[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
 *
 */
#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);

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_inc_return(&key->enabled) == 1)
		jump_label_update(key);
	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 {
		jump_label_update(key);
	}
	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 inline struct jump_entry *static_key_entries(struct static_key *key)
{
	return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK);
}

static inline bool static_key_type(struct static_key *key)
{
	return (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 & ~1UL);
}

static bool jump_entry_branch(struct jump_entry *entry)
{
	return (unsigned long)entry->key & 1UL;
}

static enum jump_label_type jump_label_type(struct jump_entry *entry)
{
	struct static_key *key = jump_entry_key(entry);
	bool enabled = static_key_enabled(key);
	bool branch = jump_entry_branch(entry);

	/* See the comment in linux/jump_label.h */
	return enabled ^ branch;
}

static void __jump_label_update(struct static_key *key,
				struct jump_entry *entry,
				struct jump_entry *stop)
{
	for (; (entry < stop) && (jump_entry_key(entry) == 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, jump_label_type(entry));
	}
}

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;

		/* rewrite NOPs */
		if (jump_label_type(iter) == JUMP_LABEL_NOP)
			arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);

		iterk = jump_entry_key(iter);
		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

static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
{
	struct static_key *key = jump_entry_key(entry);
	bool type = static_key_type(key);
	bool branch = jump_entry_branch(entry);

	/* See the comment in linux/jump_label.h */
	return type ^ branch;
}

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)
{
	struct static_key_mod *mod;

	for (mod = key->next; mod; mod = mod->next) {
		struct module *m = mod->mod;

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

/***
 * 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++) {
		/* Only write NOPs for arch_branch_static(). */
		if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
			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;

		/* Only update if we've changed from our initial state */
		if (jump_label_type(iter) != jump_label_init_type(iter))
			__jump_label_update(key, iter, iter_stop);
	}

	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)
{
	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);

	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);
}

#ifdef CONFIG_STATIC_KEYS_SELFTEST
static DEFINE_STATIC_KEY_TRUE(sk_true);
static DEFINE_STATIC_KEY_FALSE(sk_false);

static __init int jump_label_test(void)
{
	int i;

	for (i = 0; i < 2; i++) {
		WARN_ON(static_key_enabled(&sk_true.key) != true);
		WARN_ON(static_key_enabled(&sk_false.key) != false);

		WARN_ON(!static_branch_likely(&sk_true));
		WARN_ON(!static_branch_unlikely(&sk_true));
		WARN_ON(static_branch_likely(&sk_false));
		WARN_ON(static_branch_unlikely(&sk_false));

		static_branch_disable(&sk_true);
		static_branch_enable(&sk_false);

		WARN_ON(static_key_enabled(&sk_true.key) == true);
		WARN_ON(static_key_enabled(&sk_false.key) == false);

		WARN_ON(static_branch_likely(&sk_true));
		WARN_ON(static_branch_unlikely(&sk_true));
		WARN_ON(!static_branch_likely(&sk_false));
		WARN_ON(!static_branch_unlikely(&sk_false));

		static_branch_enable(&sk_true);
		static_branch_disable(&sk_false);
	}

	return 0;
}
late_initcall(jump_label_test);
#endif /* STATIC_KEYS_SELFTEST */

#endif /* HAVE_JUMP_LABEL */
Commit	Line	Data
bf5438fc JB	1	/*
	2	* jump label support
	3	*
	4	* Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
90eec103	5	* Copyright (C) 2011 Peter Zijlstra
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
706249c2	57	static void jump_label_update(struct static_key *key);
a1efb01f	58
c5905afb	59	void static_key_slow_inc(struct static_key *key)
bf5438fc	60	{
c4b2c0c5	61	STATIC_KEY_CHECK_USE();
d430d3d7 JB	62	if (atomic_inc_not_zero(&key->enabled))
d430d3d7 JB	63	return;
bf5438fc	64
d430d3d7	65	jump_label_lock();
706249c2 PZ	66	if (atomic_inc_return(&key->enabled) == 1)
706249c2 PZ	67	jump_label_update(key);
d430d3d7	68	jump_label_unlock();
bf5438fc	69	}
c5905afb	70	EXPORT_SYMBOL_GPL(static_key_slow_inc);
bf5438fc	71
c5905afb	72	static void __static_key_slow_dec(struct static_key *key,
b2029520	73	unsigned long rate_limit, struct delayed_work *work)
bf5438fc	74	{
fadf0464 JB	75	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
	76	WARN(atomic_read(&key->enabled) < 0,
	77	"jump label: negative count!\n");
d430d3d7	78	return;
fadf0464	79	}
bf5438fc	80
b2029520 GN	81	if (rate_limit) {
	82	atomic_inc(&key->enabled);
	83	schedule_delayed_work(work, rate_limit);
c5905afb	84	} else {
706249c2	85	jump_label_update(key);
c5905afb	86	}
91bad2f8	87	jump_label_unlock();
bf5438fc JB	88	}
bf5438fc JB	89
b2029520 GN	90	static void jump_label_update_timeout(struct work_struct *work)
b2029520 GN	91	{
c5905afb IM	92	struct static_key_deferred *key =
	93	container_of(work, struct static_key_deferred, work.work);
	94	__static_key_slow_dec(&key->key, 0, NULL);
b2029520 GN	95	}
b2029520 GN	96
c5905afb	97	void static_key_slow_dec(struct static_key *key)
b2029520	98	{
c4b2c0c5	99	STATIC_KEY_CHECK_USE();
c5905afb	100	__static_key_slow_dec(key, 0, NULL);
b2029520	101	}
c5905afb	102	EXPORT_SYMBOL_GPL(static_key_slow_dec);
b2029520	103
c5905afb	104	void static_key_slow_dec_deferred(struct static_key_deferred *key)
b2029520	105	{
c4b2c0c5	106	STATIC_KEY_CHECK_USE();
c5905afb	107	__static_key_slow_dec(&key->key, key->timeout, &key->work);
b2029520	108	}
c5905afb	109	EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
b2029520	110
c5905afb	111	void jump_label_rate_limit(struct static_key_deferred *key,
b2029520 GN	112	unsigned long rl)
b2029520 GN	113	{
c4b2c0c5	114	STATIC_KEY_CHECK_USE();
b2029520 GN	115	key->timeout = rl;
	116	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
	117	}
a181dc14	118	EXPORT_SYMBOL_GPL(jump_label_rate_limit);
b2029520	119
4c3ef6d7 JB	120	static int addr_conflict(struct jump_entry entry, void start, void *end)
	121	{
	122	if (entry->code <= (unsigned long)end &&
	123	entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
	124	return 1;
	125
	126	return 0;
	127	}
	128
d430d3d7 JB	129	static int __jump_label_text_reserved(struct jump_entry *iter_start,
d430d3d7 JB	130	struct jump_entry iter_stop, void start, void *end)
4c3ef6d7	131	{
4c3ef6d7	132	struct jump_entry *iter;
4c3ef6d7	133
4c3ef6d7 JB	134	iter = iter_start;
4c3ef6d7 JB	135	while (iter < iter_stop) {
d430d3d7 JB	136	if (addr_conflict(iter, start, end))
d430d3d7 JB	137	return 1;
4c3ef6d7 JB	138	iter++;
	139	}
	140
d430d3d7 JB	141	return 0;
	142	}
	143
706249c2	144	/*
20284aa7 JF	145	* Update code which is definitely not currently executing.
	146	* Architectures which need heavyweight synchronization to modify
	147	* running code can override this to make the non-live update case
	148	* cheaper.
	149	*/
9cdbe1cb	150	void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
20284aa7 JF	151	enum jump_label_type type)
20284aa7 JF	152	{
706249c2	153	arch_jump_label_transform(entry, type);
20284aa7 JF	154	}
20284aa7 JF	155
706249c2	156	static inline struct jump_entry static_key_entries(struct static_key key)
d430d3d7	157	{
706249c2	158	return (struct jump_entry *)((unsigned long)key->entries & ~JUMP_TYPE_MASK);
4c3ef6d7 JB	159	}
4c3ef6d7 JB	160
706249c2	161	static inline bool static_key_type(struct static_key *key)
c5905afb	162	{
706249c2	163	return (unsigned long)key->entries & JUMP_TYPE_MASK;
a1efb01f	164	}
c5905afb	165
7dcfd915 PZ	166	static inline struct static_key jump_entry_key(struct jump_entry entry)
7dcfd915 PZ	167	{
11276d53 PZ	168	return (struct static_key *)((unsigned long)entry->key & ~1UL);
	169	}
	170
	171	static bool jump_entry_branch(struct jump_entry *entry)
	172	{
	173	return (unsigned long)entry->key & 1UL;
7dcfd915 PZ	174	}
7dcfd915 PZ	175
706249c2	176	static enum jump_label_type jump_label_type(struct jump_entry *entry)
a1efb01f	177	{
706249c2	178	struct static_key *key = jump_entry_key(entry);
a1efb01f	179	bool enabled = static_key_enabled(key);
11276d53	180	bool branch = jump_entry_branch(entry);
c5905afb	181
11276d53 PZ	182	/* See the comment in linux/jump_label.h */
11276d53 PZ	183	return enabled ^ branch;
c5905afb IM	184	}
c5905afb IM	185
706249c2 PZ	186	static void __jump_label_update(struct static_key *key,
	187	struct jump_entry *entry,
	188	struct jump_entry *stop)
	189	{
	190	for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
	191	/*
	192	* entry->code set to 0 invalidates module init text sections
	193	* kernel_text_address() verifies we are not in core kernel
	194	* init code, see jump_label_invalidate_module_init().
	195	*/
	196	if (entry->code && kernel_text_address(entry->code))
	197	arch_jump_label_transform(entry, jump_label_type(entry));
	198	}
	199	}
	200
97ce2c88	201	void __init jump_label_init(void)
bf5438fc	202	{
bf5438fc JB	203	struct jump_entry *iter_start = __start___jump_table;
bf5438fc JB	204	struct jump_entry *iter_stop = __stop___jump_table;
c5905afb	205	struct static_key *key = NULL;
bf5438fc JB	206	struct jump_entry *iter;
bf5438fc JB	207
91bad2f8	208	jump_label_lock();
d430d3d7 JB	209	jump_label_sort_entries(iter_start, iter_stop);
	210
	211	for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb	212	struct static_key *iterk;
37348804	213
11276d53 PZ	214	/* rewrite NOPs */
	215	if (jump_label_type(iter) == JUMP_LABEL_NOP)
	216	arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
	217
7dcfd915	218	iterk = jump_entry_key(iter);
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
11276d53 PZ	237	static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
	238	{
	239	struct static_key *key = jump_entry_key(entry);
	240	bool type = static_key_type(key);
	241	bool branch = jump_entry_branch(entry);
	242
	243	/* See the comment in linux/jump_label.h */
	244	return type ^ branch;
	245	}
	246
c5905afb IM	247	struct static_key_mod {
c5905afb IM	248	struct static_key_mod *next;
d430d3d7 JB	249	struct jump_entry *entries;
	250	struct module *mod;
	251	};
	252
	253	static int __jump_label_mod_text_reserved(void start, void end)
	254	{
	255	struct module *mod;
	256
	257	mod = __module_text_address((unsigned long)start);
	258	if (!mod)
	259	return 0;
	260
	261	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
	262
	263	return __jump_label_text_reserved(mod->jump_entries,
	264	mod->jump_entries + mod->num_jump_entries,
	265	start, end);
	266	}
	267
706249c2	268	static void __jump_label_mod_update(struct static_key *key)
d430d3d7	269	{
706249c2	270	struct static_key_mod *mod;
d430d3d7	271
706249c2	272	for (mod = key->next; mod; mod = mod->next) {
7cbc5b8d JO	273	struct module *m = mod->mod;
	274
	275	__jump_label_update(key, mod->entries,
706249c2	276	m->jump_entries + m->num_jump_entries);
d430d3d7 JB	277	}
	278	}
	279
	280	/***
	281	* apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
	282	* @mod: module to patch
	283	*
	284	* Allow for run-time selection of the optimal nops. Before the module
	285	* loads patch these with arch_get_jump_label_nop(), which is specified by
	286	* the arch specific jump label code.
	287	*/
	288	void jump_label_apply_nops(struct module *mod)
bf5438fc	289	{
d430d3d7 JB	290	struct jump_entry *iter_start = mod->jump_entries;
	291	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	292	struct jump_entry *iter;
	293
	294	/* if the module doesn't have jump label entries, just return */
	295	if (iter_start == iter_stop)
	296	return;
	297
11276d53 PZ	298	for (iter = iter_start; iter < iter_stop; iter++) {
	299	/* Only write NOPs for arch_branch_static(). */
	300	if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
	301	arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
	302	}
bf5438fc JB	303	}
bf5438fc JB	304
d430d3d7	305	static int jump_label_add_module(struct module *mod)
bf5438fc	306	{
d430d3d7 JB	307	struct jump_entry *iter_start = mod->jump_entries;
	308	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	309	struct jump_entry *iter;
c5905afb IM	310	struct static_key *key = NULL;
c5905afb IM	311	struct static_key_mod *jlm;
bf5438fc JB	312
bf5438fc JB	313	/* if the module doesn't have jump label entries, just return */
d430d3d7	314	if (iter_start == iter_stop)
bf5438fc JB	315	return 0;
bf5438fc JB	316
d430d3d7 JB	317	jump_label_sort_entries(iter_start, iter_stop);
	318
	319	for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb	320	struct static_key *iterk;
d430d3d7	321
7dcfd915	322	iterk = jump_entry_key(iter);
c5905afb IM	323	if (iterk == key)
c5905afb IM	324	continue;
d430d3d7	325
c5905afb	326	key = iterk;
bed831f9	327	if (within_module(iter->key, mod)) {
c5905afb IM	328	/*
	329	* Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
	330	*/
	331	((unsigned long )&key->entries) += (unsigned long)iter;
d430d3d7 JB	332	key->next = NULL;
d430d3d7 JB	333	continue;
bf5438fc	334	}
c5905afb	335	jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
d430d3d7 JB	336	if (!jlm)
d430d3d7 JB	337	return -ENOMEM;
d430d3d7 JB	338	jlm->mod = mod;
	339	jlm->entries = iter;
	340	jlm->next = key->next;
	341	key->next = jlm;
	342
11276d53 PZ	343	/* Only update if we've changed from our initial state */
11276d53 PZ	344	if (jump_label_type(iter) != jump_label_init_type(iter))
706249c2	345	__jump_label_update(key, iter, iter_stop);
bf5438fc	346	}
d430d3d7	347
bf5438fc JB	348	return 0;
	349	}
	350
d430d3d7	351	static void jump_label_del_module(struct module *mod)
bf5438fc	352	{
d430d3d7 JB	353	struct jump_entry *iter_start = mod->jump_entries;
	354	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	355	struct jump_entry *iter;
c5905afb IM	356	struct static_key *key = NULL;
c5905afb IM	357	struct static_key_mod jlm, *prev;
bf5438fc	358
d430d3d7	359	for (iter = iter_start; iter < iter_stop; iter++) {
7dcfd915	360	if (jump_entry_key(iter) == key)
d430d3d7 JB	361	continue;
d430d3d7 JB	362
7dcfd915	363	key = jump_entry_key(iter);
d430d3d7	364
bed831f9	365	if (within_module(iter->key, mod))
d430d3d7 JB	366	continue;
	367
	368	prev = &key->next;
	369	jlm = key->next;
bf5438fc	370
d430d3d7 JB	371	while (jlm && jlm->mod != mod) {
	372	prev = &jlm->next;
	373	jlm = jlm->next;
	374	}
	375
	376	if (jlm) {
	377	*prev = jlm->next;
	378	kfree(jlm);
bf5438fc JB	379	}
	380	}
	381	}
	382
d430d3d7	383	static void jump_label_invalidate_module_init(struct module *mod)
b842f8fa	384	{
d430d3d7 JB	385	struct jump_entry *iter_start = mod->jump_entries;
d430d3d7 JB	386	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
b842f8fa	387	struct jump_entry *iter;
b842f8fa	388
d430d3d7 JB	389	for (iter = iter_start; iter < iter_stop; iter++) {
	390	if (within_module_init(iter->code, mod))
	391	iter->code = 0;
b842f8fa JB	392	}
	393	}
	394
bf5438fc JB	395	static int
	396	jump_label_module_notify(struct notifier_block *self, unsigned long val,
	397	void *data)
	398	{
	399	struct module *mod = data;
	400	int ret = 0;
	401
	402	switch (val) {
	403	case MODULE_STATE_COMING:
91bad2f8	404	jump_label_lock();
d430d3d7	405	ret = jump_label_add_module(mod);
bf5438fc	406	if (ret)
d430d3d7	407	jump_label_del_module(mod);
91bad2f8	408	jump_label_unlock();
bf5438fc JB	409	break;
bf5438fc JB	410	case MODULE_STATE_GOING:
91bad2f8	411	jump_label_lock();
d430d3d7	412	jump_label_del_module(mod);
91bad2f8	413	jump_label_unlock();
bf5438fc	414	break;
b842f8fa	415	case MODULE_STATE_LIVE:
91bad2f8	416	jump_label_lock();
d430d3d7	417	jump_label_invalidate_module_init(mod);
91bad2f8	418	jump_label_unlock();
b842f8fa	419	break;
bf5438fc	420	}
bf5438fc	421
d430d3d7	422	return notifier_from_errno(ret);
bf5438fc JB	423	}
	424
	425	struct notifier_block jump_label_module_nb = {
	426	.notifier_call = jump_label_module_notify,
d430d3d7	427	.priority = 1, /* higher than tracepoints */
bf5438fc JB	428	};
bf5438fc JB	429
d430d3d7	430	static __init int jump_label_init_module(void)
bf5438fc JB	431	{
	432	return register_module_notifier(&jump_label_module_nb);
	433	}
d430d3d7	434	early_initcall(jump_label_init_module);
bf5438fc JB	435
	436	#endif /* CONFIG_MODULES */
	437
d430d3d7 JB	438	/***
	439	* jump_label_text_reserved - check if addr range is reserved
	440	* @start: start text addr
	441	* @end: end text addr
	442	*
	443	* checks if the text addr located between @start and @end
	444	* overlaps with any of the jump label patch addresses. Code
	445	* that wants to modify kernel text should first verify that
	446	* it does not overlap with any of the jump label addresses.
	447	* Caller must hold jump_label_mutex.
	448	*
	449	* returns 1 if there is an overlap, 0 otherwise
	450	*/
	451	int jump_label_text_reserved(void start, void end)
	452	{
	453	int ret = __jump_label_text_reserved(__start___jump_table,
	454	__stop___jump_table, start, end);
	455
	456	if (ret)
	457	return ret;
	458
	459	#ifdef CONFIG_MODULES
	460	ret = __jump_label_mod_text_reserved(start, end);
	461	#endif
	462	return ret;
	463	}
	464
706249c2	465	static void jump_label_update(struct static_key *key)
d430d3d7	466	{
c5905afb	467	struct jump_entry *stop = __stop___jump_table;
a1efb01f	468	struct jump_entry *entry = static_key_entries(key);
d430d3d7	469	#ifdef CONFIG_MODULES
bed831f9	470	struct module *mod;
140fe3b1	471
706249c2	472	__jump_label_mod_update(key);
140fe3b1	473
bed831f9 PZ	474	preempt_disable();
bed831f9 PZ	475	mod = __module_address((unsigned long)key);
140fe3b1 XG	476	if (mod)
140fe3b1 XG	477	stop = mod->jump_entries + mod->num_jump_entries;
bed831f9	478	preempt_enable();
d430d3d7	479	#endif
140fe3b1 XG	480	/* if there are no users, entry can be NULL */
140fe3b1 XG	481	if (entry)
706249c2	482	__jump_label_update(key, entry, stop);
d430d3d7 JB	483	}
d430d3d7 JB	484
1987c947 PZ	485	#ifdef CONFIG_STATIC_KEYS_SELFTEST
	486	static DEFINE_STATIC_KEY_TRUE(sk_true);
	487	static DEFINE_STATIC_KEY_FALSE(sk_false);
	488
	489	static __init int jump_label_test(void)
	490	{
	491	int i;
	492
	493	for (i = 0; i < 2; i++) {
	494	WARN_ON(static_key_enabled(&sk_true.key) != true);
	495	WARN_ON(static_key_enabled(&sk_false.key) != false);
	496
	497	WARN_ON(!static_branch_likely(&sk_true));
	498	WARN_ON(!static_branch_unlikely(&sk_true));
	499	WARN_ON(static_branch_likely(&sk_false));
	500	WARN_ON(static_branch_unlikely(&sk_false));
	501
	502	static_branch_disable(&sk_true);
	503	static_branch_enable(&sk_false);
	504
	505	WARN_ON(static_key_enabled(&sk_true.key) == true);
	506	WARN_ON(static_key_enabled(&sk_false.key) == false);
	507
	508	WARN_ON(static_branch_likely(&sk_true));
	509	WARN_ON(static_branch_unlikely(&sk_true));
	510	WARN_ON(!static_branch_likely(&sk_false));
	511	WARN_ON(!static_branch_unlikely(&sk_false));
	512
	513	static_branch_enable(&sk_true);
	514	static_branch_disable(&sk_false);
	515	}
	516
	517	return 0;
	518	}
	519	late_initcall(jump_label_test);
	520	#endif /* STATIC_KEYS_SELFTEST */
	521
	522	#endif /* HAVE_JUMP_LABEL */