1 //===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Implementation of ELF support for the MC-JIT runtime dynamic linker.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "dyld"
15 #include "llvm/ADT/OwningPtr.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/IntervalMap.h"
19 #include "RuntimeDyldELF.h"
20 #include "llvm/Object/ObjectFile.h"
21 #include "llvm/Support/ELF.h"
22 #include "llvm/ADT/Triple.h"
23 #include "llvm/Object/ELF.h"
24 #include "JITRegistrar.h"
26 using namespace llvm::object;
30 template<support::endianness target_endianness, bool is64Bits>
31 class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
32 LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
34 typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
35 typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
36 typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
37 typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
39 typedef typename ELFObjectFile<target_endianness, is64Bits>::
42 typedef typename ELFDataTypeTypedefHelper<
43 target_endianness, is64Bits>::value_type addr_type;
46 // This duplicates the 'Data' member in the 'Binary' base class
47 // but it is necessary to workaround a bug in gcc 4.2
48 MemoryBuffer *InputData;
51 DyldELFObject(MemoryBuffer *Object, error_code &ec);
53 void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
54 void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
56 const MemoryBuffer& getBuffer() const { return *InputData; }
58 // Methods for type inquiry through isa, cast and dyn_cast
59 static inline bool classof(const Binary *v) {
60 return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
61 && classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
63 static inline bool classof(
64 const ELFObjectFile<target_endianness, is64Bits> *v) {
65 return v->isDyldType();
67 static inline bool classof(const DyldELFObject *v) {
72 template<support::endianness target_endianness, bool is64Bits>
73 class ELFObjectImage : public ObjectImage {
75 DyldELFObject<target_endianness, is64Bits> *DyldObj;
79 ELFObjectImage(DyldELFObject<target_endianness, is64Bits> *Obj)
84 virtual ~ELFObjectImage() {
86 deregisterWithDebugger();
89 // Subclasses can override these methods to update the image with loaded
90 // addresses for sections and common symbols
91 virtual void updateSectionAddress(const SectionRef &Sec, uint64_t Addr)
93 DyldObj->updateSectionAddress(Sec, Addr);
96 virtual void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr)
98 DyldObj->updateSymbolAddress(Sym, Addr);
101 virtual void registerWithDebugger()
103 JITRegistrar::getGDBRegistrar().registerObject(DyldObj->getBuffer());
106 virtual void deregisterWithDebugger()
108 JITRegistrar::getGDBRegistrar().deregisterObject(DyldObj->getBuffer());
112 template<support::endianness target_endianness, bool is64Bits>
113 DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Object,
115 : ELFObjectFile<target_endianness, is64Bits>(Object, ec),
117 this->isDyldELFObject = true;
120 template<support::endianness target_endianness, bool is64Bits>
121 void DyldELFObject<target_endianness, is64Bits>::updateSectionAddress(
122 const SectionRef &Sec,
124 DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
125 Elf_Shdr *shdr = const_cast<Elf_Shdr*>(
126 reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
128 // This assumes the address passed in matches the target address bitness
129 // The template-based type cast handles everything else.
130 shdr->sh_addr = static_cast<addr_type>(Addr);
133 template<support::endianness target_endianness, bool is64Bits>
134 void DyldELFObject<target_endianness, is64Bits>::updateSymbolAddress(
135 const SymbolRef &SymRef,
138 Elf_Sym *sym = const_cast<Elf_Sym*>(
139 ELFObjectFile<target_endianness, is64Bits>::
140 getSymbol(SymRef.getRawDataRefImpl()));
142 // This assumes the address passed in matches the target address bitness
143 // The template-based type cast handles everything else.
144 sym->st_value = static_cast<addr_type>(Addr);
152 ObjectImage *RuntimeDyldELF::createObjectImage(
153 const MemoryBuffer *ConstInputBuffer) {
154 MemoryBuffer *InputBuffer = const_cast<MemoryBuffer*>(ConstInputBuffer);
155 std::pair<unsigned char, unsigned char> Ident = getElfArchType(InputBuffer);
158 if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
159 DyldELFObject<support::little, false> *Obj =
160 new DyldELFObject<support::little, false>(InputBuffer, ec);
161 return new ELFObjectImage<support::little, false>(Obj);
163 else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
164 DyldELFObject<support::big, false> *Obj =
165 new DyldELFObject<support::big, false>(InputBuffer, ec);
166 return new ELFObjectImage<support::big, false>(Obj);
168 else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
169 DyldELFObject<support::big, true> *Obj =
170 new DyldELFObject<support::big, true>(InputBuffer, ec);
171 return new ELFObjectImage<support::big, true>(Obj);
173 else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
174 DyldELFObject<support::little, true> *Obj =
175 new DyldELFObject<support::little, true>(InputBuffer, ec);
176 return new ELFObjectImage<support::little, true>(Obj);
179 llvm_unreachable("Unexpected ELF format");
182 void RuntimeDyldELF::handleObjectLoaded(ObjectImage *Obj)
184 Obj->registerWithDebugger();
185 // Save the loaded object. It will deregister itself when deleted
189 RuntimeDyldELF::~RuntimeDyldELF() {
194 void RuntimeDyldELF::resolveX86_64Relocation(uint8_t *LocalAddress,
195 uint64_t FinalAddress,
201 llvm_unreachable("Relocation type not implemented yet!");
203 case ELF::R_X86_64_64: {
204 uint64_t *Target = (uint64_t*)(LocalAddress);
205 *Target = Value + Addend;
208 case ELF::R_X86_64_32:
209 case ELF::R_X86_64_32S: {
211 assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
212 (Type == ELF::R_X86_64_32S &&
213 ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
214 uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
215 uint32_t *Target = reinterpret_cast<uint32_t*>(LocalAddress);
216 *Target = TruncatedAddr;
219 case ELF::R_X86_64_PC32: {
220 uint32_t *Placeholder = reinterpret_cast<uint32_t*>(LocalAddress);
221 int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
222 assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
223 int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
224 *Placeholder = TruncOffset;
230 void RuntimeDyldELF::resolveX86Relocation(uint8_t *LocalAddress,
231 uint32_t FinalAddress,
236 case ELF::R_386_32: {
237 uint32_t *Target = (uint32_t*)(LocalAddress);
238 uint32_t Placeholder = *Target;
239 *Target = Placeholder + Value + Addend;
242 case ELF::R_386_PC32: {
243 uint32_t *Placeholder = reinterpret_cast<uint32_t*>(LocalAddress);
244 uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
245 *Placeholder = RealOffset;
249 // There are other relocation types, but it appears these are the
250 // only ones currently used by the LLVM ELF object writer
251 llvm_unreachable("Relocation type not implemented yet!");
256 void RuntimeDyldELF::resolveARMRelocation(uint8_t *LocalAddress,
257 uint32_t FinalAddress,
261 // TODO: Add Thumb relocations.
262 uint32_t* TargetPtr = (uint32_t*)LocalAddress;
265 DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: " << LocalAddress
266 << " FinalAddress: " << format("%p",FinalAddress)
267 << " Value: " << format("%x",Value)
268 << " Type: " << format("%x",Type)
269 << " Addend: " << format("%x",Addend)
274 llvm_unreachable("Not implemented relocation type!");
276 // Just write 32bit value to relocation address
277 case ELF::R_ARM_ABS32 :
281 // Write first 16 bit of 32 bit value to the mov instruction.
282 // Last 4 bit should be shifted.
283 case ELF::R_ARM_MOVW_ABS_NC :
284 Value = Value & 0xFFFF;
285 *TargetPtr |= Value & 0xFFF;
286 *TargetPtr |= ((Value >> 12) & 0xF) << 16;
289 // Write last 16 bit of 32 bit value to the mov instruction.
290 // Last 4 bit should be shifted.
291 case ELF::R_ARM_MOVT_ABS :
292 Value = (Value >> 16) & 0xFFFF;
293 *TargetPtr |= Value & 0xFFF;
294 *TargetPtr |= ((Value >> 12) & 0xF) << 16;
297 // Write 24 bit relative value to the branch instruction.
298 case ELF::R_ARM_PC24 : // Fall through.
299 case ELF::R_ARM_CALL : // Fall through.
300 case ELF::R_ARM_JUMP24 :
301 int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
302 RelValue = (RelValue & 0x03FFFFFC) >> 2;
303 *TargetPtr &= 0xFF000000;
304 *TargetPtr |= RelValue;
309 void RuntimeDyldELF::resolveRelocation(uint8_t *LocalAddress,
310 uint64_t FinalAddress,
316 resolveX86_64Relocation(LocalAddress, FinalAddress, Value, Type, Addend);
319 resolveX86Relocation(LocalAddress, (uint32_t)(FinalAddress & 0xffffffffL),
320 (uint32_t)(Value & 0xffffffffL), Type,
321 (uint32_t)(Addend & 0xffffffffL));
323 case Triple::arm: // Fall through.
325 resolveARMRelocation(LocalAddress, (uint32_t)(FinalAddress & 0xffffffffL),
326 (uint32_t)(Value & 0xffffffffL), Type,
327 (uint32_t)(Addend & 0xffffffffL));
329 default: llvm_unreachable("Unsupported CPU type!");
333 void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
335 ObjSectionToIDMap &ObjSectionToID,
336 const SymbolTableMap &Symbols,
339 uint32_t RelType = (uint32_t)(Rel.Type & 0xffffffffL);
340 intptr_t Addend = (intptr_t)Rel.AdditionalInfo;
341 const SymbolRef &Symbol = Rel.Symbol;
343 // Obtain the symbol name which is referenced in the relocation
344 StringRef TargetName;
345 Symbol.getName(TargetName);
346 DEBUG(dbgs() << "\t\tRelType: " << RelType
347 << " Addend: " << Addend
348 << " TargetName: " << TargetName
350 RelocationValueRef Value;
351 // First search for the symbol in the local symbol table
352 SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
353 if (lsi != Symbols.end()) {
354 Value.SectionID = lsi->second.first;
355 Value.Addend = lsi->second.second;
357 // Search for the symbol in the global symbol table
358 SymbolTableMap::const_iterator gsi =
359 GlobalSymbolTable.find(TargetName.data());
360 if (gsi != GlobalSymbolTable.end()) {
361 Value.SectionID = gsi->second.first;
362 Value.Addend = gsi->second.second;
364 SymbolRef::Type SymType;
365 Symbol.getType(SymType);
367 case SymbolRef::ST_Debug: {
368 // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
369 // and can be changed by another developers. Maybe best way is add
370 // a new symbol type ST_Section to SymbolRef and use it.
371 section_iterator si(Obj.end_sections());
372 Symbol.getSection(si);
373 if (si == Obj.end_sections())
374 llvm_unreachable("Symbol section not found, bad object file format!");
375 DEBUG(dbgs() << "\t\tThis is section symbol\n");
376 Value.SectionID = findOrEmitSection(Obj, (*si), true, ObjSectionToID);
377 Value.Addend = Addend;
380 case SymbolRef::ST_Unknown: {
381 Value.SymbolName = TargetName.data();
382 Value.Addend = Addend;
386 llvm_unreachable("Unresolved symbol type!");
391 DEBUG(dbgs() << "\t\tRel.SectionID: " << Rel.SectionID
392 << " Rel.Offset: " << Rel.Offset
394 if (Arch == Triple::arm &&
395 (RelType == ELF::R_ARM_PC24 ||
396 RelType == ELF::R_ARM_CALL ||
397 RelType == ELF::R_ARM_JUMP24)) {
398 // This is an ARM branch relocation, need to use a stub function.
399 DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
400 SectionEntry &Section = Sections[Rel.SectionID];
401 uint8_t *Target = Section.Address + Rel.Offset;
403 // Look up for existing stub.
404 StubMap::const_iterator i = Stubs.find(Value);
405 if (i != Stubs.end()) {
406 resolveRelocation(Target, (uint64_t)Target, (uint64_t)Section.Address +
407 i->second, RelType, 0);
408 DEBUG(dbgs() << " Stub function found\n");
410 // Create a new stub function.
411 DEBUG(dbgs() << " Create a new stub function\n");
412 Stubs[Value] = Section.StubOffset;
413 uint8_t *StubTargetAddr = createStubFunction(Section.Address +
415 RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
416 ELF::R_ARM_ABS32, Value.Addend);
417 if (Value.SymbolName)
418 addRelocationForSymbol(RE, Value.SymbolName);
420 addRelocationForSection(RE, Value.SectionID);
422 resolveRelocation(Target, (uint64_t)Target, (uint64_t)Section.Address +
423 Section.StubOffset, RelType, 0);
424 Section.StubOffset += getMaxStubSize();
427 RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
428 if (Value.SymbolName)
429 addRelocationForSymbol(RE, Value.SymbolName);
431 addRelocationForSection(RE, Value.SectionID);
435 bool RuntimeDyldELF::isCompatibleFormat(const MemoryBuffer *InputBuffer) const {
436 StringRef Magic = InputBuffer->getBuffer().slice(0, ELF::EI_NIDENT);
437 return (memcmp(Magic.data(), ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;