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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2021 Arm Ltd.
*/
#include <linux/linkage.h>
#include <asm/asm-uaccess.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)
add x2, x0, x1
#ifdef CONFIG_AS_HAS_MOPS
.arch_extension mops
alternative_if_not ARM64_HAS_MOPS
b .Lno_mops
alternative_else_nop_endif
USER(9f, setpt [x0]!, x1!, xzr)
USER(6f, setmt [x0]!, x1!, xzr)
USER(6f, setet [x0]!, x1!, xzr)
mov x0, #0
ret
.Lno_mops:
#endif
subs x1, x1, #8
b.mi 2f
1: .p2align 4
USER(9f, sttr xzr, [x0])
add x0, x0, #8
subs x1, x1, #8
b.hi 1b
USER(9f, sttr xzr, [x2, #-8])
mov x0, #0
ret
2: tbz x1, #2, 3f
USER(9f, sttr wzr, [x0])
USER(8f, sttr wzr, [x2, #-4])
mov x0, #0
ret
3: tbz x1, #1, 4f
USER(9f, sttrh wzr, [x0])
4: tbz x1, #0, 5f
USER(7f, sttrb wzr, [x2, #-1])
5: mov x0, #0
ret
// Exception fixups
6: b.cs 9f
// Registers are in Option A format
add x0, x0, x1
b 9f
7: sub x0, x2, #5 // Adjust for faulting on the final byte...
8: add x0, x0, #4 // ...or the second word of the 4-7 byte case
9: sub x0, x2, x0
ret
SYM_FUNC_END(__arch_clear_user)
EXPORT_SYMBOL(__arch_clear_user)
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