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<class ELFT>
  42 class DyldELFObject
  43   : public ELFObjectFile<ELFT> {
  44   LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
  45
  46   typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
  47   typedef Elf_Sym_Impl<ELFT> Elf_Sym;
  48   typedef
  49     Elf_Rel_Impl<ELFT, false> Elf_Rel;
  50   typedef
  51     Elf_Rel_Impl<ELFT, true> Elf_Rela;
  52
  53   typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
  54
  55   typedef typename ELFDataTypeTypedefHelper<
  56           ELFT>::value_type addr_type;
  57
  58 public:
  59   DyldELFObject(MemoryBuffer *Wrapper, error_code &ec);
  60
  61   void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
  62   void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
  63
  64   // Methods for type inquiry through isa, cast and dyn_cast
  65   static inline bool classof(const Binary *v) {
  66     return (isa<ELFObjectFile<ELFT> >(v)
  67             && classof(cast<ELFObjectFile
  68                 <ELFT> >(v)));
  69   }
  70   static inline bool classof(
  71       const ELFObjectFile<ELFT> *v) {
  72     return v->isDyldType();
  73   }
  74 };
  75
  76 template<class ELFT>
  77 class ELFObjectImage : public ObjectImageCommon {
  78   protected:
  79     DyldELFObject<ELFT> *DyldObj;
  80     bool Registered;
  81
  82   public:
  83     ELFObjectImage(ObjectBuffer *Input,
  84                  DyldELFObject<ELFT> *Obj)
  85     : ObjectImageCommon(Input, Obj),
  86       DyldObj(Obj),
  87       Registered(false) {}
  88
  89     virtual ~ELFObjectImage() {
  90       if (Registered)
  91         deregisterWithDebugger();
  92     }
  93
  94     // Subclasses can override these methods to update the image with loaded
  95     // addresses for sections and common symbols
  96     virtual void updateSectionAddress(const SectionRef &Sec, uint64_t Addr)
  97     {
  98       DyldObj->updateSectionAddress(Sec, Addr);
  99     }
 100
 101     virtual void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr)
 102     {
 103       DyldObj->updateSymbolAddress(Sym, Addr);
 104     }
 105
 106     virtual void registerWithDebugger()
 107     {
 108       JITRegistrar::getGDBRegistrar().registerObject(*Buffer);
 109       Registered = true;
 110     }
 111     virtual void deregisterWithDebugger()
 112     {
 113       JITRegistrar::getGDBRegistrar().deregisterObject(*Buffer);
 114     }
 115 };
 116
 117 // The MemoryBuffer passed into this constructor is just a wrapper around the
 118 // actual memory.  Ultimately, the Binary parent class will take ownership of
 119 // this MemoryBuffer object but not the underlying memory.
 120 template<class ELFT>
 121 DyldELFObject<ELFT>::DyldELFObject(MemoryBuffer *Wrapper, error_code &ec)
 122   : ELFObjectFile<ELFT>(Wrapper, ec) {
 123   this->isDyldELFObject = true;
 124 }
 125
 126 template<class ELFT>
 127 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
 128                                                uint64_t Addr) {
 129   DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
 130   Elf_Shdr *shdr = const_cast<Elf_Shdr*>(
 131                           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
 132
 133   // This assumes the address passed in matches the target address bitness
 134   // The template-based type cast handles everything else.
 135   shdr->sh_addr = static_cast<addr_type>(Addr);
 136 }
 137
 138 template<class ELFT>
 139 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
 140                                               uint64_t Addr) {
 141
 142   Elf_Sym *sym = const_cast<Elf_Sym*>(
 143     ELFObjectFile<ELFT>::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 namespace llvm {
 153
 154 ObjectImage *RuntimeDyldELF::createObjectImage(ObjectBuffer *Buffer) {
 155   if (Buffer->getBufferSize() < ELF::EI_NIDENT)
 156     llvm_unreachable("Unexpected ELF object size");
 157   std::pair<unsigned char, unsigned char> Ident = std::make_pair(
 158                          (uint8_t)Buffer->getBufferStart()[ELF::EI_CLASS],
 159                          (uint8_t)Buffer->getBufferStart()[ELF::EI_DATA]);
 160   error_code ec;
 161
 162   if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
 163     DyldELFObject<ELFType<support::little, 4, false> > *Obj =
 164       new DyldELFObject<ELFType<support::little, 4, false> >(
 165         Buffer->getMemBuffer(), ec);
 166     return new ELFObjectImage<ELFType<support::little, 4, false> >(Buffer, Obj);
 167   }
 168   else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) {
 169     DyldELFObject<ELFType<support::big, 4, false> > *Obj =
 170       new DyldELFObject<ELFType<support::big, 4, false> >(
 171         Buffer->getMemBuffer(), ec);
 172     return new ELFObjectImage<ELFType<support::big, 4, false> >(Buffer, Obj);
 173   }
 174   else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) {
 175     DyldELFObject<ELFType<support::big, 8, true> > *Obj =
 176       new DyldELFObject<ELFType<support::big, 8, true> >(
 177         Buffer->getMemBuffer(), ec);
 178     return new ELFObjectImage<ELFType<support::big, 8, true> >(Buffer, Obj);
 179   }
 180   else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
 181     DyldELFObject<ELFType<support::little, 8, true> > *Obj =
 182       new DyldELFObject<ELFType<support::little, 8, true> >(
 183         Buffer->getMemBuffer(), ec);
 184     return new ELFObjectImage<ELFType<support::little, 8, true> >(Buffer, Obj);
 185   }
 186   else
 187     llvm_unreachable("Unexpected ELF format");
 188 }
 189
 190 RuntimeDyldELF::~RuntimeDyldELF() {
 191 }
 192
 193 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
 194                                              uint64_t Offset,
 195                                              uint64_t Value,
 196                                              uint32_t Type,
 197                                              int64_t Addend) {
 198   switch (Type) {
 199   default:
 200     llvm_unreachable("Relocation type not implemented yet!");
 201   break;
 202   case ELF::R_X86_64_64: {
 203     uint64_t *Target = reinterpret_cast<uint64_t*>(Section.Address + Offset);
 204     *Target = Value + Addend;
 205     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend))
 206                  << " at " << format("%p\n",Target));
 207     break;
 208   }
 209   case ELF::R_X86_64_32:
 210   case ELF::R_X86_64_32S: {
 211     Value += Addend;
 212     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
 213            (Type == ELF::R_X86_64_32S &&
 214              ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
 215     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
 216     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 217     *Target = TruncatedAddr;
 218     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr)
 219                  << " at " << format("%p\n",Target));
 220     break;
 221   }
 222   case ELF::R_X86_64_PC32: {
 223     // Get the placeholder value from the generated object since
 224     // a previous relocation attempt may have overwritten the loaded version
 225     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
 226                                                                    + Offset);
 227     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 228     uint64_t  FinalAddress = Section.LoadAddress + Offset;
 229     int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
 230     assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
 231     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
 232     *Target = TruncOffset;
 233     break;
 234   }
 235   }
 236 }
 237
 238 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
 239                                           uint64_t Offset,
 240                                           uint32_t Value,
 241                                           uint32_t Type,
 242                                           int32_t Addend) {
 243   switch (Type) {
 244   case ELF::R_386_32: {
 245     // Get the placeholder value from the generated object since
 246     // a previous relocation attempt may have overwritten the loaded version
 247     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
 248                                                                    + Offset);
 249     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 250     *Target = *Placeholder + Value + Addend;
 251     break;
 252   }
 253   case ELF::R_386_PC32: {
 254     // Get the placeholder value from the generated object since
 255     // a previous relocation attempt may have overwritten the loaded version
 256     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(Section.ObjAddress
 257                                                                    + Offset);
 258     uint32_t *Target = reinterpret_cast<uint32_t*>(Section.Address + Offset);
 259     uint32_t  FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
 260     uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
 261     *Target = RealOffset;
 262     break;
 263     }
 264     default:
 265       // There are other relocation types, but it appears these are the
 266       // only ones currently used by the LLVM ELF object writer
 267       llvm_unreachable("Relocation type not implemented yet!");
 268       break;
 269   }
 270 }
 271
 272 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
 273                                           uint64_t Offset,
 274                                           uint32_t Value,
 275                                           uint32_t Type,
 276                                           int32_t Addend) {
 277   // TODO: Add Thumb relocations.
 278   uint32_t* TargetPtr = (uint32_t*)(Section.Address + Offset);
 279   uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
 280   Value += Addend;
 281
 282   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
 283                << Section.Address + Offset
 284                << " FinalAddress: " << format("%p",FinalAddress)
 285                << " Value: " << format("%x",Value)
 286                << " Type: " << format("%x",Type)
 287                << " Addend: " << format("%x",Addend)
 288                << "\n");
 289
 290   switch(Type) {
 291   default:
 292     llvm_unreachable("Not implemented relocation type!");
 293
 294   // Write a 32bit value to relocation address, taking into account the
 295   // implicit addend encoded in the target.
 296   case ELF::R_ARM_TARGET1 :
 297   case ELF::R_ARM_ABS32 :
 298     *TargetPtr += Value;
 299     break;
 300
 301   // Write first 16 bit of 32 bit value to the mov instruction.
 302   // Last 4 bit should be shifted.
 303   case ELF::R_ARM_MOVW_ABS_NC :
 304     // We are not expecting any other addend in the relocation address.
 305     // Using 0x000F0FFF because MOVW has its 16 bit immediate split into 2
 306     // non-contiguous fields.
 307     assert((*TargetPtr & 0x000F0FFF) == 0);
 308     Value = Value & 0xFFFF;
 309     *TargetPtr |= Value & 0xFFF;
 310     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
 311     break;
 312
 313   // Write last 16 bit of 32 bit value to the mov instruction.
 314   // Last 4 bit should be shifted.
 315   case ELF::R_ARM_MOVT_ABS :
 316     // We are not expecting any other addend in the relocation address.
 317     // Use 0x000F0FFF for the same reason as R_ARM_MOVW_ABS_NC.
 318     assert((*TargetPtr & 0x000F0FFF) == 0);
 319     Value = (Value >> 16) & 0xFFFF;
 320     *TargetPtr |= Value & 0xFFF;
 321     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
 322     break;
 323
 324   // Write 24 bit relative value to the branch instruction.
 325   case ELF::R_ARM_PC24 :    // Fall through.
 326   case ELF::R_ARM_CALL :    // Fall through.
 327   case ELF::R_ARM_JUMP24 :
 328     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
 329     RelValue = (RelValue & 0x03FFFFFC) >> 2;
 330     *TargetPtr &= 0xFF000000;
 331     *TargetPtr |= RelValue;
 332     break;
 333   }
 334 }
 335
 336 void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
 337                                            uint64_t Offset,
 338                                            uint32_t Value,
 339                                            uint32_t Type,
 340                                            int32_t Addend) {
 341   uint32_t* TargetPtr = (uint32_t*)(Section.Address + Offset);
 342   Value += Addend;
 343
 344   DEBUG(dbgs() << "resolveMipselocation, LocalAddress: "
 345                << Section.Address + Offset
 346                << " FinalAddress: "
 347                << format("%p",Section.LoadAddress + Offset)
 348                << " Value: " << format("%x",Value)
 349                << " Type: " << format("%x",Type)
 350                << " Addend: " << format("%x",Addend)
 351                << "\n");
 352
 353   switch(Type) {
 354   default:
 355     llvm_unreachable("Not implemented relocation type!");
 356     break;
 357   case ELF::R_MIPS_32:
 358     *TargetPtr = Value + (*TargetPtr);
 359     break;
 360   case ELF::R_MIPS_26:
 361     *TargetPtr = ((*TargetPtr) & 0xfc000000) | (( Value & 0x0fffffff) >> 2);
 362     break;
 363   case ELF::R_MIPS_HI16:
 364     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
 365     Value += ((*TargetPtr) & 0x0000ffff) << 16;
 366     *TargetPtr = ((*TargetPtr) & 0xffff0000) |
 367                  (((Value + 0x8000) >> 16) & 0xffff);
 368     break;
 369    case ELF::R_MIPS_LO16:
 370     Value += ((*TargetPtr) & 0x0000ffff);
 371     *TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
 372     break;
 373    }
 374 }
 375
 376 // Return the .TOC. section address to R_PPC64_TOC relocations.
 377 uint64_t RuntimeDyldELF::findPPC64TOC() const {
 378   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
 379   // order. The TOC starts where the first of these sections starts.
 380   SectionList::const_iterator it = Sections.begin();
 381   SectionList::const_iterator ite = Sections.end();
 382   for (; it != ite; ++it) {
 383     if (it->Name == ".got" ||
 384         it->Name == ".toc" ||
 385         it->Name == ".tocbss" ||
 386         it->Name == ".plt")
 387       break;
 388   }
 389   if (it == ite) {
 390     // This may happen for
 391     // * references to TOC base base (sym@toc, .odp relocation) without
 392     // a .toc directive.
 393     // In this case just use the first section (which is usually
 394     // the .odp) since the code won't reference the .toc base
 395     // directly.
 396     it = Sections.begin();
 397   }
 398   assert (it != ite);
 399   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
 400   // thus permitting a full 64 Kbytes segment.
 401   return it->LoadAddress + 0x8000;
 402 }
 403
 404 // Returns the sections and offset associated with the ODP entry referenced
 405 // by Symbol.
 406 void RuntimeDyldELF::findOPDEntrySection(ObjectImage &Obj,
 407                                          ObjSectionToIDMap &LocalSections,
 408                                          RelocationValueRef &Rel) {
 409   // Get the ELF symbol value (st_value) to compare with Relocation offset in
 410   // .opd entries
 411
 412   error_code err;
 413   for (section_iterator si = Obj.begin_sections(),
 414      se = Obj.end_sections(); si != se; si.increment(err)) {
 415     StringRef SectionName;
 416     check(si->getName(SectionName));
 417     if (SectionName != ".opd")
 418       continue;
 419
 420     for (relocation_iterator i = si->begin_relocations(),
 421          e = si->end_relocations(); i != e;) {
 422       check(err);
 423
 424       // The R_PPC64_ADDR64 relocation indicates the first field
 425       // of a .opd entry
 426       uint64_t TypeFunc;
 427       check(i->getType(TypeFunc));
 428       if (TypeFunc != ELF::R_PPC64_ADDR64) {
 429         i.increment(err);
 430         continue;
 431       }
 432
 433       SymbolRef TargetSymbol;
 434       uint64_t TargetSymbolOffset;
 435       int64_t TargetAdditionalInfo;
 436       check(i->getSymbol(TargetSymbol));
 437       check(i->getOffset(TargetSymbolOffset));
 438       check(i->getAdditionalInfo(TargetAdditionalInfo));
 439
 440       i = i.increment(err);
 441       if (i == e)
 442         break;
 443       check(err);
 444
 445       // Just check if following relocation is a R_PPC64_TOC
 446       uint64_t TypeTOC;
 447       check(i->getType(TypeTOC));
 448       if (TypeTOC != ELF::R_PPC64_TOC)
 449         continue;
 450
 451       // Finally compares the Symbol value and the target symbol offset
 452       // to check if this .opd entry refers to the symbol the relocation
 453       // points to.
 454       if (Rel.Addend != (intptr_t)TargetSymbolOffset)
 455         continue;
 456
 457       section_iterator tsi(Obj.end_sections());
 458       check(TargetSymbol.getSection(tsi));
 459       Rel.SectionID = findOrEmitSection(Obj, (*tsi), true, LocalSections);
 460       Rel.Addend = (intptr_t)TargetAdditionalInfo;
 461       return;
 462     }
 463   }
 464   llvm_unreachable("Attempting to get address of ODP entry!");
 465 }
 466
 467 // Relocation masks following the #lo(value), #hi(value), #higher(value),
 468 // and #highest(value) macros defined in section 4.5.1. Relocation Types
 469 // in PPC-elf64abi document.
 470 //
 471 static inline
 472 uint16_t applyPPClo (uint64_t value)
 473 {
 474   return value & 0xffff;
 475 }
 476
 477 static inline
 478 uint16_t applyPPChi (uint64_t value)
 479 {
 480   return (value >> 16) & 0xffff;
 481 }
 482
 483 static inline
 484 uint16_t applyPPChigher (uint64_t value)
 485 {
 486   return (value >> 32) & 0xffff;
 487 }
 488
 489 static inline
 490 uint16_t applyPPChighest (uint64_t value)
 491 {
 492   return (value >> 48) & 0xffff;
 493 }
 494
 495 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
 496                                             uint64_t Offset,
 497                                             uint64_t Value,
 498                                             uint32_t Type,
 499                                             int64_t Addend) {
 500   uint8_t* LocalAddress = Section.Address + Offset;
 501   switch (Type) {
 502   default:
 503     llvm_unreachable("Relocation type not implemented yet!");
 504   break;
 505   case ELF::R_PPC64_ADDR16_LO :
 506     writeInt16BE(LocalAddress, applyPPClo (Value + Addend));
 507     break;
 508   case ELF::R_PPC64_ADDR16_HI :
 509     writeInt16BE(LocalAddress, applyPPChi (Value + Addend));
 510     break;
 511   case ELF::R_PPC64_ADDR16_HIGHER :
 512     writeInt16BE(LocalAddress, applyPPChigher (Value + Addend));
 513     break;
 514   case ELF::R_PPC64_ADDR16_HIGHEST :
 515     writeInt16BE(LocalAddress, applyPPChighest (Value + Addend));
 516     break;
 517   case ELF::R_PPC64_ADDR14 : {
 518     assert(((Value + Addend) & 3) == 0);
 519     // Preserve the AA/LK bits in the branch instruction
 520     uint8_t aalk = *(LocalAddress+3);
 521     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
 522   } break;
 523   case ELF::R_PPC64_ADDR32 : {
 524     int32_t Result = static_cast<int32_t>(Value + Addend);
 525     if (SignExtend32<32>(Result) != Result)
 526       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
 527     writeInt32BE(LocalAddress, Result);
 528   } break;
 529   case ELF::R_PPC64_REL24 : {
 530     uint64_t FinalAddress = (Section.LoadAddress + Offset);
 531     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
 532     if (SignExtend32<24>(delta) != delta)
 533       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
 534     // Generates a 'bl <address>' instruction
 535     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
 536   } break;
 537   case ELF::R_PPC64_REL32 : {
 538     uint64_t FinalAddress = (Section.LoadAddress + Offset);
 539     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
 540     if (SignExtend32<32>(delta) != delta)
 541       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
 542     writeInt32BE(LocalAddress, delta);
 543   } break;
 544   case ELF::R_PPC64_ADDR64 :
 545     writeInt64BE(LocalAddress, Value + Addend);
 546     break;
 547   case ELF::R_PPC64_TOC :
 548     writeInt64BE(LocalAddress, findPPC64TOC());
 549     break;
 550   case ELF::R_PPC64_TOC16 : {
 551     uint64_t TOCStart = findPPC64TOC();
 552     Value = applyPPClo((Value + Addend) - TOCStart);
 553     writeInt16BE(LocalAddress, applyPPClo(Value));
 554   } break;
 555   case ELF::R_PPC64_TOC16_DS : {
 556     uint64_t TOCStart = findPPC64TOC();
 557     Value = ((Value + Addend) - TOCStart);
 558     writeInt16BE(LocalAddress, applyPPClo(Value));
 559   } break;
 560   }
 561 }
 562
 563 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
 564                                        uint64_t Value) {
 565   const SectionEntry &Section = Sections[RE.SectionID];
 566   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend);
 567 }
 568
 569 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
 570                                        uint64_t Offset,
 571                                        uint64_t Value,
 572                                        uint32_t Type,
 573                                        int64_t Addend) {
 574   switch (Arch) {
 575   case Triple::x86_64:
 576     resolveX86_64Relocation(Section, Offset, Value, Type, Addend);
 577     break;
 578   case Triple::x86:
 579     resolveX86Relocation(Section, Offset,
 580                          (uint32_t)(Value & 0xffffffffL), Type,
 581                          (uint32_t)(Addend & 0xffffffffL));
 582     break;
 583   case Triple::arm:    // Fall through.
 584   case Triple::thumb:
 585     resolveARMRelocation(Section, Offset,
 586                          (uint32_t)(Value & 0xffffffffL), Type,
 587                          (uint32_t)(Addend & 0xffffffffL));
 588     break;
 589   case Triple::mips:    // Fall through.
 590   case Triple::mipsel:
 591     resolveMIPSRelocation(Section, Offset,
 592                           (uint32_t)(Value & 0xffffffffL), Type,
 593                           (uint32_t)(Addend & 0xffffffffL));
 594     break;
 595   case Triple::ppc64:
 596     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
 597     break;
 598   default: llvm_unreachable("Unsupported CPU type!");
 599   }
 600 }
 601
 602 void RuntimeDyldELF::processRelocationRef(unsigned SectionID,
 603                                           relocation_iterator RelI,
 604                                           ObjectImage &Obj,
 605                                           ObjSectionToIDMap &ObjSectionToID,
 606                                           const SymbolTableMap &Symbols,
 607                                           StubMap &Stubs) {
 608   uint64_t RelType;
 609   Check(RelI->getType(RelType));
 610   int64_t Addend;
 611   Check(RelI->getAdditionalInfo(Addend));
 612   SymbolRef Symbol;
 613   Check(RelI->getSymbol(Symbol));
 614
 615   // Obtain the symbol name which is referenced in the relocation
 616   StringRef TargetName;
 617   Symbol.getName(TargetName);
 618   DEBUG(dbgs() << "\t\tRelType: " << RelType
 619                << " Addend: " << Addend
 620                << " TargetName: " << TargetName
 621                << "\n");
 622   RelocationValueRef Value;
 623   // First search for the symbol in the local symbol table
 624   SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
 625   SymbolRef::Type SymType;
 626   Symbol.getType(SymType);
 627   if (lsi != Symbols.end()) {
 628     Value.SectionID = lsi->second.first;
 629     Value.Addend = lsi->second.second + Addend;
 630   } else {
 631     // Search for the symbol in the global symbol table
 632     SymbolTableMap::const_iterator gsi =
 633         GlobalSymbolTable.find(TargetName.data());
 634     if (gsi != GlobalSymbolTable.end()) {
 635       Value.SectionID = gsi->second.first;
 636       Value.Addend = gsi->second.second + Addend;
 637     } else {
 638       switch (SymType) {
 639         case SymbolRef::ST_Debug: {
 640           // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
 641           // and can be changed by another developers. Maybe best way is add
 642           // a new symbol type ST_Section to SymbolRef and use it.
 643           section_iterator si(Obj.end_sections());
 644           Symbol.getSection(si);
 645           if (si == Obj.end_sections())
 646             llvm_unreachable("Symbol section not found, bad object file format!");
 647           DEBUG(dbgs() << "\t\tThis is section symbol\n");
 648           // Default to 'true' in case isText fails (though it never does).
 649           bool isCode = true;
 650           si->isText(isCode);
 651           Value.SectionID = findOrEmitSection(Obj,
 652                                               (*si),
 653                                               isCode,
 654                                               ObjSectionToID);
 655           Value.Addend = Addend;
 656           break;
 657         }
 658         case SymbolRef::ST_Unknown: {
 659           Value.SymbolName = TargetName.data();
 660           Value.Addend = Addend;
 661           break;
 662         }
 663         default:
 664           llvm_unreachable("Unresolved symbol type!");
 665           break;
 666       }
 667     }
 668   }
 669   uint64_t Offset;
 670   Check(RelI->getOffset(Offset));
 671
 672   DEBUG(dbgs() << "\t\tSectionID: " << SectionID
 673                << " Offset: " << Offset
 674                << "\n");
 675   if (Arch == Triple::arm &&
 676       (RelType == ELF::R_ARM_PC24 ||
 677        RelType == ELF::R_ARM_CALL ||
 678        RelType == ELF::R_ARM_JUMP24)) {
 679     // This is an ARM branch relocation, need to use a stub function.
 680     DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
 681     SectionEntry &Section = Sections[SectionID];
 682
 683     // Look for an existing stub.
 684     StubMap::const_iterator i = Stubs.find(Value);
 685     if (i != Stubs.end()) {
 686         resolveRelocation(Section, Offset,
 687                           (uint64_t)Section.Address + i->second, RelType, 0);
 688       DEBUG(dbgs() << " Stub function found\n");
 689     } else {
 690       // Create a new stub function.
 691       DEBUG(dbgs() << " Create a new stub function\n");
 692       Stubs[Value] = Section.StubOffset;
 693       uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 694                                                    Section.StubOffset);
 695       RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
 696                          ELF::R_ARM_ABS32, Value.Addend);
 697       if (Value.SymbolName)
 698         addRelocationForSymbol(RE, Value.SymbolName);
 699       else
 700         addRelocationForSection(RE, Value.SectionID);
 701
 702       resolveRelocation(Section, Offset,
 703                         (uint64_t)Section.Address + Section.StubOffset,
 704                         RelType, 0);
 705       Section.StubOffset += getMaxStubSize();
 706     }
 707   } else if ((Arch == Triple::mipsel || Arch == Triple::mips) &&
 708              RelType == ELF::R_MIPS_26) {
 709     // This is an Mips branch relocation, need to use a stub function.
 710     DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
 711     SectionEntry &Section = Sections[SectionID];
 712     uint8_t *Target = Section.Address + Offset;
 713     uint32_t *TargetAddress = (uint32_t *)Target;
 714
 715     // Extract the addend from the instruction.
 716     uint32_t Addend = ((*TargetAddress) & 0x03ffffff) << 2;
 717
 718     Value.Addend += Addend;
 719
 720     //  Look up for existing stub.
 721     StubMap::const_iterator i = Stubs.find(Value);
 722     if (i != Stubs.end()) {
 723       resolveRelocation(Section, Offset,
 724                         (uint64_t)Section.Address + i->second, RelType, 0);
 725       DEBUG(dbgs() << " Stub function found\n");
 726     } else {
 727       // Create a new stub function.
 728       DEBUG(dbgs() << " Create a new stub function\n");
 729       Stubs[Value] = Section.StubOffset;
 730       uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 731                                                    Section.StubOffset);
 732
 733       // Creating Hi and Lo relocations for the filled stub instructions.
 734       RelocationEntry REHi(SectionID,
 735                            StubTargetAddr - Section.Address,
 736                            ELF::R_MIPS_HI16, Value.Addend);
 737       RelocationEntry RELo(SectionID,
 738                            StubTargetAddr - Section.Address + 4,
 739                            ELF::R_MIPS_LO16, Value.Addend);
 740
 741       if (Value.SymbolName) {
 742         addRelocationForSymbol(REHi, Value.SymbolName);
 743         addRelocationForSymbol(RELo, Value.SymbolName);
 744       } else {
 745         addRelocationForSection(REHi, Value.SectionID);
 746         addRelocationForSection(RELo, Value.SectionID);
 747       }
 748
 749       resolveRelocation(Section, Offset,
 750                         (uint64_t)Section.Address + Section.StubOffset,
 751                         RelType, 0);
 752       Section.StubOffset += getMaxStubSize();
 753     }
 754   } else if (Arch == Triple::ppc64) {
 755     if (RelType == ELF::R_PPC64_REL24) {
 756       // A PPC branch relocation will need a stub function if the target is
 757       // an external symbol (Symbol::ST_Unknown) or if the target address
 758       // is not within the signed 24-bits branch address.
 759       SectionEntry &Section = Sections[SectionID];
 760       uint8_t *Target = Section.Address + Offset;
 761       bool RangeOverflow = false;
 762       if (SymType != SymbolRef::ST_Unknown) {
 763         // A function call may points to the .opd entry, so the final symbol value
 764         // in calculated based in the relocation values in .opd section.
 765         findOPDEntrySection(Obj, ObjSectionToID, Value);
 766         uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
 767         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
 768         // If it is within 24-bits branch range, just set the branch target
 769         if (SignExtend32<24>(delta) == delta) {
 770           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
 771           if (Value.SymbolName)
 772             addRelocationForSymbol(RE, Value.SymbolName);
 773           else
 774             addRelocationForSection(RE, Value.SectionID);
 775         } else {
 776           RangeOverflow = true;
 777         }
 778       }
 779       if (SymType == SymbolRef::ST_Unknown || RangeOverflow == true) {
 780         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
 781         // larger than 24-bits.
 782         StubMap::const_iterator i = Stubs.find(Value);
 783         if (i != Stubs.end()) {
 784           // Symbol function stub already created, just relocate to it
 785           resolveRelocation(Section, Offset,
 786                             (uint64_t)Section.Address + i->second, RelType, 0);
 787           DEBUG(dbgs() << " Stub function found\n");
 788         } else {
 789           // Create a new stub function.
 790           DEBUG(dbgs() << " Create a new stub function\n");
 791           Stubs[Value] = Section.StubOffset;
 792           uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 793                                                        Section.StubOffset);
 794           RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
 795                              ELF::R_PPC64_ADDR64, Value.Addend);
 796
 797           // Generates the 64-bits address loads as exemplified in section
 798           // 4.5.1 in PPC64 ELF ABI.
 799           RelocationEntry REhst(SectionID,
 800                                 StubTargetAddr - Section.Address + 2,
 801                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
 802           RelocationEntry REhr(SectionID,
 803                                StubTargetAddr - Section.Address + 6,
 804                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
 805           RelocationEntry REh(SectionID,
 806                               StubTargetAddr - Section.Address + 14,
 807                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
 808           RelocationEntry REl(SectionID,
 809                               StubTargetAddr - Section.Address + 18,
 810                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
 811
 812           if (Value.SymbolName) {
 813             addRelocationForSymbol(REhst, Value.SymbolName);
 814             addRelocationForSymbol(REhr,  Value.SymbolName);
 815             addRelocationForSymbol(REh,   Value.SymbolName);
 816             addRelocationForSymbol(REl,   Value.SymbolName);
 817           } else {
 818             addRelocationForSection(REhst, Value.SectionID);
 819             addRelocationForSection(REhr,  Value.SectionID);
 820             addRelocationForSection(REh,   Value.SectionID);
 821             addRelocationForSection(REl,   Value.SectionID);
 822           }
 823
 824           resolveRelocation(Section, Offset,
 825                             (uint64_t)Section.Address + Section.StubOffset,
 826                             RelType, 0);
 827           if (SymType == SymbolRef::ST_Unknown)
 828             // Restore the TOC for external calls
 829             writeInt32BE(Target+4, 0xE8410028); // ld r2,40(r1)
 830           Section.StubOffset += getMaxStubSize();
 831         }
 832       }
 833     } else {
 834       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
 835       // Extra check to avoid relocation againt empty symbols (usually
 836       // the R_PPC64_TOC).
 837       if (Value.SymbolName && !TargetName.empty())
 838         addRelocationForSymbol(RE, Value.SymbolName);
 839       else
 840         addRelocationForSection(RE, Value.SectionID);
 841     }
 842   } else {
 843     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
 844     if (Value.SymbolName)
 845       addRelocationForSymbol(RE, Value.SymbolName);
 846     else
 847       addRelocationForSection(RE, Value.SectionID);
 848   }
 849 }
 850
 851 unsigned RuntimeDyldELF::getCommonSymbolAlignment(const SymbolRef &Sym) {
 852   // In ELF, the value of an SHN_COMMON symbol is its alignment requirement.
 853   uint64_t Align;
 854   Check(Sym.getValue(Align));
 855   return Align;
 856 }
 857
 858 bool RuntimeDyldELF::isCompatibleFormat(const ObjectBuffer *Buffer) const {
 859   if (Buffer->getBufferSize() < strlen(ELF::ElfMagic))
 860     return false;
 861   return (memcmp(Buffer->getBufferStart(), ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;
 862 }
 863 } // namespace llvm