BaseTools: Add support for preserving build ID

Adds an optional flag that copies the GNU build-id note from the input
ELF file into the output PE/COFF firmware image as a dedicated ".bldid"
section. The build ID is emitted by the linker as a unique fingerprint
of the binary and allows custom post-build and debugging tools to
reliably match a firmware image against its corresponding unstripped
ELF and debug symbols, without relying on file names, timestamps, or
build paths.

This notable opts to use a non-standard section name ".bldid" to store
the build ID. This approach was chosen to keep genfw and the parsers simple
since the full "build-id" name would require redirecting the section name.
While this breaks from standard conventions, this is not impactful since
GenFW is already creating a non-standard artifact for the PE image with
the associated ELF symbol file.

Signed-off-by: Chris Fernald <chfernal@microsoft.com>

BaseTools/Source/C/GenFw/Elf64Convert.c

@@ -130,6 +130,8 @@ STATIC UINT32 mHiiRsrcOffset;
 STATIC UINT32 mRelocOffset;
 STATIC UINT32 mDebugOffset;
 STATIC UINT32 mExportOffset;
+STATIC UINT32 mBuildIdOffset;
+STATIC BOOLEAN mBuildIdFound;
 //
 // Used for RISC-V relocations.
 //
@@ -227,6 +229,10 @@ InitializeElf64 (
     ElfFunctions->WriteExport = WriteExport64;
   }
 
+  if (mBuildIdFlag) {
+    mCoffNbrSections++;
+  }
+
   return TRUE;
 }
 
@@ -290,6 +296,22 @@ IsHiiRsrcShdr (
   return (BOOLEAN) (strcmp((CHAR8*)mEhdr + Namedr->sh_offset + Shdr->sh_name, ELF_HII_SECTION_NAME) == 0);
 }
 
+STATIC
+BOOLEAN
+IsBuildIdShdr (
+  Elf_Shdr *Shdr
+  )
+{
+  Elf_Shdr *Namedr = GetShdrByIndex(mEhdr->e_shstrndx);
+
+  if (Namedr->sh_offset + Shdr->sh_name >= mFileBufferSize) {
+    Error (NULL, 0, 3000, "Invalid", "IsBuildIdShdr: Name offset %lu is larger then file size %lu", mEhdr->e_shstrndx, mFileBufferSize);
+    exit(EXIT_FAILURE);
+  }
+
+  return (BOOLEAN) (strcmp((CHAR8*)mEhdr + Namedr->sh_offset + Shdr->sh_name, ELF_BUILD_ID_SECTION_NAME) == 0);
+}
+
 STATIC
 BOOLEAN
 IsSymbolShdr (
@@ -1123,6 +1145,40 @@ ScanSections64 (
     }
   }
 
+  //
+  //  The build-ID section.
+  //
+  mBuildIdOffset = mCoffOffset;
+  mBuildIdFound = FALSE;
+  if (mBuildIdFlag) {
+    for (i = 0; i < mEhdr->e_shnum; i++) {
+      Elf_Shdr *shdr = GetShdrByIndex(i);
+      if (IsBuildIdShdr(shdr)) {
+        if ((shdr->sh_addralign != 0) && (shdr->sh_addralign != 1)) {
+          // the alignment field is valid
+          if ((shdr->sh_addr & (shdr->sh_addralign - 1)) == 0) {
+            // if the section address is aligned we must align PE/COFF
+            mCoffOffset = (UINT32) ((mCoffOffset + shdr->sh_addralign - 1) & ~(shdr->sh_addralign - 1));
+          } else {
+            Error (NULL, 0, 3000, "Invalid", "Section address not aligned to its own alignment.");
+          }
+        }
+        if (shdr->sh_size != 0) {
+          mBuildIdOffset = mCoffOffset;
+          mCoffSectionsOffset[i] = mCoffOffset;
+          mCoffOffset += (UINT32) shdr->sh_size;
+          mCoffOffset = CoffAlign(mCoffOffset);
+          mBuildIdFound = TRUE;
+        }
+        break;
+      }
+    }
+
+    if (!mBuildIdFound) {
+      Warning (NULL, 0, 0, NULL, "Build ID section is not found in %s.", mInImageName);
+    }
+  }
+
   mRelocOffset = mCoffOffset;
 
   //
@@ -1242,18 +1298,41 @@ ScanSections64 (
     }
   }
 
-  if ((mRelocOffset - mHiiRsrcOffset) > 0) {
-    CreateSectionHeader (".rsrc", mHiiRsrcOffset, mRelocOffset - mHiiRsrcOffset,
+  //
+  // Determine the end offset for .rsrc section based on whether build-ID is present
+  //
+  if (mBuildIdFound) {
+    Offset = mBuildIdOffset;
+  } else {
+    Offset = mRelocOffset;
+  }
+
+  if ((Offset - mHiiRsrcOffset) > 0) {
+    CreateSectionHeader (".rsrc", mHiiRsrcOffset, Offset - mHiiRsrcOffset,
             EFI_IMAGE_SCN_CNT_INITIALIZED_DATA
             | EFI_IMAGE_SCN_MEM_READ);
 
-    NtHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_RESOURCE].Size = mRelocOffset - mHiiRsrcOffset;
+    NtHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_RESOURCE].Size = Offset - mHiiRsrcOffset;
     NtHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_RESOURCE].VirtualAddress = mHiiRsrcOffset;
   } else {
     // Don't make a section of size 0.
     NtHdr->Pe32Plus.FileHeader.NumberOfSections--;
   }
 
+  //
+  // Add build-ID section if requested and found
+  //
+  if (mBuildIdFlag) {
+    if (mBuildIdFound) {
+      CreateSectionHeader (".bldid", mBuildIdOffset, mRelocOffset - mBuildIdOffset,
+              EFI_IMAGE_SCN_CNT_INITIALIZED_DATA
+              | EFI_IMAGE_SCN_MEM_READ);
+    } else {
+      // Don't make a section of size 0, decrement the section count
+      NtHdr->Pe32Plus.FileHeader.NumberOfSections--;
+    }
+  }
+
 }
 
 STATIC
@@ -1281,6 +1360,9 @@ WriteSections64 (
     case SECTION_DATA:
       Filter = IsDataShdr;
       break;
+    case SECTION_BUILD_ID:
+      Filter = IsBuildIdShdr;
+      break;
     default:
       return FALSE;
   }

BaseTools/Source/C/GenFw/ElfConvert.c

@@ -210,6 +210,11 @@ ConvertElf (
   if (!ElfFunctions.WriteSections (SECTION_HII)) {
     return FALSE;
   }
+  if (mBuildIdFlag) {
+    if (!ElfFunctions.WriteSections (SECTION_BUILD_ID)) {
+      return FALSE;
+    }
+  }
 
   //
   // Translate and write relocations.

BaseTools/Source/C/GenFw/ElfConvert.h

@@ -24,14 +24,16 @@ extern UINT32   mTableOffset;
 extern UINT32   mOutImageType;
 extern UINT32   mFileBufferSize;
 extern BOOLEAN  mExportFlag;
+extern BOOLEAN  mBuildIdFlag;
 
 //
 // Common EFI specific data.
 //
-#define ELF_HII_SECTION_NAME     ".hii"
-#define ELF_STRTAB_SECTION_NAME  ".strtab"
-#define MAX_COFF_ALIGNMENT       0x10000
-#define ELF_SYMBOL_SECTION_NAME  ".symtab"
+#define ELF_HII_SECTION_NAME       ".hii"
+#define ELF_STRTAB_SECTION_NAME    ".strtab"
+#define MAX_COFF_ALIGNMENT         0x10000
+#define ELF_SYMBOL_SECTION_NAME    ".symtab"
+#define ELF_BUILD_ID_SECTION_NAME  ".build-id"
 
 //
 // Platform Runtime Mechanism (PRM) specific data.
@@ -77,7 +79,8 @@ typedef enum {
   SECTION_TEXT,
   SECTION_HII,
   SECTION_DATA,
-  SECTION_SYMBOL
+  SECTION_SYMBOL,
+  SECTION_BUILD_ID
 } SECTION_FILTER_TYPES;
 
 //

BaseTools/Source/C/GenFw/GenFw.c

@@ -89,6 +89,7 @@ UINT32 mOutImageType = FW_DUMMY_IMAGE;
 BOOLEAN mIsConvertXip = FALSE;
 BOOLEAN mExportFlag = FALSE;
 BOOLEAN mNoNxCompat = FALSE;
+BOOLEAN mBuildIdFlag = FALSE;
 
 STATIC
 EFI_STATUS
@@ -290,6 +291,10 @@ Returns:
   fprintf (stdout, "  --nonxcompat          Do not set the IMAGE_DLLCHARACTERISTICS_NX_COMPAT bit \n\
                         of the optional header in the PE header even if the \n\
                         requirements are met.\n");
+  fprintf (stdout, "  --build-id            Preserve the .build-id section from the ELF image\n\
+                        and copy it to a .bldid section in the PE image.\n\
+                        This option can be used together with -e or -t.\n\
+                        It doesn't work for other options.\n");
   fprintf (stdout, "  -v, --verbose         Turn on verbose output with informational messages.\n");
   fprintf (stdout, "  -q, --quiet           Disable all messages except key message and fatal error\n");
   fprintf (stdout, "  -d, --debug level     Enable debug messages, at input debug level.\n");
@@ -1576,6 +1581,13 @@ Returns:
       continue;
     }
 
+    if (stricmp (argv[0], "--build-id") == 0) {
+      mBuildIdFlag = TRUE;
+      argc--;
+      argv++;
+      continue;
+    }
+
     if (argv[0][0] == '-') {
       Error (NULL, 0, 1000, "Unknown option", argv[0]);
       goto Finish;