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