Kernel: Implement new abstract MemoryRegion

MemoryBackedRegion now inherits from this and is used for private
anonymous mappigs. This will make shared mappings and file backed
mappings much easier to implement.

kernel/include/kernel/Memory/MemoryRegion.h

@@ -0,0 +1,59 @@
+#pragma once
+
+#include <BAN/UniqPtr.h>
+#include <kernel/Memory/PageTable.h>
+#include <kernel/Memory/Types.h>
+
+#include <stddef.h>
+
+namespace Kernel
+{
+
+	struct AddressRange
+	{
+		vaddr_t start;
+		vaddr_t end;
+	};
+
+	class MemoryRegion
+	{
+		BAN_NON_COPYABLE(MemoryRegion);
+		BAN_NON_MOVABLE(MemoryRegion);
+
+	public:
+		enum Type : uint8_t
+		{
+			PRIVATE,
+			SHARED
+		};
+
+	public:
+		virtual ~MemoryRegion();
+
+		bool contains(vaddr_t address) const;
+		bool contains_fully(vaddr_t address, size_t size) const;
+		bool overlaps(vaddr_t address, size_t size) const;
+
+		size_t size() const { return m_size; }
+		vaddr_t vaddr() const { return m_vaddr; }
+
+		// Returns error if no memory was available
+		// Returns true if page was succesfully allocated
+		// Returns false if page was already allocated
+		virtual BAN::ErrorOr<bool> allocate_page_containing(vaddr_t address) = 0;
+
+		virtual BAN::ErrorOr<BAN::UniqPtr<MemoryRegion>> clone(PageTable& new_page_table) = 0;
+	
+	protected:
+		MemoryRegion(PageTable&, size_t size, Type type, PageTable::flags_t flags);
+		BAN::ErrorOr<void> initialize(AddressRange);
+
+	protected:
+		PageTable& m_page_table;
+		const size_t m_size;
+		const Type m_type;
+		const PageTable::flags_t m_flags;
+		vaddr_t m_vaddr { 0 };
+	};
+
+}