lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

   1 //===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Implementation of ELF support for the MC-JIT runtime dynamic linker.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "RuntimeDyldELF.h"
  14 #include "RuntimeDyldCheckerImpl.h"
  15 #include "Targets/RuntimeDyldELFMips.h"
  16 #include "llvm/ADT/STLExtras.h"
  17 #include "llvm/ADT/StringRef.h"
  18 #include "llvm/ADT/Triple.h"
  19 #include "llvm/BinaryFormat/ELF.h"
  20 #include "llvm/Object/ELFObjectFile.h"
  21 #include "llvm/Object/ObjectFile.h"
  22 #include "llvm/Support/Endian.h"
  23 #include "llvm/Support/MemoryBuffer.h"
  24
  25 using namespace llvm;
  26 using namespace llvm::object;
  27 using namespace llvm::support::endian;
  28
  29 #define DEBUG_TYPE "dyld"
  30
  31 static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); }
  32
  33 static void or32AArch64Imm(void *L, uint64_t Imm) {
  34   or32le(L, (Imm & 0xFFF) << 10);
  35 }
  36
  37 template <class T> static void write(bool isBE, void *P, T V) {
  38   isBE ? write<T, support::big>(P, V) : write<T, support::little>(P, V);
  39 }
  40
  41 static void write32AArch64Addr(void *L, uint64_t Imm) {
  42   uint32_t ImmLo = (Imm & 0x3) << 29;
  43   uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
  44   uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
  45   write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
  46 }
  47
  48 // Return the bits [Start, End] from Val shifted Start bits.
  49 // For instance, getBits(0xF0, 4, 8) returns 0xF.
  50 static uint64_t getBits(uint64_t Val, int Start, int End) {
  51   uint64_t Mask = ((uint64_t)1 << (End + 1 - Start)) - 1;
  52   return (Val >> Start) & Mask;
  53 }
  54
  55 namespace {
  56
  57 template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> {
  58   LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
  59
  60   typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
  61   typedef Elf_Sym_Impl<ELFT> Elf_Sym;
  62   typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
  63   typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
  64
  65   typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
  66
  67   typedef typename ELFT::uint addr_type;
  68
  69   DyldELFObject(ELFObjectFile<ELFT> &&Obj);
  70
  71 public:
  72   static Expected<std::unique_ptr<DyldELFObject>>
  73   create(MemoryBufferRef Wrapper);
  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(ELFObjectFile<ELFT> &&Obj)
  96     : ELFObjectFile<ELFT>(std::move(Obj)) {
  97   this->isDyldELFObject = true;
  98 }
  99
 100 template <class ELFT>
 101 Expected<std::unique_ptr<DyldELFObject<ELFT>>>
 102 DyldELFObject<ELFT>::create(MemoryBufferRef Wrapper) {
 103   auto Obj = ELFObjectFile<ELFT>::create(Wrapper);
 104   if (auto E = Obj.takeError())
 105     return std::move(E);
 106   std::unique_ptr<DyldELFObject<ELFT>> Ret(
 107       new DyldELFObject<ELFT>(std::move(*Obj)));
 108   return std::move(Ret);
 109 }
 110
 111 template <class ELFT>
 112 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
 113                                                uint64_t Addr) {
 114   DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
 115   Elf_Shdr *shdr =
 116       const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
 117
 118   // This assumes the address passed in matches the target address bitness
 119   // The template-based type cast handles everything else.
 120   shdr->sh_addr = static_cast<addr_type>(Addr);
 121 }
 122
 123 template <class ELFT>
 124 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
 125                                               uint64_t Addr) {
 126
 127   Elf_Sym *sym = const_cast<Elf_Sym *>(
 128       ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
 129
 130   // This assumes the address passed in matches the target address bitness
 131   // The template-based type cast handles everything else.
 132   sym->st_value = static_cast<addr_type>(Addr);
 133 }
 134
 135 class LoadedELFObjectInfo final
 136     : public LoadedObjectInfoHelper<LoadedELFObjectInfo,
 137                                     RuntimeDyld::LoadedObjectInfo> {
 138 public:
 139   LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
 140       : LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {}
 141
 142   OwningBinary<ObjectFile>
 143   getObjectForDebug(const ObjectFile &Obj) const override;
 144 };
 145
 146 template <typename ELFT>
 147 static Expected<std::unique_ptr<DyldELFObject<ELFT>>>
 148 createRTDyldELFObject(MemoryBufferRef Buffer, const ObjectFile &SourceObject,
 149                       const LoadedELFObjectInfo &L) {
 150   typedef typename ELFT::Shdr Elf_Shdr;
 151   typedef typename ELFT::uint addr_type;
 152
 153   Expected<std::unique_ptr<DyldELFObject<ELFT>>> ObjOrErr =
 154       DyldELFObject<ELFT>::create(Buffer);
 155   if (Error E = ObjOrErr.takeError())
 156     return std::move(E);
 157
 158   std::unique_ptr<DyldELFObject<ELFT>> Obj = std::move(*ObjOrErr);
 159
 160   // Iterate over all sections in the object.
 161   auto SI = SourceObject.section_begin();
 162   for (const auto &Sec : Obj->sections()) {
 163     Expected<StringRef> NameOrErr = Sec.getName();
 164     if (!NameOrErr) {
 165       consumeError(NameOrErr.takeError());
 166       continue;
 167     }
 168
 169     if (*NameOrErr != "") {
 170       DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
 171       Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
 172           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
 173
 174       if (uint64_t SecLoadAddr = L.getSectionLoadAddress(*SI)) {
 175         // This assumes that the address passed in matches the target address
 176         // bitness. The template-based type cast handles everything else.
 177         shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
 178       }
 179     }
 180     ++SI;
 181   }
 182
 183   return std::move(Obj);
 184 }
 185
 186 static OwningBinary<ObjectFile>
 187 createELFDebugObject(const ObjectFile &Obj, const LoadedELFObjectInfo &L) {
 188   assert(Obj.isELF() && "Not an ELF object file.");
 189
 190   std::unique_ptr<MemoryBuffer> Buffer =
 191     MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
 192
 193   Expected<std::unique_ptr<ObjectFile>> DebugObj(nullptr);
 194   handleAllErrors(DebugObj.takeError());
 195   if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian())
 196     DebugObj =
 197         createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), Obj, L);
 198   else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian())
 199     DebugObj =
 200         createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), Obj, L);
 201   else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian())
 202     DebugObj =
 203         createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), Obj, L);
 204   else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian())
 205     DebugObj =
 206         createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), Obj, L);
 207   else
 208     llvm_unreachable("Unexpected ELF format");
 209
 210   handleAllErrors(DebugObj.takeError());
 211   return OwningBinary<ObjectFile>(std::move(*DebugObj), std::move(Buffer));
 212 }
 213
 214 OwningBinary<ObjectFile>
 215 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
 216   return createELFDebugObject(Obj, *this);
 217 }
 218
 219 } // anonymous namespace
 220
 221 namespace llvm {
 222
 223 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
 224                                JITSymbolResolver &Resolver)
 225     : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
 226 RuntimeDyldELF::~RuntimeDyldELF() {}
 227
 228 void RuntimeDyldELF::registerEHFrames() {
 229   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
 230     SID EHFrameSID = UnregisteredEHFrameSections[i];
 231     uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
 232     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
 233     size_t EHFrameSize = Sections[EHFrameSID].getSize();
 234     MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
 235   }
 236   UnregisteredEHFrameSections.clear();
 237 }
 238
 239 std::unique_ptr<RuntimeDyldELF>
 240 llvm::RuntimeDyldELF::create(Triple::ArchType Arch,
 241                              RuntimeDyld::MemoryManager &MemMgr,
 242                              JITSymbolResolver &Resolver) {
 243   switch (Arch) {
 244   default:
 245     return std::make_unique<RuntimeDyldELF>(MemMgr, Resolver);
 246   case Triple::mips:
 247   case Triple::mipsel:
 248   case Triple::mips64:
 249   case Triple::mips64el:
 250     return std::make_unique<RuntimeDyldELFMips>(MemMgr, Resolver);
 251   }
 252 }
 253
 254 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
 255 RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
 256   if (auto ObjSectionToIDOrErr = loadObjectImpl(O))
 257     return std::make_unique<LoadedELFObjectInfo>(*this, *ObjSectionToIDOrErr);
 258   else {
 259     HasError = true;
 260     raw_string_ostream ErrStream(ErrorStr);
 261     logAllUnhandledErrors(ObjSectionToIDOrErr.takeError(), ErrStream);
 262     return nullptr;
 263   }
 264 }
 265
 266 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
 267                                              uint64_t Offset, uint64_t Value,
 268                                              uint32_t Type, int64_t Addend,
 269                                              uint64_t SymOffset) {
 270   switch (Type) {
 271   default:
 272     llvm_unreachable("Relocation type not implemented yet!");
 273     break;
 274   case ELF::R_X86_64_NONE:
 275     break;
 276   case ELF::R_X86_64_64: {
 277     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
 278         Value + Addend;
 279     LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
 280                       << format("%p\n", Section.getAddressWithOffset(Offset)));
 281     break;
 282   }
 283   case ELF::R_X86_64_32:
 284   case ELF::R_X86_64_32S: {
 285     Value += Addend;
 286     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
 287            (Type == ELF::R_X86_64_32S &&
 288             ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
 289     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
 290     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 291         TruncatedAddr;
 292     LLVM_DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
 293                       << format("%p\n", Section.getAddressWithOffset(Offset)));
 294     break;
 295   }
 296   case ELF::R_X86_64_PC8: {
 297     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 298     int64_t RealOffset = Value + Addend - FinalAddress;
 299     assert(isInt<8>(RealOffset));
 300     int8_t TruncOffset = (RealOffset & 0xFF);
 301     Section.getAddress()[Offset] = TruncOffset;
 302     break;
 303   }
 304   case ELF::R_X86_64_PC32: {
 305     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 306     int64_t RealOffset = Value + Addend - FinalAddress;
 307     assert(isInt<32>(RealOffset));
 308     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
 309     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 310         TruncOffset;
 311     break;
 312   }
 313   case ELF::R_X86_64_PC64: {
 314     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 315     int64_t RealOffset = Value + Addend - FinalAddress;
 316     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
 317         RealOffset;
 318     LLVM_DEBUG(dbgs() << "Writing " << format("%p", RealOffset) << " at "
 319                       << format("%p\n", FinalAddress));
 320     break;
 321   }
 322   case ELF::R_X86_64_GOTOFF64: {
 323     // Compute Value - GOTBase.
 324     uint64_t GOTBase = 0;
 325     for (const auto &Section : Sections) {
 326       if (Section.getName() == ".got") {
 327         GOTBase = Section.getLoadAddressWithOffset(0);
 328         break;
 329       }
 330     }
 331     assert(GOTBase != 0 && "missing GOT");
 332     int64_t GOTOffset = Value - GOTBase + Addend;
 333     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) = GOTOffset;
 334     break;
 335   }
 336   }
 337 }
 338
 339 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
 340                                           uint64_t Offset, uint32_t Value,
 341                                           uint32_t Type, int32_t Addend) {
 342   switch (Type) {
 343   case ELF::R_386_32: {
 344     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 345         Value + Addend;
 346     break;
 347   }
 348   // Handle R_386_PLT32 like R_386_PC32 since it should be able to
 349   // reach any 32 bit address.
 350   case ELF::R_386_PLT32:
 351   case ELF::R_386_PC32: {
 352     uint32_t FinalAddress =
 353         Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
 354     uint32_t RealOffset = Value + Addend - FinalAddress;
 355     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 356         RealOffset;
 357     break;
 358   }
 359   default:
 360     // There are other relocation types, but it appears these are the
 361     // only ones currently used by the LLVM ELF object writer
 362     llvm_unreachable("Relocation type not implemented yet!");
 363     break;
 364   }
 365 }
 366
 367 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
 368                                               uint64_t Offset, uint64_t Value,
 369                                               uint32_t Type, int64_t Addend) {
 370   uint32_t *TargetPtr =
 371       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
 372   uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 373   // Data should use target endian. Code should always use little endian.
 374   bool isBE = Arch == Triple::aarch64_be;
 375
 376   LLVM_DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
 377                     << format("%llx", Section.getAddressWithOffset(Offset))
 378                     << " FinalAddress: 0x" << format("%llx", FinalAddress)
 379                     << " Value: 0x" << format("%llx", Value) << " Type: 0x"
 380                     << format("%x", Type) << " Addend: 0x"
 381                     << format("%llx", Addend) << "\n");
 382
 383   switch (Type) {
 384   default:
 385     llvm_unreachable("Relocation type not implemented yet!");
 386     break;
 387   case ELF::R_AARCH64_ABS16: {
 388     uint64_t Result = Value + Addend;
 389     assert(static_cast<int64_t>(Result) >= INT16_MIN && Result < UINT16_MAX);
 390     write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU));
 391     break;
 392   }
 393   case ELF::R_AARCH64_ABS32: {
 394     uint64_t Result = Value + Addend;
 395     assert(static_cast<int64_t>(Result) >= INT32_MIN && Result < UINT32_MAX);
 396     write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
 397     break;
 398   }
 399   case ELF::R_AARCH64_ABS64:
 400     write(isBE, TargetPtr, Value + Addend);
 401     break;
 402   case ELF::R_AARCH64_PREL32: {
 403     uint64_t Result = Value + Addend - FinalAddress;
 404     assert(static_cast<int64_t>(Result) >= INT32_MIN &&
 405            static_cast<int64_t>(Result) <= UINT32_MAX);
 406     write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
 407     break;
 408   }
 409   case ELF::R_AARCH64_PREL64:
 410     write(isBE, TargetPtr, Value + Addend - FinalAddress);
 411     break;
 412   case ELF::R_AARCH64_CALL26: // fallthrough
 413   case ELF::R_AARCH64_JUMP26: {
 414     // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
 415     // calculation.
 416     uint64_t BranchImm = Value + Addend - FinalAddress;
 417
 418     // "Check that -2^27 <= result < 2^27".
 419     assert(isInt<28>(BranchImm));
 420     or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) >> 2);
 421     break;
 422   }
 423   case ELF::R_AARCH64_MOVW_UABS_G3:
 424     or32le(TargetPtr, ((Value + Addend) & 0xFFFF000000000000) >> 43);
 425     break;
 426   case ELF::R_AARCH64_MOVW_UABS_G2_NC:
 427     or32le(TargetPtr, ((Value + Addend) & 0xFFFF00000000) >> 27);
 428     break;
 429   case ELF::R_AARCH64_MOVW_UABS_G1_NC:
 430     or32le(TargetPtr, ((Value + Addend) & 0xFFFF0000) >> 11);
 431     break;
 432   case ELF::R_AARCH64_MOVW_UABS_G0_NC:
 433     or32le(TargetPtr, ((Value + Addend) & 0xFFFF) << 5);
 434     break;
 435   case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
 436     // Operation: Page(S+A) - Page(P)
 437     uint64_t Result =
 438         ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
 439
 440     // Check that -2^32 <= X < 2^32
 441     assert(isInt<33>(Result) && "overflow check failed for relocation");
 442
 443     // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
 444     // from bits 32:12 of X.
 445     write32AArch64Addr(TargetPtr, Result >> 12);
 446     break;
 447   }
 448   case ELF::R_AARCH64_ADD_ABS_LO12_NC:
 449     // Operation: S + A
 450     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 451     // from bits 11:0 of X
 452     or32AArch64Imm(TargetPtr, Value + Addend);
 453     break;
 454   case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
 455     // Operation: S + A
 456     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 457     // from bits 11:0 of X
 458     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 0, 11));
 459     break;
 460   case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
 461     // Operation: S + A
 462     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 463     // from bits 11:1 of X
 464     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 1, 11));
 465     break;
 466   case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
 467     // Operation: S + A
 468     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 469     // from bits 11:2 of X
 470     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 2, 11));
 471     break;
 472   case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
 473     // Operation: S + A
 474     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 475     // from bits 11:3 of X
 476     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 3, 11));
 477     break;
 478   case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
 479     // Operation: S + A
 480     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 481     // from bits 11:4 of X
 482     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 4, 11));
 483     break;
 484   }
 485 }
 486
 487 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
 488                                           uint64_t Offset, uint32_t Value,
 489                                           uint32_t Type, int32_t Addend) {
 490   // TODO: Add Thumb relocations.
 491   uint32_t *TargetPtr =
 492       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
 493   uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
 494   Value += Addend;
 495
 496   LLVM_DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
 497                     << Section.getAddressWithOffset(Offset)
 498                     << " FinalAddress: " << format("%p", FinalAddress)
 499                     << " Value: " << format("%x", Value)
 500                     << " Type: " << format("%x", Type)
 501                     << " Addend: " << format("%x", Addend) << "\n");
 502
 503   switch (Type) {
 504   default:
 505     llvm_unreachable("Not implemented relocation type!");
 506
 507   case ELF::R_ARM_NONE:
 508     break;
 509     // Write a 31bit signed offset
 510   case ELF::R_ARM_PREL31:
 511     support::ulittle32_t::ref{TargetPtr} =
 512         (support::ulittle32_t::ref{TargetPtr} & 0x80000000) |
 513         ((Value - FinalAddress) & ~0x80000000);
 514     break;
 515   case ELF::R_ARM_TARGET1:
 516   case ELF::R_ARM_ABS32:
 517     support::ulittle32_t::ref{TargetPtr} = Value;
 518     break;
 519     // Write first 16 bit of 32 bit value to the mov instruction.
 520     // Last 4 bit should be shifted.
 521   case ELF::R_ARM_MOVW_ABS_NC:
 522   case ELF::R_ARM_MOVT_ABS:
 523     if (Type == ELF::R_ARM_MOVW_ABS_NC)
 524       Value = Value & 0xFFFF;
 525     else if (Type == ELF::R_ARM_MOVT_ABS)
 526       Value = (Value >> 16) & 0xFFFF;
 527     support::ulittle32_t::ref{TargetPtr} =
 528         (support::ulittle32_t::ref{TargetPtr} & ~0x000F0FFF) | (Value & 0xFFF) |
 529         (((Value >> 12) & 0xF) << 16);
 530     break;
 531     // Write 24 bit relative value to the branch instruction.
 532   case ELF::R_ARM_PC24: // Fall through.
 533   case ELF::R_ARM_CALL: // Fall through.
 534   case ELF::R_ARM_JUMP24:
 535     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
 536     RelValue = (RelValue & 0x03FFFFFC) >> 2;
 537     assert((support::ulittle32_t::ref{TargetPtr} & 0xFFFFFF) == 0xFFFFFE);
 538     support::ulittle32_t::ref{TargetPtr} =
 539         (support::ulittle32_t::ref{TargetPtr} & 0xFF000000) | RelValue;
 540     break;
 541   }
 542 }
 543
 544 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
 545   if (Arch == Triple::UnknownArch ||
 546       !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
 547     IsMipsO32ABI = false;
 548     IsMipsN32ABI = false;
 549     IsMipsN64ABI = false;
 550     return;
 551   }
 552   if (auto *E = dyn_cast<ELFObjectFileBase>(&Obj)) {
 553     unsigned AbiVariant = E->getPlatformFlags();
 554     IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
 555     IsMipsN32ABI = AbiVariant & ELF::EF_MIPS_ABI2;
 556   }
 557   IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips");
 558 }
 559
 560 // Return the .TOC. section and offset.
 561 Error RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
 562                                           ObjSectionToIDMap &LocalSections,
 563                                           RelocationValueRef &Rel) {
 564   // Set a default SectionID in case we do not find a TOC section below.
 565   // This may happen for references to TOC base base (sym@toc, .odp
 566   // relocation) without a .toc directive.  In this case just use the
 567   // first section (which is usually the .odp) since the code won't
 568   // reference the .toc base directly.
 569   Rel.SymbolName = nullptr;
 570   Rel.SectionID = 0;
 571
 572   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
 573   // order. The TOC starts where the first of these sections starts.
 574   for (auto &Section : Obj.sections()) {
 575     Expected<StringRef> NameOrErr = Section.getName();
 576     if (!NameOrErr)
 577       return NameOrErr.takeError();
 578     StringRef SectionName = *NameOrErr;
 579
 580     if (SectionName == ".got"
 581         || SectionName == ".toc"
 582         || SectionName == ".tocbss"
 583         || SectionName == ".plt") {
 584       if (auto SectionIDOrErr =
 585             findOrEmitSection(Obj, Section, false, LocalSections))
 586         Rel.SectionID = *SectionIDOrErr;
 587       else
 588         return SectionIDOrErr.takeError();
 589       break;
 590     }
 591   }
 592
 593   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
 594   // thus permitting a full 64 Kbytes segment.
 595   Rel.Addend = 0x8000;
 596
 597   return Error::success();
 598 }
 599
 600 // Returns the sections and offset associated with the ODP entry referenced
 601 // by Symbol.
 602 Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
 603                                           ObjSectionToIDMap &LocalSections,
 604                                           RelocationValueRef &Rel) {
 605   // Get the ELF symbol value (st_value) to compare with Relocation offset in
 606   // .opd entries
 607   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
 608        si != se; ++si) {
 609     section_iterator RelSecI = si->getRelocatedSection();
 610     if (RelSecI == Obj.section_end())
 611       continue;
 612
 613     Expected<StringRef> NameOrErr = RelSecI->getName();
 614     if (!NameOrErr)
 615       return NameOrErr.takeError();
 616     StringRef RelSectionName = *NameOrErr;
 617
 618     if (RelSectionName != ".opd")
 619       continue;
 620
 621     for (elf_relocation_iterator i = si->relocation_begin(),
 622                                  e = si->relocation_end();
 623          i != e;) {
 624       // The R_PPC64_ADDR64 relocation indicates the first field
 625       // of a .opd entry
 626       uint64_t TypeFunc = i->getType();
 627       if (TypeFunc != ELF::R_PPC64_ADDR64) {
 628         ++i;
 629         continue;
 630       }
 631
 632       uint64_t TargetSymbolOffset = i->getOffset();
 633       symbol_iterator TargetSymbol = i->getSymbol();
 634       int64_t Addend;
 635       if (auto AddendOrErr = i->getAddend())
 636         Addend = *AddendOrErr;
 637       else
 638         return AddendOrErr.takeError();
 639
 640       ++i;
 641       if (i == e)
 642         break;
 643
 644       // Just check if following relocation is a R_PPC64_TOC
 645       uint64_t TypeTOC = i->getType();
 646       if (TypeTOC != ELF::R_PPC64_TOC)
 647         continue;
 648
 649       // Finally compares the Symbol value and the target symbol offset
 650       // to check if this .opd entry refers to the symbol the relocation
 651       // points to.
 652       if (Rel.Addend != (int64_t)TargetSymbolOffset)
 653         continue;
 654
 655       section_iterator TSI = Obj.section_end();
 656       if (auto TSIOrErr = TargetSymbol->getSection())
 657         TSI = *TSIOrErr;
 658       else
 659         return TSIOrErr.takeError();
 660       assert(TSI != Obj.section_end() && "TSI should refer to a valid section");
 661
 662       bool IsCode = TSI->isText();
 663       if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode,
 664                                                   LocalSections))
 665         Rel.SectionID = *SectionIDOrErr;
 666       else
 667         return SectionIDOrErr.takeError();
 668       Rel.Addend = (intptr_t)Addend;
 669       return Error::success();
 670     }
 671   }
 672   llvm_unreachable("Attempting to get address of ODP entry!");
 673 }
 674
 675 // Relocation masks following the #lo(value), #hi(value), #ha(value),
 676 // #higher(value), #highera(value), #highest(value), and #highesta(value)
 677 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
 678 // document.
 679
 680 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
 681
 682 static inline uint16_t applyPPChi(uint64_t value) {
 683   return (value >> 16) & 0xffff;
 684 }
 685
 686 static inline uint16_t applyPPCha (uint64_t value) {
 687   return ((value + 0x8000) >> 16) & 0xffff;
 688 }
 689
 690 static inline uint16_t applyPPChigher(uint64_t value) {
 691   return (value >> 32) & 0xffff;
 692 }
 693
 694 static inline uint16_t applyPPChighera (uint64_t value) {
 695   return ((value + 0x8000) >> 32) & 0xffff;
 696 }
 697
 698 static inline uint16_t applyPPChighest(uint64_t value) {
 699   return (value >> 48) & 0xffff;
 700 }
 701
 702 static inline uint16_t applyPPChighesta (uint64_t value) {
 703   return ((value + 0x8000) >> 48) & 0xffff;
 704 }
 705
 706 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
 707                                             uint64_t Offset, uint64_t Value,
 708                                             uint32_t Type, int64_t Addend) {
 709   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 710   switch (Type) {
 711   default:
 712     llvm_unreachable("Relocation type not implemented yet!");
 713     break;
 714   case ELF::R_PPC_ADDR16_LO:
 715     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 716     break;
 717   case ELF::R_PPC_ADDR16_HI:
 718     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
 719     break;
 720   case ELF::R_PPC_ADDR16_HA:
 721     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
 722     break;
 723   }
 724 }
 725
 726 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
 727                                             uint64_t Offset, uint64_t Value,
 728                                             uint32_t Type, int64_t Addend) {
 729   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 730   switch (Type) {
 731   default:
 732     llvm_unreachable("Relocation type not implemented yet!");
 733     break;
 734   case ELF::R_PPC64_ADDR16:
 735     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 736     break;
 737   case ELF::R_PPC64_ADDR16_DS:
 738     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
 739     break;
 740   case ELF::R_PPC64_ADDR16_LO:
 741     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 742     break;
 743   case ELF::R_PPC64_ADDR16_LO_DS:
 744     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
 745     break;
 746   case ELF::R_PPC64_ADDR16_HI:
 747   case ELF::R_PPC64_ADDR16_HIGH:
 748     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
 749     break;
 750   case ELF::R_PPC64_ADDR16_HA:
 751   case ELF::R_PPC64_ADDR16_HIGHA:
 752     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
 753     break;
 754   case ELF::R_PPC64_ADDR16_HIGHER:
 755     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
 756     break;
 757   case ELF::R_PPC64_ADDR16_HIGHERA:
 758     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
 759     break;
 760   case ELF::R_PPC64_ADDR16_HIGHEST:
 761     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
 762     break;
 763   case ELF::R_PPC64_ADDR16_HIGHESTA:
 764     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
 765     break;
 766   case ELF::R_PPC64_ADDR14: {
 767     assert(((Value + Addend) & 3) == 0);
 768     // Preserve the AA/LK bits in the branch instruction
 769     uint8_t aalk = *(LocalAddress + 3);
 770     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
 771   } break;
 772   case ELF::R_PPC64_REL16_LO: {
 773     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 774     uint64_t Delta = Value - FinalAddress + Addend;
 775     writeInt16BE(LocalAddress, applyPPClo(Delta));
 776   } break;
 777   case ELF::R_PPC64_REL16_HI: {
 778     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 779     uint64_t Delta = Value - FinalAddress + Addend;
 780     writeInt16BE(LocalAddress, applyPPChi(Delta));
 781   } break;
 782   case ELF::R_PPC64_REL16_HA: {
 783     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 784     uint64_t Delta = Value - FinalAddress + Addend;
 785     writeInt16BE(LocalAddress, applyPPCha(Delta));
 786   } break;
 787   case ELF::R_PPC64_ADDR32: {
 788     int64_t Result = static_cast<int64_t>(Value + Addend);
 789     if (SignExtend64<32>(Result) != Result)
 790       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
 791     writeInt32BE(LocalAddress, Result);
 792   } break;
 793   case ELF::R_PPC64_REL24: {
 794     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 795     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
 796     if (SignExtend64<26>(delta) != delta)
 797       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
 798     // We preserve bits other than LI field, i.e. PO and AA/LK fields.
 799     uint32_t Inst = readBytesUnaligned(LocalAddress, 4);
 800     writeInt32BE(LocalAddress, (Inst & 0xFC000003) | (delta & 0x03FFFFFC));
 801   } break;
 802   case ELF::R_PPC64_REL32: {
 803     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 804     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
 805     if (SignExtend64<32>(delta) != delta)
 806       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
 807     writeInt32BE(LocalAddress, delta);
 808   } break;
 809   case ELF::R_PPC64_REL64: {
 810     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 811     uint64_t Delta = Value - FinalAddress + Addend;
 812     writeInt64BE(LocalAddress, Delta);
 813   } break;
 814   case ELF::R_PPC64_ADDR64:
 815     writeInt64BE(LocalAddress, Value + Addend);
 816     break;
 817   }
 818 }
 819
 820 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
 821                                               uint64_t Offset, uint64_t Value,
 822                                               uint32_t Type, int64_t Addend) {
 823   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 824   switch (Type) {
 825   default:
 826     llvm_unreachable("Relocation type not implemented yet!");
 827     break;
 828   case ELF::R_390_PC16DBL:
 829   case ELF::R_390_PLT16DBL: {
 830     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 831     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
 832     writeInt16BE(LocalAddress, Delta / 2);
 833     break;
 834   }
 835   case ELF::R_390_PC32DBL:
 836   case ELF::R_390_PLT32DBL: {
 837     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 838     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
 839     writeInt32BE(LocalAddress, Delta / 2);
 840     break;
 841   }
 842   case ELF::R_390_PC16: {
 843     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 844     assert(int16_t(Delta) == Delta && "R_390_PC16 overflow");
 845     writeInt16BE(LocalAddress, Delta);
 846     break;
 847   }
 848   case ELF::R_390_PC32: {
 849     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 850     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
 851     writeInt32BE(LocalAddress, Delta);
 852     break;
 853   }
 854   case ELF::R_390_PC64: {
 855     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 856     writeInt64BE(LocalAddress, Delta);
 857     break;
 858   }
 859   case ELF::R_390_8:
 860     *LocalAddress = (uint8_t)(Value + Addend);
 861     break;
 862   case ELF::R_390_16:
 863     writeInt16BE(LocalAddress, Value + Addend);
 864     break;
 865   case ELF::R_390_32:
 866     writeInt32BE(LocalAddress, Value + Addend);
 867     break;
 868   case ELF::R_390_64:
 869     writeInt64BE(LocalAddress, Value + Addend);
 870     break;
 871   }
 872 }
 873
 874 void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
 875                                           uint64_t Offset, uint64_t Value,
 876                                           uint32_t Type, int64_t Addend) {
 877   bool isBE = Arch == Triple::bpfeb;
 878
 879   switch (Type) {
 880   default:
 881     llvm_unreachable("Relocation type not implemented yet!");
 882     break;
 883   case ELF::R_BPF_NONE:
 884     break;
 885   case ELF::R_BPF_64_64: {
 886     write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
 887     LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
 888                       << format("%p\n", Section.getAddressWithOffset(Offset)));
 889     break;
 890   }
 891   case ELF::R_BPF_64_32: {
 892     Value += Addend;
 893     assert(Value <= UINT32_MAX);
 894     write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
 895     LLVM_DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
 896                       << format("%p\n", Section.getAddressWithOffset(Offset)));
 897     break;
 898   }
 899   }
 900 }
 901
 902 // The target location for the relocation is described by RE.SectionID and
 903 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
 904 // SectionEntry has three members describing its location.
 905 // SectionEntry::Address is the address at which the section has been loaded
 906 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
 907 // address that the section will have in the target process.
 908 // SectionEntry::ObjAddress is the address of the bits for this section in the
 909 // original emitted object image (also in the current address space).
 910 //
 911 // Relocations will be applied as if the section were loaded at
 912 // SectionEntry::LoadAddress, but they will be applied at an address based
 913 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
 914 // Target memory contents if they are required for value calculations.
 915 //
 916 // The Value parameter here is the load address of the symbol for the
 917 // relocation to be applied.  For relocations which refer to symbols in the
 918 // current object Value will be the LoadAddress of the section in which
 919 // the symbol resides (RE.Addend provides additional information about the
 920 // symbol location).  For external symbols, Value will be the address of the
 921 // symbol in the target address space.
 922 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
 923                                        uint64_t Value) {
 924   const SectionEntry &Section = Sections[RE.SectionID];
 925   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
 926                            RE.SymOffset, RE.SectionID);
 927 }
 928
 929 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
 930                                        uint64_t Offset, uint64_t Value,
 931                                        uint32_t Type, int64_t Addend,
 932                                        uint64_t SymOffset, SID SectionID) {
 933   switch (Arch) {
 934   case Triple::x86_64:
 935     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
 936     break;
 937   case Triple::x86:
 938     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
 939                          (uint32_t)(Addend & 0xffffffffL));
 940     break;
 941   case Triple::aarch64:
 942   case Triple::aarch64_be:
 943     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
 944     break;
 945   case Triple::arm: // Fall through.
 946   case Triple::armeb:
 947   case Triple::thumb:
 948   case Triple::thumbeb:
 949     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
 950                          (uint32_t)(Addend & 0xffffffffL));
 951     break;
 952   case Triple::ppc:
 953     resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
 954     break;
 955   case Triple::ppc64: // Fall through.
 956   case Triple::ppc64le:
 957     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
 958     break;
 959   case Triple::systemz:
 960     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
 961     break;
 962   case Triple::bpfel:
 963   case Triple::bpfeb:
 964     resolveBPFRelocation(Section, Offset, Value, Type, Addend);
 965     break;
 966   default:
 967     llvm_unreachable("Unsupported CPU type!");
 968   }
 969 }
 970
 971 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
 972   return (void *)(Sections[SectionID].getObjAddress() + Offset);
 973 }
 974
 975 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
 976   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
 977   if (Value.SymbolName)
 978     addRelocationForSymbol(RE, Value.SymbolName);
 979   else
 980     addRelocationForSection(RE, Value.SectionID);
 981 }
 982
 983 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
 984                                                  bool IsLocal) const {
 985   switch (RelType) {
 986   case ELF::R_MICROMIPS_GOT16:
 987     if (IsLocal)
 988       return ELF::R_MICROMIPS_LO16;
 989     break;
 990   case ELF::R_MICROMIPS_HI16:
 991     return ELF::R_MICROMIPS_LO16;
 992   case ELF::R_MIPS_GOT16:
 993     if (IsLocal)
 994       return ELF::R_MIPS_LO16;
 995     break;
 996   case ELF::R_MIPS_HI16:
 997     return ELF::R_MIPS_LO16;
 998   case ELF::R_MIPS_PCHI16:
 999     return ELF::R_MIPS_PCLO16;
1000   default:
1001     break;
1002   }
1003   return ELF::R_MIPS_NONE;
1004 }
1005
1006 // Sometimes we don't need to create thunk for a branch.
1007 // This typically happens when branch target is located
1008 // in the same object file. In such case target is either
1009 // a weak symbol or symbol in a different executable section.
1010 // This function checks if branch target is located in the
1011 // same object file and if distance between source and target
1012 // fits R_AARCH64_CALL26 relocation. If both conditions are
1013 // met, it emits direct jump to the target and returns true.
1014 // Otherwise false is returned and thunk is created.
1015 bool RuntimeDyldELF::resolveAArch64ShortBranch(
1016     unsigned SectionID, relocation_iterator RelI,
1017     const RelocationValueRef &Value) {
1018   uint64_t Address;
1019   if (Value.SymbolName) {
1020     auto Loc = GlobalSymbolTable.find(Value.SymbolName);
1021
1022     // Don't create direct branch for external symbols.
1023     if (Loc == GlobalSymbolTable.end())
1024       return false;
1025
1026     const auto &SymInfo = Loc->second;
1027     Address =
1028         uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset(
1029             SymInfo.getOffset()));
1030   } else {
1031     Address = uint64_t(Sections[Value.SectionID].getLoadAddress());
1032   }
1033   uint64_t Offset = RelI->getOffset();
1034   uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset);
1035
1036   // R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27
1037   // If distance between source and target is out of range then we should
1038   // create thunk.
1039   if (!isInt<28>(Address + Value.Addend - SourceAddress))
1040     return false;
1041
1042   resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(),
1043                     Value.Addend);
1044
1045   return true;
1046 }
1047
1048 void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID,
1049                                           const RelocationValueRef &Value,
1050                                           relocation_iterator RelI,
1051                                           StubMap &Stubs) {
1052
1053   LLVM_DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1054   SectionEntry &Section = Sections[SectionID];
1055
1056   uint64_t Offset = RelI->getOffset();
1057   unsigned RelType = RelI->getType();
1058   // Look for an existing stub.
1059   StubMap::const_iterator i = Stubs.find(Value);
1060   if (i != Stubs.end()) {
1061     resolveRelocation(Section, Offset,
1062                       (uint64_t)Section.getAddressWithOffset(i->second),
1063                       RelType, 0);
1064     LLVM_DEBUG(dbgs() << " Stub function found\n");
1065   } else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) {
1066     // Create a new stub function.
1067     LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1068     Stubs[Value] = Section.getStubOffset();
1069     uint8_t *StubTargetAddr = createStubFunction(
1070         Section.getAddressWithOffset(Section.getStubOffset()));
1071
1072     RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(),
1073                               ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1074     RelocationEntry REmovk_g2(SectionID,
1075                               StubTargetAddr - Section.getAddress() + 4,
1076                               ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1077     RelocationEntry REmovk_g1(SectionID,
1078                               StubTargetAddr - Section.getAddress() + 8,
1079                               ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1080     RelocationEntry REmovk_g0(SectionID,
1081                               StubTargetAddr - Section.getAddress() + 12,
1082                               ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1083
1084     if (Value.SymbolName) {
1085       addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1086       addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1087       addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1088       addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1089     } else {
1090       addRelocationForSection(REmovz_g3, Value.SectionID);
1091       addRelocationForSection(REmovk_g2, Value.SectionID);
1092       addRelocationForSection(REmovk_g1, Value.SectionID);
1093       addRelocationForSection(REmovk_g0, Value.SectionID);
1094     }
1095     resolveRelocation(Section, Offset,
1096                       reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
1097                           Section.getStubOffset())),
1098                       RelType, 0);
1099     Section.advanceStubOffset(getMaxStubSize());
1100   }
1101 }
1102
1103 Expected<relocation_iterator>
1104 RuntimeDyldELF::processRelocationRef(
1105     unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1106     ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1107   const auto &Obj = cast<ELFObjectFileBase>(O);
1108   uint64_t RelType = RelI->getType();
1109   int64_t Addend = 0;
1110   if (Expected<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend())
1111     Addend = *AddendOrErr;
1112   else
1113     consumeError(AddendOrErr.takeError());
1114   elf_symbol_iterator Symbol = RelI->getSymbol();
1115
1116   // Obtain the symbol name which is referenced in the relocation
1117   StringRef TargetName;
1118   if (Symbol != Obj.symbol_end()) {
1119     if (auto TargetNameOrErr = Symbol->getName())
1120       TargetName = *TargetNameOrErr;
1121     else
1122       return TargetNameOrErr.takeError();
1123   }
1124   LLVM_DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1125                     << " TargetName: " << TargetName << "\n");
1126   RelocationValueRef Value;
1127   // First search for the symbol in the local symbol table
1128   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1129
1130   // Search for the symbol in the global symbol table
1131   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1132   if (Symbol != Obj.symbol_end()) {
1133     gsi = GlobalSymbolTable.find(TargetName.data());
1134     Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType();
1135     if (!SymTypeOrErr) {
1136       std::string Buf;
1137       raw_string_ostream OS(Buf);
1138       logAllUnhandledErrors(SymTypeOrErr.takeError(), OS);
1139       OS.flush();
1140       report_fatal_error(Buf);
1141     }
1142     SymType = *SymTypeOrErr;
1143   }
1144   if (gsi != GlobalSymbolTable.end()) {
1145     const auto &SymInfo = gsi->second;
1146     Value.SectionID = SymInfo.getSectionID();
1147     Value.Offset = SymInfo.getOffset();
1148     Value.Addend = SymInfo.getOffset() + Addend;
1149   } else {
1150     switch (SymType) {
1151     case SymbolRef::ST_Debug: {
1152       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1153       // and can be changed by another developers. Maybe best way is add
1154       // a new symbol type ST_Section to SymbolRef and use it.
1155       auto SectionOrErr = Symbol->getSection();
1156       if (!SectionOrErr) {
1157         std::string Buf;
1158         raw_string_ostream OS(Buf);
1159         logAllUnhandledErrors(SectionOrErr.takeError(), OS);
1160         OS.flush();
1161         report_fatal_error(Buf);
1162       }
1163       section_iterator si = *SectionOrErr;
1164       if (si == Obj.section_end())
1165         llvm_unreachable("Symbol section not found, bad object file format!");
1166       LLVM_DEBUG(dbgs() << "\t\tThis is section symbol\n");
1167       bool isCode = si->isText();
1168       if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode,
1169                                                   ObjSectionToID))
1170         Value.SectionID = *SectionIDOrErr;
1171       else
1172         return SectionIDOrErr.takeError();
1173       Value.Addend = Addend;
1174       break;
1175     }
1176     case SymbolRef::ST_Data:
1177     case SymbolRef::ST_Function:
1178     case SymbolRef::ST_Unknown: {
1179       Value.SymbolName = TargetName.data();
1180       Value.Addend = Addend;
1181
1182       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1183       // will manifest here as a NULL symbol name.
1184       // We can set this as a valid (but empty) symbol name, and rely
1185       // on addRelocationForSymbol to handle this.
1186       if (!Value.SymbolName)
1187         Value.SymbolName = "";
1188       break;
1189     }
1190     default:
1191       llvm_unreachable("Unresolved symbol type!");
1192       break;
1193     }
1194   }
1195
1196   uint64_t Offset = RelI->getOffset();
1197
1198   LLVM_DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1199                     << "\n");
1200   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) {
1201     if (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26) {
1202       resolveAArch64Branch(SectionID, Value, RelI, Stubs);
1203     } else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) {
1204       // Craete new GOT entry or find existing one. If GOT entry is
1205       // to be created, then we also emit ABS64 relocation for it.
1206       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1207       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1208                                  ELF::R_AARCH64_ADR_PREL_PG_HI21);
1209
1210     } else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) {
1211       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1212       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1213                                  ELF::R_AARCH64_LDST64_ABS_LO12_NC);
1214     } else {
1215       processSimpleRelocation(SectionID, Offset, RelType, Value);
1216     }
1217   } else if (Arch == Triple::arm) {
1218     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1219       RelType == ELF::R_ARM_JUMP24) {
1220       // This is an ARM branch relocation, need to use a stub function.
1221       LLVM_DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n");
1222       SectionEntry &Section = Sections[SectionID];
1223
1224       // Look for an existing stub.
1225       StubMap::const_iterator i = Stubs.find(Value);
1226       if (i != Stubs.end()) {
1227         resolveRelocation(
1228             Section, Offset,
1229             reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
1230             RelType, 0);
1231         LLVM_DEBUG(dbgs() << " Stub function found\n");
1232       } else {
1233         // Create a new stub function.
1234         LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1235         Stubs[Value] = Section.getStubOffset();
1236         uint8_t *StubTargetAddr = createStubFunction(
1237             Section.getAddressWithOffset(Section.getStubOffset()));
1238         RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1239                            ELF::R_ARM_ABS32, Value.Addend);
1240         if (Value.SymbolName)
1241           addRelocationForSymbol(RE, Value.SymbolName);
1242         else
1243           addRelocationForSection(RE, Value.SectionID);
1244
1245         resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1246                                                Section.getAddressWithOffset(
1247                                                    Section.getStubOffset())),
1248                           RelType, 0);
1249         Section.advanceStubOffset(getMaxStubSize());
1250       }
1251     } else {
1252       uint32_t *Placeholder =
1253         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1254       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1255           RelType == ELF::R_ARM_ABS32) {
1256         Value.Addend += *Placeholder;
1257       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1258         // See ELF for ARM documentation
1259         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1260       }
1261       processSimpleRelocation(SectionID, Offset, RelType, Value);
1262     }
1263   } else if (IsMipsO32ABI) {
1264     uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1265         computePlaceholderAddress(SectionID, Offset));
1266     uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1267     if (RelType == ELF::R_MIPS_26) {
1268       // This is an Mips branch relocation, need to use a stub function.
1269       LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1270       SectionEntry &Section = Sections[SectionID];
1271
1272       // Extract the addend from the instruction.
1273       // We shift up by two since the Value will be down shifted again
1274       // when applying the relocation.
1275       uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1276
1277       Value.Addend += Addend;
1278
1279       //  Look up for existing stub.
1280       StubMap::const_iterator i = Stubs.find(Value);
1281       if (i != Stubs.end()) {
1282         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1283         addRelocationForSection(RE, SectionID);
1284         LLVM_DEBUG(dbgs() << " Stub function found\n");
1285       } else {
1286         // Create a new stub function.
1287         LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1288         Stubs[Value] = Section.getStubOffset();
1289
1290         unsigned AbiVariant = Obj.getPlatformFlags();
1291
1292         uint8_t *StubTargetAddr = createStubFunction(
1293             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1294
1295         // Creating Hi and Lo relocations for the filled stub instructions.
1296         RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1297                              ELF::R_MIPS_HI16, Value.Addend);
1298         RelocationEntry RELo(SectionID,
1299                              StubTargetAddr - Section.getAddress() + 4,
1300                              ELF::R_MIPS_LO16, Value.Addend);
1301
1302         if (Value.SymbolName) {
1303           addRelocationForSymbol(REHi, Value.SymbolName);
1304           addRelocationForSymbol(RELo, Value.SymbolName);
1305         } else {
1306           addRelocationForSection(REHi, Value.SectionID);
1307           addRelocationForSection(RELo, Value.SectionID);
1308         }
1309
1310         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1311         addRelocationForSection(RE, SectionID);
1312         Section.advanceStubOffset(getMaxStubSize());
1313       }
1314     } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
1315       int64_t Addend = (Opcode & 0x0000ffff) << 16;
1316       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1317       PendingRelocs.push_back(std::make_pair(Value, RE));
1318     } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
1319       int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
1320       for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
1321         const RelocationValueRef &MatchingValue = I->first;
1322         RelocationEntry &Reloc = I->second;
1323         if (MatchingValue == Value &&
1324             RelType == getMatchingLoRelocation(Reloc.RelType) &&
1325             SectionID == Reloc.SectionID) {
1326           Reloc.Addend += Addend;
1327           if (Value.SymbolName)
1328             addRelocationForSymbol(Reloc, Value.SymbolName);
1329           else
1330             addRelocationForSection(Reloc, Value.SectionID);
1331           I = PendingRelocs.erase(I);
1332         } else
1333           ++I;
1334       }
1335       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1336       if (Value.SymbolName)
1337         addRelocationForSymbol(RE, Value.SymbolName);
1338       else
1339         addRelocationForSection(RE, Value.SectionID);
1340     } else {
1341       if (RelType == ELF::R_MIPS_32)
1342         Value.Addend += Opcode;
1343       else if (RelType == ELF::R_MIPS_PC16)
1344         Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1345       else if (RelType == ELF::R_MIPS_PC19_S2)
1346         Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1347       else if (RelType == ELF::R_MIPS_PC21_S2)
1348         Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1349       else if (RelType == ELF::R_MIPS_PC26_S2)
1350         Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1351       processSimpleRelocation(SectionID, Offset, RelType, Value);
1352     }
1353   } else if (IsMipsN32ABI || IsMipsN64ABI) {
1354     uint32_t r_type = RelType & 0xff;
1355     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1356     if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1357         || r_type == ELF::R_MIPS_GOT_DISP) {
1358       StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1359       if (i != GOTSymbolOffsets.end())
1360         RE.SymOffset = i->second;
1361       else {
1362         RE.SymOffset = allocateGOTEntries(1);
1363         GOTSymbolOffsets[TargetName] = RE.SymOffset;
1364       }
1365       if (Value.SymbolName)
1366         addRelocationForSymbol(RE, Value.SymbolName);
1367       else
1368         addRelocationForSection(RE, Value.SectionID);
1369     } else if (RelType == ELF::R_MIPS_26) {
1370       // This is an Mips branch relocation, need to use a stub function.
1371       LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1372       SectionEntry &Section = Sections[SectionID];
1373
1374       //  Look up for existing stub.
1375       StubMap::const_iterator i = Stubs.find(Value);
1376       if (i != Stubs.end()) {
1377         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1378         addRelocationForSection(RE, SectionID);
1379         LLVM_DEBUG(dbgs() << " Stub function found\n");
1380       } else {
1381         // Create a new stub function.
1382         LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1383         Stubs[Value] = Section.getStubOffset();
1384
1385         unsigned AbiVariant = Obj.getPlatformFlags();
1386
1387         uint8_t *StubTargetAddr = createStubFunction(
1388             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1389
1390         if (IsMipsN32ABI) {
1391           // Creating Hi and Lo relocations for the filled stub instructions.
1392           RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1393                                ELF::R_MIPS_HI16, Value.Addend);
1394           RelocationEntry RELo(SectionID,
1395                                StubTargetAddr - Section.getAddress() + 4,
1396                                ELF::R_MIPS_LO16, Value.Addend);
1397           if (Value.SymbolName) {
1398             addRelocationForSymbol(REHi, Value.SymbolName);
1399             addRelocationForSymbol(RELo, Value.SymbolName);
1400           } else {
1401             addRelocationForSection(REHi, Value.SectionID);
1402             addRelocationForSection(RELo, Value.SectionID);
1403           }
1404         } else {
1405           // Creating Highest, Higher, Hi and Lo relocations for the filled stub
1406           // instructions.
1407           RelocationEntry REHighest(SectionID,
1408                                     StubTargetAddr - Section.getAddress(),
1409                                     ELF::R_MIPS_HIGHEST, Value.Addend);
1410           RelocationEntry REHigher(SectionID,
1411                                    StubTargetAddr - Section.getAddress() + 4,
1412                                    ELF::R_MIPS_HIGHER, Value.Addend);
1413           RelocationEntry REHi(SectionID,
1414                                StubTargetAddr - Section.getAddress() + 12,
1415                                ELF::R_MIPS_HI16, Value.Addend);
1416           RelocationEntry RELo(SectionID,
1417                                StubTargetAddr - Section.getAddress() + 20,
1418                                ELF::R_MIPS_LO16, Value.Addend);
1419           if (Value.SymbolName) {
1420             addRelocationForSymbol(REHighest, Value.SymbolName);
1421             addRelocationForSymbol(REHigher, Value.SymbolName);
1422             addRelocationForSymbol(REHi, Value.SymbolName);
1423             addRelocationForSymbol(RELo, Value.SymbolName);
1424           } else {
1425             addRelocationForSection(REHighest, Value.SectionID);
1426             addRelocationForSection(REHigher, Value.SectionID);
1427             addRelocationForSection(REHi, Value.SectionID);
1428             addRelocationForSection(RELo, Value.SectionID);
1429           }
1430         }
1431         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1432         addRelocationForSection(RE, SectionID);
1433         Section.advanceStubOffset(getMaxStubSize());
1434       }
1435     } else {
1436       processSimpleRelocation(SectionID, Offset, RelType, Value);
1437     }
1438
1439   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1440     if (RelType == ELF::R_PPC64_REL24) {
1441       // Determine ABI variant in use for this object.
1442       unsigned AbiVariant = Obj.getPlatformFlags();
1443       AbiVariant &= ELF::EF_PPC64_ABI;
1444       // A PPC branch relocation will need a stub function if the target is
1445       // an external symbol (either Value.SymbolName is set, or SymType is
1446       // Symbol::ST_Unknown) or if the target address is not within the
1447       // signed 24-bits branch address.
1448       SectionEntry &Section = Sections[SectionID];
1449       uint8_t *Target = Section.getAddressWithOffset(Offset);
1450       bool RangeOverflow = false;
1451       bool IsExtern = Value.SymbolName || SymType == SymbolRef::ST_Unknown;
1452       if (!IsExtern) {
1453         if (AbiVariant != 2) {
1454           // In the ELFv1 ABI, a function call may point to the .opd entry,
1455           // so the final symbol value is calculated based on the relocation
1456           // values in the .opd section.
1457           if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value))
1458             return std::move(Err);
1459         } else {
1460           // In the ELFv2 ABI, a function symbol may provide a local entry
1461           // point, which must be used for direct calls.
1462           if (Value.SectionID == SectionID){
1463             uint8_t SymOther = Symbol->getOther();
1464             Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1465           }
1466         }
1467         uint8_t *RelocTarget =
1468             Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
1469         int64_t delta = static_cast<int64_t>(Target - RelocTarget);
1470         // If it is within 26-bits branch range, just set the branch target
1471         if (SignExtend64<26>(delta) != delta) {
1472           RangeOverflow = true;
1473         } else if ((AbiVariant != 2) ||
1474                    (AbiVariant == 2  && Value.SectionID == SectionID)) {
1475           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1476           addRelocationForSection(RE, Value.SectionID);
1477         }
1478       }
1479       if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID) ||
1480           RangeOverflow) {
1481         // It is an external symbol (either Value.SymbolName is set, or
1482         // SymType is SymbolRef::ST_Unknown) or out of range.
1483         StubMap::const_iterator i = Stubs.find(Value);
1484         if (i != Stubs.end()) {
1485           // Symbol function stub already created, just relocate to it
1486           resolveRelocation(Section, Offset,
1487                             reinterpret_cast<uint64_t>(
1488                                 Section.getAddressWithOffset(i->second)),
1489                             RelType, 0);
1490           LLVM_DEBUG(dbgs() << " Stub function found\n");
1491         } else {
1492           // Create a new stub function.
1493           LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1494           Stubs[Value] = Section.getStubOffset();
1495           uint8_t *StubTargetAddr = createStubFunction(
1496               Section.getAddressWithOffset(Section.getStubOffset()),
1497               AbiVariant);
1498           RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1499                              ELF::R_PPC64_ADDR64, Value.Addend);
1500
1501           // Generates the 64-bits address loads as exemplified in section
1502           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1503           // apply to the low part of the instructions, so we have to update
1504           // the offset according to the target endianness.
1505           uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
1506           if (!IsTargetLittleEndian)
1507             StubRelocOffset += 2;
1508
1509           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1510                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1511           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1512                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1513           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1514                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1515           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1516                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1517
1518           if (Value.SymbolName) {
1519             addRelocationForSymbol(REhst, Value.SymbolName);
1520             addRelocationForSymbol(REhr, Value.SymbolName);
1521             addRelocationForSymbol(REh, Value.SymbolName);
1522             addRelocationForSymbol(REl, Value.SymbolName);
1523           } else {
1524             addRelocationForSection(REhst, Value.SectionID);
1525             addRelocationForSection(REhr, Value.SectionID);
1526             addRelocationForSection(REh, Value.SectionID);
1527             addRelocationForSection(REl, Value.SectionID);
1528           }
1529
1530           resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1531                                                  Section.getAddressWithOffset(
1532                                                      Section.getStubOffset())),
1533                             RelType, 0);
1534           Section.advanceStubOffset(getMaxStubSize());
1535         }
1536         if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID)) {
1537           // Restore the TOC for external calls
1538           if (AbiVariant == 2)
1539             writeInt32BE(Target + 4, 0xE8410018); // ld r2,24(r1)
1540           else
1541             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1542         }
1543       }
1544     } else if (RelType == ELF::R_PPC64_TOC16 ||
1545                RelType == ELF::R_PPC64_TOC16_DS ||
1546                RelType == ELF::R_PPC64_TOC16_LO ||
1547                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1548                RelType == ELF::R_PPC64_TOC16_HI ||
1549                RelType == ELF::R_PPC64_TOC16_HA) {
1550       // These relocations are supposed to subtract the TOC address from
1551       // the final value.  This does not fit cleanly into the RuntimeDyld
1552       // scheme, since there may be *two* sections involved in determining
1553       // the relocation value (the section of the symbol referred to by the
1554       // relocation, and the TOC section associated with the current module).
1555       //
1556       // Fortunately, these relocations are currently only ever generated
1557       // referring to symbols that themselves reside in the TOC, which means
1558       // that the two sections are actually the same.  Thus they cancel out
1559       // and we can immediately resolve the relocation right now.
1560       switch (RelType) {
1561       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1562       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1563       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1564       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1565       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1566       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1567       default: llvm_unreachable("Wrong relocation type.");
1568       }
1569
1570       RelocationValueRef TOCValue;
1571       if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue))
1572         return std::move(Err);
1573       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1574         llvm_unreachable("Unsupported TOC relocation.");
1575       Value.Addend -= TOCValue.Addend;
1576       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1577     } else {
1578       // There are two ways to refer to the TOC address directly: either
1579       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1580       // ignored), or via any relocation that refers to the magic ".TOC."
1581       // symbols (in which case the addend is respected).
1582       if (RelType == ELF::R_PPC64_TOC) {
1583         RelType = ELF::R_PPC64_ADDR64;
1584         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1585           return std::move(Err);
1586       } else if (TargetName == ".TOC.") {
1587         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1588           return std::move(Err);
1589         Value.Addend += Addend;
1590       }
1591
1592       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1593
1594       if (Value.SymbolName)
1595         addRelocationForSymbol(RE, Value.SymbolName);
1596       else
1597         addRelocationForSection(RE, Value.SectionID);
1598     }
1599   } else if (Arch == Triple::systemz &&
1600              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1601     // Create function stubs for both PLT and GOT references, regardless of
1602     // whether the GOT reference is to data or code.  The stub contains the
1603     // full address of the symbol, as needed by GOT references, and the
1604     // executable part only adds an overhead of 8 bytes.
1605     //
1606     // We could try to conserve space by allocating the code and data
1607     // parts of the stub separately.  However, as things stand, we allocate
1608     // a stub for every relocation, so using a GOT in JIT code should be
1609     // no less space efficient than using an explicit constant pool.
1610     LLVM_DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1611     SectionEntry &Section = Sections[SectionID];
1612
1613     // Look for an existing stub.
1614     StubMap::const_iterator i = Stubs.find(Value);
1615     uintptr_t StubAddress;
1616     if (i != Stubs.end()) {
1617       StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
1618       LLVM_DEBUG(dbgs() << " Stub function found\n");
1619     } else {
1620       // Create a new stub function.
1621       LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1622
1623       uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1624       uintptr_t StubAlignment = getStubAlignment();
1625       StubAddress =
1626           (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1627           -StubAlignment;
1628       unsigned StubOffset = StubAddress - BaseAddress;
1629
1630       Stubs[Value] = StubOffset;
1631       createStubFunction((uint8_t *)StubAddress);
1632       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1633                          Value.Offset);
1634       if (Value.SymbolName)
1635         addRelocationForSymbol(RE, Value.SymbolName);
1636       else
1637         addRelocationForSection(RE, Value.SectionID);
1638       Section.advanceStubOffset(getMaxStubSize());
1639     }
1640
1641     if (RelType == ELF::R_390_GOTENT)
1642       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1643                         Addend);
1644     else
1645       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1646   } else if (Arch == Triple::x86_64) {
1647     if (RelType == ELF::R_X86_64_PLT32) {
1648       // The way the PLT relocations normally work is that the linker allocates
1649       // the
1650       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1651       // entry will then jump to an address provided by the GOT.  On first call,
1652       // the
1653       // GOT address will point back into PLT code that resolves the symbol. After
1654       // the first call, the GOT entry points to the actual function.
1655       //
1656       // For local functions we're ignoring all of that here and just replacing
1657       // the PLT32 relocation type with PC32, which will translate the relocation
1658       // into a PC-relative call directly to the function. For external symbols we
1659       // can't be sure the function will be within 2^32 bytes of the call site, so
1660       // we need to create a stub, which calls into the GOT.  This case is
1661       // equivalent to the usual PLT implementation except that we use the stub
1662       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1663       // rather than allocating a PLT section.
1664       if (Value.SymbolName) {
1665         // This is a call to an external function.
1666         // Look for an existing stub.
1667         SectionEntry &Section = Sections[SectionID];
1668         StubMap::const_iterator i = Stubs.find(Value);
1669         uintptr_t StubAddress;
1670         if (i != Stubs.end()) {
1671           StubAddress = uintptr_t(Section.getAddress()) + i->second;
1672           LLVM_DEBUG(dbgs() << " Stub function found\n");
1673         } else {
1674           // Create a new stub function (equivalent to a PLT entry).
1675           LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1676
1677           uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1678           uintptr_t StubAlignment = getStubAlignment();
1679           StubAddress =
1680               (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1681               -StubAlignment;
1682           unsigned StubOffset = StubAddress - BaseAddress;
1683           Stubs[Value] = StubOffset;
1684           createStubFunction((uint8_t *)StubAddress);
1685
1686           // Bump our stub offset counter
1687           Section.advanceStubOffset(getMaxStubSize());
1688
1689           // Allocate a GOT Entry
1690           uint64_t GOTOffset = allocateGOTEntries(1);
1691
1692           // The load of the GOT address has an addend of -4
1693           resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
1694                                      ELF::R_X86_64_PC32);
1695
1696           // Fill in the value of the symbol we're targeting into the GOT
1697           addRelocationForSymbol(
1698               computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
1699               Value.SymbolName);
1700         }
1701
1702         // Make the target call a call into the stub table.
1703         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1704                           Addend);
1705       } else {
1706         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1707                   Value.Offset);
1708         addRelocationForSection(RE, Value.SectionID);
1709       }
1710     } else if (RelType == ELF::R_X86_64_GOTPCREL ||
1711                RelType == ELF::R_X86_64_GOTPCRELX ||
1712                RelType == ELF::R_X86_64_REX_GOTPCRELX) {
1713       uint64_t GOTOffset = allocateGOTEntries(1);
1714       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1715                                  ELF::R_X86_64_PC32);
1716
1717       // Fill in the value of the symbol we're targeting into the GOT
1718       RelocationEntry RE =
1719           computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1720       if (Value.SymbolName)
1721         addRelocationForSymbol(RE, Value.SymbolName);
1722       else
1723         addRelocationForSection(RE, Value.SectionID);
1724     } else if (RelType == ELF::R_X86_64_GOT64) {
1725       // Fill in a 64-bit GOT offset.
1726       uint64_t GOTOffset = allocateGOTEntries(1);
1727       resolveRelocation(Sections[SectionID], Offset, GOTOffset,
1728                         ELF::R_X86_64_64, 0);
1729
1730       // Fill in the value of the symbol we're targeting into the GOT
1731       RelocationEntry RE =
1732           computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1733       if (Value.SymbolName)
1734         addRelocationForSymbol(RE, Value.SymbolName);
1735       else
1736         addRelocationForSection(RE, Value.SectionID);
1737     } else if (RelType == ELF::R_X86_64_GOTPC64) {
1738       // Materialize the address of the base of the GOT relative to the PC.
1739       // This doesn't create a GOT entry, but it does mean we need a GOT
1740       // section.
1741       (void)allocateGOTEntries(0);
1742       resolveGOTOffsetRelocation(SectionID, Offset, Addend, ELF::R_X86_64_PC64);
1743     } else if (RelType == ELF::R_X86_64_GOTOFF64) {
1744       // GOTOFF relocations ultimately require a section difference relocation.
1745       (void)allocateGOTEntries(0);
1746       processSimpleRelocation(SectionID, Offset, RelType, Value);
1747     } else if (RelType == ELF::R_X86_64_PC32) {
1748       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1749       processSimpleRelocation(SectionID, Offset, RelType, Value);
1750     } else if (RelType == ELF::R_X86_64_PC64) {
1751       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1752       processSimpleRelocation(SectionID, Offset, RelType, Value);
1753     } else {
1754       processSimpleRelocation(SectionID, Offset, RelType, Value);
1755     }
1756   } else {
1757     if (Arch == Triple::x86) {
1758       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1759     }
1760     processSimpleRelocation(SectionID, Offset, RelType, Value);
1761   }
1762   return ++RelI;
1763 }
1764
1765 size_t RuntimeDyldELF::getGOTEntrySize() {
1766   // We don't use the GOT in all of these cases, but it's essentially free
1767   // to put them all here.
1768   size_t Result = 0;
1769   switch (Arch) {
1770   case Triple::x86_64:
1771   case Triple::aarch64:
1772   case Triple::aarch64_be:
1773   case Triple::ppc64:
1774   case Triple::ppc64le:
1775   case Triple::systemz:
1776     Result = sizeof(uint64_t);
1777     break;
1778   case Triple::x86:
1779   case Triple::arm:
1780   case Triple::thumb:
1781     Result = sizeof(uint32_t);
1782     break;
1783   case Triple::mips:
1784   case Triple::mipsel:
1785   case Triple::mips64:
1786   case Triple::mips64el:
1787     if (IsMipsO32ABI || IsMipsN32ABI)
1788       Result = sizeof(uint32_t);
1789     else if (IsMipsN64ABI)
1790       Result = sizeof(uint64_t);
1791     else
1792       llvm_unreachable("Mips ABI not handled");
1793     break;
1794   default:
1795     llvm_unreachable("Unsupported CPU type!");
1796   }
1797   return Result;
1798 }
1799
1800 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) {
1801   if (GOTSectionID == 0) {
1802     GOTSectionID = Sections.size();
1803     // Reserve a section id. We'll allocate the section later
1804     // once we know the total size
1805     Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
1806   }
1807   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1808   CurrentGOTIndex += no;
1809   return StartOffset;
1810 }
1811
1812 uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value,
1813                                              unsigned GOTRelType) {
1814   auto E = GOTOffsetMap.insert({Value, 0});
1815   if (E.second) {
1816     uint64_t GOTOffset = allocateGOTEntries(1);
1817
1818     // Create relocation for newly created GOT entry
1819     RelocationEntry RE =
1820         computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType);
1821     if (Value.SymbolName)
1822       addRelocationForSymbol(RE, Value.SymbolName);
1823     else
1824       addRelocationForSection(RE, Value.SectionID);
1825
1826     E.first->second = GOTOffset;
1827   }
1828
1829   return E.first->second;
1830 }
1831
1832 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID,
1833                                                 uint64_t Offset,
1834                                                 uint64_t GOTOffset,
1835                                                 uint32_t Type) {
1836   // Fill in the relative address of the GOT Entry into the stub
1837   RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset);
1838   addRelocationForSection(GOTRE, GOTSectionID);
1839 }
1840
1841 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset,
1842                                                    uint64_t SymbolOffset,
1843                                                    uint32_t Type) {
1844   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1845 }
1846
1847 Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1848                                   ObjSectionToIDMap &SectionMap) {
1849   if (IsMipsO32ABI)
1850     if (!PendingRelocs.empty())
1851       return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
1852
1853   // If necessary, allocate the global offset table
1854   if (GOTSectionID != 0) {
1855     // Allocate memory for the section
1856     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1857     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1858                                                 GOTSectionID, ".got", false);
1859     if (!Addr)
1860       return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!");
1861
1862     Sections[GOTSectionID] =
1863         SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
1864
1865     // For now, initialize all GOT entries to zero.  We'll fill them in as
1866     // needed when GOT-based relocations are applied.
1867     memset(Addr, 0, TotalSize);
1868     if (IsMipsN32ABI || IsMipsN64ABI) {
1869       // To correctly resolve Mips GOT relocations, we need a mapping from
1870       // object's sections to GOTs.
1871       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1872            SI != SE; ++SI) {
1873         if (SI->relocation_begin() != SI->relocation_end()) {
1874           section_iterator RelocatedSection = SI->getRelocatedSection();
1875           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1876           assert (i != SectionMap.end());
1877           SectionToGOTMap[i->second] = GOTSectionID;
1878         }
1879       }
1880       GOTSymbolOffsets.clear();
1881     }
1882   }
1883
1884   // Look for and record the EH frame section.
1885   ObjSectionToIDMap::iterator i, e;
1886   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1887     const SectionRef &Section = i->first;
1888
1889     StringRef Name;
1890     Expected<StringRef> NameOrErr = Section.getName();
1891     if (NameOrErr)
1892       Name = *NameOrErr;
1893     else
1894       consumeError(NameOrErr.takeError());
1895
1896     if (Name == ".eh_frame") {
1897       UnregisteredEHFrameSections.push_back(i->second);
1898       break;
1899     }
1900   }
1901
1902   GOTSectionID = 0;
1903   CurrentGOTIndex = 0;
1904
1905   return Error::success();
1906 }
1907
1908 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1909   return Obj.isELF();
1910 }
1911
1912 bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const {
1913   unsigned RelTy = R.getType();
1914   if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
1915     return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE ||
1916            RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC;
1917
1918   if (Arch == Triple::x86_64)
1919     return RelTy == ELF::R_X86_64_GOTPCREL ||
1920            RelTy == ELF::R_X86_64_GOTPCRELX ||
1921            RelTy == ELF::R_X86_64_GOT64 ||
1922            RelTy == ELF::R_X86_64_REX_GOTPCRELX;
1923   return false;
1924 }
1925
1926 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
1927   if (Arch != Triple::x86_64)
1928     return true;  // Conservative answer
1929
1930   switch (R.getType()) {
1931   default:
1932     return true;  // Conservative answer
1933
1934
1935   case ELF::R_X86_64_GOTPCREL:
1936   case ELF::R_X86_64_GOTPCRELX:
1937   case ELF::R_X86_64_REX_GOTPCRELX:
1938   case ELF::R_X86_64_GOTPC64:
1939   case ELF::R_X86_64_GOT64:
1940   case ELF::R_X86_64_GOTOFF64:
1941   case ELF::R_X86_64_PC32:
1942   case ELF::R_X86_64_PC64:
1943   case ELF::R_X86_64_64:
1944     // We know that these reloation types won't need a stub function.  This list
1945     // can be extended as needed.
1946     return false;
1947   }
1948 }
1949
1950 } // namespace llvm