amd64: get rid of zeroing (122b05dd) · Commits · 戴 / test

arch/x86/include/asm/uaccess.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -379,6 +379,18 @@ do { \
		: "=r" (err), ltype(x) \
		: "m" (__m(addr)), "i" (errret), "0" (err))

		#define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret) \
		asm volatile("\n" \
		"1: mov"itype" %2,%"rtype"1\n" \
		"2:\n" \
		".section .fixup,\"ax\"\n" \
		"3: mov %3,%0\n" \
		" jmp 2b\n" \
		".previous\n" \
		_ASM_EXTABLE(1b, 3b) \
		: "=r" (err), ltype(x) \
		: "m" (__m(addr)), "i" (errret), "0" (err))

		/*
		* This doesn't do __uaccess_begin/end - the exception handling
		* around it must do that.

arch/x86/include/asm/uaccess_64.h

+8 −8

Original line number	Diff line number	Diff line
		@@ -59,44 +59,44 @@ int __copy_from_user_nocheck(void dst, const void __user src, unsigned size)
		switch (size) {
		case 1:
		__uaccess_begin();
		__get_user_asm((u8 )dst, (u8 __user *)src,
		__get_user_asm_nozero((u8 )dst, (u8 __user *)src,
		ret, "b", "b", "=q", 1);
		__uaccess_end();
		return ret;
		case 2:
		__uaccess_begin();
		__get_user_asm((u16 )dst, (u16 __user *)src,
		__get_user_asm_nozero((u16 )dst, (u16 __user *)src,
		ret, "w", "w", "=r", 2);
		__uaccess_end();
		return ret;
		case 4:
		__uaccess_begin();
		__get_user_asm((u32 )dst, (u32 __user *)src,
		__get_user_asm_nozero((u32 )dst, (u32 __user *)src,
		ret, "l", "k", "=r", 4);
		__uaccess_end();
		return ret;
		case 8:
		__uaccess_begin();
		__get_user_asm((u64 )dst, (u64 __user *)src,
		__get_user_asm_nozero((u64 )dst, (u64 __user *)src,
		ret, "q", "", "=r", 8);
		__uaccess_end();
		return ret;
		case 10:
		__uaccess_begin();
		__get_user_asm((u64 )dst, (u64 __user *)src,
		__get_user_asm_nozero((u64 )dst, (u64 __user *)src,
		ret, "q", "", "=r", 10);
		if (likely(!ret))
		__get_user_asm((u16 )(8 + (char *)dst),
		__get_user_asm_nozero((u16 )(8 + (char *)dst),
		(u16 __user )(8 + (char __user )src),
		ret, "w", "w", "=r", 2);
		__uaccess_end();
		return ret;
		case 16:
		__uaccess_begin();
		__get_user_asm((u64 )dst, (u64 __user *)src,
		__get_user_asm_nozero((u64 )dst, (u64 __user *)src,
		ret, "q", "", "=r", 16);
		if (likely(!ret))
		__get_user_asm((u64 )(8 + (char *)dst),
		__get_user_asm_nozero((u64 )(8 + (char *)dst),
		(u64 __user )(8 + (char __user )src),
		ret, "q", "", "=r", 8);
		__uaccess_end();

arch/x86/lib/usercopy.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -76,10 +76,11 @@ EXPORT_SYMBOL(_copy_to_user);
		*/
		unsigned long _copy_from_user(void to, const void __user from, unsigned n)
		{
		unsigned long res = n;
		if (access_ok(VERIFY_READ, from, n))
		n = __copy_from_user(to, from, n);
		else
		memset(to, 0, n);
		return n;
		res = __copy_from_user_inatomic(to, from, n);
		if (unlikely(res))
		memset(to + n - res, 0, res);
		return res;
		}
		EXPORT_SYMBOL(_copy_from_user);

arch/x86/lib/usercopy_64.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -80,9 +80,5 @@ copy_user_handle_tail(char to, char from, unsigned len)
		break;
		}
		clac();

		/* If the destination is a kernel buffer, we always clear the end */
		if (!__addr_ok(to))
		memset(to, 0, len);
		return len;
		}

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