Properly, recursively self map page tables; currently only for AMD64 and PML4

sdk/xtdk/bltypes.h

@@ -46,7 +46,7 @@ typedef LONG (*PBL_GET_MEMTYPE_ROUTINE)(IN LONG EfiMemoryType);
 typedef EFI_STATUS (*PBL_ALLOCATE_PAGES)(IN ULONGLONG Size, OUT PEFI_PHYSICAL_ADDRESS Memory);
 typedef EFI_STATUS (*PBL_ALLOCATE_POOL)(IN UINT_PTR Size, OUT PVOID *Memory);
 typedef VOID (*PBL_BOOTMENU_INITIALIZE_OS_LIST)(OUT PXTBL_BOOTMENU_ITEM MenuEntries, OUT PULONG EntriesCount, OUT PULONG DefaultId);
-typedef EFI_STATUS (*PBL_BUILD_PAGE_MAP)(IN PXTBL_PAGE_MAPPING PageMap);
+typedef EFI_STATUS (*PBL_BUILD_PAGE_MAP)(IN PXTBL_PAGE_MAPPING PageMap, IN ULONG_PTR SelfMapAddress);
 typedef EFI_STATUS (*PBL_CLOSE_VOLUME)(IN PEFI_HANDLE VolumeHandle);
 typedef VOID (*PBL_CLEAR_CONSOLE_LINE)(IN ULONGLONG LineNo);
 typedef EFI_STATUS (*PBL_CLOSE_XT_PROTOCOL)(IN PEFI_HANDLE Handle, IN PEFI_GUID ProtocolGuid);

xtldr/arch/amd64/memory.c

@@ -15,13 +15,17 @@
  * @param PageMap
  *        Supplies a pointer to the page mapping structure.
  *
+ * @param SelfMapAddress
+ *        Supplies a virtual address of the page tables.
+ *
  * @return This routine returns a status code.
  *
  * @since XT 1.0
  */
 XTCDECL
 EFI_STATUS
-BlBuildPageMap(IN PXTBL_PAGE_MAPPING PageMap)
+BlBuildPageMap(IN PXTBL_PAGE_MAPPING PageMap,
+               IN ULONG_PTR SelfMapAddress)
 {
     PLIST_ENTRY ListEntry, ModulesList, ModulesListEntry;
     PXTBL_MEMORY_MAPPING Mapping;
@@ -42,7 +46,7 @@ BlBuildPageMap(IN PXTBL_PAGE_MAPPING PageMap)
     RtlZeroMemory(PageMap->PtePointer, EFI_PAGE_SIZE);
 
     /* Add page mapping itself to memory mapping */
-    Status = BlMapVirtualMemory(PageMap, NULL, PageMap->PtePointer, 1, LoaderMemoryData);
+    Status = BlpSelfMapPml(PageMap, SelfMapAddress);
     if(Status != STATUS_EFI_SUCCESS)
     {
         /* PML mapping failed */
@@ -227,3 +231,45 @@ BlMapPage(IN PXTBL_PAGE_MAPPING PageMap,
     /* Return success */
     return STATUS_EFI_SUCCESS;
 }
+
+/**
+ * Creates a recursive self mapping for all PML levels.
+ *
+ * @param PageMap
+ *        Supplies a pointer to the page mapping structure.
+ *
+ * @param SelfMapAddress
+ *        Supplies a virtual address of the page tables.
+ *
+ * @return This routine returns a status code.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+EFI_STATUS
+BlpSelfMapPml(IN PXTBL_PAGE_MAPPING PageMap,
+              IN ULONG_PTR SelfMapAddress)
+{
+    ULONGLONG PmlIndex;
+
+    /* Check page map level */
+    if(PageMap->PageMapLevel == 5)
+    {
+        /* Self-mapping for PML5 is not supported */
+        BlDebugPrint(L"PML5 self-mapping not supported yet!\n");
+        return STATUS_EFI_UNSUPPORTED;
+    }
+    else
+    {
+        /* Calculate PML index based on provided self map address */
+        PmlIndex = (SelfMapAddress >> 39) & 0x1FF;
+
+        /* Add self-mapping for PML4 */
+        ((PHARDWARE_PTE)PageMap->PtePointer)[PmlIndex].PageFrameNumber = (UINT_PTR)PageMap->PtePointer / EFI_PAGE_SIZE;
+        ((PHARDWARE_PTE)PageMap->PtePointer)[PmlIndex].Valid = 1;
+        ((PHARDWARE_PTE)PageMap->PtePointer)[PmlIndex].Writable = 1;
+    }
+
+    /* Return success */
+    return STATUS_EFI_SUCCESS;
+}

xtldr/arch/i686/memory.c

@@ -21,7 +21,8 @@
  */
 XTCDECL
 EFI_STATUS
-BlBuildPageMap(IN PXTBL_PAGE_MAPPING PageMap)
+BlBuildPageMap(IN PXTBL_PAGE_MAPPING PageMap,
+               IN ULONG_PTR SelfMapAddress)
 {
     PLIST_ENTRY ListEntry, ModulesList, ModulesListEntry;
     EFI_PHYSICAL_ADDRESS Address, DirectoryAddress;

xtldr/includes/xtldr.h

@@ -28,7 +28,8 @@ BlAllocateMemoryPool(IN UINT_PTR Size,
 
 XTCDECL
 EFI_STATUS
-BlBuildPageMap(IN PXTBL_PAGE_MAPPING PageMap);
+BlBuildPageMap(IN PXTBL_PAGE_MAPPING PageMap,
+               IN ULONG_PTR SelfMapAddress);
 
 XTCDECL
 VOID
@@ -524,6 +525,11 @@ BlpReadConfigFile(IN CONST PWCHAR ConfigDirectory,
                   IN CONST PWCHAR ConfigFile,
                   OUT PCHAR *ConfigData);
 
+XTCDECL
+EFI_STATUS
+BlpSelfMapPml(IN PXTBL_PAGE_MAPPING PageMap,
+              IN ULONG_PTR SelfMapAddress);
+
 XTCDECL
 ULONGLONG
 BlpStringReadPadding(IN PUSHORT *Format);

xtldr/modules/xtos_o/amd64/memory.c

@@ -35,7 +35,7 @@ XtEnablePaging(IN PXTBL_PAGE_MAPPING PageMap)
     EFI_STATUS Status;
 
     /* Build page map */
-    Status = XtLdrProtocol->Memory.BuildPageMap(PageMap);
+    Status = XtLdrProtocol->Memory.BuildPageMap(PageMap, 0xFFFFF6FB7DBED000);
     if(Status != STATUS_EFI_SUCCESS)
     {
         /* Failed to build page map */

xtldr/modules/xtos_o/i686/memory.c

@@ -55,7 +55,7 @@ XtEnablePaging(IN PXTBL_PAGE_MAPPING PageMap)
     }
 
     /* Build page map */
-    Status = XtLdrProtocol->Memory.BuildPageMap(PageMap);
+    Status = XtLdrProtocol->Memory.BuildPageMap(PageMap, 0);
     if(Status != STATUS_EFI_SUCCESS)
     {
         /* Failed to build page map */