Differential D13466 Diff 36568 head/contrib/llvm/tools/lld/ELF/Writer.cpp

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head/contrib/llvm/tools/lld/ELF/Writer.cpp

Show First 20 Lines • Show All 44 Lines • ▼ Show 20 Lines	public:

void run();		void run();

private:		private:
void clearOutputSections();		void clearOutputSections();
void createSyntheticSections();		void createSyntheticSections();
void copyLocalSymbols();		void copyLocalSymbols();
void addSectionSymbols();		void addSectionSymbols();
void addReservedSymbols();
void createSections();		void createSections();
void forEachRelSec(std::function<void(InputSectionBase &)> Fn);		void forEachRelSec(std::function<void(InputSectionBase &)> Fn);
void sortSections();		void sortSections();
void finalizeSections();		void finalizeSections();
void addPredefinedSections();		void addPredefinedSections();

std::vector<PhdrEntry> createPhdrs();		std::vector<PhdrEntry> createPhdrs();
void removeEmptyPTLoad();		void removeEmptyPTLoad();
▲ Show 20 Lines • Show All 101 Lines • ▼ Show 20 Lines
template <class ELFT> void Writer<ELFT>::run() {		template <class ELFT> void Writer<ELFT>::run() {
// Create linker-synthesized sections such as .got or .plt.		// Create linker-synthesized sections such as .got or .plt.
// Such sections are of type input section.		// Such sections are of type input section.
createSyntheticSections();		createSyntheticSections();

if (!Config->Relocatable)		if (!Config->Relocatable)
combineEhFrameSections<ELFT>();		combineEhFrameSections<ELFT>();

// We need to create some reserved symbols such as _end. Create them.
if (!Config->Relocatable)
addReservedSymbols();

// Create output sections.		// Create output sections.
if (Script->Opt.HasSections) {		if (Script->Opt.HasSections) {
// If linker script contains SECTIONS commands, let it create sections.		// If linker script contains SECTIONS commands, let it create sections.
Script->processCommands(Factory);		Script->processCommands(Factory);

// Linker scripts may have left some input sections unassigned.		// Linker scripts may have left some input sections unassigned.
// Assign such sections using the default rule.		// Assign such sections using the default rule.
Script->addOrphanSections(Factory);		Script->addOrphanSections(Factory);
▲ Show 20 Lines • Show All 98 Lines • ▼ Show 20 Lines	template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
auto Add = [](InputSectionBase *Sec) { InputSections.push_back(Sec); };		auto Add = [](InputSectionBase *Sec) { InputSections.push_back(Sec); };

InX::DynStrTab = make<StringTableSection>(".dynstr", true);		InX::DynStrTab = make<StringTableSection>(".dynstr", true);
InX::Dynamic = make<DynamicSection<ELFT>>();		InX::Dynamic = make<DynamicSection<ELFT>>();
In<ELFT>::RelaDyn = make<RelocationSection<ELFT>>(		In<ELFT>::RelaDyn = make<RelocationSection<ELFT>>(
Config->IsRela ? ".rela.dyn" : ".rel.dyn", Config->ZCombreloc);		Config->IsRela ? ".rela.dyn" : ".rel.dyn", Config->ZCombreloc);
InX::ShStrTab = make<StringTableSection>(".shstrtab", false);		InX::ShStrTab = make<StringTableSection>(".shstrtab", false);

Out::ElfHeader = make<OutputSection>("", 0, SHF_ALLOC);
Out::ElfHeader->Size = sizeof(Elf_Ehdr);
Out::ProgramHeaders = make<OutputSection>("", 0, SHF_ALLOC);		Out::ProgramHeaders = make<OutputSection>("", 0, SHF_ALLOC);
Out::ProgramHeaders->updateAlignment(Config->Wordsize);		Out::ProgramHeaders->updateAlignment(Config->Wordsize);

if (needsInterpSection<ELFT>()) {		if (needsInterpSection<ELFT>()) {
InX::Interp = createInterpSection();		InX::Interp = createInterpSection();
Add(InX::Interp);		Add(InX::Interp);
} else {		} else {
InX::Interp = nullptr;		InX::Interp = nullptr;
▲ Show 20 Lines • Show All 492 Lines • ▼ Show 20 Lines	template <class ELFT> void Writer<ELFT>::addRelIpltSymbols() {
addOptionalRegular<ELFT>(S, In<ELFT>::RelaIplt, 0, STV_HIDDEN, STB_WEAK);		addOptionalRegular<ELFT>(S, In<ELFT>::RelaIplt, 0, STV_HIDDEN, STB_WEAK);

S = Config->IsRela ? "__rela_iplt_end" : "__rel_iplt_end";		S = Config->IsRela ? "__rela_iplt_end" : "__rel_iplt_end";
addOptionalRegular<ELFT>(S, In<ELFT>::RelaIplt, -1, STV_HIDDEN, STB_WEAK);		addOptionalRegular<ELFT>(S, In<ELFT>::RelaIplt, -1, STV_HIDDEN, STB_WEAK);
}		}

// The linker is expected to define some symbols depending on		// The linker is expected to define some symbols depending on
// the linking result. This function defines such symbols.		// the linking result. This function defines such symbols.
template <class ELFT> void Writer<ELFT>::addReservedSymbols() {		template <class ELFT> void elf::addReservedSymbols() {
if (Config->EMachine == EM_MIPS) {		if (Config->EMachine == EM_MIPS) {
// Define _gp for MIPS. st_value of _gp symbol will be updated by Writer		// Define _gp for MIPS. st_value of _gp symbol will be updated by Writer
// so that it points to an absolute address which by default is relative		// so that it points to an absolute address which by default is relative
// to GOT. Default offset is 0x7ff0.		// to GOT. Default offset is 0x7ff0.
// See "Global Data Symbols" in Chapter 6 in the following document:		// See "Global Data Symbols" in Chapter 6 in the following document:
// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf		// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
ElfSym::MipsGp = Symtab<ELFT>::X->addAbsolute("_gp", STV_HIDDEN, STB_LOCAL);		ElfSym::MipsGp = Symtab<ELFT>::X->addAbsolute("_gp", STV_HIDDEN, STB_LOCAL);

// On MIPS O32 ABI, _gp_disp is a magic symbol designates offset between		// On MIPS O32 ABI, _gp_disp is a magic symbol designates offset between
// start of function and 'gp' pointer into GOT.		// start of function and 'gp' pointer into GOT.
if (Symtab<ELFT>::X->find("_gp_disp"))		if (Symtab<ELFT>::X->find("_gp_disp"))
ElfSym::MipsGpDisp =		ElfSym::MipsGpDisp =
Symtab<ELFT>::X->addAbsolute("_gp_disp", STV_HIDDEN, STB_LOCAL);		Symtab<ELFT>::X->addAbsolute("_gp_disp", STV_HIDDEN, STB_LOCAL);

// The __gnu_local_gp is a magic symbol equal to the current value of 'gp'		// The __gnu_local_gp is a magic symbol equal to the current value of 'gp'
// pointer. This symbol is used in the code generated by .cpload pseudo-op		// pointer. This symbol is used in the code generated by .cpload pseudo-op
// in case of using -mno-shared option.		// in case of using -mno-shared option.
// https://sourceware.org/ml/binutils/2004-12/msg00094.html		// https://sourceware.org/ml/binutils/2004-12/msg00094.html
if (Symtab<ELFT>::X->find("__gnu_local_gp"))		if (Symtab<ELFT>::X->find("__gnu_local_gp"))
ElfSym::MipsLocalGp =		ElfSym::MipsLocalGp =
Symtab<ELFT>::X->addAbsolute("__gnu_local_gp", STV_HIDDEN, STB_LOCAL);		Symtab<ELFT>::X->addAbsolute("__gnu_local_gp", STV_HIDDEN, STB_LOCAL);
}		}

// The _GLOBAL_OFFSET_TABLE_ symbol is defined by target convention to
// be at some offset from the base of the .got section, usually 0 or the end
// of the .got
InputSection *GotSection = InX::MipsGot ? cast<InputSection>(InX::MipsGot)
: cast<InputSection>(InX::Got);
ElfSym::GlobalOffsetTable = addOptionalRegular<ELFT>(		ElfSym::GlobalOffsetTable = addOptionalRegular<ELFT>(
"_GLOBAL_OFFSET_TABLE_", GotSection, Target->GotBaseSymOff);		"_GLOBAL_OFFSET_TABLE_", Out::ElfHeader, Target->GotBaseSymOff);

// __tls_get_addr is defined by the dynamic linker for dynamic ELFs. For
// static linking the linker is required to optimize away any references to
// __tls_get_addr, so it's not defined anywhere. Create a hidden definition
// to avoid the undefined symbol error.
if (!InX::DynSymTab)
Symtab<ELFT>::X->addIgnored("__tls_get_addr");

// __ehdr_start is the location of ELF file headers. Note that we define		// __ehdr_start is the location of ELF file headers. Note that we define
// this symbol unconditionally even when using a linker script, which		// this symbol unconditionally even when using a linker script, which
// differs from the behavior implemented by GNU linker which only define		// differs from the behavior implemented by GNU linker which only define
// this symbol if ELF headers are in the memory mapped segment.		// this symbol if ELF headers are in the memory mapped segment.
// __executable_start is not documented, but the expectation of at		// __executable_start is not documented, but the expectation of at
// least the android libc is that it points to the elf header too.		// least the android libc is that it points to the elf header too.
// __dso_handle symbol is passed to cxa_finalize as a marker to identify		// __dso_handle symbol is passed to cxa_finalize as a marker to identify
// each DSO. The address of the symbol doesn't matter as long as they are		// each DSO. The address of the symbol doesn't matter as long as they are
▲ Show 20 Lines • Show All 870 Lines • ▼ Show 20 Lines	if (Config->Relocatable)
return ET_REL;		return ET_REL;
return ET_EXEC;		return ET_EXEC;
}		}

// This function is called after we have assigned address and size		// This function is called after we have assigned address and size
// to each section. This function fixes some predefined		// to each section. This function fixes some predefined
// symbol values that depend on section address and size.		// symbol values that depend on section address and size.
template <class ELFT> void Writer<ELFT>::fixPredefinedSymbols() {		template <class ELFT> void Writer<ELFT>::fixPredefinedSymbols() {
		if (ElfSym::GlobalOffsetTable) {
		// The _GLOBAL_OFFSET_TABLE_ symbol is defined by target convention to
		// be at some offset from the base of the .got section, usually 0 or the end
		// of the .got
		InputSection *GotSection = InX::MipsGot ? cast<InputSection>(InX::MipsGot)
		: cast<InputSection>(InX::Got);
		ElfSym::GlobalOffsetTable->Section = GotSection;
		}

// _etext is the first location after the last read-only loadable segment.		// _etext is the first location after the last read-only loadable segment.
// _edata is the first location after the last read-write loadable segment.		// _edata is the first location after the last read-write loadable segment.
// _end is the first location after the uninitialized data region.		// _end is the first location after the uninitialized data region.
PhdrEntry *Last = nullptr;		PhdrEntry *Last = nullptr;
PhdrEntry *LastRO = nullptr;		PhdrEntry *LastRO = nullptr;
PhdrEntry *LastRW = nullptr;		PhdrEntry *LastRW = nullptr;
for (PhdrEntry &P : Phdrs) {		for (PhdrEntry &P : Phdrs) {
if (P.p_type != PT_LOAD)		if (P.p_type != PT_LOAD)
▲ Show 20 Lines • Show All 174 Lines • ▼ Show 20 Lines	template <class ELFT> void Writer<ELFT>::writeBuildId() {
uint8_t *End = Start + FileSize;		uint8_t *End = Start + FileSize;
InX::BuildId->writeBuildId({Start, End});		InX::BuildId->writeBuildId({Start, End});
}		}

template void elf::writeResult<ELF32LE>();		template void elf::writeResult<ELF32LE>();
template void elf::writeResult<ELF32BE>();		template void elf::writeResult<ELF32BE>();
template void elf::writeResult<ELF64LE>();		template void elf::writeResult<ELF64LE>();
template void elf::writeResult<ELF64BE>();		template void elf::writeResult<ELF64BE>();

		template void elf::addReservedSymbols<ELF32LE>();
		template void elf::addReservedSymbols<ELF32BE>();
		template void elf::addReservedSymbols<ELF64LE>();
		template void elf::addReservedSymbols<ELF64BE>();