[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/staging/static-keys.rst
 */

#ifndef __ASSEMBLY__

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

struct static_key {
	atomic_t enabled;
#ifdef CONFIG_JUMP_LABEL
/*
 * 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;
	};
#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, bool set)
{
	if (set)
		entry->key |= 2;
	else
		entry->key &= ~2;
}

static inline int jump_entry_size(struct jump_entry *entry)
{
#ifdef JUMP_LABEL_NOP_SIZE
	return JUMP_LABEL_NOP_SIZE;
#else
	return arch_jump_entry_size(entry);
#endif
}

#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_init_ro(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 bool arch_jump_label_transform_queue(struct jump_entry *entry,
					    enum jump_label_type type);
extern void arch_jump_label_transform_apply(void);
extern int jump_label_text_reserved(void *start, void *end);
extern bool static_key_slow_inc(struct static_key *key);
extern bool static_key_fast_inc_not_disabled(struct static_key *key);
extern void static_key_slow_dec(struct static_key *key);
extern bool static_key_slow_inc_cpuslocked(struct static_key *key);
extern void static_key_slow_dec_cpuslocked(struct static_key *key);
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);
extern enum jump_label_type jump_label_init_type(struct jump_entry *entry);

/*
 * 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 },					\
	  { .type = JUMP_TYPE_TRUE } }
#define STATIC_KEY_INIT_FALSE					\
	{ .enabled = { 0 },					\
	  { .type = JUMP_TYPE_FALSE } }

#else  /* !CONFIG_JUMP_LABEL */

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

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

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

static __always_inline void jump_label_init_ro(void) { }

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

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

static inline bool static_key_fast_inc_not_disabled(struct static_key *key)
{
	int v;

	STATIC_KEY_CHECK_USE(key);
	/*
	 * Prevent key->enabled getting negative to follow the same semantics
	 * as for CONFIG_JUMP_LABEL=y, see kernel/jump_label.c comment.
	 */
	v = atomic_read(&key->enabled);
	do {
		if (v < 0 || (v + 1) < 0)
			return false;
	} while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1)));
	return true;
}
#define static_key_slow_inc(key)	static_key_fast_inc_not_disabled(key)

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 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_LOCK_GUARD_0(jump_label_lock, jump_label_lock(), jump_label_unlock())

#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,	\
	}

#define _DEFINE_STATIC_KEY_1(name)	DEFINE_STATIC_KEY_TRUE(name)
#define _DEFINE_STATIC_KEY_0(name)	DEFINE_STATIC_KEY_FALSE(name)
#define DEFINE_STATIC_KEY_MAYBE(cfg, name)			\
	__PASTE(_DEFINE_STATIC_KEY_, IS_ENABLED(cfg))(name)

#define _DEFINE_STATIC_KEY_RO_1(name)	DEFINE_STATIC_KEY_TRUE_RO(name)
#define _DEFINE_STATIC_KEY_RO_0(name)	DEFINE_STATIC_KEY_FALSE_RO(name)
#define DEFINE_STATIC_KEY_MAYBE_RO(cfg, name)			\
	__PASTE(_DEFINE_STATIC_KEY_RO_, IS_ENABLED(cfg))(name)

#define _DECLARE_STATIC_KEY_1(name)	DECLARE_STATIC_KEY_TRUE(name)
#define _DECLARE_STATIC_KEY_0(name)	DECLARE_STATIC_KEY_FALSE(name)
#define DECLARE_STATIC_KEY_MAYBE(cfg, name)			\
	__PASTE(_DECLARE_STATIC_KEY_, IS_ENABLED(cfg))(name)

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_notrace(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_notrace(branch);							\
})

#else /* !CONFIG_JUMP_LABEL */

#define static_branch_likely(x)		likely_notrace(static_key_enabled(&(x)->key))
#define static_branch_unlikely(x)	unlikely_notrace(static_key_enabled(&(x)->key))

#endif /* CONFIG_JUMP_LABEL */

#define static_branch_maybe(config, x)					\
	(IS_ENABLED(config) ? static_branch_likely(x)			\
			    : static_branch_unlikely(x))

/*
 * 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	*
8e2a46a4	71	* Additional babbling in: Documentation/staging/static-keys.rst
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>
e2b6e5e4	78	#include <linux/cleanup.h>
c4b2c0c5 HFS	79
	80	extern bool static_key_initialized;
	81
5cdda511 BP	82	#define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized, \
	83	"%s(): static key '%pS' used before call to jump_label_init()", \
	84	__func__, (key))
d430d3d7	85
c5905afb	86	struct static_key {
d430d3d7	87	atomic_t enabled;
cd27ccfc	88	#ifdef CONFIG_JUMP_LABEL
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	};
cd27ccfc	107	#endif /* CONFIG_JUMP_LABEL */
d430d3d7 JB	108	};
d430d3d7 JB	109
c0ccf6f9 AB	110	#endif /* __ASSEMBLY__ */
c0ccf6f9 AB	111
e9666d10	112	#ifdef CONFIG_JUMP_LABEL
c0ccf6f9	113	#include <asm/jump_label.h>
9ae033ac AB	114
9ae033ac AB	115	#ifndef __ASSEMBLY__
50ff18ab AB	116	#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
	117
	118	struct jump_entry {
	119	s32 code;
	120	s32 target;
	121	long key; // key may be far away from the core kernel under KASLR
	122	};
	123
	124	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	125	{
	126	return (unsigned long)&entry->code + entry->code;
	127	}
	128
	129	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	130	{
	131	return (unsigned long)&entry->target + entry->target;
	132	}
	133
	134	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	135	{
19483677	136	long offset = entry->key & ~3L;
50ff18ab AB	137
	138	return (struct static_key *)((unsigned long)&entry->key + offset);
	139	}
	140
	141	#else
9ae033ac AB	142
	143	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	144	{
	145	return entry->code;
	146	}
	147
	148	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	149	{
	150	return entry->target;
	151	}
	152
	153	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	154	{
19483677	155	return (struct static_key *)((unsigned long)entry->key & ~3UL);
9ae033ac AB	156	}
9ae033ac AB	157
50ff18ab AB	158	#endif
50ff18ab AB	159
9ae033ac AB	160	static inline bool jump_entry_is_branch(const struct jump_entry *entry)
	161	{
	162	return (unsigned long)entry->key & 1UL;
	163	}
	164
	165	static inline bool jump_entry_is_init(const struct jump_entry *entry)
	166	{
19483677	167	return (unsigned long)entry->key & 2UL;
9ae033ac AB	168	}
9ae033ac AB	169
5af0ea29	170	static inline void jump_entry_set_init(struct jump_entry *entry, bool set)
9ae033ac	171	{
5af0ea29 PZ	172	if (set)
	173	entry->key \|= 2;
	174	else
	175	entry->key &= ~2;
9ae033ac AB	176	}
9ae033ac AB	177
fa5e5dc3 PZ	178	static inline int jump_entry_size(struct jump_entry *entry)
	179	{
	180	#ifdef JUMP_LABEL_NOP_SIZE
	181	return JUMP_LABEL_NOP_SIZE;
	182	#else
	183	return arch_jump_entry_size(entry);
	184	#endif
	185	}
	186
9ae033ac	187	#endif
c0ccf6f9 AB	188	#endif
	189
	190	#ifndef __ASSEMBLY__
bf5438fc JB	191
bf5438fc JB	192	enum jump_label_type {
76b235c6 PZ	193	JUMP_LABEL_NOP = 0,
76b235c6 PZ	194	JUMP_LABEL_JMP,
bf5438fc JB	195	};
	196
	197	struct module;
	198
e9666d10	199	#ifdef CONFIG_JUMP_LABEL
4c5ea0a9	200
3821fd35 JB	201	#define JUMP_TYPE_FALSE 0UL
	202	#define JUMP_TYPE_TRUE 1UL
	203	#define JUMP_TYPE_LINKED 2UL
	204	#define JUMP_TYPE_MASK 3UL
c5905afb IM	205
	206	static __always_inline bool static_key_false(struct static_key *key)
	207	{
11276d53	208	return arch_static_branch(key, false);
c5905afb	209	}
d430d3d7	210
c5905afb IM	211	static __always_inline bool static_key_true(struct static_key *key)
c5905afb IM	212	{
11276d53	213	return !arch_static_branch(key, true);
c5905afb IM	214	}
c5905afb IM	215
bf5438fc JB	216	extern struct jump_entry __start___jump_table[];
	217	extern struct jump_entry __stop___jump_table[];
	218
97ce2c88	219	extern void jump_label_init(void);
91a1d97e	220	extern void jump_label_init_ro(void);
91bad2f8 JB	221	extern void jump_label_lock(void);
91bad2f8 JB	222	extern void jump_label_unlock(void);
bf5438fc	223	extern void arch_jump_label_transform(struct jump_entry *entry,
37348804	224	enum jump_label_type type);
c2ba8a15 DBO	225	extern bool arch_jump_label_transform_queue(struct jump_entry *entry,
	226	enum jump_label_type type);
	227	extern void arch_jump_label_transform_apply(void);
4c3ef6d7	228	extern int jump_label_text_reserved(void start, void end);
eb8c5072 DS	229	extern bool static_key_slow_inc(struct static_key *key);
eb8c5072 DS	230	extern bool static_key_fast_inc_not_disabled(struct static_key *key);
c5905afb	231	extern void static_key_slow_dec(struct static_key *key);
eb8c5072	232	extern bool static_key_slow_inc_cpuslocked(struct static_key *key);
ce48c146	233	extern void static_key_slow_dec_cpuslocked(struct static_key *key);
1f69bf9c JB	234	extern int static_key_count(struct static_key *key);
	235	extern void static_key_enable(struct static_key *key);
	236	extern void static_key_disable(struct static_key *key);
5a40527f MZ	237	extern void static_key_enable_cpuslocked(struct static_key *key);
5a40527f MZ	238	extern void static_key_disable_cpuslocked(struct static_key *key);
fdfd4289	239	extern enum jump_label_type jump_label_init_type(struct jump_entry *entry);
c5905afb	240
1f69bf9c JB	241	/*
	242	* We should be using ATOMIC_INIT() for initializing .enabled, but
	243	* the inclusion of atomic.h is problematic for inclusion of jump_label.h
	244	* in 'low-level' headers. Thus, we are initializing .enabled with a
	245	* raw value, but have added a BUILD_BUG_ON() to catch any issues in
	246	* jump_label_init() see: kernel/jump_label.c.
	247	*/
11276d53	248	#define STATIC_KEY_INIT_TRUE \
1f69bf9c	249	{ .enabled = { 1 }, \
fe65deb5	250	{ .type = JUMP_TYPE_TRUE } }
11276d53	251	#define STATIC_KEY_INIT_FALSE \
1f69bf9c	252	{ .enabled = { 0 }, \
fe65deb5	253	{ .type = JUMP_TYPE_FALSE } }
bf5438fc	254
e9666d10	255	#else /* !CONFIG_JUMP_LABEL */
bf5438fc	256
1f69bf9c JB	257	#include <linux/atomic.h>
	258	#include <linux/bug.h>
	259
656d054e	260	static __always_inline int static_key_count(struct static_key *key)
4c5ea0a9	261	{
0f613bfa	262	return raw_atomic_read(&key->enabled);
4c5ea0a9 PB	263	}
4c5ea0a9 PB	264
97ce2c88 JF	265	static __always_inline void jump_label_init(void)
97ce2c88 JF	266	{
c4b2c0c5	267	static_key_initialized = true;
97ce2c88 JF	268	}
97ce2c88 JF	269
91a1d97e PZ	270	static __always_inline void jump_label_init_ro(void) { }
91a1d97e PZ	271
c5905afb IM	272	static __always_inline bool static_key_false(struct static_key *key)
c5905afb IM	273	{
2f0df49c	274	if (unlikely_notrace(static_key_count(key) > 0))
c5905afb IM	275	return true;
	276	return false;
	277	}
	278
	279	static __always_inline bool static_key_true(struct static_key *key)
d430d3d7	280	{
2f0df49c	281	if (likely_notrace(static_key_count(key) > 0))
d430d3d7 JB	282	return true;
	283	return false;
	284	}
bf5438fc	285
eb8c5072	286	static inline bool static_key_fast_inc_not_disabled(struct static_key *key)
d430d3d7	287	{
eb8c5072 DS	288	int v;
eb8c5072 DS	289
5cdda511	290	STATIC_KEY_CHECK_USE(key);
eb8c5072 DS	291	/*
	292	* Prevent key->enabled getting negative to follow the same semantics
	293	* as for CONFIG_JUMP_LABEL=y, see kernel/jump_label.c comment.
	294	*/
	295	v = atomic_read(&key->enabled);
	296	do {
	297	if (v < 0 \|\| (v + 1) < 0)
	298	return false;
	299	} while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1)));
	300	return true;
d430d3d7	301	}
eb8c5072	302	#define static_key_slow_inc(key) static_key_fast_inc_not_disabled(key)
bf5438fc	303
c5905afb	304	static inline void static_key_slow_dec(struct static_key *key)
bf5438fc	305	{
5cdda511	306	STATIC_KEY_CHECK_USE(key);
d430d3d7	307	atomic_dec(&key->enabled);
bf5438fc JB	308	}
bf5438fc JB	309
ce48c146 PZ	310	#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
	311	#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
	312
4c3ef6d7 JB	313	static inline int jump_label_text_reserved(void start, void end)
	314	{
	315	return 0;
	316	}
	317
91bad2f8 JB	318	static inline void jump_label_lock(void) {}
	319	static inline void jump_label_unlock(void) {}
	320
e33886b3 PZ	321	static inline void static_key_enable(struct static_key *key)
e33886b3 PZ	322	{
5cdda511	323	STATIC_KEY_CHECK_USE(key);
e33886b3	324
1dbb6704 PB	325	if (atomic_read(&key->enabled) != 0) {
	326	WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
	327	return;
	328	}
	329	atomic_set(&key->enabled, 1);
e33886b3 PZ	330	}
	331
	332	static inline void static_key_disable(struct static_key *key)
	333	{
5cdda511	334	STATIC_KEY_CHECK_USE(key);
e33886b3	335
1dbb6704 PB	336	if (atomic_read(&key->enabled) != 1) {
	337	WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
	338	return;
	339	}
	340	atomic_set(&key->enabled, 0);
e33886b3 PZ	341	}
e33886b3 PZ	342
5a40527f MZ	343	#define static_key_enable_cpuslocked(k) static_key_enable((k))
	344	#define static_key_disable_cpuslocked(k) static_key_disable((k))
	345
1f69bf9c JB	346	#define STATIC_KEY_INIT_TRUE { .enabled = ATOMIC_INIT(1) }
	347	#define STATIC_KEY_INIT_FALSE { .enabled = ATOMIC_INIT(0) }
	348
e9666d10	349	#endif /* CONFIG_JUMP_LABEL */
1f69bf9c	350
e2b6e5e4 MHG	351	DEFINE_LOCK_GUARD_0(jump_label_lock, jump_label_lock(), jump_label_unlock())
e2b6e5e4 MHG	352
1f69bf9c JB	353	#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
	354	#define jump_label_enabled static_key_enabled
	355
11276d53 PZ	356	/* -------------------------------------------------------------------------- */
	357
	358	/*
	359	* Two type wrappers around static_key, such that we can use compile time
	360	* type differentiation to emit the right code.
	361	*
	362	* All the below code is macros in order to play type games.
	363	*/
	364
	365	struct static_key_true {
	366	struct static_key key;
	367	};
	368
	369	struct static_key_false {
	370	struct static_key key;
	371	};
	372
	373	#define STATIC_KEY_TRUE_INIT (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE, }
	374	#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }
	375
	376	#define DEFINE_STATIC_KEY_TRUE(name) \
	377	struct static_key_true name = STATIC_KEY_TRUE_INIT
	378
b5cb15d9 CR	379	#define DEFINE_STATIC_KEY_TRUE_RO(name) \
	380	struct static_key_true name __ro_after_init = STATIC_KEY_TRUE_INIT
	381
b8fb0378 TL	382	#define DECLARE_STATIC_KEY_TRUE(name) \
	383	extern struct static_key_true name
	384
11276d53 PZ	385	#define DEFINE_STATIC_KEY_FALSE(name) \
	386	struct static_key_false name = STATIC_KEY_FALSE_INIT
	387
b5cb15d9 CR	388	#define DEFINE_STATIC_KEY_FALSE_RO(name) \
	389	struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT
	390
b8fb0378 TL	391	#define DECLARE_STATIC_KEY_FALSE(name) \
	392	extern struct static_key_false name
	393
ef0da55a CM	394	#define DEFINE_STATIC_KEY_ARRAY_TRUE(name, count) \
	395	struct static_key_true name[count] = { \
	396	[0 ... (count) - 1] = STATIC_KEY_TRUE_INIT, \
	397	}
	398
	399	#define DEFINE_STATIC_KEY_ARRAY_FALSE(name, count) \
	400	struct static_key_false name[count] = { \
	401	[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \
	402	}
	403
0d66ccc1 KC	404	#define _DEFINE_STATIC_KEY_1(name) DEFINE_STATIC_KEY_TRUE(name)
	405	#define _DEFINE_STATIC_KEY_0(name) DEFINE_STATIC_KEY_FALSE(name)
	406	#define DEFINE_STATIC_KEY_MAYBE(cfg, name) \
	407	__PASTE(_DEFINE_STATIC_KEY_, IS_ENABLED(cfg))(name)
	408
	409	#define _DEFINE_STATIC_KEY_RO_1(name) DEFINE_STATIC_KEY_TRUE_RO(name)
	410	#define _DEFINE_STATIC_KEY_RO_0(name) DEFINE_STATIC_KEY_FALSE_RO(name)
	411	#define DEFINE_STATIC_KEY_MAYBE_RO(cfg, name) \
	412	__PASTE(_DEFINE_STATIC_KEY_RO_, IS_ENABLED(cfg))(name)
	413
	414	#define _DECLARE_STATIC_KEY_1(name) DECLARE_STATIC_KEY_TRUE(name)
	415	#define _DECLARE_STATIC_KEY_0(name) DECLARE_STATIC_KEY_FALSE(name)
	416	#define DECLARE_STATIC_KEY_MAYBE(cfg, name) \
	417	__PASTE(_DECLARE_STATIC_KEY_, IS_ENABLED(cfg))(name)
	418
fa128fd7 TH	419	extern bool ____wrong_branch_error(void);
	420
	421	#define static_key_enabled(x) \
	422	({ \
	423	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) && \
	424	!__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
	425	!__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	426	____wrong_branch_error(); \
	427	static_key_count((struct static_key *)x) > 0; \
	428	})
	429
e9666d10	430	#ifdef CONFIG_JUMP_LABEL
11276d53 PZ	431
	432	/*
	433	* Combine the right initial value (type) with the right branch order
	434	* to generate the desired result.
	435	*
	436	*
	437	* type\branch\| likely (1) \| unlikely (0)
	438	* -----------+-----------------------+------------------
	439	* \| \|
	440	* true (1) \| ... \| ...
	441	* \| NOP \| JMP L
	442	* \| <br-stmts> \| 1: ...
	443	* \| L: ... \|
	444	* \| \|
	445	* \| \| L: <br-stmts>
	446	* \| \| jmp 1b
	447	* \| \|
	448	* -----------+-----------------------+------------------
	449	* \| \|
	450	* false (0) \| ... \| ...
	451	* \| JMP L \| NOP
	452	* \| <br-stmts> \| 1: ...
	453	* \| L: ... \|
	454	* \| \|
	455	* \| \| L: <br-stmts>
	456	* \| \| jmp 1b
	457	* \| \|
	458	* -----------+-----------------------+------------------
	459	*
	460	* The initial value is encoded in the LSB of static_key::entries,
	461	* type: 0 = false, 1 = true.
	462	*
	463	* The branch type is encoded in the LSB of jump_entry::key,
	464	* branch: 0 = unlikely, 1 = likely.
	465	*
	466	* This gives the following logic table:
	467	*
	468	* enabled type branch instuction
	469	* -----------------------------+-----------
	470	* 0 0 0 \| NOP
	471	* 0 0 1 \| JMP
	472	* 0 1 0 \| NOP
	473	* 0 1 1 \| JMP
	474	*
	475	* 1 0 0 \| JMP
	476	* 1 0 1 \| NOP
	477	* 1 1 0 \| JMP
	478	* 1 1 1 \| NOP
	479	*
	480	* Which gives the following functions:
	481	*
	482	* dynamic: instruction = enabled ^ branch
	483	* static: instruction = type ^ branch
	484	*
	485	* See jump_label_type() / jump_label_init_type().
	486	*/
	487
11276d53 PZ	488	#define static_branch_likely(x) \
	489	({ \
	490	bool branch; \
	491	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	492	branch = !arch_static_branch(&(x)->key, true); \
	493	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	494	branch = !arch_static_branch_jump(&(x)->key, true); \
	495	else \
	496	branch = ____wrong_branch_error(); \
2f0df49c	497	likely_notrace(branch); \
11276d53 PZ	498	})
	499
	500	#define static_branch_unlikely(x) \
	501	({ \
	502	bool branch; \
	503	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	504	branch = arch_static_branch_jump(&(x)->key, false); \
	505	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	506	branch = arch_static_branch(&(x)->key, false); \
	507	else \
	508	branch = ____wrong_branch_error(); \
2f0df49c	509	unlikely_notrace(branch); \
11276d53 PZ	510	})
11276d53 PZ	511
e9666d10	512	#else /* !CONFIG_JUMP_LABEL */
11276d53	513
2f0df49c SRV	514	#define static_branch_likely(x) likely_notrace(static_key_enabled(&(x)->key))
2f0df49c SRV	515	#define static_branch_unlikely(x) unlikely_notrace(static_key_enabled(&(x)->key))
11276d53	516
e9666d10	517	#endif /* CONFIG_JUMP_LABEL */
11276d53	518
0d66ccc1 KC	519	#define static_branch_maybe(config, x) \
	520	(IS_ENABLED(config) ? static_branch_likely(x) \
	521	: static_branch_unlikely(x))
	522
11276d53 PZ	523	/*
	524	* Advanced usage; refcount, branch is enabled when: count != 0
	525	*/
	526
	527	#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
	528	#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
ce48c146 PZ	529	#define static_branch_inc_cpuslocked(x) static_key_slow_inc_cpuslocked(&(x)->key)
ce48c146 PZ	530	#define static_branch_dec_cpuslocked(x) static_key_slow_dec_cpuslocked(&(x)->key)
11276d53 PZ	531
	532	/*
	533	* Normal usage; boolean enable/disable.
	534	*/
	535
5a40527f MZ	536	#define static_branch_enable(x) static_key_enable(&(x)->key)
	537	#define static_branch_disable(x) static_key_disable(&(x)->key)
	538	#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key)
	539	#define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key)
11276d53	540
c0ccf6f9	541	#endif /* __ASSEMBLY__ */
85b36c93 LR	542
85b36c93 LR	543	#endif /* _LINUX_JUMP_LABEL_H */