[PATCH] m68k IP checksum fix

M68k: revive csum_partial_copy_nocheck() after csum_partial_copy() was removed
in 2.5.44 (from Roman Zippel)

arch/m68k/lib/checksum.c

@@ -318,3 +318,103 @@ csum_partial_copy_from_user(const char *src, char *dst, int len,
 
 	return(sum);
 }
+
+/*
+ * copy from kernel space while checksumming, otherwise like csum_partial
+ */
+
+unsigned int
+csum_partial_copy_nocheck(const char *src, char *dst, int len, int sum)
+{
+	unsigned long tmp1, tmp2;
+	__asm__("movel %2,%4\n\t"
+		"btst #1,%4\n\t"	/* Check alignment */
+		"jeq 2f\n\t"
+		"subql #2,%1\n\t"	/* buff%4==2: treat first word */
+		"jgt 1f\n\t"
+		"addql #2,%1\n\t"	/* len was == 2, treat only rest */
+		"jra 4f\n"
+	     "1:\t"
+		"movew %2@+,%4\n\t"	/* add first word to sum */
+		"addw %4,%0\n\t"
+		"movew %4,%3@+\n\t"
+		"clrl %4\n\t"
+		"addxl %4,%0\n"		/* add X bit */
+	     "2:\t"
+		/* unrolled loop for the main part: do 8 longs at once */
+		"movel %1,%4\n\t"	/* save len in tmp1 */
+		"lsrl #5,%1\n\t"	/* len/32 */
+		"jeq 2f\n\t"		/* not enough... */
+		"subql #1,%1\n"
+	     "1:\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"dbra %1,1b\n\t"
+		"clrl %5\n\t"
+		"addxl %5,%0\n\t"	/* add X bit */
+		"clrw %1\n\t"
+		"subql #1,%1\n\t"
+		"jcc 1b\n"
+	     "2:\t"
+		"movel %4,%1\n\t"	/* restore len from tmp1 */
+		"andw #0x1c,%4\n\t"	/* number of rest longs */
+		"jeq 4f\n\t"
+		"lsrw #2,%4\n\t"
+		"subqw #1,%4\n"
+	     "3:\t"
+		/* loop for rest longs */
+		"movel %2@+,%5\n\t"
+		"addxl %5,%0\n\t"
+		"movel %5,%3@+\n\t"
+		"dbra %4,3b\n\t"
+		"clrl %5\n\t"
+		"addxl %5,%0\n"		/* add X bit */
+	     "4:\t"
+		/* now check for rest bytes that do not fit into longs */
+		"andw #3,%1\n\t"
+		"jeq 7f\n\t"
+		"clrl %5\n\t"		/* clear tmp2 for rest bytes */
+		"subqw #2,%1\n\t"
+		"jlt 5f\n\t"
+		"movew %2@+,%5\n\t"	/* have rest >= 2: get word */
+		"movew %5,%3@+\n\t"
+		"swap %5\n\t"		/* into bits 16..31 */
+		"tstw %1\n\t"		/* another byte? */
+		"jeq 6f\n"
+	     "5:\t"
+		"moveb %2@,%5\n\t"	/* have odd rest: get byte */
+		"moveb %5,%3@+\n\t"
+		"lslw #8,%5\n"		/* into bits 8..15; 16..31 untouched */
+	     "6:\t"
+		"addl %5,%0\n\t"	/* now add rest long to sum */
+		"clrl %5\n\t"
+		"addxl %5,%0\n"		/* add X bit */
+	     "7:\t"
+		: "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
+		  "=&d" (tmp1), "=&d" (tmp2)
+		: "0" (sum), "1" (len), "2" (src), "3" (dst)
+	    );
+    return(sum);
+}

include/asm-m68k/checksum.h

@@ -26,8 +26,8 @@ unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
 extern unsigned int csum_partial_copy_from_user(const char *src, char *dst,
 						int len, int sum, int *csum_err);
 
-#define csum_partial_copy_nocheck(src, dst, len, sum)	\
-	csum_partial_copy((src), (dst), (len), (sum))
+extern unsigned int csum_partial_copy_nocheck(const char *src, char *dst,
+					      int len, int sum);
 
 /*
  *	This is a version of ip_compute_csum() optimized for IP headers,