[mirror_ubuntu-artful-kernel.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
#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
#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

/* 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 data_access_exceeds_word_size(void)
#ifdef __compiletime_warning
__compiletime_warning("data access exceeds word size and won't be atomic")
#endif
;

static __always_inline void data_access_exceeds_word_size(void)
{
}

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;
#ifdef CONFIG_64BIT
	case 8: *(__u64 *)res = *(volatile __u64 *)p; break;
#endif
	default:
		barrier();
		__builtin_memcpy((void *)res, (const void *)p, size);
		data_access_exceeds_word_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;
#ifdef CONFIG_64BIT
	case 8: *(volatile __u64 *)p = *(__u64 *)res; break;
#endif
	default:
		barrier();
		__builtin_memcpy((void *)p, (const void *)res, size);
		data_access_exceeds_word_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) \
	({ typeof(x) __val = (val); __write_once_size(&(x), &__val, sizeof(__val)); __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/ASSIGN_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))

/* 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
ca5ecddf	24	#endif
c47ffe3d AV	25	extern void __chk_user_ptr(const volatile void __user *);
c47ffe3d AV	26	extern void __chk_io_ptr(const volatile void __iomem *);
1da177e4 LT	27	#else
	28	# define __user
	29	# define __kernel
	30	# define __safe
	31	# define __force
	32	# define __nocast
	33	# define __iomem
	34	# define __chk_user_ptr(x) (void)0
	35	# define __chk_io_ptr(x) (void)0
	36	# define __builtin_warning(x, y...) (1)
8529091e	37	# define __must_hold(x)
1da177e4 LT	38	# define __acquires(x)
	39	# define __releases(x)
	40	# define __acquire(x) (void)0
	41	# define __release(x) (void)0
dcc8e559	42	# define __cond_lock(x,c) (c)
e0fdb0e0	43	# define __percpu
71d1d5c7	44	# define __rcu
1da177e4 LT	45	#endif
1da177e4 LT	46
6f33d587 RR	47	/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
	48	#define ___PASTE(a,b) a##b
	49	#define __PASTE(a,b) ___PASTE(a,b)
	50
1da177e4 LT	51	#ifdef __KERNEL__
1da177e4 LT	52
f153b821 LT	53	#ifdef __GNUC__
f153b821 LT	54	#include <linux/compiler-gcc.h>
1da177e4 LT	55	#endif
1da177e4 LT	56
61f55214 HC	57	#ifdef CC_USING_HOTPATCH
	58	#define notrace __attribute__((hotpatch(0,0)))
	59	#else
28614889	60	#define notrace __attribute__((no_instrument_function))
61f55214	61	#endif
28614889	62
1da177e4 LT	63	/* Intel compiler defines __GNUC__. So we will overwrite implementations
	64	* coming from above header files here
	65	*/
	66	#ifdef __INTEL_COMPILER
	67	# include <linux/compiler-intel.h>
	68	#endif
	69
565cbdc2 MC	70	/* Clang compiler defines __GNUC__. So we will overwrite implementations
	71	* coming from above header files here
	72	*/
	73	#ifdef __clang__
	74	#include <linux/compiler-clang.h>
	75	#endif
	76
1da177e4 LT	77	/*
	78	* Generic compiler-dependent macros required for kernel
	79	* build go below this comment. Actual compiler/compiler version
	80	* specific implementations come from the above header files
	81	*/
	82
2ed84eeb	83	struct ftrace_branch_data {
1f0d69a9 SR	84	const char *func;
	85	const char *file;
	86	unsigned line;
2bcd521a SR	87	union {
	88	struct {
	89	unsigned long correct;
	90	unsigned long incorrect;
	91	};
	92	struct {
	93	unsigned long miss;
	94	unsigned long hit;
	95	};
97e7e4f3	96	unsigned long miss_hit[2];
2bcd521a	97	};
1f0d69a9	98	};
2ed84eeb SR	99
	100	/*
	101	* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
	102	* to disable branch tracing on a per file basis.
	103	*/
d9ad8bc0 BVA	104	#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
d9ad8bc0 BVA	105	&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
2ed84eeb	106	void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
1f0d69a9 SR	107
	108	#define likely_notrace(x) __builtin_expect(!!(x), 1)
	109	#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
	110
45b79749	111	#define __branch_check__(x, expect) ({ \
1f0d69a9	112	int ______r; \
2ed84eeb	113	static struct ftrace_branch_data \
1f0d69a9	114	__attribute__((__aligned__(4))) \
45b79749	115	__attribute__((section("_ftrace_annotated_branch"))) \
1f0d69a9 SR	116	______f = { \
	117	.func = __func__, \
	118	.file = __FILE__, \
	119	.line = __LINE__, \
	120	}; \
1f0d69a9	121	______r = likely_notrace(x); \
45b79749	122	ftrace_likely_update(&______f, ______r, expect); \
1f0d69a9 SR	123	______r; \
	124	})
	125
	126	/*
	127	* Using __builtin_constant_p(x) to ignore cases where the return
	128	* value is always the same. This idea is taken from a similar patch
	129	* written by Daniel Walker.
	130	*/
	131	# ifndef likely
45b79749	132	# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
1f0d69a9 SR	133	# endif
1f0d69a9 SR	134	# ifndef unlikely
45b79749	135	# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
1f0d69a9	136	# endif
2bcd521a SR	137
	138	#ifdef CONFIG_PROFILE_ALL_BRANCHES
	139	/*
	140	* "Define 'is'", Bill Clinton
	141	* "Define 'if'", Steven Rostedt
	142	*/
ab3c9c68 LT	143	#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
	144	#define __trace_if(cond) \
	145	if (__builtin_constant_p((cond)) ? !!(cond) : \
2bcd521a SR	146	({ \
	147	int ______r; \
	148	static struct ftrace_branch_data \
	149	__attribute__((__aligned__(4))) \
	150	__attribute__((section("_ftrace_branch"))) \
	151	______f = { \
	152	.func = __func__, \
	153	.file = __FILE__, \
	154	.line = __LINE__, \
	155	}; \
	156	______r = !!(cond); \
97e7e4f3	157	______f.miss_hit[______r]++; \
2bcd521a SR	158	______r; \
	159	}))
	160	#endif /* CONFIG_PROFILE_ALL_BRANCHES */
	161
1f0d69a9 SR	162	#else
	163	# define likely(x) __builtin_expect(!!(x), 1)
	164	# define unlikely(x) __builtin_expect(!!(x), 0)
	165	#endif
1da177e4 LT	166
	167	/* Optimization barrier */
	168	#ifndef barrier
	169	# define barrier() __memory_barrier()
	170	#endif
	171
38938c87 DD	172	/* Unreachable code */
	173	#ifndef unreachable
	174	# define unreachable() do { } while (1)
	175	#endif
	176
1da177e4 LT	177	#ifndef RELOC_HIDE
	178	# define RELOC_HIDE(ptr, off) \
	179	({ unsigned long __ptr; \
	180	__ptr = (unsigned long) (ptr); \
	181	(typeof(ptr)) (__ptr + (off)); })
	182	#endif
	183
fe8c8a12 CEB	184	#ifndef OPTIMIZER_HIDE_VAR
	185	#define OPTIMIZER_HIDE_VAR(var) barrier()
	186	#endif
	187
6f33d587 RR	188	/* Not-quite-unique ID. */
	189	#ifndef __UNIQUE_ID
	190	# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
	191	#endif
	192
230fa253 CB	193	#include <uapi/linux/types.h>
	194
	195	static __always_inline void data_access_exceeds_word_size(void)
	196	#ifdef __compiletime_warning
	197	__compiletime_warning("data access exceeds word size and won't be atomic")
	198	#endif
	199	;
	200
	201	static __always_inline void data_access_exceeds_word_size(void)
	202	{
	203	}
	204
dd369297	205	static __always_inline void __read_once_size(const volatile void p, void res, int size)
230fa253 CB	206	{
	207	switch (size) {
	208	case 1: (__u8 )res = (volatile __u8 )p; break;
	209	case 2: (__u16 )res = (volatile __u16 )p; break;
	210	case 4: (__u32 )res = (volatile __u32 )p; break;
	211	#ifdef CONFIG_64BIT
	212	case 8: (__u64 )res = (volatile __u64 )p; break;
	213	#endif
	214	default:
	215	barrier();
	216	__builtin_memcpy((void )res, (const void )p, size);
	217	data_access_exceeds_word_size();
	218	barrier();
	219	}
	220	}
	221
43239cbe	222	static __always_inline void __write_once_size(volatile void p, void res, int size)
230fa253 CB	223	{
	224	switch (size) {
	225	case 1: (volatile __u8 )p = (__u8 )res; break;
	226	case 2: (volatile __u16 )p = (__u16 )res; break;
	227	case 4: (volatile __u32 )p = (__u32 )res; break;
	228	#ifdef CONFIG_64BIT
	229	case 8: (volatile __u64 )p = (__u64 )res; break;
	230	#endif
	231	default:
	232	barrier();
	233	__builtin_memcpy((void )p, (const void )res, size);
	234	data_access_exceeds_word_size();
	235	barrier();
	236	}
	237	}
	238
	239	/*
	240	* Prevent the compiler from merging or refetching reads or writes. The
	241	* compiler is also forbidden from reordering successive instances of
43239cbe	242	* READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the
230fa253 CB	243	* compiler is aware of some particular ordering. One way to make the
230fa253 CB	244	* compiler aware of ordering is to put the two invocations of READ_ONCE,
43239cbe	245	* WRITE_ONCE or ACCESS_ONCE() in different C statements.
230fa253 CB	246	*
	247	* In contrast to ACCESS_ONCE these two macros will also work on aggregate
	248	* data types like structs or unions. If the size of the accessed data
	249	* type exceeds the word size of the machine (e.g., 32 bits or 64 bits)
43239cbe	250	* READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a
230fa253 CB	251	* compile-time warning.
	252	*
	253	* Their two major use cases are: (1) Mediating communication between
	254	* process-level code and irq/NMI handlers, all running on the same CPU,
	255	* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
	256	* mutilate accesses that either do not require ordering or that interact
	257	* with an explicit memory barrier or atomic instruction that provides the
	258	* required ordering.
	259	*/
	260
	261	#define READ_ONCE(x) \
dd369297	262	({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
230fa253	263
43239cbe	264	#define WRITE_ONCE(x, val) \
dd369297	265	({ typeof(x) __val = (val); __write_once_size(&(x), &__val, sizeof(__val)); __val; })
230fa253	266
1da177e4 LT	267	#endif /* __KERNEL__ */
	268
	269	#endif /* __ASSEMBLY__ */
	270
4f79c3ff	271	#ifdef __KERNEL__
1da177e4 LT	272	/*
	273	* Allow us to mark functions as 'deprecated' and have gcc emit a nice
	274	* warning for each use, in hopes of speeding the functions removal.
	275	* Usage is:
	276	* int __deprecated foo(void)
	277	*/
	278	#ifndef __deprecated
	279	# define __deprecated /* unimplemented */
	280	#endif
	281
512345be PM	282	#ifdef MODULE
	283	#define __deprecated_for_modules __deprecated
	284	#else
	285	#define __deprecated_for_modules
	286	#endif
	287
1da177e4 LT	288	#ifndef __must_check
	289	#define __must_check
	290	#endif
	291
cebc04ba AM	292	#ifndef CONFIG_ENABLE_MUST_CHECK
	293	#undef __must_check
	294	#define __must_check
	295	#endif
de488443 JG	296	#ifndef CONFIG_ENABLE_WARN_DEPRECATED
	297	#undef __deprecated
	298	#undef __deprecated_for_modules
	299	#define __deprecated
	300	#define __deprecated_for_modules
	301	#endif
cebc04ba	302
1da177e4 LT	303	/*
	304	* Allow us to avoid 'defined but not used' warnings on functions and data,
	305	* as well as force them to be emitted to the assembly file.
	306	*
0d7ebbbc DR	307	* As of gcc 3.4, static functions that are not marked with attribute((used))
0d7ebbbc DR	308	* may be elided from the assembly file. As of gcc 3.4, static data not so
1da177e4 LT	309	* marked will not be elided, but this may change in a future gcc version.
1da177e4 LT	310	*
0d7ebbbc DR	311	* NOTE: Because distributions shipped with a backported unit-at-a-time
	312	* compiler in gcc 3.3, we must define __used to be __attribute__((used))
	313	* for gcc >=3.3 instead of 3.4.
	314	*
1da177e4 LT	315	* In prior versions of gcc, such functions and data would be emitted, but
1da177e4 LT	316	* would be warned about except with attribute((unused)).
0d7ebbbc DR	317	*
	318	* Mark functions that are referenced only in inline assembly as __used so
	319	* the code is emitted even though it appears to be unreferenced.
1da177e4	320	*/
0d7ebbbc DR	321	#ifndef __used
	322	# define __used /* unimplemented */
	323	#endif
	324
	325	#ifndef __maybe_unused
	326	# define __maybe_unused /* unimplemented */
1da177e4 LT	327	#endif
1da177e4 LT	328
7b2a3513 LZ	329	#ifndef __always_unused
	330	# define __always_unused /* unimplemented */
	331	#endif
	332
423bc7b2 DW	333	#ifndef noinline
	334	#define noinline
	335	#endif
	336
735c4fb9 AM	337	/*
735c4fb9 AM	338	* Rather then using noinline to prevent stack consumption, use
e6be0c9e	339	* noinline_for_stack instead. For documentation reasons.
735c4fb9 AM	340	*/
	341	#define noinline_for_stack noinline
	342
423bc7b2 DW	343	#ifndef __always_inline
	344	#define __always_inline inline
	345	#endif
	346
	347	#endif /* __KERNEL__ */
	348
1da177e4 LT	349	/*
	350	* From the GCC manual:
	351	*
	352	* Many functions do not examine any values except their arguments,
	353	* and have no effects except the return value. Basically this is
	354	* just slightly more strict class than the `pure' attribute above,
	355	* since function is not allowed to read global memory.
	356	*
	357	* Note that a function that has pointer arguments and examines the
	358	* data pointed to must _not_ be declared `const'. Likewise, a
	359	* function that calls a non-`const' function usually must not be
	360	* `const'. It does not make sense for a `const' function to return
	361	* `void'.
	362	*/
	363	#ifndef __attribute_const__
	364	# define __attribute_const__ /* unimplemented */
	365	#endif
	366
a586df06 AK	367	/*
	368	* Tell gcc if a function is cold. The compiler will assume any path
	369	* directly leading to the call is unlikely.
	370	*/
	371
	372	#ifndef __cold
	373	#define __cold
	374	#endif
	375
f3fe866d SR	376	/* Simple shorthand for a section definition */
	377	#ifndef __section
	378	# define __section(S) __attribute__ ((__section__(#S)))
	379	#endif
	380
9a858dc7 AK	381	#ifndef __visible
	382	#define __visible
	383	#endif
	384
d2c123c2 RR	385	/* Are two types/vars the same type (ignoring qualifiers)? */
	386	#ifndef __same_type
	387	# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
	388	#endif
	389
47933ad4 PZ	390	/* Is this type a native word size -- useful for atomic operations */
47933ad4 PZ	391	#ifndef __native_word
536fa402	392	# define __native_word(t) (sizeof(t) == sizeof(char) \|\| sizeof(t) == sizeof(short) \|\| sizeof(t) == sizeof(int) \|\| sizeof(t) == sizeof(long))
47933ad4 PZ	393	#endif
47933ad4 PZ	394
9f0cf4ad AV	395	/* Compile time object size, -1 for unknown */
	396	#ifndef __compiletime_object_size
	397	# define __compiletime_object_size(obj) -1
	398	#endif
4a312769 AV	399	#ifndef __compiletime_warning
	400	# define __compiletime_warning(message)
	401	#endif
63312b6a AV	402	#ifndef __compiletime_error
63312b6a AV	403	# define __compiletime_error(message)
2c0d259e JH	404	/*
	405	* Sparse complains of variable sized arrays due to the temporary variable in
	406	* __compiletime_assert. Unfortunately we can't just expand it out to make
	407	* sparse see a constant array size without breaking compiletime_assert on old
	408	* versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether.
	409	*/
	410	# ifndef __CHECKER__
	411	# define __compiletime_error_fallback(condition) \
9a8ab1c3	412	do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
2c0d259e JH	413	# endif
	414	#endif
	415	#ifndef __compiletime_error_fallback
c361d3e5	416	# define __compiletime_error_fallback(condition) do { } while (0)
63312b6a	417	#endif
c361d3e5	418
9a8ab1c3 DS	419	#define __compiletime_assert(condition, msg, prefix, suffix) \
	420	do { \
	421	bool __cond = !(condition); \
	422	extern void prefix ## suffix(void) __compiletime_error(msg); \
	423	if (__cond) \
	424	prefix ## suffix(); \
	425	__compiletime_error_fallback(__cond); \
	426	} while (0)
	427
	428	#define _compiletime_assert(condition, msg, prefix, suffix) \
	429	__compiletime_assert(condition, msg, prefix, suffix)
	430
	431	/**
	432	* compiletime_assert - break build and emit msg if condition is false
	433	* @condition: a compile-time constant condition to check
	434	* @msg: a message to emit if condition is false
	435	*
	436	* In tradition of POSIX assert, this macro will break the build if the
	437	* supplied condition is false, emitting the supplied error message if the
	438	* compiler has support to do so.
	439	*/
	440	#define compiletime_assert(condition, msg) \
	441	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
	442
47933ad4 PZ	443	#define compiletime_assert_atomic_type(t) \
	444	compiletime_assert(__native_word(t), \
	445	"Need native word sized stores/loads for atomicity.")
	446
9c3cdc1f LT	447	/*
	448	* Prevent the compiler from merging or refetching accesses. The compiler
	449	* is also forbidden from reordering successive instances of ACCESS_ONCE(),
	450	* but only when the compiler is aware of some particular ordering. One way
	451	* to make the compiler aware of ordering is to put the two invocations of
	452	* ACCESS_ONCE() in different C statements.
	453	*
927609d6 CB	454	* ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE
	455	* on a union member will work as long as the size of the member matches the
	456	* size of the union and the size is smaller than word size.
	457	*
	458	* The major use cases of ACCESS_ONCE used to be (1) Mediating communication
	459	* between process-level code and irq/NMI handlers, all running on the same CPU,
	460	* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
	461	* mutilate accesses that either do not require ordering or that interact
	462	* with an explicit memory barrier or atomic instruction that provides the
	463	* required ordering.
	464	*
	465	* If possible use READ_ONCE/ASSIGN_ONCE instead.
9c3cdc1f	466	*/
927609d6	467	#define __ACCESS_ONCE(x) ({ \
c5b19946	468	__maybe_unused typeof(x) __var = (__force typeof(x)) 0; \
927609d6 CB	469	(volatile typeof(x) *)&(x); })
927609d6 CB	470	#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
9c3cdc1f	471
324670b6 MH	472	/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
	473	#ifdef CONFIG_KPROBES
	474	# define __kprobes __attribute__((__section__(".kprobes.text")))
376e2424	475	# define nokprobe_inline __always_inline
324670b6 MH	476	#else
324670b6 MH	477	# define __kprobes
376e2424	478	# define nokprobe_inline inline
324670b6	479	#endif
1da177e4	480	#endif /* __LINUX_COMPILER_H */