[linux-block.git] / include / linux / jump_label.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_JUMP_LABEL_H
#define _LINUX_JUMP_LABEL_H

/*
 * Jump label support
 *
 * Copyright (C) 2009-2012 Jason Baron <jbaron@redhat.com>
 * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra
 *
 * DEPRECATED API:
 *
 * The use of 'struct static_key' directly, is now DEPRECATED. In addition
 * static_key_{true,false}() is also DEPRECATED. IE DO NOT use the following:
 *
 * struct static_key false = STATIC_KEY_INIT_FALSE;
 * struct static_key true = STATIC_KEY_INIT_TRUE;
 * static_key_true()
 * static_key_false()
 *
 * The updated API replacements are:
 *
 * DEFINE_STATIC_KEY_TRUE(key);
 * DEFINE_STATIC_KEY_FALSE(key);
 * DEFINE_STATIC_KEY_ARRAY_TRUE(keys, count);
 * DEFINE_STATIC_KEY_ARRAY_FALSE(keys, count);
 * static_branch_likely()
 * static_branch_unlikely()
 *
 * Jump labels provide an interface to generate dynamic branches using
 * self-modifying code. Assuming toolchain and architecture support, if we
 * define a "key" that is initially false via "DEFINE_STATIC_KEY_FALSE(key)",
 * an "if (static_branch_unlikely(&key))" statement is an unconditional branch
 * (which defaults to false - and the true block is placed out of line).
 * Similarly, we can define an initially true key via
 * "DEFINE_STATIC_KEY_TRUE(key)", and use it in the same
 * "if (static_branch_unlikely(&key))", in which case we will generate an
 * unconditional branch to the out-of-line true branch. Keys that are
 * initially true or false can be using in both static_branch_unlikely()
 * and static_branch_likely() statements.
 *
 * At runtime we can change the branch target by setting the key
 * to true via a call to static_branch_enable(), or false using
 * static_branch_disable(). If the direction of the branch is switched by
 * these calls then we run-time modify the branch target via a
 * no-op -> jump or jump -> no-op conversion. For example, for an
 * initially false key that is used in an "if (static_branch_unlikely(&key))"
 * statement, setting the key to true requires us to patch in a jump
 * to the out-of-line of true branch.
 *
 * In addition to static_branch_{enable,disable}, we can also reference count
 * the key or branch direction via static_branch_{inc,dec}. Thus,
 * static_branch_inc() can be thought of as a 'make more true' and
 * static_branch_dec() as a 'make more false'.
 *
 * Since this relies on modifying code, the branch modifying functions
 * must be considered absolute slow paths (machine wide synchronization etc.).
 * OTOH, since the affected branches are unconditional, their runtime overhead
 * will be absolutely minimal, esp. in the default (off) case where the total
 * effect is a single NOP of appropriate size. The on case will patch in a jump
 * to the out-of-line block.
 *
 * When the control is directly exposed to userspace, it is prudent to delay the
 * decrement to avoid high frequency code modifications which can (and do)
 * cause significant performance degradation. Struct static_key_deferred and
 * static_key_slow_dec_deferred() provide for this.
 *
 * Lacking toolchain and or architecture support, static keys fall back to a
 * simple conditional branch.
 *
 * Additional babbling in: Documentation/static-keys.txt
 */

#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
# define HAVE_JUMP_LABEL
#endif

#ifndef __ASSEMBLY__

#include <linux/types.h>
#include <linux/compiler.h>

extern bool static_key_initialized;

#define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,		      \
				    "%s(): static key '%pS' used before call to jump_label_init()", \
				    __func__, (key))

#ifdef HAVE_JUMP_LABEL

struct static_key {
	atomic_t enabled;
/*
 * Note:
 *   To make anonymous unions work with old compilers, the static
 *   initialization of them requires brackets. This creates a dependency
 *   on the order of the struct with the initializers. If any fields
 *   are added, STATIC_KEY_INIT_TRUE and STATIC_KEY_INIT_FALSE may need
 *   to be modified.
 *
 * bit 0 => 1 if key is initially true
 *	    0 if initially false
 * bit 1 => 1 if points to struct static_key_mod
 *	    0 if points to struct jump_entry
 */
	union {
		unsigned long type;
		struct jump_entry *entries;
		struct static_key_mod *next;
	};
};

#else
struct static_key {
	atomic_t enabled;
};
#endif	/* HAVE_JUMP_LABEL */
#endif /* __ASSEMBLY__ */

#ifdef HAVE_JUMP_LABEL
#include <asm/jump_label.h>

#ifndef __ASSEMBLY__
#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE

struct jump_entry {
	s32 code;
	s32 target;
	long key;	// key may be far away from the core kernel under KASLR
};

static inline unsigned long jump_entry_code(const struct jump_entry *entry)
{
	return (unsigned long)&entry->code + entry->code;
}

static inline unsigned long jump_entry_target(const struct jump_entry *entry)
{
	return (unsigned long)&entry->target + entry->target;
}

static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
{
	long offset = entry->key & ~3L;

	return (struct static_key *)((unsigned long)&entry->key + offset);
}

#else

static inline unsigned long jump_entry_code(const struct jump_entry *entry)
{
	return entry->code;
}

static inline unsigned long jump_entry_target(const struct jump_entry *entry)
{
	return entry->target;
}

static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
{
	return (struct static_key *)((unsigned long)entry->key & ~3UL);
}

#endif

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

static inline bool jump_entry_is_init(const struct jump_entry *entry)
{
	return (unsigned long)entry->key & 2UL;
}

static inline void jump_entry_set_init(struct jump_entry *entry)
{
	entry->key |= 2;
}

#endif
#endif

#ifndef __ASSEMBLY__

enum jump_label_type {
	JUMP_LABEL_NOP = 0,
	JUMP_LABEL_JMP,
};

struct module;

#ifdef HAVE_JUMP_LABEL

#define JUMP_TYPE_FALSE		0UL
#define JUMP_TYPE_TRUE		1UL
#define JUMP_TYPE_LINKED	2UL
#define JUMP_TYPE_MASK		3UL

static __always_inline bool static_key_false(struct static_key *key)
{
	return arch_static_branch(key, false);
}

static __always_inline bool static_key_true(struct static_key *key)
{
	return !arch_static_branch(key, true);
}

extern struct jump_entry __start___jump_table[];
extern struct jump_entry __stop___jump_table[];

extern void jump_label_init(void);
extern void jump_label_lock(void);
extern void jump_label_unlock(void);
extern void arch_jump_label_transform(struct jump_entry *entry,
				      enum jump_label_type type);
extern void arch_jump_label_transform_static(struct jump_entry *entry,
					     enum jump_label_type type);
extern int jump_label_text_reserved(void *start, void *end);
extern void static_key_slow_inc(struct static_key *key);
extern void static_key_slow_dec(struct static_key *key);
extern void static_key_slow_inc_cpuslocked(struct static_key *key);
extern void static_key_slow_dec_cpuslocked(struct static_key *key);
extern void jump_label_apply_nops(struct module *mod);
extern int static_key_count(struct static_key *key);
extern void static_key_enable(struct static_key *key);
extern void static_key_disable(struct static_key *key);
extern void static_key_enable_cpuslocked(struct static_key *key);
extern void static_key_disable_cpuslocked(struct static_key *key);

/*
 * We should be using ATOMIC_INIT() for initializing .enabled, but
 * the inclusion of atomic.h is problematic for inclusion of jump_label.h
 * in 'low-level' headers. Thus, we are initializing .enabled with a
 * raw value, but have added a BUILD_BUG_ON() to catch any issues in
 * jump_label_init() see: kernel/jump_label.c.
 */
#define STATIC_KEY_INIT_TRUE					\
	{ .enabled = { 1 },					\
	  { .entries = (void *)JUMP_TYPE_TRUE } }
#define STATIC_KEY_INIT_FALSE					\
	{ .enabled = { 0 },					\
	  { .entries = (void *)JUMP_TYPE_FALSE } }

#else  /* !HAVE_JUMP_LABEL */

#include <linux/atomic.h>
#include <linux/bug.h>

static inline int static_key_count(struct static_key *key)
{
	return atomic_read(&key->enabled);
}

static __always_inline void jump_label_init(void)
{
	static_key_initialized = true;
}

static __always_inline bool static_key_false(struct static_key *key)
{
	if (unlikely(static_key_count(key) > 0))
		return true;
	return false;
}

static __always_inline bool static_key_true(struct static_key *key)
{
	if (likely(static_key_count(key) > 0))
		return true;
	return false;
}

static inline void static_key_slow_inc(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);
	atomic_inc(&key->enabled);
}

static inline void static_key_slow_dec(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);
	atomic_dec(&key->enabled);
}

#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)

static inline int jump_label_text_reserved(void *start, void *end)
{
	return 0;
}

static inline void jump_label_lock(void) {}
static inline void jump_label_unlock(void) {}

static inline int jump_label_apply_nops(struct module *mod)
{
	return 0;
}

static inline void static_key_enable(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);

	if (atomic_read(&key->enabled) != 0) {
		WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
		return;
	}
	atomic_set(&key->enabled, 1);
}

static inline void static_key_disable(struct static_key *key)
{
	STATIC_KEY_CHECK_USE(key);

	if (atomic_read(&key->enabled) != 1) {
		WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
		return;
	}
	atomic_set(&key->enabled, 0);
}

#define static_key_enable_cpuslocked(k)		static_key_enable((k))
#define static_key_disable_cpuslocked(k)	static_key_disable((k))

#define STATIC_KEY_INIT_TRUE	{ .enabled = ATOMIC_INIT(1) }
#define STATIC_KEY_INIT_FALSE	{ .enabled = ATOMIC_INIT(0) }

#endif	/* HAVE_JUMP_LABEL */

#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
#define jump_label_enabled static_key_enabled

/* -------------------------------------------------------------------------- */

/*
 * Two type wrappers around static_key, such that we can use compile time
 * type differentiation to emit the right code.
 *
 * All the below code is macros in order to play type games.
 */

struct static_key_true {
	struct static_key key;
};

struct static_key_false {
	struct static_key key;
};

#define STATIC_KEY_TRUE_INIT  (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE,  }
#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }

#define DEFINE_STATIC_KEY_TRUE(name)	\
	struct static_key_true name = STATIC_KEY_TRUE_INIT

#define DEFINE_STATIC_KEY_TRUE_RO(name)	\
	struct static_key_true name __ro_after_init = STATIC_KEY_TRUE_INIT

#define DECLARE_STATIC_KEY_TRUE(name)	\
	extern struct static_key_true name

#define DEFINE_STATIC_KEY_FALSE(name)	\
	struct static_key_false name = STATIC_KEY_FALSE_INIT

#define DEFINE_STATIC_KEY_FALSE_RO(name)	\
	struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT

#define DECLARE_STATIC_KEY_FALSE(name)	\
	extern struct static_key_false name

#define DEFINE_STATIC_KEY_ARRAY_TRUE(name, count)		\
	struct static_key_true name[count] = {			\
		[0 ... (count) - 1] = STATIC_KEY_TRUE_INIT,	\
	}

#define DEFINE_STATIC_KEY_ARRAY_FALSE(name, count)		\
	struct static_key_false name[count] = {			\
		[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT,	\
	}

extern bool ____wrong_branch_error(void);

#define static_key_enabled(x)							\
({										\
	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) &&	\
	    !__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
	    !__builtin_types_compatible_p(typeof(*x), struct static_key_false))	\
		____wrong_branch_error();					\
	static_key_count((struct static_key *)x) > 0;				\
})

#ifdef HAVE_JUMP_LABEL

/*
 * Combine the right initial value (type) with the right branch order
 * to generate the desired result.
 *
 *
 * type\branch|	likely (1)	      |	unlikely (0)
 * -----------+-----------------------+------------------
 *            |                       |
 *  true (1)  |	   ...		      |	   ...
 *            |    NOP		      |	   JMP L
 *            |    <br-stmts>	      |	1: ...
 *            |	L: ...		      |
 *            |			      |
 *            |			      |	L: <br-stmts>
 *            |			      |	   jmp 1b
 *            |                       |
 * -----------+-----------------------+------------------
 *            |                       |
 *  false (0) |	   ...		      |	   ...
 *            |    JMP L	      |	   NOP
 *            |    <br-stmts>	      |	1: ...
 *            |	L: ...		      |
 *            |			      |
 *            |			      |	L: <br-stmts>
 *            |			      |	   jmp 1b
 *            |                       |
 * -----------+-----------------------+------------------
 *
 * The initial value is encoded in the LSB of static_key::entries,
 * type: 0 = false, 1 = true.
 *
 * The branch type is encoded in the LSB of jump_entry::key,
 * branch: 0 = unlikely, 1 = likely.
 *
 * This gives the following logic table:
 *
 *	enabled	type	branch	  instuction
 * -----------------------------+-----------
 *	0	0	0	| NOP
 *	0	0	1	| JMP
 *	0	1	0	| NOP
 *	0	1	1	| JMP
 *
 *	1	0	0	| JMP
 *	1	0	1	| NOP
 *	1	1	0	| JMP
 *	1	1	1	| NOP
 *
 * Which gives the following functions:
 *
 *   dynamic: instruction = enabled ^ branch
 *   static:  instruction = type ^ branch
 *
 * See jump_label_type() / jump_label_init_type().
 */

#define static_branch_likely(x)							\
({										\
	bool branch;								\
	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true))	\
		branch = !arch_static_branch(&(x)->key, true);			\
	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
		branch = !arch_static_branch_jump(&(x)->key, true);		\
	else									\
		branch = ____wrong_branch_error();				\
	likely(branch);								\
})

#define static_branch_unlikely(x)						\
({										\
	bool branch;								\
	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true))	\
		branch = arch_static_branch_jump(&(x)->key, false);		\
	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
		branch = arch_static_branch(&(x)->key, false);			\
	else									\
		branch = ____wrong_branch_error();				\
	unlikely(branch);							\
})

#else /* !HAVE_JUMP_LABEL */

#define static_branch_likely(x)		likely(static_key_enabled(&(x)->key))
#define static_branch_unlikely(x)	unlikely(static_key_enabled(&(x)->key))

#endif /* HAVE_JUMP_LABEL */

/*
 * Advanced usage; refcount, branch is enabled when: count != 0
 */

#define static_branch_inc(x)		static_key_slow_inc(&(x)->key)
#define static_branch_dec(x)		static_key_slow_dec(&(x)->key)
#define static_branch_inc_cpuslocked(x)	static_key_slow_inc_cpuslocked(&(x)->key)
#define static_branch_dec_cpuslocked(x)	static_key_slow_dec_cpuslocked(&(x)->key)

/*
 * Normal usage; boolean enable/disable.
 */

#define static_branch_enable(x)			static_key_enable(&(x)->key)
#define static_branch_disable(x)		static_key_disable(&(x)->key)
#define static_branch_enable_cpuslocked(x)	static_key_enable_cpuslocked(&(x)->key)
#define static_branch_disable_cpuslocked(x)	static_key_disable_cpuslocked(&(x)->key)

#endif /* __ASSEMBLY__ */

#endif	/* _LINUX_JUMP_LABEL_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
bf5438fc JB	2	#ifndef _LINUX_JUMP_LABEL_H
	3	#define _LINUX_JUMP_LABEL_H
	4
efb3040d PZ	5	/*
	6	* Jump label support
	7	*
	8	* Copyright (C) 2009-2012 Jason Baron <jbaron@redhat.com>
90eec103	9	* Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra
efb3040d	10	*
412758cb JB	11	* DEPRECATED API:
	12	*
	13	* The use of 'struct static_key' directly, is now DEPRECATED. In addition
	14	* static_key_{true,false}() is also DEPRECATED. IE DO NOT use the following:
	15	*
	16	* struct static_key false = STATIC_KEY_INIT_FALSE;
	17	* struct static_key true = STATIC_KEY_INIT_TRUE;
	18	* static_key_true()
	19	* static_key_false()
	20	*
	21	* The updated API replacements are:
	22	*
	23	* DEFINE_STATIC_KEY_TRUE(key);
	24	* DEFINE_STATIC_KEY_FALSE(key);
ef0da55a CM	25	* DEFINE_STATIC_KEY_ARRAY_TRUE(keys, count);
ef0da55a CM	26	* DEFINE_STATIC_KEY_ARRAY_FALSE(keys, count);
1975dbc2 JC	27	* static_branch_likely()
1975dbc2 JC	28	* static_branch_unlikely()
412758cb	29	*
efb3040d	30	* Jump labels provide an interface to generate dynamic branches using
412758cb JB	31	* self-modifying code. Assuming toolchain and architecture support, if we
	32	* define a "key" that is initially false via "DEFINE_STATIC_KEY_FALSE(key)",
	33	* an "if (static_branch_unlikely(&key))" statement is an unconditional branch
	34	* (which defaults to false - and the true block is placed out of line).
	35	* Similarly, we can define an initially true key via
	36	* "DEFINE_STATIC_KEY_TRUE(key)", and use it in the same
	37	* "if (static_branch_unlikely(&key))", in which case we will generate an
	38	* unconditional branch to the out-of-line true branch. Keys that are
	39	* initially true or false can be using in both static_branch_unlikely()
	40	* and static_branch_likely() statements.
efb3040d	41	*
412758cb JB	42	* At runtime we can change the branch target by setting the key
	43	* to true via a call to static_branch_enable(), or false using
	44	* static_branch_disable(). If the direction of the branch is switched by
	45	* these calls then we run-time modify the branch target via a
	46	* no-op -> jump or jump -> no-op conversion. For example, for an
	47	* initially false key that is used in an "if (static_branch_unlikely(&key))"
	48	* statement, setting the key to true requires us to patch in a jump
	49	* to the out-of-line of true branch.
efb3040d	50	*
1975dbc2	51	* In addition to static_branch_{enable,disable}, we can also reference count
412758cb JB	52	* the key or branch direction via static_branch_{inc,dec}. Thus,
412758cb JB	53	* static_branch_inc() can be thought of as a 'make more true' and
1975dbc2	54	* static_branch_dec() as a 'make more false'.
412758cb JB	55	*
412758cb JB	56	* Since this relies on modifying code, the branch modifying functions
efb3040d	57	* must be considered absolute slow paths (machine wide synchronization etc.).
fd3cbdc0	58	* OTOH, since the affected branches are unconditional, their runtime overhead
efb3040d PZ	59	* will be absolutely minimal, esp. in the default (off) case where the total
	60	* effect is a single NOP of appropriate size. The on case will patch in a jump
	61	* to the out-of-line block.
	62	*
fd3cbdc0	63	* When the control is directly exposed to userspace, it is prudent to delay the
efb3040d	64	* decrement to avoid high frequency code modifications which can (and do)
c5905afb IM	65	* cause significant performance degradation. Struct static_key_deferred and
c5905afb IM	66	* static_key_slow_dec_deferred() provide for this.
efb3040d	67	*
412758cb JB	68	* Lacking toolchain and or architecture support, static keys fall back to a
412758cb JB	69	* simple conditional branch.
c5905afb	70	*
412758cb	71	* Additional babbling in: Documentation/static-keys.txt
fd3cbdc0	72	*/
efb3040d	73
c0ccf6f9 AB	74	#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
	75	# define HAVE_JUMP_LABEL
	76	#endif
	77
	78	#ifndef __ASSEMBLY__
	79
d430d3d7 JB	80	#include <linux/types.h>
d430d3d7 JB	81	#include <linux/compiler.h>
c4b2c0c5 HFS	82
	83	extern bool static_key_initialized;
	84
5cdda511 BP	85	#define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized, \
	86	"%s(): static key '%pS' used before call to jump_label_init()", \
	87	__func__, (key))
d430d3d7	88
c0ccf6f9	89	#ifdef HAVE_JUMP_LABEL
d430d3d7	90
c5905afb	91	struct static_key {
d430d3d7	92	atomic_t enabled;
3821fd35	93	/*
b17ef2ed SRV	94	* Note:
	95	* To make anonymous unions work with old compilers, the static
	96	* initialization of them requires brackets. This creates a dependency
	97	* on the order of the struct with the initializers. If any fields
	98	* are added, STATIC_KEY_INIT_TRUE and STATIC_KEY_INIT_FALSE may need
	99	* to be modified.
	100	*
3821fd35 JB	101	* bit 0 => 1 if key is initially true
	102	* 0 if initially false
	103	* bit 1 => 1 if points to struct static_key_mod
	104	* 0 if points to struct jump_entry
	105	*/
	106	union {
	107	unsigned long type;
	108	struct jump_entry *entries;
	109	struct static_key_mod *next;
	110	};
d430d3d7 JB	111	};
d430d3d7 JB	112
ea5e9539 MG	113	#else
	114	struct static_key {
	115	atomic_t enabled;
	116	};
c0ccf6f9 AB	117	#endif /* HAVE_JUMP_LABEL */
	118	#endif /* __ASSEMBLY__ */
	119
	120	#ifdef HAVE_JUMP_LABEL
	121	#include <asm/jump_label.h>
9ae033ac AB	122
9ae033ac AB	123	#ifndef __ASSEMBLY__
50ff18ab AB	124	#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
	125
	126	struct jump_entry {
	127	s32 code;
	128	s32 target;
	129	long key; // key may be far away from the core kernel under KASLR
	130	};
	131
	132	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	133	{
	134	return (unsigned long)&entry->code + entry->code;
	135	}
	136
	137	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	138	{
	139	return (unsigned long)&entry->target + entry->target;
	140	}
	141
	142	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	143	{
19483677	144	long offset = entry->key & ~3L;
50ff18ab AB	145
	146	return (struct static_key *)((unsigned long)&entry->key + offset);
	147	}
	148
	149	#else
9ae033ac AB	150
	151	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	152	{
	153	return entry->code;
	154	}
	155
	156	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	157	{
	158	return entry->target;
	159	}
	160
	161	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	162	{
19483677	163	return (struct static_key *)((unsigned long)entry->key & ~3UL);
9ae033ac AB	164	}
9ae033ac AB	165
50ff18ab AB	166	#endif
50ff18ab AB	167
9ae033ac AB	168	static inline bool jump_entry_is_branch(const struct jump_entry *entry)
	169	{
	170	return (unsigned long)entry->key & 1UL;
	171	}
	172
	173	static inline bool jump_entry_is_init(const struct jump_entry *entry)
	174	{
19483677	175	return (unsigned long)entry->key & 2UL;
9ae033ac AB	176	}
	177
	178	static inline void jump_entry_set_init(struct jump_entry *entry)
	179	{
19483677	180	entry->key \|= 2;
9ae033ac AB	181	}
	182
	183	#endif
c0ccf6f9 AB	184	#endif
	185
	186	#ifndef __ASSEMBLY__
bf5438fc JB	187
bf5438fc JB	188	enum jump_label_type {
76b235c6 PZ	189	JUMP_LABEL_NOP = 0,
76b235c6 PZ	190	JUMP_LABEL_JMP,
bf5438fc JB	191	};
	192
	193	struct module;
	194
4c5ea0a9 PB	195	#ifdef HAVE_JUMP_LABEL
4c5ea0a9 PB	196
3821fd35 JB	197	#define JUMP_TYPE_FALSE 0UL
	198	#define JUMP_TYPE_TRUE 1UL
	199	#define JUMP_TYPE_LINKED 2UL
	200	#define JUMP_TYPE_MASK 3UL
c5905afb IM	201
	202	static __always_inline bool static_key_false(struct static_key *key)
	203	{
11276d53	204	return arch_static_branch(key, false);
c5905afb	205	}
d430d3d7	206
c5905afb IM	207	static __always_inline bool static_key_true(struct static_key *key)
c5905afb IM	208	{
11276d53	209	return !arch_static_branch(key, true);
c5905afb IM	210	}
c5905afb IM	211
bf5438fc JB	212	extern struct jump_entry __start___jump_table[];
	213	extern struct jump_entry __stop___jump_table[];
	214
97ce2c88	215	extern void jump_label_init(void);
91bad2f8 JB	216	extern void jump_label_lock(void);
91bad2f8 JB	217	extern void jump_label_unlock(void);
bf5438fc	218	extern void arch_jump_label_transform(struct jump_entry *entry,
37348804	219	enum jump_label_type type);
20284aa7 JF	220	extern void arch_jump_label_transform_static(struct jump_entry *entry,
20284aa7 JF	221	enum jump_label_type type);
4c3ef6d7	222	extern int jump_label_text_reserved(void start, void end);
c5905afb IM	223	extern void static_key_slow_inc(struct static_key *key);
c5905afb IM	224	extern void static_key_slow_dec(struct static_key *key);
ce48c146 PZ	225	extern void static_key_slow_inc_cpuslocked(struct static_key *key);
ce48c146 PZ	226	extern void static_key_slow_dec_cpuslocked(struct static_key *key);
d430d3d7	227	extern void jump_label_apply_nops(struct module *mod);
1f69bf9c JB	228	extern int static_key_count(struct static_key *key);
	229	extern void static_key_enable(struct static_key *key);
	230	extern void static_key_disable(struct static_key *key);
5a40527f MZ	231	extern void static_key_enable_cpuslocked(struct static_key *key);
5a40527f MZ	232	extern void static_key_disable_cpuslocked(struct static_key *key);
c5905afb	233
1f69bf9c JB	234	/*
	235	* We should be using ATOMIC_INIT() for initializing .enabled, but
	236	* the inclusion of atomic.h is problematic for inclusion of jump_label.h
	237	* in 'low-level' headers. Thus, we are initializing .enabled with a
	238	* raw value, but have added a BUILD_BUG_ON() to catch any issues in
	239	* jump_label_init() see: kernel/jump_label.c.
	240	*/
11276d53	241	#define STATIC_KEY_INIT_TRUE \
1f69bf9c	242	{ .enabled = { 1 }, \
cd8d860d	243	{ .entries = (void *)JUMP_TYPE_TRUE } }
11276d53	244	#define STATIC_KEY_INIT_FALSE \
1f69bf9c	245	{ .enabled = { 0 }, \
cd8d860d	246	{ .entries = (void *)JUMP_TYPE_FALSE } }
bf5438fc	247
97ce2c88	248	#else /* !HAVE_JUMP_LABEL */
bf5438fc	249
1f69bf9c JB	250	#include <linux/atomic.h>
	251	#include <linux/bug.h>
	252
4c5ea0a9 PB	253	static inline int static_key_count(struct static_key *key)
	254	{
	255	return atomic_read(&key->enabled);
	256	}
	257
97ce2c88 JF	258	static __always_inline void jump_label_init(void)
97ce2c88 JF	259	{
c4b2c0c5	260	static_key_initialized = true;
97ce2c88 JF	261	}
97ce2c88 JF	262
c5905afb IM	263	static __always_inline bool static_key_false(struct static_key *key)
c5905afb IM	264	{
ea5e9539	265	if (unlikely(static_key_count(key) > 0))
c5905afb IM	266	return true;
	267	return false;
	268	}
	269
	270	static __always_inline bool static_key_true(struct static_key *key)
d430d3d7	271	{
ea5e9539	272	if (likely(static_key_count(key) > 0))
d430d3d7 JB	273	return true;
	274	return false;
	275	}
bf5438fc	276
c5905afb	277	static inline void static_key_slow_inc(struct static_key *key)
d430d3d7	278	{
5cdda511	279	STATIC_KEY_CHECK_USE(key);
d430d3d7 JB	280	atomic_inc(&key->enabled);
d430d3d7 JB	281	}
bf5438fc	282
c5905afb	283	static inline void static_key_slow_dec(struct static_key *key)
bf5438fc	284	{
5cdda511	285	STATIC_KEY_CHECK_USE(key);
d430d3d7	286	atomic_dec(&key->enabled);
bf5438fc JB	287	}
bf5438fc JB	288
ce48c146 PZ	289	#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
	290	#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
	291
4c3ef6d7 JB	292	static inline int jump_label_text_reserved(void start, void end)
	293	{
	294	return 0;
	295	}
	296
91bad2f8 JB	297	static inline void jump_label_lock(void) {}
	298	static inline void jump_label_unlock(void) {}
	299
d430d3d7 JB	300	static inline int jump_label_apply_nops(struct module *mod)
	301	{
	302	return 0;
	303	}
b2029520	304
e33886b3 PZ	305	static inline void static_key_enable(struct static_key *key)
e33886b3 PZ	306	{
5cdda511	307	STATIC_KEY_CHECK_USE(key);
e33886b3	308
1dbb6704 PB	309	if (atomic_read(&key->enabled) != 0) {
	310	WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
	311	return;
	312	}
	313	atomic_set(&key->enabled, 1);
e33886b3 PZ	314	}
	315
	316	static inline void static_key_disable(struct static_key *key)
	317	{
5cdda511	318	STATIC_KEY_CHECK_USE(key);
e33886b3	319
1dbb6704 PB	320	if (atomic_read(&key->enabled) != 1) {
	321	WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
	322	return;
	323	}
	324	atomic_set(&key->enabled, 0);
e33886b3 PZ	325	}
e33886b3 PZ	326
5a40527f MZ	327	#define static_key_enable_cpuslocked(k) static_key_enable((k))
	328	#define static_key_disable_cpuslocked(k) static_key_disable((k))
	329
1f69bf9c JB	330	#define STATIC_KEY_INIT_TRUE { .enabled = ATOMIC_INIT(1) }
	331	#define STATIC_KEY_INIT_FALSE { .enabled = ATOMIC_INIT(0) }
	332
	333	#endif /* HAVE_JUMP_LABEL */
	334
	335	#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
	336	#define jump_label_enabled static_key_enabled
	337
11276d53 PZ	338	/* -------------------------------------------------------------------------- */
	339
	340	/*
	341	* Two type wrappers around static_key, such that we can use compile time
	342	* type differentiation to emit the right code.
	343	*
	344	* All the below code is macros in order to play type games.
	345	*/
	346
	347	struct static_key_true {
	348	struct static_key key;
	349	};
	350
	351	struct static_key_false {
	352	struct static_key key;
	353	};
	354
	355	#define STATIC_KEY_TRUE_INIT (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE, }
	356	#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }
	357
	358	#define DEFINE_STATIC_KEY_TRUE(name) \
	359	struct static_key_true name = STATIC_KEY_TRUE_INIT
	360
b5cb15d9 CR	361	#define DEFINE_STATIC_KEY_TRUE_RO(name) \
	362	struct static_key_true name __ro_after_init = STATIC_KEY_TRUE_INIT
	363
b8fb0378 TL	364	#define DECLARE_STATIC_KEY_TRUE(name) \
	365	extern struct static_key_true name
	366
11276d53 PZ	367	#define DEFINE_STATIC_KEY_FALSE(name) \
	368	struct static_key_false name = STATIC_KEY_FALSE_INIT
	369
b5cb15d9 CR	370	#define DEFINE_STATIC_KEY_FALSE_RO(name) \
	371	struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT
	372
b8fb0378 TL	373	#define DECLARE_STATIC_KEY_FALSE(name) \
	374	extern struct static_key_false name
	375
ef0da55a CM	376	#define DEFINE_STATIC_KEY_ARRAY_TRUE(name, count) \
	377	struct static_key_true name[count] = { \
	378	[0 ... (count) - 1] = STATIC_KEY_TRUE_INIT, \
	379	}
	380
	381	#define DEFINE_STATIC_KEY_ARRAY_FALSE(name, count) \
	382	struct static_key_false name[count] = { \
	383	[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \
	384	}
	385
fa128fd7 TH	386	extern bool ____wrong_branch_error(void);
	387
	388	#define static_key_enabled(x) \
	389	({ \
	390	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) && \
	391	!__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
	392	!__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	393	____wrong_branch_error(); \
	394	static_key_count((struct static_key *)x) > 0; \
	395	})
	396
11276d53 PZ	397	#ifdef HAVE_JUMP_LABEL
	398
	399	/*
	400	* Combine the right initial value (type) with the right branch order
	401	* to generate the desired result.
	402	*
	403	*
	404	* type\branch\| likely (1) \| unlikely (0)
	405	* -----------+-----------------------+------------------
	406	* \| \|
	407	* true (1) \| ... \| ...
	408	* \| NOP \| JMP L
	409	* \| <br-stmts> \| 1: ...
	410	* \| L: ... \|
	411	* \| \|
	412	* \| \| L: <br-stmts>
	413	* \| \| jmp 1b
	414	* \| \|
	415	* -----------+-----------------------+------------------
	416	* \| \|
	417	* false (0) \| ... \| ...
	418	* \| JMP L \| NOP
	419	* \| <br-stmts> \| 1: ...
	420	* \| L: ... \|
	421	* \| \|
	422	* \| \| L: <br-stmts>
	423	* \| \| jmp 1b
	424	* \| \|
	425	* -----------+-----------------------+------------------
	426	*
	427	* The initial value is encoded in the LSB of static_key::entries,
	428	* type: 0 = false, 1 = true.
	429	*
	430	* The branch type is encoded in the LSB of jump_entry::key,
	431	* branch: 0 = unlikely, 1 = likely.
	432	*
	433	* This gives the following logic table:
	434	*
	435	* enabled type branch instuction
	436	* -----------------------------+-----------
	437	* 0 0 0 \| NOP
	438	* 0 0 1 \| JMP
	439	* 0 1 0 \| NOP
	440	* 0 1 1 \| JMP
	441	*
	442	* 1 0 0 \| JMP
	443	* 1 0 1 \| NOP
	444	* 1 1 0 \| JMP
	445	* 1 1 1 \| NOP
	446	*
	447	* Which gives the following functions:
	448	*
	449	* dynamic: instruction = enabled ^ branch
	450	* static: instruction = type ^ branch
	451	*
	452	* See jump_label_type() / jump_label_init_type().
	453	*/
	454
11276d53 PZ	455	#define static_branch_likely(x) \
	456	({ \
	457	bool branch; \
	458	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	459	branch = !arch_static_branch(&(x)->key, true); \
	460	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	461	branch = !arch_static_branch_jump(&(x)->key, true); \
	462	else \
	463	branch = ____wrong_branch_error(); \
81dcf89f	464	likely(branch); \
11276d53 PZ	465	})
	466
	467	#define static_branch_unlikely(x) \
	468	({ \
	469	bool branch; \
	470	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	471	branch = arch_static_branch_jump(&(x)->key, false); \
	472	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	473	branch = arch_static_branch(&(x)->key, false); \
	474	else \
	475	branch = ____wrong_branch_error(); \
81dcf89f	476	unlikely(branch); \
11276d53 PZ	477	})
	478
	479	#else /* !HAVE_JUMP_LABEL */
	480
	481	#define static_branch_likely(x) likely(static_key_enabled(&(x)->key))
	482	#define static_branch_unlikely(x) unlikely(static_key_enabled(&(x)->key))
	483
	484	#endif /* HAVE_JUMP_LABEL */
	485
	486	/*
	487	* Advanced usage; refcount, branch is enabled when: count != 0
	488	*/
	489
	490	#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
	491	#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
ce48c146 PZ	492	#define static_branch_inc_cpuslocked(x) static_key_slow_inc_cpuslocked(&(x)->key)
ce48c146 PZ	493	#define static_branch_dec_cpuslocked(x) static_key_slow_dec_cpuslocked(&(x)->key)
11276d53 PZ	494
	495	/*
	496	* Normal usage; boolean enable/disable.
	497	*/
	498
5a40527f MZ	499	#define static_branch_enable(x) static_key_enable(&(x)->key)
	500	#define static_branch_disable(x) static_key_disable(&(x)->key)
	501	#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key)
	502	#define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key)
11276d53	503
c0ccf6f9	504	#endif /* __ASSEMBLY__ */
85b36c93 LR	505
85b36c93 LR	506	#endif /* _LINUX_JUMP_LABEL_H */