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 "llvm/ADT/STLExtras.h"
16 #include "llvm/ADT/StringRef.h"
17 
18 #include "Targets/RuntimeDyldMachOARM.h"
19 #include "Targets/RuntimeDyldMachOAArch64.h"
20 #include "Targets/RuntimeDyldMachOI386.h"
21 #include "Targets/RuntimeDyldMachOX86_64.h"
22 
23 using namespace llvm;
24 using namespace llvm::object;
25 
26 #define DEBUG_TYPE "dyld"
27 
28 namespace llvm {
29 
30 uint64_t RuntimeDyldMachO::decodeAddend(uint8_t *LocalAddress, unsigned NumBytes,
31                                         uint32_t RelType) const {
32   uint64_t Addend = 0;
33   memcpy(&Addend, LocalAddress, NumBytes);
34   return Addend;
35 }
36 
37 RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
38     ObjectImage &ObjImg, const relocation_iterator &RI,
39     const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID,
40     const SymbolTableMap &Symbols) {
41 
42   const MachOObjectFile &Obj =
43       static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
44   MachO::any_relocation_info RelInfo =
45       Obj.getRelocation(RI->getRawDataRefImpl());
46   RelocationValueRef Value;
47 
48   bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
49   if (IsExternal) {
50     symbol_iterator Symbol = RI->getSymbol();
51     StringRef TargetName;
52     Symbol->getName(TargetName);
53     SymbolTableMap::const_iterator SI = Symbols.find(TargetName.data());
54     if (SI != Symbols.end()) {
55       Value.SectionID = SI->second.first;
56       Value.Addend = SI->second.second + RE.Addend;
57     } else {
58       SI = GlobalSymbolTable.find(TargetName.data());
59       if (SI != GlobalSymbolTable.end()) {
60         Value.SectionID = SI->second.first;
61         Value.Addend = SI->second.second + RE.Addend;
62       } else {
63         Value.SymbolName = TargetName.data();
64         Value.Addend = RE.Addend;
65       }
66     }
67   } else {
68     SectionRef Sec = Obj.getRelocationSection(RelInfo);
69     bool IsCode = false;
70     Sec.isText(IsCode);
71     Value.SectionID = findOrEmitSection(ObjImg, Sec, IsCode, ObjSectionToID);
72     uint64_t Addr;
73     Sec.getAddress(Addr);
74     Value.Addend = RE.Addend - Addr;
75   }
76 
77   return Value;
78 }
79 
80 void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
81                                             ObjectImage &ObjImg,
82                                             const relocation_iterator &RI) {
83   const MachOObjectFile &Obj =
84       static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
85   MachO::any_relocation_info RelInfo =
86       Obj.getRelocation(RI->getRawDataRefImpl());
87 
88   bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
89   if (IsPCRel) {
90     uint64_t RelocAddr = 0;
91     RI->getAddress(RelocAddr);
92     unsigned RelocSize = Obj.getAnyRelocationLength(RelInfo);
93     Value.Addend += RelocAddr + (1ULL << RelocSize);
94   }
95 }
96 
97 void RuntimeDyldMachO::dumpRelocationToResolve(const RelocationEntry &RE,
98                                                uint64_t Value) const {
99   const SectionEntry &Section = Sections[RE.SectionID];
100   uint8_t *LocalAddress = Section.Address + RE.Offset;
101   uint64_t FinalAddress = Section.LoadAddress + RE.Offset;
102 
103   dbgs() << "resolveRelocation Section: " << RE.SectionID
104          << " LocalAddress: " << format("%p", LocalAddress)
105          << " FinalAddress: " << format("%p", FinalAddress)
106          << " Value: " << format("%p", Value) << " Addend: " << RE.Addend
107          << " isPCRel: " << RE.IsPCRel << " MachoType: " << RE.RelType
108          << " Size: " << (1 << RE.Size) << "\n";
109 }
110 
111 bool RuntimeDyldMachO::writeBytesUnaligned(uint8_t *Addr, uint64_t Value,
112                                            unsigned Size) {
113   for (unsigned i = 0; i < Size; ++i) {
114     *Addr++ = (uint8_t)Value;
115     Value >>= 8;
116   }
117 
118   return false;
119 }
120 
121 bool
122 RuntimeDyldMachO::isCompatibleFormat(const ObjectBuffer *InputBuffer) const {
123   if (InputBuffer->getBufferSize() < 4)
124     return false;
125   StringRef Magic(InputBuffer->getBufferStart(), 4);
126   if (Magic == "\xFE\xED\xFA\xCE")
127     return true;
128   if (Magic == "\xCE\xFA\xED\xFE")
129     return true;
130   if (Magic == "\xFE\xED\xFA\xCF")
131     return true;
132   if (Magic == "\xCF\xFA\xED\xFE")
133     return true;
134   return false;
135 }
136 
137 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile *Obj) const {
138   return Obj->isMachO();
139 }
140 
141 static unsigned char *processFDE(unsigned char *P, intptr_t DeltaForText,
142                                  intptr_t DeltaForEH) {
143   DEBUG(dbgs() << "Processing FDE: Delta for text: " << DeltaForText
144                << ", Delta for EH: " << DeltaForEH << "\n");
145   uint32_t Length = *((uint32_t *)P);
146   P += 4;
147   unsigned char *Ret = P + Length;
148   uint32_t Offset = *((uint32_t *)P);
149   if (Offset == 0) // is a CIE
150     return Ret;
151 
152   P += 4;
153   intptr_t FDELocation = *((intptr_t *)P);
154   intptr_t NewLocation = FDELocation - DeltaForText;
155   *((intptr_t *)P) = NewLocation;
156   P += sizeof(intptr_t);
157 
158   // Skip the FDE address range
159   P += sizeof(intptr_t);
160 
161   uint8_t Augmentationsize = *P;
162   P += 1;
163   if (Augmentationsize != 0) {
164     intptr_t LSDA = *((intptr_t *)P);
165     intptr_t NewLSDA = LSDA - DeltaForEH;
166     *((intptr_t *)P) = NewLSDA;
167   }
168 
169   return Ret;
170 }
171 
172 static intptr_t computeDelta(SectionEntry *A, SectionEntry *B) {
173   intptr_t ObjDistance = A->ObjAddress - B->ObjAddress;
174   intptr_t MemDistance = A->LoadAddress - B->LoadAddress;
175   return ObjDistance - MemDistance;
176 }
177 
178 void RuntimeDyldMachO::registerEHFrames() {
179 
180   if (!MemMgr)
181     return;
182   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
183     EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
184     if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
185         SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
186       continue;
187     SectionEntry *Text = &Sections[SectionInfo.TextSID];
188     SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
189     SectionEntry *ExceptTab = nullptr;
190     if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
191       ExceptTab = &Sections[SectionInfo.ExceptTabSID];
192 
193     intptr_t DeltaForText = computeDelta(Text, EHFrame);
194     intptr_t DeltaForEH = 0;
195     if (ExceptTab)
196       DeltaForEH = computeDelta(ExceptTab, EHFrame);
197 
198     unsigned char *P = EHFrame->Address;
199     unsigned char *End = P + EHFrame->Size;
200     do {
201       P = processFDE(P, DeltaForText, DeltaForEH);
202     } while (P != End);
203 
204     MemMgr->registerEHFrames(EHFrame->Address, EHFrame->LoadAddress,
205                              EHFrame->Size);
206   }
207   UnregisteredEHFrameSections.clear();
208 }
209 
210 std::unique_ptr<RuntimeDyldMachO>
211 llvm::RuntimeDyldMachO::create(Triple::ArchType Arch, RTDyldMemoryManager *MM) {
212   switch (Arch) {
213   default:
214     llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
215     break;
216   case Triple::arm: return make_unique<RuntimeDyldMachOARM>(MM);
217   case Triple::arm64: return make_unique<RuntimeDyldMachOAArch64>(MM);
218   case Triple::x86: return make_unique<RuntimeDyldMachOI386>(MM);
219   case Triple::x86_64: return make_unique<RuntimeDyldMachOX86_64>(MM);
220   }
221 }
222 
223 } // end namespace llvm
224