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