caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
8d2cbf2e9b788a544f7e46b200a1be403effc708
clang-p2996/lld/COFF/Writer.cpp
Reid Kleckner 8d2cbf2e9b [PDB] Improve our PDB OMF debug directory entry 
In order to get dbghelp to load our pdb, we have to fill in the
PointerToRawData field as well as the AddressOfRawData field. One is the
file offset and the other is the RVA.

llvm-svn: 309900
2017-08-02 23:19:54 +00:00

895 lines
29 KiB
C++
Raw Blame History

//===- Writer.cpp ---------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "Writer.h"
#include "Config.h"
#include "DLL.h"
#include "Error.h"
#include "InputFiles.h"
#include "MapFile.h"
#include "Memory.h"
#include "PDB.h"
#include "SymbolTable.h"
#include "Symbols.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/Parallel.h"
#include "llvm/Support/RandomNumberGenerator.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cstdio>
#include <map>
#include <memory>
#include <utility>
using namespace llvm;
using namespace llvm::COFF;
using namespace llvm::object;
using namespace llvm::support;
using namespace llvm::support::endian;
using namespace lld;
using namespace lld::coff;
static const int SectorSize = 512;
static const int DOSStubSize = 64;
static const int NumberfOfDataDirectory = 16;
namespace {
class DebugDirectoryChunk : public Chunk {
public:
DebugDirectoryChunk(const std::vector<Chunk *> &R) : Records(R) {}
size_t getSize() const override {
return Records.size() * sizeof(debug_directory);
}
void writeTo(uint8_t *B) const override {
auto *D = reinterpret_cast<debug_directory *>(B + OutputSectionOff);
for (const Chunk *Record : Records) {
D->Characteristics = 0;
D->TimeDateStamp = 0;
D->MajorVersion = 0;
D->MinorVersion = 0;
D->Type = COFF::IMAGE_DEBUG_TYPE_CODEVIEW;
D->SizeOfData = Record->getSize();
D->AddressOfRawData = Record->getRVA();
OutputSection *OS = Record->getOutputSection();
uint64_t Offs = OS->getFileOff() + (Record->getRVA() - OS->getRVA());
D->PointerToRawData = Offs;
++D;
}
}
private:
const std::vector<Chunk *> &Records;
};
class CVDebugRecordChunk : public Chunk {
size_t getSize() const override {
return sizeof(codeview::DebugInfo) + Config->PDBPath.size() + 1;
}
void writeTo(uint8_t *B) const override {
// Save off the DebugInfo entry to backfill the file signature (build id)
// in Writer::writeBuildId
DI = reinterpret_cast<codeview::DebugInfo *>(B + OutputSectionOff);
DI->Signature.CVSignature = OMF::Signature::PDB70;
// variable sized field (PDB Path)
auto *P = reinterpret_cast<char *>(B + OutputSectionOff + sizeof(*DI));
if (!Config->PDBPath.empty())
memcpy(P, Config->PDBPath.data(), Config->PDBPath.size());
P[Config->PDBPath.size()] = '\0';
}
public:
mutable codeview::DebugInfo *DI = nullptr;
};
// The writer writes a SymbolTable result to a file.
class Writer {
public:
Writer(SymbolTable *T) : Symtab(T) {}
void run();
private:
void createSections();
void createMiscChunks();
void createImportTables();
void createExportTable();
void assignAddresses();
void removeEmptySections();
void createSymbolAndStringTable();
void openFile(StringRef OutputPath);
template <typename PEHeaderTy> void writeHeader();
void fixSafeSEHSymbols();
void setSectionPermissions();
void writeSections();
void sortExceptionTable();
void writeBuildId();
llvm::Optional<coff_symbol16> createSymbol(Defined *D);
size_t addEntryToStringTable(StringRef Str);
OutputSection *findSection(StringRef Name);
OutputSection *createSection(StringRef Name);
void addBaserels(OutputSection *Dest);
void addBaserelBlocks(OutputSection *Dest, std::vector<Baserel> &V);
uint32_t getSizeOfInitializedData();
std::map<StringRef, std::vector<DefinedImportData *>> binImports();
SymbolTable *Symtab;
std::unique_ptr<FileOutputBuffer> Buffer;
std::vector<OutputSection *> OutputSections;
std::vector<char> Strtab;
std::vector<llvm::object::coff_symbol16> OutputSymtab;
IdataContents Idata;
DelayLoadContents DelayIdata;
EdataContents Edata;
SEHTableChunk *SEHTable = nullptr;
Chunk *DebugDirectory = nullptr;
std::vector<Chunk *> DebugRecords;
CVDebugRecordChunk *BuildId = nullptr;
ArrayRef<uint8_t> SectionTable;
uint64_t FileSize;
uint32_t PointerToSymbolTable = 0;
uint64_t SizeOfImage;
uint64_t SizeOfHeaders;
};
} // anonymous namespace
namespace lld {
namespace coff {
void writeResult(SymbolTable *T) { Writer(T).run(); }
void OutputSection::setRVA(uint64_t RVA) {
Header.VirtualAddress = RVA;
for (Chunk *C : Chunks)
C->setRVA(C->getRVA() + RVA);
}
void OutputSection::setFileOffset(uint64_t Off) {
// If a section has no actual data (i.e. BSS section), we want to
// set 0 to its PointerToRawData. Otherwise the output is rejected
// by the loader.
if (Header.SizeOfRawData == 0)
return;
Header.PointerToRawData = Off;
}
void OutputSection::addChunk(Chunk *C) {
Chunks.push_back(C);
C->setOutputSection(this);
uint64_t Off = Header.VirtualSize;
Off = alignTo(Off, C->getAlign());
C->setRVA(Off);
C->OutputSectionOff = Off;
Off += C->getSize();
Header.VirtualSize = Off;
if (C->hasData())
Header.SizeOfRawData = alignTo(Off, SectorSize);
}
void OutputSection::addPermissions(uint32_t C) {
Header.Characteristics |= C & PermMask;
}
void OutputSection::setPermissions(uint32_t C) {
Header.Characteristics = C & PermMask;
}
// Write the section header to a given buffer.
void OutputSection::writeHeaderTo(uint8_t *Buf) {
auto *Hdr = reinterpret_cast<coff_section *>(Buf);
*Hdr = Header;
if (StringTableOff) {
// If name is too long, write offset into the string table as a name.
sprintf(Hdr->Name, "/%d", StringTableOff);
} else {
assert(!Config->Debug || Name.size() <= COFF::NameSize);
strncpy(Hdr->Name, Name.data(),
std::min(Name.size(), (size_t)COFF::NameSize));
}
}
} // namespace coff
} // namespace lld
// The main function of the writer.
void Writer::run() {
createSections();
createMiscChunks();
createImportTables();
createExportTable();
if (Config->Relocatable)
createSection(".reloc");
assignAddresses();
removeEmptySections();
setSectionPermissions();
createSymbolAndStringTable();
openFile(Config->OutputFile);
if (Config->is64()) {
writeHeader<pe32plus_header>();
} else {
writeHeader<pe32_header>();
}
fixSafeSEHSymbols();
writeSections();
sortExceptionTable();
writeBuildId();
if (!Config->PDBPath.empty() && Config->Debug) {
const llvm::codeview::DebugInfo *DI = nullptr;
if (Config->DebugTypes & static_cast<unsigned>(coff::DebugType::CV))
DI = BuildId->DI;
createPDB(Symtab, SectionTable, DI);
}
writeMapFile(OutputSections);
if (auto EC = Buffer->commit())
fatal(EC, "failed to write the output file");
}
static StringRef getOutputSection(StringRef Name) {
StringRef S = Name.split('$').first;
auto It = Config->Merge.find(S);
if (It == Config->Merge.end())
return S;
return It->second;
}
// Create output section objects and add them to OutputSections.
void Writer::createSections() {
// First, bin chunks by name.
std::map<StringRef, std::vector<Chunk *>> Map;
for (Chunk *C : Symtab->getChunks()) {
auto *SC = dyn_cast<SectionChunk>(C);
if (SC && !SC->isLive()) {
if (Config->Verbose)
SC->printDiscardedMessage();
continue;
}
Map[C->getSectionName()].push_back(C);
}
// Then create an OutputSection for each section.
// '$' and all following characters in input section names are
// discarded when determining output section. So, .text$foo
// contributes to .text, for example. See PE/COFF spec 3.2.
SmallDenseMap<StringRef, OutputSection *> Sections;
for (auto Pair : Map) {
StringRef Name = getOutputSection(Pair.first);
OutputSection *&Sec = Sections[Name];
if (!Sec) {
Sec = make<OutputSection>(Name);
OutputSections.push_back(Sec);
}
std::vector<Chunk *> &Chunks = Pair.second;
for (Chunk *C : Chunks) {
Sec->addChunk(C);
Sec->addPermissions(C->getPermissions());
}
}
}
void Writer::createMiscChunks() {
OutputSection *RData = createSection(".rdata");
// Create thunks for locally-dllimported symbols.
if (!Symtab->LocalImportChunks.empty()) {
for (Chunk *C : Symtab->LocalImportChunks)
RData->addChunk(C);
}
// Create Debug Information Chunks
if (Config->Debug) {
DebugDirectory = make<DebugDirectoryChunk>(DebugRecords);
// TODO(compnerd) create a coffgrp entry if DebugType::CV is not enabled
if (Config->DebugTypes & static_cast<unsigned>(coff::DebugType::CV)) {
auto *Chunk = make<CVDebugRecordChunk>();
BuildId = Chunk;
DebugRecords.push_back(Chunk);
}
RData->addChunk(DebugDirectory);
for (Chunk *C : DebugRecords)
RData->addChunk(C);
}
// Create SEH table. x86-only.
if (Config->Machine != I386)
return;
std::set<Defined *> Handlers;
for (ObjFile *File : ObjFile::Instances) {
if (!File->SEHCompat)
return;
for (SymbolBody *B : File->SEHandlers) {
// Make sure the handler is still live. Assume all handlers are regular
// symbols.
auto *D = dyn_cast<DefinedRegular>(B);
if (D && D->getChunk()->isLive())
Handlers.insert(D);
}
}
if (!Handlers.empty()) {
SEHTable = make<SEHTableChunk>(Handlers);
RData->addChunk(SEHTable);
}
}
// Create .idata section for the DLL-imported symbol table.
// The format of this section is inherently Windows-specific.
// IdataContents class abstracted away the details for us,
// so we just let it create chunks and add them to the section.
void Writer::createImportTables() {
if (ImportFile::Instances.empty())
return;
// Initialize DLLOrder so that import entries are ordered in
// the same order as in the command line. (That affects DLL
// initialization order, and this ordering is MSVC-compatible.)
for (ImportFile *File : ImportFile::Instances) {
if (!File->Live)
continue;
std::string DLL = StringRef(File->DLLName).lower();
if (Config->DLLOrder.count(DLL) == 0)
Config->DLLOrder[DLL] = Config->DLLOrder.size();
}
OutputSection *Text = createSection(".text");
for (ImportFile *File : ImportFile::Instances) {
if (!File->Live)
continue;
if (DefinedImportThunk *Thunk = File->ThunkSym)
Text->addChunk(Thunk->getChunk());
if (Config->DelayLoads.count(StringRef(File->DLLName).lower())) {
if (!File->ThunkSym)
fatal("cannot delay-load " + toString(File) +
" due to import of data: " + toString(*File->ImpSym));
DelayIdata.add(File->ImpSym);
} else {
Idata.add(File->ImpSym);
}
}
if (!Idata.empty()) {
OutputSection *Sec = createSection(".idata");
for (Chunk *C : Idata.getChunks())
Sec->addChunk(C);
}
if (!DelayIdata.empty()) {
Defined *Helper = cast<Defined>(Config->DelayLoadHelper);
DelayIdata.create(Helper);
OutputSection *Sec = createSection(".didat");
for (Chunk *C : DelayIdata.getChunks())
Sec->addChunk(C);
Sec = createSection(".data");
for (Chunk *C : DelayIdata.getDataChunks())
Sec->addChunk(C);
Sec = createSection(".text");
for (Chunk *C : DelayIdata.getCodeChunks())
Sec->addChunk(C);
}
}
void Writer::createExportTable() {
if (Config->Exports.empty())
return;
OutputSection *Sec = createSection(".edata");
for (Chunk *C : Edata.Chunks)
Sec->addChunk(C);
}
// The Windows loader doesn't seem to like empty sections,
// so we remove them if any.
void Writer::removeEmptySections() {
auto IsEmpty = [](OutputSection *S) { return S->getVirtualSize() == 0; };
OutputSections.erase(
std::remove_if(OutputSections.begin(), OutputSections.end(), IsEmpty),
OutputSections.end());
uint32_t Idx = 1;
for (OutputSection *Sec : OutputSections)
Sec->SectionIndex = Idx++;
}
size_t Writer::addEntryToStringTable(StringRef Str) {
assert(Str.size() > COFF::NameSize);
size_t OffsetOfEntry = Strtab.size() + 4; // +4 for the size field
Strtab.insert(Strtab.end(), Str.begin(), Str.end());
Strtab.push_back('\0');
return OffsetOfEntry;
}
Optional<coff_symbol16> Writer::createSymbol(Defined *Def) {
// Relative symbols are unrepresentable in a COFF symbol table.
if (isa<DefinedSynthetic>(Def))
return None;
// Don't write dead symbols or symbols in codeview sections to the symbol
// table.
if (!Def->isLive())
return None;
if (auto *D = dyn_cast<DefinedRegular>(Def))
if (D->getChunk()->isCodeView())
return None;
coff_symbol16 Sym;
StringRef Name = Def->getName();
if (Name.size() > COFF::NameSize) {
Sym.Name.Offset.Zeroes = 0;
Sym.Name.Offset.Offset = addEntryToStringTable(Name);
} else {
memset(Sym.Name.ShortName, 0, COFF::NameSize);
memcpy(Sym.Name.ShortName, Name.data(), Name.size());
}
if (auto *D = dyn_cast<DefinedCOFF>(Def)) {
COFFSymbolRef Ref = D->getCOFFSymbol();
Sym.Type = Ref.getType();
Sym.StorageClass = Ref.getStorageClass();
} else {
Sym.Type = IMAGE_SYM_TYPE_NULL;
Sym.StorageClass = IMAGE_SYM_CLASS_EXTERNAL;
}
Sym.NumberOfAuxSymbols = 0;
switch (Def->kind()) {
case SymbolBody::DefinedAbsoluteKind:
Sym.Value = Def->getRVA();
Sym.SectionNumber = IMAGE_SYM_ABSOLUTE;
break;
default: {
uint64_t RVA = Def->getRVA();
OutputSection *Sec = nullptr;
for (OutputSection *S : OutputSections) {
if (S->getRVA() > RVA)
break;
Sec = S;
}
Sym.Value = RVA - Sec->getRVA();
Sym.SectionNumber = Sec->SectionIndex;
break;
}
}
return Sym;
}
void Writer::createSymbolAndStringTable() {
if (!Config->Debug || !Config->WriteSymtab)
return;
// Name field in the section table is 8 byte long. Longer names need
// to be written to the string table. First, construct string table.
for (OutputSection *Sec : OutputSections) {
StringRef Name = Sec->getName();
if (Name.size() <= COFF::NameSize)
continue;
Sec->setStringTableOff(addEntryToStringTable(Name));
}
for (ObjFile *File : ObjFile::Instances) {
for (SymbolBody *B : File->getSymbols()) {
auto *D = dyn_cast<Defined>(B);
if (!D || D->WrittenToSymtab)
continue;
D->WrittenToSymtab = true;
if (Optional<coff_symbol16> Sym = createSymbol(D))
OutputSymtab.push_back(*Sym);
}
}
OutputSection *LastSection = OutputSections.back();
// We position the symbol table to be adjacent to the end of the last section.
uint64_t FileOff = LastSection->getFileOff() +
alignTo(LastSection->getRawSize(), SectorSize);
if (!OutputSymtab.empty()) {
PointerToSymbolTable = FileOff;
FileOff += OutputSymtab.size() * sizeof(coff_symbol16);
}
if (!Strtab.empty())
FileOff += Strtab.size() + 4;
FileSize = alignTo(FileOff, SectorSize);
}
// Visits all sections to assign incremental, non-overlapping RVAs and
// file offsets.
void Writer::assignAddresses() {
SizeOfHeaders = DOSStubSize + sizeof(PEMagic) + sizeof(coff_file_header) +
sizeof(data_directory) * NumberfOfDataDirectory +
sizeof(coff_section) * OutputSections.size();
SizeOfHeaders +=
Config->is64() ? sizeof(pe32plus_header) : sizeof(pe32_header);
SizeOfHeaders = alignTo(SizeOfHeaders, SectorSize);
uint64_t RVA = 0x1000; // The first page is kept unmapped.
FileSize = SizeOfHeaders;
// Move DISCARDABLE (or non-memory-mapped) sections to the end of file because
// the loader cannot handle holes.
std::stable_partition(
OutputSections.begin(), OutputSections.end(), [](OutputSection *S) {
return (S->getPermissions() & IMAGE_SCN_MEM_DISCARDABLE) == 0;
});
for (OutputSection *Sec : OutputSections) {
if (Sec->getName() == ".reloc")
addBaserels(Sec);
Sec->setRVA(RVA);
Sec->setFileOffset(FileSize);
RVA += alignTo(Sec->getVirtualSize(), PageSize);
FileSize += alignTo(Sec->getRawSize(), SectorSize);
}
SizeOfImage = SizeOfHeaders + alignTo(RVA - 0x1000, PageSize);
}
template <typename PEHeaderTy> void Writer::writeHeader() {
// Write DOS stub
uint8_t *Buf = Buffer->getBufferStart();
auto *DOS = reinterpret_cast<dos_header *>(Buf);
Buf += DOSStubSize;
DOS->Magic[0] = 'M';
DOS->Magic[1] = 'Z';
DOS->AddressOfRelocationTable = sizeof(dos_header);
DOS->AddressOfNewExeHeader = DOSStubSize;
// Write PE magic
memcpy(Buf, PEMagic, sizeof(PEMagic));
Buf += sizeof(PEMagic);
// Write COFF header
auto *COFF = reinterpret_cast<coff_file_header *>(Buf);
Buf += sizeof(*COFF);
COFF->Machine = Config->Machine;
COFF->NumberOfSections = OutputSections.size();
COFF->Characteristics = IMAGE_FILE_EXECUTABLE_IMAGE;
if (Config->LargeAddressAware)
COFF->Characteristics |= IMAGE_FILE_LARGE_ADDRESS_AWARE;
if (!Config->is64())
COFF->Characteristics |= IMAGE_FILE_32BIT_MACHINE;
if (Config->DLL)
COFF->Characteristics |= IMAGE_FILE_DLL;
if (!Config->Relocatable)
COFF->Characteristics |= IMAGE_FILE_RELOCS_STRIPPED;
COFF->SizeOfOptionalHeader =
sizeof(PEHeaderTy) + sizeof(data_directory) * NumberfOfDataDirectory;
// Write PE header
auto *PE = reinterpret_cast<PEHeaderTy *>(Buf);
Buf += sizeof(*PE);
PE->Magic = Config->is64() ? PE32Header::PE32_PLUS : PE32Header::PE32;
// If {Major,Minor}LinkerVersion is left at 0.0, then for some
// reason signing the resulting PE file with Authenticode produces a
// signature that fails to validate on Windows 7 (but is OK on 10).
// Set it to 14.0, which is what VS2015 outputs, and which avoids
// that problem.
PE->MajorLinkerVersion = 14;
PE->MinorLinkerVersion = 0;
PE->ImageBase = Config->ImageBase;
PE->SectionAlignment = PageSize;
PE->FileAlignment = SectorSize;
PE->MajorImageVersion = Config->MajorImageVersion;
PE->MinorImageVersion = Config->MinorImageVersion;
PE->MajorOperatingSystemVersion = Config->MajorOSVersion;
PE->MinorOperatingSystemVersion = Config->MinorOSVersion;
PE->MajorSubsystemVersion = Config->MajorOSVersion;
PE->MinorSubsystemVersion = Config->MinorOSVersion;
PE->Subsystem = Config->Subsystem;
PE->SizeOfImage = SizeOfImage;
PE->SizeOfHeaders = SizeOfHeaders;
if (!Config->NoEntry) {
Defined *Entry = cast<Defined>(Config->Entry);
PE->AddressOfEntryPoint = Entry->getRVA();
// Pointer to thumb code must have the LSB set, so adjust it.
if (Config->Machine == ARMNT)
PE->AddressOfEntryPoint |= 1;
}
PE->SizeOfStackReserve = Config->StackReserve;
PE->SizeOfStackCommit = Config->StackCommit;
PE->SizeOfHeapReserve = Config->HeapReserve;
PE->SizeOfHeapCommit = Config->HeapCommit;
// Import Descriptor Tables and Import Address Tables are merged
// in our output. That's not compatible with the Binding feature
// that is sort of prelinking. Setting this flag to make it clear
// that our outputs are not for the Binding.
PE->DLLCharacteristics = IMAGE_DLL_CHARACTERISTICS_NO_BIND;
if (Config->AppContainer)
PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_APPCONTAINER;
if (Config->DynamicBase)
PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_DYNAMIC_BASE;
if (Config->HighEntropyVA)
PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_HIGH_ENTROPY_VA;
if (Config->NxCompat)
PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_NX_COMPAT;
if (!Config->AllowIsolation)
PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_NO_ISOLATION;
if (Config->TerminalServerAware)
PE->DLLCharacteristics |= IMAGE_DLL_CHARACTERISTICS_TERMINAL_SERVER_AWARE;
PE->NumberOfRvaAndSize = NumberfOfDataDirectory;
if (OutputSection *Text = findSection(".text")) {
PE->BaseOfCode = Text->getRVA();
PE->SizeOfCode = Text->getRawSize();
}
PE->SizeOfInitializedData = getSizeOfInitializedData();
// Write data directory
auto *Dir = reinterpret_cast<data_directory *>(Buf);
Buf += sizeof(*Dir) * NumberfOfDataDirectory;
if (OutputSection *Sec = findSection(".edata")) {
Dir[EXPORT_TABLE].RelativeVirtualAddress = Sec->getRVA();
Dir[EXPORT_TABLE].Size = Sec->getVirtualSize();
}
if (!Idata.empty()) {
Dir[IMPORT_TABLE].RelativeVirtualAddress = Idata.getDirRVA();
Dir[IMPORT_TABLE].Size = Idata.getDirSize();
Dir[IAT].RelativeVirtualAddress = Idata.getIATRVA();
Dir[IAT].Size = Idata.getIATSize();
}
if (OutputSection *Sec = findSection(".rsrc")) {
Dir[RESOURCE_TABLE].RelativeVirtualAddress = Sec->getRVA();
Dir[RESOURCE_TABLE].Size = Sec->getVirtualSize();
}
if (OutputSection *Sec = findSection(".pdata")) {
Dir[EXCEPTION_TABLE].RelativeVirtualAddress = Sec->getRVA();
Dir[EXCEPTION_TABLE].Size = Sec->getVirtualSize();
}
if (OutputSection *Sec = findSection(".reloc")) {
Dir[BASE_RELOCATION_TABLE].RelativeVirtualAddress = Sec->getRVA();
Dir[BASE_RELOCATION_TABLE].Size = Sec->getVirtualSize();
}
if (Symbol *Sym = Symtab->findUnderscore("_tls_used")) {
if (Defined *B = dyn_cast<Defined>(Sym->body())) {
Dir[TLS_TABLE].RelativeVirtualAddress = B->getRVA();
Dir[TLS_TABLE].Size = Config->is64()
? sizeof(object::coff_tls_directory64)
: sizeof(object::coff_tls_directory32);
}
}
if (Config->Debug) {
Dir[DEBUG_DIRECTORY].RelativeVirtualAddress = DebugDirectory->getRVA();
Dir[DEBUG_DIRECTORY].Size = DebugDirectory->getSize();
}
if (Symbol *Sym = Symtab->findUnderscore("_load_config_used")) {
if (auto *B = dyn_cast<DefinedRegular>(Sym->body())) {
SectionChunk *SC = B->getChunk();
assert(B->getRVA() >= SC->getRVA());
uint64_t OffsetInChunk = B->getRVA() - SC->getRVA();
if (!SC->hasData() || OffsetInChunk + 4 > SC->getSize())
fatal("_load_config_used is malformed");
ArrayRef<uint8_t> SecContents = SC->getContents();
uint32_t LoadConfigSize =
*reinterpret_cast<const ulittle32_t *>(&SecContents[OffsetInChunk]);
if (OffsetInChunk + LoadConfigSize > SC->getSize())
fatal("_load_config_used is too large");
Dir[LOAD_CONFIG_TABLE].RelativeVirtualAddress = B->getRVA();
Dir[LOAD_CONFIG_TABLE].Size = LoadConfigSize;
}
}
if (!DelayIdata.empty()) {
Dir[DELAY_IMPORT_DESCRIPTOR].RelativeVirtualAddress =
DelayIdata.getDirRVA();
Dir[DELAY_IMPORT_DESCRIPTOR].Size = DelayIdata.getDirSize();
}
// Write section table
for (OutputSection *Sec : OutputSections) {
Sec->writeHeaderTo(Buf);
Buf += sizeof(coff_section);
}
SectionTable = ArrayRef<uint8_t>(
Buf - OutputSections.size() * sizeof(coff_section), Buf);
if (OutputSymtab.empty())
return;
COFF->PointerToSymbolTable = PointerToSymbolTable;
uint32_t NumberOfSymbols = OutputSymtab.size();
COFF->NumberOfSymbols = NumberOfSymbols;
auto *SymbolTable = reinterpret_cast<coff_symbol16 *>(
Buffer->getBufferStart() + COFF->PointerToSymbolTable);
for (size_t I = 0; I != NumberOfSymbols; ++I)
SymbolTable[I] = OutputSymtab[I];
// Create the string table, it follows immediately after the symbol table.
// The first 4 bytes is length including itself.
Buf = reinterpret_cast<uint8_t *>(&SymbolTable[NumberOfSymbols]);
write32le(Buf, Strtab.size() + 4);
if (!Strtab.empty())
memcpy(Buf + 4, Strtab.data(), Strtab.size());
}
void Writer::openFile(StringRef Path) {
Buffer = check(
FileOutputBuffer::create(Path, FileSize, FileOutputBuffer::F_executable),
"failed to open " + Path);
}
void Writer::fixSafeSEHSymbols() {
if (!SEHTable)
return;
// Replace the absolute table symbol with a synthetic symbol pointing to the
// SEHTable chunk so that we can emit base relocations for it and resolve
// section relative relocations.
Symbol *T = Symtab->find("___safe_se_handler_table");
Symbol *C = Symtab->find("___safe_se_handler_count");
replaceBody<DefinedSynthetic>(T, T->body()->getName(), SEHTable);
cast<DefinedAbsolute>(C->body())->setVA(SEHTable->getSize() / 4);
}
// Handles /section options to allow users to overwrite
// section attributes.
void Writer::setSectionPermissions() {
for (auto &P : Config->Section) {
StringRef Name = P.first;
uint32_t Perm = P.second;
if (auto *Sec = findSection(Name))
Sec->setPermissions(Perm);
}
}
// Write section contents to a mmap'ed file.
void Writer::writeSections() {
// Record the section index that should be used when resolving a section
// relocation against an absolute symbol.
DefinedAbsolute::OutputSectionIndex = OutputSections.size() + 1;
uint8_t *Buf = Buffer->getBufferStart();
for (OutputSection *Sec : OutputSections) {
uint8_t *SecBuf = Buf + Sec->getFileOff();
// Fill gaps between functions in .text with INT3 instructions
// instead of leaving as NUL bytes (which can be interpreted as
// ADD instructions).
if (Sec->getPermissions() & IMAGE_SCN_CNT_CODE)
memset(SecBuf, 0xCC, Sec->getRawSize());
for_each(parallel::par, Sec->getChunks().begin(), Sec->getChunks().end(),
[&](Chunk *C) { C->writeTo(SecBuf); });
}
}
// Sort .pdata section contents according to PE/COFF spec 5.5.
void Writer::sortExceptionTable() {
OutputSection *Sec = findSection(".pdata");
if (!Sec)
return;
// We assume .pdata contains function table entries only.
uint8_t *Begin = Buffer->getBufferStart() + Sec->getFileOff();
uint8_t *End = Begin + Sec->getVirtualSize();
if (Config->Machine == AMD64) {
struct Entry { ulittle32_t Begin, End, Unwind; };
sort(parallel::par, (Entry *)Begin, (Entry *)End,
[](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
return;
}
if (Config->Machine == ARMNT) {
struct Entry { ulittle32_t Begin, Unwind; };
sort(parallel::par, (Entry *)Begin, (Entry *)End,
[](const Entry &A, const Entry &B) { return A.Begin < B.Begin; });
return;
}
errs() << "warning: don't know how to handle .pdata.\n";
}
// Backfill the CVSignature in a PDB70 Debug Record. This backfilling allows us
// to get reproducible builds.
void Writer::writeBuildId() {
// There is nothing to backfill if BuildId was not setup.
if (BuildId == nullptr)
return;
assert(BuildId->DI->Signature.CVSignature == OMF::Signature::PDB70 &&
"only PDB 7.0 is supported");
assert(sizeof(BuildId->DI->PDB70.Signature) == 16 &&
"signature size mismatch");
// Compute an MD5 hash.
ArrayRef<uint8_t> Buf(Buffer->getBufferStart(), Buffer->getBufferEnd());
memcpy(BuildId->DI->PDB70.Signature, MD5::hash(Buf).data(), 16);
// TODO(compnerd) track the Age
BuildId->DI->PDB70.Age = 1;
}
OutputSection *Writer::findSection(StringRef Name) {
for (OutputSection *Sec : OutputSections)
if (Sec->getName() == Name)
return Sec;
return nullptr;
}
uint32_t Writer::getSizeOfInitializedData() {
uint32_t Res = 0;
for (OutputSection *S : OutputSections)
if (S->getPermissions() & IMAGE_SCN_CNT_INITIALIZED_DATA)
Res += S->getRawSize();
return Res;
}
// Returns an existing section or create a new one if not found.
OutputSection *Writer::createSection(StringRef Name) {
if (auto *Sec = findSection(Name))
return Sec;
const auto DATA = IMAGE_SCN_CNT_INITIALIZED_DATA;
const auto BSS = IMAGE_SCN_CNT_UNINITIALIZED_DATA;
const auto CODE = IMAGE_SCN_CNT_CODE;
const auto DISCARDABLE = IMAGE_SCN_MEM_DISCARDABLE;
const auto R = IMAGE_SCN_MEM_READ;
const auto W = IMAGE_SCN_MEM_WRITE;
const auto X = IMAGE_SCN_MEM_EXECUTE;
uint32_t Perms = StringSwitch<uint32_t>(Name)
.Case(".bss", BSS | R | W)
.Case(".data", DATA | R | W)
.Cases(".didat", ".edata", ".idata", ".rdata", DATA | R)
.Case(".reloc", DATA | DISCARDABLE | R)
.Case(".text", CODE | R | X)
.Default(0);
if (!Perms)
llvm_unreachable("unknown section name");
auto Sec = make<OutputSection>(Name);
Sec->addPermissions(Perms);
OutputSections.push_back(Sec);
return Sec;
}
// Dest is .reloc section. Add contents to that section.
void Writer::addBaserels(OutputSection *Dest) {
std::vector<Baserel> V;
for (OutputSection *Sec : OutputSections) {
if (Sec == Dest)
continue;
// Collect all locations for base relocations.
for (Chunk *C : Sec->getChunks())
C->getBaserels(&V);
// Add the addresses to .reloc section.
if (!V.empty())
addBaserelBlocks(Dest, V);
V.clear();
}
}
// Add addresses to .reloc section. Note that addresses are grouped by page.
void Writer::addBaserelBlocks(OutputSection *Dest, std::vector<Baserel> &V) {
const uint32_t Mask = ~uint32_t(PageSize - 1);
uint32_t Page = V[0].RVA & Mask;
size_t I = 0, J = 1;
for (size_t E = V.size(); J < E; ++J) {
uint32_t P = V[J].RVA & Mask;
if (P == Page)
continue;
Dest->addChunk(make<BaserelChunk>(Page, &V[I], &V[0] + J));
I = J;
Page = P;
}
if (I == J)
return;
Dest->addChunk(make<BaserelChunk>(Page, &V[I], &V[0] + J));
}
Reference in New Issue View Git Blame Copy Permalink