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 : public RuntimeDyld::LoadedObjectInfo {
  30 public:
  31   LoadedMachOObjectInfo(RuntimeDyldImpl &RTDyld, unsigned BeginIdx,
  32                         unsigned EndIdx)
  33     : RuntimeDyld::LoadedObjectInfo(RTDyld, BeginIdx, EndIdx) {}
  34
  35   OwningBinary<ObjectFile>
  36   getObjectForDebug(const ObjectFile &Obj) const override {
  37     return OwningBinary<ObjectFile>();
  38   }
  39
  40   RuntimeDyld::LoadedObjectInfo *clone() const { return new LoadedMachOObjectInfo(*this); }
  41 };
  42
  43 }
  44
  45 namespace llvm {
  46
  47 int64_t RuntimeDyldMachO::memcpyAddend(const RelocationEntry &RE) const {
  48   unsigned NumBytes = 1 << RE.Size;
  49   uint8_t *Src = Sections[RE.SectionID].Address + RE.Offset;
  50
  51   return static_cast<int64_t>(readBytesUnaligned(Src, NumBytes));
  52 }
  53
  54 RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
  55     const ObjectFile &BaseTObj, const relocation_iterator &RI,
  56     const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID) {
  57
  58   const MachOObjectFile &Obj =
  59       static_cast<const MachOObjectFile &>(BaseTObj);
  60   MachO::any_relocation_info RelInfo =
  61       Obj.getRelocation(RI->getRawDataRefImpl());
  62   RelocationValueRef Value;
  63
  64   bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
  65   if (IsExternal) {
  66     symbol_iterator Symbol = RI->getSymbol();
  67     StringRef TargetName;
  68     Symbol->getName(TargetName);
  69     RTDyldSymbolTable::const_iterator SI =
  70       GlobalSymbolTable.find(TargetName.data());
  71     if (SI != GlobalSymbolTable.end()) {
  72       const auto &SymInfo = SI->second;
  73       Value.SectionID = SymInfo.getSectionID();
  74       Value.Offset = SymInfo.getOffset() + RE.Addend;
  75     } else {
  76       Value.SymbolName = TargetName.data();
  77       Value.Offset = RE.Addend;
  78     }
  79   } else {
  80     SectionRef Sec = Obj.getAnyRelocationSection(RelInfo);
  81     bool IsCode = Sec.isText();
  82     Value.SectionID = findOrEmitSection(Obj, Sec, IsCode, ObjSectionToID);
  83     uint64_t Addr = Sec.getAddress();
  84     Value.Offset = RE.Addend - Addr;
  85   }
  86
  87   return Value;
  88 }
  89
  90 void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
  91                                             const ObjectFile &BaseTObj,
  92                                             const relocation_iterator &RI,
  93                                             unsigned OffsetToNextPC) {
  94   const MachOObjectFile &Obj =
  95       static_cast<const MachOObjectFile &>(BaseTObj);
  96   MachO::any_relocation_info RelInfo =
  97       Obj.getRelocation(RI->getRawDataRefImpl());
  98
  99   bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
 100   if (IsPCRel) {
 101     uint64_t RelocAddr = 0;
 102     RI->getAddress(RelocAddr);
 103     Value.Offset += RelocAddr + OffsetToNextPC;
 104   }
 105 }
 106
 107 void RuntimeDyldMachO::dumpRelocationToResolve(const RelocationEntry &RE,
 108                                                uint64_t Value) const {
 109   const SectionEntry &Section = Sections[RE.SectionID];
 110   uint8_t *LocalAddress = Section.Address + RE.Offset;
 111   uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
 112
 113   dbgs() << "resolveRelocation Section: " << RE.SectionID
 114          << " LocalAddress: " << format("%p", LocalAddress)
 115          << " FinalAddress: " << format("0x%016" PRIx64, FinalAddress)
 116          << " Value: " << format("0x%016" PRIx64, Value) << " Addend: " << RE.Addend
 117          << " isPCRel: " << RE.IsPCRel << " MachoType: " << RE.RelType
 118          << " Size: " << (1 << RE.Size) << "\n";
 119 }
 120
 121 section_iterator
 122 RuntimeDyldMachO::getSectionByAddress(const MachOObjectFile &Obj,
 123                                       uint64_t Addr) {
 124   section_iterator SI = Obj.section_begin();
 125   section_iterator SE = Obj.section_end();
 126
 127   for (; SI != SE; ++SI) {
 128     uint64_t SAddr = SI->getAddress();
 129     uint64_t SSize = SI->getSize();
 130     if ((Addr >= SAddr) && (Addr < SAddr + SSize))
 131       return SI;
 132   }
 133
 134   return SE;
 135 }
 136
 137
 138 // Populate __pointers section.
 139 void RuntimeDyldMachO::populateIndirectSymbolPointersSection(
 140                                                     const MachOObjectFile &Obj,
 141                                                     const SectionRef &PTSection,
 142                                                     unsigned PTSectionID) {
 143   assert(!Obj.is64Bit() &&
 144          "Pointer table section not supported in 64-bit MachO.");
 145
 146   MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 147   MachO::section Sec32 = Obj.getSection(PTSection.getRawDataRefImpl());
 148   uint32_t PTSectionSize = Sec32.size;
 149   unsigned FirstIndirectSymbol = Sec32.reserved1;
 150   const unsigned PTEntrySize = 4;
 151   unsigned NumPTEntries = PTSectionSize / PTEntrySize;
 152   unsigned PTEntryOffset = 0;
 153
 154   assert((PTSectionSize % PTEntrySize) == 0 &&
 155          "Pointers section does not contain a whole number of stubs?");
 156
 157   DEBUG(dbgs() << "Populating pointer table section "
 158                << Sections[PTSectionID].Name
 159                << ", Section ID " << PTSectionID << ", "
 160                << NumPTEntries << " entries, " << PTEntrySize
 161                << " bytes each:\n");
 162
 163   for (unsigned i = 0; i < NumPTEntries; ++i) {
 164     unsigned SymbolIndex =
 165       Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 166     symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 167     StringRef IndirectSymbolName;
 168     SI->getName(IndirectSymbolName);
 169     DEBUG(dbgs() << "  " << IndirectSymbolName << ": index " << SymbolIndex
 170           << ", PT offset: " << PTEntryOffset << "\n");
 171     RelocationEntry RE(PTSectionID, PTEntryOffset,
 172                        MachO::GENERIC_RELOC_VANILLA, 0, false, 2);
 173     addRelocationForSymbol(RE, IndirectSymbolName);
 174     PTEntryOffset += PTEntrySize;
 175   }
 176 }
 177
 178 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile &Obj) const {
 179   return Obj.isMachO();
 180 }
 181
 182 template <typename Impl>
 183 void RuntimeDyldMachOCRTPBase<Impl>::finalizeLoad(const ObjectFile &Obj,
 184                                                   ObjSectionToIDMap &SectionMap) {
 185   unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
 186   unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
 187   unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
 188
 189   for (const auto &Section : Obj.sections()) {
 190     StringRef Name;
 191     Section.getName(Name);
 192
 193     // Force emission of the __text, __eh_frame, and __gcc_except_tab sections
 194     // if they're present. Otherwise call down to the impl to handle other
 195     // sections that have already been emitted.
 196     if (Name == "__text")
 197       TextSID = findOrEmitSection(Obj, Section, true, SectionMap);
 198     else if (Name == "__eh_frame")
 199       EHFrameSID = findOrEmitSection(Obj, Section, false, SectionMap);
 200     else if (Name == "__gcc_except_tab")
 201       ExceptTabSID = findOrEmitSection(Obj, Section, true, SectionMap);
 202     else {
 203       auto I = SectionMap.find(Section);
 204       if (I != SectionMap.end())
 205         impl().finalizeSection(Obj, I->second, Section);
 206     }
 207   }
 208   UnregisteredEHFrameSections.push_back(
 209     EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
 210 }
 211
 212 template <typename Impl>
 213 unsigned char *RuntimeDyldMachOCRTPBase<Impl>::processFDE(unsigned char *P,
 214                                                           int64_t DeltaForText,
 215                                                           int64_t DeltaForEH) {
 216   typedef typename Impl::TargetPtrT TargetPtrT;
 217
 218   DEBUG(dbgs() << "Processing FDE: Delta for text: " << DeltaForText
 219                << ", Delta for EH: " << DeltaForEH << "\n");
 220   uint32_t Length = readBytesUnaligned(P, 4);
 221   P += 4;
 222   unsigned char *Ret = P + Length;
 223   uint32_t Offset = readBytesUnaligned(P, 4);
 224   if (Offset == 0) // is a CIE
 225     return Ret;
 226
 227   P += 4;
 228   TargetPtrT FDELocation = readBytesUnaligned(P, sizeof(TargetPtrT));
 229   TargetPtrT NewLocation = FDELocation - DeltaForText;
 230   writeBytesUnaligned(NewLocation, P, sizeof(TargetPtrT));
 231
 232   P += sizeof(TargetPtrT);
 233
 234   // Skip the FDE address range
 235   P += sizeof(TargetPtrT);
 236
 237   uint8_t Augmentationsize = *P;
 238   P += 1;
 239   if (Augmentationsize != 0) {
 240     TargetPtrT LSDA = readBytesUnaligned(P, sizeof(TargetPtrT));
 241     TargetPtrT NewLSDA = LSDA - DeltaForEH;
 242     writeBytesUnaligned(NewLSDA, P, sizeof(TargetPtrT));
 243   }
 244
 245   return Ret;
 246 }
 247
 248 static int64_t computeDelta(SectionEntry *A, SectionEntry *B) {
 249   int64_t ObjDistance =
 250     static_cast<int64_t>(A->ObjAddress) - static_cast<int64_t>(B->ObjAddress);
 251   int64_t MemDistance = A->LoadAddress - B->LoadAddress;
 252   return ObjDistance - MemDistance;
 253 }
 254
 255 template <typename Impl>
 256 void RuntimeDyldMachOCRTPBase<Impl>::registerEHFrames() {
 257
 258   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
 259     EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
 260     if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
 261         SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
 262       continue;
 263     SectionEntry *Text = &Sections[SectionInfo.TextSID];
 264     SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
 265     SectionEntry *ExceptTab = nullptr;
 266     if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
 267       ExceptTab = &Sections[SectionInfo.ExceptTabSID];
 268
 269     int64_t DeltaForText = computeDelta(Text, EHFrame);
 270     int64_t DeltaForEH = 0;
 271     if (ExceptTab)
 272       DeltaForEH = computeDelta(ExceptTab, EHFrame);
 273
 274     unsigned char *P = EHFrame->Address;
 275     unsigned char *End = P + EHFrame->Size;
 276     do {
 277       P = processFDE(P, DeltaForText, DeltaForEH);
 278     } while (P != End);
 279
 280     MemMgr.registerEHFrames(EHFrame->Address, EHFrame->LoadAddress,
 281                             EHFrame->Size);
 282   }
 283   UnregisteredEHFrameSections.clear();
 284 }
 285
 286 std::unique_ptr<RuntimeDyldMachO>
 287 RuntimeDyldMachO::create(Triple::ArchType Arch,
 288                          RuntimeDyld::MemoryManager &MemMgr,
 289                          RuntimeDyld::SymbolResolver &Resolver) {
 290   switch (Arch) {
 291   default:
 292     llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
 293     break;
 294   case Triple::arm:
 295     return make_unique<RuntimeDyldMachOARM>(MemMgr, Resolver);
 296   case Triple::aarch64:
 297     return make_unique<RuntimeDyldMachOAArch64>(MemMgr, Resolver);
 298   case Triple::x86:
 299     return make_unique<RuntimeDyldMachOI386>(MemMgr, Resolver);
 300   case Triple::x86_64:
 301     return make_unique<RuntimeDyldMachOX86_64>(MemMgr, Resolver);
 302   }
 303 }
 304
 305 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
 306 RuntimeDyldMachO::loadObject(const object::ObjectFile &O) {
 307   unsigned SectionStartIdx, SectionEndIdx;
 308   std::tie(SectionStartIdx, SectionEndIdx) = loadObjectImpl(O);
 309   return llvm::make_unique<LoadedMachOObjectInfo>(*this, SectionStartIdx,
 310                                                   SectionEndIdx);
 311 }
 312
 313 } // end namespace llvm