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 "RuntimeDyldELF.h"
16 #include "JITRegistrar.h"
17 #include "ObjectImageCommon.h"
18 #include "llvm/ADT/OwningPtr.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/ADT/STLExtras.h"
21 #include "llvm/ADT/IntervalMap.h"
22 #include "llvm/Object/ObjectFile.h"
23 #include "llvm/ExecutionEngine/ObjectImage.h"
24 #include "llvm/ExecutionEngine/ObjectBuffer.h"
25 #include "llvm/Support/ELF.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/Object/ELF.h"
29 using namespace llvm::object;
33 template<support::endianness target_endianness, bool is64Bits>
34 class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
35 LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
37 typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
38 typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
39 typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
40 typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
42 typedef Elf_Ehdr_Impl<target_endianness, is64Bits> Elf_Ehdr;
44 typedef typename ELFDataTypeTypedefHelper<
45 target_endianness, is64Bits>::value_type addr_type;
48 DyldELFObject(MemoryBuffer *Wrapper, error_code &ec);
50 void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
51 void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
53 // Methods for type inquiry through isa, cast and dyn_cast
54 static inline bool classof(const Binary *v) {
55 return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
56 && classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
58 static inline bool classof(
59 const ELFObjectFile<target_endianness, is64Bits> *v) {
60 return v->isDyldType();
62 static inline bool classof(const DyldELFObject *v) {
67 template<support::endianness target_endianness, bool is64Bits>
68 class ELFObjectImage : public ObjectImageCommon {
70 DyldELFObject<target_endianness, is64Bits> *DyldObj;
74 ELFObjectImage(ObjectBuffer *Input,
75 DyldELFObject<target_endianness, is64Bits> *Obj)
76 : ObjectImageCommon(Input, Obj),
80 virtual ~ELFObjectImage() {
82 deregisterWithDebugger();
85 // Subclasses can override these methods to update the image with loaded
86 // addresses for sections and common symbols
87 virtual void updateSectionAddress(const SectionRef &Sec, uint64_t Addr)
89 DyldObj->updateSectionAddress(Sec, Addr);
92 virtual void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr)
94 DyldObj->updateSymbolAddress(Sym, Addr);
97 virtual void registerWithDebugger()
99 JITRegistrar::getGDBRegistrar().registerObject(*Buffer);
102 virtual void deregisterWithDebugger()
104 JITRegistrar::getGDBRegistrar().deregisterObject(*Buffer);
108 // The MemoryBuffer passed into this constructor is just a wrapper around the
109 // actual memory. Ultimately, the Binary parent class will take ownership of
110 // this MemoryBuffer object but not the underlying memory.
111 template<support::endianness target_endianness, bool is64Bits>
112 DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Wrapper,
114 : ELFObjectFile<target_endianness, is64Bits>(Wrapper, ec) {
115 this->isDyldELFObject = true;
118 template<support::endianness target_endianness, bool is64Bits>
119 void DyldELFObject<target_endianness, is64Bits>::updateSectionAddress(
120 const SectionRef &Sec,
122 DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
123 Elf_Shdr *shdr = const_cast<Elf_Shdr*>(
124 reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
126 // This assumes the address passed in matches the target address bitness
127 // The template-based type cast handles everything else.
128 shdr->sh_addr = static_cast<addr_type>(Addr);
131 template<support::endianness target_endianness, bool is64Bits>
132 void DyldELFObject<target_endianness, is64Bits>::updateSymbolAddress(
133 const SymbolRef &SymRef,
136 Elf_Sym *sym = const_cast<Elf_Sym*>(
137 ELFObjectFile<target_endianness, is64Bits>::
138 getSymbol(SymRef.getRawDataRefImpl()));
140 // This assumes the address passed in matches the target address bitness
141 // The template-based type cast handles everything else.
142 sym->st_value = static_cast<addr_type>(Addr);
150 ObjectImage *RuntimeDyldELF::createObjectImage(ObjectBuffer *Buffer) {
151 if (Buffer->getBufferSize() < ELF::EI_NIDENT)
152 llvm_unreachable("Unexpected ELF object size");
153 std::pair<unsigned char, unsigned char> Ident = std::make_pair(
154 (uint8_t)Buffer->getBufferStart()[ELF::EI_CLASS],
155 (uint8_t)Buffer->getBufferStart()[ELF::EI_DATA]);
158 if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
159 DyldELFObject<support::little, false> *Obj =
160 new DyldELFObject<support::little, false>(Buffer->getMemBuffer(), ec);
161 return new ELFObjectImage<support::little, false>(Buffer, Obj);
163 else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
164 DyldELFObject<support::big, false> *Obj =
165 new DyldELFObject<support::big, false>(Buffer->getMemBuffer(), ec);
166 return new ELFObjectImage<support::big, false>(Buffer, Obj);
168 else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
169 DyldELFObject<support::big, true> *Obj =
170 new DyldELFObject<support::big, true>(Buffer->getMemBuffer(), ec);
171 return new ELFObjectImage<support::big, true>(Buffer, Obj);
173 else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
174 DyldELFObject<support::little, true> *Obj =
175 new DyldELFObject<support::little, true>(Buffer->getMemBuffer(), ec);
176 return new ELFObjectImage<support::little, true>(Buffer, Obj);
179 llvm_unreachable("Unexpected ELF format");
182 RuntimeDyldELF::~RuntimeDyldELF() {
185 void RuntimeDyldELF::resolveX86_64Relocation(uint8_t *LocalAddress,
186 uint64_t FinalAddress,
192 llvm_unreachable("Relocation type not implemented yet!");
194 case ELF::R_X86_64_64: {
195 uint64_t *Target = (uint64_t*)(LocalAddress);
196 *Target = Value + Addend;
199 case ELF::R_X86_64_32:
200 case ELF::R_X86_64_32S: {
202 assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
203 (Type == ELF::R_X86_64_32S &&
204 ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
205 uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
206 uint32_t *Target = reinterpret_cast<uint32_t*>(LocalAddress);
207 *Target = TruncatedAddr;
210 case ELF::R_X86_64_PC32: {
211 uint32_t *Placeholder = reinterpret_cast<uint32_t*>(LocalAddress);
212 int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
213 assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
214 int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
215 *Placeholder = TruncOffset;
221 void RuntimeDyldELF::resolveX86Relocation(uint8_t *LocalAddress,
222 uint32_t FinalAddress,
227 case ELF::R_386_32: {
228 uint32_t *Target = (uint32_t*)(LocalAddress);
229 uint32_t Placeholder = *Target;
230 *Target = Placeholder + Value + Addend;
233 case ELF::R_386_PC32: {
234 uint32_t *Placeholder = reinterpret_cast<uint32_t*>(LocalAddress);
235 uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
236 *Placeholder = RealOffset;
240 // There are other relocation types, but it appears these are the
241 // only ones currently used by the LLVM ELF object writer
242 llvm_unreachable("Relocation type not implemented yet!");
247 void RuntimeDyldELF::resolveARMRelocation(uint8_t *LocalAddress,
248 uint32_t FinalAddress,
252 // TODO: Add Thumb relocations.
253 uint32_t* TargetPtr = (uint32_t*)LocalAddress;
256 DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: " << LocalAddress
257 << " FinalAddress: " << format("%p",FinalAddress)
258 << " Value: " << format("%x",Value)
259 << " Type: " << format("%x",Type)
260 << " Addend: " << format("%x",Addend)
265 llvm_unreachable("Not implemented relocation type!");
267 // Just write 32bit value to relocation address
268 case ELF::R_ARM_ABS32 :
272 // Write first 16 bit of 32 bit value to the mov instruction.
273 // Last 4 bit should be shifted.
274 case ELF::R_ARM_MOVW_ABS_NC :
275 Value = Value & 0xFFFF;
276 *TargetPtr |= Value & 0xFFF;
277 *TargetPtr |= ((Value >> 12) & 0xF) << 16;
280 // Write last 16 bit of 32 bit value to the mov instruction.
281 // Last 4 bit should be shifted.
282 case ELF::R_ARM_MOVT_ABS :
283 Value = (Value >> 16) & 0xFFFF;
284 *TargetPtr |= Value & 0xFFF;
285 *TargetPtr |= ((Value >> 12) & 0xF) << 16;
288 // Write 24 bit relative value to the branch instruction.
289 case ELF::R_ARM_PC24 : // Fall through.
290 case ELF::R_ARM_CALL : // Fall through.
291 case ELF::R_ARM_JUMP24 :
292 int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
293 RelValue = (RelValue & 0x03FFFFFC) >> 2;
294 *TargetPtr &= 0xFF000000;
295 *TargetPtr |= RelValue;
300 void RuntimeDyldELF::resolveMIPSRelocation(uint8_t *LocalAddress,
301 uint32_t FinalAddress,
305 uint32_t* TargetPtr = (uint32_t*)LocalAddress;
308 DEBUG(dbgs() << "resolveMipselocation, LocalAddress: " << LocalAddress
309 << " FinalAddress: " << format("%p",FinalAddress)
310 << " Value: " << format("%x",Value)
311 << " Type: " << format("%x",Type)
312 << " Addend: " << format("%x",Addend)
317 llvm_unreachable("Not implemented relocation type!");
320 *TargetPtr = Value + (*TargetPtr);
323 *TargetPtr = ((*TargetPtr) & 0xfc000000) | (( Value & 0x0fffffff) >> 2);
325 case ELF::R_MIPS_HI16:
326 // Get the higher 16-bits. Also add 1 if bit 15 is 1.
327 Value += ((*TargetPtr) & 0x0000ffff) << 16;
328 *TargetPtr = ((*TargetPtr) & 0xffff0000) |
329 (((Value + 0x8000) >> 16) & 0xffff);
331 case ELF::R_MIPS_LO16:
332 Value += ((*TargetPtr) & 0x0000ffff);
333 *TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
338 void RuntimeDyldELF::resolveRelocation(uint8_t *LocalAddress,
339 uint64_t FinalAddress,
345 resolveX86_64Relocation(LocalAddress, FinalAddress, Value, Type, Addend);
348 resolveX86Relocation(LocalAddress, (uint32_t)(FinalAddress & 0xffffffffL),
349 (uint32_t)(Value & 0xffffffffL), Type,
350 (uint32_t)(Addend & 0xffffffffL));
352 case Triple::arm: // Fall through.
354 resolveARMRelocation(LocalAddress, (uint32_t)(FinalAddress & 0xffffffffL),
355 (uint32_t)(Value & 0xffffffffL), Type,
356 (uint32_t)(Addend & 0xffffffffL));
358 case Triple::mips: // Fall through.
360 resolveMIPSRelocation(LocalAddress, (uint32_t)(FinalAddress & 0xffffffffL),
361 (uint32_t)(Value & 0xffffffffL), Type,
362 (uint32_t)(Addend & 0xffffffffL));
364 default: llvm_unreachable("Unsupported CPU type!");
368 void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
370 ObjSectionToIDMap &ObjSectionToID,
371 const SymbolTableMap &Symbols,
374 uint32_t RelType = (uint32_t)(Rel.Type & 0xffffffffL);
375 intptr_t Addend = (intptr_t)Rel.AdditionalInfo;
376 const SymbolRef &Symbol = Rel.Symbol;
378 // Obtain the symbol name which is referenced in the relocation
379 StringRef TargetName;
380 Symbol.getName(TargetName);
381 DEBUG(dbgs() << "\t\tRelType: " << RelType
382 << " Addend: " << Addend
383 << " TargetName: " << TargetName
385 RelocationValueRef Value;
386 // First search for the symbol in the local symbol table
387 SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
388 if (lsi != Symbols.end()) {
389 Value.SectionID = lsi->second.first;
390 Value.Addend = lsi->second.second;
392 // Search for the symbol in the global symbol table
393 SymbolTableMap::const_iterator gsi =
394 GlobalSymbolTable.find(TargetName.data());
395 if (gsi != GlobalSymbolTable.end()) {
396 Value.SectionID = gsi->second.first;
397 Value.Addend = gsi->second.second;
399 SymbolRef::Type SymType;
400 Symbol.getType(SymType);
402 case SymbolRef::ST_Debug: {
403 // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
404 // and can be changed by another developers. Maybe best way is add
405 // a new symbol type ST_Section to SymbolRef and use it.
406 section_iterator si(Obj.end_sections());
407 Symbol.getSection(si);
408 if (si == Obj.end_sections())
409 llvm_unreachable("Symbol section not found, bad object file format!");
410 DEBUG(dbgs() << "\t\tThis is section symbol\n");
411 Value.SectionID = findOrEmitSection(Obj, (*si), true, ObjSectionToID);
412 Value.Addend = Addend;
415 case SymbolRef::ST_Unknown: {
416 Value.SymbolName = TargetName.data();
417 Value.Addend = Addend;
421 llvm_unreachable("Unresolved symbol type!");
426 DEBUG(dbgs() << "\t\tRel.SectionID: " << Rel.SectionID
427 << " Rel.Offset: " << Rel.Offset
429 if (Arch == Triple::arm &&
430 (RelType == ELF::R_ARM_PC24 ||
431 RelType == ELF::R_ARM_CALL ||
432 RelType == ELF::R_ARM_JUMP24)) {
433 // This is an ARM branch relocation, need to use a stub function.
434 DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
435 SectionEntry &Section = Sections[Rel.SectionID];
436 uint8_t *Target = Section.Address + Rel.Offset;
438 // Look up for existing stub.
439 StubMap::const_iterator i = Stubs.find(Value);
440 if (i != Stubs.end()) {
441 resolveRelocation(Target, (uint64_t)Target, (uint64_t)Section.Address +
442 i->second, RelType, 0);
443 DEBUG(dbgs() << " Stub function found\n");
445 // Create a new stub function.
446 DEBUG(dbgs() << " Create a new stub function\n");
447 Stubs[Value] = Section.StubOffset;
448 uint8_t *StubTargetAddr = createStubFunction(Section.Address +
450 RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
451 ELF::R_ARM_ABS32, Value.Addend);
452 if (Value.SymbolName)
453 addRelocationForSymbol(RE, Value.SymbolName);
455 addRelocationForSection(RE, Value.SectionID);
457 resolveRelocation(Target, (uint64_t)Target, (uint64_t)Section.Address +
458 Section.StubOffset, RelType, 0);
459 Section.StubOffset += getMaxStubSize();
461 } else if (Arch == Triple::mipsel && RelType == ELF::R_MIPS_26) {
462 // This is an Mips branch relocation, need to use a stub function.
463 DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
464 SectionEntry &Section = Sections[Rel.SectionID];
465 uint8_t *Target = Section.Address + Rel.Offset;
466 uint32_t *TargetAddress = (uint32_t *)Target;
468 // Extract the addend from the instruction.
469 uint32_t Addend = ((*TargetAddress) & 0x03ffffff) << 2;
471 Value.Addend += Addend;
473 // Look up for existing stub.
474 StubMap::const_iterator i = Stubs.find(Value);
475 if (i != Stubs.end()) {
476 resolveRelocation(Target, (uint64_t)Target,
477 (uint64_t)Section.Address +
478 i->second, RelType, 0);
479 DEBUG(dbgs() << " Stub function found\n");
481 // Create a new stub function.
482 DEBUG(dbgs() << " Create a new stub function\n");
483 Stubs[Value] = Section.StubOffset;
484 uint8_t *StubTargetAddr = createStubFunction(Section.Address +
487 // Creating Hi and Lo relocations for the filled stub instructions.
488 RelocationEntry REHi(Rel.SectionID,
489 StubTargetAddr - Section.Address,
490 ELF::R_MIPS_HI16, Value.Addend);
491 RelocationEntry RELo(Rel.SectionID,
492 StubTargetAddr - Section.Address + 4,
493 ELF::R_MIPS_LO16, Value.Addend);
495 if (Value.SymbolName) {
496 addRelocationForSymbol(REHi, Value.SymbolName);
497 addRelocationForSymbol(RELo, Value.SymbolName);
499 addRelocationForSection(REHi, Value.SectionID);
500 addRelocationForSection(RELo, Value.SectionID);
503 resolveRelocation(Target, (uint64_t)Target,
504 (uint64_t)Section.Address +
505 Section.StubOffset, RelType, 0);
506 Section.StubOffset += getMaxStubSize();
509 RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
510 if (Value.SymbolName)
511 addRelocationForSymbol(RE, Value.SymbolName);
513 addRelocationForSection(RE, Value.SectionID);
517 bool RuntimeDyldELF::isCompatibleFormat(const ObjectBuffer *Buffer) const {
518 if (Buffer->getBufferSize() < strlen(ELF::ElfMagic))
520 return (memcmp(Buffer->getBufferStart(), ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;