Merge branch 'x86-dax-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 dax updates from Ingo Molnar:
 "This contains x86 memcpy_mcsafe() fault handling improvements the
  nvdimm tree would like to make more use of"

* 'x86-dax-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()
  x86/asm/memcpy_mcsafe: Add write-protection-fault handling
  x86/asm/memcpy_mcsafe: Return bytes remaining
  x86/asm/memcpy_mcsafe: Add labels for __memcpy_mcsafe() write fault handling
  x86/asm/memcpy_mcsafe: Remove loop unrolling

2 files changed, 20 insertions, 4 deletions

diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 533f74c300c2..d33f92b9fa22 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -116,7 +116,8 @@ int strcmp(const char *cs, const char *ct);
 #endif
 
 #define __HAVE_ARCH_MEMCPY_MCSAFE 1
-__must_check int memcpy_mcsafe_unrolled(void *dst, const void *src, size_t cnt);
+__must_check unsigned long __memcpy_mcsafe(void *dst, const void *src,
+		size_t cnt);
 DECLARE_STATIC_KEY_FALSE(mcsafe_key);
 
 /**
@@ -131,14 +132,15 @@ DECLARE_STATIC_KEY_FALSE(mcsafe_key);
  * actually do machine check recovery. Everyone else can just
  * use memcpy().
  *
- * Return 0 for success, -EFAULT for fail
+ * Return 0 for success, or number of bytes not copied if there was an
+ * exception.
  */
-static __always_inline __must_check int
+static __always_inline __must_check unsigned long
 memcpy_mcsafe(void *dst, const void *src, size_t cnt)
 {
 #ifdef CONFIG_X86_MCE
 	if (static_branch_unlikely(&mcsafe_key))
-		return memcpy_mcsafe_unrolled(dst, src, cnt);
+		return __memcpy_mcsafe(dst, src, cnt);
 	else
 #endif
 		memcpy(dst, src, cnt);
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 62546b3a398e..62acb613114b 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -47,6 +47,17 @@ copy_user_generic(void *to, const void *from, unsigned len)
 }
 
 static __always_inline __must_check unsigned long
+copy_to_user_mcsafe(void *to, const void *from, unsigned len)
+{
+	unsigned long ret;
+
+	__uaccess_begin();
+	ret = memcpy_mcsafe(to, from, len);
+	__uaccess_end();
+	return ret;
+}
+
+static __always_inline __must_check unsigned long
 raw_copy_from_user(void *dst, const void __user *src, unsigned long size)
 {
 	int ret = 0;
@@ -194,4 +205,7 @@ __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
 unsigned long
 copy_user_handle_tail(char *to, char *from, unsigned len);
 
+unsigned long
+mcsafe_handle_tail(char *to, char *from, unsigned len);
+
 #endif /* _ASM_X86_UACCESS_64_H */