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_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDMACHOI386_H
  11 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_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
  23   typedef uint32_t TargetPtrT;
  24
  25   RuntimeDyldMachOI386(RuntimeDyld::MemoryManager &MM,
  26                        RuntimeDyld::SymbolResolver &Resolver)
  27       : RuntimeDyldMachOCRTPBase(MM, Resolver) {}
  28
  29   unsigned getMaxStubSize() override { return 0; }
  30
  31   unsigned getStubAlignment() override { return 1; }
  32
  33   relocation_iterator
  34   processRelocationRef(unsigned SectionID, relocation_iterator RelI,
  35                        const ObjectFile &BaseObjT,
  36                        ObjSectionToIDMap &ObjSectionToID,
  37                        StubMap &Stubs) override {
  38     const MachOObjectFile &Obj =
  39         static_cast<const MachOObjectFile &>(BaseObjT);
  40     MachO::any_relocation_info RelInfo =
  41         Obj.getRelocation(RelI->getRawDataRefImpl());
  42     uint32_t RelType = Obj.getAnyRelocationType(RelInfo);
  43
  44     if (Obj.isRelocationScattered(RelInfo)) {
  45       if (RelType == MachO::GENERIC_RELOC_SECTDIFF ||
  46           RelType == MachO::GENERIC_RELOC_LOCAL_SECTDIFF)
  47         return processSECTDIFFRelocation(SectionID, RelI, Obj,
  48                                          ObjSectionToID);
  49       else if (RelType == MachO::GENERIC_RELOC_VANILLA)
  50         return processScatteredVANILLA(SectionID, RelI, Obj, ObjSectionToID);
  51       llvm_unreachable("Unhandled scattered relocation.");
  52     }
  53
  54     RelocationEntry RE(getRelocationEntry(SectionID, Obj, RelI));
  55     RE.Addend = memcpyAddend(RE);
  56     RelocationValueRef Value(
  57         getRelocationValueRef(Obj, RelI, RE, ObjSectionToID));
  58
  59     // Addends for external, PC-rel relocations on i386 point back to the zero
  60     // offset. Calculate the final offset from the relocation target instead.
  61     // This allows us to use the same logic for both external and internal
  62     // relocations in resolveI386RelocationRef.
  63     // bool IsExtern = Obj.getPlainRelocationExternal(RelInfo);
  64     // if (IsExtern && RE.IsPCRel) {
  65     //   uint64_t RelocAddr = 0;
  66     //   RelI->getAddress(RelocAddr);
  67     //   Value.Addend += RelocAddr + 4;
  68     // }
  69     if (RE.IsPCRel)
  70       makeValueAddendPCRel(Value, RelI, 1 << RE.Size);
  71
  72     RE.Addend = Value.Offset;
  73
  74     if (Value.SymbolName)
  75       addRelocationForSymbol(RE, Value.SymbolName);
  76     else
  77       addRelocationForSection(RE, Value.SectionID);
  78
  79     return ++RelI;
  80   }
  81
  82   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
  83     DEBUG(dumpRelocationToResolve(RE, Value));
  84
  85     const SectionEntry &Section = Sections[RE.SectionID];
  86     uint8_t *LocalAddress = Section.Address + RE.Offset;
  87
  88     if (RE.IsPCRel) {
  89       uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
  90       Value -= FinalAddress + 4; // see MachOX86_64::resolveRelocation.
  91     }
  92
  93     switch (RE.RelType) {
  94     default:
  95       llvm_unreachable("Invalid relocation type!");
  96     case MachO::GENERIC_RELOC_VANILLA:
  97       writeBytesUnaligned(Value + RE.Addend, LocalAddress, 1 << RE.Size);
  98       break;
  99     case MachO::GENERIC_RELOC_SECTDIFF:
 100     case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
 101       uint64_t SectionABase = Sections[RE.Sections.SectionA].LoadAddress;
 102       uint64_t SectionBBase = Sections[RE.Sections.SectionB].LoadAddress;
 103       assert((Value == SectionABase || Value == SectionBBase) &&
 104              "Unexpected SECTDIFF relocation value.");
 105       Value = SectionABase - SectionBBase + RE.Addend;
 106       writeBytesUnaligned(Value, LocalAddress, 1 << RE.Size);
 107       break;
 108     }
 109     case MachO::GENERIC_RELOC_PB_LA_PTR:
 110       Error("Relocation type not implemented yet!");
 111     }
 112   }
 113
 114   void finalizeSection(const ObjectFile &Obj, unsigned SectionID,
 115                        const SectionRef &Section) {
 116     StringRef Name;
 117     Section.getName(Name);
 118
 119     if (Name == "__jump_table")
 120       populateJumpTable(cast<MachOObjectFile>(Obj), Section, SectionID);
 121     else if (Name == "__pointers")
 122       populateIndirectSymbolPointersSection(cast<MachOObjectFile>(Obj),
 123                                             Section, SectionID);
 124   }
 125
 126 private:
 127   relocation_iterator
 128   processSECTDIFFRelocation(unsigned SectionID, relocation_iterator RelI,
 129                             const ObjectFile &BaseObjT,
 130                             ObjSectionToIDMap &ObjSectionToID) {
 131     const MachOObjectFile &Obj =
 132         static_cast<const MachOObjectFile&>(BaseObjT);
 133     MachO::any_relocation_info RE =
 134         Obj.getRelocation(RelI->getRawDataRefImpl());
 135
 136     SectionEntry &Section = Sections[SectionID];
 137     uint32_t RelocType = Obj.getAnyRelocationType(RE);
 138     bool IsPCRel = Obj.getAnyRelocationPCRel(RE);
 139     unsigned Size = Obj.getAnyRelocationLength(RE);
 140     uint64_t Offset = RelI->getOffset();
 141     uint8_t *LocalAddress = Section.Address + Offset;
 142     unsigned NumBytes = 1 << Size;
 143     uint64_t Addend = readBytesUnaligned(LocalAddress, NumBytes);
 144
 145     ++RelI;
 146     MachO::any_relocation_info RE2 =
 147         Obj.getRelocation(RelI->getRawDataRefImpl());
 148
 149     uint32_t AddrA = Obj.getScatteredRelocationValue(RE);
 150     section_iterator SAI = getSectionByAddress(Obj, AddrA);
 151     assert(SAI != Obj.section_end() && "Can't find section for address A");
 152     uint64_t SectionABase = SAI->getAddress();
 153     uint64_t SectionAOffset = AddrA - SectionABase;
 154     SectionRef SectionA = *SAI;
 155     bool IsCode = SectionA.isText();
 156     uint32_t SectionAID =
 157         findOrEmitSection(Obj, SectionA, IsCode, ObjSectionToID);
 158
 159     uint32_t AddrB = Obj.getScatteredRelocationValue(RE2);
 160     section_iterator SBI = getSectionByAddress(Obj, AddrB);
 161     assert(SBI != Obj.section_end() && "Can't find section for address B");
 162     uint64_t SectionBBase = SBI->getAddress();
 163     uint64_t SectionBOffset = AddrB - SectionBBase;
 164     SectionRef SectionB = *SBI;
 165     uint32_t SectionBID =
 166         findOrEmitSection(Obj, SectionB, IsCode, ObjSectionToID);
 167
 168     // Compute the addend 'C' from the original expression 'A - B + C'.
 169     Addend -= AddrA - AddrB;
 170
 171     DEBUG(dbgs() << "Found SECTDIFF: AddrA: " << AddrA << ", AddrB: " << AddrB
 172                  << ", Addend: " << Addend << ", SectionA ID: " << SectionAID
 173                  << ", SectionAOffset: " << SectionAOffset
 174                  << ", SectionB ID: " << SectionBID
 175                  << ", SectionBOffset: " << SectionBOffset << "\n");
 176     RelocationEntry R(SectionID, Offset, RelocType, Addend, SectionAID,
 177                       SectionAOffset, SectionBID, SectionBOffset,
 178                       IsPCRel, Size);
 179
 180     addRelocationForSection(R, SectionAID);
 181
 182     return ++RelI;
 183   }
 184
 185   // Populate stubs in __jump_table section.
 186   void populateJumpTable(const MachOObjectFile &Obj, const SectionRef &JTSection,
 187                          unsigned JTSectionID) {
 188     assert(!Obj.is64Bit() &&
 189            "__jump_table section not supported in 64-bit MachO.");
 190
 191     MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 192     MachO::section Sec32 = Obj.getSection(JTSection.getRawDataRefImpl());
 193     uint32_t JTSectionSize = Sec32.size;
 194     unsigned FirstIndirectSymbol = Sec32.reserved1;
 195     unsigned JTEntrySize = Sec32.reserved2;
 196     unsigned NumJTEntries = JTSectionSize / JTEntrySize;
 197     uint8_t *JTSectionAddr = getSectionAddress(JTSectionID);
 198     unsigned JTEntryOffset = 0;
 199
 200     assert((JTSectionSize % JTEntrySize) == 0 &&
 201            "Jump-table section does not contain a whole number of stubs?");
 202
 203     for (unsigned i = 0; i < NumJTEntries; ++i) {
 204       unsigned SymbolIndex =
 205           Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 206       symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 207       ErrorOr<StringRef> IndirectSymbolName = SI->getName();
 208       if (std::error_code EC = IndirectSymbolName.getError())
 209         report_fatal_error(EC.message());
 210       uint8_t *JTEntryAddr = JTSectionAddr + JTEntryOffset;
 211       createStubFunction(JTEntryAddr);
 212       RelocationEntry RE(JTSectionID, JTEntryOffset + 1,
 213                          MachO::GENERIC_RELOC_VANILLA, 0, true, 2);
 214       addRelocationForSymbol(RE, *IndirectSymbolName);
 215       JTEntryOffset += JTEntrySize;
 216     }
 217   }
 218
 219 };
 220 }
 221
 222 #undef DEBUG_TYPE
 223
 224 #endif