RuntimeDyldMachOI386.h revision 288943 
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
17namespace llvm {
18
19class RuntimeDyldMachOI386
20    : public RuntimeDyldMachOCRTPBase<RuntimeDyldMachOI386> {
21public:
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 processI386ScatteredVANILLA(SectionID, RelI, Obj,
51                                           ObjSectionToID);
52      llvm_unreachable("Unhandled scattered relocation.");
53    }
54
55    RelocationEntry RE(getRelocationEntry(SectionID, Obj, RelI));
56    RE.Addend = memcpyAddend(RE);
57    RelocationValueRef Value(
58        getRelocationValueRef(Obj, RelI, RE, ObjSectionToID));
59
60    // Addends for external, PC-rel relocations on i386 point back to the zero
61    // offset. Calculate the final offset from the relocation target instead.
62    // This allows us to use the same logic for both external and internal
63    // relocations in resolveI386RelocationRef.
64    // bool IsExtern = Obj.getPlainRelocationExternal(RelInfo);
65    // if (IsExtern && RE.IsPCRel) {
66    //   uint64_t RelocAddr = 0;
67    //   RelI->getAddress(RelocAddr);
68    //   Value.Addend += RelocAddr + 4;
69    // }
70    if (RE.IsPCRel)
71      makeValueAddendPCRel(Value, RelI, 1 << RE.Size);
72
73    RE.Addend = Value.Offset;
74
75    if (Value.SymbolName)
76      addRelocationForSymbol(RE, Value.SymbolName);
77    else
78      addRelocationForSection(RE, Value.SectionID);
79
80    return ++RelI;
81  }
82
83  void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override {
84    DEBUG(dumpRelocationToResolve(RE, Value));
85
86    const SectionEntry &Section = Sections[RE.SectionID];
87    uint8_t *LocalAddress = Section.Address + RE.Offset;
88
89    if (RE.IsPCRel) {
90      uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
91      Value -= FinalAddress + 4; // see MachOX86_64::resolveRelocation.
92    }
93
94    switch (RE.RelType) {
95    default:
96      llvm_unreachable("Invalid relocation type!");
97    case MachO::GENERIC_RELOC_VANILLA:
98      writeBytesUnaligned(Value + RE.Addend, LocalAddress, 1 << RE.Size);
99      break;
100    case MachO::GENERIC_RELOC_SECTDIFF:
101    case MachO::GENERIC_RELOC_LOCAL_SECTDIFF: {
102      uint64_t SectionABase = Sections[RE.Sections.SectionA].LoadAddress;
103      uint64_t SectionBBase = Sections[RE.Sections.SectionB].LoadAddress;
104      assert((Value == SectionABase || Value == SectionBBase) &&
105             "Unexpected SECTDIFF relocation value.");
106      Value = SectionABase - SectionBBase + RE.Addend;
107      writeBytesUnaligned(Value, LocalAddress, 1 << RE.Size);
108      break;
109    }
110    case MachO::GENERIC_RELOC_PB_LA_PTR:
111      Error("Relocation type not implemented yet!");
112    }
113  }
114
115  void finalizeSection(const ObjectFile &Obj, unsigned SectionID,
116                       const SectionRef &Section) {
117    StringRef Name;
118    Section.getName(Name);
119
120    if (Name == "__jump_table")
121      populateJumpTable(cast<MachOObjectFile>(Obj), Section, SectionID);
122    else if (Name == "__pointers")
123      populateIndirectSymbolPointersSection(cast<MachOObjectFile>(Obj),
124                                            Section, SectionID);
125  }
126
127private:
128  relocation_iterator
129  processSECTDIFFRelocation(unsigned SectionID, relocation_iterator RelI,
130                            const ObjectFile &BaseObjT,
131                            ObjSectionToIDMap &ObjSectionToID) {
132    const MachOObjectFile &Obj =
133        static_cast<const MachOObjectFile&>(BaseObjT);
134    MachO::any_relocation_info RE =
135        Obj.getRelocation(RelI->getRawDataRefImpl());
136
137    SectionEntry &Section = Sections[SectionID];
138    uint32_t RelocType = Obj.getAnyRelocationType(RE);
139    bool IsPCRel = Obj.getAnyRelocationPCRel(RE);
140    unsigned Size = Obj.getAnyRelocationLength(RE);
141    uint64_t Offset = RelI->getOffset();
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    // Compute the addend 'C' from the original expression 'A - B + C'.
170    Addend -= AddrA - AddrB;
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, Addend, SectionAID,
178                      SectionAOffset, SectionBID, SectionBOffset,
179                      IsPCRel, Size);
180
181    addRelocationForSection(R, SectionAID);
182
183    return ++RelI;
184  }
185
186  relocation_iterator processI386ScatteredVANILLA(
187      unsigned SectionID, relocation_iterator RelI,
188      const ObjectFile &BaseObjT,
189      RuntimeDyldMachO::ObjSectionToIDMap &ObjSectionToID) {
190    const MachOObjectFile &Obj =
191        static_cast<const MachOObjectFile&>(BaseObjT);
192    MachO::any_relocation_info RE =
193        Obj.getRelocation(RelI->getRawDataRefImpl());
194
195    SectionEntry &Section = Sections[SectionID];
196    uint32_t RelocType = Obj.getAnyRelocationType(RE);
197    bool IsPCRel = Obj.getAnyRelocationPCRel(RE);
198    unsigned Size = Obj.getAnyRelocationLength(RE);
199    uint64_t Offset = RelI->getOffset();
200    uint8_t *LocalAddress = Section.Address + Offset;
201    unsigned NumBytes = 1 << Size;
202    int64_t Addend = readBytesUnaligned(LocalAddress, NumBytes);
203
204    unsigned SymbolBaseAddr = Obj.getScatteredRelocationValue(RE);
205    section_iterator TargetSI = getSectionByAddress(Obj, SymbolBaseAddr);
206    assert(TargetSI != Obj.section_end() && "Can't find section for symbol");
207    uint64_t SectionBaseAddr = TargetSI->getAddress();
208    SectionRef TargetSection = *TargetSI;
209    bool IsCode = TargetSection.isText();
210    uint32_t TargetSectionID =
211        findOrEmitSection(Obj, TargetSection, IsCode, ObjSectionToID);
212
213    Addend -= SectionBaseAddr;
214    RelocationEntry R(SectionID, Offset, RelocType, Addend, IsPCRel, Size);
215
216    addRelocationForSection(R, TargetSectionID);
217
218    return ++RelI;
219  }
220
221  // Populate stubs in __jump_table section.
222  void populateJumpTable(const MachOObjectFile &Obj, const SectionRef &JTSection,
223                         unsigned JTSectionID) {
224    assert(!Obj.is64Bit() &&
225           "__jump_table section not supported in 64-bit MachO.");
226
227    MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
228    MachO::section Sec32 = Obj.getSection(JTSection.getRawDataRefImpl());
229    uint32_t JTSectionSize = Sec32.size;
230    unsigned FirstIndirectSymbol = Sec32.reserved1;
231    unsigned JTEntrySize = Sec32.reserved2;
232    unsigned NumJTEntries = JTSectionSize / JTEntrySize;
233    uint8_t *JTSectionAddr = getSectionAddress(JTSectionID);
234    unsigned JTEntryOffset = 0;
235
236    assert((JTSectionSize % JTEntrySize) == 0 &&
237           "Jump-table section does not contain a whole number of stubs?");
238
239    for (unsigned i = 0; i < NumJTEntries; ++i) {
240      unsigned SymbolIndex =
241          Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
242      symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
243      ErrorOr<StringRef> IndirectSymbolName = SI->getName();
244      if (std::error_code EC = IndirectSymbolName.getError())
245        report_fatal_error(EC.message());
246      uint8_t *JTEntryAddr = JTSectionAddr + JTEntryOffset;
247      createStubFunction(JTEntryAddr);
248      RelocationEntry RE(JTSectionID, JTEntryOffset + 1,
249                         MachO::GENERIC_RELOC_VANILLA, 0, true, 2);
250      addRelocationForSymbol(RE, *IndirectSymbolName);
251      JTEntryOffset += JTEntrySize;
252    }
253  }
254
255};
256}
257
258#undef DEBUG_TYPE
259
260#endif
261