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
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
/*
* Based on arch/arm/lib/clear_user.S
*
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/linkage.h>
#include <asm/alternative.h>
#include <asm/assembler.h>
#include <asm/cpufeature.h>
#include <asm/sysreg.h>
.text
/* Prototype: int __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.
*/
ENTRY(__clear_user)
ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \
CONFIG_ARM64_PAN)
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
ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \
CONFIG_ARM64_PAN)
ret
ENDPROC(__clear_user)
.section .fixup,"ax"
.align 2
9: mov x0, x2 // return the original size
ret
.previous
|
