linux/arch/arm64/lib/copy_from_user.S

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2012 ARM Ltd.
 */

#include <linux/linkage.h>

#include <asm/asm-uaccess.h>
#include <asm/assembler.h>
#include <asm/cache.h>

/*
 * Copy from user space to a kernel buffer (alignment handled by the hardware)
 *
 * Parameters:
 *	x0 - to
 *	x1 - from
 *	x2 - n
 * Returns:
 *	x0 - bytes not copied
 */

	.macro ldrb1 ptr, regB, val
	uao_user_alternative 9998f, ldrb, ldtrb, \ptr, \regB, \val
	.endm

	.macro strb1 ptr, regB, val
	strb \ptr, [\regB], \val
	.endm

	.macro ldrh1 ptr, regB, val
	uao_user_alternative 9998f, ldrh, ldtrh, \ptr, \regB, \val
	.endm

	.macro strh1 ptr, regB, val
	strh \ptr, [\regB], \val
	.endm

	.macro ldr1 ptr, regB, val
	uao_user_alternative 9998f, ldr, ldtr, \ptr, \regB, \val
	.endm

	.macro str1 ptr, regB, val
	str \ptr, [\regB], \val
	.endm

	.macro ldp1 ptr, regB, regC, val
	uao_ldp 9998f, \ptr, \regB, \regC, \val
	.endm

	.macro stp1 ptr, regB, regC, val
	stp \ptr, \regB, [\regC], \val
	.endm

end	.req	x5
SYM_FUNC_START(__arch_copy_from_user)
	add	end, x0, x2
#include "copy_template.S"
	mov	x0, #0				// Nothing to copy
	ret
SYM_FUNC_END(__arch_copy_from_user)
EXPORT_SYMBOL(__arch_copy_from_user)

	.section .fixup,"ax"
	.align	2
9998:	sub	x0, end, dst			// bytes not copied
	ret
	.previous