[edk2-devel] [PATCH v1] MdeModulePkg: Fixup MAT Attributes After Splitting EFI Memory Map

["Taylor Beebe" <taylor.d.beebe@gmail.com>]

The Memory Attributes Table is generated by fetching the EFI
memory map and splitting entries which contain loaded
images so DATA and CODE sections have separate descriptors.
The splitting is done via a call to SplitTable() which
marks image DATA sections with the EFI_MEMORY_XP attribute
and CODE sections with the EFI_MEMORY_RO attribute when
splitting. After this process, there may still be
EfiRuntimeServicesCode regions which did not have their
attributes set because they are not part of loaded images.

This patch updates the MAT EnforceMemoryMapAttribute logic
to set the access attributes of runtime memory regions
which are not part of loaded images (have not had their
access attributes set).

Cc: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Taylor Beebe <taylor.d.beebe@gmail.com>
---
 MdeModulePkg/Core/Dxe/Misc/MemoryAttributesTable.c | 29 ++++++++++----------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/MdeModulePkg/Core/Dxe/Misc/MemoryAttributesTable.c b/MdeModulePkg/Core/Dxe/Misc/MemoryAttributesTable.c
index e9343a2c4e..1d9f935db0 100644
--- a/MdeModulePkg/Core/Dxe/Misc/MemoryAttributesTable.c
+++ b/MdeModulePkg/Core/Dxe/Misc/MemoryAttributesTable.c
@@ -425,8 +425,8 @@ MergeMemoryMap (
 }
 
 /**
-  Enforce memory map attributes.
-  This function will set EfiRuntimeServicesData/EfiMemoryMappedIO/EfiMemoryMappedIOPortSpace to be EFI_MEMORY_XP.
+  Walk the memory map and set EfiRuntimeServicesData/EfiMemoryMappedIO/EfiMemoryMappedIOPortSpace
+  to EFI_MEMORY_XP and EfiRuntimeServicesCode to EFI_MEMORY_RO.
 
   @param  MemoryMap              A pointer to the buffer in which firmware places
                                  the current memory map.
@@ -447,18 +447,19 @@ EnforceMemoryMapAttribute (
   MemoryMapEntry = MemoryMap;
   MemoryMapEnd   = (EFI_MEMORY_DESCRIPTOR *)((UINT8 *)MemoryMap + MemoryMapSize);
   while ((UINTN)MemoryMapEntry < (UINTN)MemoryMapEnd) {
-    switch (MemoryMapEntry->Type) {
-      case EfiRuntimeServicesCode:
-        // do nothing
-        break;
-      case EfiRuntimeServicesData:
-      case EfiMemoryMappedIO:
-      case EfiMemoryMappedIOPortSpace:
-        MemoryMapEntry->Attribute |= EFI_MEMORY_XP;
-        break;
-      case EfiReservedMemoryType:
-      case EfiACPIMemoryNVS:
-        break;
+    if ((MemoryMapEntry->Attribute & EFI_MEMORY_ACCESS_MASK) == 0) {
+      switch (MemoryMapEntry->Type) {
+        case EfiRuntimeServicesCode:
+          MemoryMapEntry->Attribute |= EFI_MEMORY_RO;
+          break;
+        case EfiRuntimeServicesData:
+        case EfiMemoryMappedIO:
+        case EfiMemoryMappedIOPortSpace:
+          MemoryMapEntry->Attribute |= EFI_MEMORY_XP;
+          break;
+        default:
+          break;
+      }
     }
 
     MemoryMapEntry = NEXT_MEMORY_DESCRIPTOR (MemoryMapEntry, DescriptorSize);
-- 
2.40.1.vfs.0.0



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