arch/x86/include/asm/atomic64_32.h

Source file repositories/reference/linux-study-clean/arch/x86/include/asm/atomic64_32.h

File Facts

System
Linux kernel
Corpus path
arch/x86/include/asm/atomic64_32.h
Extension
.h
Size
8251 bytes
Lines
313
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _ASM_X86_ATOMIC64_32_H
#define _ASM_X86_ATOMIC64_32_H

#include <linux/compiler.h>
#include <linux/types.h>
//#include <asm/cmpxchg.h>

/* An 64bit atomic type */

typedef struct {
	s64 __aligned(8) counter;
} atomic64_t;

#define ATOMIC64_INIT(val)	{ (val) }

/*
 * Read an atomic64_t non-atomically.
 *
 * This is intended to be used in cases where a subsequent atomic operation
 * will handle the torn value, and can be used to prime the first iteration
 * of unconditional try_cmpxchg() loops, e.g.:
 *
 * 	s64 val = arch_atomic64_read_nonatomic(v);
 * 	do { } while (!arch_atomic64_try_cmpxchg(v, &val, val OP i);
 *
 * This is NOT safe to use where the value is not always checked by a
 * subsequent atomic operation, such as in conditional try_cmpxchg() loops
 * that can break before the atomic operation, e.g.:
 *
 * 	s64 val = arch_atomic64_read_nonatomic(v);
 * 	do {
 * 		if (condition(val))
 * 			break;
 * 	} while (!arch_atomic64_try_cmpxchg(v, &val, val OP i);
 */
static __always_inline s64 arch_atomic64_read_nonatomic(const atomic64_t *v)
{
	/* See comment in arch_atomic_read(). */
	return __READ_ONCE(v->counter);
}

#define __ATOMIC64_DECL(sym) void atomic64_##sym(atomic64_t *, ...)
#ifndef ATOMIC64_EXPORT
#define ATOMIC64_DECL_ONE __ATOMIC64_DECL
#else
#define ATOMIC64_DECL_ONE(sym) __ATOMIC64_DECL(sym); \
	ATOMIC64_EXPORT(atomic64_##sym)
#endif

#ifdef CONFIG_X86_CX8
#define __alternative_atomic64(f, g, out, in, clobbers...)		\
	asm volatile("call %c[func]"					\
		     : ALT_OUTPUT_SP(out) \
		     : [func] "i" (atomic64_##g##_cx8)			\
		       COMMA(in)					\
		     : clobbers)

#define ATOMIC64_DECL(sym) ATOMIC64_DECL_ONE(sym##_cx8)
#else
#define __alternative_atomic64(f, g, out, in, clobbers...)		\
	alternative_call(atomic64_##f##_386, atomic64_##g##_cx8,	\
			 X86_FEATURE_CX8, ASM_OUTPUT(out),		\
			 ASM_INPUT(in), clobbers)

#define ATOMIC64_DECL(sym) ATOMIC64_DECL_ONE(sym##_cx8); \
	ATOMIC64_DECL_ONE(sym##_386)

ATOMIC64_DECL_ONE(add_386);
ATOMIC64_DECL_ONE(sub_386);
ATOMIC64_DECL_ONE(inc_386);
ATOMIC64_DECL_ONE(dec_386);
#endif

#define alternative_atomic64(f, out, in, clobbers...) \
	__alternative_atomic64(f, f, ASM_OUTPUT(out), ASM_INPUT(in), clobbers)

ATOMIC64_DECL(read);
ATOMIC64_DECL(set);
ATOMIC64_DECL(xchg);
ATOMIC64_DECL(add_return);
ATOMIC64_DECL(sub_return);
ATOMIC64_DECL(inc_return);
ATOMIC64_DECL(dec_return);
ATOMIC64_DECL(dec_if_positive);
ATOMIC64_DECL(inc_not_zero);
ATOMIC64_DECL(add_unless);

#undef ATOMIC64_DECL
#undef ATOMIC64_DECL_ONE
#undef __ATOMIC64_DECL

Annotation

Implementation Notes