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amd64: get rid of zeroing 

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-03-25 18:36:22 -04:00
parent d597580d37
commit 122b05ddf5
4 changed files with 25 additions and 16 deletions
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12
arch/x86/include/asm/uaccess.h
View File

@ -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.

16
arch/x86/include/asm/uaccess_64.h
View File

@ -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();

9
arch/x86/lib/usercopy.c
View File

@ -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);

4
arch/x86/lib/usercopy_64.c
View File

@ -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;
}