[llvm] r337204 - [llvm-objcopy] Add support for large indexes
Chandler Carruth via llvm-commits
llvm-commits at lists.llvm.org
Mon Jul 16 15:24:35 PDT 2018
This breaks platforms with python3 I think. We need python to be in the
compatible space between 2.7 and 3.
On Mon, Jul 16, 2018 at 12:54 PM Jake Ehrlich via llvm-commits <
llvm-commits at lists.llvm.org> wrote:
> Author: jakehehrlich
> Date: Mon Jul 16 12:48:52 2018
> New Revision: 337204
>
> URL: http://llvm.org/viewvc/llvm-project?rev=337204&view=rev
> Log:
> [llvm-objcopy] Add support for large indexes
>
> This patch is an update of an older patch that never landed
> (see here: https://reviews.llvm.org/D42516)
>
> Recently various users have run into this issue and it just 100%
> has to be solved at this point. The main difference in this patch
> is that I use gunzip instead of unzip which should hopefully allow
> tests to pass. Please review this as if it is a new patch however.
> I found some issues along the way and made some minor modifications.
>
> The binary used in this patch for testing (a zip file to make it small)
> can be found here:
>
> https://drive.google.com/file/d/1UjsnTO9edLttZibbr-2T1bJl92KEQFAO/view?usp=sharing
>
> Differential Revision: https://reviews.llvm.org/D49206
>
> Added:
> llvm/trunk/test/tools/llvm-objcopy/Inputs/many-sections.o.gz (with
> props)
> llvm/trunk/test/tools/llvm-objcopy/Inputs/ungzip.py
> llvm/trunk/test/tools/llvm-objcopy/auto-remove-shndx.test
> llvm/trunk/test/tools/llvm-objcopy/many-sections.test
> llvm/trunk/test/tools/llvm-objcopy/remove-shndx.test
> llvm/trunk/test/tools/llvm-objcopy/strict-no-add.test
> Modified:
> llvm/trunk/tools/llvm-objcopy/Object.cpp
> llvm/trunk/tools/llvm-objcopy/Object.h
>
> Added: llvm/trunk/test/tools/llvm-objcopy/Inputs/many-sections.o.gz
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/Inputs/many-sections.o.gz?rev=337204&view=auto
>
> ==============================================================================
> Binary file - no diff available.
>
> Propchange: llvm/trunk/test/tools/llvm-objcopy/Inputs/many-sections.o.gz
>
> ------------------------------------------------------------------------------
> svn:mime-type = application/octet-stream
>
> Added: llvm/trunk/test/tools/llvm-objcopy/Inputs/ungzip.py
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/Inputs/ungzip.py?rev=337204&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-objcopy/Inputs/ungzip.py (added)
> +++ llvm/trunk/test/tools/llvm-objcopy/Inputs/ungzip.py Mon Jul 16
> 12:48:52 2018
> @@ -0,0 +1,5 @@
> +import gzip
> +import sys
> +
> +with gzip.open(sys.argv[1], 'rb') as f:
> + sys.stdout.write(f.read())
>
> Added: llvm/trunk/test/tools/llvm-objcopy/auto-remove-shndx.test
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/auto-remove-shndx.test?rev=337204&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-objcopy/auto-remove-shndx.test (added)
> +++ llvm/trunk/test/tools/llvm-objcopy/auto-remove-shndx.test Mon Jul 16
> 12:48:52 2018
> @@ -0,0 +1,5 @@
> +# RUN: python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
> +# RUN: llvm-objcopy -R .text -R s0 -R s1 -R s2 -R s3 -R s4 -R s5 -R s6 %t
> %t2
> +# RUN: llvm-readobj -sections %t2 | FileCheck --check-prefix=SECS %s
> +
> +# SECS-NOT: Name: .symtab_shndx
>
> Added: llvm/trunk/test/tools/llvm-objcopy/many-sections.test
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/many-sections.test?rev=337204&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-objcopy/many-sections.test (added)
> +++ llvm/trunk/test/tools/llvm-objcopy/many-sections.test Mon Jul 16
> 12:48:52 2018
> @@ -0,0 +1,53 @@
> +RUN: python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
> +RUN: llvm-objcopy %t %t2
> +RUN: llvm-readobj -file-headers %t2 | FileCheck --check-prefix=EHDR %s
> +RUN: llvm-readobj -sections %t2 | FileCheck --check-prefix=SECS %s
> +RUN: llvm-readobj -symbols %t2 | grep "Symbol {" | wc -l | FileCheck
> --check-prefix=SYMS %s
> +
> +EHDR: Format: ELF64-x86-64
> +EHDR-NEXT: Arch: x86_64
> +EHDR-NEXT: AddressSize: 64bit
> +EHDR-NEXT: LoadName:
> +EHDR-NEXT: ElfHeader {
> +EHDR-NEXT: Ident {
> +EHDR-NEXT: Magic: (7F 45 4C 46)
> +EHDR-NEXT: Class: 64-bit (0x2)
> +EHDR-NEXT: DataEncoding: LittleEndian (0x1)
> +EHDR-NEXT: FileVersion: 1
> +EHDR-NEXT: OS/ABI: SystemV (0x0)
> +EHDR-NEXT: ABIVersion: 0
> +EHDR-NEXT: Unused: (00 00 00 00 00 00 00)
> +EHDR-NEXT: }
> +EHDR-NEXT: Type: Relocatable (0x1)
> +EHDR-NEXT: Machine: EM_X86_64 (0x3E)
> +EHDR-NEXT: Version: 1
> +EHDR-NEXT: Entry: 0x0
> +EHDR-NEXT: ProgramHeaderOffset: 0x40
> +EHDR-NEXT: SectionHeaderOffset:
> +EHDR-NEXT: Flags [ (0x0)
> +EHDR-NEXT: ]
> +EHDR-NEXT: HeaderSize: 64
> +EHDR-NEXT: ProgramHeaderEntrySize: 56
> +EHDR-NEXT: ProgramHeaderCount: 0
> +EHDR-NEXT: SectionHeaderEntrySize: 64
> +EHDR-NEXT: SectionHeaderCount: 0
> +EHDR-NEXT: StringTableSectionIndex: 65535
> +EHDR-NEXT: }
> +
> +SECS: Index: 65285
> +SECS-NEXT: Name: .symtab
> +SECS-NEXT: Type: SHT_SYMTAB
> +SECS: Name: .symtab_shndx
> +SECS-NEXT: Type: SHT_SYMTAB_SHNDX
> +SECS-NEXT: Flags [ (0x0)
> +SECS-NEXT: ]
> +SECS-NEXT: Address: 0x0
> +SECS-NEXT: Offset:
> +# There should be #syms * EntrySize bytes.
> +SECS-NEXT: Size: 261136
> +SECS-NEXT: Link: 65285
> +SECS-NEXT: Info:
> +SECS-NEXT: AddressAlignment: 4
> +SECS-NEXT: EntrySize: 4
> +SECS: Index: 65287
> +SYMS: 65284
>
> Added: llvm/trunk/test/tools/llvm-objcopy/remove-shndx.test
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/remove-shndx.test?rev=337204&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-objcopy/remove-shndx.test (added)
> +++ llvm/trunk/test/tools/llvm-objcopy/remove-shndx.test Mon Jul 16
> 12:48:52 2018
> @@ -0,0 +1,7 @@
> +# This test checks to see that a .symtab_shndx section is added to any
> binary
> +# that needs it, even if the original was removed.
> +RUN: python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
> +RUN: llvm-objcopy -R .symtab_shndx %t %t2
> +RUN: llvm-readobj -sections %t2 | FileCheck %s
> +
> +CHECK: Name: .symtab_shndx (
>
> Added: llvm/trunk/test/tools/llvm-objcopy/strict-no-add.test
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/strict-no-add.test?rev=337204&view=auto
>
> ==============================================================================
> --- llvm/trunk/test/tools/llvm-objcopy/strict-no-add.test (added)
> +++ llvm/trunk/test/tools/llvm-objcopy/strict-no-add.test Mon Jul 16
> 12:48:52 2018
> @@ -0,0 +1,10 @@
> +# This test makes sure that sections added at the end that don't have
> symbols
> +# defined in them don't trigger the creation of a large index table.
> +
> +RUN: python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t.0
> +RUN: cat %p/Inputs/alloc-symtab.o > %t
> +RUN: llvm-objcopy -R .text -R s0 -R s1 -R s2 -R s3 -R s4 -R s5 -R s6 %t.0
> %t2
> +RUN: llvm-objcopy -add-section=.s0=%t -add-section=.s1=%t
> -add-section=.s2=%t %t2 %t2
> +RUN: llvm-readobj -sections %t2 | FileCheck --check-prefix=SECS %s
> +
> +SECS-NOT: Name: .symtab_shndx
>
> Modified: llvm/trunk/tools/llvm-objcopy/Object.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/Object.cpp?rev=337204&r1=337203&r2=337204&view=diff
>
> ==============================================================================
> --- llvm/trunk/tools/llvm-objcopy/Object.cpp (original)
> +++ llvm/trunk/tools/llvm-objcopy/Object.cpp Mon Jul 16 12:48:52 2018
> @@ -101,6 +101,10 @@ template <class ELFT> void ELFWriter<ELF
>
> SectionVisitor::~SectionVisitor() {}
>
> +void BinarySectionWriter::visit(const SectionIndexSection &Sec) {
> + error("Cannot write symbol section index table '" + Sec.Name + "' ");
> +}
> +
> void BinarySectionWriter::visit(const SymbolTableSection &Sec) {
> error("Cannot write symbol table '" + Sec.Name + "' out to binary");
> }
> @@ -154,6 +158,29 @@ void StringTableSection::accept(SectionV
> Visitor.visit(*this);
> }
>
> +template <class ELFT>
> +void ELFSectionWriter<ELFT>::visit(const SectionIndexSection &Sec) {
> + uint8_t *Buf = Out.getBufferStart() + Sec.Offset;
> + auto *IndexesBuffer = reinterpret_cast<typename ELFT::Word *>(Buf);
> + std::copy(std::begin(Sec.Indexes), std::end(Sec.Indexes),
> IndexesBuffer);
> +}
> +
> +void SectionIndexSection::initialize(SectionTableRef SecTable) {
> + Size = 0;
> + setSymTab(SecTable.getSectionOfType<SymbolTableSection>(
> + Link,
> + "Link field value " + Twine(Link) + " in section " + Name + " is
> invalid",
> + "Link field value " + Twine(Link) + " in section " + Name +
> + " is not a symbol table"));
> + Symbols->setShndxTable(this);
> +}
> +
> +void SectionIndexSection::finalize() { Link = Symbols->Index; }
> +
> +void SectionIndexSection::accept(SectionVisitor &Visitor) const {
> + Visitor.visit(*this);
> +}
> +
> static bool isValidReservedSectionIndex(uint16_t Index, uint16_t Machine)
> {
> switch (Index) {
> case SHN_ABS:
> @@ -172,8 +199,13 @@ static bool isValidReservedSectionIndex(
> return false;
> }
>
> +// Large indexes force us to clarify exactly what this function should
> do. This
> +// function should return the value that will appear in st_shndx when
> written
> +// out.
> uint16_t Symbol::getShndx() const {
> if (DefinedIn != nullptr) {
> + if (DefinedIn->Index >= SHN_LORESERVE)
> + return SHN_XINDEX;
> return DefinedIn->Index;
> }
> switch (ShndxType) {
> @@ -187,6 +219,7 @@ uint16_t Symbol::getShndx() const {
> case SYMBOL_HEXAGON_SCOMMON_2:
> case SYMBOL_HEXAGON_SCOMMON_4:
> case SYMBOL_HEXAGON_SCOMMON_8:
> + case SYMBOL_XINDEX:
> return static_cast<uint16_t>(ShndxType);
> }
> llvm_unreachable("Symbol with invalid ShndxType encountered");
> @@ -207,6 +240,8 @@ void SymbolTableSection::addSymbol(Strin
> Sym.Binding = Bind;
> Sym.Type = Type;
> Sym.DefinedIn = DefinedIn;
> + if (DefinedIn != nullptr)
> + DefinedIn->HasSymbol = true;
> if (DefinedIn == nullptr) {
> if (Shndx >= SHN_LORESERVE)
> Sym.ShndxType = static_cast<SymbolShndxType>(Shndx);
> @@ -222,6 +257,8 @@ void SymbolTableSection::addSymbol(Strin
> }
>
> void SymbolTableSection::removeSectionReferences(const SectionBase *Sec) {
> + if (SectionIndexTable == Sec)
> + SectionIndexTable = nullptr;
> if (SymbolNames == Sec) {
> error("String table " + SymbolNames->Name +
> " cannot be removed because it is referenced by the symbol
> table " +
> @@ -274,7 +311,17 @@ void SymbolTableSection::finalize() {
> Info = MaxLocalIndex + 1;
> }
>
> -void SymbolTableSection::addSymbolNames() {
> +void SymbolTableSection::prepareForLayout() {
> + // Add all potential section indexes before file layout so that the
> section
> + // index section has the approprite size.
> + if (SectionIndexTable != nullptr) {
> + for (const auto &Sym : Symbols) {
> + if (Sym->DefinedIn != nullptr && Sym->DefinedIn->Index >=
> SHN_LORESERVE)
> + SectionIndexTable->addIndex(Sym->DefinedIn->Index);
> + else
> + SectionIndexTable->addIndex(SHN_UNDEF);
> + }
> + }
> // Add all of our strings to SymbolNames so that SymbolNames has the
> right
> // size before layout is decided.
> for (auto &Sym : Symbols)
> @@ -654,12 +701,32 @@ template <class ELFT>
> void ELFBuilder<ELFT>::initSymbolTable(SymbolTableSection *SymTab) {
> const Elf_Shdr &Shdr =
> *unwrapOrError(ElfFile.getSection(SymTab->Index));
> StringRef StrTabData =
> unwrapOrError(ElfFile.getStringTableForSymtab(Shdr));
> + ArrayRef<Elf_Word> ShndxData;
>
> - for (const auto &Sym : unwrapOrError(ElfFile.symbols(&Shdr))) {
> + auto Symbols = unwrapOrError(ElfFile.symbols(&Shdr));
> + for (const auto &Sym : Symbols) {
> SectionBase *DefSection = nullptr;
> StringRef Name = unwrapOrError(Sym.getName(StrTabData));
>
> - if (Sym.st_shndx >= SHN_LORESERVE) {
> + if (Sym.st_shndx == SHN_XINDEX) {
> + if (SymTab->getShndxTable() == nullptr)
> + error("Symbol '" + Name +
> + "' has index SHN_XINDEX but no SHT_SYMTAB_SHNDX section
> exists.");
> + if (ShndxData.data() == nullptr) {
> + const Elf_Shdr &ShndxSec =
> +
> *unwrapOrError(ElfFile.getSection(SymTab->getShndxTable()->Index));
> + ShndxData = unwrapOrError(
> + ElfFile.template
> getSectionContentsAsArray<Elf_Word>(&ShndxSec));
> + if (ShndxData.size() != Symbols.size())
> + error("Symbol section index table does not have the same number
> of "
> + "entries as the symbol table.");
> + }
> + Elf_Word Index = ShndxData[&Sym - Symbols.begin()];
> + DefSection = Obj.sections().getSection(
> + Index,
> + "Symbol '" + Name + "' has invalid section index " +
> + Twine(Index));
> + } else if (Sym.st_shndx >= SHN_LORESERVE) {
> if (!isValidReservedSectionIndex(Sym.st_shndx, Obj.Machine)) {
> error(
> "Symbol '" + Name +
> @@ -669,7 +736,7 @@ void ELFBuilder<ELFT>::initSymbolTable(S
> } else if (Sym.st_shndx != SHN_UNDEF) {
> DefSection = Obj.sections().getSection(
> Sym.st_shndx, "Symbol '" + Name +
> - "' is defined in invalid section with index "
> +
> + "' is defined has invalid section index " +
> Twine(Sym.st_shndx));
> }
>
> @@ -699,14 +766,14 @@ void initRelocations(RelocationSection *
> }
> }
>
> -SectionBase *SectionTableRef::getSection(uint16_t Index, Twine ErrMsg) {
> +SectionBase *SectionTableRef::getSection(uint32_t Index, Twine ErrMsg) {
> if (Index == SHN_UNDEF || Index > Sections.size())
> error(ErrMsg);
> return Sections[Index - 1].get();
> }
>
> template <class T>
> -T *SectionTableRef::getSectionOfType(uint16_t Index, Twine IndexErrMsg,
> +T *SectionTableRef::getSectionOfType(uint32_t Index, Twine IndexErrMsg,
> Twine TypeErrMsg) {
> if (T *Sec = dyn_cast<T>(getSection(Index, IndexErrMsg)))
> return Sec;
> @@ -753,6 +820,11 @@ SectionBase &ELFBuilder<ELFT>::makeSecti
> Obj.SymbolTable = &SymTab;
> return SymTab;
> }
> + case SHT_SYMTAB_SHNDX: {
> + auto &ShndxSection = Obj.addSection<SectionIndexSection>();
> + Obj.SectionIndexTable = &ShndxSection;
> + return ShndxSection;
> + }
> case SHT_NOBITS:
> return Obj.addSection<Section>(Data);
> default:
> @@ -783,6 +855,12 @@ template <class ELFT> void ELFBuilder<EL
> Sec.Index = Index++;
> }
>
> + // If a section index table exists we'll need to initialize it before we
> + // initialize the symbol table because the symbol table might need to
> + // reference it.
> + if (Obj.SectionIndexTable)
> + Obj.SectionIndexTable->initialize(Obj.sections());
> +
> // Now that all of the sections have been added we can fill out some
> extra
> // details about symbol tables. We need the symbol table filled out
> before
> // any relocations.
> @@ -825,9 +903,13 @@ template <class ELFT> void ELFBuilder<EL
> readSectionHeaders();
> readProgramHeaders();
>
> + uint32_t ShstrIndex = Ehdr.e_shstrndx;
> + if (ShstrIndex == SHN_XINDEX)
> + ShstrIndex = unwrapOrError(ElfFile.getSection(0))->sh_link;
> +
> Obj.SectionNames =
> Obj.sections().template getSectionOfType<StringTableSection>(
> - Ehdr.e_shstrndx,
> + ShstrIndex,
> "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) +
> " in elf header " + " is invalid",
> "e_shstrndx field value " + Twine(Ehdr.e_shstrndx) +
> @@ -893,8 +975,27 @@ template <class ELFT> void ELFWriter<ELF
> Ehdr.e_shentsize = sizeof(Elf_Shdr);
> if (WriteSectionHeaders) {
> Ehdr.e_shoff = Obj.SHOffset;
> - Ehdr.e_shnum = size(Obj.sections()) + 1;
> - Ehdr.e_shstrndx = Obj.SectionNames->Index;
> + // """
> + // If the number of sections is greater than or equal to
> + // SHN_LORESERVE (0xff00), this member has the value zero and the
> actual
> + // number of section header table entries is contained in the sh_size
> field
> + // of the section header at index 0.
> + // """
> + auto Shnum = size(Obj.sections()) + 1;
> + if (Shnum >= SHN_LORESERVE)
> + Ehdr.e_shnum = 0;
> + else
> + Ehdr.e_shnum = Shnum;
> + // """
> + // If the section name string table section index is greater than or
> equal
> + // to SHN_LORESERVE (0xff00), this member has the value SHN_XINDEX
> (0xffff)
> + // and the actual index of the section name string table section is
> + // contained in the sh_link field of the section header at index 0.
> + // """
> + if (Obj.SectionNames->Index >= SHN_LORESERVE)
> + Ehdr.e_shstrndx = SHN_XINDEX;
> + else
> + Ehdr.e_shstrndx = Obj.SectionNames->Index;
> } else {
> Ehdr.e_shoff = 0;
> Ehdr.e_shnum = 0;
> @@ -917,8 +1018,17 @@ template <class ELFT> void ELFWriter<ELF
> Shdr.sh_flags = 0;
> Shdr.sh_addr = 0;
> Shdr.sh_offset = 0;
> - Shdr.sh_size = 0;
> - Shdr.sh_link = 0;
> + // See writeEhdr for why we do this.
> + uint64_t Shnum = size(Obj.sections()) + 1;
> + if (Shnum >= SHN_LORESERVE)
> + Shdr.sh_size = Shnum;
> + else
> + Shdr.sh_size = 0;
> + // See writeEhdr for why we do this.
> + if (Obj.SectionNames != nullptr && Obj.SectionNames->Index >=
> SHN_LORESERVE)
> + Shdr.sh_link = Obj.SectionNames->Index;
> + else
> + Shdr.sh_link = 0;
> Shdr.sh_info = 0;
> Shdr.sh_addralign = 0;
> Shdr.sh_entsize = 0;
> @@ -946,9 +1056,10 @@ void Object::removeSections(std::functio
> });
> if (SymbolTable != nullptr && ToRemove(*SymbolTable))
> SymbolTable = nullptr;
> - if (SectionNames != nullptr && ToRemove(*SectionNames)) {
> + if (SectionNames != nullptr && ToRemove(*SectionNames))
> SectionNames = nullptr;
> - }
> + if (SectionIndexTable != nullptr && ToRemove(*SectionIndexTable))
> + SectionIndexTable = nullptr;
> // Now make sure there are no remaining references to the sections that
> will
> // be removed. Sometimes it is impossible to remove a reference so we
> emit
> // an error here instead.
> @@ -1109,16 +1220,59 @@ template <class ELFT> void ELFWriter<ELF
> error("Cannot write section header table because section header
> string "
> "table was removed.");
>
> - // Make sure we add the names of all the sections.
> + Obj.sortSections();
> +
> + // We need to assign indexes before we perform layout because we need
> to know
> + // if we need large indexes or not. We can assign indexes first and
> check as
> + // we go to see if we will actully need large indexes.
> + bool NeedsLargeIndexes = false;
> + if (size(Obj.sections()) >= SHN_LORESERVE) {
> + auto Sections = Obj.sections();
> + NeedsLargeIndexes =
> + std::any_of(Sections.begin() + SHN_LORESERVE, Sections.end(),
> + [](const SectionBase &Sec) { return Sec.HasSymbol; });
> + // TODO: handle case where only one section needs the large index
> table but
> + // only needs it because the large index table hasn't been removed
> yet.
> + }
> +
> + if (NeedsLargeIndexes) {
> + // This means we definitely need to have a section index table but if
> we
> + // already have one then we should use it instead of making a new one.
> + if (Obj.SymbolTable != nullptr && Obj.SectionIndexTable == nullptr) {
> + // Addition of a section to the end does not invalidate the indexes
> of
> + // other sections and assigns the correct index to the new section.
> + auto &Shndx = Obj.addSection<SectionIndexSection>();
> + Obj.SymbolTable->setShndxTable(&Shndx);
> + Shndx.setSymTab(Obj.SymbolTable);
> + }
> + } else {
> + // Since we don't need SectionIndexTable we should remove it and all
> + // references to it.
> + if (Obj.SectionIndexTable != nullptr) {
> + Obj.removeSections([this](const SectionBase &Sec) {
> + return &Sec == Obj.SectionIndexTable;
> + });
> + }
> + }
> +
> + // Make sure we add the names of all the sections. Importantly this
> must be
> + // done after we decide to add or remove SectionIndexes.
> if (Obj.SectionNames != nullptr)
> for (const auto &Section : Obj.sections()) {
> Obj.SectionNames->addString(Section.Name);
> }
> - // Make sure we add the names of all the symbols.
> +
> + // Before we can prepare for layout the indexes need to be finalized.
> + uint64_t Index = 0;
> + for (auto &Sec : Obj.sections())
> + Sec.Index = Index++;
> +
> + // The symbol table does not update all other sections on update. For
> + // instance, symbol names are not added as new symbols are added. This
> means
> + // that some sections, like .strtab, don't yet have their final size.
> if (Obj.SymbolTable != nullptr)
> - Obj.SymbolTable->addSymbolNames();
> + Obj.SymbolTable->prepareForLayout();
>
> - Obj.sortSections();
> assignOffsets();
>
> // Finalize SectionNames first so that we can assign name indexes.
>
> Modified: llvm/trunk/tools/llvm-objcopy/Object.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/Object.h?rev=337204&r1=337203&r2=337204&view=diff
>
> ==============================================================================
> --- llvm/trunk/tools/llvm-objcopy/Object.h (original)
> +++ llvm/trunk/tools/llvm-objcopy/Object.h Mon Jul 16 12:48:52 2018
> @@ -37,6 +37,7 @@ class RelocationSection;
> class DynamicRelocationSection;
> class GnuDebugLinkSection;
> class GroupSection;
> +class SectionIndexSection;
> class Segment;
> class Object;
> struct Symbol;
> @@ -54,10 +55,10 @@ public:
> iterator begin() { return iterator(Sections.data()); }
> iterator end() { return iterator(Sections.data() + Sections.size()); }
>
> - SectionBase *getSection(uint16_t Index, Twine ErrMsg);
> + SectionBase *getSection(uint32_t Index, Twine ErrMsg);
>
> template <class T>
> - T *getSectionOfType(uint16_t Index, Twine IndexErrMsg, Twine
> TypeErrMsg);
> + T *getSectionOfType(uint32_t Index, Twine IndexErrMsg, Twine
> TypeErrMsg);
> };
>
> enum ElfType { ELFT_ELF32LE, ELFT_ELF64LE, ELFT_ELF32BE, ELFT_ELF64BE };
> @@ -74,6 +75,7 @@ public:
> virtual void visit(const DynamicRelocationSection &Sec) = 0;
> virtual void visit(const GnuDebugLinkSection &Sec) = 0;
> virtual void visit(const GroupSection &Sec) = 0;
> + virtual void visit(const SectionIndexSection &Sec) = 0;
> };
>
> class SectionWriter : public SectionVisitor {
> @@ -91,6 +93,7 @@ public:
> virtual void visit(const RelocationSection &Sec) override = 0;
> virtual void visit(const GnuDebugLinkSection &Sec) override = 0;
> virtual void visit(const GroupSection &Sec) override = 0;
> + virtual void visit(const SectionIndexSection &Sec) override = 0;
>
> explicit SectionWriter(Buffer &Buf) : Out(Buf) {}
> };
> @@ -107,6 +110,7 @@ public:
> void visit(const RelocationSection &Sec) override;
> void visit(const GnuDebugLinkSection &Sec) override;
> void visit(const GroupSection &Sec) override;
> + void visit(const SectionIndexSection &Sec) override;
>
> explicit ELFSectionWriter(Buffer &Buf) : SectionWriter(Buf) {}
> };
> @@ -123,6 +127,7 @@ public:
> void visit(const RelocationSection &Sec) override;
> void visit(const GnuDebugLinkSection &Sec) override;
> void visit(const GroupSection &Sec) override;
> + void visit(const SectionIndexSection &Sec) override;
>
> explicit BinarySectionWriter(Buffer &Buf) : SectionWriter(Buf) {}
> };
> @@ -230,8 +235,9 @@ public:
> StringRef Name;
> Segment *ParentSegment = nullptr;
> uint64_t HeaderOffset;
> - uint64_t OriginalOffset;
> + uint64_t OriginalOffset = std::numeric_limits<uint64_t>::max();
> uint32_t Index;
> + bool HasSymbol = false;
>
> uint64_t Addr = 0;
> uint64_t Align = 1;
> @@ -371,6 +377,7 @@ enum SymbolShndxType {
> SYMBOL_HEXAGON_SCOMMON_2 = ELF::SHN_HEXAGON_SCOMMON_2,
> SYMBOL_HEXAGON_SCOMMON_4 = ELF::SHN_HEXAGON_SCOMMON_4,
> SYMBOL_HEXAGON_SCOMMON_8 = ELF::SHN_HEXAGON_SCOMMON_8,
> + SYMBOL_XINDEX = ELF::SHN_XINDEX,
> };
>
> struct Symbol {
> @@ -389,6 +396,32 @@ struct Symbol {
> uint16_t getShndx() const;
> };
>
> +class SectionIndexSection : public SectionBase {
> + MAKE_SEC_WRITER_FRIEND
> +
> +private:
> + std::vector<uint32_t> Indexes;
> + SymbolTableSection *Symbols = nullptr;
> +
> +public:
> + virtual ~SectionIndexSection() {}
> + void addIndex(uint32_t Index) {
> + Indexes.push_back(Index);
> + Size += 4;
> + }
> + void setSymTab(SymbolTableSection *SymTab) { Symbols = SymTab; }
> + void initialize(SectionTableRef SecTable) override;
> + void finalize() override;
> + void accept(SectionVisitor &Visitor) const override;
> +
> + SectionIndexSection() {
> + Name = ".symtab_shndx";
> + Align = 4;
> + EntrySize = 4;
> + Type = ELF::SHT_SYMTAB_SHNDX;
> + }
> +};
> +
> class SymbolTableSection : public SectionBase {
> MAKE_SEC_WRITER_FRIEND
>
> @@ -398,6 +431,7 @@ class SymbolTableSection : public Sectio
> protected:
> std::vector<std::unique_ptr<Symbol>> Symbols;
> StringTableSection *SymbolNames = nullptr;
> + SectionIndexSection *SectionIndexTable = nullptr;
>
> using SymPtr = std::unique_ptr<Symbol>;
>
> @@ -405,9 +439,13 @@ public:
> void addSymbol(StringRef Name, uint8_t Bind, uint8_t Type,
> SectionBase *DefinedIn, uint64_t Value, uint8_t
> Visibility,
> uint16_t Shndx, uint64_t Sz);
> - void addSymbolNames();
> + void prepareForLayout();
> // An 'empty' symbol table still contains a null symbol.
> bool empty() const { return Symbols.size() == 1; }
> + void setShndxTable(SectionIndexSection *ShndxTable) {
> + SectionIndexTable = ShndxTable;
> + }
> + const SectionIndexSection *getShndxTable() const { return
> SectionIndexTable; }
> const SectionBase *getStrTab() const { return SymbolNames; }
> const Symbol *getSymbolByIndex(uint32_t Index) const;
> Symbol *getSymbolByIndex(uint32_t Index);
> @@ -589,6 +627,7 @@ private:
> using Elf_Addr = typename ELFT::Addr;
> using Elf_Shdr = typename ELFT::Shdr;
> using Elf_Ehdr = typename ELFT::Ehdr;
> + using Elf_Word = typename ELFT::Word;
>
> const ELFFile<ELFT> &ElfFile;
> Object &Obj;
> @@ -652,6 +691,7 @@ public:
>
> StringTableSection *SectionNames = nullptr;
> SymbolTableSection *SymbolTable = nullptr;
> + SectionIndexSection *SectionIndexTable = nullptr;
>
> void sortSections();
> SectionTableRef sections() { return SectionTableRef(Sections); }
>
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>
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