Messages in this thread Patch in this message | | | From | Vitaly Mayatskikh <> | Subject | Re: [PATCH 1/2] Introduce copy_user_handle_tail routine | Date | Wed, 02 Jul 2008 15:48:21 +0200 |
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Introduce generic C routine for handling necessary tail operations after protection fault in copy_*_user on x86.
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index 0c89d1b..3ab4ec8 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -158,3 +158,26 @@ unsigned long copy_in_user(void __user *to, const void __user *from, unsigned le } EXPORT_SYMBOL(copy_in_user); +/* + * Try to copy last bytes and clear the rest if needed. + * Since protection fault in copy_from/to_user is not a normal situation, + * it is not necessary to optimize tail handling. + */ +unsigned long +copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest) +{ + char c; + unsigned zero_len; + + for (; len; --len) { + if (__get_user_nocheck(c, from++, sizeof(char))) + break; + if (__put_user_nocheck(c, to++, sizeof(char))) + break; + } + + for (c = 0, zero_len = len; zerorest && zero_len; --zero_len) + if (__put_user_nocheck(c, to++, sizeof(char))) + break; + return len; +} diff --git a/include/asm-x86/uaccess_64.h b/include/asm-x86/uaccess_64.h index b8a2f43..1dc2003 100644 --- a/include/asm-x86/uaccess_64.h +++ b/include/asm-x86/uaccess_64.h @@ -455,4 +455,7 @@ static inline int __copy_from_user_inatomic_nocache(void *dst, return __copy_user_nocache(dst, src, size, 0); } +unsigned long +copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest); + #endif /* __X86_64_UACCESS_H */ Signed-off-by: Vitaly Mayatskikh <v.mayatskih@gmail.com>
-- wbr, Vitaly
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