[RFC,x86 v2 1/8] arch, x86, uaccess: Add nontemporal copy functions

[Joe Damato <jdamato@fastly.com>]

Add a generic non-temporal wrapper to uaccess which can be overridden by
arches that support non-temporal copies.

An implementation is added for x86 which wraps an existing non-temporal
copy in the kernel.

Signed-off-by: Joe Damato <jdamato@fastly.com>
---
 arch/x86/include/asm/uaccess_64.h | 6 ++++++
 include/linux/uaccess.h           | 6 ++++++
 2 files changed, 12 insertions(+)

diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 45697e0..ed41dba 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -65,6 +65,12 @@ extern long __copy_user_flushcache(void *dst, const void __user *src, unsigned s
 extern void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
 			   size_t len);
 
+static inline unsigned long
+__copy_from_user_nocache(void *dst, const void __user *src, unsigned long size)
+{
+	return (unsigned long)__copy_user_nocache(dst, src, (unsigned int) size, 0);
+}
+
 static inline int
 __copy_from_user_inatomic_nocache(void *dst, const void __user *src,
 				  unsigned size)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 5a328cf..6612c37 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -256,6 +256,12 @@ static inline size_t probe_subpage_writeable(char __user *uaddr, size_t size)
 #ifndef ARCH_HAS_NOCACHE_UACCESS
 
 static inline __must_check unsigned long
+__copy_from_user_nocache(void *to, const void __user *from, unsigned long n)
+{
+	return __copy_from_user(to, from, n);
+}
+
+static inline __must_check unsigned long
 __copy_from_user_inatomic_nocache(void *to, const void __user *from,
 				  unsigned long n)
 {
-- 
2.7.4