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/OwningPtr.h"
  19 #include "llvm/ADT/StringRef.h"
  20 #include "llvm/ADT/STLExtras.h"
  21 #include "llvm/ADT/IntervalMap.h"
  22 #include "llvm/Object/ObjectFile.h"
  23 #include "llvm/ExecutionEngine/ObjectImage.h"
  24 #include "llvm/ExecutionEngine/ObjectBuffer.h"
  25 #include "llvm/Support/ELF.h"
  26 #include "llvm/ADT/Triple.h"
  27 #include "llvm/Object/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_ABS32 :
 294     *TargetPtr += Value;
 295     break;
 296
 297   // Write first 16 bit of 32 bit value to the mov instruction.
 298   // Last 4 bit should be shifted.
 299   case ELF::R_ARM_MOVW_ABS_NC :
 300     // We are not expecting any other addend in the relocation address.
 301     // Using 0x000F0FFF because MOVW has its 16 bit immediate split into 2
 302     // non-contiguous fields.
 303     assert((*TargetPtr & 0x000F0FFF) == 0);
 304     Value = Value & 0xFFFF;
 305     *TargetPtr |= Value & 0xFFF;
 306     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
 307     break;
 308
 309   // Write last 16 bit of 32 bit value to the mov instruction.
 310   // Last 4 bit should be shifted.
 311   case ELF::R_ARM_MOVT_ABS :
 312     // We are not expecting any other addend in the relocation address.
 313     // Use 0x000F0FFF for the same reason as R_ARM_MOVW_ABS_NC.
 314     assert((*TargetPtr & 0x000F0FFF) == 0);
 315     Value = (Value >> 16) & 0xFFFF;
 316     *TargetPtr |= Value & 0xFFF;
 317     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
 318     break;
 319
 320   // Write 24 bit relative value to the branch instruction.
 321   case ELF::R_ARM_PC24 :    // Fall through.
 322   case ELF::R_ARM_CALL :    // Fall through.
 323   case ELF::R_ARM_JUMP24 :
 324     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
 325     RelValue = (RelValue & 0x03FFFFFC) >> 2;
 326     *TargetPtr &= 0xFF000000;
 327     *TargetPtr |= RelValue;
 328     break;
 329   }
 330 }
 331
 332 void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
 333                                            uint64_t Offset,
 334                                            uint32_t Value,
 335                                            uint32_t Type,
 336                                            int32_t Addend) {
 337   uint32_t* TargetPtr = (uint32_t*)(Section.Address + Offset);
 338   Value += Addend;
 339
 340   DEBUG(dbgs() << "resolveMipselocation, LocalAddress: "
 341                << Section.Address + Offset
 342                << " FinalAddress: "
 343                << format("%p",Section.LoadAddress + Offset)
 344                << " Value: " << format("%x",Value)
 345                << " Type: " << format("%x",Type)
 346                << " Addend: " << format("%x",Addend)
 347                << "\n");
 348
 349   switch(Type) {
 350   default:
 351     llvm_unreachable("Not implemented relocation type!");
 352     break;
 353   case ELF::R_MIPS_32:
 354     *TargetPtr = Value + (*TargetPtr);
 355     break;
 356   case ELF::R_MIPS_26:
 357     *TargetPtr = ((*TargetPtr) & 0xfc000000) | (( Value & 0x0fffffff) >> 2);
 358     break;
 359   case ELF::R_MIPS_HI16:
 360     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
 361     Value += ((*TargetPtr) & 0x0000ffff) << 16;
 362     *TargetPtr = ((*TargetPtr) & 0xffff0000) |
 363                  (((Value + 0x8000) >> 16) & 0xffff);
 364     break;
 365    case ELF::R_MIPS_LO16:
 366     Value += ((*TargetPtr) & 0x0000ffff);
 367     *TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
 368     break;
 369    }
 370 }
 371
 372 // Return the .TOC. section address to R_PPC64_TOC relocations.
 373 uint64_t RuntimeDyldELF::findPPC64TOC() const {
 374   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
 375   // order. The TOC starts where the first of these sections starts.
 376   SectionList::const_iterator it = Sections.begin();
 377   SectionList::const_iterator ite = Sections.end();
 378   for (; it != ite; ++it) {
 379     if (it->Name == ".got" ||
 380         it->Name == ".toc" ||
 381         it->Name == ".tocbss" ||
 382         it->Name == ".plt")
 383       break;
 384   }
 385   if (it == ite) {
 386     // This may happen for
 387     // * references to TOC base base (sym@toc, .odp relocation) without
 388     // a .toc directive.
 389     // In this case just use the first section (which is usually
 390     // the .odp) since the code won't reference the .toc base
 391     // directly.
 392     it = Sections.begin();
 393   }
 394   assert (it != ite);
 395   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
 396   // thus permitting a full 64 Kbytes segment.
 397   return it->LoadAddress + 0x8000;
 398 }
 399
 400 // Returns the sections and offset associated with the ODP entry referenced
 401 // by Symbol.
 402 void RuntimeDyldELF::findOPDEntrySection(ObjectImage &Obj,
 403                                          ObjSectionToIDMap &LocalSections,
 404                                          RelocationValueRef &Rel) {
 405   // Get the ELF symbol value (st_value) to compare with Relocation offset in
 406   // .opd entries
 407
 408   error_code err;
 409   for (section_iterator si = Obj.begin_sections(),
 410      se = Obj.end_sections(); si != se; si.increment(err)) {
 411     StringRef SectionName;
 412     check(si->getName(SectionName));
 413     if (SectionName != ".opd")
 414       continue;
 415
 416     for (relocation_iterator i = si->begin_relocations(),
 417          e = si->end_relocations(); i != e;) {
 418       check(err);
 419
 420       // The R_PPC64_ADDR64 relocation indicates the first field
 421       // of a .opd entry
 422       uint64_t TypeFunc;
 423       check(i->getType(TypeFunc));
 424       if (TypeFunc != ELF::R_PPC64_ADDR64) {
 425         i.increment(err);
 426         continue;
 427       }
 428
 429       SymbolRef TargetSymbol;
 430       uint64_t TargetSymbolOffset;
 431       int64_t TargetAdditionalInfo;
 432       check(i->getSymbol(TargetSymbol));
 433       check(i->getOffset(TargetSymbolOffset));
 434       check(i->getAdditionalInfo(TargetAdditionalInfo));
 435
 436       i = i.increment(err);
 437       if (i == e)
 438         break;
 439       check(err);
 440
 441       // Just check if following relocation is a R_PPC64_TOC
 442       uint64_t TypeTOC;
 443       check(i->getType(TypeTOC));
 444       if (TypeTOC != ELF::R_PPC64_TOC)
 445         continue;
 446
 447       // Finally compares the Symbol value and the target symbol offset
 448       // to check if this .opd entry refers to the symbol the relocation
 449       // points to.
 450       if (Rel.Addend != (intptr_t)TargetSymbolOffset)
 451         continue;
 452
 453       section_iterator tsi(Obj.end_sections());
 454       check(TargetSymbol.getSection(tsi));
 455       Rel.SectionID = findOrEmitSection(Obj, (*tsi), true, LocalSections);
 456       Rel.Addend = (intptr_t)TargetAdditionalInfo;
 457       return;
 458     }
 459   }
 460   llvm_unreachable("Attempting to get address of ODP entry!");
 461 }
 462
 463 // Relocation masks following the #lo(value), #hi(value), #higher(value),
 464 // and #highest(value) macros defined in section 4.5.1. Relocation Types
 465 // in PPC-elf64abi document.
 466 //
 467 static inline
 468 uint16_t applyPPClo (uint64_t value)
 469 {
 470   return value & 0xffff;
 471 }
 472
 473 static inline
 474 uint16_t applyPPChi (uint64_t value)
 475 {
 476   return (value >> 16) & 0xffff;
 477 }
 478
 479 static inline
 480 uint16_t applyPPChigher (uint64_t value)
 481 {
 482   return (value >> 32) & 0xffff;
 483 }
 484
 485 static inline
 486 uint16_t applyPPChighest (uint64_t value)
 487 {
 488   return (value >> 48) & 0xffff;
 489 }
 490
 491 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
 492                                             uint64_t Offset,
 493                                             uint64_t Value,
 494                                             uint32_t Type,
 495                                             int64_t Addend) {
 496   uint8_t* LocalAddress = Section.Address + Offset;
 497   switch (Type) {
 498   default:
 499     llvm_unreachable("Relocation type not implemented yet!");
 500   break;
 501   case ELF::R_PPC64_ADDR16_LO :
 502     writeInt16BE(LocalAddress, applyPPClo (Value + Addend));
 503     break;
 504   case ELF::R_PPC64_ADDR16_HI :
 505     writeInt16BE(LocalAddress, applyPPChi (Value + Addend));
 506     break;
 507   case ELF::R_PPC64_ADDR16_HIGHER :
 508     writeInt16BE(LocalAddress, applyPPChigher (Value + Addend));
 509     break;
 510   case ELF::R_PPC64_ADDR16_HIGHEST :
 511     writeInt16BE(LocalAddress, applyPPChighest (Value + Addend));
 512     break;
 513   case ELF::R_PPC64_ADDR14 : {
 514     assert(((Value + Addend) & 3) == 0);
 515     // Preserve the AA/LK bits in the branch instruction
 516     uint8_t aalk = *(LocalAddress+3);
 517     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
 518   } break;
 519   case ELF::R_PPC64_REL24 : {
 520     uint64_t FinalAddress = (Section.LoadAddress + Offset);
 521     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
 522     if (SignExtend32<24>(delta) != delta)
 523       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
 524     // Generates a 'bl <address>' instruction
 525     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
 526   } break;
 527   case ELF::R_PPC64_ADDR64 :
 528     writeInt64BE(LocalAddress, Value + Addend);
 529     break;
 530   case ELF::R_PPC64_TOC :
 531     writeInt64BE(LocalAddress, findPPC64TOC());
 532     break;
 533   case ELF::R_PPC64_TOC16 : {
 534     uint64_t TOCStart = findPPC64TOC();
 535     Value = applyPPClo((Value + Addend) - TOCStart);
 536     writeInt16BE(LocalAddress, applyPPClo(Value));
 537   } break;
 538   case ELF::R_PPC64_TOC16_DS : {
 539     uint64_t TOCStart = findPPC64TOC();
 540     Value = ((Value + Addend) - TOCStart);
 541     writeInt16BE(LocalAddress, applyPPClo(Value));
 542   } break;
 543   }
 544 }
 545
 546
 547 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
 548                                        uint64_t Offset,
 549                                        uint64_t Value,
 550                                        uint32_t Type,
 551                                        int64_t Addend) {
 552   switch (Arch) {
 553   case Triple::x86_64:
 554     resolveX86_64Relocation(Section, Offset, Value, Type, Addend);
 555     break;
 556   case Triple::x86:
 557     resolveX86Relocation(Section, Offset,
 558                          (uint32_t)(Value & 0xffffffffL), Type,
 559                          (uint32_t)(Addend & 0xffffffffL));
 560     break;
 561   case Triple::arm:    // Fall through.
 562   case Triple::thumb:
 563     resolveARMRelocation(Section, Offset,
 564                          (uint32_t)(Value & 0xffffffffL), Type,
 565                          (uint32_t)(Addend & 0xffffffffL));
 566     break;
 567   case Triple::mips:    // Fall through.
 568   case Triple::mipsel:
 569     resolveMIPSRelocation(Section, Offset,
 570                           (uint32_t)(Value & 0xffffffffL), Type,
 571                           (uint32_t)(Addend & 0xffffffffL));
 572     break;
 573   case Triple::ppc64:
 574     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
 575     break;
 576   default: llvm_unreachable("Unsupported CPU type!");
 577   }
 578 }
 579
 580 void RuntimeDyldELF::processRelocationRef(const ObjRelocationInfo &Rel,
 581                                           ObjectImage &Obj,
 582                                           ObjSectionToIDMap &ObjSectionToID,
 583                                           const SymbolTableMap &Symbols,
 584                                           StubMap &Stubs) {
 585
 586   uint32_t RelType = (uint32_t)(Rel.Type & 0xffffffffL);
 587   intptr_t Addend = (intptr_t)Rel.AdditionalInfo;
 588   const SymbolRef &Symbol = Rel.Symbol;
 589
 590   // Obtain the symbol name which is referenced in the relocation
 591   StringRef TargetName;
 592   Symbol.getName(TargetName);
 593   DEBUG(dbgs() << "\t\tRelType: " << RelType
 594                << " Addend: " << Addend
 595                << " TargetName: " << TargetName
 596                << "\n");
 597   RelocationValueRef Value;
 598   // First search for the symbol in the local symbol table
 599   SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
 600   SymbolRef::Type SymType;
 601   Symbol.getType(SymType);
 602   if (lsi != Symbols.end()) {
 603     Value.SectionID = lsi->second.first;
 604     Value.Addend = lsi->second.second;
 605   } else {
 606     // Search for the symbol in the global symbol table
 607     SymbolTableMap::const_iterator gsi =
 608         GlobalSymbolTable.find(TargetName.data());
 609     if (gsi != GlobalSymbolTable.end()) {
 610       Value.SectionID = gsi->second.first;
 611       Value.Addend = gsi->second.second;
 612     } else {
 613       switch (SymType) {
 614         case SymbolRef::ST_Debug: {
 615           // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
 616           // and can be changed by another developers. Maybe best way is add
 617           // a new symbol type ST_Section to SymbolRef and use it.
 618           section_iterator si(Obj.end_sections());
 619           Symbol.getSection(si);
 620           if (si == Obj.end_sections())
 621             llvm_unreachable("Symbol section not found, bad object file format!");
 622           DEBUG(dbgs() << "\t\tThis is section symbol\n");
 623           // Default to 'true' in case isText fails (though it never does).
 624           bool isCode = true;
 625           si->isText(isCode);
 626           Value.SectionID = findOrEmitSection(Obj,
 627                                               (*si),
 628                                               isCode,
 629                                               ObjSectionToID);
 630           Value.Addend = Addend;
 631           break;
 632         }
 633         case SymbolRef::ST_Unknown: {
 634           Value.SymbolName = TargetName.data();
 635           Value.Addend = Addend;
 636           break;
 637         }
 638         default:
 639           llvm_unreachable("Unresolved symbol type!");
 640           break;
 641       }
 642     }
 643   }
 644   DEBUG(dbgs() << "\t\tRel.SectionID: " << Rel.SectionID
 645                << " Rel.Offset: " << Rel.Offset
 646                << "\n");
 647   if (Arch == Triple::arm &&
 648       (RelType == ELF::R_ARM_PC24 ||
 649        RelType == ELF::R_ARM_CALL ||
 650        RelType == ELF::R_ARM_JUMP24)) {
 651     // This is an ARM branch relocation, need to use a stub function.
 652     DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
 653     SectionEntry &Section = Sections[Rel.SectionID];
 654
 655     // Look for an existing stub.
 656     StubMap::const_iterator i = Stubs.find(Value);
 657     if (i != Stubs.end()) {
 658         resolveRelocation(Section, Rel.Offset,
 659                           (uint64_t)Section.Address + i->second, RelType, 0);
 660       DEBUG(dbgs() << " Stub function found\n");
 661     } else {
 662       // Create a new stub function.
 663       DEBUG(dbgs() << " Create a new stub function\n");
 664       Stubs[Value] = Section.StubOffset;
 665       uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 666                                                    Section.StubOffset);
 667       RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
 668                          ELF::R_ARM_ABS32, Value.Addend);
 669       if (Value.SymbolName)
 670         addRelocationForSymbol(RE, Value.SymbolName);
 671       else
 672         addRelocationForSection(RE, Value.SectionID);
 673
 674       resolveRelocation(Section, Rel.Offset,
 675                         (uint64_t)Section.Address + Section.StubOffset,
 676                         RelType, 0);
 677       Section.StubOffset += getMaxStubSize();
 678     }
 679   } else if (Arch == Triple::mipsel && RelType == ELF::R_MIPS_26) {
 680     // This is an Mips branch relocation, need to use a stub function.
 681     DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
 682     SectionEntry &Section = Sections[Rel.SectionID];
 683     uint8_t *Target = Section.Address + Rel.Offset;
 684     uint32_t *TargetAddress = (uint32_t *)Target;
 685
 686     // Extract the addend from the instruction.
 687     uint32_t Addend = ((*TargetAddress) & 0x03ffffff) << 2;
 688
 689     Value.Addend += Addend;
 690
 691     //  Look up for existing stub.
 692     StubMap::const_iterator i = Stubs.find(Value);
 693     if (i != Stubs.end()) {
 694       resolveRelocation(Section, Rel.Offset,
 695                         (uint64_t)Section.Address + i->second, RelType, 0);
 696       DEBUG(dbgs() << " Stub function found\n");
 697     } else {
 698       // Create a new stub function.
 699       DEBUG(dbgs() << " Create a new stub function\n");
 700       Stubs[Value] = Section.StubOffset;
 701       uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 702                                                    Section.StubOffset);
 703
 704       // Creating Hi and Lo relocations for the filled stub instructions.
 705       RelocationEntry REHi(Rel.SectionID,
 706                            StubTargetAddr - Section.Address,
 707                            ELF::R_MIPS_HI16, Value.Addend);
 708       RelocationEntry RELo(Rel.SectionID,
 709                            StubTargetAddr - Section.Address + 4,
 710                            ELF::R_MIPS_LO16, Value.Addend);
 711
 712       if (Value.SymbolName) {
 713         addRelocationForSymbol(REHi, Value.SymbolName);
 714         addRelocationForSymbol(RELo, Value.SymbolName);
 715       } else {
 716         addRelocationForSection(REHi, Value.SectionID);
 717         addRelocationForSection(RELo, Value.SectionID);
 718       }
 719
 720       resolveRelocation(Section, Rel.Offset,
 721                         (uint64_t)Section.Address + Section.StubOffset,
 722                         RelType, 0);
 723       Section.StubOffset += getMaxStubSize();
 724     }
 725   } else if (Arch == Triple::ppc64) {
 726     if (RelType == ELF::R_PPC64_REL24) {
 727       // A PPC branch relocation will need a stub function if the target is
 728       // an external symbol (Symbol::ST_Unknown) or if the target address
 729       // is not within the signed 24-bits branch address.
 730       SectionEntry &Section = Sections[Rel.SectionID];
 731       uint8_t *Target = Section.Address + Rel.Offset;
 732       bool RangeOverflow = false;
 733       if (SymType != SymbolRef::ST_Unknown) {
 734         // A function call may points to the .opd entry, so the final symbol value
 735         // in calculated based in the relocation values in .opd section.
 736         findOPDEntrySection(Obj, ObjSectionToID, Value);
 737         uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
 738         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
 739         // If it is within 24-bits branch range, just set the branch target
 740         if (SignExtend32<24>(delta) == delta) {
 741           RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
 742           if (Value.SymbolName)
 743             addRelocationForSymbol(RE, Value.SymbolName);
 744           else
 745             addRelocationForSection(RE, Value.SectionID);
 746         } else {
 747           RangeOverflow = true;
 748         }
 749       }
 750       if (SymType == SymbolRef::ST_Unknown || RangeOverflow == true) {
 751         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
 752         // larger than 24-bits.
 753         StubMap::const_iterator i = Stubs.find(Value);
 754         if (i != Stubs.end()) {
 755           // Symbol function stub already created, just relocate to it
 756           resolveRelocation(Section, Rel.Offset,
 757                             (uint64_t)Section.Address + i->second, RelType, 0);
 758           DEBUG(dbgs() << " Stub function found\n");
 759         } else {
 760           // Create a new stub function.
 761           DEBUG(dbgs() << " Create a new stub function\n");
 762           Stubs[Value] = Section.StubOffset;
 763           uint8_t *StubTargetAddr = createStubFunction(Section.Address +
 764                                                        Section.StubOffset);
 765           RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
 766                              ELF::R_PPC64_ADDR64, Value.Addend);
 767
 768           // Generates the 64-bits address loads as exemplified in section
 769           // 4.5.1 in PPC64 ELF ABI.
 770           RelocationEntry REhst(Rel.SectionID,
 771                                 StubTargetAddr - Section.Address + 2,
 772                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
 773           RelocationEntry REhr(Rel.SectionID,
 774                                StubTargetAddr - Section.Address + 6,
 775                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
 776           RelocationEntry REh(Rel.SectionID,
 777                               StubTargetAddr - Section.Address + 14,
 778                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
 779           RelocationEntry REl(Rel.SectionID,
 780                               StubTargetAddr - Section.Address + 18,
 781                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
 782
 783           if (Value.SymbolName) {
 784             addRelocationForSymbol(REhst, Value.SymbolName);
 785             addRelocationForSymbol(REhr,  Value.SymbolName);
 786             addRelocationForSymbol(REh,   Value.SymbolName);
 787             addRelocationForSymbol(REl,   Value.SymbolName);
 788           } else {
 789             addRelocationForSection(REhst, Value.SectionID);
 790             addRelocationForSection(REhr,  Value.SectionID);
 791             addRelocationForSection(REh,   Value.SectionID);
 792             addRelocationForSection(REl,   Value.SectionID);
 793           }
 794
 795           resolveRelocation(Section, Rel.Offset,
 796                             (uint64_t)Section.Address + Section.StubOffset,
 797                             RelType, 0);
 798           if (SymType == SymbolRef::ST_Unknown)
 799             // Restore the TOC for external calls
 800             writeInt32BE(Target+4, 0xE8410028); // ld r2,40(r1)
 801           Section.StubOffset += getMaxStubSize();
 802         }
 803       }
 804     } else {
 805       RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
 806       // Extra check to avoid relocation againt empty symbols (usually
 807       // the R_PPC64_TOC).
 808       if (Value.SymbolName && !TargetName.empty())
 809         addRelocationForSymbol(RE, Value.SymbolName);
 810       else
 811         addRelocationForSection(RE, Value.SectionID);
 812     }
 813   } else {
 814     RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
 815     if (Value.SymbolName)
 816       addRelocationForSymbol(RE, Value.SymbolName);
 817     else
 818       addRelocationForSection(RE, Value.SectionID);
 819   }
 820 }
 821
 822 unsigned RuntimeDyldELF::getCommonSymbolAlignment(const SymbolRef &Sym) {
 823   // In ELF, the value of an SHN_COMMON symbol is its alignment requirement.
 824   uint64_t Align;
 825   Check(Sym.getValue(Align));
 826   return Align;
 827 }
 828
 829 bool RuntimeDyldELF::isCompatibleFormat(const ObjectBuffer *Buffer) const {
 830   if (Buffer->getBufferSize() < strlen(ELF::ElfMagic))
 831     return false;
 832   return (memcmp(Buffer->getBufferStart(), ELF::ElfMagic, strlen(ELF::ElfMagic))) == 0;
 833 }
 834 } // namespace llvm