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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 | ||
9ae033ac | 40 | if (jump_entry_key(jea) < jump_entry_key(jeb)) |
bf5438fc JB |
41 | return -1; |
42 | ||
9ae033ac | 43 | if (jump_entry_key(jea) > jump_entry_key(jeb)) |
bf5438fc JB |
44 | return 1; |
45 | ||
46 | return 0; | |
47 | } | |
48 | ||
50ff18ab AB |
49 | static void jump_label_swap(void *a, void *b, int size) |
50 | { | |
51 | long delta = (unsigned long)a - (unsigned long)b; | |
52 | struct jump_entry *jea = a; | |
53 | struct jump_entry *jeb = b; | |
54 | struct jump_entry tmp = *jea; | |
55 | ||
56 | jea->code = jeb->code - delta; | |
57 | jea->target = jeb->target - delta; | |
58 | jea->key = jeb->key - delta; | |
59 | ||
60 | jeb->code = tmp.code + delta; | |
61 | jeb->target = tmp.target + delta; | |
62 | jeb->key = tmp.key + delta; | |
63 | } | |
64 | ||
bf5438fc | 65 | static void |
d430d3d7 | 66 | jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) |
bf5438fc JB |
67 | { |
68 | unsigned long size; | |
50ff18ab AB |
69 | void *swapfn = NULL; |
70 | ||
71 | if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE)) | |
72 | swapfn = jump_label_swap; | |
bf5438fc JB |
73 | |
74 | size = (((unsigned long)stop - (unsigned long)start) | |
75 | / sizeof(struct jump_entry)); | |
50ff18ab | 76 | sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn); |
bf5438fc JB |
77 | } |
78 | ||
706249c2 | 79 | static void jump_label_update(struct static_key *key); |
a1efb01f | 80 | |
1f69bf9c | 81 | /* |
e9666d10 | 82 | * There are similar definitions for the !CONFIG_JUMP_LABEL case in jump_label.h. |
1f69bf9c JB |
83 | * The use of 'atomic_read()' requires atomic.h and its problematic for some |
84 | * kernel headers such as kernel.h and others. Since static_key_count() is not | |
e9666d10 | 85 | * used in the branch statements as it is for the !CONFIG_JUMP_LABEL case its ok |
1f69bf9c JB |
86 | * to have it be a function here. Similarly, for 'static_key_enable()' and |
87 | * 'static_key_disable()', which require bug.h. This should allow jump_label.h | |
e9666d10 | 88 | * to be included from most/all places for CONFIG_JUMP_LABEL. |
1f69bf9c JB |
89 | */ |
90 | int static_key_count(struct static_key *key) | |
91 | { | |
92 | /* | |
93 | * -1 means the first static_key_slow_inc() is in progress. | |
94 | * static_key_enabled() must return true, so return 1 here. | |
95 | */ | |
96 | int n = atomic_read(&key->enabled); | |
97 | ||
98 | return n >= 0 ? n : 1; | |
99 | } | |
100 | EXPORT_SYMBOL_GPL(static_key_count); | |
101 | ||
ce48c146 | 102 | void static_key_slow_inc_cpuslocked(struct static_key *key) |
bf5438fc | 103 | { |
4c5ea0a9 PB |
104 | int v, v1; |
105 | ||
5cdda511 | 106 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 107 | lockdep_assert_cpus_held(); |
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); |
cb538267 | 153 | lockdep_assert_cpus_held(); |
5a40527f | 154 | |
1dbb6704 PB |
155 | if (atomic_read(&key->enabled) > 0) { |
156 | WARN_ON_ONCE(atomic_read(&key->enabled) != 1); | |
157 | return; | |
158 | } | |
159 | ||
1dbb6704 PB |
160 | jump_label_lock(); |
161 | if (atomic_read(&key->enabled) == 0) { | |
162 | atomic_set(&key->enabled, -1); | |
163 | jump_label_update(key); | |
d0646a6f PZ |
164 | /* |
165 | * See static_key_slow_inc(). | |
166 | */ | |
167 | atomic_set_release(&key->enabled, 1); | |
1dbb6704 PB |
168 | } |
169 | jump_label_unlock(); | |
5a40527f MZ |
170 | } |
171 | EXPORT_SYMBOL_GPL(static_key_enable_cpuslocked); | |
172 | ||
173 | void static_key_enable(struct static_key *key) | |
174 | { | |
175 | cpus_read_lock(); | |
176 | static_key_enable_cpuslocked(key); | |
1dbb6704 PB |
177 | cpus_read_unlock(); |
178 | } | |
179 | EXPORT_SYMBOL_GPL(static_key_enable); | |
180 | ||
5a40527f | 181 | void static_key_disable_cpuslocked(struct static_key *key) |
1dbb6704 | 182 | { |
5cdda511 | 183 | STATIC_KEY_CHECK_USE(key); |
cb538267 | 184 | lockdep_assert_cpus_held(); |
5a40527f | 185 | |
1dbb6704 PB |
186 | if (atomic_read(&key->enabled) != 1) { |
187 | WARN_ON_ONCE(atomic_read(&key->enabled) != 0); | |
188 | return; | |
189 | } | |
190 | ||
1dbb6704 PB |
191 | jump_label_lock(); |
192 | if (atomic_cmpxchg(&key->enabled, 1, 0)) | |
193 | jump_label_update(key); | |
194 | jump_label_unlock(); | |
5a40527f MZ |
195 | } |
196 | EXPORT_SYMBOL_GPL(static_key_disable_cpuslocked); | |
197 | ||
198 | void static_key_disable(struct static_key *key) | |
199 | { | |
200 | cpus_read_lock(); | |
201 | static_key_disable_cpuslocked(key); | |
1dbb6704 PB |
202 | cpus_read_unlock(); |
203 | } | |
204 | EXPORT_SYMBOL_GPL(static_key_disable); | |
205 | ||
b92e793b | 206 | static bool static_key_slow_try_dec(struct static_key *key) |
bf5438fc | 207 | { |
a1247d06 PZ |
208 | int val; |
209 | ||
b92e793b JK |
210 | val = atomic_fetch_add_unless(&key->enabled, -1, 1); |
211 | if (val == 1) | |
212 | return false; | |
cb538267 | 213 | |
4c5ea0a9 PB |
214 | /* |
215 | * The negative count check is valid even when a negative | |
216 | * key->enabled is in use by static_key_slow_inc(); a | |
217 | * __static_key_slow_dec() before the first static_key_slow_inc() | |
218 | * returns is unbalanced, because all other static_key_slow_inc() | |
219 | * instances block while the update is in progress. | |
220 | */ | |
b92e793b JK |
221 | WARN(val < 0, "jump label: negative count!\n"); |
222 | return true; | |
223 | } | |
224 | ||
94b5f312 | 225 | static void __static_key_slow_dec_cpuslocked(struct static_key *key) |
b92e793b JK |
226 | { |
227 | lockdep_assert_cpus_held(); | |
228 | ||
229 | if (static_key_slow_try_dec(key)) | |
d430d3d7 | 230 | return; |
bf5438fc | 231 | |
a1247d06 | 232 | jump_label_lock(); |
94b5f312 JK |
233 | if (atomic_dec_and_test(&key->enabled)) |
234 | jump_label_update(key); | |
91bad2f8 | 235 | jump_label_unlock(); |
8b7b4128 MZ |
236 | } |
237 | ||
94b5f312 | 238 | static void __static_key_slow_dec(struct static_key *key) |
8b7b4128 MZ |
239 | { |
240 | cpus_read_lock(); | |
94b5f312 | 241 | __static_key_slow_dec_cpuslocked(key); |
f2545b2d | 242 | cpus_read_unlock(); |
bf5438fc JB |
243 | } |
244 | ||
ad282a81 | 245 | void jump_label_update_timeout(struct work_struct *work) |
b2029520 | 246 | { |
c5905afb IM |
247 | struct static_key_deferred *key = |
248 | container_of(work, struct static_key_deferred, work.work); | |
94b5f312 | 249 | __static_key_slow_dec(&key->key); |
b2029520 | 250 | } |
ad282a81 | 251 | EXPORT_SYMBOL_GPL(jump_label_update_timeout); |
b2029520 | 252 | |
c5905afb | 253 | void static_key_slow_dec(struct static_key *key) |
b2029520 | 254 | { |
5cdda511 | 255 | STATIC_KEY_CHECK_USE(key); |
94b5f312 | 256 | __static_key_slow_dec(key); |
b2029520 | 257 | } |
c5905afb | 258 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
b2029520 | 259 | |
ce48c146 PZ |
260 | void static_key_slow_dec_cpuslocked(struct static_key *key) |
261 | { | |
262 | STATIC_KEY_CHECK_USE(key); | |
94b5f312 | 263 | __static_key_slow_dec_cpuslocked(key); |
ce48c146 PZ |
264 | } |
265 | ||
ad282a81 JK |
266 | void __static_key_slow_dec_deferred(struct static_key *key, |
267 | struct delayed_work *work, | |
268 | unsigned long timeout) | |
b2029520 | 269 | { |
5cdda511 | 270 | STATIC_KEY_CHECK_USE(key); |
94b5f312 JK |
271 | |
272 | if (static_key_slow_try_dec(key)) | |
273 | return; | |
274 | ||
275 | schedule_delayed_work(work, timeout); | |
b2029520 | 276 | } |
ad282a81 | 277 | EXPORT_SYMBOL_GPL(__static_key_slow_dec_deferred); |
b2029520 | 278 | |
ad282a81 | 279 | void __static_key_deferred_flush(void *key, struct delayed_work *work) |
b6416e61 | 280 | { |
5cdda511 | 281 | STATIC_KEY_CHECK_USE(key); |
ad282a81 | 282 | flush_delayed_work(work); |
b6416e61 | 283 | } |
ad282a81 | 284 | EXPORT_SYMBOL_GPL(__static_key_deferred_flush); |
b6416e61 | 285 | |
c5905afb | 286 | void jump_label_rate_limit(struct static_key_deferred *key, |
b2029520 GN |
287 | unsigned long rl) |
288 | { | |
5cdda511 | 289 | STATIC_KEY_CHECK_USE(key); |
b2029520 GN |
290 | key->timeout = rl; |
291 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
292 | } | |
a181dc14 | 293 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
b2029520 | 294 | |
4c3ef6d7 JB |
295 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
296 | { | |
9ae033ac AB |
297 | if (jump_entry_code(entry) <= (unsigned long)end && |
298 | jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start) | |
4c3ef6d7 JB |
299 | return 1; |
300 | ||
301 | return 0; | |
302 | } | |
303 | ||
d430d3d7 JB |
304 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
305 | struct jump_entry *iter_stop, void *start, void *end) | |
4c3ef6d7 | 306 | { |
4c3ef6d7 | 307 | struct jump_entry *iter; |
4c3ef6d7 | 308 | |
4c3ef6d7 JB |
309 | iter = iter_start; |
310 | while (iter < iter_stop) { | |
d430d3d7 JB |
311 | if (addr_conflict(iter, start, end)) |
312 | return 1; | |
4c3ef6d7 JB |
313 | iter++; |
314 | } | |
315 | ||
d430d3d7 JB |
316 | return 0; |
317 | } | |
318 | ||
706249c2 | 319 | /* |
20284aa7 JF |
320 | * Update code which is definitely not currently executing. |
321 | * Architectures which need heavyweight synchronization to modify | |
322 | * running code can override this to make the non-live update case | |
323 | * cheaper. | |
324 | */ | |
9cdbe1cb | 325 | void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, |
20284aa7 JF |
326 | enum jump_label_type type) |
327 | { | |
706249c2 | 328 | arch_jump_label_transform(entry, type); |
20284aa7 JF |
329 | } |
330 | ||
706249c2 | 331 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
d430d3d7 | 332 | { |
3821fd35 JB |
333 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
334 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
4c3ef6d7 JB |
335 | } |
336 | ||
706249c2 | 337 | static inline bool static_key_type(struct static_key *key) |
c5905afb | 338 | { |
3821fd35 JB |
339 | return key->type & JUMP_TYPE_TRUE; |
340 | } | |
341 | ||
342 | static inline bool static_key_linked(struct static_key *key) | |
343 | { | |
344 | return key->type & JUMP_TYPE_LINKED; | |
345 | } | |
346 | ||
347 | static inline void static_key_clear_linked(struct static_key *key) | |
348 | { | |
349 | key->type &= ~JUMP_TYPE_LINKED; | |
350 | } | |
351 | ||
352 | static inline void static_key_set_linked(struct static_key *key) | |
353 | { | |
354 | key->type |= JUMP_TYPE_LINKED; | |
a1efb01f | 355 | } |
c5905afb | 356 | |
3821fd35 JB |
357 | /*** |
358 | * A 'struct static_key' uses a union such that it either points directly | |
359 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
360 | * turn point to 'struct jump_entry' tables. | |
361 | * | |
362 | * The two lower bits of the pointer are used to keep track of which pointer | |
363 | * type is in use and to store the initial branch direction, we use an access | |
364 | * function which preserves these bits. | |
365 | */ | |
366 | static void static_key_set_entries(struct static_key *key, | |
367 | struct jump_entry *entries) | |
368 | { | |
369 | unsigned long type; | |
370 | ||
371 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
372 | type = key->type & JUMP_TYPE_MASK; | |
373 | key->entries = entries; | |
374 | key->type |= type; | |
375 | } | |
376 | ||
706249c2 | 377 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
a1efb01f | 378 | { |
706249c2 | 379 | struct static_key *key = jump_entry_key(entry); |
a1efb01f | 380 | bool enabled = static_key_enabled(key); |
9ae033ac | 381 | bool branch = jump_entry_is_branch(entry); |
c5905afb | 382 | |
11276d53 PZ |
383 | /* See the comment in linux/jump_label.h */ |
384 | return enabled ^ branch; | |
c5905afb IM |
385 | } |
386 | ||
706249c2 PZ |
387 | static void __jump_label_update(struct static_key *key, |
388 | struct jump_entry *entry, | |
19483677 AB |
389 | struct jump_entry *stop, |
390 | bool init) | |
706249c2 PZ |
391 | { |
392 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
393 | /* | |
dc1dd184 JP |
394 | * An entry->code of 0 indicates an entry which has been |
395 | * disabled because it was in an init text area. | |
706249c2 | 396 | */ |
19483677 | 397 | if (init || !jump_entry_is_init(entry)) { |
9ae033ac | 398 | if (kernel_text_address(jump_entry_code(entry))) |
dc1dd184 JP |
399 | arch_jump_label_transform(entry, jump_label_type(entry)); |
400 | else | |
af1d830b | 401 | WARN_ONCE(1, "can't patch jump_label at %pS", |
9ae033ac | 402 | (void *)jump_entry_code(entry)); |
dc1dd184 | 403 | } |
706249c2 PZ |
404 | } |
405 | } | |
406 | ||
97ce2c88 | 407 | void __init jump_label_init(void) |
bf5438fc | 408 | { |
bf5438fc JB |
409 | struct jump_entry *iter_start = __start___jump_table; |
410 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 411 | struct static_key *key = NULL; |
bf5438fc JB |
412 | struct jump_entry *iter; |
413 | ||
1f69bf9c JB |
414 | /* |
415 | * Since we are initializing the static_key.enabled field with | |
416 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
417 | * jump_label.h, let's make sure that is safe. There are only two | |
418 | * cases to check since we initialize to 0 or 1. | |
419 | */ | |
420 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
421 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
422 | ||
e3f91083 KH |
423 | if (static_key_initialized) |
424 | return; | |
425 | ||
f2545b2d | 426 | cpus_read_lock(); |
91bad2f8 | 427 | jump_label_lock(); |
d430d3d7 JB |
428 | jump_label_sort_entries(iter_start, iter_stop); |
429 | ||
430 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 431 | struct static_key *iterk; |
37348804 | 432 | |
11276d53 PZ |
433 | /* rewrite NOPs */ |
434 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
435 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
436 | ||
19483677 AB |
437 | if (init_section_contains((void *)jump_entry_code(iter), 1)) |
438 | jump_entry_set_init(iter); | |
439 | ||
7dcfd915 | 440 | iterk = jump_entry_key(iter); |
37348804 | 441 | if (iterk == key) |
d430d3d7 JB |
442 | continue; |
443 | ||
37348804 | 444 | key = iterk; |
3821fd35 | 445 | static_key_set_entries(key, iter); |
bf5438fc | 446 | } |
c4b2c0c5 | 447 | static_key_initialized = true; |
91bad2f8 | 448 | jump_label_unlock(); |
f2545b2d | 449 | cpus_read_unlock(); |
bf5438fc | 450 | } |
bf5438fc JB |
451 | |
452 | #ifdef CONFIG_MODULES | |
453 | ||
11276d53 PZ |
454 | static enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
455 | { | |
456 | struct static_key *key = jump_entry_key(entry); | |
457 | bool type = static_key_type(key); | |
9ae033ac | 458 | bool branch = jump_entry_is_branch(entry); |
11276d53 PZ |
459 | |
460 | /* See the comment in linux/jump_label.h */ | |
461 | return type ^ branch; | |
462 | } | |
463 | ||
c5905afb IM |
464 | struct static_key_mod { |
465 | struct static_key_mod *next; | |
d430d3d7 JB |
466 | struct jump_entry *entries; |
467 | struct module *mod; | |
468 | }; | |
469 | ||
3821fd35 JB |
470 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
471 | { | |
34e12b86 | 472 | WARN_ON_ONCE(!static_key_linked(key)); |
3821fd35 JB |
473 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); |
474 | } | |
475 | ||
476 | /*** | |
477 | * key->type and key->next are the same via union. | |
478 | * This sets key->next and preserves the type bits. | |
479 | * | |
480 | * See additional comments above static_key_set_entries(). | |
481 | */ | |
482 | static void static_key_set_mod(struct static_key *key, | |
483 | struct static_key_mod *mod) | |
484 | { | |
485 | unsigned long type; | |
486 | ||
487 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
488 | type = key->type & JUMP_TYPE_MASK; | |
489 | key->next = mod; | |
490 | key->type |= type; | |
491 | } | |
492 | ||
d430d3d7 JB |
493 | static int __jump_label_mod_text_reserved(void *start, void *end) |
494 | { | |
495 | struct module *mod; | |
496 | ||
bdc9f373 | 497 | preempt_disable(); |
d430d3d7 | 498 | mod = __module_text_address((unsigned long)start); |
bdc9f373 RR |
499 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
500 | preempt_enable(); | |
501 | ||
d430d3d7 JB |
502 | if (!mod) |
503 | return 0; | |
504 | ||
d430d3d7 JB |
505 | |
506 | return __jump_label_text_reserved(mod->jump_entries, | |
507 | mod->jump_entries + mod->num_jump_entries, | |
508 | start, end); | |
509 | } | |
510 | ||
706249c2 | 511 | static void __jump_label_mod_update(struct static_key *key) |
d430d3d7 | 512 | { |
706249c2 | 513 | struct static_key_mod *mod; |
d430d3d7 | 514 | |
3821fd35 JB |
515 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
516 | struct jump_entry *stop; | |
517 | struct module *m; | |
518 | ||
519 | /* | |
520 | * NULL if the static_key is defined in a module | |
521 | * that does not use it | |
522 | */ | |
523 | if (!mod->entries) | |
524 | continue; | |
7cbc5b8d | 525 | |
3821fd35 JB |
526 | m = mod->mod; |
527 | if (!m) | |
528 | stop = __stop___jump_table; | |
529 | else | |
530 | stop = m->jump_entries + m->num_jump_entries; | |
19483677 | 531 | __jump_label_update(key, mod->entries, stop, |
77ac1c02 | 532 | m && m->state == MODULE_STATE_COMING); |
d430d3d7 JB |
533 | } |
534 | } | |
535 | ||
536 | /*** | |
537 | * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() | |
538 | * @mod: module to patch | |
539 | * | |
540 | * Allow for run-time selection of the optimal nops. Before the module | |
541 | * loads patch these with arch_get_jump_label_nop(), which is specified by | |
542 | * the arch specific jump label code. | |
543 | */ | |
544 | void jump_label_apply_nops(struct module *mod) | |
bf5438fc | 545 | { |
d430d3d7 JB |
546 | struct jump_entry *iter_start = mod->jump_entries; |
547 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
548 | struct jump_entry *iter; | |
549 | ||
550 | /* if the module doesn't have jump label entries, just return */ | |
551 | if (iter_start == iter_stop) | |
552 | return; | |
553 | ||
11276d53 PZ |
554 | for (iter = iter_start; iter < iter_stop; iter++) { |
555 | /* Only write NOPs for arch_branch_static(). */ | |
556 | if (jump_label_init_type(iter) == JUMP_LABEL_NOP) | |
557 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
558 | } | |
bf5438fc JB |
559 | } |
560 | ||
d430d3d7 | 561 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 562 | { |
d430d3d7 JB |
563 | struct jump_entry *iter_start = mod->jump_entries; |
564 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
565 | struct jump_entry *iter; | |
c5905afb | 566 | struct static_key *key = NULL; |
3821fd35 | 567 | struct static_key_mod *jlm, *jlm2; |
bf5438fc JB |
568 | |
569 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 570 | if (iter_start == iter_stop) |
bf5438fc JB |
571 | return 0; |
572 | ||
d430d3d7 JB |
573 | jump_label_sort_entries(iter_start, iter_stop); |
574 | ||
575 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 576 | struct static_key *iterk; |
d430d3d7 | 577 | |
19483677 AB |
578 | if (within_module_init(jump_entry_code(iter), mod)) |
579 | jump_entry_set_init(iter); | |
580 | ||
7dcfd915 | 581 | iterk = jump_entry_key(iter); |
c5905afb IM |
582 | if (iterk == key) |
583 | continue; | |
d430d3d7 | 584 | |
c5905afb | 585 | key = iterk; |
9ae033ac | 586 | if (within_module((unsigned long)key, mod)) { |
3821fd35 | 587 | static_key_set_entries(key, iter); |
d430d3d7 | 588 | continue; |
bf5438fc | 589 | } |
c5905afb | 590 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
591 | if (!jlm) |
592 | return -ENOMEM; | |
3821fd35 JB |
593 | if (!static_key_linked(key)) { |
594 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
595 | GFP_KERNEL); | |
596 | if (!jlm2) { | |
597 | kfree(jlm); | |
598 | return -ENOMEM; | |
599 | } | |
600 | preempt_disable(); | |
601 | jlm2->mod = __module_address((unsigned long)key); | |
602 | preempt_enable(); | |
603 | jlm2->entries = static_key_entries(key); | |
604 | jlm2->next = NULL; | |
605 | static_key_set_mod(key, jlm2); | |
606 | static_key_set_linked(key); | |
607 | } | |
d430d3d7 JB |
608 | jlm->mod = mod; |
609 | jlm->entries = iter; | |
3821fd35 JB |
610 | jlm->next = static_key_mod(key); |
611 | static_key_set_mod(key, jlm); | |
612 | static_key_set_linked(key); | |
d430d3d7 | 613 | |
11276d53 PZ |
614 | /* Only update if we've changed from our initial state */ |
615 | if (jump_label_type(iter) != jump_label_init_type(iter)) | |
19483677 | 616 | __jump_label_update(key, iter, iter_stop, true); |
bf5438fc | 617 | } |
d430d3d7 | 618 | |
bf5438fc JB |
619 | return 0; |
620 | } | |
621 | ||
d430d3d7 | 622 | static void jump_label_del_module(struct module *mod) |
bf5438fc | 623 | { |
d430d3d7 JB |
624 | struct jump_entry *iter_start = mod->jump_entries; |
625 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
626 | struct jump_entry *iter; | |
c5905afb IM |
627 | struct static_key *key = NULL; |
628 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 629 | |
d430d3d7 | 630 | for (iter = iter_start; iter < iter_stop; iter++) { |
7dcfd915 | 631 | if (jump_entry_key(iter) == key) |
d430d3d7 JB |
632 | continue; |
633 | ||
7dcfd915 | 634 | key = jump_entry_key(iter); |
d430d3d7 | 635 | |
9ae033ac | 636 | if (within_module((unsigned long)key, mod)) |
d430d3d7 JB |
637 | continue; |
638 | ||
3821fd35 JB |
639 | /* No memory during module load */ |
640 | if (WARN_ON(!static_key_linked(key))) | |
641 | continue; | |
642 | ||
d430d3d7 | 643 | prev = &key->next; |
3821fd35 | 644 | jlm = static_key_mod(key); |
bf5438fc | 645 | |
d430d3d7 JB |
646 | while (jlm && jlm->mod != mod) { |
647 | prev = &jlm->next; | |
648 | jlm = jlm->next; | |
649 | } | |
650 | ||
3821fd35 JB |
651 | /* No memory during module load */ |
652 | if (WARN_ON(!jlm)) | |
653 | continue; | |
654 | ||
655 | if (prev == &key->next) | |
656 | static_key_set_mod(key, jlm->next); | |
657 | else | |
d430d3d7 | 658 | *prev = jlm->next; |
3821fd35 JB |
659 | |
660 | kfree(jlm); | |
661 | ||
662 | jlm = static_key_mod(key); | |
663 | /* if only one etry is left, fold it back into the static_key */ | |
664 | if (jlm->next == NULL) { | |
665 | static_key_set_entries(key, jlm->entries); | |
666 | static_key_clear_linked(key); | |
d430d3d7 | 667 | kfree(jlm); |
bf5438fc JB |
668 | } |
669 | } | |
670 | } | |
671 | ||
672 | static int | |
673 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
674 | void *data) | |
675 | { | |
676 | struct module *mod = data; | |
677 | int ret = 0; | |
678 | ||
f2545b2d TG |
679 | cpus_read_lock(); |
680 | jump_label_lock(); | |
681 | ||
bf5438fc JB |
682 | switch (val) { |
683 | case MODULE_STATE_COMING: | |
d430d3d7 | 684 | ret = jump_label_add_module(mod); |
3821fd35 | 685 | if (ret) { |
da260fe1 | 686 | WARN(1, "Failed to allocate memory: jump_label may not work properly.\n"); |
d430d3d7 | 687 | jump_label_del_module(mod); |
3821fd35 | 688 | } |
bf5438fc JB |
689 | break; |
690 | case MODULE_STATE_GOING: | |
d430d3d7 | 691 | jump_label_del_module(mod); |
bf5438fc JB |
692 | break; |
693 | } | |
bf5438fc | 694 | |
f2545b2d TG |
695 | jump_label_unlock(); |
696 | cpus_read_unlock(); | |
697 | ||
d430d3d7 | 698 | return notifier_from_errno(ret); |
bf5438fc JB |
699 | } |
700 | ||
885885f6 | 701 | static struct notifier_block jump_label_module_nb = { |
bf5438fc | 702 | .notifier_call = jump_label_module_notify, |
d430d3d7 | 703 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
704 | }; |
705 | ||
d430d3d7 | 706 | static __init int jump_label_init_module(void) |
bf5438fc JB |
707 | { |
708 | return register_module_notifier(&jump_label_module_nb); | |
709 | } | |
d430d3d7 | 710 | early_initcall(jump_label_init_module); |
bf5438fc JB |
711 | |
712 | #endif /* CONFIG_MODULES */ | |
713 | ||
d430d3d7 JB |
714 | /*** |
715 | * jump_label_text_reserved - check if addr range is reserved | |
716 | * @start: start text addr | |
717 | * @end: end text addr | |
718 | * | |
719 | * checks if the text addr located between @start and @end | |
720 | * overlaps with any of the jump label patch addresses. Code | |
721 | * that wants to modify kernel text should first verify that | |
722 | * it does not overlap with any of the jump label addresses. | |
723 | * Caller must hold jump_label_mutex. | |
724 | * | |
725 | * returns 1 if there is an overlap, 0 otherwise | |
726 | */ | |
727 | int jump_label_text_reserved(void *start, void *end) | |
728 | { | |
729 | int ret = __jump_label_text_reserved(__start___jump_table, | |
730 | __stop___jump_table, start, end); | |
731 | ||
732 | if (ret) | |
733 | return ret; | |
734 | ||
735 | #ifdef CONFIG_MODULES | |
736 | ret = __jump_label_mod_text_reserved(start, end); | |
737 | #endif | |
738 | return ret; | |
739 | } | |
740 | ||
706249c2 | 741 | static void jump_label_update(struct static_key *key) |
d430d3d7 | 742 | { |
c5905afb | 743 | struct jump_entry *stop = __stop___jump_table; |
3821fd35 | 744 | struct jump_entry *entry; |
d430d3d7 | 745 | #ifdef CONFIG_MODULES |
bed831f9 | 746 | struct module *mod; |
140fe3b1 | 747 | |
3821fd35 JB |
748 | if (static_key_linked(key)) { |
749 | __jump_label_mod_update(key); | |
750 | return; | |
751 | } | |
140fe3b1 | 752 | |
bed831f9 PZ |
753 | preempt_disable(); |
754 | mod = __module_address((unsigned long)key); | |
140fe3b1 XG |
755 | if (mod) |
756 | stop = mod->jump_entries + mod->num_jump_entries; | |
bed831f9 | 757 | preempt_enable(); |
d430d3d7 | 758 | #endif |
3821fd35 | 759 | entry = static_key_entries(key); |
140fe3b1 XG |
760 | /* if there are no users, entry can be NULL */ |
761 | if (entry) | |
19483677 AB |
762 | __jump_label_update(key, entry, stop, |
763 | system_state < SYSTEM_RUNNING); | |
d430d3d7 JB |
764 | } |
765 | ||
1987c947 PZ |
766 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
767 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
768 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
769 | ||
770 | static __init int jump_label_test(void) | |
771 | { | |
772 | int i; | |
773 | ||
774 | for (i = 0; i < 2; i++) { | |
775 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
776 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
777 | ||
778 | WARN_ON(!static_branch_likely(&sk_true)); | |
779 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
780 | WARN_ON(static_branch_likely(&sk_false)); | |
781 | WARN_ON(static_branch_unlikely(&sk_false)); | |
782 | ||
783 | static_branch_disable(&sk_true); | |
784 | static_branch_enable(&sk_false); | |
785 | ||
786 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
787 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
788 | ||
789 | WARN_ON(static_branch_likely(&sk_true)); | |
790 | WARN_ON(static_branch_unlikely(&sk_true)); | |
791 | WARN_ON(!static_branch_likely(&sk_false)); | |
792 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
793 | ||
794 | static_branch_enable(&sk_true); | |
795 | static_branch_disable(&sk_false); | |
796 | } | |
797 | ||
798 | return 0; | |
799 | } | |
92ee46ef | 800 | early_initcall(jump_label_test); |
1987c947 | 801 | #endif /* STATIC_KEYS_SELFTEST */ |