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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 | |
83ab38ef | 134 | * static_key_slow_inc/dec() down the slow path, and it is non-zero |
695ef796 TG |
135 | * so it counts as "enabled" in jump_label_update(). |
136 | * | |
137 | * The INT_MAX overflow condition is either used by the networking | |
138 | * code to reset or detected in the slow path of | |
139 | * static_key_slow_inc_cpuslocked(). | |
eb8c5072 DS |
140 | */ |
141 | v = atomic_read(&key->enabled); | |
142 | do { | |
695ef796 | 143 | if (v <= 0 || v == INT_MAX) |
eb8c5072 DS |
144 | return false; |
145 | } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1))); | |
146 | ||
147 | return true; | |
148 | } | |
149 | EXPORT_SYMBOL_GPL(static_key_fast_inc_not_disabled); | |
150 | ||
151 | bool static_key_slow_inc_cpuslocked(struct static_key *key) | |
152 | { | |
cb538267 | 153 | lockdep_assert_cpus_held(); |
4c5ea0a9 PB |
154 | |
155 | /* | |
83ab38ef | 156 | * Careful if we get concurrent static_key_slow_inc/dec() calls; |
4c5ea0a9 PB |
157 | * later calls must wait for the first one to _finish_ the |
158 | * jump_label_update() process. At the same time, however, | |
159 | * the jump_label_update() call below wants to see | |
160 | * static_key_enabled(&key) for jumps to be updated properly. | |
4c5ea0a9 | 161 | */ |
eb8c5072 DS |
162 | if (static_key_fast_inc_not_disabled(key)) |
163 | return true; | |
bf5438fc | 164 | |
9bc2ff87 TG |
165 | guard(mutex)(&jump_label_mutex); |
166 | /* Try to mark it as 'enabling in progress. */ | |
167 | if (!atomic_cmpxchg(&key->enabled, 0, -1)) { | |
706249c2 | 168 | jump_label_update(key); |
d0646a6f | 169 | /* |
9bc2ff87 TG |
170 | * Ensure that when static_key_fast_inc_not_disabled() or |
171 | * static_key_slow_try_dec() observe the positive value, | |
172 | * they must also observe all the text changes. | |
d0646a6f PZ |
173 | */ |
174 | atomic_set_release(&key->enabled, 1); | |
4c5ea0a9 | 175 | } else { |
9bc2ff87 TG |
176 | /* |
177 | * While holding the mutex this should never observe | |
178 | * anything else than a value >= 1 and succeed | |
179 | */ | |
180 | if (WARN_ON_ONCE(!static_key_fast_inc_not_disabled(key))) | |
eb8c5072 | 181 | return false; |
4c5ea0a9 | 182 | } |
eb8c5072 | 183 | return true; |
8b7b4128 MZ |
184 | } |
185 | ||
eb8c5072 | 186 | bool static_key_slow_inc(struct static_key *key) |
8b7b4128 | 187 | { |
eb8c5072 DS |
188 | bool ret; |
189 | ||
8b7b4128 | 190 | cpus_read_lock(); |
eb8c5072 | 191 | ret = static_key_slow_inc_cpuslocked(key); |
f2545b2d | 192 | cpus_read_unlock(); |
eb8c5072 | 193 | return ret; |
bf5438fc | 194 | } |
c5905afb | 195 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
bf5438fc | 196 | |
5a40527f | 197 | void static_key_enable_cpuslocked(struct static_key *key) |
1dbb6704 | 198 | { |
5cdda511 | 199 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 200 | lockdep_assert_cpus_held(); |
5a40527f | 201 | |
1dbb6704 PB |
202 | if (atomic_read(&key->enabled) > 0) { |
203 | WARN_ON_ONCE(atomic_read(&key->enabled) != 1); | |
204 | return; | |
205 | } | |
206 | ||
1dbb6704 PB |
207 | jump_label_lock(); |
208 | if (atomic_read(&key->enabled) == 0) { | |
209 | atomic_set(&key->enabled, -1); | |
210 | jump_label_update(key); | |
d0646a6f PZ |
211 | /* |
212 | * See static_key_slow_inc(). | |
213 | */ | |
214 | atomic_set_release(&key->enabled, 1); | |
1dbb6704 PB |
215 | } |
216 | jump_label_unlock(); | |
5a40527f MZ |
217 | } |
218 | EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked); | |
219 | ||
220 | void static_key_enable(struct static_key *key) | |
221 | { | |
222 | cpus_read_lock(); | |
223 | static_key_enable_cpuslocked(key); | |
1dbb6704 PB |
224 | cpus_read_unlock(); |
225 | } | |
226 | EXPORT_SYMBOL_GPL(static_key_enable); | |
227 | ||
5a40527f | 228 | void static_key_disable_cpuslocked(struct static_key *key) |
1dbb6704 | 229 | { |
5cdda511 | 230 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 231 | lockdep_assert_cpus_held(); |
5a40527f | 232 | |
1dbb6704 PB |
233 | if (atomic_read(&key->enabled) != 1) { |
234 | WARN_ON_ONCE(atomic_read(&key->enabled) != 0); | |
235 | return; | |
236 | } | |
237 | ||
1dbb6704 | 238 | jump_label_lock(); |
224fa355 | 239 | if (atomic_cmpxchg(&key->enabled, 1, 0) == 1) |
1dbb6704 PB |
240 | jump_label_update(key); |
241 | jump_label_unlock(); | |
5a40527f MZ |
242 | } |
243 | EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked); | |
244 | ||
245 | void static_key_disable(struct static_key *key) | |
246 | { | |
247 | cpus_read_lock(); | |
248 | static_key_disable_cpuslocked(key); | |
1dbb6704 PB |
249 | cpus_read_unlock(); |
250 | } | |
251 | EXPORT_SYMBOL_GPL(static_key_disable); | |
252 | ||
b92e793b | 253 | static bool static_key_slow_try_dec(struct static_key *key) |
bf5438fc | 254 | { |
83ab38ef | 255 | int v; |
cb538267 | 256 | |
4c5ea0a9 | 257 | /* |
83ab38ef TG |
258 | * Go into the slow path if key::enabled is less than or equal than |
259 | * one. One is valid to shut down the key, anything less than one | |
260 | * is an imbalance, which is handled at the call site. | |
261 | * | |
262 | * That includes the special case of '-1' which is set in | |
263 | * static_key_slow_inc_cpuslocked(), but that's harmless as it is | |
264 | * fully serialized in the slow path below. By the time this task | |
265 | * acquires the jump label lock the value is back to one and the | |
266 | * retry under the lock must succeed. | |
4c5ea0a9 | 267 | */ |
83ab38ef TG |
268 | v = atomic_read(&key->enabled); |
269 | do { | |
270 | /* | |
271 | * Warn about the '-1' case though; since that means a | |
272 | * decrement is concurrent with a first (0->1) increment. IOW | |
273 | * people are trying to disable something that wasn't yet fully | |
274 | * enabled. This suggests an ordering problem on the user side. | |
275 | */ | |
276 | WARN_ON_ONCE(v < 0); | |
277 | if (v <= 1) | |
278 | return false; | |
279 | } while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v - 1))); | |
280 | ||
b92e793b JK |
281 | return true; |
282 | } | |
283 | ||
94b5f312 | 284 | static void __static_key_slow_dec_cpuslocked(struct static_key *key) |
b92e793b JK |
285 | { |
286 | lockdep_assert_cpus_held(); | |
287 | ||
288 | if (static_key_slow_try_dec(key)) | |
d430d3d7 | 289 | return; |
bf5438fc | 290 | |
83ab38ef | 291 | guard(mutex)(&jump_label_mutex); |
224fa355 | 292 | if (atomic_cmpxchg(&key->enabled, 1, 0) == 1) |
94b5f312 | 293 | jump_label_update(key); |
83ab38ef TG |
294 | else |
295 | WARN_ON_ONCE(!static_key_slow_try_dec(key)); | |
8b7b4128 MZ |
296 | } |
297 | ||
94b5f312 | 298 | static void __static_key_slow_dec(struct static_key *key) |
8b7b4128 MZ |
299 | { |
300 | cpus_read_lock(); | |
94b5f312 | 301 | __static_key_slow_dec_cpuslocked(key); |
f2545b2d | 302 | cpus_read_unlock(); |
bf5438fc JB |
303 | } |
304 | ||
ad282a81 | 305 | void jump_label_update_timeout(struct work_struct *work) |
b2029520 | 306 | { |
c5905afb IM |
307 | struct static_key_deferred *key = |
308 | container_of(work, struct static_key_deferred, work.work); | |
94b5f312 | 309 | __static_key_slow_dec(&key->key); |
b2029520 | 310 | } |
ad282a81 | 311 | EXPORT_SYMBOL_GPL(jump_label_update_timeout); |
b2029520 | 312 | |
c5905afb | 313 | void static_key_slow_dec(struct static_key *key) |
b2029520 | 314 | { |
5cdda511 | 315 | STATIC_KEY_CHECK_USE(key); |
94b5f312 | 316 | __static_key_slow_dec(key); |
b2029520 | 317 | } |
c5905afb | 318 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
b2029520 | 319 | |
ce48c146 PZ |
320 | void static_key_slow_dec_cpuslocked(struct static_key *key) |
321 | { | |
322 | STATIC_KEY_CHECK_USE(key); | |
94b5f312 | 323 | __static_key_slow_dec_cpuslocked(key); |
ce48c146 PZ |
324 | } |
325 | ||
ad282a81 JK |
326 | void __static_key_slow_dec_deferred(struct static_key *key, |
327 | struct delayed_work *work, | |
328 | unsigned long timeout) | |
b2029520 | 329 | { |
5cdda511 | 330 | STATIC_KEY_CHECK_USE(key); |
94b5f312 JK |
331 | |
332 | if (static_key_slow_try_dec(key)) | |
333 | return; | |
334 | ||
335 | schedule_delayed_work(work, timeout); | |
b2029520 | 336 | } |
ad282a81 | 337 | EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); |
b2029520 | 338 | |
ad282a81 | 339 | void __static_key_deferred_flush(void *key, struct delayed_work *work) |
b6416e61 | 340 | { |
5cdda511 | 341 | STATIC_KEY_CHECK_USE(key); |
ad282a81 | 342 | flush_delayed_work(work); |
b6416e61 | 343 | } |
ad282a81 | 344 | EXPORT_SYMBOL_GPL(__static_key_deferred_flush); |
b6416e61 | 345 | |
c5905afb | 346 | void jump_label_rate_limit(struct static_key_deferred *key, |
b2029520 GN |
347 | unsigned long rl) |
348 | { | |
5cdda511 | 349 | STATIC_KEY_CHECK_USE(key); |
b2029520 GN |
350 | key->timeout = rl; |
351 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
352 | } | |
a181dc14 | 353 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
b2029520 | 354 | |
4c3ef6d7 JB |
355 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
356 | { | |
9ae033ac | 357 | if (jump_entry_code(entry) <= (unsigned long)end && |
fa5e5dc3 | 358 | jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start) |
4c3ef6d7 JB |
359 | return 1; |
360 | ||
361 | return 0; | |
362 | } | |
363 | ||
d430d3d7 | 364 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
9e667624 | 365 | struct jump_entry *iter_stop, void *start, void *end, bool init) |
4c3ef6d7 | 366 | { |
4c3ef6d7 | 367 | struct jump_entry *iter; |
4c3ef6d7 | 368 | |
4c3ef6d7 JB |
369 | iter = iter_start; |
370 | while (iter < iter_stop) { | |
9e667624 PZ |
371 | if (init || !jump_entry_is_init(iter)) { |
372 | if (addr_conflict(iter, start, end)) | |
373 | return 1; | |
374 | } | |
4c3ef6d7 JB |
375 | iter++; |
376 | } | |
377 | ||
d430d3d7 JB |
378 | return 0; |
379 | } | |
380 | ||
7e6b9db2 AB |
381 | #ifndef arch_jump_label_transform_static |
382 | static void arch_jump_label_transform_static(struct jump_entry *entry, | |
383 | enum jump_label_type type) | |
20284aa7 | 384 | { |
7e6b9db2 | 385 | /* nothing to do on most architectures */ |
20284aa7 | 386 | } |
7e6b9db2 | 387 | #endif |
20284aa7 | 388 | |
706249c2 | 389 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
d430d3d7 | 390 | { |
3821fd35 JB |
391 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
392 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
4c3ef6d7 JB |
393 | } |
394 | ||
706249c2 | 395 | static inline bool static_key_type(struct static_key *key) |
c5905afb | 396 | { |
3821fd35 JB |
397 | return key->type & JUMP_TYPE_TRUE; |
398 | } | |
399 | ||
400 | static inline bool static_key_linked(struct static_key *key) | |
401 | { | |
402 | return key->type & JUMP_TYPE_LINKED; | |
403 | } | |
404 | ||
405 | static inline void static_key_clear_linked(struct static_key *key) | |
406 | { | |
407 | key->type &= ~JUMP_TYPE_LINKED; | |
408 | } | |
409 | ||
410 | static inline void static_key_set_linked(struct static_key *key) | |
411 | { | |
412 | key->type |= JUMP_TYPE_LINKED; | |
a1efb01f | 413 | } |
c5905afb | 414 | |
3821fd35 JB |
415 | /*** |
416 | * A 'struct static_key' uses a union such that it either points directly | |
417 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
418 | * turn point to 'struct jump_entry' tables. | |
419 | * | |
420 | * The two lower bits of the pointer are used to keep track of which pointer | |
421 | * type is in use and to store the initial branch direction, we use an access | |
422 | * function which preserves these bits. | |
423 | */ | |
424 | static void static_key_set_entries(struct static_key *key, | |
425 | struct jump_entry *entries) | |
426 | { | |
427 | unsigned long type; | |
428 | ||
429 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
430 | type = key->type & JUMP_TYPE_MASK; | |
431 | key->entries = entries; | |
432 | key->type |= type; | |
433 | } | |
434 | ||
706249c2 | 435 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
a1efb01f | 436 | { |
706249c2 | 437 | struct static_key *key = jump_entry_key(entry); |
a1efb01f | 438 | bool enabled = static_key_enabled(key); |
9ae033ac | 439 | bool branch = jump_entry_is_branch(entry); |
c5905afb | 440 | |
11276d53 PZ |
441 | /* See the comment in linux/jump_label.h */ |
442 | return enabled ^ branch; | |
c5905afb IM |
443 | } |
444 | ||
e1aacb3f DBO |
445 | static bool jump_label_can_update(struct jump_entry *entry, bool init) |
446 | { | |
447 | /* | |
448 | * Cannot update code that was in an init text area. | |
449 | */ | |
450 | if (!init && jump_entry_is_init(entry)) | |
451 | return false; | |
452 | ||
453 | if (!kernel_text_address(jump_entry_code(entry))) { | |
38c93587 PZ |
454 | /* |
455 | * This skips patching built-in __exit, which | |
456 | * is part of init_section_contains() but is | |
457 | * not part of kernel_text_address(). | |
458 | * | |
459 | * Skipping built-in __exit is fine since it | |
460 | * will never be executed. | |
461 | */ | |
8f35eaa5 AM |
462 | WARN_ONCE(!jump_entry_is_init(entry), |
463 | "can't patch jump_label at %pS", | |
464 | (void *)jump_entry_code(entry)); | |
e1aacb3f DBO |
465 | return false; |
466 | } | |
467 | ||
468 | return true; | |
469 | } | |
470 | ||
c2ba8a15 | 471 | #ifndef HAVE_JUMP_LABEL_BATCH |
706249c2 PZ |
472 | static void __jump_label_update(struct static_key *key, |
473 | struct jump_entry *entry, | |
19483677 AB |
474 | struct jump_entry *stop, |
475 | bool init) | |
706249c2 PZ |
476 | { |
477 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
e1aacb3f DBO |
478 | if (jump_label_can_update(entry, init)) |
479 | arch_jump_label_transform(entry, jump_label_type(entry)); | |
706249c2 PZ |
480 | } |
481 | } | |
c2ba8a15 DBO |
482 | #else |
483 | static void __jump_label_update(struct static_key *key, | |
484 | struct jump_entry *entry, | |
485 | struct jump_entry *stop, | |
486 | bool init) | |
487 | { | |
488 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
489 | ||
490 | if (!jump_label_can_update(entry, init)) | |
491 | continue; | |
492 | ||
493 | if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) { | |
494 | /* | |
495 | * Queue is full: Apply the current queue and try again. | |
496 | */ | |
497 | arch_jump_label_transform_apply(); | |
498 | BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry))); | |
499 | } | |
500 | } | |
501 | arch_jump_label_transform_apply(); | |
502 | } | |
503 | #endif | |
706249c2 | 504 | |
97ce2c88 | 505 | void __init jump_label_init(void) |
bf5438fc | 506 | { |
bf5438fc JB |
507 | struct jump_entry *iter_start = __start___jump_table; |
508 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 509 | struct static_key *key = NULL; |
bf5438fc JB |
510 | struct jump_entry *iter; |
511 | ||
1f69bf9c JB |
512 | /* |
513 | * Since we are initializing the static_key.enabled field with | |
514 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
515 | * jump_label.h, let's make sure that is safe. There are only two | |
516 | * cases to check since we initialize to 0 or 1. | |
517 | */ | |
518 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
519 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
520 | ||
e3f91083 KH |
521 | if (static_key_initialized) |
522 | return; | |
523 | ||
f2545b2d | 524 | cpus_read_lock(); |
91bad2f8 | 525 | jump_label_lock(); |
d430d3d7 JB |
526 | jump_label_sort_entries(iter_start, iter_stop); |
527 | ||
528 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 529 | struct static_key *iterk; |
5af0ea29 | 530 | bool in_init; |
37348804 | 531 | |
11276d53 PZ |
532 | /* rewrite NOPs */ |
533 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
534 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
535 | ||
5af0ea29 PZ |
536 | in_init = init_section_contains((void *)jump_entry_code(iter), 1); |
537 | jump_entry_set_init(iter, in_init); | |
19483677 | 538 | |
7dcfd915 | 539 | iterk = jump_entry_key(iter); |
37348804 | 540 | if (iterk == key) |
d430d3d7 JB |
541 | continue; |
542 | ||
37348804 | 543 | key = iterk; |
3821fd35 | 544 | static_key_set_entries(key, iter); |
bf5438fc | 545 | } |
c4b2c0c5 | 546 | static_key_initialized = true; |
91bad2f8 | 547 | jump_label_unlock(); |
f2545b2d | 548 | cpus_read_unlock(); |
bf5438fc | 549 | } |
bf5438fc | 550 | |
91a1d97e PZ |
551 | static inline bool static_key_sealed(struct static_key *key) |
552 | { | |
553 | return (key->type & JUMP_TYPE_LINKED) && !(key->type & ~JUMP_TYPE_MASK); | |
554 | } | |
555 | ||
556 | static inline void static_key_seal(struct static_key *key) | |
557 | { | |
558 | unsigned long type = key->type & JUMP_TYPE_TRUE; | |
559 | key->type = JUMP_TYPE_LINKED | type; | |
560 | } | |
561 | ||
562 | void jump_label_init_ro(void) | |
563 | { | |
564 | struct jump_entry *iter_start = __start___jump_table; | |
565 | struct jump_entry *iter_stop = __stop___jump_table; | |
566 | struct jump_entry *iter; | |
567 | ||
568 | if (WARN_ON_ONCE(!static_key_initialized)) | |
569 | return; | |
570 | ||
571 | cpus_read_lock(); | |
572 | jump_label_lock(); | |
573 | ||
574 | for (iter = iter_start; iter < iter_stop; iter++) { | |
575 | struct static_key *iterk = jump_entry_key(iter); | |
576 | ||
577 | if (!is_kernel_ro_after_init((unsigned long)iterk)) | |
578 | continue; | |
579 | ||
580 | if (static_key_sealed(iterk)) | |
581 | continue; | |
582 | ||
583 | static_key_seal(iterk); | |
584 | } | |
585 | ||
586 | jump_label_unlock(); | |
587 | cpus_read_unlock(); | |
588 | } | |
589 | ||
bf5438fc JB |
590 | #ifdef CONFIG_MODULES |
591 | ||
fdfd4289 | 592 | enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
11276d53 PZ |
593 | { |
594 | struct static_key *key = jump_entry_key(entry); | |
595 | bool type = static_key_type(key); | |
9ae033ac | 596 | bool branch = jump_entry_is_branch(entry); |
11276d53 PZ |
597 | |
598 | /* See the comment in linux/jump_label.h */ | |
599 | return type ^ branch; | |
600 | } | |
601 | ||
c5905afb IM |
602 | struct static_key_mod { |
603 | struct static_key_mod *next; | |
d430d3d7 JB |
604 | struct jump_entry *entries; |
605 | struct module *mod; | |
606 | }; | |
607 | ||
3821fd35 JB |
608 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
609 | { | |
34e12b86 | 610 | WARN_ON_ONCE(!static_key_linked(key)); |
3821fd35 JB |
611 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); |
612 | } | |
613 | ||
614 | /*** | |
615 | * key->type and key->next are the same via union. | |
616 | * This sets key->next and preserves the type bits. | |
617 | * | |
618 | * See additional comments above static_key_set_entries(). | |
619 | */ | |
620 | static void static_key_set_mod(struct static_key *key, | |
621 | struct static_key_mod *mod) | |
622 | { | |
623 | unsigned long type; | |
624 | ||
625 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
626 | type = key->type & JUMP_TYPE_MASK; | |
627 | key->next = mod; | |
628 | key->type |= type; | |
629 | } | |
630 | ||
d430d3d7 JB |
631 | static int __jump_label_mod_text_reserved(void *start, void *end) |
632 | { | |
633 | struct module *mod; | |
0db6e373 | 634 | int ret; |
d430d3d7 | 635 | |
bdc9f373 | 636 | preempt_disable(); |
d430d3d7 | 637 | mod = __module_text_address((unsigned long)start); |
bdc9f373 | 638 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
0db6e373 PZ |
639 | if (!try_module_get(mod)) |
640 | mod = NULL; | |
bdc9f373 RR |
641 | preempt_enable(); |
642 | ||
d430d3d7 JB |
643 | if (!mod) |
644 | return 0; | |
645 | ||
0db6e373 | 646 | ret = __jump_label_text_reserved(mod->jump_entries, |
d430d3d7 | 647 | mod->jump_entries + mod->num_jump_entries, |
9e667624 | 648 | start, end, mod->state == MODULE_STATE_COMING); |
0db6e373 PZ |
649 | |
650 | module_put(mod); | |
651 | ||
652 | return ret; | |
d430d3d7 JB |
653 | } |
654 | ||
706249c2 | 655 | static void __jump_label_mod_update(struct static_key *key) |
d430d3d7 | 656 | { |
706249c2 | 657 | struct static_key_mod *mod; |
d430d3d7 | 658 | |
3821fd35 JB |
659 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
660 | struct jump_entry *stop; | |
661 | struct module *m; | |
662 | ||
663 | /* | |
664 | * NULL if the static_key is defined in a module | |
665 | * that does not use it | |
666 | */ | |
667 | if (!mod->entries) | |
668 | continue; | |
7cbc5b8d | 669 | |
3821fd35 JB |
670 | m = mod->mod; |
671 | if (!m) | |
672 | stop = __stop___jump_table; | |
673 | else | |
674 | stop = m->jump_entries + m->num_jump_entries; | |
19483677 | 675 | __jump_label_update(key, mod->entries, stop, |
77ac1c02 | 676 | m && m->state == MODULE_STATE_COMING); |
d430d3d7 JB |
677 | } |
678 | } | |
679 | ||
d430d3d7 | 680 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 681 | { |
d430d3d7 JB |
682 | struct jump_entry *iter_start = mod->jump_entries; |
683 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
684 | struct jump_entry *iter; | |
c5905afb | 685 | struct static_key *key = NULL; |
3821fd35 | 686 | struct static_key_mod *jlm, *jlm2; |
bf5438fc JB |
687 | |
688 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 689 | if (iter_start == iter_stop) |
bf5438fc JB |
690 | return 0; |
691 | ||
d430d3d7 JB |
692 | jump_label_sort_entries(iter_start, iter_stop); |
693 | ||
694 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 695 | struct static_key *iterk; |
5af0ea29 | 696 | bool in_init; |
d430d3d7 | 697 | |
5af0ea29 PZ |
698 | in_init = within_module_init(jump_entry_code(iter), mod); |
699 | jump_entry_set_init(iter, in_init); | |
19483677 | 700 | |
7dcfd915 | 701 | iterk = jump_entry_key(iter); |
c5905afb IM |
702 | if (iterk == key) |
703 | continue; | |
d430d3d7 | 704 | |
c5905afb | 705 | key = iterk; |
9ae033ac | 706 | if (within_module((unsigned long)key, mod)) { |
3821fd35 | 707 | static_key_set_entries(key, iter); |
d430d3d7 | 708 | continue; |
bf5438fc | 709 | } |
91a1d97e PZ |
710 | |
711 | /* | |
712 | * If the key was sealed at init, then there's no need to keep a | |
713 | * reference to its module entries - just patch them now and be | |
714 | * done with it. | |
715 | */ | |
716 | if (static_key_sealed(key)) | |
717 | goto do_poke; | |
718 | ||
c5905afb | 719 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
720 | if (!jlm) |
721 | return -ENOMEM; | |
3821fd35 JB |
722 | if (!static_key_linked(key)) { |
723 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
724 | GFP_KERNEL); | |
725 | if (!jlm2) { | |
726 | kfree(jlm); | |
727 | return -ENOMEM; | |
728 | } | |
729 | preempt_disable(); | |
730 | jlm2->mod = __module_address((unsigned long)key); | |
731 | preempt_enable(); | |
732 | jlm2->entries = static_key_entries(key); | |
733 | jlm2->next = NULL; | |
734 | static_key_set_mod(key, jlm2); | |
735 | static_key_set_linked(key); | |
736 | } | |
d430d3d7 JB |
737 | jlm->mod = mod; |
738 | jlm->entries = iter; | |
3821fd35 JB |
739 | jlm->next = static_key_mod(key); |
740 | static_key_set_mod(key, jlm); | |
741 | static_key_set_linked(key); | |
d430d3d7 | 742 | |
11276d53 | 743 | /* Only update if we've changed from our initial state */ |
91a1d97e | 744 | do_poke: |
11276d53 | 745 | if (jump_label_type(iter) != jump_label_init_type(iter)) |
19483677 | 746 | __jump_label_update(key, iter, iter_stop, true); |
bf5438fc | 747 | } |
d430d3d7 | 748 | |
bf5438fc JB |
749 | return 0; |
750 | } | |
751 | ||
d430d3d7 | 752 | static void jump_label_del_module(struct module *mod) |
bf5438fc | 753 | { |
d430d3d7 JB |
754 | struct jump_entry *iter_start = mod->jump_entries; |
755 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
756 | struct jump_entry *iter; | |
c5905afb IM |
757 | struct static_key *key = NULL; |
758 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 759 | |
d430d3d7 | 760 | for (iter = iter_start; iter < iter_stop; iter++) { |
7dcfd915 | 761 | if (jump_entry_key(iter) == key) |
d430d3d7 JB |
762 | continue; |
763 | ||
7dcfd915 | 764 | key = jump_entry_key(iter); |
d430d3d7 | 765 | |
9ae033ac | 766 | if (within_module((unsigned long)key, mod)) |
d430d3d7 JB |
767 | continue; |
768 | ||
91a1d97e PZ |
769 | /* No @jlm allocated because key was sealed at init. */ |
770 | if (static_key_sealed(key)) | |
771 | continue; | |
772 | ||
3821fd35 JB |
773 | /* No memory during module load */ |
774 | if (WARN_ON(!static_key_linked(key))) | |
775 | continue; | |
776 | ||
d430d3d7 | 777 | prev = &key->next; |
3821fd35 | 778 | jlm = static_key_mod(key); |
bf5438fc | 779 | |
d430d3d7 JB |
780 | while (jlm && jlm->mod != mod) { |
781 | prev = &jlm->next; | |
782 | jlm = jlm->next; | |
783 | } | |
784 | ||
3821fd35 JB |
785 | /* No memory during module load */ |
786 | if (WARN_ON(!jlm)) | |
787 | continue; | |
788 | ||
789 | if (prev == &key->next) | |
790 | static_key_set_mod(key, jlm->next); | |
791 | else | |
d430d3d7 | 792 | *prev = jlm->next; |
3821fd35 JB |
793 | |
794 | kfree(jlm); | |
795 | ||
796 | jlm = static_key_mod(key); | |
797 | /* if only one etry is left, fold it back into the static_key */ | |
798 | if (jlm->next == NULL) { | |
799 | static_key_set_entries(key, jlm->entries); | |
800 | static_key_clear_linked(key); | |
d430d3d7 | 801 | kfree(jlm); |
bf5438fc JB |
802 | } |
803 | } | |
804 | } | |
805 | ||
806 | static int | |
807 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
808 | void *data) | |
809 | { | |
810 | struct module *mod = data; | |
811 | int ret = 0; | |
812 | ||
f2545b2d TG |
813 | cpus_read_lock(); |
814 | jump_label_lock(); | |
815 | ||
bf5438fc JB |
816 | switch (val) { |
817 | case MODULE_STATE_COMING: | |
d430d3d7 | 818 | ret = jump_label_add_module(mod); |
3821fd35 | 819 | if (ret) { |
da260fe1 | 820 | WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); |
d430d3d7 | 821 | jump_label_del_module(mod); |
3821fd35 | 822 | } |
bf5438fc JB |
823 | break; |
824 | case MODULE_STATE_GOING: | |
d430d3d7 | 825 | jump_label_del_module(mod); |
bf5438fc JB |
826 | break; |
827 | } | |
bf5438fc | 828 | |
f2545b2d TG |
829 | jump_label_unlock(); |
830 | cpus_read_unlock(); | |
831 | ||
d430d3d7 | 832 | return notifier_from_errno(ret); |
bf5438fc JB |
833 | } |
834 | ||
885885f6 | 835 | static struct notifier_block jump_label_module_nb = { |
bf5438fc | 836 | .notifier_call = jump_label_module_notify, |
d430d3d7 | 837 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
838 | }; |
839 | ||
d430d3d7 | 840 | static __init int jump_label_init_module(void) |
bf5438fc JB |
841 | { |
842 | return register_module_notifier(&jump_label_module_nb); | |
843 | } | |
d430d3d7 | 844 | early_initcall(jump_label_init_module); |
bf5438fc JB |
845 | |
846 | #endif /* CONFIG_MODULES */ | |
847 | ||
d430d3d7 JB |
848 | /*** |
849 | * jump_label_text_reserved - check if addr range is reserved | |
850 | * @start: start text addr | |
851 | * @end: end text addr | |
852 | * | |
853 | * checks if the text addr located between @start and @end | |
854 | * overlaps with any of the jump label patch addresses. Code | |
855 | * that wants to modify kernel text should first verify that | |
856 | * it does not overlap with any of the jump label addresses. | |
857 | * Caller must hold jump_label_mutex. | |
858 | * | |
859 | * returns 1 if there is an overlap, 0 otherwise | |
860 | */ | |
861 | int jump_label_text_reserved(void *start, void *end) | |
862 | { | |
9e667624 | 863 | bool init = system_state < SYSTEM_RUNNING; |
d430d3d7 | 864 | int ret = __jump_label_text_reserved(__start___jump_table, |
9e667624 | 865 | __stop___jump_table, start, end, init); |
d430d3d7 JB |
866 | |
867 | if (ret) | |
868 | return ret; | |
869 | ||
870 | #ifdef CONFIG_MODULES | |
871 | ret = __jump_label_mod_text_reserved(start, end); | |
872 | #endif | |
873 | return ret; | |
874 | } | |
875 | ||
706249c2 | 876 | static void jump_label_update(struct static_key *key) |
d430d3d7 | 877 | { |
c5905afb | 878 | struct jump_entry *stop = __stop___jump_table; |
55d2eba8 | 879 | bool init = system_state < SYSTEM_RUNNING; |
3821fd35 | 880 | struct jump_entry *entry; |
d430d3d7 | 881 | #ifdef CONFIG_MODULES |
bed831f9 | 882 | struct module *mod; |
140fe3b1 | 883 | |
3821fd35 JB |
884 | if (static_key_linked(key)) { |
885 | __jump_label_mod_update(key); | |
886 | return; | |
887 | } | |
140fe3b1 | 888 | |
bed831f9 PZ |
889 | preempt_disable(); |
890 | mod = __module_address((unsigned long)key); | |
55d2eba8 | 891 | if (mod) { |
140fe3b1 | 892 | stop = mod->jump_entries + mod->num_jump_entries; |
55d2eba8 PZ |
893 | init = mod->state == MODULE_STATE_COMING; |
894 | } | |
bed831f9 | 895 | preempt_enable(); |
d430d3d7 | 896 | #endif |
3821fd35 | 897 | entry = static_key_entries(key); |
140fe3b1 XG |
898 | /* if there are no users, entry can be NULL */ |
899 | if (entry) | |
55d2eba8 | 900 | __jump_label_update(key, entry, stop, init); |
d430d3d7 JB |
901 | } |
902 | ||
1987c947 PZ |
903 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
904 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
905 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
906 | ||
907 | static __init int jump_label_test(void) | |
908 | { | |
909 | int i; | |
910 | ||
911 | for (i = 0; i < 2; i++) { | |
912 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
913 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
914 | ||
915 | WARN_ON(!static_branch_likely(&sk_true)); | |
916 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
917 | WARN_ON(static_branch_likely(&sk_false)); | |
918 | WARN_ON(static_branch_unlikely(&sk_false)); | |
919 | ||
920 | static_branch_disable(&sk_true); | |
921 | static_branch_enable(&sk_false); | |
922 | ||
923 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
924 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
925 | ||
926 | WARN_ON(static_branch_likely(&sk_true)); | |
927 | WARN_ON(static_branch_unlikely(&sk_true)); | |
928 | WARN_ON(!static_branch_likely(&sk_false)); | |
929 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
930 | ||
931 | static_branch_enable(&sk_true); | |
932 | static_branch_disable(&sk_false); | |
933 | } | |
934 | ||
935 | return 0; | |
936 | } | |
92ee46ef | 937 | early_initcall(jump_label_test); |
1987c947 | 938 | #endif /* STATIC_KEYS_SELFTEST */ |