MdePkg/PeCoffLib: Capture DLL characteristics fields in image context

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4405

When loading a PE/COFF image, capture the DLL characteristics fields of
the header into our image context structure so we can refer to them when
mapping the image.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Oliver Smith-Denny <osde@linux.microsoft.com>
Reviewed-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdePkg/Include/IndustryStandard/PeImage.h

@@ -625,7 +625,8 @@ typedef struct {
   UINT32    FileOffset;  ///< The file pointer to the debug data.
 } EFI_IMAGE_DEBUG_DIRECTORY_ENTRY;
 
-#define EFI_IMAGE_DEBUG_TYPE_CODEVIEW  2    ///< The Visual C++ debug information.
+#define EFI_IMAGE_DEBUG_TYPE_CODEVIEW               2    ///< The Visual C++ debug information.
+#define EFI_IMAGE_DEBUG_TYPE_EX_DLLCHARACTERISTICS  20
 
 ///
 /// Debug Data Structure defined in Microsoft C++.
@@ -669,6 +670,16 @@ typedef struct {
   //
 } EFI_IMAGE_DEBUG_CODEVIEW_MTOC_ENTRY;
 
+///
+/// Extended DLL Characteristics
+///
+#define EFI_IMAGE_DLLCHARACTERISTICS_EX_CET_COMPAT          0x0001
+#define EFI_IMAGE_DLLCHARACTERISTICS_EX_FORWARD_CFI_COMPAT  0x0040
+
+typedef struct {
+  UINT32    DllCharacteristicsEx;
+} EFI_IMAGE_DEBUG_EX_DLLCHARACTERISTICS_ENTRY;
+
 ///
 /// Resource format.
 ///

MdePkg/Include/Library/PeCoffLib.h

@@ -171,6 +171,12 @@ typedef struct {
   ///
   UINT16                      ImageType;
   ///
+  /// Set by PeCoffLoaderGetImageInfo() to the DLL flags stored in the PE/COFF header and
+  /// in the DllCharacteristicsEx debug table.
+  ///
+  UINT16                      DllCharacteristics;
+  UINT32                      DllCharacteristicsEx;
+  ///
   /// Set by PeCoffLoaderGetImageInfo() to TRUE if the PE/COFF image does not contain
   /// relocation information.
   ///