/**************************** cof2elf.cpp ********************************
* Author: Agner Fog
* Date created: 2006-07-20
* Last modified: 2008-05-22
* Project: objconv
* Module: cof2elf.cpp
* Description:
* Module for converting PE/COFF file to ELF file
*
* Copyright 2006-2008 GNU General Public License http://www.gnu.org/licenses
*****************************************************************************/
#include "stdafx.h"
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation>
CCOF2ELF<ELFSTRUCTURES>::CCOF2ELF () {
// Constructor
memset(this, 0, sizeof(*this));
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation>
void CCOF2ELF<ELFSTRUCTURES>::Convert() {
// Do the conversion
NumSectionsNew = 5; // Number of sections generated so far
// Allocate variable size buffers
MaxSectionsNew = NumSectionsNew + 2 * NSections; // Max number of sections needed
NewSections.SetNum(MaxSectionsNew); // Allocate buffers for each section
NewSections.SetZero(); // Initialize
NewSectionHeaders.SetNum(MaxSectionsNew); // Allocate array for temporary section headers
NewSectionHeaders.SetZero(); // Initialize
NewSectIndex.SetNum(NSections); // Array for translating old section index (0-based) to new section index
NewSectIndex.SetZero(); // Initialize
NewSymbolIndex.SetNum(NumberOfSymbols); // Array of new symbol indices
NewSymbolIndex.SetZero(); // Initialize
// Call the subfunctions
ToFile.SetFileType(FILETYPE_ELF); // Set type of to file
MakeSegments(); // Make segment headers and code/data segments
MakeSymbolTable(); // Symbol table and string tables
MakeRelocationTables(); // Relocation tables
MakeBinaryFile(); // Putting sections together
*this << ToFile; // Take over new file buffer
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation>
void CCOF2ELF<ELFSTRUCTURES>::MakeSegments() {
// Convert subfunction: Make segment headers and code/data segments
TELF_SectionHeader NewSecHeader; // New section header
int oldsec; // Section index in old file
int newsec; // Section index in new file
uint32 SecNameIndex; // Section name index into shstrtab
char const * SecName; // Name of new section
const int WordSize = sizeof(NewFileHeader.e_entry) * 8; // word size 32 or 64 bits
// Special segment names
static const char * SpecialSegmentNames[] = {
"Null", ".symtab", ".shstrtab", ".strtab", ".stabstr"
};
// Indexes to these are:
symtab = 1; // Symbol table section number
shstrtab = 2; // Section name string table section number
strtab = 3; // Object name string table section number
stabstr = 4; // Debug string table section number
// Number of special segments = number of names in SpecialSegmentNames:
const int NumSpecialSegments = sizeof(SpecialSegmentNames)/sizeof(SpecialSegmentNames[0]);
// Make first section header string table entry empty
NewSections[shstrtab].PushString("");
// Loop through special sections, except the first Null section:
for (newsec = 0; newsec < NumSpecialSegments; newsec++) {
// Put data into new section header:
// Initialize to zero
memset(&NewSecHeader, 0, sizeof(NewSecHeader));
if (newsec > 0) {
// Put name into section header string table
SecName = SpecialSegmentNames[newsec];
SecNameIndex = NewSections[shstrtab].PushString(SecName);
// Put name into new section header
NewSecHeader.sh_name = SecNameIndex;
}
// Put section header into temporary buffer
NewSectionHeaders[newsec] = NewSecHeader;
}
// Put type, flags, etc. into special segments:
NewSectionHeaders[symtab] .sh_type = SHT_SYMTAB;
NewSectionHeaders[symtab] .sh_entsize = sizeof(TELF_Symbol);
NewSectionHeaders[symtab] .sh_link = strtab;
NewSectionHeaders[shstrtab].sh_type = SHT_STRTAB;
NewSectionHeaders[shstrtab].sh_flags = SHF_STRINGS;
NewSectionHeaders[shstrtab].sh_addralign = 1;
NewSectionHeaders[strtab] .sh_type = SHT_STRTAB;
NewSectionHeaders[strtab] .sh_flags = SHF_STRINGS;
NewSectionHeaders[strtab] .sh_addralign = 1;
NewSectionHeaders[stabstr] .sh_type = SHT_STRTAB;
NewSectionHeaders[stabstr] .sh_flags = SHF_STRINGS;
NewSectionHeaders[stabstr] .sh_addralign = 1;
if (newsec != NumSectionsNew) {
// Check my program for internal consistency
// If you get this error then change the value of NumSectionsNew in
// the constructor CCOF2ELF::CCOF2ELF to equal the number of entries in
// SpecialSegmentNames, including the Null segment
err.submit(9000);
}
// Loop through source file sections
for (oldsec = 0; oldsec < this->NSections; oldsec++) {
// Pointer to old section header
SCOFF_SectionHeader * SectionHeader = &this->SectionHeaders[oldsec];
// Get section name
SecName = this->GetSectionName(SectionHeader->Name);
if (strnicmp(SecName,"debug",5) == 0 || strnicmp(SecName+1,"debug",5) == 0) {
// This is a debug section
if (cmd.DebugInfo == CMDL_DEBUG_STRIP) {
// Remove debug info
NewSectIndex[oldsec] = COFF_SECTION_REMOVE_ME; // Remember that this section is removed
cmd.CountDebugRemoved();
continue;
}
else if (cmd.InputType != cmd.OutputType) {
err.submit(1029); // Warn that debug information is incompatible
}
}
if (strnicmp(SecName,".drectve",8) == 0 || (SectionHeader->Flags & (PE_SCN_LNK_INFO | PE_SCN_LNK_REMOVE))) {
// This is a directive section
if (cmd.ExeptionInfo) {
// Remove directive section
NewSectIndex[oldsec] = COFF_SECTION_REMOVE_ME; // Remember that this section is removed
cmd.CountExceptionRemoved();
continue;
}
}
if (strnicmp(SecName,".pdata", 6) == 0) {
// This section has exception information
if (cmd.ExeptionInfo == CMDL_EXCEPTION_STRIP) {
// Remove exception info
NewSectIndex[oldsec] = COFF_SECTION_REMOVE_ME; // Remember that this section is removed
cmd.CountExceptionRemoved();
continue;
}
else if (cmd.InputType != cmd.OutputType) {
err.submit(1030); // Warn that exception information is incompatible
}
}
if (strnicmp(SecName,".cormeta", 8) == 0) {
// This is a .NET Common Language Runtime section
err.submit(2014);
}
if (strnicmp(SecName,".rsrc", 5) == 0) {
// This section has Windows resource information
err.submit(1031);
}
// Store section index in index translation table (zero-based index)
NewSectIndex[oldsec] = newsec;
// Store section data
if (SectionHeader->SizeOfRawData > 0) {
NewSections[newsec].Push(Buf()+SectionHeader->PRawData, SectionHeader->SizeOfRawData);
}
// Put data into new section header:
// Initialize to zero
memset(&NewSecHeader, 0, sizeof(NewSecHeader));
// Section type
if (!(SectionHeader->Flags & PE_SCN_LNK_REMOVE)) {
NewSecHeader.sh_type = SHT_PROGBITS; // Program code or data
NewSecHeader.sh_flags |= SHF_ALLOC; // Occupies memory during execution
}
if (SectionHeader->Flags & PE_SCN_CNT_UNINIT_DATA) {
NewSecHeader.sh_type = SHT_NOBITS; // BSS
}
// Section flags
if (SectionHeader->Flags & PE_SCN_MEM_WRITE) {
NewSecHeader.sh_flags |= SHF_WRITE;
}
if (SectionHeader->Flags & PE_SCN_MEM_EXECUTE) {
NewSecHeader.sh_flags |= SHF_EXECINSTR;
}
// Check for special sections
if (strcmp(SecName, COFF_CONSTRUCTOR_NAME)==0) {
// Constructors segment
SecName = ELF_CONSTRUCTOR_NAME;
NewSecHeader.sh_flags = SHF_WRITE | SHF_ALLOC;
}
// Put name into section header string table
SecNameIndex = NewSections[shstrtab].PushString(SecName);
// Put name into new section header
NewSecHeader.sh_name = SecNameIndex;
// Section virtual memory address
NewSecHeader.sh_addr = SectionHeader->VirtualAddress;
// Section size in memory
NewSecHeader.sh_size = SectionHeader->VirtualSize;
// Section alignment
if (SectionHeader->Flags & PE_SCN_ALIGN_MASK) {
NewSecHeader.sh_addralign = uint32(1 << (((SectionHeader->Flags & PE_SCN_ALIGN_MASK) / PE_SCN_ALIGN_1) - 1));
}
// Put section header into temporary buffer
NewSectionHeaders[newsec] = NewSecHeader;
// Increment section number
newsec++;
if (SectionHeader->NRelocations > 0) {
// Source section has relocations.
// Make a relocation section in destination file
// Put data into relocation section header:
// Initialize to zero
memset(&NewSecHeader, 0, sizeof(NewSecHeader));
// Name for relocation section = ".rel" or ".rela" + name of section
const int MAXSECTIONNAMELENGTH = 256;
char RelocationSectionName[MAXSECTIONNAMELENGTH] = ".rel";
if (WordSize == 64) strcat(RelocationSectionName, "a"); // 32-bit: .rel, 64-bit: .rela
strncat(RelocationSectionName, SecName, MAXSECTIONNAMELENGTH-5);
RelocationSectionName[MAXSECTIONNAMELENGTH-1] = 0;
// Put name into section header string table
uint32 SecNameIndex = NewSections[shstrtab].PushString(RelocationSectionName);
// Put name into new section header
NewSecHeader.sh_name = SecNameIndex;
// Section type
NewSecHeader.sh_type = (WordSize == 32) ? SHT_REL : SHT_RELA; // Relocation section
// Put section header into temporary buffer
NewSectionHeaders[newsec] = NewSecHeader;
// Increment section number
newsec++;
}
}
// Number of sections generated
NumSectionsNew = newsec;
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation>
void CCOF2ELF<ELFSTRUCTURES>::MakeSymbolTable() {
// Convert subfunction: Make symbol table and string tables
int isym; // current symbol table entry
int numaux; // Number of auxiliary entries in source record
int OldSectionIndex; // Index into old section table. 1-based
int NewSectionIndex; // Index into new section table. 0-based
//const int WordSize = sizeof(NewFileHeader.e_entry) * 8; // word size 32 or 64 bits
TELF_Symbol sym; // Temporary symbol table record
const char * name1; // Name of section or main record
// Pointer to old symbol table
union {
SCOFF_SymTableEntry * p; // Symtab entry pointer
int8 * b; // Used for increment
} OldSymtab;
// Make the first record empty
NewSections[symtab].Push(0, sizeof(TELF_Symbol));
// Make first string table entries empty
NewSections[strtab] .PushString("");
NewSections[stabstr].PushString("");
// Loop twice through source symbol table to get local symbols first, global symbols last
// Loop 1: Look for local symbols only
OldSymtab.p = SymbolTable; // Pointer to source symbol table
for (isym = 0; isym < this->NumberOfSymbols; isym += numaux+1, OldSymtab.b += SIZE_SCOFF_SymTableEntry*(numaux+1)) {
if (OldSymtab.b >= Buf() + DataSize) {
err.submit(2040);
break;
}
// Number of auxiliary records belonging to same symbol
numaux = OldSymtab.p->s.NumAuxSymbols; if (numaux < 0) numaux = 0;
if (OldSymtab.p->s.StorageClass != COFF_CLASS_EXTERNAL && OldSymtab.p->s.StorageClass != COFF_CLASS_WEAK_EXTERNAL) {
// Symbol is local
// Reset destination entry
memset(&sym, 0, sizeof(sym));
// Binding
sym.st_bind = STB_LOCAL;
// Get first aux record if numaux > 0
//SCOFF_SymTableEntryAux * sa = (SCOFF_SymTableEntryAux *)(OldSymtab.b + SIZE_SCOFF_SymTableEntry);
// Symbol name
name1 = this->GetSymbolName(OldSymtab.p->s.Name);
// Symbol value
sym.st_value = OldSymtab.p->s.Value;
// Get section
OldSectionIndex = OldSymtab.p->s.SectionNumber; // 1-based index into old section table
NewSectionIndex = 0; // 0-based index into old section table
if (OldSectionIndex > 0 && OldSectionIndex <= this->NSections) {
// Subtract 1 from OldSectionIndex because NewSectIndex[] is zero-based while OldSectionIndex is 1-based
// Get new section index from translation table
NewSectionIndex = NewSectIndex[OldSectionIndex-1];
}
if (NewSectionIndex == COFF_SECTION_REMOVE_ME) {
continue; // Section has been removed. Remove symbol too
}
sym.st_shndx = (uint16)NewSectionIndex;
// Check symbol type
if (OldSymtab.p->s.StorageClass == COFF_CLASS_FILE) {
// This is a filename record
if (numaux > 0 && numaux < 20) {
// Get filename from subsequent Aux records.
// Remove path from filename because the path makes no sense on a different platform.
const char * filename = GetShortFileName(OldSymtab.p);
// Put file name into string table and debug string table
sym.st_name = NewSections[strtab].PushString(filename);
NewSections[stabstr].PushString(filename);
}
// Attributes for filename record
sym.st_shndx = (uint16)SHN_ABS;
sym.st_type = STT_FILE;
sym.st_bind = STB_LOCAL;
sym.st_value = 0;
}
else if (numaux && OldSymtab.p->s.StorageClass == COFF_CLASS_STATIC
&& OldSymtab.p->s.Value == 0 && OldSymtab.p->s.Type != 0x20) {
// This is a section definition record
sym.st_name = 0; name1 = 0;
sym.st_type = STT_SECTION;
sym.st_bind = STB_LOCAL;
sym.st_value = 0;
// aux record contains length and number of relocations. Ignore aux record
}
else if (OldSymtab.p->s.SectionNumber < 0) {
// This is an absolute or debug symbol
sym.st_type = STT_NOTYPE;
sym.st_shndx = (uint16)SHN_ABS;
}
else if (OldSymtab.p->s.Type == 0 && OldSymtab.p->s.StorageClass == COFF_CLASS_FUNCTION) {
// This is a .bf, .lf, or .ef record following a function record
// Contains line number information etc. Ignore this record
continue;
}
else if (OldSymtab.p->s.SectionNumber <= 0) {
// Unknown
sym.st_type = STT_NOTYPE;
}
else {
// This is a local data definition record
sym.st_type = STT_OBJECT;
// The size is not specified in COFF record,
// so we may give it an arbitrary size:
// sym.size = 4;
}
// Put symbol name into string table if we have not already done so
if (sym.st_name == 0 && name1) {
sym.st_name = NewSections[strtab].PushString(name1);
}
// Put record into new symbol table
NewSections[symtab].Push(&sym, sizeof(sym));
// Insert into symbol translation table
NewSymbolIndex[isym] = NewSections[symtab].GetLastIndex();
} // End if not external
} // End loop 1
// Finished with local symbols
// Make index to first global symbol
NewSectionHeaders[symtab].sh_info = NewSections[symtab].GetLastIndex() + 1;
// Loop 2: Look for global symbols only
OldSymtab.p = SymbolTable; // Pointer to source symbol table
for (isym = 0; isym < NumberOfSymbols; isym += numaux+1, OldSymtab.b += SIZE_SCOFF_SymTableEntry*(numaux+1)) {
// Number of auxiliary records belonging to same symbol
numaux = OldSymtab.p->s.NumAuxSymbols; if (numaux < 0) numaux = 0;
if (OldSymtab.p->s.StorageClass == COFF_CLASS_EXTERNAL || OldSymtab.p->s.StorageClass == COFF_CLASS_WEAK_EXTERNAL) {
// Symbol is global (public or external)
// Reset destination entry
memset(&sym, 0, sizeof(sym));
// Binding
sym.st_bind = STB_GLOBAL;
if (OldSymtab.p->s.StorageClass == COFF_CLASS_WEAK_EXTERNAL) sym.st_bind = STB_WEAK;
// Get first aux record if numaux > 0
SCOFF_SymTableEntry * sa = (SCOFF_SymTableEntry*)(OldSymtab.b + SIZE_SCOFF_SymTableEntry);
// Symbol name
name1 = GetSymbolName(OldSymtab.p->s.Name);
// Symbol value
sym.st_value = OldSymtab.p->s.Value;
// Get section
OldSectionIndex = OldSymtab.p->s.SectionNumber; // 1-based index into old section table
NewSectionIndex = 0; // 0-based index into old section table
if (OldSectionIndex > 0 && OldSectionIndex <= NSections) {
// Subtract 1 from OldSectionIndex because NewSectIndex[] is zero-based while OldSectionIndex is 1-based
// Get new section index from translation table
NewSectionIndex = NewSectIndex[OldSectionIndex-1];
}
if (NewSectionIndex == COFF_SECTION_REMOVE_ME) {
continue; // Section has been removed. Remove symbol too
}
if ((int16)OldSectionIndex == COFF_SECTION_ABSOLUTE) {
NewSectionIndex = SHN_ABS;
}
sym.st_shndx = (uint16)NewSectionIndex;
// Check symbol type
if (OldSymtab.p->s.SectionNumber < 0) {
// This is an absolute or debug symbol
sym.st_type = STT_NOTYPE;
}
else if (OldSymtab.p->s.Type == COFF_TYPE_FUNCTION && OldSymtab.p->s.SectionNumber > 0) {
// This is a function definition record
sym.st_type = STT_FUNC;
if (numaux) {
// Get size from aux record
sym.st_size = sa->func.TotalSize;
}
if (sym.st_size == 0) {
// The size is not specified in the COFF file.
// We may give it an arbitrary size:
// sym.size = 1;
}
}
else if (OldSymtab.p->s.SectionNumber <= 0) {
// This is an external symbol
sym.st_type = STT_NOTYPE;
}
else {
// This is a data definition record
sym.st_type = STT_OBJECT;
// Symbol must have a size. The size is not specified in COFF record,
// so we just give it an arbitrary size
sym.st_size = 4;
}
// Put symbol name into string table if we have not already done so
if (sym.st_name == 0 && name1) {
sym.st_name = NewSections[strtab].PushString(name1);
}
// Put record into new symbol table
NewSections[symtab].Push(&sym, sizeof(sym));
// Insert into symbol translation table
NewSymbolIndex[isym] = NewSections[symtab].GetLastIndex();
} // End if external
} // End loop 2
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation>
void CCOF2ELF<ELFSTRUCTURES>::MakeRelocationTables() {
// Convert subfunction: Relocation tables
int32 oldsec; // Relocated section number in source file
int32 newsec; // Relocated section number in destination file
int32 newsecr; // Relocation table section number in destination file
TELF_SectionHeader * NewRelTableSecHeader; // Section header for new relocation table
char TempText[32]; // Temporary text buffer
const int WordSize = sizeof(NewFileHeader.e_entry) * 8; // word size 32 or 64 bits
// Loop through source file sections
for (oldsec = 0; oldsec < NSections; oldsec++) {
// New section index
newsec = NewSectIndex[oldsec];
if (newsec == COFF_SECTION_REMOVE_ME) {
continue; // This is a debug or exception handler section which has been removed
}
// Pointer to old section header
SCOFF_SectionHeader * SectionHeader = &this->SectionHeaders[oldsec];
if (SectionHeader->NRelocations > 0) {
// This section has relocations
// Finc new relocation table section
newsecr = newsec + 1;
// Check that we have allocated a relocation section
if (oldsec+1 < this->NSections && NewSectIndex[oldsec+1] == newsecr) err.submit(9000);
if (newsecr >= NumSectionsNew) err.submit(9000);
// New relocation table section header
NewRelTableSecHeader = &NewSectionHeaders[newsecr];
// Insert header info
NewRelTableSecHeader->sh_type = (WordSize == 32) ? SHT_REL : SHT_RELA;
NewRelTableSecHeader->sh_flags = 0;
NewRelTableSecHeader->sh_addralign = WordSize / 8; // Alignment
NewRelTableSecHeader->sh_link = symtab; // Point to symbol table
NewRelTableSecHeader->sh_info = newsec; // Point to relocated section
// Entry size:
NewRelTableSecHeader->sh_entsize = (WordSize == 32) ? sizeof(Elf32_Rel) : sizeof(Elf64_Rela);
// Pointer to old relocation entry
union {
SCOFF_Relocation * p; // pointer to record
int8 * b; // used for address calculation and incrementing
} OldReloc;
// Loop through relocations
OldReloc.b = Buf() + SectionHeader->PRelocations;
for (int i = 0; i < SectionHeader->NRelocations; i++, OldReloc.b += SIZE_SCOFF_Relocation) {
// Make new relocation entry and set to zero
TELF_Relocation NewRelocEntry;
memset(&NewRelocEntry, 0, sizeof(NewRelocEntry));
// Section offset of relocated address
NewRelocEntry.r_offset = OldReloc.p->VirtualAddress;
// Target symbol
uint32 TargetSymbol = OldReloc.p->SymbolTableIndex;
if (TargetSymbol >= (uint32)NumberOfSymbols) {
err.submit(2031); // Symbol not in table
}
else { // Translate symbol number
NewRelocEntry.r_sym = NewSymbolIndex[TargetSymbol];
}
if (WordSize == 32) {
// Interpret 32-bit COFF relocation types
switch (OldReloc.p->Type) {
case COFF32_RELOC_ABS: // Ignored
NewRelocEntry.r_type = R_386_NONE; break;
case COFF32_RELOC_TOKEN: // .NET common language runtime token
err.submit(2014); // Error message
// Continue in next case and insert absolute address as token:
case COFF32_RELOC_DIR32: // 32-bit absolute virtual address
NewRelocEntry.r_type = R_386_32; break;
case COFF32_RELOC_IMGREL: // 32-bit image relative address
// Image-relative relocation not supported in ELF
if (cmd.OutputType == FILETYPE_MACHO_LE) {
// Intermediate during conversion to MachO
NewRelocEntry.r_type = R_UNSUPPORTED_IMAGEREL;
break;
}
// Work-around unsupported image-relative relocation
// Convert to absolute
NewRelocEntry.r_type = R_386_32; // Absolute relocation
if (cmd.ImageBase == 0) {
// Default image base for 32-bit Linux
cmd.ImageBase = 0x8048000; // 0x400000 ?
}
NewRelocEntry.r_addend -= cmd.ImageBase;
// Warn that image base must be set to the specified value
sprintf(TempText, "%X", cmd.ImageBase); // write value as hexadecimal
err.submit(1301, TempText); err.ClearError(1301);
break;
case COFF32_RELOC_REL32: // 32-bit self-relative
NewRelocEntry.r_type = R_386_PC32;
// Difference between EIP-relative and self-relative relocation = size of address field
NewRelocEntry.r_addend = -4; break;
/* !! error if self-relative relocation with offset
!! test data that fails = testpic32.obj */
case COFF32_RELOC_SECTION: // 16-bit section index in file
case COFF32_RELOC_SECREL: // 32-bit section-relative
case COFF32_RELOC_SECREL7: // 8-bit section-relative
// These fixup types are not supported in ELF files
if (cmd.DebugInfo != CMDL_DEBUG_STRIP) {
// Issue warning. Ignore if stripping debug info
err.submit(1010);
}
break;
default:
err.submit(2030, OldReloc.p->Type); break; // Error: Unknown relocation type (%i) ignored
}
}
else {
// Interpret 64-bit COFF relocation types
switch (OldReloc.p->Type) {
case COFF64_RELOC_ABS: // Ignored
NewRelocEntry.r_type = R_X86_64_NONE; break;
case COFF64_RELOC_TOKEN: // .NET common language runtime token
err.submit(2014); // Error message
// Continue in next case and insert absolute address as token:
case COFF64_RELOC_ABS64: // 64 bit absolute virtual address
NewRelocEntry.r_type = R_X86_64_64; break;
case COFF64_RELOC_PPC_TOKEN:
err.submit(2014); // Error message
// Continue in next case and insert absolute address as token:
case COFF64_RELOC_ABS32: // 32 bit absolute address
NewRelocEntry.r_type = R_X86_64_32S; break;
case COFF64_RELOC_IMGREL: // 32 bit image-relative
// Image-relative relocation not supported in ELF
if (cmd.OutputType == FILETYPE_MACHO_LE) {
// Intermediate during conversion to MachO
NewRelocEntry.r_type = R_UNSUPPORTED_IMAGEREL;
break;
}
// Work-around unsupported image-relative relocation
// Convert to absolute
NewRelocEntry.r_type = R_X86_64_32S; // Absolute 32-bit relocation
if (cmd.ImageBase == 0) {
// Default image base for 64-bit Linux
cmd.ImageBase = 0x400000;
}
NewRelocEntry.r_addend -= cmd.ImageBase;
// Warn that image base must be set to the specified value
sprintf(TempText, "%X", cmd.ImageBase); // write value as hexadecimal
err.submit(1301, TempText); err.ClearError(1301);
break;
case COFF64_RELOC_REL32: // 32 bit, RIP-relative
case COFF64_RELOC_REL32_1: // 32 bit, relative to RIP - 1. For instruction with immediate byte operand
case COFF64_RELOC_REL32_2: // 32 bit, relative to RIP - 2. For instruction with immediate word operand
case COFF64_RELOC_REL32_3: // 32 bit, relative to RIP - 3. (useless)
case COFF64_RELOC_REL32_4: // 32 bit, relative to RIP - 4. For instruction with immediate dword operand
case COFF64_RELOC_REL32_5: // 32 bit, relative to RIP - 5. (useless)
NewRelocEntry.r_type = R_X86_64_PC32;
// Note:
// The microprocessor calculates RIP-relative addresses
// relative to the value of the instruction pointer AFTER
// the instruction. This is equal to the address of the
// relocated field plus the size of the relocated field
// itself plus the size of any immediate operand coming
// after the relocated field.
// The COFF format makes the correction for this offset in
// the linker by using a differet relocation type for
// immediate operand size = 0, 1, 2 or 4.
// The ELF format makes the same correction by an explicit
// addend, which is -4, -5, -6 or -8, respectively.
// The difference between RIP-relative and self-relative
// relocation is equal to the size of the address field plus
// the size of any immediate operand:
NewRelocEntry.r_addend = -(4 + OldReloc.p->Type - COFF64_RELOC_REL32);
break;
case COFF64_RELOC_SECTION: // 16-bit section index in file
case COFF64_RELOC_SECREL: // 32-bit section-relative
case COFF64_RELOC_SECREL7: // 8-bit section-relative
// These fixup types are not supported in ELF files
if (cmd.DebugInfo != CMDL_DEBUG_STRIP) {
// Issue warning. Ignore if stripping debug info
err.submit(1010);
}
break;
default:
err.submit(2030, OldReloc.p->Type); break; // Error: Unknown relocation type (%i) ignored
}
}
// Find inline addend
int32 * paddend = 0;
if (OldReloc.p->VirtualAddress + 4 > NewSections[newsec].GetDataSize()
|| NewSectionHeaders[newsec].sh_type == SHT_NOBITS) {
// Address of relocation is invalid
err.submit(2032);
}
else {
// Make pointer to inline addend
paddend = (int32*)(NewSections[newsec].Buf()
+ NewSectionHeaders[newsec].sh_offset + OldReloc.p->VirtualAddress);
}
// Put relocation record into table
if (WordSize == 32) {
if (NewRelocEntry.r_addend != 0) {
// Use inline addends in 32 bit ELF (SHT_REL)
// Put addend inline
* paddend += uint32(NewRelocEntry.r_addend);
NewRelocEntry.r_addend = 0;
}
// Save 32-bit relocation record Elf32_Rel, not Elf32_Rela
if (NewRelocEntry.r_addend) err.submit(9000);
NewSections[newsecr].Push(&NewRelocEntry, sizeof(Elf32_Rel));
}
else {
// 64 bit
/*
if (*paddend != 0) {
// Use explicit addend in 64 bit ELF (SHT_RELA)
// Explicit addend may cause link error if it appears to point outside section
NewRelocEntry.r_addend += *paddend;
*paddend = 0;
}*/
// Save 64-bit relocation record. Must be Elf64_Rela
NewSections[newsecr].Push(&NewRelocEntry, sizeof(Elf64_Rela));
}
}
}
}
}
template <class TELF_Header, class TELF_SectionHeader, class TELF_Symbol, class TELF_Relocation>
void CCOF2ELF<ELFSTRUCTURES>::MakeBinaryFile() {
// Convert subfunction: Make section headers and file header,
// and combine everything into a single memory buffer.
int32 newsec; // Section index
uint32 SecOffset; // Section offset in file
uint32 SecSize; // Section size in file
uint32 SectionHeaderOffset; // File offset to section headers
// Set file type in ToFile
ToFile.SetFileType(FILETYPE_ELF);
// Make space for file header in ToFile, but don't fill data into it yet
ToFile.Push(0, sizeof(TELF_Header));
// Loop through new section buffers
for (newsec = 0; newsec < NumSectionsNew; newsec++) {
// Size of section
SecSize = NewSections[newsec].GetDataSize();
// Put section into ToFile
SecOffset = ToFile.Push(NewSections[newsec].Buf(), SecSize);
// Put size and offset into section header
NewSectionHeaders[newsec].sh_offset = SecOffset;
NewSectionHeaders[newsec].sh_size = SecSize;
// Align before next entry
ToFile.Align(16);
}
// Start offset of section headers
SectionHeaderOffset = ToFile.GetDataSize();
// Loop through new section headers
for (newsec = 0; newsec < NumSectionsNew; newsec++) {
// Put section header into ToFile
ToFile.Push(&NewSectionHeaders[newsec], sizeof(TELF_SectionHeader));
}
// Make file header
TELF_Header FileHeader;
memset(&FileHeader, 0, sizeof(FileHeader)); // Initialize to 0
// Put file type magic number in
strcpy((char*)(FileHeader.e_ident), ELFMAG);
// File class
FileHeader.e_ident[EI_CLASS] = (WordSize == 32) ? ELFCLASS32 : ELFCLASS64;
// Data Endian-ness
FileHeader.e_ident[EI_DATA] = ELFDATA2LSB;
// ELF version
FileHeader.e_ident[EI_VERSION] = EV_CURRENT;
// ABI
FileHeader.e_ident[EI_OSABI] = ELFOSABI_SYSV;
// ABI version
FileHeader.e_ident[EI_ABIVERSION] = 0;
// File type
FileHeader.e_type = ET_REL;
// Machine architecture
FileHeader.e_machine = (WordSize == 32) ? EM_386 : EM_X86_64;
// Version
FileHeader.e_version = EV_CURRENT;
// Flags
FileHeader.e_flags = 0;
// Section header table offset
FileHeader.e_shoff = SectionHeaderOffset;
// File header size
FileHeader.e_ehsize = sizeof(TELF_Header);
// Section header size
FileHeader.e_shentsize = sizeof(TELF_SectionHeader);
// Number of section headers
FileHeader.e_shnum = (uint16)NumSectionsNew;
// Section header string table index
FileHeader.e_shstrndx = (uint16)shstrtab;
// Put file header into beginning of ToFile where we made space for it
memcpy(ToFile.Buf(), &FileHeader, sizeof(FileHeader));
}
// Make template instances for 32 and 64 bits
template class CCOF2ELF<ELF32STRUCTURES>;
template class CCOF2ELF<ELF64STRUCTURES>;