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