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llvm / llvm-project / 15d1ee36720ff24323f55452ae3cfb63f318c3f3 / . / lld / lib / ReaderWriter / MachO / MachONormalizedFileFromAtoms.cpp
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//===- lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file Converts from in-memory Atoms to in-memory normalized mach-o.
///
/// +------------+
/// | normalized |
/// +------------+
/// ^
/// |
/// |
/// +-------+
/// | Atoms |
/// +-------+
#include "ArchHandler.h"
#include "DebugInfo.h"
#include "MachONormalizedFile.h"
#include "MachONormalizedFileBinaryUtils.h"
#include "lld/Common/LLVM.h"
#include "lld/Core/Error.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include <map>
#include <system_error>
#include <unordered_set>
using llvm::StringRef;
using llvm::isa;
using namespace llvm::MachO;
using namespace lld::mach_o::normalized;
using namespace lld;
namespace {
struct AtomInfo {
const DefinedAtom *atom;
uint64_t offsetInSection;
};
struct SectionInfo {
SectionInfo(StringRef seg, StringRef sect, SectionType type,
const MachOLinkingContext &ctxt, uint32_t attr,
bool relocsToDefinedCanBeImplicit);
StringRef segmentName;
StringRef sectionName;
SectionType type;
uint32_t attributes;
uint64_t address;
uint64_t size;
uint16_t alignment;
/// If this is set, the any relocs in this section which point to defined
/// addresses can be implicitly generated. This is the case for the
/// __eh_frame section where references to the function can be implicit if the
/// function is defined.
bool relocsToDefinedCanBeImplicit;
std::vector<AtomInfo> atomsAndOffsets;
uint32_t normalizedSectionIndex;
uint32_t finalSectionIndex;
};
SectionInfo::SectionInfo(StringRef sg, StringRef sct, SectionType t,
const MachOLinkingContext &ctxt, uint32_t attrs,
bool relocsToDefinedCanBeImplicit)
: segmentName(sg), sectionName(sct), type(t), attributes(attrs),
address(0), size(0), alignment(1),
relocsToDefinedCanBeImplicit(relocsToDefinedCanBeImplicit),
normalizedSectionIndex(0), finalSectionIndex(0) {
uint16_t align = 1;
if (ctxt.sectionAligned(segmentName, sectionName, align)) {
alignment = align;
}
}
struct SegmentInfo {
SegmentInfo(StringRef name);
StringRef name;
uint64_t address;
uint64_t size;
uint32_t init_access;
uint32_t max_access;
std::vector<SectionInfo*> sections;
uint32_t normalizedSegmentIndex;
};
SegmentInfo::SegmentInfo(StringRef n)
: name(n), address(0), size(0), init_access(0), max_access(0),
normalizedSegmentIndex(0) {
}
class Util {
public:
Util(const MachOLinkingContext &ctxt)
: _ctx(ctxt), _archHandler(ctxt.archHandler()), _entryAtom(nullptr),
_hasTLVDescriptors(false), _subsectionsViaSymbols(true) {}
~Util();
void processDefinedAtoms(const lld::File &atomFile);
void processAtomAttributes(const DefinedAtom *atom);
void assignAtomToSection(const DefinedAtom *atom);
void organizeSections();
void assignAddressesToSections(const NormalizedFile &file);
uint32_t fileFlags();
void copySegmentInfo(NormalizedFile &file);
void copySectionInfo(NormalizedFile &file);
void updateSectionInfo(NormalizedFile &file);
void buildAtomToAddressMap();
llvm::Error synthesizeDebugNotes(NormalizedFile &file);
llvm::Error addSymbols(const lld::File &atomFile, NormalizedFile &file);
void addIndirectSymbols(const lld::File &atomFile, NormalizedFile &file);
void addRebaseAndBindingInfo(const lld::File &, NormalizedFile &file);
void addExportInfo(const lld::File &, NormalizedFile &file);
void addSectionRelocs(const lld::File &, NormalizedFile &file);
void addFunctionStarts(const lld::File &, NormalizedFile &file);
void buildDataInCodeArray(const lld::File &, NormalizedFile &file);
void addDependentDylibs(const lld::File &, NormalizedFile &file);
void copyEntryPointAddress(NormalizedFile &file);
void copySectionContent(NormalizedFile &file);
bool allSourceFilesHaveMinVersions() const {
return _allSourceFilesHaveMinVersions;
}
uint32_t minVersion() const {
return _minVersion;
}
LoadCommandType minVersionCommandType() const {
return _minVersionCommandType;
}
private:
typedef std::map<DefinedAtom::ContentType, SectionInfo*> TypeToSection;
typedef llvm::DenseMap<const Atom*, uint64_t> AtomToAddress;
struct DylibInfo { int ordinal; bool hasWeak; bool hasNonWeak; };
typedef llvm::StringMap<DylibInfo> DylibPathToInfo;
SectionInfo *sectionForAtom(const DefinedAtom*);
SectionInfo *getRelocatableSection(DefinedAtom::ContentType type);
SectionInfo *getFinalSection(DefinedAtom::ContentType type);
void appendAtom(SectionInfo *sect, const DefinedAtom *atom);
SegmentInfo *segmentForName(StringRef segName);
void layoutSectionsInSegment(SegmentInfo *seg, uint64_t &addr);
void layoutSectionsInTextSegment(size_t, SegmentInfo *, uint64_t &);
void copySectionContent(SectionInfo *si, ContentBytes &content);
uint16_t descBits(const DefinedAtom* atom);
int dylibOrdinal(const SharedLibraryAtom *sa);
void segIndexForSection(const SectionInfo *sect,
uint8_t &segmentIndex, uint64_t &segmentStartAddr);
const Atom *targetOfLazyPointer(const DefinedAtom *lpAtom);
const Atom *targetOfStub(const DefinedAtom *stubAtom);
llvm::Error getSymbolTableRegion(const DefinedAtom* atom,
bool &inGlobalsRegion,
SymbolScope &symbolScope);
void appendSection(SectionInfo *si, NormalizedFile &file);
uint32_t sectionIndexForAtom(const Atom *atom);
void fixLazyReferenceImm(const DefinedAtom *atom, uint32_t offset,
NormalizedFile &file);
typedef llvm::DenseMap<const Atom*, uint32_t> AtomToIndex;
struct AtomAndIndex { const Atom *atom; uint32_t index; SymbolScope scope; };
struct AtomSorter {
bool operator()(const AtomAndIndex &left, const AtomAndIndex &right);
};
struct SegmentSorter {
bool operator()(const SegmentInfo *left, const SegmentInfo *right);
static unsigned weight(const SegmentInfo *);
};
struct TextSectionSorter {
bool operator()(const SectionInfo *left, const SectionInfo *right);
static unsigned weight(const SectionInfo *);
};
const MachOLinkingContext &_ctx;
mach_o::ArchHandler &_archHandler;
llvm::BumpPtrAllocator _allocator;
std::vector<SectionInfo*> _sectionInfos;
std::vector<SegmentInfo*> _segmentInfos;
TypeToSection _sectionMap;
std::vector<SectionInfo*> _customSections;
AtomToAddress _atomToAddress;
DylibPathToInfo _dylibInfo;
const DefinedAtom *_entryAtom;
AtomToIndex _atomToSymbolIndex;
std::vector<const Atom *> _machHeaderAliasAtoms;
bool _hasTLVDescriptors;
bool _subsectionsViaSymbols;
bool _allSourceFilesHaveMinVersions = true;
LoadCommandType _minVersionCommandType = (LoadCommandType)0;
uint32_t _minVersion = 0;
std::vector<lld::mach_o::Stab> _stabs;
};
Util::~Util() {
// The SectionInfo structs are BumpPtr allocated, but atomsAndOffsets needs
// to be deleted.
for (SectionInfo *si : _sectionInfos) {
// clear() destroys vector elements, but does not deallocate.
// Instead use swap() to deallocate vector buffer.
std::vector<AtomInfo> empty;
si->atomsAndOffsets.swap(empty);
}
// The SegmentInfo structs are BumpPtr allocated, but sections needs
// to be deleted.
for (SegmentInfo *sgi : _segmentInfos) {
std::vector<SectionInfo*> empty2;
sgi->sections.swap(empty2);
}
}
SectionInfo *Util::getRelocatableSection(DefinedAtom::ContentType type) {
StringRef segmentName;
StringRef sectionName;
SectionType sectionType;
SectionAttr sectionAttrs;
bool relocsToDefinedCanBeImplicit;
// Use same table used by when parsing .o files.
relocatableSectionInfoForContentType(type, segmentName, sectionName,
sectionType, sectionAttrs,
relocsToDefinedCanBeImplicit);
// If we already have a SectionInfo with this name, re-use it.
// This can happen if two ContentType map to the same mach-o section.
for (auto sect : _sectionMap) {
if (sect.second->sectionName.equals(sectionName) &&
sect.second->segmentName.equals(segmentName)) {
return sect.second;
}
}
// Otherwise allocate new SectionInfo object.
auto *sect = new (_allocator)
SectionInfo(segmentName, sectionName, sectionType, _ctx, sectionAttrs,
relocsToDefinedCanBeImplicit);
_sectionInfos.push_back(sect);
_sectionMap[type] = sect;
return sect;
}
#define ENTRY(seg, sect, type, atomType) \
{seg, sect, type, DefinedAtom::atomType }
struct MachOFinalSectionFromAtomType {
StringRef segmentName;
StringRef sectionName;
SectionType sectionType;
DefinedAtom::ContentType atomType;
};
const MachOFinalSectionFromAtomType sectsToAtomType[] = {
ENTRY("__TEXT", "__text", S_REGULAR, typeCode),
ENTRY("__TEXT", "__text", S_REGULAR, typeMachHeader),
ENTRY("__TEXT", "__cstring", S_CSTRING_LITERALS, typeCString),
ENTRY("__TEXT", "__ustring", S_REGULAR, typeUTF16String),
ENTRY("__TEXT", "__const", S_REGULAR, typeConstant),
ENTRY("__TEXT", "__const", S_4BYTE_LITERALS, typeLiteral4),
ENTRY("__TEXT", "__const", S_8BYTE_LITERALS, typeLiteral8),
ENTRY("__TEXT", "__const", S_16BYTE_LITERALS, typeLiteral16),
ENTRY("__TEXT", "__stubs", S_SYMBOL_STUBS, typeStub),
ENTRY("__TEXT", "__stub_helper", S_REGULAR, typeStubHelper),
ENTRY("__TEXT", "__gcc_except_tab", S_REGULAR, typeLSDA),
ENTRY("__TEXT", "__eh_frame", S_COALESCED, typeCFI),
ENTRY("__TEXT", "__unwind_info", S_REGULAR, typeProcessedUnwindInfo),
ENTRY("__DATA", "__data", S_REGULAR, typeData),
ENTRY("__DATA", "__const", S_REGULAR, typeConstData),
ENTRY("__DATA", "__cfstring", S_REGULAR, typeCFString),
ENTRY("__DATA", "__la_symbol_ptr", S_LAZY_SYMBOL_POINTERS,
typeLazyPointer),
ENTRY("__DATA", "__mod_init_func", S_MOD_INIT_FUNC_POINTERS,
typeInitializerPtr),
ENTRY("__DATA", "__mod_term_func", S_MOD_TERM_FUNC_POINTERS,
typeTerminatorPtr),
ENTRY("__DATA", "__got", S_NON_LAZY_SYMBOL_POINTERS,
typeGOT),
ENTRY("__DATA", "__nl_symbol_ptr", S_NON_LAZY_SYMBOL_POINTERS,
typeNonLazyPointer),
ENTRY("__DATA", "__thread_vars", S_THREAD_LOCAL_VARIABLES,
typeThunkTLV),
ENTRY("__DATA", "__thread_data", S_THREAD_LOCAL_REGULAR,
typeTLVInitialData),
ENTRY("__DATA", "__thread_ptrs", S_THREAD_LOCAL_VARIABLE_POINTERS,
typeTLVInitializerPtr),
ENTRY("__DATA", "__thread_bss", S_THREAD_LOCAL_ZEROFILL,
typeTLVInitialZeroFill),
ENTRY("__DATA", "__bss", S_ZEROFILL, typeZeroFill),
ENTRY("__DATA", "__interposing", S_INTERPOSING, typeInterposingTuples),
};
#undef ENTRY
SectionInfo *Util::getFinalSection(DefinedAtom::ContentType atomType) {
for (auto &p : sectsToAtomType) {
if (p.atomType != atomType)
continue;
SectionAttr sectionAttrs = 0;
switch (atomType) {
case DefinedAtom::typeMachHeader:
case DefinedAtom::typeCode:
case DefinedAtom::typeStub:
case DefinedAtom::typeStubHelper:
sectionAttrs = S_ATTR_PURE_INSTRUCTIONS | S_ATTR_SOME_INSTRUCTIONS;
break;
case DefinedAtom::typeThunkTLV:
_hasTLVDescriptors = true;
break;
default:
break;
}
// If we already have a SectionInfo with this name, re-use it.
// This can happen if two ContentType map to the same mach-o section.
for (auto sect : _sectionMap) {
if (sect.second->sectionName.equals(p.sectionName) &&
sect.second->segmentName.equals(p.segmentName)) {
return sect.second;
}
}
// Otherwise allocate new SectionInfo object.
auto *sect = new (_allocator) SectionInfo(
p.segmentName, p.sectionName, p.sectionType, _ctx, sectionAttrs,
/* relocsToDefinedCanBeImplicit */ false);
_sectionInfos.push_back(sect);
_sectionMap[atomType] = sect;
return sect;
}
llvm_unreachable("content type not yet supported");
}
SectionInfo *Util::sectionForAtom(const DefinedAtom *atom) {
if (atom->sectionChoice() == DefinedAtom::sectionBasedOnContent) {
// Section for this atom is derived from content type.
DefinedAtom::ContentType type = atom->contentType();
auto pos = _sectionMap.find(type);
if ( pos != _sectionMap.end() )
return pos->second;
bool rMode = (_ctx.outputMachOType() == llvm::MachO::MH_OBJECT);
return rMode ? getRelocatableSection(type) : getFinalSection(type);
} else {
// This atom needs to be in a custom section.
StringRef customName = atom->customSectionName();
// Look to see if we have already allocated the needed custom section.
for(SectionInfo *sect : _customSections) {
const DefinedAtom *firstAtom = sect->atomsAndOffsets.front().atom;
if (firstAtom->customSectionName().equals(customName)) {
return sect;
}
}
// Not found, so need to create a new custom section.
size_t seperatorIndex = customName.find('/');
assert(seperatorIndex != StringRef::npos);
StringRef segName = customName.slice(0, seperatorIndex);
StringRef sectName = customName.drop_front(seperatorIndex + 1);
auto *sect =
new (_allocator) SectionInfo(segName, sectName, S_REGULAR, _ctx,
0, /* relocsToDefinedCanBeImplicit */ false);
_customSections.push_back(sect);
_sectionInfos.push_back(sect);
return sect;
}
}
void Util::appendAtom(SectionInfo *sect, const DefinedAtom *atom) {
// Figure out offset for atom in this section given alignment constraints.
uint64_t offset = sect->size;
DefinedAtom::Alignment atomAlign = atom->alignment();
uint64_t align = atomAlign.value;
uint64_t requiredModulus = atomAlign.modulus;
uint64_t currentModulus = (offset % align);
if ( currentModulus != requiredModulus ) {
if ( requiredModulus > currentModulus )
offset += requiredModulus-currentModulus;
else
offset += align+requiredModulus-currentModulus;
}
// Record max alignment of any atom in this section.
if (align > sect->alignment)
sect->alignment = atomAlign.value;
// Assign atom to this section with this offset.
AtomInfo ai = {atom, offset};
sect->atomsAndOffsets.push_back(ai);
// Update section size to include this atom.
sect->size = offset + atom->size();
}
void Util::processDefinedAtoms(const lld::File &atomFile) {
for (const DefinedAtom *atom : atomFile.defined()) {
processAtomAttributes(atom);
assignAtomToSection(atom);
}
}
void Util::processAtomAttributes(const DefinedAtom *atom) {
if (auto *machoFile = dyn_cast<mach_o::MachOFile>(&atom->file())) {
// If the file doesn't use subsections via symbols, then make sure we don't
// add that flag to the final output file if we have a relocatable file.
if (!machoFile->subsectionsViaSymbols())
_subsectionsViaSymbols = false;
// All the source files must have min versions for us to output an object
// file with a min version.
if (auto v = machoFile->minVersion())
_minVersion = std::max(_minVersion, v);
else
_allSourceFilesHaveMinVersions = false;
// If we don't have a platform load command, but one of the source files
// does, then take the one from the file.
if (!_minVersionCommandType)
if (auto v = machoFile->minVersionLoadCommandKind())
_minVersionCommandType = v;
}
}
void Util::assignAtomToSection(const DefinedAtom *atom) {
if (atom->contentType() == DefinedAtom::typeMachHeader) {
_machHeaderAliasAtoms.push_back(atom);
// Assign atom to this section with this offset.
AtomInfo ai = {atom, 0};
sectionForAtom(atom)->atomsAndOffsets.push_back(ai);
} else if (atom->contentType() == DefinedAtom::typeDSOHandle)
_machHeaderAliasAtoms.push_back(atom);
else
appendAtom(sectionForAtom(atom), atom);
}
SegmentInfo *Util::segmentForName(StringRef segName) {
for (SegmentInfo *si : _segmentInfos) {
if ( si->name.equals(segName) )
return si;
}
auto *info = new (_allocator) SegmentInfo(segName);
// Set the initial segment protection.
if (segName.equals("__TEXT"))
info->init_access = VM_PROT_READ | VM_PROT_EXECUTE;
else if (segName.equals("__PAGEZERO"))
info->init_access = 0;
else if (segName.equals("__LINKEDIT"))
info->init_access = VM_PROT_READ;
else {
// All others default to read-write
info->init_access = VM_PROT_READ | VM_PROT_WRITE;
}
// Set max segment protection
// Note, its overkill to use a switch statement here, but makes it so much
// easier to use switch coverage to catch new cases.
switch (_ctx.os()) {
case lld::MachOLinkingContext::OS::unknown:
case lld::MachOLinkingContext::OS::macOSX:
case lld::MachOLinkingContext::OS::iOS_simulator:
if (segName.equals("__PAGEZERO")) {
info->max_access = 0;
break;
}
// All others default to all
info->max_access = VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE;
break;
case lld::MachOLinkingContext::OS::iOS:
// iPhoneOS always uses same protection for max and initial
info->max_access = info->init_access;
break;
}
_segmentInfos.push_back(info);
return info;
}
unsigned Util::SegmentSorter::weight(const SegmentInfo *seg) {
return llvm::StringSwitch<unsigned>(seg->name)
.Case("__PAGEZERO", 1)
.Case("__TEXT", 2)
.Case("__DATA", 3)
.Default(100);
}
bool Util::SegmentSorter::operator()(const SegmentInfo *left,
const SegmentInfo *right) {
return (weight(left) < weight(right));
}
unsigned Util::TextSectionSorter::weight(const SectionInfo *sect) {
return llvm::StringSwitch<unsigned>(sect->sectionName)
.Case("__text", 1)
.Case("__stubs", 2)
.Case("__stub_helper", 3)
.Case("__const", 4)
.Case("__cstring", 5)
.Case("__unwind_info", 98)
.Case("__eh_frame", 99)
.Default(10);
}
bool Util::TextSectionSorter::operator()(const SectionInfo *left,
const SectionInfo *right) {
return (weight(left) < weight(right));
}
void Util::organizeSections() {
// NOTE!: Keep this in sync with assignAddressesToSections.
switch (_ctx.outputMachOType()) {
case llvm::MachO::MH_EXECUTE:
// Main executables, need a zero-page segment
segmentForName("__PAGEZERO");
// Fall into next case.
LLVM_FALLTHROUGH;
case llvm::MachO::MH_DYLIB:
case llvm::MachO::MH_BUNDLE:
// All dynamic code needs TEXT segment to hold the load commands.
segmentForName("__TEXT");
break;
default:
break;
}
segmentForName("__LINKEDIT");
// Group sections into segments.
for (SectionInfo *si : _sectionInfos) {
SegmentInfo *seg = segmentForName(si->segmentName);
seg->sections.push_back(si);
}
// Sort segments.
std::sort(_segmentInfos.begin(), _segmentInfos.end(), SegmentSorter());
// Sort sections within segments.
for (SegmentInfo *seg : _segmentInfos) {
if (seg->name.equals("__TEXT")) {
std::sort(seg->sections.begin(), seg->sections.end(),
TextSectionSorter());
}
}
// Record final section indexes.
uint32_t segmentIndex = 0;
uint32_t sectionIndex = 1;
for (SegmentInfo *seg : _segmentInfos) {
seg->normalizedSegmentIndex = segmentIndex++;
for (SectionInfo *sect : seg->sections)
sect->finalSectionIndex = sectionIndex++;
}
}
void Util::layoutSectionsInSegment(SegmentInfo *seg, uint64_t &addr) {
seg->address = addr;
for (SectionInfo *sect : seg->sections) {
sect->address = llvm::alignTo(addr, sect->alignment);
addr = sect->address + sect->size;
}
seg->size = llvm::alignTo(addr - seg->address, _ctx.pageSize());
}
// __TEXT segment lays out backwards so padding is at front after load commands.
void Util::layoutSectionsInTextSegment(size_t hlcSize, SegmentInfo *seg,
uint64_t &addr) {
seg->address = addr;
// Walks sections starting at end to calculate padding for start.
int64_t taddr = 0;
for (auto it = seg->sections.rbegin(); it != seg->sections.rend(); ++it) {
SectionInfo *sect = *it;
taddr -= sect->size;
taddr = taddr & (0 - sect->alignment);
}
int64_t padding = taddr - hlcSize;
while (padding < 0)
padding += _ctx.pageSize();
// Start assigning section address starting at padded offset.
addr += (padding + hlcSize);
for (SectionInfo *sect : seg->sections) {
sect->address = llvm::alignTo(addr, sect->alignment);
addr = sect->address + sect->size;
}
seg->size = llvm::alignTo(addr - seg->address, _ctx.pageSize());
}
void Util::assignAddressesToSections(const NormalizedFile &file) {
// NOTE!: Keep this in sync with organizeSections.
size_t hlcSize = headerAndLoadCommandsSize(file,
_ctx.generateFunctionStartsLoadCommand());
uint64_t address = 0;
for (SegmentInfo *seg : _segmentInfos) {
if (seg->name.equals("__PAGEZERO")) {
seg->size = _ctx.pageZeroSize();
address += seg->size;
}
else if (seg->name.equals("__TEXT")) {
// _ctx.baseAddress() == 0 implies it was either unspecified or
// pageZeroSize is also 0. In either case resetting address is safe.
address = _ctx.baseAddress() ? _ctx.baseAddress() : address;
layoutSectionsInTextSegment(hlcSize, seg, address);
} else
layoutSectionsInSegment(seg, address);
address = llvm::alignTo(address, _ctx.pageSize());
}
DEBUG_WITH_TYPE("WriterMachO-norm",
llvm::dbgs() << "assignAddressesToSections()\n";
for (SegmentInfo *sgi : _segmentInfos) {
llvm::dbgs() << " address=" << llvm::format("0x%08llX", sgi->address)
<< ", size=" << llvm::format("0x%08llX", sgi->size)
<< ", segment-name='" << sgi->name
<< "'\n";
for (SectionInfo *si : sgi->sections) {
llvm::dbgs()<< " addr=" << llvm::format("0x%08llX", si->address)
<< ", size=" << llvm::format("0x%08llX", si->size)
<< ", section-name='" << si->sectionName
<< "\n";
}
}
);
}
void Util::copySegmentInfo(NormalizedFile &file) {
for (SegmentInfo *sgi : _segmentInfos) {
Segment seg;
seg.name = sgi->name;
seg.address = sgi->address;
seg.size = sgi->size;
seg.init_access = sgi->init_access;
seg.max_access = sgi->max_access;
file.segments.push_back(seg);
}
}
void Util::appendSection(SectionInfo *si, NormalizedFile &file) {
// Add new empty section to end of file.sections.
Section temp;
file.sections.push_back(std::move(temp));
Section* normSect = &file.sections.back();
// Copy fields to normalized section.
normSect->segmentName = si->segmentName;
normSect->sectionName = si->sectionName;
normSect->type = si->type;
normSect->attributes = si->attributes;
normSect->address = si->address;
normSect->alignment = si->alignment;
// Record where normalized section is.
si->normalizedSectionIndex = file.sections.size()-1;
}
void Util::copySectionContent(NormalizedFile &file) {
const bool r = (_ctx.outputMachOType() == llvm::MachO::MH_OBJECT);
// Utility function for ArchHandler to find address of atom in output file.
auto addrForAtom = [&] (const Atom &atom) -> uint64_t {
auto pos = _atomToAddress.find(&atom);
assert(pos != _atomToAddress.end());
return pos->second;
};
auto sectionAddrForAtom = [&] (const Atom &atom) -> uint64_t {
for (const SectionInfo *sectInfo : _sectionInfos)
for (const AtomInfo &atomInfo : sectInfo->atomsAndOffsets)
if (atomInfo.atom == &atom)
return sectInfo->address;
llvm_unreachable("atom not assigned to section");
};
for (SectionInfo *si : _sectionInfos) {
Section *normSect = &file.sections[si->normalizedSectionIndex];
if (isZeroFillSection(si->type)) {
const uint8_t *empty = nullptr;
normSect->content = llvm::makeArrayRef(empty, si->size);
continue;
}
// Copy content from atoms to content buffer for section.
llvm::MutableArrayRef<uint8_t> sectionContent;
if (si->size) {
uint8_t *sectContent = file.ownedAllocations.Allocate<uint8_t>(si->size);
sectionContent = llvm::MutableArrayRef<uint8_t>(sectContent, si->size);
normSect->content = sectionContent;
}
for (AtomInfo &ai : si->atomsAndOffsets) {
if (!ai.atom->size()) {
assert(ai.atom->begin() == ai.atom->end() &&
"Cannot have references without content");
continue;
}
auto atomContent = sectionContent.slice(ai.offsetInSection,
ai.atom->size());
_archHandler.generateAtomContent(*ai.atom, r, addrForAtom,
sectionAddrForAtom, _ctx.baseAddress(),
atomContent);
}
}
}
void Util::copySectionInfo(NormalizedFile &file) {
file.sections.reserve(_sectionInfos.size());
// Write sections grouped by segment.
for (SegmentInfo *sgi : _segmentInfos) {
for (SectionInfo *si : sgi->sections) {
appendSection(si, file);
}
}
}
void Util::updateSectionInfo(NormalizedFile &file) {
file.sections.reserve(_sectionInfos.size());
// sections grouped by segment.
for (SegmentInfo *sgi : _segmentInfos) {
Segment *normSeg = &file.segments[sgi->normalizedSegmentIndex];
normSeg->address = sgi->address;
normSeg->size = sgi->size;
for (SectionInfo *si : sgi->sections) {
Section *normSect = &file.sections[si->normalizedSectionIndex];
normSect->address = si->address;
}
}
}
void Util::copyEntryPointAddress(NormalizedFile &nFile) {
if (!_entryAtom) {
nFile.entryAddress = 0;
return;
}
if (_ctx.outputTypeHasEntry()) {
if (_archHandler.isThumbFunction(*_entryAtom))
nFile.entryAddress = (_atomToAddress[_entryAtom] | 1);
else
nFile.entryAddress = _atomToAddress[_entryAtom];
}
}
void Util::buildAtomToAddressMap() {
DEBUG_WITH_TYPE("WriterMachO-address", llvm::dbgs()
<< "assign atom addresses:\n");
const bool lookForEntry = _ctx.outputTypeHasEntry();
for (SectionInfo *sect : _sectionInfos) {
for (const AtomInfo &info : sect->atomsAndOffsets) {
_atomToAddress[info.atom] = sect->address + info.offsetInSection;
if (lookForEntry && (info.atom->contentType() == DefinedAtom::typeCode) &&
(info.atom->size() != 0) &&
info.atom->name() == _ctx.entrySymbolName()) {
_entryAtom = info.atom;
}
DEBUG_WITH_TYPE("WriterMachO-address", llvm::dbgs()
<< " address="
<< llvm::format("0x%016X", _atomToAddress[info.atom])
<< llvm::format(" 0x%09lX", info.atom)
<< ", file=#"
<< info.atom->file().ordinal()
<< ", atom=#"
<< info.atom->ordinal()
<< ", name="
<< info.atom->name()
<< ", type="
<< info.atom->contentType()
<< "\n");
}
}
DEBUG_WITH_TYPE("WriterMachO-address", llvm::dbgs()
<< "assign header alias atom addresses:\n");
for (const Atom *atom : _machHeaderAliasAtoms) {
_atomToAddress[atom] = _ctx.baseAddress();
#ifndef NDEBUG
if (auto *definedAtom = dyn_cast<DefinedAtom>(atom)) {
DEBUG_WITH_TYPE("WriterMachO-address", llvm::dbgs()
<< " address="
<< llvm::format("0x%016X", _atomToAddress[atom])
<< llvm::format(" 0x%09lX", atom)
<< ", file=#"
<< definedAtom->file().ordinal()
<< ", atom=#"
<< definedAtom->ordinal()
<< ", name="
<< definedAtom->name()
<< ", type="
<< definedAtom->contentType()
<< "\n");
} else {
DEBUG_WITH_TYPE("WriterMachO-address", llvm::dbgs()
<< " address="
<< llvm::format("0x%016X", _atomToAddress[atom])
<< " atom=" << atom
<< " name=" << atom->name() << "\n");
}
#endif
}
}
llvm::Error Util::synthesizeDebugNotes(NormalizedFile &file) {
// Bail out early if we don't need to generate a debug map.
if (_ctx.debugInfoMode() == MachOLinkingContext::DebugInfoMode::noDebugMap)
return llvm::Error::success();
std::vector<const DefinedAtom*> atomsNeedingDebugNotes;
std::set<const mach_o::MachOFile*> filesWithStabs;
bool objFileHasDwarf = false;
const File *objFile = nullptr;
for (SectionInfo *sect : _sectionInfos) {
for (const AtomInfo &info : sect->atomsAndOffsets) {
if (const DefinedAtom *atom = dyn_cast<DefinedAtom>(info.atom)) {
// FIXME: No stabs/debug-notes for symbols that wouldn't be in the
// symbol table.
// FIXME: No stabs/debug-notes for kernel dtrace probes.
if (atom->contentType() == DefinedAtom::typeCFI ||
atom->contentType() == DefinedAtom::typeCString)
continue;
// Whenever we encounter a new file, update the 'objfileHasDwarf' flag.
if (&info.atom->file() != objFile) {
objFileHasDwarf = false;
if (const mach_o::MachOFile *atomFile =
dyn_cast<mach_o::MachOFile>(&info.atom->file())) {
if (atomFile->debugInfo()) {
if (isa<mach_o::DwarfDebugInfo>(atomFile->debugInfo()))
objFileHasDwarf = true;
else if (isa<mach_o::StabsDebugInfo>(atomFile->debugInfo()))
filesWithStabs.insert(atomFile);
}
}
}
// If this atom is from a file that needs dwarf, add it to the list.
if (objFileHasDwarf)
atomsNeedingDebugNotes.push_back(info.atom);
}
}
}
// Sort atoms needing debug notes by file ordinal, then atom ordinal.
std::sort(atomsNeedingDebugNotes.begin(), atomsNeedingDebugNotes.end(),
[](const DefinedAtom *lhs, const DefinedAtom *rhs) {
if (lhs->file().ordinal() != rhs->file().ordinal())
return (lhs->file().ordinal() < rhs->file().ordinal());
return (lhs->ordinal() < rhs->ordinal());
});
// FIXME: Handle <rdar://problem/17689030>: Add -add_ast_path option to \
// linker which add N_AST stab entry to output
// See OutputFile::synthesizeDebugNotes in ObjectFile.cpp in ld64.
StringRef oldFileName = "";
StringRef oldDirPath = "";
bool wroteStartSO = false;
std::unordered_set<std::string> seenFiles;
for (const DefinedAtom *atom : atomsNeedingDebugNotes) {
const auto &atomFile = cast<mach_o::MachOFile>(atom->file());
assert(dyn_cast_or_null<lld::mach_o::DwarfDebugInfo>(atomFile.debugInfo())
&& "file for atom needing debug notes does not contain dwarf");
auto &dwarf = cast<lld::mach_o::DwarfDebugInfo>(*atomFile.debugInfo());
auto &tu = dwarf.translationUnitSource();
StringRef newFileName = tu.name;
StringRef newDirPath = tu.path;
// Add an SO whenever the TU source file changes.
if (newFileName != oldFileName || newDirPath != oldDirPath) {
// Translation unit change, emit ending SO
if (oldFileName != "")
_stabs.push_back(mach_o::Stab(nullptr, N_SO, 1, 0, 0, ""));
oldFileName = newFileName;
oldDirPath = newDirPath;
// If newDirPath doesn't end with a '/' we need to add one:
if (newDirPath.back() != '/') {
char *p =
file.ownedAllocations.Allocate<char>(newDirPath.size() + 2);
memcpy(p, newDirPath.data(), newDirPath.size());
p[newDirPath.size()] = '/';
p[newDirPath.size() + 1] = '\0';
newDirPath = p;
}
// New translation unit, emit start SOs:
_stabs.push_back(mach_o::Stab(nullptr, N_SO, 0, 0, 0, newDirPath));
_stabs.push_back(mach_o::Stab(nullptr, N_SO, 0, 0, 0, newFileName));
// Synthesize OSO for start of file.
char *fullPath = nullptr;
{
SmallString<1024> pathBuf(atomFile.path());
if (auto EC = llvm::sys::fs::make_absolute(pathBuf))
return llvm::errorCodeToError(EC);
fullPath = file.ownedAllocations.Allocate<char>(pathBuf.size() + 1);
memcpy(fullPath, pathBuf.c_str(), pathBuf.size() + 1);
}
// Get mod time.
uint32_t modTime = 0;
llvm::sys::fs::file_status stat;
if (!llvm::sys::fs::status(fullPath, stat))
if (llvm::sys::fs::exists(stat))
modTime = llvm::sys::toTimeT(stat.getLastModificationTime());
_stabs.push_back(mach_o::Stab(nullptr, N_OSO, _ctx.getCPUSubType(), 1,
modTime, fullPath));
// <rdar://problem/6337329> linker should put cpusubtype in n_sect field
// of nlist entry for N_OSO debug note entries.
wroteStartSO = true;
}
if (atom->contentType() == DefinedAtom::typeCode) {
// Synthesize BNSYM and start FUN stabs.
_stabs.push_back(mach_o::Stab(atom, N_BNSYM, 1, 0, 0, ""));
_stabs.push_back(mach_o::Stab(atom, N_FUN, 1, 0, 0, atom->name()));
// Synthesize any SOL stabs needed
// FIXME: add SOL stabs.
_stabs.push_back(mach_o::Stab(nullptr, N_FUN, 0, 0,
atom->rawContent().size(), ""));
_stabs.push_back(mach_o::Stab(nullptr, N_ENSYM, 1, 0,
atom->rawContent().size(), ""));
} else {
if (atom->scope() == Atom::scopeTranslationUnit)
_stabs.push_back(mach_o::Stab(atom, N_STSYM, 1, 0, 0, atom->name()));
else
_stabs.push_back(mach_o::Stab(nullptr, N_GSYM, 1, 0, 0, atom->name()));
}
}
// Emit ending SO if necessary.
if (wroteStartSO)
_stabs.push_back(mach_o::Stab(nullptr, N_SO, 1, 0, 0, ""));
// Copy any stabs from .o file.
for (const auto *objFile : filesWithStabs) {
const auto &stabsList =
cast<mach_o::StabsDebugInfo>(objFile->debugInfo())->stabs();
for (auto &stab : stabsList) {
// FIXME: Drop stabs whose atoms have been dead-stripped.
_stabs.push_back(stab);
}
}
return llvm::Error::success();
}
uint16_t Util::descBits(const DefinedAtom* atom) {
uint16_t desc = 0;
switch (atom->merge()) {
case lld::DefinedAtom::mergeNo:
case lld::DefinedAtom::mergeAsTentative:
break;
case lld::DefinedAtom::mergeAsWeak:
case lld::DefinedAtom::mergeAsWeakAndAddressUsed:
desc |= N_WEAK_DEF;
break;
case lld::DefinedAtom::mergeSameNameAndSize:
case lld::DefinedAtom::mergeByLargestSection:
case lld::DefinedAtom::mergeByContent:
llvm_unreachable("Unsupported DefinedAtom::merge()");
break;
}
if (atom->contentType() == lld::DefinedAtom::typeResolver)
desc |= N_SYMBOL_RESOLVER;
if (atom->contentType() == lld::DefinedAtom::typeMachHeader)
desc |= REFERENCED_DYNAMICALLY;
if (_archHandler.isThumbFunction(*atom))
desc |= N_ARM_THUMB_DEF;
if (atom->deadStrip() == DefinedAtom::deadStripNever &&
_ctx.outputMachOType() == llvm::MachO::MH_OBJECT) {
if ((atom->contentType() != DefinedAtom::typeInitializerPtr)
&& (atom->contentType() != DefinedAtom::typeTerminatorPtr))
desc |= N_NO_DEAD_STRIP;
}
return desc;
}
bool Util::AtomSorter::operator()(const AtomAndIndex &left,
const AtomAndIndex &right) {
return (left.atom->name().compare(right.atom->name()) < 0);
}
llvm::Error Util::getSymbolTableRegion(const DefinedAtom* atom,
bool &inGlobalsRegion,
SymbolScope &scope) {
bool rMode = (_ctx.outputMachOType() == llvm::MachO::MH_OBJECT);
switch (atom->scope()) {
case Atom::scopeTranslationUnit:
scope = 0;
inGlobalsRegion = false;
return llvm::Error::success();
case Atom::scopeLinkageUnit:
if ((_ctx.exportMode() == MachOLinkingContext::ExportMode::exported) &&
_ctx.exportSymbolNamed(atom->name())) {
return llvm::make_error<GenericError>(
Twine("cannot export hidden symbol ") + atom->name());
}
if (rMode) {
if (_ctx.keepPrivateExterns()) {
// -keep_private_externs means keep in globals region as N_PEXT.
scope = N_PEXT | N_EXT;
inGlobalsRegion = true;
return llvm::Error::success();
}
}
// scopeLinkageUnit symbols are no longer global once linked.
scope = N_PEXT;
inGlobalsRegion = false;
return llvm::Error::success();
case Atom::scopeGlobal:
if (_ctx.exportRestrictMode()) {
if (_ctx.exportSymbolNamed(atom->name())) {
scope = N_EXT;
inGlobalsRegion = true;
return llvm::Error::success();
} else {
scope = N_PEXT;
inGlobalsRegion = false;
return llvm::Error::success();
}
} else {
scope = N_EXT;
inGlobalsRegion = true;
return llvm::Error::success();
}
break;
}
llvm_unreachable("atom->scope() unknown enum value");
}
llvm::Error Util::addSymbols(const lld::File &atomFile,
NormalizedFile &file) {
bool rMode = (_ctx.outputMachOType() == llvm::MachO::MH_OBJECT);
// Mach-O symbol table has four regions: stabs, locals, globals, undefs.
// Add all stabs.
for (auto &stab : _stabs) {
lld::mach_o::normalized::Symbol sym;
sym.type = static_cast<NListType>(stab.type);
sym.scope = 0;
sym.sect = stab.other;
sym.desc = stab.desc;
if (stab.atom)
sym.value = _atomToAddress[stab.atom];
else
sym.value = stab.value;
sym.name = stab.str;
file.stabsSymbols.push_back(sym);
}
// Add all local (non-global) symbols in address order
std::vector<AtomAndIndex> globals;
globals.reserve(512);
for (SectionInfo *sect : _sectionInfos) {
for (const AtomInfo &info : sect->atomsAndOffsets) {
const DefinedAtom *atom = info.atom;
if (!atom->name().empty()) {
SymbolScope symbolScope;
bool inGlobalsRegion;
if (auto ec = getSymbolTableRegion(atom, inGlobalsRegion, symbolScope)){
return ec;
}
if (inGlobalsRegion) {
AtomAndIndex ai = { atom, sect->finalSectionIndex, symbolScope };
globals.push_back(ai);
} else {
lld::mach_o::normalized::Symbol sym;
sym.name = atom->name();
sym.type = N_SECT;
sym.scope = symbolScope;
sym.sect = sect->finalSectionIndex;
sym.desc = descBits(atom);
sym.value = _atomToAddress[atom];
_atomToSymbolIndex[atom] = file.localSymbols.size();
file.localSymbols.push_back(sym);
}
} else if (rMode && _archHandler.needsLocalSymbolInRelocatableFile(atom)){
// Create 'Lxxx' labels for anonymous atoms if archHandler says so.
static unsigned tempNum = 1;
char tmpName[16];
sprintf(tmpName, "L%04u", tempNum++);
StringRef tempRef(tmpName);
lld::mach_o::normalized::Symbol sym;
sym.name = tempRef.copy(file.ownedAllocations);
sym.type = N_SECT;
sym.scope = 0;
sym.sect = sect->finalSectionIndex;
sym.desc = 0;
sym.value = _atomToAddress[atom];
_atomToSymbolIndex[atom] = file.localSymbols.size();
file.localSymbols.push_back(sym);
}
}
}
// Sort global symbol alphabetically, then add to symbol table.
std::sort(globals.begin(), globals.end(), AtomSorter());
const uint32_t globalStartIndex = file.localSymbols.size();
for (AtomAndIndex &ai : globals) {
lld::mach_o::normalized::Symbol sym;
sym.name = ai.atom->name();
sym.type = N_SECT;
sym.scope = ai.scope;
sym.sect = ai.index;
sym.desc = descBits(static_cast<const DefinedAtom*>(ai.atom));
sym.value = _atomToAddress[ai.atom];
_atomToSymbolIndex[ai.atom] = globalStartIndex + file.globalSymbols.size();
file.globalSymbols.push_back(sym);
}
// Sort undefined symbol alphabetically, then add to symbol table.
std::vector<AtomAndIndex> undefs;
undefs.reserve(128);
for (const UndefinedAtom *atom : atomFile.undefined()) {
AtomAndIndex ai = { atom, 0, N_EXT };
undefs.push_back(ai);
}
for (const SharedLibraryAtom *atom : atomFile.sharedLibrary()) {
AtomAndIndex ai = { atom, 0, N_EXT };
undefs.push_back(ai);
}
std::sort(undefs.begin(), undefs.end(), AtomSorter());
const uint32_t start = file.globalSymbols.size() + file.localSymbols.size();
for (AtomAndIndex &ai : undefs) {
lld::mach_o::normalized::Symbol sym;
uint16_t desc = 0;
if (!rMode) {
uint8_t ordinal = 0;
if (!_ctx.useFlatNamespace())
ordinal = dylibOrdinal(dyn_cast<SharedLibraryAtom>(ai.atom));
llvm::MachO::SET_LIBRARY_ORDINAL(desc, ordinal);
}
sym.name = ai.atom->name();
sym.type = N_UNDF;
sym.scope = ai.scope;
sym.sect = 0;
sym.desc = desc;
sym.value = 0;
_atomToSymbolIndex[ai.atom] = file.undefinedSymbols.size() + start;
file.undefinedSymbols.push_back(sym);
}
return llvm::Error::success();
}
const Atom *Util::targetOfLazyPointer(const DefinedAtom *lpAtom) {
for (const Reference *ref : *lpAtom) {
if (_archHandler.isLazyPointer(*ref)) {
return ref->target();
}
}
return nullptr;
}
const Atom *Util::targetOfStub(const DefinedAtom *stubAtom) {
for (const Reference *ref : *stubAtom) {
if (const Atom *ta = ref->target()) {
if (const DefinedAtom *lpAtom = dyn_cast<DefinedAtom>(ta)) {
const Atom *target = targetOfLazyPointer(lpAtom);
if (target)
return target;
}
}
}
return nullptr;
}
void Util::addIndirectSymbols(const lld::File &atomFile, NormalizedFile &file) {
for (SectionInfo *si : _sectionInfos) {
Section &normSect = file.sections[si->normalizedSectionIndex];
switch (si->type) {
case llvm::MachO::S_NON_LAZY_SYMBOL_POINTERS:
for (const AtomInfo &info : si->atomsAndOffsets) {
bool foundTarget = false;
for (const Reference *ref : *info.atom) {
const Atom *target = ref->target();
if (target) {
if (isa<const SharedLibraryAtom>(target)) {
uint32_t index = _atomToSymbolIndex[target];
normSect.indirectSymbols.push_back(index);
foundTarget = true;
} else {
normSect.indirectSymbols.push_back(
llvm::MachO::INDIRECT_SYMBOL_LOCAL);
}
}
}
if (!foundTarget) {
normSect.indirectSymbols.push_back(
llvm::MachO::INDIRECT_SYMBOL_ABS);
}
}
break;
case llvm::MachO::S_LAZY_SYMBOL_POINTERS:
for (const AtomInfo &info : si->atomsAndOffsets) {
const Atom *target = targetOfLazyPointer(info.atom);
if (target) {
uint32_t index = _atomToSymbolIndex[target];
normSect.indirectSymbols.push_back(index);
}
}
break;
case llvm::MachO::S_SYMBOL_STUBS:
for (const AtomInfo &info : si->atomsAndOffsets) {
const Atom *target = targetOfStub(info.atom);
if (target) {
uint32_t index = _atomToSymbolIndex[target];
normSect.indirectSymbols.push_back(index);
}
}
break;
default:
break;
}
}
}
void Util::addDependentDylibs(const lld::File &atomFile,
NormalizedFile &nFile) {
// Scan all imported symbols and build up list of dylibs they are from.
int ordinal = 1;
for (const auto *dylib : _ctx.allDylibs()) {
DylibPathToInfo::iterator pos = _dylibInfo.find(dylib->installName());
if (pos == _dylibInfo.end()) {
DylibInfo info;
bool flatNamespaceAtom = dylib == _ctx.flatNamespaceFile();
// If we're in -flat_namespace mode (or this atom came from the flat
// namespace file under -undefined dynamic_lookup) then use the flat
// lookup ordinal.
if (flatNamespaceAtom || _ctx.useFlatNamespace())
info.ordinal = BIND_SPECIAL_DYLIB_FLAT_LOOKUP;
else
info.ordinal = ordinal++;
info.hasWeak = false;
info.hasNonWeak = !info.hasWeak;
_dylibInfo[dylib->installName()] = info;
// Unless this was a flat_namespace atom, record the source dylib.
if (!flatNamespaceAtom) {
DependentDylib depInfo;
depInfo.path = dylib->installName();
depInfo.kind = llvm::MachO::LC_LOAD_DYLIB;
depInfo.currentVersion = _ctx.dylibCurrentVersion(dylib->path());
depInfo.compatVersion = _ctx.dylibCompatVersion(dylib->path());
nFile.dependentDylibs.push_back(depInfo);
}
} else {
pos->second.hasWeak = false;
pos->second.hasNonWeak = !pos->second.hasWeak;
}
}
// Automatically weak link dylib in which all symbols are weak (canBeNull).
for (DependentDylib &dep : nFile.dependentDylibs) {
DylibInfo &info = _dylibInfo[dep.path];
if (info.hasWeak && !info.hasNonWeak)
dep.kind = llvm::MachO::LC_LOAD_WEAK_DYLIB;
else if (_ctx.isUpwardDylib(dep.path))
dep.kind = llvm::MachO::LC_LOAD_UPWARD_DYLIB;
}
}
int Util::dylibOrdinal(const SharedLibraryAtom *sa) {
return _dylibInfo[sa->loadName()].ordinal;
}
void Util::segIndexForSection(const SectionInfo *sect, uint8_t &segmentIndex,
uint64_t &segmentStartAddr) {
segmentIndex = 0;
for (const SegmentInfo *seg : _segmentInfos) {
if ((seg->address <= sect->address)
&& (seg->address+seg->size >= sect->address+sect->size)) {
segmentStartAddr = seg->address;
return;
}
++segmentIndex;
}
llvm_unreachable("section not in any segment");
}
uint32_t Util::sectionIndexForAtom(const Atom *atom) {
uint64_t address = _atomToAddress[atom];
for (const SectionInfo *si : _sectionInfos) {
if ((si->address <= address) && (address < si->address+si->size))
return si->finalSectionIndex;
}
llvm_unreachable("atom not in any section");
}
void Util::addSectionRelocs(const lld::File &, NormalizedFile &file) {
if (_ctx.outputMachOType() != llvm::MachO::MH_OBJECT)
return;
// Utility function for ArchHandler to find symbol index for an atom.
auto symIndexForAtom = [&] (const Atom &atom) -> uint32_t {
auto pos = _atomToSymbolIndex.find(&atom);
assert(pos != _atomToSymbolIndex.end());
return pos->second;
};
// Utility function for ArchHandler to find section index for an atom.
auto sectIndexForAtom = [&] (const Atom &atom) -> uint32_t {
return sectionIndexForAtom(&atom);
};
// Utility function for ArchHandler to find address of atom in output file.
auto addressForAtom = [&] (const Atom &atom) -> uint64_t {
auto pos = _atomToAddress.find(&atom);
assert(pos != _atomToAddress.end());
return pos->second;
};
for (SectionInfo *si : _sectionInfos) {
Section &normSect = file.sections[si->normalizedSectionIndex];
for (const AtomInfo &info : si->atomsAndOffsets) {
const DefinedAtom *atom = info.atom;
for (const Reference *ref : *atom) {
// Skip emitting relocs for sections which are always able to be
// implicitly regenerated and where the relocation targets an address
// which is defined.
if (si->relocsToDefinedCanBeImplicit && isa<DefinedAtom>(ref->target()))
continue;
_archHandler.appendSectionRelocations(*atom, info.offsetInSection, *ref,
symIndexForAtom,
sectIndexForAtom,
addressForAtom,
normSect.relocations);
}
}
}
}
void Util::addFunctionStarts(const lld::File &, NormalizedFile &file) {
if (!_ctx.generateFunctionStartsLoadCommand())
return;
file.functionStarts.reserve(8192);
// Delta compress function starts, starting with the mach header symbol.
const uint64_t badAddress = ~0ULL;
uint64_t addr = badAddress;
for (SectionInfo *si : _sectionInfos) {
for (const AtomInfo &info : si->atomsAndOffsets) {
auto type = info.atom->contentType();
if (type == DefinedAtom::typeMachHeader) {
addr = _atomToAddress[info.atom];
continue;
}
if (type != DefinedAtom::typeCode)
continue;
assert(addr != badAddress && "Missing mach header symbol");
// Skip atoms which have 0 size. This is so that LC_FUNCTION_STARTS
// can't spill in to the next section.
if (!info.atom->size())
continue;
uint64_t nextAddr = _atomToAddress[info.atom];
if (_archHandler.isThumbFunction(*info.atom))
nextAddr |= 1;
uint64_t delta = nextAddr - addr;
if (delta) {
ByteBuffer buffer;
buffer.append_uleb128(delta);
file.functionStarts.insert(file.functionStarts.end(), buffer.bytes(),
buffer.bytes() + buffer.size());
}
addr = nextAddr;
}
}
// Null terminate, and pad to pointer size for this arch.
file.functionStarts.push_back(0);
auto size = file.functionStarts.size();
for (unsigned i = size, e = llvm::alignTo(size, _ctx.is64Bit() ? 8 : 4);
i != e; ++i)
file.functionStarts.push_back(0);
}
void Util::buildDataInCodeArray(const lld::File &, NormalizedFile &file) {
if (!_ctx.generateDataInCodeLoadCommand())
return;
for (SectionInfo *si : _sectionInfos) {
for (const AtomInfo &info : si->atomsAndOffsets) {
// Atoms that contain data-in-code have "transition" references
// which mark a point where the embedded data starts of ends.
// This needs to be converted to the mach-o format which is an array
// of data-in-code ranges.
uint32_t startOffset = 0;
DataRegionType mode = DataRegionType(0);
for (const Reference *ref : *info.atom) {
if (ref->kindNamespace() != Reference::KindNamespace::mach_o)
continue;
if (_archHandler.isDataInCodeTransition(ref->kindValue())) {
DataRegionType nextMode = (DataRegionType)ref->addend();
if (mode != nextMode) {
if (mode != 0) {
// Found end data range, so make range entry.
DataInCode entry;
entry.offset = si->address + info.offsetInSection + startOffset;
entry.length = ref->offsetInAtom() - startOffset;
entry.kind = mode;
file.dataInCode.push_back(entry);
}
}
mode = nextMode;
startOffset = ref->offsetInAtom();
}
}
if (mode != 0) {
// Function ends with data (no end transition).
DataInCode entry;
entry.offset = si->address + info.offsetInSection + startOffset;
entry.length = info.atom->size() - startOffset;
entry.kind = mode;
file.dataInCode.push_back(entry);
}
}
}
}
void Util::addRebaseAndBindingInfo(const lld::File &atomFile,
NormalizedFile &nFile) {
if (_ctx.outputMachOType() == llvm::MachO::MH_OBJECT)
return;
uint8_t segmentIndex;
uint64_t segmentStartAddr;
uint32_t offsetInBindInfo = 0;
for (SectionInfo *sect : _sectionInfos) {
segIndexForSection(sect, segmentIndex, segmentStartAddr);
for (const AtomInfo &info : sect->atomsAndOffsets) {
const DefinedAtom *atom = info.atom;
for (const Reference *ref : *atom) {
uint64_t segmentOffset = _atomToAddress[atom] + ref->offsetInAtom()
- segmentStartAddr;
const Atom* targ = ref->target();
if (_archHandler.isPointer(*ref)) {
// A pointer to a DefinedAtom requires rebasing.
if (isa<DefinedAtom>(targ)) {
RebaseLocation rebase;
rebase.segIndex = segmentIndex;
rebase.segOffset = segmentOffset;
rebase.kind = llvm::MachO::REBASE_TYPE_POINTER;
nFile.rebasingInfo.push_back(rebase);
}
// A pointer to an SharedLibraryAtom requires binding.
if (const SharedLibraryAtom *sa = dyn_cast<SharedLibraryAtom>(targ)) {
BindLocation bind;
bind.segIndex = segmentIndex;
bind.segOffset = segmentOffset;
bind.kind = llvm::MachO::BIND_TYPE_POINTER;
bind.canBeNull = sa->canBeNullAtRuntime();
bind.ordinal = dylibOrdinal(sa);
bind.symbolName = targ->name();
bind.addend = ref->addend();
nFile.bindingInfo.push_back(bind);
}
}
else if (_archHandler.isLazyPointer(*ref)) {
BindLocation bind;
if (const SharedLibraryAtom *sa = dyn_cast<SharedLibraryAtom>(targ)) {
bind.ordinal = dylibOrdinal(sa);
} else {
bind.ordinal = llvm::MachO::BIND_SPECIAL_DYLIB_SELF;
}
bind.segIndex = segmentIndex;
bind.segOffset = segmentOffset;
bind.kind = llvm::MachO::BIND_TYPE_POINTER;
bind.canBeNull = false; //sa->canBeNullAtRuntime();
bind.symbolName = targ->name();
bind.addend = ref->addend();
nFile.lazyBindingInfo.push_back(bind);
// Now that we know the segmentOffset and the ordinal attribute,
// we can fix the helper's code
fixLazyReferenceImm(atom, offsetInBindInfo, nFile);
// 5 bytes for opcodes + variable sizes (target name + \0 and offset
// encode's size)
offsetInBindInfo +=
6 + targ->name().size() + llvm::getULEB128Size(bind.segOffset);
if (bind.ordinal > BIND_IMMEDIATE_MASK)
offsetInBindInfo += llvm::getULEB128Size(bind.ordinal);
}
}
}
}
}
void Util::fixLazyReferenceImm(const DefinedAtom *atom, uint32_t offset,
NormalizedFile &file) {
for (const Reference *ref : *atom) {
const DefinedAtom *da = dyn_cast<DefinedAtom>(ref->target());
if (da == nullptr)
return;
const Reference *helperRef = nullptr;
for (const Reference *hr : *da) {
if (hr->kindValue() == _archHandler.lazyImmediateLocationKind()) {
helperRef = hr;
break;
}
}
if (helperRef == nullptr)
continue;
// TODO: maybe get the fixed atom content from _archHandler ?
for (SectionInfo *sectInfo : _sectionInfos) {
for (const AtomInfo &atomInfo : sectInfo->atomsAndOffsets) {
if (atomInfo.atom == helperRef->target()) {
auto sectionContent =
file.sections[sectInfo->normalizedSectionIndex].content;
uint8_t *rawb =
file.ownedAllocations.Allocate<uint8_t>(sectionContent.size());
llvm::MutableArrayRef<uint8_t> newContent{rawb,
sectionContent.size()};
std::copy(sectionContent.begin(), sectionContent.end(),
newContent.begin());
llvm::support::ulittle32_t *loc =
reinterpret_cast<llvm::support::ulittle32_t *>(
&newContent[atomInfo.offsetInSection +
helperRef->offsetInAtom()]);
*loc = offset;
file.sections[sectInfo->normalizedSectionIndex].content = newContent;
}
}
}
}
}
void Util::addExportInfo(const lld::File &atomFile, NormalizedFile &nFile) {
if (_ctx.outputMachOType() == llvm::MachO::MH_OBJECT)
return;
for (SectionInfo *sect : _sectionInfos) {
for (const AtomInfo &info : sect->atomsAndOffsets) {
const DefinedAtom *atom = info.atom;
if (atom->scope() != Atom::scopeGlobal)
continue;
if (_ctx.exportRestrictMode()) {
if (!_ctx.exportSymbolNamed(atom->name()))
continue;
}
Export exprt;
exprt.name = atom->name();
exprt.offset = _atomToAddress[atom] - _ctx.baseAddress();
exprt.kind = EXPORT_SYMBOL_FLAGS_KIND_REGULAR;
if (atom->merge() == DefinedAtom::mergeAsWeak)
exprt.flags = EXPORT_SYMBOL_FLAGS_WEAK_DEFINITION;
else
exprt.flags = 0;
exprt.otherOffset = 0;
exprt.otherName = StringRef();
nFile.exportInfo.push_back(exprt);
}
}
}
uint32_t Util::fileFlags() {
// FIXME: these need to determined at runtime.
if (_ctx.outputMachOType() == MH_OBJECT) {
return _subsectionsViaSymbols ? (uint32_t)MH_SUBSECTIONS_VIA_SYMBOLS : 0;
} else {
uint32_t flags = MH_DYLDLINK;
if (!_ctx.useFlatNamespace())
flags |= MH_TWOLEVEL | MH_NOUNDEFS;
if ((_ctx.outputMachOType() == MH_EXECUTE) && _ctx.PIE())
flags |= MH_PIE;
if (_hasTLVDescriptors)
flags |= (MH_PIE | MH_HAS_TLV_DESCRIPTORS);
return flags;
}
}
} // end anonymous namespace
namespace lld {
namespace mach_o {
namespace normalized {
/// Convert a set of Atoms into a normalized mach-o file.
llvm::Expected<std::unique_ptr<NormalizedFile>>
normalizedFromAtoms(const lld::File &atomFile,
const MachOLinkingContext &context) {
// The util object buffers info until the normalized file can be made.
Util util(context);
util.processDefinedAtoms(atomFile);
util.organizeSections();
std::unique_ptr<NormalizedFile> f(new NormalizedFile());
NormalizedFile &normFile = *f.get();
normFile.arch = context.arch();
normFile.fileType = context.outputMachOType();
normFile.flags = util.fileFlags();
normFile.stackSize = context.stackSize();
normFile.installName = context.installName();
normFile.currentVersion = context.currentVersion();
normFile.compatVersion = context.compatibilityVersion();
normFile.os = context.os();
// If we are emitting an object file, then the min version is the maximum
// of the min's of all the source files and the cmdline.
if (normFile.fileType == llvm::MachO::MH_OBJECT)
normFile.minOSverson = std::max(context.osMinVersion(), util.minVersion());
else
normFile.minOSverson = context.osMinVersion();
normFile.minOSVersionKind = util.minVersionCommandType();
normFile.sdkVersion = context.sdkVersion();
normFile.sourceVersion = context.sourceVersion();
if (context.generateVersionLoadCommand() &&
context.os() != MachOLinkingContext::OS::unknown)
normFile.hasMinVersionLoadCommand = true;
else if (normFile.fileType == llvm::MachO::MH_OBJECT &&
util.allSourceFilesHaveMinVersions() &&
((normFile.os != MachOLinkingContext::OS::unknown) ||
util.minVersionCommandType())) {
// If we emit an object file, then it should contain a min version load
// command if all of the source files also contained min version commands.
// Also, we either need to have a platform, or found a platform from the
// source object files.
normFile.hasMinVersionLoadCommand = true;
}
normFile.generateDataInCodeLoadCommand =
context.generateDataInCodeLoadCommand();
normFile.pageSize = context.pageSize();
normFile.rpaths = context.rpaths();
util.addDependentDylibs(atomFile, normFile);
util.copySegmentInfo(normFile);
util.copySectionInfo(normFile);
util.assignAddressesToSections(normFile);
util.buildAtomToAddressMap();
if (auto err = util.synthesizeDebugNotes(normFile))
return std::move(err);
util.updateSectionInfo(normFile);
util.copySectionContent(normFile);
if (auto ec = util.addSymbols(atomFile, normFile)) {
return std::move(ec);
}
util.addIndirectSymbols(atomFile, normFile);
util.addRebaseAndBindingInfo(atomFile, normFile);
util.addExportInfo(atomFile, normFile);
util.addSectionRelocs(atomFile, normFile);
util.addFunctionStarts(atomFile, normFile);
util.buildDataInCodeArray(atomFile, normFile);
util.copyEntryPointAddress(normFile);
return std::move(f);
}
} // namespace normalized
} // namespace mach_o
} // namespace lld