diff options
author | Will Deacon <will.deacon@arm.com> | 2012-07-06 15:45:39 +0100 |
---|---|---|
committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2012-07-09 17:41:11 +0100 |
commit | 8c56cc8be5b38e3684eba96dc9b3f7ca7e495755 (patch) | |
tree | eccb882c8c5f1cc81fc226c769fc9ec99a45145b /arch/arm/include/asm | |
parent | 4295b898f5a5c7e62ae68e7a4ecc4b414622ffe6 (diff) | |
download | linux-8c56cc8be5b38e3684eba96dc9b3f7ca7e495755.tar.bz2 |
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: 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>
Diffstat (limited to 'arch/arm/include/asm')
-rw-r--r-- | arch/arm/include/asm/uaccess.h | 27 | ||||
-rw-r--r-- | arch/arm/include/asm/word-at-a-time.h | 55 |
2 files changed, 61 insertions, 21 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 71f6536d17ac..479a6352e0b5 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -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 */ diff --git a/arch/arm/include/asm/word-at-a-time.h b/arch/arm/include/asm/word-at-a-time.h new file mode 100644 index 000000000000..74b2d4578577 --- /dev/null +++ b/arch/arm/include/asm/word-at-a-time.h @@ -0,0 +1,55 @@ +#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 */ |