1 //===-- RuntimeDyldELF.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 ELF support for the MC-JIT runtime dynamic linker. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "RuntimeDyldELF.h" 15 #include "RuntimeDyldCheckerImpl.h" 16 #include "Targets/RuntimeDyldELFMips.h" 17 #include "llvm/ADT/IntervalMap.h" 18 #include "llvm/ADT/STLExtras.h" 19 #include "llvm/ADT/StringRef.h" 20 #include "llvm/ADT/Triple.h" 21 #include "llvm/BinaryFormat/ELF.h" 22 #include "llvm/MC/MCStreamer.h" 23 #include "llvm/Object/ELFObjectFile.h" 24 #include "llvm/Object/ObjectFile.h" 25 #include "llvm/Support/Endian.h" 26 #include "llvm/Support/MemoryBuffer.h" 27 28 using namespace llvm; 29 using namespace llvm::object; 30 using namespace llvm::support::endian; 31 32 #define DEBUG_TYPE "dyld" 33 34 static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); } 35 36 static void or32AArch64Imm(void *L, uint64_t Imm) { 37 or32le(L, (Imm & 0xFFF) << 10); 38 } 39 40 template <class T> static void write(bool isBE, void *P, T V) { 41 isBE ? write<T, support::big>(P, V) : write<T, support::little>(P, V); 42 } 43 44 static void write32AArch64Addr(void *L, uint64_t Imm) { 45 uint32_t ImmLo = (Imm & 0x3) << 29; 46 uint32_t ImmHi = (Imm & 0x1FFFFC) << 3; 47 uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3); 48 write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi); 49 } 50 51 // Return the bits [Start, End] from Val shifted Start bits. 52 // For instance, getBits(0xF0, 4, 8) returns 0xF. 53 static uint64_t getBits(uint64_t Val, int Start, int End) { 54 uint64_t Mask = ((uint64_t)1 << (End + 1 - Start)) - 1; 55 return (Val >> Start) & Mask; 56 } 57 58 namespace { 59 60 template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> { 61 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT) 62 63 typedef Elf_Shdr_Impl<ELFT> Elf_Shdr; 64 typedef Elf_Sym_Impl<ELFT> Elf_Sym; 65 typedef Elf_Rel_Impl<ELFT, false> Elf_Rel; 66 typedef Elf_Rel_Impl<ELFT, true> Elf_Rela; 67 68 typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr; 69 70 typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type; 71 72 public: 73 DyldELFObject(MemoryBufferRef Wrapper, std::error_code &ec); 74 75 void updateSectionAddress(const SectionRef &Sec, uint64_t Addr); 76 77 void updateSymbolAddress(const SymbolRef &SymRef, uint64_t Addr); 78 79 // Methods for type inquiry through isa, cast and dyn_cast 80 static bool classof(const Binary *v) { 81 return (isa<ELFObjectFile<ELFT>>(v) && 82 classof(cast<ELFObjectFile<ELFT>>(v))); 83 } 84 static bool classof(const ELFObjectFile<ELFT> *v) { 85 return v->isDyldType(); 86 } 87 }; 88 89 90 91 // The MemoryBuffer passed into this constructor is just a wrapper around the 92 // actual memory. Ultimately, the Binary parent class will take ownership of 93 // this MemoryBuffer object but not the underlying memory. 94 template <class ELFT> 95 DyldELFObject<ELFT>::DyldELFObject(MemoryBufferRef Wrapper, std::error_code &EC) 96 : ELFObjectFile<ELFT>(Wrapper, EC) { 97 this->isDyldELFObject = true; 98 } 99 100 template <class ELFT> 101 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec, 102 uint64_t Addr) { 103 DataRefImpl ShdrRef = Sec.getRawDataRefImpl(); 104 Elf_Shdr *shdr = 105 const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p)); 106 107 // This assumes the address passed in matches the target address bitness 108 // The template-based type cast handles everything else. 109 shdr->sh_addr = static_cast<addr_type>(Addr); 110 } 111 112 template <class ELFT> 113 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef, 114 uint64_t Addr) { 115 116 Elf_Sym *sym = const_cast<Elf_Sym *>( 117 ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl())); 118 119 // This assumes the address passed in matches the target address bitness 120 // The template-based type cast handles everything else. 121 sym->st_value = static_cast<addr_type>(Addr); 122 } 123 124 class LoadedELFObjectInfo final 125 : public LoadedObjectInfoHelper<LoadedELFObjectInfo, 126 RuntimeDyld::LoadedObjectInfo> { 127 public: 128 LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap) 129 : LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {} 130 131 OwningBinary<ObjectFile> 132 getObjectForDebug(const ObjectFile &Obj) const override; 133 }; 134 135 template <typename ELFT> 136 std::unique_ptr<DyldELFObject<ELFT>> 137 createRTDyldELFObject(MemoryBufferRef Buffer, 138 const ObjectFile &SourceObject, 139 const LoadedELFObjectInfo &L, 140 std::error_code &ec) { 141 typedef typename ELFFile<ELFT>::Elf_Shdr Elf_Shdr; 142 typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type; 143 144 std::unique_ptr<DyldELFObject<ELFT>> Obj = 145 llvm::make_unique<DyldELFObject<ELFT>>(Buffer, ec); 146 147 // Iterate over all sections in the object. 148 auto SI = SourceObject.section_begin(); 149 for (const auto &Sec : Obj->sections()) { 150 StringRef SectionName; 151 Sec.getName(SectionName); 152 if (SectionName != "") { 153 DataRefImpl ShdrRef = Sec.getRawDataRefImpl(); 154 Elf_Shdr *shdr = const_cast<Elf_Shdr *>( 155 reinterpret_cast<const Elf_Shdr *>(ShdrRef.p)); 156 157 if (uint64_t SecLoadAddr = L.getSectionLoadAddress(*SI)) { 158 // This assumes that the address passed in matches the target address 159 // bitness. The template-based type cast handles everything else. 160 shdr->sh_addr = static_cast<addr_type>(SecLoadAddr); 161 } 162 } 163 ++SI; 164 } 165 166 return Obj; 167 } 168 169 OwningBinary<ObjectFile> createELFDebugObject(const ObjectFile &Obj, 170 const LoadedELFObjectInfo &L) { 171 assert(Obj.isELF() && "Not an ELF object file."); 172 173 std::unique_ptr<MemoryBuffer> Buffer = 174 MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName()); 175 176 std::error_code ec; 177 178 std::unique_ptr<ObjectFile> DebugObj; 179 if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian()) { 180 typedef ELFType<support::little, false> ELF32LE; 181 DebugObj = createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), Obj, L, 182 ec); 183 } else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian()) { 184 typedef ELFType<support::big, false> ELF32BE; 185 DebugObj = createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), Obj, L, 186 ec); 187 } else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian()) { 188 typedef ELFType<support::big, true> ELF64BE; 189 DebugObj = createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), Obj, L, 190 ec); 191 } else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian()) { 192 typedef ELFType<support::little, true> ELF64LE; 193 DebugObj = createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), Obj, L, 194 ec); 195 } else 196 llvm_unreachable("Unexpected ELF format"); 197 198 assert(!ec && "Could not construct copy ELF object file"); 199 200 return OwningBinary<ObjectFile>(std::move(DebugObj), std::move(Buffer)); 201 } 202 203 OwningBinary<ObjectFile> 204 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const { 205 return createELFDebugObject(Obj, *this); 206 } 207 208 } // anonymous namespace 209 210 namespace llvm { 211 212 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr, 213 JITSymbolResolver &Resolver) 214 : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {} 215 RuntimeDyldELF::~RuntimeDyldELF() {} 216 217 void RuntimeDyldELF::registerEHFrames() { 218 for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) { 219 SID EHFrameSID = UnregisteredEHFrameSections[i]; 220 uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress(); 221 uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress(); 222 size_t EHFrameSize = Sections[EHFrameSID].getSize(); 223 MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize); 224 } 225 UnregisteredEHFrameSections.clear(); 226 } 227 228 std::unique_ptr<RuntimeDyldELF> 229 llvm::RuntimeDyldELF::create(Triple::ArchType Arch, 230 RuntimeDyld::MemoryManager &MemMgr, 231 JITSymbolResolver &Resolver) { 232 switch (Arch) { 233 default: 234 return make_unique<RuntimeDyldELF>(MemMgr, Resolver); 235 case Triple::mips: 236 case Triple::mipsel: 237 case Triple::mips64: 238 case Triple::mips64el: 239 return make_unique<RuntimeDyldELFMips>(MemMgr, Resolver); 240 } 241 } 242 243 std::unique_ptr<RuntimeDyld::LoadedObjectInfo> 244 RuntimeDyldELF::loadObject(const object::ObjectFile &O) { 245 if (auto ObjSectionToIDOrErr = loadObjectImpl(O)) 246 return llvm::make_unique<LoadedELFObjectInfo>(*this, *ObjSectionToIDOrErr); 247 else { 248 HasError = true; 249 raw_string_ostream ErrStream(ErrorStr); 250 logAllUnhandledErrors(ObjSectionToIDOrErr.takeError(), ErrStream, ""); 251 return nullptr; 252 } 253 } 254 255 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section, 256 uint64_t Offset, uint64_t Value, 257 uint32_t Type, int64_t Addend, 258 uint64_t SymOffset) { 259 switch (Type) { 260 default: 261 llvm_unreachable("Relocation type not implemented yet!"); 262 break; 263 case ELF::R_X86_64_NONE: 264 break; 265 case ELF::R_X86_64_64: { 266 support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) = 267 Value + Addend; 268 DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at " 269 << format("%p\n", Section.getAddressWithOffset(Offset))); 270 break; 271 } 272 case ELF::R_X86_64_32: 273 case ELF::R_X86_64_32S: { 274 Value += Addend; 275 assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) || 276 (Type == ELF::R_X86_64_32S && 277 ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN))); 278 uint32_t TruncatedAddr = (Value & 0xFFFFFFFF); 279 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) = 280 TruncatedAddr; 281 DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at " 282 << format("%p\n", Section.getAddressWithOffset(Offset))); 283 break; 284 } 285 case ELF::R_X86_64_PC8: { 286 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 287 int64_t RealOffset = Value + Addend - FinalAddress; 288 assert(isInt<8>(RealOffset)); 289 int8_t TruncOffset = (RealOffset & 0xFF); 290 Section.getAddress()[Offset] = TruncOffset; 291 break; 292 } 293 case ELF::R_X86_64_PC32: { 294 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 295 int64_t RealOffset = Value + Addend - FinalAddress; 296 assert(isInt<32>(RealOffset)); 297 int32_t TruncOffset = (RealOffset & 0xFFFFFFFF); 298 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) = 299 TruncOffset; 300 break; 301 } 302 case ELF::R_X86_64_PC64: { 303 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 304 int64_t RealOffset = Value + Addend - FinalAddress; 305 support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) = 306 RealOffset; 307 break; 308 } 309 } 310 } 311 312 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section, 313 uint64_t Offset, uint32_t Value, 314 uint32_t Type, int32_t Addend) { 315 switch (Type) { 316 case ELF::R_386_32: { 317 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) = 318 Value + Addend; 319 break; 320 } 321 case ELF::R_386_PC32: { 322 uint32_t FinalAddress = 323 Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF; 324 uint32_t RealOffset = Value + Addend - FinalAddress; 325 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) = 326 RealOffset; 327 break; 328 } 329 default: 330 // There are other relocation types, but it appears these are the 331 // only ones currently used by the LLVM ELF object writer 332 llvm_unreachable("Relocation type not implemented yet!"); 333 break; 334 } 335 } 336 337 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section, 338 uint64_t Offset, uint64_t Value, 339 uint32_t Type, int64_t Addend) { 340 uint32_t *TargetPtr = 341 reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset)); 342 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 343 // Data should use target endian. Code should always use little endian. 344 bool isBE = Arch == Triple::aarch64_be; 345 346 DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x" 347 << format("%llx", Section.getAddressWithOffset(Offset)) 348 << " FinalAddress: 0x" << format("%llx", FinalAddress) 349 << " Value: 0x" << format("%llx", Value) << " Type: 0x" 350 << format("%x", Type) << " Addend: 0x" << format("%llx", Addend) 351 << "\n"); 352 353 switch (Type) { 354 default: 355 llvm_unreachable("Relocation type not implemented yet!"); 356 break; 357 case ELF::R_AARCH64_ABS16: { 358 uint64_t Result = Value + Addend; 359 assert(static_cast<int64_t>(Result) >= INT16_MIN && Result < UINT16_MAX); 360 write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU)); 361 break; 362 } 363 case ELF::R_AARCH64_ABS32: { 364 uint64_t Result = Value + Addend; 365 assert(static_cast<int64_t>(Result) >= INT32_MIN && Result < UINT32_MAX); 366 write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU)); 367 break; 368 } 369 case ELF::R_AARCH64_ABS64: 370 write(isBE, TargetPtr, Value + Addend); 371 break; 372 case ELF::R_AARCH64_PREL32: { 373 uint64_t Result = Value + Addend - FinalAddress; 374 assert(static_cast<int64_t>(Result) >= INT32_MIN && 375 static_cast<int64_t>(Result) <= UINT32_MAX); 376 write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU)); 377 break; 378 } 379 case ELF::R_AARCH64_PREL64: 380 write(isBE, TargetPtr, Value + Addend - FinalAddress); 381 break; 382 case ELF::R_AARCH64_CALL26: // fallthrough 383 case ELF::R_AARCH64_JUMP26: { 384 // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the 385 // calculation. 386 uint64_t BranchImm = Value + Addend - FinalAddress; 387 388 // "Check that -2^27 <= result < 2^27". 389 assert(isInt<28>(BranchImm)); 390 or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) >> 2); 391 break; 392 } 393 case ELF::R_AARCH64_MOVW_UABS_G3: 394 or32le(TargetPtr, ((Value + Addend) & 0xFFFF000000000000) >> 43); 395 break; 396 case ELF::R_AARCH64_MOVW_UABS_G2_NC: 397 or32le(TargetPtr, ((Value + Addend) & 0xFFFF00000000) >> 27); 398 break; 399 case ELF::R_AARCH64_MOVW_UABS_G1_NC: 400 or32le(TargetPtr, ((Value + Addend) & 0xFFFF0000) >> 11); 401 break; 402 case ELF::R_AARCH64_MOVW_UABS_G0_NC: 403 or32le(TargetPtr, ((Value + Addend) & 0xFFFF) << 5); 404 break; 405 case ELF::R_AARCH64_ADR_PREL_PG_HI21: { 406 // Operation: Page(S+A) - Page(P) 407 uint64_t Result = 408 ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL); 409 410 // Check that -2^32 <= X < 2^32 411 assert(isInt<33>(Result) && "overflow check failed for relocation"); 412 413 // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken 414 // from bits 32:12 of X. 415 write32AArch64Addr(TargetPtr, Result >> 12); 416 break; 417 } 418 case ELF::R_AARCH64_ADD_ABS_LO12_NC: 419 // Operation: S + A 420 // Immediate goes in bits 21:10 of LD/ST instruction, taken 421 // from bits 11:0 of X 422 or32AArch64Imm(TargetPtr, Value + Addend); 423 break; 424 case ELF::R_AARCH64_LDST8_ABS_LO12_NC: 425 // Operation: S + A 426 // Immediate goes in bits 21:10 of LD/ST instruction, taken 427 // from bits 11:0 of X 428 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 0, 11)); 429 break; 430 case ELF::R_AARCH64_LDST16_ABS_LO12_NC: 431 // Operation: S + A 432 // Immediate goes in bits 21:10 of LD/ST instruction, taken 433 // from bits 11:1 of X 434 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 1, 11)); 435 break; 436 case ELF::R_AARCH64_LDST32_ABS_LO12_NC: 437 // Operation: S + A 438 // Immediate goes in bits 21:10 of LD/ST instruction, taken 439 // from bits 11:2 of X 440 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 2, 11)); 441 break; 442 case ELF::R_AARCH64_LDST64_ABS_LO12_NC: 443 // Operation: S + A 444 // Immediate goes in bits 21:10 of LD/ST instruction, taken 445 // from bits 11:3 of X 446 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 3, 11)); 447 break; 448 case ELF::R_AARCH64_LDST128_ABS_LO12_NC: 449 // Operation: S + A 450 // Immediate goes in bits 21:10 of LD/ST instruction, taken 451 // from bits 11:4 of X 452 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 4, 11)); 453 break; 454 } 455 } 456 457 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section, 458 uint64_t Offset, uint32_t Value, 459 uint32_t Type, int32_t Addend) { 460 // TODO: Add Thumb relocations. 461 uint32_t *TargetPtr = 462 reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset)); 463 uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF; 464 Value += Addend; 465 466 DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: " 467 << Section.getAddressWithOffset(Offset) 468 << " FinalAddress: " << format("%p", FinalAddress) << " Value: " 469 << format("%x", Value) << " Type: " << format("%x", Type) 470 << " Addend: " << format("%x", Addend) << "\n"); 471 472 switch (Type) { 473 default: 474 llvm_unreachable("Not implemented relocation type!"); 475 476 case ELF::R_ARM_NONE: 477 break; 478 // Write a 31bit signed offset 479 case ELF::R_ARM_PREL31: 480 support::ulittle32_t::ref{TargetPtr} = 481 (support::ulittle32_t::ref{TargetPtr} & 0x80000000) | 482 ((Value - FinalAddress) & ~0x80000000); 483 break; 484 case ELF::R_ARM_TARGET1: 485 case ELF::R_ARM_ABS32: 486 support::ulittle32_t::ref{TargetPtr} = Value; 487 break; 488 // Write first 16 bit of 32 bit value to the mov instruction. 489 // Last 4 bit should be shifted. 490 case ELF::R_ARM_MOVW_ABS_NC: 491 case ELF::R_ARM_MOVT_ABS: 492 if (Type == ELF::R_ARM_MOVW_ABS_NC) 493 Value = Value & 0xFFFF; 494 else if (Type == ELF::R_ARM_MOVT_ABS) 495 Value = (Value >> 16) & 0xFFFF; 496 support::ulittle32_t::ref{TargetPtr} = 497 (support::ulittle32_t::ref{TargetPtr} & ~0x000F0FFF) | (Value & 0xFFF) | 498 (((Value >> 12) & 0xF) << 16); 499 break; 500 // Write 24 bit relative value to the branch instruction. 501 case ELF::R_ARM_PC24: // Fall through. 502 case ELF::R_ARM_CALL: // Fall through. 503 case ELF::R_ARM_JUMP24: 504 int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8); 505 RelValue = (RelValue & 0x03FFFFFC) >> 2; 506 assert((support::ulittle32_t::ref{TargetPtr} & 0xFFFFFF) == 0xFFFFFE); 507 support::ulittle32_t::ref{TargetPtr} = 508 (support::ulittle32_t::ref{TargetPtr} & 0xFF000000) | RelValue; 509 break; 510 } 511 } 512 513 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) { 514 if (Arch == Triple::UnknownArch || 515 !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) { 516 IsMipsO32ABI = false; 517 IsMipsN32ABI = false; 518 IsMipsN64ABI = false; 519 return; 520 } 521 unsigned AbiVariant; 522 Obj.getPlatformFlags(AbiVariant); 523 IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32; 524 IsMipsN32ABI = AbiVariant & ELF::EF_MIPS_ABI2; 525 IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips"); 526 } 527 528 // Return the .TOC. section and offset. 529 Error RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj, 530 ObjSectionToIDMap &LocalSections, 531 RelocationValueRef &Rel) { 532 // Set a default SectionID in case we do not find a TOC section below. 533 // This may happen for references to TOC base base (sym@toc, .odp 534 // relocation) without a .toc directive. In this case just use the 535 // first section (which is usually the .odp) since the code won't 536 // reference the .toc base directly. 537 Rel.SymbolName = nullptr; 538 Rel.SectionID = 0; 539 540 // The TOC consists of sections .got, .toc, .tocbss, .plt in that 541 // order. The TOC starts where the first of these sections starts. 542 for (auto &Section: Obj.sections()) { 543 StringRef SectionName; 544 if (auto EC = Section.getName(SectionName)) 545 return errorCodeToError(EC); 546 547 if (SectionName == ".got" 548 || SectionName == ".toc" 549 || SectionName == ".tocbss" 550 || SectionName == ".plt") { 551 if (auto SectionIDOrErr = 552 findOrEmitSection(Obj, Section, false, LocalSections)) 553 Rel.SectionID = *SectionIDOrErr; 554 else 555 return SectionIDOrErr.takeError(); 556 break; 557 } 558 } 559 560 // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000 561 // thus permitting a full 64 Kbytes segment. 562 Rel.Addend = 0x8000; 563 564 return Error::success(); 565 } 566 567 // Returns the sections and offset associated with the ODP entry referenced 568 // by Symbol. 569 Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj, 570 ObjSectionToIDMap &LocalSections, 571 RelocationValueRef &Rel) { 572 // Get the ELF symbol value (st_value) to compare with Relocation offset in 573 // .opd entries 574 for (section_iterator si = Obj.section_begin(), se = Obj.section_end(); 575 si != se; ++si) { 576 section_iterator RelSecI = si->getRelocatedSection(); 577 if (RelSecI == Obj.section_end()) 578 continue; 579 580 StringRef RelSectionName; 581 if (auto EC = RelSecI->getName(RelSectionName)) 582 return errorCodeToError(EC); 583 584 if (RelSectionName != ".opd") 585 continue; 586 587 for (elf_relocation_iterator i = si->relocation_begin(), 588 e = si->relocation_end(); 589 i != e;) { 590 // The R_PPC64_ADDR64 relocation indicates the first field 591 // of a .opd entry 592 uint64_t TypeFunc = i->getType(); 593 if (TypeFunc != ELF::R_PPC64_ADDR64) { 594 ++i; 595 continue; 596 } 597 598 uint64_t TargetSymbolOffset = i->getOffset(); 599 symbol_iterator TargetSymbol = i->getSymbol(); 600 int64_t Addend; 601 if (auto AddendOrErr = i->getAddend()) 602 Addend = *AddendOrErr; 603 else 604 return errorCodeToError(AddendOrErr.getError()); 605 606 ++i; 607 if (i == e) 608 break; 609 610 // Just check if following relocation is a R_PPC64_TOC 611 uint64_t TypeTOC = i->getType(); 612 if (TypeTOC != ELF::R_PPC64_TOC) 613 continue; 614 615 // Finally compares the Symbol value and the target symbol offset 616 // to check if this .opd entry refers to the symbol the relocation 617 // points to. 618 if (Rel.Addend != (int64_t)TargetSymbolOffset) 619 continue; 620 621 section_iterator TSI = Obj.section_end(); 622 if (auto TSIOrErr = TargetSymbol->getSection()) 623 TSI = *TSIOrErr; 624 else 625 return TSIOrErr.takeError(); 626 assert(TSI != Obj.section_end() && "TSI should refer to a valid section"); 627 628 bool IsCode = TSI->isText(); 629 if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode, 630 LocalSections)) 631 Rel.SectionID = *SectionIDOrErr; 632 else 633 return SectionIDOrErr.takeError(); 634 Rel.Addend = (intptr_t)Addend; 635 return Error::success(); 636 } 637 } 638 llvm_unreachable("Attempting to get address of ODP entry!"); 639 } 640 641 // Relocation masks following the #lo(value), #hi(value), #ha(value), 642 // #higher(value), #highera(value), #highest(value), and #highesta(value) 643 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi 644 // document. 645 646 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; } 647 648 static inline uint16_t applyPPChi(uint64_t value) { 649 return (value >> 16) & 0xffff; 650 } 651 652 static inline uint16_t applyPPCha (uint64_t value) { 653 return ((value + 0x8000) >> 16) & 0xffff; 654 } 655 656 static inline uint16_t applyPPChigher(uint64_t value) { 657 return (value >> 32) & 0xffff; 658 } 659 660 static inline uint16_t applyPPChighera (uint64_t value) { 661 return ((value + 0x8000) >> 32) & 0xffff; 662 } 663 664 static inline uint16_t applyPPChighest(uint64_t value) { 665 return (value >> 48) & 0xffff; 666 } 667 668 static inline uint16_t applyPPChighesta (uint64_t value) { 669 return ((value + 0x8000) >> 48) & 0xffff; 670 } 671 672 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section, 673 uint64_t Offset, uint64_t Value, 674 uint32_t Type, int64_t Addend) { 675 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset); 676 switch (Type) { 677 default: 678 llvm_unreachable("Relocation type not implemented yet!"); 679 break; 680 case ELF::R_PPC_ADDR16_LO: 681 writeInt16BE(LocalAddress, applyPPClo(Value + Addend)); 682 break; 683 case ELF::R_PPC_ADDR16_HI: 684 writeInt16BE(LocalAddress, applyPPChi(Value + Addend)); 685 break; 686 case ELF::R_PPC_ADDR16_HA: 687 writeInt16BE(LocalAddress, applyPPCha(Value + Addend)); 688 break; 689 } 690 } 691 692 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section, 693 uint64_t Offset, uint64_t Value, 694 uint32_t Type, int64_t Addend) { 695 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset); 696 switch (Type) { 697 default: 698 llvm_unreachable("Relocation type not implemented yet!"); 699 break; 700 case ELF::R_PPC64_ADDR16: 701 writeInt16BE(LocalAddress, applyPPClo(Value + Addend)); 702 break; 703 case ELF::R_PPC64_ADDR16_DS: 704 writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3); 705 break; 706 case ELF::R_PPC64_ADDR16_LO: 707 writeInt16BE(LocalAddress, applyPPClo(Value + Addend)); 708 break; 709 case ELF::R_PPC64_ADDR16_LO_DS: 710 writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3); 711 break; 712 case ELF::R_PPC64_ADDR16_HI: 713 writeInt16BE(LocalAddress, applyPPChi(Value + Addend)); 714 break; 715 case ELF::R_PPC64_ADDR16_HA: 716 writeInt16BE(LocalAddress, applyPPCha(Value + Addend)); 717 break; 718 case ELF::R_PPC64_ADDR16_HIGHER: 719 writeInt16BE(LocalAddress, applyPPChigher(Value + Addend)); 720 break; 721 case ELF::R_PPC64_ADDR16_HIGHERA: 722 writeInt16BE(LocalAddress, applyPPChighera(Value + Addend)); 723 break; 724 case ELF::R_PPC64_ADDR16_HIGHEST: 725 writeInt16BE(LocalAddress, applyPPChighest(Value + Addend)); 726 break; 727 case ELF::R_PPC64_ADDR16_HIGHESTA: 728 writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend)); 729 break; 730 case ELF::R_PPC64_ADDR14: { 731 assert(((Value + Addend) & 3) == 0); 732 // Preserve the AA/LK bits in the branch instruction 733 uint8_t aalk = *(LocalAddress + 3); 734 writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc)); 735 } break; 736 case ELF::R_PPC64_REL16_LO: { 737 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 738 uint64_t Delta = Value - FinalAddress + Addend; 739 writeInt16BE(LocalAddress, applyPPClo(Delta)); 740 } break; 741 case ELF::R_PPC64_REL16_HI: { 742 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 743 uint64_t Delta = Value - FinalAddress + Addend; 744 writeInt16BE(LocalAddress, applyPPChi(Delta)); 745 } break; 746 case ELF::R_PPC64_REL16_HA: { 747 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 748 uint64_t Delta = Value - FinalAddress + Addend; 749 writeInt16BE(LocalAddress, applyPPCha(Delta)); 750 } break; 751 case ELF::R_PPC64_ADDR32: { 752 int64_t Result = static_cast<int64_t>(Value + Addend); 753 if (SignExtend64<32>(Result) != Result) 754 llvm_unreachable("Relocation R_PPC64_ADDR32 overflow"); 755 writeInt32BE(LocalAddress, Result); 756 } break; 757 case ELF::R_PPC64_REL24: { 758 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 759 int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend); 760 if (SignExtend64<26>(delta) != delta) 761 llvm_unreachable("Relocation R_PPC64_REL24 overflow"); 762 // Generates a 'bl <address>' instruction 763 writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC)); 764 } break; 765 case ELF::R_PPC64_REL32: { 766 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 767 int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend); 768 if (SignExtend64<32>(delta) != delta) 769 llvm_unreachable("Relocation R_PPC64_REL32 overflow"); 770 writeInt32BE(LocalAddress, delta); 771 } break; 772 case ELF::R_PPC64_REL64: { 773 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset); 774 uint64_t Delta = Value - FinalAddress + Addend; 775 writeInt64BE(LocalAddress, Delta); 776 } break; 777 case ELF::R_PPC64_ADDR64: 778 writeInt64BE(LocalAddress, Value + Addend); 779 break; 780 } 781 } 782 783 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section, 784 uint64_t Offset, uint64_t Value, 785 uint32_t Type, int64_t Addend) { 786 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset); 787 switch (Type) { 788 default: 789 llvm_unreachable("Relocation type not implemented yet!"); 790 break; 791 case ELF::R_390_PC16DBL: 792 case ELF::R_390_PLT16DBL: { 793 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset); 794 assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow"); 795 writeInt16BE(LocalAddress, Delta / 2); 796 break; 797 } 798 case ELF::R_390_PC32DBL: 799 case ELF::R_390_PLT32DBL: { 800 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset); 801 assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow"); 802 writeInt32BE(LocalAddress, Delta / 2); 803 break; 804 } 805 case ELF::R_390_PC16: { 806 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset); 807 assert(int16_t(Delta) == Delta && "R_390_PC16 overflow"); 808 writeInt16BE(LocalAddress, Delta); 809 break; 810 } 811 case ELF::R_390_PC32: { 812 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset); 813 assert(int32_t(Delta) == Delta && "R_390_PC32 overflow"); 814 writeInt32BE(LocalAddress, Delta); 815 break; 816 } 817 case ELF::R_390_PC64: { 818 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset); 819 writeInt64BE(LocalAddress, Delta); 820 break; 821 } 822 case ELF::R_390_8: 823 *LocalAddress = (uint8_t)(Value + Addend); 824 break; 825 case ELF::R_390_16: 826 writeInt16BE(LocalAddress, Value + Addend); 827 break; 828 case ELF::R_390_32: 829 writeInt32BE(LocalAddress, Value + Addend); 830 break; 831 case ELF::R_390_64: 832 writeInt64BE(LocalAddress, Value + Addend); 833 break; 834 } 835 } 836 837 void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section, 838 uint64_t Offset, uint64_t Value, 839 uint32_t Type, int64_t Addend) { 840 bool isBE = Arch == Triple::bpfeb; 841 842 switch (Type) { 843 default: 844 llvm_unreachable("Relocation type not implemented yet!"); 845 break; 846 case ELF::R_BPF_NONE: 847 break; 848 case ELF::R_BPF_64_64: { 849 write(isBE, Section.getAddressWithOffset(Offset), Value + Addend); 850 DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at " 851 << format("%p\n", Section.getAddressWithOffset(Offset))); 852 break; 853 } 854 case ELF::R_BPF_64_32: { 855 Value += Addend; 856 assert(Value <= UINT32_MAX); 857 write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value)); 858 DEBUG(dbgs() << "Writing " << format("%p", Value) << " at " 859 << format("%p\n", Section.getAddressWithOffset(Offset))); 860 break; 861 } 862 } 863 } 864 865 // The target location for the relocation is described by RE.SectionID and 866 // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each 867 // SectionEntry has three members describing its location. 868 // SectionEntry::Address is the address at which the section has been loaded 869 // into memory in the current (host) process. SectionEntry::LoadAddress is the 870 // address that the section will have in the target process. 871 // SectionEntry::ObjAddress is the address of the bits for this section in the 872 // original emitted object image (also in the current address space). 873 // 874 // Relocations will be applied as if the section were loaded at 875 // SectionEntry::LoadAddress, but they will be applied at an address based 876 // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer to 877 // Target memory contents if they are required for value calculations. 878 // 879 // The Value parameter here is the load address of the symbol for the 880 // relocation to be applied. For relocations which refer to symbols in the 881 // current object Value will be the LoadAddress of the section in which 882 // the symbol resides (RE.Addend provides additional information about the 883 // symbol location). For external symbols, Value will be the address of the 884 // symbol in the target address space. 885 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE, 886 uint64_t Value) { 887 const SectionEntry &Section = Sections[RE.SectionID]; 888 return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend, 889 RE.SymOffset, RE.SectionID); 890 } 891 892 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section, 893 uint64_t Offset, uint64_t Value, 894 uint32_t Type, int64_t Addend, 895 uint64_t SymOffset, SID SectionID) { 896 switch (Arch) { 897 case Triple::x86_64: 898 resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset); 899 break; 900 case Triple::x86: 901 resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type, 902 (uint32_t)(Addend & 0xffffffffL)); 903 break; 904 case Triple::aarch64: 905 case Triple::aarch64_be: 906 resolveAArch64Relocation(Section, Offset, Value, Type, Addend); 907 break; 908 case Triple::arm: // Fall through. 909 case Triple::armeb: 910 case Triple::thumb: 911 case Triple::thumbeb: 912 resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type, 913 (uint32_t)(Addend & 0xffffffffL)); 914 break; 915 case Triple::ppc: 916 resolvePPC32Relocation(Section, Offset, Value, Type, Addend); 917 break; 918 case Triple::ppc64: // Fall through. 919 case Triple::ppc64le: 920 resolvePPC64Relocation(Section, Offset, Value, Type, Addend); 921 break; 922 case Triple::systemz: 923 resolveSystemZRelocation(Section, Offset, Value, Type, Addend); 924 break; 925 case Triple::bpfel: 926 case Triple::bpfeb: 927 resolveBPFRelocation(Section, Offset, Value, Type, Addend); 928 break; 929 default: 930 llvm_unreachable("Unsupported CPU type!"); 931 } 932 } 933 934 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const { 935 return (void *)(Sections[SectionID].getObjAddress() + Offset); 936 } 937 938 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) { 939 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset); 940 if (Value.SymbolName) 941 addRelocationForSymbol(RE, Value.SymbolName); 942 else 943 addRelocationForSection(RE, Value.SectionID); 944 } 945 946 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType, 947 bool IsLocal) const { 948 switch (RelType) { 949 case ELF::R_MICROMIPS_GOT16: 950 if (IsLocal) 951 return ELF::R_MICROMIPS_LO16; 952 break; 953 case ELF::R_MICROMIPS_HI16: 954 return ELF::R_MICROMIPS_LO16; 955 case ELF::R_MIPS_GOT16: 956 if (IsLocal) 957 return ELF::R_MIPS_LO16; 958 break; 959 case ELF::R_MIPS_HI16: 960 return ELF::R_MIPS_LO16; 961 case ELF::R_MIPS_PCHI16: 962 return ELF::R_MIPS_PCLO16; 963 default: 964 break; 965 } 966 return ELF::R_MIPS_NONE; 967 } 968 969 // Sometimes we don't need to create thunk for a branch. 970 // This typically happens when branch target is located 971 // in the same object file. In such case target is either 972 // a weak symbol or symbol in a different executable section. 973 // This function checks if branch target is located in the 974 // same object file and if distance between source and target 975 // fits R_AARCH64_CALL26 relocation. If both conditions are 976 // met, it emits direct jump to the target and returns true. 977 // Otherwise false is returned and thunk is created. 978 bool RuntimeDyldELF::resolveAArch64ShortBranch( 979 unsigned SectionID, relocation_iterator RelI, 980 const RelocationValueRef &Value) { 981 uint64_t Address; 982 if (Value.SymbolName) { 983 auto Loc = GlobalSymbolTable.find(Value.SymbolName); 984 985 // Don't create direct branch for external symbols. 986 if (Loc == GlobalSymbolTable.end()) 987 return false; 988 989 const auto &SymInfo = Loc->second; 990 Address = 991 uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset( 992 SymInfo.getOffset())); 993 } else { 994 Address = uint64_t(Sections[Value.SectionID].getLoadAddress()); 995 } 996 uint64_t Offset = RelI->getOffset(); 997 uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset); 998 999 // R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27 1000 // If distance between source and target is out of range then we should 1001 // create thunk. 1002 if (!isInt<28>(Address + Value.Addend - SourceAddress)) 1003 return false; 1004 1005 resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(), 1006 Value.Addend); 1007 1008 return true; 1009 } 1010 1011 void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID, 1012 const RelocationValueRef &Value, 1013 relocation_iterator RelI, 1014 StubMap &Stubs) { 1015 1016 DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation."); 1017 SectionEntry &Section = Sections[SectionID]; 1018 1019 uint64_t Offset = RelI->getOffset(); 1020 unsigned RelType = RelI->getType(); 1021 // Look for an existing stub. 1022 StubMap::const_iterator i = Stubs.find(Value); 1023 if (i != Stubs.end()) { 1024 resolveRelocation(Section, Offset, 1025 (uint64_t)Section.getAddressWithOffset(i->second), 1026 RelType, 0); 1027 DEBUG(dbgs() << " Stub function found\n"); 1028 } else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) { 1029 // Create a new stub function. 1030 DEBUG(dbgs() << " Create a new stub function\n"); 1031 Stubs[Value] = Section.getStubOffset(); 1032 uint8_t *StubTargetAddr = createStubFunction( 1033 Section.getAddressWithOffset(Section.getStubOffset())); 1034 1035 RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(), 1036 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend); 1037 RelocationEntry REmovk_g2(SectionID, 1038 StubTargetAddr - Section.getAddress() + 4, 1039 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend); 1040 RelocationEntry REmovk_g1(SectionID, 1041 StubTargetAddr - Section.getAddress() + 8, 1042 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend); 1043 RelocationEntry REmovk_g0(SectionID, 1044 StubTargetAddr - Section.getAddress() + 12, 1045 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend); 1046 1047 if (Value.SymbolName) { 1048 addRelocationForSymbol(REmovz_g3, Value.SymbolName); 1049 addRelocationForSymbol(REmovk_g2, Value.SymbolName); 1050 addRelocationForSymbol(REmovk_g1, Value.SymbolName); 1051 addRelocationForSymbol(REmovk_g0, Value.SymbolName); 1052 } else { 1053 addRelocationForSection(REmovz_g3, Value.SectionID); 1054 addRelocationForSection(REmovk_g2, Value.SectionID); 1055 addRelocationForSection(REmovk_g1, Value.SectionID); 1056 addRelocationForSection(REmovk_g0, Value.SectionID); 1057 } 1058 resolveRelocation(Section, Offset, 1059 reinterpret_cast<uint64_t>(Section.getAddressWithOffset( 1060 Section.getStubOffset())), 1061 RelType, 0); 1062 Section.advanceStubOffset(getMaxStubSize()); 1063 } 1064 } 1065 1066 Expected<relocation_iterator> 1067 RuntimeDyldELF::processRelocationRef( 1068 unsigned SectionID, relocation_iterator RelI, const ObjectFile &O, 1069 ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) { 1070 const auto &Obj = cast<ELFObjectFileBase>(O); 1071 uint64_t RelType = RelI->getType(); 1072 ErrorOr<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend(); 1073 int64_t Addend = AddendOrErr ? *AddendOrErr : 0; 1074 elf_symbol_iterator Symbol = RelI->getSymbol(); 1075 1076 // Obtain the symbol name which is referenced in the relocation 1077 StringRef TargetName; 1078 if (Symbol != Obj.symbol_end()) { 1079 if (auto TargetNameOrErr = Symbol->getName()) 1080 TargetName = *TargetNameOrErr; 1081 else 1082 return TargetNameOrErr.takeError(); 1083 } 1084 DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend 1085 << " TargetName: " << TargetName << "\n"); 1086 RelocationValueRef Value; 1087 // First search for the symbol in the local symbol table 1088 SymbolRef::Type SymType = SymbolRef::ST_Unknown; 1089 1090 // Search for the symbol in the global symbol table 1091 RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end(); 1092 if (Symbol != Obj.symbol_end()) { 1093 gsi = GlobalSymbolTable.find(TargetName.data()); 1094 Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType(); 1095 if (!SymTypeOrErr) { 1096 std::string Buf; 1097 raw_string_ostream OS(Buf); 1098 logAllUnhandledErrors(SymTypeOrErr.takeError(), OS, ""); 1099 OS.flush(); 1100 report_fatal_error(Buf); 1101 } 1102 SymType = *SymTypeOrErr; 1103 } 1104 if (gsi != GlobalSymbolTable.end()) { 1105 const auto &SymInfo = gsi->second; 1106 Value.SectionID = SymInfo.getSectionID(); 1107 Value.Offset = SymInfo.getOffset(); 1108 Value.Addend = SymInfo.getOffset() + Addend; 1109 } else { 1110 switch (SymType) { 1111 case SymbolRef::ST_Debug: { 1112 // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously 1113 // and can be changed by another developers. Maybe best way is add 1114 // a new symbol type ST_Section to SymbolRef and use it. 1115 auto SectionOrErr = Symbol->getSection(); 1116 if (!SectionOrErr) { 1117 std::string Buf; 1118 raw_string_ostream OS(Buf); 1119 logAllUnhandledErrors(SectionOrErr.takeError(), OS, ""); 1120 OS.flush(); 1121 report_fatal_error(Buf); 1122 } 1123 section_iterator si = *SectionOrErr; 1124 if (si == Obj.section_end()) 1125 llvm_unreachable("Symbol section not found, bad object file format!"); 1126 DEBUG(dbgs() << "\t\tThis is section symbol\n"); 1127 bool isCode = si->isText(); 1128 if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode, 1129 ObjSectionToID)) 1130 Value.SectionID = *SectionIDOrErr; 1131 else 1132 return SectionIDOrErr.takeError(); 1133 Value.Addend = Addend; 1134 break; 1135 } 1136 case SymbolRef::ST_Data: 1137 case SymbolRef::ST_Function: 1138 case SymbolRef::ST_Unknown: { 1139 Value.SymbolName = TargetName.data(); 1140 Value.Addend = Addend; 1141 1142 // Absolute relocations will have a zero symbol ID (STN_UNDEF), which 1143 // will manifest here as a NULL symbol name. 1144 // We can set this as a valid (but empty) symbol name, and rely 1145 // on addRelocationForSymbol to handle this. 1146 if (!Value.SymbolName) 1147 Value.SymbolName = ""; 1148 break; 1149 } 1150 default: 1151 llvm_unreachable("Unresolved symbol type!"); 1152 break; 1153 } 1154 } 1155 1156 uint64_t Offset = RelI->getOffset(); 1157 1158 DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset 1159 << "\n"); 1160 if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) { 1161 if (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26) { 1162 resolveAArch64Branch(SectionID, Value, RelI, Stubs); 1163 } else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) { 1164 // Craete new GOT entry or find existing one. If GOT entry is 1165 // to be created, then we also emit ABS64 relocation for it. 1166 uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64); 1167 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend, 1168 ELF::R_AARCH64_ADR_PREL_PG_HI21); 1169 1170 } else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) { 1171 uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64); 1172 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend, 1173 ELF::R_AARCH64_LDST64_ABS_LO12_NC); 1174 } else { 1175 processSimpleRelocation(SectionID, Offset, RelType, Value); 1176 } 1177 } else if (Arch == Triple::arm) { 1178 if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL || 1179 RelType == ELF::R_ARM_JUMP24) { 1180 // This is an ARM branch relocation, need to use a stub function. 1181 DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n"); 1182 SectionEntry &Section = Sections[SectionID]; 1183 1184 // Look for an existing stub. 1185 StubMap::const_iterator i = Stubs.find(Value); 1186 if (i != Stubs.end()) { 1187 resolveRelocation( 1188 Section, Offset, 1189 reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)), 1190 RelType, 0); 1191 DEBUG(dbgs() << " Stub function found\n"); 1192 } else { 1193 // Create a new stub function. 1194 DEBUG(dbgs() << " Create a new stub function\n"); 1195 Stubs[Value] = Section.getStubOffset(); 1196 uint8_t *StubTargetAddr = createStubFunction( 1197 Section.getAddressWithOffset(Section.getStubOffset())); 1198 RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(), 1199 ELF::R_ARM_ABS32, Value.Addend); 1200 if (Value.SymbolName) 1201 addRelocationForSymbol(RE, Value.SymbolName); 1202 else 1203 addRelocationForSection(RE, Value.SectionID); 1204 1205 resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>( 1206 Section.getAddressWithOffset( 1207 Section.getStubOffset())), 1208 RelType, 0); 1209 Section.advanceStubOffset(getMaxStubSize()); 1210 } 1211 } else { 1212 uint32_t *Placeholder = 1213 reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset)); 1214 if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 || 1215 RelType == ELF::R_ARM_ABS32) { 1216 Value.Addend += *Placeholder; 1217 } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) { 1218 // See ELF for ARM documentation 1219 Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12)); 1220 } 1221 processSimpleRelocation(SectionID, Offset, RelType, Value); 1222 } 1223 } else if (IsMipsO32ABI) { 1224 uint8_t *Placeholder = reinterpret_cast<uint8_t *>( 1225 computePlaceholderAddress(SectionID, Offset)); 1226 uint32_t Opcode = readBytesUnaligned(Placeholder, 4); 1227 if (RelType == ELF::R_MIPS_26) { 1228 // This is an Mips branch relocation, need to use a stub function. 1229 DEBUG(dbgs() << "\t\tThis is a Mips branch relocation."); 1230 SectionEntry &Section = Sections[SectionID]; 1231 1232 // Extract the addend from the instruction. 1233 // We shift up by two since the Value will be down shifted again 1234 // when applying the relocation. 1235 uint32_t Addend = (Opcode & 0x03ffffff) << 2; 1236 1237 Value.Addend += Addend; 1238 1239 // Look up for existing stub. 1240 StubMap::const_iterator i = Stubs.find(Value); 1241 if (i != Stubs.end()) { 1242 RelocationEntry RE(SectionID, Offset, RelType, i->second); 1243 addRelocationForSection(RE, SectionID); 1244 DEBUG(dbgs() << " Stub function found\n"); 1245 } else { 1246 // Create a new stub function. 1247 DEBUG(dbgs() << " Create a new stub function\n"); 1248 Stubs[Value] = Section.getStubOffset(); 1249 1250 unsigned AbiVariant; 1251 O.getPlatformFlags(AbiVariant); 1252 1253 uint8_t *StubTargetAddr = createStubFunction( 1254 Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant); 1255 1256 // Creating Hi and Lo relocations for the filled stub instructions. 1257 RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(), 1258 ELF::R_MIPS_HI16, Value.Addend); 1259 RelocationEntry RELo(SectionID, 1260 StubTargetAddr - Section.getAddress() + 4, 1261 ELF::R_MIPS_LO16, Value.Addend); 1262 1263 if (Value.SymbolName) { 1264 addRelocationForSymbol(REHi, Value.SymbolName); 1265 addRelocationForSymbol(RELo, Value.SymbolName); 1266 } 1267 else { 1268 addRelocationForSection(REHi, Value.SectionID); 1269 addRelocationForSection(RELo, Value.SectionID); 1270 } 1271 1272 RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset()); 1273 addRelocationForSection(RE, SectionID); 1274 Section.advanceStubOffset(getMaxStubSize()); 1275 } 1276 } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) { 1277 int64_t Addend = (Opcode & 0x0000ffff) << 16; 1278 RelocationEntry RE(SectionID, Offset, RelType, Addend); 1279 PendingRelocs.push_back(std::make_pair(Value, RE)); 1280 } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) { 1281 int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff); 1282 for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) { 1283 const RelocationValueRef &MatchingValue = I->first; 1284 RelocationEntry &Reloc = I->second; 1285 if (MatchingValue == Value && 1286 RelType == getMatchingLoRelocation(Reloc.RelType) && 1287 SectionID == Reloc.SectionID) { 1288 Reloc.Addend += Addend; 1289 if (Value.SymbolName) 1290 addRelocationForSymbol(Reloc, Value.SymbolName); 1291 else 1292 addRelocationForSection(Reloc, Value.SectionID); 1293 I = PendingRelocs.erase(I); 1294 } else 1295 ++I; 1296 } 1297 RelocationEntry RE(SectionID, Offset, RelType, Addend); 1298 if (Value.SymbolName) 1299 addRelocationForSymbol(RE, Value.SymbolName); 1300 else 1301 addRelocationForSection(RE, Value.SectionID); 1302 } else { 1303 if (RelType == ELF::R_MIPS_32) 1304 Value.Addend += Opcode; 1305 else if (RelType == ELF::R_MIPS_PC16) 1306 Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2); 1307 else if (RelType == ELF::R_MIPS_PC19_S2) 1308 Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2); 1309 else if (RelType == ELF::R_MIPS_PC21_S2) 1310 Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2); 1311 else if (RelType == ELF::R_MIPS_PC26_S2) 1312 Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2); 1313 processSimpleRelocation(SectionID, Offset, RelType, Value); 1314 } 1315 } else if (IsMipsN32ABI || IsMipsN64ABI) { 1316 uint32_t r_type = RelType & 0xff; 1317 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend); 1318 if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE 1319 || r_type == ELF::R_MIPS_GOT_DISP) { 1320 StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName); 1321 if (i != GOTSymbolOffsets.end()) 1322 RE.SymOffset = i->second; 1323 else { 1324 RE.SymOffset = allocateGOTEntries(1); 1325 GOTSymbolOffsets[TargetName] = RE.SymOffset; 1326 } 1327 } 1328 if (Value.SymbolName) 1329 addRelocationForSymbol(RE, Value.SymbolName); 1330 else 1331 addRelocationForSection(RE, Value.SectionID); 1332 } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) { 1333 if (RelType == ELF::R_PPC64_REL24) { 1334 // Determine ABI variant in use for this object. 1335 unsigned AbiVariant; 1336 Obj.getPlatformFlags(AbiVariant); 1337 AbiVariant &= ELF::EF_PPC64_ABI; 1338 // A PPC branch relocation will need a stub function if the target is 1339 // an external symbol (either Value.SymbolName is set, or SymType is 1340 // Symbol::ST_Unknown) or if the target address is not within the 1341 // signed 24-bits branch address. 1342 SectionEntry &Section = Sections[SectionID]; 1343 uint8_t *Target = Section.getAddressWithOffset(Offset); 1344 bool RangeOverflow = false; 1345 if (!Value.SymbolName && SymType != SymbolRef::ST_Unknown) { 1346 if (AbiVariant != 2) { 1347 // In the ELFv1 ABI, a function call may point to the .opd entry, 1348 // so the final symbol value is calculated based on the relocation 1349 // values in the .opd section. 1350 if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value)) 1351 return std::move(Err); 1352 } else { 1353 // In the ELFv2 ABI, a function symbol may provide a local entry 1354 // point, which must be used for direct calls. 1355 uint8_t SymOther = Symbol->getOther(); 1356 Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther); 1357 } 1358 uint8_t *RelocTarget = 1359 Sections[Value.SectionID].getAddressWithOffset(Value.Addend); 1360 int64_t delta = static_cast<int64_t>(Target - RelocTarget); 1361 // If it is within 26-bits branch range, just set the branch target 1362 if (SignExtend64<26>(delta) == delta) { 1363 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend); 1364 addRelocationForSection(RE, Value.SectionID); 1365 } else { 1366 RangeOverflow = true; 1367 } 1368 } 1369 if (Value.SymbolName || SymType == SymbolRef::ST_Unknown || 1370 RangeOverflow) { 1371 // It is an external symbol (either Value.SymbolName is set, or 1372 // SymType is SymbolRef::ST_Unknown) or out of range. 1373 StubMap::const_iterator i = Stubs.find(Value); 1374 if (i != Stubs.end()) { 1375 // Symbol function stub already created, just relocate to it 1376 resolveRelocation(Section, Offset, 1377 reinterpret_cast<uint64_t>( 1378 Section.getAddressWithOffset(i->second)), 1379 RelType, 0); 1380 DEBUG(dbgs() << " Stub function found\n"); 1381 } else { 1382 // Create a new stub function. 1383 DEBUG(dbgs() << " Create a new stub function\n"); 1384 Stubs[Value] = Section.getStubOffset(); 1385 uint8_t *StubTargetAddr = createStubFunction( 1386 Section.getAddressWithOffset(Section.getStubOffset()), 1387 AbiVariant); 1388 RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(), 1389 ELF::R_PPC64_ADDR64, Value.Addend); 1390 1391 // Generates the 64-bits address loads as exemplified in section 1392 // 4.5.1 in PPC64 ELF ABI. Note that the relocations need to 1393 // apply to the low part of the instructions, so we have to update 1394 // the offset according to the target endianness. 1395 uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress(); 1396 if (!IsTargetLittleEndian) 1397 StubRelocOffset += 2; 1398 1399 RelocationEntry REhst(SectionID, StubRelocOffset + 0, 1400 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend); 1401 RelocationEntry REhr(SectionID, StubRelocOffset + 4, 1402 ELF::R_PPC64_ADDR16_HIGHER, Value.Addend); 1403 RelocationEntry REh(SectionID, StubRelocOffset + 12, 1404 ELF::R_PPC64_ADDR16_HI, Value.Addend); 1405 RelocationEntry REl(SectionID, StubRelocOffset + 16, 1406 ELF::R_PPC64_ADDR16_LO, Value.Addend); 1407 1408 if (Value.SymbolName) { 1409 addRelocationForSymbol(REhst, Value.SymbolName); 1410 addRelocationForSymbol(REhr, Value.SymbolName); 1411 addRelocationForSymbol(REh, Value.SymbolName); 1412 addRelocationForSymbol(REl, Value.SymbolName); 1413 } else { 1414 addRelocationForSection(REhst, Value.SectionID); 1415 addRelocationForSection(REhr, Value.SectionID); 1416 addRelocationForSection(REh, Value.SectionID); 1417 addRelocationForSection(REl, Value.SectionID); 1418 } 1419 1420 resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>( 1421 Section.getAddressWithOffset( 1422 Section.getStubOffset())), 1423 RelType, 0); 1424 Section.advanceStubOffset(getMaxStubSize()); 1425 } 1426 if (Value.SymbolName || SymType == SymbolRef::ST_Unknown) { 1427 // Restore the TOC for external calls 1428 if (AbiVariant == 2) 1429 writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1) 1430 else 1431 writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1) 1432 } 1433 } 1434 } else if (RelType == ELF::R_PPC64_TOC16 || 1435 RelType == ELF::R_PPC64_TOC16_DS || 1436 RelType == ELF::R_PPC64_TOC16_LO || 1437 RelType == ELF::R_PPC64_TOC16_LO_DS || 1438 RelType == ELF::R_PPC64_TOC16_HI || 1439 RelType == ELF::R_PPC64_TOC16_HA) { 1440 // These relocations are supposed to subtract the TOC address from 1441 // the final value. This does not fit cleanly into the RuntimeDyld 1442 // scheme, since there may be *two* sections involved in determining 1443 // the relocation value (the section of the symbol referred to by the 1444 // relocation, and the TOC section associated with the current module). 1445 // 1446 // Fortunately, these relocations are currently only ever generated 1447 // referring to symbols that themselves reside in the TOC, which means 1448 // that the two sections are actually the same. Thus they cancel out 1449 // and we can immediately resolve the relocation right now. 1450 switch (RelType) { 1451 case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break; 1452 case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break; 1453 case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break; 1454 case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break; 1455 case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break; 1456 case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break; 1457 default: llvm_unreachable("Wrong relocation type."); 1458 } 1459 1460 RelocationValueRef TOCValue; 1461 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue)) 1462 return std::move(Err); 1463 if (Value.SymbolName || Value.SectionID != TOCValue.SectionID) 1464 llvm_unreachable("Unsupported TOC relocation."); 1465 Value.Addend -= TOCValue.Addend; 1466 resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0); 1467 } else { 1468 // There are two ways to refer to the TOC address directly: either 1469 // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are 1470 // ignored), or via any relocation that refers to the magic ".TOC." 1471 // symbols (in which case the addend is respected). 1472 if (RelType == ELF::R_PPC64_TOC) { 1473 RelType = ELF::R_PPC64_ADDR64; 1474 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value)) 1475 return std::move(Err); 1476 } else if (TargetName == ".TOC.") { 1477 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value)) 1478 return std::move(Err); 1479 Value.Addend += Addend; 1480 } 1481 1482 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend); 1483 1484 if (Value.SymbolName) 1485 addRelocationForSymbol(RE, Value.SymbolName); 1486 else 1487 addRelocationForSection(RE, Value.SectionID); 1488 } 1489 } else if (Arch == Triple::systemz && 1490 (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) { 1491 // Create function stubs for both PLT and GOT references, regardless of 1492 // whether the GOT reference is to data or code. The stub contains the 1493 // full address of the symbol, as needed by GOT references, and the 1494 // executable part only adds an overhead of 8 bytes. 1495 // 1496 // We could try to conserve space by allocating the code and data 1497 // parts of the stub separately. However, as things stand, we allocate 1498 // a stub for every relocation, so using a GOT in JIT code should be 1499 // no less space efficient than using an explicit constant pool. 1500 DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation."); 1501 SectionEntry &Section = Sections[SectionID]; 1502 1503 // Look for an existing stub. 1504 StubMap::const_iterator i = Stubs.find(Value); 1505 uintptr_t StubAddress; 1506 if (i != Stubs.end()) { 1507 StubAddress = uintptr_t(Section.getAddressWithOffset(i->second)); 1508 DEBUG(dbgs() << " Stub function found\n"); 1509 } else { 1510 // Create a new stub function. 1511 DEBUG(dbgs() << " Create a new stub function\n"); 1512 1513 uintptr_t BaseAddress = uintptr_t(Section.getAddress()); 1514 uintptr_t StubAlignment = getStubAlignment(); 1515 StubAddress = 1516 (BaseAddress + Section.getStubOffset() + StubAlignment - 1) & 1517 -StubAlignment; 1518 unsigned StubOffset = StubAddress - BaseAddress; 1519 1520 Stubs[Value] = StubOffset; 1521 createStubFunction((uint8_t *)StubAddress); 1522 RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64, 1523 Value.Offset); 1524 if (Value.SymbolName) 1525 addRelocationForSymbol(RE, Value.SymbolName); 1526 else 1527 addRelocationForSection(RE, Value.SectionID); 1528 Section.advanceStubOffset(getMaxStubSize()); 1529 } 1530 1531 if (RelType == ELF::R_390_GOTENT) 1532 resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL, 1533 Addend); 1534 else 1535 resolveRelocation(Section, Offset, StubAddress, RelType, Addend); 1536 } else if (Arch == Triple::x86_64) { 1537 if (RelType == ELF::R_X86_64_PLT32) { 1538 // The way the PLT relocations normally work is that the linker allocates 1539 // the 1540 // PLT and this relocation makes a PC-relative call into the PLT. The PLT 1541 // entry will then jump to an address provided by the GOT. On first call, 1542 // the 1543 // GOT address will point back into PLT code that resolves the symbol. After 1544 // the first call, the GOT entry points to the actual function. 1545 // 1546 // For local functions we're ignoring all of that here and just replacing 1547 // the PLT32 relocation type with PC32, which will translate the relocation 1548 // into a PC-relative call directly to the function. For external symbols we 1549 // can't be sure the function will be within 2^32 bytes of the call site, so 1550 // we need to create a stub, which calls into the GOT. This case is 1551 // equivalent to the usual PLT implementation except that we use the stub 1552 // mechanism in RuntimeDyld (which puts stubs at the end of the section) 1553 // rather than allocating a PLT section. 1554 if (Value.SymbolName) { 1555 // This is a call to an external function. 1556 // Look for an existing stub. 1557 SectionEntry &Section = Sections[SectionID]; 1558 StubMap::const_iterator i = Stubs.find(Value); 1559 uintptr_t StubAddress; 1560 if (i != Stubs.end()) { 1561 StubAddress = uintptr_t(Section.getAddress()) + i->second; 1562 DEBUG(dbgs() << " Stub function found\n"); 1563 } else { 1564 // Create a new stub function (equivalent to a PLT entry). 1565 DEBUG(dbgs() << " Create a new stub function\n"); 1566 1567 uintptr_t BaseAddress = uintptr_t(Section.getAddress()); 1568 uintptr_t StubAlignment = getStubAlignment(); 1569 StubAddress = 1570 (BaseAddress + Section.getStubOffset() + StubAlignment - 1) & 1571 -StubAlignment; 1572 unsigned StubOffset = StubAddress - BaseAddress; 1573 Stubs[Value] = StubOffset; 1574 createStubFunction((uint8_t *)StubAddress); 1575 1576 // Bump our stub offset counter 1577 Section.advanceStubOffset(getMaxStubSize()); 1578 1579 // Allocate a GOT Entry 1580 uint64_t GOTOffset = allocateGOTEntries(1); 1581 1582 // The load of the GOT address has an addend of -4 1583 resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4, 1584 ELF::R_X86_64_PC32); 1585 1586 // Fill in the value of the symbol we're targeting into the GOT 1587 addRelocationForSymbol( 1588 computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64), 1589 Value.SymbolName); 1590 } 1591 1592 // Make the target call a call into the stub table. 1593 resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32, 1594 Addend); 1595 } else { 1596 RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend, 1597 Value.Offset); 1598 addRelocationForSection(RE, Value.SectionID); 1599 } 1600 } else if (RelType == ELF::R_X86_64_GOTPCREL || 1601 RelType == ELF::R_X86_64_GOTPCRELX || 1602 RelType == ELF::R_X86_64_REX_GOTPCRELX) { 1603 uint64_t GOTOffset = allocateGOTEntries(1); 1604 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend, 1605 ELF::R_X86_64_PC32); 1606 1607 // Fill in the value of the symbol we're targeting into the GOT 1608 RelocationEntry RE = 1609 computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64); 1610 if (Value.SymbolName) 1611 addRelocationForSymbol(RE, Value.SymbolName); 1612 else 1613 addRelocationForSection(RE, Value.SectionID); 1614 } else if (RelType == ELF::R_X86_64_PC32) { 1615 Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset)); 1616 processSimpleRelocation(SectionID, Offset, RelType, Value); 1617 } else if (RelType == ELF::R_X86_64_PC64) { 1618 Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset)); 1619 processSimpleRelocation(SectionID, Offset, RelType, Value); 1620 } else { 1621 processSimpleRelocation(SectionID, Offset, RelType, Value); 1622 } 1623 } else { 1624 if (Arch == Triple::x86) { 1625 Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset)); 1626 } 1627 processSimpleRelocation(SectionID, Offset, RelType, Value); 1628 } 1629 return ++RelI; 1630 } 1631 1632 size_t RuntimeDyldELF::getGOTEntrySize() { 1633 // We don't use the GOT in all of these cases, but it's essentially free 1634 // to put them all here. 1635 size_t Result = 0; 1636 switch (Arch) { 1637 case Triple::x86_64: 1638 case Triple::aarch64: 1639 case Triple::aarch64_be: 1640 case Triple::ppc64: 1641 case Triple::ppc64le: 1642 case Triple::systemz: 1643 Result = sizeof(uint64_t); 1644 break; 1645 case Triple::x86: 1646 case Triple::arm: 1647 case Triple::thumb: 1648 Result = sizeof(uint32_t); 1649 break; 1650 case Triple::mips: 1651 case Triple::mipsel: 1652 case Triple::mips64: 1653 case Triple::mips64el: 1654 if (IsMipsO32ABI || IsMipsN32ABI) 1655 Result = sizeof(uint32_t); 1656 else if (IsMipsN64ABI) 1657 Result = sizeof(uint64_t); 1658 else 1659 llvm_unreachable("Mips ABI not handled"); 1660 break; 1661 default: 1662 llvm_unreachable("Unsupported CPU type!"); 1663 } 1664 return Result; 1665 } 1666 1667 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) { 1668 if (GOTSectionID == 0) { 1669 GOTSectionID = Sections.size(); 1670 // Reserve a section id. We'll allocate the section later 1671 // once we know the total size 1672 Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0)); 1673 } 1674 uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize(); 1675 CurrentGOTIndex += no; 1676 return StartOffset; 1677 } 1678 1679 uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value, 1680 unsigned GOTRelType) { 1681 auto E = GOTOffsetMap.insert({Value, 0}); 1682 if (E.second) { 1683 uint64_t GOTOffset = allocateGOTEntries(1); 1684 1685 // Create relocation for newly created GOT entry 1686 RelocationEntry RE = 1687 computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType); 1688 if (Value.SymbolName) 1689 addRelocationForSymbol(RE, Value.SymbolName); 1690 else 1691 addRelocationForSection(RE, Value.SectionID); 1692 1693 E.first->second = GOTOffset; 1694 } 1695 1696 return E.first->second; 1697 } 1698 1699 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID, 1700 uint64_t Offset, 1701 uint64_t GOTOffset, 1702 uint32_t Type) { 1703 // Fill in the relative address of the GOT Entry into the stub 1704 RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset); 1705 addRelocationForSection(GOTRE, GOTSectionID); 1706 } 1707 1708 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset, 1709 uint64_t SymbolOffset, 1710 uint32_t Type) { 1711 return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset); 1712 } 1713 1714 Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj, 1715 ObjSectionToIDMap &SectionMap) { 1716 if (IsMipsO32ABI) 1717 if (!PendingRelocs.empty()) 1718 return make_error<RuntimeDyldError>("Can't find matching LO16 reloc"); 1719 1720 // If necessary, allocate the global offset table 1721 if (GOTSectionID != 0) { 1722 // Allocate memory for the section 1723 size_t TotalSize = CurrentGOTIndex * getGOTEntrySize(); 1724 uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(), 1725 GOTSectionID, ".got", false); 1726 if (!Addr) 1727 return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!"); 1728 1729 Sections[GOTSectionID] = 1730 SectionEntry(".got", Addr, TotalSize, TotalSize, 0); 1731 1732 if (Checker) 1733 Checker->registerSection(Obj.getFileName(), GOTSectionID); 1734 1735 // For now, initialize all GOT entries to zero. We'll fill them in as 1736 // needed when GOT-based relocations are applied. 1737 memset(Addr, 0, TotalSize); 1738 if (IsMipsN32ABI || IsMipsN64ABI) { 1739 // To correctly resolve Mips GOT relocations, we need a mapping from 1740 // object's sections to GOTs. 1741 for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end(); 1742 SI != SE; ++SI) { 1743 if (SI->relocation_begin() != SI->relocation_end()) { 1744 section_iterator RelocatedSection = SI->getRelocatedSection(); 1745 ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection); 1746 assert (i != SectionMap.end()); 1747 SectionToGOTMap[i->second] = GOTSectionID; 1748 } 1749 } 1750 GOTSymbolOffsets.clear(); 1751 } 1752 } 1753 1754 // Look for and record the EH frame section. 1755 ObjSectionToIDMap::iterator i, e; 1756 for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) { 1757 const SectionRef &Section = i->first; 1758 StringRef Name; 1759 Section.getName(Name); 1760 if (Name == ".eh_frame") { 1761 UnregisteredEHFrameSections.push_back(i->second); 1762 break; 1763 } 1764 } 1765 1766 GOTSectionID = 0; 1767 CurrentGOTIndex = 0; 1768 1769 return Error::success(); 1770 } 1771 1772 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const { 1773 return Obj.isELF(); 1774 } 1775 1776 bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const { 1777 unsigned RelTy = R.getType(); 1778 if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be) 1779 return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE || 1780 RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC; 1781 1782 if (Arch == Triple::x86_64) 1783 return RelTy == ELF::R_X86_64_GOTPCREL || 1784 RelTy == ELF::R_X86_64_GOTPCRELX || 1785 RelTy == ELF::R_X86_64_REX_GOTPCRELX; 1786 return false; 1787 } 1788 1789 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const { 1790 if (Arch != Triple::x86_64) 1791 return true; // Conservative answer 1792 1793 switch (R.getType()) { 1794 default: 1795 return true; // Conservative answer 1796 1797 1798 case ELF::R_X86_64_GOTPCREL: 1799 case ELF::R_X86_64_GOTPCRELX: 1800 case ELF::R_X86_64_REX_GOTPCRELX: 1801 case ELF::R_X86_64_PC32: 1802 case ELF::R_X86_64_PC64: 1803 case ELF::R_X86_64_64: 1804 // We know that these reloation types won't need a stub function. This list 1805 // can be extended as needed. 1806 return false; 1807 } 1808 } 1809 1810 } // namespace llvm 1811