Introduce memcpy_nocache() as a memcpy() that avoids the processor cache
if possible. Without arch-specific support, this defaults to just
memcpy(). For now, include arch-specific support for x86.
Cc: Ross Zwisler <ross.zwis...@linux.intel.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: <x...@kernel.org>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Brian Boylston <brian.boyls...@hpe.com>
Reviewed-by: Toshi Kani <toshi.k...@hpe.com>
Reported-by: Oliver Moreno <oliver.mor...@hpe.com>
---
arch/x86/include/asm/string_32.h | 3 +++
arch/x86/include/asm/string_64.h | 3 +++
arch/x86/lib/misc.c | 12 ++++++++++++
include/linux/string.h | 15 +++++++++++++++
4 files changed, 33 insertions(+)
diff --git a/arch/x86/include/asm/string_32.h b/arch/x86/include/asm/string_32.h
index 3d3e835..64f80c0 100644
--- a/arch/x86/include/asm/string_32.h
+++ b/arch/x86/include/asm/string_32.h
@@ -196,6 +196,9 @@ static inline void *__memcpy3d(void *to, const void *from,
size_t len)
#endif
+#define __HAVE_ARCH_MEMCPY_NOCACHE
+extern void *memcpy_nocache(void *dest, const void *src, size_t count);
+
#define __HAVE_ARCH_MEMMOVE
void *memmove(void *dest, const void *src, size_t n);
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index 90dbbd9..a8fdd55 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -51,6 +51,9 @@ extern void *__memcpy(void *to, const void *from, size_t len);
#define memcpy(dst, src, len) __inline_memcpy((dst), (src), (len))
#endif
+#define __HAVE_ARCH_MEMCPY_NOCACHE
+extern void *memcpy_nocache(void *dest, const void *src, size_t count);
+
#define __HAVE_ARCH_MEMSET
void *memset(void *s, int c, size_t n);
void *__memset(void *s, int c, size_t n);
diff --git a/arch/x86/lib/misc.c b/arch/x86/lib/misc.c
index 76b373a..c993ab3 100644
--- a/arch/x86/lib/misc.c
+++ b/arch/x86/lib/misc.c
@@ -1,3 +1,6 @@
+#include <linux/export.h>
+#include <linux/uaccess.h>
+
/*
* Count the digits of @val including a possible sign.
*
@@ -19,3 +22,12 @@ int num_digits(int val)
}
return d;
}
+
+#ifdef __HAVE_ARCH_MEMCPY_NOCACHE
+void *memcpy_nocache(void *dest, const void *src, size_t count)
+{
+ __copy_from_user_inatomic_nocache(dest, src, count);
+ return dest;
+}
+EXPORT_SYMBOL(memcpy_nocache);
+#endif
diff --git a/include/linux/string.h b/include/linux/string.h
index 26b6f6a..7f40c41 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -102,6 +102,21 @@ extern void * memset(void *,int,__kernel_size_t);
#ifndef __HAVE_ARCH_MEMCPY
extern void * memcpy(void *,const void *,__kernel_size_t);
#endif
+
+#ifndef __HAVE_ARCH_MEMCPY_NOCACHE
+/**
+ * memcpy_nocache - Copy one area of memory to another, avoiding the
+ * processor cache if possible
+ * @dest: Where to copy to
+ * @src: Where to copy from
+ * @count: The size of the area.
+ */
+static inline void *memcpy_nocache(void *dest, const void *src, size_t count)
+{
+ return memcpy(dest, src, count);
+}
+#endif
+
#ifndef __HAVE_ARCH_MEMMOVE
extern void * memmove(void *,const void *,__kernel_size_t);
#endif
--
2.8.3
