linux/arch/unicore32/lib/strnlen_user.S
GuanXuetao 77c93b2f23 unicore32 additional architecture files: low-level lib: uaccess
This patch implements low-level uaccess libraries.

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: Arnd Bergmann <arnd@arndb.de>
2011-03-17 09:19:13 +08:00

42 lines
966 B
ArmAsm

/*
* linux/arch/unicore32/lib/strnlen_user.S
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Copyright (C) 2001-2010 GUAN Xue-tao
*
* 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.
*/
#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 + 1 if too long
*/
ENTRY(__strnlen_user)
mov r2, r0
1:
ldrusr r3, r0, 1
cxor.a r3, #0
beq 2f
sub.a r1, r1, #1
bne 1b
add r0, r0, #1
2: sub r0, r0, r2
mov pc, lr
ENDPROC(__strnlen_user)
.pushsection .fixup,"ax"
.align 0
9001: mov r0, #0
mov pc, lr
.popsection