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 = Sec.isText();
  70     Value.SectionID = findOrEmitSection(ObjImg, Sec, IsCode, ObjSectionToID);
  71     uint64_t Addr = Sec.getAddress();
  72     Value.Offset = RE.Addend - Addr;
  73   }
  74
  75   return Value;
  76 }
  77
  78 void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
  79                                             ObjectImage &ObjImg,
  80                                             const relocation_iterator &RI,
  81                                             unsigned OffsetToNextPC) {
  82   const MachOObjectFile &Obj =
  83       static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
  84   MachO::any_relocation_info RelInfo =
  85       Obj.getRelocation(RI->getRawDataRefImpl());
  86
  87   bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
  88   if (IsPCRel) {
  89     uint64_t RelocAddr = 0;
  90     RI->getAddress(RelocAddr);
  91     Value.Offset += RelocAddr + OffsetToNextPC;
  92   }
  93 }
  94
  95 void RuntimeDyldMachO::dumpRelocationToResolve(const RelocationEntry &RE,
  96                                                uint64_t Value) const {
  97   const SectionEntry &Section = Sections[RE.SectionID];
  98   uint8_t *LocalAddress = Section.Address + RE.Offset;
  99   uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
 100
 101   dbgs() << "resolveRelocation Section: " << RE.SectionID
 102          << " LocalAddress: " << format("%p", LocalAddress)
 103          << " FinalAddress: " << format("0x%016" PRIx64, FinalAddress)
 104          << " Value: " << format("0x%016" PRIx64, Value) << " Addend: " << RE.Addend
 105          << " isPCRel: " << RE.IsPCRel << " MachoType: " << RE.RelType
 106          << " Size: " << (1 << RE.Size) << "\n";
 107 }
 108
 109 section_iterator
 110 RuntimeDyldMachO::getSectionByAddress(const MachOObjectFile &Obj,
 111                                       uint64_t Addr) {
 112   section_iterator SI = Obj.section_begin();
 113   section_iterator SE = Obj.section_end();
 114
 115   for (; SI != SE; ++SI) {
 116     uint64_t SAddr = SI->getAddress();
 117     uint64_t SSize = SI->getSize();
 118     if ((Addr >= SAddr) && (Addr < SAddr + SSize))
 119       return SI;
 120   }
 121
 122   return SE;
 123 }
 124
 125
 126 // Populate __pointers section.
 127 void RuntimeDyldMachO::populateIndirectSymbolPointersSection(
 128                                                     MachOObjectFile &Obj,
 129                                                     const SectionRef &PTSection,
 130                                                     unsigned PTSectionID) {
 131   assert(!Obj.is64Bit() &&
 132          "Pointer table section not supported in 64-bit MachO.");
 133
 134   MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 135   MachO::section Sec32 = Obj.getSection(PTSection.getRawDataRefImpl());
 136   uint32_t PTSectionSize = Sec32.size;
 137   unsigned FirstIndirectSymbol = Sec32.reserved1;
 138   const unsigned PTEntrySize = 4;
 139   unsigned NumPTEntries = PTSectionSize / PTEntrySize;
 140   unsigned PTEntryOffset = 0;
 141
 142   assert((PTSectionSize % PTEntrySize) == 0 &&
 143          "Pointers section does not contain a whole number of stubs?");
 144
 145   DEBUG(dbgs() << "Populating pointer table section "
 146                << Sections[PTSectionID].Name
 147                << ", Section ID " << PTSectionID << ", "
 148                << NumPTEntries << " entries, " << PTEntrySize
 149                << " bytes each:\n");
 150
 151   for (unsigned i = 0; i < NumPTEntries; ++i) {
 152     unsigned SymbolIndex =
 153       Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 154     symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 155     StringRef IndirectSymbolName;
 156     SI->getName(IndirectSymbolName);
 157     DEBUG(dbgs() << "  " << IndirectSymbolName << ": index " << SymbolIndex
 158           << ", PT offset: " << PTEntryOffset << "\n");
 159     RelocationEntry RE(PTSectionID, PTEntryOffset,
 160                        MachO::GENERIC_RELOC_VANILLA, 0, false, 2);
 161     addRelocationForSymbol(RE, IndirectSymbolName);
 162     PTEntryOffset += PTEntrySize;
 163   }
 164 }
 165
 166 bool
 167 RuntimeDyldMachO::isCompatibleFormat(const ObjectBuffer *InputBuffer) const {
 168   if (InputBuffer->getBufferSize() < 4)
 169     return false;
 170   StringRef Magic(InputBuffer->getBufferStart(), 4);
 171   if (Magic == "\xFE\xED\xFA\xCE")
 172     return true;
 173   if (Magic == "\xCE\xFA\xED\xFE")
 174     return true;
 175   if (Magic == "\xFE\xED\xFA\xCF")
 176     return true;
 177   if (Magic == "\xCF\xFA\xED\xFE")
 178     return true;
 179   return false;
 180 }
 181
 182 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile *Obj) const {
 183   return Obj->isMachO();
 184 }
 185
 186 template <typename Impl>
 187 void RuntimeDyldMachOCRTPBase<Impl>::finalizeLoad(ObjectImage &ObjImg,
 188                                                   ObjSectionToIDMap &SectionMap) {
 189   unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
 190   unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
 191   unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
 192   ObjSectionToIDMap::iterator i, e;
 193
 194   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
 195     const SectionRef &Section = i->first;
 196     StringRef Name;
 197     Section.getName(Name);
 198     if (Name == "__eh_frame")
 199       EHFrameSID = i->second;
 200     else if (Name == "__text")
 201       TextSID = i->second;
 202     else if (Name == "__gcc_except_tab")
 203       ExceptTabSID = i->second;
 204     else
 205       impl().finalizeSection(ObjImg, i->second, Section);
 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 = A->ObjAddress - B->ObjAddress;
 249   int64_t MemDistance = A->LoadAddress - B->LoadAddress;
 250   return ObjDistance - MemDistance;
 251 }
 252
 253 template <typename Impl>
 254 void RuntimeDyldMachOCRTPBase<Impl>::registerEHFrames() {
 255
 256   if (!MemMgr)
 257     return;
 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 llvm::RuntimeDyldMachO::create(Triple::ArchType Arch, RTDyldMemoryManager *MM) {
 288   switch (Arch) {
 289   default:
 290     llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
 291     break;
 292   case Triple::arm: return make_unique<RuntimeDyldMachOARM>(MM);
 293   case Triple::aarch64: return make_unique<RuntimeDyldMachOAArch64>(MM);
 294   case Triple::x86: return make_unique<RuntimeDyldMachOI386>(MM);
 295   case Triple::x86_64: return make_unique<RuntimeDyldMachOX86_64>(MM);
 296   }
 297 }
 298
 299 } // end namespace llvm