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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 |
23 | static DEFINE_MUTEX(jump_label_mutex); |
24 | ||
91bad2f8 JB |
25 | void jump_label_lock(void) |
26 | { | |
27 | mutex_lock(&jump_label_mutex); | |
28 | } | |
29 | ||
30 | void jump_label_unlock(void) | |
31 | { | |
32 | mutex_unlock(&jump_label_mutex); | |
33 | } | |
34 | ||
bf5438fc JB |
35 | static int jump_label_cmp(const void *a, const void *b) |
36 | { | |
37 | const struct jump_entry *jea = a; | |
38 | const struct jump_entry *jeb = b; | |
39 | ||
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 |
63 | static void jump_label_swap(void *a, void *b, int size) |
64 | { | |
65 | long delta = (unsigned long)a - (unsigned long)b; | |
66 | struct jump_entry *jea = a; | |
67 | struct jump_entry *jeb = b; | |
68 | struct jump_entry tmp = *jea; | |
69 | ||
70 | jea->code = jeb->code - delta; | |
71 | jea->target = jeb->target - delta; | |
72 | jea->key = jeb->key - delta; | |
73 | ||
74 | jeb->code = tmp.code + delta; | |
75 | jeb->target = tmp.target + delta; | |
76 | jeb->key = tmp.key + delta; | |
77 | } | |
78 | ||
bf5438fc | 79 | static void |
d430d3d7 | 80 | jump_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 | 93 | static 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 | */ |
104 | int static_key_count(struct static_key *key) | |
105 | { | |
106 | /* | |
107 | * -1 means the first static_key_slow_inc() is in progress. | |
108 | * static_key_enabled() must return true, so return 1 here. | |
109 | */ | |
110 | int n = atomic_read(&key->enabled); | |
111 | ||
112 | return n >= 0 ? n : 1; | |
113 | } | |
114 | EXPORT_SYMBOL_GPL(static_key_count); | |
115 | ||
eb8c5072 DS |
116 | /* |
117 | * static_key_fast_inc_not_disabled - adds a user for a static key | |
118 | * @key: static key that must be already enabled | |
119 | * | |
120 | * The caller must make sure that the static key can't get disabled while | |
121 | * in this function. It doesn't patch jump labels, only adds a user to | |
122 | * an already enabled static key. | |
123 | * | |
124 | * Returns true if the increment was done. Unlike refcount_t the ref counter | |
125 | * is not saturated, but will fail to increment on overflow. | |
126 | */ | |
127 | bool static_key_fast_inc_not_disabled(struct static_key *key) | |
bf5438fc | 128 | { |
eb8c5072 DS |
129 | int v; |
130 | ||
5cdda511 | 131 | STATIC_KEY_CHECK_USE(key); |
eb8c5072 DS |
132 | /* |
133 | * Negative key->enabled has a special meaning: it sends | |
134 | * static_key_slow_inc() down the slow path, and it is non-zero | |
135 | * so it counts as "enabled" in jump_label_update(). Note that | |
136 | * atomic_inc_unless_negative() checks >= 0, so roll our own. | |
137 | */ | |
138 | v = atomic_read(&key->enabled); | |
139 | do { | |
140 | if (v <= 0 || (v + 1) < 0) | |
141 | return false; | |
142 | } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1))); | |
143 | ||
144 | return true; | |
145 | } | |
146 | EXPORT_SYMBOL_GPL(static_key_fast_inc_not_disabled); | |
147 | ||
148 | bool static_key_slow_inc_cpuslocked(struct static_key *key) | |
149 | { | |
cb538267 | 150 | lockdep_assert_cpus_held(); |
4c5ea0a9 PB |
151 | |
152 | /* | |
153 | * Careful if we get concurrent static_key_slow_inc() calls; | |
154 | * later calls must wait for the first one to _finish_ the | |
155 | * jump_label_update() process. At the same time, however, | |
156 | * the jump_label_update() call below wants to see | |
157 | * static_key_enabled(&key) for jumps to be updated properly. | |
4c5ea0a9 | 158 | */ |
eb8c5072 DS |
159 | if (static_key_fast_inc_not_disabled(key)) |
160 | return true; | |
bf5438fc | 161 | |
d430d3d7 | 162 | jump_label_lock(); |
4c5ea0a9 PB |
163 | if (atomic_read(&key->enabled) == 0) { |
164 | atomic_set(&key->enabled, -1); | |
706249c2 | 165 | jump_label_update(key); |
d0646a6f PZ |
166 | /* |
167 | * Ensure that if the above cmpxchg loop observes our positive | |
168 | * value, it must also observe all the text changes. | |
169 | */ | |
170 | atomic_set_release(&key->enabled, 1); | |
4c5ea0a9 | 171 | } else { |
eb8c5072 DS |
172 | if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key))) { |
173 | jump_label_unlock(); | |
174 | return false; | |
175 | } | |
4c5ea0a9 | 176 | } |
d430d3d7 | 177 | jump_label_unlock(); |
eb8c5072 | 178 | return true; |
8b7b4128 MZ |
179 | } |
180 | ||
eb8c5072 | 181 | bool static_key_slow_inc(struct static_key *key) |
8b7b4128 | 182 | { |
eb8c5072 DS |
183 | bool ret; |
184 | ||
8b7b4128 | 185 | cpus_read_lock(); |
eb8c5072 | 186 | ret = static_key_slow_inc_cpuslocked(key); |
f2545b2d | 187 | cpus_read_unlock(); |
eb8c5072 | 188 | return ret; |
bf5438fc | 189 | } |
c5905afb | 190 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
bf5438fc | 191 | |
5a40527f | 192 | void static_key_enable_cpuslocked(struct static_key *key) |
1dbb6704 | 193 | { |
5cdda511 | 194 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 195 | lockdep_assert_cpus_held(); |
5a40527f | 196 | |
1dbb6704 PB |
197 | if (atomic_read(&key->enabled) > 0) { |
198 | WARN_ON_ONCE(atomic_read(&key->enabled) != 1); | |
199 | return; | |
200 | } | |
201 | ||
1dbb6704 PB |
202 | jump_label_lock(); |
203 | if (atomic_read(&key->enabled) == 0) { | |
204 | atomic_set(&key->enabled, -1); | |
205 | jump_label_update(key); | |
d0646a6f PZ |
206 | /* |
207 | * See static_key_slow_inc(). | |
208 | */ | |
209 | atomic_set_release(&key->enabled, 1); | |
1dbb6704 PB |
210 | } |
211 | jump_label_unlock(); | |
5a40527f MZ |
212 | } |
213 | EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked); | |
214 | ||
215 | void static_key_enable(struct static_key *key) | |
216 | { | |
217 | cpus_read_lock(); | |
218 | static_key_enable_cpuslocked(key); | |
1dbb6704 PB |
219 | cpus_read_unlock(); |
220 | } | |
221 | EXPORT_SYMBOL_GPL(static_key_enable); | |
222 | ||
5a40527f | 223 | void static_key_disable_cpuslocked(struct static_key *key) |
1dbb6704 | 224 | { |
5cdda511 | 225 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 226 | lockdep_assert_cpus_held(); |
5a40527f | 227 | |
1dbb6704 PB |
228 | if (atomic_read(&key->enabled) != 1) { |
229 | WARN_ON_ONCE(atomic_read(&key->enabled) != 0); | |
230 | return; | |
231 | } | |
232 | ||
1dbb6704 PB |
233 | jump_label_lock(); |
234 | if (atomic_cmpxchg(&key->enabled, 1, 0)) | |
235 | jump_label_update(key); | |
236 | jump_label_unlock(); | |
5a40527f MZ |
237 | } |
238 | EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked); | |
239 | ||
240 | void static_key_disable(struct static_key *key) | |
241 | { | |
242 | cpus_read_lock(); | |
243 | static_key_disable_cpuslocked(key); | |
1dbb6704 PB |
244 | cpus_read_unlock(); |
245 | } | |
246 | EXPORT_SYMBOL_GPL(static_key_disable); | |
247 | ||
b92e793b | 248 | static bool static_key_slow_try_dec(struct static_key *key) |
bf5438fc | 249 | { |
a1247d06 PZ |
250 | int val; |
251 | ||
b92e793b JK |
252 | val = atomic_fetch_add_unless(&key->enabled, -1, 1); |
253 | if (val == 1) | |
254 | return false; | |
cb538267 | 255 | |
4c5ea0a9 PB |
256 | /* |
257 | * The negative count check is valid even when a negative | |
258 | * key->enabled is in use by static_key_slow_inc(); a | |
259 | * __static_key_slow_dec() before the first static_key_slow_inc() | |
260 | * returns is unbalanced, because all other static_key_slow_inc() | |
261 | * instances block while the update is in progress. | |
262 | */ | |
b92e793b JK |
263 | WARN(val < 0, "jump label: negative count!\n"); |
264 | return true; | |
265 | } | |
266 | ||
94b5f312 | 267 | static void __static_key_slow_dec_cpuslocked(struct static_key *key) |
b92e793b JK |
268 | { |
269 | lockdep_assert_cpus_held(); | |
270 | ||
271 | if (static_key_slow_try_dec(key)) | |
d430d3d7 | 272 | return; |
bf5438fc | 273 | |
a1247d06 | 274 | jump_label_lock(); |
94b5f312 JK |
275 | if (atomic_dec_and_test(&key->enabled)) |
276 | jump_label_update(key); | |
91bad2f8 | 277 | jump_label_unlock(); |
8b7b4128 MZ |
278 | } |
279 | ||
94b5f312 | 280 | static void __static_key_slow_dec(struct static_key *key) |
8b7b4128 MZ |
281 | { |
282 | cpus_read_lock(); | |
94b5f312 | 283 | __static_key_slow_dec_cpuslocked(key); |
f2545b2d | 284 | cpus_read_unlock(); |
bf5438fc JB |
285 | } |
286 | ||
ad282a81 | 287 | void jump_label_update_timeout(struct work_struct *work) |
b2029520 | 288 | { |
c5905afb IM |
289 | struct static_key_deferred *key = |
290 | container_of(work, struct static_key_deferred, work.work); | |
94b5f312 | 291 | __static_key_slow_dec(&key->key); |
b2029520 | 292 | } |
ad282a81 | 293 | EXPORT_SYMBOL_GPL(jump_label_update_timeout); |
b2029520 | 294 | |
c5905afb | 295 | void static_key_slow_dec(struct static_key *key) |
b2029520 | 296 | { |
5cdda511 | 297 | STATIC_KEY_CHECK_USE(key); |
94b5f312 | 298 | __static_key_slow_dec(key); |
b2029520 | 299 | } |
c5905afb | 300 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
b2029520 | 301 | |
ce48c146 PZ |
302 | void static_key_slow_dec_cpuslocked(struct static_key *key) |
303 | { | |
304 | STATIC_KEY_CHECK_USE(key); | |
94b5f312 | 305 | __static_key_slow_dec_cpuslocked(key); |
ce48c146 PZ |
306 | } |
307 | ||
ad282a81 JK |
308 | void __static_key_slow_dec_deferred(struct static_key *key, |
309 | struct delayed_work *work, | |
310 | unsigned long timeout) | |
b2029520 | 311 | { |
5cdda511 | 312 | STATIC_KEY_CHECK_USE(key); |
94b5f312 JK |
313 | |
314 | if (static_key_slow_try_dec(key)) | |
315 | return; | |
316 | ||
317 | schedule_delayed_work(work, timeout); | |
b2029520 | 318 | } |
ad282a81 | 319 | EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); |
b2029520 | 320 | |
ad282a81 | 321 | void __static_key_deferred_flush(void *key, struct delayed_work *work) |
b6416e61 | 322 | { |
5cdda511 | 323 | STATIC_KEY_CHECK_USE(key); |
ad282a81 | 324 | flush_delayed_work(work); |
b6416e61 | 325 | } |
ad282a81 | 326 | EXPORT_SYMBOL_GPL(__static_key_deferred_flush); |
b6416e61 | 327 | |
c5905afb | 328 | void jump_label_rate_limit(struct static_key_deferred *key, |
b2029520 GN |
329 | unsigned long rl) |
330 | { | |
5cdda511 | 331 | STATIC_KEY_CHECK_USE(key); |
b2029520 GN |
332 | key->timeout = rl; |
333 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
334 | } | |
a181dc14 | 335 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
b2029520 | 336 | |
4c3ef6d7 JB |
337 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
338 | { | |
9ae033ac | 339 | if (jump_entry_code(entry) <= (unsigned long)end && |
fa5e5dc3 | 340 | jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start) |
4c3ef6d7 JB |
341 | return 1; |
342 | ||
343 | return 0; | |
344 | } | |
345 | ||
d430d3d7 | 346 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
9e667624 | 347 | struct jump_entry *iter_stop, void *start, void *end, bool init) |
4c3ef6d7 | 348 | { |
4c3ef6d7 | 349 | struct jump_entry *iter; |
4c3ef6d7 | 350 | |
4c3ef6d7 JB |
351 | iter = iter_start; |
352 | while (iter < iter_stop) { | |
9e667624 PZ |
353 | if (init || !jump_entry_is_init(iter)) { |
354 | if (addr_conflict(iter, start, end)) | |
355 | return 1; | |
356 | } | |
4c3ef6d7 JB |
357 | iter++; |
358 | } | |
359 | ||
d430d3d7 JB |
360 | return 0; |
361 | } | |
362 | ||
7e6b9db2 AB |
363 | #ifndef arch_jump_label_transform_static |
364 | static void arch_jump_label_transform_static(struct jump_entry *entry, | |
365 | enum jump_label_type type) | |
20284aa7 | 366 | { |
7e6b9db2 | 367 | /* nothing to do on most architectures */ |
20284aa7 | 368 | } |
7e6b9db2 | 369 | #endif |
20284aa7 | 370 | |
706249c2 | 371 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
d430d3d7 | 372 | { |
3821fd35 JB |
373 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
374 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
4c3ef6d7 JB |
375 | } |
376 | ||
706249c2 | 377 | static inline bool static_key_type(struct static_key *key) |
c5905afb | 378 | { |
3821fd35 JB |
379 | return key->type & JUMP_TYPE_TRUE; |
380 | } | |
381 | ||
382 | static inline bool static_key_linked(struct static_key *key) | |
383 | { | |
384 | return key->type & JUMP_TYPE_LINKED; | |
385 | } | |
386 | ||
387 | static inline void static_key_clear_linked(struct static_key *key) | |
388 | { | |
389 | key->type &= ~JUMP_TYPE_LINKED; | |
390 | } | |
391 | ||
392 | static inline void static_key_set_linked(struct static_key *key) | |
393 | { | |
394 | key->type |= JUMP_TYPE_LINKED; | |
a1efb01f | 395 | } |
c5905afb | 396 | |
3821fd35 JB |
397 | /*** |
398 | * A 'struct static_key' uses a union such that it either points directly | |
399 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
400 | * turn point to 'struct jump_entry' tables. | |
401 | * | |
402 | * The two lower bits of the pointer are used to keep track of which pointer | |
403 | * type is in use and to store the initial branch direction, we use an access | |
404 | * function which preserves these bits. | |
405 | */ | |
406 | static void static_key_set_entries(struct static_key *key, | |
407 | struct jump_entry *entries) | |
408 | { | |
409 | unsigned long type; | |
410 | ||
411 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
412 | type = key->type & JUMP_TYPE_MASK; | |
413 | key->entries = entries; | |
414 | key->type |= type; | |
415 | } | |
416 | ||
706249c2 | 417 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
a1efb01f | 418 | { |
706249c2 | 419 | struct static_key *key = jump_entry_key(entry); |
a1efb01f | 420 | bool enabled = static_key_enabled(key); |
9ae033ac | 421 | bool branch = jump_entry_is_branch(entry); |
c5905afb | 422 | |
11276d53 PZ |
423 | /* See the comment in linux/jump_label.h */ |
424 | return enabled ^ branch; | |
c5905afb IM |
425 | } |
426 | ||
e1aacb3f DBO |
427 | static bool jump_label_can_update(struct jump_entry *entry, bool init) |
428 | { | |
429 | /* | |
430 | * Cannot update code that was in an init text area. | |
431 | */ | |
432 | if (!init && jump_entry_is_init(entry)) | |
433 | return false; | |
434 | ||
435 | if (!kernel_text_address(jump_entry_code(entry))) { | |
38c93587 PZ |
436 | /* |
437 | * This skips patching built-in __exit, which | |
438 | * is part of init_section_contains() but is | |
439 | * not part of kernel_text_address(). | |
440 | * | |
441 | * Skipping built-in __exit is fine since it | |
442 | * will never be executed. | |
443 | */ | |
8f35eaa5 AM |
444 | WARN_ONCE(!jump_entry_is_init(entry), |
445 | "can't patch jump_label at %pS", | |
446 | (void *)jump_entry_code(entry)); | |
e1aacb3f DBO |
447 | return false; |
448 | } | |
449 | ||
450 | return true; | |
451 | } | |
452 | ||
c2ba8a15 | 453 | #ifndef HAVE_JUMP_LABEL_BATCH |
706249c2 PZ |
454 | static void __jump_label_update(struct static_key *key, |
455 | struct jump_entry *entry, | |
19483677 AB |
456 | struct jump_entry *stop, |
457 | bool init) | |
706249c2 PZ |
458 | { |
459 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
e1aacb3f DBO |
460 | if (jump_label_can_update(entry, init)) |
461 | arch_jump_label_transform(entry, jump_label_type(entry)); | |
706249c2 PZ |
462 | } |
463 | } | |
c2ba8a15 DBO |
464 | #else |
465 | static void __jump_label_update(struct static_key *key, | |
466 | struct jump_entry *entry, | |
467 | struct jump_entry *stop, | |
468 | bool init) | |
469 | { | |
470 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
471 | ||
472 | if (!jump_label_can_update(entry, init)) | |
473 | continue; | |
474 | ||
475 | if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) { | |
476 | /* | |
477 | * Queue is full: Apply the current queue and try again. | |
478 | */ | |
479 | arch_jump_label_transform_apply(); | |
480 | BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry))); | |
481 | } | |
482 | } | |
483 | arch_jump_label_transform_apply(); | |
484 | } | |
485 | #endif | |
706249c2 | 486 | |
97ce2c88 | 487 | void __init jump_label_init(void) |
bf5438fc | 488 | { |
bf5438fc JB |
489 | struct jump_entry *iter_start = __start___jump_table; |
490 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 491 | struct static_key *key = NULL; |
bf5438fc JB |
492 | struct jump_entry *iter; |
493 | ||
1f69bf9c JB |
494 | /* |
495 | * Since we are initializing the static_key.enabled field with | |
496 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
497 | * jump_label.h, let's make sure that is safe. There are only two | |
498 | * cases to check since we initialize to 0 or 1. | |
499 | */ | |
500 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
501 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
502 | ||
e3f91083 KH |
503 | if (static_key_initialized) |
504 | return; | |
505 | ||
f2545b2d | 506 | cpus_read_lock(); |
91bad2f8 | 507 | jump_label_lock(); |
d430d3d7 JB |
508 | jump_label_sort_entries(iter_start, iter_stop); |
509 | ||
510 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 511 | struct static_key *iterk; |
5af0ea29 | 512 | bool in_init; |
37348804 | 513 | |
11276d53 PZ |
514 | /* rewrite NOPs */ |
515 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
516 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
517 | ||
5af0ea29 PZ |
518 | in_init = init_section_contains((void *)jump_entry_code(iter), 1); |
519 | jump_entry_set_init(iter, in_init); | |
19483677 | 520 | |
7dcfd915 | 521 | iterk = jump_entry_key(iter); |
37348804 | 522 | if (iterk == key) |
d430d3d7 JB |
523 | continue; |
524 | ||
37348804 | 525 | key = iterk; |
3821fd35 | 526 | static_key_set_entries(key, iter); |
bf5438fc | 527 | } |
c4b2c0c5 | 528 | static_key_initialized = true; |
91bad2f8 | 529 | jump_label_unlock(); |
f2545b2d | 530 | cpus_read_unlock(); |
bf5438fc | 531 | } |
bf5438fc | 532 | |
91a1d97e PZ |
533 | static inline bool static_key_sealed(struct static_key *key) |
534 | { | |
535 | return (key->type & JUMP_TYPE_LINKED) && !(key->type & ~JUMP_TYPE_MASK); | |
536 | } | |
537 | ||
538 | static inline void static_key_seal(struct static_key *key) | |
539 | { | |
540 | unsigned long type = key->type & JUMP_TYPE_TRUE; | |
541 | key->type = JUMP_TYPE_LINKED | type; | |
542 | } | |
543 | ||
544 | void jump_label_init_ro(void) | |
545 | { | |
546 | struct jump_entry *iter_start = __start___jump_table; | |
547 | struct jump_entry *iter_stop = __stop___jump_table; | |
548 | struct jump_entry *iter; | |
549 | ||
550 | if (WARN_ON_ONCE(!static_key_initialized)) | |
551 | return; | |
552 | ||
553 | cpus_read_lock(); | |
554 | jump_label_lock(); | |
555 | ||
556 | for (iter = iter_start; iter < iter_stop; iter++) { | |
557 | struct static_key *iterk = jump_entry_key(iter); | |
558 | ||
559 | if (!is_kernel_ro_after_init((unsigned long)iterk)) | |
560 | continue; | |
561 | ||
562 | if (static_key_sealed(iterk)) | |
563 | continue; | |
564 | ||
565 | static_key_seal(iterk); | |
566 | } | |
567 | ||
568 | jump_label_unlock(); | |
569 | cpus_read_unlock(); | |
570 | } | |
571 | ||
bf5438fc JB |
572 | #ifdef CONFIG_MODULES |
573 | ||
fdfd4289 | 574 | enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
11276d53 PZ |
575 | { |
576 | struct static_key *key = jump_entry_key(entry); | |
577 | bool type = static_key_type(key); | |
9ae033ac | 578 | bool branch = jump_entry_is_branch(entry); |
11276d53 PZ |
579 | |
580 | /* See the comment in linux/jump_label.h */ | |
581 | return type ^ branch; | |
582 | } | |
583 | ||
c5905afb IM |
584 | struct static_key_mod { |
585 | struct static_key_mod *next; | |
d430d3d7 JB |
586 | struct jump_entry *entries; |
587 | struct module *mod; | |
588 | }; | |
589 | ||
3821fd35 JB |
590 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
591 | { | |
34e12b86 | 592 | WARN_ON_ONCE(!static_key_linked(key)); |
3821fd35 JB |
593 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); |
594 | } | |
595 | ||
596 | /*** | |
597 | * key->type and key->next are the same via union. | |
598 | * This sets key->next and preserves the type bits. | |
599 | * | |
600 | * See additional comments above static_key_set_entries(). | |
601 | */ | |
602 | static void static_key_set_mod(struct static_key *key, | |
603 | struct static_key_mod *mod) | |
604 | { | |
605 | unsigned long type; | |
606 | ||
607 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
608 | type = key->type & JUMP_TYPE_MASK; | |
609 | key->next = mod; | |
610 | key->type |= type; | |
611 | } | |
612 | ||
d430d3d7 JB |
613 | static int __jump_label_mod_text_reserved(void *start, void *end) |
614 | { | |
615 | struct module *mod; | |
0db6e373 | 616 | int ret; |
d430d3d7 | 617 | |
bdc9f373 | 618 | preempt_disable(); |
d430d3d7 | 619 | mod = __module_text_address((unsigned long)start); |
bdc9f373 | 620 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
0db6e373 PZ |
621 | if (!try_module_get(mod)) |
622 | mod = NULL; | |
bdc9f373 RR |
623 | preempt_enable(); |
624 | ||
d430d3d7 JB |
625 | if (!mod) |
626 | return 0; | |
627 | ||
0db6e373 | 628 | ret = __jump_label_text_reserved(mod->jump_entries, |
d430d3d7 | 629 | mod->jump_entries + mod->num_jump_entries, |
9e667624 | 630 | start, end, mod->state == MODULE_STATE_COMING); |
0db6e373 PZ |
631 | |
632 | module_put(mod); | |
633 | ||
634 | return ret; | |
d430d3d7 JB |
635 | } |
636 | ||
706249c2 | 637 | static void __jump_label_mod_update(struct static_key *key) |
d430d3d7 | 638 | { |
706249c2 | 639 | struct static_key_mod *mod; |
d430d3d7 | 640 | |
3821fd35 JB |
641 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
642 | struct jump_entry *stop; | |
643 | struct module *m; | |
644 | ||
645 | /* | |
646 | * NULL if the static_key is defined in a module | |
647 | * that does not use it | |
648 | */ | |
649 | if (!mod->entries) | |
650 | continue; | |
7cbc5b8d | 651 | |
3821fd35 JB |
652 | m = mod->mod; |
653 | if (!m) | |
654 | stop = __stop___jump_table; | |
655 | else | |
656 | stop = m->jump_entries + m->num_jump_entries; | |
19483677 | 657 | __jump_label_update(key, mod->entries, stop, |
77ac1c02 | 658 | m && m->state == MODULE_STATE_COMING); |
d430d3d7 JB |
659 | } |
660 | } | |
661 | ||
d430d3d7 | 662 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 663 | { |
d430d3d7 JB |
664 | struct jump_entry *iter_start = mod->jump_entries; |
665 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
666 | struct jump_entry *iter; | |
c5905afb | 667 | struct static_key *key = NULL; |
3821fd35 | 668 | struct static_key_mod *jlm, *jlm2; |
bf5438fc JB |
669 | |
670 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 671 | if (iter_start == iter_stop) |
bf5438fc JB |
672 | return 0; |
673 | ||
d430d3d7 JB |
674 | jump_label_sort_entries(iter_start, iter_stop); |
675 | ||
676 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 677 | struct static_key *iterk; |
5af0ea29 | 678 | bool in_init; |
d430d3d7 | 679 | |
5af0ea29 PZ |
680 | in_init = within_module_init(jump_entry_code(iter), mod); |
681 | jump_entry_set_init(iter, in_init); | |
19483677 | 682 | |
7dcfd915 | 683 | iterk = jump_entry_key(iter); |
c5905afb IM |
684 | if (iterk == key) |
685 | continue; | |
d430d3d7 | 686 | |
c5905afb | 687 | key = iterk; |
9ae033ac | 688 | if (within_module((unsigned long)key, mod)) { |
3821fd35 | 689 | static_key_set_entries(key, iter); |
d430d3d7 | 690 | continue; |
bf5438fc | 691 | } |
91a1d97e PZ |
692 | |
693 | /* | |
694 | * If the key was sealed at init, then there's no need to keep a | |
695 | * reference to its module entries - just patch them now and be | |
696 | * done with it. | |
697 | */ | |
698 | if (static_key_sealed(key)) | |
699 | goto do_poke; | |
700 | ||
c5905afb | 701 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
702 | if (!jlm) |
703 | return -ENOMEM; | |
3821fd35 JB |
704 | if (!static_key_linked(key)) { |
705 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
706 | GFP_KERNEL); | |
707 | if (!jlm2) { | |
708 | kfree(jlm); | |
709 | return -ENOMEM; | |
710 | } | |
711 | preempt_disable(); | |
712 | jlm2->mod = __module_address((unsigned long)key); | |
713 | preempt_enable(); | |
714 | jlm2->entries = static_key_entries(key); | |
715 | jlm2->next = NULL; | |
716 | static_key_set_mod(key, jlm2); | |
717 | static_key_set_linked(key); | |
718 | } | |
d430d3d7 JB |
719 | jlm->mod = mod; |
720 | jlm->entries = iter; | |
3821fd35 JB |
721 | jlm->next = static_key_mod(key); |
722 | static_key_set_mod(key, jlm); | |
723 | static_key_set_linked(key); | |
d430d3d7 | 724 | |
11276d53 | 725 | /* Only update if we've changed from our initial state */ |
91a1d97e | 726 | do_poke: |
11276d53 | 727 | if (jump_label_type(iter) != jump_label_init_type(iter)) |
19483677 | 728 | __jump_label_update(key, iter, iter_stop, true); |
bf5438fc | 729 | } |
d430d3d7 | 730 | |
bf5438fc JB |
731 | return 0; |
732 | } | |
733 | ||
d430d3d7 | 734 | static void jump_label_del_module(struct module *mod) |
bf5438fc | 735 | { |
d430d3d7 JB |
736 | struct jump_entry *iter_start = mod->jump_entries; |
737 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
738 | struct jump_entry *iter; | |
c5905afb IM |
739 | struct static_key *key = NULL; |
740 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 741 | |
d430d3d7 | 742 | for (iter = iter_start; iter < iter_stop; iter++) { |
7dcfd915 | 743 | if (jump_entry_key(iter) == key) |
d430d3d7 JB |
744 | continue; |
745 | ||
7dcfd915 | 746 | key = jump_entry_key(iter); |
d430d3d7 | 747 | |
9ae033ac | 748 | if (within_module((unsigned long)key, mod)) |
d430d3d7 JB |
749 | continue; |
750 | ||
91a1d97e PZ |
751 | /* No @jlm allocated because key was sealed at init. */ |
752 | if (static_key_sealed(key)) | |
753 | continue; | |
754 | ||
3821fd35 JB |
755 | /* No memory during module load */ |
756 | if (WARN_ON(!static_key_linked(key))) | |
757 | continue; | |
758 | ||
d430d3d7 | 759 | prev = &key->next; |
3821fd35 | 760 | jlm = static_key_mod(key); |
bf5438fc | 761 | |
d430d3d7 JB |
762 | while (jlm && jlm->mod != mod) { |
763 | prev = &jlm->next; | |
764 | jlm = jlm->next; | |
765 | } | |
766 | ||
3821fd35 JB |
767 | /* No memory during module load */ |
768 | if (WARN_ON(!jlm)) | |
769 | continue; | |
770 | ||
771 | if (prev == &key->next) | |
772 | static_key_set_mod(key, jlm->next); | |
773 | else | |
d430d3d7 | 774 | *prev = jlm->next; |
3821fd35 JB |
775 | |
776 | kfree(jlm); | |
777 | ||
778 | jlm = static_key_mod(key); | |
779 | /* if only one etry is left, fold it back into the static_key */ | |
780 | if (jlm->next == NULL) { | |
781 | static_key_set_entries(key, jlm->entries); | |
782 | static_key_clear_linked(key); | |
d430d3d7 | 783 | kfree(jlm); |
bf5438fc JB |
784 | } |
785 | } | |
786 | } | |
787 | ||
788 | static int | |
789 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
790 | void *data) | |
791 | { | |
792 | struct module *mod = data; | |
793 | int ret = 0; | |
794 | ||
f2545b2d TG |
795 | cpus_read_lock(); |
796 | jump_label_lock(); | |
797 | ||
bf5438fc JB |
798 | switch (val) { |
799 | case MODULE_STATE_COMING: | |
d430d3d7 | 800 | ret = jump_label_add_module(mod); |
3821fd35 | 801 | if (ret) { |
da260fe1 | 802 | WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); |
d430d3d7 | 803 | jump_label_del_module(mod); |
3821fd35 | 804 | } |
bf5438fc JB |
805 | break; |
806 | case MODULE_STATE_GOING: | |
d430d3d7 | 807 | jump_label_del_module(mod); |
bf5438fc JB |
808 | break; |
809 | } | |
bf5438fc | 810 | |
f2545b2d TG |
811 | jump_label_unlock(); |
812 | cpus_read_unlock(); | |
813 | ||
d430d3d7 | 814 | return notifier_from_errno(ret); |
bf5438fc JB |
815 | } |
816 | ||
885885f6 | 817 | static struct notifier_block jump_label_module_nb = { |
bf5438fc | 818 | .notifier_call = jump_label_module_notify, |
d430d3d7 | 819 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
820 | }; |
821 | ||
d430d3d7 | 822 | static __init int jump_label_init_module(void) |
bf5438fc JB |
823 | { |
824 | return register_module_notifier(&jump_label_module_nb); | |
825 | } | |
d430d3d7 | 826 | early_initcall(jump_label_init_module); |
bf5438fc JB |
827 | |
828 | #endif /* CONFIG_MODULES */ | |
829 | ||
d430d3d7 JB |
830 | /*** |
831 | * jump_label_text_reserved - check if addr range is reserved | |
832 | * @start: start text addr | |
833 | * @end: end text addr | |
834 | * | |
835 | * checks if the text addr located between @start and @end | |
836 | * overlaps with any of the jump label patch addresses. Code | |
837 | * that wants to modify kernel text should first verify that | |
838 | * it does not overlap with any of the jump label addresses. | |
839 | * Caller must hold jump_label_mutex. | |
840 | * | |
841 | * returns 1 if there is an overlap, 0 otherwise | |
842 | */ | |
843 | int jump_label_text_reserved(void *start, void *end) | |
844 | { | |
9e667624 | 845 | bool init = system_state < SYSTEM_RUNNING; |
d430d3d7 | 846 | int ret = __jump_label_text_reserved(__start___jump_table, |
9e667624 | 847 | __stop___jump_table, start, end, init); |
d430d3d7 JB |
848 | |
849 | if (ret) | |
850 | return ret; | |
851 | ||
852 | #ifdef CONFIG_MODULES | |
853 | ret = __jump_label_mod_text_reserved(start, end); | |
854 | #endif | |
855 | return ret; | |
856 | } | |
857 | ||
706249c2 | 858 | static void jump_label_update(struct static_key *key) |
d430d3d7 | 859 | { |
c5905afb | 860 | struct jump_entry *stop = __stop___jump_table; |
55d2eba8 | 861 | bool init = system_state < SYSTEM_RUNNING; |
3821fd35 | 862 | struct jump_entry *entry; |
d430d3d7 | 863 | #ifdef CONFIG_MODULES |
bed831f9 | 864 | struct module *mod; |
140fe3b1 | 865 | |
3821fd35 JB |
866 | if (static_key_linked(key)) { |
867 | __jump_label_mod_update(key); | |
868 | return; | |
869 | } | |
140fe3b1 | 870 | |
bed831f9 PZ |
871 | preempt_disable(); |
872 | mod = __module_address((unsigned long)key); | |
55d2eba8 | 873 | if (mod) { |
140fe3b1 | 874 | stop = mod->jump_entries + mod->num_jump_entries; |
55d2eba8 PZ |
875 | init = mod->state == MODULE_STATE_COMING; |
876 | } | |
bed831f9 | 877 | preempt_enable(); |
d430d3d7 | 878 | #endif |
3821fd35 | 879 | entry = static_key_entries(key); |
140fe3b1 XG |
880 | /* if there are no users, entry can be NULL */ |
881 | if (entry) | |
55d2eba8 | 882 | __jump_label_update(key, entry, stop, init); |
d430d3d7 JB |
883 | } |
884 | ||
1987c947 PZ |
885 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
886 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
887 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
888 | ||
889 | static __init int jump_label_test(void) | |
890 | { | |
891 | int i; | |
892 | ||
893 | for (i = 0; i < 2; i++) { | |
894 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
895 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
896 | ||
897 | WARN_ON(!static_branch_likely(&sk_true)); | |
898 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
899 | WARN_ON(static_branch_likely(&sk_false)); | |
900 | WARN_ON(static_branch_unlikely(&sk_false)); | |
901 | ||
902 | static_branch_disable(&sk_true); | |
903 | static_branch_enable(&sk_false); | |
904 | ||
905 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
906 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
907 | ||
908 | WARN_ON(static_branch_likely(&sk_true)); | |
909 | WARN_ON(static_branch_unlikely(&sk_true)); | |
910 | WARN_ON(!static_branch_likely(&sk_false)); | |
911 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
912 | ||
913 | static_branch_enable(&sk_true); | |
914 | static_branch_disable(&sk_false); | |
915 | } | |
916 | ||
917 | return 0; | |
918 | } | |
92ee46ef | 919 | early_initcall(jump_label_test); |
1987c947 | 920 | #endif /* STATIC_KEYS_SELFTEST */ |