[MIPS] csum_partial and copy in parallel

Implement optimized asm version of csum_partial_copy_nocheck,
csum_partial_copy_from_user and csum_and_copy_to_user which can do
calculate and copy in parallel, based on memcpy.S.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/mips_ksyms.c

@@ -46,5 +46,7 @@ EXPORT_SYMBOL(__strnlen_user_nocheck_asm);
 EXPORT_SYMBOL(__strnlen_user_asm);
 
 EXPORT_SYMBOL(csum_partial);
+EXPORT_SYMBOL(csum_partial_copy_nocheck);
+EXPORT_SYMBOL(__csum_partial_copy_user);
 
 EXPORT_SYMBOL(invalid_pte_table);

arch/mips/lib/Makefile

@@ -2,7 +2,7 @@
 # Makefile for MIPS-specific library files..
 #
 
-lib-y	+= csum_partial.o csum_partial_copy.o memcpy.o promlib.o \
+lib-y	+= csum_partial.o memcpy.o promlib.o \
 	   strlen_user.o strncpy_user.o strnlen_user.o uncached.o
 
 obj-y	+= iomap.o

arch/mips/lib/csum_partial_copy.c

-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 1994, 1995 Waldorf Electronics GmbH
- * Copyright (C) 1998, 1999 Ralf Baechle
- */
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/types.h>
-#include <asm/byteorder.h>
-#include <asm/string.h>
-#include <asm/uaccess.h>
-#include <net/checksum.h>
-
-/*
- * copy while checksumming, otherwise like csum_partial
- */
-__wsum csum_partial_copy_nocheck(const void *src,
-	void *dst, int len, __wsum sum)
-{
-	/*
-	 * It's 2:30 am and I don't feel like doing it real ...
-	 * This is lots slower than the real thing (tm)
-	 */
-	sum = csum_partial(src, len, sum);
-	memcpy(dst, src, len);
-
-	return sum;
-}
-
-EXPORT_SYMBOL(csum_partial_copy_nocheck);
-
-/*
- * Copy from userspace and compute checksum.  If we catch an exception
- * then zero the rest of the buffer.
- */
-__wsum csum_partial_copy_from_user (const void __user *src,
-	void *dst, int len, __wsum sum, int *err_ptr)
-{
-	int missing;
-
-	might_sleep();
-	missing = copy_from_user(dst, src, len);
-	if (missing) {
-		memset(dst + len - missing, 0, missing);
-		*err_ptr = -EFAULT;
-	}
-
-	return csum_partial(dst, len, sum);
-}

include/asm-mips/checksum.h

@@ -29,31 +29,38 @@
  */
 __wsum csum_partial(const void *buff, int len, __wsum sum);
 
+__wsum __csum_partial_copy_user(const void *src, void *dst,
+				int len, __wsum sum, int *err_ptr);
+
 /*
  * this is a new version of the above that records errors it finds in *errp,
  * but continues and zeros the rest of the buffer.
  */
-__wsum csum_partial_copy_from_user(const void __user *src,
-					 void *dst, int len,
-					 __wsum sum, int *errp);
+static inline
+__wsum csum_partial_copy_from_user(const void __user *src, void *dst, int len,
+				   __wsum sum, int *err_ptr)
+{
+	might_sleep();
+	return __csum_partial_copy_user((__force void *)src, dst,
+					len, sum, err_ptr);
+}
 
 /*
  * Copy and checksum to user
  */
 #define HAVE_CSUM_COPY_USER
-static inline __wsum csum_and_copy_to_user (const void *src, void __user *dst,
-						  int len, __wsum sum,
-						  int *err_ptr)
+static inline
+__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
+			     __wsum sum, int *err_ptr)
 {
 	might_sleep();
-	sum = csum_partial(src, len, sum);
-
-	if (copy_to_user(dst, src, len)) {
+	if (access_ok(VERIFY_WRITE, dst, len))
+		return __csum_partial_copy_user(src, (__force void *)dst,
+						len, sum, err_ptr);
+	if (len)
 		*err_ptr = -EFAULT;
-		return (__force __wsum)-1;
-	}
 
-	return sum;
+	return (__force __wsum)-1; /* invalid checksum */
 }
 
 /*