[linux-2.6-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
 */

#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 CONFIG_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	/* CONFIG_JUMP_LABEL */
#endif /* __ASSEMBLY__ */

#ifdef CONFIG_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 CONFIG_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  /* !CONFIG_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	/* CONFIG_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 CONFIG_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 /* !CONFIG_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 /* CONFIG_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	#ifndef __ASSEMBLY__
c0ccf6f9 AB	75
d430d3d7 JB	76	#include <linux/types.h>
d430d3d7 JB	77	#include <linux/compiler.h>
c4b2c0c5 HFS	78
	79	extern bool static_key_initialized;
	80
5cdda511 BP	81	#define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized, \
	82	"%s(): static key '%pS' used before call to jump_label_init()", \
	83	__func__, (key))
d430d3d7	84
e9666d10	85	#ifdef CONFIG_JUMP_LABEL
d430d3d7	86
c5905afb	87	struct static_key {
d430d3d7	88	atomic_t enabled;
3821fd35	89	/*
b17ef2ed SRV	90	* Note:
	91	* To make anonymous unions work with old compilers, the static
	92	* initialization of them requires brackets. This creates a dependency
	93	* on the order of the struct with the initializers. If any fields
	94	* are added, STATIC_KEY_INIT_TRUE and STATIC_KEY_INIT_FALSE may need
	95	* to be modified.
	96	*
3821fd35 JB	97	* bit 0 => 1 if key is initially true
	98	* 0 if initially false
	99	* bit 1 => 1 if points to struct static_key_mod
	100	* 0 if points to struct jump_entry
	101	*/
	102	union {
	103	unsigned long type;
	104	struct jump_entry *entries;
	105	struct static_key_mod *next;
	106	};
d430d3d7 JB	107	};
d430d3d7 JB	108
ea5e9539 MG	109	#else
	110	struct static_key {
	111	atomic_t enabled;
	112	};
e9666d10	113	#endif /* CONFIG_JUMP_LABEL */
c0ccf6f9 AB	114	#endif /* __ASSEMBLY__ */
c0ccf6f9 AB	115
e9666d10	116	#ifdef CONFIG_JUMP_LABEL
c0ccf6f9	117	#include <asm/jump_label.h>
9ae033ac AB	118
9ae033ac AB	119	#ifndef __ASSEMBLY__
50ff18ab AB	120	#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
	121
	122	struct jump_entry {
	123	s32 code;
	124	s32 target;
	125	long key; // key may be far away from the core kernel under KASLR
	126	};
	127
	128	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	129	{
	130	return (unsigned long)&entry->code + entry->code;
	131	}
	132
	133	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	134	{
	135	return (unsigned long)&entry->target + entry->target;
	136	}
	137
	138	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	139	{
19483677	140	long offset = entry->key & ~3L;
50ff18ab AB	141
	142	return (struct static_key *)((unsigned long)&entry->key + offset);
	143	}
	144
	145	#else
9ae033ac AB	146
	147	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	148	{
	149	return entry->code;
	150	}
	151
	152	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	153	{
	154	return entry->target;
	155	}
	156
	157	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	158	{
19483677	159	return (struct static_key *)((unsigned long)entry->key & ~3UL);
9ae033ac AB	160	}
9ae033ac AB	161
50ff18ab AB	162	#endif
50ff18ab AB	163
9ae033ac AB	164	static inline bool jump_entry_is_branch(const struct jump_entry *entry)
	165	{
	166	return (unsigned long)entry->key & 1UL;
	167	}
	168
	169	static inline bool jump_entry_is_init(const struct jump_entry *entry)
	170	{
19483677	171	return (unsigned long)entry->key & 2UL;
9ae033ac AB	172	}
	173
	174	static inline void jump_entry_set_init(struct jump_entry *entry)
	175	{
19483677	176	entry->key \|= 2;
9ae033ac AB	177	}
	178
	179	#endif
c0ccf6f9 AB	180	#endif
	181
	182	#ifndef __ASSEMBLY__
bf5438fc JB	183
bf5438fc JB	184	enum jump_label_type {
76b235c6 PZ	185	JUMP_LABEL_NOP = 0,
76b235c6 PZ	186	JUMP_LABEL_JMP,
bf5438fc JB	187	};
	188
	189	struct module;
	190
e9666d10	191	#ifdef CONFIG_JUMP_LABEL
4c5ea0a9	192
3821fd35 JB	193	#define JUMP_TYPE_FALSE 0UL
	194	#define JUMP_TYPE_TRUE 1UL
	195	#define JUMP_TYPE_LINKED 2UL
	196	#define JUMP_TYPE_MASK 3UL
c5905afb IM	197
	198	static __always_inline bool static_key_false(struct static_key *key)
	199	{
11276d53	200	return arch_static_branch(key, false);
c5905afb	201	}
d430d3d7	202
c5905afb IM	203	static __always_inline bool static_key_true(struct static_key *key)
c5905afb IM	204	{
11276d53	205	return !arch_static_branch(key, true);
c5905afb IM	206	}
c5905afb IM	207
bf5438fc JB	208	extern struct jump_entry __start___jump_table[];
	209	extern struct jump_entry __stop___jump_table[];
	210
97ce2c88	211	extern void jump_label_init(void);
91bad2f8 JB	212	extern void jump_label_lock(void);
91bad2f8 JB	213	extern void jump_label_unlock(void);
bf5438fc	214	extern void arch_jump_label_transform(struct jump_entry *entry,
37348804	215	enum jump_label_type type);
20284aa7 JF	216	extern void arch_jump_label_transform_static(struct jump_entry *entry,
20284aa7 JF	217	enum jump_label_type type);
4c3ef6d7	218	extern int jump_label_text_reserved(void start, void end);
c5905afb IM	219	extern void static_key_slow_inc(struct static_key *key);
c5905afb IM	220	extern void static_key_slow_dec(struct static_key *key);
ce48c146 PZ	221	extern void static_key_slow_inc_cpuslocked(struct static_key *key);
ce48c146 PZ	222	extern void static_key_slow_dec_cpuslocked(struct static_key *key);
d430d3d7	223	extern void jump_label_apply_nops(struct module *mod);
1f69bf9c JB	224	extern int static_key_count(struct static_key *key);
	225	extern void static_key_enable(struct static_key *key);
	226	extern void static_key_disable(struct static_key *key);
5a40527f MZ	227	extern void static_key_enable_cpuslocked(struct static_key *key);
5a40527f MZ	228	extern void static_key_disable_cpuslocked(struct static_key *key);
c5905afb	229
1f69bf9c JB	230	/*
	231	* We should be using ATOMIC_INIT() for initializing .enabled, but
	232	* the inclusion of atomic.h is problematic for inclusion of jump_label.h
	233	* in 'low-level' headers. Thus, we are initializing .enabled with a
	234	* raw value, but have added a BUILD_BUG_ON() to catch any issues in
	235	* jump_label_init() see: kernel/jump_label.c.
	236	*/
11276d53	237	#define STATIC_KEY_INIT_TRUE \
1f69bf9c	238	{ .enabled = { 1 }, \
cd8d860d	239	{ .entries = (void *)JUMP_TYPE_TRUE } }
11276d53	240	#define STATIC_KEY_INIT_FALSE \
1f69bf9c	241	{ .enabled = { 0 }, \
cd8d860d	242	{ .entries = (void *)JUMP_TYPE_FALSE } }
bf5438fc	243
e9666d10	244	#else /* !CONFIG_JUMP_LABEL */
bf5438fc	245
1f69bf9c JB	246	#include <linux/atomic.h>
	247	#include <linux/bug.h>
	248
4c5ea0a9 PB	249	static inline int static_key_count(struct static_key *key)
	250	{
	251	return atomic_read(&key->enabled);
	252	}
	253
97ce2c88 JF	254	static __always_inline void jump_label_init(void)
97ce2c88 JF	255	{
c4b2c0c5	256	static_key_initialized = true;
97ce2c88 JF	257	}
97ce2c88 JF	258
c5905afb IM	259	static __always_inline bool static_key_false(struct static_key *key)
c5905afb IM	260	{
ea5e9539	261	if (unlikely(static_key_count(key) > 0))
c5905afb IM	262	return true;
	263	return false;
	264	}
	265
	266	static __always_inline bool static_key_true(struct static_key *key)
d430d3d7	267	{
ea5e9539	268	if (likely(static_key_count(key) > 0))
d430d3d7 JB	269	return true;
	270	return false;
	271	}
bf5438fc	272
c5905afb	273	static inline void static_key_slow_inc(struct static_key *key)
d430d3d7	274	{
5cdda511	275	STATIC_KEY_CHECK_USE(key);
d430d3d7 JB	276	atomic_inc(&key->enabled);
d430d3d7 JB	277	}
bf5438fc	278
c5905afb	279	static inline void static_key_slow_dec(struct static_key *key)
bf5438fc	280	{
5cdda511	281	STATIC_KEY_CHECK_USE(key);
d430d3d7	282	atomic_dec(&key->enabled);
bf5438fc JB	283	}
bf5438fc JB	284
ce48c146 PZ	285	#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
	286	#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
	287
4c3ef6d7 JB	288	static inline int jump_label_text_reserved(void start, void end)
	289	{
	290	return 0;
	291	}
	292
91bad2f8 JB	293	static inline void jump_label_lock(void) {}
	294	static inline void jump_label_unlock(void) {}
	295
d430d3d7 JB	296	static inline int jump_label_apply_nops(struct module *mod)
	297	{
	298	return 0;
	299	}
b2029520	300
e33886b3 PZ	301	static inline void static_key_enable(struct static_key *key)
e33886b3 PZ	302	{
5cdda511	303	STATIC_KEY_CHECK_USE(key);
e33886b3	304
1dbb6704 PB	305	if (atomic_read(&key->enabled) != 0) {
	306	WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
	307	return;
	308	}
	309	atomic_set(&key->enabled, 1);
e33886b3 PZ	310	}
	311
	312	static inline void static_key_disable(struct static_key *key)
	313	{
5cdda511	314	STATIC_KEY_CHECK_USE(key);
e33886b3	315
1dbb6704 PB	316	if (atomic_read(&key->enabled) != 1) {
	317	WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
	318	return;
	319	}
	320	atomic_set(&key->enabled, 0);
e33886b3 PZ	321	}
e33886b3 PZ	322
5a40527f MZ	323	#define static_key_enable_cpuslocked(k) static_key_enable((k))
	324	#define static_key_disable_cpuslocked(k) static_key_disable((k))
	325
1f69bf9c JB	326	#define STATIC_KEY_INIT_TRUE { .enabled = ATOMIC_INIT(1) }
	327	#define STATIC_KEY_INIT_FALSE { .enabled = ATOMIC_INIT(0) }
	328
e9666d10	329	#endif /* CONFIG_JUMP_LABEL */
1f69bf9c JB	330
	331	#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
	332	#define jump_label_enabled static_key_enabled
	333
11276d53 PZ	334	/* -------------------------------------------------------------------------- */
	335
	336	/*
	337	* Two type wrappers around static_key, such that we can use compile time
	338	* type differentiation to emit the right code.
	339	*
	340	* All the below code is macros in order to play type games.
	341	*/
	342
	343	struct static_key_true {
	344	struct static_key key;
	345	};
	346
	347	struct static_key_false {
	348	struct static_key key;
	349	};
	350
	351	#define STATIC_KEY_TRUE_INIT (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE, }
	352	#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }
	353
	354	#define DEFINE_STATIC_KEY_TRUE(name) \
	355	struct static_key_true name = STATIC_KEY_TRUE_INIT
	356
b5cb15d9 CR	357	#define DEFINE_STATIC_KEY_TRUE_RO(name) \
	358	struct static_key_true name __ro_after_init = STATIC_KEY_TRUE_INIT
	359
b8fb0378 TL	360	#define DECLARE_STATIC_KEY_TRUE(name) \
	361	extern struct static_key_true name
	362
11276d53 PZ	363	#define DEFINE_STATIC_KEY_FALSE(name) \
	364	struct static_key_false name = STATIC_KEY_FALSE_INIT
	365
b5cb15d9 CR	366	#define DEFINE_STATIC_KEY_FALSE_RO(name) \
	367	struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT
	368
b8fb0378 TL	369	#define DECLARE_STATIC_KEY_FALSE(name) \
	370	extern struct static_key_false name
	371
ef0da55a CM	372	#define DEFINE_STATIC_KEY_ARRAY_TRUE(name, count) \
	373	struct static_key_true name[count] = { \
	374	[0 ... (count) - 1] = STATIC_KEY_TRUE_INIT, \
	375	}
	376
	377	#define DEFINE_STATIC_KEY_ARRAY_FALSE(name, count) \
	378	struct static_key_false name[count] = { \
	379	[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \
	380	}
	381
fa128fd7 TH	382	extern bool ____wrong_branch_error(void);
	383
	384	#define static_key_enabled(x) \
	385	({ \
	386	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) && \
	387	!__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
	388	!__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	389	____wrong_branch_error(); \
	390	static_key_count((struct static_key *)x) > 0; \
	391	})
	392
e9666d10	393	#ifdef CONFIG_JUMP_LABEL
11276d53 PZ	394
	395	/*
	396	* Combine the right initial value (type) with the right branch order
	397	* to generate the desired result.
	398	*
	399	*
	400	* type\branch\| likely (1) \| unlikely (0)
	401	* -----------+-----------------------+------------------
	402	* \| \|
	403	* true (1) \| ... \| ...
	404	* \| NOP \| JMP L
	405	* \| <br-stmts> \| 1: ...
	406	* \| L: ... \|
	407	* \| \|
	408	* \| \| L: <br-stmts>
	409	* \| \| jmp 1b
	410	* \| \|
	411	* -----------+-----------------------+------------------
	412	* \| \|
	413	* false (0) \| ... \| ...
	414	* \| JMP L \| NOP
	415	* \| <br-stmts> \| 1: ...
	416	* \| L: ... \|
	417	* \| \|
	418	* \| \| L: <br-stmts>
	419	* \| \| jmp 1b
	420	* \| \|
	421	* -----------+-----------------------+------------------
	422	*
	423	* The initial value is encoded in the LSB of static_key::entries,
	424	* type: 0 = false, 1 = true.
	425	*
	426	* The branch type is encoded in the LSB of jump_entry::key,
	427	* branch: 0 = unlikely, 1 = likely.
	428	*
	429	* This gives the following logic table:
	430	*
	431	* enabled type branch instuction
	432	* -----------------------------+-----------
	433	* 0 0 0 \| NOP
	434	* 0 0 1 \| JMP
	435	* 0 1 0 \| NOP
	436	* 0 1 1 \| JMP
	437	*
	438	* 1 0 0 \| JMP
	439	* 1 0 1 \| NOP
	440	* 1 1 0 \| JMP
	441	* 1 1 1 \| NOP
	442	*
	443	* Which gives the following functions:
	444	*
	445	* dynamic: instruction = enabled ^ branch
	446	* static: instruction = type ^ branch
	447	*
	448	* See jump_label_type() / jump_label_init_type().
	449	*/
	450
11276d53 PZ	451	#define static_branch_likely(x) \
	452	({ \
	453	bool branch; \
	454	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	455	branch = !arch_static_branch(&(x)->key, true); \
	456	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	457	branch = !arch_static_branch_jump(&(x)->key, true); \
	458	else \
	459	branch = ____wrong_branch_error(); \
81dcf89f	460	likely(branch); \
11276d53 PZ	461	})
	462
	463	#define static_branch_unlikely(x) \
	464	({ \
	465	bool branch; \
	466	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	467	branch = arch_static_branch_jump(&(x)->key, false); \
	468	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	469	branch = arch_static_branch(&(x)->key, false); \
	470	else \
	471	branch = ____wrong_branch_error(); \
81dcf89f	472	unlikely(branch); \
11276d53 PZ	473	})
11276d53 PZ	474
e9666d10	475	#else /* !CONFIG_JUMP_LABEL */
11276d53 PZ	476
	477	#define static_branch_likely(x) likely(static_key_enabled(&(x)->key))
	478	#define static_branch_unlikely(x) unlikely(static_key_enabled(&(x)->key))
	479
e9666d10	480	#endif /* CONFIG_JUMP_LABEL */
11276d53 PZ	481
	482	/*
	483	* Advanced usage; refcount, branch is enabled when: count != 0
	484	*/
	485
	486	#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
	487	#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
ce48c146 PZ	488	#define static_branch_inc_cpuslocked(x) static_key_slow_inc_cpuslocked(&(x)->key)
ce48c146 PZ	489	#define static_branch_dec_cpuslocked(x) static_key_slow_dec_cpuslocked(&(x)->key)
11276d53 PZ	490
	491	/*
	492	* Normal usage; boolean enable/disable.
	493	*/
	494
5a40527f MZ	495	#define static_branch_enable(x) static_key_enable(&(x)->key)
	496	#define static_branch_disable(x) static_key_disable(&(x)->key)
	497	#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key)
	498	#define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key)
11276d53	499
c0ccf6f9	500	#endif /* __ASSEMBLY__ */
85b36c93 LR	501
85b36c93 LR	502	#endif /* _LINUX_JUMP_LABEL_H */