[linux.git] / kernel / jump_label.c

/*
 * jump label support
 *
 * Copyright (C) 2009 Jason Baron <[email protected]>
 * Copyright (C) 2011 Peter Zijlstra <[email protected]>
 *
 */
#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>

#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)
{
	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_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_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)
{
	key->timeout = rl;
	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
}

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
	}
	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
bf5438fc JB	1	/*
	2	* jump label support
	3	*
	4	* Copyright (C) 2009 Jason Baron <[email protected]>
d430d3d7	5	* Copyright (C) 2011 Peter Zijlstra <[email protected]>
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>
bf5438fc JB	16
	17	#ifdef HAVE_JUMP_LABEL
	18
bf5438fc JB	19	/* mutex to protect coming/going of the the jump_label table */
	20	static DEFINE_MUTEX(jump_label_mutex);
	21
91bad2f8 JB	22	void jump_label_lock(void)
	23	{
	24	mutex_lock(&jump_label_mutex);
	25	}
	26
	27	void jump_label_unlock(void)
	28	{
	29	mutex_unlock(&jump_label_mutex);
	30	}
	31
bf5438fc JB	32	static int jump_label_cmp(const void a, const void b)
	33	{
	34	const struct jump_entry *jea = a;
	35	const struct jump_entry *jeb = b;
	36
	37	if (jea->key < jeb->key)
	38	return -1;
	39
	40	if (jea->key > jeb->key)
	41	return 1;
	42
	43	return 0;
	44	}
	45
	46	static void
d430d3d7	47	jump_label_sort_entries(struct jump_entry start, struct jump_entry stop)
bf5438fc JB	48	{
	49	unsigned long size;
	50
	51	size = (((unsigned long)stop - (unsigned long)start)
	52	/ sizeof(struct jump_entry));
	53	sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
	54	}
	55
c5905afb	56	static void jump_label_update(struct static_key *key, int enable);
bf5438fc	57
c5905afb	58	void static_key_slow_inc(struct static_key *key)
bf5438fc	59	{
d430d3d7 JB	60	if (atomic_inc_not_zero(&key->enabled))
d430d3d7 JB	61	return;
bf5438fc	62
d430d3d7	63	jump_label_lock();
c5905afb IM	64	if (atomic_read(&key->enabled) == 0) {
	65	if (!jump_label_get_branch_default(key))
	66	jump_label_update(key, JUMP_LABEL_ENABLE);
	67	else
	68	jump_label_update(key, JUMP_LABEL_DISABLE);
	69	}
bbbf7af4	70	atomic_inc(&key->enabled);
d430d3d7	71	jump_label_unlock();
bf5438fc	72	}
c5905afb	73	EXPORT_SYMBOL_GPL(static_key_slow_inc);
bf5438fc	74
c5905afb	75	static void __static_key_slow_dec(struct static_key *key,
b2029520	76	unsigned long rate_limit, struct delayed_work *work)
bf5438fc	77	{
fadf0464 JB	78	if (!atomic_dec_and_mutex_lock(&key->enabled, &jump_label_mutex)) {
	79	WARN(atomic_read(&key->enabled) < 0,
	80	"jump label: negative count!\n");
d430d3d7	81	return;
fadf0464	82	}
bf5438fc	83
b2029520 GN	84	if (rate_limit) {
	85	atomic_inc(&key->enabled);
	86	schedule_delayed_work(work, rate_limit);
c5905afb IM	87	} else {
	88	if (!jump_label_get_branch_default(key))
	89	jump_label_update(key, JUMP_LABEL_DISABLE);
	90	else
	91	jump_label_update(key, JUMP_LABEL_ENABLE);
	92	}
91bad2f8	93	jump_label_unlock();
bf5438fc JB	94	}
bf5438fc JB	95
b2029520 GN	96	static void jump_label_update_timeout(struct work_struct *work)
b2029520 GN	97	{
c5905afb IM	98	struct static_key_deferred *key =
	99	container_of(work, struct static_key_deferred, work.work);
	100	__static_key_slow_dec(&key->key, 0, NULL);
b2029520 GN	101	}
b2029520 GN	102
c5905afb	103	void static_key_slow_dec(struct static_key *key)
b2029520	104	{
c5905afb	105	__static_key_slow_dec(key, 0, NULL);
b2029520	106	}
c5905afb	107	EXPORT_SYMBOL_GPL(static_key_slow_dec);
b2029520	108
c5905afb	109	void static_key_slow_dec_deferred(struct static_key_deferred *key)
b2029520	110	{
c5905afb	111	__static_key_slow_dec(&key->key, key->timeout, &key->work);
b2029520	112	}
c5905afb	113	EXPORT_SYMBOL_GPL(static_key_slow_dec_deferred);
b2029520	114
c5905afb	115	void jump_label_rate_limit(struct static_key_deferred *key,
b2029520 GN	116	unsigned long rl)
	117	{
	118	key->timeout = rl;
	119	INIT_DELAYED_WORK(&key->work, jump_label_update_timeout);
	120	}
	121
4c3ef6d7 JB	122	static int addr_conflict(struct jump_entry entry, void start, void *end)
	123	{
	124	if (entry->code <= (unsigned long)end &&
	125	entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
	126	return 1;
	127
	128	return 0;
	129	}
	130
d430d3d7 JB	131	static int __jump_label_text_reserved(struct jump_entry *iter_start,
d430d3d7 JB	132	struct jump_entry iter_stop, void start, void *end)
4c3ef6d7	133	{
4c3ef6d7	134	struct jump_entry *iter;
4c3ef6d7	135
4c3ef6d7 JB	136	iter = iter_start;
4c3ef6d7 JB	137	while (iter < iter_stop) {
d430d3d7 JB	138	if (addr_conflict(iter, start, end))
d430d3d7 JB	139	return 1;
4c3ef6d7 JB	140	iter++;
	141	}
	142
d430d3d7 JB	143	return 0;
	144	}
	145
20284aa7 JF	146	/*
	147	* Update code which is definitely not currently executing.
	148	* Architectures which need heavyweight synchronization to modify
	149	* running code can override this to make the non-live update case
	150	* cheaper.
	151	*/
9cdbe1cb	152	void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
20284aa7 JF	153	enum jump_label_type type)
	154	{
	155	arch_jump_label_transform(entry, type);
	156	}
	157
c5905afb	158	static void __jump_label_update(struct static_key *key,
7cbc5b8d JO	159	struct jump_entry *entry,
7cbc5b8d JO	160	struct jump_entry *stop, int enable)
d430d3d7	161	{
7cbc5b8d JO	162	for (; (entry < stop) &&
	163	(entry->key == (jump_label_t)(unsigned long)key);
	164	entry++) {
d430d3d7 JB	165	/*
	166	* entry->code set to 0 invalidates module init text sections
	167	* kernel_text_address() verifies we are not in core kernel
	168	* init code, see jump_label_invalidate_module_init().
	169	*/
	170	if (entry->code && kernel_text_address(entry->code))
	171	arch_jump_label_transform(entry, enable);
	172	}
4c3ef6d7 JB	173	}
4c3ef6d7 JB	174
c5905afb IM	175	static enum jump_label_type jump_label_type(struct static_key *key)
	176	{
	177	bool true_branch = jump_label_get_branch_default(key);
	178	bool state = static_key_enabled(key);
	179
	180	if ((!true_branch && state) \|\| (true_branch && !state))
	181	return JUMP_LABEL_ENABLE;
	182
	183	return JUMP_LABEL_DISABLE;
	184	}
	185
97ce2c88	186	void __init jump_label_init(void)
bf5438fc	187	{
bf5438fc JB	188	struct jump_entry *iter_start = __start___jump_table;
bf5438fc JB	189	struct jump_entry *iter_stop = __stop___jump_table;
c5905afb	190	struct static_key *key = NULL;
bf5438fc JB	191	struct jump_entry *iter;
bf5438fc JB	192
91bad2f8	193	jump_label_lock();
d430d3d7 JB	194	jump_label_sort_entries(iter_start, iter_stop);
	195
	196	for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb	197	struct static_key *iterk;
37348804	198
c5905afb IM	199	iterk = (struct static_key *)(unsigned long)iter->key;
c5905afb IM	200	arch_jump_label_transform_static(iter, jump_label_type(iterk));
37348804	201	if (iterk == key)
d430d3d7 JB	202	continue;
d430d3d7 JB	203
37348804	204	key = iterk;
c5905afb IM	205	/*
	206	* Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
	207	*/
	208	((unsigned long )&key->entries) += (unsigned long)iter;
d430d3d7 JB	209	#ifdef CONFIG_MODULES
	210	key->next = NULL;
	211	#endif
bf5438fc	212	}
91bad2f8	213	jump_label_unlock();
bf5438fc	214	}
bf5438fc JB	215
	216	#ifdef CONFIG_MODULES
	217
c5905afb IM	218	struct static_key_mod {
c5905afb IM	219	struct static_key_mod *next;
d430d3d7 JB	220	struct jump_entry *entries;
	221	struct module *mod;
	222	};
	223
	224	static int __jump_label_mod_text_reserved(void start, void end)
	225	{
	226	struct module *mod;
	227
	228	mod = __module_text_address((unsigned long)start);
	229	if (!mod)
	230	return 0;
	231
	232	WARN_ON_ONCE(__module_text_address((unsigned long)end) != mod);
	233
	234	return __jump_label_text_reserved(mod->jump_entries,
	235	mod->jump_entries + mod->num_jump_entries,
	236	start, end);
	237	}
	238
c5905afb	239	static void __jump_label_mod_update(struct static_key *key, int enable)
d430d3d7	240	{
c5905afb	241	struct static_key_mod *mod = key->next;
d430d3d7 JB	242
d430d3d7 JB	243	while (mod) {
7cbc5b8d JO	244	struct module *m = mod->mod;
	245
	246	__jump_label_update(key, mod->entries,
	247	m->jump_entries + m->num_jump_entries,
	248	enable);
d430d3d7 JB	249	mod = mod->next;
	250	}
	251	}
	252
	253	/***
	254	* apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
	255	* @mod: module to patch
	256	*
	257	* Allow for run-time selection of the optimal nops. Before the module
	258	* loads patch these with arch_get_jump_label_nop(), which is specified by
	259	* the arch specific jump label code.
	260	*/
	261	void jump_label_apply_nops(struct module *mod)
bf5438fc	262	{
d430d3d7 JB	263	struct jump_entry *iter_start = mod->jump_entries;
	264	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	265	struct jump_entry *iter;
	266
	267	/* if the module doesn't have jump label entries, just return */
	268	if (iter_start == iter_stop)
	269	return;
	270
ac99b862	271	for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb	272	arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
ac99b862	273	}
bf5438fc JB	274	}
bf5438fc JB	275
d430d3d7	276	static int jump_label_add_module(struct module *mod)
bf5438fc	277	{
d430d3d7 JB	278	struct jump_entry *iter_start = mod->jump_entries;
	279	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	280	struct jump_entry *iter;
c5905afb IM	281	struct static_key *key = NULL;
c5905afb IM	282	struct static_key_mod *jlm;
bf5438fc JB	283
bf5438fc JB	284	/* if the module doesn't have jump label entries, just return */
d430d3d7	285	if (iter_start == iter_stop)
bf5438fc JB	286	return 0;
bf5438fc JB	287
d430d3d7 JB	288	jump_label_sort_entries(iter_start, iter_stop);
	289
	290	for (iter = iter_start; iter < iter_stop; iter++) {
c5905afb	291	struct static_key *iterk;
d430d3d7	292
c5905afb IM	293	iterk = (struct static_key *)(unsigned long)iter->key;
	294	if (iterk == key)
	295	continue;
d430d3d7	296
c5905afb	297	key = iterk;
d430d3d7	298	if (__module_address(iter->key) == mod) {
c5905afb IM	299	/*
	300	* Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
	301	*/
	302	((unsigned long )&key->entries) += (unsigned long)iter;
d430d3d7 JB	303	key->next = NULL;
d430d3d7 JB	304	continue;
bf5438fc	305	}
c5905afb	306	jlm = kzalloc(sizeof(struct static_key_mod), GFP_KERNEL);
d430d3d7 JB	307	if (!jlm)
d430d3d7 JB	308	return -ENOMEM;
d430d3d7 JB	309	jlm->mod = mod;
	310	jlm->entries = iter;
	311	jlm->next = key->next;
	312	key->next = jlm;
	313
c5905afb	314	if (jump_label_type(key) == JUMP_LABEL_ENABLE)
ac99b862	315	__jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE);
bf5438fc	316	}
d430d3d7	317
bf5438fc JB	318	return 0;
	319	}
	320
d430d3d7	321	static void jump_label_del_module(struct module *mod)
bf5438fc	322	{
d430d3d7 JB	323	struct jump_entry *iter_start = mod->jump_entries;
	324	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
	325	struct jump_entry *iter;
c5905afb IM	326	struct static_key *key = NULL;
c5905afb IM	327	struct static_key_mod jlm, *prev;
bf5438fc	328
d430d3d7 JB	329	for (iter = iter_start; iter < iter_stop; iter++) {
	330	if (iter->key == (jump_label_t)(unsigned long)key)
	331	continue;
	332
c5905afb	333	key = (struct static_key *)(unsigned long)iter->key;
d430d3d7 JB	334
	335	if (__module_address(iter->key) == mod)
	336	continue;
	337
	338	prev = &key->next;
	339	jlm = key->next;
bf5438fc	340
d430d3d7 JB	341	while (jlm && jlm->mod != mod) {
	342	prev = &jlm->next;
	343	jlm = jlm->next;
	344	}
	345
	346	if (jlm) {
	347	*prev = jlm->next;
	348	kfree(jlm);
bf5438fc JB	349	}
	350	}
	351	}
	352
d430d3d7	353	static void jump_label_invalidate_module_init(struct module *mod)
b842f8fa	354	{
d430d3d7 JB	355	struct jump_entry *iter_start = mod->jump_entries;
d430d3d7 JB	356	struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
b842f8fa	357	struct jump_entry *iter;
b842f8fa	358
d430d3d7 JB	359	for (iter = iter_start; iter < iter_stop; iter++) {
	360	if (within_module_init(iter->code, mod))
	361	iter->code = 0;
b842f8fa JB	362	}
	363	}
	364
bf5438fc JB	365	static int
	366	jump_label_module_notify(struct notifier_block *self, unsigned long val,
	367	void *data)
	368	{
	369	struct module *mod = data;
	370	int ret = 0;
	371
	372	switch (val) {
	373	case MODULE_STATE_COMING:
91bad2f8	374	jump_label_lock();
d430d3d7	375	ret = jump_label_add_module(mod);
bf5438fc	376	if (ret)
d430d3d7	377	jump_label_del_module(mod);
91bad2f8	378	jump_label_unlock();
bf5438fc JB	379	break;
bf5438fc JB	380	case MODULE_STATE_GOING:
91bad2f8	381	jump_label_lock();
d430d3d7	382	jump_label_del_module(mod);
91bad2f8	383	jump_label_unlock();
bf5438fc	384	break;
b842f8fa	385	case MODULE_STATE_LIVE:
91bad2f8	386	jump_label_lock();
d430d3d7	387	jump_label_invalidate_module_init(mod);
91bad2f8	388	jump_label_unlock();
b842f8fa	389	break;
bf5438fc	390	}
bf5438fc	391
d430d3d7	392	return notifier_from_errno(ret);
bf5438fc JB	393	}
	394
	395	struct notifier_block jump_label_module_nb = {
	396	.notifier_call = jump_label_module_notify,
d430d3d7	397	.priority = 1, /* higher than tracepoints */
bf5438fc JB	398	};
bf5438fc JB	399
d430d3d7	400	static __init int jump_label_init_module(void)
bf5438fc JB	401	{
	402	return register_module_notifier(&jump_label_module_nb);
	403	}
d430d3d7	404	early_initcall(jump_label_init_module);
bf5438fc JB	405
	406	#endif /* CONFIG_MODULES */
	407
d430d3d7 JB	408	/***
	409	* jump_label_text_reserved - check if addr range is reserved
	410	* @start: start text addr
	411	* @end: end text addr
	412	*
	413	* checks if the text addr located between @start and @end
	414	* overlaps with any of the jump label patch addresses. Code
	415	* that wants to modify kernel text should first verify that
	416	* it does not overlap with any of the jump label addresses.
	417	* Caller must hold jump_label_mutex.
	418	*
	419	* returns 1 if there is an overlap, 0 otherwise
	420	*/
	421	int jump_label_text_reserved(void start, void end)
	422	{
	423	int ret = __jump_label_text_reserved(__start___jump_table,
	424	__stop___jump_table, start, end);
	425
	426	if (ret)
	427	return ret;
	428
	429	#ifdef CONFIG_MODULES
	430	ret = __jump_label_mod_text_reserved(start, end);
	431	#endif
	432	return ret;
	433	}
	434
c5905afb	435	static void jump_label_update(struct static_key *key, int enable)
d430d3d7	436	{
c5905afb IM	437	struct jump_entry *stop = __stop___jump_table;
c5905afb IM	438	struct jump_entry *entry = jump_label_get_entries(key);
d430d3d7 JB	439
d430d3d7 JB	440	#ifdef CONFIG_MODULES
a746e3cc	441	struct module *mod = __module_address((unsigned long)key);
140fe3b1	442
d430d3d7	443	__jump_label_mod_update(key, enable);
140fe3b1 XG	444
	445	if (mod)
	446	stop = mod->jump_entries + mod->num_jump_entries;
d430d3d7	447	#endif
140fe3b1 XG	448	/* if there are no users, entry can be NULL */
	449	if (entry)
	450	__jump_label_update(key, entry, stop, enable);
d430d3d7 JB	451	}
d430d3d7 JB	452
bf5438fc	453	#endif