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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Based on arch/arm/lib/clear_user.S
*
* Copyright (C) 2012 ARM Ltd.
*/
#include <linux/linkage.h>
#include <asm/asm-uaccess.h>
#include <asm/assembler.h>
.text
/* Prototype: int __arch_clear_user(void *addr, size_t sz)
* Purpose : clear some user memory
* Params : addr - user memory address to clear
* : sz - number of bytes to clear
* Returns : number of bytes NOT cleared
*
* Alignment fixed up by hardware.
*/
SYM_FUNC_START(__arch_clear_user)
mov x2, x1 // save the size for fixup return
subs x1, x1, #8
b.mi 2f
1:
user_ldst 9f, sttr, xzr, x0, 8
subs x1, x1, #8
b.pl 1b
2: adds x1, x1, #4
b.mi 3f
user_ldst 9f, sttr, wzr, x0, 4
sub x1, x1, #4
3: adds x1, x1, #2
b.mi 4f
user_ldst 9f, sttrh, wzr, x0, 2
sub x1, x1, #2
4: adds x1, x1, #1
b.mi 5f
user_ldst 9f, sttrb, wzr, x0, 0
5: mov x0, #0
ret
SYM_FUNC_END(__arch_clear_user)
EXPORT_SYMBOL(__arch_clear_user)
.section .fixup,"ax"
.align 2
9: mov x0, x2 // return the original size
ret
.previous
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