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
 610     Expected<section_iterator> RelSecOrErr = si->getRelocatedSection();
 611     if (!RelSecOrErr)
 612       report_fatal_error(toString(RelSecOrErr.takeError()));
 613
 614     section_iterator RelSecI = *RelSecOrErr;
 615     if (RelSecI == Obj.section_end())
 616       continue;
 617
 618     Expected<StringRef> NameOrErr = RelSecI->getName();
 619     if (!NameOrErr)
 620       return NameOrErr.takeError();
 621     StringRef RelSectionName = *NameOrErr;
 622
 623     if (RelSectionName != ".opd")
 624       continue;
 625
 626     for (elf_relocation_iterator i = si->relocation_begin(),
 627                                  e = si->relocation_end();
 628          i != e;) {
 629       // The R_PPC64_ADDR64 relocation indicates the first field
 630       // of a .opd entry
 631       uint64_t TypeFunc = i->getType();
 632       if (TypeFunc != ELF::R_PPC64_ADDR64) {
 633         ++i;
 634         continue;
 635       }
 636
 637       uint64_t TargetSymbolOffset = i->getOffset();
 638       symbol_iterator TargetSymbol = i->getSymbol();
 639       int64_t Addend;
 640       if (auto AddendOrErr = i->getAddend())
 641         Addend = *AddendOrErr;
 642       else
 643         return AddendOrErr.takeError();
 644
 645       ++i;
 646       if (i == e)
 647         break;
 648
 649       // Just check if following relocation is a R_PPC64_TOC
 650       uint64_t TypeTOC = i->getType();
 651       if (TypeTOC != ELF::R_PPC64_TOC)
 652         continue;
 653
 654       // Finally compares the Symbol value and the target symbol offset
 655       // to check if this .opd entry refers to the symbol the relocation
 656       // points to.
 657       if (Rel.Addend != (int64_t)TargetSymbolOffset)
 658         continue;
 659
 660       section_iterator TSI = Obj.section_end();
 661       if (auto TSIOrErr = TargetSymbol->getSection())
 662         TSI = *TSIOrErr;
 663       else
 664         return TSIOrErr.takeError();
 665       assert(TSI != Obj.section_end() && "TSI should refer to a valid section");
 666
 667       bool IsCode = TSI->isText();
 668       if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode,
 669                                                   LocalSections))
 670         Rel.SectionID = *SectionIDOrErr;
 671       else
 672         return SectionIDOrErr.takeError();
 673       Rel.Addend = (intptr_t)Addend;
 674       return Error::success();
 675     }
 676   }
 677   llvm_unreachable("Attempting to get address of ODP entry!");
 678 }
 679
 680 // Relocation masks following the #lo(value), #hi(value), #ha(value),
 681 // #higher(value), #highera(value), #highest(value), and #highesta(value)
 682 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
 683 // document.
 684
 685 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
 686
 687 static inline uint16_t applyPPChi(uint64_t value) {
 688   return (value >> 16) & 0xffff;
 689 }
 690
 691 static inline uint16_t applyPPCha (uint64_t value) {
 692   return ((value + 0x8000) >> 16) & 0xffff;
 693 }
 694
 695 static inline uint16_t applyPPChigher(uint64_t value) {
 696   return (value >> 32) & 0xffff;
 697 }
 698
 699 static inline uint16_t applyPPChighera (uint64_t value) {
 700   return ((value + 0x8000) >> 32) & 0xffff;
 701 }
 702
 703 static inline uint16_t applyPPChighest(uint64_t value) {
 704   return (value >> 48) & 0xffff;
 705 }
 706
 707 static inline uint16_t applyPPChighesta (uint64_t value) {
 708   return ((value + 0x8000) >> 48) & 0xffff;
 709 }
 710
 711 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
 712                                             uint64_t Offset, uint64_t Value,
 713                                             uint32_t Type, int64_t Addend) {
 714   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 715   switch (Type) {
 716   default:
 717     llvm_unreachable("Relocation type not implemented yet!");
 718     break;
 719   case ELF::R_PPC_ADDR16_LO:
 720     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 721     break;
 722   case ELF::R_PPC_ADDR16_HI:
 723     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
 724     break;
 725   case ELF::R_PPC_ADDR16_HA:
 726     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
 727     break;
 728   }
 729 }
 730
 731 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
 732                                             uint64_t Offset, uint64_t Value,
 733                                             uint32_t Type, int64_t Addend) {
 734   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 735   switch (Type) {
 736   default:
 737     llvm_unreachable("Relocation type not implemented yet!");
 738     break;
 739   case ELF::R_PPC64_ADDR16:
 740     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 741     break;
 742   case ELF::R_PPC64_ADDR16_DS:
 743     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
 744     break;
 745   case ELF::R_PPC64_ADDR16_LO:
 746     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 747     break;
 748   case ELF::R_PPC64_ADDR16_LO_DS:
 749     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
 750     break;
 751   case ELF::R_PPC64_ADDR16_HI:
 752   case ELF::R_PPC64_ADDR16_HIGH:
 753     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
 754     break;
 755   case ELF::R_PPC64_ADDR16_HA:
 756   case ELF::R_PPC64_ADDR16_HIGHA:
 757     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
 758     break;
 759   case ELF::R_PPC64_ADDR16_HIGHER:
 760     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
 761     break;
 762   case ELF::R_PPC64_ADDR16_HIGHERA:
 763     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
 764     break;
 765   case ELF::R_PPC64_ADDR16_HIGHEST:
 766     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
 767     break;
 768   case ELF::R_PPC64_ADDR16_HIGHESTA:
 769     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
 770     break;
 771   case ELF::R_PPC64_ADDR14: {
 772     assert(((Value + Addend) & 3) == 0);
 773     // Preserve the AA/LK bits in the branch instruction
 774     uint8_t aalk = *(LocalAddress + 3);
 775     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
 776   } break;
 777   case ELF::R_PPC64_REL16_LO: {
 778     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 779     uint64_t Delta = Value - FinalAddress + Addend;
 780     writeInt16BE(LocalAddress, applyPPClo(Delta));
 781   } break;
 782   case ELF::R_PPC64_REL16_HI: {
 783     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 784     uint64_t Delta = Value - FinalAddress + Addend;
 785     writeInt16BE(LocalAddress, applyPPChi(Delta));
 786   } break;
 787   case ELF::R_PPC64_REL16_HA: {
 788     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 789     uint64_t Delta = Value - FinalAddress + Addend;
 790     writeInt16BE(LocalAddress, applyPPCha(Delta));
 791   } break;
 792   case ELF::R_PPC64_ADDR32: {
 793     int64_t Result = static_cast<int64_t>(Value + Addend);
 794     if (SignExtend64<32>(Result) != Result)
 795       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
 796     writeInt32BE(LocalAddress, Result);
 797   } break;
 798   case ELF::R_PPC64_REL24: {
 799     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 800     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
 801     if (SignExtend64<26>(delta) != delta)
 802       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
 803     // We preserve bits other than LI field, i.e. PO and AA/LK fields.
 804     uint32_t Inst = readBytesUnaligned(LocalAddress, 4);
 805     writeInt32BE(LocalAddress, (Inst & 0xFC000003) | (delta & 0x03FFFFFC));
 806   } break;
 807   case ELF::R_PPC64_REL32: {
 808     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 809     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
 810     if (SignExtend64<32>(delta) != delta)
 811       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
 812     writeInt32BE(LocalAddress, delta);
 813   } break;
 814   case ELF::R_PPC64_REL64: {
 815     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 816     uint64_t Delta = Value - FinalAddress + Addend;
 817     writeInt64BE(LocalAddress, Delta);
 818   } break;
 819   case ELF::R_PPC64_ADDR64:
 820     writeInt64BE(LocalAddress, Value + Addend);
 821     break;
 822   }
 823 }
 824
 825 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
 826                                               uint64_t Offset, uint64_t Value,
 827                                               uint32_t Type, int64_t Addend) {
 828   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 829   switch (Type) {
 830   default:
 831     llvm_unreachable("Relocation type not implemented yet!");
 832     break;
 833   case ELF::R_390_PC16DBL:
 834   case ELF::R_390_PLT16DBL: {
 835     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 836     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
 837     writeInt16BE(LocalAddress, Delta / 2);
 838     break;
 839   }
 840   case ELF::R_390_PC32DBL:
 841   case ELF::R_390_PLT32DBL: {
 842     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 843     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
 844     writeInt32BE(LocalAddress, Delta / 2);
 845     break;
 846   }
 847   case ELF::R_390_PC16: {
 848     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 849     assert(int16_t(Delta) == Delta && "R_390_PC16 overflow");
 850     writeInt16BE(LocalAddress, Delta);
 851     break;
 852   }
 853   case ELF::R_390_PC32: {
 854     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 855     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
 856     writeInt32BE(LocalAddress, Delta);
 857     break;
 858   }
 859   case ELF::R_390_PC64: {
 860     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 861     writeInt64BE(LocalAddress, Delta);
 862     break;
 863   }
 864   case ELF::R_390_8:
 865     *LocalAddress = (uint8_t)(Value + Addend);
 866     break;
 867   case ELF::R_390_16:
 868     writeInt16BE(LocalAddress, Value + Addend);
 869     break;
 870   case ELF::R_390_32:
 871     writeInt32BE(LocalAddress, Value + Addend);
 872     break;
 873   case ELF::R_390_64:
 874     writeInt64BE(LocalAddress, Value + Addend);
 875     break;
 876   }
 877 }
 878
 879 void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
 880                                           uint64_t Offset, uint64_t Value,
 881                                           uint32_t Type, int64_t Addend) {
 882   bool isBE = Arch == Triple::bpfeb;
 883
 884   switch (Type) {
 885   default:
 886     llvm_unreachable("Relocation type not implemented yet!");
 887     break;
 888   case ELF::R_BPF_NONE:
 889     break;
 890   case ELF::R_BPF_64_64: {
 891     write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
 892     LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
 893                       << format("%p\n", Section.getAddressWithOffset(Offset)));
 894     break;
 895   }
 896   case ELF::R_BPF_64_32: {
 897     Value += Addend;
 898     assert(Value <= UINT32_MAX);
 899     write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
 900     LLVM_DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
 901                       << format("%p\n", Section.getAddressWithOffset(Offset)));
 902     break;
 903   }
 904   }
 905 }
 906
 907 // The target location for the relocation is described by RE.SectionID and
 908 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
 909 // SectionEntry has three members describing its location.
 910 // SectionEntry::Address is the address at which the section has been loaded
 911 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
 912 // address that the section will have in the target process.
 913 // SectionEntry::ObjAddress is the address of the bits for this section in the
 914 // original emitted object image (also in the current address space).
 915 //
 916 // Relocations will be applied as if the section were loaded at
 917 // SectionEntry::LoadAddress, but they will be applied at an address based
 918 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
 919 // Target memory contents if they are required for value calculations.
 920 //
 921 // The Value parameter here is the load address of the symbol for the
 922 // relocation to be applied.  For relocations which refer to symbols in the
 923 // current object Value will be the LoadAddress of the section in which
 924 // the symbol resides (RE.Addend provides additional information about the
 925 // symbol location).  For external symbols, Value will be the address of the
 926 // symbol in the target address space.
 927 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
 928                                        uint64_t Value) {
 929   const SectionEntry &Section = Sections[RE.SectionID];
 930   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
 931                            RE.SymOffset, RE.SectionID);
 932 }
 933
 934 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
 935                                        uint64_t Offset, uint64_t Value,
 936                                        uint32_t Type, int64_t Addend,
 937                                        uint64_t SymOffset, SID SectionID) {
 938   switch (Arch) {
 939   case Triple::x86_64:
 940     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
 941     break;
 942   case Triple::x86:
 943     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
 944                          (uint32_t)(Addend & 0xffffffffL));
 945     break;
 946   case Triple::aarch64:
 947   case Triple::aarch64_be:
 948     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
 949     break;
 950   case Triple::arm: // Fall through.
 951   case Triple::armeb:
 952   case Triple::thumb:
 953   case Triple::thumbeb:
 954     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
 955                          (uint32_t)(Addend & 0xffffffffL));
 956     break;
 957   case Triple::ppc:
 958     resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
 959     break;
 960   case Triple::ppc64: // Fall through.
 961   case Triple::ppc64le:
 962     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
 963     break;
 964   case Triple::systemz:
 965     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
 966     break;
 967   case Triple::bpfel:
 968   case Triple::bpfeb:
 969     resolveBPFRelocation(Section, Offset, Value, Type, Addend);
 970     break;
 971   default:
 972     llvm_unreachable("Unsupported CPU type!");
 973   }
 974 }
 975
 976 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
 977   return (void *)(Sections[SectionID].getObjAddress() + Offset);
 978 }
 979
 980 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
 981   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
 982   if (Value.SymbolName)
 983     addRelocationForSymbol(RE, Value.SymbolName);
 984   else
 985     addRelocationForSection(RE, Value.SectionID);
 986 }
 987
 988 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
 989                                                  bool IsLocal) const {
 990   switch (RelType) {
 991   case ELF::R_MICROMIPS_GOT16:
 992     if (IsLocal)
 993       return ELF::R_MICROMIPS_LO16;
 994     break;
 995   case ELF::R_MICROMIPS_HI16:
 996     return ELF::R_MICROMIPS_LO16;
 997   case ELF::R_MIPS_GOT16:
 998     if (IsLocal)
 999       return ELF::R_MIPS_LO16;
1000     break;
1001   case ELF::R_MIPS_HI16:
1002     return ELF::R_MIPS_LO16;
1003   case ELF::R_MIPS_PCHI16:
1004     return ELF::R_MIPS_PCLO16;
1005   default:
1006     break;
1007   }
1008   return ELF::R_MIPS_NONE;
1009 }
1010
1011 // Sometimes we don't need to create thunk for a branch.
1012 // This typically happens when branch target is located
1013 // in the same object file. In such case target is either
1014 // a weak symbol or symbol in a different executable section.
1015 // This function checks if branch target is located in the
1016 // same object file and if distance between source and target
1017 // fits R_AARCH64_CALL26 relocation. If both conditions are
1018 // met, it emits direct jump to the target and returns true.
1019 // Otherwise false is returned and thunk is created.
1020 bool RuntimeDyldELF::resolveAArch64ShortBranch(
1021     unsigned SectionID, relocation_iterator RelI,
1022     const RelocationValueRef &Value) {
1023   uint64_t Address;
1024   if (Value.SymbolName) {
1025     auto Loc = GlobalSymbolTable.find(Value.SymbolName);
1026
1027     // Don't create direct branch for external symbols.
1028     if (Loc == GlobalSymbolTable.end())
1029       return false;
1030
1031     const auto &SymInfo = Loc->second;
1032     Address =
1033         uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset(
1034             SymInfo.getOffset()));
1035   } else {
1036     Address = uint64_t(Sections[Value.SectionID].getLoadAddress());
1037   }
1038   uint64_t Offset = RelI->getOffset();
1039   uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset);
1040
1041   // R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27
1042   // If distance between source and target is out of range then we should
1043   // create thunk.
1044   if (!isInt<28>(Address + Value.Addend - SourceAddress))
1045     return false;
1046
1047   resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(),
1048                     Value.Addend);
1049
1050   return true;
1051 }
1052
1053 void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID,
1054                                           const RelocationValueRef &Value,
1055                                           relocation_iterator RelI,
1056                                           StubMap &Stubs) {
1057
1058   LLVM_DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1059   SectionEntry &Section = Sections[SectionID];
1060
1061   uint64_t Offset = RelI->getOffset();
1062   unsigned RelType = RelI->getType();
1063   // Look for an existing stub.
1064   StubMap::const_iterator i = Stubs.find(Value);
1065   if (i != Stubs.end()) {
1066     resolveRelocation(Section, Offset,
1067                       (uint64_t)Section.getAddressWithOffset(i->second),
1068                       RelType, 0);
1069     LLVM_DEBUG(dbgs() << " Stub function found\n");
1070   } else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) {
1071     // Create a new stub function.
1072     LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1073     Stubs[Value] = Section.getStubOffset();
1074     uint8_t *StubTargetAddr = createStubFunction(
1075         Section.getAddressWithOffset(Section.getStubOffset()));
1076
1077     RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(),
1078                               ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1079     RelocationEntry REmovk_g2(SectionID,
1080                               StubTargetAddr - Section.getAddress() + 4,
1081                               ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1082     RelocationEntry REmovk_g1(SectionID,
1083                               StubTargetAddr - Section.getAddress() + 8,
1084                               ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1085     RelocationEntry REmovk_g0(SectionID,
1086                               StubTargetAddr - Section.getAddress() + 12,
1087                               ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1088
1089     if (Value.SymbolName) {
1090       addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1091       addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1092       addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1093       addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1094     } else {
1095       addRelocationForSection(REmovz_g3, Value.SectionID);
1096       addRelocationForSection(REmovk_g2, Value.SectionID);
1097       addRelocationForSection(REmovk_g1, Value.SectionID);
1098       addRelocationForSection(REmovk_g0, Value.SectionID);
1099     }
1100     resolveRelocation(Section, Offset,
1101                       reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
1102                           Section.getStubOffset())),
1103                       RelType, 0);
1104     Section.advanceStubOffset(getMaxStubSize());
1105   }
1106 }
1107
1108 Expected<relocation_iterator>
1109 RuntimeDyldELF::processRelocationRef(
1110     unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1111     ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1112   const auto &Obj = cast<ELFObjectFileBase>(O);
1113   uint64_t RelType = RelI->getType();
1114   int64_t Addend = 0;
1115   if (Expected<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend())
1116     Addend = *AddendOrErr;
1117   else
1118     consumeError(AddendOrErr.takeError());
1119   elf_symbol_iterator Symbol = RelI->getSymbol();
1120
1121   // Obtain the symbol name which is referenced in the relocation
1122   StringRef TargetName;
1123   if (Symbol != Obj.symbol_end()) {
1124     if (auto TargetNameOrErr = Symbol->getName())
1125       TargetName = *TargetNameOrErr;
1126     else
1127       return TargetNameOrErr.takeError();
1128   }
1129   LLVM_DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1130                     << " TargetName: " << TargetName << "\n");
1131   RelocationValueRef Value;
1132   // First search for the symbol in the local symbol table
1133   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1134
1135   // Search for the symbol in the global symbol table
1136   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1137   if (Symbol != Obj.symbol_end()) {
1138     gsi = GlobalSymbolTable.find(TargetName.data());
1139     Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType();
1140     if (!SymTypeOrErr) {
1141       std::string Buf;
1142       raw_string_ostream OS(Buf);
1143       logAllUnhandledErrors(SymTypeOrErr.takeError(), OS);
1144       OS.flush();
1145       report_fatal_error(Buf);
1146     }
1147     SymType = *SymTypeOrErr;
1148   }
1149   if (gsi != GlobalSymbolTable.end()) {
1150     const auto &SymInfo = gsi->second;
1151     Value.SectionID = SymInfo.getSectionID();
1152     Value.Offset = SymInfo.getOffset();
1153     Value.Addend = SymInfo.getOffset() + Addend;
1154   } else {
1155     switch (SymType) {
1156     case SymbolRef::ST_Debug: {
1157       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1158       // and can be changed by another developers. Maybe best way is add
1159       // a new symbol type ST_Section to SymbolRef and use it.
1160       auto SectionOrErr = Symbol->getSection();
1161       if (!SectionOrErr) {
1162         std::string Buf;
1163         raw_string_ostream OS(Buf);
1164         logAllUnhandledErrors(SectionOrErr.takeError(), OS);
1165         OS.flush();
1166         report_fatal_error(Buf);
1167       }
1168       section_iterator si = *SectionOrErr;
1169       if (si == Obj.section_end())
1170         llvm_unreachable("Symbol section not found, bad object file format!");
1171       LLVM_DEBUG(dbgs() << "\t\tThis is section symbol\n");
1172       bool isCode = si->isText();
1173       if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode,
1174                                                   ObjSectionToID))
1175         Value.SectionID = *SectionIDOrErr;
1176       else
1177         return SectionIDOrErr.takeError();
1178       Value.Addend = Addend;
1179       break;
1180     }
1181     case SymbolRef::ST_Data:
1182     case SymbolRef::ST_Function:
1183     case SymbolRef::ST_Unknown: {
1184       Value.SymbolName = TargetName.data();
1185       Value.Addend = Addend;
1186
1187       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1188       // will manifest here as a NULL symbol name.
1189       // We can set this as a valid (but empty) symbol name, and rely
1190       // on addRelocationForSymbol to handle this.
1191       if (!Value.SymbolName)
1192         Value.SymbolName = "";
1193       break;
1194     }
1195     default:
1196       llvm_unreachable("Unresolved symbol type!");
1197       break;
1198     }
1199   }
1200
1201   uint64_t Offset = RelI->getOffset();
1202
1203   LLVM_DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1204                     << "\n");
1205   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) {
1206     if (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26) {
1207       resolveAArch64Branch(SectionID, Value, RelI, Stubs);
1208     } else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) {
1209       // Craete new GOT entry or find existing one. If GOT entry is
1210       // to be created, then we also emit ABS64 relocation for it.
1211       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1212       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1213                                  ELF::R_AARCH64_ADR_PREL_PG_HI21);
1214
1215     } else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) {
1216       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1217       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1218                                  ELF::R_AARCH64_LDST64_ABS_LO12_NC);
1219     } else {
1220       processSimpleRelocation(SectionID, Offset, RelType, Value);
1221     }
1222   } else if (Arch == Triple::arm) {
1223     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1224       RelType == ELF::R_ARM_JUMP24) {
1225       // This is an ARM branch relocation, need to use a stub function.
1226       LLVM_DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n");
1227       SectionEntry &Section = Sections[SectionID];
1228
1229       // Look for an existing stub.
1230       StubMap::const_iterator i = Stubs.find(Value);
1231       if (i != Stubs.end()) {
1232         resolveRelocation(
1233             Section, Offset,
1234             reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
1235             RelType, 0);
1236         LLVM_DEBUG(dbgs() << " Stub function found\n");
1237       } else {
1238         // Create a new stub function.
1239         LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1240         Stubs[Value] = Section.getStubOffset();
1241         uint8_t *StubTargetAddr = createStubFunction(
1242             Section.getAddressWithOffset(Section.getStubOffset()));
1243         RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1244                            ELF::R_ARM_ABS32, Value.Addend);
1245         if (Value.SymbolName)
1246           addRelocationForSymbol(RE, Value.SymbolName);
1247         else
1248           addRelocationForSection(RE, Value.SectionID);
1249
1250         resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1251                                                Section.getAddressWithOffset(
1252                                                    Section.getStubOffset())),
1253                           RelType, 0);
1254         Section.advanceStubOffset(getMaxStubSize());
1255       }
1256     } else {
1257       uint32_t *Placeholder =
1258         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1259       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1260           RelType == ELF::R_ARM_ABS32) {
1261         Value.Addend += *Placeholder;
1262       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1263         // See ELF for ARM documentation
1264         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1265       }
1266       processSimpleRelocation(SectionID, Offset, RelType, Value);
1267     }
1268   } else if (IsMipsO32ABI) {
1269     uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1270         computePlaceholderAddress(SectionID, Offset));
1271     uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1272     if (RelType == ELF::R_MIPS_26) {
1273       // This is an Mips branch relocation, need to use a stub function.
1274       LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1275       SectionEntry &Section = Sections[SectionID];
1276
1277       // Extract the addend from the instruction.
1278       // We shift up by two since the Value will be down shifted again
1279       // when applying the relocation.
1280       uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1281
1282       Value.Addend += Addend;
1283
1284       //  Look up for existing stub.
1285       StubMap::const_iterator i = Stubs.find(Value);
1286       if (i != Stubs.end()) {
1287         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1288         addRelocationForSection(RE, SectionID);
1289         LLVM_DEBUG(dbgs() << " Stub function found\n");
1290       } else {
1291         // Create a new stub function.
1292         LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1293         Stubs[Value] = Section.getStubOffset();
1294
1295         unsigned AbiVariant = Obj.getPlatformFlags();
1296
1297         uint8_t *StubTargetAddr = createStubFunction(
1298             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1299
1300         // Creating Hi and Lo relocations for the filled stub instructions.
1301         RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1302                              ELF::R_MIPS_HI16, Value.Addend);
1303         RelocationEntry RELo(SectionID,
1304                              StubTargetAddr - Section.getAddress() + 4,
1305                              ELF::R_MIPS_LO16, Value.Addend);
1306
1307         if (Value.SymbolName) {
1308           addRelocationForSymbol(REHi, Value.SymbolName);
1309           addRelocationForSymbol(RELo, Value.SymbolName);
1310         } else {
1311           addRelocationForSection(REHi, Value.SectionID);
1312           addRelocationForSection(RELo, Value.SectionID);
1313         }
1314
1315         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1316         addRelocationForSection(RE, SectionID);
1317         Section.advanceStubOffset(getMaxStubSize());
1318       }
1319     } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
1320       int64_t Addend = (Opcode & 0x0000ffff) << 16;
1321       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1322       PendingRelocs.push_back(std::make_pair(Value, RE));
1323     } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
1324       int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
1325       for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
1326         const RelocationValueRef &MatchingValue = I->first;
1327         RelocationEntry &Reloc = I->second;
1328         if (MatchingValue == Value &&
1329             RelType == getMatchingLoRelocation(Reloc.RelType) &&
1330             SectionID == Reloc.SectionID) {
1331           Reloc.Addend += Addend;
1332           if (Value.SymbolName)
1333             addRelocationForSymbol(Reloc, Value.SymbolName);
1334           else
1335             addRelocationForSection(Reloc, Value.SectionID);
1336           I = PendingRelocs.erase(I);
1337         } else
1338           ++I;
1339       }
1340       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1341       if (Value.SymbolName)
1342         addRelocationForSymbol(RE, Value.SymbolName);
1343       else
1344         addRelocationForSection(RE, Value.SectionID);
1345     } else {
1346       if (RelType == ELF::R_MIPS_32)
1347         Value.Addend += Opcode;
1348       else if (RelType == ELF::R_MIPS_PC16)
1349         Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1350       else if (RelType == ELF::R_MIPS_PC19_S2)
1351         Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1352       else if (RelType == ELF::R_MIPS_PC21_S2)
1353         Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1354       else if (RelType == ELF::R_MIPS_PC26_S2)
1355         Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1356       processSimpleRelocation(SectionID, Offset, RelType, Value);
1357     }
1358   } else if (IsMipsN32ABI || IsMipsN64ABI) {
1359     uint32_t r_type = RelType & 0xff;
1360     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1361     if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1362         || r_type == ELF::R_MIPS_GOT_DISP) {
1363       StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1364       if (i != GOTSymbolOffsets.end())
1365         RE.SymOffset = i->second;
1366       else {
1367         RE.SymOffset = allocateGOTEntries(1);
1368         GOTSymbolOffsets[TargetName] = RE.SymOffset;
1369       }
1370       if (Value.SymbolName)
1371         addRelocationForSymbol(RE, Value.SymbolName);
1372       else
1373         addRelocationForSection(RE, Value.SectionID);
1374     } else if (RelType == ELF::R_MIPS_26) {
1375       // This is an Mips branch relocation, need to use a stub function.
1376       LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1377       SectionEntry &Section = Sections[SectionID];
1378
1379       //  Look up for existing stub.
1380       StubMap::const_iterator i = Stubs.find(Value);
1381       if (i != Stubs.end()) {
1382         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1383         addRelocationForSection(RE, SectionID);
1384         LLVM_DEBUG(dbgs() << " Stub function found\n");
1385       } else {
1386         // Create a new stub function.
1387         LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1388         Stubs[Value] = Section.getStubOffset();
1389
1390         unsigned AbiVariant = Obj.getPlatformFlags();
1391
1392         uint8_t *StubTargetAddr = createStubFunction(
1393             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1394
1395         if (IsMipsN32ABI) {
1396           // Creating Hi and Lo relocations for the filled stub instructions.
1397           RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1398                                ELF::R_MIPS_HI16, Value.Addend);
1399           RelocationEntry RELo(SectionID,
1400                                StubTargetAddr - Section.getAddress() + 4,
1401                                ELF::R_MIPS_LO16, Value.Addend);
1402           if (Value.SymbolName) {
1403             addRelocationForSymbol(REHi, Value.SymbolName);
1404             addRelocationForSymbol(RELo, Value.SymbolName);
1405           } else {
1406             addRelocationForSection(REHi, Value.SectionID);
1407             addRelocationForSection(RELo, Value.SectionID);
1408           }
1409         } else {
1410           // Creating Highest, Higher, Hi and Lo relocations for the filled stub
1411           // instructions.
1412           RelocationEntry REHighest(SectionID,
1413                                     StubTargetAddr - Section.getAddress(),
1414                                     ELF::R_MIPS_HIGHEST, Value.Addend);
1415           RelocationEntry REHigher(SectionID,
1416                                    StubTargetAddr - Section.getAddress() + 4,
1417                                    ELF::R_MIPS_HIGHER, Value.Addend);
1418           RelocationEntry REHi(SectionID,
1419                                StubTargetAddr - Section.getAddress() + 12,
1420                                ELF::R_MIPS_HI16, Value.Addend);
1421           RelocationEntry RELo(SectionID,
1422                                StubTargetAddr - Section.getAddress() + 20,
1423                                ELF::R_MIPS_LO16, Value.Addend);
1424           if (Value.SymbolName) {
1425             addRelocationForSymbol(REHighest, Value.SymbolName);
1426             addRelocationForSymbol(REHigher, Value.SymbolName);
1427             addRelocationForSymbol(REHi, Value.SymbolName);
1428             addRelocationForSymbol(RELo, Value.SymbolName);
1429           } else {
1430             addRelocationForSection(REHighest, Value.SectionID);
1431             addRelocationForSection(REHigher, Value.SectionID);
1432             addRelocationForSection(REHi, Value.SectionID);
1433             addRelocationForSection(RELo, Value.SectionID);
1434           }
1435         }
1436         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1437         addRelocationForSection(RE, SectionID);
1438         Section.advanceStubOffset(getMaxStubSize());
1439       }
1440     } else {
1441       processSimpleRelocation(SectionID, Offset, RelType, Value);
1442     }
1443
1444   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1445     if (RelType == ELF::R_PPC64_REL24) {
1446       // Determine ABI variant in use for this object.
1447       unsigned AbiVariant = Obj.getPlatformFlags();
1448       AbiVariant &= ELF::EF_PPC64_ABI;
1449       // A PPC branch relocation will need a stub function if the target is
1450       // an external symbol (either Value.SymbolName is set, or SymType is
1451       // Symbol::ST_Unknown) or if the target address is not within the
1452       // signed 24-bits branch address.
1453       SectionEntry &Section = Sections[SectionID];
1454       uint8_t *Target = Section.getAddressWithOffset(Offset);
1455       bool RangeOverflow = false;
1456       bool IsExtern = Value.SymbolName || SymType == SymbolRef::ST_Unknown;
1457       if (!IsExtern) {
1458         if (AbiVariant != 2) {
1459           // In the ELFv1 ABI, a function call may point to the .opd entry,
1460           // so the final symbol value is calculated based on the relocation
1461           // values in the .opd section.
1462           if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value))
1463             return std::move(Err);
1464         } else {
1465           // In the ELFv2 ABI, a function symbol may provide a local entry
1466           // point, which must be used for direct calls.
1467           if (Value.SectionID == SectionID){
1468             uint8_t SymOther = Symbol->getOther();
1469             Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1470           }
1471         }
1472         uint8_t *RelocTarget =
1473             Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
1474         int64_t delta = static_cast<int64_t>(Target - RelocTarget);
1475         // If it is within 26-bits branch range, just set the branch target
1476         if (SignExtend64<26>(delta) != delta) {
1477           RangeOverflow = true;
1478         } else if ((AbiVariant != 2) ||
1479                    (AbiVariant == 2  && Value.SectionID == SectionID)) {
1480           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1481           addRelocationForSection(RE, Value.SectionID);
1482         }
1483       }
1484       if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID) ||
1485           RangeOverflow) {
1486         // It is an external symbol (either Value.SymbolName is set, or
1487         // SymType is SymbolRef::ST_Unknown) or out of range.
1488         StubMap::const_iterator i = Stubs.find(Value);
1489         if (i != Stubs.end()) {
1490           // Symbol function stub already created, just relocate to it
1491           resolveRelocation(Section, Offset,
1492                             reinterpret_cast<uint64_t>(
1493                                 Section.getAddressWithOffset(i->second)),
1494                             RelType, 0);
1495           LLVM_DEBUG(dbgs() << " Stub function found\n");
1496         } else {
1497           // Create a new stub function.
1498           LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1499           Stubs[Value] = Section.getStubOffset();
1500           uint8_t *StubTargetAddr = createStubFunction(
1501               Section.getAddressWithOffset(Section.getStubOffset()),
1502               AbiVariant);
1503           RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1504                              ELF::R_PPC64_ADDR64, Value.Addend);
1505
1506           // Generates the 64-bits address loads as exemplified in section
1507           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1508           // apply to the low part of the instructions, so we have to update
1509           // the offset according to the target endianness.
1510           uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
1511           if (!IsTargetLittleEndian)
1512             StubRelocOffset += 2;
1513
1514           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1515                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1516           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1517                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1518           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1519                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1520           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1521                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1522
1523           if (Value.SymbolName) {
1524             addRelocationForSymbol(REhst, Value.SymbolName);
1525             addRelocationForSymbol(REhr, Value.SymbolName);
1526             addRelocationForSymbol(REh, Value.SymbolName);
1527             addRelocationForSymbol(REl, Value.SymbolName);
1528           } else {
1529             addRelocationForSection(REhst, Value.SectionID);
1530             addRelocationForSection(REhr, Value.SectionID);
1531             addRelocationForSection(REh, Value.SectionID);
1532             addRelocationForSection(REl, Value.SectionID);
1533           }
1534
1535           resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1536                                                  Section.getAddressWithOffset(
1537                                                      Section.getStubOffset())),
1538                             RelType, 0);
1539           Section.advanceStubOffset(getMaxStubSize());
1540         }
1541         if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID)) {
1542           // Restore the TOC for external calls
1543           if (AbiVariant == 2)
1544             writeInt32BE(Target + 4, 0xE8410018); // ld r2,24(r1)
1545           else
1546             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1547         }
1548       }
1549     } else if (RelType == ELF::R_PPC64_TOC16 ||
1550                RelType == ELF::R_PPC64_TOC16_DS ||
1551                RelType == ELF::R_PPC64_TOC16_LO ||
1552                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1553                RelType == ELF::R_PPC64_TOC16_HI ||
1554                RelType == ELF::R_PPC64_TOC16_HA) {
1555       // These relocations are supposed to subtract the TOC address from
1556       // the final value.  This does not fit cleanly into the RuntimeDyld
1557       // scheme, since there may be *two* sections involved in determining
1558       // the relocation value (the section of the symbol referred to by the
1559       // relocation, and the TOC section associated with the current module).
1560       //
1561       // Fortunately, these relocations are currently only ever generated
1562       // referring to symbols that themselves reside in the TOC, which means
1563       // that the two sections are actually the same.  Thus they cancel out
1564       // and we can immediately resolve the relocation right now.
1565       switch (RelType) {
1566       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1567       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1568       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1569       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1570       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1571       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1572       default: llvm_unreachable("Wrong relocation type.");
1573       }
1574
1575       RelocationValueRef TOCValue;
1576       if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue))
1577         return std::move(Err);
1578       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1579         llvm_unreachable("Unsupported TOC relocation.");
1580       Value.Addend -= TOCValue.Addend;
1581       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1582     } else {
1583       // There are two ways to refer to the TOC address directly: either
1584       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1585       // ignored), or via any relocation that refers to the magic ".TOC."
1586       // symbols (in which case the addend is respected).
1587       if (RelType == ELF::R_PPC64_TOC) {
1588         RelType = ELF::R_PPC64_ADDR64;
1589         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1590           return std::move(Err);
1591       } else if (TargetName == ".TOC.") {
1592         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1593           return std::move(Err);
1594         Value.Addend += Addend;
1595       }
1596
1597       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1598
1599       if (Value.SymbolName)
1600         addRelocationForSymbol(RE, Value.SymbolName);
1601       else
1602         addRelocationForSection(RE, Value.SectionID);
1603     }
1604   } else if (Arch == Triple::systemz &&
1605              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1606     // Create function stubs for both PLT and GOT references, regardless of
1607     // whether the GOT reference is to data or code.  The stub contains the
1608     // full address of the symbol, as needed by GOT references, and the
1609     // executable part only adds an overhead of 8 bytes.
1610     //
1611     // We could try to conserve space by allocating the code and data
1612     // parts of the stub separately.  However, as things stand, we allocate
1613     // a stub for every relocation, so using a GOT in JIT code should be
1614     // no less space efficient than using an explicit constant pool.
1615     LLVM_DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1616     SectionEntry &Section = Sections[SectionID];
1617
1618     // Look for an existing stub.
1619     StubMap::const_iterator i = Stubs.find(Value);
1620     uintptr_t StubAddress;
1621     if (i != Stubs.end()) {
1622       StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
1623       LLVM_DEBUG(dbgs() << " Stub function found\n");
1624     } else {
1625       // Create a new stub function.
1626       LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1627
1628       uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1629       uintptr_t StubAlignment = getStubAlignment();
1630       StubAddress =
1631           (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1632           -StubAlignment;
1633       unsigned StubOffset = StubAddress - BaseAddress;
1634
1635       Stubs[Value] = StubOffset;
1636       createStubFunction((uint8_t *)StubAddress);
1637       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1638                          Value.Offset);
1639       if (Value.SymbolName)
1640         addRelocationForSymbol(RE, Value.SymbolName);
1641       else
1642         addRelocationForSection(RE, Value.SectionID);
1643       Section.advanceStubOffset(getMaxStubSize());
1644     }
1645
1646     if (RelType == ELF::R_390_GOTENT)
1647       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1648                         Addend);
1649     else
1650       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1651   } else if (Arch == Triple::x86_64) {
1652     if (RelType == ELF::R_X86_64_PLT32) {
1653       // The way the PLT relocations normally work is that the linker allocates
1654       // the
1655       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1656       // entry will then jump to an address provided by the GOT.  On first call,
1657       // the
1658       // GOT address will point back into PLT code that resolves the symbol. After
1659       // the first call, the GOT entry points to the actual function.
1660       //
1661       // For local functions we're ignoring all of that here and just replacing
1662       // the PLT32 relocation type with PC32, which will translate the relocation
1663       // into a PC-relative call directly to the function. For external symbols we
1664       // can't be sure the function will be within 2^32 bytes of the call site, so
1665       // we need to create a stub, which calls into the GOT.  This case is
1666       // equivalent to the usual PLT implementation except that we use the stub
1667       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1668       // rather than allocating a PLT section.
1669       if (Value.SymbolName) {
1670         // This is a call to an external function.
1671         // Look for an existing stub.
1672         SectionEntry &Section = Sections[SectionID];
1673         StubMap::const_iterator i = Stubs.find(Value);
1674         uintptr_t StubAddress;
1675         if (i != Stubs.end()) {
1676           StubAddress = uintptr_t(Section.getAddress()) + i->second;
1677           LLVM_DEBUG(dbgs() << " Stub function found\n");
1678         } else {
1679           // Create a new stub function (equivalent to a PLT entry).
1680           LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1681
1682           uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1683           uintptr_t StubAlignment = getStubAlignment();
1684           StubAddress =
1685               (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1686               -StubAlignment;
1687           unsigned StubOffset = StubAddress - BaseAddress;
1688           Stubs[Value] = StubOffset;
1689           createStubFunction((uint8_t *)StubAddress);
1690
1691           // Bump our stub offset counter
1692           Section.advanceStubOffset(getMaxStubSize());
1693
1694           // Allocate a GOT Entry
1695           uint64_t GOTOffset = allocateGOTEntries(1);
1696
1697           // The load of the GOT address has an addend of -4
1698           resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
1699                                      ELF::R_X86_64_PC32);
1700
1701           // Fill in the value of the symbol we're targeting into the GOT
1702           addRelocationForSymbol(
1703               computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
1704               Value.SymbolName);
1705         }
1706
1707         // Make the target call a call into the stub table.
1708         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1709                           Addend);
1710       } else {
1711         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1712                   Value.Offset);
1713         addRelocationForSection(RE, Value.SectionID);
1714       }
1715     } else if (RelType == ELF::R_X86_64_GOTPCREL ||
1716                RelType == ELF::R_X86_64_GOTPCRELX ||
1717                RelType == ELF::R_X86_64_REX_GOTPCRELX) {
1718       uint64_t GOTOffset = allocateGOTEntries(1);
1719       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1720                                  ELF::R_X86_64_PC32);
1721
1722       // Fill in the value of the symbol we're targeting into the GOT
1723       RelocationEntry RE =
1724           computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1725       if (Value.SymbolName)
1726         addRelocationForSymbol(RE, Value.SymbolName);
1727       else
1728         addRelocationForSection(RE, Value.SectionID);
1729     } else if (RelType == ELF::R_X86_64_GOT64) {
1730       // Fill in a 64-bit GOT offset.
1731       uint64_t GOTOffset = allocateGOTEntries(1);
1732       resolveRelocation(Sections[SectionID], Offset, GOTOffset,
1733                         ELF::R_X86_64_64, 0);
1734
1735       // Fill in the value of the symbol we're targeting into the GOT
1736       RelocationEntry RE =
1737           computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1738       if (Value.SymbolName)
1739         addRelocationForSymbol(RE, Value.SymbolName);
1740       else
1741         addRelocationForSection(RE, Value.SectionID);
1742     } else if (RelType == ELF::R_X86_64_GOTPC64) {
1743       // Materialize the address of the base of the GOT relative to the PC.
1744       // This doesn't create a GOT entry, but it does mean we need a GOT
1745       // section.
1746       (void)allocateGOTEntries(0);
1747       resolveGOTOffsetRelocation(SectionID, Offset, Addend, ELF::R_X86_64_PC64);
1748     } else if (RelType == ELF::R_X86_64_GOTOFF64) {
1749       // GOTOFF relocations ultimately require a section difference relocation.
1750       (void)allocateGOTEntries(0);
1751       processSimpleRelocation(SectionID, Offset, RelType, Value);
1752     } else if (RelType == ELF::R_X86_64_PC32) {
1753       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1754       processSimpleRelocation(SectionID, Offset, RelType, Value);
1755     } else if (RelType == ELF::R_X86_64_PC64) {
1756       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1757       processSimpleRelocation(SectionID, Offset, RelType, Value);
1758     } else {
1759       processSimpleRelocation(SectionID, Offset, RelType, Value);
1760     }
1761   } else {
1762     if (Arch == Triple::x86) {
1763       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1764     }
1765     processSimpleRelocation(SectionID, Offset, RelType, Value);
1766   }
1767   return ++RelI;
1768 }
1769
1770 size_t RuntimeDyldELF::getGOTEntrySize() {
1771   // We don't use the GOT in all of these cases, but it's essentially free
1772   // to put them all here.
1773   size_t Result = 0;
1774   switch (Arch) {
1775   case Triple::x86_64:
1776   case Triple::aarch64:
1777   case Triple::aarch64_be:
1778   case Triple::ppc64:
1779   case Triple::ppc64le:
1780   case Triple::systemz:
1781     Result = sizeof(uint64_t);
1782     break;
1783   case Triple::x86:
1784   case Triple::arm:
1785   case Triple::thumb:
1786     Result = sizeof(uint32_t);
1787     break;
1788   case Triple::mips:
1789   case Triple::mipsel:
1790   case Triple::mips64:
1791   case Triple::mips64el:
1792     if (IsMipsO32ABI || IsMipsN32ABI)
1793       Result = sizeof(uint32_t);
1794     else if (IsMipsN64ABI)
1795       Result = sizeof(uint64_t);
1796     else
1797       llvm_unreachable("Mips ABI not handled");
1798     break;
1799   default:
1800     llvm_unreachable("Unsupported CPU type!");
1801   }
1802   return Result;
1803 }
1804
1805 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) {
1806   if (GOTSectionID == 0) {
1807     GOTSectionID = Sections.size();
1808     // Reserve a section id. We'll allocate the section later
1809     // once we know the total size
1810     Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
1811   }
1812   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1813   CurrentGOTIndex += no;
1814   return StartOffset;
1815 }
1816
1817 uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value,
1818                                              unsigned GOTRelType) {
1819   auto E = GOTOffsetMap.insert({Value, 0});
1820   if (E.second) {
1821     uint64_t GOTOffset = allocateGOTEntries(1);
1822
1823     // Create relocation for newly created GOT entry
1824     RelocationEntry RE =
1825         computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType);
1826     if (Value.SymbolName)
1827       addRelocationForSymbol(RE, Value.SymbolName);
1828     else
1829       addRelocationForSection(RE, Value.SectionID);
1830
1831     E.first->second = GOTOffset;
1832   }
1833
1834   return E.first->second;
1835 }
1836
1837 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID,
1838                                                 uint64_t Offset,
1839                                                 uint64_t GOTOffset,
1840                                                 uint32_t Type) {
1841   // Fill in the relative address of the GOT Entry into the stub
1842   RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset);
1843   addRelocationForSection(GOTRE, GOTSectionID);
1844 }
1845
1846 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset,
1847                                                    uint64_t SymbolOffset,
1848                                                    uint32_t Type) {
1849   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1850 }
1851
1852 Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1853                                   ObjSectionToIDMap &SectionMap) {
1854   if (IsMipsO32ABI)
1855     if (!PendingRelocs.empty())
1856       return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
1857
1858   // If necessary, allocate the global offset table
1859   if (GOTSectionID != 0) {
1860     // Allocate memory for the section
1861     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1862     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1863                                                 GOTSectionID, ".got", false);
1864     if (!Addr)
1865       return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!");
1866
1867     Sections[GOTSectionID] =
1868         SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
1869
1870     // For now, initialize all GOT entries to zero.  We'll fill them in as
1871     // needed when GOT-based relocations are applied.
1872     memset(Addr, 0, TotalSize);
1873     if (IsMipsN32ABI || IsMipsN64ABI) {
1874       // To correctly resolve Mips GOT relocations, we need a mapping from
1875       // object's sections to GOTs.
1876       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1877            SI != SE; ++SI) {
1878         if (SI->relocation_begin() != SI->relocation_end()) {
1879           Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
1880           if (!RelSecOrErr)
1881             return make_error<RuntimeDyldError>(
1882                 toString(RelSecOrErr.takeError()));
1883
1884           section_iterator RelocatedSection = *RelSecOrErr;
1885           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1886           assert (i != SectionMap.end());
1887           SectionToGOTMap[i->second] = GOTSectionID;
1888         }
1889       }
1890       GOTSymbolOffsets.clear();
1891     }
1892   }
1893
1894   // Look for and record the EH frame section.
1895   ObjSectionToIDMap::iterator i, e;
1896   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1897     const SectionRef &Section = i->first;
1898
1899     StringRef Name;
1900     Expected<StringRef> NameOrErr = Section.getName();
1901     if (NameOrErr)
1902       Name = *NameOrErr;
1903     else
1904       consumeError(NameOrErr.takeError());
1905
1906     if (Name == ".eh_frame") {
1907       UnregisteredEHFrameSections.push_back(i->second);
1908       break;
1909     }
1910   }
1911
1912   GOTSectionID = 0;
1913   CurrentGOTIndex = 0;
1914
1915   return Error::success();
1916 }
1917
1918 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1919   return Obj.isELF();
1920 }
1921
1922 bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const {
1923   unsigned RelTy = R.getType();
1924   if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
1925     return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE ||
1926            RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC;
1927
1928   if (Arch == Triple::x86_64)
1929     return RelTy == ELF::R_X86_64_GOTPCREL ||
1930            RelTy == ELF::R_X86_64_GOTPCRELX ||
1931            RelTy == ELF::R_X86_64_GOT64 ||
1932            RelTy == ELF::R_X86_64_REX_GOTPCRELX;
1933   return false;
1934 }
1935
1936 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
1937   if (Arch != Triple::x86_64)
1938     return true;  // Conservative answer
1939
1940   switch (R.getType()) {
1941   default:
1942     return true;  // Conservative answer
1943
1944
1945   case ELF::R_X86_64_GOTPCREL:
1946   case ELF::R_X86_64_GOTPCRELX:
1947   case ELF::R_X86_64_REX_GOTPCRELX:
1948   case ELF::R_X86_64_GOTPC64:
1949   case ELF::R_X86_64_GOT64:
1950   case ELF::R_X86_64_GOTOFF64:
1951   case ELF::R_X86_64_PC32:
1952   case ELF::R_X86_64_PC64:
1953   case ELF::R_X86_64_64:
1954     // We know that these reloation types won't need a stub function.  This list
1955     // can be extended as needed.
1956     return false;
1957   }
1958 }
1959
1960 } // namespace llvm