arch/x86/include/asm/futex.h

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

File Facts

System
Linux kernel
Corpus path
arch/x86/include/asm/futex.h
Extension
.h
Size
2520 bytes
Lines
99
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

switch (op) {
		case FUTEX_OP_SET:
			unsafe_atomic_op1("xchgl %0, %2", oval, uaddr, oparg, Efault);
			break;
		case FUTEX_OP_ADD:
			unsafe_atomic_op1(LOCK_PREFIX "xaddl %0, %2", oval, uaddr, oparg, Efault);
			break;
		case FUTEX_OP_OR:
			unsafe_atomic_op2("orl %4, %3", oval, uaddr, oparg, Efault);
			break;
		case FUTEX_OP_ANDN:
			unsafe_atomic_op2("andl %4, %3", oval, uaddr, ~oparg, Efault);
			break;
		case FUTEX_OP_XOR:
			unsafe_atomic_op2("xorl %4, %3", oval, uaddr, oparg, Efault);
			break;
		default:
			return -ENOSYS;
		}
	}
	return 0;
Efault:
	return -EFAULT;
}

static inline int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
						u32 oldval, u32 newval)
{
	int ret = 0;

	scoped_user_rw_access(uaddr, Efault) {
		asm_inline volatile("\n"
				    "1:\t" LOCK_PREFIX "cmpxchgl %3, %2\n"
				    "2:\n"
				    _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_EFAULT_REG, %0)
				    : "+r" (ret), "=a" (oldval), "+m" (*uaddr)
				    : "r" (newval), "1" (oldval)
				    : "memory");
		*uval = oldval;
	}
	return ret;
Efault:
	return -EFAULT;
}

#endif
#endif /* _ASM_X86_FUTEX_H */

Annotation

Implementation Notes