Commit | Line | Data |
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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 | ||
ce48c146 | 116 | void static_key_slow_inc_cpuslocked(struct static_key *key) |
bf5438fc | 117 | { |
4c5ea0a9 PB |
118 | int v, v1; |
119 | ||
5cdda511 | 120 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 121 | lockdep_assert_cpus_held(); |
4c5ea0a9 PB |
122 | |
123 | /* | |
124 | * Careful if we get concurrent static_key_slow_inc() calls; | |
125 | * later calls must wait for the first one to _finish_ the | |
126 | * jump_label_update() process. At the same time, however, | |
127 | * the jump_label_update() call below wants to see | |
128 | * static_key_enabled(&key) for jumps to be updated properly. | |
129 | * | |
130 | * So give a special meaning to negative key->enabled: it sends | |
131 | * static_key_slow_inc() down the slow path, and it is non-zero | |
132 | * so it counts as "enabled" in jump_label_update(). Note that | |
133 | * atomic_inc_unless_negative() checks >= 0, so roll our own. | |
134 | */ | |
135 | for (v = atomic_read(&key->enabled); v > 0; v = v1) { | |
136 | v1 = atomic_cmpxchg(&key->enabled, v, v + 1); | |
8b7b4128 | 137 | if (likely(v1 == v)) |
4c5ea0a9 PB |
138 | return; |
139 | } | |
bf5438fc | 140 | |
d430d3d7 | 141 | jump_label_lock(); |
4c5ea0a9 PB |
142 | if (atomic_read(&key->enabled) == 0) { |
143 | atomic_set(&key->enabled, -1); | |
706249c2 | 144 | jump_label_update(key); |
d0646a6f PZ |
145 | /* |
146 | * Ensure that if the above cmpxchg loop observes our positive | |
147 | * value, it must also observe all the text changes. | |
148 | */ | |
149 | atomic_set_release(&key->enabled, 1); | |
4c5ea0a9 PB |
150 | } else { |
151 | atomic_inc(&key->enabled); | |
152 | } | |
d430d3d7 | 153 | jump_label_unlock(); |
8b7b4128 MZ |
154 | } |
155 | ||
156 | void static_key_slow_inc(struct static_key *key) | |
157 | { | |
158 | cpus_read_lock(); | |
159 | static_key_slow_inc_cpuslocked(key); | |
f2545b2d | 160 | cpus_read_unlock(); |
bf5438fc | 161 | } |
c5905afb | 162 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
bf5438fc | 163 | |
5a40527f | 164 | void static_key_enable_cpuslocked(struct static_key *key) |
1dbb6704 | 165 | { |
5cdda511 | 166 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 167 | lockdep_assert_cpus_held(); |
5a40527f | 168 | |
1dbb6704 PB |
169 | if (atomic_read(&key->enabled) > 0) { |
170 | WARN_ON_ONCE(atomic_read(&key->enabled) != 1); | |
171 | return; | |
172 | } | |
173 | ||
1dbb6704 PB |
174 | jump_label_lock(); |
175 | if (atomic_read(&key->enabled) == 0) { | |
176 | atomic_set(&key->enabled, -1); | |
177 | jump_label_update(key); | |
d0646a6f PZ |
178 | /* |
179 | * See static_key_slow_inc(). | |
180 | */ | |
181 | atomic_set_release(&key->enabled, 1); | |
1dbb6704 PB |
182 | } |
183 | jump_label_unlock(); | |
5a40527f MZ |
184 | } |
185 | EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked); | |
186 | ||
187 | void static_key_enable(struct static_key *key) | |
188 | { | |
189 | cpus_read_lock(); | |
190 | static_key_enable_cpuslocked(key); | |
1dbb6704 PB |
191 | cpus_read_unlock(); |
192 | } | |
193 | EXPORT_SYMBOL_GPL(static_key_enable); | |
194 | ||
5a40527f | 195 | void static_key_disable_cpuslocked(struct static_key *key) |
1dbb6704 | 196 | { |
5cdda511 | 197 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 198 | lockdep_assert_cpus_held(); |
5a40527f | 199 | |
1dbb6704 PB |
200 | if (atomic_read(&key->enabled) != 1) { |
201 | WARN_ON_ONCE(atomic_read(&key->enabled) != 0); | |
202 | return; | |
203 | } | |
204 | ||
1dbb6704 PB |
205 | jump_label_lock(); |
206 | if (atomic_cmpxchg(&key->enabled, 1, 0)) | |
207 | jump_label_update(key); | |
208 | jump_label_unlock(); | |
5a40527f MZ |
209 | } |
210 | EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked); | |
211 | ||
212 | void static_key_disable(struct static_key *key) | |
213 | { | |
214 | cpus_read_lock(); | |
215 | static_key_disable_cpuslocked(key); | |
1dbb6704 PB |
216 | cpus_read_unlock(); |
217 | } | |
218 | EXPORT_SYMBOL_GPL(static_key_disable); | |
219 | ||
b92e793b | 220 | static bool static_key_slow_try_dec(struct static_key *key) |
bf5438fc | 221 | { |
a1247d06 PZ |
222 | int val; |
223 | ||
b92e793b JK |
224 | val = atomic_fetch_add_unless(&key->enabled, -1, 1); |
225 | if (val == 1) | |
226 | return false; | |
cb538267 | 227 | |
4c5ea0a9 PB |
228 | /* |
229 | * The negative count check is valid even when a negative | |
230 | * key->enabled is in use by static_key_slow_inc(); a | |
231 | * __static_key_slow_dec() before the first static_key_slow_inc() | |
232 | * returns is unbalanced, because all other static_key_slow_inc() | |
233 | * instances block while the update is in progress. | |
234 | */ | |
b92e793b JK |
235 | WARN(val < 0, "jump label: negative count!\n"); |
236 | return true; | |
237 | } | |
238 | ||
94b5f312 | 239 | static void __static_key_slow_dec_cpuslocked(struct static_key *key) |
b92e793b JK |
240 | { |
241 | lockdep_assert_cpus_held(); | |
242 | ||
243 | if (static_key_slow_try_dec(key)) | |
d430d3d7 | 244 | return; |
bf5438fc | 245 | |
a1247d06 | 246 | jump_label_lock(); |
94b5f312 JK |
247 | if (atomic_dec_and_test(&key->enabled)) |
248 | jump_label_update(key); | |
91bad2f8 | 249 | jump_label_unlock(); |
8b7b4128 MZ |
250 | } |
251 | ||
94b5f312 | 252 | static void __static_key_slow_dec(struct static_key *key) |
8b7b4128 MZ |
253 | { |
254 | cpus_read_lock(); | |
94b5f312 | 255 | __static_key_slow_dec_cpuslocked(key); |
f2545b2d | 256 | cpus_read_unlock(); |
bf5438fc JB |
257 | } |
258 | ||
ad282a81 | 259 | void jump_label_update_timeout(struct work_struct *work) |
b2029520 | 260 | { |
c5905afb IM |
261 | struct static_key_deferred *key = |
262 | container_of(work, struct static_key_deferred, work.work); | |
94b5f312 | 263 | __static_key_slow_dec(&key->key); |
b2029520 | 264 | } |
ad282a81 | 265 | EXPORT_SYMBOL_GPL(jump_label_update_timeout); |
b2029520 | 266 | |
c5905afb | 267 | void static_key_slow_dec(struct static_key *key) |
b2029520 | 268 | { |
5cdda511 | 269 | STATIC_KEY_CHECK_USE(key); |
94b5f312 | 270 | __static_key_slow_dec(key); |
b2029520 | 271 | } |
c5905afb | 272 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
b2029520 | 273 | |
ce48c146 PZ |
274 | void static_key_slow_dec_cpuslocked(struct static_key *key) |
275 | { | |
276 | STATIC_KEY_CHECK_USE(key); | |
94b5f312 | 277 | __static_key_slow_dec_cpuslocked(key); |
ce48c146 PZ |
278 | } |
279 | ||
ad282a81 JK |
280 | void __static_key_slow_dec_deferred(struct static_key *key, |
281 | struct delayed_work *work, | |
282 | unsigned long timeout) | |
b2029520 | 283 | { |
5cdda511 | 284 | STATIC_KEY_CHECK_USE(key); |
94b5f312 JK |
285 | |
286 | if (static_key_slow_try_dec(key)) | |
287 | return; | |
288 | ||
289 | schedule_delayed_work(work, timeout); | |
b2029520 | 290 | } |
ad282a81 | 291 | EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); |
b2029520 | 292 | |
ad282a81 | 293 | void __static_key_deferred_flush(void *key, struct delayed_work *work) |
b6416e61 | 294 | { |
5cdda511 | 295 | STATIC_KEY_CHECK_USE(key); |
ad282a81 | 296 | flush_delayed_work(work); |
b6416e61 | 297 | } |
ad282a81 | 298 | EXPORT_SYMBOL_GPL(__static_key_deferred_flush); |
b6416e61 | 299 | |
c5905afb | 300 | void jump_label_rate_limit(struct static_key_deferred *key, |
b2029520 GN |
301 | unsigned long rl) |
302 | { | |
5cdda511 | 303 | STATIC_KEY_CHECK_USE(key); |
b2029520 GN |
304 | key->timeout = rl; |
305 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
306 | } | |
a181dc14 | 307 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
b2029520 | 308 | |
4c3ef6d7 JB |
309 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
310 | { | |
9ae033ac | 311 | if (jump_entry_code(entry) <= (unsigned long)end && |
fa5e5dc3 | 312 | jump_entry_code(entry) + jump_entry_size(entry) > (unsigned long)start) |
4c3ef6d7 JB |
313 | return 1; |
314 | ||
315 | return 0; | |
316 | } | |
317 | ||
d430d3d7 | 318 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
9e667624 | 319 | struct jump_entry *iter_stop, void *start, void *end, bool init) |
4c3ef6d7 | 320 | { |
4c3ef6d7 | 321 | struct jump_entry *iter; |
4c3ef6d7 | 322 | |
4c3ef6d7 JB |
323 | iter = iter_start; |
324 | while (iter < iter_stop) { | |
9e667624 PZ |
325 | if (init || !jump_entry_is_init(iter)) { |
326 | if (addr_conflict(iter, start, end)) | |
327 | return 1; | |
328 | } | |
4c3ef6d7 JB |
329 | iter++; |
330 | } | |
331 | ||
d430d3d7 JB |
332 | return 0; |
333 | } | |
334 | ||
7e6b9db2 AB |
335 | #ifndef arch_jump_label_transform_static |
336 | static void arch_jump_label_transform_static(struct jump_entry *entry, | |
337 | enum jump_label_type type) | |
20284aa7 | 338 | { |
7e6b9db2 | 339 | /* nothing to do on most architectures */ |
20284aa7 | 340 | } |
7e6b9db2 | 341 | #endif |
20284aa7 | 342 | |
706249c2 | 343 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
d430d3d7 | 344 | { |
3821fd35 JB |
345 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
346 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
4c3ef6d7 JB |
347 | } |
348 | ||
706249c2 | 349 | static inline bool static_key_type(struct static_key *key) |
c5905afb | 350 | { |
3821fd35 JB |
351 | return key->type & JUMP_TYPE_TRUE; |
352 | } | |
353 | ||
354 | static inline bool static_key_linked(struct static_key *key) | |
355 | { | |
356 | return key->type & JUMP_TYPE_LINKED; | |
357 | } | |
358 | ||
359 | static inline void static_key_clear_linked(struct static_key *key) | |
360 | { | |
361 | key->type &= ~JUMP_TYPE_LINKED; | |
362 | } | |
363 | ||
364 | static inline void static_key_set_linked(struct static_key *key) | |
365 | { | |
366 | key->type |= JUMP_TYPE_LINKED; | |
a1efb01f | 367 | } |
c5905afb | 368 | |
3821fd35 JB |
369 | /*** |
370 | * A 'struct static_key' uses a union such that it either points directly | |
371 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
372 | * turn point to 'struct jump_entry' tables. | |
373 | * | |
374 | * The two lower bits of the pointer are used to keep track of which pointer | |
375 | * type is in use and to store the initial branch direction, we use an access | |
376 | * function which preserves these bits. | |
377 | */ | |
378 | static void static_key_set_entries(struct static_key *key, | |
379 | struct jump_entry *entries) | |
380 | { | |
381 | unsigned long type; | |
382 | ||
383 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
384 | type = key->type & JUMP_TYPE_MASK; | |
385 | key->entries = entries; | |
386 | key->type |= type; | |
387 | } | |
388 | ||
706249c2 | 389 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
a1efb01f | 390 | { |
706249c2 | 391 | struct static_key *key = jump_entry_key(entry); |
a1efb01f | 392 | bool enabled = static_key_enabled(key); |
9ae033ac | 393 | bool branch = jump_entry_is_branch(entry); |
c5905afb | 394 | |
11276d53 PZ |
395 | /* See the comment in linux/jump_label.h */ |
396 | return enabled ^ branch; | |
c5905afb IM |
397 | } |
398 | ||
e1aacb3f DBO |
399 | static bool jump_label_can_update(struct jump_entry *entry, bool init) |
400 | { | |
401 | /* | |
402 | * Cannot update code that was in an init text area. | |
403 | */ | |
404 | if (!init && jump_entry_is_init(entry)) | |
405 | return false; | |
406 | ||
407 | if (!kernel_text_address(jump_entry_code(entry))) { | |
38c93587 PZ |
408 | /* |
409 | * This skips patching built-in __exit, which | |
410 | * is part of init_section_contains() but is | |
411 | * not part of kernel_text_address(). | |
412 | * | |
413 | * Skipping built-in __exit is fine since it | |
414 | * will never be executed. | |
415 | */ | |
8f35eaa5 AM |
416 | WARN_ONCE(!jump_entry_is_init(entry), |
417 | "can't patch jump_label at %pS", | |
418 | (void *)jump_entry_code(entry)); | |
e1aacb3f DBO |
419 | return false; |
420 | } | |
421 | ||
422 | return true; | |
423 | } | |
424 | ||
c2ba8a15 | 425 | #ifndef HAVE_JUMP_LABEL_BATCH |
706249c2 PZ |
426 | static void __jump_label_update(struct static_key *key, |
427 | struct jump_entry *entry, | |
19483677 AB |
428 | struct jump_entry *stop, |
429 | bool init) | |
706249c2 PZ |
430 | { |
431 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
e1aacb3f DBO |
432 | if (jump_label_can_update(entry, init)) |
433 | arch_jump_label_transform(entry, jump_label_type(entry)); | |
706249c2 PZ |
434 | } |
435 | } | |
c2ba8a15 DBO |
436 | #else |
437 | static void __jump_label_update(struct static_key *key, | |
438 | struct jump_entry *entry, | |
439 | struct jump_entry *stop, | |
440 | bool init) | |
441 | { | |
442 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
443 | ||
444 | if (!jump_label_can_update(entry, init)) | |
445 | continue; | |
446 | ||
447 | if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) { | |
448 | /* | |
449 | * Queue is full: Apply the current queue and try again. | |
450 | */ | |
451 | arch_jump_label_transform_apply(); | |
452 | BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry))); | |
453 | } | |
454 | } | |
455 | arch_jump_label_transform_apply(); | |
456 | } | |
457 | #endif | |
706249c2 | 458 | |
97ce2c88 | 459 | void __init jump_label_init(void) |
bf5438fc | 460 | { |
bf5438fc JB |
461 | struct jump_entry *iter_start = __start___jump_table; |
462 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 463 | struct static_key *key = NULL; |
bf5438fc JB |
464 | struct jump_entry *iter; |
465 | ||
1f69bf9c JB |
466 | /* |
467 | * Since we are initializing the static_key.enabled field with | |
468 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
469 | * jump_label.h, let's make sure that is safe. There are only two | |
470 | * cases to check since we initialize to 0 or 1. | |
471 | */ | |
472 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
473 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
474 | ||
e3f91083 KH |
475 | if (static_key_initialized) |
476 | return; | |
477 | ||
f2545b2d | 478 | cpus_read_lock(); |
91bad2f8 | 479 | jump_label_lock(); |
d430d3d7 JB |
480 | jump_label_sort_entries(iter_start, iter_stop); |
481 | ||
482 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 483 | struct static_key *iterk; |
5af0ea29 | 484 | bool in_init; |
37348804 | 485 | |
11276d53 PZ |
486 | /* rewrite NOPs */ |
487 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
488 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
489 | ||
5af0ea29 PZ |
490 | in_init = init_section_contains((void *)jump_entry_code(iter), 1); |
491 | jump_entry_set_init(iter, in_init); | |
19483677 | 492 | |
7dcfd915 | 493 | iterk = jump_entry_key(iter); |
37348804 | 494 | if (iterk == key) |
d430d3d7 JB |
495 | continue; |
496 | ||
37348804 | 497 | key = iterk; |
3821fd35 | 498 | static_key_set_entries(key, iter); |
bf5438fc | 499 | } |
c4b2c0c5 | 500 | static_key_initialized = true; |
91bad2f8 | 501 | jump_label_unlock(); |
f2545b2d | 502 | cpus_read_unlock(); |
bf5438fc | 503 | } |
bf5438fc JB |
504 | |
505 | #ifdef CONFIG_MODULES | |
506 | ||
fdfd4289 | 507 | enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
11276d53 PZ |
508 | { |
509 | struct static_key *key = jump_entry_key(entry); | |
510 | bool type = static_key_type(key); | |
9ae033ac | 511 | bool branch = jump_entry_is_branch(entry); |
11276d53 PZ |
512 | |
513 | /* See the comment in linux/jump_label.h */ | |
514 | return type ^ branch; | |
515 | } | |
516 | ||
c5905afb IM |
517 | struct static_key_mod { |
518 | struct static_key_mod *next; | |
d430d3d7 JB |
519 | struct jump_entry *entries; |
520 | struct module *mod; | |
521 | }; | |
522 | ||
3821fd35 JB |
523 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
524 | { | |
34e12b86 | 525 | WARN_ON_ONCE(!static_key_linked(key)); |
3821fd35 JB |
526 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); |
527 | } | |
528 | ||
529 | /*** | |
530 | * key->type and key->next are the same via union. | |
531 | * This sets key->next and preserves the type bits. | |
532 | * | |
533 | * See additional comments above static_key_set_entries(). | |
534 | */ | |
535 | static void static_key_set_mod(struct static_key *key, | |
536 | struct static_key_mod *mod) | |
537 | { | |
538 | unsigned long type; | |
539 | ||
540 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
541 | type = key->type & JUMP_TYPE_MASK; | |
542 | key->next = mod; | |
543 | key->type |= type; | |
544 | } | |
545 | ||
d430d3d7 JB |
546 | static int __jump_label_mod_text_reserved(void *start, void *end) |
547 | { | |
548 | struct module *mod; | |
0db6e373 | 549 | int ret; |
d430d3d7 | 550 | |
bdc9f373 | 551 | preempt_disable(); |
d430d3d7 | 552 | mod = __module_text_address((unsigned long)start); |
bdc9f373 | 553 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
0db6e373 PZ |
554 | if (!try_module_get(mod)) |
555 | mod = NULL; | |
bdc9f373 RR |
556 | preempt_enable(); |
557 | ||
d430d3d7 JB |
558 | if (!mod) |
559 | return 0; | |
560 | ||
0db6e373 | 561 | ret = __jump_label_text_reserved(mod->jump_entries, |
d430d3d7 | 562 | mod->jump_entries + mod->num_jump_entries, |
9e667624 | 563 | start, end, mod->state == MODULE_STATE_COMING); |
0db6e373 PZ |
564 | |
565 | module_put(mod); | |
566 | ||
567 | return ret; | |
d430d3d7 JB |
568 | } |
569 | ||
706249c2 | 570 | static void __jump_label_mod_update(struct static_key *key) |
d430d3d7 | 571 | { |
706249c2 | 572 | struct static_key_mod *mod; |
d430d3d7 | 573 | |
3821fd35 JB |
574 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
575 | struct jump_entry *stop; | |
576 | struct module *m; | |
577 | ||
578 | /* | |
579 | * NULL if the static_key is defined in a module | |
580 | * that does not use it | |
581 | */ | |
582 | if (!mod->entries) | |
583 | continue; | |
7cbc5b8d | 584 | |
3821fd35 JB |
585 | m = mod->mod; |
586 | if (!m) | |
587 | stop = __stop___jump_table; | |
588 | else | |
589 | stop = m->jump_entries + m->num_jump_entries; | |
19483677 | 590 | __jump_label_update(key, mod->entries, stop, |
77ac1c02 | 591 | m && m->state == MODULE_STATE_COMING); |
d430d3d7 JB |
592 | } |
593 | } | |
594 | ||
d430d3d7 | 595 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 596 | { |
d430d3d7 JB |
597 | struct jump_entry *iter_start = mod->jump_entries; |
598 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
599 | struct jump_entry *iter; | |
c5905afb | 600 | struct static_key *key = NULL; |
3821fd35 | 601 | struct static_key_mod *jlm, *jlm2; |
bf5438fc JB |
602 | |
603 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 604 | if (iter_start == iter_stop) |
bf5438fc JB |
605 | return 0; |
606 | ||
d430d3d7 JB |
607 | jump_label_sort_entries(iter_start, iter_stop); |
608 | ||
609 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 610 | struct static_key *iterk; |
5af0ea29 | 611 | bool in_init; |
d430d3d7 | 612 | |
5af0ea29 PZ |
613 | in_init = within_module_init(jump_entry_code(iter), mod); |
614 | jump_entry_set_init(iter, in_init); | |
19483677 | 615 | |
7dcfd915 | 616 | iterk = jump_entry_key(iter); |
c5905afb IM |
617 | if (iterk == key) |
618 | continue; | |
d430d3d7 | 619 | |
c5905afb | 620 | key = iterk; |
9ae033ac | 621 | if (within_module((unsigned long)key, mod)) { |
3821fd35 | 622 | static_key_set_entries(key, iter); |
d430d3d7 | 623 | continue; |
bf5438fc | 624 | } |
c5905afb | 625 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
626 | if (!jlm) |
627 | return -ENOMEM; | |
3821fd35 JB |
628 | if (!static_key_linked(key)) { |
629 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
630 | GFP_KERNEL); | |
631 | if (!jlm2) { | |
632 | kfree(jlm); | |
633 | return -ENOMEM; | |
634 | } | |
635 | preempt_disable(); | |
636 | jlm2->mod = __module_address((unsigned long)key); | |
637 | preempt_enable(); | |
638 | jlm2->entries = static_key_entries(key); | |
639 | jlm2->next = NULL; | |
640 | static_key_set_mod(key, jlm2); | |
641 | static_key_set_linked(key); | |
642 | } | |
d430d3d7 JB |
643 | jlm->mod = mod; |
644 | jlm->entries = iter; | |
3821fd35 JB |
645 | jlm->next = static_key_mod(key); |
646 | static_key_set_mod(key, jlm); | |
647 | static_key_set_linked(key); | |
d430d3d7 | 648 | |
11276d53 PZ |
649 | /* Only update if we've changed from our initial state */ |
650 | if (jump_label_type(iter) != jump_label_init_type(iter)) | |
19483677 | 651 | __jump_label_update(key, iter, iter_stop, true); |
bf5438fc | 652 | } |
d430d3d7 | 653 | |
bf5438fc JB |
654 | return 0; |
655 | } | |
656 | ||
d430d3d7 | 657 | static void jump_label_del_module(struct module *mod) |
bf5438fc | 658 | { |
d430d3d7 JB |
659 | struct jump_entry *iter_start = mod->jump_entries; |
660 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
661 | struct jump_entry *iter; | |
c5905afb IM |
662 | struct static_key *key = NULL; |
663 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 664 | |
d430d3d7 | 665 | for (iter = iter_start; iter < iter_stop; iter++) { |
7dcfd915 | 666 | if (jump_entry_key(iter) == key) |
d430d3d7 JB |
667 | continue; |
668 | ||
7dcfd915 | 669 | key = jump_entry_key(iter); |
d430d3d7 | 670 | |
9ae033ac | 671 | if (within_module((unsigned long)key, mod)) |
d430d3d7 JB |
672 | continue; |
673 | ||
3821fd35 JB |
674 | /* No memory during module load */ |
675 | if (WARN_ON(!static_key_linked(key))) | |
676 | continue; | |
677 | ||
d430d3d7 | 678 | prev = &key->next; |
3821fd35 | 679 | jlm = static_key_mod(key); |
bf5438fc | 680 | |
d430d3d7 JB |
681 | while (jlm && jlm->mod != mod) { |
682 | prev = &jlm->next; | |
683 | jlm = jlm->next; | |
684 | } | |
685 | ||
3821fd35 JB |
686 | /* No memory during module load */ |
687 | if (WARN_ON(!jlm)) | |
688 | continue; | |
689 | ||
690 | if (prev == &key->next) | |
691 | static_key_set_mod(key, jlm->next); | |
692 | else | |
d430d3d7 | 693 | *prev = jlm->next; |
3821fd35 JB |
694 | |
695 | kfree(jlm); | |
696 | ||
697 | jlm = static_key_mod(key); | |
698 | /* if only one etry is left, fold it back into the static_key */ | |
699 | if (jlm->next == NULL) { | |
700 | static_key_set_entries(key, jlm->entries); | |
701 | static_key_clear_linked(key); | |
d430d3d7 | 702 | kfree(jlm); |
bf5438fc JB |
703 | } |
704 | } | |
705 | } | |
706 | ||
707 | static int | |
708 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
709 | void *data) | |
710 | { | |
711 | struct module *mod = data; | |
712 | int ret = 0; | |
713 | ||
f2545b2d TG |
714 | cpus_read_lock(); |
715 | jump_label_lock(); | |
716 | ||
bf5438fc JB |
717 | switch (val) { |
718 | case MODULE_STATE_COMING: | |
d430d3d7 | 719 | ret = jump_label_add_module(mod); |
3821fd35 | 720 | if (ret) { |
da260fe1 | 721 | WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); |
d430d3d7 | 722 | jump_label_del_module(mod); |
3821fd35 | 723 | } |
bf5438fc JB |
724 | break; |
725 | case MODULE_STATE_GOING: | |
d430d3d7 | 726 | jump_label_del_module(mod); |
bf5438fc JB |
727 | break; |
728 | } | |
bf5438fc | 729 | |
f2545b2d TG |
730 | jump_label_unlock(); |
731 | cpus_read_unlock(); | |
732 | ||
d430d3d7 | 733 | return notifier_from_errno(ret); |
bf5438fc JB |
734 | } |
735 | ||
885885f6 | 736 | static struct notifier_block jump_label_module_nb = { |
bf5438fc | 737 | .notifier_call = jump_label_module_notify, |
d430d3d7 | 738 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
739 | }; |
740 | ||
d430d3d7 | 741 | static __init int jump_label_init_module(void) |
bf5438fc JB |
742 | { |
743 | return register_module_notifier(&jump_label_module_nb); | |
744 | } | |
d430d3d7 | 745 | early_initcall(jump_label_init_module); |
bf5438fc JB |
746 | |
747 | #endif /* CONFIG_MODULES */ | |
748 | ||
d430d3d7 JB |
749 | /*** |
750 | * jump_label_text_reserved - check if addr range is reserved | |
751 | * @start: start text addr | |
752 | * @end: end text addr | |
753 | * | |
754 | * checks if the text addr located between @start and @end | |
755 | * overlaps with any of the jump label patch addresses. Code | |
756 | * that wants to modify kernel text should first verify that | |
757 | * it does not overlap with any of the jump label addresses. | |
758 | * Caller must hold jump_label_mutex. | |
759 | * | |
760 | * returns 1 if there is an overlap, 0 otherwise | |
761 | */ | |
762 | int jump_label_text_reserved(void *start, void *end) | |
763 | { | |
9e667624 | 764 | bool init = system_state < SYSTEM_RUNNING; |
d430d3d7 | 765 | int ret = __jump_label_text_reserved(__start___jump_table, |
9e667624 | 766 | __stop___jump_table, start, end, init); |
d430d3d7 JB |
767 | |
768 | if (ret) | |
769 | return ret; | |
770 | ||
771 | #ifdef CONFIG_MODULES | |
772 | ret = __jump_label_mod_text_reserved(start, end); | |
773 | #endif | |
774 | return ret; | |
775 | } | |
776 | ||
706249c2 | 777 | static void jump_label_update(struct static_key *key) |
d430d3d7 | 778 | { |
c5905afb | 779 | struct jump_entry *stop = __stop___jump_table; |
55d2eba8 | 780 | bool init = system_state < SYSTEM_RUNNING; |
3821fd35 | 781 | struct jump_entry *entry; |
d430d3d7 | 782 | #ifdef CONFIG_MODULES |
bed831f9 | 783 | struct module *mod; |
140fe3b1 | 784 | |
3821fd35 JB |
785 | if (static_key_linked(key)) { |
786 | __jump_label_mod_update(key); | |
787 | return; | |
788 | } | |
140fe3b1 | 789 | |
bed831f9 PZ |
790 | preempt_disable(); |
791 | mod = __module_address((unsigned long)key); | |
55d2eba8 | 792 | if (mod) { |
140fe3b1 | 793 | stop = mod->jump_entries + mod->num_jump_entries; |
55d2eba8 PZ |
794 | init = mod->state == MODULE_STATE_COMING; |
795 | } | |
bed831f9 | 796 | preempt_enable(); |
d430d3d7 | 797 | #endif |
3821fd35 | 798 | entry = static_key_entries(key); |
140fe3b1 XG |
799 | /* if there are no users, entry can be NULL */ |
800 | if (entry) | |
55d2eba8 | 801 | __jump_label_update(key, entry, stop, init); |
d430d3d7 JB |
802 | } |
803 | ||
1987c947 PZ |
804 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
805 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
806 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
807 | ||
808 | static __init int jump_label_test(void) | |
809 | { | |
810 | int i; | |
811 | ||
812 | for (i = 0; i < 2; i++) { | |
813 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
814 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
815 | ||
816 | WARN_ON(!static_branch_likely(&sk_true)); | |
817 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
818 | WARN_ON(static_branch_likely(&sk_false)); | |
819 | WARN_ON(static_branch_unlikely(&sk_false)); | |
820 | ||
821 | static_branch_disable(&sk_true); | |
822 | static_branch_enable(&sk_false); | |
823 | ||
824 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
825 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
826 | ||
827 | WARN_ON(static_branch_likely(&sk_true)); | |
828 | WARN_ON(static_branch_unlikely(&sk_true)); | |
829 | WARN_ON(!static_branch_likely(&sk_false)); | |
830 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
831 | ||
832 | static_branch_enable(&sk_true); | |
833 | static_branch_disable(&sk_false); | |
834 | } | |
835 | ||
836 | return 0; | |
837 | } | |
92ee46ef | 838 | early_initcall(jump_label_test); |
1987c947 | 839 | #endif /* STATIC_KEYS_SELFTEST */ |