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