path: root/arch/arm/include/asm/uaccess.h
diff options
authorWill Deacon <will.deacon@arm.com>2012-07-06 15:45:39 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-07-09 17:41:11 +0100
commit8c56cc8be5b38e3684eba96dc9b3f7ca7e495755 (patch)
treeeccb882c8c5f1cc81fc226c769fc9ec99a45145b /arch/arm/include/asm/uaccess.h
parent4295b898f5a5c7e62ae68e7a4ecc4b414622ffe6 (diff)
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/uaccess.h')
1 files changed, 6 insertions, 21 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 71f6536d17a..479a6352e0b 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)
-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 */