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 
21 using namespace llvm;
22 using namespace llvm::object;
23 
24 #define DEBUG_TYPE "dyld"
25 
26 namespace {
27 
28 class LoadedMachOObjectInfo final
29     : public LoadedObjectInfoHelper<LoadedMachOObjectInfo,
30                                     RuntimeDyld::LoadedObjectInfo> {
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].getAddress() + RE.Offset;
49 
50   return static_cast<int64_t>(readBytesUnaligned(Src, NumBytes));
51 }
52 
53 Expected<relocation_iterator>
54 RuntimeDyldMachO::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 
96 Expected<RelocationValueRef>
97 RuntimeDyldMachO::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 
140 void 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 
148 void 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 
162 section_iterator
163 RuntimeDyldMachO::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.
180 Error 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 
222 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile &Obj) const {
223   return Obj.isMachO();
224 }
225 
226 template <typename Impl>
227 Error
228 RuntimeDyldMachOCRTPBase<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 
274 template <typename Impl>
275 unsigned 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 
310 static 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 
317 template <typename Impl>
318 void 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 
348 std::unique_ptr<RuntimeDyldMachO>
349 RuntimeDyldMachO::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 
369 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
370 RuntimeDyldMachO::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