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 : public RuntimeDyld::LoadedObjectInfo {
30 public:
31   LoadedMachOObjectInfo(RuntimeDyldImpl &RTDyld, unsigned BeginIdx,
32                         unsigned EndIdx)
33     : RuntimeDyld::LoadedObjectInfo(RTDyld, BeginIdx, EndIdx) {}
34 
35   OwningBinary<ObjectFile>
36   getObjectForDebug(const ObjectFile &Obj) const override {
37     return OwningBinary<ObjectFile>();
38   }
39 };
40 
41 }
42 
43 namespace llvm {
44 
45 int64_t RuntimeDyldMachO::memcpyAddend(const RelocationEntry &RE) const {
46   unsigned NumBytes = 1 << RE.Size;
47   uint8_t *Src = Sections[RE.SectionID].Address + RE.Offset;
48 
49   return static_cast<int64_t>(readBytesUnaligned(Src, NumBytes));
50 }
51 
52 RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
53     const ObjectFile &BaseTObj, const relocation_iterator &RI,
54     const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID) {
55 
56   const MachOObjectFile &Obj =
57       static_cast<const MachOObjectFile &>(BaseTObj);
58   MachO::any_relocation_info RelInfo =
59       Obj.getRelocation(RI->getRawDataRefImpl());
60   RelocationValueRef Value;
61 
62   bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
63   if (IsExternal) {
64     symbol_iterator Symbol = RI->getSymbol();
65     StringRef TargetName;
66     Symbol->getName(TargetName);
67     RTDyldSymbolTable::const_iterator SI =
68       GlobalSymbolTable.find(TargetName.data());
69     if (SI != GlobalSymbolTable.end()) {
70       const auto &SymInfo = SI->second;
71       Value.SectionID = SymInfo.getSectionID();
72       Value.Offset = SymInfo.getOffset() + RE.Addend;
73     } else {
74       Value.SymbolName = TargetName.data();
75       Value.Offset = RE.Addend;
76     }
77   } else {
78     SectionRef Sec = Obj.getRelocationSection(RelInfo);
79     bool IsCode = Sec.isText();
80     Value.SectionID = findOrEmitSection(Obj, Sec, IsCode, ObjSectionToID);
81     uint64_t Addr = Sec.getAddress();
82     Value.Offset = RE.Addend - Addr;
83   }
84 
85   return Value;
86 }
87 
88 void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
89                                             const ObjectFile &BaseTObj,
90                                             const relocation_iterator &RI,
91                                             unsigned OffsetToNextPC) {
92   const MachOObjectFile &Obj =
93       static_cast<const MachOObjectFile &>(BaseTObj);
94   MachO::any_relocation_info RelInfo =
95       Obj.getRelocation(RI->getRawDataRefImpl());
96 
97   bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
98   if (IsPCRel) {
99     uint64_t RelocAddr = 0;
100     RI->getAddress(RelocAddr);
101     Value.Offset += RelocAddr + OffsetToNextPC;
102   }
103 }
104 
105 void RuntimeDyldMachO::dumpRelocationToResolve(const RelocationEntry &RE,
106                                                uint64_t Value) const {
107   const SectionEntry &Section = Sections[RE.SectionID];
108   uint8_t *LocalAddress = Section.Address + RE.Offset;
109   uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
110 
111   dbgs() << "resolveRelocation Section: " << RE.SectionID
112          << " LocalAddress: " << format("%p", LocalAddress)
113          << " FinalAddress: " << format("0x%016" PRIx64, FinalAddress)
114          << " Value: " << format("0x%016" PRIx64, Value) << " Addend: " << RE.Addend
115          << " isPCRel: " << RE.IsPCRel << " MachoType: " << RE.RelType
116          << " Size: " << (1 << RE.Size) << "\n";
117 }
118 
119 section_iterator
120 RuntimeDyldMachO::getSectionByAddress(const MachOObjectFile &Obj,
121                                       uint64_t Addr) {
122   section_iterator SI = Obj.section_begin();
123   section_iterator SE = Obj.section_end();
124 
125   for (; SI != SE; ++SI) {
126     uint64_t SAddr = SI->getAddress();
127     uint64_t SSize = SI->getSize();
128     if ((Addr >= SAddr) && (Addr < SAddr + SSize))
129       return SI;
130   }
131 
132   return SE;
133 }
134 
135 
136 // Populate __pointers section.
137 void RuntimeDyldMachO::populateIndirectSymbolPointersSection(
138                                                     const MachOObjectFile &Obj,
139                                                     const SectionRef &PTSection,
140                                                     unsigned PTSectionID) {
141   assert(!Obj.is64Bit() &&
142          "Pointer table section not supported in 64-bit MachO.");
143 
144   MachO::dysymtab_command DySymTabCmd = Obj.getDysymtabLoadCommand();
145   MachO::section Sec32 = Obj.getSection(PTSection.getRawDataRefImpl());
146   uint32_t PTSectionSize = Sec32.size;
147   unsigned FirstIndirectSymbol = Sec32.reserved1;
148   const unsigned PTEntrySize = 4;
149   unsigned NumPTEntries = PTSectionSize / PTEntrySize;
150   unsigned PTEntryOffset = 0;
151 
152   assert((PTSectionSize % PTEntrySize) == 0 &&
153          "Pointers section does not contain a whole number of stubs?");
154 
155   DEBUG(dbgs() << "Populating pointer table section "
156                << Sections[PTSectionID].Name
157                << ", Section ID " << PTSectionID << ", "
158                << NumPTEntries << " entries, " << PTEntrySize
159                << " bytes each:\n");
160 
161   for (unsigned i = 0; i < NumPTEntries; ++i) {
162     unsigned SymbolIndex =
163       Obj.getIndirectSymbolTableEntry(DySymTabCmd, FirstIndirectSymbol + i);
164     symbol_iterator SI = Obj.getSymbolByIndex(SymbolIndex);
165     StringRef IndirectSymbolName;
166     SI->getName(IndirectSymbolName);
167     DEBUG(dbgs() << "  " << IndirectSymbolName << ": index " << SymbolIndex
168           << ", PT offset: " << PTEntryOffset << "\n");
169     RelocationEntry RE(PTSectionID, PTEntryOffset,
170                        MachO::GENERIC_RELOC_VANILLA, 0, false, 2);
171     addRelocationForSymbol(RE, IndirectSymbolName);
172     PTEntryOffset += PTEntrySize;
173   }
174 }
175 
176 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile &Obj) const {
177   return Obj.isMachO();
178 }
179 
180 template <typename Impl>
181 void RuntimeDyldMachOCRTPBase<Impl>::finalizeLoad(const ObjectFile &ObjImg,
182                                                   ObjSectionToIDMap &SectionMap) {
183   unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
184   unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
185   unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
186   ObjSectionToIDMap::iterator i, e;
187 
188   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
189     const SectionRef &Section = i->first;
190     StringRef Name;
191     Section.getName(Name);
192     if (Name == "__eh_frame")
193       EHFrameSID = i->second;
194     else if (Name == "__text")
195       TextSID = i->second;
196     else if (Name == "__gcc_except_tab")
197       ExceptTabSID = i->second;
198     else
199       impl().finalizeSection(ObjImg, i->second, Section);
200   }
201   UnregisteredEHFrameSections.push_back(
202     EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
203 }
204 
205 template <typename Impl>
206 unsigned char *RuntimeDyldMachOCRTPBase<Impl>::processFDE(unsigned char *P,
207                                                           int64_t DeltaForText,
208                                                           int64_t DeltaForEH) {
209   typedef typename Impl::TargetPtrT TargetPtrT;
210 
211   DEBUG(dbgs() << "Processing FDE: Delta for text: " << DeltaForText
212                << ", Delta for EH: " << DeltaForEH << "\n");
213   uint32_t Length = readBytesUnaligned(P, 4);
214   P += 4;
215   unsigned char *Ret = P + Length;
216   uint32_t Offset = readBytesUnaligned(P, 4);
217   if (Offset == 0) // is a CIE
218     return Ret;
219 
220   P += 4;
221   TargetPtrT FDELocation = readBytesUnaligned(P, sizeof(TargetPtrT));
222   TargetPtrT NewLocation = FDELocation - DeltaForText;
223   writeBytesUnaligned(NewLocation, P, sizeof(TargetPtrT));
224 
225   P += sizeof(TargetPtrT);
226 
227   // Skip the FDE address range
228   P += sizeof(TargetPtrT);
229 
230   uint8_t Augmentationsize = *P;
231   P += 1;
232   if (Augmentationsize != 0) {
233     TargetPtrT LSDA = readBytesUnaligned(P, sizeof(TargetPtrT));
234     TargetPtrT NewLSDA = LSDA - DeltaForEH;
235     writeBytesUnaligned(NewLSDA, P, sizeof(TargetPtrT));
236   }
237 
238   return Ret;
239 }
240 
241 static int64_t computeDelta(SectionEntry *A, SectionEntry *B) {
242   int64_t ObjDistance = A->ObjAddress - B->ObjAddress;
243   int64_t MemDistance = A->LoadAddress - B->LoadAddress;
244   return ObjDistance - MemDistance;
245 }
246 
247 template <typename Impl>
248 void RuntimeDyldMachOCRTPBase<Impl>::registerEHFrames() {
249 
250   if (!MemMgr)
251     return;
252   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
253     EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
254     if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
255         SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
256       continue;
257     SectionEntry *Text = &Sections[SectionInfo.TextSID];
258     SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
259     SectionEntry *ExceptTab = nullptr;
260     if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
261       ExceptTab = &Sections[SectionInfo.ExceptTabSID];
262 
263     int64_t DeltaForText = computeDelta(Text, EHFrame);
264     int64_t DeltaForEH = 0;
265     if (ExceptTab)
266       DeltaForEH = computeDelta(ExceptTab, EHFrame);
267 
268     unsigned char *P = EHFrame->Address;
269     unsigned char *End = P + EHFrame->Size;
270     do {
271       P = processFDE(P, DeltaForText, DeltaForEH);
272     } while (P != End);
273 
274     MemMgr->registerEHFrames(EHFrame->Address, EHFrame->LoadAddress,
275                              EHFrame->Size);
276   }
277   UnregisteredEHFrameSections.clear();
278 }
279 
280 std::unique_ptr<RuntimeDyldMachO>
281 RuntimeDyldMachO::create(Triple::ArchType Arch, RTDyldMemoryManager *MM) {
282   switch (Arch) {
283   default:
284     llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
285     break;
286   case Triple::arm: return make_unique<RuntimeDyldMachOARM>(MM);
287   case Triple::aarch64: return make_unique<RuntimeDyldMachOAArch64>(MM);
288   case Triple::x86: return make_unique<RuntimeDyldMachOI386>(MM);
289   case Triple::x86_64: return make_unique<RuntimeDyldMachOX86_64>(MM);
290   }
291 }
292 
293 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
294 RuntimeDyldMachO::loadObject(const object::ObjectFile &O) {
295   unsigned SectionStartIdx, SectionEndIdx;
296   std::tie(SectionStartIdx, SectionEndIdx) = loadObjectImpl(O);
297   return llvm::make_unique<LoadedMachOObjectInfo>(*this, SectionStartIdx,
298                                                   SectionEndIdx);
299 }
300 
301 } // end namespace llvm
302