strncpy_from_user.S
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/*
* Copy to/from userspace with optional address space checking.
*
* Copyright 2004-2006 Atmel Corporation
*
* 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/errno.h>
#include <asm/page.h>
#include <asm/thread_info.h>
#include <asm/asm.h>
/*
* long strncpy_from_user(char *dst, const char *src, long count)
*
* On success, returns the length of the string, not including
* the terminating NUL.
*
* If the string is longer than count, returns count
*
* If userspace access fails, returns -EFAULT
*/
.text
.align 1
.global strncpy_from_user
.type strncpy_from_user, "function"
strncpy_from_user:
mov r9, -EFAULT
branch_if_kernel r8, __strncpy_from_user
ret_if_privileged r8, r11, r10, r9
.global __strncpy_from_user
.type __strncpy_from_user, "function"
__strncpy_from_user:
cp.w r10, 0
reteq 0
mov r9, r10
1: ld.ub r8, r11++
st.b r12++, r8
cp.w r8, 0
breq 2f
sub r9, 1
brne 1b
2: sub r10, r9
retal r10
.section .fixup, "ax"
.align 1
3: mov r12, -EFAULT
retal r12
.section __ex_table, "a"
.align 2
.long 1b, 3b