Refactor EFI memory mapping to support distinct mapping strategies

boot/xtldr/includes/xtldr.hh

@@ -177,7 +177,8 @@ class Memory
                                               IN SHORT PageMapLevel,
                                               IN PAGE_SIZE PageSize);
         STATIC XTCDECL EFI_STATUS MapEfiMemory(IN OUT PXTBL_PAGE_MAPPING PageMap,
-                                               IN OUT PVOID *MemoryMapAddress,
+                                               IN OUT PVOID *BaseAddress,
+                                               IN BOOLEAN IdentityMapping,
                                                IN PBL_GET_MEMTYPE_ROUTINE GetMemoryTypeRoutine);
         STATIC XTCDECL EFI_STATUS MapPage(IN PXTBL_PAGE_MAPPING PageMap,
                                           IN ULONGLONG VirtualAddress,

boot/xtldr/memory.cc

@@ -314,9 +314,12 @@ Memory::InitializePageMap(OUT PXTBL_PAGE_MAPPING PageMap,
  * @param PageMap
  *        Supplies a pointer to the page mapping structure.
  *
- * @param MemoryMapAddress
+ * @param BaseAddress
  *        Supplies a virtual address, where EFI memory will be mapped.
  *
+ * @param IdentityMapping
+ *        Specifies whether EFI non-free memory should be mapped by identity or sequential mapping.
+ *
  * @param GetMemoryTypeRoutine
  *        Supplies a pointer to the routine which will be used to match EFI memory type to the OS memory type.
  *
@@ -327,7 +330,8 @@ Memory::InitializePageMap(OUT PXTBL_PAGE_MAPPING PageMap,
 XTCDECL
 EFI_STATUS
 Memory::MapEfiMemory(IN OUT PXTBL_PAGE_MAPPING PageMap,
-                     IN OUT PVOID *MemoryMapAddress,
+                     IN OUT PVOID *BaseAddress,
+                     IN BOOLEAN IdentityMapping,
                      IN PBL_GET_MEMTYPE_ROUTINE GetMemoryTypeRoutine)
 {
     ULONGLONG MaxAddress, VirtualAddress;
@@ -339,7 +343,7 @@ Memory::MapEfiMemory(IN OUT PXTBL_PAGE_MAPPING PageMap,
     SIZE_T Index;
 
     /* Set virtual address as specified in argument */
-    VirtualAddress = (ULONGLONG)*MemoryMapAddress;
+    VirtualAddress = (ULONGLONG)*BaseAddress;
 
     /* Check if custom memory type routine is specified */
     if(GetMemoryTypeRoutine == NULLPTR)
@@ -419,12 +423,22 @@ Memory::MapEfiMemory(IN OUT PXTBL_PAGE_MAPPING PageMap,
             }
             else if(MemoryType != LoaderFree)
             {
-                /* Add any non-free memory mapping */
-                Status = MapVirtualMemory(PageMap, VirtualAddress, Descriptor->PhysicalStart,
-                                          Descriptor->NumberOfPages, MemoryType);
+                /* Check mapping strategy */
+                if(IdentityMapping)
+                {
+                    /* Add any non-free memory using identity mapping */
+                    Status = MapVirtualMemory(PageMap, Descriptor->PhysicalStart + KSEG0_BASE, Descriptor->PhysicalStart,
+                                              Descriptor->NumberOfPages, MemoryType);
+                }
+                else
+                {
+                    /* Add any non-free memory using sequential mapping */
+                    Status = MapVirtualMemory(PageMap, VirtualAddress, Descriptor->PhysicalStart,
+                                              Descriptor->NumberOfPages, MemoryType);
 
-                /* Update virtual address */
-                VirtualAddress = VirtualAddress + (Descriptor->NumberOfPages * MM_PAGE_SIZE);
+                    /* Update virtual address */
+                    VirtualAddress = VirtualAddress + (Descriptor->NumberOfPages * MM_PAGE_SIZE);
+                }
             }
             else
             {
@@ -462,7 +476,7 @@ Memory::MapEfiMemory(IN OUT PXTBL_PAGE_MAPPING PageMap,
     }
 
     /* Store next valid virtual address and return success */
-    *MemoryMapAddress = (PVOID)VirtualAddress;
+    *BaseAddress = (PVOID)VirtualAddress;
     return STATUS_EFI_SUCCESS;
 }
 

boot/xtldr/modules/xtos_o/amd64/memory.cc

@@ -10,6 +10,21 @@
 #include <xtos.hh>
 
 
+/**
+ * Determines the appropriate EFI memory mapping strategy for the AMD64 architecture.
+ *
+ * @return This routine returns TRUE, what results in an identity mapping.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+BOOLEAN
+Xtos::DetermineMappingStrategy()
+{
+    /* Use an identity mapping strategy */
+    return TRUE;
+}
+
 /**
  * Determines the appropriate paging level (PML) for the AMD64 architecture.
  *

boot/xtldr/modules/xtos_o/i686/memory.cc

@@ -9,6 +9,21 @@
 #include <xtos.hh>
 
 
+/**
+ * Determines the appropriate EFI memory mapping strategy for the i686 architecture.
+ *
+ * @return This routine returns FALSE, what results in a sequential mapping.
+ *
+ * @since XT 1.0
+ */
+XTCDECL
+BOOLEAN
+Xtos::DetermineMappingStrategy()
+{
+    /* Use a sequential mapping strategy */
+    return FALSE;
+}
+
 /**
  * Determines the appropriate paging level (PML) for the i686 architecture.
  *

boot/xtldr/modules/xtos_o/includes/xtos.hh

@@ -39,6 +39,7 @@ class Xtos
                                                           IN UINT NumberOfPages,
                                                           IN LOADER_MEMORY_TYPE MemoryType);
         STATIC XTCDECL LOADER_MEMORY_TYPE ConvertEfiMemoryType(IN EFI_MEMORY_TYPE EfiMemoryType);
+        STATIC XTCDECL BOOLEAN DetermineMappingStrategy();
         STATIC XTCDECL ULONG DeterminePagingLevel(IN CONST PWCHAR Parameters);
         STATIC XTCDECL EFI_STATUS EnablePaging(IN PXTBL_PAGE_MAPPING PageMap);
         STATIC XTCDECL VOID GetDisplayInformation(OUT PSYSTEM_RESOURCE_FRAMEBUFFER FrameBufferResource,

boot/xtldr/modules/xtos_o/xtos.cc

@@ -618,6 +618,7 @@ Xtos::RunBootSequence(IN PEFI_FILE_HANDLE BootDir,
     EFI_HANDLE ProtocolHandle;
     EFI_STATUS Status;
     XTBL_PAGE_MAPPING PageMap;
+    BOOLEAN IdentityMapping;
 
     /* Initialize XTOS startup sequence */
     XtLdrProtocol->Debug.Print(L"Initializing XTOS startup sequence\n");
@@ -634,18 +635,30 @@ Xtos::RunBootSequence(IN PEFI_FILE_HANDLE BootDir,
     /* Close FrameBuffer protocol */
     XtLdrProtocol->Protocol.Close(&ProtocolHandle, &FrameBufGuid);
 
+    /* Determine whether to use a sequential or an identity mapping strategy */
+    IdentityMapping = DetermineMappingStrategy();
+
     /* Set base virtual memory area for the kernel mappings */
     VirtualAddress = (PVOID)(KSEG0_BASE);
 
     /* Initialize virtual memory mappings */
     XtLdrProtocol->Memory.InitializePageMap(&PageMap, DeterminePagingLevel(Parameters->Parameters), Size4K);
 
-    Status = XtLdrProtocol->Memory.MapEfiMemory(&PageMap, &VirtualAddress, NULLPTR);
+    /* Map all EFI memory regions */
+    Status = XtLdrProtocol->Memory.MapEfiMemory(&PageMap, &VirtualAddress, IdentityMapping, NULLPTR);
     if(Status != STATUS_EFI_SUCCESS)
     {
+        /* Mapping failed */
         return Status;
     }
 
+    /* Check mapping strategy */
+    if(IdentityMapping)
+    {
+        /* Adjust virtual address to skip the identity-mapped physical range */
+        VirtualAddress = (PVOID)((ULONGLONG)VirtualAddress + 0x800000000);
+    }
+
     /* Load the kernel */
     Status = LoadModule(BootDir, Parameters->KernelFile, VirtualAddress, LoaderSystemCode, &ImageContext);
     if(Status != STATUS_EFI_SUCCESS)

sdk/xtdk/bltypes.h

@@ -100,7 +100,7 @@ typedef VOID (XTCDECL *PBL_LLIST_INITIALIZE_HEAD)(IN PLIST_ENTRY ListHead);
 typedef VOID (XTCDECL *PBL_LLIST_INSERT_HEAD)(IN OUT PLIST_ENTRY ListHead, IN PLIST_ENTRY Entry);
 typedef VOID (XTCDECL *PBL_LLIST_INSERT_TAIL)(IN OUT PLIST_ENTRY ListHead, IN PLIST_ENTRY Entry);
 typedef VOID (XTCDECL *PBL_LLIST_REMOVE_ENTRY)(IN PLIST_ENTRY Entry);
-typedef EFI_STATUS (XTCDECL *PBL_MAP_EFI_MEMORY)(IN OUT PXTBL_PAGE_MAPPING PageMap, IN OUT PVOID *MemoryMapAddress, IN PBL_GET_MEMTYPE_ROUTINE GetMemoryTypeRoutine);
+typedef EFI_STATUS (XTCDECL *PBL_MAP_EFI_MEMORY)(IN OUT PXTBL_PAGE_MAPPING PageMap, IN OUT PVOID *BaseAddress, IN BOOLEAN IdentityMapping, IN PBL_GET_MEMTYPE_ROUTINE GetMemoryTypeRoutine);
 typedef EFI_STATUS (XTCDECL *PBL_MAP_PAGE)(IN PXTBL_PAGE_MAPPING PageMap, IN ULONGLONG VirtualAddress, IN ULONGLONG PhysicalAddress, IN ULONGLONG NumberOfPages);
 typedef EFI_STATUS (XTCDECL *PBL_MAP_VIRTUAL_MEMORY)(IN OUT PXTBL_PAGE_MAPPING PageMap, IN ULONGLONG VirtualAddress, IN ULONGLONG PhysicalAddress, IN ULONGLONG NumberOfPages, IN LOADER_MEMORY_TYPE MemoryType);
 typedef VOID (XTAPI *PBL_MOVE_MEMORY)(IN OUT PVOID Destination, IN PCVOID Source, IN SIZE_T Length);