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

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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: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon
2012-07-06 15:45:39 +01:00
committed by Russell King
parent 4295b898f5
commit 8c56cc8be5
7 changed files with 63 additions and 109 deletions
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27
arch/arm/include/asm/uaccess.h
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@@ -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;
}
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 /* _ASMARM_UACCESS_H */