BaseTools/Source/C/GenFw/Elf32Convert.c

/** @file
Elf32 Convert solution

Copyright (c) 2010 - 2016, Intel Corporation. All rights reserved.<BR>
Portions copyright (c) 2013, ARM Ltd. All rights reserved.<BR>

This program and the accompanying materials are licensed and made available
under the terms and conditions of the BSD License which accompanies this
distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "WinNtInclude.h"

#ifndef __GNUC__
#include <windows.h>
#include <io.h>
#endif
#include <assert.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <ctype.h>

#include <Common/UefiBaseTypes.h>
#include <IndustryStandard/PeImage.h>

#include "PeCoffLib.h"
#include "EfiUtilityMsgs.h"

#include "GenFw.h"
#include "ElfConvert.h"
#include "Elf32Convert.h"

STATIC
VOID
ScanSections32 (
  VOID
  );

STATIC
BOOLEAN
WriteSections32 (
  SECTION_FILTER_TYPES  FilterType
  );

STATIC
VOID
WriteRelocations32 (
  VOID
  );

STATIC
VOID
WriteDebug32 (
  VOID
  );

STATIC
VOID
SetImageSize32 (
  VOID
  );

STATIC
VOID
CleanUp32 (
  VOID
  );

//
// Rename ELF32 strucutres to common names to help when porting to ELF64.
//
typedef Elf32_Shdr Elf_Shdr;
typedef Elf32_Ehdr Elf_Ehdr;
typedef Elf32_Rel Elf_Rel;
typedef Elf32_Sym Elf_Sym;
typedef Elf32_Phdr Elf_Phdr;
typedef Elf32_Dyn Elf_Dyn;
#define ELFCLASS ELFCLASS32
#define ELF_R_TYPE(r) ELF32_R_TYPE(r)
#define ELF_R_SYM(r) ELF32_R_SYM(r)

//
// Well known ELF structures.
//
STATIC Elf_Ehdr *mEhdr;
STATIC Elf_Shdr *mShdrBase;
STATIC Elf_Phdr *mPhdrBase;

//
// Coff information
//
STATIC UINT32 mCoffAlignment = 0x20;

//
// PE section alignment.
//
STATIC const UINT16 mCoffNbrSections = 4;

//
// ELF sections to offset in Coff file.
//
STATIC UINT32 *mCoffSectionsOffset = NULL;

//
// Offsets in COFF file
//
STATIC UINT32 mNtHdrOffset;
STATIC UINT32 mTextOffset;
STATIC UINT32 mDataOffset;
STATIC UINT32 mHiiRsrcOffset;
STATIC UINT32 mRelocOffset;
STATIC UINT32 mDebugOffset;

//
// Initialization Function
//
BOOLEAN
InitializeElf32 (
  UINT8               *FileBuffer,
  ELF_FUNCTION_TABLE  *ElfFunctions
  )
{
  //
  // Initialize data pointer and structures.
  //
  mEhdr = (Elf_Ehdr*) FileBuffer;  

  //
  // Check the ELF32 specific header information.
  //
  if (mEhdr->e_ident[EI_CLASS] != ELFCLASS32) {
    Error (NULL, 0, 3000, "Unsupported", "ELF EI_DATA not ELFCLASS32");
    return FALSE;
  }
  if (mEhdr->e_ident[EI_DATA] != ELFDATA2LSB) {
    Error (NULL, 0, 3000, "Unsupported", "ELF EI_DATA not ELFDATA2LSB");
    return FALSE;
  }  
  if ((mEhdr->e_type != ET_EXEC) && (mEhdr->e_type != ET_DYN)) {
    Error (NULL, 0, 3000, "Unsupported", "ELF e_type not ET_EXEC or ET_DYN");
    return FALSE;
  }
  if (!((mEhdr->e_machine == EM_386) || (mEhdr->e_machine == EM_ARM))) { 
    Error (NULL, 0, 3000, "Unsupported", "ELF e_machine not EM_386 or EM_ARM");
    return FALSE;
  }
  if (mEhdr->e_version != EV_CURRENT) {
    Error (NULL, 0, 3000, "Unsupported", "ELF e_version (%u) not EV_CURRENT (%d)", (unsigned) mEhdr->e_version, EV_CURRENT);
    return FALSE;
  }
  
  //
  // Update section header pointers
  //
  mShdrBase  = (Elf_Shdr *)((UINT8 *)mEhdr + mEhdr->e_shoff);
  mPhdrBase = (Elf_Phdr *)((UINT8 *)mEhdr + mEhdr->e_phoff);
  
  //
  // Create COFF Section offset buffer and zero.
  //
  mCoffSectionsOffset = (UINT32 *)malloc(mEhdr->e_shnum * sizeof (UINT32));
  memset(mCoffSectionsOffset, 0, mEhdr->e_shnum * sizeof(UINT32));

  //
  // Fill in function pointers.
  //
  ElfFunctions->ScanSections = ScanSections32;
  ElfFunctions->WriteSections = WriteSections32;
  ElfFunctions->WriteRelocations = WriteRelocations32;
  ElfFunctions->WriteDebug = WriteDebug32;
  ElfFunctions->SetImageSize = SetImageSize32;
  ElfFunctions->CleanUp = CleanUp32;

  return TRUE;
}


//
// Header by Index functions
//
STATIC
Elf_Shdr*
GetShdrByIndex (
  UINT32 Num
  )
{
  if (Num >= mEhdr->e_shnum) {
    Error (NULL, 0, 3000, "Invalid", "GetShdrByIndex: Index %u is too high.", Num);
    exit(EXIT_FAILURE);
  }

  return (Elf_Shdr*)((UINT8*)mShdrBase + Num * mEhdr->e_shentsize);
}

STATIC
Elf_Phdr*
GetPhdrByIndex (
  UINT32 num
  )
{
  if (num >= mEhdr->e_phnum) {
    Error (NULL, 0, 3000, "Invalid", "GetPhdrByIndex: Index %u is too high.", num);
    exit(EXIT_FAILURE);
  }

  return (Elf_Phdr *)((UINT8*)mPhdrBase + num * mEhdr->e_phentsize);
}

STATIC
UINT32
CoffAlign (
  UINT32 Offset
  )
{
  return (Offset + mCoffAlignment - 1) & ~(mCoffAlignment - 1);
}

STATIC
UINT32
DebugRvaAlign (
  UINT32 Offset
  )
{
  return (Offset + 3) & ~3;
}

//
// filter functions
//
STATIC
BOOLEAN
IsTextShdr (
  Elf_Shdr *Shdr
  )
{
  return (BOOLEAN) ((Shdr->sh_flags & (SHF_WRITE | SHF_ALLOC)) == SHF_ALLOC);
}

STATIC
BOOLEAN
IsHiiRsrcShdr (
  Elf_Shdr *Shdr
  )
{
  Elf_Shdr *Namedr = GetShdrByIndex(mEhdr->e_shstrndx);

  return (BOOLEAN) (strcmp((CHAR8*)mEhdr + Namedr->sh_offset + Shdr->sh_name, ELF_HII_SECTION_NAME) == 0);
}

STATIC
BOOLEAN
IsDataShdr (
  Elf_Shdr *Shdr
  )
{
  if (IsHiiRsrcShdr(Shdr)) {
    return FALSE;
  }
  return (BOOLEAN) (Shdr->sh_flags & (SHF_WRITE | SHF_ALLOC)) == (SHF_ALLOC | SHF_WRITE);
}

STATIC
BOOLEAN
IsStrtabShdr (
  Elf_Shdr *Shdr
  )
{
  Elf_Shdr *Namedr = GetShdrByIndex(mEhdr->e_shstrndx);

  return (BOOLEAN) (strcmp((CHAR8*)mEhdr + Namedr->sh_offset + Shdr->sh_name, ELF_STRTAB_SECTION_NAME) == 0);
}

STATIC
Elf_Shdr *
FindStrtabShdr (
  VOID
  )
{
  UINT32 i;
  for (i = 0; i < mEhdr->e_shnum; i++) {
    Elf_Shdr *shdr = GetShdrByIndex(i);
    if (IsStrtabShdr(shdr)) {
      return shdr;
    }
  }
  return NULL;
}

STATIC
const UINT8 *
GetSymName (
  Elf_Sym *Sym
  )
{
  if (Sym->st_name == 0) {
    return NULL;
  }

  Elf_Shdr *StrtabShdr = FindStrtabShdr();
  if (StrtabShdr == NULL) {
    return NULL;
  }

  assert(Sym->st_name < StrtabShdr->sh_size);

  UINT8* StrtabContents = (UINT8*)mEhdr + StrtabShdr->sh_offset;

  bool foundEnd = false;
  UINT32 i;
  for (i = Sym->st_name; (i < StrtabShdr->sh_size) && !foundEnd; i++) {
    foundEnd = StrtabContents[i] == 0;
  }
  assert(foundEnd);

  return StrtabContents + Sym->st_name;
}

//
// Elf functions interface implementation
//

STATIC
VOID
ScanSections32 (
  VOID
  )
{
  UINT32                          i;
  EFI_IMAGE_DOS_HEADER            *DosHdr;
  EFI_IMAGE_OPTIONAL_HEADER_UNION *NtHdr;
  UINT32                          CoffEntry;
  UINT32                          SectionCount;
  BOOLEAN                         FoundSection;

  CoffEntry = 0;
  mCoffOffset = 0;

  //
  // Coff file start with a DOS header.
  //
  mCoffOffset = sizeof(EFI_IMAGE_DOS_HEADER) + 0x40;
  mNtHdrOffset = mCoffOffset;
  switch (mEhdr->e_machine) {
  case EM_386:
  case EM_ARM:
    mCoffOffset += sizeof (EFI_IMAGE_NT_HEADERS32);
  break;
  default:
    VerboseMsg ("%s unknown e_machine type. Assume IA-32", (UINTN)mEhdr->e_machine);
    mCoffOffset += sizeof (EFI_IMAGE_NT_HEADERS32);
  break;
  }

  mTableOffset = mCoffOffset;
  mCoffOffset += mCoffNbrSections * sizeof(EFI_IMAGE_SECTION_HEADER);

  //
  // Set mCoffAlignment to the maximum alignment of the input sections
  // we care about
  //
  for (i = 0; i < mEhdr->e_shnum; i++) {
    Elf_Shdr *shdr = GetShdrByIndex(i);
    if (shdr->sh_addralign <= mCoffAlignment) {
      continue;
    }
    if (IsTextShdr(shdr) || IsDataShdr(shdr) || IsHiiRsrcShdr(shdr)) {
      mCoffAlignment = (UINT32)shdr->sh_addralign;
    }
  }

  //
  // Move the PE/COFF header right before the first section. This will help us
  // save space when converting to TE.
  //
  if (mCoffAlignment > mCoffOffset) {
    mNtHdrOffset += mCoffAlignment - mCoffOffset;
    mTableOffset += mCoffAlignment - mCoffOffset;
    mCoffOffset = mCoffAlignment;
  }

  //
  // First text sections.
  //
  mCoffOffset = CoffAlign(mCoffOffset);
  mTextOffset = mCoffOffset;
  FoundSection = FALSE;
  SectionCount = 0;
  for (i = 0; i < mEhdr->e_shnum; i++) {
    Elf_Shdr *shdr = GetShdrByIndex(i);
    if (IsTextShdr(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 = (mCoffOffset + shdr->sh_addralign - 1) & ~(shdr->sh_addralign - 1);
        } else {
          Error (NULL, 0, 3000, "Invalid", "Section address not aligned to its own alignment.");
        }
      }

      /* Relocate entry.  */
      if ((mEhdr->e_entry >= shdr->sh_addr) &&
          (mEhdr->e_entry < shdr->sh_addr + shdr->sh_size)) {
        CoffEntry = mCoffOffset + mEhdr->e_entry - shdr->sh_addr;
      }

      //
      // Set mTextOffset with the offset of the first '.text' section
      //
      if (!FoundSection) {
        mTextOffset = mCoffOffset;
        FoundSection = TRUE;
      }

      mCoffSectionsOffset[i] = mCoffOffset;
      mCoffOffset += shdr->sh_size;
      SectionCount ++;
    }
  }

  if (!FoundSection) {
    Error (NULL, 0, 3000, "Invalid", "Did not find any '.text' section.");
    assert (FALSE);
  }

  mDebugOffset = DebugRvaAlign(mCoffOffset);
  mCoffOffset = CoffAlign(mCoffOffset);

  if (SectionCount > 1 && mOutImageType == FW_EFI_IMAGE) {
    Warning (NULL, 0, 0, NULL, "Mulitple sections in %s are merged into 1 text section. Source level debug might not work correctly.", mInImageName);
  }

  //
  //  Then data sections.
  //
  mDataOffset = mCoffOffset;
  FoundSection = FALSE;
  SectionCount = 0;
  for (i = 0; i < mEhdr->e_shnum; i++) {
    Elf_Shdr *shdr = GetShdrByIndex(i);
    if (IsDataShdr(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 = (mCoffOffset + shdr->sh_addralign - 1) & ~(shdr->sh_addralign - 1);
        } else {
          Error (NULL, 0, 3000, "Invalid", "Section address not aligned to its own alignment.");
        }
      }

      //
      // Set mDataOffset with the offset of the first '.data' section
      //
      if (!FoundSection) {
        mDataOffset = mCoffOffset;
        FoundSection = TRUE;
      }

      mCoffSectionsOffset[i] = mCoffOffset;
      mCoffOffset += shdr->sh_size;
      SectionCount ++;
    }
  }

  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);
  }

  //
  // 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 = DebugRvaAlign(mCoffOffset);
  }
  mCoffOffset = mDebugOffset + 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;
  for (i = 0; i < mEhdr->e_shnum; i++) {
    Elf_Shdr *shdr = GetShdrByIndex(i);
    if (IsHiiRsrcShdr(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 = (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) {
        mHiiRsrcOffset = mCoffOffset;
        mCoffSectionsOffset[i] = mCoffOffset;
        mCoffOffset += shdr->sh_size;
        mCoffOffset = CoffAlign(mCoffOffset);
        SetHiiResourceHeader ((UINT8*) mEhdr + shdr->sh_offset, mHiiRsrcOffset);
      }
      break;
    }
  }

  mRelocOffset = mCoffOffset;

  //
  // Allocate base Coff file.  Will be expanded later for relocations.
  //
  mCoffFile = (UINT8 *)malloc(mCoffOffset);
  memset(mCoffFile, 0, mCoffOffset);

  //
  // Fill headers.
  //
  DosHdr = (EFI_IMAGE_DOS_HEADER *)mCoffFile;
  DosHdr->e_magic = EFI_IMAGE_DOS_SIGNATURE;
  DosHdr->e_lfanew = mNtHdrOffset;

  NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION*)(mCoffFile + mNtHdrOffset);

  NtHdr->Pe32.Signature = EFI_IMAGE_NT_SIGNATURE;

  switch (mEhdr->e_machine) {
  case EM_386:
    NtHdr->Pe32.FileHeader.Machine = EFI_IMAGE_MACHINE_IA32;
    NtHdr->Pe32.OptionalHeader.Magic = EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC;
    break;
  case EM_ARM:
    NtHdr->Pe32.FileHeader.Machine = EFI_IMAGE_MACHINE_ARMT;
    NtHdr->Pe32.OptionalHeader.Magic = EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC;
    break;
  default:
    VerboseMsg ("%s unknown e_machine type %hu. Assume IA-32", mInImageName, mEhdr->e_machine);
    NtHdr->Pe32.FileHeader.Machine = EFI_IMAGE_MACHINE_IA32;
    NtHdr->Pe32.OptionalHeader.Magic = EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC;
  }

  NtHdr->Pe32.FileHeader.NumberOfSections = mCoffNbrSections;
  NtHdr->Pe32.FileHeader.TimeDateStamp = (UINT32) time(NULL);
  mImageTimeStamp = NtHdr->Pe32.FileHeader.TimeDateStamp;
  NtHdr->Pe32.FileHeader.PointerToSymbolTable = 0;
  NtHdr->Pe32.FileHeader.NumberOfSymbols = 0;
  NtHdr->Pe32.FileHeader.SizeOfOptionalHeader = sizeof(NtHdr->Pe32.OptionalHeader);
  NtHdr->Pe32.FileHeader.Characteristics = EFI_IMAGE_FILE_EXECUTABLE_IMAGE
    | EFI_IMAGE_FILE_LINE_NUMS_STRIPPED
    | EFI_IMAGE_FILE_LOCAL_SYMS_STRIPPED
    | EFI_IMAGE_FILE_32BIT_MACHINE;

  NtHdr->Pe32.OptionalHeader.SizeOfCode = mDataOffset - mTextOffset;
  NtHdr->Pe32.OptionalHeader.SizeOfInitializedData = mRelocOffset - mDataOffset;
  NtHdr->Pe32.OptionalHeader.SizeOfUninitializedData = 0;
  NtHdr->Pe32.OptionalHeader.AddressOfEntryPoint = CoffEntry;

  NtHdr->Pe32.OptionalHeader.BaseOfCode = mTextOffset;

  NtHdr->Pe32.OptionalHeader.BaseOfData = mDataOffset;
  NtHdr->Pe32.OptionalHeader.ImageBase = 0;
  NtHdr->Pe32.OptionalHeader.SectionAlignment = mCoffAlignment;
  NtHdr->Pe32.OptionalHeader.FileAlignment = mCoffAlignment;
  NtHdr->Pe32.OptionalHeader.SizeOfImage = 0;

  NtHdr->Pe32.OptionalHeader.SizeOfHeaders = mTextOffset;
  NtHdr->Pe32.OptionalHeader.NumberOfRvaAndSizes = EFI_IMAGE_NUMBER_OF_DIRECTORY_ENTRIES;

  //
  // Section headers.
  //
  if ((mDataOffset - mTextOffset) > 0) {
    CreateSectionHeader (".text", mTextOffset, mDataOffset - mTextOffset,
            EFI_IMAGE_SCN_CNT_CODE
            | EFI_IMAGE_SCN_MEM_EXECUTE
            | EFI_IMAGE_SCN_MEM_READ);
  } else {
    // Don't make a section of size 0.
    NtHdr->Pe32.FileHeader.NumberOfSections--;
  }

  if ((mHiiRsrcOffset - mDataOffset) > 0) {
    CreateSectionHeader (".data", mDataOffset, mHiiRsrcOffset - mDataOffset,
            EFI_IMAGE_SCN_CNT_INITIALIZED_DATA
            | EFI_IMAGE_SCN_MEM_WRITE
            | EFI_IMAGE_SCN_MEM_READ);
  } else {
    // Don't make a section of size 0.
    NtHdr->Pe32.FileHeader.NumberOfSections--;
  }

  if ((mRelocOffset - mHiiRsrcOffset) > 0) {
    CreateSectionHeader (".rsrc", mHiiRsrcOffset, mRelocOffset - mHiiRsrcOffset,
            EFI_IMAGE_SCN_CNT_INITIALIZED_DATA
            | EFI_IMAGE_SCN_MEM_READ);

    NtHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_RESOURCE].Size = mRelocOffset - mHiiRsrcOffset;
    NtHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_RESOURCE].VirtualAddress = mHiiRsrcOffset;
  } else {
    // Don't make a section of size 0.
    NtHdr->Pe32.FileHeader.NumberOfSections--;
  }

}

STATIC
BOOLEAN
WriteSections32 (
  SECTION_FILTER_TYPES  FilterType
  )
{
  UINT32      Idx;
  Elf_Shdr    *SecShdr;
  UINT32      SecOffset;
  BOOLEAN     (*Filter)(Elf_Shdr *);

  //
  // Initialize filter pointer
  //
  switch (FilterType) {
    case SECTION_TEXT:
      Filter = IsTextShdr;
      break;
    case SECTION_HII:
      Filter = IsHiiRsrcShdr;
      break;
    case SECTION_DATA:
      Filter = IsDataShdr;
      break;
    default:
      return FALSE;
  }

  //
  // First: copy sections.
  //
  for (Idx = 0; Idx < mEhdr->e_shnum; Idx++) {
    Elf_Shdr *Shdr = GetShdrByIndex(Idx);
    if ((*Filter)(Shdr)) {
      switch (Shdr->sh_type) {
      case SHT_PROGBITS:
        /* Copy.  */
        memcpy(mCoffFile + mCoffSectionsOffset[Idx],
              (UINT8*)mEhdr + Shdr->sh_offset,
              Shdr->sh_size);
        break;

      case SHT_NOBITS:
        memset(mCoffFile + mCoffSectionsOffset[Idx], 0, Shdr->sh_size);
        break;

      default:
        //
        //  Ignore for unkown section type.
        //
        VerboseMsg ("%s unknown section type %x. We directly copy this section into Coff file", mInImageName, (unsigned)Shdr->sh_type);
        break;
      }
    }
  }

  //
  // Second: apply relocations.
  //
  for (Idx = 0; Idx < mEhdr->e_shnum; Idx++) {
    //
    // Determine if this is a relocation section.
    //
    Elf_Shdr *RelShdr = GetShdrByIndex(Idx);
    if ((RelShdr->sh_type != SHT_REL) && (RelShdr->sh_type != SHT_RELA)) {
      continue;
    }
    
    //
    // Relocation section found.  Now extract section information that the relocations
    // apply to in the ELF data and the new COFF data.
    //
    SecShdr = GetShdrByIndex(RelShdr->sh_info);
    SecOffset = mCoffSectionsOffset[RelShdr->sh_info];
    
    //
    // Only process relocations for the current filter type.
    //
    if (RelShdr->sh_type == SHT_REL && (*Filter)(SecShdr)) {
      UINT32 RelOffset;
      
      //
      // Determine the symbol table referenced by the relocation data.
      //
      Elf_Shdr *SymtabShdr = GetShdrByIndex(RelShdr->sh_link);
      UINT8 *Symtab = (UINT8*)mEhdr + SymtabShdr->sh_offset;

      //
      // Process all relocation entries for this section.
      //
      for (RelOffset = 0; RelOffset < RelShdr->sh_size; RelOffset += RelShdr->sh_entsize) {
        //
        // Set pointer to relocation entry
        //
        Elf_Rel *Rel = (Elf_Rel *)((UINT8*)mEhdr + RelShdr->sh_offset + RelOffset);
        
        //
        // Set pointer to symbol table entry associated with the relocation entry.
        //
        Elf_Sym *Sym = (Elf_Sym *)(Symtab + ELF_R_SYM(Rel->r_info) * SymtabShdr->sh_entsize);
        
        Elf_Shdr *SymShdr;
        UINT8 *Targ;
        UINT16 Address;

        //
        // Check section header index found in symbol table and get the section 
        // header location.
        //
        if (Sym->st_shndx == SHN_UNDEF
            || Sym->st_shndx >= mEhdr->e_shnum) {
          const UINT8 *SymName = GetSymName(Sym);
          if (SymName == NULL) {
            SymName = (const UINT8 *)"<unknown>";
          }

          Error (NULL, 0, 3000, "Invalid",
                 "%s: Bad definition for symbol '%s'@%#x or unsupported symbol type.  "
                 "For example, absolute and undefined symbols are not supported.",
                 mInImageName, SymName, Sym->st_value);

          exit(EXIT_FAILURE);
        }
        SymShdr = GetShdrByIndex(Sym->st_shndx);

        //
        // Convert the relocation data to a pointer into the coff file.
        //
        // Note: 
        //   r_offset is the virtual address of the storage unit to be relocated.
        //   sh_addr is the virtual address for the base of the section.
        //
        Targ = mCoffFile + SecOffset + (Rel->r_offset - SecShdr->sh_addr);

        //
        // Determine how to handle each relocation type based on the machine type.
        //
        if (mEhdr->e_machine == EM_386) {
          switch (ELF_R_TYPE(Rel->r_info)) {
          case R_386_NONE:
            break;
          case R_386_32:
            //
            // Absolute relocation.
            //  Converts Targ from a absolute virtual address to the absolute
            //  COFF address.
            //
            *(UINT32 *)Targ = *(UINT32 *)Targ - SymShdr->sh_addr
              + mCoffSectionsOffset[Sym->st_shndx];
            break;
          case R_386_PC32:
            //
            // Relative relocation: Symbol - Ip + Addend
            //
            *(UINT32 *)Targ = *(UINT32 *)Targ
              + (mCoffSectionsOffset[Sym->st_shndx] - SymShdr->sh_addr)
              - (SecOffset - SecShdr->sh_addr);
            break;
          default:
            Error (NULL, 0, 3000, "Invalid", "%s unsupported ELF EM_386 relocation 0x%x.", mInImageName, (unsigned) ELF_R_TYPE(Rel->r_info));
          }
        } else if (mEhdr->e_machine == EM_ARM) {
          switch (ELF32_R_TYPE(Rel->r_info)) {
          case R_ARM_RBASE:
            // No relocation - no action required
            // break skipped

          case R_ARM_PC24:
          case R_ARM_REL32:
          case R_ARM_XPC25:
          case R_ARM_THM_PC22:
          case R_ARM_THM_JUMP19:
          case R_ARM_CALL:
          case R_ARM_JMP24:
          case R_ARM_THM_JUMP24:  
          case R_ARM_PREL31:  
          case R_ARM_MOVW_PREL_NC:  
          case R_ARM_MOVT_PREL:
          case R_ARM_THM_MOVW_PREL_NC:
          case R_ARM_THM_MOVT_PREL:
          case R_ARM_THM_JMP6:
          case R_ARM_THM_ALU_PREL_11_0:
          case R_ARM_THM_PC12:
          case R_ARM_REL32_NOI:
          case R_ARM_ALU_PC_G0_NC:
          case R_ARM_ALU_PC_G0:
          case R_ARM_ALU_PC_G1_NC:
          case R_ARM_ALU_PC_G1:
          case R_ARM_ALU_PC_G2:
          case R_ARM_LDR_PC_G1:
          case R_ARM_LDR_PC_G2:
          case R_ARM_LDRS_PC_G0:
          case R_ARM_LDRS_PC_G1:
          case R_ARM_LDRS_PC_G2:
          case R_ARM_LDC_PC_G0:
          case R_ARM_LDC_PC_G1:
          case R_ARM_LDC_PC_G2:
          case R_ARM_GOT_PREL:
          case R_ARM_THM_JUMP11:
          case R_ARM_THM_JUMP8:
          case R_ARM_TLS_GD32:
          case R_ARM_TLS_LDM32:
          case R_ARM_TLS_IE32:
            // Thease are all PC-relative relocations and don't require modification
            // GCC does not seem to have the concept of a application that just needs to get relocated.
            break;

          case R_ARM_THM_MOVW_ABS_NC:
            // MOVW is only lower 16-bits of the addres
            Address = (UINT16)(Sym->st_value - SymShdr->sh_addr + mCoffSectionsOffset[Sym->st_shndx]);
            ThumbMovtImmediatePatch ((UINT16 *)Targ, Address);
            break;

          case R_ARM_THM_MOVT_ABS:
            // MOVT is only upper 16-bits of the addres
            Address = (UINT16)((Sym->st_value - SymShdr->sh_addr + mCoffSectionsOffset[Sym->st_shndx]) >> 16);
            ThumbMovtImmediatePatch ((UINT16 *)Targ, Address);
            break;

          case R_ARM_ABS32:
          case R_ARM_RABS32:
            //
            // Absolute relocation.
            //
            *(UINT32 *)Targ = *(UINT32 *)Targ - SymShdr->sh_addr + mCoffSectionsOffset[Sym->st_shndx];
            break;

          default:
            Error (NULL, 0, 3000, "Invalid", "WriteSections (): %s unsupported ELF EM_ARM relocation 0x%x.", mInImageName, (unsigned) ELF32_R_TYPE(Rel->r_info));
          }
        }
      }
    }
  }

  return TRUE;
}

UINTN gMovwOffset = 0;

STATIC
VOID
WriteRelocations32 (
  VOID
  )
{
  UINT32                           Index;
  EFI_IMAGE_OPTIONAL_HEADER_UNION  *NtHdr;
  EFI_IMAGE_DATA_DIRECTORY         *Dir;
  BOOLEAN                          FoundRelocations;
  Elf_Dyn                          *Dyn;
  Elf_Rel                          *Rel;
  UINTN                            RelElementSize;
  UINTN                            RelSize;
  UINTN                            RelOffset;
  UINTN                            K;
  Elf32_Phdr                       *DynamicSegment;

  for (Index = 0, FoundRelocations = FALSE; Index < mEhdr->e_shnum; Index++) {
    Elf_Shdr *RelShdr = GetShdrByIndex(Index);
    if ((RelShdr->sh_type == SHT_REL) || (RelShdr->sh_type == SHT_RELA)) {
      Elf_Shdr *SecShdr = GetShdrByIndex (RelShdr->sh_info);
      if (IsTextShdr(SecShdr) || IsDataShdr(SecShdr)) {
        UINT32 RelIdx;

        FoundRelocations = TRUE;
        for (RelIdx = 0; RelIdx < RelShdr->sh_size; RelIdx += RelShdr->sh_entsize) {
          Rel = (Elf_Rel *)((UINT8*)mEhdr + RelShdr->sh_offset + RelIdx);

          if (mEhdr->e_machine == EM_386) { 
            switch (ELF_R_TYPE(Rel->r_info)) {
            case R_386_NONE:
            case R_386_PC32:
              //
              // No fixup entry required.
              //
              break;
            case R_386_32:
              //
              // Creates a relative relocation entry from the absolute entry.
              //
              CoffAddFixup(mCoffSectionsOffset[RelShdr->sh_info]
              + (Rel->r_offset - SecShdr->sh_addr),
              EFI_IMAGE_REL_BASED_HIGHLOW);
              break;
            default:
              Error (NULL, 0, 3000, "Invalid", "%s unsupported ELF EM_386 relocation 0x%x.", mInImageName, (unsigned) ELF_R_TYPE(Rel->r_info));
            }
          } else if (mEhdr->e_machine == EM_ARM) {
            switch (ELF32_R_TYPE(Rel->r_info)) {
            case R_ARM_RBASE:
              // No relocation - no action required
              // break skipped

            case R_ARM_PC24:
            case R_ARM_REL32:
            case R_ARM_XPC25:
            case R_ARM_THM_PC22:
            case R_ARM_THM_JUMP19:
            case R_ARM_CALL:
            case R_ARM_JMP24:
            case R_ARM_THM_JUMP24:  
            case R_ARM_PREL31:  
            case R_ARM_MOVW_PREL_NC:  
            case R_ARM_MOVT_PREL:
            case R_ARM_THM_MOVW_PREL_NC:
            case R_ARM_THM_MOVT_PREL:
            case R_ARM_THM_JMP6:
            case R_ARM_THM_ALU_PREL_11_0:
            case R_ARM_THM_PC12:
            case R_ARM_REL32_NOI:
            case R_ARM_ALU_PC_G0_NC:
            case R_ARM_ALU_PC_G0:
            case R_ARM_ALU_PC_G1_NC:
            case R_ARM_ALU_PC_G1:
            case R_ARM_ALU_PC_G2:
            case R_ARM_LDR_PC_G1:
            case R_ARM_LDR_PC_G2:
            case R_ARM_LDRS_PC_G0:
            case R_ARM_LDRS_PC_G1:
            case R_ARM_LDRS_PC_G2:
            case R_ARM_LDC_PC_G0:
            case R_ARM_LDC_PC_G1:
            case R_ARM_LDC_PC_G2:
            case R_ARM_GOT_PREL:
            case R_ARM_THM_JUMP11:
            case R_ARM_THM_JUMP8:
            case R_ARM_TLS_GD32:
            case R_ARM_TLS_LDM32:
            case R_ARM_TLS_IE32:
              // Thease are all PC-relative relocations and don't require modification
              break;

            case R_ARM_THM_MOVW_ABS_NC:
              CoffAddFixup (
                mCoffSectionsOffset[RelShdr->sh_info]
                + (Rel->r_offset - SecShdr->sh_addr),
                EFI_IMAGE_REL_BASED_ARM_MOV32T
                );

              // PE/COFF treats MOVW/MOVT relocation as single 64-bit instruction
              // Track this address so we can log an error for unsupported sequence of MOVW/MOVT
              gMovwOffset = mCoffSectionsOffset[RelShdr->sh_info] + (Rel->r_offset - SecShdr->sh_addr);
              break;

            case R_ARM_THM_MOVT_ABS:
              if ((gMovwOffset + 4) !=  (mCoffSectionsOffset[RelShdr->sh_info] + (Rel->r_offset - SecShdr->sh_addr))) {
                Error (NULL, 0, 3000, "Not Supported", "PE/COFF requires MOVW+MOVT instruction sequence %x +4 != %x.", gMovwOffset, mCoffSectionsOffset[RelShdr->sh_info] + (Rel->r_offset - SecShdr->sh_addr));
              }
              break;

            case R_ARM_ABS32:
            case R_ARM_RABS32:
              CoffAddFixup (
                mCoffSectionsOffset[RelShdr->sh_info]
                + (Rel->r_offset - SecShdr->sh_addr),
                EFI_IMAGE_REL_BASED_HIGHLOW
                );
              break;

           default:
              Error (NULL, 0, 3000, "Invalid", "WriteRelocations(): %s unsupported ELF EM_ARM relocation 0x%x.", mInImageName, (unsigned) ELF32_R_TYPE(Rel->r_info));
            }
          } else {
            Error (NULL, 0, 3000, "Not Supported", "This tool does not support relocations for ELF with e_machine %u (processor type).", (unsigned) mEhdr->e_machine);
          }
        }
      }
    }
  }

  if (!FoundRelocations && (mEhdr->e_machine == EM_ARM)) {
    /* Try again, but look for PT_DYNAMIC instead of SHT_REL */

    for (Index = 0; Index < mEhdr->e_phnum; Index++) {
      RelElementSize = 0;
      RelSize = 0;
      RelOffset = 0;

      DynamicSegment = GetPhdrByIndex (Index);

      if (DynamicSegment->p_type == PT_DYNAMIC) {
        Dyn = (Elf32_Dyn *) ((UINT8 *)mEhdr + DynamicSegment->p_offset);

        while (Dyn->d_tag != DT_NULL) {
          switch (Dyn->d_tag) {
            case  DT_REL:
              RelOffset = Dyn->d_un.d_val;
              break;

            case  DT_RELSZ:
              RelSize = Dyn->d_un.d_val;
              break;

            case  DT_RELENT:
              RelElementSize = Dyn->d_un.d_val;
              break;

            default:
              break;
          }
          Dyn++;
        }
        if (( RelOffset == 0 ) || ( RelSize == 0 ) || ( RelElementSize == 0 )) {
          Error (NULL, 0, 3000, "Invalid", "%s bad ARM dynamic relocations.", mInImageName);
        }

        for (Index = 0; Index < mEhdr->e_shnum; Index++) {
          Elf_Shdr *shdr = GetShdrByIndex(Index);

          //
          // The PT_DYNAMIC section contains DT_REL relocations whose r_offset
          // field is relative to the base of a segment (or the entire image),
          // and not to the base of an ELF input section as is the case for
          // SHT_REL sections. This means that we cannot fix up such relocations
          // unless we cross-reference ELF sections and segments, considering
          // that the output placement recorded in mCoffSectionsOffset[] is
          // section based, not segment based.
          //
          // Fortunately, there is a simple way around this: we require that the
          // in-memory layout of the ELF and PE/COFF versions of the binary is
          // identical. That way, r_offset will retain its validity as a PE/COFF
          // image offset, and we can record it in the COFF fixup table
          // unmodified.
          //
          if (shdr->sh_addr != mCoffSectionsOffset[Index]) {
            Error (NULL, 0, 3000,
              "Invalid", "%s: PT_DYNAMIC relocations require identical ELF and PE/COFF section offsets.",
              mInImageName);
          }
        }

        for (K = 0; K < RelSize; K += RelElementSize) {

          if (DynamicSegment->p_paddr == 0) {
            // Older versions of the ARM ELF (SWS ESPC 0003 B-02) specification define DT_REL
            // as an offset in the dynamic segment. p_paddr is defined to be zero for ARM tools
            Rel = (Elf32_Rel *) ((UINT8 *) mEhdr + DynamicSegment->p_offset + RelOffset + K);
          } else {
            // This is how it reads in the generic ELF specification
            Rel = (Elf32_Rel *) ((UINT8 *) mEhdr + RelOffset + K);
          }

          switch (ELF32_R_TYPE (Rel->r_info)) {
          case  R_ARM_RBASE:
            break;

          case  R_ARM_RABS32:
            CoffAddFixup (Rel->r_offset, EFI_IMAGE_REL_BASED_HIGHLOW);
            break;
          
          default:
            Error (NULL, 0, 3000, "Invalid", "%s bad ARM dynamic relocations, unkown type %d.", mInImageName, ELF32_R_TYPE (Rel->r_info));
            break;
          }
        }
        break;
      }
    }
  }

  //
  // Pad by adding empty entries.
  //
  while (mCoffOffset & (mCoffAlignment - 1)) {
    CoffAddFixupEntry(0);
  }

  NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)(mCoffFile + mNtHdrOffset);
  Dir = &NtHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_BASERELOC];
  Dir->Size = mCoffOffset - mRelocOffset;
  if (Dir->Size == 0) {
    // If no relocations, null out the directory entry and don't add the .reloc section
    Dir->VirtualAddress = 0;
    NtHdr->Pe32.FileHeader.NumberOfSections--;
  } else {
    Dir->VirtualAddress = mRelocOffset;
    CreateSectionHeader (".reloc", mRelocOffset, mCoffOffset - mRelocOffset,
            EFI_IMAGE_SCN_CNT_INITIALIZED_DATA
            | EFI_IMAGE_SCN_MEM_DISCARDABLE
            | EFI_IMAGE_SCN_MEM_READ);
  }

}

STATIC
VOID
WriteDebug32 (
  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;

  Len = strlen(mInImageName) + 1;

  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 = 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;
  strcpy ((char *)(Nb10 + 1), mInImageName);


  NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)(mCoffFile + mNtHdrOffset);
  DataDir = &NtHdr->Pe32.OptionalHeader.DataDirectory[EFI_IMAGE_DIRECTORY_ENTRY_DEBUG];
  DataDir->VirtualAddress = mDebugOffset;
  DataDir->Size = Dir->SizeOfData + sizeof(EFI_IMAGE_DEBUG_DIRECTORY_ENTRY);
}

STATIC
VOID
SetImageSize32 (
  VOID
  )
{
  EFI_IMAGE_OPTIONAL_HEADER_UNION *NtHdr;
  
  //
  // Set image size
  //
  NtHdr = (EFI_IMAGE_OPTIONAL_HEADER_UNION *)(mCoffFile + mNtHdrOffset);
  NtHdr->Pe32.OptionalHeader.SizeOfImage = mCoffOffset;
}

STATIC
VOID
CleanUp32 (
  VOID
  )
{
  if (mCoffSectionsOffset != NULL) {
    free (mCoffSectionsOffset);
  }
}