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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/loongarch/include/asm/futex.h
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/* SPDX-License-Identifier: GPL-2.0 */

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/*

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 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited

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 */

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#ifndef _ASM_FUTEX_H

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#define _ASM_FUTEX_H

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#include <linux/futex.h>

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#include <linux/uaccess.h>

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#include <asm/asm-extable.h>

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#include <asm/barrier.h>

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#include <asm/errno.h>

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#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)		\

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{									\

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	__asm__ __volatile__(						\

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	"1:	ll.w	%1, %4 # __futex_atomic_op\n"		\

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	"	" insn	"				\n"	\

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	"2:	sc.w	$t0, %2				\n"	\

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	"	beqz	$t0, 1b				\n"	\

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	"3:						\n"	\

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	_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %0)			\

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	_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %0)			\

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	: "=r" (ret), "=&r" (oldval),				\

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	  "=ZC" (*uaddr)					\

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	: "0" (0), "ZC" (*uaddr), "Jr" (oparg)			\

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	: "memory", "t0");					\

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}

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static inline int

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arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr)

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{

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	int oldval = 0, ret = 0;

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	pagefault_disable();

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	switch (op) {

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	case FUTEX_OP_SET:

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		__futex_atomic_op("move $t0, %z5", ret, oldval, uaddr, oparg);

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		break;

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	case FUTEX_OP_ADD:

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		__futex_atomic_op("add.w $t0, %1, %z5", ret, oldval, uaddr, oparg);

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		break;

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	case FUTEX_OP_OR:

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		__futex_atomic_op("or	$t0, %1, %z5", ret, oldval, uaddr, oparg);

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		break;

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	case FUTEX_OP_ANDN:

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		__futex_atomic_op("and	$t0, %1, %z5", ret, oldval, uaddr, ~oparg);

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		break;

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	case FUTEX_OP_XOR:

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		__futex_atomic_op("xor	$t0, %1, %z5", ret, oldval, uaddr, oparg);

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		break;

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	default:

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		ret = -ENOSYS;

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	}

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	pagefault_enable();

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	if (!ret)

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		*oval = oldval;

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	return ret;

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}

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static inline int

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futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 oldval, u32 newval)

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{

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	int ret = 0;

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	u32 val = 0;

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	if (!access_ok(uaddr, sizeof(u32)))

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		return -EFAULT;

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	__asm__ __volatile__(

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	"# futex_atomic_cmpxchg_inatomic			\n"

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	"1:	ll.w	%1, %3					\n"

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	"	bne	%1, %z4, 3f				\n"

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	"	move	$t0, %z5				\n"

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	"2:	sc.w	$t0, %2					\n"

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	"	beqz	$t0, 1b					\n"

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	"3:							\n"

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	__WEAK_LLSC_MB

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	_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %0)

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	_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %0)

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	: "+r" (ret), "=&r" (val), "=ZC" (*uaddr)

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	: "ZC" (*uaddr), "Jr" (oldval), "Jr" (newval)

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	: "memory", "t0");

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	*uval = val;

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	return ret;

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}

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#endif /* _ASM_FUTEX_H */

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