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llvm-project/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp

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//===- lib/ReaderWriter/PECOFF/WriterPECOFF.cpp ---------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
///
/// PE/COFF file consists of DOS Header, PE Header, COFF Header and Section
/// Tables followed by raw section data.
///
/// This writer is responsible for writing Core Linker results to an Windows
/// executable file.
///
/// This writer currently supports 32 bit PE/COFF for x86 processor only.
///
//===----------------------------------------------------------------------===//
#include "Atoms.h"
#include "WriterImportLibrary.h"
#include "lld/Core/DefinedAtom.h"
#include "lld/Core/File.h"
#include "lld/Core/Writer.h"
#include "lld/ReaderWriter/AtomLayout.h"
#include "lld/ReaderWriter/PECOFFLinkingContext.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Object/COFF.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/Format.h"
#include <algorithm>
#include <cstdlib>
#include <map>
#include <time.h>
#include <vector>
#define DEBUG_TYPE "WriterPECOFF"
using namespace llvm::support::endian;
using llvm::COFF::DataDirectoryIndex;
using llvm::object::coff_runtime_function_x64;
using llvm::support::ulittle16_t;
using llvm::support::ulittle32_t;
using llvm::support::ulittle64_t;
namespace lld {
namespace pecoff {
// Disk sector size. Some data needs to be aligned at disk sector boundary in
// file.
static const int SECTOR_SIZE = 512;
namespace {
class SectionChunk;
/// A Chunk is an abstract contiguous range in an output file.
class Chunk {
public:
enum Kind {
kindHeader,
kindSection,
kindStringTable,
kindAtomChunk
};
explicit Chunk(Kind kind) : _kind(kind), _size(0) {}
virtual ~Chunk() {}
virtual void write(uint8_t *buffer) = 0;
virtual uint64_t size() const { return _size; }
virtual uint64_t onDiskSize() const { return size(); }
virtual uint64_t align() const { return 1; }
uint64_t fileOffset() const { return _fileOffset; }
void setFileOffset(uint64_t fileOffset) { _fileOffset = fileOffset; }
Kind getKind() const { return _kind; }
protected:
Kind _kind;
uint64_t _size;
uint64_t _fileOffset;
};
/// A HeaderChunk is an abstract class to represent a file header for
/// PE/COFF. The data in the header chunk is metadata about program and will
/// be consumed by the windows loader. HeaderChunks are not mapped to memory
/// when executed.
class HeaderChunk : public Chunk {
public:
HeaderChunk() : Chunk(kindHeader) {}
static bool classof(const Chunk *c) { return c->getKind() == kindHeader; }
};
/// A DOSStubChunk represents the DOS compatible header at the beginning
/// of PE/COFF files.
class DOSStubChunk : public HeaderChunk {
public:
explicit DOSStubChunk(const PECOFFLinkingContext &ctx)
: HeaderChunk(), _ctx(ctx) {
// Minimum size of DOS stub is 64 bytes. The next block (PE header) needs to
// be aligned on 8 byte boundary.
size_t size = std::max(_ctx.getDosStub().size(), (size_t)64);
_size = llvm::RoundUpToAlignment(size, 8);
}
void write(uint8_t *buffer) override {
ArrayRef<uint8_t> array = _ctx.getDosStub();
std::memcpy(buffer, array.data(), array.size());
auto *header = reinterpret_cast<llvm::object::dos_header *>(buffer);
header->AddressOfRelocationTable = sizeof(llvm::object::dos_header);
header->AddressOfNewExeHeader = _size;
}
private:
const PECOFFLinkingContext &_ctx;
};
/// A PEHeaderChunk represents PE header including COFF header.
template <class PEHeader>
class PEHeaderChunk : public HeaderChunk {
public:
explicit PEHeaderChunk(const PECOFFLinkingContext &ctx);
void write(uint8_t *buffer) override;
void setSizeOfHeaders(uint64_t size) {
// Must be multiple of FileAlignment.
_peHeader.SizeOfHeaders = llvm::RoundUpToAlignment(size, SECTOR_SIZE);
}
void setSizeOfCode(uint64_t size) { _peHeader.SizeOfCode = size; }
void setBaseOfCode(uint32_t rva) { _peHeader.BaseOfCode = rva; }
void setBaseOfData(uint32_t rva);
void setSizeOfImage(uint32_t size) { _peHeader.SizeOfImage = size; }
void setSizeOfInitializedData(uint64_t size) {
_peHeader.SizeOfInitializedData = size;
}
void setSizeOfUninitializedData(uint64_t size) {
_peHeader.SizeOfUninitializedData = size;
}
void setNumberOfSections(uint32_t num) { _coffHeader.NumberOfSections = num; }
void setNumberOfSymbols(uint32_t num) { _coffHeader.NumberOfSymbols = num; }
void setAddressOfEntryPoint(uint32_t address) {
_peHeader.AddressOfEntryPoint = address;
}
void setPointerToSymbolTable(uint32_t rva) {
_coffHeader.PointerToSymbolTable = rva;
}
private:
llvm::object::coff_file_header _coffHeader;
PEHeader _peHeader;
};
/// A SectionHeaderTableChunk represents Section Table Header of PE/COFF
/// format, which is a list of section headers.
class SectionHeaderTableChunk : public HeaderChunk {
public:
SectionHeaderTableChunk() : HeaderChunk() {}
void addSection(SectionChunk *chunk);
uint64_t size() const override;
void write(uint8_t *buffer) override;
private:
static llvm::object::coff_section createSectionHeader(SectionChunk *chunk);
std::vector<SectionChunk *> _sections;
};
class StringTableChunk : public Chunk {
public:
StringTableChunk() : Chunk(kindStringTable) {}
static bool classof(const Chunk *c) {
return c->getKind() == kindStringTable;
}
uint32_t addSectionName(StringRef sectionName) {
if (_stringTable.empty()) {
// The string table immediately follows the symbol table.
// We don't really need a symbol table, but some tools (e.g. dumpbin)
// don't like zero-length symbol table.
// Make room for the empty symbol slot, which occupies 18 byte.
// We also need to reserve 4 bytes for the string table header.
int size = sizeof(llvm::object::coff_symbol16) + 4;
_stringTable.insert(_stringTable.begin(), size, 0);
// Set the name of the dummy symbol to the first string table entry.
// It's better than letting dumpbin print out a garabage as a symbol name.
char *off = _stringTable.data() + 4;
write32le(off, 4);
}
uint32_t offset = _stringTable.size();
_stringTable.insert(_stringTable.end(), sectionName.begin(),
sectionName.end());
_stringTable.push_back('\0');
return offset - sizeof(llvm::object::coff_symbol16);
}
uint64_t size() const override { return _stringTable.size(); }
void write(uint8_t *buffer) override {
if (_stringTable.empty())
return;
char *off = _stringTable.data() + sizeof(llvm::object::coff_symbol16);
write32le(off, _stringTable.size());
std::memcpy(buffer, _stringTable.data(), _stringTable.size());
}
private:
std::vector<char> _stringTable;
};
class SectionChunk : public Chunk {
public:
uint64_t onDiskSize() const override {
if (_characteristics & llvm::COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)
return 0;
return llvm::RoundUpToAlignment(size(), SECTOR_SIZE);
}
uint64_t align() const override { return SECTOR_SIZE; }
uint32_t getCharacteristics() const { return _characteristics; }
StringRef getSectionName() const { return _sectionName; }
virtual uint64_t memAlign() const { return _memAlign; }
static bool classof(const Chunk *c) {
Kind kind = c->getKind();
return kind == kindSection || kind == kindAtomChunk;
}
uint64_t getVirtualAddress() { return _virtualAddress; }
virtual void setVirtualAddress(uint32_t rva) { _virtualAddress = rva; }
uint32_t getStringTableOffset() const { return _stringTableOffset; }
void setStringTableOffset(uint32_t offset) { _stringTableOffset = offset; }
protected:
SectionChunk(Kind kind, StringRef sectionName, uint32_t characteristics,
const PECOFFLinkingContext &ctx)
: Chunk(kind), _sectionName(sectionName),
_characteristics(characteristics), _virtualAddress(0),
_stringTableOffset(0), _memAlign(ctx.getPageSize()) {}
private:
StringRef _sectionName;
const uint32_t _characteristics;
uint64_t _virtualAddress;
uint32_t _stringTableOffset;
uint64_t _memAlign;
};
struct BaseReloc {
BaseReloc(uint64_t a, llvm::COFF::BaseRelocationType t) : addr(a), type(t) {}
uint64_t addr;
llvm::COFF::BaseRelocationType type;
};
/// An AtomChunk represents a section containing atoms.
class AtomChunk : public SectionChunk {
public:
AtomChunk(const PECOFFLinkingContext &ctx, StringRef name,
const std::vector<const DefinedAtom *> &atoms);
void write(uint8_t *buffer) override;
uint64_t memAlign() const override;
void appendAtom(const DefinedAtom *atom);
void buildAtomRvaMap(std::map<const Atom *, uint64_t> &atomRva) const;
void applyRelocationsARM(uint8_t *buffer,
std::map<const Atom *, uint64_t> &atomRva,
std::vector<uint64_t> &sectionRva,
uint64_t imageBaseAddress);
void applyRelocationsX86(uint8_t *buffer,
std::map<const Atom *, uint64_t> &atomRva,
std::vector<uint64_t> &sectionRva,
uint64_t imageBaseAddress);
void applyRelocationsX64(uint8_t *buffer,
std::map<const Atom *, uint64_t> &atomRva,
std::vector<uint64_t> &sectionRva,
uint64_t imageBaseAddress);
void printAtomAddresses(uint64_t baseAddr) const;
void addBaseRelocations(std::vector<BaseReloc> &relocSites) const;
void setVirtualAddress(uint32_t rva) override;
uint64_t getAtomVirtualAddress(StringRef name) const;
static bool classof(const Chunk *c) { return c->getKind() == kindAtomChunk; }
protected:
std::vector<AtomLayout *> _atomLayouts;
uint64_t _virtualAddress;
private:
uint32_t
computeCharacteristics(const PECOFFLinkingContext &ctx, StringRef name,
const std::vector<const DefinedAtom *> &atoms) const {
return ctx.getSectionAttributes(name,
getDefaultCharacteristics(name, atoms));
}
uint32_t getDefaultCharacteristics(
StringRef name, const std::vector<const DefinedAtom *> &atoms) const;
mutable llvm::BumpPtrAllocator _alloc;
llvm::COFF::MachineTypes _machineType;
const PECOFFLinkingContext &_ctx;
};
/// A DataDirectoryChunk represents data directory entries that follows the PE
/// header in the output file. An entry consists of an 8 byte field that
/// indicates a relative virtual address (the starting address of the entry data
/// in memory) and 8 byte entry data size.
class DataDirectoryChunk : public HeaderChunk {
public:
DataDirectoryChunk()
: HeaderChunk(), _data(std::vector<llvm::object::data_directory>(16)) {}
uint64_t size() const override {
return sizeof(llvm::object::data_directory) * _data.size();
}
void setField(DataDirectoryIndex index, uint32_t addr, uint32_t size);
void write(uint8_t *buffer) override;
private:
std::vector<llvm::object::data_directory> _data;
};
/// A BaseRelocChunk represents ".reloc" section.
///
/// .reloc section contains a list of addresses. If the PE/COFF loader decides
/// to load the binary at a memory address different from its preferred base
/// address, which is specified by ImageBase field in the COFF header, the
/// loader needs to relocate the binary, so that all the addresses in the binary
/// point to new locations. The loader will do that by fixing up the addresses
/// specified by .reloc section.
///
/// The executable is almost always loaded at the preferred base address because
/// it's loaded into an empty address space. The DLL is however an subject of
/// load-time relocation because it may conflict with other DLLs or the
/// executable.
class BaseRelocChunk : public SectionChunk {
typedef std::vector<std::unique_ptr<Chunk> > ChunkVectorT;
public:
BaseRelocChunk(ChunkVectorT &chunks, const PECOFFLinkingContext &ctx)
: SectionChunk(kindSection, ".reloc", characteristics, ctx),
_ctx(ctx), _contents(createContents(chunks)) {}
void write(uint8_t *buffer) override {
std::memcpy(buffer, &_contents[0], _contents.size());
}
uint64_t size() const override { return _contents.size(); }
private:
// When loaded into memory, reloc section should be readable and writable.
static const uint32_t characteristics =
llvm::COFF::IMAGE_SCN_MEM_READ |
llvm::COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
llvm::COFF::IMAGE_SCN_MEM_DISCARDABLE;
std::vector<uint8_t> createContents(ChunkVectorT &chunks) const;
// Returns a list of RVAs that needs to be relocated if the binary is loaded
// at an address different from its preferred one.
std::vector<BaseReloc> listRelocSites(ChunkVectorT &chunks) const;
// Create the content of a relocation block.
std::vector<uint8_t>
createBaseRelocBlock(uint64_t pageAddr, const BaseReloc *begin,
const BaseReloc *end) const;
const PECOFFLinkingContext &_ctx;
std::vector<uint8_t> _contents;
};
template <class PEHeader>
PEHeaderChunk<PEHeader>::PEHeaderChunk(const PECOFFLinkingContext &ctx)
: HeaderChunk() {
// Set the size of the chunk and initialize the header with null bytes.
_size = sizeof(llvm::COFF::PEMagic) + sizeof(_coffHeader) + sizeof(_peHeader);
std::memset(&_coffHeader, 0, sizeof(_coffHeader));
std::memset(&_peHeader, 0, sizeof(_peHeader));
_coffHeader.Machine = ctx.getMachineType();
_coffHeader.TimeDateStamp = time(nullptr);
// Attributes of the executable.
uint16_t characteristics = llvm::COFF::IMAGE_FILE_EXECUTABLE_IMAGE;
if (!ctx.is64Bit())
characteristics |= llvm::COFF::IMAGE_FILE_32BIT_MACHINE;
if (ctx.isDll())
characteristics |= llvm::COFF::IMAGE_FILE_DLL;
if (ctx.getLargeAddressAware() || ctx.is64Bit())
characteristics |= llvm::COFF::IMAGE_FILE_LARGE_ADDRESS_AWARE;
if (ctx.getSwapRunFromCD())
characteristics |= llvm::COFF::IMAGE_FILE_REMOVABLE_RUN_FROM_SWAP;
if (ctx.getSwapRunFromNet())
characteristics |= llvm::COFF::IMAGE_FILE_NET_RUN_FROM_SWAP;
if (!ctx.getBaseRelocationEnabled())
characteristics |= llvm::COFF::IMAGE_FILE_RELOCS_STRIPPED;
_coffHeader.Characteristics = characteristics;
_peHeader.Magic = ctx.is64Bit() ? llvm::COFF::PE32Header::PE32_PLUS
: llvm::COFF::PE32Header::PE32;
// The address of the executable when loaded into memory. The default for
// DLLs is 0x10000000. The default for executables is 0x400000.
_peHeader.ImageBase = ctx.getBaseAddress();
// Sections should be page-aligned when loaded into memory, which is 4KB on
// x86.
_peHeader.SectionAlignment = ctx.getSectionDefaultAlignment();
// Sections in an executable file on disk should be sector-aligned (512 byte).
_peHeader.FileAlignment = SECTOR_SIZE;
// The version number of the resultant executable/DLL. The number is purely
// informative, and neither the linker nor the loader won't use it. User can
// set the value using /version command line option. Default is 0.0.
PECOFFLinkingContext::Version imageVersion = ctx.getImageVersion();
_peHeader.MajorImageVersion = imageVersion.majorVersion;
_peHeader.MinorImageVersion = imageVersion.minorVersion;
// The required Windows version number. This is the internal version and
// shouldn't be confused with product name. Windows 7 is version 6.1 and
// Windows 8 is 6.2, for example.
PECOFFLinkingContext::Version minOSVersion = ctx.getMinOSVersion();
_peHeader.MajorOperatingSystemVersion = minOSVersion.majorVersion;
_peHeader.MinorOperatingSystemVersion = minOSVersion.minorVersion;
_peHeader.MajorSubsystemVersion = minOSVersion.majorVersion;
_peHeader.MinorSubsystemVersion = minOSVersion.minorVersion;
_peHeader.Subsystem = ctx.getSubsystem();
// Despite its name, DLL characteristics field has meaning both for
// executables and DLLs. We are not very sure if the following bits must
// be set, but regular binaries seem to have these bits, so we follow
// them.
uint16_t dllCharacteristics = 0;
if (ctx.noSEH())
dllCharacteristics |= llvm::COFF::IMAGE_DLL_CHARACTERISTICS_NO_SEH;
if (ctx.isTerminalServerAware())
dllCharacteristics |=
llvm::COFF::IMAGE_DLL_CHARACTERISTICS_TERMINAL_SERVER_AWARE;
if (ctx.isNxCompat())
dllCharacteristics |= llvm::COFF::IMAGE_DLL_CHARACTERISTICS_NX_COMPAT;
if (ctx.getDynamicBaseEnabled())
dllCharacteristics |= llvm::COFF::IMAGE_DLL_CHARACTERISTICS_DYNAMIC_BASE;
if (!ctx.getAllowBind())
dllCharacteristics |= llvm::COFF::IMAGE_DLL_CHARACTERISTICS_NO_BIND;
if (!ctx.getAllowIsolation())
dllCharacteristics |= llvm::COFF::IMAGE_DLL_CHARACTERISTICS_NO_ISOLATION;
if (ctx.getHighEntropyVA() && ctx.is64Bit())
dllCharacteristics |= llvm::COFF::IMAGE_DLL_CHARACTERISTICS_HIGH_ENTROPY_VA;
_peHeader.DLLCharacteristics = dllCharacteristics;
_peHeader.SizeOfStackReserve = ctx.getStackReserve();
_peHeader.SizeOfStackCommit = ctx.getStackCommit();
_peHeader.SizeOfHeapReserve = ctx.getHeapReserve();
_peHeader.SizeOfHeapCommit = ctx.getHeapCommit();
// The number of data directory entries. We always have 16 entries.
_peHeader.NumberOfRvaAndSize = 16;
// The size of PE header including optional data directory.
_coffHeader.SizeOfOptionalHeader = sizeof(PEHeader) +
_peHeader.NumberOfRvaAndSize * sizeof(llvm::object::data_directory);
}
template <>
void PEHeaderChunk<llvm::object::pe32_header>::setBaseOfData(uint32_t rva) {
_peHeader.BaseOfData = rva;
}
template <>
void PEHeaderChunk<llvm::object::pe32plus_header>::setBaseOfData(uint32_t rva) {
// BaseOfData field does not exist in PE32+ header.
}
template <class PEHeader>
void PEHeaderChunk<PEHeader>::write(uint8_t *buffer) {
std::memcpy(buffer, llvm::COFF::PEMagic, sizeof(llvm::COFF::PEMagic));
buffer += sizeof(llvm::COFF::PEMagic);
std::memcpy(buffer, &_coffHeader, sizeof(_coffHeader));
buffer += sizeof(_coffHeader);
std::memcpy(buffer, &_peHeader, sizeof(_peHeader));
}
AtomChunk::AtomChunk(const PECOFFLinkingContext &ctx, StringRef sectionName,
const std::vector<const DefinedAtom *> &atoms)
: SectionChunk(kindAtomChunk, sectionName,
computeCharacteristics(ctx, sectionName, atoms), ctx),
_virtualAddress(0), _machineType(ctx.getMachineType()), _ctx(ctx) {
for (auto *a : atoms)
appendAtom(a);
}
void AtomChunk::write(uint8_t *buffer) {
if (_atomLayouts.empty())
return;
if (getCharacteristics() & llvm::COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)
return;
if (getCharacteristics() & llvm::COFF::IMAGE_SCN_CNT_CODE) {
// Fill the section with INT 3 (0xCC) rather than NUL, so that the
// disassembler will not interpret a garbage between atoms as the beginning
// of multi-byte machine code. This does not change the behavior of
// resulting binary but help debugging.
uint8_t *start = buffer + _atomLayouts.front()->_fileOffset;
uint8_t *end = buffer + _atomLayouts.back()->_fileOffset;
memset(start, 0xCC, end - start);
}
for (const auto *layout : _atomLayouts) {
const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
ArrayRef<uint8_t> rawContent = atom->rawContent();
std::memcpy(buffer + layout->_fileOffset, rawContent.data(),
rawContent.size());
}
}
// Add all atoms to the given map. This data will be used to do relocation.
void
AtomChunk::buildAtomRvaMap(std::map<const Atom *, uint64_t> &atomRva) const {
for (const auto *layout : _atomLayouts)
atomRva[layout->_atom] = layout->_virtualAddr;
}
static int getSectionIndex(uint64_t targetAddr,
const std::vector<uint64_t> &sectionRva) {
int i = 1;
for (uint64_t rva : sectionRva) {
if (targetAddr < rva)
return i;
++i;
}
return i;
}
static uint32_t getSectionStartAddr(uint64_t targetAddr,
const std::vector<uint64_t> &sectionRva) {
// Scan the list of section start addresses to find the section start address
// for the given RVA.
for (int i = 0, e = sectionRva.size(); i < e; ++i)
if (i == e - 1 || (sectionRva[i] <= targetAddr && targetAddr < sectionRva[i + 1]))
return sectionRva[i];
llvm_unreachable("Section missing");
}
static void applyThumbMoveImmediate(ulittle16_t *mov, uint16_t imm) {
// MOVW(T3): |11110|i|10|0|1|0|0|imm4|0|imm3|Rd|imm8|
// imm32 = zext imm4:i:imm3:imm8
// MOVT(T1): |11110|i|10|1|1|0|0|imm4|0|imm3|Rd|imm8|
// imm16 = imm4:i:imm3:imm8
mov[0] =
mov[0] | (((imm & 0x0800) >> 11) << 10) | (((imm & 0xf000) >> 12) << 0);
mov[1] =
mov[1] | (((imm & 0x0700) >> 8) << 12) | (((imm & 0x00ff) >> 0) << 0);
}
static void applyThumbBranchImmediate(ulittle16_t *bl, int32_t imm) {
// BL(T1): |11110|S|imm10|11|J1|1|J2|imm11|
// imm32 = sext S:I1:I2:imm10:imm11:'0'
// B.W(T4): |11110|S|imm10|10|J1|1|J2|imm11|
// imm32 = sext S:I1:I2:imm10:imm11:'0'
//
// I1 = ~(J1 ^ S), I2 = ~(J2 ^ S)
assert((~abs(imm) & (-1 << 24)) && "bl/b.w out of range");
uint32_t S = (imm < 0 ? 1 : 0);
uint32_t J1 = ((~imm & 0x00800000) >> 23) ^ S;
uint32_t J2 = ((~imm & 0x00400000) >> 22) ^ S;
bl[0] = bl[0] | (((imm & 0x003ff000) >> 12) << 0) | (S << 10);
bl[1] = bl[1] | (((imm & 0x00000ffe) >> 1) << 0) | (J2 << 11) | (J1 << 13);
}
void AtomChunk::applyRelocationsARM(uint8_t *Buffer,
std::map<const Atom *, uint64_t> &AtomRVA,
std::vector<uint64_t> &SectionRVA,
uint64_t ImageBase) {
Buffer = Buffer + _fileOffset;
parallel_for_each(_atomLayouts.begin(), _atomLayouts.end(),
[&](const AtomLayout *layout) {
const DefinedAtom *Atom = cast<DefinedAtom>(layout->_atom);
for (const Reference *R : *Atom) {
if (R->kindNamespace() != Reference::KindNamespace::COFF)
continue;
bool AssumeTHUMBCode = false;
if (auto Target = dyn_cast<DefinedAtom>(R->target()))
AssumeTHUMBCode = Target->permissions() == DefinedAtom::permR_X ||
Target->permissions() == DefinedAtom::permRWX;
const auto AtomOffset = R->offsetInAtom();
const auto FileOffset = layout->_fileOffset;
const auto TargetAddr = AtomRVA[R->target()] | (AssumeTHUMBCode ? 1 : 0);
auto RelocSite16 =
reinterpret_cast<ulittle16_t *>(Buffer + FileOffset + AtomOffset);
auto RelocSite32 =
reinterpret_cast<ulittle32_t *>(Buffer + FileOffset + AtomOffset);
switch (R->kindValue()) {
default: llvm_unreachable("unsupported relocation type");
case llvm::COFF::IMAGE_REL_ARM_ADDR32:
*RelocSite32 = *RelocSite32 + TargetAddr + ImageBase;
break;
case llvm::COFF::IMAGE_REL_ARM_ADDR32NB:
*RelocSite32 = *RelocSite32 + TargetAddr;
break;
case llvm::COFF::IMAGE_REL_ARM_MOV32T:
applyThumbMoveImmediate(&RelocSite16[0], (TargetAddr + ImageBase) >> 0);
applyThumbMoveImmediate(&RelocSite16[2], (TargetAddr + ImageBase) >> 16);
break;
case llvm::COFF::IMAGE_REL_ARM_BRANCH24T:
// NOTE: the thumb bit will implicitly be truncated properly
applyThumbBranchImmediate(RelocSite16,
TargetAddr - AtomRVA[Atom] - AtomOffset - 4);
break;
case llvm::COFF::IMAGE_REL_ARM_BLX23T:
// NOTE: the thumb bit will implicitly be truncated properly
applyThumbBranchImmediate(RelocSite16,
TargetAddr - AtomRVA[Atom] - AtomOffset - 4);
break;
}
}
});
}
void AtomChunk::applyRelocationsX86(uint8_t *buffer,
std::map<const Atom *, uint64_t> &atomRva,
std::vector<uint64_t> &sectionRva,
uint64_t imageBaseAddress) {
buffer += _fileOffset;
parallel_for_each(_atomLayouts.begin(), _atomLayouts.end(),
[&](const AtomLayout *layout) {
const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
for (const Reference *ref : *atom) {
// Skip if this reference is not for COFF relocation.
if (ref->kindNamespace() != Reference::KindNamespace::COFF)
continue;
auto relocSite32 = reinterpret_cast<ulittle32_t *>(
buffer + layout->_fileOffset + ref->offsetInAtom());
auto relocSite16 = reinterpret_cast<ulittle16_t *>(relocSite32);
const Atom *target = ref->target();
uint64_t targetAddr = atomRva[target];
// Also account for whatever offset is already stored at the relocation
// site.
switch (ref->kindValue()) {
case llvm::COFF::IMAGE_REL_I386_ABSOLUTE:
// This relocation is no-op.
break;
case llvm::COFF::IMAGE_REL_I386_DIR32:
// Set target's 32-bit VA.
if (auto *abs = dyn_cast<AbsoluteAtom>(target))
*relocSite32 += abs->value();
else
*relocSite32 += targetAddr + imageBaseAddress;
break;
case llvm::COFF::IMAGE_REL_I386_DIR32NB:
// Set target's 32-bit RVA.
*relocSite32 += targetAddr;
break;
case llvm::COFF::IMAGE_REL_I386_REL32: {
// Set 32-bit relative address of the target. This relocation is
// usually used for relative branch or call instruction.
uint32_t disp = atomRva[atom] + ref->offsetInAtom() + 4;
*relocSite32 += targetAddr - disp;
break;
}
case llvm::COFF::IMAGE_REL_I386_SECTION:
// The 16-bit section index that contains the target symbol.
*relocSite16 += getSectionIndex(targetAddr, sectionRva);
break;
case llvm::COFF::IMAGE_REL_I386_SECREL:
// The 32-bit relative address from the beginning of the section that
// contains the target symbol.
*relocSite32 +=
targetAddr - getSectionStartAddr(targetAddr, sectionRva);
break;
default:
llvm::report_fatal_error("Unsupported relocation kind");
}
}
});
}
void AtomChunk::applyRelocationsX64(uint8_t *buffer,
std::map<const Atom *, uint64_t> &atomRva,
std::vector<uint64_t> &sectionRva,
uint64_t imageBase) {
buffer += _fileOffset;
parallel_for_each(_atomLayouts.begin(), _atomLayouts.end(),
[&](const AtomLayout *layout) {
const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
for (const Reference *ref : *atom) {
if (ref->kindNamespace() != Reference::KindNamespace::COFF)
continue;
uint8_t *loc = buffer + layout->_fileOffset + ref->offsetInAtom();
auto relocSite16 = reinterpret_cast<ulittle16_t *>(loc);
auto relocSite32 = reinterpret_cast<ulittle32_t *>(loc);
auto relocSite64 = reinterpret_cast<ulittle64_t *>(loc);
uint64_t targetAddr = atomRva[ref->target()];
switch (ref->kindValue()) {
case llvm::COFF::IMAGE_REL_AMD64_ADDR64:
*relocSite64 += targetAddr + imageBase;
break;
case llvm::COFF::IMAGE_REL_AMD64_ADDR32:
*relocSite32 += targetAddr + imageBase;
break;
case llvm::COFF::IMAGE_REL_AMD64_ADDR32NB:
*relocSite32 += targetAddr;
break;
case llvm::COFF::IMAGE_REL_AMD64_REL32:
*relocSite32 += targetAddr - atomRva[atom] - ref->offsetInAtom() - 4;
break;
case llvm::COFF::IMAGE_REL_AMD64_REL32_1:
*relocSite32 += targetAddr - atomRva[atom] - ref->offsetInAtom() - 5;
break;
case llvm::COFF::IMAGE_REL_AMD64_REL32_2:
*relocSite32 += targetAddr - atomRva[atom] - ref->offsetInAtom() - 6;
break;
case llvm::COFF::IMAGE_REL_AMD64_REL32_3:
*relocSite32 += targetAddr - atomRva[atom] - ref->offsetInAtom() - 7;
break;
case llvm::COFF::IMAGE_REL_AMD64_REL32_4:
*relocSite32 += targetAddr - atomRva[atom] - ref->offsetInAtom() - 8;
break;
case llvm::COFF::IMAGE_REL_AMD64_REL32_5:
*relocSite32 += targetAddr - atomRva[atom] - ref->offsetInAtom() - 9;
break;
case llvm::COFF::IMAGE_REL_AMD64_SECTION:
*relocSite16 += getSectionIndex(targetAddr, sectionRva) - 1;
break;
case llvm::COFF::IMAGE_REL_AMD64_SECREL:
*relocSite32 +=
targetAddr - getSectionStartAddr(targetAddr, sectionRva);
break;
default:
llvm::errs() << "Kind: " << (int)ref->kindValue() << "\n";
llvm::report_fatal_error("Unsupported relocation kind");
}
}
});
}
/// Print atom VAs. Used only for debugging.
void AtomChunk::printAtomAddresses(uint64_t baseAddr) const {
for (const auto *layout : _atomLayouts) {
const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
uint64_t addr = layout->_virtualAddr;
llvm::dbgs() << llvm::format("0x%08llx: ", addr + baseAddr)
<< (atom->name().empty() ? "(anonymous)" : atom->name())
<< "\n";
}
}
/// List all virtual addresses (and not relative virtual addresses) that need
/// to be fixed up if image base is relocated. The only relocation type that
/// needs to be fixed is DIR32 on i386. REL32 is not (and should not be)
/// fixed up because it's PC-relative.
void AtomChunk::addBaseRelocations(std::vector<BaseReloc> &relocSites) const {
for (const auto *layout : _atomLayouts) {
const DefinedAtom *atom = cast<DefinedAtom>(layout->_atom);
for (const Reference *ref : *atom) {
if (ref->kindNamespace() != Reference::KindNamespace::COFF)
continue;
// An absolute symbol points to a fixed location in memory. Their
// address should not be fixed at load time. One exception is ImageBase
// because that's relative to run-time image base address.
if (auto *abs = dyn_cast<AbsoluteAtom>(ref->target()))
if (!abs->name().equals("__ImageBase") &&
!abs->name().equals("___ImageBase"))
continue;
uint64_t address = layout->_virtualAddr + ref->offsetInAtom();
switch (_machineType) {
default: llvm_unreachable("unsupported machine type");
case llvm::COFF::IMAGE_FILE_MACHINE_I386:
if (ref->kindValue() == llvm::COFF::IMAGE_REL_I386_DIR32)
relocSites.push_back(
BaseReloc(address, llvm::COFF::IMAGE_REL_BASED_HIGHLOW));
break;
case llvm::COFF::IMAGE_FILE_MACHINE_AMD64:
if (ref->kindValue() == llvm::COFF::IMAGE_REL_AMD64_ADDR64)
relocSites.push_back(
BaseReloc(address, llvm::COFF::IMAGE_REL_BASED_DIR64));
break;
case llvm::COFF::IMAGE_FILE_MACHINE_ARMNT:
if (ref->kindValue() == llvm::COFF::IMAGE_REL_ARM_ADDR32)
relocSites.push_back(
BaseReloc(address, llvm::COFF::IMAGE_REL_BASED_HIGHLOW));
else if (ref->kindValue() == llvm::COFF::IMAGE_REL_ARM_MOV32T)
relocSites.push_back(
BaseReloc(address, llvm::COFF::IMAGE_REL_BASED_ARM_MOV32T));
break;
}
}
}
}
void AtomChunk::setVirtualAddress(uint32_t rva) {
SectionChunk::setVirtualAddress(rva);
for (AtomLayout *layout : _atomLayouts)
layout->_virtualAddr += rva;
}
uint64_t AtomChunk::getAtomVirtualAddress(StringRef name) const {
for (auto atomLayout : _atomLayouts)
if (atomLayout->_atom->name() == name)
return atomLayout->_virtualAddr;
return 0;
}
void DataDirectoryChunk::setField(DataDirectoryIndex index, uint32_t addr,
uint32_t size) {
llvm::object::data_directory &dir = _data[index];
dir.RelativeVirtualAddress = addr;
dir.Size = size;
}
void DataDirectoryChunk::write(uint8_t *buffer) {
std::memcpy(buffer, &_data[0], size());
}
uint64_t AtomChunk::memAlign() const {
// ReaderCOFF propagated the section alignment to the first atom in
// the section. We restore that here.
if (_atomLayouts.empty())
return _ctx.getPageSize();
unsigned align = _ctx.getPageSize();
for (auto atomLayout : _atomLayouts) {
auto *atom = cast<const DefinedAtom>(atomLayout->_atom);
align = std::max(align, (unsigned)atom->alignment().value);
}
return align;
}
void AtomChunk::appendAtom(const DefinedAtom *atom) {
// Atom may have to be at a proper alignment boundary. If so, move the
// pointer to make a room after the last atom before adding new one.
_size = llvm::RoundUpToAlignment(_size, atom->alignment().value);
// Create an AtomLayout and move the current pointer.
auto *layout = new (_alloc) AtomLayout(atom, _size, _size);
_atomLayouts.push_back(layout);
_size += atom->size();
}
uint32_t AtomChunk::getDefaultCharacteristics(
StringRef name, const std::vector<const DefinedAtom *> &atoms) const {
const uint32_t code = llvm::COFF::IMAGE_SCN_CNT_CODE;
const uint32_t execute = llvm::COFF::IMAGE_SCN_MEM_EXECUTE;
const uint32_t read = llvm::COFF::IMAGE_SCN_MEM_READ;
const uint32_t write = llvm::COFF::IMAGE_SCN_MEM_WRITE;
const uint32_t data = llvm::COFF::IMAGE_SCN_CNT_INITIALIZED_DATA;
const uint32_t bss = llvm::COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
if (name == ".text")
return code | execute | read;
if (name == ".data")
return data | read | write;
if (name == ".rdata")
return data | read;
if (name == ".bss")
return bss | read | write;
assert(atoms.size() > 0);
switch (atoms[0]->permissions()) {
case DefinedAtom::permR__:
return data | read;
case DefinedAtom::permRW_:
return data | read | write;
case DefinedAtom::permR_X:
return code | execute | read;
case DefinedAtom::permRWX:
return code | execute | read | write;
default:
llvm_unreachable("Unsupported permission");
}
}
void SectionHeaderTableChunk::addSection(SectionChunk *chunk) {
_sections.push_back(chunk);
}
uint64_t SectionHeaderTableChunk::size() const {
return _sections.size() * sizeof(llvm::object::coff_section);
}
void SectionHeaderTableChunk::write(uint8_t *buffer) {
uint64_t offset = 0;
for (SectionChunk *chunk : _sections) {
llvm::object::coff_section header = createSectionHeader(chunk);
std::memcpy(buffer + offset, &header, sizeof(header));
offset += sizeof(header);
}
}
llvm::object::coff_section
SectionHeaderTableChunk::createSectionHeader(SectionChunk *chunk) {
llvm::object::coff_section header;
// We have extended the COFF specification by allowing section names to be
// greater than eight characters. We achieve this by adding the section names
// to the string table. Binutils' linker, ld, performs the same trick.
StringRef sectionName = chunk->getSectionName();
std::memset(header.Name, 0, llvm::COFF::NameSize);
if (uint32_t stringTableOffset = chunk->getStringTableOffset())
sprintf(header.Name, "/%u", stringTableOffset);
else
std::strncpy(header.Name, sectionName.data(), sectionName.size());
uint32_t characteristics = chunk->getCharacteristics();
header.VirtualSize = chunk->size();
header.VirtualAddress = chunk->getVirtualAddress();
header.SizeOfRawData = chunk->onDiskSize();
header.PointerToRelocations = 0;
header.PointerToLinenumbers = 0;
header.NumberOfRelocations = 0;
header.NumberOfLinenumbers = 0;
header.Characteristics = characteristics;
if (characteristics & llvm::COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) {
header.PointerToRawData = 0;
} else {
header.PointerToRawData = chunk->fileOffset();
}
return header;
}
/// Creates .reloc section content from the other sections. The content of
/// .reloc is basically a list of relocation sites. The relocation sites are
/// divided into blocks. Each block represents the base relocation for a 4K
/// page.
///
/// By dividing 32 bit RVAs into blocks, COFF saves disk and memory space for
/// the base relocation. A block consists of a 32 bit page RVA and 16 bit
/// relocation entries which represent offsets in the page. That is a more
/// compact representation than a simple vector of 32 bit RVAs.
std::vector<uint8_t>
BaseRelocChunk::createContents(ChunkVectorT &chunks) const {
std::vector<uint8_t> contents;
std::vector<BaseReloc> relocSites = listRelocSites(chunks);
uint64_t mask = _ctx.getPageSize() - 1;
parallel_sort(relocSites.begin(), relocSites.end(),
[=](const BaseReloc &a, const BaseReloc &b) {
return (a.addr & ~mask) < (b.addr & ~mask);
});
// Base relocations for the same memory page are grouped together
// and passed to createBaseRelocBlock.
for (auto it = relocSites.begin(), e = relocSites.end(); it != e;) {
auto beginIt = it;
uint64_t pageAddr = (beginIt->addr & ~mask);
for (++it; it != e; ++it)
if ((it->addr & ~mask) != pageAddr)
break;
const BaseReloc *begin = &*beginIt;
const BaseReloc *end = begin + (it - beginIt);
std::vector<uint8_t> block = createBaseRelocBlock(pageAddr, begin, end);
contents.insert(contents.end(), block.begin(), block.end());
}
return contents;
}
// Returns a list of RVAs that needs to be relocated if the binary is loaded
// at an address different from its preferred one.
std::vector<BaseReloc>
BaseRelocChunk::listRelocSites(ChunkVectorT &chunks) const {
std::vector<BaseReloc> ret;
for (auto &cp : chunks)
if (AtomChunk *chunk = dyn_cast<AtomChunk>(&*cp))
chunk->addBaseRelocations(ret);
return ret;
}
// Create the content of a relocation block.
std::vector<uint8_t>
BaseRelocChunk::createBaseRelocBlock(uint64_t pageAddr,
const BaseReloc *begin,
const BaseReloc *end) const {
// Relocation blocks should be padded with IMAGE_REL_I386_ABSOLUTE to be
// aligned to a DWORD size boundary.
uint32_t size = llvm::RoundUpToAlignment(
sizeof(ulittle32_t) * 2 + sizeof(ulittle16_t) * (end - begin),
sizeof(ulittle32_t));
std::vector<uint8_t> contents(size);
uint8_t *ptr = &contents[0];
// The first four bytes is the page RVA.
write32le(ptr, pageAddr);
ptr += sizeof(ulittle32_t);
// The second four bytes is the size of the block, including the the page
// RVA and this size field.
write32le(ptr, size);
ptr += sizeof(ulittle32_t);
uint64_t mask = _ctx.getPageSize() - 1;
for (const BaseReloc *i = begin; i < end; ++i) {
write16le(ptr, (i->type << 12) | (i->addr & mask));
ptr += sizeof(ulittle16_t);
}
return contents;
}
} // end anonymous namespace
class PECOFFWriter : public Writer {
public:
explicit PECOFFWriter(const PECOFFLinkingContext &context)
: _ctx(context), _numSections(0), _imageSizeInMemory(_ctx.getPageSize()),
_imageSizeOnDisk(0) {}
template <class PEHeader> void build(const File &linkedFile);
std::error_code writeFile(const File &linkedFile, StringRef path) override;
private:
void applyAllRelocations(uint8_t *bufferStart);
void printAllAtomAddresses() const;
void reorderSEHTableEntries(uint8_t *bufferStart);
void reorderSEHTableEntriesX86(uint8_t *bufferStart);
void reorderSEHTableEntriesX64(uint8_t *bufferStart);
void addChunk(Chunk *chunk);
void addSectionChunk(std::unique_ptr<SectionChunk> chunk,
SectionHeaderTableChunk *table,
StringTableChunk *stringTable);
void setImageSizeOnDisk();
uint64_t
calcSectionSize(llvm::COFF::SectionCharacteristics sectionType) const;
uint64_t calcSizeOfInitializedData() const {
return calcSectionSize(llvm::COFF::IMAGE_SCN_CNT_INITIALIZED_DATA);
}
uint64_t calcSizeOfUninitializedData() const {
return calcSectionSize(llvm::COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA);
}
uint64_t calcSizeOfCode() const {
return calcSectionSize(llvm::COFF::IMAGE_SCN_CNT_CODE);
}
std::vector<std::unique_ptr<Chunk> > _chunks;
const PECOFFLinkingContext &_ctx;
uint32_t _numSections;
// The size of the image in memory. This is initialized with
// _ctx.getPageSize(), as the first page starting at ImageBase is usually left
// unmapped. IIUC there's no technical reason to do so, but we'll follow that
// convention so that we don't produce odd-looking binary.
uint32_t _imageSizeInMemory;
// The size of the image on disk. This is basically the sum of all chunks in
// the output file with paddings between them.
uint32_t _imageSizeOnDisk;
// The map from atom to its relative virtual address.
std::map<const Atom *, uint64_t> _atomRva;
};
StringRef customSectionName(const DefinedAtom *atom) {
assert(atom->sectionChoice() == DefinedAtom::sectionCustomRequired);
StringRef s = atom->customSectionName();
size_t pos = s.find('$');
return (pos == StringRef::npos) ? s : s.substr(0, pos);
}
StringRef chooseSectionByContent(const DefinedAtom *atom) {
switch (atom->contentType()) {
case DefinedAtom::typeCode:
return ".text";
case DefinedAtom::typeZeroFill:
return ".bss";
case DefinedAtom::typeData:
if (atom->permissions() == DefinedAtom::permR__)
return ".rdata";
if (atom->permissions() == DefinedAtom::permRW_)
return ".data";
break;
default:
break;
}
llvm::errs() << "Atom: contentType=" << atom->contentType()
<< " permission=" << atom->permissions() << "\n";
llvm::report_fatal_error("Failed to choose section based on content");
}
typedef std::map<StringRef, std::vector<const DefinedAtom *> > AtomVectorMap;
void groupAtoms(const PECOFFLinkingContext &ctx, const File &file,
AtomVectorMap &result) {
for (const DefinedAtom *atom : file.defined()) {
if (atom->sectionChoice() == DefinedAtom::sectionCustomRequired) {
StringRef section = customSectionName(atom);
result[ctx.getOutputSectionName(section)].push_back(atom);
continue;
}
if (atom->sectionChoice() == DefinedAtom::sectionBasedOnContent) {
StringRef section = chooseSectionByContent(atom);
result[ctx.getOutputSectionName(section)].push_back(atom);
continue;
}
llvm_unreachable("Unknown section choice");
}
}
static const DefinedAtom *findTLSUsedSymbol(const PECOFFLinkingContext &ctx,
const File &file) {
StringRef sym = ctx.decorateSymbol("_tls_used");
for (const DefinedAtom *atom : file.defined())
if (atom->name() == sym)
return atom;
return nullptr;
}
// Create all chunks that consist of the output file.
template <class PEHeader>
void PECOFFWriter::build(const File &linkedFile) {
AtomVectorMap atoms;
groupAtoms(_ctx, linkedFile, atoms);
// Create file chunks and add them to the list.
auto *dosStub = new DOSStubChunk(_ctx);
auto *peHeader = new PEHeaderChunk<PEHeader>(_ctx);
auto *dataDirectory = new DataDirectoryChunk();
auto *sectionTable = new SectionHeaderTableChunk();
auto *stringTable = new StringTableChunk();
addChunk(dosStub);
addChunk(peHeader);
addChunk(dataDirectory);
addChunk(sectionTable);
addChunk(stringTable);
// Create sections and add the atoms to them.
for (auto i : atoms) {
StringRef sectionName = i.first;
std::vector<const DefinedAtom *> &contents = i.second;
std::unique_ptr<SectionChunk> section(
new AtomChunk(_ctx, sectionName, contents));
if (section->size() > 0)
addSectionChunk(std::move(section), sectionTable, stringTable);
}
// Build atom to its RVA map.
for (std::unique_ptr<Chunk> &cp : _chunks)
if (AtomChunk *chunk = dyn_cast<AtomChunk>(&*cp))
chunk->buildAtomRvaMap(_atomRva);
// We know the addresses of all defined atoms that needs to be
// relocated. So we can create the ".reloc" section which contains
// all the relocation sites.
if (_ctx.getBaseRelocationEnabled()) {
std::unique_ptr<SectionChunk> baseReloc(new BaseRelocChunk(_chunks, _ctx));
if (baseReloc->size()) {
SectionChunk &ref = *baseReloc;
addSectionChunk(std::move(baseReloc), sectionTable, stringTable);
dataDirectory->setField(DataDirectoryIndex::BASE_RELOCATION_TABLE,
ref.getVirtualAddress(), ref.size());
}
}
setImageSizeOnDisk();
if (stringTable->size()) {
peHeader->setPointerToSymbolTable(stringTable->fileOffset());
peHeader->setNumberOfSymbols(1);
}
for (std::unique_ptr<Chunk> &chunk : _chunks) {
SectionChunk *section = dyn_cast<SectionChunk>(chunk.get());
if (!section)
continue;
if (section->getSectionName() == ".text") {
peHeader->setBaseOfCode(section->getVirtualAddress());
// Find the virtual address of the entry point symbol if any. PECOFF spec
// says that entry point for dll images is optional, in which case it must
// be set to 0.
if (_ctx.hasEntry()) {
AtomChunk *atom = cast<AtomChunk>(section);
uint64_t entryPointAddress =
atom->getAtomVirtualAddress(_ctx.getEntrySymbolName());
if (entryPointAddress) {
// NOTE: ARM NT assumes a pure THUMB execution, so adjust the entry
// point accordingly
if (_ctx.getMachineType() == llvm::COFF::IMAGE_FILE_MACHINE_ARMNT)
entryPointAddress |= 1;
peHeader->setAddressOfEntryPoint(entryPointAddress);
}
} else {
peHeader->setAddressOfEntryPoint(0);
}
}
StringRef name = section->getSectionName();
if (name == ".data") {
peHeader->setBaseOfData(section->getVirtualAddress());
continue;
}
DataDirectoryIndex ignore = DataDirectoryIndex(-1);
DataDirectoryIndex idx = llvm::StringSwitch<DataDirectoryIndex>(name)
.Case(".pdata", DataDirectoryIndex::EXCEPTION_TABLE)
.Case(".rsrc", DataDirectoryIndex::RESOURCE_TABLE)
.Case(".idata.a", DataDirectoryIndex::IAT)
.Case(".idata.d", DataDirectoryIndex::IMPORT_TABLE)
.Case(".edata", DataDirectoryIndex::EXPORT_TABLE)
.Case(".loadcfg", DataDirectoryIndex::LOAD_CONFIG_TABLE)
.Case(".didat.d", DataDirectoryIndex::DELAY_IMPORT_DESCRIPTOR)
.Default(ignore);
if (idx == ignore)
continue;
dataDirectory->setField(idx, section->getVirtualAddress(), section->size());
}
if (const DefinedAtom *atom = findTLSUsedSymbol(_ctx, linkedFile)) {
dataDirectory->setField(DataDirectoryIndex::TLS_TABLE, _atomRva[atom],
0x18);
}
// Now that we know the size and file offset of sections. Set the file
// header accordingly.
peHeader->setSizeOfCode(calcSizeOfCode());
peHeader->setSizeOfInitializedData(calcSizeOfInitializedData());
peHeader->setSizeOfUninitializedData(calcSizeOfUninitializedData());
peHeader->setNumberOfSections(_numSections);
peHeader->setSizeOfImage(_imageSizeInMemory);
peHeader->setSizeOfHeaders(sectionTable->fileOffset() + sectionTable->size());
}
std::error_code PECOFFWriter::writeFile(const File &linkedFile,
StringRef path) {
if (_ctx.is64Bit()) {
this->build<llvm::object::pe32plus_header>(linkedFile);
} else {
this->build<llvm::object::pe32_header>(linkedFile);
}
uint64_t totalSize =
_chunks.back()->fileOffset() + _chunks.back()->onDiskSize();
std::unique_ptr<llvm::FileOutputBuffer> buffer;
std::error_code ec = llvm::FileOutputBuffer::create(
path, totalSize, buffer, llvm::FileOutputBuffer::F_executable);
if (ec)
return ec;
for (std::unique_ptr<Chunk> &chunk : _chunks)
chunk->write(buffer->getBufferStart() + chunk->fileOffset());
applyAllRelocations(buffer->getBufferStart());
reorderSEHTableEntries(buffer->getBufferStart());
DEBUG(printAllAtomAddresses());
if (_ctx.isDll())
writeImportLibrary(_ctx);
return buffer->commit();
}
/// Apply relocations to the output file buffer. This two pass. In the first
/// pass, we visit all atoms to create a map from atom to its virtual
/// address. In the second pass, we visit all relocation references to fix
/// up addresses in the buffer.
void PECOFFWriter::applyAllRelocations(uint8_t *bufferStart) {
// Create the list of section start addresses. It's needed for
// relocations of SECREL type.
std::vector<uint64_t> sectionRva;
for (auto &cp : _chunks)
if (SectionChunk *section = dyn_cast<SectionChunk>(&*cp))
sectionRva.push_back(section->getVirtualAddress());
uint64_t base = _ctx.getBaseAddress();
for (auto &cp : _chunks) {
if (AtomChunk *chunk = dyn_cast<AtomChunk>(&*cp)) {
switch (_ctx.getMachineType()) {
default: llvm_unreachable("unsupported machine type");
case llvm::COFF::IMAGE_FILE_MACHINE_ARMNT:
chunk->applyRelocationsARM(bufferStart, _atomRva, sectionRva, base);
break;
case llvm::COFF::IMAGE_FILE_MACHINE_I386:
chunk->applyRelocationsX86(bufferStart, _atomRva, sectionRva, base);
break;
case llvm::COFF::IMAGE_FILE_MACHINE_AMD64:
chunk->applyRelocationsX64(bufferStart, _atomRva, sectionRva, base);
break;
}
}
}
}
/// Print atom VAs. Used only for debugging.
void PECOFFWriter::printAllAtomAddresses() const {
for (auto &cp : _chunks)
if (AtomChunk *chunk = dyn_cast<AtomChunk>(&*cp))
chunk->printAtomAddresses(_ctx.getBaseAddress());
}
void PECOFFWriter::reorderSEHTableEntries(uint8_t *bufferStart) {
auto machineType = _ctx.getMachineType();
if (machineType == llvm::COFF::IMAGE_FILE_MACHINE_I386)
reorderSEHTableEntriesX86(bufferStart);
if (machineType == llvm::COFF::IMAGE_FILE_MACHINE_AMD64)
reorderSEHTableEntriesX64(bufferStart);
}
/// It seems that the entries in .sxdata must be sorted. This function is called
/// after a COFF file image is created in memory and before it is written to
/// disk. It is safe to reorder entries at this stage because the contents of
/// the entries are RVAs and there's no reference to a .sxdata entry other than
/// to the beginning of the section.
void PECOFFWriter::reorderSEHTableEntriesX86(uint8_t *bufferStart) {
for (std::unique_ptr<Chunk> &chunk : _chunks) {
if (SectionChunk *section = dyn_cast<SectionChunk>(chunk.get())) {
if (section->getSectionName() == ".sxdata") {
int numEntries = section->size() / sizeof(ulittle32_t);
ulittle32_t *begin = reinterpret_cast<ulittle32_t *>(bufferStart + section->fileOffset());
ulittle32_t *end = begin + numEntries;
std::sort(begin, end);
}
}
}
}
/// The entries in .pdata must be sorted according to its BeginAddress field
/// value. It's safe to do it because of the same reason as .sxdata.
void PECOFFWriter::reorderSEHTableEntriesX64(uint8_t *bufferStart) {
for (std::unique_ptr<Chunk> &chunk : _chunks) {
if (SectionChunk *section = dyn_cast<SectionChunk>(chunk.get())) {
if (section->getSectionName() != ".pdata")
continue;
int numEntries = section->size() / sizeof(coff_runtime_function_x64);
coff_runtime_function_x64 *begin =
(coff_runtime_function_x64 *)(bufferStart + section->fileOffset());
coff_runtime_function_x64 *end = begin + numEntries;
std::sort(begin, end, [](const coff_runtime_function_x64 &lhs,
const coff_runtime_function_x64 &rhs) {
return lhs.BeginAddress < rhs.BeginAddress;
});
}
}
}
void PECOFFWriter::addChunk(Chunk *chunk) {
_chunks.push_back(std::unique_ptr<Chunk>(chunk));
}
void PECOFFWriter::addSectionChunk(std::unique_ptr<SectionChunk> chunk,
SectionHeaderTableChunk *table,
StringTableChunk *stringTable) {
table->addSection(chunk.get());
_numSections++;
StringRef sectionName = chunk->getSectionName();
if (sectionName.size() > llvm::COFF::NameSize) {
uint32_t stringTableOffset = stringTable->addSectionName(sectionName);
chunk->setStringTableOffset(stringTableOffset);
}
// Compute and set the starting address of sections when loaded in
// memory. They are different from positions on disk because sections need
// to be sector-aligned on disk but page-aligned in memory.
_imageSizeInMemory = llvm::RoundUpToAlignment(
_imageSizeInMemory, chunk->memAlign());
chunk->setVirtualAddress(_imageSizeInMemory);
_imageSizeInMemory = llvm::RoundUpToAlignment(
_imageSizeInMemory + chunk->size(), _ctx.getPageSize());
_chunks.push_back(std::move(chunk));
}
void PECOFFWriter::setImageSizeOnDisk() {
for (auto &chunk : _chunks) {
// Compute and set the offset of the chunk in the output file.
_imageSizeOnDisk =
llvm::RoundUpToAlignment(_imageSizeOnDisk, chunk->align());
chunk->setFileOffset(_imageSizeOnDisk);
_imageSizeOnDisk += chunk->onDiskSize();
}
}
uint64_t PECOFFWriter::calcSectionSize(
llvm::COFF::SectionCharacteristics sectionType) const {
uint64_t ret = 0;
for (auto &cp : _chunks)
if (SectionChunk *chunk = dyn_cast<SectionChunk>(&*cp))
if (chunk->getCharacteristics() & sectionType)
ret += chunk->onDiskSize();
return ret;
}
} // end namespace pecoff
std::unique_ptr<Writer> createWriterPECOFF(const PECOFFLinkingContext &info) {
return std::unique_ptr<Writer>(new pecoff::PECOFFWriter(info));
}
} // end namespace lld
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