Introduce page fault handling infrastructure

xtoskrnl/mm/i686/pfault.cc

@@ -0,0 +1,36 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/mm/i686/pfault.cc
+ * DESCRIPTION:     Page fault support for i686 architecture
+ * DEVELOPERS:      Aiken Harris <harraiken91@gmail.com>
+ */
+
+#include <xtos.hh>
+
+
+/**
+ * Evaluates the PDE for for paged pool and per-session mappings.
+ *
+ * @param VirtualAddress
+ *        Specifies the virtual address to verify.
+ *
+ * @return This routine returns ACCESS_VIOLATION on PML3 or status code on PML2.
+ */
+XTFASTCALL
+XTSTATUS
+MM::PageFault::CheckPdeForPagedPool(IN PVOID VirtualAddress)
+{
+    /* Check if XPA is enabled */
+    if(MM::Paging::GetXpaStatus())
+    {
+        /* Access violation for PML3 */
+        return STATUS_ACCESS_VIOLATION;
+    }
+
+    /* Unimplemented path for PML2 */
+    UNIMPLEMENTED;
+
+    /* Temporarily, just return access violation */
+    return STATUS_ACCESS_VIOLATION;
+}