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Commit | Line | Data |
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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> |
bf5438fc JB |
19 | |
20 | #ifdef HAVE_JUMP_LABEL | |
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 | ||
40 | if (jea->key < jeb->key) | |
41 | return -1; | |
42 | ||
43 | if (jea->key > jeb->key) | |
44 | return 1; | |
45 | ||
46 | return 0; | |
47 | } | |
48 | ||
49 | static void | |
d430d3d7 | 50 | jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) |
bf5438fc JB |
51 | { |
52 | unsigned long size; | |
53 | ||
54 | size = (((unsigned long)stop - (unsigned long)start) | |
55 | / sizeof(struct jump_entry)); | |
56 | sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL); | |
57 | } | |
58 | ||
706249c2 | 59 | static void jump_label_update(struct static_key *key); |
a1efb01f | 60 | |
1f69bf9c JB |
61 | /* |
62 | * There are similar definitions for the !HAVE_JUMP_LABEL case in jump_label.h. | |
63 | * The use of 'atomic_read()' requires atomic.h and its problematic for some | |
64 | * kernel headers such as kernel.h and others. Since static_key_count() is not | |
65 | * used in the branch statements as it is for the !HAVE_JUMP_LABEL case its ok | |
66 | * to have it be a function here. Similarly, for 'static_key_enable()' and | |
67 | * 'static_key_disable()', which require bug.h. This should allow jump_label.h | |
68 | * to be included from most/all places for HAVE_JUMP_LABEL. | |
69 | */ | |
70 | int static_key_count(struct static_key *key) | |
71 | { | |
72 | /* | |
73 | * -1 means the first static_key_slow_inc() is in progress. | |
74 | * static_key_enabled() must return true, so return 1 here. | |
75 | */ | |
76 | int n = atomic_read(&key->enabled); | |
77 | ||
78 | return n >= 0 ? n : 1; | |
79 | } | |
80 | EXPORT_SYMBOL_GPL(static_key_count); | |
81 | ||
c5905afb | 82 | void static_key_slow_inc(struct static_key *key) |
bf5438fc | 83 | { |
4c5ea0a9 PB |
84 | int v, v1; |
85 | ||
b70cecf4 | 86 | cpus_read_lock(); |
c4b2c0c5 | 87 | STATIC_KEY_CHECK_USE(); |
4c5ea0a9 PB |
88 | |
89 | /* | |
90 | * Careful if we get concurrent static_key_slow_inc() calls; | |
91 | * later calls must wait for the first one to _finish_ the | |
92 | * jump_label_update() process. At the same time, however, | |
93 | * the jump_label_update() call below wants to see | |
94 | * static_key_enabled(&key) for jumps to be updated properly. | |
95 | * | |
96 | * So give a special meaning to negative key->enabled: it sends | |
97 | * static_key_slow_inc() down the slow path, and it is non-zero | |
98 | * so it counts as "enabled" in jump_label_update(). Note that | |
99 | * atomic_inc_unless_negative() checks >= 0, so roll our own. | |
100 | */ | |
101 | for (v = atomic_read(&key->enabled); v > 0; v = v1) { | |
102 | v1 = atomic_cmpxchg(&key->enabled, v, v + 1); | |
b70cecf4 MZ |
103 | if (likely(v1 == v)) { |
104 | cpus_read_unlock(); | |
4c5ea0a9 | 105 | return; |
b70cecf4 | 106 | } |
4c5ea0a9 | 107 | } |
bf5438fc | 108 | |
d430d3d7 | 109 | jump_label_lock(); |
4c5ea0a9 PB |
110 | if (atomic_read(&key->enabled) == 0) { |
111 | atomic_set(&key->enabled, -1); | |
706249c2 | 112 | jump_label_update(key); |
d0646a6f PZ |
113 | /* |
114 | * Ensure that if the above cmpxchg loop observes our positive | |
115 | * value, it must also observe all the text changes. | |
116 | */ | |
117 | atomic_set_release(&key->enabled, 1); | |
4c5ea0a9 PB |
118 | } else { |
119 | atomic_inc(&key->enabled); | |
120 | } | |
d430d3d7 | 121 | jump_label_unlock(); |
f2545b2d | 122 | cpus_read_unlock(); |
bf5438fc | 123 | } |
c5905afb | 124 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
bf5438fc | 125 | |
1dbb6704 PB |
126 | void static_key_enable(struct static_key *key) |
127 | { | |
128 | STATIC_KEY_CHECK_USE(); | |
129 | if (atomic_read(&key->enabled) > 0) { | |
130 | WARN_ON_ONCE(atomic_read(&key->enabled) != 1); | |
131 | return; | |
132 | } | |
133 | ||
134 | cpus_read_lock(); | |
135 | jump_label_lock(); | |
136 | if (atomic_read(&key->enabled) == 0) { | |
137 | atomic_set(&key->enabled, -1); | |
138 | jump_label_update(key); | |
d0646a6f PZ |
139 | /* |
140 | * See static_key_slow_inc(). | |
141 | */ | |
142 | atomic_set_release(&key->enabled, 1); | |
1dbb6704 PB |
143 | } |
144 | jump_label_unlock(); | |
145 | cpus_read_unlock(); | |
146 | } | |
147 | EXPORT_SYMBOL_GPL(static_key_enable); | |
148 | ||
149 | void static_key_disable(struct static_key *key) | |
150 | { | |
151 | STATIC_KEY_CHECK_USE(); | |
152 | if (atomic_read(&key->enabled) != 1) { | |
153 | WARN_ON_ONCE(atomic_read(&key->enabled) != 0); | |
154 | return; | |
155 | } | |
156 | ||
157 | cpus_read_lock(); | |
158 | jump_label_lock(); | |
159 | if (atomic_cmpxchg(&key->enabled, 1, 0)) | |
160 | jump_label_update(key); | |
161 | jump_label_unlock(); | |
162 | cpus_read_unlock(); | |
163 | } | |
164 | EXPORT_SYMBOL_GPL(static_key_disable); | |
165 | ||
c5905afb | 166 | static void __static_key_slow_dec(struct static_key *key, |
b2029520 | 167 | unsigned long rate_limit, struct delayed_work *work) |
bf5438fc | 168 | { |
f2545b2d | 169 | cpus_read_lock(); |
4c5ea0a9 PB |
170 | /* |
171 | * The negative count check is valid even when a negative | |
172 | * key->enabled is in use by static_key_slow_inc(); a | |
173 | * __static_key_slow_dec() before the first static_key_slow_inc() | |
174 | * returns is unbalanced, because all other static_key_slow_inc() | |
175 | * instances block while the update is in progress. | |
176 | */ | |
fadf0464 JB |
177 | if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { |
178 | WARN(atomic_read(&key->enabled) < 0, | |
179 | "jump label: negative count!\n"); | |
f2545b2d | 180 | cpus_read_unlock(); |
d430d3d7 | 181 | return; |
fadf0464 | 182 | } |
bf5438fc | 183 | |
b2029520 GN |
184 | if (rate_limit) { |
185 | atomic_inc(&key->enabled); | |
186 | schedule_delayed_work(work, rate_limit); | |
c5905afb | 187 | } else { |
706249c2 | 188 | jump_label_update(key); |
c5905afb | 189 | } |
91bad2f8 | 190 | jump_label_unlock(); |
f2545b2d | 191 | cpus_read_unlock(); |
bf5438fc JB |
192 | } |
193 | ||
b2029520 GN |
194 | static void jump_label_update_timeout(struct work_struct *work) |
195 | { | |
c5905afb IM |
196 | struct static_key_deferred *key = |
197 | container_of(work, struct static_key_deferred, work.work); | |
198 | __static_key_slow_dec(&key->key, 0, NULL); | |
b2029520 GN |
199 | } |
200 | ||
c5905afb | 201 | void static_key_slow_dec(struct static_key *key) |
b2029520 | 202 | { |
c4b2c0c5 | 203 | STATIC_KEY_CHECK_USE(); |
c5905afb | 204 | __static_key_slow_dec(key, 0, NULL); |
b2029520 | 205 | } |
c5905afb | 206 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
b2029520 | 207 | |
c5905afb | 208 | void static_key_slow_dec_deferred(struct static_key_deferred *key) |
b2029520 | 209 | { |
c4b2c0c5 | 210 | STATIC_KEY_CHECK_USE(); |
c5905afb | 211 | __static_key_slow_dec(&key->key, key->timeout, &key->work); |
b2029520 | 212 | } |
c5905afb | 213 | EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); |
b2029520 | 214 | |
b6416e61 DM |
215 | void static_key_deferred_flush(struct static_key_deferred *key) |
216 | { | |
217 | STATIC_KEY_CHECK_USE(); | |
218 | flush_delayed_work(&key->work); | |
219 | } | |
220 | EXPORT_SYMBOL_GPL(static_key_deferred_flush); | |
221 | ||
c5905afb | 222 | void jump_label_rate_limit(struct static_key_deferred *key, |
b2029520 GN |
223 | unsigned long rl) |
224 | { | |
c4b2c0c5 | 225 | STATIC_KEY_CHECK_USE(); |
b2029520 GN |
226 | key->timeout = rl; |
227 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
228 | } | |
a181dc14 | 229 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
b2029520 | 230 | |
4c3ef6d7 JB |
231 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
232 | { | |
233 | if (entry->code <= (unsigned long)end && | |
234 | entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start) | |
235 | return 1; | |
236 | ||
237 | return 0; | |
238 | } | |
239 | ||
d430d3d7 JB |
240 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
241 | struct jump_entry *iter_stop, void *start, void *end) | |
4c3ef6d7 | 242 | { |
4c3ef6d7 | 243 | struct jump_entry *iter; |
4c3ef6d7 | 244 | |
4c3ef6d7 JB |
245 | iter = iter_start; |
246 | while (iter < iter_stop) { | |
d430d3d7 JB |
247 | if (addr_conflict(iter, start, end)) |
248 | return 1; | |
4c3ef6d7 JB |
249 | iter++; |
250 | } | |
251 | ||
d430d3d7 JB |
252 | return 0; |
253 | } | |
254 | ||
706249c2 | 255 | /* |
20284aa7 JF |
256 | * Update code which is definitely not currently executing. |
257 | * Architectures which need heavyweight synchronization to modify | |
258 | * running code can override this to make the non-live update case | |
259 | * cheaper. | |
260 | */ | |
9cdbe1cb | 261 | void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, |
20284aa7 JF |
262 | enum jump_label_type type) |
263 | { | |
706249c2 | 264 | arch_jump_label_transform(entry, type); |
20284aa7 JF |
265 | } |
266 | ||
706249c2 | 267 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
d430d3d7 | 268 | { |
3821fd35 JB |
269 | WARN_ON_ONCE(key->type & JUMP_TYPE_LINKED); |
270 | return (struct jump_entry *)(key->type & ~JUMP_TYPE_MASK); | |
4c3ef6d7 JB |
271 | } |
272 | ||
706249c2 | 273 | static inline bool static_key_type(struct static_key *key) |
c5905afb | 274 | { |
3821fd35 JB |
275 | return key->type & JUMP_TYPE_TRUE; |
276 | } | |
277 | ||
278 | static inline bool static_key_linked(struct static_key *key) | |
279 | { | |
280 | return key->type & JUMP_TYPE_LINKED; | |
281 | } | |
282 | ||
283 | static inline void static_key_clear_linked(struct static_key *key) | |
284 | { | |
285 | key->type &= ~JUMP_TYPE_LINKED; | |
286 | } | |
287 | ||
288 | static inline void static_key_set_linked(struct static_key *key) | |
289 | { | |
290 | key->type |= JUMP_TYPE_LINKED; | |
a1efb01f | 291 | } |
c5905afb | 292 | |
7dcfd915 PZ |
293 | static inline struct static_key *jump_entry_key(struct jump_entry *entry) |
294 | { | |
11276d53 PZ |
295 | return (struct static_key *)((unsigned long)entry->key & ~1UL); |
296 | } | |
297 | ||
298 | static bool jump_entry_branch(struct jump_entry *entry) | |
299 | { | |
300 | return (unsigned long)entry->key & 1UL; | |
7dcfd915 PZ |
301 | } |
302 | ||
3821fd35 JB |
303 | /*** |
304 | * A 'struct static_key' uses a union such that it either points directly | |
305 | * to a table of 'struct jump_entry' or to a linked list of modules which in | |
306 | * turn point to 'struct jump_entry' tables. | |
307 | * | |
308 | * The two lower bits of the pointer are used to keep track of which pointer | |
309 | * type is in use and to store the initial branch direction, we use an access | |
310 | * function which preserves these bits. | |
311 | */ | |
312 | static void static_key_set_entries(struct static_key *key, | |
313 | struct jump_entry *entries) | |
314 | { | |
315 | unsigned long type; | |
316 | ||
317 | WARN_ON_ONCE((unsigned long)entries & JUMP_TYPE_MASK); | |
318 | type = key->type & JUMP_TYPE_MASK; | |
319 | key->entries = entries; | |
320 | key->type |= type; | |
321 | } | |
322 | ||
706249c2 | 323 | static enum jump_label_type jump_label_type(struct jump_entry *entry) |
a1efb01f | 324 | { |
706249c2 | 325 | struct static_key *key = jump_entry_key(entry); |
a1efb01f | 326 | bool enabled = static_key_enabled(key); |
11276d53 | 327 | bool branch = jump_entry_branch(entry); |
c5905afb | 328 | |
11276d53 PZ |
329 | /* See the comment in linux/jump_label.h */ |
330 | return enabled ^ branch; | |
c5905afb IM |
331 | } |
332 | ||
706249c2 PZ |
333 | static void __jump_label_update(struct static_key *key, |
334 | struct jump_entry *entry, | |
335 | struct jump_entry *stop) | |
336 | { | |
337 | for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) { | |
338 | /* | |
339 | * entry->code set to 0 invalidates module init text sections | |
340 | * kernel_text_address() verifies we are not in core kernel | |
341 | * init code, see jump_label_invalidate_module_init(). | |
342 | */ | |
343 | if (entry->code && kernel_text_address(entry->code)) | |
344 | arch_jump_label_transform(entry, jump_label_type(entry)); | |
345 | } | |
346 | } | |
347 | ||
97ce2c88 | 348 | void __init jump_label_init(void) |
bf5438fc | 349 | { |
bf5438fc JB |
350 | struct jump_entry *iter_start = __start___jump_table; |
351 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 352 | struct static_key *key = NULL; |
bf5438fc JB |
353 | struct jump_entry *iter; |
354 | ||
1f69bf9c JB |
355 | /* |
356 | * Since we are initializing the static_key.enabled field with | |
357 | * with the 'raw' int values (to avoid pulling in atomic.h) in | |
358 | * jump_label.h, let's make sure that is safe. There are only two | |
359 | * cases to check since we initialize to 0 or 1. | |
360 | */ | |
361 | BUILD_BUG_ON((int)ATOMIC_INIT(0) != 0); | |
362 | BUILD_BUG_ON((int)ATOMIC_INIT(1) != 1); | |
363 | ||
e3f91083 KH |
364 | if (static_key_initialized) |
365 | return; | |
366 | ||
f2545b2d | 367 | cpus_read_lock(); |
91bad2f8 | 368 | jump_label_lock(); |
d430d3d7 JB |
369 | jump_label_sort_entries(iter_start, iter_stop); |
370 | ||
371 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 372 | struct static_key *iterk; |
37348804 | 373 | |
11276d53 PZ |
374 | /* rewrite NOPs */ |
375 | if (jump_label_type(iter) == JUMP_LABEL_NOP) | |
376 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
377 | ||
7dcfd915 | 378 | iterk = jump_entry_key(iter); |
37348804 | 379 | if (iterk == key) |
d430d3d7 JB |
380 | continue; |
381 | ||
37348804 | 382 | key = iterk; |
3821fd35 | 383 | static_key_set_entries(key, iter); |
bf5438fc | 384 | } |
c4b2c0c5 | 385 | static_key_initialized = true; |
91bad2f8 | 386 | jump_label_unlock(); |
f2545b2d | 387 | cpus_read_unlock(); |
bf5438fc | 388 | } |
bf5438fc JB |
389 | |
390 | #ifdef CONFIG_MODULES | |
391 | ||
11276d53 PZ |
392 | static enum jump_label_type jump_label_init_type(struct jump_entry *entry) |
393 | { | |
394 | struct static_key *key = jump_entry_key(entry); | |
395 | bool type = static_key_type(key); | |
396 | bool branch = jump_entry_branch(entry); | |
397 | ||
398 | /* See the comment in linux/jump_label.h */ | |
399 | return type ^ branch; | |
400 | } | |
401 | ||
c5905afb IM |
402 | struct static_key_mod { |
403 | struct static_key_mod *next; | |
d430d3d7 JB |
404 | struct jump_entry *entries; |
405 | struct module *mod; | |
406 | }; | |
407 | ||
3821fd35 JB |
408 | static inline struct static_key_mod *static_key_mod(struct static_key *key) |
409 | { | |
410 | WARN_ON_ONCE(!(key->type & JUMP_TYPE_LINKED)); | |
411 | return (struct static_key_mod *)(key->type & ~JUMP_TYPE_MASK); | |
412 | } | |
413 | ||
414 | /*** | |
415 | * key->type and key->next are the same via union. | |
416 | * This sets key->next and preserves the type bits. | |
417 | * | |
418 | * See additional comments above static_key_set_entries(). | |
419 | */ | |
420 | static void static_key_set_mod(struct static_key *key, | |
421 | struct static_key_mod *mod) | |
422 | { | |
423 | unsigned long type; | |
424 | ||
425 | WARN_ON_ONCE((unsigned long)mod & JUMP_TYPE_MASK); | |
426 | type = key->type & JUMP_TYPE_MASK; | |
427 | key->next = mod; | |
428 | key->type |= type; | |
429 | } | |
430 | ||
d430d3d7 JB |
431 | static int __jump_label_mod_text_reserved(void *start, void *end) |
432 | { | |
433 | struct module *mod; | |
434 | ||
bdc9f373 | 435 | preempt_disable(); |
d430d3d7 | 436 | mod = __module_text_address((unsigned long)start); |
bdc9f373 RR |
437 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); |
438 | preempt_enable(); | |
439 | ||
d430d3d7 JB |
440 | if (!mod) |
441 | return 0; | |
442 | ||
d430d3d7 JB |
443 | |
444 | return __jump_label_text_reserved(mod->jump_entries, | |
445 | mod->jump_entries + mod->num_jump_entries, | |
446 | start, end); | |
447 | } | |
448 | ||
706249c2 | 449 | static void __jump_label_mod_update(struct static_key *key) |
d430d3d7 | 450 | { |
706249c2 | 451 | struct static_key_mod *mod; |
d430d3d7 | 452 | |
3821fd35 JB |
453 | for (mod = static_key_mod(key); mod; mod = mod->next) { |
454 | struct jump_entry *stop; | |
455 | struct module *m; | |
456 | ||
457 | /* | |
458 | * NULL if the static_key is defined in a module | |
459 | * that does not use it | |
460 | */ | |
461 | if (!mod->entries) | |
462 | continue; | |
7cbc5b8d | 463 | |
3821fd35 JB |
464 | m = mod->mod; |
465 | if (!m) | |
466 | stop = __stop___jump_table; | |
467 | else | |
468 | stop = m->jump_entries + m->num_jump_entries; | |
469 | __jump_label_update(key, mod->entries, stop); | |
d430d3d7 JB |
470 | } |
471 | } | |
472 | ||
473 | /*** | |
474 | * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() | |
475 | * @mod: module to patch | |
476 | * | |
477 | * Allow for run-time selection of the optimal nops. Before the module | |
478 | * loads patch these with arch_get_jump_label_nop(), which is specified by | |
479 | * the arch specific jump label code. | |
480 | */ | |
481 | void jump_label_apply_nops(struct module *mod) | |
bf5438fc | 482 | { |
d430d3d7 JB |
483 | struct jump_entry *iter_start = mod->jump_entries; |
484 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
485 | struct jump_entry *iter; | |
486 | ||
487 | /* if the module doesn't have jump label entries, just return */ | |
488 | if (iter_start == iter_stop) | |
489 | return; | |
490 | ||
11276d53 PZ |
491 | for (iter = iter_start; iter < iter_stop; iter++) { |
492 | /* Only write NOPs for arch_branch_static(). */ | |
493 | if (jump_label_init_type(iter) == JUMP_LABEL_NOP) | |
494 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); | |
495 | } | |
bf5438fc JB |
496 | } |
497 | ||
d430d3d7 | 498 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 499 | { |
d430d3d7 JB |
500 | struct jump_entry *iter_start = mod->jump_entries; |
501 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
502 | struct jump_entry *iter; | |
c5905afb | 503 | struct static_key *key = NULL; |
3821fd35 | 504 | struct static_key_mod *jlm, *jlm2; |
bf5438fc JB |
505 | |
506 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 507 | if (iter_start == iter_stop) |
bf5438fc JB |
508 | return 0; |
509 | ||
d430d3d7 JB |
510 | jump_label_sort_entries(iter_start, iter_stop); |
511 | ||
512 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 513 | struct static_key *iterk; |
d430d3d7 | 514 | |
7dcfd915 | 515 | iterk = jump_entry_key(iter); |
c5905afb IM |
516 | if (iterk == key) |
517 | continue; | |
d430d3d7 | 518 | |
c5905afb | 519 | key = iterk; |
bed831f9 | 520 | if (within_module(iter->key, mod)) { |
3821fd35 | 521 | static_key_set_entries(key, iter); |
d430d3d7 | 522 | continue; |
bf5438fc | 523 | } |
c5905afb | 524 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
525 | if (!jlm) |
526 | return -ENOMEM; | |
3821fd35 JB |
527 | if (!static_key_linked(key)) { |
528 | jlm2 = kzalloc(sizeof(struct static_key_mod), | |
529 | GFP_KERNEL); | |
530 | if (!jlm2) { | |
531 | kfree(jlm); | |
532 | return -ENOMEM; | |
533 | } | |
534 | preempt_disable(); | |
535 | jlm2->mod = __module_address((unsigned long)key); | |
536 | preempt_enable(); | |
537 | jlm2->entries = static_key_entries(key); | |
538 | jlm2->next = NULL; | |
539 | static_key_set_mod(key, jlm2); | |
540 | static_key_set_linked(key); | |
541 | } | |
d430d3d7 JB |
542 | jlm->mod = mod; |
543 | jlm->entries = iter; | |
3821fd35 JB |
544 | jlm->next = static_key_mod(key); |
545 | static_key_set_mod(key, jlm); | |
546 | static_key_set_linked(key); | |
d430d3d7 | 547 | |
11276d53 PZ |
548 | /* Only update if we've changed from our initial state */ |
549 | if (jump_label_type(iter) != jump_label_init_type(iter)) | |
706249c2 | 550 | __jump_label_update(key, iter, iter_stop); |
bf5438fc | 551 | } |
d430d3d7 | 552 | |
bf5438fc JB |
553 | return 0; |
554 | } | |
555 | ||
d430d3d7 | 556 | static void jump_label_del_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 IM |
561 | struct static_key *key = NULL; |
562 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 563 | |
d430d3d7 | 564 | for (iter = iter_start; iter < iter_stop; iter++) { |
7dcfd915 | 565 | if (jump_entry_key(iter) == key) |
d430d3d7 JB |
566 | continue; |
567 | ||
7dcfd915 | 568 | key = jump_entry_key(iter); |
d430d3d7 | 569 | |
bed831f9 | 570 | if (within_module(iter->key, mod)) |
d430d3d7 JB |
571 | continue; |
572 | ||
3821fd35 JB |
573 | /* No memory during module load */ |
574 | if (WARN_ON(!static_key_linked(key))) | |
575 | continue; | |
576 | ||
d430d3d7 | 577 | prev = &key->next; |
3821fd35 | 578 | jlm = static_key_mod(key); |
bf5438fc | 579 | |
d430d3d7 JB |
580 | while (jlm && jlm->mod != mod) { |
581 | prev = &jlm->next; | |
582 | jlm = jlm->next; | |
583 | } | |
584 | ||
3821fd35 JB |
585 | /* No memory during module load */ |
586 | if (WARN_ON(!jlm)) | |
587 | continue; | |
588 | ||
589 | if (prev == &key->next) | |
590 | static_key_set_mod(key, jlm->next); | |
591 | else | |
d430d3d7 | 592 | *prev = jlm->next; |
3821fd35 JB |
593 | |
594 | kfree(jlm); | |
595 | ||
596 | jlm = static_key_mod(key); | |
597 | /* if only one etry is left, fold it back into the static_key */ | |
598 | if (jlm->next == NULL) { | |
599 | static_key_set_entries(key, jlm->entries); | |
600 | static_key_clear_linked(key); | |
d430d3d7 | 601 | kfree(jlm); |
bf5438fc JB |
602 | } |
603 | } | |
604 | } | |
605 | ||
d430d3d7 | 606 | static void jump_label_invalidate_module_init(struct module *mod) |
b842f8fa | 607 | { |
d430d3d7 JB |
608 | struct jump_entry *iter_start = mod->jump_entries; |
609 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
b842f8fa | 610 | struct jump_entry *iter; |
b842f8fa | 611 | |
d430d3d7 JB |
612 | for (iter = iter_start; iter < iter_stop; iter++) { |
613 | if (within_module_init(iter->code, mod)) | |
614 | iter->code = 0; | |
b842f8fa JB |
615 | } |
616 | } | |
617 | ||
bf5438fc JB |
618 | static int |
619 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
620 | void *data) | |
621 | { | |
622 | struct module *mod = data; | |
623 | int ret = 0; | |
624 | ||
f2545b2d TG |
625 | cpus_read_lock(); |
626 | jump_label_lock(); | |
627 | ||
bf5438fc JB |
628 | switch (val) { |
629 | case MODULE_STATE_COMING: | |
d430d3d7 | 630 | ret = jump_label_add_module(mod); |
3821fd35 JB |
631 | if (ret) { |
632 | WARN(1, "Failed to allocatote memory: jump_label may not work properly.\n"); | |
d430d3d7 | 633 | jump_label_del_module(mod); |
3821fd35 | 634 | } |
bf5438fc JB |
635 | break; |
636 | case MODULE_STATE_GOING: | |
d430d3d7 | 637 | jump_label_del_module(mod); |
bf5438fc | 638 | break; |
b842f8fa | 639 | case MODULE_STATE_LIVE: |
d430d3d7 | 640 | jump_label_invalidate_module_init(mod); |
b842f8fa | 641 | break; |
bf5438fc | 642 | } |
bf5438fc | 643 | |
f2545b2d TG |
644 | jump_label_unlock(); |
645 | cpus_read_unlock(); | |
646 | ||
d430d3d7 | 647 | return notifier_from_errno(ret); |
bf5438fc JB |
648 | } |
649 | ||
885885f6 | 650 | static struct notifier_block jump_label_module_nb = { |
bf5438fc | 651 | .notifier_call = jump_label_module_notify, |
d430d3d7 | 652 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
653 | }; |
654 | ||
d430d3d7 | 655 | static __init int jump_label_init_module(void) |
bf5438fc JB |
656 | { |
657 | return register_module_notifier(&jump_label_module_nb); | |
658 | } | |
d430d3d7 | 659 | early_initcall(jump_label_init_module); |
bf5438fc JB |
660 | |
661 | #endif /* CONFIG_MODULES */ | |
662 | ||
d430d3d7 JB |
663 | /*** |
664 | * jump_label_text_reserved - check if addr range is reserved | |
665 | * @start: start text addr | |
666 | * @end: end text addr | |
667 | * | |
668 | * checks if the text addr located between @start and @end | |
669 | * overlaps with any of the jump label patch addresses. Code | |
670 | * that wants to modify kernel text should first verify that | |
671 | * it does not overlap with any of the jump label addresses. | |
672 | * Caller must hold jump_label_mutex. | |
673 | * | |
674 | * returns 1 if there is an overlap, 0 otherwise | |
675 | */ | |
676 | int jump_label_text_reserved(void *start, void *end) | |
677 | { | |
678 | int ret = __jump_label_text_reserved(__start___jump_table, | |
679 | __stop___jump_table, start, end); | |
680 | ||
681 | if (ret) | |
682 | return ret; | |
683 | ||
684 | #ifdef CONFIG_MODULES | |
685 | ret = __jump_label_mod_text_reserved(start, end); | |
686 | #endif | |
687 | return ret; | |
688 | } | |
689 | ||
706249c2 | 690 | static void jump_label_update(struct static_key *key) |
d430d3d7 | 691 | { |
c5905afb | 692 | struct jump_entry *stop = __stop___jump_table; |
3821fd35 | 693 | struct jump_entry *entry; |
d430d3d7 | 694 | #ifdef CONFIG_MODULES |
bed831f9 | 695 | struct module *mod; |
140fe3b1 | 696 | |
3821fd35 JB |
697 | if (static_key_linked(key)) { |
698 | __jump_label_mod_update(key); | |
699 | return; | |
700 | } | |
140fe3b1 | 701 | |
bed831f9 PZ |
702 | preempt_disable(); |
703 | mod = __module_address((unsigned long)key); | |
140fe3b1 XG |
704 | if (mod) |
705 | stop = mod->jump_entries + mod->num_jump_entries; | |
bed831f9 | 706 | preempt_enable(); |
d430d3d7 | 707 | #endif |
3821fd35 | 708 | entry = static_key_entries(key); |
140fe3b1 XG |
709 | /* if there are no users, entry can be NULL */ |
710 | if (entry) | |
706249c2 | 711 | __jump_label_update(key, entry, stop); |
d430d3d7 JB |
712 | } |
713 | ||
1987c947 PZ |
714 | #ifdef CONFIG_STATIC_KEYS_SELFTEST |
715 | static DEFINE_STATIC_KEY_TRUE(sk_true); | |
716 | static DEFINE_STATIC_KEY_FALSE(sk_false); | |
717 | ||
718 | static __init int jump_label_test(void) | |
719 | { | |
720 | int i; | |
721 | ||
722 | for (i = 0; i < 2; i++) { | |
723 | WARN_ON(static_key_enabled(&sk_true.key) != true); | |
724 | WARN_ON(static_key_enabled(&sk_false.key) != false); | |
725 | ||
726 | WARN_ON(!static_branch_likely(&sk_true)); | |
727 | WARN_ON(!static_branch_unlikely(&sk_true)); | |
728 | WARN_ON(static_branch_likely(&sk_false)); | |
729 | WARN_ON(static_branch_unlikely(&sk_false)); | |
730 | ||
731 | static_branch_disable(&sk_true); | |
732 | static_branch_enable(&sk_false); | |
733 | ||
734 | WARN_ON(static_key_enabled(&sk_true.key) == true); | |
735 | WARN_ON(static_key_enabled(&sk_false.key) == false); | |
736 | ||
737 | WARN_ON(static_branch_likely(&sk_true)); | |
738 | WARN_ON(static_branch_unlikely(&sk_true)); | |
739 | WARN_ON(!static_branch_likely(&sk_false)); | |
740 | WARN_ON(!static_branch_unlikely(&sk_false)); | |
741 | ||
742 | static_branch_enable(&sk_true); | |
743 | static_branch_disable(&sk_false); | |
744 | } | |
745 | ||
746 | return 0; | |
747 | } | |
748 | late_initcall(jump_label_test); | |
749 | #endif /* STATIC_KEYS_SELFTEST */ | |
750 | ||
751 | #endif /* HAVE_JUMP_LABEL */ |