[mirror_ubuntu-bionic-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

#define notrace __attribute__((no_instrument_function))

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

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

#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

/* 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)
# define __compiletime_error_fallback(condition) \
	do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
#else
# 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__)

/*
 * 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.
 *
 * This macro does absolutely -nothing- to prevent the CPU from reordering,
 * merging, or refetching absolutely anything at any time.  Its main intended
 * use is to mediate communication between process-level code and irq/NMI
 * handlers, all running on the same CPU.
 */
#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))

/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
#ifdef CONFIG_KPROBES
# define __kprobes	__attribute__((__section__(".kprobes.text")))
#else
# define __kprobes
#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
28614889 SR	57	#define notrace __attribute__((no_instrument_function))
28614889 SR	58
1da177e4 LT	59	/* Intel compiler defines __GNUC__. So we will overwrite implementations
	60	* coming from above header files here
	61	*/
	62	#ifdef __INTEL_COMPILER
	63	# include <linux/compiler-intel.h>
	64	#endif
	65
	66	/*
	67	* Generic compiler-dependent macros required for kernel
	68	* build go below this comment. Actual compiler/compiler version
	69	* specific implementations come from the above header files
	70	*/
	71
2ed84eeb	72	struct ftrace_branch_data {
1f0d69a9 SR	73	const char *func;
	74	const char *file;
	75	unsigned line;
2bcd521a SR	76	union {
	77	struct {
	78	unsigned long correct;
	79	unsigned long incorrect;
	80	};
	81	struct {
	82	unsigned long miss;
	83	unsigned long hit;
	84	};
97e7e4f3	85	unsigned long miss_hit[2];
2bcd521a	86	};
1f0d69a9	87	};
2ed84eeb SR	88
	89	/*
	90	* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
	91	* to disable branch tracing on a per file basis.
	92	*/
d9ad8bc0 BVA	93	#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
d9ad8bc0 BVA	94	&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
2ed84eeb	95	void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
1f0d69a9 SR	96
	97	#define likely_notrace(x) __builtin_expect(!!(x), 1)
	98	#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
	99
45b79749	100	#define __branch_check__(x, expect) ({ \
1f0d69a9	101	int ______r; \
2ed84eeb	102	static struct ftrace_branch_data \
1f0d69a9	103	__attribute__((__aligned__(4))) \
45b79749	104	__attribute__((section("_ftrace_annotated_branch"))) \
1f0d69a9 SR	105	______f = { \
	106	.func = __func__, \
	107	.file = __FILE__, \
	108	.line = __LINE__, \
	109	}; \
1f0d69a9	110	______r = likely_notrace(x); \
45b79749	111	ftrace_likely_update(&______f, ______r, expect); \
1f0d69a9 SR	112	______r; \
	113	})
	114
	115	/*
	116	* Using __builtin_constant_p(x) to ignore cases where the return
	117	* value is always the same. This idea is taken from a similar patch
	118	* written by Daniel Walker.
	119	*/
	120	# ifndef likely
45b79749	121	# define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
1f0d69a9 SR	122	# endif
1f0d69a9 SR	123	# ifndef unlikely
45b79749	124	# define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
1f0d69a9	125	# endif
2bcd521a SR	126
	127	#ifdef CONFIG_PROFILE_ALL_BRANCHES
	128	/*
	129	* "Define 'is'", Bill Clinton
	130	* "Define 'if'", Steven Rostedt
	131	*/
ab3c9c68 LT	132	#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
	133	#define __trace_if(cond) \
	134	if (__builtin_constant_p((cond)) ? !!(cond) : \
2bcd521a SR	135	({ \
	136	int ______r; \
	137	static struct ftrace_branch_data \
	138	__attribute__((__aligned__(4))) \
	139	__attribute__((section("_ftrace_branch"))) \
	140	______f = { \
	141	.func = __func__, \
	142	.file = __FILE__, \
	143	.line = __LINE__, \
	144	}; \
	145	______r = !!(cond); \
97e7e4f3	146	______f.miss_hit[______r]++; \
2bcd521a SR	147	______r; \
	148	}))
	149	#endif /* CONFIG_PROFILE_ALL_BRANCHES */
	150
1f0d69a9 SR	151	#else
	152	# define likely(x) __builtin_expect(!!(x), 1)
	153	# define unlikely(x) __builtin_expect(!!(x), 0)
	154	#endif
1da177e4 LT	155
	156	/* Optimization barrier */
	157	#ifndef barrier
	158	# define barrier() __memory_barrier()
	159	#endif
	160
38938c87 DD	161	/* Unreachable code */
	162	#ifndef unreachable
	163	# define unreachable() do { } while (1)
	164	#endif
	165
1da177e4 LT	166	#ifndef RELOC_HIDE
	167	# define RELOC_HIDE(ptr, off) \
	168	({ unsigned long __ptr; \
	169	__ptr = (unsigned long) (ptr); \
	170	(typeof(ptr)) (__ptr + (off)); })
	171	#endif
	172
6f33d587 RR	173	/* Not-quite-unique ID. */
	174	#ifndef __UNIQUE_ID
	175	# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
	176	#endif
	177
1da177e4 LT	178	#endif /* __KERNEL__ */
	179
	180	#endif /* __ASSEMBLY__ */
	181
4f79c3ff	182	#ifdef __KERNEL__
1da177e4 LT	183	/*
	184	* Allow us to mark functions as 'deprecated' and have gcc emit a nice
	185	* warning for each use, in hopes of speeding the functions removal.
	186	* Usage is:
	187	* int __deprecated foo(void)
	188	*/
	189	#ifndef __deprecated
	190	# define __deprecated /* unimplemented */
	191	#endif
	192
512345be PM	193	#ifdef MODULE
	194	#define __deprecated_for_modules __deprecated
	195	#else
	196	#define __deprecated_for_modules
	197	#endif
	198
1da177e4 LT	199	#ifndef __must_check
	200	#define __must_check
	201	#endif
	202
cebc04ba AM	203	#ifndef CONFIG_ENABLE_MUST_CHECK
	204	#undef __must_check
	205	#define __must_check
	206	#endif
de488443 JG	207	#ifndef CONFIG_ENABLE_WARN_DEPRECATED
	208	#undef __deprecated
	209	#undef __deprecated_for_modules
	210	#define __deprecated
	211	#define __deprecated_for_modules
	212	#endif
cebc04ba	213
1da177e4 LT	214	/*
	215	* Allow us to avoid 'defined but not used' warnings on functions and data,
	216	* as well as force them to be emitted to the assembly file.
	217	*
0d7ebbbc DR	218	* As of gcc 3.4, static functions that are not marked with attribute((used))
0d7ebbbc DR	219	* may be elided from the assembly file. As of gcc 3.4, static data not so
1da177e4 LT	220	* marked will not be elided, but this may change in a future gcc version.
1da177e4 LT	221	*
0d7ebbbc DR	222	* NOTE: Because distributions shipped with a backported unit-at-a-time
	223	* compiler in gcc 3.3, we must define __used to be __attribute__((used))
	224	* for gcc >=3.3 instead of 3.4.
	225	*
1da177e4 LT	226	* In prior versions of gcc, such functions and data would be emitted, but
1da177e4 LT	227	* would be warned about except with attribute((unused)).
0d7ebbbc DR	228	*
	229	* Mark functions that are referenced only in inline assembly as __used so
	230	* the code is emitted even though it appears to be unreferenced.
1da177e4	231	*/
0d7ebbbc DR	232	#ifndef __used
	233	# define __used /* unimplemented */
	234	#endif
	235
	236	#ifndef __maybe_unused
	237	# define __maybe_unused /* unimplemented */
1da177e4 LT	238	#endif
1da177e4 LT	239
7b2a3513 LZ	240	#ifndef __always_unused
	241	# define __always_unused /* unimplemented */
	242	#endif
	243
423bc7b2 DW	244	#ifndef noinline
	245	#define noinline
	246	#endif
	247
735c4fb9 AM	248	/*
735c4fb9 AM	249	* Rather then using noinline to prevent stack consumption, use
e6be0c9e	250	* noinline_for_stack instead. For documentation reasons.
735c4fb9 AM	251	*/
	252	#define noinline_for_stack noinline
	253
423bc7b2 DW	254	#ifndef __always_inline
	255	#define __always_inline inline
	256	#endif
	257
	258	#endif /* __KERNEL__ */
	259
1da177e4 LT	260	/*
	261	* From the GCC manual:
	262	*
	263	* Many functions do not examine any values except their arguments,
	264	* and have no effects except the return value. Basically this is
	265	* just slightly more strict class than the `pure' attribute above,
	266	* since function is not allowed to read global memory.
	267	*
	268	* Note that a function that has pointer arguments and examines the
	269	* data pointed to must _not_ be declared `const'. Likewise, a
	270	* function that calls a non-`const' function usually must not be
	271	* `const'. It does not make sense for a `const' function to return
	272	* `void'.
	273	*/
	274	#ifndef __attribute_const__
	275	# define __attribute_const__ /* unimplemented */
	276	#endif
	277
a586df06 AK	278	/*
	279	* Tell gcc if a function is cold. The compiler will assume any path
	280	* directly leading to the call is unlikely.
	281	*/
	282
	283	#ifndef __cold
	284	#define __cold
	285	#endif
	286
f3fe866d SR	287	/* Simple shorthand for a section definition */
	288	#ifndef __section
	289	# define __section(S) __attribute__ ((__section__(#S)))
	290	#endif
	291
9a858dc7 AK	292	#ifndef __visible
	293	#define __visible
	294	#endif
	295
d2c123c2 RR	296	/* Are two types/vars the same type (ignoring qualifiers)? */
	297	#ifndef __same_type
	298	# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
	299	#endif
	300
9f0cf4ad AV	301	/* Compile time object size, -1 for unknown */
	302	#ifndef __compiletime_object_size
	303	# define __compiletime_object_size(obj) -1
	304	#endif
4a312769 AV	305	#ifndef __compiletime_warning
	306	# define __compiletime_warning(message)
	307	#endif
63312b6a AV	308	#ifndef __compiletime_error
63312b6a AV	309	# define __compiletime_error(message)
c361d3e5	310	# define __compiletime_error_fallback(condition) \
9a8ab1c3	311	do { ((void)sizeof(char[1 - 2 * condition])); } while (0)
c361d3e5 DS	312	#else
c361d3e5 DS	313	# define __compiletime_error_fallback(condition) do { } while (0)
63312b6a	314	#endif
c361d3e5	315
9a8ab1c3 DS	316	#define __compiletime_assert(condition, msg, prefix, suffix) \
	317	do { \
	318	bool __cond = !(condition); \
	319	extern void prefix ## suffix(void) __compiletime_error(msg); \
	320	if (__cond) \
	321	prefix ## suffix(); \
	322	__compiletime_error_fallback(__cond); \
	323	} while (0)
	324
	325	#define _compiletime_assert(condition, msg, prefix, suffix) \
	326	__compiletime_assert(condition, msg, prefix, suffix)
	327
	328	/**
	329	* compiletime_assert - break build and emit msg if condition is false
	330	* @condition: a compile-time constant condition to check
	331	* @msg: a message to emit if condition is false
	332	*
	333	* In tradition of POSIX assert, this macro will break the build if the
	334	* supplied condition is false, emitting the supplied error message if the
	335	* compiler has support to do so.
	336	*/
	337	#define compiletime_assert(condition, msg) \
	338	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
	339
9c3cdc1f LT	340	/*
	341	* Prevent the compiler from merging or refetching accesses. The compiler
	342	* is also forbidden from reordering successive instances of ACCESS_ONCE(),
	343	* but only when the compiler is aware of some particular ordering. One way
	344	* to make the compiler aware of ordering is to put the two invocations of
	345	* ACCESS_ONCE() in different C statements.
	346	*
	347	* This macro does absolutely -nothing- to prevent the CPU from reordering,
ded00a56 PM	348	* merging, or refetching absolutely anything at any time. Its main intended
	349	* use is to mediate communication between process-level code and irq/NMI
	350	* handlers, all running on the same CPU.
9c3cdc1f LT	351	*/
	352	#define ACCESS_ONCE(x) ((volatile typeof(x) )&(x))
	353
324670b6 MH	354	/* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
	355	#ifdef CONFIG_KPROBES
	356	# define __kprobes __attribute__((__section__(".kprobes.text")))
	357	#else
	358	# define __kprobes
	359	#endif
1da177e4	360	#endif /* __LINUX_COMPILER_H */