[llvm] r350336 - [llvm-objcopy][ELF] Implement a mutable section visitor that updates size-related fields (Size, EntrySize, Align) before layout.
Jordan Rupprecht via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 3 09:45:30 PST 2019
Author: rupprecht
Date: Thu Jan 3 09:45:30 2019
New Revision: 350336
URL: http://llvm.org/viewvc/llvm-project?rev=350336&view=rev
Log:
[llvm-objcopy][ELF] Implement a mutable section visitor that updates size-related fields (Size, EntrySize, Align) before layout.
Summary:
Fix EntrySize, Size, and Align before doing layout calculation.
As a side cleanup, this removes a dependence on sizeof(Elf_Sym) within BinaryReader, so we can untemplatize that.
This unblocks a cleaner implementation of handling the -O<format> flag. See D53667 for a previous attempt. Actual implementation of the -O<format> flag will come in an upcoming commit, this is largely a NFC (although not _totally_ one, because alignment on binary input was actually wrong before).
Reviewers: jakehehrlich, jhenderson, alexshap, espindola
Reviewed By: jhenderson
Subscribers: emaste, arichardson, llvm-commits
Differential Revision: https://reviews.llvm.org/D56211
Modified:
llvm/trunk/test/tools/llvm-objcopy/ELF/binary-input.test
llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp
llvm/trunk/tools/llvm-objcopy/ELF/Object.h
Modified: llvm/trunk/test/tools/llvm-objcopy/ELF/binary-input.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/ELF/binary-input.test?rev=350336&r1=350335&r2=350336&view=diff
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/ELF/binary-input.test (original)
+++ llvm/trunk/test/tools/llvm-objcopy/ELF/binary-input.test Thu Jan 3 09:45:30 2019
@@ -45,7 +45,7 @@
# CHECK-NEXT: Size:
# CHECK-NEXT: Link: 1
# CHECK-NEXT: Info: 1
-# CHECK-NEXT: AddressAlignment: 1
+# CHECK-NEXT: AddressAlignment: 8
# CHECK-NEXT: EntrySize: 24
# CHECK-NEXT: }
# CHECK-NEXT: Section {
Modified: llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp?rev=350336&r1=350335&r2=350336&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp (original)
+++ llvm/trunk/tools/llvm-objcopy/ELF/Object.cpp Thu Jan 3 09:45:30 2019
@@ -71,7 +71,47 @@ template <class ELFT> void ELFWriter<ELF
Shdr.sh_entsize = Sec.EntrySize;
}
-SectionVisitor::~SectionVisitor() {}
+template <class ELFT> void ELFSectionSizer<ELFT>::visit(Section &Sec) {}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(OwnedDataSection &Sec) {}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(StringTableSection &Sec) {}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(DynamicRelocationSection &Sec) {}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(SymbolTableSection &Sec) {
+ Sec.EntrySize = sizeof(Elf_Sym);
+ Sec.Size = Sec.Symbols.size() * Sec.EntrySize;
+ // Align to the larget field in Elf_Sym.
+ Sec.Align = sizeof(Elf_Sym::st_size);
+}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(RelocationSection &Sec) {
+ Sec.EntrySize = Sec.Type == SHT_REL ? sizeof(Elf_Rel) : sizeof(Elf_Rela);
+ Sec.Size = Sec.Relocations.size() * Sec.EntrySize;
+ // Align to the larget field in Elf_Rel(a).
+ Sec.Align =
+ Sec.Type == SHT_REL ? sizeof(Elf_Rel::r_info) : sizeof(Elf_Rela::r_info);
+}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(GnuDebugLinkSection &Sec) {}
+
+template <class ELFT> void ELFSectionSizer<ELFT>::visit(GroupSection &Sec) {}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(SectionIndexSection &Sec) {}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(CompressedSection &Sec) {}
+
+template <class ELFT>
+void ELFSectionSizer<ELFT>::visit(DecompressedSection &Sec) {}
void BinarySectionWriter::visit(const SectionIndexSection &Sec) {
error("Cannot write symbol section index table '" + Sec.Name + "' ");
@@ -102,6 +142,8 @@ void SectionWriter::visit(const Section
void Section::accept(SectionVisitor &Visitor) const { Visitor.visit(*this); }
+void Section::accept(MutableSectionVisitor &Visitor) { Visitor.visit(*this); }
+
void SectionWriter::visit(const OwnedDataSection &Sec) {
uint8_t *Buf = Out.getBufferStart() + Sec.Offset;
llvm::copy(Sec.Data, Buf);
@@ -164,10 +206,18 @@ void DecompressedSection::accept(Section
Visitor.visit(*this);
}
+void DecompressedSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
void OwnedDataSection::accept(SectionVisitor &Visitor) const {
Visitor.visit(*this);
}
+void OwnedDataSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
void BinarySectionWriter::visit(const CompressedSection &Sec) {
error("Cannot write compressed section '" + Sec.Name + "' ");
}
@@ -246,6 +296,10 @@ void CompressedSection::accept(SectionVi
Visitor.visit(*this);
}
+void CompressedSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
void StringTableSection::addString(StringRef Name) {
StrTabBuilder.add(Name);
Size = StrTabBuilder.getSize();
@@ -265,6 +319,10 @@ void StringTableSection::accept(SectionV
Visitor.visit(*this);
}
+void StringTableSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
template <class ELFT>
void ELFSectionWriter<ELFT>::visit(const SectionIndexSection &Sec) {
uint8_t *Buf = Out.getBufferStart() + Sec.Offset;
@@ -288,6 +346,10 @@ void SectionIndexSection::accept(Section
Visitor.visit(*this);
}
+void SectionIndexSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
static bool isValidReservedSectionIndex(uint16_t Index, uint16_t Machine) {
switch (Index) {
case SHN_ABS:
@@ -470,6 +532,10 @@ void SymbolTableSection::accept(SectionV
Visitor.visit(*this);
}
+void SymbolTableSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
template <class SymTabType>
void RelocSectionWithSymtabBase<SymTabType>::removeSectionReferences(
const SectionBase *Sec) {
@@ -540,6 +606,10 @@ void RelocationSection::accept(SectionVi
Visitor.visit(*this);
}
+void RelocationSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
void RelocationSection::removeSymbols(
function_ref<bool(const Symbol &)> ToRemove) {
for (const Relocation &Reloc : Relocations)
@@ -562,6 +632,10 @@ void DynamicRelocationSection::accept(Se
Visitor.visit(*this);
}
+void DynamicRelocationSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
void Section::removeSectionReferences(const SectionBase *Sec) {
if (LinkSection == Sec) {
error("Section " + LinkSection->Name +
@@ -648,6 +722,10 @@ void GnuDebugLinkSection::accept(Section
Visitor.visit(*this);
}
+void GnuDebugLinkSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
template <class ELFT>
void ELFSectionWriter<ELFT>::visit(const GroupSection &Sec) {
ELF::Elf32_Word *Buf =
@@ -661,6 +739,10 @@ void GroupSection::accept(SectionVisitor
Visitor.visit(*this);
}
+void GroupSection::accept(MutableSectionVisitor &Visitor) {
+ Visitor.visit(*this);
+}
+
// Returns true IFF a section is wholly inside the range of a segment
static bool sectionWithinSegment(const SectionBase &Section,
const Segment &Segment) {
@@ -700,7 +782,7 @@ static bool compareSegmentsByPAddr(const
return A->Index < B->Index;
}
-template <class ELFT> void BinaryELFBuilder<ELFT>::initFileHeader() {
+void BinaryELFBuilder::initFileHeader() {
Obj->Flags = 0x0;
Obj->Type = ET_REL;
Obj->OSABI = ELFOSABI_NONE;
@@ -710,11 +792,9 @@ template <class ELFT> void BinaryELFBuil
Obj->Version = 1;
}
-template <class ELFT> void BinaryELFBuilder<ELFT>::initHeaderSegment() {
- Obj->ElfHdrSegment.Index = 0;
-}
+void BinaryELFBuilder::initHeaderSegment() { Obj->ElfHdrSegment.Index = 0; }
-template <class ELFT> StringTableSection *BinaryELFBuilder<ELFT>::addStrTab() {
+StringTableSection *BinaryELFBuilder::addStrTab() {
auto &StrTab = Obj->addSection<StringTableSection>();
StrTab.Name = ".strtab";
@@ -722,15 +802,11 @@ template <class ELFT> StringTableSection
return &StrTab;
}
-template <class ELFT>
-SymbolTableSection *
-BinaryELFBuilder<ELFT>::addSymTab(StringTableSection *StrTab) {
+SymbolTableSection *BinaryELFBuilder::addSymTab(StringTableSection *StrTab) {
auto &SymTab = Obj->addSection<SymbolTableSection>();
SymTab.Name = ".symtab";
SymTab.Link = StrTab->Index;
- // TODO: Factor out dependence on ElfType here.
- SymTab.EntrySize = sizeof(Elf_Sym);
// The symbol table always needs a null symbol
SymTab.addSymbol("", 0, 0, nullptr, 0, 0, 0, 0);
@@ -739,8 +815,7 @@ BinaryELFBuilder<ELFT>::addSymTab(String
return &SymTab;
}
-template <class ELFT>
-void BinaryELFBuilder<ELFT>::addData(SymbolTableSection *SymTab) {
+void BinaryELFBuilder::addData(SymbolTableSection *SymTab) {
auto Data = ArrayRef<uint8_t>(
reinterpret_cast<const uint8_t *>(MemBuf->getBufferStart()),
MemBuf->getBufferSize());
@@ -763,13 +838,13 @@ void BinaryELFBuilder<ELFT>::addData(Sym
/*Value=*/DataSection.Size, STV_DEFAULT, SHN_ABS, 0);
}
-template <class ELFT> void BinaryELFBuilder<ELFT>::initSections() {
+void BinaryELFBuilder::initSections() {
for (auto &Section : Obj->sections()) {
Section.initialize(Obj->sections());
}
}
-template <class ELFT> std::unique_ptr<Object> BinaryELFBuilder<ELFT>::build() {
+std::unique_ptr<Object> BinaryELFBuilder::build() {
initFileHeader();
initHeaderSegment();
StringTableSection *StrTab = addStrTab();
@@ -1122,14 +1197,7 @@ Writer::~Writer() {}
Reader::~Reader() {}
std::unique_ptr<Object> BinaryReader::create() const {
- if (MInfo.Is64Bit)
- return MInfo.IsLittleEndian
- ? BinaryELFBuilder<ELF64LE>(MInfo.EMachine, MemBuf).build()
- : BinaryELFBuilder<ELF64BE>(MInfo.EMachine, MemBuf).build();
- else
- return MInfo.IsLittleEndian
- ? BinaryELFBuilder<ELF32LE>(MInfo.EMachine, MemBuf).build()
- : BinaryELFBuilder<ELF32BE>(MInfo.EMachine, MemBuf).build();
+ return BinaryELFBuilder(MInfo.EMachine, MemBuf).build();
}
std::unique_ptr<Object> ELFReader::create() const {
@@ -1483,10 +1551,16 @@ template <class ELFT> void ELFWriter<ELF
}
initEhdrSegment();
+
// Before we can prepare for layout the indexes need to be finalized.
+ // Also, the output arch may not be the same as the input arch, so fix up
+ // size-related fields before doing layout calculations.
uint64_t Index = 0;
- for (auto &Sec : Obj.sections())
+ auto SecSizer = llvm::make_unique<ELFSectionSizer<ELFT>>();
+ for (auto &Sec : Obj.sections()) {
Sec.Index = Index++;
+ Sec.accept(*SecSizer);
+ }
// 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
@@ -1607,11 +1681,6 @@ void BinaryWriter::finalize() {
SecWriter = llvm::make_unique<BinarySectionWriter>(Buf);
}
-template class BinaryELFBuilder<ELF64LE>;
-template class BinaryELFBuilder<ELF64BE>;
-template class BinaryELFBuilder<ELF32LE>;
-template class BinaryELFBuilder<ELF32BE>;
-
template class ELFBuilder<ELF64LE>;
template class ELFBuilder<ELF64BE>;
template class ELFBuilder<ELF32LE>;
Modified: llvm/trunk/tools/llvm-objcopy/ELF/Object.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/ELF/Object.h?rev=350336&r1=350335&r2=350336&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/ELF/Object.h (original)
+++ llvm/trunk/tools/llvm-objcopy/ELF/Object.h Thu Jan 3 09:45:30 2019
@@ -71,7 +71,7 @@ enum ElfType { ELFT_ELF32LE, ELFT_ELF64L
class SectionVisitor {
public:
- virtual ~SectionVisitor();
+ virtual ~SectionVisitor() = default;
virtual void visit(const Section &Sec) = 0;
virtual void visit(const OwnedDataSection &Sec) = 0;
@@ -86,6 +86,23 @@ public:
virtual void visit(const DecompressedSection &Sec) = 0;
};
+class MutableSectionVisitor {
+public:
+ virtual ~MutableSectionVisitor() = default;
+
+ virtual void visit(Section &Sec) = 0;
+ virtual void visit(OwnedDataSection &Sec) = 0;
+ virtual void visit(StringTableSection &Sec) = 0;
+ virtual void visit(SymbolTableSection &Sec) = 0;
+ virtual void visit(RelocationSection &Sec) = 0;
+ virtual void visit(DynamicRelocationSection &Sec) = 0;
+ virtual void visit(GnuDebugLinkSection &Sec) = 0;
+ virtual void visit(GroupSection &Sec) = 0;
+ virtual void visit(SectionIndexSection &Sec) = 0;
+ virtual void visit(CompressedSection &Sec) = 0;
+ virtual void visit(DecompressedSection &Sec) = 0;
+};
+
class SectionWriter : public SectionVisitor {
protected:
Buffer &Out;
@@ -128,9 +145,30 @@ public:
explicit ELFSectionWriter(Buffer &Buf) : SectionWriter(Buf) {}
};
+template <class ELFT> class ELFSectionSizer : public MutableSectionVisitor {
+private:
+ using Elf_Rel = typename ELFT::Rel;
+ using Elf_Rela = typename ELFT::Rela;
+ using Elf_Sym = typename ELFT::Sym;
+
+public:
+ void visit(Section &Sec) override;
+ void visit(OwnedDataSection &Sec) override;
+ void visit(StringTableSection &Sec) override;
+ void visit(DynamicRelocationSection &Sec) override;
+ void visit(SymbolTableSection &Sec) override;
+ void visit(RelocationSection &Sec) override;
+ void visit(GnuDebugLinkSection &Sec) override;
+ void visit(GroupSection &Sec) override;
+ void visit(SectionIndexSection &Sec) override;
+ void visit(CompressedSection &Sec) override;
+ void visit(DecompressedSection &Sec) override;
+};
+
#define MAKE_SEC_WRITER_FRIEND \
friend class SectionWriter; \
- template <class ELFT> friend class ELFSectionWriter;
+ template <class ELFT> friend class ELFSectionWriter; \
+ template <class ELFT> friend class ELFSectionSizer;
class BinarySectionWriter : public SectionWriter {
public:
@@ -237,6 +275,7 @@ public:
virtual void removeSectionReferences(const SectionBase *Sec);
virtual void removeSymbols(function_ref<bool(const Symbol &)> ToRemove);
virtual void accept(SectionVisitor &Visitor) const = 0;
+ virtual void accept(MutableSectionVisitor &Visitor) = 0;
virtual void markSymbols();
};
@@ -293,6 +332,7 @@ public:
explicit Section(ArrayRef<uint8_t> Data) : Contents(Data) {}
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
void removeSectionReferences(const SectionBase *Sec) override;
void initialize(SectionTableRef SecTable) override;
void finalize() override;
@@ -313,6 +353,7 @@ public:
}
void accept(SectionVisitor &Sec) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
};
class CompressedSection : public SectionBase {
@@ -333,6 +374,7 @@ public:
uint64_t getDecompressedAlign() const { return DecompressedAlign; }
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
static bool classof(const SectionBase *S) {
return (S->Flags & ELF::SHF_COMPRESSED) ||
@@ -354,6 +396,7 @@ public:
}
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
};
// There are two types of string tables that can exist, dynamic and not dynamic.
@@ -378,6 +421,7 @@ public:
uint32_t findIndex(StringRef Name) const;
void finalize() override;
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
static bool classof(const SectionBase *S) {
if (S->Flags & ELF::SHF_ALLOC)
@@ -435,6 +479,7 @@ public:
void initialize(SectionTableRef SecTable) override;
void finalize() override;
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
SectionIndexSection() {
Name = ".symtab_shndx";
@@ -479,6 +524,7 @@ public:
void initialize(SectionTableRef SecTable) override;
void finalize() override;
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
void removeSymbols(function_ref<bool(const Symbol &)> ToRemove) override;
static bool classof(const SectionBase *S) {
@@ -540,6 +586,7 @@ class RelocationSection
public:
void addRelocation(Relocation Rel) { Relocations.push_back(Rel); }
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
void removeSymbols(function_ref<bool(const Symbol &)> ToRemove) override;
void markSymbols() override;
@@ -573,6 +620,7 @@ public:
void addMember(SectionBase *Sec) { GroupMembers.push_back(Sec); }
void accept(SectionVisitor &) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
void finalize() override;
void removeSymbols(function_ref<bool(const Symbol &)> ToRemove) override;
void markSymbols() override;
@@ -611,6 +659,7 @@ public:
explicit DynamicRelocationSection(ArrayRef<uint8_t> Data) : Contents(Data) {}
void accept(SectionVisitor &) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
static bool classof(const SectionBase *S) {
if (!(S->Flags & ELF::SHF_ALLOC))
@@ -632,6 +681,7 @@ public:
// If we add this section from an external source we can use this ctor.
explicit GnuDebugLinkSection(StringRef File);
void accept(SectionVisitor &Visitor) const override;
+ void accept(MutableSectionVisitor &Visitor) override;
};
class Reader {
@@ -645,9 +695,7 @@ using object::ELFFile;
using object::ELFObjectFile;
using object::OwningBinary;
-template <class ELFT> class BinaryELFBuilder {
- using Elf_Sym = typename ELFT::Sym;
-
+class BinaryELFBuilder {
uint16_t EMachine;
MemoryBuffer *MemBuf;
std::unique_ptr<Object> Obj;
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