0aea86a217
This patch add support for various user access functions. These functions use the standard LDR/STR instructions and not the LDRT/STRT variants in order to allow kernel addresses (after set_fs(KERNEL_DS)). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
51 lines
1.3 KiB
ArmAsm
51 lines
1.3 KiB
ArmAsm
/*
|
|
* Based on arch/arm/lib/strncpy_from_user.S
|
|
*
|
|
* Copyright (C) 1995-2000 Russell King
|
|
* 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/assembler.h>
|
|
#include <asm/errno.h>
|
|
|
|
.text
|
|
.align 5
|
|
|
|
/*
|
|
* Copy a string from user space to kernel space.
|
|
* x0 = dst, x1 = src, x2 = byte length
|
|
* returns the number of characters copied (strlen of copied string),
|
|
* -EFAULT on exception, or "len" if we fill the whole buffer
|
|
*/
|
|
ENTRY(__strncpy_from_user)
|
|
mov x4, x1
|
|
1: subs x2, x2, #1
|
|
bmi 2f
|
|
USER(9f, ldrb w3, [x1], #1 )
|
|
strb w3, [x0], #1
|
|
cbnz w3, 1b
|
|
sub x1, x1, #1 // take NUL character out of count
|
|
2: sub x0, x1, x4
|
|
ret
|
|
ENDPROC(__strncpy_from_user)
|
|
|
|
.section .fixup,"ax"
|
|
.align 0
|
|
9: strb wzr, [x0] // null terminate
|
|
mov x0, #-EFAULT
|
|
ret
|
|
.previous
|