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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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2
arch/arm64/Kconfig
View File

@ -17,6 +17,8 @@ config ARM64
select GENERIC_IRQ_SHOW
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select GENERIC_TIME_VSYSCALL
select HARDIRQS_SW_RESEND
select HAVE_ARCH_TRACEHOOK

25
arch/arm64/include/asm/uaccess.h
View File

@ -100,6 +100,7 @@ static inline void set_fs(mm_segment_t fs)
})
#define access_ok(type, addr, size) __range_ok(addr, size)
#define user_addr_max get_fs
/*
* The "__xxx" versions of the user access functions do not verify the address
@ -240,9 +241,6 @@ extern unsigned long __must_check __copy_to_user(void __user *to, const void *fr
extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
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))
@ -276,24 +274,9 @@ 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;
}
extern long strncpy_from_user(char *dest, const char __user *src, long count);
#define strlen_user(s) strnlen_user(s, ~0UL >> 1)
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 /* __ASM_UACCESS_H */

54
arch/arm64/include/asm/word-at-a-time.h Normal file
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@ -0,0 +1,54 @@
/*
* Copyright (C) 2013 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/>.
*/
#ifndef __ASM_WORD_AT_A_TIME_H
#define __ASM_WORD_AT_A_TIME_H
#ifndef __AARCH64EB__
#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)
{
return fls64(mask) >> 3;
}
#else /* __AARCH64EB__ */
#include <asm-generic/word-at-a-time.h>
#endif
#endif /* __ASM_WORD_AT_A_TIME_H */

5
arch/arm64/kernel/arm64ksyms.c
View File

@ -29,13 +29,10 @@
#include <asm/checksum.h>
/* user mem (segment) */
EXPORT_SYMBOL(__strnlen_user);
EXPORT_SYMBOL(__strncpy_from_user);
EXPORT_SYMBOL(copy_page);
EXPORT_SYMBOL(clear_page);
/* user mem (segment) */
EXPORT_SYMBOL(__copy_from_user);
EXPORT_SYMBOL(__copy_to_user);
EXPORT_SYMBOL(__clear_user);

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
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@ -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