lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOI386.h

   1 //===---- RuntimeDyldMachOI386.h ---- MachO/I386 specific code. ---*- 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 #ifndef LLVM_RUNTIMEDYLDMACHOI386_H
  11 #define LLVM_RUNTIMEDYLDMACHOI386_H
  12
  13 #include "../RuntimeDyldMachO.h"
  14
  15 #define DEBUG_TYPE "dyld"
  16
  17 namespace llvm {
  18
  19 class RuntimeDyldMachOI386
  20     : public RuntimeDyldMachOCRTPBase<RuntimeDyldMachOI386> {
  21 public:
  22   RuntimeDyldMachOI386(RTDyldMemoryManager *MM)
  23       : RuntimeDyldMachOCRTPBase(MM) {}
  24
  25   unsigned getMaxStubSize() override { return 0; }
  26
  27   unsigned getStubAlignment() override { return 1; }
  28
  29   relocation_iterator
  30   processRelocationRef(unsigned SectionID, relocation_iterator RelI,
  31                        ObjectImage &ObjImg, ObjSectionToIDMap &ObjSectionToID,
  32                        const SymbolTableMap &Symbols, StubMap &Stubs) override {
  33     const MachOObjectFile &Obj =
  34         static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
  35     MachO::any_relocation_info RelInfo =
  36         Obj.getRelocation(RelI->getRawDataRefImpl());
  37     uint32_t RelType = Obj.getAnyRelocationType(RelInfo);
  38
  39     if (Obj.isRelocationScattered(RelInfo)) {
  40       if (RelType == MachO::GENERIC_RELOC_SECTDIFF ||
  41           RelType == MachO::GENERIC_RELOC_LOCAL_SECTDIFF)
  42         return processSECTDIFFRelocation(SectionID, RelI, ObjImg,
  43                                          ObjSectionToID);
  44       else if (Arch == Triple::x86 && RelType == MachO::GENERIC_RELOC_VANILLA)
  45         return processI386ScatteredVANILLA(SectionID, RelI, ObjImg,
  46                                            ObjSectionToID);
  47       llvm_unreachable("Unhandled scattered relocation.");
  48     }
  49
  50     RelocationEntry RE(getBasicRelocationEntry(SectionID, ObjImg, RelI));
  51     RelocationValueRef Value(
  52         getRelocationValueRef(ObjImg, RelI, RE, ObjSectionToID, Symbols));
  53
  54     // Addends for external, PC-rel relocations on i386 point back to the zero
  55     // offset. Calculate the final offset from the relocation target instead.
  56     // This allows us to use the same logic for both external and internal
  57     // relocations in resolveI386RelocationRef.
  58     // bool IsExtern = Obj.getPlainRelocationExternal(RelInfo);
  59     // if (IsExtern && RE.IsPCRel) {
  60     //   uint64_t RelocAddr = 0;
  61     //   RelI->getAddress(RelocAddr);
  62     //   Value.Addend += RelocAddr + 4;
  63     // }
  64     if (RE.IsPCRel)
  65       makeValueAddendPCRel(Value, ObjImg, RelI, 1 << RE.Size);
  66
  67     RE.Addend = Value.Addend;
  68
  69     if (Value.SymbolName)
  70       addRelocationForSymbol(RE, Value.SymbolName);
  71     else
  72       addRelocationForSection(RE, Value.SectionID);
  73
  74     return ++RelI;
  75   }
  76
  77   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) {
  78     DEBUG(dumpRelocationToResolve(RE, Value));
  79
  80     const SectionEntry &Section = Sections[RE.SectionID];
  81     uint8_t *LocalAddress = Section.Address + RE.Offset;
  82
  83     if (RE.IsPCRel) {
  84       uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
  85       Value -= FinalAddress + 4; // see MachOX86_64::resolveRelocation.
  86     }
  87
  88     switch (RE.RelType) {
  89     default:
  90       llvm_unreachable("Invalid relocation type!");
  91     case MachO::GENERIC_RELOC_VANILLA:
  92       writeBytesUnaligned(LocalAddress, Value + RE.Addend, 1 << RE.Size);
  93       break;
  94     case MachO::GENERIC_RELOC_SECTDIFF:
  95     case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
  96       uint64_t SectionABase = Sections[RE.Sections.SectionA].LoadAddress;
  97       uint64_t SectionBBase = Sections[RE.Sections.SectionB].LoadAddress;
  98       assert((Value == SectionABase || Value == SectionBBase) &&
  99              "Unexpected SECTDIFF relocation value.");
 100       Value = SectionABase - SectionBBase + RE.Addend;
 101       writeBytesUnaligned(LocalAddress, Value, 1 << RE.Size);
 102       break;
 103     }
 104     case MachO::GENERIC_RELOC_PB_LA_PTR:
 105       Error("Relocation type not implemented yet!");
 106     }
 107   }
 108
 109   void finalizeSection(ObjectImage &ObjImg, unsigned SectionID,
 110                        const SectionRef &Section) {
 111     StringRef Name;
 112     Section.getName(Name);
 113
 114     if (Name == "__jump_table")
 115       populateJumpTable(cast<MachOObjectFile>(*ObjImg.getObjectFile()), Section,
 116                         SectionID);
 117     else if (Name == "__pointers")
 118       populatePointersSection(cast<MachOObjectFile>(*ObjImg.getObjectFile()),
 119                               Section, SectionID);
 120   }
 121
 122 private:
 123   relocation_iterator
 124   processSECTDIFFRelocation(unsigned SectionID, relocation_iterator RelI,
 125                             ObjectImage &Obj,
 126                             ObjSectionToIDMap &ObjSectionToID) {
 127     const MachOObjectFile *MachO =
 128         static_cast<const MachOObjectFile *>(Obj.getObjectFile());
 129     MachO::any_relocation_info RE =
 130         MachO->getRelocation(RelI->getRawDataRefImpl());
 131
 132     SectionEntry &Section = Sections[SectionID];
 133     uint32_t RelocType = MachO->getAnyRelocationType(RE);
 134     bool IsPCRel = MachO->getAnyRelocationPCRel(RE);
 135     unsigned Size = MachO->getAnyRelocationLength(RE);
 136     uint64_t Offset;
 137     RelI->getOffset(Offset);
 138     uint8_t *LocalAddress = Section.Address + Offset;
 139     unsigned NumBytes = 1 << Size;
 140     int64_t Addend = 0;
 141     memcpy(&Addend, LocalAddress, NumBytes);
 142
 143     ++RelI;
 144     MachO::any_relocation_info RE2 =
 145         MachO->getRelocation(RelI->getRawDataRefImpl());
 146
 147     uint32_t AddrA = MachO->getScatteredRelocationValue(RE);
 148     section_iterator SAI = getSectionByAddress(*MachO, AddrA);
 149     assert(SAI != MachO->section_end() && "Can't find section for address A");
 150     uint64_t SectionABase;
 151     SAI->getAddress(SectionABase);
 152     uint64_t SectionAOffset = AddrA - SectionABase;
 153     SectionRef SectionA = *SAI;
 154     bool IsCode;
 155     SectionA.isText(IsCode);
 156     uint32_t SectionAID =
 157         findOrEmitSection(Obj, SectionA, IsCode, ObjSectionToID);
 158
 159     uint32_t AddrB = MachO->getScatteredRelocationValue(RE2);
 160     section_iterator SBI = getSectionByAddress(*MachO, AddrB);
 161     assert(SBI != MachO->section_end() && "Can't find section for address B");
 162     uint64_t SectionBBase;
 163     SBI->getAddress(SectionBBase);
 164     uint64_t SectionBOffset = AddrB - SectionBBase;
 165     SectionRef SectionB = *SBI;
 166     uint32_t SectionBID =
 167         findOrEmitSection(Obj, SectionB, IsCode, ObjSectionToID);
 168
 169     if (Addend != AddrA - AddrB)
 170       Error("Unexpected SECTDIFF relocation addend.");
 171
 172     DEBUG(dbgs() << "Found SECTDIFF: AddrA: " << AddrA << ", AddrB: " << AddrB
 173                  << ", Addend: " << Addend << ", SectionA ID: " << SectionAID
 174                  << ", SectionAOffset: " << SectionAOffset
 175                  << ", SectionB ID: " << SectionBID
 176                  << ", SectionBOffset: " << SectionBOffset << "\n");
 177     RelocationEntry R(SectionID, Offset, RelocType, 0, SectionAID,
 178                       SectionAOffset, SectionBID, SectionBOffset, IsPCRel,
 179                       Size);
 180
 181     addRelocationForSection(R, SectionAID);
 182     addRelocationForSection(R, SectionBID);
 183
 184     return ++RelI;
 185   }
 186
 187   relocation_iterator processI386ScatteredVANILLA(
 188       unsigned SectionID, relocation_iterator RelI, ObjectImage &Obj,
 189       RuntimeDyldMachO::ObjSectionToIDMap &ObjSectionToID) {
 190     const MachOObjectFile *MachO =
 191         static_cast<const MachOObjectFile *>(Obj.getObjectFile());
 192     MachO::any_relocation_info RE =
 193         MachO->getRelocation(RelI->getRawDataRefImpl());
 194
 195     SectionEntry &Section = Sections[SectionID];
 196     uint32_t RelocType = MachO->getAnyRelocationType(RE);
 197     bool IsPCRel = MachO->getAnyRelocationPCRel(RE);
 198     unsigned Size = MachO->getAnyRelocationLength(RE);
 199     uint64_t Offset;
 200     RelI->getOffset(Offset);
 201     uint8_t *LocalAddress = Section.Address + Offset;
 202     unsigned NumBytes = 1 << Size;
 203     int64_t Addend = 0;
 204     memcpy(&Addend, LocalAddress, NumBytes);
 205
 206     unsigned SymbolBaseAddr = MachO->getScatteredRelocationValue(RE);
 207     section_iterator TargetSI = getSectionByAddress(*MachO, SymbolBaseAddr);
 208     assert(TargetSI != MachO->section_end() && "Can't find section for symbol");
 209     uint64_t SectionBaseAddr;
 210     TargetSI->getAddress(SectionBaseAddr);
 211     SectionRef TargetSection = *TargetSI;
 212     bool IsCode;
 213     TargetSection.isText(IsCode);
 214     uint32_t TargetSectionID =
 215         findOrEmitSection(Obj, TargetSection, IsCode, ObjSectionToID);
 216
 217     Addend -= SectionBaseAddr;
 218     RelocationEntry R(SectionID, Offset, RelocType, Addend, IsPCRel, Size);
 219
 220     addRelocationForSection(R, TargetSectionID);
 221
 222     return ++RelI;
 223   }
 224
 225   // Populate stubs in __jump_table section.
 226   void populateJumpTable(MachOObjectFile &Obj, const SectionRef &JTSection,
 227                          unsigned JTSectionID) {
 228     assert(!Obj.is64Bit() &&
 229            "__jump_table section not supported in 64-bit MachO.");
 230
 231     MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 232     MachO::section Sec32 = Obj.getSection(JTSection.getRawDataRefImpl());
 233     uint32_t JTSectionSize = Sec32.size;
 234     unsigned FirstIndirectSymbol = Sec32.reserved1;
 235     unsigned JTEntrySize = Sec32.reserved2;
 236     unsigned NumJTEntries = JTSectionSize / JTEntrySize;
 237     uint8_t *JTSectionAddr = getSectionAddress(JTSectionID);
 238     unsigned JTEntryOffset = 0;
 239
 240     assert((JTSectionSize % JTEntrySize) == 0 &&
 241            "Jump-table section does not contain a whole number of stubs?");
 242
 243     for (unsigned i = 0; i < NumJTEntries; ++i) {
 244       unsigned SymbolIndex =
 245           Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 246       symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 247       StringRef IndirectSymbolName;
 248       SI->getName(IndirectSymbolName);
 249       uint8_t *JTEntryAddr = JTSectionAddr + JTEntryOffset;
 250       createStubFunction(JTEntryAddr);
 251       RelocationEntry RE(JTSectionID, JTEntryOffset + 1,
 252                          MachO::GENERIC_RELOC_VANILLA, 0, true, 2);
 253       addRelocationForSymbol(RE, IndirectSymbolName);
 254       JTEntryOffset += JTEntrySize;
 255     }
 256   }
 257
 258   // Populate __pointers section.
 259   void populatePointersSection(MachOObjectFile &Obj,
 260                                const SectionRef &PTSection,
 261                                unsigned PTSectionID) {
 262     assert(!Obj.is64Bit() &&
 263            "__pointers section not supported in 64-bit MachO.");
 264
 265     MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 266     MachO::section Sec32 = Obj.getSection(PTSection.getRawDataRefImpl());
 267     uint32_t PTSectionSize = Sec32.size;
 268     unsigned FirstIndirectSymbol = Sec32.reserved1;
 269     const unsigned PTEntrySize = 4;
 270     unsigned NumPTEntries = PTSectionSize / PTEntrySize;
 271     unsigned PTEntryOffset = 0;
 272
 273     assert((PTSectionSize % PTEntrySize) == 0 &&
 274            "Pointers section does not contain a whole number of stubs?");
 275
 276     DEBUG(dbgs() << "Populating __pointers, Section ID " << PTSectionID << ", "
 277                  << NumPTEntries << " entries, " << PTEntrySize
 278                  << " bytes each:\n");
 279
 280     for (unsigned i = 0; i < NumPTEntries; ++i) {
 281       unsigned SymbolIndex =
 282           Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 283       symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 284       StringRef IndirectSymbolName;
 285       SI->getName(IndirectSymbolName);
 286       DEBUG(dbgs() << "  " << IndirectSymbolName << ": index " << SymbolIndex
 287                    << ", PT offset: " << PTEntryOffset << "\n");
 288       RelocationEntry RE(PTSectionID, PTEntryOffset,
 289                          MachO::GENERIC_RELOC_VANILLA, 0, false, 2);
 290       addRelocationForSymbol(RE, IndirectSymbolName);
 291       PTEntryOffset += PTEntrySize;
 292     }
 293   }
 294
 295   static section_iterator getSectionByAddress(const MachOObjectFile &Obj,
 296                                               uint64_t Addr) {
 297     section_iterator SI = Obj.section_begin();
 298     section_iterator SE = Obj.section_end();
 299
 300     for (; SI != SE; ++SI) {
 301       uint64_t SAddr, SSize;
 302       SI->getAddress(SAddr);
 303       SI->getSize(SSize);
 304       if ((Addr >= SAddr) && (Addr < SAddr + SSize))
 305         return SI;
 306     }
 307
 308     return SE;
 309   }
 310 };
 311 }
 312
 313 #undef DEBUG_TYPE
 314
 315 #endif // LLVM_RUNTIMEDYLDMACHOI386_H