Kernel: Add VMManager to manage process address spaces

This enables more dynamic management of the process address space,
compared to just directly configuring the page table for major areas.

This will serve as the foundation upon which the rest of the Kernel
memory management functions will be built.

src/core/memory_setup.h

@@ -6,8 +6,13 @@
 
 #include "common/common_types.h"
 
+#include "core/memory.h"
+
 namespace Memory {
 
+const u32 PAGE_MASK = PAGE_SIZE - 1;
+const int PAGE_BITS = 12;
+
 void InitMemoryMap();
 
 /**
@@ -26,4 +31,6 @@ void MapMemoryRegion(VAddr base, u32 size, u8* target);
  */
 void MapIoRegion(VAddr base, u32 size);
 
+void UnmapRegion(VAddr base, u32 size);
+
 }