MN10300: Handle missing sys_cacheflush() when caching disabled

When caching is disabled on the MN10300 arch, the sys_cacheflush()
function is removed by conditional stuff in the makefiles, but is still
referred to by the syscall table.

Provide a null version that just returns 0 when caching is disabled (or
-EINVAL if the arguments are silly).

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/mn10300/mm/Makefile

@@ -2,13 +2,11 @@
 # Makefile for the MN10300-specific memory management code
 #
 
+cacheflush-y	:= cache.o cache-mn10300.o
+cacheflush-$(CONFIG_MN10300_CACHE_WBACK) += cache-flush-mn10300.o
+
+cacheflush-$(CONFIG_MN10300_CACHE_DISABLED) := cache-disabled.o
+
 obj-y := \
 	init.o fault.o pgtable.o extable.o tlb-mn10300.o mmu-context.o \
-	misalignment.o dma-alloc.o
-
-ifneq ($(CONFIG_MN10300_CACHE_DISABLED),y)
-obj-y	+= cache.o cache-mn10300.o
-ifeq ($(CONFIG_MN10300_CACHE_WBACK),y)
-obj-y	+= cache-flush-mn10300.o
-endif
-endif
+	misalignment.o dma-alloc.o $(cacheflush-y)

arch/mn10300/mm/cache-disabled.c

@@ -0,0 +1,21 @@
+/* Handle the cache being disabled
+ *
+ * Copyright (C) 2010 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#include <linux/mm.h>
+
+/*
+ * allow userspace to flush the instruction cache
+ */
+asmlinkage long sys_cacheflush(unsigned long start, unsigned long end)
+{
+	if (end < start)
+		return -EINVAL;
+	return 0;
+}