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