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

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/*

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 * Copyright (c) 2006  Ralf Baechle ([email protected])

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 * Copyright (c) 2018  Jim Wilson ([email protected])

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 */

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#ifndef _ASM_RISCV_FUTEX_H

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#define _ASM_RISCV_FUTEX_H

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#include <linux/futex.h>

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#include <linux/uaccess.h>

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#include <linux/errno.h>

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#include <asm/asm.h>

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#include <asm/asm-extable.h>

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/* We don't even really need the extable code, but for now keep it simple */

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#ifndef CONFIG_MMU

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#define __enable_user_access()		do { } while (0)

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#define __disable_user_access()		do { } while (0)

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#endif

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

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{								\

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	__enable_user_access();					\

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	__asm__ __volatile__ (					\

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	"1:	" insn "				\n"	\

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	"2:						\n"	\

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	_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %[r])			\

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	: [r] "+r" (ret), [ov] "=&r" (oldval),			\

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	  [u] "+m" (*uaddr)					\

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	: [op] "Jr" (oparg)					\

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	: "memory");						\

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	__disable_user_access();				\

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

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		return -EFAULT;

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	switch (op) {

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	case FUTEX_OP_SET:

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		__futex_atomic_op("amoswap.w.aqrl %[ov],%z[op],%[u]",

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				  ret, oldval, uaddr, oparg);

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		break;

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	case FUTEX_OP_ADD:

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		__futex_atomic_op("amoadd.w.aqrl %[ov],%z[op],%[u]",

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				  ret, oldval, uaddr, oparg);

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		break;

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	case FUTEX_OP_OR:

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		__futex_atomic_op("amoor.w.aqrl %[ov],%z[op],%[u]",

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				  ret, oldval, uaddr, oparg);

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		break;

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	case FUTEX_OP_ANDN:

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		__futex_atomic_op("amoand.w.aqrl %[ov],%z[op],%[u]",

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				  ret, oldval, uaddr, ~oparg);

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		break;

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	case FUTEX_OP_XOR:

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		__futex_atomic_op("amoxor.w.aqrl %[ov],%z[op],%[u]",

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				  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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	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,

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			      u32 oldval, u32 newval)

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{

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	int ret = 0;

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	u32 val;

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	uintptr_t tmp;

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

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		return -EFAULT;

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	__enable_user_access();

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	__asm__ __volatile__ (

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	"1:	lr.w %[v],%[u]			        \n"

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	"	bne %[v],%z[ov],3f			\n"

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	"2:	sc.w.aqrl %[t],%z[nv],%[u]		\n"

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	"	bnez %[t],1b				\n"

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	"3:						\n"

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		_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %[r])	\

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		_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %[r])	\

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	: [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)

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	: [ov] "Jr" ((long)(int)oldval), [nv] "Jr" (newval)

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	: "memory");

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	__disable_user_access();

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	*uval = val;

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	return ret;

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}

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#endif /* _ASM_RISCV_FUTEX_H */

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