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