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