[llvm-readobj][ELF] New `-mips-plt-got` command line option to output
MIPS GOT section.
Patch reviewed by Rafael Espindola.
llvm-svn: 211150
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index f13b300..03dfa37 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/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 @@
void printProgramHeaders() override;
void printAttributes() override;
+ void printMipsPLTGOT() override;
private:
typedef ELFFile<ELFT> ELFO;
@@ -159,6 +161,15 @@
}
}
+template <class ELFT>
+static const typename ELFFile<ELFT>::Elf_Shdr *
+findSectionByAddress(const ELFFile<ELFT> *Obj, uint64_t Addr) {
+ for (const auto &Shdr : Obj->sections())
+ if (Shdr.sh_addr == Addr)
+ return &Shdr;
+ return nullptr;
+}
+
static const EnumEntry<unsigned> ElfClass[] = {
{ "None", ELF::ELFCLASSNONE },
{ "32-bit", ELF::ELFCLASS32 },
@@ -1021,3 +1032,209 @@
}
}
+namespace {
+template <class ELFT> class MipsGOTParser {
+public:
+ typedef object::ELFFile<ELFT> 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<const GOTEntry>
+ GOTIter;
+
+ const ObjectFile *Obj;
+ StreamWriter &W;
+
+ std::size_t GetGOTTotal(ArrayRef<uint8_t> GOT) const;
+ GOTIter MakeGOTIter(ArrayRef<uint8_t> 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 <class ELFT>
+void MipsGOTParser<ELFT>::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<ArrayRef<uint8_t>> 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 <class ELFT>
+std::size_t MipsGOTParser<ELFT>::GetGOTTotal(ArrayRef<uint8_t> GOT) const {
+ return GOT.size() / sizeof(GOTEntry);
+}
+
+template <class ELFT>
+typename MipsGOTParser<ELFT>::GOTIter
+MipsGOTParser<ELFT>::MakeGOTIter(ArrayRef<uint8_t> GOT, std::size_t EntryNum) {
+ const char *Data = reinterpret_cast<const char *>(GOT.data());
+ return GOTIter(sizeof(GOTEntry), Data + EntryNum * sizeof(GOTEntry));
+}
+
+template <class ELFT>
+bool MipsGOTParser<ELFT>::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 <class ELFT>
+void MipsGOTParser<ELFT>::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 <class ELFT>
+void MipsGOTParser<ELFT>::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 <class ELFT> void ELFDumper<ELFT>::printMipsPLTGOT() {
+ if (Obj->getHeader()->e_machine != EM_MIPS) {
+ W.startLine() << "MIPS PLT GOT is available for MIPS targets only.\n";
+ return;
+ }
+
+ llvm::Optional<uint64_t> 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<ELFT>(Obj, W).ParseGOT(*GotShdr);
+}
diff --git a/llvm/tools/llvm-readobj/ObjDumper.h b/llvm/tools/llvm-readobj/ObjDumper.h
index 7951933..f80a28b 100644
--- a/llvm/tools/llvm-readobj/ObjDumper.h
+++ b/llvm/tools/llvm-readobj/ObjDumper.h
@@ -40,6 +40,9 @@
// Only implemented for ARM ELF at this time.
virtual void printAttributes() { }
+ // Only implemented for MIPS ELF at this time.
+ virtual void printMipsPLTGOT() { }
+
protected:
StreamWriter& W;
};
diff --git a/llvm/tools/llvm-readobj/llvm-readobj.cpp b/llvm/tools/llvm-readobj/llvm-readobj.cpp
index 52db0eb..8d2a997 100644
--- a/llvm/tools/llvm-readobj/llvm-readobj.cpp
+++ b/llvm/tools/llvm-readobj/llvm-readobj.cpp
@@ -135,6 +135,11 @@
cl::desc("Display the ARM attributes section"));
cl::alias ARMAttributesShort("-a", cl::desc("Alias for --arm-attributes"),
cl::aliasopt(ARMAttributes));
+
+ // -mips-plt-got
+ cl::opt<bool>
+ MipsPLTGOT("mips-plt-got",
+ cl::desc("Display the MIPS GOT and PLT GOT sections"));
} // namespace opts
static int ReturnValue = EXIT_SUCCESS;
@@ -177,6 +182,18 @@
ReturnValue = EXIT_FAILURE;
}
+static bool isMipsArch(unsigned Arch) {
+ switch (Arch) {
+ case llvm::Triple::mips:
+ case llvm::Triple::mipsel:
+ case llvm::Triple::mips64:
+ case llvm::Triple::mips64el:
+ return true;
+ default:
+ return false;
+ }
+}
+
/// @brief Creates an format-specific object file dumper.
static std::error_code createDumper(const ObjectFile *Obj, StreamWriter &Writer,
std::unique_ptr<ObjDumper> &Result) {
@@ -234,6 +251,9 @@
if (Obj->getArch() == llvm::Triple::arm && Obj->isELF())
if (opts::ARMAttributes)
Dumper->printAttributes();
+ if (isMipsArch(Obj->getArch()) && Obj->isELF())
+ if (opts::MipsPLTGOT)
+ Dumper->printMipsPLTGOT();
}
diff --git a/llvm/tools/llvm-readobj/llvm-readobj.h b/llvm/tools/llvm-readobj/llvm-readobj.h
index 033195c..0413948 100644
--- a/llvm/tools/llvm-readobj/llvm-readobj.h
+++ b/llvm/tools/llvm-readobj/llvm-readobj.h
@@ -38,6 +38,7 @@
extern llvm::cl::opt<bool> ExpandRelocs;
extern llvm::cl::opt<bool> CodeViewLineTables;
extern llvm::cl::opt<bool> ARMAttributes;
+ extern llvm::cl::opt<bool> MipsPLTGOT;
} // namespace opts
#define LLVM_READOBJ_ENUM_ENT(ns, enum) \