| //===-- lib/MC/MCObjectSymbolizer.cpp -------------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/MC/MCObjectSymbolizer.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCInst.h" |
| #include "llvm/MC/MCRelocationInfo.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/Object/ELFObjectFile.h" |
| #include "llvm/Object/MachO.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include <algorithm> |
| |
| using namespace llvm; |
| using namespace object; |
| |
| //===- MCMachObjectSymbolizer ---------------------------------------------===// |
| |
| namespace { |
| class MCMachObjectSymbolizer : public MCObjectSymbolizer { |
| const MachOObjectFile *MOOF; |
| // __TEXT;__stubs support. |
| uint64_t StubsStart; |
| uint64_t StubsCount; |
| uint64_t StubSize; |
| uint64_t StubsIndSymIndex; |
| |
| public: |
| MCMachObjectSymbolizer(MCContext &Ctx, |
| std::unique_ptr<MCRelocationInfo> RelInfo, |
| const MachOObjectFile *MOOF); |
| |
| StringRef findExternalFunctionAt(uint64_t Addr) override; |
| |
| void tryAddingPcLoadReferenceComment(raw_ostream &cStream, int64_t Value, |
| uint64_t Address) override; |
| }; |
| } // End unnamed namespace |
| |
| MCMachObjectSymbolizer::MCMachObjectSymbolizer( |
| MCContext &Ctx, std::unique_ptr<MCRelocationInfo> RelInfo, |
| const MachOObjectFile *MOOF) |
| : MCObjectSymbolizer(Ctx, std::move(RelInfo), MOOF), MOOF(MOOF), |
| StubsStart(0), StubsCount(0), StubSize(0), StubsIndSymIndex(0) { |
| |
| for (const SectionRef &Section : MOOF->sections()) { |
| StringRef Name; |
| Section.getName(Name); |
| if (Name == "__stubs") { |
| SectionRef StubsSec = Section; |
| if (MOOF->is64Bit()) { |
| MachO::section_64 S = MOOF->getSection64(StubsSec.getRawDataRefImpl()); |
| StubsIndSymIndex = S.reserved1; |
| StubSize = S.reserved2; |
| } else { |
| MachO::section S = MOOF->getSection(StubsSec.getRawDataRefImpl()); |
| StubsIndSymIndex = S.reserved1; |
| StubSize = S.reserved2; |
| } |
| assert(StubSize && "Mach-O stub entry size can't be zero!"); |
| StubsSec.getAddress(StubsStart); |
| StubsSec.getSize(StubsCount); |
| StubsCount /= StubSize; |
| } |
| } |
| } |
| |
| StringRef MCMachObjectSymbolizer::findExternalFunctionAt(uint64_t Addr) { |
| // FIXME: also, this can all be done at the very beginning, by iterating over |
| // all stubs and creating the calls to outside functions. Is it worth it |
| // though? |
| if (!StubSize) |
| return StringRef(); |
| uint64_t StubIdx = (Addr - StubsStart) / StubSize; |
| if (StubIdx >= StubsCount) |
| return StringRef(); |
| |
| uint32_t SymtabIdx = |
| MOOF->getIndirectSymbolTableEntry(MOOF->getDysymtabLoadCommand(), StubIdx); |
| |
| StringRef SymName; |
| symbol_iterator SI = MOOF->symbol_begin(); |
| for (uint32_t i = 0; i != SymtabIdx; ++i) |
| ++SI; |
| SI->getName(SymName); |
| assert(SI != MOOF->symbol_end() && "Stub wasn't found in the symbol table!"); |
| assert(SymName.front() == '_' && "Mach-O symbol doesn't start with '_'!"); |
| return SymName.substr(1); |
| } |
| |
| void MCMachObjectSymbolizer:: |
| tryAddingPcLoadReferenceComment(raw_ostream &cStream, int64_t Value, |
| uint64_t Address) { |
| if (const RelocationRef *R = findRelocationAt(Address)) { |
| const MCExpr *RelExpr = RelInfo->createExprForRelocation(*R); |
| if (!RelExpr || RelExpr->EvaluateAsAbsolute(Value) == false) |
| return; |
| } |
| uint64_t Addr = Value; |
| if (const SectionRef *S = findSectionContaining(Addr)) { |
| StringRef Name; S->getName(Name); |
| uint64_t SAddr; S->getAddress(SAddr); |
| if (Name == "__cstring") { |
| StringRef Contents; |
| S->getContents(Contents); |
| Contents = Contents.substr(Addr - SAddr); |
| cStream << " ## literal pool for: " |
| << Contents.substr(0, Contents.find_first_of(0)); |
| } |
| } |
| } |
| |
| //===- MCObjectSymbolizer -------------------------------------------------===// |
| |
| MCObjectSymbolizer::MCObjectSymbolizer( |
| MCContext &Ctx, std::unique_ptr<MCRelocationInfo> RelInfo, |
| const ObjectFile *Obj) |
| : MCSymbolizer(Ctx, std::move(RelInfo)), Obj(Obj), SortedSections(), |
| AddrToReloc() {} |
| |
| bool MCObjectSymbolizer:: |
| tryAddingSymbolicOperand(MCInst &MI, raw_ostream &cStream, |
| int64_t Value, uint64_t Address, bool IsBranch, |
| uint64_t Offset, uint64_t InstSize) { |
| if (IsBranch) { |
| StringRef ExtFnName = findExternalFunctionAt((uint64_t)Value); |
| if (!ExtFnName.empty()) { |
| MCSymbol *Sym = Ctx.GetOrCreateSymbol(ExtFnName); |
| const MCExpr *Expr = MCSymbolRefExpr::Create(Sym, Ctx); |
| MI.addOperand(MCOperand::CreateExpr(Expr)); |
| return true; |
| } |
| } |
| |
| if (const RelocationRef *R = findRelocationAt(Address + Offset)) { |
| if (const MCExpr *RelExpr = RelInfo->createExprForRelocation(*R)) { |
| MI.addOperand(MCOperand::CreateExpr(RelExpr)); |
| return true; |
| } |
| // Only try to create a symbol+offset expression if there is no relocation. |
| return false; |
| } |
| |
| // Interpret Value as a branch target. |
| if (IsBranch == false) |
| return false; |
| uint64_t UValue = Value; |
| // FIXME: map instead of looping each time? |
| for (const SymbolRef &Symbol : Obj->symbols()) { |
| uint64_t SymAddr; |
| Symbol.getAddress(SymAddr); |
| uint64_t SymSize; |
| Symbol.getSize(SymSize); |
| StringRef SymName; |
| Symbol.getName(SymName); |
| SymbolRef::Type SymType; |
| Symbol.getType(SymType); |
| if (SymAddr == UnknownAddressOrSize || SymSize == UnknownAddressOrSize || |
| SymName.empty() || SymType != SymbolRef::ST_Function) |
| continue; |
| |
| if ( SymAddr == UValue || |
| (SymAddr <= UValue && SymAddr + SymSize > UValue)) { |
| MCSymbol *Sym = Ctx.GetOrCreateSymbol(SymName); |
| const MCExpr *Expr = MCSymbolRefExpr::Create(Sym, Ctx); |
| if (SymAddr != UValue) { |
| const MCExpr *Off = MCConstantExpr::Create(UValue - SymAddr, Ctx); |
| Expr = MCBinaryExpr::CreateAdd(Expr, Off, Ctx); |
| } |
| MI.addOperand(MCOperand::CreateExpr(Expr)); |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| void MCObjectSymbolizer:: |
| tryAddingPcLoadReferenceComment(raw_ostream &cStream, |
| int64_t Value, uint64_t Address) { |
| } |
| |
| StringRef MCObjectSymbolizer::findExternalFunctionAt(uint64_t Addr) { |
| return StringRef(); |
| } |
| |
| MCObjectSymbolizer *MCObjectSymbolizer::createObjectSymbolizer( |
| MCContext &Ctx, std::unique_ptr<MCRelocationInfo> RelInfo, |
| const ObjectFile *Obj) { |
| if (const MachOObjectFile *MOOF = dyn_cast<MachOObjectFile>(Obj)) |
| return new MCMachObjectSymbolizer(Ctx, std::move(RelInfo), MOOF); |
| return new MCObjectSymbolizer(Ctx, std::move(RelInfo), Obj); |
| } |
| |
| // SortedSections implementation. |
| |
| static bool SectionStartsBefore(const SectionRef &S, uint64_t Addr) { |
| uint64_t SAddr; S.getAddress(SAddr); |
| return SAddr < Addr; |
| } |
| |
| const SectionRef *MCObjectSymbolizer::findSectionContaining(uint64_t Addr) { |
| if (SortedSections.empty()) |
| buildSectionList(); |
| |
| SortedSectionList::iterator |
| EndIt = SortedSections.end(), |
| It = std::lower_bound(SortedSections.begin(), EndIt, |
| Addr, SectionStartsBefore); |
| if (It == EndIt) |
| return nullptr; |
| uint64_t SAddr; It->getAddress(SAddr); |
| uint64_t SSize; It->getSize(SSize); |
| if (Addr >= SAddr + SSize) |
| return nullptr; |
| return &*It; |
| } |
| |
| const RelocationRef *MCObjectSymbolizer::findRelocationAt(uint64_t Addr) { |
| if (AddrToReloc.empty()) |
| buildRelocationByAddrMap(); |
| |
| AddrToRelocMap::const_iterator RI = AddrToReloc.find(Addr); |
| if (RI == AddrToReloc.end()) |
| return nullptr; |
| return &RI->second; |
| } |
| |
| void MCObjectSymbolizer::buildSectionList() { |
| for (const SectionRef &Section : Obj->sections()) { |
| bool RequiredForExec; |
| Section.isRequiredForExecution(RequiredForExec); |
| if (RequiredForExec == false) |
| continue; |
| uint64_t SAddr; |
| Section.getAddress(SAddr); |
| uint64_t SSize; |
| Section.getSize(SSize); |
| SortedSectionList::iterator It = |
| std::lower_bound(SortedSections.begin(), SortedSections.end(), SAddr, |
| SectionStartsBefore); |
| if (It != SortedSections.end()) { |
| uint64_t FoundSAddr; It->getAddress(FoundSAddr); |
| if (FoundSAddr < SAddr + SSize) |
| llvm_unreachable("Inserting overlapping sections"); |
| } |
| SortedSections.insert(It, Section); |
| } |
| } |
| |
| void MCObjectSymbolizer::buildRelocationByAddrMap() { |
| for (const SectionRef &Section : Obj->sections()) { |
| for (const RelocationRef &Reloc : Section.relocations()) { |
| uint64_t Address; |
| Reloc.getAddress(Address); |
| // At a specific address, only keep the first relocation. |
| if (AddrToReloc.find(Address) == AddrToReloc.end()) |
| AddrToReloc[Address] = Reloc; |
| } |
| } |
| } |