lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

   1 //===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Implementation of ELF support for the MC-JIT runtime dynamic linker.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "RuntimeDyldELF.h"
  15 #include "RuntimeDyldCheckerImpl.h"
  16 #include "Targets/RuntimeDyldELFMips.h"
  17 #include "llvm/ADT/STLExtras.h"
  18 #include "llvm/ADT/StringRef.h"
  19 #include "llvm/ADT/Triple.h"
  20 #include "llvm/BinaryFormat/ELF.h"
  21 #include "llvm/Object/ELFObjectFile.h"
  22 #include "llvm/Object/ObjectFile.h"
  23 #include "llvm/Support/Endian.h"
  24 #include "llvm/Support/MemoryBuffer.h"
  25
  26 using namespace llvm;
  27 using namespace llvm::object;
  28 using namespace llvm::support::endian;
  29
  30 #define DEBUG_TYPE "dyld"
  31
  32 static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); }
  33
  34 static void or32AArch64Imm(void *L, uint64_t Imm) {
  35   or32le(L, (Imm & 0xFFF) << 10);
  36 }
  37
  38 template <class T> static void write(bool isBE, void *P, T V) {
  39   isBE ? write<T, support::big>(P, V) : write<T, support::little>(P, V);
  40 }
  41
  42 static void write32AArch64Addr(void *L, uint64_t Imm) {
  43   uint32_t ImmLo = (Imm & 0x3) << 29;
  44   uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
  45   uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
  46   write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
  47 }
  48
  49 // Return the bits [Start, End] from Val shifted Start bits.
  50 // For instance, getBits(0xF0, 4, 8) returns 0xF.
  51 static uint64_t getBits(uint64_t Val, int Start, int End) {
  52   uint64_t Mask = ((uint64_t)1 << (End + 1 - Start)) - 1;
  53   return (Val >> Start) & Mask;
  54 }
  55
  56 namespace {
  57
  58 template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> {
  59   LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
  60
  61   typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
  62   typedef Elf_Sym_Impl<ELFT> Elf_Sym;
  63   typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
  64   typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
  65
  66   typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
  67
  68   typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type;
  69
  70   DyldELFObject(ELFObjectFile<ELFT> &&Obj);
  71
  72 public:
  73   static Expected<std::unique_ptr<DyldELFObject>>
  74   create(MemoryBufferRef Wrapper);
  75
  76   void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
  77
  78   void updateSymbolAddress(const SymbolRef &SymRef, uint64_t Addr);
  79
  80   // Methods for type inquiry through isa, cast and dyn_cast
  81   static bool classof(const Binary *v) {
  82     return (isa<ELFObjectFile<ELFT>>(v) &&
  83             classof(cast<ELFObjectFile<ELFT>>(v)));
  84   }
  85   static bool classof(const ELFObjectFile<ELFT> *v) {
  86     return v->isDyldType();
  87   }
  88 };
  89
  90
  91
  92 // The MemoryBuffer passed into this constructor is just a wrapper around the
  93 // actual memory.  Ultimately, the Binary parent class will take ownership of
  94 // this MemoryBuffer object but not the underlying memory.
  95 template <class ELFT>
  96 DyldELFObject<ELFT>::DyldELFObject(ELFObjectFile<ELFT> &&Obj)
  97     : ELFObjectFile<ELFT>(std::move(Obj)) {
  98   this->isDyldELFObject = true;
  99 }
 100
 101 template <class ELFT>
 102 Expected<std::unique_ptr<DyldELFObject<ELFT>>>
 103 DyldELFObject<ELFT>::create(MemoryBufferRef Wrapper) {
 104   auto Obj = ELFObjectFile<ELFT>::create(Wrapper);
 105   if (auto E = Obj.takeError())
 106     return std::move(E);
 107   std::unique_ptr<DyldELFObject<ELFT>> Ret(
 108       new DyldELFObject<ELFT>(std::move(*Obj)));
 109   return std::move(Ret);
 110 }
 111
 112 template <class ELFT>
 113 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
 114                                                uint64_t Addr) {
 115   DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
 116   Elf_Shdr *shdr =
 117       const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
 118
 119   // This assumes the address passed in matches the target address bitness
 120   // The template-based type cast handles everything else.
 121   shdr->sh_addr = static_cast<addr_type>(Addr);
 122 }
 123
 124 template <class ELFT>
 125 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
 126                                               uint64_t Addr) {
 127
 128   Elf_Sym *sym = const_cast<Elf_Sym *>(
 129       ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
 130
 131   // This assumes the address passed in matches the target address bitness
 132   // The template-based type cast handles everything else.
 133   sym->st_value = static_cast<addr_type>(Addr);
 134 }
 135
 136 class LoadedELFObjectInfo final
 137     : public LoadedObjectInfoHelper<LoadedELFObjectInfo,
 138                                     RuntimeDyld::LoadedObjectInfo> {
 139 public:
 140   LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
 141       : LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {}
 142
 143   OwningBinary<ObjectFile>
 144   getObjectForDebug(const ObjectFile &Obj) const override;
 145 };
 146
 147 template <typename ELFT>
 148 static Expected<std::unique_ptr<DyldELFObject<ELFT>>>
 149 createRTDyldELFObject(MemoryBufferRef Buffer, const ObjectFile &SourceObject,
 150                       const LoadedELFObjectInfo &L) {
 151   typedef typename ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
 152   typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type;
 153
 154   Expected<std::unique_ptr<DyldELFObject<ELFT>>> ObjOrErr =
 155       DyldELFObject<ELFT>::create(Buffer);
 156   if (Error E = ObjOrErr.takeError())
 157     return std::move(E);
 158
 159   std::unique_ptr<DyldELFObject<ELFT>> Obj = std::move(*ObjOrErr);
 160
 161   // Iterate over all sections in the object.
 162   auto SI = SourceObject.section_begin();
 163   for (const auto &Sec : Obj->sections()) {
 164     StringRef SectionName;
 165     Sec.getName(SectionName);
 166     if (SectionName != "") {
 167       DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
 168       Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
 169           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
 170
 171       if (uint64_t SecLoadAddr = L.getSectionLoadAddress(*SI)) {
 172         // This assumes that the address passed in matches the target address
 173         // bitness. The template-based type cast handles everything else.
 174         shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
 175       }
 176     }
 177     ++SI;
 178   }
 179
 180   return std::move(Obj);
 181 }
 182
 183 static OwningBinary<ObjectFile>
 184 createELFDebugObject(const ObjectFile &Obj, const LoadedELFObjectInfo &L) {
 185   assert(Obj.isELF() && "Not an ELF object file.");
 186
 187   std::unique_ptr<MemoryBuffer> Buffer =
 188     MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
 189
 190   Expected<std::unique_ptr<ObjectFile>> DebugObj(nullptr);
 191   handleAllErrors(DebugObj.takeError());
 192   if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian())
 193     DebugObj =
 194         createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), Obj, L);
 195   else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian())
 196     DebugObj =
 197         createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), Obj, L);
 198   else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian())
 199     DebugObj =
 200         createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), Obj, L);
 201   else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian())
 202     DebugObj =
 203         createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), Obj, L);
 204   else
 205     llvm_unreachable("Unexpected ELF format");
 206
 207   handleAllErrors(DebugObj.takeError());
 208   return OwningBinary<ObjectFile>(std::move(*DebugObj), std::move(Buffer));
 209 }
 210
 211 OwningBinary<ObjectFile>
 212 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
 213   return createELFDebugObject(Obj, *this);
 214 }
 215
 216 } // anonymous namespace
 217
 218 namespace llvm {
 219
 220 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
 221                                JITSymbolResolver &Resolver)
 222     : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
 223 RuntimeDyldELF::~RuntimeDyldELF() {}
 224
 225 void RuntimeDyldELF::registerEHFrames() {
 226   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
 227     SID EHFrameSID = UnregisteredEHFrameSections[i];
 228     uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
 229     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
 230     size_t EHFrameSize = Sections[EHFrameSID].getSize();
 231     MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
 232   }
 233   UnregisteredEHFrameSections.clear();
 234 }
 235
 236 std::unique_ptr<RuntimeDyldELF>
 237 llvm::RuntimeDyldELF::create(Triple::ArchType Arch,
 238                              RuntimeDyld::MemoryManager &MemMgr,
 239                              JITSymbolResolver &Resolver) {
 240   switch (Arch) {
 241   default:
 242     return make_unique<RuntimeDyldELF>(MemMgr, Resolver);
 243   case Triple::mips:
 244   case Triple::mipsel:
 245   case Triple::mips64:
 246   case Triple::mips64el:
 247     return make_unique<RuntimeDyldELFMips>(MemMgr, Resolver);
 248   }
 249 }
 250
 251 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
 252 RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
 253   if (auto ObjSectionToIDOrErr = loadObjectImpl(O))
 254     return llvm::make_unique<LoadedELFObjectInfo>(*this, *ObjSectionToIDOrErr);
 255   else {
 256     HasError = true;
 257     raw_string_ostream ErrStream(ErrorStr);
 258     logAllUnhandledErrors(ObjSectionToIDOrErr.takeError(), ErrStream, "");
 259     return nullptr;
 260   }
 261 }
 262
 263 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
 264                                              uint64_t Offset, uint64_t Value,
 265                                              uint32_t Type, int64_t Addend,
 266                                              uint64_t SymOffset) {
 267   switch (Type) {
 268   default:
 269     llvm_unreachable("Relocation type not implemented yet!");
 270     break;
 271   case ELF::R_X86_64_NONE:
 272     break;
 273   case ELF::R_X86_64_64: {
 274     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
 275         Value + Addend;
 276     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
 277                  << format("%p\n", Section.getAddressWithOffset(Offset)));
 278     break;
 279   }
 280   case ELF::R_X86_64_32:
 281   case ELF::R_X86_64_32S: {
 282     Value += Addend;
 283     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
 284            (Type == ELF::R_X86_64_32S &&
 285             ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
 286     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
 287     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 288         TruncatedAddr;
 289     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
 290                  << format("%p\n", Section.getAddressWithOffset(Offset)));
 291     break;
 292   }
 293   case ELF::R_X86_64_PC8: {
 294     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 295     int64_t RealOffset = Value + Addend - FinalAddress;
 296     assert(isInt<8>(RealOffset));
 297     int8_t TruncOffset = (RealOffset & 0xFF);
 298     Section.getAddress()[Offset] = TruncOffset;
 299     break;
 300   }
 301   case ELF::R_X86_64_PC32: {
 302     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 303     int64_t RealOffset = Value + Addend - FinalAddress;
 304     assert(isInt<32>(RealOffset));
 305     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
 306     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 307         TruncOffset;
 308     break;
 309   }
 310   case ELF::R_X86_64_PC64: {
 311     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 312     int64_t RealOffset = Value + Addend - FinalAddress;
 313     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
 314         RealOffset;
 315     break;
 316   }
 317   }
 318 }
 319
 320 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
 321                                           uint64_t Offset, uint32_t Value,
 322                                           uint32_t Type, int32_t Addend) {
 323   switch (Type) {
 324   case ELF::R_386_32: {
 325     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 326         Value + Addend;
 327     break;
 328   }
 329   case ELF::R_386_PC32: {
 330     uint32_t FinalAddress =
 331         Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
 332     uint32_t RealOffset = Value + Addend - FinalAddress;
 333     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
 334         RealOffset;
 335     break;
 336   }
 337   default:
 338     // There are other relocation types, but it appears these are the
 339     // only ones currently used by the LLVM ELF object writer
 340     llvm_unreachable("Relocation type not implemented yet!");
 341     break;
 342   }
 343 }
 344
 345 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
 346                                               uint64_t Offset, uint64_t Value,
 347                                               uint32_t Type, int64_t Addend) {
 348   uint32_t *TargetPtr =
 349       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
 350   uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 351   // Data should use target endian. Code should always use little endian.
 352   bool isBE = Arch == Triple::aarch64_be;
 353
 354   DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
 355                << format("%llx", Section.getAddressWithOffset(Offset))
 356                << " FinalAddress: 0x" << format("%llx", FinalAddress)
 357                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
 358                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
 359                << "\n");
 360
 361   switch (Type) {
 362   default:
 363     llvm_unreachable("Relocation type not implemented yet!");
 364     break;
 365   case ELF::R_AARCH64_ABS16: {
 366     uint64_t Result = Value + Addend;
 367     assert(static_cast<int64_t>(Result) >= INT16_MIN && Result < UINT16_MAX);
 368     write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU));
 369     break;
 370   }
 371   case ELF::R_AARCH64_ABS32: {
 372     uint64_t Result = Value + Addend;
 373     assert(static_cast<int64_t>(Result) >= INT32_MIN && Result < UINT32_MAX);
 374     write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
 375     break;
 376   }
 377   case ELF::R_AARCH64_ABS64:
 378     write(isBE, TargetPtr, Value + Addend);
 379     break;
 380   case ELF::R_AARCH64_PREL32: {
 381     uint64_t Result = Value + Addend - FinalAddress;
 382     assert(static_cast<int64_t>(Result) >= INT32_MIN &&
 383            static_cast<int64_t>(Result) <= UINT32_MAX);
 384     write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
 385     break;
 386   }
 387   case ELF::R_AARCH64_PREL64:
 388     write(isBE, TargetPtr, Value + Addend - FinalAddress);
 389     break;
 390   case ELF::R_AARCH64_CALL26: // fallthrough
 391   case ELF::R_AARCH64_JUMP26: {
 392     // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
 393     // calculation.
 394     uint64_t BranchImm = Value + Addend - FinalAddress;
 395
 396     // "Check that -2^27 <= result < 2^27".
 397     assert(isInt<28>(BranchImm));
 398     or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) >> 2);
 399     break;
 400   }
 401   case ELF::R_AARCH64_MOVW_UABS_G3:
 402     or32le(TargetPtr, ((Value + Addend) & 0xFFFF000000000000) >> 43);
 403     break;
 404   case ELF::R_AARCH64_MOVW_UABS_G2_NC:
 405     or32le(TargetPtr, ((Value + Addend) & 0xFFFF00000000) >> 27);
 406     break;
 407   case ELF::R_AARCH64_MOVW_UABS_G1_NC:
 408     or32le(TargetPtr, ((Value + Addend) & 0xFFFF0000) >> 11);
 409     break;
 410   case ELF::R_AARCH64_MOVW_UABS_G0_NC:
 411     or32le(TargetPtr, ((Value + Addend) & 0xFFFF) << 5);
 412     break;
 413   case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
 414     // Operation: Page(S+A) - Page(P)
 415     uint64_t Result =
 416         ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
 417
 418     // Check that -2^32 <= X < 2^32
 419     assert(isInt<33>(Result) && "overflow check failed for relocation");
 420
 421     // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
 422     // from bits 32:12 of X.
 423     write32AArch64Addr(TargetPtr, Result >> 12);
 424     break;
 425   }
 426   case ELF::R_AARCH64_ADD_ABS_LO12_NC:
 427     // Operation: S + A
 428     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 429     // from bits 11:0 of X
 430     or32AArch64Imm(TargetPtr, Value + Addend);
 431     break;
 432   case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
 433     // Operation: S + A
 434     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 435     // from bits 11:0 of X
 436     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 0, 11));
 437     break;
 438   case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
 439     // Operation: S + A
 440     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 441     // from bits 11:1 of X
 442     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 1, 11));
 443     break;
 444   case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
 445     // Operation: S + A
 446     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 447     // from bits 11:2 of X
 448     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 2, 11));
 449     break;
 450   case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
 451     // Operation: S + A
 452     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 453     // from bits 11:3 of X
 454     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 3, 11));
 455     break;
 456   case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
 457     // Operation: S + A
 458     // Immediate goes in bits 21:10 of LD/ST instruction, taken
 459     // from bits 11:4 of X
 460     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 4, 11));
 461     break;
 462   }
 463 }
 464
 465 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
 466                                           uint64_t Offset, uint32_t Value,
 467                                           uint32_t Type, int32_t Addend) {
 468   // TODO: Add Thumb relocations.
 469   uint32_t *TargetPtr =
 470       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
 471   uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
 472   Value += Addend;
 473
 474   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
 475                << Section.getAddressWithOffset(Offset)
 476                << " FinalAddress: " << format("%p", FinalAddress) << " Value: "
 477                << format("%x", Value) << " Type: " << format("%x", Type)
 478                << " Addend: " << format("%x", Addend) << "\n");
 479
 480   switch (Type) {
 481   default:
 482     llvm_unreachable("Not implemented relocation type!");
 483
 484   case ELF::R_ARM_NONE:
 485     break;
 486     // Write a 31bit signed offset
 487   case ELF::R_ARM_PREL31:
 488     support::ulittle32_t::ref{TargetPtr} =
 489         (support::ulittle32_t::ref{TargetPtr} & 0x80000000) |
 490         ((Value - FinalAddress) & ~0x80000000);
 491     break;
 492   case ELF::R_ARM_TARGET1:
 493   case ELF::R_ARM_ABS32:
 494     support::ulittle32_t::ref{TargetPtr} = Value;
 495     break;
 496     // Write first 16 bit of 32 bit value to the mov instruction.
 497     // Last 4 bit should be shifted.
 498   case ELF::R_ARM_MOVW_ABS_NC:
 499   case ELF::R_ARM_MOVT_ABS:
 500     if (Type == ELF::R_ARM_MOVW_ABS_NC)
 501       Value = Value & 0xFFFF;
 502     else if (Type == ELF::R_ARM_MOVT_ABS)
 503       Value = (Value >> 16) & 0xFFFF;
 504     support::ulittle32_t::ref{TargetPtr} =
 505         (support::ulittle32_t::ref{TargetPtr} & ~0x000F0FFF) | (Value & 0xFFF) |
 506         (((Value >> 12) & 0xF) << 16);
 507     break;
 508     // Write 24 bit relative value to the branch instruction.
 509   case ELF::R_ARM_PC24: // Fall through.
 510   case ELF::R_ARM_CALL: // Fall through.
 511   case ELF::R_ARM_JUMP24:
 512     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
 513     RelValue = (RelValue & 0x03FFFFFC) >> 2;
 514     assert((support::ulittle32_t::ref{TargetPtr} & 0xFFFFFF) == 0xFFFFFE);
 515     support::ulittle32_t::ref{TargetPtr} =
 516         (support::ulittle32_t::ref{TargetPtr} & 0xFF000000) | RelValue;
 517     break;
 518   }
 519 }
 520
 521 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
 522   if (Arch == Triple::UnknownArch ||
 523       !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
 524     IsMipsO32ABI = false;
 525     IsMipsN32ABI = false;
 526     IsMipsN64ABI = false;
 527     return;
 528   }
 529   unsigned AbiVariant;
 530   Obj.getPlatformFlags(AbiVariant);
 531   IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
 532   IsMipsN32ABI = AbiVariant & ELF::EF_MIPS_ABI2;
 533   IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips");
 534 }
 535
 536 // Return the .TOC. section and offset.
 537 Error RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
 538                                           ObjSectionToIDMap &LocalSections,
 539                                           RelocationValueRef &Rel) {
 540   // Set a default SectionID in case we do not find a TOC section below.
 541   // This may happen for references to TOC base base (sym@toc, .odp
 542   // relocation) without a .toc directive.  In this case just use the
 543   // first section (which is usually the .odp) since the code won't
 544   // reference the .toc base directly.
 545   Rel.SymbolName = nullptr;
 546   Rel.SectionID = 0;
 547
 548   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
 549   // order. The TOC starts where the first of these sections starts.
 550   for (auto &Section: Obj.sections()) {
 551     StringRef SectionName;
 552     if (auto EC = Section.getName(SectionName))
 553       return errorCodeToError(EC);
 554
 555     if (SectionName == ".got"
 556         || SectionName == ".toc"
 557         || SectionName == ".tocbss"
 558         || SectionName == ".plt") {
 559       if (auto SectionIDOrErr =
 560             findOrEmitSection(Obj, Section, false, LocalSections))
 561         Rel.SectionID = *SectionIDOrErr;
 562       else
 563         return SectionIDOrErr.takeError();
 564       break;
 565     }
 566   }
 567
 568   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
 569   // thus permitting a full 64 Kbytes segment.
 570   Rel.Addend = 0x8000;
 571
 572   return Error::success();
 573 }
 574
 575 // Returns the sections and offset associated with the ODP entry referenced
 576 // by Symbol.
 577 Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
 578                                           ObjSectionToIDMap &LocalSections,
 579                                           RelocationValueRef &Rel) {
 580   // Get the ELF symbol value (st_value) to compare with Relocation offset in
 581   // .opd entries
 582   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
 583        si != se; ++si) {
 584     section_iterator RelSecI = si->getRelocatedSection();
 585     if (RelSecI == Obj.section_end())
 586       continue;
 587
 588     StringRef RelSectionName;
 589     if (auto EC = RelSecI->getName(RelSectionName))
 590       return errorCodeToError(EC);
 591
 592     if (RelSectionName != ".opd")
 593       continue;
 594
 595     for (elf_relocation_iterator i = si->relocation_begin(),
 596                                  e = si->relocation_end();
 597          i != e;) {
 598       // The R_PPC64_ADDR64 relocation indicates the first field
 599       // of a .opd entry
 600       uint64_t TypeFunc = i->getType();
 601       if (TypeFunc != ELF::R_PPC64_ADDR64) {
 602         ++i;
 603         continue;
 604       }
 605
 606       uint64_t TargetSymbolOffset = i->getOffset();
 607       symbol_iterator TargetSymbol = i->getSymbol();
 608       int64_t Addend;
 609       if (auto AddendOrErr = i->getAddend())
 610         Addend = *AddendOrErr;
 611       else
 612         return AddendOrErr.takeError();
 613
 614       ++i;
 615       if (i == e)
 616         break;
 617
 618       // Just check if following relocation is a R_PPC64_TOC
 619       uint64_t TypeTOC = i->getType();
 620       if (TypeTOC != ELF::R_PPC64_TOC)
 621         continue;
 622
 623       // Finally compares the Symbol value and the target symbol offset
 624       // to check if this .opd entry refers to the symbol the relocation
 625       // points to.
 626       if (Rel.Addend != (int64_t)TargetSymbolOffset)
 627         continue;
 628
 629       section_iterator TSI = Obj.section_end();
 630       if (auto TSIOrErr = TargetSymbol->getSection())
 631         TSI = *TSIOrErr;
 632       else
 633         return TSIOrErr.takeError();
 634       assert(TSI != Obj.section_end() && "TSI should refer to a valid section");
 635
 636       bool IsCode = TSI->isText();
 637       if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode,
 638                                                   LocalSections))
 639         Rel.SectionID = *SectionIDOrErr;
 640       else
 641         return SectionIDOrErr.takeError();
 642       Rel.Addend = (intptr_t)Addend;
 643       return Error::success();
 644     }
 645   }
 646   llvm_unreachable("Attempting to get address of ODP entry!");
 647 }
 648
 649 // Relocation masks following the #lo(value), #hi(value), #ha(value),
 650 // #higher(value), #highera(value), #highest(value), and #highesta(value)
 651 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
 652 // document.
 653
 654 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
 655
 656 static inline uint16_t applyPPChi(uint64_t value) {
 657   return (value >> 16) & 0xffff;
 658 }
 659
 660 static inline uint16_t applyPPCha (uint64_t value) {
 661   return ((value + 0x8000) >> 16) & 0xffff;
 662 }
 663
 664 static inline uint16_t applyPPChigher(uint64_t value) {
 665   return (value >> 32) & 0xffff;
 666 }
 667
 668 static inline uint16_t applyPPChighera (uint64_t value) {
 669   return ((value + 0x8000) >> 32) & 0xffff;
 670 }
 671
 672 static inline uint16_t applyPPChighest(uint64_t value) {
 673   return (value >> 48) & 0xffff;
 674 }
 675
 676 static inline uint16_t applyPPChighesta (uint64_t value) {
 677   return ((value + 0x8000) >> 48) & 0xffff;
 678 }
 679
 680 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
 681                                             uint64_t Offset, uint64_t Value,
 682                                             uint32_t Type, int64_t Addend) {
 683   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 684   switch (Type) {
 685   default:
 686     llvm_unreachable("Relocation type not implemented yet!");
 687     break;
 688   case ELF::R_PPC_ADDR16_LO:
 689     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 690     break;
 691   case ELF::R_PPC_ADDR16_HI:
 692     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
 693     break;
 694   case ELF::R_PPC_ADDR16_HA:
 695     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
 696     break;
 697   }
 698 }
 699
 700 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
 701                                             uint64_t Offset, uint64_t Value,
 702                                             uint32_t Type, int64_t Addend) {
 703   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 704   switch (Type) {
 705   default:
 706     llvm_unreachable("Relocation type not implemented yet!");
 707     break;
 708   case ELF::R_PPC64_ADDR16:
 709     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 710     break;
 711   case ELF::R_PPC64_ADDR16_DS:
 712     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
 713     break;
 714   case ELF::R_PPC64_ADDR16_LO:
 715     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
 716     break;
 717   case ELF::R_PPC64_ADDR16_LO_DS:
 718     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
 719     break;
 720   case ELF::R_PPC64_ADDR16_HI:
 721     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
 722     break;
 723   case ELF::R_PPC64_ADDR16_HA:
 724     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
 725     break;
 726   case ELF::R_PPC64_ADDR16_HIGHER:
 727     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
 728     break;
 729   case ELF::R_PPC64_ADDR16_HIGHERA:
 730     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
 731     break;
 732   case ELF::R_PPC64_ADDR16_HIGHEST:
 733     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
 734     break;
 735   case ELF::R_PPC64_ADDR16_HIGHESTA:
 736     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
 737     break;
 738   case ELF::R_PPC64_ADDR14: {
 739     assert(((Value + Addend) & 3) == 0);
 740     // Preserve the AA/LK bits in the branch instruction
 741     uint8_t aalk = *(LocalAddress + 3);
 742     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
 743   } break;
 744   case ELF::R_PPC64_REL16_LO: {
 745     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 746     uint64_t Delta = Value - FinalAddress + Addend;
 747     writeInt16BE(LocalAddress, applyPPClo(Delta));
 748   } break;
 749   case ELF::R_PPC64_REL16_HI: {
 750     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 751     uint64_t Delta = Value - FinalAddress + Addend;
 752     writeInt16BE(LocalAddress, applyPPChi(Delta));
 753   } break;
 754   case ELF::R_PPC64_REL16_HA: {
 755     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 756     uint64_t Delta = Value - FinalAddress + Addend;
 757     writeInt16BE(LocalAddress, applyPPCha(Delta));
 758   } break;
 759   case ELF::R_PPC64_ADDR32: {
 760     int64_t Result = static_cast<int64_t>(Value + Addend);
 761     if (SignExtend64<32>(Result) != Result)
 762       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
 763     writeInt32BE(LocalAddress, Result);
 764   } break;
 765   case ELF::R_PPC64_REL24: {
 766     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 767     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
 768     if (SignExtend64<26>(delta) != delta)
 769       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
 770     // Generates a 'bl <address>' instruction
 771     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
 772   } break;
 773   case ELF::R_PPC64_REL32: {
 774     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 775     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
 776     if (SignExtend64<32>(delta) != delta)
 777       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
 778     writeInt32BE(LocalAddress, delta);
 779   } break;
 780   case ELF::R_PPC64_REL64: {
 781     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
 782     uint64_t Delta = Value - FinalAddress + Addend;
 783     writeInt64BE(LocalAddress, Delta);
 784   } break;
 785   case ELF::R_PPC64_ADDR64:
 786     writeInt64BE(LocalAddress, Value + Addend);
 787     break;
 788   }
 789 }
 790
 791 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
 792                                               uint64_t Offset, uint64_t Value,
 793                                               uint32_t Type, int64_t Addend) {
 794   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
 795   switch (Type) {
 796   default:
 797     llvm_unreachable("Relocation type not implemented yet!");
 798     break;
 799   case ELF::R_390_PC16DBL:
 800   case ELF::R_390_PLT16DBL: {
 801     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 802     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
 803     writeInt16BE(LocalAddress, Delta / 2);
 804     break;
 805   }
 806   case ELF::R_390_PC32DBL:
 807   case ELF::R_390_PLT32DBL: {
 808     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 809     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
 810     writeInt32BE(LocalAddress, Delta / 2);
 811     break;
 812   }
 813   case ELF::R_390_PC16: {
 814     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 815     assert(int16_t(Delta) == Delta && "R_390_PC16 overflow");
 816     writeInt16BE(LocalAddress, Delta);
 817     break;
 818   }
 819   case ELF::R_390_PC32: {
 820     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 821     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
 822     writeInt32BE(LocalAddress, Delta);
 823     break;
 824   }
 825   case ELF::R_390_PC64: {
 826     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
 827     writeInt64BE(LocalAddress, Delta);
 828     break;
 829   }
 830   case ELF::R_390_8:
 831     *LocalAddress = (uint8_t)(Value + Addend);
 832     break;
 833   case ELF::R_390_16:
 834     writeInt16BE(LocalAddress, Value + Addend);
 835     break;
 836   case ELF::R_390_32:
 837     writeInt32BE(LocalAddress, Value + Addend);
 838     break;
 839   case ELF::R_390_64:
 840     writeInt64BE(LocalAddress, Value + Addend);
 841     break;
 842   }
 843 }
 844
 845 void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
 846                                           uint64_t Offset, uint64_t Value,
 847                                           uint32_t Type, int64_t Addend) {
 848   bool isBE = Arch == Triple::bpfeb;
 849
 850   switch (Type) {
 851   default:
 852     llvm_unreachable("Relocation type not implemented yet!");
 853     break;
 854   case ELF::R_BPF_NONE:
 855     break;
 856   case ELF::R_BPF_64_64: {
 857     write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
 858     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
 859                  << format("%p\n", Section.getAddressWithOffset(Offset)));
 860     break;
 861   }
 862   case ELF::R_BPF_64_32: {
 863     Value += Addend;
 864     assert(Value <= UINT32_MAX);
 865     write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
 866     DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
 867                  << format("%p\n", Section.getAddressWithOffset(Offset)));
 868     break;
 869   }
 870   }
 871 }
 872
 873 // The target location for the relocation is described by RE.SectionID and
 874 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
 875 // SectionEntry has three members describing its location.
 876 // SectionEntry::Address is the address at which the section has been loaded
 877 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
 878 // address that the section will have in the target process.
 879 // SectionEntry::ObjAddress is the address of the bits for this section in the
 880 // original emitted object image (also in the current address space).
 881 //
 882 // Relocations will be applied as if the section were loaded at
 883 // SectionEntry::LoadAddress, but they will be applied at an address based
 884 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
 885 // Target memory contents if they are required for value calculations.
 886 //
 887 // The Value parameter here is the load address of the symbol for the
 888 // relocation to be applied.  For relocations which refer to symbols in the
 889 // current object Value will be the LoadAddress of the section in which
 890 // the symbol resides (RE.Addend provides additional information about the
 891 // symbol location).  For external symbols, Value will be the address of the
 892 // symbol in the target address space.
 893 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
 894                                        uint64_t Value) {
 895   const SectionEntry &Section = Sections[RE.SectionID];
 896   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
 897                            RE.SymOffset, RE.SectionID);
 898 }
 899
 900 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
 901                                        uint64_t Offset, uint64_t Value,
 902                                        uint32_t Type, int64_t Addend,
 903                                        uint64_t SymOffset, SID SectionID) {
 904   switch (Arch) {
 905   case Triple::x86_64:
 906     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
 907     break;
 908   case Triple::x86:
 909     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
 910                          (uint32_t)(Addend & 0xffffffffL));
 911     break;
 912   case Triple::aarch64:
 913   case Triple::aarch64_be:
 914     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
 915     break;
 916   case Triple::arm: // Fall through.
 917   case Triple::armeb:
 918   case Triple::thumb:
 919   case Triple::thumbeb:
 920     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
 921                          (uint32_t)(Addend & 0xffffffffL));
 922     break;
 923   case Triple::ppc:
 924     resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
 925     break;
 926   case Triple::ppc64: // Fall through.
 927   case Triple::ppc64le:
 928     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
 929     break;
 930   case Triple::systemz:
 931     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
 932     break;
 933   case Triple::bpfel:
 934   case Triple::bpfeb:
 935     resolveBPFRelocation(Section, Offset, Value, Type, Addend);
 936     break;
 937   default:
 938     llvm_unreachable("Unsupported CPU type!");
 939   }
 940 }
 941
 942 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
 943   return (void *)(Sections[SectionID].getObjAddress() + Offset);
 944 }
 945
 946 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
 947   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
 948   if (Value.SymbolName)
 949     addRelocationForSymbol(RE, Value.SymbolName);
 950   else
 951     addRelocationForSection(RE, Value.SectionID);
 952 }
 953
 954 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
 955                                                  bool IsLocal) const {
 956   switch (RelType) {
 957   case ELF::R_MICROMIPS_GOT16:
 958     if (IsLocal)
 959       return ELF::R_MICROMIPS_LO16;
 960     break;
 961   case ELF::R_MICROMIPS_HI16:
 962     return ELF::R_MICROMIPS_LO16;
 963   case ELF::R_MIPS_GOT16:
 964     if (IsLocal)
 965       return ELF::R_MIPS_LO16;
 966     break;
 967   case ELF::R_MIPS_HI16:
 968     return ELF::R_MIPS_LO16;
 969   case ELF::R_MIPS_PCHI16:
 970     return ELF::R_MIPS_PCLO16;
 971   default:
 972     break;
 973   }
 974   return ELF::R_MIPS_NONE;
 975 }
 976
 977 // Sometimes we don't need to create thunk for a branch.
 978 // This typically happens when branch target is located
 979 // in the same object file. In such case target is either
 980 // a weak symbol or symbol in a different executable section.
 981 // This function checks if branch target is located in the
 982 // same object file and if distance between source and target
 983 // fits R_AARCH64_CALL26 relocation. If both conditions are
 984 // met, it emits direct jump to the target and returns true.
 985 // Otherwise false is returned and thunk is created.
 986 bool RuntimeDyldELF::resolveAArch64ShortBranch(
 987     unsigned SectionID, relocation_iterator RelI,
 988     const RelocationValueRef &Value) {
 989   uint64_t Address;
 990   if (Value.SymbolName) {
 991     auto Loc = GlobalSymbolTable.find(Value.SymbolName);
 992
 993     // Don't create direct branch for external symbols.
 994     if (Loc == GlobalSymbolTable.end())
 995       return false;
 996
 997     const auto &SymInfo = Loc->second;
 998     Address =
 999         uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset(
1000             SymInfo.getOffset()));
1001   } else {
1002     Address = uint64_t(Sections[Value.SectionID].getLoadAddress());
1003   }
1004   uint64_t Offset = RelI->getOffset();
1005   uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset);
1006
1007   // R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27
1008   // If distance between source and target is out of range then we should
1009   // create thunk.
1010   if (!isInt<28>(Address + Value.Addend - SourceAddress))
1011     return false;
1012
1013   resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(),
1014                     Value.Addend);
1015
1016   return true;
1017 }
1018
1019 void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID,
1020                                           const RelocationValueRef &Value,
1021                                           relocation_iterator RelI,
1022                                           StubMap &Stubs) {
1023
1024   DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1025   SectionEntry &Section = Sections[SectionID];
1026
1027   uint64_t Offset = RelI->getOffset();
1028   unsigned RelType = RelI->getType();
1029   // Look for an existing stub.
1030   StubMap::const_iterator i = Stubs.find(Value);
1031   if (i != Stubs.end()) {
1032     resolveRelocation(Section, Offset,
1033                       (uint64_t)Section.getAddressWithOffset(i->second),
1034                       RelType, 0);
1035     DEBUG(dbgs() << " Stub function found\n");
1036   } else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) {
1037     // Create a new stub function.
1038     DEBUG(dbgs() << " Create a new stub function\n");
1039     Stubs[Value] = Section.getStubOffset();
1040     uint8_t *StubTargetAddr = createStubFunction(
1041         Section.getAddressWithOffset(Section.getStubOffset()));
1042
1043     RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(),
1044                               ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1045     RelocationEntry REmovk_g2(SectionID,
1046                               StubTargetAddr - Section.getAddress() + 4,
1047                               ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1048     RelocationEntry REmovk_g1(SectionID,
1049                               StubTargetAddr - Section.getAddress() + 8,
1050                               ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1051     RelocationEntry REmovk_g0(SectionID,
1052                               StubTargetAddr - Section.getAddress() + 12,
1053                               ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1054
1055     if (Value.SymbolName) {
1056       addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1057       addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1058       addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1059       addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1060     } else {
1061       addRelocationForSection(REmovz_g3, Value.SectionID);
1062       addRelocationForSection(REmovk_g2, Value.SectionID);
1063       addRelocationForSection(REmovk_g1, Value.SectionID);
1064       addRelocationForSection(REmovk_g0, Value.SectionID);
1065     }
1066     resolveRelocation(Section, Offset,
1067                       reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
1068                           Section.getStubOffset())),
1069                       RelType, 0);
1070     Section.advanceStubOffset(getMaxStubSize());
1071   }
1072 }
1073
1074 Expected<relocation_iterator>
1075 RuntimeDyldELF::processRelocationRef(
1076     unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1077     ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1078   const auto &Obj = cast<ELFObjectFileBase>(O);
1079   uint64_t RelType = RelI->getType();
1080   int64_t Addend = 0;
1081   if (Expected<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend())
1082     Addend = *AddendOrErr;
1083   else
1084     consumeError(AddendOrErr.takeError());
1085   elf_symbol_iterator Symbol = RelI->getSymbol();
1086
1087   // Obtain the symbol name which is referenced in the relocation
1088   StringRef TargetName;
1089   if (Symbol != Obj.symbol_end()) {
1090     if (auto TargetNameOrErr = Symbol->getName())
1091       TargetName = *TargetNameOrErr;
1092     else
1093       return TargetNameOrErr.takeError();
1094   }
1095   DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1096                << " TargetName: " << TargetName << "\n");
1097   RelocationValueRef Value;
1098   // First search for the symbol in the local symbol table
1099   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1100
1101   // Search for the symbol in the global symbol table
1102   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1103   if (Symbol != Obj.symbol_end()) {
1104     gsi = GlobalSymbolTable.find(TargetName.data());
1105     Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType();
1106     if (!SymTypeOrErr) {
1107       std::string Buf;
1108       raw_string_ostream OS(Buf);
1109       logAllUnhandledErrors(SymTypeOrErr.takeError(), OS, "");
1110       OS.flush();
1111       report_fatal_error(Buf);
1112     }
1113     SymType = *SymTypeOrErr;
1114   }
1115   if (gsi != GlobalSymbolTable.end()) {
1116     const auto &SymInfo = gsi->second;
1117     Value.SectionID = SymInfo.getSectionID();
1118     Value.Offset = SymInfo.getOffset();
1119     Value.Addend = SymInfo.getOffset() + Addend;
1120   } else {
1121     switch (SymType) {
1122     case SymbolRef::ST_Debug: {
1123       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1124       // and can be changed by another developers. Maybe best way is add
1125       // a new symbol type ST_Section to SymbolRef and use it.
1126       auto SectionOrErr = Symbol->getSection();
1127       if (!SectionOrErr) {
1128         std::string Buf;
1129         raw_string_ostream OS(Buf);
1130         logAllUnhandledErrors(SectionOrErr.takeError(), OS, "");
1131         OS.flush();
1132         report_fatal_error(Buf);
1133       }
1134       section_iterator si = *SectionOrErr;
1135       if (si == Obj.section_end())
1136         llvm_unreachable("Symbol section not found, bad object file format!");
1137       DEBUG(dbgs() << "\t\tThis is section symbol\n");
1138       bool isCode = si->isText();
1139       if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode,
1140                                                   ObjSectionToID))
1141         Value.SectionID = *SectionIDOrErr;
1142       else
1143         return SectionIDOrErr.takeError();
1144       Value.Addend = Addend;
1145       break;
1146     }
1147     case SymbolRef::ST_Data:
1148     case SymbolRef::ST_Function:
1149     case SymbolRef::ST_Unknown: {
1150       Value.SymbolName = TargetName.data();
1151       Value.Addend = Addend;
1152
1153       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1154       // will manifest here as a NULL symbol name.
1155       // We can set this as a valid (but empty) symbol name, and rely
1156       // on addRelocationForSymbol to handle this.
1157       if (!Value.SymbolName)
1158         Value.SymbolName = "";
1159       break;
1160     }
1161     default:
1162       llvm_unreachable("Unresolved symbol type!");
1163       break;
1164     }
1165   }
1166
1167   uint64_t Offset = RelI->getOffset();
1168
1169   DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1170                << "\n");
1171   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) {
1172     if (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26) {
1173       resolveAArch64Branch(SectionID, Value, RelI, Stubs);
1174     } else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) {
1175       // Craete new GOT entry or find existing one. If GOT entry is
1176       // to be created, then we also emit ABS64 relocation for it.
1177       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1178       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1179                                  ELF::R_AARCH64_ADR_PREL_PG_HI21);
1180
1181     } else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) {
1182       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1183       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1184                                  ELF::R_AARCH64_LDST64_ABS_LO12_NC);
1185     } else {
1186       processSimpleRelocation(SectionID, Offset, RelType, Value);
1187     }
1188   } else if (Arch == Triple::arm) {
1189     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1190       RelType == ELF::R_ARM_JUMP24) {
1191       // This is an ARM branch relocation, need to use a stub function.
1192       DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n");
1193       SectionEntry &Section = Sections[SectionID];
1194
1195       // Look for an existing stub.
1196       StubMap::const_iterator i = Stubs.find(Value);
1197       if (i != Stubs.end()) {
1198         resolveRelocation(
1199             Section, Offset,
1200             reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
1201             RelType, 0);
1202         DEBUG(dbgs() << " Stub function found\n");
1203       } else {
1204         // Create a new stub function.
1205         DEBUG(dbgs() << " Create a new stub function\n");
1206         Stubs[Value] = Section.getStubOffset();
1207         uint8_t *StubTargetAddr = createStubFunction(
1208             Section.getAddressWithOffset(Section.getStubOffset()));
1209         RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1210                            ELF::R_ARM_ABS32, Value.Addend);
1211         if (Value.SymbolName)
1212           addRelocationForSymbol(RE, Value.SymbolName);
1213         else
1214           addRelocationForSection(RE, Value.SectionID);
1215
1216         resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1217                                                Section.getAddressWithOffset(
1218                                                    Section.getStubOffset())),
1219                           RelType, 0);
1220         Section.advanceStubOffset(getMaxStubSize());
1221       }
1222     } else {
1223       uint32_t *Placeholder =
1224         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1225       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1226           RelType == ELF::R_ARM_ABS32) {
1227         Value.Addend += *Placeholder;
1228       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1229         // See ELF for ARM documentation
1230         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1231       }
1232       processSimpleRelocation(SectionID, Offset, RelType, Value);
1233     }
1234   } else if (IsMipsO32ABI) {
1235     uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1236         computePlaceholderAddress(SectionID, Offset));
1237     uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1238     if (RelType == ELF::R_MIPS_26) {
1239       // This is an Mips branch relocation, need to use a stub function.
1240       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1241       SectionEntry &Section = Sections[SectionID];
1242
1243       // Extract the addend from the instruction.
1244       // We shift up by two since the Value will be down shifted again
1245       // when applying the relocation.
1246       uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1247
1248       Value.Addend += Addend;
1249
1250       //  Look up for existing stub.
1251       StubMap::const_iterator i = Stubs.find(Value);
1252       if (i != Stubs.end()) {
1253         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1254         addRelocationForSection(RE, SectionID);
1255         DEBUG(dbgs() << " Stub function found\n");
1256       } else {
1257         // Create a new stub function.
1258         DEBUG(dbgs() << " Create a new stub function\n");
1259         Stubs[Value] = Section.getStubOffset();
1260
1261         unsigned AbiVariant;
1262         O.getPlatformFlags(AbiVariant);
1263
1264         uint8_t *StubTargetAddr = createStubFunction(
1265             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1266
1267         // Creating Hi and Lo relocations for the filled stub instructions.
1268         RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1269                              ELF::R_MIPS_HI16, Value.Addend);
1270         RelocationEntry RELo(SectionID,
1271                              StubTargetAddr - Section.getAddress() + 4,
1272                              ELF::R_MIPS_LO16, Value.Addend);
1273
1274         if (Value.SymbolName) {
1275           addRelocationForSymbol(REHi, Value.SymbolName);
1276           addRelocationForSymbol(RELo, Value.SymbolName);
1277         } else {
1278           addRelocationForSection(REHi, Value.SectionID);
1279           addRelocationForSection(RELo, Value.SectionID);
1280         }
1281
1282         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1283         addRelocationForSection(RE, SectionID);
1284         Section.advanceStubOffset(getMaxStubSize());
1285       }
1286     } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
1287       int64_t Addend = (Opcode & 0x0000ffff) << 16;
1288       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1289       PendingRelocs.push_back(std::make_pair(Value, RE));
1290     } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
1291       int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
1292       for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
1293         const RelocationValueRef &MatchingValue = I->first;
1294         RelocationEntry &Reloc = I->second;
1295         if (MatchingValue == Value &&
1296             RelType == getMatchingLoRelocation(Reloc.RelType) &&
1297             SectionID == Reloc.SectionID) {
1298           Reloc.Addend += Addend;
1299           if (Value.SymbolName)
1300             addRelocationForSymbol(Reloc, Value.SymbolName);
1301           else
1302             addRelocationForSection(Reloc, Value.SectionID);
1303           I = PendingRelocs.erase(I);
1304         } else
1305           ++I;
1306       }
1307       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1308       if (Value.SymbolName)
1309         addRelocationForSymbol(RE, Value.SymbolName);
1310       else
1311         addRelocationForSection(RE, Value.SectionID);
1312     } else {
1313       if (RelType == ELF::R_MIPS_32)
1314         Value.Addend += Opcode;
1315       else if (RelType == ELF::R_MIPS_PC16)
1316         Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1317       else if (RelType == ELF::R_MIPS_PC19_S2)
1318         Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1319       else if (RelType == ELF::R_MIPS_PC21_S2)
1320         Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1321       else if (RelType == ELF::R_MIPS_PC26_S2)
1322         Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1323       processSimpleRelocation(SectionID, Offset, RelType, Value);
1324     }
1325   } else if (IsMipsN32ABI || IsMipsN64ABI) {
1326     uint32_t r_type = RelType & 0xff;
1327     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1328     if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1329         || r_type == ELF::R_MIPS_GOT_DISP) {
1330       StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1331       if (i != GOTSymbolOffsets.end())
1332         RE.SymOffset = i->second;
1333       else {
1334         RE.SymOffset = allocateGOTEntries(1);
1335         GOTSymbolOffsets[TargetName] = RE.SymOffset;
1336       }
1337       if (Value.SymbolName)
1338         addRelocationForSymbol(RE, Value.SymbolName);
1339       else
1340         addRelocationForSection(RE, Value.SectionID);
1341     } else if (RelType == ELF::R_MIPS_26) {
1342       // This is an Mips branch relocation, need to use a stub function.
1343       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1344       SectionEntry &Section = Sections[SectionID];
1345
1346       //  Look up for existing stub.
1347       StubMap::const_iterator i = Stubs.find(Value);
1348       if (i != Stubs.end()) {
1349         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1350         addRelocationForSection(RE, SectionID);
1351         DEBUG(dbgs() << " Stub function found\n");
1352       } else {
1353         // Create a new stub function.
1354         DEBUG(dbgs() << " Create a new stub function\n");
1355         Stubs[Value] = Section.getStubOffset();
1356
1357         unsigned AbiVariant;
1358         O.getPlatformFlags(AbiVariant);
1359
1360         uint8_t *StubTargetAddr = createStubFunction(
1361             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1362
1363         if (IsMipsN32ABI) {
1364           // Creating Hi and Lo relocations for the filled stub instructions.
1365           RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1366                                ELF::R_MIPS_HI16, Value.Addend);
1367           RelocationEntry RELo(SectionID,
1368                                StubTargetAddr - Section.getAddress() + 4,
1369                                ELF::R_MIPS_LO16, Value.Addend);
1370           if (Value.SymbolName) {
1371             addRelocationForSymbol(REHi, Value.SymbolName);
1372             addRelocationForSymbol(RELo, Value.SymbolName);
1373           } else {
1374             addRelocationForSection(REHi, Value.SectionID);
1375             addRelocationForSection(RELo, Value.SectionID);
1376           }
1377         } else {
1378           // Creating Highest, Higher, Hi and Lo relocations for the filled stub
1379           // instructions.
1380           RelocationEntry REHighest(SectionID,
1381                                     StubTargetAddr - Section.getAddress(),
1382                                     ELF::R_MIPS_HIGHEST, Value.Addend);
1383           RelocationEntry REHigher(SectionID,
1384                                    StubTargetAddr - Section.getAddress() + 4,
1385                                    ELF::R_MIPS_HIGHER, Value.Addend);
1386           RelocationEntry REHi(SectionID,
1387                                StubTargetAddr - Section.getAddress() + 12,
1388                                ELF::R_MIPS_HI16, Value.Addend);
1389           RelocationEntry RELo(SectionID,
1390                                StubTargetAddr - Section.getAddress() + 20,
1391                                ELF::R_MIPS_LO16, Value.Addend);
1392           if (Value.SymbolName) {
1393             addRelocationForSymbol(REHighest, Value.SymbolName);
1394             addRelocationForSymbol(REHigher, Value.SymbolName);
1395             addRelocationForSymbol(REHi, Value.SymbolName);
1396             addRelocationForSymbol(RELo, Value.SymbolName);
1397           } else {
1398             addRelocationForSection(REHighest, Value.SectionID);
1399             addRelocationForSection(REHigher, Value.SectionID);
1400             addRelocationForSection(REHi, Value.SectionID);
1401             addRelocationForSection(RELo, Value.SectionID);
1402           }
1403         }
1404         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1405         addRelocationForSection(RE, SectionID);
1406         Section.advanceStubOffset(getMaxStubSize());
1407       }
1408     } else {
1409       processSimpleRelocation(SectionID, Offset, RelType, Value);
1410     }
1411
1412   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1413     if (RelType == ELF::R_PPC64_REL24) {
1414       // Determine ABI variant in use for this object.
1415       unsigned AbiVariant;
1416       Obj.getPlatformFlags(AbiVariant);
1417       AbiVariant &= ELF::EF_PPC64_ABI;
1418       // A PPC branch relocation will need a stub function if the target is
1419       // an external symbol (either Value.SymbolName is set, or SymType is
1420       // Symbol::ST_Unknown) or if the target address is not within the
1421       // signed 24-bits branch address.
1422       SectionEntry &Section = Sections[SectionID];
1423       uint8_t *Target = Section.getAddressWithOffset(Offset);
1424       bool RangeOverflow = false;
1425       if (!Value.SymbolName && SymType != SymbolRef::ST_Unknown) {
1426         if (AbiVariant != 2) {
1427           // In the ELFv1 ABI, a function call may point to the .opd entry,
1428           // so the final symbol value is calculated based on the relocation
1429           // values in the .opd section.
1430           if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value))
1431             return std::move(Err);
1432         } else {
1433           // In the ELFv2 ABI, a function symbol may provide a local entry
1434           // point, which must be used for direct calls.
1435           uint8_t SymOther = Symbol->getOther();
1436           Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1437         }
1438         uint8_t *RelocTarget =
1439             Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
1440         int64_t delta = static_cast<int64_t>(Target - RelocTarget);
1441         // If it is within 26-bits branch range, just set the branch target
1442         if (SignExtend64<26>(delta) == delta) {
1443           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1444           addRelocationForSection(RE, Value.SectionID);
1445         } else {
1446           RangeOverflow = true;
1447         }
1448       }
1449       if (Value.SymbolName || SymType == SymbolRef::ST_Unknown ||
1450           RangeOverflow) {
1451         // It is an external symbol (either Value.SymbolName is set, or
1452         // SymType is SymbolRef::ST_Unknown) or out of range.
1453         StubMap::const_iterator i = Stubs.find(Value);
1454         if (i != Stubs.end()) {
1455           // Symbol function stub already created, just relocate to it
1456           resolveRelocation(Section, Offset,
1457                             reinterpret_cast<uint64_t>(
1458                                 Section.getAddressWithOffset(i->second)),
1459                             RelType, 0);
1460           DEBUG(dbgs() << " Stub function found\n");
1461         } else {
1462           // Create a new stub function.
1463           DEBUG(dbgs() << " Create a new stub function\n");
1464           Stubs[Value] = Section.getStubOffset();
1465           uint8_t *StubTargetAddr = createStubFunction(
1466               Section.getAddressWithOffset(Section.getStubOffset()),
1467               AbiVariant);
1468           RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1469                              ELF::R_PPC64_ADDR64, Value.Addend);
1470
1471           // Generates the 64-bits address loads as exemplified in section
1472           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1473           // apply to the low part of the instructions, so we have to update
1474           // the offset according to the target endianness.
1475           uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
1476           if (!IsTargetLittleEndian)
1477             StubRelocOffset += 2;
1478
1479           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1480                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1481           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1482                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1483           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1484                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1485           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1486                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1487
1488           if (Value.SymbolName) {
1489             addRelocationForSymbol(REhst, Value.SymbolName);
1490             addRelocationForSymbol(REhr, Value.SymbolName);
1491             addRelocationForSymbol(REh, Value.SymbolName);
1492             addRelocationForSymbol(REl, Value.SymbolName);
1493           } else {
1494             addRelocationForSection(REhst, Value.SectionID);
1495             addRelocationForSection(REhr, Value.SectionID);
1496             addRelocationForSection(REh, Value.SectionID);
1497             addRelocationForSection(REl, Value.SectionID);
1498           }
1499
1500           resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1501                                                  Section.getAddressWithOffset(
1502                                                      Section.getStubOffset())),
1503                             RelType, 0);
1504           Section.advanceStubOffset(getMaxStubSize());
1505         }
1506         if (Value.SymbolName || SymType == SymbolRef::ST_Unknown) {
1507           // Restore the TOC for external calls
1508           if (AbiVariant == 2)
1509             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
1510           else
1511             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1512         }
1513       }
1514     } else if (RelType == ELF::R_PPC64_TOC16 ||
1515                RelType == ELF::R_PPC64_TOC16_DS ||
1516                RelType == ELF::R_PPC64_TOC16_LO ||
1517                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1518                RelType == ELF::R_PPC64_TOC16_HI ||
1519                RelType == ELF::R_PPC64_TOC16_HA) {
1520       // These relocations are supposed to subtract the TOC address from
1521       // the final value.  This does not fit cleanly into the RuntimeDyld
1522       // scheme, since there may be *two* sections involved in determining
1523       // the relocation value (the section of the symbol referred to by the
1524       // relocation, and the TOC section associated with the current module).
1525       //
1526       // Fortunately, these relocations are currently only ever generated
1527       // referring to symbols that themselves reside in the TOC, which means
1528       // that the two sections are actually the same.  Thus they cancel out
1529       // and we can immediately resolve the relocation right now.
1530       switch (RelType) {
1531       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1532       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1533       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1534       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1535       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1536       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1537       default: llvm_unreachable("Wrong relocation type.");
1538       }
1539
1540       RelocationValueRef TOCValue;
1541       if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue))
1542         return std::move(Err);
1543       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1544         llvm_unreachable("Unsupported TOC relocation.");
1545       Value.Addend -= TOCValue.Addend;
1546       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1547     } else {
1548       // There are two ways to refer to the TOC address directly: either
1549       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1550       // ignored), or via any relocation that refers to the magic ".TOC."
1551       // symbols (in which case the addend is respected).
1552       if (RelType == ELF::R_PPC64_TOC) {
1553         RelType = ELF::R_PPC64_ADDR64;
1554         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1555           return std::move(Err);
1556       } else if (TargetName == ".TOC.") {
1557         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1558           return std::move(Err);
1559         Value.Addend += Addend;
1560       }
1561
1562       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1563
1564       if (Value.SymbolName)
1565         addRelocationForSymbol(RE, Value.SymbolName);
1566       else
1567         addRelocationForSection(RE, Value.SectionID);
1568     }
1569   } else if (Arch == Triple::systemz &&
1570              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1571     // Create function stubs for both PLT and GOT references, regardless of
1572     // whether the GOT reference is to data or code.  The stub contains the
1573     // full address of the symbol, as needed by GOT references, and the
1574     // executable part only adds an overhead of 8 bytes.
1575     //
1576     // We could try to conserve space by allocating the code and data
1577     // parts of the stub separately.  However, as things stand, we allocate
1578     // a stub for every relocation, so using a GOT in JIT code should be
1579     // no less space efficient than using an explicit constant pool.
1580     DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1581     SectionEntry &Section = Sections[SectionID];
1582
1583     // Look for an existing stub.
1584     StubMap::const_iterator i = Stubs.find(Value);
1585     uintptr_t StubAddress;
1586     if (i != Stubs.end()) {
1587       StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
1588       DEBUG(dbgs() << " Stub function found\n");
1589     } else {
1590       // Create a new stub function.
1591       DEBUG(dbgs() << " Create a new stub function\n");
1592
1593       uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1594       uintptr_t StubAlignment = getStubAlignment();
1595       StubAddress =
1596           (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1597           -StubAlignment;
1598       unsigned StubOffset = StubAddress - BaseAddress;
1599
1600       Stubs[Value] = StubOffset;
1601       createStubFunction((uint8_t *)StubAddress);
1602       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1603                          Value.Offset);
1604       if (Value.SymbolName)
1605         addRelocationForSymbol(RE, Value.SymbolName);
1606       else
1607         addRelocationForSection(RE, Value.SectionID);
1608       Section.advanceStubOffset(getMaxStubSize());
1609     }
1610
1611     if (RelType == ELF::R_390_GOTENT)
1612       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1613                         Addend);
1614     else
1615       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1616   } else if (Arch == Triple::x86_64) {
1617     if (RelType == ELF::R_X86_64_PLT32) {
1618       // The way the PLT relocations normally work is that the linker allocates
1619       // the
1620       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1621       // entry will then jump to an address provided by the GOT.  On first call,
1622       // the
1623       // GOT address will point back into PLT code that resolves the symbol. After
1624       // the first call, the GOT entry points to the actual function.
1625       //
1626       // For local functions we're ignoring all of that here and just replacing
1627       // the PLT32 relocation type with PC32, which will translate the relocation
1628       // into a PC-relative call directly to the function. For external symbols we
1629       // can't be sure the function will be within 2^32 bytes of the call site, so
1630       // we need to create a stub, which calls into the GOT.  This case is
1631       // equivalent to the usual PLT implementation except that we use the stub
1632       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1633       // rather than allocating a PLT section.
1634       if (Value.SymbolName) {
1635         // This is a call to an external function.
1636         // Look for an existing stub.
1637         SectionEntry &Section = Sections[SectionID];
1638         StubMap::const_iterator i = Stubs.find(Value);
1639         uintptr_t StubAddress;
1640         if (i != Stubs.end()) {
1641           StubAddress = uintptr_t(Section.getAddress()) + i->second;
1642           DEBUG(dbgs() << " Stub function found\n");
1643         } else {
1644           // Create a new stub function (equivalent to a PLT entry).
1645           DEBUG(dbgs() << " Create a new stub function\n");
1646
1647           uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1648           uintptr_t StubAlignment = getStubAlignment();
1649           StubAddress =
1650               (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1651               -StubAlignment;
1652           unsigned StubOffset = StubAddress - BaseAddress;
1653           Stubs[Value] = StubOffset;
1654           createStubFunction((uint8_t *)StubAddress);
1655
1656           // Bump our stub offset counter
1657           Section.advanceStubOffset(getMaxStubSize());
1658
1659           // Allocate a GOT Entry
1660           uint64_t GOTOffset = allocateGOTEntries(1);
1661
1662           // The load of the GOT address has an addend of -4
1663           resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
1664                                      ELF::R_X86_64_PC32);
1665
1666           // Fill in the value of the symbol we're targeting into the GOT
1667           addRelocationForSymbol(
1668               computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
1669               Value.SymbolName);
1670         }
1671
1672         // Make the target call a call into the stub table.
1673         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1674                           Addend);
1675       } else {
1676         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1677                   Value.Offset);
1678         addRelocationForSection(RE, Value.SectionID);
1679       }
1680     } else if (RelType == ELF::R_X86_64_GOTPCREL ||
1681                RelType == ELF::R_X86_64_GOTPCRELX ||
1682                RelType == ELF::R_X86_64_REX_GOTPCRELX) {
1683       uint64_t GOTOffset = allocateGOTEntries(1);
1684       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1685                                  ELF::R_X86_64_PC32);
1686
1687       // Fill in the value of the symbol we're targeting into the GOT
1688       RelocationEntry RE =
1689           computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1690       if (Value.SymbolName)
1691         addRelocationForSymbol(RE, Value.SymbolName);
1692       else
1693         addRelocationForSection(RE, Value.SectionID);
1694     } else if (RelType == ELF::R_X86_64_PC32) {
1695       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1696       processSimpleRelocation(SectionID, Offset, RelType, Value);
1697     } else if (RelType == ELF::R_X86_64_PC64) {
1698       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1699       processSimpleRelocation(SectionID, Offset, RelType, Value);
1700     } else {
1701       processSimpleRelocation(SectionID, Offset, RelType, Value);
1702     }
1703   } else {
1704     if (Arch == Triple::x86) {
1705       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1706     }
1707     processSimpleRelocation(SectionID, Offset, RelType, Value);
1708   }
1709   return ++RelI;
1710 }
1711
1712 size_t RuntimeDyldELF::getGOTEntrySize() {
1713   // We don't use the GOT in all of these cases, but it's essentially free
1714   // to put them all here.
1715   size_t Result = 0;
1716   switch (Arch) {
1717   case Triple::x86_64:
1718   case Triple::aarch64:
1719   case Triple::aarch64_be:
1720   case Triple::ppc64:
1721   case Triple::ppc64le:
1722   case Triple::systemz:
1723     Result = sizeof(uint64_t);
1724     break;
1725   case Triple::x86:
1726   case Triple::arm:
1727   case Triple::thumb:
1728     Result = sizeof(uint32_t);
1729     break;
1730   case Triple::mips:
1731   case Triple::mipsel:
1732   case Triple::mips64:
1733   case Triple::mips64el:
1734     if (IsMipsO32ABI || IsMipsN32ABI)
1735       Result = sizeof(uint32_t);
1736     else if (IsMipsN64ABI)
1737       Result = sizeof(uint64_t);
1738     else
1739       llvm_unreachable("Mips ABI not handled");
1740     break;
1741   default:
1742     llvm_unreachable("Unsupported CPU type!");
1743   }
1744   return Result;
1745 }
1746
1747 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) {
1748   if (GOTSectionID == 0) {
1749     GOTSectionID = Sections.size();
1750     // Reserve a section id. We'll allocate the section later
1751     // once we know the total size
1752     Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
1753   }
1754   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1755   CurrentGOTIndex += no;
1756   return StartOffset;
1757 }
1758
1759 uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value,
1760                                              unsigned GOTRelType) {
1761   auto E = GOTOffsetMap.insert({Value, 0});
1762   if (E.second) {
1763     uint64_t GOTOffset = allocateGOTEntries(1);
1764
1765     // Create relocation for newly created GOT entry
1766     RelocationEntry RE =
1767         computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType);
1768     if (Value.SymbolName)
1769       addRelocationForSymbol(RE, Value.SymbolName);
1770     else
1771       addRelocationForSection(RE, Value.SectionID);
1772
1773     E.first->second = GOTOffset;
1774   }
1775
1776   return E.first->second;
1777 }
1778
1779 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID,
1780                                                 uint64_t Offset,
1781                                                 uint64_t GOTOffset,
1782                                                 uint32_t Type) {
1783   // Fill in the relative address of the GOT Entry into the stub
1784   RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset);
1785   addRelocationForSection(GOTRE, GOTSectionID);
1786 }
1787
1788 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset,
1789                                                    uint64_t SymbolOffset,
1790                                                    uint32_t Type) {
1791   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1792 }
1793
1794 Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1795                                   ObjSectionToIDMap &SectionMap) {
1796   if (IsMipsO32ABI)
1797     if (!PendingRelocs.empty())
1798       return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
1799
1800   // If necessary, allocate the global offset table
1801   if (GOTSectionID != 0) {
1802     // Allocate memory for the section
1803     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1804     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1805                                                 GOTSectionID, ".got", false);
1806     if (!Addr)
1807       return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!");
1808
1809     Sections[GOTSectionID] =
1810         SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
1811
1812     if (Checker)
1813       Checker->registerSection(Obj.getFileName(), GOTSectionID);
1814
1815     // For now, initialize all GOT entries to zero.  We'll fill them in as
1816     // needed when GOT-based relocations are applied.
1817     memset(Addr, 0, TotalSize);
1818     if (IsMipsN32ABI || IsMipsN64ABI) {
1819       // To correctly resolve Mips GOT relocations, we need a mapping from
1820       // object's sections to GOTs.
1821       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1822            SI != SE; ++SI) {
1823         if (SI->relocation_begin() != SI->relocation_end()) {
1824           section_iterator RelocatedSection = SI->getRelocatedSection();
1825           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1826           assert (i != SectionMap.end());
1827           SectionToGOTMap[i->second] = GOTSectionID;
1828         }
1829       }
1830       GOTSymbolOffsets.clear();
1831     }
1832   }
1833
1834   // Look for and record the EH frame section.
1835   ObjSectionToIDMap::iterator i, e;
1836   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1837     const SectionRef &Section = i->first;
1838     StringRef Name;
1839     Section.getName(Name);
1840     if (Name == ".eh_frame") {
1841       UnregisteredEHFrameSections.push_back(i->second);
1842       break;
1843     }
1844   }
1845
1846   GOTSectionID = 0;
1847   CurrentGOTIndex = 0;
1848
1849   return Error::success();
1850 }
1851
1852 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1853   return Obj.isELF();
1854 }
1855
1856 bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const {
1857   unsigned RelTy = R.getType();
1858   if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
1859     return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE ||
1860            RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC;
1861
1862   if (Arch == Triple::x86_64)
1863     return RelTy == ELF::R_X86_64_GOTPCREL ||
1864            RelTy == ELF::R_X86_64_GOTPCRELX ||
1865            RelTy == ELF::R_X86_64_REX_GOTPCRELX;
1866   return false;
1867 }
1868
1869 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
1870   if (Arch != Triple::x86_64)
1871     return true;  // Conservative answer
1872
1873   switch (R.getType()) {
1874   default:
1875     return true;  // Conservative answer
1876
1877
1878   case ELF::R_X86_64_GOTPCREL:
1879   case ELF::R_X86_64_GOTPCRELX:
1880   case ELF::R_X86_64_REX_GOTPCRELX:
1881   case ELF::R_X86_64_PC32:
1882   case ELF::R_X86_64_PC64:
1883   case ELF::R_X86_64_64:
1884     // We know that these reloation types won't need a stub function.  This list
1885     // can be extended as needed.
1886     return false;
1887   }
1888 }
1889
1890 } // namespace llvm