nommu: Provide vmalloc_exec().

Now that SH has switched to vmalloc_exec() for PAGE_KERNEL_EXEC usage,
it's apparent that nommu has no vmalloc_exec() definition of its own.
Stub in the one from mm/vmalloc.c.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

mm/nommu.c

@@ -266,6 +266,27 @@ void *vmalloc_node(unsigned long size, int node)
 }
 EXPORT_SYMBOL(vmalloc_node);
 
+#ifndef PAGE_KERNEL_EXEC
+# define PAGE_KERNEL_EXEC PAGE_KERNEL
+#endif
+
+/**
+ *	vmalloc_exec  -  allocate virtually contiguous, executable memory
+ *	@size:		allocation size
+ *
+ *	Kernel-internal function to allocate enough pages to cover @size
+ *	the page level allocator and map them into contiguous and
+ *	executable kernel virtual space.
+ *
+ *	For tight control over page level allocator and protection flags
+ *	use __vmalloc() instead.
+ */
+
+void *vmalloc_exec(unsigned long size)
+{
+	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
+}
+
 /**
  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
  *	@size:		allocation size