Add virtual address validation and system PTE helpers

xtoskrnl/mm/i686/pte.cc

@@ -8,3 +8,68 @@
 
 #include <xtos.hh>
 
+
+/**
+ * Checks if the virtual address is valid and mapped in the page tables.
+ *
+ * @param VirtualAddress
+ *        The virtual address to check.
+ *
+ * @return This routine returns TRUE if the address is valid, or FALSE otherwise.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+BOOLEAN
+MM::Pte::AddressValid(IN PVOID VirtualAddress)
+{
+    /* Check XPA status */
+    if(MM::Paging::GetXpaStatus())
+    {
+        /* Check if the P5E is valid */
+        if(!MM::Paging::PteValid(MM::Paging::GetPpeAddress(VirtualAddress)))
+        {
+            /* Invalid PPE, return FALSE */
+            return FALSE;
+        }
+    }
+
+    /* Check if PDE and PTE are valid */
+    if(!MM::Paging::PteValid(MM::Paging::GetPdeAddress(VirtualAddress)) ||
+       !MM::Paging::PteValid(MM::Paging::GetPteAddress(VirtualAddress)))
+    {
+        /* Invalid PDE or PTE, return FALSE */
+        return FALSE;
+    }
+
+    /* Address is valid, return TRUE */
+    return TRUE;
+}
+
+/**
+ * Retrieves the base virtual address of the system PTEs.
+ *
+ * @return This routine returns a pointer to the first PTE in the system PTE space.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+PMMPTE
+MM::Pte::GetSystemPteBaseAddress(VOID)
+{
+    return MM::Paging::GetPteAddress(NULLPTR);
+}
+
+/**
+ * Performs the initial setup of the system's page table hierarchy.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+MM::Pte::InitializePageTable(VOID)
+{
+    UNIMPLEMENTED;
+}