[llvm] r311974 - Reland "[llvm] Add symbol table support to llvm-objcopy"
Petr Hosek via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 28 19:12:03 PDT 2017
Author: phosek
Date: Mon Aug 28 19:12:03 2017
New Revision: 311974
URL: http://llvm.org/viewvc/llvm-project?rev=311974&view=rev
Log:
Reland "[llvm] Add symbol table support to llvm-objcopy"
This change adds support for SHT_SYMTAB sections.
Patch by Jake Ehrlich
Differential Revision: https://reviews.llvm.org/D34167
Added:
llvm/trunk/test/tools/llvm-objcopy/symbol-copy.test
Modified:
llvm/trunk/tools/llvm-objcopy/Object.cpp
llvm/trunk/tools/llvm-objcopy/Object.h
Added: llvm/trunk/test/tools/llvm-objcopy/symbol-copy.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-objcopy/symbol-copy.test?rev=311974&view=auto
==============================================================================
--- llvm/trunk/test/tools/llvm-objcopy/symbol-copy.test (added)
+++ llvm/trunk/test/tools/llvm-objcopy/symbol-copy.test Mon Aug 28 19:12:03 2017
@@ -0,0 +1,93 @@
+# RUN: yaml2obj %s > %t
+# RUN: llvm-objcopy %t %t2
+# RUN: llvm-readobj -symbols %t2 | FileCheck %s
+
+!ELF
+FileHeader:
+ Class: ELFCLASS64
+ Data: ELFDATA2LSB
+ Type: ET_EXEC
+ Machine: EM_X86_64
+Sections:
+ - Name: .text
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+ Address: 0x1000
+ AddressAlign: 0x0000000000000010
+ Content: "0000000000000000"
+ - Name: .data
+ Type: SHT_PROGBITS
+ Flags: [ SHF_ALLOC ]
+ Address: 0x2000
+ AddressAlign: 0x0000000000000010
+ Content: "0000000000000000"
+Symbols:
+ Global:
+ - Name: _start
+ Type: STT_FUNC
+ Section: .text
+ Value: 0x1000
+ Size: 4
+ - Name: foo
+ Type: STT_FUNC
+ Section: .text
+ Section: .text
+ Value: 0x1004
+ - Name: bar
+ Type: STT_OBJECT
+ Section: .data
+ Value: 0x2000
+ Size: 4
+ - Name: baz
+ Type: STT_OBJECT
+ Section: .data
+ Value: 0x2004
+ Size: 4
+
+#CHECK: Symbols [
+#CHECK-NEXT: Symbol {
+#CHECK-NEXT: Name:
+#CHECK-NEXT: Value: 0x0
+#CHECK-NEXT: Size: 0
+#CHECK-NEXT: Binding: Local
+#CHECK-NEXT: Type: None
+#CHECK-NEXT: Other: 0
+#CHECK-NEXT: Section: Undefined
+#CHECK-NEXT: }
+#CHECK-NEXT: Symbol {
+#CHECK-NEXT: Name: _start
+#CHECK-NEXT: Value: 0x1000
+#CHECK-NEXT: Size: 4
+#CHECK-NEXT: Binding: Global
+#CHECK-NEXT: Type: Function
+#CHECK-NEXT: Other: 0
+#CHECK-NEXT: Section: .text
+#CHECK-NEXT: }
+#CHECK-NEXT: Symbol {
+#CHECK-NEXT: Name: foo
+#CHECK-NEXT: Value: 0x1004
+#CHECK-NEXT: Size: 0
+#CHECK-NEXT: Binding: Global
+#CHECK-NEXT: Type: Function
+#CHECK-NEXT: Other: 0
+#CHECK-NEXT: Section: .text
+#CHECK-NEXT: }
+#CHECK-NEXT: Symbol {
+#CHECK-NEXT: Name: bar
+#CHECK-NEXT: Value: 0x2000
+#CHECK-NEXT: Size: 4
+#CHECK-NEXT: Binding: Global
+#CHECK-NEXT: Type: Object
+#CHECK-NEXT: Other: 0
+#CHECK-NEXT: Section: .data
+#CHECK-NEXT: }
+#CHECK-NEXT: Symbol {
+#CHECK-NEXT: Name: baz
+#CHECK-NEXT: Value: 0x2004
+#CHECK-NEXT: Size: 4
+#CHECK-NEXT: Binding: Global
+#CHECK-NEXT: Type: Object
+#CHECK-NEXT: Other: 0
+#CHECK-NEXT: Section: .data
+#CHECK-NEXT: }
+#CHECK-NEXT:]
Modified: llvm/trunk/tools/llvm-objcopy/Object.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/Object.cpp?rev=311974&r1=311973&r2=311974&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/Object.cpp (original)
+++ llvm/trunk/tools/llvm-objcopy/Object.cpp Mon Aug 28 19:12:03 2017
@@ -90,6 +90,70 @@ void StringTableSection::writeSection(Fi
StrTabBuilder.write(Out.getBufferStart() + Offset);
}
+void SymbolTableSection::addSymbol(StringRef Name, uint8_t Bind, uint8_t Type,
+ SectionBase *DefinedIn, uint64_t Value,
+ uint64_t Sz) {
+ Symbol Sym;
+ Sym.Name = Name;
+ Sym.Binding = Bind;
+ Sym.Type = Type;
+ Sym.DefinedIn = DefinedIn;
+ Sym.Value = Value;
+ Sym.Size = Sz;
+ Sym.Index = Symbols.size();
+ Symbols.emplace_back(llvm::make_unique<Symbol>(Sym));
+ Size += this->EntrySize;
+}
+
+void SymbolTableSection::finalize() {
+ // Make sure SymbolNames is finalized before getting name indexes.
+ SymbolNames->finalize();
+
+ uint32_t MaxLocalIndex = 0;
+ for (auto &Sym : Symbols) {
+ Sym->NameIndex = SymbolNames->findIndex(Sym->Name);
+ if (Sym->Binding == STB_LOCAL)
+ MaxLocalIndex = std::max(MaxLocalIndex, Sym->Index);
+ }
+ // Now we need to set the Link and Info fields.
+ Link = SymbolNames->Index;
+ Info = MaxLocalIndex + 1;
+}
+
+void SymbolTableSection::addSymbolNames() {
+ // Add all of our strings to SymbolNames so that SymbolNames has the right
+ // size before layout is decided.
+ for (auto &Sym : Symbols)
+ SymbolNames->addString(Sym->Name);
+}
+
+const Symbol *SymbolTableSection::getSymbolByIndex(uint32_t Index) const {
+ if (Symbols.size() <= Index)
+ error("Invalid symbol index: " + Twine(Index));
+ return Symbols[Index].get();
+}
+
+template <class ELFT>
+void SymbolTableSectionImpl<ELFT>::writeSection(
+ llvm::FileOutputBuffer &Out) const {
+ uint8_t *Buf = Out.getBufferStart();
+ Buf += Offset;
+ typename ELFT::Sym *Sym = reinterpret_cast<typename ELFT::Sym *>(Buf);
+ // Loop though symbols setting each entry of the symbol table.
+ for (auto &Symbol : Symbols) {
+ Sym->st_name = Symbol->NameIndex;
+ Sym->st_value = Symbol->Value;
+ Sym->st_size = Symbol->Size;
+ Sym->setBinding(Symbol->Binding);
+ Sym->setType(Symbol->Type);
+ if (Symbol->DefinedIn)
+ Sym->st_shndx = Symbol->DefinedIn->Index;
+ else
+ Sym->st_shndx = SHN_UNDEF;
+ ++Sym;
+ }
+}
+
// Returns true IFF a section is wholly inside the range of a segment
static bool sectionWithinSegment(const SectionBase &Section,
const Segment &Segment) {
@@ -133,6 +197,40 @@ void Object<ELFT>::readProgramHeaders(co
}
template <class ELFT>
+void Object<ELFT>::initSymbolTable(const llvm::object::ELFFile<ELFT> &ElfFile,
+ SymbolTableSection *SymTab) {
+
+ SymTab->Size = 0;
+ if (SymbolTable->Link - 1 >= Sections.size())
+ error("Symbol table has link index of " + Twine(SymbolTable->Link) +
+ " which is not a valid index");
+
+ if (auto StrTab =
+ dyn_cast<StringTableSection>(Sections[SymbolTable->Link - 1].get()))
+ SymTab->setStrTab(StrTab);
+ else
+ error("Symbol table has link index of " + Twine(SymbolTable->Link) +
+ "which is not a string table");
+
+ const Elf_Shdr &Shdr = *unwrapOrError(ElfFile.getSection(SymTab->Index));
+ StringRef StrTabData = unwrapOrError(ElfFile.getStringTableForSymtab(Shdr));
+
+ for (const auto &Sym : unwrapOrError(ElfFile.symbols(&Shdr))) {
+ SectionBase *DefSection = nullptr;
+ StringRef Name = unwrapOrError(Sym.getName(StrTabData));
+ if (Sym.st_shndx != SHN_UNDEF) {
+ if (Sym.st_shndx >= Sections.size())
+ error("Symbol '" + Name +
+ "' is defined in invalid section with index " +
+ Twine(Sym.st_shndx));
+ DefSection = Sections[Sym.st_shndx - 1].get();
+ }
+ SymTab->addSymbol(Name, Sym.getBinding(), Sym.getType(), DefSection,
+ Sym.getValue(), Sym.st_size);
+ }
+}
+
+template <class ELFT>
std::unique_ptr<SectionBase>
Object<ELFT>::makeSection(const llvm::object::ELFFile<ELFT> &ElfFile,
const Elf_Shdr &Shdr) {
@@ -140,6 +238,11 @@ Object<ELFT>::makeSection(const llvm::ob
switch (Shdr.sh_type) {
case SHT_STRTAB:
return llvm::make_unique<StringTableSection>();
+ case SHT_SYMTAB: {
+ auto SymTab = llvm::make_unique<SymbolTableSectionImpl<ELFT>>();
+ SymbolTable = SymTab.get();
+ return std::move(SymTab);
+ }
case SHT_NOBITS:
return llvm::make_unique<Section>(Data);
default:
@@ -171,6 +274,11 @@ void Object<ELFT>::readSectionHeaders(co
Sec->Index = Index++;
Sections.push_back(std::move(Sec));
}
+
+ // Now that all of the sections have been added we can fill out some extra
+ // details about symbol tables.
+ if (SymbolTable)
+ initSymbolTable(ElfFile, SymbolTable);
}
template <class ELFT> Object<ELFT>::Object(const ELFObjectFile<ELFT> &Obj) {
@@ -315,9 +423,12 @@ template <class ELFT> void ELFObject<ELF
}
template <class ELFT> void ELFObject<ELFT>::finalize() {
+ // Make sure we add the names of all the sections.
for (const auto &Section : this->Sections) {
this->SectionNames->addString(Section->Name);
}
+ // Make sure we add the names of all the symbols.
+ this->SymbolTable->addSymbolNames();
sortSections();
assignOffsets();
Modified: llvm/trunk/tools/llvm-objcopy/Object.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-objcopy/Object.h?rev=311974&r1=311973&r2=311974&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-objcopy/Object.h (original)
+++ llvm/trunk/tools/llvm-objcopy/Object.h Mon Aug 28 19:12:03 2017
@@ -113,6 +113,39 @@ public:
}
};
+struct Symbol {
+ uint8_t Binding;
+ SectionBase *DefinedIn;
+ uint32_t Index;
+ llvm::StringRef Name;
+ uint32_t NameIndex;
+ uint64_t Size;
+ uint8_t Type;
+ uint64_t Value;
+};
+
+class SymbolTableSection : public SectionBase {
+protected:
+ std::vector<std::unique_ptr<Symbol>> Symbols;
+ StringTableSection *SymbolNames;
+
+public:
+ void setStrTab(StringTableSection *StrTab) { SymbolNames = StrTab; }
+ void addSymbol(llvm::StringRef Name, uint8_t Bind, uint8_t Type,
+ SectionBase *DefinedIn, uint64_t Value, uint64_t Sz);
+ void addSymbolNames();
+ const Symbol *getSymbolByIndex(uint32_t Index) const;
+ void finalize() override;
+ static bool classof(const SectionBase *S) {
+ return S->Type == llvm::ELF::SHT_SYMTAB;
+ }
+};
+
+// Only writeSection depends on the ELF type so we implement it in a subclass.
+template <class ELFT> class SymbolTableSectionImpl : public SymbolTableSection {
+ void writeSection(llvm::FileOutputBuffer &Out) const override;
+};
+
template <class ELFT> class Object {
private:
typedef std::unique_ptr<SectionBase> SecPtr;
@@ -122,6 +155,8 @@ private:
typedef typename ELFT::Ehdr Elf_Ehdr;
typedef typename ELFT::Phdr Elf_Phdr;
+ void initSymbolTable(const llvm::object::ELFFile<ELFT> &ElfFile,
+ SymbolTableSection *SymTab);
SecPtr makeSection(const llvm::object::ELFFile<ELFT> &ElfFile,
const Elf_Shdr &Shdr);
void readProgramHeaders(const llvm::object::ELFFile<ELFT> &ElfFile);
@@ -129,6 +164,7 @@ private:
protected:
StringTableSection *SectionNames;
+ SymbolTableSection *SymbolTable;
std::vector<SecPtr> Sections;
std::vector<SegPtr> Segments;
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