jump_label, locking/static_keys: Rename JUMP_LABEL_TYPE_* and related helpers to...
[linux-2.6-block.git] / kernel / jump_label.c
CommitLineData
bf5438fc
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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>
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6 *
7 */
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8#include <linux/memory.h>
9#include <linux/uaccess.h>
10#include <linux/module.h>
11#include <linux/list.h>
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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>
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17
18#ifdef HAVE_JUMP_LABEL
19
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20/* mutex to protect coming/going of the the jump_label table */
21static DEFINE_MUTEX(jump_label_mutex);
22
91bad2f8
JB
23void jump_label_lock(void)
24{
25 mutex_lock(&jump_label_mutex);
26}
27
28void jump_label_unlock(void)
29{
30 mutex_unlock(&jump_label_mutex);
31}
32
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JB
33static 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
47static void
d430d3d7 48jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
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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 57static void jump_label_update(struct static_key *key, int enable);
bf5438fc 58
a1efb01f
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59static inline bool static_key_type(struct static_key *key)
60{
61 return (unsigned long)key->entries & JUMP_TYPE_MASK;
62}
63
c5905afb 64void 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 80EXPORT_SYMBOL_GPL(static_key_slow_inc);
bf5438fc 81
c5905afb 82static 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();
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101}
102
b2029520
GN
103static void jump_label_update_timeout(struct work_struct *work)
104{
c5905afb
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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 110void 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 115EXPORT_SYMBOL_GPL(static_key_slow_dec);
b2029520 116
c5905afb 117void 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 122EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
b2029520 123
c5905afb 124void 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 131EXPORT_SYMBOL_GPL(jump_label_rate_limit);
b2029520 132
4c3ef6d7
JB
133static 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
142static 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 163void __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 169static 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 186static 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
191static 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 199void __init jump_label_init(void)
bf5438fc 200{
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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;
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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
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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}
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229
230#ifdef CONFIG_MODULES
231
c5905afb
IM
232struct static_key_mod {
233 struct static_key_mod *next;
d430d3d7
JB
234 struct jump_entry *entries;
235 struct module *mod;
236};
237
238static 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 253static 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 */
275void 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 290static 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 335static 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 367static 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
379static int
380jump_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
409struct 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 414static __init int jump_label_init_module(void)
bf5438fc
JB
415{
416 return register_module_notifier(&jump_label_module_nb);
417}
d430d3d7 418early_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 */
435int 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 449static 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