Commit | Line | Data |
---|---|---|
bf5438fc JB |
1 | /* |
2 | * jump label support | |
3 | * | |
4 | * Copyright (C) 2009 Jason Baron <jbaron@redhat.com> | |
90eec103 | 5 | * Copyright (C) 2011 Peter Zijlstra |
bf5438fc JB |
6 | * |
7 | */ | |
bf5438fc JB |
8 | #include <linux/memory.h> |
9 | #include <linux/uaccess.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/list.h> | |
bf5438fc JB |
12 | #include <linux/slab.h> |
13 | #include <linux/sort.h> | |
14 | #include <linux/err.h> | |
c5905afb | 15 | #include <linux/static_key.h> |
851cf6e7 | 16 | #include <linux/jump_label_ratelimit.h> |
1f69bf9c | 17 | #include <linux/bug.h> |
f2545b2d | 18 | #include <linux/cpu.h> |
578ae447 | 19 | #include <asm/sections.h> |
bf5438fc JB |
20 | |
21 | #ifdef HAVE_JUMP_LABEL | |
22 | ||
bf5438fc JB |
23 | /* mutex to protect coming/going of the the jump_label table */ |
24 | static DEFINE_MUTEX(jump_label_mutex); | |
25 | ||
91bad2f8 JB |
26 | void jump_label_lock(void) |
27 | { | |
28 | mutex_lock(&jump_label_mutex); | |
29 | } | |
30 | ||
31 | void jump_label_unlock(void) | |
32 | { | |
33 | mutex_unlock(&jump_label_mutex); | |
34 | } | |
35 | ||
bf5438fc JB |
36 | static int jump_label_cmp(const void *a, const void *b) |
37 | { | |
38 | const struct jump_entry *jea = a; | |
39 | const struct jump_entry *jeb = b; | |
40 | ||
9ae033ac | 41 | if (jump_entry_key(jea) < jump_entry_key(jeb)) |
bf5438fc JB |
42 | return -1; |
43 | ||
9ae033ac | 44 | if (jump_entry_key(jea) > jump_entry_key(jeb)) |
bf5438fc JB |
45 | return 1; |
46 | ||
47 | return 0; | |
48 | } | |
49 | ||
50ff18ab AB |
50 | static void jump_label_swap(void *a, void *b, int size) |
51 | { | |
52 | long delta = (unsigned long)a - (unsigned long)b; | |
53 | struct jump_entry *jea = a; | |
54 | struct jump_entry *jeb = b; | |
55 | struct jump_entry tmp = *jea; | |
56 | ||
57 | jea->code = jeb->code - delta; | |
58 | jea->target = jeb->target - delta; | |
59 | jea->key = jeb->key - delta; | |
60 | ||
61 | jeb->code = tmp.code + delta; | |
62 | jeb->target = tmp.target + delta; | |
63 | jeb->key = tmp.key + delta; | |
64 | } | |
65 | ||
bf5438fc | 66 | static void |
d430d3d7 | 67 | jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) |
bf5438fc JB |
68 | { |
69 | unsigned long size; | |
50ff18ab AB |
70 | void *swapfn = NULL; |
71 | ||
72 | if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE)) | |
73 | swapfn = jump_label_swap; | |
bf5438fc JB |
74 | |
75 | size = (((unsigned long)stop - (unsigned long)start) | |
76 | / sizeof(struct jump_entry)); | |
50ff18ab | 77 | sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn); |
bf5438fc JB |
78 | } |
79 | ||
706249c2 | 80 | static void jump_label_update(struct static_key *key); |
a1efb01f | 81 | |
1f69bf9c JB |
82 | /* |
83 | * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h. | |
84 | * The use of 'atomic_read()' requires atomic.h and its problematic for some | |
85 | * kernel headers such as kernel.h and others. Since static_key_count() is not | |
86 | * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok | |
87 | * to have it be a function here. Similarly, for 'static_key_enable()' and | |
88 | * 'static_key_disable()', which require bug.h. This should allow jump_label.h | |
89 | * to be included from most/all places for HAVE_JUMP_LABEL. | |
90 | */ | |
91 | int static_key_count(struct static_key *key) | |
92 | { | |
93 | /* | |
94 | * -1 means the first static_key_slow_inc() is in progress. | |
95 | * static_key_enabled() must return true, so return 1 here. | |
96 | */ | |
97 | int n = atomic_read(&key->enabled); | |
98 | ||
99 | return n >= 0 ? n : 1; | |
100 | } | |
101 | EXPORT_SYMBOL_GPL(static_key_count); | |
102 | ||
ce48c146 | 103 | void static_key_slow_inc_cpuslocked(struct static_key *key) |
bf5438fc | 104 | { |
4c5ea0a9 PB |
105 | int v, v1; |
106 | ||
5cdda511 | 107 | STATIC_KEY_CHECK_USE(key); |
4c5ea0a9 PB |
108 | |
109 | /* | |
110 | * Careful if we get concurrent static_key_slow_inc() calls; | |
111 | * later calls must wait for the first one to _finish_ the | |
112 | * jump_label_update() process. At the same time, however, | |
113 | * the jump_label_update() call below wants to see | |
114 | * static_key_enabled(&key) for jumps to be updated properly. | |
115 | * | |
116 | * So give a special meaning to negative key->enabled: it sends | |
117 | * static_key_slow_inc() down the slow path, and it is non-zero | |
118 | * so it counts as "enabled" in jump_label_update(). Note that | |
119 | * atomic_inc_unless_negative() checks >= 0, so roll our own. | |
120 | */ | |
121 | for (v = atomic_read(&key->enabled); v > 0; v = v1) { | |
122 | v1 = atomic_cmpxchg(&key->enabled, v, v + 1); | |
8b7b4128 | 123 | if (likely(v1 == v)) |
4c5ea0a9 PB |
124 | return; |
125 | } | |
bf5438fc | 126 | |
d430d3d7 | 127 | jump_label_lock(); |
4c5ea0a9 PB |
128 | if (atomic_read(&key->enabled) == 0) { |
129 | atomic_set(&key->enabled, -1); | |
706249c2 | 130 | jump_label_update(key); |
d0646a6f PZ |
131 | /* |
132 | * Ensure that if the above cmpxchg loop observes our positive | |
133 | * value, it must also observe all the text changes. | |
134 | */ | |
135 | atomic_set_release(&key->enabled, 1); | |
4c5ea0a9 PB |
136 | } else { |
137 | atomic_inc(&key->enabled); | |
138 | } | |
d430d3d7 | 139 | jump_label_unlock(); |
8b7b4128 MZ |
140 | } |
141 | ||
142 | void static_key_slow_inc(struct static_key *key) | |
143 | { | |
144 | cpus_read_lock(); | |
145 | static_key_slow_inc_cpuslocked(key); | |
f2545b2d | 146 | cpus_read_unlock(); |
bf5438fc | 147 | } |
c5905afb | 148 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
bf5438fc | 149 | |
5a40527f | 150 | void static_key_enable_cpuslocked(struct static_key *key) |
1dbb6704 | 151 | { |
5cdda511 | 152 | STATIC_KEY_CHECK_USE(key); |
5a40527f | 153 | |
1dbb6704 PB |
154 | if (atomic_read(&key->enabled) > 0) { |
155 | WARN_ON_ONCE(atomic_read(&key->enabled) != 1); | |
156 | return; | |
157 | } | |
158 | ||
1dbb6704 PB |
159 | jump_label_lock(); |
160 | if (atomic_read(&key->enabled) == 0) { | |
161 | atomic_set(&key->enabled, -1); | |
162 | jump_label_update(key); | |
d0646a6f PZ |
163 | /* |
164 | * See static_key_slow_inc(). | |
165 | */ | |
166 | atomic_set_release(&key->enabled, 1); | |
1dbb6704 PB |
167 | } |
168 | jump_label_unlock(); | |
5a40527f MZ |
169 | } |
170 | EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked); | |
171 | ||
172 | void static_key_enable(struct static_key *key) | |
173 | { | |
174 | cpus_read_lock(); | |
175 | static_key_enable_cpuslocked(key); | |
1dbb6704 PB |
176 | cpus_read_unlock(); |
177 | } | |
178 | EXPORT_SYMBOL_GPL(static_key_enable); | |
179 | ||
5a40527f | 180 | void static_key_disable_cpuslocked(struct static_key *key) |
1dbb6704 | 181 | { |
5cdda511 | 182 | STATIC_KEY_CHECK_USE(key); |
5a40527f | 183 | |
1dbb6704 PB |
184 | if (atomic_read(&key->enabled) != 1) { |
185 | WARN_ON_ONCE(atomic_read(&key->enabled) != 0); | |
186 | return; | |
187 | } | |
188 | ||
1dbb6704 PB |
189 | jump_label_lock(); |
190 | if (atomic_cmpxchg(&key->enabled, 1, 0)) | |
191 | jump_label_update(key); | |
192 | jump_label_unlock(); | |
5a40527f MZ |
193 | } |
194 | EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked); | |
195 | ||
196 | void static_key_disable(struct static_key *key) | |
197 | { | |
198 | cpus_read_lock(); | |
199 | static_key_disable_cpuslocked(key); | |
1dbb6704 PB |
200 | cpus_read_unlock(); |
201 | } | |
202 | EXPORT_SYMBOL_GPL(static_key_disable); | |
203 | ||
ce48c146 | 204 | static void __static_key_slow_dec_cpuslocked(struct static_key *key, |
8b7b4128 MZ |
205 | unsigned long rate_limit, |
206 | struct delayed_work *work) | |
bf5438fc | 207 | { |
4c5ea0a9 PB |
208 | /* |
209 | * The negative count check is valid even when a negative | |
210 | * key->enabled is in use by static_key_slow_inc(); a | |
211 | * __static_key_slow_dec() before the first static_key_slow_inc() | |
212 | * returns is unbalanced, because all other static_key_slow_inc() | |
213 | * instances block while the update is in progress. | |
214 | */ | |
fadf0464 JB |
215 | if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { |
216 | WARN(atomic_read(&key->enabled) < 0, | |
217 | "jump label: negative count!\n"); | |
d430d3d7 | 218 | return; |
fadf0464 | 219 | } |
bf5438fc | 220 | |
b2029520 GN |
221 | if (rate_limit) { |
222 | atomic_inc(&key->enabled); | |
223 | schedule_delayed_work(work, rate_limit); | |
c5905afb | 224 | } else { |
706249c2 | 225 | jump_label_update(key); |
c5905afb | 226 | } |
91bad2f8 | 227 | jump_label_unlock(); |
8b7b4128 MZ |
228 | } |
229 | ||
230 | static void __static_key_slow_dec(struct static_key *key, | |
231 | unsigned long rate_limit, | |
232 | struct delayed_work *work) | |
233 | { | |
234 | cpus_read_lock(); | |
ce48c146 | 235 | __static_key_slow_dec_cpuslocked(key, rate_limit, work); |
f2545b2d | 236 | cpus_read_unlock(); |
bf5438fc JB |
237 | } |
238 | ||
b2029520 GN |
239 | static void jump_label_update_timeout(struct work_struct *work) |
240 | { | |
c5905afb IM |
241 | struct static_key_deferred *key = |
242 | container_of(work, struct static_key_deferred, work.work); | |
243 | __static_key_slow_dec(&key->key, 0, NULL); | |
b2029520 GN |
244 | } |
245 | ||
c5905afb | 246 | void static_key_slow_dec(struct static_key *key) |
b2029520 | 247 | { |
5cdda511 | 248 | STATIC_KEY_CHECK_USE(key); |
c5905afb | 249 | __static_key_slow_dec(key, 0, NULL); |
b2029520 | 250 | } |
c5905afb | 251 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
b2029520 | 252 | |
ce48c146 PZ |
253 | void static_key_slow_dec_cpuslocked(struct static_key *key) |
254 | { | |
255 | STATIC_KEY_CHECK_USE(key); | |
256 | __static_key_slow_dec_cpuslocked(key, 0, NULL); | |
257 | } | |
258 | ||
c5905afb | 259 | void static_key_slow_dec_deferred(struct static_key_deferred *key) |
b2029520 | 260 | { |
5cdda511 | 261 | STATIC_KEY_CHECK_USE(key); |
c5905afb | 262 | __static_key_slow_dec(&key->key, key->timeout, &key->work); |
b2029520 | 263 | } |
c5905afb | 264 | EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); |
b2029520 | 265 | |
b6416e61 DM |
266 | void static_key_deferred_flush(struct static_key_deferred *key) |
267 | { | |
5cdda511 | 268 | STATIC_KEY_CHECK_USE(key); |
b6416e61 DM |
269 | flush_delayed_work(&key->work); |
270 | } | |
271 | EXPORT_SYMBOL_GPL(static_key_deferred_flush); | |
272 | ||
c5905afb | 273 | void jump_label_rate_limit(struct static_key_deferred *key, |
b2029520 GN |
274 | unsigned long rl) |
275 | { | |
5cdda511 | 276 | STATIC_KEY_CHECK_USE(key); |
b2029520 GN |
277 | key->timeout = rl; |
278 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
279 | } | |
a181dc14 | 280 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
b2029520 | 281 | |
4c3ef6d7 JB |
282 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
283 | { | |
9ae033ac AB |
284 | if (jump_entry_code(entry) <= (unsigned long)end && |
285 | jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start) | |
4c3ef6d7 JB |
286 | return 1; |
287 | ||
288 | return 0; | |
289 | } | |
290 | ||
d430d3d7 JB |
291 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
292 | struct jump_entry *iter_stop, void *start, void *end) | |
4c3ef6d7 | 293 | { |
4c3ef6d7 | 294 | struct jump_entry *iter; |
4c3ef6d7 | 295 | |
4c3ef6d7 JB |
296 | iter = iter_start; |
297 | while (iter < iter_stop) { | |
d430d3d7 JB |
298 | if (addr_conflict(iter, start, end)) |
299 | return 1; | |
4c3ef6d7 JB |
300 | iter++; |
301 | } | |
302 | ||
d430d3d7 JB |
303 | return 0; |
304 | } | |
305 | ||
706249c2 | 306 | /* |
20284aa7 JF |
307 | * Update code which is definitely not currently executing. |
308 | * Architectures which need heavyweight synchronization to modify | |
309 | * running code can override this to make the non-live update case | |
310 | * cheaper. | |
311 | */ | |
9cdbe1cb | 312 | void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, |
20284aa7 JF |
313 | enum jump_label_type type) |
314 | { | |
706249c2 | 315 | arch_jump_label_transform(entry, type); |
20284aa7 JF |
316 | } |
317 | ||
706249c2 | 318 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
d430d3d7 | 319 | { |
3821fd35 JB |
320 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
321 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
4c3ef6d7 JB |
322 | } |
323 | ||
706249c2 | 324 | static inline bool static_key_type(struct static_key *key) |
c5905afb | 325 | { |
3821fd35 JB |
326 | return key->type & JUMP_TYPE_TRUE; |
327 | } | |
328 | ||
329 | static inline bool static_key_linked(struct static_key *key) | |
330 | { | |
331 | return key->type & JUMP_TYPE_LINKED; | |
332 | } | |
333 | ||
334 | static inline void static_key_clear_linked(struct static_key *key) | |
335 | { | |
336 | key->type &= ~JUMP_TYPE_LINKED; | |
337 | } | |
338 | ||
339 | static inline void static_key_set_linked(struct static_key *key) | |
340 | { | |
341 | key->type |= JUMP_TYPE_LINKED; | |
a1efb01f | 342 | } |
c5905afb | 343 | |
3821fd35 JB |
344 | /*** |
345 | * A 'struct static_key' uses a union such that it either points directly | |
346 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
347 | * turn point to 'struct jump_entry' tables. | |
348 | * | |
349 | * The two lower bits of the pointer are used to keep track of which pointer | |
350 | * type is in use and to store the initial branch direction, we use an access | |
351 | * function which preserves these bits. | |
352 | */ | |
353 | static void static_key_set_entries(struct static_key *key, | |
354 | struct jump_entry *entries) | |
355 | { | |
356 | unsigned long type; | |
357 | ||
358 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
359 | type = key->type & JUMP_TYPE_MASK; | |
360 | key->entries = entries; | |
361 | key->type |= type; | |
362 | } | |
363 | ||
706249c2 | 364 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
a1efb01f | 365 | { |
706249c2 | 366 | struct static_key *key = jump_entry_key(entry); |
a1efb01f | 367 | bool enabled = static_key_enabled(key); |
9ae033ac | 368 | bool branch = jump_entry_is_branch(entry); |
c5905afb | 369 | |
11276d53 PZ |
370 | /* See the comment in linux/jump_label.h */ |
371 | return enabled ^ branch; | |
c5905afb IM |
372 | } |
373 | ||
706249c2 PZ |
374 | static void __jump_label_update(struct static_key *key, |
375 | struct jump_entry *entry, | |
376 | struct jump_entry *stop) | |
377 | { | |
378 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
379 | /* | |
dc1dd184 JP |
380 | * An entry->code of 0 indicates an entry which has been |
381 | * disabled because it was in an init text area. | |
706249c2 | 382 | */ |
9ae033ac AB |
383 | if (!jump_entry_is_init(entry)) { |
384 | if (kernel_text_address(jump_entry_code(entry))) | |
dc1dd184 JP |
385 | arch_jump_label_transform(entry, jump_label_type(entry)); |
386 | else | |
af1d830b | 387 | WARN_ONCE(1, "can't patch jump_label at %pS", |
9ae033ac | 388 | (void *)jump_entry_code(entry)); |
dc1dd184 | 389 | } |
706249c2 PZ |
390 | } |
391 | } | |
392 | ||
97ce2c88 | 393 | void __init jump_label_init(void) |
bf5438fc | 394 | { |
bf5438fc JB |
395 | struct jump_entry *iter_start = __start___jump_table; |
396 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 397 | struct static_key *key = NULL; |
bf5438fc JB |
398 | struct jump_entry *iter; |
399 | ||
1f69bf9c JB |
400 | /* |
401 | * Since we are initializing the static_key.enabled field with | |
402 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
403 | * jump_label.h, let's make sure that is safe. There are only two | |
404 | * cases to check since we initialize to 0 or 1. | |
405 | */ | |
406 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
407 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
408 | ||
e3f91083 KH |
409 | if (static_key_initialized) |
410 | return; | |
411 | ||
f2545b2d | 412 | cpus_read_lock(); |
91bad2f8 | 413 | jump_label_lock(); |
d430d3d7 JB |
414 | jump_label_sort_entries(iter_start, iter_stop); |
415 | ||
416 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 417 | struct static_key *iterk; |
37348804 | 418 | |
11276d53 PZ |
419 | /* rewrite NOPs */ |
420 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
421 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
422 | ||
7dcfd915 | 423 | iterk = jump_entry_key(iter); |
37348804 | 424 | if (iterk == key) |
d430d3d7 JB |
425 | continue; |
426 | ||
37348804 | 427 | key = iterk; |
3821fd35 | 428 | static_key_set_entries(key, iter); |
bf5438fc | 429 | } |
c4b2c0c5 | 430 | static_key_initialized = true; |
91bad2f8 | 431 | jump_label_unlock(); |
f2545b2d | 432 | cpus_read_unlock(); |
bf5438fc | 433 | } |
bf5438fc | 434 | |
578ae447 JP |
435 | /* Disable any jump label entries in __init/__exit code */ |
436 | void __init jump_label_invalidate_initmem(void) | |
33352244 JP |
437 | { |
438 | struct jump_entry *iter_start = __start___jump_table; | |
439 | struct jump_entry *iter_stop = __stop___jump_table; | |
440 | struct jump_entry *iter; | |
441 | ||
442 | for (iter = iter_start; iter < iter_stop; iter++) { | |
9ae033ac AB |
443 | if (init_section_contains((void *)jump_entry_code(iter), 1)) |
444 | jump_entry_set_init(iter); | |
33352244 JP |
445 | } |
446 | } | |
447 | ||
bf5438fc JB |
448 | #ifdef CONFIG_MODULES |
449 | ||
11276d53 PZ |
450 | static enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
451 | { | |
452 | struct static_key *key = jump_entry_key(entry); | |
453 | bool type = static_key_type(key); | |
9ae033ac | 454 | bool branch = jump_entry_is_branch(entry); |
11276d53 PZ |
455 | |
456 | /* See the comment in linux/jump_label.h */ | |
457 | return type ^ branch; | |
458 | } | |
459 | ||
c5905afb IM |
460 | struct static_key_mod { |
461 | struct static_key_mod *next; | |
d430d3d7 JB |
462 | struct jump_entry *entries; |
463 | struct module *mod; | |
464 | }; | |
465 | ||
3821fd35 JB |
466 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
467 | { | |
468 | WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED)); | |
469 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); | |
470 | } | |
471 | ||
472 | /*** | |
473 | * key->type and key->next are the same via union. | |
474 | * This sets key->next and preserves the type bits. | |
475 | * | |
476 | * See additional comments above static_key_set_entries(). | |
477 | */ | |
478 | static void static_key_set_mod(struct static_key *key, | |
479 | struct static_key_mod *mod) | |
480 | { | |
481 | unsigned long type; | |
482 | ||
483 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
484 | type = key->type & JUMP_TYPE_MASK; | |
485 | key->next = mod; | |
486 | key->type |= type; | |
487 | } | |
488 | ||
d430d3d7 JB |
489 | static int __jump_label_mod_text_reserved(void *start, void *end) |
490 | { | |
491 | struct module *mod; | |
492 | ||
bdc9f373 | 493 | preempt_disable(); |
d430d3d7 | 494 | mod = __module_text_address((unsigned long)start); |
bdc9f373 RR |
495 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
496 | preempt_enable(); | |
497 | ||
d430d3d7 JB |
498 | if (!mod) |
499 | return 0; | |
500 | ||
d430d3d7 JB |
501 | |
502 | return __jump_label_text_reserved(mod->jump_entries, | |
503 | mod->jump_entries + mod->num_jump_entries, | |
504 | start, end); | |
505 | } | |
506 | ||
706249c2 | 507 | static void __jump_label_mod_update(struct static_key *key) |
d430d3d7 | 508 | { |
706249c2 | 509 | struct static_key_mod *mod; |
d430d3d7 | 510 | |
3821fd35 JB |
511 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
512 | struct jump_entry *stop; | |
513 | struct module *m; | |
514 | ||
515 | /* | |
516 | * NULL if the static_key is defined in a module | |
517 | * that does not use it | |
518 | */ | |
519 | if (!mod->entries) | |
520 | continue; | |
7cbc5b8d | 521 | |
3821fd35 JB |
522 | m = mod->mod; |
523 | if (!m) | |
524 | stop = __stop___jump_table; | |
525 | else | |
526 | stop = m->jump_entries + m->num_jump_entries; | |
527 | __jump_label_update(key, mod->entries, stop); | |
d430d3d7 JB |
528 | } |
529 | } | |
530 | ||
531 | /*** | |
532 | * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() | |
533 | * @mod: module to patch | |
534 | * | |
535 | * Allow for run-time selection of the optimal nops. Before the module | |
536 | * loads patch these with arch_get_jump_label_nop(), which is specified by | |
537 | * the arch specific jump label code. | |
538 | */ | |
539 | void jump_label_apply_nops(struct module *mod) | |
bf5438fc | 540 | { |
d430d3d7 JB |
541 | struct jump_entry *iter_start = mod->jump_entries; |
542 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
543 | struct jump_entry *iter; | |
544 | ||
545 | /* if the module doesn't have jump label entries, just return */ | |
546 | if (iter_start == iter_stop) | |
547 | return; | |
548 | ||
11276d53 PZ |
549 | for (iter = iter_start; iter < iter_stop; iter++) { |
550 | /* Only write NOPs for arch_branch_static(). */ | |
551 | if (jump_label_init_type(iter) == JUMP_LABEL_NOP) | |
552 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
553 | } | |
bf5438fc JB |
554 | } |
555 | ||
d430d3d7 | 556 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 557 | { |
d430d3d7 JB |
558 | struct jump_entry *iter_start = mod->jump_entries; |
559 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
560 | struct jump_entry *iter; | |
c5905afb | 561 | struct static_key *key = NULL; |
3821fd35 | 562 | struct static_key_mod *jlm, *jlm2; |
bf5438fc JB |
563 | |
564 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 565 | if (iter_start == iter_stop) |
bf5438fc JB |
566 | return 0; |
567 | ||
d430d3d7 JB |
568 | jump_label_sort_entries(iter_start, iter_stop); |
569 | ||
570 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 571 | struct static_key *iterk; |
d430d3d7 | 572 | |
7dcfd915 | 573 | iterk = jump_entry_key(iter); |
c5905afb IM |
574 | if (iterk == key) |
575 | continue; | |
d430d3d7 | 576 | |
c5905afb | 577 | key = iterk; |
9ae033ac | 578 | if (within_module((unsigned long)key, mod)) { |
3821fd35 | 579 | static_key_set_entries(key, iter); |
d430d3d7 | 580 | continue; |
bf5438fc | 581 | } |
c5905afb | 582 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
583 | if (!jlm) |
584 | return -ENOMEM; | |
3821fd35 JB |
585 | if (!static_key_linked(key)) { |
586 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
587 | GFP_KERNEL); | |
588 | if (!jlm2) { | |
589 | kfree(jlm); | |
590 | return -ENOMEM; | |
591 | } | |
592 | preempt_disable(); | |
593 | jlm2->mod = __module_address((unsigned long)key); | |
594 | preempt_enable(); | |
595 | jlm2->entries = static_key_entries(key); | |
596 | jlm2->next = NULL; | |
597 | static_key_set_mod(key, jlm2); | |
598 | static_key_set_linked(key); | |
599 | } | |
d430d3d7 JB |
600 | jlm->mod = mod; |
601 | jlm->entries = iter; | |
3821fd35 JB |
602 | jlm->next = static_key_mod(key); |
603 | static_key_set_mod(key, jlm); | |
604 | static_key_set_linked(key); | |
d430d3d7 | 605 | |
11276d53 PZ |
606 | /* Only update if we've changed from our initial state */ |
607 | if (jump_label_type(iter) != jump_label_init_type(iter)) | |
706249c2 | 608 | __jump_label_update(key, iter, iter_stop); |
bf5438fc | 609 | } |
d430d3d7 | 610 | |
bf5438fc JB |
611 | return 0; |
612 | } | |
613 | ||
d430d3d7 | 614 | static void jump_label_del_module(struct module *mod) |
bf5438fc | 615 | { |
d430d3d7 JB |
616 | struct jump_entry *iter_start = mod->jump_entries; |
617 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
618 | struct jump_entry *iter; | |
c5905afb IM |
619 | struct static_key *key = NULL; |
620 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 621 | |
d430d3d7 | 622 | for (iter = iter_start; iter < iter_stop; iter++) { |
7dcfd915 | 623 | if (jump_entry_key(iter) == key) |
d430d3d7 JB |
624 | continue; |
625 | ||
7dcfd915 | 626 | key = jump_entry_key(iter); |
d430d3d7 | 627 | |
9ae033ac | 628 | if (within_module((unsigned long)key, mod)) |
d430d3d7 JB |
629 | continue; |
630 | ||
3821fd35 JB |
631 | /* No memory during module load */ |
632 | if (WARN_ON(!static_key_linked(key))) | |
633 | continue; | |
634 | ||
d430d3d7 | 635 | prev = &key->next; |
3821fd35 | 636 | jlm = static_key_mod(key); |
bf5438fc | 637 | |
d430d3d7 JB |
638 | while (jlm && jlm->mod != mod) { |
639 | prev = &jlm->next; | |
640 | jlm = jlm->next; | |
641 | } | |
642 | ||
3821fd35 JB |
643 | /* No memory during module load */ |
644 | if (WARN_ON(!jlm)) | |
645 | continue; | |
646 | ||
647 | if (prev == &key->next) | |
648 | static_key_set_mod(key, jlm->next); | |
649 | else | |
d430d3d7 | 650 | *prev = jlm->next; |
3821fd35 JB |
651 | |
652 | kfree(jlm); | |
653 | ||
654 | jlm = static_key_mod(key); | |
655 | /* if only one etry is left, fold it back into the static_key */ | |
656 | if (jlm->next == NULL) { | |
657 | static_key_set_entries(key, jlm->entries); | |
658 | static_key_clear_linked(key); | |
d430d3d7 | 659 | kfree(jlm); |
bf5438fc JB |
660 | } |
661 | } | |
662 | } | |
663 | ||
33352244 | 664 | /* Disable any jump label entries in module init code */ |
d430d3d7 | 665 | static void jump_label_invalidate_module_init(struct module *mod) |
b842f8fa | 666 | { |
d430d3d7 JB |
667 | struct jump_entry *iter_start = mod->jump_entries; |
668 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
b842f8fa | 669 | struct jump_entry *iter; |
b842f8fa | 670 | |
d430d3d7 | 671 | for (iter = iter_start; iter < iter_stop; iter++) { |
9ae033ac AB |
672 | if (within_module_init(jump_entry_code(iter), mod)) |
673 | jump_entry_set_init(iter); | |
b842f8fa JB |
674 | } |
675 | } | |
676 | ||
bf5438fc JB |
677 | static int |
678 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
679 | void *data) | |
680 | { | |
681 | struct module *mod = data; | |
682 | int ret = 0; | |
683 | ||
f2545b2d TG |
684 | cpus_read_lock(); |
685 | jump_label_lock(); | |
686 | ||
bf5438fc JB |
687 | switch (val) { |
688 | case MODULE_STATE_COMING: | |
d430d3d7 | 689 | ret = jump_label_add_module(mod); |
3821fd35 | 690 | if (ret) { |
da260fe1 | 691 | WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); |
d430d3d7 | 692 | jump_label_del_module(mod); |
3821fd35 | 693 | } |
bf5438fc JB |
694 | break; |
695 | case MODULE_STATE_GOING: | |
d430d3d7 | 696 | jump_label_del_module(mod); |
bf5438fc | 697 | break; |
b842f8fa | 698 | case MODULE_STATE_LIVE: |
d430d3d7 | 699 | jump_label_invalidate_module_init(mod); |
b842f8fa | 700 | break; |
bf5438fc | 701 | } |
bf5438fc | 702 | |
f2545b2d TG |
703 | jump_label_unlock(); |
704 | cpus_read_unlock(); | |
705 | ||
d430d3d7 | 706 | return notifier_from_errno(ret); |
bf5438fc JB |
707 | } |
708 | ||
885885f6 | 709 | static struct notifier_block jump_label_module_nb = { |
bf5438fc | 710 | .notifier_call = jump_label_module_notify, |
d430d3d7 | 711 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
712 | }; |
713 | ||
d430d3d7 | 714 | static __init int jump_label_init_module(void) |
bf5438fc JB |
715 | { |
716 | return register_module_notifier(&jump_label_module_nb); | |
717 | } | |
d430d3d7 | 718 | early_initcall(jump_label_init_module); |
bf5438fc JB |
719 | |
720 | #endif /* CONFIG_MODULES */ | |
721 | ||
d430d3d7 JB |
722 | /*** |
723 | * jump_label_text_reserved - check if addr range is reserved | |
724 | * @start: start text addr | |
725 | * @end: end text addr | |
726 | * | |
727 | * checks if the text addr located between @start and @end | |
728 | * overlaps with any of the jump label patch addresses. Code | |
729 | * that wants to modify kernel text should first verify that | |
730 | * it does not overlap with any of the jump label addresses. | |
731 | * Caller must hold jump_label_mutex. | |
732 | * | |
733 | * returns 1 if there is an overlap, 0 otherwise | |
734 | */ | |
735 | int jump_label_text_reserved(void *start, void *end) | |
736 | { | |
737 | int ret = __jump_label_text_reserved(__start___jump_table, | |
738 | __stop___jump_table, start, end); | |
739 | ||
740 | if (ret) | |
741 | return ret; | |
742 | ||
743 | #ifdef CONFIG_MODULES | |
744 | ret = __jump_label_mod_text_reserved(start, end); | |
745 | #endif | |
746 | return ret; | |
747 | } | |
748 | ||
706249c2 | 749 | static void jump_label_update(struct static_key *key) |
d430d3d7 | 750 | { |
c5905afb | 751 | struct jump_entry *stop = __stop___jump_table; |
3821fd35 | 752 | struct jump_entry *entry; |
d430d3d7 | 753 | #ifdef CONFIG_MODULES |
bed831f9 | 754 | struct module *mod; |
140fe3b1 | 755 | |
3821fd35 JB |
756 | if (static_key_linked(key)) { |
757 | __jump_label_mod_update(key); | |
758 | return; | |
759 | } | |
140fe3b1 | 760 | |
bed831f9 PZ |
761 | preempt_disable(); |
762 | mod = __module_address((unsigned long)key); | |
140fe3b1 XG |
763 | if (mod) |
764 | stop = mod->jump_entries + mod->num_jump_entries; | |
bed831f9 | 765 | preempt_enable(); |
d430d3d7 | 766 | #endif |
3821fd35 | 767 | entry = static_key_entries(key); |
140fe3b1 XG |
768 | /* if there are no users, entry can be NULL */ |
769 | if (entry) | |
706249c2 | 770 | __jump_label_update(key, entry, stop); |
d430d3d7 JB |
771 | } |
772 | ||
1987c947 PZ |
773 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
774 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
775 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
776 | ||
777 | static __init int jump_label_test(void) | |
778 | { | |
779 | int i; | |
780 | ||
781 | for (i = 0; i < 2; i++) { | |
782 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
783 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
784 | ||
785 | WARN_ON(!static_branch_likely(&sk_true)); | |
786 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
787 | WARN_ON(static_branch_likely(&sk_false)); | |
788 | WARN_ON(static_branch_unlikely(&sk_false)); | |
789 | ||
790 | static_branch_disable(&sk_true); | |
791 | static_branch_enable(&sk_false); | |
792 | ||
793 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
794 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
795 | ||
796 | WARN_ON(static_branch_likely(&sk_true)); | |
797 | WARN_ON(static_branch_unlikely(&sk_true)); | |
798 | WARN_ON(!static_branch_likely(&sk_false)); | |
799 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
800 | ||
801 | static_branch_enable(&sk_true); | |
802 | static_branch_disable(&sk_false); | |
803 | } | |
804 | ||
805 | return 0; | |
806 | } | |
92ee46ef | 807 | early_initcall(jump_label_test); |
1987c947 PZ |
808 | #endif /* STATIC_KEYS_SELFTEST */ |
809 | ||
810 | #endif /* HAVE_JUMP_LABEL */ |