Commit 8c56cc8b authored by Will Deacon's avatar Will Deacon Committed by Russell King

ARM: 7449/1: use generic strnlen_user and strncpy_from_user functions

This patch implements the word-at-a-time interface for ARM using the
same algorithm as x86. We use the fls macro from ARMv5 onwards, where
we have a clz instruction available which saves us a mov instruction
when targetting Thumb-2. For older CPUs, we use the magic 0x0ff0001
constant. 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.
Reviewed-by: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 4295b898
......@@ -46,6 +46,8 @@ config ARM
select GENERIC_SMP_IDLE_THREAD
select KTIME_SCALAR
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
help
The ARM series is a line of low-power-consumption RISC chip designs
licensed by ARM Ltd and targeted at embedded applications and
......
......@@ -189,6 +189,9 @@ static inline void set_fs(mm_segment_t fs)
#define access_ok(type,addr,size) (__range_ok(addr,size) == 0)
#define user_addr_max() \
(segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
/*
* The "__xxx" versions of the user access functions do not verify the
* address space - it must have been done previously with a separate
......@@ -398,9 +401,6 @@ extern unsigned long __must_check __clear_user_std(void __user *addr, unsigned l
#define __clear_user(addr,n) (memset((void __force *)addr, 0, n), 0)
#endif
extern unsigned long __must_check __strncpy_from_user(char *to, const char __user *from, unsigned long count);
extern unsigned long __must_check __strnlen_user(const char __user *s, long n);
static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
{
if (access_ok(VERIFY_READ, from, n))
......@@ -427,24 +427,9 @@ static inline unsigned long __must_check clear_user(void __user *to, unsigned lo
return n;
}
static inline long __must_check strncpy_from_user(char *dst, const char __user *src, long count)
{
long res = -EFAULT;
if (access_ok(VERIFY_READ, src, 1))
res = __strncpy_from_user(dst, src, count);
return res;
}
#define strlen_user(s) strnlen_user(s, ~0UL >> 1)
extern long strncpy_from_user(char *dest, const char __user *src, long count);
static inline long __must_check strnlen_user(const char __user *s, long n)
{
unsigned long res = 0;
if (__addr_ok(s))
res = __strnlen_user(s, n);
return res;
}
extern __must_check long strlen_user(const char __user *str);
extern __must_check long strnlen_user(const char __user *str, long n);
#endif /* _ASMARM_UACCESS_H */
#ifndef __ASM_ARM_WORD_AT_A_TIME_H
#define __ASM_ARM_WORD_AT_A_TIME_H
#ifndef __ARMEB__
/*
* Little-endian word-at-a-time zero byte handling.
* Heavily based on the x86 algorithm.
*/
#include <linux/kernel.h>
struct word_at_a_time {
const unsigned long one_bits, high_bits;
};
#define WORD_AT_A_TIME_CONSTANTS { REPEAT_BYTE(0x01), REPEAT_BYTE(0x80) }
static inline unsigned long has_zero(unsigned long a, unsigned long *bits,
const struct word_at_a_time *c)
{
unsigned long mask = ((a - c->one_bits) & ~a) & c->high_bits;
*bits = mask;
return mask;
}
#define prep_zero_mask(a, bits, c) (bits)
static inline unsigned long create_zero_mask(unsigned long bits)
{
bits = (bits - 1) & ~bits;
return bits >> 7;
}
static inline unsigned long find_zero(unsigned long mask)
{
unsigned long ret;
#if __LINUX_ARM_ARCH__ >= 5
/* We have clz available. */
ret = fls(mask) >> 3;
#else
/* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
ret = (0x0ff0001 + mask) >> 23;
/* Fix the 1 for 00 case */
ret &= mask;
#endif
return ret;
}
#else /* __ARMEB__ */
#include <asm-generic/word-at-a-time.h>
#endif
#endif /* __ASM_ARM_WORD_AT_A_TIME_H */
......@@ -87,10 +87,6 @@ EXPORT_SYMBOL(memmove);
EXPORT_SYMBOL(memchr);
EXPORT_SYMBOL(__memzero);
/* user mem (segment) */
EXPORT_SYMBOL(__strnlen_user);
EXPORT_SYMBOL(__strncpy_from_user);
#ifdef CONFIG_MMU
EXPORT_SYMBOL(copy_page);
......
......@@ -8,7 +8,6 @@ lib-y := backtrace.o changebit.o csumipv6.o csumpartial.o \
csumpartialcopy.o csumpartialcopyuser.o clearbit.o \
delay.o findbit.o memchr.o memcpy.o \
memmove.o memset.o memzero.o setbit.o \
strncpy_from_user.o strnlen_user.o \
strchr.o strrchr.o \
testchangebit.o testclearbit.o testsetbit.o \
ashldi3.o ashrdi3.o lshrdi3.o muldi3.o \
......
/*
* linux/arch/arm/lib/strncpy_from_user.S
*
* Copyright (C) 1995-2000 Russell King
*
* 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
/*
* Copy a string from user space to kernel space.
* r0 = dst, r1 = src, r2 = 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 ip, r1
1: subs r2, r2, #1
ldrusr r3, r1, 1, pl
bmi 2f
strb r3, [r0], #1
teq r3, #0
bne 1b
sub r1, r1, #1 @ take NUL character out of count
2: sub r0, r1, ip
mov pc, lr
ENDPROC(__strncpy_from_user)
.pushsection .fixup,"ax"
.align 0
9001: mov r3, #0
strb r3, [r0, #0] @ null terminate
mov r0, #-EFAULT
mov pc, lr
.popsection
/*
* linux/arch/arm/lib/strnlen_user.S
*
* Copyright (C) 1995-2000 Russell King
*
* 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
teq r3, #0
beq 2f
subs 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
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