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(RTDyldMemoryManager *MM)
  26       : RuntimeDyldMachOCRTPBase(MM) {}
  27
  28   unsigned getMaxStubSize() override { return 0; }
  29
  30   unsigned getStubAlignment() override { return 1; }
  31
  32   relocation_iterator
  33   processRelocationRef(unsigned SectionID, relocation_iterator RelI,
  34                        ObjectImage &ObjImg, ObjSectionToIDMap &ObjSectionToID,
  35                        const SymbolTableMap &Symbols, StubMap &Stubs) override {
  36     const MachOObjectFile &Obj =
  37         static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
  38     MachO::any_relocation_info RelInfo =
  39         Obj.getRelocation(RelI->getRawDataRefImpl());
  40     uint32_t RelType = Obj.getAnyRelocationType(RelInfo);
  41
  42     if (Obj.isRelocationScattered(RelInfo)) {
  43       if (RelType == MachO::GENERIC_RELOC_SECTDIFF ||
  44           RelType == MachO::GENERIC_RELOC_LOCAL_SECTDIFF)
  45         return processSECTDIFFRelocation(SectionID, RelI, ObjImg,
  46                                          ObjSectionToID);
  47       else if (RelType == MachO::GENERIC_RELOC_VANILLA)
  48         return processI386ScatteredVANILLA(SectionID, RelI, ObjImg,
  49                                            ObjSectionToID);
  50       llvm_unreachable("Unhandled scattered relocation.");
  51     }
  52
  53     RelocationEntry RE(getRelocationEntry(SectionID, ObjImg, RelI));
  54     RE.Addend = memcpyAddend(RE);
  55     RelocationValueRef Value(
  56         getRelocationValueRef(ObjImg, RelI, RE, ObjSectionToID, Symbols));
  57
  58     // Addends for external, PC-rel relocations on i386 point back to the zero
  59     // offset. Calculate the final offset from the relocation target instead.
  60     // This allows us to use the same logic for both external and internal
  61     // relocations in resolveI386RelocationRef.
  62     // bool IsExtern = Obj.getPlainRelocationExternal(RelInfo);
  63     // if (IsExtern && RE.IsPCRel) {
  64     //   uint64_t RelocAddr = 0;
  65     //   RelI->getAddress(RelocAddr);
  66     //   Value.Addend += RelocAddr + 4;
  67     // }
  68     if (RE.IsPCRel)
  69       makeValueAddendPCRel(Value, ObjImg, RelI, 1 << RE.Size);
  70
  71     RE.Addend = Value.Offset;
  72
  73     if (Value.SymbolName)
  74       addRelocationForSymbol(RE, Value.SymbolName);
  75     else
  76       addRelocationForSection(RE, Value.SectionID);
  77
  78     return ++RelI;
  79   }
  80
  81   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
  82     DEBUG(dumpRelocationToResolve(RE, Value));
  83
  84     const SectionEntry &Section = Sections[RE.SectionID];
  85     uint8_t *LocalAddress = Section.Address + RE.Offset;
  86
  87     if (RE.IsPCRel) {
  88       uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
  89       Value -= FinalAddress + 4; // see MachOX86_64::resolveRelocation.
  90     }
  91
  92     switch (RE.RelType) {
  93     default:
  94       llvm_unreachable("Invalid relocation type!");
  95     case MachO::GENERIC_RELOC_VANILLA:
  96       writeBytesUnaligned(Value + RE.Addend, LocalAddress, 1 << RE.Size);
  97       break;
  98     case MachO::GENERIC_RELOC_SECTDIFF:
  99     case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
 100       uint64_t SectionABase = Sections[RE.Sections.SectionA].LoadAddress;
 101       uint64_t SectionBBase = Sections[RE.Sections.SectionB].LoadAddress;
 102       assert((Value == SectionABase || Value == SectionBBase) &&
 103              "Unexpected SECTDIFF relocation value.");
 104       Value = SectionABase - SectionBBase + RE.Addend;
 105       writeBytesUnaligned(Value, LocalAddress, 1 << RE.Size);
 106       break;
 107     }
 108     case MachO::GENERIC_RELOC_PB_LA_PTR:
 109       Error("Relocation type not implemented yet!");
 110     }
 111   }
 112
 113   void finalizeSection(ObjectImage &ObjImg, unsigned SectionID,
 114                        const SectionRef &Section) {
 115     StringRef Name;
 116     Section.getName(Name);
 117
 118     if (Name == "__jump_table")
 119       populateJumpTable(cast<MachOObjectFile>(*ObjImg.getObjectFile()), Section,
 120                         SectionID);
 121     else if (Name == "__pointers")
 122       populateIndirectSymbolPointersSection(
 123                                  cast<MachOObjectFile>(*ObjImg.getObjectFile()),
 124                                  Section, SectionID);
 125   }
 126
 127 private:
 128   relocation_iterator
 129   processSECTDIFFRelocation(unsigned SectionID, relocation_iterator RelI,
 130                             ObjectImage &Obj,
 131                             ObjSectionToIDMap &ObjSectionToID) {
 132     const MachOObjectFile *MachO =
 133         static_cast<const MachOObjectFile *>(Obj.getObjectFile());
 134     MachO::any_relocation_info RE =
 135         MachO->getRelocation(RelI->getRawDataRefImpl());
 136
 137     SectionEntry &Section = Sections[SectionID];
 138     uint32_t RelocType = MachO->getAnyRelocationType(RE);
 139     bool IsPCRel = MachO->getAnyRelocationPCRel(RE);
 140     unsigned Size = MachO->getAnyRelocationLength(RE);
 141     uint64_t Offset;
 142     RelI->getOffset(Offset);
 143     uint8_t *LocalAddress = Section.Address + Offset;
 144     unsigned NumBytes = 1 << Size;
 145     uint64_t Addend = readBytesUnaligned(LocalAddress, NumBytes);
 146
 147     ++RelI;
 148     MachO::any_relocation_info RE2 =
 149         MachO->getRelocation(RelI->getRawDataRefImpl());
 150
 151     uint32_t AddrA = MachO->getScatteredRelocationValue(RE);
 152     section_iterator SAI = getSectionByAddress(*MachO, AddrA);
 153     assert(SAI != MachO->section_end() && "Can't find section for address A");
 154     uint64_t SectionABase = SAI->getAddress();
 155     uint64_t SectionAOffset = AddrA - SectionABase;
 156     SectionRef SectionA = *SAI;
 157     bool IsCode = SectionA.isText();
 158     uint32_t SectionAID =
 159         findOrEmitSection(Obj, SectionA, IsCode, ObjSectionToID);
 160
 161     uint32_t AddrB = MachO->getScatteredRelocationValue(RE2);
 162     section_iterator SBI = getSectionByAddress(*MachO, AddrB);
 163     assert(SBI != MachO->section_end() && "Can't find section for address B");
 164     uint64_t SectionBBase = SBI->getAddress();
 165     uint64_t SectionBOffset = AddrB - SectionBBase;
 166     SectionRef SectionB = *SBI;
 167     uint32_t SectionBID =
 168         findOrEmitSection(Obj, SectionB, IsCode, ObjSectionToID);
 169
 170     if (Addend != AddrA - AddrB)
 171       Error("Unexpected SECTDIFF relocation addend.");
 172
 173     DEBUG(dbgs() << "Found SECTDIFF: AddrA: " << AddrA << ", AddrB: " << AddrB
 174                  << ", Addend: " << Addend << ", SectionA ID: " << SectionAID
 175                  << ", SectionAOffset: " << SectionAOffset
 176                  << ", SectionB ID: " << SectionBID
 177                  << ", SectionBOffset: " << SectionBOffset << "\n");
 178     RelocationEntry R(SectionID, Offset, RelocType, 0, SectionAID,
 179                       SectionAOffset, SectionBID, SectionBOffset, IsPCRel,
 180                       Size);
 181
 182     addRelocationForSection(R, SectionAID);
 183     addRelocationForSection(R, SectionBID);
 184
 185     return ++RelI;
 186   }
 187
 188   relocation_iterator processI386ScatteredVANILLA(
 189       unsigned SectionID, relocation_iterator RelI, ObjectImage &Obj,
 190       RuntimeDyldMachO::ObjSectionToIDMap &ObjSectionToID) {
 191     const MachOObjectFile *MachO =
 192         static_cast<const MachOObjectFile *>(Obj.getObjectFile());
 193     MachO::any_relocation_info RE =
 194         MachO->getRelocation(RelI->getRawDataRefImpl());
 195
 196     SectionEntry &Section = Sections[SectionID];
 197     uint32_t RelocType = MachO->getAnyRelocationType(RE);
 198     bool IsPCRel = MachO->getAnyRelocationPCRel(RE);
 199     unsigned Size = MachO->getAnyRelocationLength(RE);
 200     uint64_t Offset;
 201     RelI->getOffset(Offset);
 202     uint8_t *LocalAddress = Section.Address + Offset;
 203     unsigned NumBytes = 1 << Size;
 204     int64_t Addend = readBytesUnaligned(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 = TargetSI->getAddress();
 210     SectionRef TargetSection = *TargetSI;
 211     bool IsCode = TargetSection.isText();
 212     uint32_t TargetSectionID =
 213         findOrEmitSection(Obj, TargetSection, IsCode, ObjSectionToID);
 214
 215     Addend -= SectionBaseAddr;
 216     RelocationEntry R(SectionID, Offset, RelocType, Addend, IsPCRel, Size);
 217
 218     addRelocationForSection(R, TargetSectionID);
 219
 220     return ++RelI;
 221   }
 222
 223   // Populate stubs in __jump_table section.
 224   void populateJumpTable(MachOObjectFile &Obj, const SectionRef &JTSection,
 225                          unsigned JTSectionID) {
 226     assert(!Obj.is64Bit() &&
 227            "__jump_table section not supported in 64-bit MachO.");
 228
 229     MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 230     MachO::section Sec32 = Obj.getSection(JTSection.getRawDataRefImpl());
 231     uint32_t JTSectionSize = Sec32.size;
 232     unsigned FirstIndirectSymbol = Sec32.reserved1;
 233     unsigned JTEntrySize = Sec32.reserved2;
 234     unsigned NumJTEntries = JTSectionSize / JTEntrySize;
 235     uint8_t *JTSectionAddr = getSectionAddress(JTSectionID);
 236     unsigned JTEntryOffset = 0;
 237
 238     assert((JTSectionSize % JTEntrySize) == 0 &&
 239            "Jump-table section does not contain a whole number of stubs?");
 240
 241     for (unsigned i = 0; i < NumJTEntries; ++i) {
 242       unsigned SymbolIndex =
 243           Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 244       symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 245       StringRef IndirectSymbolName;
 246       SI->getName(IndirectSymbolName);
 247       uint8_t *JTEntryAddr = JTSectionAddr + JTEntryOffset;
 248       createStubFunction(JTEntryAddr);
 249       RelocationEntry RE(JTSectionID, JTEntryOffset + 1,
 250                          MachO::GENERIC_RELOC_VANILLA, 0, true, 2);
 251       addRelocationForSymbol(RE, IndirectSymbolName);
 252       JTEntryOffset += JTEntrySize;
 253     }
 254   }
 255
 256 };
 257 }
 258
 259 #undef DEBUG_TYPE
 260
 261 #endif