[mirror_ubuntu-eoan-kernel.git] / include / linux / compiler.h

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

#include <linux/compiler_types.h>

#ifndef __ASSEMBLY__

#ifdef __KERNEL__

/*
 * 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_likely_data *f, int val,
			  int expect, int is_constant);

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

#define __branch_check__(x, expect, is_constant) ({			\
			long ______r;					\
			static struct ftrace_likely_data		\
				__aligned(4)				\
				__section("_ftrace_annotated_branch")	\
				______f = {				\
				.data.func = __func__,			\
				.data.file = __FILE__,			\
				.data.line = __LINE__,			\
			};						\
			______r = __builtin_expect(!!(x), expect);	\
			ftrace_likely_update(&______f, ______r,		\
					     expect, is_constant);	\
			______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)	(__branch_check__(x, 1, __builtin_constant_p(x)))
# endif
# ifndef unlikely
#  define unlikely(x)	(__branch_check__(x, 0, __builtin_constant_p(x)))
# 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			\
			__aligned(4)					\
			__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

/* workaround for GCC PR82365 if needed */
#ifndef barrier_before_unreachable
# define barrier_before_unreachable() do { } while (0)
#endif

/* Unreachable code */
#ifdef CONFIG_STACK_VALIDATION
/*
 * These macros help objtool understand GCC code flow for unreachable code.
 * The __COUNTER__ based labels are a hack to make each instance of the macros
 * unique, to convince GCC not to merge duplicate inline asm statements.
 */
#define annotate_reachable() ({						\
	asm volatile("ANNOTATE_REACHABLE counter=%c0"			\
		     : : "i" (__COUNTER__));				\
})
#define annotate_unreachable() ({					\
	asm volatile("ANNOTATE_UNREACHABLE counter=%c0"			\
		     : : "i" (__COUNTER__));				\
})
#else
#define annotate_reachable()
#define annotate_unreachable()
#endif

#ifndef ASM_UNREACHABLE
# define ASM_UNREACHABLE
#endif
#ifndef unreachable
# define unreachable() do {		\
	annotate_unreachable();		\
	__builtin_unreachable();	\
} while (0)
#endif

/*
 * KENTRY - kernel entry point
 * This can be used to annotate symbols (functions or data) that are used
 * without their linker symbol being referenced explicitly. For example,
 * interrupt vector handlers, or functions in the kernel image that are found
 * programatically.
 *
 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
 * are handled in their own way (with KEEP() in linker scripts).
 *
 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
 * linker script. For example an architecture could KEEP() its entire
 * boot/exception vector code rather than annotate each function and data.
 */
#ifndef KENTRY
# define KENTRY(sym)						\
	extern typeof(sym) sym;					\
	static const unsigned long __kentry_##sym		\
	__used							\
	__section("___kentry" "+" #sym )			\
	= (unsigned long)&sym;
#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>

#define __READ_ONCE_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 __read_once_size(const volatile void *p, void *res, int size)
{
	__READ_ONCE_SIZE;
}

#ifdef CONFIG_KASAN
/*
 * We can't declare function 'inline' because __no_sanitize_address confilcts
 * with inlining. Attempt to inline it may cause a build failure.
 * 	https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
 * '__maybe_unused' allows us to avoid defined-but-not-used warnings.
 */
# define __no_kasan_or_inline __no_sanitize_address notrace __maybe_unused
#else
# define __no_kasan_or_inline __always_inline
#endif

static __no_kasan_or_inline
void __read_once_size_nocheck(const volatile void *p, void *res, int size)
{
	__READ_ONCE_SIZE;
}

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 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(). There's at least two memcpy()s: one for the
 * __builtin_memcpy() and then one for the macro doing the copy of variable
 * - '__u' allocated on the stack.
 *
 * 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.
 */
#include <asm/barrier.h>
#include <linux/kasan-checks.h>

#define __READ_ONCE(x, check)						\
({									\
	union { typeof(x) __val; char __c[1]; } __u;			\
	if (check)							\
		__read_once_size(&(x), __u.__c, sizeof(x));		\
	else								\
		__read_once_size_nocheck(&(x), __u.__c, sizeof(x));	\
	smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
	__u.__val;							\
})
#define READ_ONCE(x) __READ_ONCE(x, 1)

/*
 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
 * to hide memory access from KASAN.
 */
#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)

static __no_kasan_or_inline
unsigned long read_word_at_a_time(const void *addr)
{
	kasan_check_read(addr, 1);
	return *(unsigned long *)addr;
}

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

#endif /* __KERNEL__ */

/*
 * Force the compiler to emit 'sym' as a symbol, so that we can reference
 * it from inline assembler. Necessary in case 'sym' could be inlined
 * otherwise, or eliminated entirely due to lack of references that are
 * visible to the compiler.
 */
#define __ADDRESSABLE(sym) \
	static void * __section(".discard.addressable") __used \
		__PASTE(__addressable_##sym, __LINE__) = (void *)&sym;

/**
 * offset_to_ptr - convert a relative memory offset to an absolute pointer
 * @off:	the address of the 32-bit offset value
 */
static inline void *offset_to_ptr(const int *off)
{
	return (void *)((unsigned long)off + *off);
}

#else /* __ASSEMBLY__ */

#ifdef __KERNEL__
#ifndef LINKER_SCRIPT

#ifdef CONFIG_STACK_VALIDATION
.macro ANNOTATE_UNREACHABLE counter:req
\counter:
	.pushsection .discard.unreachable
	.long \counter\()b -.
	.popsection
.endm

.macro ANNOTATE_REACHABLE counter:req
\counter:
	.pushsection .discard.reachable
	.long \counter\()b -.
	.popsection
.endm

.macro ASM_UNREACHABLE
999:
	.pushsection .discard.unreachable
	.long 999b - .
	.popsection
.endm
#else /* CONFIG_STACK_VALIDATION */
.macro ANNOTATE_UNREACHABLE counter:req
.endm

.macro ANNOTATE_REACHABLE counter:req
.endm

.macro ASM_UNREACHABLE
.endm
#endif /* CONFIG_STACK_VALIDATION */

#endif /* LINKER_SCRIPT */
#endif /* __KERNEL__ */
#endif /* __ASSEMBLY__ */

/* 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)
#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_, __LINE__)

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

/* &a[0] degrades to a pointer: a different type from an array */
#define __must_be_array(a)	BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))

#endif /* __LINUX_COMPILER_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1da177e4 LT	2	#ifndef __LINUX_COMPILER_H
	3	#define __LINUX_COMPILER_H
	4
d1515582	5	#include <linux/compiler_types.h>
1da177e4	6
d1515582	7	#ifndef __ASSEMBLY__
6f33d587	8
1da177e4 LT	9	#ifdef __KERNEL__
1da177e4 LT	10
2ed84eeb SR	11	/*
	12	* Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
	13	* to disable branch tracing on a per file basis.
	14	*/
d9ad8bc0 BVA	15	#if defined(CONFIG_TRACE_BRANCH_PROFILING) \
d9ad8bc0 BVA	16	&& !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__)
134e6a03	17	void ftrace_likely_update(struct ftrace_likely_data *f, int val,
d45ae1f7	18	int expect, int is_constant);
1f0d69a9 SR	19
	20	#define likely_notrace(x) __builtin_expect(!!(x), 1)
	21	#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
	22
d45ae1f7	23	#define __branch_check__(x, expect, is_constant) ({ \
2026d357	24	long ______r; \
134e6a03	25	static struct ftrace_likely_data \
e04462fb MO	26	__aligned(4) \
e04462fb MO	27	__section("_ftrace_annotated_branch") \
1f0d69a9	28	______f = { \
134e6a03 SRV	29	.data.func = __func__, \
	30	.data.file = __FILE__, \
	31	.data.line = __LINE__, \
1f0d69a9	32	}; \
d45ae1f7 SRV	33	______r = __builtin_expect(!!(x), expect); \
	34	ftrace_likely_update(&______f, ______r, \
	35	expect, is_constant); \
1f0d69a9 SR	36	______r; \
	37	})
	38
	39	/*
	40	* Using __builtin_constant_p(x) to ignore cases where the return
	41	* value is always the same. This idea is taken from a similar patch
	42	* written by Daniel Walker.
	43	*/
	44	# ifndef likely
d45ae1f7	45	# define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x)))
1f0d69a9 SR	46	# endif
1f0d69a9 SR	47	# ifndef unlikely
d45ae1f7	48	# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
1f0d69a9	49	# endif
2bcd521a SR	50
	51	#ifdef CONFIG_PROFILE_ALL_BRANCHES
	52	/*
	53	* "Define 'is'", Bill Clinton
	54	* "Define 'if'", Steven Rostedt
	55	*/
ab3c9c68 LT	56	#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
ab3c9c68 LT	57	#define __trace_if(cond) \
b33c8ff4	58	if (__builtin_constant_p(!!(cond)) ? !!(cond) : \
2bcd521a SR	59	({ \
	60	int ______r; \
	61	static struct ftrace_branch_data \
e04462fb MO	62	__aligned(4) \
e04462fb MO	63	__section("_ftrace_branch") \
2bcd521a SR	64	______f = { \
	65	.func = __func__, \
	66	.file = __FILE__, \
	67	.line = __LINE__, \
	68	}; \
	69	______r = !!(cond); \
97e7e4f3	70	______f.miss_hit[______r]++; \
2bcd521a SR	71	______r; \
	72	}))
	73	#endif /* CONFIG_PROFILE_ALL_BRANCHES */
	74
1f0d69a9 SR	75	#else
	76	# define likely(x) __builtin_expect(!!(x), 1)
	77	# define unlikely(x) __builtin_expect(!!(x), 0)
	78	#endif
1da177e4 LT	79
	80	/* Optimization barrier */
	81	#ifndef barrier
	82	# define barrier() __memory_barrier()
	83	#endif
	84
7829fb09 DB	85	#ifndef barrier_data
	86	# define barrier_data(ptr) barrier()
	87	#endif
	88
173a3efd AB	89	/* workaround for GCC PR82365 if needed */
	90	#ifndef barrier_before_unreachable
	91	# define barrier_before_unreachable() do { } while (0)
	92	#endif
	93
38938c87	94	/* Unreachable code */
649ea4d5	95	#ifdef CONFIG_STACK_VALIDATION
d0c2e691 JP	96	/*
	97	* These macros help objtool understand GCC code flow for unreachable code.
	98	* The __COUNTER__ based labels are a hack to make each instance of the macros
	99	* unique, to convince GCC not to merge duplicate inline asm statements.
	100	*/
649ea4d5	101	#define annotate_reachable() ({ \
c06c4d80 NA	102	asm volatile("ANNOTATE_REACHABLE counter=%c0" \
c06c4d80 NA	103	: : "i" (__COUNTER__)); \
649ea4d5 JP	104	})
649ea4d5 JP	105	#define annotate_unreachable() ({ \
c06c4d80 NA	106	asm volatile("ANNOTATE_UNREACHABLE counter=%c0" \
c06c4d80 NA	107	: : "i" (__COUNTER__)); \
649ea4d5	108	})
649ea4d5 JP	109	#else
	110	#define annotate_reachable()
	111	#define annotate_unreachable()
	112	#endif
	113
aa5d1b81 KC	114	#ifndef ASM_UNREACHABLE
	115	# define ASM_UNREACHABLE
	116	#endif
38938c87	117	#ifndef unreachable
fe0640eb	118	# define unreachable() do { \
	119	annotate_unreachable(); \
	120	__builtin_unreachable(); \
	121	} while (0)
38938c87 DD	122	#endif
38938c87 DD	123
b67067f1 NP	124	/*
	125	* KENTRY - kernel entry point
	126	* This can be used to annotate symbols (functions or data) that are used
	127	* without their linker symbol being referenced explicitly. For example,
	128	* interrupt vector handlers, or functions in the kernel image that are found
	129	* programatically.
	130	*
	131	* Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
	132	* are handled in their own way (with KEEP() in linker scripts).
	133	*
	134	* KENTRY can be avoided if the symbols in question are marked as KEEP() in the
	135	* linker script. For example an architecture could KEEP() its entire
	136	* boot/exception vector code rather than annotate each function and data.
	137	*/
	138	#ifndef KENTRY
	139	# define KENTRY(sym) \
	140	extern typeof(sym) sym; \
	141	static const unsigned long __kentry_##sym \
	142	__used \
e04462fb	143	__section("___kentry" "+" #sym ) \
b67067f1 NP	144	= (unsigned long)&sym;
	145	#endif
	146
1da177e4 LT	147	#ifndef RELOC_HIDE
	148	# define RELOC_HIDE(ptr, off) \
	149	({ unsigned long __ptr; \
	150	__ptr = (unsigned long) (ptr); \
	151	(typeof(ptr)) (__ptr + (off)); })
	152	#endif
	153
fe8c8a12 CEB	154	#ifndef OPTIMIZER_HIDE_VAR
	155	#define OPTIMIZER_HIDE_VAR(var) barrier()
	156	#endif
	157
6f33d587 RR	158	/* Not-quite-unique ID. */
	159	#ifndef __UNIQUE_ID
	160	# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
	161	#endif
	162
230fa253 CB	163	#include <uapi/linux/types.h>
230fa253 CB	164
d976441f AR	165	#define __READ_ONCE_SIZE \
	166	({ \
	167	switch (size) { \
	168	case 1: (__u8 )res = (volatile __u8 )p; break; \
	169	case 2: (__u16 )res = (volatile __u16 )p; break; \
	170	case 4: (__u32 )res = (volatile __u32 )p; break; \
	171	case 8: (__u64 )res = (volatile __u64 )p; break; \
	172	default: \
	173	barrier(); \
	174	__builtin_memcpy((void )res, (const void )p, size); \
	175	barrier(); \
	176	} \
	177	})
	178
	179	static __always_inline
	180	void __read_once_size(const volatile void p, void res, int size)
230fa253	181	{
d976441f AR	182	__READ_ONCE_SIZE;
	183	}
	184
	185	#ifdef CONFIG_KASAN
	186	/*
bdb5ac80	187	* We can't declare function 'inline' because __no_sanitize_address confilcts
d976441f AR	188	* with inlining. Attempt to inline it may cause a build failure.
	189	* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
	190	* '__maybe_unused' allows us to avoid defined-but-not-used warnings.
	191	*/
163c8d54	192	# define __no_kasan_or_inline __no_sanitize_address notrace __maybe_unused
d976441f	193	#else
bdb5ac80 AR	194	# define __no_kasan_or_inline __always_inline
	195	#endif
	196
	197	static __no_kasan_or_inline
d976441f AR	198	void __read_once_size_nocheck(const volatile void p, void res, int size)
	199	{
	200	__READ_ONCE_SIZE;
230fa253 CB	201	}
230fa253 CB	202
43239cbe	203	static __always_inline void __write_once_size(volatile void p, void res, int size)
230fa253 CB	204	{
	205	switch (size) {
	206	case 1: (volatile __u8 )p = (__u8 )res; break;
	207	case 2: (volatile __u16 )p = (__u16 )res; break;
	208	case 4: (volatile __u32 )p = (__u32 )res; break;
230fa253	209	case 8: (volatile __u64 )p = (__u64 )res; break;
230fa253 CB	210	default:
	211	barrier();
	212	__builtin_memcpy((void )p, (const void )res, size);
230fa253 CB	213	barrier();
	214	}
	215	}
	216
	217	/*
	218	* Prevent the compiler from merging or refetching reads or writes. The
	219	* compiler is also forbidden from reordering successive instances of
b899a850 MR	220	* READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
	221	* particular ordering. One way to make the compiler aware of ordering is to
	222	* put the two invocations of READ_ONCE or WRITE_ONCE in different C
	223	* statements.
230fa253	224	*
b899a850 MR	225	* These two macros will also work on aggregate data types like structs or
	226	* unions. If the size of the accessed data type exceeds the word size of
	227	* the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will
	228	* fall back to memcpy(). There's at least two memcpy()s: one for the
	229	* __builtin_memcpy() and then one for the macro doing the copy of variable
	230	* - '__u' allocated on the stack.
230fa253 CB	231	*
	232	* Their two major use cases are: (1) Mediating communication between
	233	* process-level code and irq/NMI handlers, all running on the same CPU,
b899a850	234	* and (2) Ensuring that the compiler does not fold, spindle, or otherwise
230fa253 CB	235	* mutilate accesses that either do not require ordering or that interact
	236	* with an explicit memory barrier or atomic instruction that provides the
	237	* required ordering.
	238	*/
d1515582	239	#include <asm/barrier.h>
7f1e541f	240	#include <linux/kasan-checks.h>
230fa253	241
d976441f AR	242	#define __READ_ONCE(x, check) \
	243	({ \
	244	union { typeof(x) __val; char __c[1]; } __u; \
	245	if (check) \
	246	__read_once_size(&(x), __u.__c, sizeof(x)); \
	247	else \
	248	__read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \
76ebbe78	249	smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
d976441f AR	250	__u.__val; \
	251	})
	252	#define READ_ONCE(x) __READ_ONCE(x, 1)
	253
	254	/*
	255	* Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need
	256	* to hide memory access from KASAN.
	257	*/
	258	#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0)
230fa253	259
7f1e541f AR	260	static __no_kasan_or_inline
	261	unsigned long read_word_at_a_time(const void *addr)
	262	{
	263	kasan_check_read(addr, 1);
	264	return (unsigned long )addr;
	265	}
	266
43239cbe	267	#define WRITE_ONCE(x, val) \
ba33034f CB	268	({ \
	269	union { typeof(x) __val; char __c[1]; } __u = \
	270	{ .__val = (__force typeof(x)) (val) }; \
	271	__write_once_size(&(x), __u.__c, sizeof(x)); \
	272	__u.__val; \
	273	})
230fa253	274
1da177e4 LT	275	#endif /* __KERNEL__ */
1da177e4 LT	276
7290d580 AB	277	/*
	278	* Force the compiler to emit 'sym' as a symbol, so that we can reference
	279	* it from inline assembler. Necessary in case 'sym' could be inlined
	280	* otherwise, or eliminated entirely due to lack of references that are
	281	* visible to the compiler.
	282	*/
	283	#define __ADDRESSABLE(sym) \
e04462fb	284	static void * __section(".discard.addressable") __used \
7290d580 AB	285	__PASTE(__addressable_##sym, __LINE__) = (void *)&sym;
	286
	287	/**
	288	* offset_to_ptr - convert a relative memory offset to an absolute pointer
	289	* @off: the address of the 32-bit offset value
	290	*/
	291	static inline void offset_to_ptr(const int off)
	292	{
	293	return (void )((unsigned long)off + off);
	294	}
	295
c06c4d80 NA	296	#else /* __ASSEMBLY__ */
	297
	298	#ifdef __KERNEL__
	299	#ifndef LINKER_SCRIPT
	300
	301	#ifdef CONFIG_STACK_VALIDATION
	302	.macro ANNOTATE_UNREACHABLE counter:req
	303	\counter:
	304	.pushsection .discard.unreachable
	305	.long \counter\()b -.
	306	.popsection
	307	.endm
	308
	309	.macro ANNOTATE_REACHABLE counter:req
	310	\counter:
	311	.pushsection .discard.reachable
	312	.long \counter\()b -.
	313	.popsection
	314	.endm
	315
	316	.macro ASM_UNREACHABLE
	317	999:
	318	.pushsection .discard.unreachable
	319	.long 999b - .
	320	.popsection
	321	.endm
	322	#else /* CONFIG_STACK_VALIDATION */
	323	.macro ANNOTATE_UNREACHABLE counter:req
	324	.endm
	325
	326	.macro ANNOTATE_REACHABLE counter:req
	327	.endm
	328
	329	.macro ASM_UNREACHABLE
	330	.endm
	331	#endif /* CONFIG_STACK_VALIDATION */
	332
	333	#endif /* LINKER_SCRIPT */
	334	#endif /* __KERNEL__ */
1da177e4 LT	335	#endif /* __ASSEMBLY__ */
1da177e4 LT	336
9f0cf4ad AV	337	/* Compile time object size, -1 for unknown */
	338	#ifndef __compiletime_object_size
	339	# define __compiletime_object_size(obj) -1
	340	#endif
4a312769 AV	341	#ifndef __compiletime_warning
	342	# define __compiletime_warning(message)
	343	#endif
63312b6a AV	344	#ifndef __compiletime_error
	345	# define __compiletime_error(message)
	346	#endif
c361d3e5	347
c03567a8 JS	348	#ifdef __OPTIMIZE__
c03567a8 JS	349	# define __compiletime_assert(condition, msg, prefix, suffix) \
9a8ab1c3	350	do { \
9a8ab1c3	351	extern void prefix ## suffix(void) __compiletime_error(msg); \
81b45683	352	if (!(condition)) \
9a8ab1c3	353	prefix ## suffix(); \
9a8ab1c3	354	} while (0)
c03567a8 JS	355	#else
	356	# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
	357	#endif
9a8ab1c3 DS	358
	359	#define _compiletime_assert(condition, msg, prefix, suffix) \
	360	__compiletime_assert(condition, msg, prefix, suffix)
	361
	362	/**
	363	* compiletime_assert - break build and emit msg if condition is false
	364	* @condition: a compile-time constant condition to check
	365	* @msg: a message to emit if condition is false
	366	*
	367	* In tradition of POSIX assert, this macro will break the build if the
	368	* supplied condition is false, emitting the supplied error message if the
	369	* compiler has support to do so.
	370	*/
	371	#define compiletime_assert(condition, msg) \
	372	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
	373
47933ad4 PZ	374	#define compiletime_assert_atomic_type(t) \
	375	compiletime_assert(__native_word(t), \
	376	"Need native word sized stores/loads for atomicity.")
	377
ec0bbef6 MO	378	/* &a[0] degrades to a pointer: a different type from an array */
ec0bbef6 MO	379	#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
ec0bbef6	380
1da177e4	381	#endif /* __LINUX_COMPILER_H */