Commit | Line | Data |
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bf5438fc JB |
1 | /* |
2 | * jump label support | |
3 | * | |
4 | * Copyright (C) 2009 Jason Baron <jbaron@redhat.com> | |
d430d3d7 | 5 | * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com> |
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> |
bf5438fc JB |
17 | |
18 | #ifdef HAVE_JUMP_LABEL | |
19 | ||
bf5438fc JB |
20 | /* mutex to protect coming/going of the the jump_label table */ |
21 | static DEFINE_MUTEX(jump_label_mutex); | |
22 | ||
91bad2f8 JB |
23 | void jump_label_lock(void) |
24 | { | |
25 | mutex_lock(&jump_label_mutex); | |
26 | } | |
27 | ||
28 | void jump_label_unlock(void) | |
29 | { | |
30 | mutex_unlock(&jump_label_mutex); | |
31 | } | |
32 | ||
bf5438fc JB |
33 | static int jump_label_cmp(const void *a, const void *b) |
34 | { | |
35 | const struct jump_entry *jea = a; | |
36 | const struct jump_entry *jeb = b; | |
37 | ||
38 | if (jea->key < jeb->key) | |
39 | return -1; | |
40 | ||
41 | if (jea->key > jeb->key) | |
42 | return 1; | |
43 | ||
44 | return 0; | |
45 | } | |
46 | ||
47 | static void | |
d430d3d7 | 48 | jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop) |
bf5438fc JB |
49 | { |
50 | unsigned long size; | |
51 | ||
52 | size = (((unsigned long)stop - (unsigned long)start) | |
53 | / sizeof(struct jump_entry)); | |
54 | sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL); | |
55 | } | |
56 | ||
c5905afb | 57 | static void jump_label_update(struct static_key *key, int enable); |
bf5438fc | 58 | |
a1efb01f PZ |
59 | static inline bool static_key_type(struct static_key *key) |
60 | { | |
61 | return (unsigned long)key->entries & JUMP_TYPE_MASK; | |
62 | } | |
63 | ||
c5905afb | 64 | void static_key_slow_inc(struct static_key *key) |
bf5438fc | 65 | { |
c4b2c0c5 | 66 | STATIC_KEY_CHECK_USE(); |
d430d3d7 JB |
67 | if (atomic_inc_not_zero(&key->enabled)) |
68 | return; | |
bf5438fc | 69 | |
d430d3d7 | 70 | jump_label_lock(); |
c5905afb | 71 | if (atomic_read(&key->enabled) == 0) { |
a1efb01f | 72 | if (!static_key_type(key)) |
76b235c6 | 73 | jump_label_update(key, JUMP_LABEL_JMP); |
c5905afb | 74 | else |
76b235c6 | 75 | jump_label_update(key, JUMP_LABEL_NOP); |
c5905afb | 76 | } |
bbbf7af4 | 77 | atomic_inc(&key->enabled); |
d430d3d7 | 78 | jump_label_unlock(); |
bf5438fc | 79 | } |
c5905afb | 80 | EXPORT_SYMBOL_GPL(static_key_slow_inc); |
bf5438fc | 81 | |
c5905afb | 82 | static void __static_key_slow_dec(struct static_key *key, |
b2029520 | 83 | unsigned long rate_limit, struct delayed_work *work) |
bf5438fc | 84 | { |
fadf0464 JB |
85 | if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) { |
86 | WARN(atomic_read(&key->enabled) < 0, | |
87 | "jump label: negative count!\n"); | |
d430d3d7 | 88 | return; |
fadf0464 | 89 | } |
bf5438fc | 90 | |
b2029520 GN |
91 | if (rate_limit) { |
92 | atomic_inc(&key->enabled); | |
93 | schedule_delayed_work(work, rate_limit); | |
c5905afb | 94 | } else { |
a1efb01f | 95 | if (!static_key_type(key)) |
76b235c6 | 96 | jump_label_update(key, JUMP_LABEL_NOP); |
c5905afb | 97 | else |
76b235c6 | 98 | jump_label_update(key, JUMP_LABEL_JMP); |
c5905afb | 99 | } |
91bad2f8 | 100 | jump_label_unlock(); |
bf5438fc JB |
101 | } |
102 | ||
b2029520 GN |
103 | static void jump_label_update_timeout(struct work_struct *work) |
104 | { | |
c5905afb IM |
105 | struct static_key_deferred *key = |
106 | container_of(work, struct static_key_deferred, work.work); | |
107 | __static_key_slow_dec(&key->key, 0, NULL); | |
b2029520 GN |
108 | } |
109 | ||
c5905afb | 110 | void static_key_slow_dec(struct static_key *key) |
b2029520 | 111 | { |
c4b2c0c5 | 112 | STATIC_KEY_CHECK_USE(); |
c5905afb | 113 | __static_key_slow_dec(key, 0, NULL); |
b2029520 | 114 | } |
c5905afb | 115 | EXPORT_SYMBOL_GPL(static_key_slow_dec); |
b2029520 | 116 | |
c5905afb | 117 | void static_key_slow_dec_deferred(struct static_key_deferred *key) |
b2029520 | 118 | { |
c4b2c0c5 | 119 | STATIC_KEY_CHECK_USE(); |
c5905afb | 120 | __static_key_slow_dec(&key->key, key->timeout, &key->work); |
b2029520 | 121 | } |
c5905afb | 122 | EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred); |
b2029520 | 123 | |
c5905afb | 124 | void jump_label_rate_limit(struct static_key_deferred *key, |
b2029520 GN |
125 | unsigned long rl) |
126 | { | |
c4b2c0c5 | 127 | STATIC_KEY_CHECK_USE(); |
b2029520 GN |
128 | key->timeout = rl; |
129 | INIT_DELAYED_WORK(&key->work, jump_label_update_timeout); | |
130 | } | |
a181dc14 | 131 | EXPORT_SYMBOL_GPL(jump_label_rate_limit); |
b2029520 | 132 | |
4c3ef6d7 JB |
133 | static int addr_conflict(struct jump_entry *entry, void *start, void *end) |
134 | { | |
135 | if (entry->code <= (unsigned long)end && | |
136 | entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start) | |
137 | return 1; | |
138 | ||
139 | return 0; | |
140 | } | |
141 | ||
d430d3d7 JB |
142 | static int __jump_label_text_reserved(struct jump_entry *iter_start, |
143 | struct jump_entry *iter_stop, void *start, void *end) | |
4c3ef6d7 | 144 | { |
4c3ef6d7 | 145 | struct jump_entry *iter; |
4c3ef6d7 | 146 | |
4c3ef6d7 JB |
147 | iter = iter_start; |
148 | while (iter < iter_stop) { | |
d430d3d7 JB |
149 | if (addr_conflict(iter, start, end)) |
150 | return 1; | |
4c3ef6d7 JB |
151 | iter++; |
152 | } | |
153 | ||
d430d3d7 JB |
154 | return 0; |
155 | } | |
156 | ||
20284aa7 JF |
157 | /* |
158 | * Update code which is definitely not currently executing. | |
159 | * Architectures which need heavyweight synchronization to modify | |
160 | * running code can override this to make the non-live update case | |
161 | * cheaper. | |
162 | */ | |
9cdbe1cb | 163 | void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry, |
20284aa7 JF |
164 | enum jump_label_type type) |
165 | { | |
166 | arch_jump_label_transform(entry, type); | |
167 | } | |
168 | ||
c5905afb | 169 | static void __jump_label_update(struct static_key *key, |
7cbc5b8d JO |
170 | struct jump_entry *entry, |
171 | struct jump_entry *stop, int enable) | |
d430d3d7 | 172 | { |
7cbc5b8d JO |
173 | for (; (entry < stop) && |
174 | (entry->key == (jump_label_t)(unsigned long)key); | |
175 | entry++) { | |
d430d3d7 JB |
176 | /* |
177 | * entry->code set to 0 invalidates module init text sections | |
178 | * kernel_text_address() verifies we are not in core kernel | |
179 | * init code, see jump_label_invalidate_module_init(). | |
180 | */ | |
181 | if (entry->code && kernel_text_address(entry->code)) | |
182 | arch_jump_label_transform(entry, enable); | |
183 | } | |
4c3ef6d7 JB |
184 | } |
185 | ||
a1efb01f | 186 | static inline struct jump_entry *static_key_entries(struct static_key *key) |
c5905afb | 187 | { |
a1efb01f PZ |
188 | return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK); |
189 | } | |
c5905afb | 190 | |
a1efb01f PZ |
191 | static enum jump_label_type jump_label_type(struct static_key *key) |
192 | { | |
193 | bool enabled = static_key_enabled(key); | |
194 | bool type = static_key_type(key); | |
c5905afb | 195 | |
a1efb01f | 196 | return enabled ^ type; |
c5905afb IM |
197 | } |
198 | ||
97ce2c88 | 199 | void __init jump_label_init(void) |
bf5438fc | 200 | { |
bf5438fc JB |
201 | struct jump_entry *iter_start = __start___jump_table; |
202 | struct jump_entry *iter_stop = __stop___jump_table; | |
c5905afb | 203 | struct static_key *key = NULL; |
bf5438fc JB |
204 | struct jump_entry *iter; |
205 | ||
91bad2f8 | 206 | jump_label_lock(); |
d430d3d7 JB |
207 | jump_label_sort_entries(iter_start, iter_stop); |
208 | ||
209 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 210 | struct static_key *iterk; |
37348804 | 211 | |
c5905afb IM |
212 | iterk = (struct static_key *)(unsigned long)iter->key; |
213 | arch_jump_label_transform_static(iter, jump_label_type(iterk)); | |
37348804 | 214 | if (iterk == key) |
d430d3d7 JB |
215 | continue; |
216 | ||
37348804 | 217 | key = iterk; |
c5905afb IM |
218 | /* |
219 | * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH. | |
220 | */ | |
221 | *((unsigned long *)&key->entries) += (unsigned long)iter; | |
d430d3d7 JB |
222 | #ifdef CONFIG_MODULES |
223 | key->next = NULL; | |
224 | #endif | |
bf5438fc | 225 | } |
c4b2c0c5 | 226 | static_key_initialized = true; |
91bad2f8 | 227 | jump_label_unlock(); |
bf5438fc | 228 | } |
bf5438fc JB |
229 | |
230 | #ifdef CONFIG_MODULES | |
231 | ||
c5905afb IM |
232 | struct static_key_mod { |
233 | struct static_key_mod *next; | |
d430d3d7 JB |
234 | struct jump_entry *entries; |
235 | struct module *mod; | |
236 | }; | |
237 | ||
238 | static int __jump_label_mod_text_reserved(void *start, void *end) | |
239 | { | |
240 | struct module *mod; | |
241 | ||
242 | mod = __module_text_address((unsigned long)start); | |
243 | if (!mod) | |
244 | return 0; | |
245 | ||
246 | WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod); | |
247 | ||
248 | return __jump_label_text_reserved(mod->jump_entries, | |
249 | mod->jump_entries + mod->num_jump_entries, | |
250 | start, end); | |
251 | } | |
252 | ||
c5905afb | 253 | static void __jump_label_mod_update(struct static_key *key, int enable) |
d430d3d7 | 254 | { |
c5905afb | 255 | struct static_key_mod *mod = key->next; |
d430d3d7 JB |
256 | |
257 | while (mod) { | |
7cbc5b8d JO |
258 | struct module *m = mod->mod; |
259 | ||
260 | __jump_label_update(key, mod->entries, | |
261 | m->jump_entries + m->num_jump_entries, | |
262 | enable); | |
d430d3d7 JB |
263 | mod = mod->next; |
264 | } | |
265 | } | |
266 | ||
267 | /*** | |
268 | * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop() | |
269 | * @mod: module to patch | |
270 | * | |
271 | * Allow for run-time selection of the optimal nops. Before the module | |
272 | * loads patch these with arch_get_jump_label_nop(), which is specified by | |
273 | * the arch specific jump label code. | |
274 | */ | |
275 | void jump_label_apply_nops(struct module *mod) | |
bf5438fc | 276 | { |
d430d3d7 JB |
277 | struct jump_entry *iter_start = mod->jump_entries; |
278 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
279 | struct jump_entry *iter; | |
280 | ||
281 | /* if the module doesn't have jump label entries, just return */ | |
282 | if (iter_start == iter_stop) | |
283 | return; | |
284 | ||
ac99b862 | 285 | for (iter = iter_start; iter < iter_stop; iter++) { |
76b235c6 | 286 | arch_jump_label_transform_static(iter, JUMP_LABEL_NOP); |
ac99b862 | 287 | } |
bf5438fc JB |
288 | } |
289 | ||
d430d3d7 | 290 | static int jump_label_add_module(struct module *mod) |
bf5438fc | 291 | { |
d430d3d7 JB |
292 | struct jump_entry *iter_start = mod->jump_entries; |
293 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
294 | struct jump_entry *iter; | |
c5905afb IM |
295 | struct static_key *key = NULL; |
296 | struct static_key_mod *jlm; | |
bf5438fc JB |
297 | |
298 | /* if the module doesn't have jump label entries, just return */ | |
d430d3d7 | 299 | if (iter_start == iter_stop) |
bf5438fc JB |
300 | return 0; |
301 | ||
d430d3d7 JB |
302 | jump_label_sort_entries(iter_start, iter_stop); |
303 | ||
304 | for (iter = iter_start; iter < iter_stop; iter++) { | |
c5905afb | 305 | struct static_key *iterk; |
d430d3d7 | 306 | |
c5905afb IM |
307 | iterk = (struct static_key *)(unsigned long)iter->key; |
308 | if (iterk == key) | |
309 | continue; | |
d430d3d7 | 310 | |
c5905afb | 311 | key = iterk; |
bed831f9 | 312 | if (within_module(iter->key, mod)) { |
c5905afb IM |
313 | /* |
314 | * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH. | |
315 | */ | |
316 | *((unsigned long *)&key->entries) += (unsigned long)iter; | |
d430d3d7 JB |
317 | key->next = NULL; |
318 | continue; | |
bf5438fc | 319 | } |
c5905afb | 320 | jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL); |
d430d3d7 JB |
321 | if (!jlm) |
322 | return -ENOMEM; | |
d430d3d7 JB |
323 | jlm->mod = mod; |
324 | jlm->entries = iter; | |
325 | jlm->next = key->next; | |
326 | key->next = jlm; | |
327 | ||
76b235c6 PZ |
328 | if (jump_label_type(key) == JUMP_LABEL_JMP) |
329 | __jump_label_update(key, iter, iter_stop, JUMP_LABEL_JMP); | |
bf5438fc | 330 | } |
d430d3d7 | 331 | |
bf5438fc JB |
332 | return 0; |
333 | } | |
334 | ||
d430d3d7 | 335 | static void jump_label_del_module(struct module *mod) |
bf5438fc | 336 | { |
d430d3d7 JB |
337 | struct jump_entry *iter_start = mod->jump_entries; |
338 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
339 | struct jump_entry *iter; | |
c5905afb IM |
340 | struct static_key *key = NULL; |
341 | struct static_key_mod *jlm, **prev; | |
bf5438fc | 342 | |
d430d3d7 JB |
343 | for (iter = iter_start; iter < iter_stop; iter++) { |
344 | if (iter->key == (jump_label_t)(unsigned long)key) | |
345 | continue; | |
346 | ||
c5905afb | 347 | key = (struct static_key *)(unsigned long)iter->key; |
d430d3d7 | 348 | |
bed831f9 | 349 | if (within_module(iter->key, mod)) |
d430d3d7 JB |
350 | continue; |
351 | ||
352 | prev = &key->next; | |
353 | jlm = key->next; | |
bf5438fc | 354 | |
d430d3d7 JB |
355 | while (jlm && jlm->mod != mod) { |
356 | prev = &jlm->next; | |
357 | jlm = jlm->next; | |
358 | } | |
359 | ||
360 | if (jlm) { | |
361 | *prev = jlm->next; | |
362 | kfree(jlm); | |
bf5438fc JB |
363 | } |
364 | } | |
365 | } | |
366 | ||
d430d3d7 | 367 | static void jump_label_invalidate_module_init(struct module *mod) |
b842f8fa | 368 | { |
d430d3d7 JB |
369 | struct jump_entry *iter_start = mod->jump_entries; |
370 | struct jump_entry *iter_stop = iter_start + mod->num_jump_entries; | |
b842f8fa | 371 | struct jump_entry *iter; |
b842f8fa | 372 | |
d430d3d7 JB |
373 | for (iter = iter_start; iter < iter_stop; iter++) { |
374 | if (within_module_init(iter->code, mod)) | |
375 | iter->code = 0; | |
b842f8fa JB |
376 | } |
377 | } | |
378 | ||
bf5438fc JB |
379 | static int |
380 | jump_label_module_notify(struct notifier_block *self, unsigned long val, | |
381 | void *data) | |
382 | { | |
383 | struct module *mod = data; | |
384 | int ret = 0; | |
385 | ||
386 | switch (val) { | |
387 | case MODULE_STATE_COMING: | |
91bad2f8 | 388 | jump_label_lock(); |
d430d3d7 | 389 | ret = jump_label_add_module(mod); |
bf5438fc | 390 | if (ret) |
d430d3d7 | 391 | jump_label_del_module(mod); |
91bad2f8 | 392 | jump_label_unlock(); |
bf5438fc JB |
393 | break; |
394 | case MODULE_STATE_GOING: | |
91bad2f8 | 395 | jump_label_lock(); |
d430d3d7 | 396 | jump_label_del_module(mod); |
91bad2f8 | 397 | jump_label_unlock(); |
bf5438fc | 398 | break; |
b842f8fa | 399 | case MODULE_STATE_LIVE: |
91bad2f8 | 400 | jump_label_lock(); |
d430d3d7 | 401 | jump_label_invalidate_module_init(mod); |
91bad2f8 | 402 | jump_label_unlock(); |
b842f8fa | 403 | break; |
bf5438fc | 404 | } |
bf5438fc | 405 | |
d430d3d7 | 406 | return notifier_from_errno(ret); |
bf5438fc JB |
407 | } |
408 | ||
409 | struct notifier_block jump_label_module_nb = { | |
410 | .notifier_call = jump_label_module_notify, | |
d430d3d7 | 411 | .priority = 1, /* higher than tracepoints */ |
bf5438fc JB |
412 | }; |
413 | ||
d430d3d7 | 414 | static __init int jump_label_init_module(void) |
bf5438fc JB |
415 | { |
416 | return register_module_notifier(&jump_label_module_nb); | |
417 | } | |
d430d3d7 | 418 | early_initcall(jump_label_init_module); |
bf5438fc JB |
419 | |
420 | #endif /* CONFIG_MODULES */ | |
421 | ||
d430d3d7 JB |
422 | /*** |
423 | * jump_label_text_reserved - check if addr range is reserved | |
424 | * @start: start text addr | |
425 | * @end: end text addr | |
426 | * | |
427 | * checks if the text addr located between @start and @end | |
428 | * overlaps with any of the jump label patch addresses. Code | |
429 | * that wants to modify kernel text should first verify that | |
430 | * it does not overlap with any of the jump label addresses. | |
431 | * Caller must hold jump_label_mutex. | |
432 | * | |
433 | * returns 1 if there is an overlap, 0 otherwise | |
434 | */ | |
435 | int jump_label_text_reserved(void *start, void *end) | |
436 | { | |
437 | int ret = __jump_label_text_reserved(__start___jump_table, | |
438 | __stop___jump_table, start, end); | |
439 | ||
440 | if (ret) | |
441 | return ret; | |
442 | ||
443 | #ifdef CONFIG_MODULES | |
444 | ret = __jump_label_mod_text_reserved(start, end); | |
445 | #endif | |
446 | return ret; | |
447 | } | |
448 | ||
c5905afb | 449 | static void jump_label_update(struct static_key *key, int enable) |
d430d3d7 | 450 | { |
c5905afb | 451 | struct jump_entry *stop = __stop___jump_table; |
a1efb01f | 452 | struct jump_entry *entry = static_key_entries(key); |
d430d3d7 | 453 | #ifdef CONFIG_MODULES |
bed831f9 | 454 | struct module *mod; |
140fe3b1 | 455 | |
d430d3d7 | 456 | __jump_label_mod_update(key, enable); |
140fe3b1 | 457 | |
bed831f9 PZ |
458 | preempt_disable(); |
459 | mod = __module_address((unsigned long)key); | |
140fe3b1 XG |
460 | if (mod) |
461 | stop = mod->jump_entries + mod->num_jump_entries; | |
bed831f9 | 462 | preempt_enable(); |
d430d3d7 | 463 | #endif |
140fe3b1 XG |
464 | /* if there are no users, entry can be NULL */ |
465 | if (entry) | |
466 | __jump_label_update(key, entry, stop, enable); | |
d430d3d7 JB |
467 | } |
468 | ||
bf5438fc | 469 | #endif |