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                        const ObjectFile &BaseObjT,
  35                        ObjSectionToIDMap &ObjSectionToID,
  36                        const SymbolTableMap &Symbols, StubMap &Stubs) override {
  37     const MachOObjectFile &Obj =
  38         static_cast<const MachOObjectFile &>(BaseObjT);
  39     MachO::any_relocation_info RelInfo =
  40         Obj.getRelocation(RelI->getRawDataRefImpl());
  41     uint32_t RelType = Obj.getAnyRelocationType(RelInfo);
  42
  43     if (Obj.isRelocationScattered(RelInfo)) {
  44       if (RelType == MachO::GENERIC_RELOC_SECTDIFF ||
  45           RelType == MachO::GENERIC_RELOC_LOCAL_SECTDIFF)
  46         return processSECTDIFFRelocation(SectionID, RelI, Obj,
  47                                          ObjSectionToID);
  48       else if (RelType == MachO::GENERIC_RELOC_VANILLA)
  49         return processI386ScatteredVANILLA(SectionID, RelI, Obj,
  50                                            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, Symbols));
  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, Obj, 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;
 141     RelI->getOffset(Offset);
 142     uint8_t *LocalAddress = Section.Address + Offset;
 143     unsigned NumBytes = 1 << Size;
 144     uint64_t Addend = readBytesUnaligned(LocalAddress, NumBytes);
 145
 146     ++RelI;
 147     MachO::any_relocation_info RE2 =
 148         Obj.getRelocation(RelI->getRawDataRefImpl());
 149
 150     uint32_t AddrA = Obj.getScatteredRelocationValue(RE);
 151     section_iterator SAI = getSectionByAddress(Obj, AddrA);
 152     assert(SAI != Obj.section_end() && "Can't find section for address A");
 153     uint64_t SectionABase = SAI->getAddress();
 154     uint64_t SectionAOffset = AddrA - SectionABase;
 155     SectionRef SectionA = *SAI;
 156     bool IsCode = SectionA.isText();
 157     uint32_t SectionAID =
 158         findOrEmitSection(Obj, SectionA, IsCode, ObjSectionToID);
 159
 160     uint32_t AddrB = Obj.getScatteredRelocationValue(RE2);
 161     section_iterator SBI = getSectionByAddress(Obj, AddrB);
 162     assert(SBI != Obj.section_end() && "Can't find section for address B");
 163     uint64_t SectionBBase = SBI->getAddress();
 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,
 189       const ObjectFile &BaseObjT,
 190       RuntimeDyldMachO::ObjSectionToIDMap &ObjSectionToID) {
 191     const MachOObjectFile &Obj =
 192         static_cast<const MachOObjectFile&>(BaseObjT);
 193     MachO::any_relocation_info RE =
 194         Obj.getRelocation(RelI->getRawDataRefImpl());
 195
 196     SectionEntry &Section = Sections[SectionID];
 197     uint32_t RelocType = Obj.getAnyRelocationType(RE);
 198     bool IsPCRel = Obj.getAnyRelocationPCRel(RE);
 199     unsigned Size = Obj.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 = Obj.getScatteredRelocationValue(RE);
 207     section_iterator TargetSI = getSectionByAddress(Obj, SymbolBaseAddr);
 208     assert(TargetSI != Obj.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(const 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