[deliverable/linux.git] / include / linux / compiler.h

#ifndef __LINUX_COMPILER_H
#define __LINUX_COMPILER_H

#ifndef __ASSEMBLY__

#ifdef __CHECKER__
# define __user		__attribute__((noderef, address_space(1)))
# define __kernel	__attribute__((address_space(0)))
# define __safe		__attribute__((safe))
# define __force	__attribute__((force))
# define __nocast	__attribute__((nocast))
# define __iomem	__attribute__((noderef, address_space(2)))
# define __must_hold(x)	__attribute__((context(x,1,1)))
# define __acquires(x)	__attribute__((context(x,0,1)))
# define __releases(x)	__attribute__((context(x,1,0)))
# define __acquire(x)	__context__(x,1)
# define __release(x)	__context__(x,-1)
# define __cond_lock(x,c)	((c) ? ({ __acquire(x); 1; }) : 0)
# define __percpu	__attribute__((noderef, address_space(3)))
#ifdef CONFIG_SPARSE_RCU_POINTER
# define __rcu		__attribute__((noderef, address_space(4)))
#else
# define __rcu
# define __pmem		__attribute__((noderef, address_space(5)))
#endif
extern void __chk_user_ptr(const volatile void __user *);
extern void __chk_io_ptr(const volatile void __iomem *);
#else
# define __user
# define __kernel
# define __safe
# define __force
# define __nocast
# define __iomem
# define __chk_user_ptr(x) (void)0
# define __chk_io_ptr(x) (void)0
# define __builtin_warning(x, y...) (1)
# define __must_hold(x)
# define __acquires(x)
# define __releases(x)
# define __acquire(x) (void)0
# define __release(x) (void)0
# define __cond_lock(x,c) (c)
# define __percpu
# define __rcu
# define __pmem
#endif

/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
#define ___PASTE(a,b) a##b
#define __PASTE(a,b) ___PASTE(a,b)

#ifdef __KERNEL__

#ifdef __GNUC__
#include <linux/compiler-gcc.h>
#endif

#ifdef CC_USING_HOTPATCH
#define notrace __attribute__((hotpatch(0,0)))
#else
#define notrace __attribute__((no_instrument_function))
#endif

/* Intel compiler defines __GNUC__. So we will overwrite implementations
 * coming from above header files here
 */
#ifdef __INTEL_COMPILER
# include <linux/compiler-intel.h>
#endif

/* Clang compiler defines __GNUC__. So we will overwrite implementations
 * coming from above header files here
 */
#ifdef __clang__
#include <linux/compiler-clang.h>
#endif

/*
 * Generic compiler-dependent macros required for kernel
 * build go below this comment. Actual compiler/compiler version
 * specific implementations come from the above header files
 */

struct ftrace_branch_data {
	const char *func;
	const char *file;
	unsigned line;
	union {
		struct {
			unsigned long correct;
			unsigned long incorrect;
		};
		struct {
			unsigned long miss;
			unsigned long hit;
		};
		unsigned long miss_hit[2];
	};
};

/*
 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
 * to disable branch tracing on a per file basis.
 */
#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
    && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);

#define likely_notrace(x)	__builtin_expect(!!(x), 1)
#define unlikely_notrace(x)	__builtin_expect(!!(x), 0)

#define __branch_check__(x, expect) ({					\
			int ______r;					\
			static struct ftrace_branch_data		\
				__attribute__((__aligned__(4)))		\
				__attribute__((section("_ftrace_annotated_branch"))) \
				______f = {				\
				.func = __func__,			\
				.file = __FILE__,			\
				.line = __LINE__,			\
			};						\
			______r = likely_notrace(x);			\
			ftrace_likely_update(&______f, ______r, expect); \
			______r;					\
		})

/*
 * Using __builtin_constant_p(x) to ignore cases where the return
 * value is always the same.  This idea is taken from a similar patch
 * written by Daniel Walker.
 */
# ifndef likely
#  define likely(x)	(__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
# endif
# ifndef unlikely
#  define unlikely(x)	(__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
# endif

#ifdef CONFIG_PROFILE_ALL_BRANCHES
/*
 * "Define 'is'", Bill Clinton
 * "Define 'if'", Steven Rostedt
 */
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
#define __trace_if(cond) \
	if (__builtin_constant_p((cond)) ? !!(cond) :			\
	({								\
		int ______r;						\
		static struct ftrace_branch_data			\
			__attribute__((__aligned__(4)))			\
			__attribute__((section("_ftrace_branch")))	\
			______f = {					\
				.func = __func__,			\
				.file = __FILE__,			\
				.line = __LINE__,			\
			};						\
		______r = !!(cond);					\
		______f.miss_hit[______r]++;					\
		______r;						\
	}))
#endif /* CONFIG_PROFILE_ALL_BRANCHES */

#else
# define likely(x)	__builtin_expect(!!(x), 1)
# define unlikely(x)	__builtin_expect(!!(x), 0)
#endif

/* Optimization barrier */
#ifndef barrier
# define barrier() __memory_barrier()
#endif

#ifndef barrier_data
# define barrier_data(ptr) barrier()
#endif

/* Unreachable code */
#ifndef unreachable
# define unreachable() do { } while (1)
#endif

#ifndef RELOC_HIDE
# define RELOC_HIDE(ptr, off)					\
  ({ unsigned long __ptr;					\
     __ptr = (unsigned long) (ptr);				\
    (typeof(ptr)) (__ptr + (off)); })
#endif

#ifndef OPTIMIZER_HIDE_VAR
#define OPTIMIZER_HIDE_VAR(var) barrier()
#endif

/* Not-quite-unique ID. */
#ifndef __UNIQUE_ID
# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
#endif

#include <uapi/linux/types.h>

static __always_inline void __read_once_size(const volatile void *p, void *res, int size)
{
	switch (size) {
	case 1: *(__u8 *)res = *(volatile __u8 *)p; break;
	case 2: *(__u16 *)res = *(volatile __u16 *)p; break;
	case 4: *(__u32 *)res = *(volatile __u32 *)p; break;
	case 8: *(__u64 *)res = *(volatile __u64 *)p; break;
	default:
		barrier();
		__builtin_memcpy((void *)res, (const void *)p, size);
		barrier();
	}
}

static __always_inline void __write_once_size(volatile void *p, void *res, int size)
{
	switch (size) {
	case 1: *(volatile __u8 *)p = *(__u8 *)res; break;
	case 2: *(volatile __u16 *)p = *(__u16 *)res; break;
	case 4: *(volatile __u32 *)p = *(__u32 *)res; break;
	case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
	default:
		barrier();
		__builtin_memcpy((void *)p, (const void *)res, size);
		barrier();
	}
}

/*
 * Prevent the compiler from merging or refetching reads or writes. The
 * compiler is also forbidden from reordering successive instances of
 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
 * compiler is aware of some particular ordering.  One way to make the
 * compiler aware of ordering is to put the two invocations of READ_ONCE,
 * WRITE_ONCE or ACCESS_ONCE() in different C statements.
 *
 * In contrast to ACCESS_ONCE these two macros will also work on aggregate
 * data types like structs or unions. If the size of the accessed data
 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
 * READ_ONCE() and WRITE_ONCE()  will fall back to memcpy and print a
 * compile-time warning.
 *
 * Their two major use cases are: (1) Mediating communication between
 * process-level code and irq/NMI handlers, all running on the same CPU,
 * and (2) Ensuring that the compiler does not  fold, spindle, or otherwise
 * mutilate accesses that either do not require ordering or that interact
 * with an explicit memory barrier or atomic instruction that provides the
 * required ordering.
 */

#define READ_ONCE(x) \
	({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })

#define WRITE_ONCE(x, val) \
	({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })

/**
 * READ_ONCE_CTRL - Read a value heading a control dependency
 * @x: The value to be read, heading the control dependency
 *
 * Control dependencies are tricky.  See Documentation/memory-barriers.txt
 * for important information on how to use them.  Note that in many cases,
 * use of smp_load_acquire() will be much simpler.  Control dependencies
 * should be avoided except on the hottest of hotpaths.
 */
#define READ_ONCE_CTRL(x) \
({ \
	typeof(x) __val = READ_ONCE(x); \
	smp_read_barrier_depends(); /* Enforce control dependency. */ \
	__val; \
})

#endif /* __KERNEL__ */

#endif /* __ASSEMBLY__ */

#ifdef __KERNEL__
/*
 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 * warning for each use, in hopes of speeding the functions removal.
 * Usage is:
 * 		int __deprecated foo(void)
 */
#ifndef __deprecated
# define __deprecated		/* unimplemented */
#endif

#ifdef MODULE
#define __deprecated_for_modules __deprecated
#else
#define __deprecated_for_modules
#endif

#ifndef __must_check
#define __must_check
#endif

#ifndef CONFIG_ENABLE_MUST_CHECK
#undef __must_check
#define __must_check
#endif
#ifndef CONFIG_ENABLE_WARN_DEPRECATED
#undef __deprecated
#undef __deprecated_for_modules
#define __deprecated
#define __deprecated_for_modules
#endif

/*
 * Allow us to avoid 'defined but not used' warnings on functions and data,
 * as well as force them to be emitted to the assembly file.
 *
 * As of gcc 3.4, static functions that are not marked with attribute((used))
 * may be elided from the assembly file.  As of gcc 3.4, static data not so
 * marked will not be elided, but this may change in a future gcc version.
 *
 * NOTE: Because distributions shipped with a backported unit-at-a-time
 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 * for gcc >=3.3 instead of 3.4.
 *
 * In prior versions of gcc, such functions and data would be emitted, but
 * would be warned about except with attribute((unused)).
 *
 * Mark functions that are referenced only in inline assembly as __used so
 * the code is emitted even though it appears to be unreferenced.
 */
#ifndef __used
# define __used			/* unimplemented */
#endif

#ifndef __maybe_unused
# define __maybe_unused		/* unimplemented */
#endif

#ifndef __always_unused
# define __always_unused	/* unimplemented */
#endif

#ifndef noinline
#define noinline
#endif

/*
 * Rather then using noinline to prevent stack consumption, use
 * noinline_for_stack instead.  For documentation reasons.
 */
#define noinline_for_stack noinline

#ifndef __always_inline
#define __always_inline inline
#endif

#endif /* __KERNEL__ */

/*
 * From the GCC manual:
 *
 * Many functions do not examine any values except their arguments,
 * and have no effects except the return value.  Basically this is
 * just slightly more strict class than the `pure' attribute above,
 * since function is not allowed to read global memory.
 *
 * Note that a function that has pointer arguments and examines the
 * data pointed to must _not_ be declared `const'.  Likewise, a
 * function that calls a non-`const' function usually must not be
 * `const'.  It does not make sense for a `const' function to return
 * `void'.
 */
#ifndef __attribute_const__
# define __attribute_const__	/* unimplemented */
#endif

/*
 * Tell gcc if a function is cold. The compiler will assume any path
 * directly leading to the call is unlikely.
 */

#ifndef __cold
#define __cold
#endif

/* Simple shorthand for a section definition */
#ifndef __section
# define __section(S) __attribute__ ((__section__(#S)))
#endif

#ifndef __visible
#define __visible
#endif

/* Are two types/vars the same type (ignoring qualifiers)? */
#ifndef __same_type
# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
#endif

/* Is this type a native word size -- useful for atomic operations */
#ifndef __native_word
# define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
#endif

/* Compile time object size, -1 for unknown */
#ifndef __compiletime_object_size
# define __compiletime_object_size(obj) -1
#endif
#ifndef __compiletime_warning
# define __compiletime_warning(message)
#endif
#ifndef __compiletime_error
# define __compiletime_error(message)
/*
 * Sparse complains of variable sized arrays due to the temporary variable in
 * __compiletime_assert. Unfortunately we can't just expand it out to make
 * sparse see a constant array size without breaking compiletime_assert on old
 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
 */
# ifndef __CHECKER__
#  define __compiletime_error_fallback(condition) \
	do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
# endif
#endif
#ifndef __compiletime_error_fallback
# define __compiletime_error_fallback(condition) do { } while (0)
#endif

#define __compiletime_assert(condition, msg, prefix, suffix)		\
	do {								\
		bool __cond = !(condition);				\
		extern void prefix ## suffix(void) __compiletime_error(msg); \
		if (__cond)						\
			prefix ## suffix();				\
		__compiletime_error_fallback(__cond);			\
	} while (0)

#define _compiletime_assert(condition, msg, prefix, suffix) \
	__compiletime_assert(condition, msg, prefix, suffix)

/**
 * compiletime_assert - break build and emit msg if condition is false
 * @condition: a compile-time constant condition to check
 * @msg:       a message to emit if condition is false
 *
 * In tradition of POSIX assert, this macro will break the build if the
 * supplied condition is *false*, emitting the supplied error message if the
 * compiler has support to do so.
 */
#define compiletime_assert(condition, msg) \
	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)

#define compiletime_assert_atomic_type(t)				\
	compiletime_assert(__native_word(t),				\
		"Need native word sized stores/loads for atomicity.")

/*
 * Prevent the compiler from merging or refetching accesses.  The compiler
 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 * but only when the compiler is aware of some particular ordering.  One way
 * to make the compiler aware of ordering is to put the two invocations of
 * ACCESS_ONCE() in different C statements.
 *
 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
 * on a union member will work as long as the size of the member matches the
 * size of the union and the size is smaller than word size.
 *
 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication
 * between process-level code and irq/NMI handlers, all running on the same CPU,
 * and (2) Ensuring that the compiler does not  fold, spindle, or otherwise
 * mutilate accesses that either do not require ordering or that interact
 * with an explicit memory barrier or atomic instruction that provides the
 * required ordering.
 *
 * If possible use READ_ONCE()/WRITE_ONCE() instead.
 */
#define __ACCESS_ONCE(x) ({ \
	 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
	(volatile typeof(x) *)&(x); })
#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))

/**
 * lockless_dereference() - safely load a pointer for later dereference
 * @p: The pointer to load
 *
 * Similar to rcu_dereference(), but for situations where the pointed-to
 * object's lifetime is managed by something other than RCU.  That
 * "something other" might be reference counting or simple immortality.
 */
#define lockless_dereference(p) \
({ \
	typeof(p) _________p1 = READ_ONCE(p); \
	smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
	(_________p1); \
})

/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
#ifdef CONFIG_KPROBES
# define __kprobes	__attribute__((__section__(".kprobes.text")))
# define nokprobe_inline	__always_inline
#else
# define __kprobes
# define nokprobe_inline	inline
#endif
#endif /* __LINUX_COMPILER_H */
Commit	Line	Data
1da177e4 LT	1	#ifndef __LINUX_COMPILER_H
	2	#define __LINUX_COMPILER_H
	3
	4	#ifndef __ASSEMBLY__
	5
	6	#ifdef __CHECKER__
	7	# define __user __attribute__((noderef, address_space(1)))
e0fdb0e0	8	# define __kernel __attribute__((address_space(0)))
1da177e4 LT	9	# define __safe __attribute__((safe))
	10	# define __force __attribute__((force))
	11	# define __nocast __attribute__((nocast))
	12	# define __iomem __attribute__((noderef, address_space(2)))
8529091e	13	# define __must_hold(x) __attribute__((context(x,1,1)))
c902e0a0 JT	14	# define __acquires(x) __attribute__((context(x,0,1)))
	15	# define __releases(x) __attribute__((context(x,1,0)))
	16	# define __acquire(x) __context__(x,1)
	17	# define __release(x) __context__(x,-1)
dcc8e559	18	# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
e0fdb0e0	19	# define __percpu __attribute__((noderef, address_space(3)))
ca5ecddf PM	20	#ifdef CONFIG_SPARSE_RCU_POINTER
	21	# define __rcu __attribute__((noderef, address_space(4)))
	22	#else
71d1d5c7	23	# define __rcu
61031952	24	# define __pmem __attribute__((noderef, address_space(5)))
ca5ecddf	25	#endif
c47ffe3d AV	26	extern void __chk_user_ptr(const volatile void __user *);
c47ffe3d AV	27	extern void __chk_io_ptr(const volatile void __iomem *);
1da177e4 LT	28	#else
	29	# define __user
	30	# define __kernel
	31	# define __safe
	32	# define __force
	33	# define __nocast
	34	# define __iomem
	35	# define __chk_user_ptr(x) (void)0
	36	# define __chk_io_ptr(x) (void)0
	37	# define __builtin_warning(x, y...) (1)
8529091e	38	# define __must_hold(x)
1da177e4 LT	39	# define __acquires(x)
	40	# define __releases(x)
	41	# define __acquire(x) (void)0
	42	# define __release(x) (void)0
dcc8e559	43	# define __cond_lock(x,c) (c)
e0fdb0e0	44	# define __percpu
71d1d5c7	45	# define __rcu
61031952	46	# define __pmem
1da177e4 LT	47	#endif
1da177e4 LT	48
6f33d587 RR	49	/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
	50	#define ___PASTE(a,b) a##b
	51	#define __PASTE(a,b) ___PASTE(a,b)
	52
1da177e4 LT	53	#ifdef __KERNEL__
1da177e4 LT	54
f153b821 LT	55	#ifdef __GNUC__
f153b821 LT	56	#include <linux/compiler-gcc.h>
1da177e4 LT	57	#endif
1da177e4 LT	58
61f55214 HC	59	#ifdef CC_USING_HOTPATCH
	60	#define notrace __attribute__((hotpatch(0,0)))
	61	#else
28614889	62	#define notrace __attribute__((no_instrument_function))
61f55214	63	#endif
28614889	64
1da177e4 LT	65	/* Intel compiler defines __GNUC__. So we will overwrite implementations
	66	* coming from above header files here
	67	*/
	68	#ifdef __INTEL_COMPILER
	69	# include <linux/compiler-intel.h>
	70	#endif
	71
565cbdc2 MC	72	/* Clang compiler defines __GNUC__. So we will overwrite implementations
	73	* coming from above header files here
	74	*/
	75	#ifdef __clang__
	76	#include <linux/compiler-clang.h>
	77	#endif
	78
1da177e4 LT	79	/*
	80	* Generic compiler-dependent macros required for kernel
	81	* build go below this comment. Actual compiler/compiler version
	82	* specific implementations come from the above header files
	83	*/
	84
2ed84eeb	85	struct ftrace_branch_data {
1f0d69a9 SR	86	const char *func;
	87	const char *file;
	88	unsigned line;
2bcd521a SR	89	union {
	90	struct {
	91	unsigned long correct;
	92	unsigned long incorrect;
	93	};
	94	struct {
	95	unsigned long miss;
	96	unsigned long hit;
	97	};
97e7e4f3	98	unsigned long miss_hit[2];
2bcd521a	99	};
1f0d69a9	100	};
2ed84eeb SR	101
	102	/*
	103	* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
	104	* to disable branch tracing on a per file basis.
	105	*/
d9ad8bc0 BVA	106	#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
d9ad8bc0 BVA	107	&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
2ed84eeb	108	void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
1f0d69a9 SR	109
	110	#define likely_notrace(x) __builtin_expect(!!(x), 1)
	111	#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
	112
45b79749	113	#define __branch_check__(x, expect) ({ \
1f0d69a9	114	int ______r; \
2ed84eeb	115	static struct ftrace_branch_data \
1f0d69a9	116	__attribute__((__aligned__(4))) \
45b79749	117	__attribute__((section("_ftrace_annotated_branch"))) \
1f0d69a9 SR	118	______f = { \
	119	.func = __func__, \
	120	.file = __FILE__, \
	121	.line = __LINE__, \
	122	}; \
1f0d69a9	123	______r = likely_notrace(x); \
45b79749	124	ftrace_likely_update(&______f, ______r, expect); \
1f0d69a9 SR	125	______r; \
	126	})
	127
	128	/*
	129	* Using __builtin_constant_p(x) to ignore cases where the return
	130	* value is always the same. This idea is taken from a similar patch
	131	* written by Daniel Walker.
	132	*/
	133	# ifndef likely
45b79749	134	# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
1f0d69a9 SR	135	# endif
1f0d69a9 SR	136	# ifndef unlikely
45b79749	137	# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
1f0d69a9	138	# endif
2bcd521a SR	139
	140	#ifdef CONFIG_PROFILE_ALL_BRANCHES
	141	/*
	142	* "Define 'is'", Bill Clinton
	143	* "Define 'if'", Steven Rostedt
	144	*/
ab3c9c68 LT	145	#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
	146	#define __trace_if(cond) \
	147	if (__builtin_constant_p((cond)) ? !!(cond) : \
2bcd521a SR	148	({ \
	149	int ______r; \
	150	static struct ftrace_branch_data \
	151	__attribute__((__aligned__(4))) \
	152	__attribute__((section("_ftrace_branch"))) \
	153	______f = { \
	154	.func = __func__, \
	155	.file = __FILE__, \
	156	.line = __LINE__, \
	157	}; \
	158	______r = !!(cond); \
97e7e4f3	159	______f.miss_hit[______r]++; \
2bcd521a SR	160	______r; \
	161	}))
	162	#endif /* CONFIG_PROFILE_ALL_BRANCHES */
	163
1f0d69a9 SR	164	#else
	165	# define likely(x) __builtin_expect(!!(x), 1)
	166	# define unlikely(x) __builtin_expect(!!(x), 0)
	167	#endif
1da177e4 LT	168
	169	/* Optimization barrier */
	170	#ifndef barrier
	171	# define barrier() __memory_barrier()
	172	#endif
	173
7829fb09 DB	174	#ifndef barrier_data
	175	# define barrier_data(ptr) barrier()
	176	#endif
	177
38938c87 DD	178	/* Unreachable code */
	179	#ifndef unreachable
	180	# define unreachable() do { } while (1)
	181	#endif
	182
1da177e4 LT	183	#ifndef RELOC_HIDE
	184	# define RELOC_HIDE(ptr, off) \
	185	({ unsigned long __ptr; \
	186	__ptr = (unsigned long) (ptr); \
	187	(typeof(ptr)) (__ptr + (off)); })
	188	#endif
	189
fe8c8a12 CEB	190	#ifndef OPTIMIZER_HIDE_VAR
	191	#define OPTIMIZER_HIDE_VAR(var) barrier()
	192	#endif
	193
6f33d587 RR	194	/* Not-quite-unique ID. */
	195	#ifndef __UNIQUE_ID
	196	# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
	197	#endif
	198
230fa253 CB	199	#include <uapi/linux/types.h>
230fa253 CB	200
dd369297	201	static __always_inline void __read_once_size(const volatile void p, void res, int size)
230fa253 CB	202	{
	203	switch (size) {
	204	case 1: (__u8 )res = (volatile __u8 )p; break;
	205	case 2: (__u16 )res = (volatile __u16 )p; break;
	206	case 4: (__u32 )res = (volatile __u32 )p; break;
230fa253	207	case 8: (__u64 )res = (volatile __u64 )p; break;
230fa253 CB	208	default:
	209	barrier();
	210	__builtin_memcpy((void )res, (const void )p, size);
230fa253 CB	211	barrier();
	212	}
	213	}
	214
43239cbe	215	static __always_inline void __write_once_size(volatile void p, void res, int size)
230fa253 CB	216	{
	217	switch (size) {
	218	case 1: (volatile __u8 )p = (__u8 )res; break;
	219	case 2: (volatile __u16 )p = (__u16 )res; break;
	220	case 4: (volatile __u32 )p = (__u32 )res; break;
230fa253	221	case 8: (volatile __u64 )p = (__u64 )res; break;
230fa253 CB	222	default:
	223	barrier();
	224	__builtin_memcpy((void )p, (const void )res, size);
230fa253 CB	225	barrier();
	226	}
	227	}
	228
	229	/*
	230	* Prevent the compiler from merging or refetching reads or writes. The
	231	* compiler is also forbidden from reordering successive instances of
43239cbe	232	* READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
230fa253 CB	233	* compiler is aware of some particular ordering. One way to make the
230fa253 CB	234	* compiler aware of ordering is to put the two invocations of READ_ONCE,
43239cbe	235	* WRITE_ONCE or ACCESS_ONCE() in different C statements.
230fa253 CB	236	*
	237	* In contrast to ACCESS_ONCE these two macros will also work on aggregate
	238	* data types like structs or unions. If the size of the accessed data
	239	* type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
43239cbe	240	* READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a
230fa253 CB	241	* compile-time warning.
	242	*
	243	* Their two major use cases are: (1) Mediating communication between
	244	* process-level code and irq/NMI handlers, all running on the same CPU,
	245	* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
	246	* mutilate accesses that either do not require ordering or that interact
	247	* with an explicit memory barrier or atomic instruction that provides the
	248	* required ordering.
	249	*/
	250
	251	#define READ_ONCE(x) \
dd369297	252	({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
230fa253	253
43239cbe	254	#define WRITE_ONCE(x, val) \
ab3f02fc	255	({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
230fa253	256
5af4692a PM	257	/**
	258	* READ_ONCE_CTRL - Read a value heading a control dependency
	259	* @x: The value to be read, heading the control dependency
	260	*
	261	* Control dependencies are tricky. See Documentation/memory-barriers.txt
	262	* for important information on how to use them. Note that in many cases,
	263	* use of smp_load_acquire() will be much simpler. Control dependencies
	264	* should be avoided except on the hottest of hotpaths.
	265	*/
	266	#define READ_ONCE_CTRL(x) \
	267	({ \
	268	typeof(x) __val = READ_ONCE(x); \
	269	smp_read_barrier_depends(); /* Enforce control dependency. */ \
	270	__val; \
	271	})
	272
1da177e4 LT	273	#endif /* __KERNEL__ */
	274
	275	#endif /* __ASSEMBLY__ */
	276
4f79c3ff	277	#ifdef __KERNEL__
1da177e4 LT	278	/*
	279	* Allow us to mark functions as 'deprecated' and have gcc emit a nice
	280	* warning for each use, in hopes of speeding the functions removal.
	281	* Usage is:
	282	* int __deprecated foo(void)
	283	*/
	284	#ifndef __deprecated
	285	# define __deprecated /* unimplemented */
	286	#endif
	287
512345be PM	288	#ifdef MODULE
	289	#define __deprecated_for_modules __deprecated
	290	#else
	291	#define __deprecated_for_modules
	292	#endif
	293
1da177e4 LT	294	#ifndef __must_check
	295	#define __must_check
	296	#endif
	297
cebc04ba AM	298	#ifndef CONFIG_ENABLE_MUST_CHECK
	299	#undef __must_check
	300	#define __must_check
	301	#endif
de488443 JG	302	#ifndef CONFIG_ENABLE_WARN_DEPRECATED
	303	#undef __deprecated
	304	#undef __deprecated_for_modules
	305	#define __deprecated
	306	#define __deprecated_for_modules
	307	#endif
cebc04ba	308
1da177e4 LT	309	/*
	310	* Allow us to avoid 'defined but not used' warnings on functions and data,
	311	* as well as force them to be emitted to the assembly file.
	312	*
0d7ebbbc DR	313	* As of gcc 3.4, static functions that are not marked with attribute((used))
0d7ebbbc DR	314	* may be elided from the assembly file. As of gcc 3.4, static data not so
1da177e4 LT	315	* marked will not be elided, but this may change in a future gcc version.
1da177e4 LT	316	*
0d7ebbbc DR	317	* NOTE: Because distributions shipped with a backported unit-at-a-time
	318	* compiler in gcc 3.3, we must define __used to be __attribute__((used))
	319	* for gcc >=3.3 instead of 3.4.
	320	*
1da177e4 LT	321	* In prior versions of gcc, such functions and data would be emitted, but
1da177e4 LT	322	* would be warned about except with attribute((unused)).
0d7ebbbc DR	323	*
	324	* Mark functions that are referenced only in inline assembly as __used so
	325	* the code is emitted even though it appears to be unreferenced.
1da177e4	326	*/
0d7ebbbc DR	327	#ifndef __used
	328	# define __used /* unimplemented */
	329	#endif
	330
	331	#ifndef __maybe_unused
	332	# define __maybe_unused /* unimplemented */
1da177e4 LT	333	#endif
1da177e4 LT	334
7b2a3513 LZ	335	#ifndef __always_unused
	336	# define __always_unused /* unimplemented */
	337	#endif
	338
423bc7b2 DW	339	#ifndef noinline
	340	#define noinline
	341	#endif
	342
735c4fb9 AM	343	/*
735c4fb9 AM	344	* Rather then using noinline to prevent stack consumption, use
e6be0c9e	345	* noinline_for_stack instead. For documentation reasons.
735c4fb9 AM	346	*/
	347	#define noinline_for_stack noinline
	348
423bc7b2 DW	349	#ifndef __always_inline
	350	#define __always_inline inline
	351	#endif
	352
	353	#endif /* __KERNEL__ */
	354
1da177e4 LT	355	/*
	356	* From the GCC manual:
	357	*
	358	* Many functions do not examine any values except their arguments,
	359	* and have no effects except the return value. Basically this is
	360	* just slightly more strict class than the `pure' attribute above,
	361	* since function is not allowed to read global memory.
	362	*
	363	* Note that a function that has pointer arguments and examines the
	364	* data pointed to must _not_ be declared `const'. Likewise, a
	365	* function that calls a non-`const' function usually must not be
	366	* `const'. It does not make sense for a `const' function to return
	367	* `void'.
	368	*/
	369	#ifndef __attribute_const__
	370	# define __attribute_const__ /* unimplemented */
	371	#endif
	372
a586df06 AK	373	/*
	374	* Tell gcc if a function is cold. The compiler will assume any path
	375	* directly leading to the call is unlikely.
	376	*/
	377
	378	#ifndef __cold
	379	#define __cold
	380	#endif
	381
f3fe866d SR	382	/* Simple shorthand for a section definition */
	383	#ifndef __section
	384	# define __section(S) __attribute__ ((__section__(#S)))
	385	#endif
	386
9a858dc7 AK	387	#ifndef __visible
	388	#define __visible
	389	#endif
	390
d2c123c2 RR	391	/* Are two types/vars the same type (ignoring qualifiers)? */
	392	#ifndef __same_type
	393	# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
	394	#endif
	395
47933ad4 PZ	396	/* Is this type a native word size -- useful for atomic operations */
47933ad4 PZ	397	#ifndef __native_word
536fa402	398	# define __native_word(t) (sizeof(t) == sizeof(char) \|\| sizeof(t) == sizeof(short) \|\| sizeof(t) == sizeof(int) \|\| sizeof(t) == sizeof(long))
47933ad4 PZ	399	#endif
47933ad4 PZ	400
9f0cf4ad AV	401	/* Compile time object size, -1 for unknown */
	402	#ifndef __compiletime_object_size
	403	# define __compiletime_object_size(obj) -1
	404	#endif
4a312769 AV	405	#ifndef __compiletime_warning
	406	# define __compiletime_warning(message)
	407	#endif
63312b6a AV	408	#ifndef __compiletime_error
63312b6a AV	409	# define __compiletime_error(message)
2c0d259e JH	410	/*
	411	* Sparse complains of variable sized arrays due to the temporary variable in
	412	* __compiletime_assert. Unfortunately we can't just expand it out to make
	413	* sparse see a constant array size without breaking compiletime_assert on old
	414	* versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
	415	*/
	416	# ifndef __CHECKER__
	417	# define __compiletime_error_fallback(condition) \
9a8ab1c3	418	do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
2c0d259e JH	419	# endif
	420	#endif
	421	#ifndef __compiletime_error_fallback
c361d3e5	422	# define __compiletime_error_fallback(condition) do { } while (0)
63312b6a	423	#endif
c361d3e5	424
9a8ab1c3 DS	425	#define __compiletime_assert(condition, msg, prefix, suffix) \
	426	do { \
	427	bool __cond = !(condition); \
	428	extern void prefix ## suffix(void) __compiletime_error(msg); \
	429	if (__cond) \
	430	prefix ## suffix(); \
	431	__compiletime_error_fallback(__cond); \
	432	} while (0)
	433
	434	#define _compiletime_assert(condition, msg, prefix, suffix) \
	435	__compiletime_assert(condition, msg, prefix, suffix)
	436
	437	/**
	438	* compiletime_assert - break build and emit msg if condition is false
	439	* @condition: a compile-time constant condition to check
	440	* @msg: a message to emit if condition is false
	441	*
	442	* In tradition of POSIX assert, this macro will break the build if the
	443	* supplied condition is false, emitting the supplied error message if the
	444	* compiler has support to do so.
	445	*/
	446	#define compiletime_assert(condition, msg) \
	447	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
	448
47933ad4 PZ	449	#define compiletime_assert_atomic_type(t) \
	450	compiletime_assert(__native_word(t), \
	451	"Need native word sized stores/loads for atomicity.")
	452
9c3cdc1f LT	453	/*
	454	* Prevent the compiler from merging or refetching accesses. The compiler
	455	* is also forbidden from reordering successive instances of ACCESS_ONCE(),
	456	* but only when the compiler is aware of some particular ordering. One way
	457	* to make the compiler aware of ordering is to put the two invocations of
	458	* ACCESS_ONCE() in different C statements.
	459	*
927609d6 CB	460	* ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
	461	* on a union member will work as long as the size of the member matches the
	462	* size of the union and the size is smaller than word size.
	463	*
	464	* The major use cases of ACCESS_ONCE used to be (1) Mediating communication
	465	* between process-level code and irq/NMI handlers, all running on the same CPU,
	466	* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
	467	* mutilate accesses that either do not require ordering or that interact
	468	* with an explicit memory barrier or atomic instruction that provides the
	469	* required ordering.
	470	*
663fdcbe	471	* If possible use READ_ONCE()/WRITE_ONCE() instead.
9c3cdc1f	472	*/
927609d6	473	#define __ACCESS_ONCE(x) ({ \
c5b19946	474	__maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
927609d6 CB	475	(volatile typeof(x) *)&(x); })
927609d6 CB	476	#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
9c3cdc1f	477
0a04b016 PZ	478	/**
	479	* lockless_dereference() - safely load a pointer for later dereference
	480	* @p: The pointer to load
	481	*
	482	* Similar to rcu_dereference(), but for situations where the pointed-to
	483	* object's lifetime is managed by something other than RCU. That
	484	* "something other" might be reference counting or simple immortality.
	485	*/
	486	#define lockless_dereference(p) \
	487	({ \
38183b9c	488	typeof(p) _________p1 = READ_ONCE(p); \
0a04b016 PZ	489	smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
	490	(_________p1); \
	491	})
	492
324670b6 MH	493	/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
	494	#ifdef CONFIG_KPROBES
	495	# define __kprobes __attribute__((__section__(".kprobes.text")))
376e2424	496	# define nokprobe_inline __always_inline
324670b6 MH	497	#else
324670b6 MH	498	# define __kprobes
376e2424	499	# define nokprobe_inline inline
324670b6	500	#endif
1da177e4	501	#endif /* __LINUX_COMPILER_H */