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arm64: use generic strnlen_user and strncpy_from_user functions

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This patch implements the word-at-a-time interface for arm64 using the
same algorithm as ARM. We use the fls64 macro, which expands to a clz
instruction via a compiler builtin. Big-endian configurations make use
of the implementation from asm-generic.

With this implemented, we can replace our byte-at-a-time strnlen_user
and strncpy_from_user functions with the optimised generic versions.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon
2013-11-06 17:20:22 +00:00
committed by Catalin Marinas
parent 7158627686
commit 12a0ef7b0a
7 changed files with 64 additions and 127 deletions
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8
arch/arm64/lib/Makefile
View File

@@ -1,6 +1,4 @@
lib-y := bitops.o delay.o \
strncpy_from_user.o strnlen_user.o clear_user.o \
copy_from_user.o copy_to_user.o copy_in_user.o \
copy_page.o clear_page.o \
memchr.o memcpy.o memmove.o memset.o \
lib-y := bitops.o clear_user.o delay.o copy_from_user.o \
copy_to_user.o copy_in_user.o copy_page.o \
clear_page.o memchr.o memcpy.o memmove.o memset.o \
strchr.o strrchr.o

50
arch/arm64/lib/strncpy_from_user.S
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@@ -1,50 +0,0 @@
/*
* 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

47
arch/arm64/lib/strnlen_user.S
View File

@@ -1,47 +0,0 @@
/*
* Based on arch/arm/lib/strnlen_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
/* Prototype: unsigned long __strnlen_user(const char *str, long n)
* Purpose : get length of a string in user memory
* Params : str - address of string in user memory
* Returns : length of string *including terminator*
* or zero on exception, or n if too long
*/
ENTRY(__strnlen_user)
mov x2, x0
1: subs x1, x1, #1
b.mi 2f
USER(9f, ldrb w3, [x0], #1 )
cbnz w3, 1b
2: sub x0, x0, x2
ret
ENDPROC(__strnlen_user)
.section .fixup,"ax"
.align 0
9: mov x0, #0
ret
.previous