks if the text addr located between @start and @end
782 * overlaps with any of the jump label patch addresses. Code
783 * that wants to modify kernel text should first verify that
784 * it does not overlap with any of the jump label addresses.
785 * Caller must hold jump_label_mutex.
786 *
787 * returns 1 if there is an overlap, 0 otherwise
788 */
789int jump_label_text_reserved(void *start, void *end)
790{
791 int ret = __jump_label_text_reserved(__start___jump_table,
792 __stop___jump_table, start, end);
793
794 if (ret)
795 return ret;
796
797#ifdef CONFIG_MODULES
798 ret = __jump_label_mod_text_reserved(start, end);
799#endif
800 return ret;
801}
802
706249c2 803static void jump_label_update(struct static_key *key)
d430d3d7 804{
c5905afb 805 struct jump_entry *stop = __stop___jump_table;
55d2eba8 806 bool init = system_state < SYSTEM_RUNNING;
3821fd35 807 struct jump_entry *entry;
d430d3d7 808#ifdef CONFIG_MODULES
bed831f9 809 struct module *mod;
140fe3b1 810
3821fd35
JB
811 if (static_key_linked(key)) {
812 __jump_label_mod_update(key);
813 return;
814 }
140fe3b1 815
bed831f9
PZ
816 preempt_disable();
817 mod = __module_address((unsigned long)key);
55d2eba8 818 if (mod) {
140fe3b1 819 stop = mod->jump_entries + mod->num_jump_entries;
55d2eba8
PZ
820 init = mod->state == MODULE_STATE_COMING;
821 }
bed831f9 822 preempt_enable();
d430d3d7 823#endif
3821fd35 824 entry = static_key_entries(key);
140fe3b1
XG
825 /* if there are no users, entry can be NULL */
826 if (entry)
55d2eba8 827 __jump_label_update(key, entry, stop, init);
d430d3d7
JB
828}
829
1987c947
PZ
830#ifdef CONFIG_STATIC_KEYS_SELFTEST
831static DEFINE_STATIC_KEY_TRUE(sk_true);
832static DEFINE_STATIC_KEY_FALSE(sk_false);
833
834static __init int jump_label_test(void)
835{
836 int i;
837
838 for (i = 0; i < 2; i++) {
839 WARN_ON(static_key_enabled(&sk_true.key) != true);
840 WARN_ON(static_key_enabled(&sk_false.key) != false);
841
842 WARN_ON(!static_branch_likely(&sk_true));
843 WARN_ON(!static_branch_unlikely(&sk_true));
844 WARN_ON(static_branch_likely(&sk_false));
845 WARN_ON(static_branch_unlikely(&sk_false));
846
847 static_branch_disable(&sk_true);
848 static_branch_enable(&sk_false);
849
850 WARN_ON(static_key_enabled(&sk_true.key) == true);
851 WARN_ON(static_key_enabled(&sk_false.key) == false);
852
853 WARN_ON(static_branch_likely(&sk_true));
854 WARN_ON(static_branch_unlikely(&sk_true));
855 WARN_ON(!static_branch_likely(&sk_false));
856 WARN_ON(!static_branch_unlikely(&sk_false));
857
858 static_branch_enable(&sk_true);
859 static_branch_disable(&sk_false);
860 }
861
862 return 0;
863}
92ee46ef 864early_initcall(jump_label_test);
1987c947 865#endif /* STATIC_KEYS_SELFTEST */