[linux-2.6-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);

static inline bool static_key_type(struct static_key *key)
{
	return (unsigned long)key->entries & JUMP_TYPE_MASK;
}

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 (!static_key_type(key))
			jump_label_update(key, JUMP_LABEL_JMP);
		else
			jump_label_update(key, JUMP_LABEL_NOP);
	}
	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 (!static_key_type(key))
			jump_label_update(key, JUMP_LABEL_NOP);
		else
			jump_label_update(key, JUMP_LABEL_JMP);
	}
	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 inline struct jump_entry *static_key_entries(struct static_key *key)
{
	return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK);
}

static inline struct static_key *jump_entry_key(struct jump_entry *entry)
{
	return (struct static_key *)((unsigned long)entry->key);
}

static enum jump_label_type jump_label_type(struct static_key *key)
{
	bool enabled = static_key_enabled(key);
	bool type = static_key_type(key);

	return enabled ^ type;
}

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 = jump_entry_key(iter);
		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_NOP);
	}
}

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 = jump_entry_key(iter);
		if (iterk == key)
			continue;

		key = iterk;
		if (within_module(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_JMP)
			__jump_label_update(key, iter, iter_stop, JUMP_LABEL_JMP);
	}

	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 (jump_entry_key(iter) == key)
			continue;

		key = jump_entry_key(iter);

		if (within_module(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 = static_key_entries(key);
#ifdef CONFIG_MODULES
	struct module *mod;

	__jump_label_mod_update(key, enable);

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

#endif
Commit	Line	Data
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	*
bf5438fc JB	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))
d430d3d7 JB	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	}
bf5438fc JB	102
b2029520 GN	103	static void jump_label_update_timeout(struct work_struct *work)
b2029520 GN	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	}
b2029520 GN	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)
b2029520 GN	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,
d430d3d7 JB	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;
4c3ef6d7 JB	148	while (iter < iter_stop) {
d430d3d7 JB	149	if (addr_conflict(iter, start, end))
d430d3d7 JB	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,
7cbc5b8d JO	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	}
4c3ef6d7 JB	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);
a1efb01f PZ	189	}
c5905afb	190
7dcfd915 PZ	191	static inline struct static_key jump_entry_key(struct jump_entry entry)
	192	{
	193	return (struct static_key *)((unsigned long)entry->key);
	194	}
	195
a1efb01f PZ	196	static enum jump_label_type jump_label_type(struct static_key *key)
	197	{
	198	bool enabled = static_key_enabled(key);
	199	bool type = static_key_type(key);
c5905afb	200
a1efb01f	201	return enabled ^ type;
c5905afb IM	202	}
c5905afb IM	203
97ce2c88	204	void __init jump_label_init(void)
bf5438fc	205	{
bf5438fc JB	206	struct jump_entry *iter_start = __start___jump_table;
bf5438fc JB	207	struct jump_entry *iter_stop = __stop___jump_table;
c5905afb	208	struct static_key *key = NULL;
bf5438fc JB	209	struct jump_entry *iter;
bf5438fc JB	210
91bad2f8	211	jump_label_lock();
d430d3d7 JB	212	jump_label_sort_entries(iter_start, iter_stop);
	213
	214	for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb	215	struct static_key *iterk;
37348804	216
7dcfd915	217	iterk = jump_entry_key(iter);
c5905afb	218	arch_jump_label_transform_static(iter, jump_label_type(iterk));
37348804	219	if (iterk == key)
d430d3d7 JB	220	continue;
d430d3d7 JB	221
37348804	222	key = iterk;
c5905afb IM	223	/*
	224	* Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
	225	*/
	226	((unsigned long )&key->entries) += (unsigned long)iter;
d430d3d7 JB	227	#ifdef CONFIG_MODULES
	228	key->next = NULL;
	229	#endif
bf5438fc	230	}
c4b2c0c5	231	static_key_initialized = true;
91bad2f8	232	jump_label_unlock();
bf5438fc	233	}
bf5438fc JB	234
	235	#ifdef CONFIG_MODULES
	236
c5905afb IM	237	struct static_key_mod {
c5905afb IM	238	struct static_key_mod *next;
d430d3d7 JB	239	struct jump_entry *entries;
	240	struct module *mod;
	241	};
	242
	243	static int __jump_label_mod_text_reserved(void start, void end)
	244	{
	245	struct module *mod;
	246
	247	mod = __module_text_address((unsigned long)start);
	248	if (!mod)
	249	return 0;
	250
	251	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
	252
	253	return __jump_label_text_reserved(mod->jump_entries,
	254	mod->jump_entries + mod->num_jump_entries,
	255	start, end);
	256	}
	257
c5905afb	258	static void __jump_label_mod_update(struct static_key *key, int enable)
d430d3d7	259	{
c5905afb	260	struct static_key_mod *mod = key->next;
d430d3d7 JB	261
d430d3d7 JB	262	while (mod) {
7cbc5b8d JO	263	struct module *m = mod->mod;
	264
	265	__jump_label_update(key, mod->entries,
	266	m->jump_entries + m->num_jump_entries,
	267	enable);
d430d3d7 JB	268	mod = mod->next;
	269	}
	270	}
	271
	272	/***
	273	* apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
	274	* @mod: module to patch
	275	*
	276	* Allow for run-time selection of the optimal nops. Before the module
	277	* loads patch these with arch_get_jump_label_nop(), which is specified by
	278	* the arch specific jump label code.
	279	*/
	280	void jump_label_apply_nops(struct module *mod)
bf5438fc	281	{
d430d3d7 JB	282	struct jump_entry *iter_start = mod->jump_entries;
	283	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	284	struct jump_entry *iter;
	285
	286	/* if the module doesn't have jump label entries, just return */
	287	if (iter_start == iter_stop)
	288	return;
	289
ac99b862	290	for (iter = iter_start; iter < iter_stop; iter++) {
76b235c6	291	arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
ac99b862	292	}
bf5438fc JB	293	}
bf5438fc JB	294
d430d3d7	295	static int jump_label_add_module(struct module *mod)
bf5438fc	296	{
d430d3d7 JB	297	struct jump_entry *iter_start = mod->jump_entries;
	298	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	299	struct jump_entry *iter;
c5905afb IM	300	struct static_key *key = NULL;
c5905afb IM	301	struct static_key_mod *jlm;
bf5438fc JB	302
bf5438fc JB	303	/* if the module doesn't have jump label entries, just return */
d430d3d7	304	if (iter_start == iter_stop)
bf5438fc JB	305	return 0;
bf5438fc JB	306
d430d3d7 JB	307	jump_label_sort_entries(iter_start, iter_stop);
	308
	309	for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb	310	struct static_key *iterk;
d430d3d7	311
7dcfd915	312	iterk = jump_entry_key(iter);
c5905afb IM	313	if (iterk == key)
c5905afb IM	314	continue;
d430d3d7	315
c5905afb	316	key = iterk;
bed831f9	317	if (within_module(iter->key, mod)) {
c5905afb IM	318	/*
	319	* Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
	320	*/
	321	((unsigned long )&key->entries) += (unsigned long)iter;
d430d3d7 JB	322	key->next = NULL;
d430d3d7 JB	323	continue;
bf5438fc	324	}
c5905afb	325	jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
d430d3d7 JB	326	if (!jlm)
d430d3d7 JB	327	return -ENOMEM;
d430d3d7 JB	328	jlm->mod = mod;
	329	jlm->entries = iter;
	330	jlm->next = key->next;
	331	key->next = jlm;
	332
76b235c6 PZ	333	if (jump_label_type(key) == JUMP_LABEL_JMP)
76b235c6 PZ	334	__jump_label_update(key, iter, iter_stop, JUMP_LABEL_JMP);
bf5438fc	335	}
d430d3d7	336
bf5438fc JB	337	return 0;
	338	}
	339
d430d3d7	340	static void jump_label_del_module(struct module *mod)
bf5438fc	341	{
d430d3d7 JB	342	struct jump_entry *iter_start = mod->jump_entries;
	343	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	344	struct jump_entry *iter;
c5905afb IM	345	struct static_key *key = NULL;
c5905afb IM	346	struct static_key_mod jlm, *prev;
bf5438fc	347
d430d3d7	348	for (iter = iter_start; iter < iter_stop; iter++) {
7dcfd915	349	if (jump_entry_key(iter) == key)
d430d3d7 JB	350	continue;
d430d3d7 JB	351
7dcfd915	352	key = jump_entry_key(iter);
d430d3d7	353
bed831f9	354	if (within_module(iter->key, mod))
d430d3d7 JB	355	continue;
	356
	357	prev = &key->next;
	358	jlm = key->next;
bf5438fc	359
d430d3d7 JB	360	while (jlm && jlm->mod != mod) {
	361	prev = &jlm->next;
	362	jlm = jlm->next;
	363	}
	364
	365	if (jlm) {
	366	*prev = jlm->next;
	367	kfree(jlm);
bf5438fc JB	368	}
	369	}
	370	}
	371
d430d3d7	372	static void jump_label_invalidate_module_init(struct module *mod)
b842f8fa	373	{
d430d3d7 JB	374	struct jump_entry *iter_start = mod->jump_entries;
d430d3d7 JB	375	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
b842f8fa	376	struct jump_entry *iter;
b842f8fa	377
d430d3d7 JB	378	for (iter = iter_start; iter < iter_stop; iter++) {
	379	if (within_module_init(iter->code, mod))
	380	iter->code = 0;
b842f8fa JB	381	}
	382	}
	383
bf5438fc JB	384	static int
	385	jump_label_module_notify(struct notifier_block *self, unsigned long val,
	386	void *data)
	387	{
	388	struct module *mod = data;
	389	int ret = 0;
	390
	391	switch (val) {
	392	case MODULE_STATE_COMING:
91bad2f8	393	jump_label_lock();
d430d3d7	394	ret = jump_label_add_module(mod);
bf5438fc	395	if (ret)
d430d3d7	396	jump_label_del_module(mod);
91bad2f8	397	jump_label_unlock();
bf5438fc JB	398	break;
bf5438fc JB	399	case MODULE_STATE_GOING:
91bad2f8	400	jump_label_lock();
d430d3d7	401	jump_label_del_module(mod);
91bad2f8	402	jump_label_unlock();
bf5438fc	403	break;
b842f8fa	404	case MODULE_STATE_LIVE:
91bad2f8	405	jump_label_lock();
d430d3d7	406	jump_label_invalidate_module_init(mod);
91bad2f8	407	jump_label_unlock();
b842f8fa	408	break;
bf5438fc	409	}
bf5438fc	410
d430d3d7	411	return notifier_from_errno(ret);
bf5438fc JB	412	}
	413
	414	struct notifier_block jump_label_module_nb = {
	415	.notifier_call = jump_label_module_notify,
d430d3d7	416	.priority = 1, /* higher than tracepoints */
bf5438fc JB	417	};
bf5438fc JB	418
d430d3d7	419	static __init int jump_label_init_module(void)
bf5438fc JB	420	{
	421	return register_module_notifier(&jump_label_module_nb);
	422	}
d430d3d7	423	early_initcall(jump_label_init_module);
bf5438fc JB	424
	425	#endif /* CONFIG_MODULES */
	426
d430d3d7 JB	427	/***
	428	* jump_label_text_reserved - check if addr range is reserved
	429	* @start: start text addr
	430	* @end: end text addr
	431	*
	432	* checks if the text addr located between @start and @end
	433	* overlaps with any of the jump label patch addresses. Code
	434	* that wants to modify kernel text should first verify that
	435	* it does not overlap with any of the jump label addresses.
	436	* Caller must hold jump_label_mutex.
	437	*
	438	* returns 1 if there is an overlap, 0 otherwise
	439	*/
	440	int jump_label_text_reserved(void start, void end)
	441	{
	442	int ret = __jump_label_text_reserved(__start___jump_table,
	443	__stop___jump_table, start, end);
	444
	445	if (ret)
	446	return ret;
	447
	448	#ifdef CONFIG_MODULES
	449	ret = __jump_label_mod_text_reserved(start, end);
	450	#endif
	451	return ret;
	452	}
	453
c5905afb	454	static void jump_label_update(struct static_key *key, int enable)
d430d3d7	455	{
c5905afb	456	struct jump_entry *stop = __stop___jump_table;
a1efb01f	457	struct jump_entry *entry = static_key_entries(key);
d430d3d7	458	#ifdef CONFIG_MODULES
bed831f9	459	struct module *mod;
140fe3b1	460
d430d3d7	461	__jump_label_mod_update(key, enable);
140fe3b1	462
bed831f9 PZ	463	preempt_disable();
bed831f9 PZ	464	mod = __module_address((unsigned long)key);
140fe3b1 XG	465	if (mod)
140fe3b1 XG	466	stop = mod->jump_entries + mod->num_jump_entries;
bed831f9	467	preempt_enable();
d430d3d7	468	#endif
140fe3b1 XG	469	/* if there are no users, entry can be NULL */
	470	if (entry)
	471	__jump_label_update(key, entry, stop, enable);
d430d3d7 JB	472	}
d430d3d7 JB	473
bf5438fc	474	#endif