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 #define DEBUG_TYPE "dyld"
  15 #include "RuntimeDyldELF.h"
  16 #include "JITRegistrar.h"
  17 #include "ObjectImageCommon.h"
  18 #include "llvm/ADT/IntervalMap.h"
  19 #include "llvm/ADT/OwningPtr.h"
  20 #include "llvm/ADT/STLExtras.h"
  21 #include "llvm/ADT/StringRef.h"
  22 #include "llvm/ADT/Triple.h"
  23 #include "llvm/ExecutionEngine/ObjectBuffer.h"
  24 #include "llvm/ExecutionEngine/ObjectImage.h"
  25 #include "llvm/Object/ELF.h"
  26 #include "llvm/Object/ObjectFile.h"
  27 #include "llvm/Support/ELF.h"
  28 using namespace llvm;
  29 using namespace llvm::object;
  30
  31 namespace {
  32
  33 static inline
  34 error_code check(error_code Err) {
  35   if (Err) {
  36     report_fatal_error(Err.message());
  37   }
  38   return Err;
  39 }
  40
  41 template<support::endianness target_endianness, bool is64Bits>
  42 class DyldELFObject : public ELFObjectFile<target_endianness, is64Bits> {
  43   LLVM_ELF_IMPORT_TYPES(target_endianness, is64Bits)
  44
  45   typedef Elf_Shdr_Impl<target_endianness, is64Bits> Elf_Shdr;
  46   typedef Elf_Sym_Impl<target_endianness, is64Bits> Elf_Sym;
  47   typedef Elf_Rel_Impl<target_endianness, is64Bits, false> Elf_Rel;
  48   typedef Elf_Rel_Impl<target_endianness, is64Bits, true> Elf_Rela;
  49
  50   typedef Elf_Ehdr_Impl<target_endianness, is64Bits> Elf_Ehdr;
  51
  52   typedef typename ELFDataTypeTypedefHelper<
  53           target_endianness, is64Bits>::value_type addr_type;
  54
  55 public:
  56   DyldELFObject(MemoryBuffer *Wrapper, error_code &ec);
  57
  58   void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
  59   void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
  60
  61   // Methods for type inquiry through isa, cast and dyn_cast
  62   static inline bool classof(const Binary *v) {
  63     return (isa<ELFObjectFile<target_endianness, is64Bits> >(v)
  64             && classof(cast<ELFObjectFile<target_endianness, is64Bits> >(v)));
  65   }
  66   static inline bool classof(
  67       const ELFObjectFile<target_endianness, is64Bits> *v) {
  68     return v->isDyldType();
  69   }
  70 };
  71
  72 template<support::endianness target_endianness, bool is64Bits>
  73 class ELFObjectImage : public ObjectImageCommon {
  74   protected:
  75     DyldELFObject<target_endianness, is64Bits> *DyldObj;
  76     bool Registered;
  77
  78   public:
  79     ELFObjectImage(ObjectBuffer *Input,
  80                    DyldELFObject<target_endianness, is64Bits> *Obj)
  81     : ObjectImageCommon(Input, Obj),
  82       DyldObj(Obj),
  83       Registered(false) {}
  84
  85     virtual ~ELFObjectImage() {
  86       if (Registered)
  87         deregisterWithDebugger();
  88     }
  89
  90     // Subclasses can override these methods to update the image with loaded
  91     // addresses for sections and common symbols
  92     virtual void updateSectionAddress(const SectionRef &Sec, uint64_t Addr)
  93     {
  94       DyldObj->updateSectionAddress(Sec, Addr);
  95     }
  96
  97     virtual void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr)
  98     {
  99       DyldObj->updateSymbolAddress(Sym, Addr);
 100     }
 101
 102     virtual void registerWithDebugger()
 103     {
 104       JITRegistrar::getGDBRegistrar().registerObject(*Buffer);
 105       Registered = true;
 106     }
 107     virtual void deregisterWithDebugger()
 108     {
 109       JITRegistrar::getGDBRegistrar().deregisterObject(*Buffer);
 110     }
 111 };
 112
 113 // The MemoryBuffer passed into this constructor is just a wrapper around the
 114 // actual memory.  Ultimately, the Binary parent class will take ownership of
 115 // this MemoryBuffer object but not the underlying memory.
 116 template<support::endianness target_endianness, bool is64Bits>
 117 DyldELFObject<target_endianness, is64Bits>::DyldELFObject(MemoryBuffer *Wrapper,
 118                                                           error_code &ec)
 119   : ELFObjectFile<target_endianness, is64Bits>(Wrapper, ec) {
 120   this->isDyldELFObject = true;
 121 }
 122
 123 template<support::endianness target_endianness, bool is64Bits>
 124 void DyldELFObject<target_endianness, is64Bits>::updateSectionAddress(
 125                                                        const SectionRef &Sec,
 126                                                        uint64_t Addr) {
 127   DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
 128   Elf_Shdr *shdr = const_cast<Elf_Shdr*>(
 129                           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
 130
 131   // This assumes the address passed in matches the target address bitness
 132   // The template-based type cast handles everything else.
 133   shdr->sh_addr = static_cast<addr_type>(Addr);
 134 }
 135
 136 template<support::endianness target_endianness, bool is64Bits>
 137 void DyldELFObject<target_endianness, is64Bits>::updateSymbolAddress(
 138                                                        const SymbolRef &SymRef,
 139                                                        uint64_t Addr) {
 140
 141   Elf_Sym *sym = const_cast<Elf_Sym*>(
 142                                  ELFObjectFile<target_endianness, is64Bits>::
 143                                    getSymbol(SymRef.getRawDataRefImpl()));
 144
 145   // This assumes the address passed in matches the target address bitness
 146   // The template-based type cast handles everything else.
 147   sym->st_value = static_cast<addr_type>(Addr);
 148 }
 149
 150 } // namespace
 151
 152
 153 namespace llvm {
 154
 155 ObjectImage *RuntimeDyldELF::createObjectImage(ObjectBuffer *Buffer) {
 156   if (Buffer->getBufferSize() < ELF::EI_NIDENT)
 157     llvm_unreachable("Unexpected ELF object size");
 158   std::pair<unsigned char, unsigned char> Ident = std::make_pair(
 159                          (uint8_t)Buffer->getBufferStart()[ELF::EI_CLASS],
 160                          (uint8_t)Buffer->getBufferStart()[ELF::EI_DATA]);
 161   error_code ec;
 162
 163   if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
 164     DyldELFObject<support::little, false> *Obj =
 165            new DyldELFObject<support::little, false>(Buffer->getMemBuffer(), ec);
 166     return new ELFObjectImage<support::little, false>(Buffer, Obj);
 167   }
 168   else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
 169     DyldELFObject<support::big, false> *Obj =
 170            new DyldELFObject<support::big, false>(Buffer->getMemBuffer(), ec);
 171     return new ELFObjectImage<support::big, false>(Buffer, Obj);
 172   }
 173   else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
 174     DyldELFObject<support::big, true> *Obj =
 175            new DyldELFObject<support::big, true>(Buffer->getMemBuffer(), ec);
 176     return new ELFObjectImage<support::big, true>(Buffer, Obj);
 177   }
 178   else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
 179     DyldELFObject<support::little, true> *Obj =
 180            new DyldELFObject<support::little, true>(Buffer->getMemBuffer(), ec);
 181     return new ELFObjectImage<support::little, true>(Buffer, Obj);
 182   }
 183   else
 184     llvm_unreachable("Unexpected ELF format");
 185 }
 186
 187 RuntimeDyldELF::~RuntimeDyldELF() {
 188 }
 189
 190 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
 191                                              uint64_t Offset,
 192                                              uint64_t Value,
 193                                              uint32_t Type,
 194                                              int64_t Addend) {
 195   switch (Type) {
 196   default:
 197     llvm_unreachable("Relocation type not implemented yet!");
 198   break;
 199   case ELF::R_X86_64_64: {
 200     uint64_t *Target = reinterpret_cast<uint64_t*>(Section.Address + Offset);
 201     *Target = Value + Addend;
 202     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend))
 203                  << " at " << format("%p\n",Target));
 204     break;
 205   }
 206   case ELF::R_X86_64_32:
 207   case ELF::R_X86_64_32S: {
 208     Value += Addend;
 209     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
 210            (Type == ELF::R_X86_64_32S &&
 211              ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
 212     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
 213     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 214     *Target = TruncatedAddr;
 215     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr)
 216                  << " at " << format("%p\n",Target));
 217     break;
 218   }
 219   case ELF::R_X86_64_PC32: {
 220     // Get the placeholder value from the generated object since
 221     // a previous relocation attempt may have overwritten the loaded version
 222     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
 223                                                                    + Offset);
 224     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 225     uint64_t  FinalAddress = Section.LoadAddress + Offset;
 226     int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
 227     assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
 228     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
 229     *Target = TruncOffset;
 230     break;
 231   }
 232   }
 233 }
 234
 235 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
 236                                           uint64_t Offset,
 237                                           uint32_t Value,
 238                                           uint32_t Type,
 239                                           int32_t Addend) {
 240   switch (Type) {
 241   case ELF::R_386_32: {
 242     // Get the placeholder value from the generated object since
 243     // a previous relocation attempt may have overwritten the loaded version
 244     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
 245                                                                    + Offset);
 246     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 247     *Target = *Placeholder + Value + Addend;
 248     break;
 249   }
 250   case ELF::R_386_PC32: {
 251     // Get the placeholder value from the generated object since
 252     // a previous relocation attempt may have overwritten the loaded version
 253     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
 254                                                                    + Offset);
 255     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 256     uint32_t  FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
 257     uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
 258     *Target = RealOffset;
 259     break;
 260     }
 261     default:
 262       // There are other relocation types, but it appears these are the
 263       // only ones currently used by the LLVM ELF object writer
 264       llvm_unreachable("Relocation type not implemented yet!");
 265       break;
 266   }
 267 }
 268
 269 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
 270                                           uint64_t Offset,
 271                                           uint32_t Value,
 272                                           uint32_t Type,
 273                                           int32_t Addend) {
 274   // TODO: Add Thumb relocations.
 275   uint32_t* TargetPtr = (uint32_t*)(Section.Address + Offset);
 276   uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
 277   Value += Addend;
 278
 279   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
 280                << Section.Address + Offset
 281                << " FinalAddress: " << format("%p",FinalAddress)
 282                << " Value: " << format("%x",Value)
 283                << " Type: " << format("%x",Type)
 284                << " Addend: " << format("%x",Addend)
 285                << "\n");
 286
 287   switch(Type) {
 288   default:
 289     llvm_unreachable("Not implemented relocation type!");
 290
 291   // Write a 32bit value to relocation address, taking into account the
 292   // implicit addend encoded in the target.
 293   case ELF::R_ARM_TARGET1 :
 294   case ELF::R_ARM_ABS32 :
 295     *TargetPtr += Value;
 296     break;
 297
 298   // Write first 16 bit of 32 bit value to the mov instruction.
 299   // Last 4 bit should be shifted.
 300   case ELF::R_ARM_MOVW_ABS_NC :
 301     // We are not expecting any other addend in the relocation address.
 302     // Using 0x000F0FFF because MOVW has its 16 bit immediate split into 2
 303     // non-contiguous fields.
 304     assert((*TargetPtr & 0x000F0FFF) == 0);
 305     Value = Value & 0xFFFF;
 306     *TargetPtr |= Value & 0xFFF;
 307     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
 308     break;
 309
 310   // Write last 16 bit of 32 bit value to the mov instruction.
 311   // Last 4 bit should be shifted.
 312   case ELF::R_ARM_MOVT_ABS :
 313     // We are not expecting any other addend in the relocation address.
 314     // Use 0x000F0FFF for the same reason as R_ARM_MOVW_ABS_NC.
 315     assert((*TargetPtr & 0x000F0FFF) == 0);
 316     Value = (Value >> 16) & 0xFFFF;
 317     *TargetPtr |= Value & 0xFFF;
 318     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
 319     break;
 320
 321   // Write 24 bit relative value to the branch instruction.
 322   case ELF::R_ARM_PC24 :    // Fall through.
 323   case ELF::R_ARM_CALL :    // Fall through.
 324   case ELF::R_ARM_JUMP24 :
 325     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
 326     RelValue = (RelValue & 0x03FFFFFC) >> 2;
 327     *TargetPtr &= 0xFF000000;
 328     *TargetPtr |= RelValue;
 329     break;
 330   }
 331 }
 332
 333 void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
 334                                            uint64_t Offset,
 335                                            uint32_t Value,
 336                                            uint32_t Type,
 337                                            int32_t Addend) {
 338   uint32_t* TargetPtr = (uint32_t*)(Section.Address + Offset);
 339   Value += Addend;
 340
 341   DEBUG(dbgs() << "resolveMipselocation, LocalAddress: "
 342                << Section.Address + Offset
 343                << " FinalAddress: "
 344                << format("%p",Section.LoadAddress + Offset)
 345                << " Value: " << format("%x",Value)
 346                << " Type: " << format("%x",Type)
 347                << " Addend: " << format("%x",Addend)
 348                << "\n");
 349
 350   switch(Type) {
 351   default:
 352     llvm_unreachable("Not implemented relocation type!");
 353     break;
 354   case ELF::R_MIPS_32:
 355     *TargetPtr = Value + (*TargetPtr);
 356     break;
 357   case ELF::R_MIPS_26:
 358     *TargetPtr = ((*TargetPtr) & 0xfc000000) | (( Value & 0x0fffffff) >> 2);
 359     break;
 360   case ELF::R_MIPS_HI16:
 361     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
 362     Value += ((*TargetPtr) & 0x0000ffff) << 16;
 363     *TargetPtr = ((*TargetPtr) & 0xffff0000) |
 364                  (((Value + 0x8000) >> 16) & 0xffff);
 365     break;
 366    case ELF::R_MIPS_LO16:
 367     Value += ((*TargetPtr) & 0x0000ffff);
 368     *TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
 369     break;
 370    }
 371 }
 372
 373 // Return the .TOC. section address to R_PPC64_TOC relocations.
 374 uint64_t RuntimeDyldELF::findPPC64TOC() const {
 375   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
 376   // order. The TOC starts where the first of these sections starts.
 377   SectionList::const_iterator it = Sections.begin();
 378   SectionList::const_iterator ite = Sections.end();
 379   for (; it != ite; ++it) {
 380     if (it->Name == ".got" ||
 381         it->Name == ".toc" ||
 382         it->Name == ".tocbss" ||
 383         it->Name == ".plt")
 384       break;
 385   }
 386   if (it == ite) {
 387     // This may happen for
 388     // * references to TOC base base (sym@toc, .odp relocation) without
 389     // a .toc directive.
 390     // In this case just use the first section (which is usually
 391     // the .odp) since the code won't reference the .toc base
 392     // directly.
 393     it = Sections.begin();
 394   }
 395   assert (it != ite);
 396   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
 397   // thus permitting a full 64 Kbytes segment.
 398   return it->LoadAddress + 0x8000;
 399 }
 400
 401 // Returns the sections and offset associated with the ODP entry referenced
 402 // by Symbol.
 403 void RuntimeDyldELF::findOPDEntrySection(ObjectImage &Obj,
 404                                          ObjSectionToIDMap &LocalSections,
 405                                          RelocationValueRef &Rel) {
 406   // Get the ELF symbol value (st_value) to compare with Relocation offset in
 407   // .opd entries
 408
 409   error_code err;
 410   for (section_iterator si = Obj.begin_sections(),
 411      se = Obj.end_sections(); si != se; si.increment(err)) {
 412     StringRef SectionName;
 413     check(si->getName(SectionName));
 414     if (SectionName != ".opd")
 415       continue;
 416
 417     for (relocation_iterator i = si->begin_relocations(),
 418          e = si->end_relocations(); i != e;) {
 419       check(err);
 420
 421       // The R_PPC64_ADDR64 relocation indicates the first field
 422       // of a .opd entry
 423       uint64_t TypeFunc;
 424       check(i->getType(TypeFunc));
 425       if (TypeFunc != ELF::R_PPC64_ADDR64) {
 426         i.increment(err);
 427         continue;
 428       }
 429
 430       SymbolRef TargetSymbol;
 431       uint64_t TargetSymbolOffset;
 432       int64_t TargetAdditionalInfo;
 433       check(i->getSymbol(TargetSymbol));
 434       check(i->getOffset(TargetSymbolOffset));
 435       check(i->getAdditionalInfo(TargetAdditionalInfo));
 436
 437       i = i.increment(err);
 438       if (i == e)
 439         break;
 440       check(err);
 441
 442       // Just check if following relocation is a R_PPC64_TOC
 443       uint64_t TypeTOC;
 444       check(i->getType(TypeTOC));
 445       if (TypeTOC != ELF::R_PPC64_TOC)
 446         continue;
 447
 448       // Finally compares the Symbol value and the target symbol offset
 449       // to check if this .opd entry refers to the symbol the relocation
 450       // points to.
 451       if (Rel.Addend != (intptr_t)TargetSymbolOffset)
 452         continue;
 453
 454       section_iterator tsi(Obj.end_sections());
 455       check(TargetSymbol.getSection(tsi));
 456       Rel.SectionID = findOrEmitSection(Obj, (*tsi), true, LocalSections);
 457       Rel.Addend = (intptr_t)TargetAdditionalInfo;
 458       return;
 459     }
 460   }
 461   llvm_unreachable("Attempting to get address of ODP entry!");
 462 }
 463
 464 // Relocation masks following the #lo(value), #hi(value), #higher(value),
 465 // and #highest(value) macros defined in section 4.5.1. Relocation Types
 466 // in PPC-elf64abi document.
 467 //
 468 static inline
 469 uint16_t applyPPClo (uint64_t value)
 470 {
 471   return value & 0xffff;
 472 }
 473
 474 static inline
 475 uint16_t applyPPChi (uint64_t value)
 476 {
 477   return (value >> 16) & 0xffff;
 478 }
 479
 480 static inline
 481 uint16_t applyPPChigher (uint64_t value)
 482 {
 483   return (value >> 32) & 0xffff;
 484 }
 485
 486 static inline
 487 uint16_t applyPPChighest (uint64_t value)
 488 {
 489   return (value >> 48) & 0xffff;
 490 }
 491
 492 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
 493                                             uint64_t Offset,
 494                                             uint64_t Value,
 495                                             uint32_t Type,
 496                                             int64_t Addend) {
 497   uint8_t* LocalAddress = Section.Address + Offset;
 498   switch (Type) {
 499   default:
 500     llvm_unreachable("Relocation type not implemented yet!");
 501   break;
 502   case ELF::R_PPC64_ADDR16_LO :
 503     writeInt16BE(LocalAddress, applyPPClo (Value + Addend));
 504     break;
 505   case ELF::R_PPC64_ADDR16_HI :
 506     writeInt16BE(LocalAddress, applyPPChi (Value + Addend));
 507     break;
 508   case ELF::R_PPC64_ADDR16_HIGHER :
 509     writeInt16BE(LocalAddress, applyPPChigher (Value + Addend));
 510     break;
 511   case ELF::R_PPC64_ADDR16_HIGHEST :
 512     writeInt16BE(LocalAddress, applyPPChighest (Value + Addend));
 513     break;
 514   case ELF::R_PPC64_ADDR14 : {
 515     assert(((Value + Addend) & 3) == 0);
 516     // Preserve the AA/LK bits in the branch instruction
 517     uint8_t aalk = *(LocalAddress+3);
 518     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
 519   } break;
 520   case ELF::R_PPC64_REL24 : {
 521     uint64_t FinalAddress = (Section.LoadAddress + Offset);
 522     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
 523     if (SignExtend32<24>(delta) != delta)
 524       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
 525     // Generates a 'bl <address>' instruction
 526     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
 527   } break;
 528   case ELF::R_PPC64_ADDR64 :
 529     writeInt64BE(LocalAddress, Value + Addend);
 530     break;
 531   case ELF::R_PPC64_TOC :
 532     writeInt64BE(LocalAddress, findPPC64TOC());
 533     break;
 534   case ELF::R_PPC64_TOC16 : {
 535     uint64_t TOCStart = findPPC64TOC();
 536     Value = applyPPClo((Value + Addend) - TOCStart);
 537     writeInt16BE(LocalAddress, applyPPClo(Value));
 538   } break;
 539   case ELF::R_PPC64_TOC16_DS : {
 540     uint64_t TOCStart = findPPC64TOC();
 541     Value = ((Value + Addend) - TOCStart);
 542     writeInt16BE(LocalAddress, applyPPClo(Value));
 543   } break;
 544   }
 545 }
 546
 547
 548 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
 549                                        uint64_t Offset,
 550                                        uint64_t Value,
 551                                        uint32_t Type,
 552                                        int64_t Addend) {
 553   switch (Arch) {
 554   case Triple::x86_64:
 555     resolveX86_64Relocation(Section, Offset, Value, Type, Addend);
 556     break;
 557   case Triple::x86:
 558     resolveX86Relocation(Section, Offset,
 559                          (uint32_t)(Value & 0xffffffffL), Type,
 560                          (uint32_t)(Addend & 0xffffffffL));
 561     break;
 562   case Triple::arm:    // Fall through.
 563   case Triple::thumb:
 564     resolveARMRelocation(Section, Offset,
 565                          (uint32_t)(Value & 0xffffffffL), Type,
 566                          (uint32_t)(Addend & 0xffffffffL));
 567     break;
 568   case Triple::mips:    // Fall through.
 569   case Triple::mipsel:
 570     resolveMIPSRelocation(Section, Offset,
 571                           (uint32_t)(Value & 0xffffffffL), Type,
 572                           (uint32_t)(Addend & 0xffffffffL));
 573     break;
 574   case Triple::ppc64:
 575     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
 576     break;
 577   default: llvm_unreachable("Unsupported CPU type!");
 578   }
 579 }
 580
 581 void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
 582                                           ObjectImage &Obj,
 583                                           ObjSectionToIDMap &ObjSectionToID,
 584                                           const SymbolTableMap &Symbols,
 585                                           StubMap &Stubs) {
 586
 587   uint32_t RelType = (uint32_t)(Rel.Type & 0xffffffffL);
 588   intptr_t Addend = (intptr_t)Rel.AdditionalInfo;
 589   const SymbolRef &Symbol = Rel.Symbol;
 590
 591   // Obtain the symbol name which is referenced in the relocation
 592   StringRef TargetName;
 593   Symbol.getName(TargetName);
 594   DEBUG(dbgs() << "\t\tRelType: " << RelType
 595                << " Addend: " << Addend
 596                << " TargetName: " << TargetName
 597                << "\n");
 598   RelocationValueRef Value;
 599   // First search for the symbol in the local symbol table
 600   SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
 601   SymbolRef::Type SymType;
 602   Symbol.getType(SymType);
 603   if (lsi != Symbols.end()) {
 604     Value.SectionID = lsi->second.first;
 605     Value.Addend = lsi->second.second;
 606   } else {
 607     // Search for the symbol in the global symbol table
 608     SymbolTableMap::const_iterator gsi =
 609         GlobalSymbolTable.find(TargetName.data());
 610     if (gsi != GlobalSymbolTable.end()) {
 611       Value.SectionID = gsi->second.first;
 612       Value.Addend = gsi->second.second;
 613     } else {
 614       switch (SymType) {
 615         case SymbolRef::ST_Debug: {
 616           // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
 617           // and can be changed by another developers. Maybe best way is add
 618           // a new symbol type ST_Section to SymbolRef and use it.
 619           section_iterator si(Obj.end_sections());
 620           Symbol.getSection(si);
 621           if (si == Obj.end_sections())
 622             llvm_unreachable("Symbol section not found, bad object file format!");
 623           DEBUG(dbgs() << "\t\tThis is section symbol\n");
 624           // Default to 'true' in case isText fails (though it never does).
 625           bool isCode = true;
 626           si->isText(isCode);
 627           Value.SectionID = findOrEmitSection(Obj,
 628                                               (*si),
 629                                               isCode,
 630                                               ObjSectionToID);
 631           Value.Addend = Addend;
 632           break;
 633         }
 634         case SymbolRef::ST_Unknown: {
 635           Value.SymbolName = TargetName.data();
 636           Value.Addend = Addend;
 637           break;
 638         }
 639         default:
 640           llvm_unreachable("Unresolved symbol type!");
 641           break;
 642       }
 643     }
 644   }
 645   DEBUG(dbgs() << "\t\tRel.SectionID: " << Rel.SectionID
 646                << " Rel.Offset: " << Rel.Offset
 647                << "\n");
 648   if (Arch == Triple::arm &&
 649       (RelType == ELF::R_ARM_PC24 ||
 650        RelType == ELF::R_ARM_CALL ||
 651        RelType == ELF::R_ARM_JUMP24)) {
 652     // This is an ARM branch relocation, need to use a stub function.
 653     DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
 654     SectionEntry &Section = Sections[Rel.SectionID];
 655
 656     // Look for an existing stub.
 657     StubMap::const_iterator i = Stubs.find(Value);
 658     if (i != Stubs.end()) {
 659         resolveRelocation(Section, Rel.Offset,
 660                           (uint64_t)Section.Address + i->second, RelType, 0);
 661       DEBUG(dbgs() << " Stub function found\n");
 662     } else {
 663       // Create a new stub function.
 664       DEBUG(dbgs() << " Create a new stub function\n");
 665       Stubs[Value] = Section.StubOffset;
 666       uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 667                                                    Section.StubOffset);
 668       RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
 669                          ELF::R_ARM_ABS32, Value.Addend);
 670       if (Value.SymbolName)
 671         addRelocationForSymbol(RE, Value.SymbolName);
 672       else
 673         addRelocationForSection(RE, Value.SectionID);
 674
 675       resolveRelocation(Section, Rel.Offset,
 676                         (uint64_t)Section.Address + Section.StubOffset,
 677                         RelType, 0);
 678       Section.StubOffset += getMaxStubSize();
 679     }
 680   } else if (Arch == Triple::mipsel && RelType == ELF::R_MIPS_26) {
 681     // This is an Mips branch relocation, need to use a stub function.
 682     DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
 683     SectionEntry &Section = Sections[Rel.SectionID];
 684     uint8_t *Target = Section.Address + Rel.Offset;
 685     uint32_t *TargetAddress = (uint32_t *)Target;
 686
 687     // Extract the addend from the instruction.
 688     uint32_t Addend = ((*TargetAddress) & 0x03ffffff) << 2;
 689
 690     Value.Addend += Addend;
 691
 692     //  Look up for existing stub.
 693     StubMap::const_iterator i = Stubs.find(Value);
 694     if (i != Stubs.end()) {
 695       resolveRelocation(Section, Rel.Offset,
 696                         (uint64_t)Section.Address + i->second, RelType, 0);
 697       DEBUG(dbgs() << " Stub function found\n");
 698     } else {
 699       // Create a new stub function.
 700       DEBUG(dbgs() << " Create a new stub function\n");
 701       Stubs[Value] = Section.StubOffset;
 702       uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 703                                                    Section.StubOffset);
 704
 705       // Creating Hi and Lo relocations for the filled stub instructions.
 706       RelocationEntry REHi(Rel.SectionID,
 707                            StubTargetAddr - Section.Address,
 708                            ELF::R_MIPS_HI16, Value.Addend);
 709       RelocationEntry RELo(Rel.SectionID,
 710                            StubTargetAddr - Section.Address + 4,
 711                            ELF::R_MIPS_LO16, Value.Addend);
 712
 713       if (Value.SymbolName) {
 714         addRelocationForSymbol(REHi, Value.SymbolName);
 715         addRelocationForSymbol(RELo, Value.SymbolName);
 716       } else {
 717         addRelocationForSection(REHi, Value.SectionID);
 718         addRelocationForSection(RELo, Value.SectionID);
 719       }
 720
 721       resolveRelocation(Section, Rel.Offset,
 722                         (uint64_t)Section.Address + Section.StubOffset,
 723                         RelType, 0);
 724       Section.StubOffset += getMaxStubSize();
 725     }
 726   } else if (Arch == Triple::ppc64) {
 727     if (RelType == ELF::R_PPC64_REL24) {
 728       // A PPC branch relocation will need a stub function if the target is
 729       // an external symbol (Symbol::ST_Unknown) or if the target address
 730       // is not within the signed 24-bits branch address.
 731       SectionEntry &Section = Sections[Rel.SectionID];
 732       uint8_t *Target = Section.Address + Rel.Offset;
 733       bool RangeOverflow = false;
 734       if (SymType != SymbolRef::ST_Unknown) {
 735         // A function call may points to the .opd entry, so the final symbol value
 736         // in calculated based in the relocation values in .opd section.
 737         findOPDEntrySection(Obj, ObjSectionToID, Value);
 738         uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
 739         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
 740         // If it is within 24-bits branch range, just set the branch target
 741         if (SignExtend32<24>(delta) == delta) {
 742           RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
 743           if (Value.SymbolName)
 744             addRelocationForSymbol(RE, Value.SymbolName);
 745           else
 746             addRelocationForSection(RE, Value.SectionID);
 747         } else {
 748           RangeOverflow = true;
 749         }
 750       }
 751       if (SymType == SymbolRef::ST_Unknown || RangeOverflow == true) {
 752         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
 753         // larger than 24-bits.
 754         StubMap::const_iterator i = Stubs.find(Value);
 755         if (i != Stubs.end()) {
 756           // Symbol function stub already created, just relocate to it
 757           resolveRelocation(Section, Rel.Offset,
 758                             (uint64_t)Section.Address + i->second, RelType, 0);
 759           DEBUG(dbgs() << " Stub function found\n");
 760         } else {
 761           // Create a new stub function.
 762           DEBUG(dbgs() << " Create a new stub function\n");
 763           Stubs[Value] = Section.StubOffset;
 764           uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 765                                                        Section.StubOffset);
 766           RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
 767                              ELF::R_PPC64_ADDR64, Value.Addend);
 768
 769           // Generates the 64-bits address loads as exemplified in section
 770           // 4.5.1 in PPC64 ELF ABI.
 771           RelocationEntry REhst(Rel.SectionID,
 772                                 StubTargetAddr - Section.Address + 2,
 773                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
 774           RelocationEntry REhr(Rel.SectionID,
 775                                StubTargetAddr - Section.Address + 6,
 776                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
 777           RelocationEntry REh(Rel.SectionID,
 778                               StubTargetAddr - Section.Address + 14,
 779                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
 780           RelocationEntry REl(Rel.SectionID,
 781                               StubTargetAddr - Section.Address + 18,
 782                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
 783
 784           if (Value.SymbolName) {
 785             addRelocationForSymbol(REhst, Value.SymbolName);
 786             addRelocationForSymbol(REhr,  Value.SymbolName);
 787             addRelocationForSymbol(REh,   Value.SymbolName);
 788             addRelocationForSymbol(REl,   Value.SymbolName);
 789           } else {
 790             addRelocationForSection(REhst, Value.SectionID);
 791             addRelocationForSection(REhr,  Value.SectionID);
 792             addRelocationForSection(REh,   Value.SectionID);
 793             addRelocationForSection(REl,   Value.SectionID);
 794           }
 795
 796           resolveRelocation(Section, Rel.Offset,
 797                             (uint64_t)Section.Address + Section.StubOffset,
 798                             RelType, 0);
 799           if (SymType == SymbolRef::ST_Unknown)
 800             // Restore the TOC for external calls
 801             writeInt32BE(Target+4, 0xE8410028); // ld r2,40(r1)
 802           Section.StubOffset += getMaxStubSize();
 803         }
 804       }
 805     } else {
 806       RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
 807       // Extra check to avoid relocation againt empty symbols (usually
 808       // the R_PPC64_TOC).
 809       if (Value.SymbolName && !TargetName.empty())
 810         addRelocationForSymbol(RE, Value.SymbolName);
 811       else
 812         addRelocationForSection(RE, Value.SectionID);
 813     }
 814   } else {
 815     RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
 816     if (Value.SymbolName)
 817       addRelocationForSymbol(RE, Value.SymbolName);
 818     else
 819       addRelocationForSection(RE, Value.SectionID);
 820   }
 821 }
 822
 823 unsigned RuntimeDyldELF::getCommonSymbolAlignment(const SymbolRef &Sym) {
 824   // In ELF, the value of an SHN_COMMON symbol is its alignment requirement.
 825   uint64_t Align;
 826   Check(Sym.getValue(Align));
 827   return Align;
 828 }
 829
 830 bool RuntimeDyldELF::isCompatibleFormat(const ObjectBuffer *Buffer) const {
 831   if (Buffer->getBufferSize() < strlen(ELF::ElfMagic))
 832     return false;
 833   return (memcmp(Buffer->getBufferStart(), ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;
 834 }
 835 } // namespace llvm