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Commit 1129585a authored by Vitaly Mayatskikh's avatar Vitaly Mayatskikh Committed by Ingo Molnar
Browse files

x86: introduce copy_user_handle_tail() routine 



Introduce generic C routine for handling necessary tail operations after
protection fault in copy_*_user on x86.

Signed-off-by: default avatarVitaly Mayatskikh <v.mayatskih@gmail.com>
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent de989ef0

arch/x86/lib/usercopy_64.c

+23 −0
Original line number Diff line number Diff line
@@ -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;

}

include/asm-x86/uaccess_64.h

+3 −0
Original line number Diff line number Diff line
@@ -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 */