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1 | /* | |
2 | * jump label support | |
3 | * | |
4 | * Copyright (C) 2009 Jason Baron <jbaron@redhat.com> | |
5 | * Copyright (C) 2011 Peter Zijlstra | |
6 | * | |
7 | */ | |
8 | #include <linux/memory.h> | |
9 | #include <linux/uaccess.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/list.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/sort.h> | |
14 | #include <linux/err.h> | |
15 | #include <linux/static_key.h> | |
16 | #include <linux/jump_label_ratelimit.h> | |
17 | #include <linux/bug.h> | |
18 | ||
19 | #ifdef HAVE_JUMP_LABEL | |
20 | ||
21 | /* mutex to protect coming/going of the the jump_label table */ | |
22 | static DEFINE_MUTEX(jump_label_mutex); | |
23 | ||
24 | void jump_label_lock(void) | |
25 | { | |
26 | mutex_lock(&jump_label_mutex); | |
27 | } | |
28 | ||
29 | void jump_label_unlock(void) | |
30 | { | |
31 | mutex_unlock(&jump_label_mutex); | |
32 | } | |
33 | ||
34 | static int jump_label_cmp(const void *a, const void *b) | |
35 | { | |
36 | const struct jump_entry *jea = a; | |
37 | const struct jump_entry *jeb = b; | |
38 | ||
39 | if (jea->key < jeb->key) | |
40 | return -1; | |
41 | ||
42 | if (jea->key > jeb->key) | |
43 | return 1; | |
44 | ||
45 | return 0; | |
46 | } | |
47 | ||
48 | static void | |
49 | jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) | |
50 | { | |
51 | unsigned long size; | |
52 | ||
53 | size = (((unsigned long)stop - (unsigned long)start) | |
54 | / sizeof(struct jump_entry)); | |
55 | sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL); | |
56 | } | |
57 | ||
58 | static void jump_label_update(struct static_key *key); | |
59 | ||
60 | /* | |
61 | * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h. | |
62 | * The use of 'atomic_read()' requires atomic.h and its problematic for some | |
63 | * kernel headers such as kernel.h and others. Since static_key_count() is not | |
64 | * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok | |
65 | * to have it be a function here. Similarly, for 'static_key_enable()' and | |
66 | * 'static_key_disable()', which require bug.h. This should allow jump_label.h | |
67 | * to be included from most/all places for HAVE_JUMP_LABEL. | |
68 | */ | |
69 | int static_key_count(struct static_key *key) | |
70 | { | |
71 | /* | |
72 | * -1 means the first static_key_slow_inc() is in progress. | |
73 | * static_key_enabled() must return true, so return 1 here. | |
74 | */ | |
75 | int n = atomic_read(&key->enabled); | |
76 | ||
77 | return n >= 0 ? n : 1; | |
78 | } | |
79 | EXPORT_SYMBOL_GPL(static_key_count); | |
80 | ||
81 | void static_key_enable(struct static_key *key) | |
82 | { | |
83 | int count = static_key_count(key); | |
84 | ||
85 | WARN_ON_ONCE(count < 0 || count > 1); | |
86 | ||
87 | if (!count) | |
88 | static_key_slow_inc(key); | |
89 | } | |
90 | EXPORT_SYMBOL_GPL(static_key_enable); | |
91 | ||
92 | void static_key_disable(struct static_key *key) | |
93 | { | |
94 | int count = static_key_count(key); | |
95 | ||
96 | WARN_ON_ONCE(count < 0 || count > 1); | |
97 | ||
98 | if (count) | |
99 | static_key_slow_dec(key); | |
100 | } | |
101 | EXPORT_SYMBOL_GPL(static_key_disable); | |
102 | ||
103 | void static_key_slow_inc(struct static_key *key) | |
104 | { | |
105 | int v, v1; | |
106 | ||
107 | STATIC_KEY_CHECK_USE(); | |
108 | ||
109 | /* | |
110 | * Careful if we get concurrent static_key_slow_inc() calls; | |
111 | * later calls must wait for the first one to _finish_ the | |
112 | * jump_label_update() process. At the same time, however, | |
113 | * the jump_label_update() call below wants to see | |
114 | * static_key_enabled(&key) for jumps to be updated properly. | |
115 | * | |
116 | * So give a special meaning to negative key->enabled: it sends | |
117 | * static_key_slow_inc() down the slow path, and it is non-zero | |
118 | * so it counts as "enabled" in jump_label_update(). Note that | |
119 | * atomic_inc_unless_negative() checks >= 0, so roll our own. | |
120 | */ | |
121 | for (v = atomic_read(&key->enabled); v > 0; v = v1) { | |
122 | v1 = atomic_cmpxchg(&key->enabled, v, v + 1); | |
123 | if (likely(v1 == v)) | |
124 | return; | |
125 | } | |
126 | ||
127 | jump_label_lock(); | |
128 | if (atomic_read(&key->enabled) == 0) { | |
129 | atomic_set(&key->enabled, -1); | |
130 | jump_label_update(key); | |
131 | atomic_set(&key->enabled, 1); | |
132 | } else { | |
133 | atomic_inc(&key->enabled); | |
134 | } | |
135 | jump_label_unlock(); | |
136 | } | |
137 | EXPORT_SYMBOL_GPL(static_key_slow_inc); | |
138 | ||
139 | static void __static_key_slow_dec(struct static_key *key, | |
140 | unsigned long rate_limit, struct delayed_work *work) | |
141 | { | |
142 | /* | |
143 | * The negative count check is valid even when a negative | |
144 | * key->enabled is in use by static_key_slow_inc(); a | |
145 | * __static_key_slow_dec() before the first static_key_slow_inc() | |
146 | * returns is unbalanced, because all other static_key_slow_inc() | |
147 | * instances block while the update is in progress. | |
148 | */ | |
149 | if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { | |
150 | WARN(atomic_read(&key->enabled) < 0, | |
151 | "jump label: negative count!\n"); | |
152 | return; | |
153 | } | |
154 | ||
155 | if (rate_limit) { | |
156 | atomic_inc(&key->enabled); | |
157 | schedule_delayed_work(work, rate_limit); | |
158 | } else { | |
159 | jump_label_update(key); | |
160 | } | |
161 | jump_label_unlock(); | |
162 | } | |
163 | ||
164 | static void jump_label_update_timeout(struct work_struct *work) | |
165 | { | |
166 | struct static_key_deferred *key = | |
167 | container_of(work, struct static_key_deferred, work.work); | |
168 | __static_key_slow_dec(&key->key, 0, NULL); | |
169 | } | |
170 | ||
171 | void static_key_slow_dec(struct static_key *key) | |
172 | { | |
173 | STATIC_KEY_CHECK_USE(); | |
174 | __static_key_slow_dec(key, 0, NULL); | |
175 | } | |
176 | EXPORT_SYMBOL_GPL(static_key_slow_dec); | |
177 | ||
178 | void static_key_slow_dec_deferred(struct static_key_deferred *key) | |
179 | { | |
180 | STATIC_KEY_CHECK_USE(); | |
181 | __static_key_slow_dec(&key->key, key->timeout, &key->work); | |
182 | } | |
183 | EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); | |
184 | ||
185 | void static_key_deferred_flush(struct static_key_deferred *key) | |
186 | { | |
187 | STATIC_KEY_CHECK_USE(); | |
188 | flush_delayed_work(&key->work); | |
189 | } | |
190 | EXPORT_SYMBOL_GPL(static_key_deferred_flush); | |
191 | ||
192 | void jump_label_rate_limit(struct static_key_deferred *key, | |
193 | unsigned long rl) | |
194 | { | |
195 | STATIC_KEY_CHECK_USE(); | |
196 | key->timeout = rl; | |
197 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
198 | } | |
199 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); | |
200 | ||
201 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) | |
202 | { | |
203 | if (entry->code <= (unsigned long)end && | |
204 | entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start) | |
205 | return 1; | |
206 | ||
207 | return 0; | |
208 | } | |
209 | ||
210 | static int __jump_label_text_reserved(struct jump_entry *iter_start, | |
211 | struct jump_entry *iter_stop, void *start, void *end) | |
212 | { | |
213 | struct jump_entry *iter; | |
214 | ||
215 | iter = iter_start; | |
216 | while (iter < iter_stop) { | |
217 | if (addr_conflict(iter, start, end)) | |
218 | return 1; | |
219 | iter++; | |
220 | } | |
221 | ||
222 | return 0; | |
223 | } | |
224 | ||
225 | /* | |
226 | * Update code which is definitely not currently executing. | |
227 | * Architectures which need heavyweight synchronization to modify | |
228 | * running code can override this to make the non-live update case | |
229 | * cheaper. | |
230 | */ | |
231 | void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, | |
232 | enum jump_label_type type) | |
233 | { | |
234 | arch_jump_label_transform(entry, type); | |
235 | } | |
236 | ||
237 | static inline struct jump_entry *static_key_entries(struct static_key *key) | |
238 | { | |
239 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); | |
240 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
241 | } | |
242 | ||
243 | static inline bool static_key_type(struct static_key *key) | |
244 | { | |
245 | return key->type & JUMP_TYPE_TRUE; | |
246 | } | |
247 | ||
248 | static inline bool static_key_linked(struct static_key *key) | |
249 | { | |
250 | return key->type & JUMP_TYPE_LINKED; | |
251 | } | |
252 | ||
253 | static inline void static_key_clear_linked(struct static_key *key) | |
254 | { | |
255 | key->type &= ~JUMP_TYPE_LINKED; | |
256 | } | |
257 | ||
258 | static inline void static_key_set_linked(struct static_key *key) | |
259 | { | |
260 | key->type |= JUMP_TYPE_LINKED; | |
261 | } | |
262 | ||
263 | static inline struct static_key *jump_entry_key(struct jump_entry *entry) | |
264 | { | |
265 | return (struct static_key *)((unsigned long)entry->key & ~1UL); | |
266 | } | |
267 | ||
268 | static bool jump_entry_branch(struct jump_entry *entry) | |
269 | { | |
270 | return (unsigned long)entry->key & 1UL; | |
271 | } | |
272 | ||
273 | /*** | |
274 | * A 'struct static_key' uses a union such that it either points directly | |
275 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
276 | * turn point to 'struct jump_entry' tables. | |
277 | * | |
278 | * The two lower bits of the pointer are used to keep track of which pointer | |
279 | * type is in use and to store the initial branch direction, we use an access | |
280 | * function which preserves these bits. | |
281 | */ | |
282 | static void static_key_set_entries(struct static_key *key, | |
283 | struct jump_entry *entries) | |
284 | { | |
285 | unsigned long type; | |
286 | ||
287 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
288 | type = key->type & JUMP_TYPE_MASK; | |
289 | key->entries = entries; | |
290 | key->type |= type; | |
291 | } | |
292 | ||
293 | static enum jump_label_type jump_label_type(struct jump_entry *entry) | |
294 | { | |
295 | struct static_key *key = jump_entry_key(entry); | |
296 | bool enabled = static_key_enabled(key); | |
297 | bool branch = jump_entry_branch(entry); | |
298 | ||
299 | /* See the comment in linux/jump_label.h */ | |
300 | return enabled ^ branch; | |
301 | } | |
302 | ||
303 | static void __jump_label_update(struct static_key *key, | |
304 | struct jump_entry *entry, | |
305 | struct jump_entry *stop) | |
306 | { | |
307 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
308 | /* | |
309 | * entry->code set to 0 invalidates module init text sections | |
310 | * kernel_text_address() verifies we are not in core kernel | |
311 | * init code, see jump_label_invalidate_module_init(). | |
312 | */ | |
313 | if (entry->code && kernel_text_address(entry->code)) | |
314 | arch_jump_label_transform(entry, jump_label_type(entry)); | |
315 | } | |
316 | } | |
317 | ||
318 | void __init jump_label_init(void) | |
319 | { | |
320 | struct jump_entry *iter_start = __start___jump_table; | |
321 | struct jump_entry *iter_stop = __stop___jump_table; | |
322 | struct static_key *key = NULL; | |
323 | struct jump_entry *iter; | |
324 | ||
325 | /* | |
326 | * Since we are initializing the static_key.enabled field with | |
327 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
328 | * jump_label.h, let's make sure that is safe. There are only two | |
329 | * cases to check since we initialize to 0 or 1. | |
330 | */ | |
331 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
332 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
333 | ||
334 | if (static_key_initialized) | |
335 | return; | |
336 | ||
337 | jump_label_lock(); | |
338 | jump_label_sort_entries(iter_start, iter_stop); | |
339 | ||
340 | for (iter = iter_start; iter < iter_stop; iter++) { | |
341 | struct static_key *iterk; | |
342 | ||
343 | /* rewrite NOPs */ | |
344 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
345 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
346 | ||
347 | iterk = jump_entry_key(iter); | |
348 | if (iterk == key) | |
349 | continue; | |
350 | ||
351 | key = iterk; | |
352 | static_key_set_entries(key, iter); | |
353 | } | |
354 | static_key_initialized = true; | |
355 | jump_label_unlock(); | |
356 | } | |
357 | ||
358 | #ifdef CONFIG_MODULES | |
359 | ||
360 | static enum jump_label_type jump_label_init_type(struct jump_entry *entry) | |
361 | { | |
362 | struct static_key *key = jump_entry_key(entry); | |
363 | bool type = static_key_type(key); | |
364 | bool branch = jump_entry_branch(entry); | |
365 | ||
366 | /* See the comment in linux/jump_label.h */ | |
367 | return type ^ branch; | |
368 | } | |
369 | ||
370 | struct static_key_mod { | |
371 | struct static_key_mod *next; | |
372 | struct jump_entry *entries; | |
373 | struct module *mod; | |
374 | }; | |
375 | ||
376 | static inline struct static_key_mod *static_key_mod(struct static_key *key) | |
377 | { | |
378 | WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED)); | |
379 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); | |
380 | } | |
381 | ||
382 | /*** | |
383 | * key->type and key->next are the same via union. | |
384 | * This sets key->next and preserves the type bits. | |
385 | * | |
386 | * See additional comments above static_key_set_entries(). | |
387 | */ | |
388 | static void static_key_set_mod(struct static_key *key, | |
389 | struct static_key_mod *mod) | |
390 | { | |
391 | unsigned long type; | |
392 | ||
393 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
394 | type = key->type & JUMP_TYPE_MASK; | |
395 | key->next = mod; | |
396 | key->type |= type; | |
397 | } | |
398 | ||
399 | static int __jump_label_mod_text_reserved(void *start, void *end) | |
400 | { | |
401 | struct module *mod; | |
402 | ||
403 | preempt_disable(); | |
404 | mod = __module_text_address((unsigned long)start); | |
405 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); | |
406 | preempt_enable(); | |
407 | ||
408 | if (!mod) | |
409 | return 0; | |
410 | ||
411 | ||
412 | return __jump_label_text_reserved(mod->jump_entries, | |
413 | mod->jump_entries + mod->num_jump_entries, | |
414 | start, end); | |
415 | } | |
416 | ||
417 | static void __jump_label_mod_update(struct static_key *key) | |
418 | { | |
419 | struct static_key_mod *mod; | |
420 | ||
421 | for (mod = static_key_mod(key); mod; mod = mod->next) { | |
422 | struct jump_entry *stop; | |
423 | struct module *m; | |
424 | ||
425 | /* | |
426 | * NULL if the static_key is defined in a module | |
427 | * that does not use it | |
428 | */ | |
429 | if (!mod->entries) | |
430 | continue; | |
431 | ||
432 | m = mod->mod; | |
433 | if (!m) | |
434 | stop = __stop___jump_table; | |
435 | else | |
436 | stop = m->jump_entries + m->num_jump_entries; | |
437 | __jump_label_update(key, mod->entries, stop); | |
438 | } | |
439 | } | |
440 | ||
441 | /*** | |
442 | * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() | |
443 | * @mod: module to patch | |
444 | * | |
445 | * Allow for run-time selection of the optimal nops. Before the module | |
446 | * loads patch these with arch_get_jump_label_nop(), which is specified by | |
447 | * the arch specific jump label code. | |
448 | */ | |
449 | void jump_label_apply_nops(struct module *mod) | |
450 | { | |
451 | struct jump_entry *iter_start = mod->jump_entries; | |
452 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
453 | struct jump_entry *iter; | |
454 | ||
455 | /* if the module doesn't have jump label entries, just return */ | |
456 | if (iter_start == iter_stop) | |
457 | return; | |
458 | ||
459 | for (iter = iter_start; iter < iter_stop; iter++) { | |
460 | /* Only write NOPs for arch_branch_static(). */ | |
461 | if (jump_label_init_type(iter) == JUMP_LABEL_NOP) | |
462 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
463 | } | |
464 | } | |
465 | ||
466 | static int jump_label_add_module(struct module *mod) | |
467 | { | |
468 | struct jump_entry *iter_start = mod->jump_entries; | |
469 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
470 | struct jump_entry *iter; | |
471 | struct static_key *key = NULL; | |
472 | struct static_key_mod *jlm, *jlm2; | |
473 | ||
474 | /* if the module doesn't have jump label entries, just return */ | |
475 | if (iter_start == iter_stop) | |
476 | return 0; | |
477 | ||
478 | jump_label_sort_entries(iter_start, iter_stop); | |
479 | ||
480 | for (iter = iter_start; iter < iter_stop; iter++) { | |
481 | struct static_key *iterk; | |
482 | ||
483 | iterk = jump_entry_key(iter); | |
484 | if (iterk == key) | |
485 | continue; | |
486 | ||
487 | key = iterk; | |
488 | if (within_module(iter->key, mod)) { | |
489 | static_key_set_entries(key, iter); | |
490 | continue; | |
491 | } | |
492 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); | |
493 | if (!jlm) | |
494 | return -ENOMEM; | |
495 | if (!static_key_linked(key)) { | |
496 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
497 | GFP_KERNEL); | |
498 | if (!jlm2) { | |
499 | kfree(jlm); | |
500 | return -ENOMEM; | |
501 | } | |
502 | preempt_disable(); | |
503 | jlm2->mod = __module_address((unsigned long)key); | |
504 | preempt_enable(); | |
505 | jlm2->entries = static_key_entries(key); | |
506 | jlm2->next = NULL; | |
507 | static_key_set_mod(key, jlm2); | |
508 | static_key_set_linked(key); | |
509 | } | |
510 | jlm->mod = mod; | |
511 | jlm->entries = iter; | |
512 | jlm->next = static_key_mod(key); | |
513 | static_key_set_mod(key, jlm); | |
514 | static_key_set_linked(key); | |
515 | ||
516 | /* Only update if we've changed from our initial state */ | |
517 | if (jump_label_type(iter) != jump_label_init_type(iter)) | |
518 | __jump_label_update(key, iter, iter_stop); | |
519 | } | |
520 | ||
521 | return 0; | |
522 | } | |
523 | ||
524 | static void jump_label_del_module(struct module *mod) | |
525 | { | |
526 | struct jump_entry *iter_start = mod->jump_entries; | |
527 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
528 | struct jump_entry *iter; | |
529 | struct static_key *key = NULL; | |
530 | struct static_key_mod *jlm, **prev; | |
531 | ||
532 | for (iter = iter_start; iter < iter_stop; iter++) { | |
533 | if (jump_entry_key(iter) == key) | |
534 | continue; | |
535 | ||
536 | key = jump_entry_key(iter); | |
537 | ||
538 | if (within_module(iter->key, mod)) | |
539 | continue; | |
540 | ||
541 | /* No memory during module load */ | |
542 | if (WARN_ON(!static_key_linked(key))) | |
543 | continue; | |
544 | ||
545 | prev = &key->next; | |
546 | jlm = static_key_mod(key); | |
547 | ||
548 | while (jlm && jlm->mod != mod) { | |
549 | prev = &jlm->next; | |
550 | jlm = jlm->next; | |
551 | } | |
552 | ||
553 | /* No memory during module load */ | |
554 | if (WARN_ON(!jlm)) | |
555 | continue; | |
556 | ||
557 | if (prev == &key->next) | |
558 | static_key_set_mod(key, jlm->next); | |
559 | else | |
560 | *prev = jlm->next; | |
561 | ||
562 | kfree(jlm); | |
563 | ||
564 | jlm = static_key_mod(key); | |
565 | /* if only one etry is left, fold it back into the static_key */ | |
566 | if (jlm->next == NULL) { | |
567 | static_key_set_entries(key, jlm->entries); | |
568 | static_key_clear_linked(key); | |
569 | kfree(jlm); | |
570 | } | |
571 | } | |
572 | } | |
573 | ||
574 | static void jump_label_invalidate_module_init(struct module *mod) | |
575 | { | |
576 | struct jump_entry *iter_start = mod->jump_entries; | |
577 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
578 | struct jump_entry *iter; | |
579 | ||
580 | for (iter = iter_start; iter < iter_stop; iter++) { | |
581 | if (within_module_init(iter->code, mod)) | |
582 | iter->code = 0; | |
583 | } | |
584 | } | |
585 | ||
586 | static int | |
587 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
588 | void *data) | |
589 | { | |
590 | struct module *mod = data; | |
591 | int ret = 0; | |
592 | ||
593 | switch (val) { | |
594 | case MODULE_STATE_COMING: | |
595 | jump_label_lock(); | |
596 | ret = jump_label_add_module(mod); | |
597 | if (ret) { | |
598 | WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n"); | |
599 | jump_label_del_module(mod); | |
600 | } | |
601 | jump_label_unlock(); | |
602 | break; | |
603 | case MODULE_STATE_GOING: | |
604 | jump_label_lock(); | |
605 | jump_label_del_module(mod); | |
606 | jump_label_unlock(); | |
607 | break; | |
608 | case MODULE_STATE_LIVE: | |
609 | jump_label_lock(); | |
610 | jump_label_invalidate_module_init(mod); | |
611 | jump_label_unlock(); | |
612 | break; | |
613 | } | |
614 | ||
615 | return notifier_from_errno(ret); | |
616 | } | |
617 | ||
618 | static struct notifier_block jump_label_module_nb = { | |
619 | .notifier_call = jump_label_module_notify, | |
620 | .priority = 1, /* higher than tracepoints */ | |
621 | }; | |
622 | ||
623 | static __init int jump_label_init_module(void) | |
624 | { | |
625 | return register_module_notifier(&jump_label_module_nb); | |
626 | } | |
627 | early_initcall(jump_label_init_module); | |
628 | ||
629 | #endif /* CONFIG_MODULES */ | |
630 | ||
631 | /*** | |
632 | * jump_label_text_reserved - check if addr range is reserved | |
633 | * @start: start text addr | |
634 | * @end: end text addr | |
635 | * | |
636 | * checks if the text addr located between @start and @end | |
637 | * overlaps with any of the jump label patch addresses. Code | |
638 | * that wants to modify kernel text should first verify that | |
639 | * it does not overlap with any of the jump label addresses. | |
640 | * Caller must hold jump_label_mutex. | |
641 | * | |
642 | * returns 1 if there is an overlap, 0 otherwise | |
643 | */ | |
644 | int jump_label_text_reserved(void *start, void *end) | |
645 | { | |
646 | int ret = __jump_label_text_reserved(__start___jump_table, | |
647 | __stop___jump_table, start, end); | |
648 | ||
649 | if (ret) | |
650 | return ret; | |
651 | ||
652 | #ifdef CONFIG_MODULES | |
653 | ret = __jump_label_mod_text_reserved(start, end); | |
654 | #endif | |
655 | return ret; | |
656 | } | |
657 | ||
658 | static void jump_label_update(struct static_key *key) | |
659 | { | |
660 | struct jump_entry *stop = __stop___jump_table; | |
661 | struct jump_entry *entry; | |
662 | #ifdef CONFIG_MODULES | |
663 | struct module *mod; | |
664 | ||
665 | if (static_key_linked(key)) { | |
666 | __jump_label_mod_update(key); | |
667 | return; | |
668 | } | |
669 | ||
670 | preempt_disable(); | |
671 | mod = __module_address((unsigned long)key); | |
672 | if (mod) | |
673 | stop = mod->jump_entries + mod->num_jump_entries; | |
674 | preempt_enable(); | |
675 | #endif | |
676 | entry = static_key_entries(key); | |
677 | /* if there are no users, entry can be NULL */ | |
678 | if (entry) | |
679 | __jump_label_update(key, entry, stop); | |
680 | } | |
681 | ||
682 | #ifdef CONFIG_STATIC_KEYS_SELFTEST | |
683 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
684 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
685 | ||
686 | static __init int jump_label_test(void) | |
687 | { | |
688 | int i; | |
689 | ||
690 | for (i = 0; i < 2; i++) { | |
691 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
692 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
693 | ||
694 | WARN_ON(!static_branch_likely(&sk_true)); | |
695 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
696 | WARN_ON(static_branch_likely(&sk_false)); | |
697 | WARN_ON(static_branch_unlikely(&sk_false)); | |
698 | ||
699 | static_branch_disable(&sk_true); | |
700 | static_branch_enable(&sk_false); | |
701 | ||
702 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
703 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
704 | ||
705 | WARN_ON(static_branch_likely(&sk_true)); | |
706 | WARN_ON(static_branch_unlikely(&sk_true)); | |
707 | WARN_ON(!static_branch_likely(&sk_false)); | |
708 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
709 | ||
710 | static_branch_enable(&sk_true); | |
711 | static_branch_disable(&sk_false); | |
712 | } | |
713 | ||
714 | return 0; | |
715 | } | |
716 | late_initcall(jump_label_test); | |
717 | #endif /* STATIC_KEYS_SELFTEST */ | |
718 | ||
719 | #endif /* HAVE_JUMP_LABEL */ |