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 "llvm/ADT/STLExtras.h"
  16 #include "llvm/ADT/StringRef.h"
  17
  18 #include "Targets/RuntimeDyldMachOARM.h"
  19 #include "Targets/RuntimeDyldMachOAArch64.h"
  20 #include "Targets/RuntimeDyldMachOI386.h"
  21 #include "Targets/RuntimeDyldMachOX86_64.h"
  22
  23 using namespace llvm;
  24 using namespace llvm::object;
  25
  26 #define DEBUG_TYPE "dyld"
  27
  28 namespace llvm {
  29
  30 int64_t RuntimeDyldMachO::memcpyAddend(const RelocationEntry &RE) const {
  31   unsigned NumBytes = 1 << RE.Size;
  32   uint8_t *Src = Sections[RE.SectionID].Address + RE.Offset;
  33
  34   return static_cast<int64_t>(readBytesUnaligned(Src, NumBytes));
  35 }
  36
  37 RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
  38     ObjectImage &ObjImg, const relocation_iterator &RI,
  39     const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID,
  40     const SymbolTableMap &Symbols) {
  41
  42   const MachOObjectFile &Obj =
  43       static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
  44   MachO::any_relocation_info RelInfo =
  45       Obj.getRelocation(RI->getRawDataRefImpl());
  46   RelocationValueRef Value;
  47
  48   bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
  49   if (IsExternal) {
  50     symbol_iterator Symbol = RI->getSymbol();
  51     StringRef TargetName;
  52     Symbol->getName(TargetName);
  53     SymbolTableMap::const_iterator SI = Symbols.find(TargetName.data());
  54     if (SI != Symbols.end()) {
  55       Value.SectionID = SI->second.first;
  56       Value.Offset = SI->second.second + RE.Addend;
  57     } else {
  58       SI = GlobalSymbolTable.find(TargetName.data());
  59       if (SI != GlobalSymbolTable.end()) {
  60         Value.SectionID = SI->second.first;
  61         Value.Offset = SI->second.second + RE.Addend;
  62       } else {
  63         Value.SymbolName = TargetName.data();
  64         Value.Offset = RE.Addend;
  65       }
  66     }
  67   } else {
  68     SectionRef Sec = Obj.getRelocationSection(RelInfo);
  69     bool IsCode = false;
  70     Sec.isText(IsCode);
  71     Value.SectionID = findOrEmitSection(ObjImg, Sec, IsCode, ObjSectionToID);
  72     uint64_t Addr;
  73     Sec.getAddress(Addr);
  74     Value.Offset = RE.Addend - Addr;
  75   }
  76
  77   return Value;
  78 }
  79
  80 void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
  81                                             ObjectImage &ObjImg,
  82                                             const relocation_iterator &RI,
  83                                             unsigned OffsetToNextPC) {
  84   const MachOObjectFile &Obj =
  85       static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
  86   MachO::any_relocation_info RelInfo =
  87       Obj.getRelocation(RI->getRawDataRefImpl());
  88
  89   bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
  90   if (IsPCRel) {
  91     uint64_t RelocAddr = 0;
  92     RI->getAddress(RelocAddr);
  93     Value.Offset += RelocAddr + OffsetToNextPC;
  94   }
  95 }
  96
  97 void RuntimeDyldMachO::dumpRelocationToResolve(const RelocationEntry &RE,
  98                                                uint64_t Value) const {
  99   const SectionEntry &Section = Sections[RE.SectionID];
 100   uint8_t *LocalAddress = Section.Address + RE.Offset;
 101   uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
 102
 103   dbgs() << "resolveRelocation Section: " << RE.SectionID
 104          << " LocalAddress: " << format("%p", LocalAddress)
 105          << " FinalAddress: " << format("0x%016" PRIx64, FinalAddress)
 106          << " Value: " << format("0x%016" PRIx64, Value) << " Addend: " << RE.Addend
 107          << " isPCRel: " << RE.IsPCRel << " MachoType: " << RE.RelType
 108          << " Size: " << (1 << RE.Size) << "\n";
 109 }
 110
 111 section_iterator
 112 RuntimeDyldMachO::getSectionByAddress(const MachOObjectFile &Obj,
 113                                       uint64_t Addr) {
 114   section_iterator SI = Obj.section_begin();
 115   section_iterator SE = Obj.section_end();
 116
 117   for (; SI != SE; ++SI) {
 118     uint64_t SAddr, SSize;
 119     SI->getAddress(SAddr);
 120     SI->getSize(SSize);
 121     if ((Addr >= SAddr) && (Addr < SAddr + SSize))
 122       return SI;
 123   }
 124
 125   return SE;
 126 }
 127
 128
 129 // Populate __pointers section.
 130 void RuntimeDyldMachO::populateIndirectSymbolPointersSection(
 131                                                     MachOObjectFile &Obj,
 132                                                     const SectionRef &PTSection,
 133                                                     unsigned PTSectionID) {
 134   assert(!Obj.is64Bit() &&
 135          "Pointer table section not supported in 64-bit MachO.");
 136
 137   MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 138   MachO::section Sec32 = Obj.getSection(PTSection.getRawDataRefImpl());
 139   uint32_t PTSectionSize = Sec32.size;
 140   unsigned FirstIndirectSymbol = Sec32.reserved1;
 141   const unsigned PTEntrySize = 4;
 142   unsigned NumPTEntries = PTSectionSize / PTEntrySize;
 143   unsigned PTEntryOffset = 0;
 144
 145   assert((PTSectionSize % PTEntrySize) == 0 &&
 146          "Pointers section does not contain a whole number of stubs?");
 147
 148   DEBUG(dbgs() << "Populating pointer table section "
 149                << Sections[PTSectionID].Name
 150                << ", Section ID " << PTSectionID << ", "
 151                << NumPTEntries << " entries, " << PTEntrySize
 152                << " bytes each:\n");
 153
 154   for (unsigned i = 0; i < NumPTEntries; ++i) {
 155     unsigned SymbolIndex =
 156       Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 157     symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 158     StringRef IndirectSymbolName;
 159     SI->getName(IndirectSymbolName);
 160     DEBUG(dbgs() << "  " << IndirectSymbolName << ": index " << SymbolIndex
 161           << ", PT offset: " << PTEntryOffset << "\n");
 162     RelocationEntry RE(PTSectionID, PTEntryOffset,
 163                        MachO::GENERIC_RELOC_VANILLA, 0, false, 2);
 164     addRelocationForSymbol(RE, IndirectSymbolName);
 165     PTEntryOffset += PTEntrySize;
 166   }
 167 }
 168
 169 bool
 170 RuntimeDyldMachO::isCompatibleFormat(const ObjectBuffer *InputBuffer) const {
 171   if (InputBuffer->getBufferSize() < 4)
 172     return false;
 173   StringRef Magic(InputBuffer->getBufferStart(), 4);
 174   if (Magic == "\xFE\xED\xFA\xCE")
 175     return true;
 176   if (Magic == "\xCE\xFA\xED\xFE")
 177     return true;
 178   if (Magic == "\xFE\xED\xFA\xCF")
 179     return true;
 180   if (Magic == "\xCF\xFA\xED\xFE")
 181     return true;
 182   return false;
 183 }
 184
 185 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile *Obj) const {
 186   return Obj->isMachO();
 187 }
 188
 189 template <typename Impl>
 190 void RuntimeDyldMachOCRTPBase<Impl>::finalizeLoad(ObjectImage &ObjImg,
 191                                                   ObjSectionToIDMap &SectionMap) {
 192   unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
 193   unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
 194   unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
 195   ObjSectionToIDMap::iterator i, e;
 196
 197   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
 198     const SectionRef &Section = i->first;
 199     StringRef Name;
 200     Section.getName(Name);
 201     if (Name == "__eh_frame")
 202       EHFrameSID = i->second;
 203     else if (Name == "__text")
 204       TextSID = i->second;
 205     else if (Name == "__gcc_except_tab")
 206       ExceptTabSID = i->second;
 207     else
 208       impl().finalizeSection(ObjImg, i->second, Section);
 209   }
 210   UnregisteredEHFrameSections.push_back(
 211     EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
 212 }
 213
 214 template <typename Impl>
 215 unsigned char *RuntimeDyldMachOCRTPBase<Impl>::processFDE(unsigned char *P,
 216                                                           int64_t DeltaForText,
 217                                                           int64_t DeltaForEH) {
 218   typedef typename Impl::TargetPtrT TargetPtrT;
 219
 220   DEBUG(dbgs() << "Processing FDE: Delta for text: " << DeltaForText
 221                << ", Delta for EH: " << DeltaForEH << "\n");
 222   uint32_t Length = *((uint32_t *)P);
 223   P += 4;
 224   unsigned char *Ret = P + Length;
 225   uint32_t Offset = *((uint32_t *)P);
 226   if (Offset == 0) // is a CIE
 227     return Ret;
 228
 229   P += 4;
 230   TargetPtrT FDELocation = *((TargetPtrT*)P);
 231   TargetPtrT NewLocation = FDELocation - DeltaForText;
 232   *((TargetPtrT*)P) = NewLocation;
 233   P += sizeof(TargetPtrT);
 234
 235   // Skip the FDE address range
 236   P += sizeof(TargetPtrT);
 237
 238   uint8_t Augmentationsize = *P;
 239   P += 1;
 240   if (Augmentationsize != 0) {
 241     TargetPtrT LSDA = *((TargetPtrT *)P);
 242     TargetPtrT NewLSDA = LSDA - DeltaForEH;
 243     *((TargetPtrT *)P) = NewLSDA;
 244   }
 245
 246   return Ret;
 247 }
 248
 249 static int64_t computeDelta(SectionEntry *A, SectionEntry *B) {
 250   int64_t ObjDistance = A->ObjAddress - 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   if (!MemMgr)
 259     return;
 260   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
 261     EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
 262     if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
 263         SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
 264       continue;
 265     SectionEntry *Text = &Sections[SectionInfo.TextSID];
 266     SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
 267     SectionEntry *ExceptTab = nullptr;
 268     if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
 269       ExceptTab = &Sections[SectionInfo.ExceptTabSID];
 270
 271     int64_t DeltaForText = computeDelta(Text, EHFrame);
 272     int64_t DeltaForEH = 0;
 273     if (ExceptTab)
 274       DeltaForEH = computeDelta(ExceptTab, EHFrame);
 275
 276     unsigned char *P = EHFrame->Address;
 277     unsigned char *End = P + EHFrame->Size;
 278     do {
 279       P = processFDE(P, DeltaForText, DeltaForEH);
 280     } while (P != End);
 281
 282     MemMgr->registerEHFrames(EHFrame->Address, EHFrame->LoadAddress,
 283                              EHFrame->Size);
 284   }
 285   UnregisteredEHFrameSections.clear();
 286 }
 287
 288 std::unique_ptr<RuntimeDyldMachO>
 289 llvm::RuntimeDyldMachO::create(Triple::ArchType Arch, RTDyldMemoryManager *MM) {
 290   switch (Arch) {
 291   default:
 292     llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
 293     break;
 294   case Triple::arm: return make_unique<RuntimeDyldMachOARM>(MM);
 295   case Triple::aarch64: return make_unique<RuntimeDyldMachOAArch64>(MM);
 296   case Triple::x86: return make_unique<RuntimeDyldMachOI386>(MM);
 297   case Triple::x86_64: return make_unique<RuntimeDyldMachOX86_64>(MM);
 298   }
 299 }
 300
 301 } // end namespace llvm