From 42469f61f5ea6ce6dafcabfe0dffdd19dc4ab527 Mon Sep 17 00:00:00 2001 From: Simon Atanasyan Date: Wed, 18 Jun 2014 08:47:09 +0000 Subject: [llvm-readobj][ELF] New `-mips-plt-got` command line option to output MIPS GOT section. Patch reviewed by Rafael Espindola. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211150 91177308-0d34-0410-b5e6-96231b3b80d8 --- tools/llvm-readobj/ELFDumper.cpp | 217 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 217 insertions(+) (limited to 'tools/llvm-readobj/ELFDumper.cpp') diff --git a/tools/llvm-readobj/ELFDumper.cpp b/tools/llvm-readobj/ELFDumper.cpp index f13b300d6d..03dfa379fa 100644 --- a/tools/llvm-readobj/ELFDumper.cpp +++ b/tools/llvm-readobj/ELFDumper.cpp @@ -18,6 +18,7 @@ #include "Error.h" #include "ObjDumper.h" #include "StreamWriter.h" +#include "llvm/ADT/Optional.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/StringExtras.h" #include "llvm/Object/ELFObjectFile.h" @@ -54,6 +55,7 @@ public: void printProgramHeaders() override; void printAttributes() override; + void printMipsPLTGOT() override; private: typedef ELFFile ELFO; @@ -159,6 +161,15 @@ getSectionNameIndex(const ELFO &Obj, typename ELFO::Elf_Sym_Iter Symbol, } } +template +static const typename ELFFile::Elf_Shdr * +findSectionByAddress(const ELFFile *Obj, uint64_t Addr) { + for (const auto &Shdr : Obj->sections()) + if (Shdr.sh_addr == Addr) + return &Shdr; + return nullptr; +} + static const EnumEntry ElfClass[] = { { "None", ELF::ELFCLASSNONE }, { "32-bit", ELF::ELFCLASS32 }, @@ -1021,3 +1032,209 @@ void ELFDumper >::printAttributes() { } } +namespace { +template class MipsGOTParser { +public: + typedef object::ELFFile ObjectFile; + typedef typename ObjectFile::Elf_Shdr Elf_Shdr; + + MipsGOTParser(const ObjectFile *Obj, StreamWriter &W) : Obj(Obj), W(W) {} + + void ParseGOT(const Elf_Shdr &GOTShdr); + +private: + typedef typename ObjectFile::Elf_Sym_Iter Elf_Sym_Iter; + typedef typename ObjectFile::Elf_Addr GOTEntry; + typedef typename ObjectFile::template ELFEntityIterator + GOTIter; + + const ObjectFile *Obj; + StreamWriter &W; + + std::size_t GetGOTTotal(ArrayRef GOT) const; + GOTIter MakeGOTIter(ArrayRef GOT, std::size_t EntryNum); + + bool getGOTTags(uint64_t &LocalGotNum, uint64_t &GotSym); + void printGotEntry(uint64_t GotAddr, GOTIter BeginIt, GOTIter It); + void printGlobalGotEntry(uint64_t GotAddr, GOTIter BeginIt, GOTIter It, + Elf_Sym_Iter Sym); +}; +} + +template +void MipsGOTParser::ParseGOT(const Elf_Shdr &GOTShdr) { + // See "Global Offset Table" in Chapter 5 in the following document + // for detailed GOT description. + // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf + + ErrorOr> GOT = Obj->getSectionContents(&GOTShdr); + if (!GOT) { + W.startLine() << "The .got section is empty.\n"; + return; + } + + uint64_t DtLocalGotNum; + uint64_t DtGotSym; + if (!getGOTTags(DtLocalGotNum, DtGotSym)) + return; + + if (DtLocalGotNum > GetGOTTotal(*GOT)) { + W.startLine() << "MIPS_LOCAL_GOTNO exceeds a number of GOT entries.\n"; + return; + } + + Elf_Sym_Iter DynSymBegin = Obj->begin_dynamic_symbols(); + Elf_Sym_Iter DynSymEnd = Obj->end_dynamic_symbols(); + std::size_t DynSymTotal = std::size_t(std::distance(DynSymBegin, DynSymEnd)); + + if (DtGotSym + 1 > DynSymTotal) { + W.startLine() << "MIPS_GOTSYM exceeds a number of dynamic symbols.\n"; + return; + } + + std::size_t GlobalGotNum = DynSymTotal - DtGotSym; + + if (DtLocalGotNum + GlobalGotNum > GetGOTTotal(*GOT)) { + W.startLine() << "Number of global GOT entries exceeds the size of GOT.\n"; + return; + } + + GOTIter GotBegin = MakeGOTIter(*GOT, 0); + GOTIter GotLocalEnd = MakeGOTIter(*GOT, DtLocalGotNum); + GOTIter It = GotBegin; + + DictScope GS(W, "Primary GOT"); + + W.printHex("Canonical gp value", GOTShdr.sh_addr + 0x7ff0); + { + ListScope RS(W, "Reserved entries"); + + { + DictScope D(W, "Entry"); + printGotEntry(GOTShdr.sh_addr, GotBegin, It++); + W.printString("Purpose", StringRef("Lazy resolver")); + } + + if (It != GotLocalEnd && (*It >> (sizeof(GOTEntry) * 8 - 1)) != 0) { + DictScope D(W, "Entry"); + printGotEntry(GOTShdr.sh_addr, GotBegin, It++); + W.printString("Purpose", StringRef("Module pointer (GNU extension)")); + } + } + { + ListScope LS(W, "Local entries"); + for (; It != GotLocalEnd; ++It) { + DictScope D(W, "Entry"); + printGotEntry(GOTShdr.sh_addr, GotBegin, It); + } + } + { + ListScope GS(W, "Global entries"); + + GOTIter GotGlobalEnd = MakeGOTIter(*GOT, DtLocalGotNum + GlobalGotNum); + Elf_Sym_Iter GotDynSym = DynSymBegin + DtGotSym; + for (; It != GotGlobalEnd; ++It) { + DictScope D(W, "Entry"); + printGlobalGotEntry(GOTShdr.sh_addr, GotBegin, It, GotDynSym++); + } + } + + std::size_t SpecGotNum = GetGOTTotal(*GOT) - DtLocalGotNum - GlobalGotNum; + W.printNumber("Number of TLS and multi-GOT entries", SpecGotNum); +} + +template +std::size_t MipsGOTParser::GetGOTTotal(ArrayRef GOT) const { + return GOT.size() / sizeof(GOTEntry); +} + +template +typename MipsGOTParser::GOTIter +MipsGOTParser::MakeGOTIter(ArrayRef GOT, std::size_t EntryNum) { + const char *Data = reinterpret_cast(GOT.data()); + return GOTIter(sizeof(GOTEntry), Data + EntryNum * sizeof(GOTEntry)); +} + +template +bool MipsGOTParser::getGOTTags(uint64_t &LocalGotNum, uint64_t &GotSym) { + bool FoundLocalGotNum = false; + bool FoundGotSym = false; + for (const auto &Entry : Obj->dynamic_table()) { + switch (Entry.getTag()) { + case ELF::DT_MIPS_LOCAL_GOTNO: + LocalGotNum = Entry.getVal(); + FoundLocalGotNum = true; + break; + case ELF::DT_MIPS_GOTSYM: + GotSym = Entry.getVal(); + FoundGotSym = true; + break; + } + } + + if (!FoundLocalGotNum) { + W.startLine() << "Cannot find MIPS_LOCAL_GOTNO dynamic table tag.\n"; + return false; + } + + if (!FoundGotSym) { + W.startLine() << "Cannot find MIPS_GOTSYM dynamic table tag.\n"; + return false; + } + + return true; +} + +template +void MipsGOTParser::printGotEntry(uint64_t GotAddr, GOTIter BeginIt, + GOTIter It) { + int64_t Offset = std::distance(BeginIt, It) * sizeof(GOTEntry); + W.printHex("Address", GotAddr + Offset); + W.printNumber("Access", Offset - 0x7ff0); + W.printHex("Initial", *It); +} + +template +void MipsGOTParser::printGlobalGotEntry(uint64_t GotAddr, GOTIter BeginIt, + GOTIter It, Elf_Sym_Iter Sym) { + printGotEntry(GotAddr, BeginIt, It); + + W.printHex("Value", Sym->st_value); + W.printEnum("Type", Sym->getType(), makeArrayRef(ElfSymbolTypes)); + + unsigned SectionIndex = 0; + StringRef SectionName; + getSectionNameIndex(*Obj, Sym, SectionName, SectionIndex); + W.printHex("Section", SectionName, SectionIndex); + + std::string FullSymbolName = getFullSymbolName(*Obj, Sym); + W.printNumber("Name", FullSymbolName, Sym->st_name); +} + +template void ELFDumper::printMipsPLTGOT() { + if (Obj->getHeader()->e_machine != EM_MIPS) { + W.startLine() << "MIPS PLT GOT is available for MIPS targets only.\n"; + return; + } + + llvm::Optional DtPltGot; + for (const auto &Entry : Obj->dynamic_table()) { + if (Entry.getTag() == ELF::DT_PLTGOT) { + DtPltGot = Entry.getVal(); + break; + } + } + + if (!DtPltGot) { + W.startLine() << "Cannot find PLTGOT dynamic table tag.\n"; + return; + } + + const Elf_Shdr *GotShdr = findSectionByAddress(Obj, *DtPltGot); + if (!GotShdr) { + W.startLine() << "There is no .got section in the file.\n"; + return; + } + + MipsGOTParser(Obj, W).ParseGOT(*GotShdr); +} -- cgit v1.2.3