diff options
| -rw-r--r-- | arch/x86/lib/usercopy_64.c | 23 | ||||
| -rw-r--r-- | include/asm-x86/uaccess_64.h | 3 |
2 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index 0c89d1bb0287..f4df6e7c718b 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 4e3ec004e14a..515d4dce96b5 100644 --- a/include/asm-x86/uaccess_64.h +++ b/include/asm-x86/uaccess_64.h @@ -195,4 +195,7 @@ 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 */ |