linux/arch/arm64/lib/clear_user.S
Will Deacon f71c2ffcb2 arm64: uaccess: Mask __user pointers for __arch_{clear, copy_*}_user
Like we've done for get_user and put_user, ensure that user pointers
are masked before invoking the underlying __arch_{clear,copy_*}_user
operations.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-02-06 22:53:40 +00:00

62 lines
1.6 KiB
ArmAsm

/*
* 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/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.
*/
ENTRY(__arch_clear_user)
uaccess_enable_not_uao x2, x3, x4
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
uaccess_disable_not_uao x2, x3
ret
ENDPROC(__arch_clear_user)
.section .fixup,"ax"
.align 2
9: mov x0, x2 // return the original size
ret
.previous