[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))

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 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
c5905afb	85	struct static_key {
d430d3d7	86	atomic_t enabled;
cd27ccfc	87	#ifdef CONFIG_JUMP_LABEL
3821fd35	88	/*
b17ef2ed SRV	89	* Note:
	90	* To make anonymous unions work with old compilers, the static
	91	* initialization of them requires brackets. This creates a dependency
	92	* on the order of the struct with the initializers. If any fields
	93	* are added, STATIC_KEY_INIT_TRUE and STATIC_KEY_INIT_FALSE may need
	94	* to be modified.
	95	*
3821fd35 JB	96	* bit 0 => 1 if key is initially true
	97	* 0 if initially false
	98	* bit 1 => 1 if points to struct static_key_mod
	99	* 0 if points to struct jump_entry
	100	*/
	101	union {
	102	unsigned long type;
	103	struct jump_entry *entries;
	104	struct static_key_mod *next;
	105	};
cd27ccfc	106	#endif /* CONFIG_JUMP_LABEL */
d430d3d7 JB	107	};
d430d3d7 JB	108
c0ccf6f9 AB	109	#endif /* __ASSEMBLY__ */
c0ccf6f9 AB	110
e9666d10	111	#ifdef CONFIG_JUMP_LABEL
c0ccf6f9	112	#include <asm/jump_label.h>
9ae033ac AB	113
9ae033ac AB	114	#ifndef __ASSEMBLY__
50ff18ab AB	115	#ifdef CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE
	116
	117	struct jump_entry {
	118	s32 code;
	119	s32 target;
	120	long key; // key may be far away from the core kernel under KASLR
	121	};
	122
	123	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	124	{
	125	return (unsigned long)&entry->code + entry->code;
	126	}
	127
	128	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	129	{
	130	return (unsigned long)&entry->target + entry->target;
	131	}
	132
	133	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	134	{
19483677	135	long offset = entry->key & ~3L;
50ff18ab AB	136
	137	return (struct static_key *)((unsigned long)&entry->key + offset);
	138	}
	139
	140	#else
9ae033ac AB	141
	142	static inline unsigned long jump_entry_code(const struct jump_entry *entry)
	143	{
	144	return entry->code;
	145	}
	146
	147	static inline unsigned long jump_entry_target(const struct jump_entry *entry)
	148	{
	149	return entry->target;
	150	}
	151
	152	static inline struct static_key jump_entry_key(const struct jump_entry entry)
	153	{
19483677	154	return (struct static_key *)((unsigned long)entry->key & ~3UL);
9ae033ac AB	155	}
9ae033ac AB	156
50ff18ab AB	157	#endif
50ff18ab AB	158
9ae033ac AB	159	static inline bool jump_entry_is_branch(const struct jump_entry *entry)
	160	{
	161	return (unsigned long)entry->key & 1UL;
	162	}
	163
	164	static inline bool jump_entry_is_init(const struct jump_entry *entry)
	165	{
19483677	166	return (unsigned long)entry->key & 2UL;
9ae033ac AB	167	}
9ae033ac AB	168
5af0ea29	169	static inline void jump_entry_set_init(struct jump_entry *entry, bool set)
9ae033ac	170	{
5af0ea29 PZ	171	if (set)
	172	entry->key \|= 2;
	173	else
	174	entry->key &= ~2;
9ae033ac AB	175	}
9ae033ac AB	176
fa5e5dc3 PZ	177	static inline int jump_entry_size(struct jump_entry *entry)
	178	{
	179	#ifdef JUMP_LABEL_NOP_SIZE
	180	return JUMP_LABEL_NOP_SIZE;
	181	#else
	182	return arch_jump_entry_size(entry);
	183	#endif
	184	}
	185
9ae033ac	186	#endif
c0ccf6f9 AB	187	#endif
	188
	189	#ifndef __ASSEMBLY__
bf5438fc JB	190
bf5438fc JB	191	enum jump_label_type {
76b235c6 PZ	192	JUMP_LABEL_NOP = 0,
76b235c6 PZ	193	JUMP_LABEL_JMP,
bf5438fc JB	194	};
	195
	196	struct module;
	197
e9666d10	198	#ifdef CONFIG_JUMP_LABEL
4c5ea0a9	199
3821fd35 JB	200	#define JUMP_TYPE_FALSE 0UL
	201	#define JUMP_TYPE_TRUE 1UL
	202	#define JUMP_TYPE_LINKED 2UL
	203	#define JUMP_TYPE_MASK 3UL
c5905afb IM	204
	205	static __always_inline bool static_key_false(struct static_key *key)
	206	{
11276d53	207	return arch_static_branch(key, false);
c5905afb	208	}
d430d3d7	209
c5905afb IM	210	static __always_inline bool static_key_true(struct static_key *key)
c5905afb IM	211	{
11276d53	212	return !arch_static_branch(key, true);
c5905afb IM	213	}
c5905afb IM	214
bf5438fc JB	215	extern struct jump_entry __start___jump_table[];
	216	extern struct jump_entry __stop___jump_table[];
	217
97ce2c88	218	extern void jump_label_init(void);
91a1d97e	219	extern void jump_label_init_ro(void);
91bad2f8 JB	220	extern void jump_label_lock(void);
91bad2f8 JB	221	extern void jump_label_unlock(void);
bf5438fc	222	extern void arch_jump_label_transform(struct jump_entry *entry,
37348804	223	enum jump_label_type type);
c2ba8a15 DBO	224	extern bool arch_jump_label_transform_queue(struct jump_entry *entry,
	225	enum jump_label_type type);
	226	extern void arch_jump_label_transform_apply(void);
4c3ef6d7	227	extern int jump_label_text_reserved(void start, void end);
eb8c5072 DS	228	extern bool static_key_slow_inc(struct static_key *key);
eb8c5072 DS	229	extern bool static_key_fast_inc_not_disabled(struct static_key *key);
c5905afb	230	extern void static_key_slow_dec(struct static_key *key);
eb8c5072	231	extern bool static_key_slow_inc_cpuslocked(struct static_key *key);
ce48c146	232	extern void static_key_slow_dec_cpuslocked(struct static_key *key);
1f69bf9c JB	233	extern int static_key_count(struct static_key *key);
	234	extern void static_key_enable(struct static_key *key);
	235	extern void static_key_disable(struct static_key *key);
5a40527f MZ	236	extern void static_key_enable_cpuslocked(struct static_key *key);
5a40527f MZ	237	extern void static_key_disable_cpuslocked(struct static_key *key);
fdfd4289	238	extern enum jump_label_type jump_label_init_type(struct jump_entry *entry);
c5905afb	239
1f69bf9c JB	240	/*
	241	* We should be using ATOMIC_INIT() for initializing .enabled, but
	242	* the inclusion of atomic.h is problematic for inclusion of jump_label.h
	243	* in 'low-level' headers. Thus, we are initializing .enabled with a
	244	* raw value, but have added a BUILD_BUG_ON() to catch any issues in
	245	* jump_label_init() see: kernel/jump_label.c.
	246	*/
11276d53	247	#define STATIC_KEY_INIT_TRUE \
1f69bf9c	248	{ .enabled = { 1 }, \
fe65deb5	249	{ .type = JUMP_TYPE_TRUE } }
11276d53	250	#define STATIC_KEY_INIT_FALSE \
1f69bf9c	251	{ .enabled = { 0 }, \
fe65deb5	252	{ .type = JUMP_TYPE_FALSE } }
bf5438fc	253
e9666d10	254	#else /* !CONFIG_JUMP_LABEL */
bf5438fc	255
1f69bf9c JB	256	#include <linux/atomic.h>
	257	#include <linux/bug.h>
	258
656d054e	259	static __always_inline int static_key_count(struct static_key *key)
4c5ea0a9	260	{
0f613bfa	261	return raw_atomic_read(&key->enabled);
4c5ea0a9 PB	262	}
4c5ea0a9 PB	263
97ce2c88 JF	264	static __always_inline void jump_label_init(void)
97ce2c88 JF	265	{
c4b2c0c5	266	static_key_initialized = true;
97ce2c88 JF	267	}
97ce2c88 JF	268
91a1d97e PZ	269	static __always_inline void jump_label_init_ro(void) { }
91a1d97e PZ	270
c5905afb IM	271	static __always_inline bool static_key_false(struct static_key *key)
c5905afb IM	272	{
2f0df49c	273	if (unlikely_notrace(static_key_count(key) > 0))
c5905afb IM	274	return true;
	275	return false;
	276	}
	277
	278	static __always_inline bool static_key_true(struct static_key *key)
d430d3d7	279	{
2f0df49c	280	if (likely_notrace(static_key_count(key) > 0))
d430d3d7 JB	281	return true;
	282	return false;
	283	}
bf5438fc	284
eb8c5072	285	static inline bool static_key_fast_inc_not_disabled(struct static_key *key)
d430d3d7	286	{
eb8c5072 DS	287	int v;
eb8c5072 DS	288
5cdda511	289	STATIC_KEY_CHECK_USE(key);
eb8c5072 DS	290	/*
	291	* Prevent key->enabled getting negative to follow the same semantics
	292	* as for CONFIG_JUMP_LABEL=y, see kernel/jump_label.c comment.
	293	*/
	294	v = atomic_read(&key->enabled);
	295	do {
	296	if (v < 0 \|\| (v + 1) < 0)
	297	return false;
	298	} while (!likely(atomic_try_cmpxchg(&key->enabled, &v, v + 1)));
	299	return true;
d430d3d7	300	}
eb8c5072	301	#define static_key_slow_inc(key) static_key_fast_inc_not_disabled(key)
bf5438fc	302
c5905afb	303	static inline void static_key_slow_dec(struct static_key *key)
bf5438fc	304	{
5cdda511	305	STATIC_KEY_CHECK_USE(key);
d430d3d7	306	atomic_dec(&key->enabled);
bf5438fc JB	307	}
bf5438fc JB	308
ce48c146 PZ	309	#define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
	310	#define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
	311
4c3ef6d7 JB	312	static inline int jump_label_text_reserved(void start, void end)
	313	{
	314	return 0;
	315	}
	316
91bad2f8 JB	317	static inline void jump_label_lock(void) {}
	318	static inline void jump_label_unlock(void) {}
	319
e33886b3 PZ	320	static inline void static_key_enable(struct static_key *key)
e33886b3 PZ	321	{
5cdda511	322	STATIC_KEY_CHECK_USE(key);
e33886b3	323
1dbb6704 PB	324	if (atomic_read(&key->enabled) != 0) {
	325	WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
	326	return;
	327	}
	328	atomic_set(&key->enabled, 1);
e33886b3 PZ	329	}
	330
	331	static inline void static_key_disable(struct static_key *key)
	332	{
5cdda511	333	STATIC_KEY_CHECK_USE(key);
e33886b3	334
1dbb6704 PB	335	if (atomic_read(&key->enabled) != 1) {
	336	WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
	337	return;
	338	}
	339	atomic_set(&key->enabled, 0);
e33886b3 PZ	340	}
e33886b3 PZ	341
5a40527f MZ	342	#define static_key_enable_cpuslocked(k) static_key_enable((k))
	343	#define static_key_disable_cpuslocked(k) static_key_disable((k))
	344
1f69bf9c JB	345	#define STATIC_KEY_INIT_TRUE { .enabled = ATOMIC_INIT(1) }
	346	#define STATIC_KEY_INIT_FALSE { .enabled = ATOMIC_INIT(0) }
	347
e9666d10	348	#endif /* CONFIG_JUMP_LABEL */
1f69bf9c JB	349
	350	#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
	351	#define jump_label_enabled static_key_enabled
	352
11276d53 PZ	353	/* -------------------------------------------------------------------------- */
	354
	355	/*
	356	* Two type wrappers around static_key, such that we can use compile time
	357	* type differentiation to emit the right code.
	358	*
	359	* All the below code is macros in order to play type games.
	360	*/
	361
	362	struct static_key_true {
	363	struct static_key key;
	364	};
	365
	366	struct static_key_false {
	367	struct static_key key;
	368	};
	369
	370	#define STATIC_KEY_TRUE_INIT (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE, }
	371	#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }
	372
	373	#define DEFINE_STATIC_KEY_TRUE(name) \
	374	struct static_key_true name = STATIC_KEY_TRUE_INIT
	375
b5cb15d9 CR	376	#define DEFINE_STATIC_KEY_TRUE_RO(name) \
	377	struct static_key_true name __ro_after_init = STATIC_KEY_TRUE_INIT
	378
b8fb0378 TL	379	#define DECLARE_STATIC_KEY_TRUE(name) \
	380	extern struct static_key_true name
	381
11276d53 PZ	382	#define DEFINE_STATIC_KEY_FALSE(name) \
	383	struct static_key_false name = STATIC_KEY_FALSE_INIT
	384
b5cb15d9 CR	385	#define DEFINE_STATIC_KEY_FALSE_RO(name) \
	386	struct static_key_false name __ro_after_init = STATIC_KEY_FALSE_INIT
	387
b8fb0378 TL	388	#define DECLARE_STATIC_KEY_FALSE(name) \
	389	extern struct static_key_false name
	390
ef0da55a CM	391	#define DEFINE_STATIC_KEY_ARRAY_TRUE(name, count) \
	392	struct static_key_true name[count] = { \
	393	[0 ... (count) - 1] = STATIC_KEY_TRUE_INIT, \
	394	}
	395
	396	#define DEFINE_STATIC_KEY_ARRAY_FALSE(name, count) \
	397	struct static_key_false name[count] = { \
	398	[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT, \
	399	}
	400
0d66ccc1 KC	401	#define _DEFINE_STATIC_KEY_1(name) DEFINE_STATIC_KEY_TRUE(name)
	402	#define _DEFINE_STATIC_KEY_0(name) DEFINE_STATIC_KEY_FALSE(name)
	403	#define DEFINE_STATIC_KEY_MAYBE(cfg, name) \
	404	__PASTE(_DEFINE_STATIC_KEY_, IS_ENABLED(cfg))(name)
	405
	406	#define _DEFINE_STATIC_KEY_RO_1(name) DEFINE_STATIC_KEY_TRUE_RO(name)
	407	#define _DEFINE_STATIC_KEY_RO_0(name) DEFINE_STATIC_KEY_FALSE_RO(name)
	408	#define DEFINE_STATIC_KEY_MAYBE_RO(cfg, name) \
	409	__PASTE(_DEFINE_STATIC_KEY_RO_, IS_ENABLED(cfg))(name)
	410
	411	#define _DECLARE_STATIC_KEY_1(name) DECLARE_STATIC_KEY_TRUE(name)
	412	#define _DECLARE_STATIC_KEY_0(name) DECLARE_STATIC_KEY_FALSE(name)
	413	#define DECLARE_STATIC_KEY_MAYBE(cfg, name) \
	414	__PASTE(_DECLARE_STATIC_KEY_, IS_ENABLED(cfg))(name)
	415
fa128fd7 TH	416	extern bool ____wrong_branch_error(void);
	417
	418	#define static_key_enabled(x) \
	419	({ \
	420	if (!__builtin_types_compatible_p(typeof(*x), struct static_key) && \
	421	!__builtin_types_compatible_p(typeof(*x), struct static_key_true) &&\
	422	!__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	423	____wrong_branch_error(); \
	424	static_key_count((struct static_key *)x) > 0; \
	425	})
	426
e9666d10	427	#ifdef CONFIG_JUMP_LABEL
11276d53 PZ	428
	429	/*
	430	* Combine the right initial value (type) with the right branch order
	431	* to generate the desired result.
	432	*
	433	*
	434	* type\branch\| likely (1) \| unlikely (0)
	435	* -----------+-----------------------+------------------
	436	* \| \|
	437	* true (1) \| ... \| ...
	438	* \| NOP \| JMP L
	439	* \| <br-stmts> \| 1: ...
	440	* \| L: ... \|
	441	* \| \|
	442	* \| \| L: <br-stmts>
	443	* \| \| jmp 1b
	444	* \| \|
	445	* -----------+-----------------------+------------------
	446	* \| \|
	447	* false (0) \| ... \| ...
	448	* \| JMP L \| NOP
	449	* \| <br-stmts> \| 1: ...
	450	* \| L: ... \|
	451	* \| \|
	452	* \| \| L: <br-stmts>
	453	* \| \| jmp 1b
	454	* \| \|
	455	* -----------+-----------------------+------------------
	456	*
	457	* The initial value is encoded in the LSB of static_key::entries,
	458	* type: 0 = false, 1 = true.
	459	*
	460	* The branch type is encoded in the LSB of jump_entry::key,
	461	* branch: 0 = unlikely, 1 = likely.
	462	*
	463	* This gives the following logic table:
	464	*
	465	* enabled type branch instuction
	466	* -----------------------------+-----------
	467	* 0 0 0 \| NOP
	468	* 0 0 1 \| JMP
	469	* 0 1 0 \| NOP
	470	* 0 1 1 \| JMP
	471	*
	472	* 1 0 0 \| JMP
	473	* 1 0 1 \| NOP
	474	* 1 1 0 \| JMP
	475	* 1 1 1 \| NOP
	476	*
	477	* Which gives the following functions:
	478	*
	479	* dynamic: instruction = enabled ^ branch
	480	* static: instruction = type ^ branch
	481	*
	482	* See jump_label_type() / jump_label_init_type().
	483	*/
	484
11276d53 PZ	485	#define static_branch_likely(x) \
	486	({ \
	487	bool branch; \
	488	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	489	branch = !arch_static_branch(&(x)->key, true); \
	490	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	491	branch = !arch_static_branch_jump(&(x)->key, true); \
	492	else \
	493	branch = ____wrong_branch_error(); \
2f0df49c	494	likely_notrace(branch); \
11276d53 PZ	495	})
	496
	497	#define static_branch_unlikely(x) \
	498	({ \
	499	bool branch; \
	500	if (__builtin_types_compatible_p(typeof(*x), struct static_key_true)) \
	501	branch = arch_static_branch_jump(&(x)->key, false); \
	502	else if (__builtin_types_compatible_p(typeof(*x), struct static_key_false)) \
	503	branch = arch_static_branch(&(x)->key, false); \
	504	else \
	505	branch = ____wrong_branch_error(); \
2f0df49c	506	unlikely_notrace(branch); \
11276d53 PZ	507	})
11276d53 PZ	508
e9666d10	509	#else /* !CONFIG_JUMP_LABEL */
11276d53	510
2f0df49c SRV	511	#define static_branch_likely(x) likely_notrace(static_key_enabled(&(x)->key))
2f0df49c SRV	512	#define static_branch_unlikely(x) unlikely_notrace(static_key_enabled(&(x)->key))
11276d53	513
e9666d10	514	#endif /* CONFIG_JUMP_LABEL */
11276d53	515
0d66ccc1 KC	516	#define static_branch_maybe(config, x) \
	517	(IS_ENABLED(config) ? static_branch_likely(x) \
	518	: static_branch_unlikely(x))
	519
11276d53 PZ	520	/*
	521	* Advanced usage; refcount, branch is enabled when: count != 0
	522	*/
	523
	524	#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
	525	#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
ce48c146 PZ	526	#define static_branch_inc_cpuslocked(x) static_key_slow_inc_cpuslocked(&(x)->key)
ce48c146 PZ	527	#define static_branch_dec_cpuslocked(x) static_key_slow_dec_cpuslocked(&(x)->key)
11276d53 PZ	528
	529	/*
	530	* Normal usage; boolean enable/disable.
	531	*/
	532
5a40527f MZ	533	#define static_branch_enable(x) static_key_enable(&(x)->key)
	534	#define static_branch_disable(x) static_key_disable(&(x)->key)
	535	#define static_branch_enable_cpuslocked(x) static_key_enable_cpuslocked(&(x)->key)
	536	#define static_branch_disable_cpuslocked(x) static_key_disable_cpuslocked(&(x)->key)
11276d53	537
c0ccf6f9	538	#endif /* __ASSEMBLY__ */
85b36c93 LR	539
85b36c93 LR	540	#endif /* _LINUX_JUMP_LABEL_H */