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v3.15
  1/*
  2 * jump label support
  3 *
  4 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
  5 * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
  6 *
  7 */
  8#include <linux/memory.h>
  9#include <linux/uaccess.h>
 10#include <linux/module.h>
 11#include <linux/list.h>
 12#include <linux/slab.h>
 13#include <linux/sort.h>
 14#include <linux/err.h>
 15#include <linux/static_key.h>
 16#include <linux/jump_label_ratelimit.h>
 17
 18#ifdef HAVE_JUMP_LABEL
 19
 20/* mutex to protect coming/going of the the jump_label table */
 21static DEFINE_MUTEX(jump_label_mutex);
 22
 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
 
 
 
 
 
 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
 48jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
 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
 57static void jump_label_update(struct static_key *key, int enable);
 58
 59void static_key_slow_inc(struct static_key *key)
 60{
 61	STATIC_KEY_CHECK_USE();
 62	if (atomic_inc_not_zero(&key->enabled))
 63		return;
 64
 65	jump_label_lock();
 66	if (atomic_read(&key->enabled) == 0) {
 67		if (!jump_label_get_branch_default(key))
 68			jump_label_update(key, JUMP_LABEL_ENABLE);
 69		else
 70			jump_label_update(key, JUMP_LABEL_DISABLE);
 71	}
 72	atomic_inc(&key->enabled);
 73	jump_label_unlock();
 74}
 75EXPORT_SYMBOL_GPL(static_key_slow_inc);
 76
 77static void __static_key_slow_dec(struct static_key *key,
 78		unsigned long rate_limit, struct delayed_work *work)
 79{
 80	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
 81		WARN(atomic_read(&key->enabled) < 0,
 82		     "jump label: negative count!\n");
 83		return;
 84	}
 85
 86	if (rate_limit) {
 87		atomic_inc(&key->enabled);
 88		schedule_delayed_work(work, rate_limit);
 89	} else {
 90		if (!jump_label_get_branch_default(key))
 91			jump_label_update(key, JUMP_LABEL_DISABLE);
 92		else
 93			jump_label_update(key, JUMP_LABEL_ENABLE);
 94	}
 95	jump_label_unlock();
 96}
 97
 98static void jump_label_update_timeout(struct work_struct *work)
 99{
100	struct static_key_deferred *key =
101		container_of(work, struct static_key_deferred, work.work);
102	__static_key_slow_dec(&key->key, 0, NULL);
103}
104
105void static_key_slow_dec(struct static_key *key)
106{
107	STATIC_KEY_CHECK_USE();
108	__static_key_slow_dec(key, 0, NULL);
109}
110EXPORT_SYMBOL_GPL(static_key_slow_dec);
111
112void static_key_slow_dec_deferred(struct static_key_deferred *key)
113{
114	STATIC_KEY_CHECK_USE();
115	__static_key_slow_dec(&key->key, key->timeout, &key->work);
116}
117EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
118
119void jump_label_rate_limit(struct static_key_deferred *key,
120		unsigned long rl)
121{
122	STATIC_KEY_CHECK_USE();
123	key->timeout = rl;
124	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
125}
126EXPORT_SYMBOL_GPL(jump_label_rate_limit);
127
128static int addr_conflict(struct jump_entry *entry, void *start, void *end)
129{
130	if (entry->code <= (unsigned long)end &&
131		entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
132		return 1;
133
134	return 0;
135}
136
137static int __jump_label_text_reserved(struct jump_entry *iter_start,
138		struct jump_entry *iter_stop, void *start, void *end)
139{
140	struct jump_entry *iter;
141
142	iter = iter_start;
143	while (iter < iter_stop) {
144		if (addr_conflict(iter, start, end))
145			return 1;
146		iter++;
147	}
148
149	return 0;
150}
151
152/* 
153 * Update code which is definitely not currently executing.
154 * Architectures which need heavyweight synchronization to modify
155 * running code can override this to make the non-live update case
156 * cheaper.
157 */
158void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
159					    enum jump_label_type type)
160{
161	arch_jump_label_transform(entry, type);	
162}
163
164static void __jump_label_update(struct static_key *key,
165				struct jump_entry *entry,
166				struct jump_entry *stop, int enable)
167{
168	for (; (entry < stop) &&
169	      (entry->key == (jump_label_t)(unsigned long)key);
170	      entry++) {
171		/*
172		 * entry->code set to 0 invalidates module init text sections
173		 * kernel_text_address() verifies we are not in core kernel
174		 * init code, see jump_label_invalidate_module_init().
175		 */
176		if (entry->code && kernel_text_address(entry->code))
177			arch_jump_label_transform(entry, enable);
178	}
179}
180
181static enum jump_label_type jump_label_type(struct static_key *key)
 
 
 
182{
183	bool true_branch = jump_label_get_branch_default(key);
184	bool state = static_key_enabled(key);
185
186	if ((!true_branch && state) || (true_branch && !state))
187		return JUMP_LABEL_ENABLE;
188
189	return JUMP_LABEL_DISABLE;
190}
191
192void __init jump_label_init(void)
193{
194	struct jump_entry *iter_start = __start___jump_table;
195	struct jump_entry *iter_stop = __stop___jump_table;
196	struct static_key *key = NULL;
197	struct jump_entry *iter;
198
199	jump_label_lock();
200	jump_label_sort_entries(iter_start, iter_stop);
201
202	for (iter = iter_start; iter < iter_stop; iter++) {
203		struct static_key *iterk;
204
205		iterk = (struct static_key *)(unsigned long)iter->key;
206		arch_jump_label_transform_static(iter, jump_label_type(iterk));
207		if (iterk == key)
208			continue;
209
210		key = iterk;
211		/*
212		 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
213		 */
214		*((unsigned long *)&key->entries) += (unsigned long)iter;
215#ifdef CONFIG_MODULES
216		key->next = NULL;
217#endif
218	}
219	static_key_initialized = true;
220	jump_label_unlock();
 
 
221}
 
222
223#ifdef CONFIG_MODULES
224
225struct static_key_mod {
226	struct static_key_mod *next;
227	struct jump_entry *entries;
228	struct module *mod;
229};
230
231static int __jump_label_mod_text_reserved(void *start, void *end)
232{
233	struct module *mod;
234
235	mod = __module_text_address((unsigned long)start);
236	if (!mod)
237		return 0;
238
239	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
240
241	return __jump_label_text_reserved(mod->jump_entries,
242				mod->jump_entries + mod->num_jump_entries,
243				start, end);
244}
245
246static void __jump_label_mod_update(struct static_key *key, int enable)
247{
248	struct static_key_mod *mod = key->next;
249
250	while (mod) {
251		struct module *m = mod->mod;
252
253		__jump_label_update(key, mod->entries,
254				    m->jump_entries + m->num_jump_entries,
255				    enable);
256		mod = mod->next;
257	}
258}
259
260/***
261 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
262 * @mod: module to patch
263 *
264 * Allow for run-time selection of the optimal nops. Before the module
265 * loads patch these with arch_get_jump_label_nop(), which is specified by
266 * the arch specific jump label code.
267 */
268void jump_label_apply_nops(struct module *mod)
269{
270	struct jump_entry *iter_start = mod->jump_entries;
271	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
272	struct jump_entry *iter;
273
274	/* if the module doesn't have jump label entries, just return */
275	if (iter_start == iter_stop)
276		return;
277
278	for (iter = iter_start; iter < iter_stop; iter++) {
279		arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
280	}
281}
282
283static int jump_label_add_module(struct module *mod)
284{
285	struct jump_entry *iter_start = mod->jump_entries;
286	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
287	struct jump_entry *iter;
288	struct static_key *key = NULL;
289	struct static_key_mod *jlm;
290
291	/* if the module doesn't have jump label entries, just return */
292	if (iter_start == iter_stop)
293		return 0;
294
295	jump_label_sort_entries(iter_start, iter_stop);
296
297	for (iter = iter_start; iter < iter_stop; iter++) {
298		struct static_key *iterk;
299
300		iterk = (struct static_key *)(unsigned long)iter->key;
301		if (iterk == key)
302			continue;
303
304		key = iterk;
 
305		if (__module_address(iter->key) == mod) {
306			/*
307			 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
308			 */
309			*((unsigned long *)&key->entries) += (unsigned long)iter;
310			key->next = NULL;
311			continue;
312		}
313		jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
 
314		if (!jlm)
315			return -ENOMEM;
 
316		jlm->mod = mod;
317		jlm->entries = iter;
318		jlm->next = key->next;
319		key->next = jlm;
320
321		if (jump_label_type(key) == JUMP_LABEL_ENABLE)
322			__jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE);
 
323	}
324
325	return 0;
326}
327
328static void jump_label_del_module(struct module *mod)
329{
330	struct jump_entry *iter_start = mod->jump_entries;
331	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
332	struct jump_entry *iter;
333	struct static_key *key = NULL;
334	struct static_key_mod *jlm, **prev;
335
336	for (iter = iter_start; iter < iter_stop; iter++) {
337		if (iter->key == (jump_label_t)(unsigned long)key)
338			continue;
339
340		key = (struct static_key *)(unsigned long)iter->key;
341
342		if (__module_address(iter->key) == mod)
343			continue;
344
345		prev = &key->next;
346		jlm = key->next;
347
348		while (jlm && jlm->mod != mod) {
349			prev = &jlm->next;
350			jlm = jlm->next;
351		}
352
353		if (jlm) {
354			*prev = jlm->next;
355			kfree(jlm);
356		}
357	}
358}
359
360static void jump_label_invalidate_module_init(struct module *mod)
361{
362	struct jump_entry *iter_start = mod->jump_entries;
363	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
364	struct jump_entry *iter;
365
366	for (iter = iter_start; iter < iter_stop; iter++) {
367		if (within_module_init(iter->code, mod))
368			iter->code = 0;
369	}
370}
371
372static int
373jump_label_module_notify(struct notifier_block *self, unsigned long val,
374			 void *data)
375{
376	struct module *mod = data;
377	int ret = 0;
378
379	switch (val) {
380	case MODULE_STATE_COMING:
381		jump_label_lock();
382		ret = jump_label_add_module(mod);
383		if (ret)
384			jump_label_del_module(mod);
385		jump_label_unlock();
386		break;
387	case MODULE_STATE_GOING:
388		jump_label_lock();
389		jump_label_del_module(mod);
390		jump_label_unlock();
391		break;
392	case MODULE_STATE_LIVE:
393		jump_label_lock();
394		jump_label_invalidate_module_init(mod);
395		jump_label_unlock();
396		break;
397	}
398
399	return notifier_from_errno(ret);
400}
401
402struct notifier_block jump_label_module_nb = {
403	.notifier_call = jump_label_module_notify,
404	.priority = 1, /* higher than tracepoints */
405};
406
407static __init int jump_label_init_module(void)
408{
409	return register_module_notifier(&jump_label_module_nb);
410}
411early_initcall(jump_label_init_module);
412
413#endif /* CONFIG_MODULES */
414
415/***
416 * jump_label_text_reserved - check if addr range is reserved
417 * @start: start text addr
418 * @end: end text addr
419 *
420 * checks if the text addr located between @start and @end
421 * overlaps with any of the jump label patch addresses. Code
422 * that wants to modify kernel text should first verify that
423 * it does not overlap with any of the jump label addresses.
424 * Caller must hold jump_label_mutex.
425 *
426 * returns 1 if there is an overlap, 0 otherwise
427 */
428int jump_label_text_reserved(void *start, void *end)
429{
430	int ret = __jump_label_text_reserved(__start___jump_table,
431			__stop___jump_table, start, end);
432
433	if (ret)
434		return ret;
435
436#ifdef CONFIG_MODULES
437	ret = __jump_label_mod_text_reserved(start, end);
438#endif
439	return ret;
440}
441
442static void jump_label_update(struct static_key *key, int enable)
443{
444	struct jump_entry *stop = __stop___jump_table;
445	struct jump_entry *entry = jump_label_get_entries(key);
446
447#ifdef CONFIG_MODULES
448	struct module *mod = __module_address((unsigned long)key);
449
450	__jump_label_mod_update(key, enable);
451
452	if (mod)
453		stop = mod->jump_entries + mod->num_jump_entries;
454#endif
455	/* if there are no users, entry can be NULL */
456	if (entry)
457		__jump_label_update(key, entry, stop, enable);
458}
459
460#endif
v3.1
  1/*
  2 * jump label support
  3 *
  4 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
  5 * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
  6 *
  7 */
  8#include <linux/memory.h>
  9#include <linux/uaccess.h>
 10#include <linux/module.h>
 11#include <linux/list.h>
 12#include <linux/slab.h>
 13#include <linux/sort.h>
 14#include <linux/err.h>
 15#include <linux/jump_label.h>
 
 16
 17#ifdef HAVE_JUMP_LABEL
 18
 19/* mutex to protect coming/going of the the jump_label table */
 20static DEFINE_MUTEX(jump_label_mutex);
 21
 22void jump_label_lock(void)
 23{
 24	mutex_lock(&jump_label_mutex);
 25}
 26
 27void jump_label_unlock(void)
 28{
 29	mutex_unlock(&jump_label_mutex);
 30}
 31
 32bool jump_label_enabled(struct jump_label_key *key)
 33{
 34	return !!atomic_read(&key->enabled);
 35}
 36
 37static int jump_label_cmp(const void *a, const void *b)
 38{
 39	const struct jump_entry *jea = a;
 40	const struct jump_entry *jeb = b;
 41
 42	if (jea->key < jeb->key)
 43		return -1;
 44
 45	if (jea->key > jeb->key)
 46		return 1;
 47
 48	return 0;
 49}
 50
 51static void
 52jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
 53{
 54	unsigned long size;
 55
 56	size = (((unsigned long)stop - (unsigned long)start)
 57					/ sizeof(struct jump_entry));
 58	sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
 59}
 60
 61static void jump_label_update(struct jump_label_key *key, int enable);
 62
 63void jump_label_inc(struct jump_label_key *key)
 64{
 
 65	if (atomic_inc_not_zero(&key->enabled))
 66		return;
 67
 68	jump_label_lock();
 69	if (atomic_add_return(1, &key->enabled) == 1)
 70		jump_label_update(key, JUMP_LABEL_ENABLE);
 
 
 
 
 
 71	jump_label_unlock();
 72}
 
 73
 74void jump_label_dec(struct jump_label_key *key)
 
 75{
 76	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex))
 
 
 77		return;
 
 78
 79	jump_label_update(key, JUMP_LABEL_DISABLE);
 
 
 
 
 
 
 
 
 80	jump_label_unlock();
 81}
 82
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 83static int addr_conflict(struct jump_entry *entry, void *start, void *end)
 84{
 85	if (entry->code <= (unsigned long)end &&
 86		entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
 87		return 1;
 88
 89	return 0;
 90}
 91
 92static int __jump_label_text_reserved(struct jump_entry *iter_start,
 93		struct jump_entry *iter_stop, void *start, void *end)
 94{
 95	struct jump_entry *iter;
 96
 97	iter = iter_start;
 98	while (iter < iter_stop) {
 99		if (addr_conflict(iter, start, end))
100			return 1;
101		iter++;
102	}
103
104	return 0;
105}
106
107static void __jump_label_update(struct jump_label_key *key,
 
 
 
 
 
 
 
 
 
 
 
 
108				struct jump_entry *entry,
109				struct jump_entry *stop, int enable)
110{
111	for (; (entry < stop) &&
112	      (entry->key == (jump_label_t)(unsigned long)key);
113	      entry++) {
114		/*
115		 * entry->code set to 0 invalidates module init text sections
116		 * kernel_text_address() verifies we are not in core kernel
117		 * init code, see jump_label_invalidate_module_init().
118		 */
119		if (entry->code && kernel_text_address(entry->code))
120			arch_jump_label_transform(entry, enable);
121	}
122}
123
124/*
125 * Not all archs need this.
126 */
127void __weak arch_jump_label_text_poke_early(jump_label_t addr)
128{
 
 
 
 
 
 
 
129}
130
131static __init int jump_label_init(void)
132{
133	struct jump_entry *iter_start = __start___jump_table;
134	struct jump_entry *iter_stop = __stop___jump_table;
135	struct jump_label_key *key = NULL;
136	struct jump_entry *iter;
137
138	jump_label_lock();
139	jump_label_sort_entries(iter_start, iter_stop);
140
141	for (iter = iter_start; iter < iter_stop; iter++) {
142		arch_jump_label_text_poke_early(iter->code);
143		if (iter->key == (jump_label_t)(unsigned long)key)
 
 
 
144			continue;
145
146		key = (struct jump_label_key *)(unsigned long)iter->key;
147		atomic_set(&key->enabled, 0);
148		key->entries = iter;
 
 
149#ifdef CONFIG_MODULES
150		key->next = NULL;
151#endif
152	}
 
153	jump_label_unlock();
154
155	return 0;
156}
157early_initcall(jump_label_init);
158
159#ifdef CONFIG_MODULES
160
161struct jump_label_mod {
162	struct jump_label_mod *next;
163	struct jump_entry *entries;
164	struct module *mod;
165};
166
167static int __jump_label_mod_text_reserved(void *start, void *end)
168{
169	struct module *mod;
170
171	mod = __module_text_address((unsigned long)start);
172	if (!mod)
173		return 0;
174
175	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
176
177	return __jump_label_text_reserved(mod->jump_entries,
178				mod->jump_entries + mod->num_jump_entries,
179				start, end);
180}
181
182static void __jump_label_mod_update(struct jump_label_key *key, int enable)
183{
184	struct jump_label_mod *mod = key->next;
185
186	while (mod) {
187		struct module *m = mod->mod;
188
189		__jump_label_update(key, mod->entries,
190				    m->jump_entries + m->num_jump_entries,
191				    enable);
192		mod = mod->next;
193	}
194}
195
196/***
197 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
198 * @mod: module to patch
199 *
200 * Allow for run-time selection of the optimal nops. Before the module
201 * loads patch these with arch_get_jump_label_nop(), which is specified by
202 * the arch specific jump label code.
203 */
204void jump_label_apply_nops(struct module *mod)
205{
206	struct jump_entry *iter_start = mod->jump_entries;
207	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
208	struct jump_entry *iter;
209
210	/* if the module doesn't have jump label entries, just return */
211	if (iter_start == iter_stop)
212		return;
213
214	for (iter = iter_start; iter < iter_stop; iter++)
215		arch_jump_label_text_poke_early(iter->code);
 
216}
217
218static int jump_label_add_module(struct module *mod)
219{
220	struct jump_entry *iter_start = mod->jump_entries;
221	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
222	struct jump_entry *iter;
223	struct jump_label_key *key = NULL;
224	struct jump_label_mod *jlm;
225
226	/* if the module doesn't have jump label entries, just return */
227	if (iter_start == iter_stop)
228		return 0;
229
230	jump_label_sort_entries(iter_start, iter_stop);
231
232	for (iter = iter_start; iter < iter_stop; iter++) {
233		if (iter->key == (jump_label_t)(unsigned long)key)
 
 
 
234			continue;
235
236		key = (struct jump_label_key *)(unsigned long)iter->key;
237
238		if (__module_address(iter->key) == mod) {
239			atomic_set(&key->enabled, 0);
240			key->entries = iter;
 
 
241			key->next = NULL;
242			continue;
243		}
244
245		jlm = kzalloc(sizeof(struct jump_label_mod), GFP_KERNEL);
246		if (!jlm)
247			return -ENOMEM;
248
249		jlm->mod = mod;
250		jlm->entries = iter;
251		jlm->next = key->next;
252		key->next = jlm;
253
254		if (jump_label_enabled(key))
255			__jump_label_update(key, iter, iter_stop,
256					    JUMP_LABEL_ENABLE);
257	}
258
259	return 0;
260}
261
262static void jump_label_del_module(struct module *mod)
263{
264	struct jump_entry *iter_start = mod->jump_entries;
265	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
266	struct jump_entry *iter;
267	struct jump_label_key *key = NULL;
268	struct jump_label_mod *jlm, **prev;
269
270	for (iter = iter_start; iter < iter_stop; iter++) {
271		if (iter->key == (jump_label_t)(unsigned long)key)
272			continue;
273
274		key = (struct jump_label_key *)(unsigned long)iter->key;
275
276		if (__module_address(iter->key) == mod)
277			continue;
278
279		prev = &key->next;
280		jlm = key->next;
281
282		while (jlm && jlm->mod != mod) {
283			prev = &jlm->next;
284			jlm = jlm->next;
285		}
286
287		if (jlm) {
288			*prev = jlm->next;
289			kfree(jlm);
290		}
291	}
292}
293
294static void jump_label_invalidate_module_init(struct module *mod)
295{
296	struct jump_entry *iter_start = mod->jump_entries;
297	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
298	struct jump_entry *iter;
299
300	for (iter = iter_start; iter < iter_stop; iter++) {
301		if (within_module_init(iter->code, mod))
302			iter->code = 0;
303	}
304}
305
306static int
307jump_label_module_notify(struct notifier_block *self, unsigned long val,
308			 void *data)
309{
310	struct module *mod = data;
311	int ret = 0;
312
313	switch (val) {
314	case MODULE_STATE_COMING:
315		jump_label_lock();
316		ret = jump_label_add_module(mod);
317		if (ret)
318			jump_label_del_module(mod);
319		jump_label_unlock();
320		break;
321	case MODULE_STATE_GOING:
322		jump_label_lock();
323		jump_label_del_module(mod);
324		jump_label_unlock();
325		break;
326	case MODULE_STATE_LIVE:
327		jump_label_lock();
328		jump_label_invalidate_module_init(mod);
329		jump_label_unlock();
330		break;
331	}
332
333	return notifier_from_errno(ret);
334}
335
336struct notifier_block jump_label_module_nb = {
337	.notifier_call = jump_label_module_notify,
338	.priority = 1, /* higher than tracepoints */
339};
340
341static __init int jump_label_init_module(void)
342{
343	return register_module_notifier(&jump_label_module_nb);
344}
345early_initcall(jump_label_init_module);
346
347#endif /* CONFIG_MODULES */
348
349/***
350 * jump_label_text_reserved - check if addr range is reserved
351 * @start: start text addr
352 * @end: end text addr
353 *
354 * checks if the text addr located between @start and @end
355 * overlaps with any of the jump label patch addresses. Code
356 * that wants to modify kernel text should first verify that
357 * it does not overlap with any of the jump label addresses.
358 * Caller must hold jump_label_mutex.
359 *
360 * returns 1 if there is an overlap, 0 otherwise
361 */
362int jump_label_text_reserved(void *start, void *end)
363{
364	int ret = __jump_label_text_reserved(__start___jump_table,
365			__stop___jump_table, start, end);
366
367	if (ret)
368		return ret;
369
370#ifdef CONFIG_MODULES
371	ret = __jump_label_mod_text_reserved(start, end);
372#endif
373	return ret;
374}
375
376static void jump_label_update(struct jump_label_key *key, int enable)
377{
378	struct jump_entry *entry = key->entries, *stop = __stop___jump_table;
 
379
380#ifdef CONFIG_MODULES
381	struct module *mod = __module_address((jump_label_t)key);
382
383	__jump_label_mod_update(key, enable);
384
385	if (mod)
386		stop = mod->jump_entries + mod->num_jump_entries;
387#endif
388	/* if there are no users, entry can be NULL */
389	if (entry)
390		__jump_label_update(key, entry, stop, enable);
391}
392
393#endif