1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
| /* 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:
| uao_user_alternative 9f, str, sttr, xzr, x0, 8
| subs x1, x1, #8
| b.pl 1b
| 2: adds x1, x1, #4
| b.mi 3f
| uao_user_alternative 9f, str, sttr, wzr, x0, 4
| sub x1, x1, #4
| 3: adds x1, x1, #2
| b.mi 4f
| uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
| sub x1, x1, #2
| 4: adds x1, x1, #1
| b.mi 5f
| uao_user_alternative 9f, strb, 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
|
|
