[mirror_ubuntu-focal-kernel.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() WARN(!static_key_initialized,		      \
				    "%s used before call to jump_label_init", \
				    __func__)

#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>
#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 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();
	atomic_inc(&key->enabled);
}

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

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();

	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();

	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 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 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();				\
	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();				\
	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)

/*
 * 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
	85	#define STATIC_KEY_CHECK_USE() WARN(!static_key_initialized, \
	86	"%s used before call to jump_label_init", \
	87	__func__)
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>
	122	#endif
	123
	124	#ifndef __ASSEMBLY__
bf5438fc JB	125
bf5438fc JB	126	enum jump_label_type {
76b235c6 PZ	127	JUMP_LABEL_NOP = 0,
76b235c6 PZ	128	JUMP_LABEL_JMP,
bf5438fc JB	129	};
	130
	131	struct module;
	132
4c5ea0a9 PB	133	#ifdef HAVE_JUMP_LABEL
4c5ea0a9 PB	134
3821fd35 JB	135	#define JUMP_TYPE_FALSE 0UL
	136	#define JUMP_TYPE_TRUE 1UL
	137	#define JUMP_TYPE_LINKED 2UL
	138	#define JUMP_TYPE_MASK 3UL
c5905afb IM	139
	140	static __always_inline bool static_key_false(struct static_key *key)
	141	{
11276d53	142	return arch_static_branch(key, false);
c5905afb	143	}
d430d3d7	144
c5905afb IM	145	static __always_inline bool static_key_true(struct static_key *key)
c5905afb IM	146	{
11276d53	147	return !arch_static_branch(key, true);
c5905afb IM	148	}
c5905afb IM	149
bf5438fc JB	150	extern struct jump_entry __start___jump_table[];
	151	extern struct jump_entry __stop___jump_table[];
	152
97ce2c88	153	extern void jump_label_init(void);
91bad2f8 JB	154	extern void jump_label_lock(void);
91bad2f8 JB	155	extern void jump_label_unlock(void);
bf5438fc	156	extern void arch_jump_label_transform(struct jump_entry *entry,
37348804	157	enum jump_label_type type);
20284aa7 JF	158	extern void arch_jump_label_transform_static(struct jump_entry *entry,
20284aa7 JF	159	enum jump_label_type type);
4c3ef6d7	160	extern int jump_label_text_reserved(void start, void end);
c5905afb IM	161	extern void static_key_slow_inc(struct static_key *key);
c5905afb IM	162	extern void static_key_slow_dec(struct static_key *key);
d430d3d7	163	extern void jump_label_apply_nops(struct module *mod);
1f69bf9c JB	164	extern int static_key_count(struct static_key *key);
	165	extern void static_key_enable(struct static_key *key);
	166	extern void static_key_disable(struct static_key *key);
5a40527f MZ	167	extern void static_key_enable_cpuslocked(struct static_key *key);
5a40527f MZ	168	extern void static_key_disable_cpuslocked(struct static_key *key);
c5905afb	169
1f69bf9c JB	170	/*
	171	* We should be using ATOMIC_INIT() for initializing .enabled, but
	172	* the inclusion of atomic.h is problematic for inclusion of jump_label.h
	173	* in 'low-level' headers. Thus, we are initializing .enabled with a
	174	* raw value, but have added a BUILD_BUG_ON() to catch any issues in
	175	* jump_label_init() see: kernel/jump_label.c.
	176	*/
11276d53	177	#define STATIC_KEY_INIT_TRUE \
1f69bf9c	178	{ .enabled = { 1 }, \
cd8d860d	179	{ .entries = (void *)JUMP_TYPE_TRUE } }
11276d53	180	#define STATIC_KEY_INIT_FALSE \
1f69bf9c	181	{ .enabled = { 0 }, \
cd8d860d	182	{ .entries = (void *)JUMP_TYPE_FALSE } }
bf5438fc	183
97ce2c88	184	#else /* !HAVE_JUMP_LABEL */
bf5438fc	185
1f69bf9c JB	186	#include <linux/atomic.h>
	187	#include <linux/bug.h>
	188
4c5ea0a9 PB	189	static inline int static_key_count(struct static_key *key)
	190	{
	191	return atomic_read(&key->enabled);
	192	}
	193
97ce2c88 JF	194	static __always_inline void jump_label_init(void)
97ce2c88 JF	195	{
c4b2c0c5	196	static_key_initialized = true;
97ce2c88 JF	197	}
97ce2c88 JF	198
c5905afb IM	199	static __always_inline bool static_key_false(struct static_key *key)
c5905afb IM	200	{
ea5e9539	201	if (unlikely(static_key_count(key) > 0))
c5905afb IM	202	return true;
	203	return false;
	204	}
	205
	206	static __always_inline bool static_key_true(struct static_key *key)
d430d3d7	207	{
ea5e9539	208	if (likely(static_key_count(key) > 0))
d430d3d7 JB	209	return true;
	210	return false;
	211	}
bf5438fc	212
c5905afb	213	static inline void static_key_slow_inc(struct static_key *key)
d430d3d7	214	{
c4b2c0c5	215	STATIC_KEY_CHECK_USE();
d430d3d7 JB	216	atomic_inc(&key->enabled);
d430d3d7 JB	217	}
bf5438fc	218
c5905afb	219	static inline void static_key_slow_dec(struct static_key *key)
bf5438fc	220	{
c4b2c0c5	221	STATIC_KEY_CHECK_USE();
d430d3d7	222	atomic_dec(&key->enabled);
bf5438fc JB	223	}
bf5438fc JB	224
4c3ef6d7 JB	225	static inline int jump_label_text_reserved(void start, void end)
	226	{
	227	return 0;
	228	}
	229
91bad2f8 JB	230	static inline void jump_label_lock(void) {}
	231	static inline void jump_label_unlock(void) {}
	232
d430d3d7 JB	233	static inline int jump_label_apply_nops(struct module *mod)
	234	{
	235	return 0;
	236	}
b2029520	237
e33886b3 PZ	238	static inline void static_key_enable(struct static_key *key)
e33886b3 PZ	239	{
1dbb6704	240	STATIC_KEY_CHECK_USE();
e33886b3	241
1dbb6704 PB	242	if (atomic_read(&key->enabled) != 0) {
	243	WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
	244	return;
	245	}
	246	atomic_set(&key->enabled, 1);
e33886b3 PZ	247	}
	248
	249	static inline void static_key_disable(struct static_key *key)
	250	{
1dbb6704	251	STATIC_KEY_CHECK_USE();
e33886b3	252
1dbb6704 PB	253	if (atomic_read(&key->enabled) != 1) {
	254	WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
	255	return;
	256	}
	257	atomic_set(&key->enabled, 0);
e33886b3 PZ	258	}
e33886b3 PZ	259
5a40527f MZ	260	#define static_key_enable_cpuslocked(k) static_key_enable((k))
	261	#define static_key_disable_cpuslocked(k) static_key_disable((k))
	262
1f69bf9c JB	263	#define STATIC_KEY_INIT_TRUE { .enabled = ATOMIC_INIT(1) }
	264	#define STATIC_KEY_INIT_FALSE { .enabled = ATOMIC_INIT(0) }
	265
	266	#endif /* HAVE_JUMP_LABEL */
	267
	268	#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
	269	#define jump_label_enabled static_key_enabled
	270
11276d53 PZ	271	/* -------------------------------------------------------------------------- */
	272
	273	/*
	274	* Two type wrappers around static_key, such that we can use compile time
	275	* type differentiation to emit the right code.
	276	*
	277	* All the below code is macros in order to play type games.
	278	*/
	279
	280	struct static_key_true {
	281	struct static_key key;
	282	};
	283
	284	struct static_key_false {
	285	struct static_key key;
	286	};
	287
	288	#define STATIC_KEY_TRUE_INIT (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE, }
	289	#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }
	290
	291	#define DEFINE_STATIC_KEY_TRUE(name) \
	292	struct static_key_true name = STATIC_KEY_TRUE_INIT
	293
b8fb0378 TL	294	#define DECLARE_STATIC_KEY_TRUE(name) \
	295	extern struct static_key_true name
	296
11276d53 PZ	297	#define DEFINE_STATIC_KEY_FALSE(name) \
	298	struct static_key_false name = STATIC_KEY_FALSE_INIT
	299
b8fb0378 TL	300	#define DECLARE_STATIC_KEY_FALSE(name) \
	301	extern struct static_key_false name
	302
ef0da55a CM	303	#define DEFINE_STATIC_KEY_ARRAY_TRUE(name, count) \
	304	struct static_key_true name[count] = { \
	305	[0 ... (count) - 1] = STATIC_KEY_TRUE_INIT, \
	306	}
	307
	308	#define DEFINE_STATIC_KEY_ARRAY_FALSE(name, count) \
	309	struct static_key_false name[count] = { \
	310	[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \
	311	}
	312
fa128fd7 TH	313	extern bool ____wrong_branch_error(void);
	314
	315	#define static_key_enabled(x) \
	316	({ \
	317	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) && \
	318	!__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
	319	!__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	320	____wrong_branch_error(); \
	321	static_key_count((struct static_key *)x) > 0; \
	322	})
	323
11276d53 PZ	324	#ifdef HAVE_JUMP_LABEL
	325
	326	/*
	327	* Combine the right initial value (type) with the right branch order
	328	* to generate the desired result.
	329	*
	330	*
	331	* type\branch\| likely (1) \| unlikely (0)
	332	* -----------+-----------------------+------------------
	333	* \| \|
	334	* true (1) \| ... \| ...
	335	* \| NOP \| JMP L
	336	* \| <br-stmts> \| 1: ...
	337	* \| L: ... \|
	338	* \| \|
	339	* \| \| L: <br-stmts>
	340	* \| \| jmp 1b
	341	* \| \|
	342	* -----------+-----------------------+------------------
	343	* \| \|
	344	* false (0) \| ... \| ...
	345	* \| JMP L \| NOP
	346	* \| <br-stmts> \| 1: ...
	347	* \| L: ... \|
	348	* \| \|
	349	* \| \| L: <br-stmts>
	350	* \| \| jmp 1b
	351	* \| \|
	352	* -----------+-----------------------+------------------
	353	*
	354	* The initial value is encoded in the LSB of static_key::entries,
	355	* type: 0 = false, 1 = true.
	356	*
	357	* The branch type is encoded in the LSB of jump_entry::key,
	358	* branch: 0 = unlikely, 1 = likely.
	359	*
	360	* This gives the following logic table:
	361	*
	362	* enabled type branch instuction
	363	* -----------------------------+-----------
	364	* 0 0 0 \| NOP
	365	* 0 0 1 \| JMP
	366	* 0 1 0 \| NOP
	367	* 0 1 1 \| JMP
	368	*
	369	* 1 0 0 \| JMP
	370	* 1 0 1 \| NOP
	371	* 1 1 0 \| JMP
	372	* 1 1 1 \| NOP
	373	*
	374	* Which gives the following functions:
	375	*
	376	* dynamic: instruction = enabled ^ branch
	377	* static: instruction = type ^ branch
	378	*
	379	* See jump_label_type() / jump_label_init_type().
	380	*/
	381
11276d53 PZ	382	#define static_branch_likely(x) \
	383	({ \
	384	bool branch; \
	385	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	386	branch = !arch_static_branch(&(x)->key, true); \
	387	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	388	branch = !arch_static_branch_jump(&(x)->key, true); \
	389	else \
	390	branch = ____wrong_branch_error(); \
	391	branch; \
	392	})
	393
	394	#define static_branch_unlikely(x) \
	395	({ \
	396	bool branch; \
	397	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	398	branch = arch_static_branch_jump(&(x)->key, false); \
	399	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	400	branch = arch_static_branch(&(x)->key, false); \
	401	else \
	402	branch = ____wrong_branch_error(); \
	403	branch; \
	404	})
	405
	406	#else /* !HAVE_JUMP_LABEL */
	407
	408	#define static_branch_likely(x) likely(static_key_enabled(&(x)->key))
	409	#define static_branch_unlikely(x) unlikely(static_key_enabled(&(x)->key))
	410
	411	#endif /* HAVE_JUMP_LABEL */
	412
	413	/*
	414	* Advanced usage; refcount, branch is enabled when: count != 0
	415	*/
	416
	417	#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
	418	#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
	419
	420	/*
	421	* Normal usage; boolean enable/disable.
	422	*/
	423
5a40527f MZ	424	#define static_branch_enable(x) static_key_enable(&(x)->key)
	425	#define static_branch_disable(x) static_key_disable(&(x)->key)
	426	#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key)
	427	#define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key)
11276d53	428
c0ccf6f9	429	#endif /* __ASSEMBLY__ */
85b36c93 LR	430
85b36c93 LR	431	#endif /* _LINUX_JUMP_LABEL_H */