[linux-block.git] / kernel / jump_label.c

/*
 * jump label support
 *
 * Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
 * Copyright (C) 2011 Peter Zijlstra <pzijlstr@redhat.com>
 *
 */
#include <linux/memory.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/err.h>
#include <linux/static_key.h>
#include <linux/jump_label_ratelimit.h>

#ifdef HAVE_JUMP_LABEL

/* mutex to protect coming/going of the the jump_label table */
static DEFINE_MUTEX(jump_label_mutex);

void jump_label_lock(void)
{
	mutex_lock(&jump_label_mutex);
}

void jump_label_unlock(void)
{
	mutex_unlock(&jump_label_mutex);
}

static int jump_label_cmp(const void *a, const void *b)
{
	const struct jump_entry *jea = a;
	const struct jump_entry *jeb = b;

	if (jea->key < jeb->key)
		return -1;

	if (jea->key > jeb->key)
		return 1;

	return 0;
}

static void
jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
{
	unsigned long size;

	size = (((unsigned long)stop - (unsigned long)start)
					/ sizeof(struct jump_entry));
	sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
}

static void jump_label_update(struct static_key *key, int enable);

void static_key_slow_inc(struct static_key *key)
{
	STATIC_KEY_CHECK_USE();
	if (atomic_inc_not_zero(&key->enabled))
		return;

	jump_label_lock();
	if (atomic_read(&key->enabled) == 0) {
		if (!jump_label_get_branch_default(key))
			jump_label_update(key, JUMP_LABEL_ENABLE);
		else
			jump_label_update(key, JUMP_LABEL_DISABLE);
	}
	atomic_inc(&key->enabled);
	jump_label_unlock();
}
EXPORT_SYMBOL_GPL(static_key_slow_inc);

static void __static_key_slow_dec(struct static_key *key,
		unsigned long rate_limit, struct delayed_work *work)
{
	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
		WARN(atomic_read(&key->enabled) < 0,
		     "jump label: negative count!\n");
		return;
	}

	if (rate_limit) {
		atomic_inc(&key->enabled);
		schedule_delayed_work(work, rate_limit);
	} else {
		if (!jump_label_get_branch_default(key))
			jump_label_update(key, JUMP_LABEL_DISABLE);
		else
			jump_label_update(key, JUMP_LABEL_ENABLE);
	}
	jump_label_unlock();
}

static void jump_label_update_timeout(struct work_struct *work)
{
	struct static_key_deferred *key =
		container_of(work, struct static_key_deferred, work.work);
	__static_key_slow_dec(&key->key, 0, NULL);
}

void static_key_slow_dec(struct static_key *key)
{
	STATIC_KEY_CHECK_USE();
	__static_key_slow_dec(key, 0, NULL);
}
EXPORT_SYMBOL_GPL(static_key_slow_dec);

void static_key_slow_dec_deferred(struct static_key_deferred *key)
{
	STATIC_KEY_CHECK_USE();
	__static_key_slow_dec(&key->key, key->timeout, &key->work);
}
EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);

void jump_label_rate_limit(struct static_key_deferred *key,
		unsigned long rl)
{
	STATIC_KEY_CHECK_USE();
	key->timeout = rl;
	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
}
EXPORT_SYMBOL_GPL(jump_label_rate_limit);

static int addr_conflict(struct jump_entry *entry, void *start, void *end)
{
	if (entry->code <= (unsigned long)end &&
		entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
		return 1;

	return 0;
}

static int __jump_label_text_reserved(struct jump_entry *iter_start,
		struct jump_entry *iter_stop, void *start, void *end)
{
	struct jump_entry *iter;

	iter = iter_start;
	while (iter < iter_stop) {
		if (addr_conflict(iter, start, end))
			return 1;
		iter++;
	}

	return 0;
}

/* 
 * Update code which is definitely not currently executing.
 * Architectures which need heavyweight synchronization to modify
 * running code can override this to make the non-live update case
 * cheaper.
 */
void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
					    enum jump_label_type type)
{
	arch_jump_label_transform(entry, type);	
}

static void __jump_label_update(struct static_key *key,
				struct jump_entry *entry,
				struct jump_entry *stop, int enable)
{
	for (; (entry < stop) &&
	      (entry->key == (jump_label_t)(unsigned long)key);
	      entry++) {
		/*
		 * entry->code set to 0 invalidates module init text sections
		 * kernel_text_address() verifies we are not in core kernel
		 * init code, see jump_label_invalidate_module_init().
		 */
		if (entry->code && kernel_text_address(entry->code))
			arch_jump_label_transform(entry, enable);
	}
}

static enum jump_label_type jump_label_type(struct static_key *key)
{
	bool true_branch = jump_label_get_branch_default(key);
	bool state = static_key_enabled(key);

	if ((!true_branch && state) || (true_branch && !state))
		return JUMP_LABEL_ENABLE;

	return JUMP_LABEL_DISABLE;
}

void __init jump_label_init(void)
{
	struct jump_entry *iter_start = __start___jump_table;
	struct jump_entry *iter_stop = __stop___jump_table;
	struct static_key *key = NULL;
	struct jump_entry *iter;

	jump_label_lock();
	jump_label_sort_entries(iter_start, iter_stop);

	for (iter = iter_start; iter < iter_stop; iter++) {
		struct static_key *iterk;

		iterk = (struct static_key *)(unsigned long)iter->key;
		arch_jump_label_transform_static(iter, jump_label_type(iterk));
		if (iterk == key)
			continue;

		key = iterk;
		/*
		 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
		 */
		*((unsigned long *)&key->entries) += (unsigned long)iter;
#ifdef CONFIG_MODULES
		key->next = NULL;
#endif
	}
	static_key_initialized = true;
	jump_label_unlock();
}

#ifdef CONFIG_MODULES

struct static_key_mod {
	struct static_key_mod *next;
	struct jump_entry *entries;
	struct module *mod;
};

static int __jump_label_mod_text_reserved(void *start, void *end)
{
	struct module *mod;

	mod = __module_text_address((unsigned long)start);
	if (!mod)
		return 0;

	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);

	return __jump_label_text_reserved(mod->jump_entries,
				mod->jump_entries + mod->num_jump_entries,
				start, end);
}

static void __jump_label_mod_update(struct static_key *key, int enable)
{
	struct static_key_mod *mod = key->next;

	while (mod) {
		struct module *m = mod->mod;

		__jump_label_update(key, mod->entries,
				    m->jump_entries + m->num_jump_entries,
				    enable);
		mod = mod->next;
	}
}

/***
 * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
 * @mod: module to patch
 *
 * Allow for run-time selection of the optimal nops. Before the module
 * loads patch these with arch_get_jump_label_nop(), which is specified by
 * the arch specific jump label code.
 */
void jump_label_apply_nops(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;

	/* if the module doesn't have jump label entries, just return */
	if (iter_start == iter_stop)
		return;

	for (iter = iter_start; iter < iter_stop; iter++) {
		arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
	}
}

static int jump_label_add_module(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;
	struct static_key *key = NULL;
	struct static_key_mod *jlm;

	/* if the module doesn't have jump label entries, just return */
	if (iter_start == iter_stop)
		return 0;

	jump_label_sort_entries(iter_start, iter_stop);

	for (iter = iter_start; iter < iter_stop; iter++) {
		struct static_key *iterk;

		iterk = (struct static_key *)(unsigned long)iter->key;
		if (iterk == key)
			continue;

		key = iterk;
		if (__module_address(iter->key) == mod) {
			/*
			 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
			 */
			*((unsigned long *)&key->entries) += (unsigned long)iter;
			key->next = NULL;
			continue;
		}
		jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
		if (!jlm)
			return -ENOMEM;
		jlm->mod = mod;
		jlm->entries = iter;
		jlm->next = key->next;
		key->next = jlm;

		if (jump_label_type(key) == JUMP_LABEL_ENABLE)
			__jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE);
	}

	return 0;
}

static void jump_label_del_module(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;
	struct static_key *key = NULL;
	struct static_key_mod *jlm, **prev;

	for (iter = iter_start; iter < iter_stop; iter++) {
		if (iter->key == (jump_label_t)(unsigned long)key)
			continue;

		key = (struct static_key *)(unsigned long)iter->key;

		if (__module_address(iter->key) == mod)
			continue;

		prev = &key->next;
		jlm = key->next;

		while (jlm && jlm->mod != mod) {
			prev = &jlm->next;
			jlm = jlm->next;
		}

		if (jlm) {
			*prev = jlm->next;
			kfree(jlm);
		}
	}
}

static void jump_label_invalidate_module_init(struct module *mod)
{
	struct jump_entry *iter_start = mod->jump_entries;
	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	struct jump_entry *iter;

	for (iter = iter_start; iter < iter_stop; iter++) {
		if (within_module_init(iter->code, mod))
			iter->code = 0;
	}
}

static int
jump_label_module_notify(struct notifier_block *self, unsigned long val,
			 void *data)
{
	struct module *mod = data;
	int ret = 0;

	switch (val) {
	case MODULE_STATE_COMING:
		jump_label_lock();
		ret = jump_label_add_module(mod);
		if (ret)
			jump_label_del_module(mod);
		jump_label_unlock();
		break;
	case MODULE_STATE_GOING:
		jump_label_lock();
		jump_label_del_module(mod);
		jump_label_unlock();
		break;
	case MODULE_STATE_LIVE:
		jump_label_lock();
		jump_label_invalidate_module_init(mod);
		jump_label_unlock();
		break;
	}

	return notifier_from_errno(ret);
}

struct notifier_block jump_label_module_nb = {
	.notifier_call = jump_label_module_notify,
	.priority = 1, /* higher than tracepoints */
};

static __init int jump_label_init_module(void)
{
	return register_module_notifier(&jump_label_module_nb);
}
early_initcall(jump_label_init_module);

#endif /* CONFIG_MODULES */

/***
 * jump_label_text_reserved - check if addr range is reserved
 * @start: start text addr
 * @end: end text addr
 *
 * checks if the text addr located between @start and @end
 * overlaps with any of the jump label patch addresses. Code
 * that wants to modify kernel text should first verify that
 * it does not overlap with any of the jump label addresses.
 * Caller must hold jump_label_mutex.
 *
 * returns 1 if there is an overlap, 0 otherwise
 */
int jump_label_text_reserved(void *start, void *end)
{
	int ret = __jump_label_text_reserved(__start___jump_table,
			__stop___jump_table, start, end);

	if (ret)
		return ret;

#ifdef CONFIG_MODULES
	ret = __jump_label_mod_text_reserved(start, end);
#endif
	return ret;
}

static void jump_label_update(struct static_key *key, int enable)
{
	struct jump_entry *stop = __stop___jump_table;
	struct jump_entry *entry = jump_label_get_entries(key);

#ifdef CONFIG_MODULES
	struct module *mod = __module_address((unsigned long)key);

	__jump_label_mod_update(key, enable);

	if (mod)
		stop = mod->jump_entries + mod->num_jump_entries;
#endif
	/* if there are no users, entry can be NULL */
	if (entry)
		__jump_label_update(key, entry, stop, enable);
}

#endif
Commit	Line	Data
	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 */
	21	static DEFINE_MUTEX(jump_label_mutex);
	22
	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
	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
	48	jump_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
	57	static void jump_label_update(struct static_key *key, int enable);
	58
	59	void 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	}
	75	EXPORT_SYMBOL_GPL(static_key_slow_inc);
	76
	77	static 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
	98	static 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
	105	void static_key_slow_dec(struct static_key *key)
	106	{
	107	STATIC_KEY_CHECK_USE();
	108	__static_key_slow_dec(key, 0, NULL);
	109	}
	110	EXPORT_SYMBOL_GPL(static_key_slow_dec);
	111
	112	void 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	}
	117	EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
	118
	119	void 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	}
	126	EXPORT_SYMBOL_GPL(jump_label_rate_limit);
	127
	128	static 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
	137	static 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	*/
	158	void __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
	164	static 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
	181	static 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
	192	void __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
	225	struct static_key_mod {
	226	struct static_key_mod *next;
	227	struct jump_entry *entries;
	228	struct module *mod;
	229	};
	230
	231	static 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
	246	static 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	*/
	268	void 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
	283	static 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
	328	static 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
	360	static 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
	372	static int
	373	jump_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
	402	struct notifier_block jump_label_module_nb = {
	403	.notifier_call = jump_label_module_notify,
	404	.priority = 1, /* higher than tracepoints */
	405	};
	406
	407	static __init int jump_label_init_module(void)
	408	{
	409	return register_module_notifier(&jump_label_module_nb);
	410	}
	411	early_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	*/
	428	int 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
	442	static 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