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