[linux-2.6-block.git] / tools / include / linux / compiler.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _TOOLS_LINUX_COMPILER_H_
#define _TOOLS_LINUX_COMPILER_H_

#include <linux/compiler_types.h>

#ifndef __compiletime_error
# define __compiletime_error(message)
#endif

#ifdef __OPTIMIZE__
# define __compiletime_assert(condition, msg, prefix, suffix)		\
	do {								\
		extern void prefix ## suffix(void) __compiletime_error(msg); \
		if (!(condition))					\
			prefix ## suffix();				\
	} while (0)
#else
# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
#endif

#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_, __COUNTER__)

/* Optimization barrier */
/* The "volatile" is due to gcc bugs */
#define barrier() __asm__ __volatile__("": : :"memory")

#ifndef __always_inline
# define __always_inline	inline __attribute__((always_inline))
#endif

#ifndef __always_unused
#define __always_unused __attribute__((__unused__))
#endif

#ifndef __noreturn
#define __noreturn __attribute__((__noreturn__))
#endif

#ifndef unreachable
#define unreachable() __builtin_unreachable()
#endif

#ifndef noinline
#define noinline
#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

#ifdef __ANDROID__
/*
 * FIXME: Big hammer to get rid of tons of:
 *   "warning: always_inline function might not be inlinable"
 *
 * At least on android-ndk-r12/platforms/android-24/arch-arm
 */
#undef __always_inline
#define __always_inline	inline
#endif

#define __user
#define __rcu
#define __read_mostly

#ifndef __attribute_const__
# define __attribute_const__
#endif

#ifndef __maybe_unused
# define __maybe_unused		__attribute__((unused))
#endif

#ifndef __used
# define __used		__attribute__((__unused__))
#endif

#ifndef __packed
# define __packed		__attribute__((__packed__))
#endif

#ifndef __force
# define __force
#endif

#ifndef __weak
# define __weak			__attribute__((weak))
#endif

#ifndef likely
# define likely(x)		__builtin_expect(!!(x), 1)
#endif

#ifndef unlikely
# define unlikely(x)		__builtin_expect(!!(x), 0)
#endif

#ifndef __init
# define __init
#endif

#include <linux/types.h>

/*
 * Following functions are taken from kernel sources and
 * break aliasing rules in their original form.
 *
 * While kernel is compiled with -fno-strict-aliasing,
 * perf uses -Wstrict-aliasing=3 which makes build fail
 * under gcc 4.4.
 *
 * Using extra __may_alias__ type to allow aliasing
 * in this case.
 */
typedef __u8  __attribute__((__may_alias__))  __u8_alias_t;
typedef __u16 __attribute__((__may_alias__)) __u16_alias_t;
typedef __u32 __attribute__((__may_alias__)) __u32_alias_t;
typedef __u64 __attribute__((__may_alias__)) __u64_alias_t;

static __always_inline void __read_once_size(const volatile void *p, void *res, int size)
{
	switch (size) {
	case 1: *(__u8_alias_t  *) res = *(volatile __u8_alias_t  *) p; break;
	case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break;
	case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break;
	case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) 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_alias_t *) p = *(__u8_alias_t  *) res; break;
	case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break;
	case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break;
	case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) 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 and WRITE_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 READ_ONCE or WRITE_ONCE in different C
 * statements.
 *
 * 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 =	\
		{ .__c = { 0 } };			\
	__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;					\
})


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

#ifndef OPTIMIZER_HIDE_VAR
/* Make the optimizer believe the variable can be manipulated arbitrarily. */
#define OPTIMIZER_HIDE_VAR(var)						\
	__asm__ ("" : "=r" (var) : "0" (var))
#endif

#endif /* _TOOLS_LINUX_COMPILER_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
8a625c1f NK	2	#ifndef _TOOLS_LINUX_COMPILER_H_
8a625c1f NK	3	#define _TOOLS_LINUX_COMPILER_H_
5a116dd2	4
4bba4c4b	5	#include <linux/compiler_types.h>
19261401	6
49006538 ACM	7	#ifndef __compiletime_error
	8	# define __compiletime_error(message)
	9	#endif
	10
5b992add ACM	11	#ifdef __OPTIMIZE__
	12	# define __compiletime_assert(condition, msg, prefix, suffix) \
	13	do { \
	14	extern void prefix ## suffix(void) __compiletime_error(msg); \
	15	if (!(condition)) \
	16	prefix ## suffix(); \
	17	} while (0)
	18	#else
	19	# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
	20	#endif
	21
	22	#define _compiletime_assert(condition, msg, prefix, suffix) \
	23	__compiletime_assert(condition, msg, prefix, suffix)
	24
	25	/**
	26	* compiletime_assert - break build and emit msg if condition is false
	27	* @condition: a compile-time constant condition to check
	28	* @msg: a message to emit if condition is false
	29	*
	30	* In tradition of POSIX assert, this macro will break the build if the
	31	* supplied condition is false, emitting the supplied error message if the
	32	* compiler has support to do so.
	33	*/
	34	#define compiletime_assert(condition, msg) \
	35	_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
	36
5ac69737 ACM	37	/* Optimization barrier */
	38	/* The "volatile" is due to gcc bugs */
	39	#define barrier() __asm__ __volatile__("": : :"memory")
	40
5a116dd2	41	#ifndef __always_inline
7a10822a	42	# define __always_inline inline __attribute__((always_inline))
5a116dd2	43	#endif
7a10822a	44
51e6ac1f MB	45	#ifndef __always_unused
	46	#define __always_unused __attribute__((__unused__))
	47	#endif
	48
	49	#ifndef __noreturn
	50	#define __noreturn __attribute__((__noreturn__))
	51	#endif
	52
	53	#ifndef unreachable
	54	#define unreachable() __builtin_unreachable()
	55	#endif
	56
9dd4ca47 ACM	57	#ifndef noinline
	58	#define noinline
	59	#endif
	60
f6441aff ACM	61	/* Are two types/vars the same type (ignoring qualifiers)? */
	62	#ifndef __same_type
	63	# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
	64	#endif
	65
8c98abff ACM	66	#ifdef __ANDROID__
	67	/*
	68	* FIXME: Big hammer to get rid of tons of:
	69	* "warning: always_inline function might not be inlinable"
	70	*
	71	* At least on android-ndk-r12/platforms/android-24/arch-arm
	72	*/
	73	#undef __always_inline
	74	#define __always_inline inline
	75	#endif
	76
5a116dd2	77	#define __user
12ea6539 MW	78	#define __rcu
12ea6539 MW	79	#define __read_mostly
7a10822a	80
195bcbf5	81	#ifndef __attribute_const__
7a10822a	82	# define __attribute_const__
195bcbf5	83	#endif
5a116dd2	84
1d037ca1	85	#ifndef __maybe_unused
7a10822a IM	86	# define __maybe_unused __attribute__((unused))
	87	#endif
	88
e58e871b LASL	89	#ifndef __used
	90	# define __used __attribute__((__unused__))
	91	#endif
	92
7a10822a IM	93	#ifndef __packed
7a10822a IM	94	# define __packed __attribute__((__packed__))
1d037ca1	95	#endif
618038df	96
86d5a70c	97	#ifndef __force
7a10822a	98	# define __force
86d5a70c IT	99	#endif
86d5a70c IT	100
fb1c9185 IM	101	#ifndef __weak
	102	# define __weak __attribute__((weak))
	103	#endif
	104
835d44b9 NK	105	#ifndef likely
	106	# define likely(x) __builtin_expect(!!(x), 1)
	107	#endif
	108
	109	#ifndef unlikely
	110	# define unlikely(x) __builtin_expect(!!(x), 0)
	111	#endif
	112
e58e871b LASL	113	#ifndef __init
	114	# define __init
	115	#endif
	116
728abda6 ACM	117	#include <linux/types.h>
728abda6 ACM	118
c95f3432 JO	119	/*
	120	* Following functions are taken from kernel sources and
	121	* break aliasing rules in their original form.
	122	*
	123	* While kernel is compiled with -fno-strict-aliasing,
	124	* perf uses -Wstrict-aliasing=3 which makes build fail
	125	* under gcc 4.4.
	126	*
	127	* Using extra __may_alias__ type to allow aliasing
	128	* in this case.
	129	*/
	130	typedef __u8 __attribute__((__may_alias__)) __u8_alias_t;
	131	typedef __u16 __attribute__((__may_alias__)) __u16_alias_t;
	132	typedef __u32 __attribute__((__may_alias__)) __u32_alias_t;
	133	typedef __u64 __attribute__((__may_alias__)) __u64_alias_t;
	134
728abda6 ACM	135	static __always_inline void __read_once_size(const volatile void p, void res, int size)
	136	{
	137	switch (size) {
c95f3432 JO	138	case 1: (__u8_alias_t ) res = (volatile __u8_alias_t ) p; break;
	139	case 2: (__u16_alias_t ) res = (volatile __u16_alias_t ) p; break;
	140	case 4: (__u32_alias_t ) res = (volatile __u32_alias_t ) p; break;
	141	case 8: (__u64_alias_t ) res = (volatile __u64_alias_t ) p; break;
728abda6 ACM	142	default:
	143	barrier();
	144	__builtin_memcpy((void )res, (const void )p, size);
	145	barrier();
	146	}
	147	}
	148
	149	static __always_inline void __write_once_size(volatile void p, void res, int size)
	150	{
	151	switch (size) {
c95f3432 JO	152	case 1: (volatile __u8_alias_t ) p = (__u8_alias_t ) res; break;
	153	case 2: (volatile __u16_alias_t ) p = (__u16_alias_t ) res; break;
	154	case 4: (volatile __u32_alias_t ) p = (__u32_alias_t ) res; break;
	155	case 8: (volatile __u64_alias_t ) p = (__u64_alias_t ) res; break;
728abda6 ACM	156	default:
	157	barrier();
	158	__builtin_memcpy((void )p, (const void )res, size);
	159	barrier();
	160	}
	161	}
	162
	163	/*
	164	* Prevent the compiler from merging or refetching reads or writes. The
	165	* compiler is also forbidden from reordering successive instances of
2a22f692 MR	166	* READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
	167	* particular ordering. One way to make the compiler aware of ordering is to
	168	* put the two invocations of READ_ONCE or WRITE_ONCE in different C
	169	* statements.
728abda6	170	*
2a22f692 MR	171	* These two macros will also work on aggregate data types like structs or
	172	* unions. If the size of the accessed data type exceeds the word size of
	173	* the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will
	174	* fall back to memcpy and print a compile-time warning.
728abda6 ACM	175	*
	176	* Their two major use cases are: (1) Mediating communication between
	177	* process-level code and irq/NMI handlers, all running on the same CPU,
2a22f692	178	* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
728abda6 ACM	179	* mutilate accesses that either do not require ordering or that interact
	180	* with an explicit memory barrier or atomic instruction that provides the
	181	* required ordering.
	182	*/
	183
4d3b57da MR	184	#define READ_ONCE(x) \
	185	({ \
	186	union { typeof(x) __val; char __c[1]; } __u = \
	187	{ .__c = { 0 } }; \
	188	__read_once_size(&(x), __u.__c, sizeof(x)); \
	189	__u.__val; \
	190	})
	191
	192	#define WRITE_ONCE(x, val) \
	193	({ \
	194	union { typeof(x) __val; char __c[1]; } __u = \
	195	{ .__val = (val) }; \
	196	__write_once_size(&(x), __u.__c, sizeof(x)); \
	197	__u.__val; \
	198	})
728abda6	199
b5bf1733	200
e5a0516e JO	201	/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
	202	#define ___PASTE(a, b) a##b
	203	#define __PASTE(a, b) ___PASTE(a, b)
	204
e5d51a66 MB	205	#ifndef OPTIMIZER_HIDE_VAR
	206	/* Make the optimizer believe the variable can be manipulated arbitrarily. */
	207	#define OPTIMIZER_HIDE_VAR(var) \
	208	__asm__ ("" : "=r" (var) : "0" (var))
	209	#endif
	210
8a625c1f	211	#endif /* _TOOLS_LINUX_COMPILER_H */