[edk2] BaseTools/GenFw: move .debug contents to .data to save space

Message ID 1436988391-16305-1-git-send-email-ard.biesheuvel@linaro.org
State New
Headers show

Commit Message

Ard Biesheuvel July 15, 2015, 7:26 p.m.
In order to reduce the memory footprint of PE/COFF images when
using large values for the PE/COFF section alignment, move the
contents of the .debug section to .data, and point the debug data
directory entry to it. This allows us to drop the .debug section
entirely, as well as any associated rounding. Since our .debug
section only contains the filename of the ELF input image, the
penalty of keeping this data in a non-discardable section is
negligible.

Note that the PE/COFF spec v6.3 explicitly mentions that this is
allowed.

This also makes it possible to actually drop the .reloc section
from a XIP binary, since .reloc is now the final section in the
image.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 BaseTools/Source/C/GenFw/Elf32Convert.c | 55 ++++++++++++++++-----------------
 BaseTools/Source/C/GenFw/Elf64Convert.c | 54 ++++++++++++++++----------------
 2 files changed, 53 insertions(+), 56 deletions(-)

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diff --git a/BaseTools/Source/C/GenFw/Elf32Convert.c b/BaseTools/Source/C/GenFw/Elf32Convert.c
index 10d9892ba1e0..ba68833f2fb8 100644
--- a/BaseTools/Source/C/GenFw/Elf32Convert.c
+++ b/BaseTools/Source/C/GenFw/Elf32Convert.c
@@ -101,7 +101,7 @@  STATIC UINT32 mCoffAlignment = 0x20;
 //
 // PE section alignment.
 //
-STATIC const UINT16 mCoffNbrSections = 5;
+STATIC const UINT16 mCoffNbrSections = 4;
 
 //
 // ELF sections to offset in Coff file.
@@ -116,6 +116,7 @@  STATIC UINT32 mTextOffset;
 STATIC UINT32 mDataOffset;
 STATIC UINT32 mHiiRsrcOffset;
 STATIC UINT32 mRelocOffset;
+STATIC UINT32 mDebugOffset;
 
 //
 // Initialization Function
@@ -354,6 +355,8 @@  ScanSections32 (
     assert (FALSE);
   }
 
+  mDebugOffset = mCoffOffset;
+
   if (mEhdr->e_machine != EM_ARM) {
     mCoffOffset = CoffAlign(mCoffOffset);
   }
@@ -405,6 +408,24 @@  ScanSections32 (
   }
 
   //
+  // Make room for .debug data in .data (or .text if .data is empty) instead of
+  // putting it in a section of its own. This is explicitly allowed by the
+  // PE/COFF spec, and prevents bloat in the binary when using large values for
+  // section alignment.
+  //
+  if (SectionCount > 0) {
+    mDebugOffset = mCoffOffset;
+  }
+  mCoffOffset += sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY) +
+                 sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY) +
+                 strlen(mInImageName) + 1;
+
+  mCoffOffset = CoffAlign(mCoffOffset);
+  if (SectionCount == 0) {
+    mDataOffset = mCoffOffset;
+  }
+
+  //
   //  The HII resource sections.
   //
   mHiiRsrcOffset = mCoffOffset;
@@ -998,28 +1019,18 @@  WriteDebug32 (
   )
 {
   UINT32                              Len;
-  UINT32                              DebugOffset;
   EFI_IMAGE_OPTIONAL_HEADER_UNION     *NtHdr;
   EFI_IMAGE_DATA_DIRECTORY            *DataDir;
   EFI_IMAGE_DEBUG_DIRECTORY_ENTRY     *Dir;
   EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY *Nb10;
 
   Len = strlen(mInImageName) + 1;
-  DebugOffset = mCoffOffset;
-
-  mCoffOffset += sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY)
-    + sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY)
-    + Len;
-  mCoffOffset = CoffAlign(mCoffOffset);
-
-  mCoffFile = realloc(mCoffFile, mCoffOffset);
-  memset(mCoffFile + DebugOffset, 0, mCoffOffset - DebugOffset);
 
-  Dir = (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY*)(mCoffFile + DebugOffset);
+  Dir = (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY*)(mCoffFile + mDebugOffset);
   Dir->Type = EFI_IMAGE_DEBUG_TYPE_CODEVIEW;
   Dir->SizeOfData = sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY) + Len;
-  Dir->RVA = DebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
-  Dir->FileOffset = DebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
+  Dir->RVA = mDebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
+  Dir->FileOffset = mDebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
 
   Nb10 = (EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY*)(Dir + 1);
   Nb10->Signature = CODEVIEW_SIGNATURE_NB10;
@@ -1028,20 +1039,8 @@  WriteDebug32 (
 
   NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)(mCoffFile + mNtHdrOffset);
   DataDir = &NtHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_DEBUG];
-  DataDir->VirtualAddress = DebugOffset;
-  DataDir->Size = mCoffOffset - DebugOffset;
-  if (DataDir->Size == 0) {
-    // If no debug, null out the directory entry and don't add the .debug section
-    DataDir->VirtualAddress = 0;
-    NtHdr->Pe32.FileHeader.NumberOfSections--;
-  } else {
-    DataDir->VirtualAddress = DebugOffset;
-    CreateSectionHeader (".debug", DebugOffset, mCoffOffset - DebugOffset,
-            EFI_IMAGE_SCN_CNT_INITIALIZED_DATA
-            | EFI_IMAGE_SCN_MEM_DISCARDABLE
-            | EFI_IMAGE_SCN_MEM_READ);
-
-  }
+  DataDir->VirtualAddress = mDebugOffset;
+  DataDir->Size = Dir->SizeOfData + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
 }
 
 STATIC
diff --git a/BaseTools/Source/C/GenFw/Elf64Convert.c b/BaseTools/Source/C/GenFw/Elf64Convert.c
index d2becf165f55..9265e6f9d03c 100644
--- a/BaseTools/Source/C/GenFw/Elf64Convert.c
+++ b/BaseTools/Source/C/GenFw/Elf64Convert.c
@@ -102,7 +102,7 @@  STATIC UINT32 mCoffAlignment = 0x20;
 //
 // PE section alignment.
 //
-STATIC const UINT16 mCoffNbrSections = 5;
+STATIC const UINT16 mCoffNbrSections = 4;
 
 //
 // ELF sections to offset in Coff file.
@@ -117,6 +117,7 @@  STATIC UINT32 mTextOffset;
 STATIC UINT32 mDataOffset;
 STATIC UINT32 mHiiRsrcOffset;
 STATIC UINT32 mRelocOffset;
+STATIC UINT32 mDebugOffset;
 
 //
 // Initialization Function
@@ -348,6 +349,8 @@  ScanSections64 (
     assert (FALSE);
   }
 
+  mDebugOffset = mCoffOffset;
+
   if (mEhdr->e_machine != EM_ARM) {
     mCoffOffset = CoffAlign(mCoffOffset);
   }
@@ -391,7 +394,24 @@  ScanSections64 (
       SectionCount ++;
     }
   }
+
+  //
+  // Make room for .debug data in .data (or .text if .data is empty) instead of
+  // putting it in a section of its own. This is explicitly allowed by the
+  // PE/COFF spec, and prevents bloat in the binary when using large values for
+  // section alignment.
+  //
+  if (SectionCount > 0) {
+    mDebugOffset = mCoffOffset;
+  }
+  mCoffOffset += sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY) +
+                 sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY) +
+                 strlen(mInImageName) + 1;
+
   mCoffOffset = CoffAlign(mCoffOffset);
+  if (SectionCount == 0) {
+    mDataOffset = mCoffOffset;
+  }
 
   if (SectionCount > 1 && mOutImageType == FW_EFI_IMAGE) {
     Warning (NULL, 0, 0, NULL, "Mulitple sections in %s are merged into 1 data section. Source level debug might not work correctly.", mInImageName);
@@ -903,28 +923,18 @@  WriteDebug64 (
   )
 {
   UINT32                              Len;
-  UINT32                              DebugOffset;
   EFI_IMAGE_OPTIONAL_HEADER_UNION     *NtHdr;
   EFI_IMAGE_DATA_DIRECTORY            *DataDir;
   EFI_IMAGE_DEBUG_DIRECTORY_ENTRY     *Dir;
   EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY *Nb10;
 
   Len = strlen(mInImageName) + 1;
-  DebugOffset = mCoffOffset;
-
-  mCoffOffset += sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY)
-    + sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY)
-    + Len;
-  mCoffOffset = CoffAlign(mCoffOffset);
 
-  mCoffFile = realloc(mCoffFile, mCoffOffset);
-  memset(mCoffFile + DebugOffset, 0, mCoffOffset - DebugOffset);
-
-  Dir = (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY*)(mCoffFile + DebugOffset);
+  Dir = (EFI_IMAGE_DEBUG_DIRECTORY_ENTRY*)(mCoffFile + mDebugOffset);
   Dir->Type = EFI_IMAGE_DEBUG_TYPE_CODEVIEW;
   Dir->SizeOfData = sizeof(EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY) + Len;
-  Dir->RVA = DebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
-  Dir->FileOffset = DebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
+  Dir->RVA = mDebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
+  Dir->FileOffset = mDebugOffset + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
 
   Nb10 = (EFI_IMAGE_DEBUG_CODEVIEW_NB10_ENTRY*)(Dir + 1);
   Nb10->Signature = CODEVIEW_SIGNATURE_NB10;
@@ -933,20 +943,8 @@  WriteDebug64 (
 
   NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)(mCoffFile + mNtHdrOffset);
   DataDir = &NtHdr->Pe32Plus.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_DEBUG];
-  DataDir->VirtualAddress = DebugOffset;
-  DataDir->Size = mCoffOffset - DebugOffset;
-  if (DataDir->Size == 0) {
-    // If no debug, null out the directory entry and don't add the .debug section
-    DataDir->VirtualAddress = 0;
-    NtHdr->Pe32Plus.FileHeader.NumberOfSections--;
-  } else {
-    DataDir->VirtualAddress = DebugOffset;
-    CreateSectionHeader (".debug", DebugOffset, mCoffOffset - DebugOffset,
-            EFI_IMAGE_SCN_CNT_INITIALIZED_DATA
-            | EFI_IMAGE_SCN_MEM_DISCARDABLE
-            | EFI_IMAGE_SCN_MEM_READ);
-
-  }
+  DataDir->VirtualAddress = mDebugOffset;
+  DataDir->Size = Dir->SizeOfData + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
 }
 
 STATIC