llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOI386.h

   1 //===---- RuntimeDyldMachOI386.h ---- MachO/I386 specific code. ---*- C++ -*-=//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDMACHOI386_H
  10 #define LLVM_LIB_EXECUTIONENGINE_RUNTIMEDYLD_TARGETS_RUNTIMEDYLDMACHOI386_H
  11
  12 #include "../RuntimeDyldMachO.h"
  13
  14 #define DEBUG_TYPE "dyld"
  15
  16 namespace llvm {
  17
  18 class RuntimeDyldMachOI386
  19     : public RuntimeDyldMachOCRTPBase<RuntimeDyldMachOI386> {
  20 public:
  21
  22   typedef uint32_t TargetPtrT;
  23
  24   RuntimeDyldMachOI386(RuntimeDyld::MemoryManager &MM,
  25                        JITSymbolResolver &Resolver)
  26       : RuntimeDyldMachOCRTPBase(MM, Resolver) {}
  27
  28   unsigned getMaxStubSize() const override { return 0; }
  29
  30   Align getStubAlignment() override { return Align(1); }
  31
  32   Expected<relocation_iterator>
  33   processRelocationRef(unsigned SectionID, relocation_iterator RelI,
  34                        const ObjectFile &BaseObjT,
  35                        ObjSectionToIDMap &ObjSectionToID,
  36                        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 processScatteredVANILLA(SectionID, RelI, Obj, ObjSectionToID);
  50       return make_error<RuntimeDyldError>(("Unhandled I386 scattered relocation "
  51                                            "type: " + Twine(RelType)).str());
  52     }
  53
  54     switch (RelType) {
  55     UNIMPLEMENTED_RELOC(MachO::GENERIC_RELOC_PAIR);
  56     UNIMPLEMENTED_RELOC(MachO::GENERIC_RELOC_PB_LA_PTR);
  57     UNIMPLEMENTED_RELOC(MachO::GENERIC_RELOC_TLV);
  58     default:
  59       if (RelType > MachO::GENERIC_RELOC_TLV)
  60         return make_error<RuntimeDyldError>(("MachO I386 relocation type " +
  61                                              Twine(RelType) +
  62                                              " is out of range").str());
  63       break;
  64     }
  65
  66     RelocationEntry RE(getRelocationEntry(SectionID, Obj, RelI));
  67     RE.Addend = memcpyAddend(RE);
  68     RelocationValueRef Value;
  69     if (auto ValueOrErr = getRelocationValueRef(Obj, RelI, RE, ObjSectionToID))
  70       Value = *ValueOrErr;
  71     else
  72       return ValueOrErr.takeError();
  73
  74     // Addends for external, PC-rel relocations on i386 point back to the zero
  75     // offset. Calculate the final offset from the relocation target instead.
  76     // This allows us to use the same logic for both external and internal
  77     // relocations in resolveI386RelocationRef.
  78     // bool IsExtern = Obj.getPlainRelocationExternal(RelInfo);
  79     // if (IsExtern && RE.IsPCRel) {
  80     //   uint64_t RelocAddr = 0;
  81     //   RelI->getAddress(RelocAddr);
  82     //   Value.Addend += RelocAddr + 4;
  83     // }
  84     if (RE.IsPCRel)
  85       makeValueAddendPCRel(Value, RelI, 1 << RE.Size);
  86
  87     RE.Addend = Value.Offset;
  88
  89     if (Value.SymbolName)
  90       addRelocationForSymbol(RE, Value.SymbolName);
  91     else
  92       addRelocationForSection(RE, Value.SectionID);
  93
  94     return ++RelI;
  95   }
  96
  97   void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
  98     LLVM_DEBUG(dumpRelocationToResolve(RE, Value));
  99
 100     const SectionEntry &Section = Sections[RE.SectionID];
 101     uint8_t *LocalAddress = Section.getAddressWithOffset(RE.Offset);
 102
 103     if (RE.IsPCRel) {
 104       uint64_t FinalAddress = Section.getLoadAddressWithOffset(RE.Offset);
 105       Value -= FinalAddress + 4; // see MachOX86_64::resolveRelocation.
 106     }
 107
 108     switch (RE.RelType) {
 109     case MachO::GENERIC_RELOC_VANILLA:
 110       writeBytesUnaligned(Value + RE.Addend, LocalAddress, 1 << RE.Size);
 111       break;
 112     case MachO::GENERIC_RELOC_SECTDIFF:
 113     case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
 114       uint64_t SectionABase = Sections[RE.Sections.SectionA].getLoadAddress();
 115       uint64_t SectionBBase = Sections[RE.Sections.SectionB].getLoadAddress();
 116       assert((Value == SectionABase || Value == SectionBBase) &&
 117              "Unexpected SECTDIFF relocation value.");
 118       Value = SectionABase - SectionBBase + RE.Addend;
 119       writeBytesUnaligned(Value, LocalAddress, 1 << RE.Size);
 120       break;
 121     }
 122     default:
 123       llvm_unreachable("Invalid relocation type!");
 124     }
 125   }
 126
 127   Error finalizeSection(const ObjectFile &Obj, unsigned SectionID,
 128                        const SectionRef &Section) {
 129     StringRef Name;
 130     if (Expected<StringRef> NameOrErr = Section.getName())
 131       Name = *NameOrErr;
 132     else
 133       consumeError(NameOrErr.takeError());
 134
 135     if (Name == "__jump_table")
 136       return populateJumpTable(cast<MachOObjectFile>(Obj), Section, SectionID);
 137     else if (Name == "__pointers")
 138       return populateIndirectSymbolPointersSection(cast<MachOObjectFile>(Obj),
 139                                                    Section, SectionID);
 140     return Error::success();
 141   }
 142
 143 private:
 144   Expected<relocation_iterator>
 145   processSECTDIFFRelocation(unsigned SectionID, relocation_iterator RelI,
 146                             const ObjectFile &BaseObjT,
 147                             ObjSectionToIDMap &ObjSectionToID) {
 148     const MachOObjectFile &Obj =
 149         static_cast<const MachOObjectFile&>(BaseObjT);
 150     MachO::any_relocation_info RE =
 151         Obj.getRelocation(RelI->getRawDataRefImpl());
 152
 153     SectionEntry &Section = Sections[SectionID];
 154     uint32_t RelocType = Obj.getAnyRelocationType(RE);
 155     bool IsPCRel = Obj.getAnyRelocationPCRel(RE);
 156     unsigned Size = Obj.getAnyRelocationLength(RE);
 157     uint64_t Offset = RelI->getOffset();
 158     uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 159     unsigned NumBytes = 1 << Size;
 160     uint64_t Addend = readBytesUnaligned(LocalAddress, NumBytes);
 161
 162     ++RelI;
 163     MachO::any_relocation_info RE2 =
 164         Obj.getRelocation(RelI->getRawDataRefImpl());
 165
 166     uint32_t AddrA = Obj.getScatteredRelocationValue(RE);
 167     section_iterator SAI = getSectionByAddress(Obj, AddrA);
 168     assert(SAI != Obj.section_end() && "Can't find section for address A");
 169     uint64_t SectionABase = SAI->getAddress();
 170     uint64_t SectionAOffset = AddrA - SectionABase;
 171     SectionRef SectionA = *SAI;
 172     bool IsCode = SectionA.isText();
 173     uint32_t SectionAID = ~0U;
 174     if (auto SectionAIDOrErr =
 175         findOrEmitSection(Obj, SectionA, IsCode, ObjSectionToID))
 176       SectionAID = *SectionAIDOrErr;
 177     else
 178       return SectionAIDOrErr.takeError();
 179
 180     uint32_t AddrB = Obj.getScatteredRelocationValue(RE2);
 181     section_iterator SBI = getSectionByAddress(Obj, AddrB);
 182     assert(SBI != Obj.section_end() && "Can't find section for address B");
 183     uint64_t SectionBBase = SBI->getAddress();
 184     uint64_t SectionBOffset = AddrB - SectionBBase;
 185     SectionRef SectionB = *SBI;
 186     uint32_t SectionBID = ~0U;
 187     if (auto SectionBIDOrErr =
 188         findOrEmitSection(Obj, SectionB, IsCode, ObjSectionToID))
 189       SectionBID = *SectionBIDOrErr;
 190     else
 191       return SectionBIDOrErr.takeError();
 192
 193     // Compute the addend 'C' from the original expression 'A - B + C'.
 194     Addend -= AddrA - AddrB;
 195
 196     LLVM_DEBUG(dbgs() << "Found SECTDIFF: AddrA: " << AddrA
 197                       << ", AddrB: " << AddrB << ", Addend: " << Addend
 198                       << ", SectionA ID: " << SectionAID << ", SectionAOffset: "
 199                       << SectionAOffset << ", SectionB ID: " << SectionBID
 200                       << ", SectionBOffset: " << SectionBOffset << "\n");
 201     RelocationEntry R(SectionID, Offset, RelocType, Addend, SectionAID,
 202                       SectionAOffset, SectionBID, SectionBOffset,
 203                       IsPCRel, Size);
 204
 205     addRelocationForSection(R, SectionAID);
 206
 207     return ++RelI;
 208   }
 209
 210   // Populate stubs in __jump_table section.
 211   Error populateJumpTable(const MachOObjectFile &Obj,
 212                           const SectionRef &JTSection,
 213                          unsigned JTSectionID) {
 214     MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
 215     MachO::section Sec32 = Obj.getSection(JTSection.getRawDataRefImpl());
 216     uint32_t JTSectionSize = Sec32.size;
 217     unsigned FirstIndirectSymbol = Sec32.reserved1;
 218     unsigned JTEntrySize = Sec32.reserved2;
 219     unsigned NumJTEntries = JTSectionSize / JTEntrySize;
 220     uint8_t *JTSectionAddr = getSectionAddress(JTSectionID);
 221     unsigned JTEntryOffset = 0;
 222
 223     if (JTSectionSize % JTEntrySize != 0)
 224       return make_error<RuntimeDyldError>("Jump-table section does not contain "
 225                                           "a whole number of stubs?");
 226
 227     for (unsigned i = 0; i < NumJTEntries; ++i) {
 228       unsigned SymbolIndex =
 229           Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
 230       symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
 231       Expected<StringRef> IndirectSymbolName = SI->getName();
 232       if (!IndirectSymbolName)
 233         return IndirectSymbolName.takeError();
 234       uint8_t *JTEntryAddr = JTSectionAddr + JTEntryOffset;
 235       createStubFunction(JTEntryAddr);
 236       RelocationEntry RE(JTSectionID, JTEntryOffset + 1,
 237                          MachO::GENERIC_RELOC_VANILLA, 0, true, 2);
 238       addRelocationForSymbol(RE, *IndirectSymbolName);
 239       JTEntryOffset += JTEntrySize;
 240     }
 241
 242     return Error::success();
 243   }
 244
 245 };
 246 }
 247
 248 #undef DEBUG_TYPE
 249
 250 #endif