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 AB |
311 | if (jump_entry_code(entry) <= (unsigned long)end && |
312 | jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start) | |
4c3ef6d7 JB |
313 | return 1; |
314 | ||
315 | return 0; | |
316 | } | |
317 | ||
d430d3d7 JB |
318 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
319 | struct jump_entry *iter_stop, void *start, void *end) | |
4c3ef6d7 | 320 | { |
4c3ef6d7 | 321 | struct jump_entry *iter; |
4c3ef6d7 | 322 | |
4c3ef6d7 JB |
323 | iter = iter_start; |
324 | while (iter < iter_stop) { | |
d430d3d7 JB |
325 | if (addr_conflict(iter, start, end)) |
326 | return 1; | |
4c3ef6d7 JB |
327 | iter++; |
328 | } | |
329 | ||
d430d3d7 JB |
330 | return 0; |
331 | } | |
332 | ||
706249c2 | 333 | /* |
20284aa7 JF |
334 | * Update code which is definitely not currently executing. |
335 | * Architectures which need heavyweight synchronization to modify | |
336 | * running code can override this to make the non-live update case | |
337 | * cheaper. | |
338 | */ | |
9cdbe1cb | 339 | void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, |
20284aa7 JF |
340 | enum jump_label_type type) |
341 | { | |
706249c2 | 342 | arch_jump_label_transform(entry, type); |
20284aa7 JF |
343 | } |
344 | ||
706249c2 | 345 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
d430d3d7 | 346 | { |
3821fd35 JB |
347 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
348 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
4c3ef6d7 JB |
349 | } |
350 | ||
706249c2 | 351 | static inline bool static_key_type(struct static_key *key) |
c5905afb | 352 | { |
3821fd35 JB |
353 | return key->type & JUMP_TYPE_TRUE; |
354 | } | |
355 | ||
356 | static inline bool static_key_linked(struct static_key *key) | |
357 | { | |
358 | return key->type & JUMP_TYPE_LINKED; | |
359 | } | |
360 | ||
361 | static inline void static_key_clear_linked(struct static_key *key) | |
362 | { | |
363 | key->type &= ~JUMP_TYPE_LINKED; | |
364 | } | |
365 | ||
366 | static inline void static_key_set_linked(struct static_key *key) | |
367 | { | |
368 | key->type |= JUMP_TYPE_LINKED; | |
a1efb01f | 369 | } |
c5905afb | 370 | |
3821fd35 JB |
371 | /*** |
372 | * A 'struct static_key' uses a union such that it either points directly | |
373 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
374 | * turn point to 'struct jump_entry' tables. | |
375 | * | |
376 | * The two lower bits of the pointer are used to keep track of which pointer | |
377 | * type is in use and to store the initial branch direction, we use an access | |
378 | * function which preserves these bits. | |
379 | */ | |
380 | static void static_key_set_entries(struct static_key *key, | |
381 | struct jump_entry *entries) | |
382 | { | |
383 | unsigned long type; | |
384 | ||
385 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
386 | type = key->type & JUMP_TYPE_MASK; | |
387 | key->entries = entries; | |
388 | key->type |= type; | |
389 | } | |
390 | ||
706249c2 | 391 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
a1efb01f | 392 | { |
706249c2 | 393 | struct static_key *key = jump_entry_key(entry); |
a1efb01f | 394 | bool enabled = static_key_enabled(key); |
9ae033ac | 395 | bool branch = jump_entry_is_branch(entry); |
c5905afb | 396 | |
11276d53 PZ |
397 | /* See the comment in linux/jump_label.h */ |
398 | return enabled ^ branch; | |
c5905afb IM |
399 | } |
400 | ||
e1aacb3f DBO |
401 | static bool jump_label_can_update(struct jump_entry *entry, bool init) |
402 | { | |
403 | /* | |
404 | * Cannot update code that was in an init text area. | |
405 | */ | |
406 | if (!init && jump_entry_is_init(entry)) | |
407 | return false; | |
408 | ||
409 | if (!kernel_text_address(jump_entry_code(entry))) { | |
38c93587 PZ |
410 | /* |
411 | * This skips patching built-in __exit, which | |
412 | * is part of init_section_contains() but is | |
413 | * not part of kernel_text_address(). | |
414 | * | |
415 | * Skipping built-in __exit is fine since it | |
416 | * will never be executed. | |
417 | */ | |
8f35eaa5 AM |
418 | WARN_ONCE(!jump_entry_is_init(entry), |
419 | "can't patch jump_label at %pS", | |
420 | (void *)jump_entry_code(entry)); | |
e1aacb3f DBO |
421 | return false; |
422 | } | |
423 | ||
424 | return true; | |
425 | } | |
426 | ||
c2ba8a15 | 427 | #ifndef HAVE_JUMP_LABEL_BATCH |
706249c2 PZ |
428 | static void __jump_label_update(struct static_key *key, |
429 | struct jump_entry *entry, | |
19483677 AB |
430 | struct jump_entry *stop, |
431 | bool init) | |
706249c2 PZ |
432 | { |
433 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
e1aacb3f DBO |
434 | if (jump_label_can_update(entry, init)) |
435 | arch_jump_label_transform(entry, jump_label_type(entry)); | |
706249c2 PZ |
436 | } |
437 | } | |
c2ba8a15 DBO |
438 | #else |
439 | static void __jump_label_update(struct static_key *key, | |
440 | struct jump_entry *entry, | |
441 | struct jump_entry *stop, | |
442 | bool init) | |
443 | { | |
444 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
445 | ||
446 | if (!jump_label_can_update(entry, init)) | |
447 | continue; | |
448 | ||
449 | if (!arch_jump_label_transform_queue(entry, jump_label_type(entry))) { | |
450 | /* | |
451 | * Queue is full: Apply the current queue and try again. | |
452 | */ | |
453 | arch_jump_label_transform_apply(); | |
454 | BUG_ON(!arch_jump_label_transform_queue(entry, jump_label_type(entry))); | |
455 | } | |
456 | } | |
457 | arch_jump_label_transform_apply(); | |
458 | } | |
459 | #endif | |
706249c2 | 460 | |
97ce2c88 | 461 | void __init jump_label_init(void) |
bf5438fc | 462 | { |
bf5438fc JB |
463 | struct jump_entry *iter_start = __start___jump_table; |
464 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 465 | struct static_key *key = NULL; |
bf5438fc JB |
466 | struct jump_entry *iter; |
467 | ||
1f69bf9c JB |
468 | /* |
469 | * Since we are initializing the static_key.enabled field with | |
470 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
471 | * jump_label.h, let's make sure that is safe. There are only two | |
472 | * cases to check since we initialize to 0 or 1. | |
473 | */ | |
474 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
475 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
476 | ||
e3f91083 KH |
477 | if (static_key_initialized) |
478 | return; | |
479 | ||
f2545b2d | 480 | cpus_read_lock(); |
91bad2f8 | 481 | jump_label_lock(); |
d430d3d7 JB |
482 | jump_label_sort_entries(iter_start, iter_stop); |
483 | ||
484 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 485 | struct static_key *iterk; |
37348804 | 486 | |
11276d53 PZ |
487 | /* rewrite NOPs */ |
488 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
489 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
490 | ||
19483677 AB |
491 | if (init_section_contains((void *)jump_entry_code(iter), 1)) |
492 | jump_entry_set_init(iter); | |
493 | ||
7dcfd915 | 494 | iterk = jump_entry_key(iter); |
37348804 | 495 | if (iterk == key) |
d430d3d7 JB |
496 | continue; |
497 | ||
37348804 | 498 | key = iterk; |
3821fd35 | 499 | static_key_set_entries(key, iter); |
bf5438fc | 500 | } |
c4b2c0c5 | 501 | static_key_initialized = true; |
91bad2f8 | 502 | jump_label_unlock(); |
f2545b2d | 503 | cpus_read_unlock(); |
bf5438fc | 504 | } |
bf5438fc JB |
505 | |
506 | #ifdef CONFIG_MODULES | |
507 | ||
11276d53 PZ |
508 | static enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
509 | { | |
510 | struct static_key *key = jump_entry_key(entry); | |
511 | bool type = static_key_type(key); | |
9ae033ac | 512 | bool branch = jump_entry_is_branch(entry); |
11276d53 PZ |
513 | |
514 | /* See the comment in linux/jump_label.h */ | |
515 | return type ^ branch; | |
516 | } | |
517 | ||
c5905afb IM |
518 | struct static_key_mod { |
519 | struct static_key_mod *next; | |
d430d3d7 JB |
520 | struct jump_entry *entries; |
521 | struct module *mod; | |
522 | }; | |
523 | ||
3821fd35 JB |
524 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
525 | { | |
34e12b86 | 526 | WARN_ON_ONCE(!static_key_linked(key)); |
3821fd35 JB |
527 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); |
528 | } | |
529 | ||
530 | /*** | |
531 | * key->type and key->next are the same via union. | |
532 | * This sets key->next and preserves the type bits. | |
533 | * | |
534 | * See additional comments above static_key_set_entries(). | |
535 | */ | |
536 | static void static_key_set_mod(struct static_key *key, | |
537 | struct static_key_mod *mod) | |
538 | { | |
539 | unsigned long type; | |
540 | ||
541 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
542 | type = key->type & JUMP_TYPE_MASK; | |
543 | key->next = mod; | |
544 | key->type |= type; | |
545 | } | |
546 | ||
d430d3d7 JB |
547 | static int __jump_label_mod_text_reserved(void *start, void *end) |
548 | { | |
549 | struct module *mod; | |
0db6e373 | 550 | int ret; |
d430d3d7 | 551 | |
bdc9f373 | 552 | preempt_disable(); |
d430d3d7 | 553 | mod = __module_text_address((unsigned long)start); |
bdc9f373 | 554 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
0db6e373 PZ |
555 | if (!try_module_get(mod)) |
556 | mod = NULL; | |
bdc9f373 RR |
557 | preempt_enable(); |
558 | ||
d430d3d7 JB |
559 | if (!mod) |
560 | return 0; | |
561 | ||
0db6e373 | 562 | ret = __jump_label_text_reserved(mod->jump_entries, |
d430d3d7 JB |
563 | mod->jump_entries + mod->num_jump_entries, |
564 | start, end); | |
0db6e373 PZ |
565 | |
566 | module_put(mod); | |
567 | ||
568 | return ret; | |
d430d3d7 JB |
569 | } |
570 | ||
706249c2 | 571 | static void __jump_label_mod_update(struct static_key *key) |
d430d3d7 | 572 | { |
706249c2 | 573 | struct static_key_mod *mod; |
d430d3d7 | 574 | |
3821fd35 JB |
575 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
576 | struct jump_entry *stop; | |
577 | struct module *m; | |
578 | ||
579 | /* | |
580 | * NULL if the static_key is defined in a module | |
581 | * that does not use it | |
582 | */ | |
583 | if (!mod->entries) | |
584 | continue; | |
7cbc5b8d | 585 | |
3821fd35 JB |
586 | m = mod->mod; |
587 | if (!m) | |
588 | stop = __stop___jump_table; | |
589 | else | |
590 | stop = m->jump_entries + m->num_jump_entries; | |
19483677 | 591 | __jump_label_update(key, mod->entries, stop, |
77ac1c02 | 592 | m && m->state == MODULE_STATE_COMING); |
d430d3d7 JB |
593 | } |
594 | } | |
595 | ||
596 | /*** | |
597 | * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() | |
598 | * @mod: module to patch | |
599 | * | |
600 | * Allow for run-time selection of the optimal nops. Before the module | |
601 | * loads patch these with arch_get_jump_label_nop(), which is specified by | |
602 | * the arch specific jump label code. | |
603 | */ | |
604 | void jump_label_apply_nops(struct module *mod) | |
bf5438fc | 605 | { |
d430d3d7 JB |
606 | struct jump_entry *iter_start = mod->jump_entries; |
607 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
608 | struct jump_entry *iter; | |
609 | ||
610 | /* if the module doesn't have jump label entries, just return */ | |
611 | if (iter_start == iter_stop) | |
612 | return; | |
613 | ||
11276d53 PZ |
614 | for (iter = iter_start; iter < iter_stop; iter++) { |
615 | /* Only write NOPs for arch_branch_static(). */ | |
616 | if (jump_label_init_type(iter) == JUMP_LABEL_NOP) | |
617 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
618 | } | |
bf5438fc JB |
619 | } |
620 | ||
d430d3d7 | 621 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 622 | { |
d430d3d7 JB |
623 | struct jump_entry *iter_start = mod->jump_entries; |
624 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
625 | struct jump_entry *iter; | |
c5905afb | 626 | struct static_key *key = NULL; |
3821fd35 | 627 | struct static_key_mod *jlm, *jlm2; |
bf5438fc JB |
628 | |
629 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 630 | if (iter_start == iter_stop) |
bf5438fc JB |
631 | return 0; |
632 | ||
d430d3d7 JB |
633 | jump_label_sort_entries(iter_start, iter_stop); |
634 | ||
635 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 636 | struct static_key *iterk; |
d430d3d7 | 637 | |
19483677 AB |
638 | if (within_module_init(jump_entry_code(iter), mod)) |
639 | jump_entry_set_init(iter); | |
640 | ||
7dcfd915 | 641 | iterk = jump_entry_key(iter); |
c5905afb IM |
642 | if (iterk == key) |
643 | continue; | |
d430d3d7 | 644 | |
c5905afb | 645 | key = iterk; |
9ae033ac | 646 | if (within_module((unsigned long)key, mod)) { |
3821fd35 | 647 | static_key_set_entries(key, iter); |
d430d3d7 | 648 | continue; |
bf5438fc | 649 | } |
c5905afb | 650 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
651 | if (!jlm) |
652 | return -ENOMEM; | |
3821fd35 JB |
653 | if (!static_key_linked(key)) { |
654 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
655 | GFP_KERNEL); | |
656 | if (!jlm2) { | |
657 | kfree(jlm); | |
658 | return -ENOMEM; | |
659 | } | |
660 | preempt_disable(); | |
661 | jlm2->mod = __module_address((unsigned long)key); | |
662 | preempt_enable(); | |
663 | jlm2->entries = static_key_entries(key); | |
664 | jlm2->next = NULL; | |
665 | static_key_set_mod(key, jlm2); | |
666 | static_key_set_linked(key); | |
667 | } | |
d430d3d7 JB |
668 | jlm->mod = mod; |
669 | jlm->entries = iter; | |
3821fd35 JB |
670 | jlm->next = static_key_mod(key); |
671 | static_key_set_mod(key, jlm); | |
672 | static_key_set_linked(key); | |
d430d3d7 | 673 | |
11276d53 PZ |
674 | /* Only update if we've changed from our initial state */ |
675 | if (jump_label_type(iter) != jump_label_init_type(iter)) | |
19483677 | 676 | __jump_label_update(key, iter, iter_stop, true); |
bf5438fc | 677 | } |
d430d3d7 | 678 | |
bf5438fc JB |
679 | return 0; |
680 | } | |
681 | ||
d430d3d7 | 682 | static void jump_label_del_module(struct module *mod) |
bf5438fc | 683 | { |
d430d3d7 JB |
684 | struct jump_entry *iter_start = mod->jump_entries; |
685 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
686 | struct jump_entry *iter; | |
c5905afb IM |
687 | struct static_key *key = NULL; |
688 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 689 | |
d430d3d7 | 690 | for (iter = iter_start; iter < iter_stop; iter++) { |
7dcfd915 | 691 | if (jump_entry_key(iter) == key) |
d430d3d7 JB |
692 | continue; |
693 | ||
7dcfd915 | 694 | key = jump_entry_key(iter); |
d430d3d7 | 695 | |
9ae033ac | 696 | if (within_module((unsigned long)key, mod)) |
d430d3d7 JB |
697 | continue; |
698 | ||
3821fd35 JB |
699 | /* No memory during module load */ |
700 | if (WARN_ON(!static_key_linked(key))) | |
701 | continue; | |
702 | ||
d430d3d7 | 703 | prev = &key->next; |
3821fd35 | 704 | jlm = static_key_mod(key); |
bf5438fc | 705 | |
d430d3d7 JB |
706 | while (jlm && jlm->mod != mod) { |
707 | prev = &jlm->next; | |
708 | jlm = jlm->next; | |
709 | } | |
710 | ||
3821fd35 JB |
711 | /* No memory during module load */ |
712 | if (WARN_ON(!jlm)) | |
713 | continue; | |
714 | ||
715 | if (prev == &key->next) | |
716 | static_key_set_mod(key, jlm->next); | |
717 | else | |
d430d3d7 | 718 | *prev = jlm->next; |
3821fd35 JB |
719 | |
720 | kfree(jlm); | |
721 | ||
722 | jlm = static_key_mod(key); | |
723 | /* if only one etry is left, fold it back into the static_key */ | |
724 | if (jlm->next == NULL) { | |
725 | static_key_set_entries(key, jlm->entries); | |
726 | static_key_clear_linked(key); | |
d430d3d7 | 727 | kfree(jlm); |
bf5438fc JB |
728 | } |
729 | } | |
730 | } | |
731 | ||
732 | static int | |
733 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
734 | void *data) | |
735 | { | |
736 | struct module *mod = data; | |
737 | int ret = 0; | |
738 | ||
f2545b2d TG |
739 | cpus_read_lock(); |
740 | jump_label_lock(); | |
741 | ||
bf5438fc JB |
742 | switch (val) { |
743 | case MODULE_STATE_COMING: | |
d430d3d7 | 744 | ret = jump_label_add_module(mod); |
3821fd35 | 745 | if (ret) { |
da260fe1 | 746 | WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); |
d430d3d7 | 747 | jump_label_del_module(mod); |
3821fd35 | 748 | } |
bf5438fc JB |
749 | break; |
750 | case MODULE_STATE_GOING: | |
d430d3d7 | 751 | jump_label_del_module(mod); |
bf5438fc JB |
752 | break; |
753 | } | |
bf5438fc | 754 | |
f2545b2d TG |
755 | jump_label_unlock(); |
756 | cpus_read_unlock(); | |
757 | ||
d430d3d7 | 758 | return notifier_from_errno(ret); |
bf5438fc JB |
759 | } |
760 | ||
885885f6 | 761 | static struct notifier_block jump_label_module_nb = { |
bf5438fc | 762 | .notifier_call = jump_label_module_notify, |
d430d3d7 | 763 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
764 | }; |
765 | ||
d430d3d7 | 766 | static __init int jump_label_init_module(void) |
bf5438fc JB |
767 | { |
768 | return register_module_notifier(&jump_label_module_nb); | |
769 | } | |
d430d3d7 | 770 | early_initcall(jump_label_init_module); |
bf5438fc JB |
771 | |
772 | #endif /* CONFIG_MODULES */ | |
773 | ||
d430d3d7 JB |
774 | /*** |
775 | * jump_label_text_reserved - check if addr range is reserved | |
776 | * @start: start text addr | |
777 | * @end: end text addr | |
778 | * | |
779 | * checks if the text addr located between @start and @end | |
780 | * overlaps with any of the jump label patch addresses. Code | |
781 | * that wants to modify kernel text should first verify that | |
782 | * it does not overlap with any of the jump label addresses. | |
783 | * Caller must hold jump_label_mutex. | |
784 | * | |
785 | * returns 1 if there is an overlap, 0 otherwise | |
786 | */ | |
787 | int jump_label_text_reserved(void *start, void *end) | |
788 | { | |
789 | int ret = __jump_label_text_reserved(__start___jump_table, | |
790 | __stop___jump_table, start, end); | |
791 | ||
792 | if (ret) | |
793 | return ret; | |
794 | ||
795 | #ifdef CONFIG_MODULES | |
796 | ret = __jump_label_mod_text_reserved(start, end); | |
797 | #endif | |
798 | return ret; | |
799 | } | |
800 | ||
706249c2 | 801 | static void jump_label_update(struct static_key *key) |
d430d3d7 | 802 | { |
c5905afb | 803 | struct jump_entry *stop = __stop___jump_table; |
55d2eba8 | 804 | bool init = system_state < SYSTEM_RUNNING; |
3821fd35 | 805 | struct jump_entry *entry; |
d430d3d7 | 806 | #ifdef CONFIG_MODULES |
bed831f9 | 807 | struct module *mod; |
140fe3b1 | 808 | |
3821fd35 JB |
809 | if (static_key_linked(key)) { |
810 | __jump_label_mod_update(key); | |
811 | return; | |
812 | } | |
140fe3b1 | 813 | |
bed831f9 PZ |
814 | preempt_disable(); |
815 | mod = __module_address((unsigned long)key); | |
55d2eba8 | 816 | if (mod) { |
140fe3b1 | 817 | stop = mod->jump_entries + mod->num_jump_entries; |
55d2eba8 PZ |
818 | init = mod->state == MODULE_STATE_COMING; |
819 | } | |
bed831f9 | 820 | preempt_enable(); |
d430d3d7 | 821 | #endif |
3821fd35 | 822 | entry = static_key_entries(key); |
140fe3b1 XG |
823 | /* if there are no users, entry can be NULL */ |
824 | if (entry) | |
55d2eba8 | 825 | __jump_label_update(key, entry, stop, init); |
d430d3d7 JB |
826 | } |
827 | ||
1987c947 PZ |
828 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
829 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
830 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
831 | ||
832 | static __init int jump_label_test(void) | |
833 | { | |
834 | int i; | |
835 | ||
836 | for (i = 0; i < 2; i++) { | |
837 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
838 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
839 | ||
840 | WARN_ON(!static_branch_likely(&sk_true)); | |
841 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
842 | WARN_ON(static_branch_likely(&sk_false)); | |
843 | WARN_ON(static_branch_unlikely(&sk_false)); | |
844 | ||
845 | static_branch_disable(&sk_true); | |
846 | static_branch_enable(&sk_false); | |
847 | ||
848 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
849 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
850 | ||
851 | WARN_ON(static_branch_likely(&sk_true)); | |
852 | WARN_ON(static_branch_unlikely(&sk_true)); | |
853 | WARN_ON(!static_branch_likely(&sk_false)); | |
854 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
855 | ||
856 | static_branch_enable(&sk_true); | |
857 | static_branch_disable(&sk_false); | |
858 | } | |
859 | ||
860 | return 0; | |
861 | } | |
92ee46ef | 862 | early_initcall(jump_label_test); |
1987c947 | 863 | #endif /* STATIC_KEYS_SELFTEST */ |