From ff47ab4ff3cddfa7bc1b25b990e24abe2ae474ff Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@linux.intel.com>
Date: Fri, 16 Aug 2013 14:17:19 -0700
Subject: [PATCH] x86: Add 1/2/4/8 byte optimization to 64bit
__copy_{from,to}_user_inatomic
The 64bit __copy_{from,to}_user_inatomic always called
copy_from_user_generic, but skipped the special optimizations for 1/2/4/8
byte accesses.
This especially hurts the futex call, which accesses the 4 byte futex
user value with a complicated fast string operation in a function call,
instead of a single movl.
Use __copy_{from,to}_user for _inatomic instead to get the same
optimizations. The only problem was the might_fault() in those functions.
So move that to new wrapper and call __copy_{f,t}_user_nocheck()
from *_inatomic directly.
32bit already did this correctly by duplicating the code.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1376687844-19857-2-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
arch/x86/include/asm/uaccess_64.h | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 4f7923dd00079..64476bb2a1465 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -77,11 +77,10 @@ int copy_to_user(void __user *dst, const void *src, unsigned size)
}
static __always_inline __must_check
-int __copy_from_user(void *dst, const void __user *src, unsigned size)
+int __copy_from_user_nocheck(void *dst, const void __user *src, unsigned size)
{
int ret = 0;
- might_fault();
if (!__builtin_constant_p(size))
return copy_user_generic(dst, (__force void *)src, size);
switch (size) {
@@ -121,11 +120,17 @@ int __copy_from_user(void *dst, const void __user *src, unsigned size)
}
static __always_inline __must_check
-int __copy_to_user(void __user *dst, const void *src, unsigned size)
+int __copy_from_user(void *dst, const void __user *src, unsigned size)
+{
+ might_fault();
+ return __copy_from_user_nocheck(dst, src, size);
+}
+
+static __always_inline __must_check
+int __copy_to_user_nocheck(void __user *dst, const void *src, unsigned size)
{
int ret = 0;
- might_fault();
if (!__builtin_constant_p(size))
return copy_user_generic((__force void *)dst, src, size);
switch (size) {
@@ -164,6 +169,13 @@ int __copy_to_user(void __user *dst, const void *src, unsigned size)
}
}
+static __always_inline __must_check
+int __copy_to_user(void __user *dst, const void *src, unsigned size)
+{
+ might_fault();
+ return __copy_to_user_nocheck(dst, src, size);
+}
+
static __always_inline __must_check
int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
{
@@ -220,13 +232,13 @@ int __copy_in_user(void __user *dst, const void __user *src, unsigned size)
static __must_check __always_inline int
__copy_from_user_inatomic(void *dst, const void __user *src, unsigned size)
{
- return copy_user_generic(dst, (__force const void *)src, size);
+ return __copy_from_user_nocheck(dst, (__force const void *)src, size);
}
static __must_check __always_inline int
__copy_to_user_inatomic(void __user *dst, const void *src, unsigned size)
{
- return copy_user_generic((__force void *)dst, src, size);
+ return __copy_to_user_nocheck((__force void *)dst, src, size);
}
extern long __copy_user_nocache(void *dst, const void __user *src,
--
2.30.2