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