lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp

   1 //===-- RuntimeDyldMachO.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-=//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Implementation of the MC-JIT runtime dynamic linker.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "RuntimeDyldMachO.h"
  15 #include "Targets/RuntimeDyldMachOAArch64.h"
  16 #include "Targets/RuntimeDyldMachOARM.h"
  17 #include "Targets/RuntimeDyldMachOI386.h"
  18 #include "Targets/RuntimeDyldMachOX86_64.h"
  19 #include "llvm/ADT/STLExtras.h"
  20 #include "llvm/ADT/StringRef.h"
  21
  22 using namespace llvm;
  23 using namespace llvm::object;
  24
  25 #define DEBUG_TYPE "dyld"
  26
  27 namespace {
  28
  29 class LoadedMachOObjectInfo
  30     : public RuntimeDyld::LoadedObjectInfoHelper<LoadedMachOObjectInfo> {
  31 public:
  32   LoadedMachOObjectInfo(RuntimeDyldImpl &RTDyld, unsigned BeginIdx,
  33                         unsigned EndIdx)
  34       : LoadedObjectInfoHelper(RTDyld, BeginIdx, EndIdx) {}
  35
  36   OwningBinary<ObjectFile>
  37   getObjectForDebug(const ObjectFile &Obj) const override {
  38     return OwningBinary<ObjectFile>();
  39   }
  40 };
  41
  42 }
  43
  44 namespace llvm {
  45
  46 int64_t RuntimeDyldMachO::memcpyAddend(const RelocationEntry &RE) const {
  47   unsigned NumBytes = 1 << RE.Size;
  48   uint8_t *Src = Sections[RE.SectionID].Address + RE.Offset;
  49
  50   return static_cast<int64_t>(readBytesUnaligned(Src, NumBytes));
  51 }
  52
  53 RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
  54     const ObjectFile &BaseTObj, const relocation_iterator &RI,
  55     const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID) {
  56
  57   const MachOObjectFile &Obj =
  58       static_cast<const MachOObjectFile &>(BaseTObj);
  59   MachO::any_relocation_info RelInfo =
  60       Obj.getRelocation(RI->getRawDataRefImpl());
  61   RelocationValueRef Value;
  62
  63   bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
  64   if (IsExternal) {
  65     symbol_iterator Symbol = RI->getSymbol();
  66     ErrorOr<StringRef> TargetNameOrErr = Symbol->getName();
  67     if (std::error_code EC = TargetNameOrErr.getError())
  68       report_fatal_error(EC.message());
  69     StringRef TargetName = *TargetNameOrErr;
  70     RTDyldSymbolTable::const_iterator SI =
  71       GlobalSymbolTable.find(TargetName.data());
  72     if (SI != GlobalSymbolTable.end()) {
  73       const auto &SymInfo = SI->second;
  74       Value.SectionID = SymInfo.getSectionID();
  75       Value.Offset = SymInfo.getOffset() + RE.Addend;
  76     } else {
  77       Value.SymbolName = TargetName.data();
  78       Value.Offset = RE.Addend;
  79     }
  80   } else {
  81     SectionRef Sec = Obj.getAnyRelocationSection(RelInfo);
  82     bool IsCode = Sec.isText();
  83     Value.SectionID = findOrEmitSection(Obj, Sec, IsCode, ObjSectionToID);
  84     uint64_t Addr = Sec.getAddress();
  85     Value.Offset = RE.Addend - Addr;
  86   }
  87
  88   return Value;
  89 }
  90
  91 void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
  92                                             const relocation_iterator &RI,
  93                                             unsigned OffsetToNextPC) {
  94   auto &O = *cast<MachOObjectFile>(RI->getObject());
  95   section_iterator SecI = O.getRelocationRelocatedSection(RI);
  96   Value.Offset += RI->getOffset() + OffsetToNextPC + SecI->getAddress();
  97 }
  98
  99 void RuntimeDyldMachO::dumpRelocationToResolve(const RelocationEntry &RE,
 100                                                uint64_t Value) const {
 101   const SectionEntry &Section = Sections[RE.SectionID];
 102   uint8_t *LocalAddress = Section.Address + RE.Offset;
 103   uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
 104
 105   dbgs() << "resolveRelocation Section: " << RE.SectionID
 106          << " LocalAddress: " << format("%p", LocalAddress)
 107          << " FinalAddress: " << format("0x%016" PRIx64, FinalAddress)
 108          << " Value: " << format("0x%016" PRIx64, Value) << " Addend: " << RE.Addend
 109          << " isPCRel: " << RE.IsPCRel << " MachoType: " << RE.RelType
 110          << " Size: " << (1 << RE.Size) << "\n";
 111 }
 112
 113 section_iterator
 114 RuntimeDyldMachO::getSectionByAddress(const MachOObjectFile &Obj,
 115                                       uint64_t Addr) {
 116   section_iterator SI = Obj.section_begin();
 117   section_iterator SE = Obj.section_end();
 118
 119   for (; SI != SE; ++SI) {
 120     uint64_t SAddr = SI->getAddress();
 121     uint64_t SSize = SI->getSize();
 122     if ((Addr >= SAddr) && (Addr < SAddr + SSize))
 123       return SI;
 124   }
 125
 126   return SE;
 127 }
 128
 129
 130 // Populate __pointers section.
 131 void RuntimeDyldMachO::populateIndirectSymbolPointersSection(
 132                                                     const MachOObjectFile &Obj,
 133                                                     const SectionRef &PTSection,
 134                                                     unsigned PTSectionID) {
 135   assert(!Obj.is64Bit() &&
 136          "Pointer table section not supported in 64-bit MachO.");
 137
 138   MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 139   MachO::section Sec32 = Obj.getSection(PTSection.getRawDataRefImpl());
 140   uint32_t PTSectionSize = Sec32.size;
 141   unsigned FirstIndirectSymbol = Sec32.reserved1;
 142   const unsigned PTEntrySize = 4;
 143   unsigned NumPTEntries = PTSectionSize / PTEntrySize;
 144   unsigned PTEntryOffset = 0;
 145
 146   assert((PTSectionSize % PTEntrySize) == 0 &&
 147          "Pointers section does not contain a whole number of stubs?");
 148
 149   DEBUG(dbgs() << "Populating pointer table section "
 150                << Sections[PTSectionID].Name
 151                << ", Section ID " << PTSectionID << ", "
 152                << NumPTEntries << " entries, " << PTEntrySize
 153                << " bytes each:\n");
 154
 155   for (unsigned i = 0; i < NumPTEntries; ++i) {
 156     unsigned SymbolIndex =
 157       Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 158     symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 159     ErrorOr<StringRef> IndirectSymbolNameOrErr = SI->getName();
 160     if (std::error_code EC = IndirectSymbolNameOrErr.getError())
 161       report_fatal_error(EC.message());
 162     StringRef IndirectSymbolName = *IndirectSymbolNameOrErr;
 163     DEBUG(dbgs() << "  " << IndirectSymbolName << ": index " << SymbolIndex
 164           << ", PT offset: " << PTEntryOffset << "\n");
 165     RelocationEntry RE(PTSectionID, PTEntryOffset,
 166                        MachO::GENERIC_RELOC_VANILLA, 0, false, 2);
 167     addRelocationForSymbol(RE, IndirectSymbolName);
 168     PTEntryOffset += PTEntrySize;
 169   }
 170 }
 171
 172 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile &Obj) const {
 173   return Obj.isMachO();
 174 }
 175
 176 template <typename Impl>
 177 void RuntimeDyldMachOCRTPBase<Impl>::finalizeLoad(const ObjectFile &Obj,
 178                                                   ObjSectionToIDMap &SectionMap) {
 179   unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
 180   unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
 181   unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
 182
 183   for (const auto &Section : Obj.sections()) {
 184     StringRef Name;
 185     Section.getName(Name);
 186
 187     // Force emission of the __text, __eh_frame, and __gcc_except_tab sections
 188     // if they're present. Otherwise call down to the impl to handle other
 189     // sections that have already been emitted.
 190     if (Name == "__text")
 191       TextSID = findOrEmitSection(Obj, Section, true, SectionMap);
 192     else if (Name == "__eh_frame")
 193       EHFrameSID = findOrEmitSection(Obj, Section, false, SectionMap);
 194     else if (Name == "__gcc_except_tab")
 195       ExceptTabSID = findOrEmitSection(Obj, Section, true, SectionMap);
 196     else {
 197       auto I = SectionMap.find(Section);
 198       if (I != SectionMap.end())
 199         impl().finalizeSection(Obj, I->second, Section);
 200     }
 201   }
 202   UnregisteredEHFrameSections.push_back(
 203     EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
 204 }
 205
 206 template <typename Impl>
 207 unsigned char *RuntimeDyldMachOCRTPBase<Impl>::processFDE(unsigned char *P,
 208                                                           int64_t DeltaForText,
 209                                                           int64_t DeltaForEH) {
 210   typedef typename Impl::TargetPtrT TargetPtrT;
 211
 212   DEBUG(dbgs() << "Processing FDE: Delta for text: " << DeltaForText
 213                << ", Delta for EH: " << DeltaForEH << "\n");
 214   uint32_t Length = readBytesUnaligned(P, 4);
 215   P += 4;
 216   unsigned char *Ret = P + Length;
 217   uint32_t Offset = readBytesUnaligned(P, 4);
 218   if (Offset == 0) // is a CIE
 219     return Ret;
 220
 221   P += 4;
 222   TargetPtrT FDELocation = readBytesUnaligned(P, sizeof(TargetPtrT));
 223   TargetPtrT NewLocation = FDELocation - DeltaForText;
 224   writeBytesUnaligned(NewLocation, P, sizeof(TargetPtrT));
 225
 226   P += sizeof(TargetPtrT);
 227
 228   // Skip the FDE address range
 229   P += sizeof(TargetPtrT);
 230
 231   uint8_t Augmentationsize = *P;
 232   P += 1;
 233   if (Augmentationsize != 0) {
 234     TargetPtrT LSDA = readBytesUnaligned(P, sizeof(TargetPtrT));
 235     TargetPtrT NewLSDA = LSDA - DeltaForEH;
 236     writeBytesUnaligned(NewLSDA, P, sizeof(TargetPtrT));
 237   }
 238
 239   return Ret;
 240 }
 241
 242 static int64_t computeDelta(SectionEntry *A, SectionEntry *B) {
 243   int64_t ObjDistance =
 244     static_cast<int64_t>(A->ObjAddress) - static_cast<int64_t>(B->ObjAddress);
 245   int64_t MemDistance = A->LoadAddress - B->LoadAddress;
 246   return ObjDistance - MemDistance;
 247 }
 248
 249 template <typename Impl>
 250 void RuntimeDyldMachOCRTPBase<Impl>::registerEHFrames() {
 251
 252   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
 253     EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
 254     if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
 255         SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
 256       continue;
 257     SectionEntry *Text = &Sections[SectionInfo.TextSID];
 258     SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
 259     SectionEntry *ExceptTab = nullptr;
 260     if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
 261       ExceptTab = &Sections[SectionInfo.ExceptTabSID];
 262
 263     int64_t DeltaForText = computeDelta(Text, EHFrame);
 264     int64_t DeltaForEH = 0;
 265     if (ExceptTab)
 266       DeltaForEH = computeDelta(ExceptTab, EHFrame);
 267
 268     unsigned char *P = EHFrame->Address;
 269     unsigned char *End = P + EHFrame->Size;
 270     do {
 271       P = processFDE(P, DeltaForText, DeltaForEH);
 272     } while (P != End);
 273
 274     MemMgr.registerEHFrames(EHFrame->Address, EHFrame->LoadAddress,
 275                             EHFrame->Size);
 276   }
 277   UnregisteredEHFrameSections.clear();
 278 }
 279
 280 std::unique_ptr<RuntimeDyldMachO>
 281 RuntimeDyldMachO::create(Triple::ArchType Arch,
 282                          RuntimeDyld::MemoryManager &MemMgr,
 283                          RuntimeDyld::SymbolResolver &Resolver) {
 284   switch (Arch) {
 285   default:
 286     llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
 287     break;
 288   case Triple::arm:
 289     return make_unique<RuntimeDyldMachOARM>(MemMgr, Resolver);
 290   case Triple::aarch64:
 291     return make_unique<RuntimeDyldMachOAArch64>(MemMgr, Resolver);
 292   case Triple::x86:
 293     return make_unique<RuntimeDyldMachOI386>(MemMgr, Resolver);
 294   case Triple::x86_64:
 295     return make_unique<RuntimeDyldMachOX86_64>(MemMgr, Resolver);
 296   }
 297 }
 298
 299 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
 300 RuntimeDyldMachO::loadObject(const object::ObjectFile &O) {
 301   unsigned SectionStartIdx, SectionEndIdx;
 302   std::tie(SectionStartIdx, SectionEndIdx) = loadObjectImpl(O);
 303   return llvm::make_unique<LoadedMachOObjectInfo>(*this, SectionStartIdx,
 304                                                   SectionEndIdx);
 305 }
 306
 307 } // end namespace llvm