RuntimeDyldMachO.cpp revision 360784 
1//===-- RuntimeDyldMachO.cpp - Run-time dynamic linker for MC-JIT -*- 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// Implementation of the MC-JIT runtime dynamic linker.
10//
11//===----------------------------------------------------------------------===//
12
13#include "RuntimeDyldMachO.h"
14#include "Targets/RuntimeDyldMachOAArch64.h"
15#include "Targets/RuntimeDyldMachOARM.h"
16#include "Targets/RuntimeDyldMachOI386.h"
17#include "Targets/RuntimeDyldMachOX86_64.h"
18#include "llvm/ADT/STLExtras.h"
19#include "llvm/ADT/StringRef.h"
20
21using namespace llvm;
22using namespace llvm::object;
23
24#define DEBUG_TYPE "dyld"
25
26namespace {
27
28class LoadedMachOObjectInfo final
29    : public LoadedObjectInfoHelper<LoadedMachOObjectInfo,
30                                    RuntimeDyld::LoadedObjectInfo> {
31public:
32  LoadedMachOObjectInfo(RuntimeDyldImpl &RTDyld,
33                        ObjSectionToIDMap ObjSecToIDMap)
34      : LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {}
35
36  OwningBinary<ObjectFile>
37  getObjectForDebug(const ObjectFile &Obj) const override {
38    return OwningBinary<ObjectFile>();
39  }
40};
41
42}
43
44namespace llvm {
45
46int64_t RuntimeDyldMachO::memcpyAddend(const RelocationEntry &RE) const {
47  unsigned NumBytes = 1 << RE.Size;
48  uint8_t *Src = Sections[RE.SectionID].getAddress() + RE.Offset;
49
50  return static_cast<int64_t>(readBytesUnaligned(Src, NumBytes));
51}
52
53Expected<relocation_iterator>
54RuntimeDyldMachO::processScatteredVANILLA(
55                          unsigned SectionID, relocation_iterator RelI,
56                          const ObjectFile &BaseObjT,
57                          RuntimeDyldMachO::ObjSectionToIDMap &ObjSectionToID,
58                          bool TargetIsLocalThumbFunc) {
59  const MachOObjectFile &Obj =
60    static_cast<const MachOObjectFile&>(BaseObjT);
61  MachO::any_relocation_info RE =
62    Obj.getRelocation(RelI->getRawDataRefImpl());
63
64  SectionEntry &Section = Sections[SectionID];
65  uint32_t RelocType = Obj.getAnyRelocationType(RE);
66  bool IsPCRel = Obj.getAnyRelocationPCRel(RE);
67  unsigned Size = Obj.getAnyRelocationLength(RE);
68  uint64_t Offset = RelI->getOffset();
69  uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
70  unsigned NumBytes = 1 << Size;
71  int64_t Addend = readBytesUnaligned(LocalAddress, NumBytes);
72
73  unsigned SymbolBaseAddr = Obj.getScatteredRelocationValue(RE);
74  section_iterator TargetSI = getSectionByAddress(Obj, SymbolBaseAddr);
75  assert(TargetSI != Obj.section_end() && "Can't find section for symbol");
76  uint64_t SectionBaseAddr = TargetSI->getAddress();
77  SectionRef TargetSection = *TargetSI;
78  bool IsCode = TargetSection.isText();
79  uint32_t TargetSectionID = ~0U;
80  if (auto TargetSectionIDOrErr =
81        findOrEmitSection(Obj, TargetSection, IsCode, ObjSectionToID))
82    TargetSectionID = *TargetSectionIDOrErr;
83  else
84    return TargetSectionIDOrErr.takeError();
85
86  Addend -= SectionBaseAddr;
87  RelocationEntry R(SectionID, Offset, RelocType, Addend, IsPCRel, Size);
88  R.IsTargetThumbFunc = TargetIsLocalThumbFunc;
89
90  addRelocationForSection(R, TargetSectionID);
91
92  return ++RelI;
93}
94
95
96Expected<RelocationValueRef>
97RuntimeDyldMachO::getRelocationValueRef(
98    const ObjectFile &BaseTObj, const relocation_iterator &RI,
99    const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID) {
100
101  const MachOObjectFile &Obj =
102      static_cast<const MachOObjectFile &>(BaseTObj);
103  MachO::any_relocation_info RelInfo =
104      Obj.getRelocation(RI->getRawDataRefImpl());
105  RelocationValueRef Value;
106
107  bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
108  if (IsExternal) {
109    symbol_iterator Symbol = RI->getSymbol();
110    StringRef TargetName;
111    if (auto TargetNameOrErr = Symbol->getName())
112      TargetName = *TargetNameOrErr;
113    else
114      return TargetNameOrErr.takeError();
115    RTDyldSymbolTable::const_iterator SI =
116      GlobalSymbolTable.find(TargetName.data());
117    if (SI != GlobalSymbolTable.end()) {
118      const auto &SymInfo = SI->second;
119      Value.SectionID = SymInfo.getSectionID();
120      Value.Offset = SymInfo.getOffset() + RE.Addend;
121    } else {
122      Value.SymbolName = TargetName.data();
123      Value.Offset = RE.Addend;
124    }
125  } else {
126    SectionRef Sec = Obj.getAnyRelocationSection(RelInfo);
127    bool IsCode = Sec.isText();
128    if (auto SectionIDOrErr = findOrEmitSection(Obj, Sec, IsCode,
129                                                ObjSectionToID))
130      Value.SectionID = *SectionIDOrErr;
131    else
132      return SectionIDOrErr.takeError();
133    uint64_t Addr = Sec.getAddress();
134    Value.Offset = RE.Addend - Addr;
135  }
136
137  return Value;
138}
139
140void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
141                                            const relocation_iterator &RI,
142                                            unsigned OffsetToNextPC) {
143  auto &O = *cast<MachOObjectFile>(RI->getObject());
144  section_iterator SecI = O.getRelocationRelocatedSection(RI);
145  Value.Offset += RI->getOffset() + OffsetToNextPC + SecI->getAddress();
146}
147
148void RuntimeDyldMachO::dumpRelocationToResolve(const RelocationEntry &RE,
149                                               uint64_t Value) const {
150  const SectionEntry &Section = Sections[RE.SectionID];
151  uint8_t *LocalAddress = Section.getAddress() + RE.Offset;
152  uint64_t FinalAddress = Section.getLoadAddress() + RE.Offset;
153
154  dbgs() << "resolveRelocation Section: " << RE.SectionID
155         << " LocalAddress: " << format("%p", LocalAddress)
156         << " FinalAddress: " << format("0x%016" PRIx64, FinalAddress)
157         << " Value: " << format("0x%016" PRIx64, Value) << " Addend: " << RE.Addend
158         << " isPCRel: " << RE.IsPCRel << " MachoType: " << RE.RelType
159         << " Size: " << (1 << RE.Size) << "\n";
160}
161
162section_iterator
163RuntimeDyldMachO::getSectionByAddress(const MachOObjectFile &Obj,
164                                      uint64_t Addr) {
165  section_iterator SI = Obj.section_begin();
166  section_iterator SE = Obj.section_end();
167
168  for (; SI != SE; ++SI) {
169    uint64_t SAddr = SI->getAddress();
170    uint64_t SSize = SI->getSize();
171    if ((Addr >= SAddr) && (Addr < SAddr + SSize))
172      return SI;
173  }
174
175  return SE;
176}
177
178
179// Populate __pointers section.
180Error RuntimeDyldMachO::populateIndirectSymbolPointersSection(
181                                                    const MachOObjectFile &Obj,
182                                                    const SectionRef &PTSection,
183                                                    unsigned PTSectionID) {
184  assert(!Obj.is64Bit() &&
185         "Pointer table section not supported in 64-bit MachO.");
186
187  MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
188  MachO::section Sec32 = Obj.getSection(PTSection.getRawDataRefImpl());
189  uint32_t PTSectionSize = Sec32.size;
190  unsigned FirstIndirectSymbol = Sec32.reserved1;
191  const unsigned PTEntrySize = 4;
192  unsigned NumPTEntries = PTSectionSize / PTEntrySize;
193  unsigned PTEntryOffset = 0;
194
195  assert((PTSectionSize % PTEntrySize) == 0 &&
196         "Pointers section does not contain a whole number of stubs?");
197
198  LLVM_DEBUG(dbgs() << "Populating pointer table section "
199                    << Sections[PTSectionID].getName() << ", Section ID "
200                    << PTSectionID << ", " << NumPTEntries << " entries, "
201                    << PTEntrySize << " bytes each:\n");
202
203  for (unsigned i = 0; i < NumPTEntries; ++i) {
204    unsigned SymbolIndex =
205      Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
206    symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
207    StringRef IndirectSymbolName;
208    if (auto IndirectSymbolNameOrErr = SI->getName())
209      IndirectSymbolName = *IndirectSymbolNameOrErr;
210    else
211      return IndirectSymbolNameOrErr.takeError();
212    LLVM_DEBUG(dbgs() << "  " << IndirectSymbolName << ": index " << SymbolIndex
213                      << ", PT offset: " << PTEntryOffset << "\n");
214    RelocationEntry RE(PTSectionID, PTEntryOffset,
215                       MachO::GENERIC_RELOC_VANILLA, 0, false, 2);
216    addRelocationForSymbol(RE, IndirectSymbolName);
217    PTEntryOffset += PTEntrySize;
218  }
219  return Error::success();
220}
221
222bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile &Obj) const {
223  return Obj.isMachO();
224}
225
226template <typename Impl>
227Error
228RuntimeDyldMachOCRTPBase<Impl>::finalizeLoad(const ObjectFile &Obj,
229                                             ObjSectionToIDMap &SectionMap) {
230  unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
231  unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
232  unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
233
234  for (const auto &Section : Obj.sections()) {
235    StringRef Name;
236    if (Expected<StringRef> NameOrErr = Section.getName())
237      Name = *NameOrErr;
238    else
239      consumeError(NameOrErr.takeError());
240
241    // Force emission of the __text, __eh_frame, and __gcc_except_tab sections
242    // if they're present. Otherwise call down to the impl to handle other
243    // sections that have already been emitted.
244    if (Name == "__text") {
245      if (auto TextSIDOrErr = findOrEmitSection(Obj, Section, true, SectionMap))
246        TextSID = *TextSIDOrErr;
247      else
248        return TextSIDOrErr.takeError();
249    } else if (Name == "__eh_frame") {
250      if (auto EHFrameSIDOrErr = findOrEmitSection(Obj, Section, false,
251                                                   SectionMap))
252        EHFrameSID = *EHFrameSIDOrErr;
253      else
254        return EHFrameSIDOrErr.takeError();
255    } else if (Name == "__gcc_except_tab") {
256      if (auto ExceptTabSIDOrErr = findOrEmitSection(Obj, Section, true,
257                                                     SectionMap))
258        ExceptTabSID = *ExceptTabSIDOrErr;
259      else
260        return ExceptTabSIDOrErr.takeError();
261    } else {
262      auto I = SectionMap.find(Section);
263      if (I != SectionMap.end())
264        if (auto Err = impl().finalizeSection(Obj, I->second, Section))
265          return Err;
266    }
267  }
268  UnregisteredEHFrameSections.push_back(
269    EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
270
271  return Error::success();
272}
273
274template <typename Impl>
275unsigned char *RuntimeDyldMachOCRTPBase<Impl>::processFDE(uint8_t *P,
276                                                          int64_t DeltaForText,
277                                                          int64_t DeltaForEH) {
278  typedef typename Impl::TargetPtrT TargetPtrT;
279
280  LLVM_DEBUG(dbgs() << "Processing FDE: Delta for text: " << DeltaForText
281                    << ", Delta for EH: " << DeltaForEH << "\n");
282  uint32_t Length = readBytesUnaligned(P, 4);
283  P += 4;
284  uint8_t *Ret = P + Length;
285  uint32_t Offset = readBytesUnaligned(P, 4);
286  if (Offset == 0) // is a CIE
287    return Ret;
288
289  P += 4;
290  TargetPtrT FDELocation = readBytesUnaligned(P, sizeof(TargetPtrT));
291  TargetPtrT NewLocation = FDELocation - DeltaForText;
292  writeBytesUnaligned(NewLocation, P, sizeof(TargetPtrT));
293
294  P += sizeof(TargetPtrT);
295
296  // Skip the FDE address range
297  P += sizeof(TargetPtrT);
298
299  uint8_t Augmentationsize = *P;
300  P += 1;
301  if (Augmentationsize != 0) {
302    TargetPtrT LSDA = readBytesUnaligned(P, sizeof(TargetPtrT));
303    TargetPtrT NewLSDA = LSDA - DeltaForEH;
304    writeBytesUnaligned(NewLSDA, P, sizeof(TargetPtrT));
305  }
306
307  return Ret;
308}
309
310static int64_t computeDelta(SectionEntry *A, SectionEntry *B) {
311  int64_t ObjDistance = static_cast<int64_t>(A->getObjAddress()) -
312                        static_cast<int64_t>(B->getObjAddress());
313  int64_t MemDistance = A->getLoadAddress() - B->getLoadAddress();
314  return ObjDistance - MemDistance;
315}
316
317template <typename Impl>
318void RuntimeDyldMachOCRTPBase<Impl>::registerEHFrames() {
319
320  for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
321    EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
322    if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
323        SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
324      continue;
325    SectionEntry *Text = &Sections[SectionInfo.TextSID];
326    SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
327    SectionEntry *ExceptTab = nullptr;
328    if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
329      ExceptTab = &Sections[SectionInfo.ExceptTabSID];
330
331    int64_t DeltaForText = computeDelta(Text, EHFrame);
332    int64_t DeltaForEH = 0;
333    if (ExceptTab)
334      DeltaForEH = computeDelta(ExceptTab, EHFrame);
335
336    uint8_t *P = EHFrame->getAddress();
337    uint8_t *End = P + EHFrame->getSize();
338    while (P != End) {
339      P = processFDE(P, DeltaForText, DeltaForEH);
340    }
341
342    MemMgr.registerEHFrames(EHFrame->getAddress(), EHFrame->getLoadAddress(),
343                            EHFrame->getSize());
344  }
345  UnregisteredEHFrameSections.clear();
346}
347
348std::unique_ptr<RuntimeDyldMachO>
349RuntimeDyldMachO::create(Triple::ArchType Arch,
350                         RuntimeDyld::MemoryManager &MemMgr,
351                         JITSymbolResolver &Resolver) {
352  switch (Arch) {
353  default:
354    llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
355    break;
356  case Triple::arm:
357    return std::make_unique<RuntimeDyldMachOARM>(MemMgr, Resolver);
358  case Triple::aarch64:
359    return std::make_unique<RuntimeDyldMachOAArch64>(MemMgr, Resolver);
360  case Triple::aarch64_32:
361    return std::make_unique<RuntimeDyldMachOAArch64>(MemMgr, Resolver);
362  case Triple::x86:
363    return std::make_unique<RuntimeDyldMachOI386>(MemMgr, Resolver);
364  case Triple::x86_64:
365    return std::make_unique<RuntimeDyldMachOX86_64>(MemMgr, Resolver);
366  }
367}
368
369std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
370RuntimeDyldMachO::loadObject(const object::ObjectFile &O) {
371  if (auto ObjSectionToIDOrErr = loadObjectImpl(O))
372    return std::make_unique<LoadedMachOObjectInfo>(*this,
373                                                    *ObjSectionToIDOrErr);
374  else {
375    HasError = true;
376    raw_string_ostream ErrStream(ErrorStr);
377    logAllUnhandledErrors(ObjSectionToIDOrErr.takeError(), ErrStream);
378    return nullptr;
379  }
380}
381
382} // end namespace llvm
383