Add KDL command "mapping"

* VMTranslationMap:
  - Add DebugPrintMappingInfo(): Given a virtual address it is supposed
    to print the paging structure information for that address. To be
    implemented by derived classes.
  - Add DebugGetReverseMappingInfo(): Given a physical addresss it is
    supposed to find all virtual addresses mapped to it. To be
    implemented by derived classes.
* X86VMTranslationMapPAE: Implement the new methods
  DebugPrintMappingInfo() and DebugGetReverseMappingInfo().
* Add KDL command "mapping". It supports both virtual address lookups
  and reverse lookups.

headers/private/kernel/vm/VMTranslationMap.h

@@ -20,6 +20,9 @@ struct vm_page_reservation;
 
 
 struct VMTranslationMap {
+			struct ReverseMappingInfoCallback;
+
+public:
 								VMTranslationMap();
 	virtual						~VMTranslationMap();
 
@@ -72,6 +75,12 @@ struct VMTranslationMap {
 
 	virtual	void				Flush() = 0;
 
+	// backends for KDL commands
+	virtual	void				DebugPrintMappingInfo(addr_t virtualAddress);
+	virtual	bool				DebugGetReverseMappingInfo(
+									phys_addr_t physicalAddress,
+									ReverseMappingInfoCallback& callback);
+
 protected:
 			void				PageUnmapped(VMArea* area,
 									page_num_t pageNumber, bool accessed,
@@ -85,6 +94,13 @@ protected:
 };
 
 
+struct VMTranslationMap::ReverseMappingInfoCallback {
+	virtual						~ReverseMappingInfoCallback();
+
+	virtual	bool				HandleVirtualAddress(addr_t virtualAddress) = 0;
+};
+
+
 struct VMPhysicalPageMapper {
 								VMPhysicalPageMapper();
 	virtual						~VMPhysicalPageMapper();