[PATCH v3 2/4] BaseTools/GenFw: Add DllCharacteristicsEx field to debug data

["Ard Biesheuvel" <ardb@kernel.org>]

The PE/COFF spec describes an additional DllCharacteristics field
implemented as a debug directory entry, which carries flags related to
which control flow integrity (CFI) features are supported by the binary.

So let's add this entry when doing ELF to PE/COFF conversion - we will
add support for setting the flags in a subsequent patch.

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>
---
 BaseTools/Source/C/GenFw/Elf64Convert.c               | 54 +++++++++++++++-----
 BaseTools/Source/C/GenFw/GenFw.c                      |  3 +-
 BaseTools/Source/C/Include/IndustryStandard/PeImage.h | 13 ++++-
 3 files changed, 55 insertions(+), 15 deletions(-)

diff --git a/BaseTools/Source/C/GenFw/Elf64Convert.c b/BaseTools/Source/C/GenFw/Elf64Convert.c
index 2a810e835d4a4a66..9c17c90b16602421 100644
--- a/BaseTools/Source/C/GenFw/Elf64Convert.c
+++ b/BaseTools/Source/C/GenFw/Elf64Convert.c
@@ -992,6 +992,16 @@ ScanSections64 (
                 sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY) +
                 strlen(mInImageName) + 1;
 
+  //
+  // Add more space in the .debug data region for the DllCharacteristicsEx
+  // field.
+  //
+  if (mDllCharacteristicsEx != 0) {
+    mCoffOffset = DebugRvaAlign(mCoffOffset) +
+                  sizeof (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY) +
+                  sizeof (EFI_IMAGE_DEBUG_EX_DLLCHARACTERISTICS_ENTRY);
+  }
+
   mCoffOffset = CoffAlign(mCoffOffset);
   if (SectionCount == 0) {
     mDataOffset = mCoffOffset;
@@ -2244,29 +2254,47 @@ WriteDebug64 (
   VOID
   )
 {
-  UINT32                              Len;
-  EFI_IMAGE_OPTIONAL_HEADER_UNION     *NtHdr;
-  EFI_IMAGE_DATA_DIRECTORY            *DataDir;
-  EFI_IMAGE_DEBUG_DIRECTORY_ENTRY     *Dir;
-  EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY *Nb10;
+  UINT32                                      Len;
+  EFI_IMAGE_OPTIONAL_HEADER_UNION             *NtHdr;
+  EFI_IMAGE_DATA_DIRECTORY                    *DataDir;
+  EFI_IMAGE_DEBUG_DIRECTORY_ENTRY             *Dir;
+  EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY         *Nb10;
+  EFI_IMAGE_DEBUG_EX_DLLCHARACTERISTICS_ENTRY *DllEntry;
 
   Len = strlen(mInImageName) + 1;
 
+  NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)(mCoffFile + mNtHdrOffset);
+  DataDir = &NtHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_DEBUG];
+  DataDir->VirtualAddress = mDebugOffset;
+  DataDir->Size = sizeof (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
+
   Dir = (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY*)(mCoffFile + mDebugOffset);
+
+  if (mDllCharacteristicsEx != 0) {
+    DataDir->Size  += sizeof (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
+
+    Dir->Type       = EFI_IMAGE_DEBUG_TYPE_EX_DLLCHARACTERISTICS;
+    Dir->SizeOfData = sizeof (EFI_IMAGE_DEBUG_EX_DLLCHARACTERISTICS_ENTRY);
+    Dir->FileOffset = mDebugOffset + DataDir->Size +
+                      sizeof (EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY) +
+                      DebugRvaAlign(Len);
+    Dir->RVA        = Dir->FileOffset;
+
+    DllEntry = (VOID *)(mCoffFile + Dir->FileOffset);
+
+    DllEntry->DllCharacteristicsEx = mDllCharacteristicsEx;
+
+    Dir++;
+  }
+
   Dir->Type = EFI_IMAGE_DEBUG_TYPE_CODEVIEW;
   Dir->SizeOfData = sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY) + Len;
-  Dir->RVA = mDebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
-  Dir->FileOffset = mDebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
+  Dir->RVA = mDebugOffset + DataDir->Size;
+  Dir->FileOffset = mDebugOffset + DataDir->Size;
 
   Nb10 = (EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY*)(Dir + 1);
   Nb10->Signature = CODEVIEW_SIGNATURE_NB10;
   strcpy ((char *)(Nb10 + 1), mInImageName);
-
-
-  NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)(mCoffFile + mNtHdrOffset);
-  DataDir = &NtHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_DEBUG];
-  DataDir->VirtualAddress = mDebugOffset;
-  DataDir->Size = sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
 }
 
 STATIC
diff --git a/BaseTools/Source/C/GenFw/GenFw.c b/BaseTools/Source/C/GenFw/GenFw.c
index 6f61f16788cd2a0a..d0e52ccc26431380 100644
--- a/BaseTools/Source/C/GenFw/GenFw.c
+++ b/BaseTools/Source/C/GenFw/GenFw.c
@@ -2932,7 +2932,8 @@ Routine Description:
       if (mIsConvertXip) {
         DebugEntry->FileOffset = DebugEntry->RVA;
       }
-      if (ZeroDebugFlag || DebugEntry->Type != EFI_IMAGE_DEBUG_TYPE_CODEVIEW) {
+      if ((ZeroDebugFlag || DebugEntry->Type != EFI_IMAGE_DEBUG_TYPE_CODEVIEW) &&
+          (DebugEntry->Type != EFI_IMAGE_DEBUG_TYPE_EX_DLLCHARACTERISTICS)) {
         memset (FileBuffer + DebugEntry->FileOffset, 0, DebugEntry->SizeOfData);
         memset (DebugEntry, 0, sizeof (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY));
       }
diff --git a/BaseTools/Source/C/Include/IndustryStandard/PeImage.h b/BaseTools/Source/C/Include/IndustryStandard/PeImage.h
index 77ded3f611398278..22161edf443d0e22 100644
--- a/BaseTools/Source/C/Include/IndustryStandard/PeImage.h
+++ b/BaseTools/Source/C/Include/IndustryStandard/PeImage.h
@@ -615,7 +615,8 @@ typedef struct {
 ///
 /// Debug Format
 ///
-#define EFI_IMAGE_DEBUG_TYPE_CODEVIEW 2
+#define EFI_IMAGE_DEBUG_TYPE_CODEVIEW               2
+#define EFI_IMAGE_DEBUG_TYPE_EX_DLLCHARACTERISTICS  20
 
 typedef struct {
   UINT32  Characteristics;
@@ -664,6 +665,16 @@ 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;
+
 //
 // .pdata entries for X64
 //
-- 
2.39.2