[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>

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, 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_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 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 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_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 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,	\
	}

#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>
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	}
9ae033ac AB	173
5af0ea29	174	static inline void jump_entry_set_init(struct jump_entry *entry, bool set)
9ae033ac	175	{
5af0ea29 PZ	176	if (set)
	177	entry->key \|= 2;
	178	else
	179	entry->key &= ~2;
9ae033ac AB	180	}
9ae033ac AB	181
fa5e5dc3 PZ	182	static inline int jump_entry_size(struct jump_entry *entry)
	183	{
	184	#ifdef JUMP_LABEL_NOP_SIZE
	185	return JUMP_LABEL_NOP_SIZE;
	186	#else
	187	return arch_jump_entry_size(entry);
	188	#endif
	189	}
	190
9ae033ac	191	#endif
c0ccf6f9 AB	192	#endif
	193
	194	#ifndef __ASSEMBLY__
bf5438fc JB	195
bf5438fc JB	196	enum jump_label_type {
76b235c6 PZ	197	JUMP_LABEL_NOP = 0,
76b235c6 PZ	198	JUMP_LABEL_JMP,
bf5438fc JB	199	};
	200
	201	struct module;
	202
e9666d10	203	#ifdef CONFIG_JUMP_LABEL
4c5ea0a9	204
3821fd35 JB	205	#define JUMP_TYPE_FALSE 0UL
	206	#define JUMP_TYPE_TRUE 1UL
	207	#define JUMP_TYPE_LINKED 2UL
	208	#define JUMP_TYPE_MASK 3UL
c5905afb IM	209
	210	static __always_inline bool static_key_false(struct static_key *key)
	211	{
11276d53	212	return arch_static_branch(key, false);
c5905afb	213	}
d430d3d7	214
c5905afb IM	215	static __always_inline bool static_key_true(struct static_key *key)
c5905afb IM	216	{
11276d53	217	return !arch_static_branch(key, true);
c5905afb IM	218	}
c5905afb IM	219
bf5438fc JB	220	extern struct jump_entry __start___jump_table[];
	221	extern struct jump_entry __stop___jump_table[];
	222
97ce2c88	223	extern void jump_label_init(void);
91bad2f8 JB	224	extern void jump_label_lock(void);
91bad2f8 JB	225	extern void jump_label_unlock(void);
bf5438fc	226	extern void arch_jump_label_transform(struct jump_entry *entry,
37348804	227	enum jump_label_type type);
20284aa7 JF	228	extern void arch_jump_label_transform_static(struct jump_entry *entry,
20284aa7 JF	229	enum jump_label_type type);
c2ba8a15 DBO	230	extern bool arch_jump_label_transform_queue(struct jump_entry *entry,
	231	enum jump_label_type type);
	232	extern void arch_jump_label_transform_apply(void);
4c3ef6d7	233	extern int jump_label_text_reserved(void start, void end);
c5905afb IM	234	extern void static_key_slow_inc(struct static_key *key);
c5905afb IM	235	extern void static_key_slow_dec(struct static_key *key);
ce48c146 PZ	236	extern void static_key_slow_inc_cpuslocked(struct static_key *key);
ce48c146 PZ	237	extern void static_key_slow_dec_cpuslocked(struct static_key *key);
d430d3d7	238	extern void jump_label_apply_nops(struct module *mod);
1f69bf9c JB	239	extern int static_key_count(struct static_key *key);
	240	extern void static_key_enable(struct static_key *key);
	241	extern void static_key_disable(struct static_key *key);
5a40527f MZ	242	extern void static_key_enable_cpuslocked(struct static_key *key);
5a40527f MZ	243	extern void static_key_disable_cpuslocked(struct static_key *key);
c5905afb	244
1f69bf9c JB	245	/*
	246	* We should be using ATOMIC_INIT() for initializing .enabled, but
	247	* the inclusion of atomic.h is problematic for inclusion of jump_label.h
	248	* in 'low-level' headers. Thus, we are initializing .enabled with a
	249	* raw value, but have added a BUILD_BUG_ON() to catch any issues in
	250	* jump_label_init() see: kernel/jump_label.c.
	251	*/
11276d53	252	#define STATIC_KEY_INIT_TRUE \
1f69bf9c	253	{ .enabled = { 1 }, \
cd8d860d	254	{ .entries = (void *)JUMP_TYPE_TRUE } }
11276d53	255	#define STATIC_KEY_INIT_FALSE \
1f69bf9c	256	{ .enabled = { 0 }, \
cd8d860d	257	{ .entries = (void *)JUMP_TYPE_FALSE } }
bf5438fc	258
e9666d10	259	#else /* !CONFIG_JUMP_LABEL */
bf5438fc	260
1f69bf9c JB	261	#include <linux/atomic.h>
	262	#include <linux/bug.h>
	263
4c5ea0a9 PB	264	static inline int static_key_count(struct static_key *key)
	265	{
	266	return atomic_read(&key->enabled);
	267	}
	268
97ce2c88 JF	269	static __always_inline void jump_label_init(void)
97ce2c88 JF	270	{
c4b2c0c5	271	static_key_initialized = true;
97ce2c88 JF	272	}
97ce2c88 JF	273
c5905afb IM	274	static __always_inline bool static_key_false(struct static_key *key)
c5905afb IM	275	{
2f0df49c	276	if (unlikely_notrace(static_key_count(key) > 0))
c5905afb IM	277	return true;
	278	return false;
	279	}
	280
	281	static __always_inline bool static_key_true(struct static_key *key)
d430d3d7	282	{
2f0df49c	283	if (likely_notrace(static_key_count(key) > 0))
d430d3d7 JB	284	return true;
	285	return false;
	286	}
bf5438fc	287
c5905afb	288	static inline void static_key_slow_inc(struct static_key *key)
d430d3d7	289	{
5cdda511	290	STATIC_KEY_CHECK_USE(key);
d430d3d7 JB	291	atomic_inc(&key->enabled);
d430d3d7 JB	292	}
bf5438fc	293
c5905afb	294	static inline void static_key_slow_dec(struct static_key *key)
bf5438fc	295	{
5cdda511	296	STATIC_KEY_CHECK_USE(key);
d430d3d7	297	atomic_dec(&key->enabled);
bf5438fc JB	298	}
bf5438fc JB	299
ce48c146 PZ	300	#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
	301	#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
	302
4c3ef6d7 JB	303	static inline int jump_label_text_reserved(void start, void end)
	304	{
	305	return 0;
	306	}
	307
91bad2f8 JB	308	static inline void jump_label_lock(void) {}
	309	static inline void jump_label_unlock(void) {}
	310
d430d3d7 JB	311	static inline int jump_label_apply_nops(struct module *mod)
	312	{
	313	return 0;
	314	}
b2029520	315
e33886b3 PZ	316	static inline void static_key_enable(struct static_key *key)
e33886b3 PZ	317	{
5cdda511	318	STATIC_KEY_CHECK_USE(key);
e33886b3	319
1dbb6704 PB	320	if (atomic_read(&key->enabled) != 0) {
	321	WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
	322	return;
	323	}
	324	atomic_set(&key->enabled, 1);
e33886b3 PZ	325	}
	326
	327	static inline void static_key_disable(struct static_key *key)
	328	{
5cdda511	329	STATIC_KEY_CHECK_USE(key);
e33886b3	330
1dbb6704 PB	331	if (atomic_read(&key->enabled) != 1) {
	332	WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
	333	return;
	334	}
	335	atomic_set(&key->enabled, 0);
e33886b3 PZ	336	}
e33886b3 PZ	337
5a40527f MZ	338	#define static_key_enable_cpuslocked(k) static_key_enable((k))
	339	#define static_key_disable_cpuslocked(k) static_key_disable((k))
	340
1f69bf9c JB	341	#define STATIC_KEY_INIT_TRUE { .enabled = ATOMIC_INIT(1) }
	342	#define STATIC_KEY_INIT_FALSE { .enabled = ATOMIC_INIT(0) }
	343
e9666d10	344	#endif /* CONFIG_JUMP_LABEL */
1f69bf9c JB	345
	346	#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
	347	#define jump_label_enabled static_key_enabled
	348
11276d53 PZ	349	/* -------------------------------------------------------------------------- */
	350
	351	/*
	352	* Two type wrappers around static_key, such that we can use compile time
	353	* type differentiation to emit the right code.
	354	*
	355	* All the below code is macros in order to play type games.
	356	*/
	357
	358	struct static_key_true {
	359	struct static_key key;
	360	};
	361
	362	struct static_key_false {
	363	struct static_key key;
	364	};
	365
	366	#define STATIC_KEY_TRUE_INIT (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE, }
	367	#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }
	368
	369	#define DEFINE_STATIC_KEY_TRUE(name) \
	370	struct static_key_true name = STATIC_KEY_TRUE_INIT
	371
b5cb15d9 CR	372	#define DEFINE_STATIC_KEY_TRUE_RO(name) \
	373	struct static_key_true name __ro_after_init = STATIC_KEY_TRUE_INIT
	374
b8fb0378 TL	375	#define DECLARE_STATIC_KEY_TRUE(name) \
	376	extern struct static_key_true name
	377
11276d53 PZ	378	#define DEFINE_STATIC_KEY_FALSE(name) \
	379	struct static_key_false name = STATIC_KEY_FALSE_INIT
	380
b5cb15d9 CR	381	#define DEFINE_STATIC_KEY_FALSE_RO(name) \
	382	struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT
	383
b8fb0378 TL	384	#define DECLARE_STATIC_KEY_FALSE(name) \
	385	extern struct static_key_false name
	386
ef0da55a CM	387	#define DEFINE_STATIC_KEY_ARRAY_TRUE(name, count) \
	388	struct static_key_true name[count] = { \
	389	[0 ... (count) - 1] = STATIC_KEY_TRUE_INIT, \
	390	}
	391
	392	#define DEFINE_STATIC_KEY_ARRAY_FALSE(name, count) \
	393	struct static_key_false name[count] = { \
	394	[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \
	395	}
	396
0d66ccc1 KC	397	#define _DEFINE_STATIC_KEY_1(name) DEFINE_STATIC_KEY_TRUE(name)
	398	#define _DEFINE_STATIC_KEY_0(name) DEFINE_STATIC_KEY_FALSE(name)
	399	#define DEFINE_STATIC_KEY_MAYBE(cfg, name) \
	400	__PASTE(_DEFINE_STATIC_KEY_, IS_ENABLED(cfg))(name)
	401
	402	#define _DEFINE_STATIC_KEY_RO_1(name) DEFINE_STATIC_KEY_TRUE_RO(name)
	403	#define _DEFINE_STATIC_KEY_RO_0(name) DEFINE_STATIC_KEY_FALSE_RO(name)
	404	#define DEFINE_STATIC_KEY_MAYBE_RO(cfg, name) \
	405	__PASTE(_DEFINE_STATIC_KEY_RO_, IS_ENABLED(cfg))(name)
	406
	407	#define _DECLARE_STATIC_KEY_1(name) DECLARE_STATIC_KEY_TRUE(name)
	408	#define _DECLARE_STATIC_KEY_0(name) DECLARE_STATIC_KEY_FALSE(name)
	409	#define DECLARE_STATIC_KEY_MAYBE(cfg, name) \
	410	__PASTE(_DECLARE_STATIC_KEY_, IS_ENABLED(cfg))(name)
	411
fa128fd7 TH	412	extern bool ____wrong_branch_error(void);
	413
	414	#define static_key_enabled(x) \
	415	({ \
	416	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) && \
	417	!__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
	418	!__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	419	____wrong_branch_error(); \
	420	static_key_count((struct static_key *)x) > 0; \
	421	})
	422
e9666d10	423	#ifdef CONFIG_JUMP_LABEL
11276d53 PZ	424
	425	/*
	426	* Combine the right initial value (type) with the right branch order
	427	* to generate the desired result.
	428	*
	429	*
	430	* type\branch\| likely (1) \| unlikely (0)
	431	* -----------+-----------------------+------------------
	432	* \| \|
	433	* true (1) \| ... \| ...
	434	* \| NOP \| JMP L
	435	* \| <br-stmts> \| 1: ...
	436	* \| L: ... \|
	437	* \| \|
	438	* \| \| L: <br-stmts>
	439	* \| \| jmp 1b
	440	* \| \|
	441	* -----------+-----------------------+------------------
	442	* \| \|
	443	* false (0) \| ... \| ...
	444	* \| JMP L \| NOP
	445	* \| <br-stmts> \| 1: ...
	446	* \| L: ... \|
	447	* \| \|
	448	* \| \| L: <br-stmts>
	449	* \| \| jmp 1b
	450	* \| \|
	451	* -----------+-----------------------+------------------
	452	*
	453	* The initial value is encoded in the LSB of static_key::entries,
	454	* type: 0 = false, 1 = true.
	455	*
	456	* The branch type is encoded in the LSB of jump_entry::key,
	457	* branch: 0 = unlikely, 1 = likely.
	458	*
	459	* This gives the following logic table:
	460	*
	461	* enabled type branch instuction
	462	* -----------------------------+-----------
	463	* 0 0 0 \| NOP
	464	* 0 0 1 \| JMP
	465	* 0 1 0 \| NOP
	466	* 0 1 1 \| JMP
	467	*
	468	* 1 0 0 \| JMP
	469	* 1 0 1 \| NOP
	470	* 1 1 0 \| JMP
	471	* 1 1 1 \| NOP
	472	*
	473	* Which gives the following functions:
	474	*
	475	* dynamic: instruction = enabled ^ branch
	476	* static: instruction = type ^ branch
	477	*
	478	* See jump_label_type() / jump_label_init_type().
	479	*/
	480
11276d53 PZ	481	#define static_branch_likely(x) \
	482	({ \
	483	bool branch; \
	484	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	485	branch = !arch_static_branch(&(x)->key, true); \
	486	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	487	branch = !arch_static_branch_jump(&(x)->key, true); \
	488	else \
	489	branch = ____wrong_branch_error(); \
2f0df49c	490	likely_notrace(branch); \
11276d53 PZ	491	})
	492
	493	#define static_branch_unlikely(x) \
	494	({ \
	495	bool branch; \
	496	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	497	branch = arch_static_branch_jump(&(x)->key, false); \
	498	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	499	branch = arch_static_branch(&(x)->key, false); \
	500	else \
	501	branch = ____wrong_branch_error(); \
2f0df49c	502	unlikely_notrace(branch); \
11276d53 PZ	503	})
11276d53 PZ	504
e9666d10	505	#else /* !CONFIG_JUMP_LABEL */
11276d53	506
2f0df49c SRV	507	#define static_branch_likely(x) likely_notrace(static_key_enabled(&(x)->key))
2f0df49c SRV	508	#define static_branch_unlikely(x) unlikely_notrace(static_key_enabled(&(x)->key))
11276d53	509
e9666d10	510	#endif /* CONFIG_JUMP_LABEL */
11276d53	511
0d66ccc1 KC	512	#define static_branch_maybe(config, x) \
	513	(IS_ENABLED(config) ? static_branch_likely(x) \
	514	: static_branch_unlikely(x))
	515
11276d53 PZ	516	/*
	517	* Advanced usage; refcount, branch is enabled when: count != 0
	518	*/
	519
	520	#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
	521	#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
ce48c146 PZ	522	#define static_branch_inc_cpuslocked(x) static_key_slow_inc_cpuslocked(&(x)->key)
ce48c146 PZ	523	#define static_branch_dec_cpuslocked(x) static_key_slow_dec_cpuslocked(&(x)->key)
11276d53 PZ	524
	525	/*
	526	* Normal usage; boolean enable/disable.
	527	*/
	528
5a40527f MZ	529	#define static_branch_enable(x) static_key_enable(&(x)->key)
	530	#define static_branch_disable(x) static_key_disable(&(x)->key)
	531	#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key)
	532	#define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key)
11276d53	533
c0ccf6f9	534	#endif /* __ASSEMBLY__ */
85b36c93 LR	535
85b36c93 LR	536	#endif /* _LINUX_JUMP_LABEL_H */