tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Based on arch/arm/lib/clear_user.S
3 *
4 * Copyright (C) 2012 ARM Ltd.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
17 */
18#include <linux/linkage.h>
19
20#include <asm/asm-uaccess.h>
21#include <asm/assembler.h>
22
23 .text
24
25/* Prototype: int __arch_clear_user(void *addr, size_t sz)
26 * Purpose : clear some user memory
27 * Params : addr - user memory address to clear
28 * : sz - number of bytes to clear
29 * Returns : number of bytes NOT cleared
30 *
31 * Alignment fixed up by hardware.
32 */
33ENTRY(__arch_clear_user)
34 uaccess_enable_not_uao x2, x3, x4
35 mov x2, x1 // save the size for fixup return
36 subs x1, x1, #8
37 b.mi 2f
381:
39uao_user_alternative 9f, str, sttr, xzr, x0, 8
40 subs x1, x1, #8
41 b.pl 1b
422: adds x1, x1, #4
43 b.mi 3f
44uao_user_alternative 9f, str, sttr, wzr, x0, 4
45 sub x1, x1, #4
463: adds x1, x1, #2
47 b.mi 4f
48uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
49 sub x1, x1, #2
504: adds x1, x1, #1
51 b.mi 5f
52uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
535: mov x0, #0
54 uaccess_disable_not_uao x2, x3
55 ret
56ENDPROC(__arch_clear_user)
57EXPORT_SYMBOL(__arch_clear_user)
58
59 .section .fixup,"ax"
60 .align 2
619: mov x0, x2 // return the original size
62 ret
63 .previous