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:
LoadedMachOObjectInfo(RuntimeDyldImpl & RTDyld,unsigned BeginIdx,unsigned EndIdx)31 LoadedMachOObjectInfo(RuntimeDyldImpl &RTDyld, unsigned BeginIdx,
32 unsigned EndIdx)
33 : RuntimeDyld::LoadedObjectInfo(RTDyld, BeginIdx, EndIdx) {}
34
35 OwningBinary<ObjectFile>
getObjectForDebug(const ObjectFile & Obj) const36 getObjectForDebug(const ObjectFile &Obj) const override {
37 return OwningBinary<ObjectFile>();
38 }
39 };
40
41 }
42
43 namespace llvm {
44
memcpyAddend(const RelocationEntry & RE) const45 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
getRelocationValueRef(const ObjectFile & BaseTObj,const relocation_iterator & RI,const RelocationEntry & RE,ObjSectionToIDMap & ObjSectionToID)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
makeValueAddendPCRel(RelocationValueRef & Value,const ObjectFile & BaseTObj,const relocation_iterator & RI,unsigned OffsetToNextPC)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
dumpRelocationToResolve(const RelocationEntry & RE,uint64_t Value) const105 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
getSectionByAddress(const MachOObjectFile & Obj,uint64_t Addr)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.
populateIndirectSymbolPointersSection(const MachOObjectFile & Obj,const SectionRef & PTSection,unsigned PTSectionID)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
isCompatibleFile(const object::ObjectFile & Obj) const176 bool RuntimeDyldMachO::isCompatibleFile(const object::ObjectFile &Obj) const {
177 return Obj.isMachO();
178 }
179
180 template <typename Impl>
finalizeLoad(const ObjectFile & Obj,ObjSectionToIDMap & SectionMap)181 void RuntimeDyldMachOCRTPBase<Impl>::finalizeLoad(const ObjectFile &Obj,
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
187 for (const auto &Section : Obj.sections()) {
188 StringRef Name;
189 Section.getName(Name);
190
191 // Force emission of the __text, __eh_frame, and __gcc_except_tab sections
192 // if they're present. Otherwise call down to the impl to handle other
193 // sections that have already been emitted.
194 if (Name == "__text")
195 TextSID = findOrEmitSection(Obj, Section, true, SectionMap);
196 else if (Name == "__eh_frame")
197 EHFrameSID = findOrEmitSection(Obj, Section, false, SectionMap);
198 else if (Name == "__gcc_except_tab")
199 ExceptTabSID = findOrEmitSection(Obj, Section, true, SectionMap);
200 else {
201 auto I = SectionMap.find(Section);
202 if (I != SectionMap.end())
203 impl().finalizeSection(Obj, I->second, Section);
204 }
205 }
206 UnregisteredEHFrameSections.push_back(
207 EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
208 }
209
210 template <typename Impl>
processFDE(unsigned char * P,int64_t DeltaForText,int64_t DeltaForEH)211 unsigned char *RuntimeDyldMachOCRTPBase<Impl>::processFDE(unsigned char *P,
212 int64_t DeltaForText,
213 int64_t DeltaForEH) {
214 typedef typename Impl::TargetPtrT TargetPtrT;
215
216 DEBUG(dbgs() << "Processing FDE: Delta for text: " << DeltaForText
217 << ", Delta for EH: " << DeltaForEH << "\n");
218 uint32_t Length = readBytesUnaligned(P, 4);
219 P += 4;
220 unsigned char *Ret = P + Length;
221 uint32_t Offset = readBytesUnaligned(P, 4);
222 if (Offset == 0) // is a CIE
223 return Ret;
224
225 P += 4;
226 TargetPtrT FDELocation = readBytesUnaligned(P, sizeof(TargetPtrT));
227 TargetPtrT NewLocation = FDELocation - DeltaForText;
228 writeBytesUnaligned(NewLocation, P, sizeof(TargetPtrT));
229
230 P += sizeof(TargetPtrT);
231
232 // Skip the FDE address range
233 P += sizeof(TargetPtrT);
234
235 uint8_t Augmentationsize = *P;
236 P += 1;
237 if (Augmentationsize != 0) {
238 TargetPtrT LSDA = readBytesUnaligned(P, sizeof(TargetPtrT));
239 TargetPtrT NewLSDA = LSDA - DeltaForEH;
240 writeBytesUnaligned(NewLSDA, P, sizeof(TargetPtrT));
241 }
242
243 return Ret;
244 }
245
computeDelta(SectionEntry * A,SectionEntry * B)246 static int64_t computeDelta(SectionEntry *A, SectionEntry *B) {
247 int64_t ObjDistance =
248 static_cast<int64_t>(A->ObjAddress) - static_cast<int64_t>(B->ObjAddress);
249 int64_t MemDistance = A->LoadAddress - B->LoadAddress;
250 return ObjDistance - MemDistance;
251 }
252
253 template <typename Impl>
registerEHFrames()254 void RuntimeDyldMachOCRTPBase<Impl>::registerEHFrames() {
255
256 for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
257 EHFrameRelatedSections &SectionInfo = UnregisteredEHFrameSections[i];
258 if (SectionInfo.EHFrameSID == RTDYLD_INVALID_SECTION_ID ||
259 SectionInfo.TextSID == RTDYLD_INVALID_SECTION_ID)
260 continue;
261 SectionEntry *Text = &Sections[SectionInfo.TextSID];
262 SectionEntry *EHFrame = &Sections[SectionInfo.EHFrameSID];
263 SectionEntry *ExceptTab = nullptr;
264 if (SectionInfo.ExceptTabSID != RTDYLD_INVALID_SECTION_ID)
265 ExceptTab = &Sections[SectionInfo.ExceptTabSID];
266
267 int64_t DeltaForText = computeDelta(Text, EHFrame);
268 int64_t DeltaForEH = 0;
269 if (ExceptTab)
270 DeltaForEH = computeDelta(ExceptTab, EHFrame);
271
272 unsigned char *P = EHFrame->Address;
273 unsigned char *End = P + EHFrame->Size;
274 do {
275 P = processFDE(P, DeltaForText, DeltaForEH);
276 } while (P != End);
277
278 MemMgr.registerEHFrames(EHFrame->Address, EHFrame->LoadAddress,
279 EHFrame->Size);
280 }
281 UnregisteredEHFrameSections.clear();
282 }
283
284 std::unique_ptr<RuntimeDyldMachO>
create(Triple::ArchType Arch,RuntimeDyld::MemoryManager & MemMgr,RuntimeDyld::SymbolResolver & Resolver)285 RuntimeDyldMachO::create(Triple::ArchType Arch,
286 RuntimeDyld::MemoryManager &MemMgr,
287 RuntimeDyld::SymbolResolver &Resolver) {
288 switch (Arch) {
289 default:
290 llvm_unreachable("Unsupported target for RuntimeDyldMachO.");
291 break;
292 case Triple::arm:
293 return make_unique<RuntimeDyldMachOARM>(MemMgr, Resolver);
294 case Triple::aarch64:
295 return make_unique<RuntimeDyldMachOAArch64>(MemMgr, Resolver);
296 case Triple::x86:
297 return make_unique<RuntimeDyldMachOI386>(MemMgr, Resolver);
298 case Triple::x86_64:
299 return make_unique<RuntimeDyldMachOX86_64>(MemMgr, Resolver);
300 }
301 }
302
303 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
loadObject(const object::ObjectFile & O)304 RuntimeDyldMachO::loadObject(const object::ObjectFile &O) {
305 unsigned SectionStartIdx, SectionEndIdx;
306 std::tie(SectionStartIdx, SectionEndIdx) = loadObjectImpl(O);
307 return llvm::make_unique<LoadedMachOObjectInfo>(*this, SectionStartIdx,
308 SectionEndIdx);
309 }
310
311 } // end namespace llvm
312