lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

   1 //===-- RuntimeDyld.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 the MC-JIT runtime dynamic linker.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #define DEBUG_TYPE "dyld"
  15 #include "RuntimeDyldImpl.h"
  16 #include "RuntimeDyldELF.h"
  17 #include "RuntimeDyldMachO.h"
  18 #include "llvm/Support/Path.h"
  19
  20 using namespace llvm;
  21 using namespace llvm::object;
  22
  23 // Empty out-of-line virtual destructor as the key function.
  24 RTDyldMemoryManager::~RTDyldMemoryManager() {}
  25 RuntimeDyldImpl::~RuntimeDyldImpl() {}
  26
  27 namespace llvm {
  28
  29 namespace {
  30   // Helper for extensive error checking in debug builds.
  31   error_code Check(error_code Err) {
  32     if (Err) {
  33       report_fatal_error(Err.message());
  34     }
  35     return Err;
  36   }
  37 } // end anonymous namespace
  38
  39 // Resolve the relocations for all symbols we currently know about.
  40 void RuntimeDyldImpl::resolveRelocations() {
  41   // First, resolve relocations associated with external symbols.
  42   resolveSymbols();
  43
  44   // Just iterate over the sections we have and resolve all the relocations
  45   // in them. Gross overkill, but it gets the job done.
  46   for (int i = 0, e = Sections.size(); i != e; ++i) {
  47     reassignSectionAddress(i, Sections[i].LoadAddress);
  48   }
  49 }
  50
  51 void RuntimeDyldImpl::mapSectionAddress(void *LocalAddress,
  52                                         uint64_t TargetAddress) {
  53   for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
  54     if (Sections[i].Address == LocalAddress) {
  55       reassignSectionAddress(i, TargetAddress);
  56       return;
  57     }
  58   }
  59   llvm_unreachable("Attempting to remap address of unknown section!");
  60 }
  61
  62 bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
  63   // FIXME: ObjectFile don't modify MemoryBuffer.
  64   //        It should use const MemoryBuffer as parameter.
  65   OwningPtr<ObjectFile> obj(ObjectFile::createObjectFile(
  66                                        const_cast<MemoryBuffer*>(InputBuffer)));
  67   if (!obj)
  68     report_fatal_error("Unable to create object image from memory buffer!");
  69
  70   Arch = (Triple::ArchType)obj->getArch();
  71
  72   LocalSymbolMap LocalSymbols;     // Functions and data symbols from the
  73                                    // object file.
  74   ObjSectionToIDMap LocalSections; // Used sections from the object file
  75   CommonSymbolMap   CommonSymbols; // Common symbols requiring allocation
  76   uint64_t          CommonSize = 0;
  77
  78   error_code err;
  79   // Parse symbols
  80   DEBUG(dbgs() << "Parse symbols:\n");
  81   for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
  82        i != e; i.increment(err)) {
  83     Check(err);
  84     object::SymbolRef::Type SymType;
  85     StringRef Name;
  86     Check(i->getType(SymType));
  87     Check(i->getName(Name));
  88
  89     uint32_t flags;
  90     Check(i->getFlags(flags));
  91
  92     bool isCommon = flags & SymbolRef::SF_Common;
  93     if (isCommon) {
  94       // Add the common symbols to a list.  We'll allocate them all below.
  95       uint64_t Size = 0;
  96       Check(i->getSize(Size));
  97       CommonSize += Size;
  98       CommonSymbols[*i] = Size;
  99     } else {
 100       if (SymType == object::SymbolRef::ST_Function ||
 101           SymType == object::SymbolRef::ST_Data) {
 102         uint64_t FileOffset;
 103         StringRef sData;
 104         section_iterator si = obj->end_sections();
 105         Check(i->getFileOffset(FileOffset));
 106         Check(i->getSection(si));
 107         if (si == obj->end_sections()) continue;
 108         Check(si->getContents(sData));
 109         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
 110                                 (uintptr_t)FileOffset;
 111         uintptr_t SectOffset = (uintptr_t)(SymPtr - (const uint8_t*)sData.begin());
 112         unsigned SectionID =
 113           findOrEmitSection(*si,
 114                             SymType == object::SymbolRef::ST_Function,
 115                             LocalSections);
 116         bool isGlobal = flags & SymbolRef::SF_Global;
 117         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 118         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 119                      << " flags: " << flags
 120                      << " SID: " << SectionID
 121                      << " Offset: " << format("%p", SectOffset));
 122         if (isGlobal)
 123           SymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 124       }
 125     }
 126     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 127   }
 128
 129   // Allocate common symbols
 130   if (CommonSize != 0)
 131     emitCommonSymbols(CommonSymbols, CommonSize, LocalSymbols);
 132
 133   // Parse and proccess relocations
 134   DEBUG(dbgs() << "Parse relocations:\n");
 135   for (section_iterator si = obj->begin_sections(),
 136        se = obj->end_sections(); si != se; si.increment(err)) {
 137     Check(err);
 138     bool isFirstRelocation = true;
 139     unsigned SectionID = 0;
 140     StubMap Stubs;
 141
 142     for (relocation_iterator i = si->begin_relocations(),
 143          e = si->end_relocations(); i != e; i.increment(err)) {
 144       Check(err);
 145
 146       // If it's first relocation in this section, find its SectionID
 147       if (isFirstRelocation) {
 148         SectionID = findOrEmitSection(*si, true, LocalSections);
 149         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 150         isFirstRelocation = false;
 151       }
 152
 153       ObjRelocationInfo RI;
 154       RI.SectionID = SectionID;
 155       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 156       Check(i->getOffset(RI.Offset));
 157       Check(i->getSymbol(RI.Symbol));
 158       Check(i->getType(RI.Type));
 159
 160       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 161                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 162                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 163                    << "\n");
 164       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 165     }
 166   }
 167   return false;
 168 }
 169
 170 unsigned RuntimeDyldImpl::emitCommonSymbols(const CommonSymbolMap &Map,
 171                                             uint64_t TotalSize,
 172                                             LocalSymbolMap &LocalSymbols) {
 173   // Allocate memory for the section
 174   unsigned SectionID = Sections.size();
 175   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 176                                               SectionID);
 177   if (!Addr)
 178     report_fatal_error("Unable to allocate memory for common symbols!");
 179   uint64_t Offset = 0;
 180   Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
 181   memset(Addr, 0, TotalSize);
 182
 183   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 184                << " new addr: " << format("%p", Addr)
 185                << " DataSize: " << TotalSize
 186                << "\n");
 187
 188   // Assign the address of each symbol
 189   for (CommonSymbolMap::const_iterator it = Map.begin(), itEnd = Map.end();
 190        it != itEnd; it++) {
 191     uint64_t Size = it->second;
 192     StringRef Name;
 193     it->first.getName(Name);
 194     LocalSymbols[Name.data()] = SymbolLoc(SectionID, Offset);
 195     Offset += Size;
 196     Addr += Size;
 197   }
 198
 199   return SectionID;
 200 }
 201
 202 unsigned RuntimeDyldImpl::emitSection(const SectionRef &Section,
 203                                       bool IsCode) {
 204
 205   unsigned StubBufSize = 0,
 206            StubSize = getMaxStubSize();
 207   error_code err;
 208   if (StubSize > 0) {
 209     for (relocation_iterator i = Section.begin_relocations(),
 210          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 211       StubBufSize += StubSize;
 212   }
 213   StringRef data;
 214   uint64_t Alignment64;
 215   Check(Section.getContents(data));
 216   Check(Section.getAlignment(Alignment64));
 217
 218   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 219   bool IsRequired;
 220   bool IsVirtual;
 221   bool IsZeroInit;
 222   uint64_t DataSize;
 223   Check(Section.isRequiredForExecution(IsRequired));
 224   Check(Section.isVirtual(IsVirtual));
 225   Check(Section.isZeroInit(IsZeroInit));
 226   Check(Section.getSize(DataSize));
 227
 228   unsigned Allocate;
 229   unsigned SectionID = Sections.size();
 230   uint8_t *Addr;
 231   const char *pData = 0;
 232
 233   // Some sections, such as debug info, don't need to be loaded for execution.
 234   // Leave those where they are.
 235   if (IsRequired) {
 236     Allocate = DataSize + StubBufSize;
 237     Addr = IsCode
 238       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 239       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
 240     if (!Addr)
 241       report_fatal_error("Unable to allocate section memory!");
 242
 243     // Virtual sections have no data in the object image, so leave pData = 0
 244     if (!IsVirtual)
 245       pData = data.data();
 246
 247     // Zero-initialize or copy the data from the image
 248     if (IsZeroInit || IsVirtual)
 249       memset(Addr, 0, DataSize);
 250     else
 251       memcpy(Addr, pData, DataSize);
 252
 253     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 254                  << " obj addr: " << format("%p", pData)
 255                  << " new addr: " << format("%p", Addr)
 256                  << " DataSize: " << DataSize
 257                  << " StubBufSize: " << StubBufSize
 258                  << " Allocate: " << Allocate
 259                  << "\n");
 260   }
 261   else {
 262     // Even if we didn't load the section, we need to record an entry for it
 263     //   to handle later processing (and by 'handle' I mean don't do anything
 264     //   with these sections).
 265     Allocate = 0;
 266     Addr = 0;
 267     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 268                  << " obj addr: " << format("%p", data.data())
 269                  << " new addr: 0"
 270                  << " DataSize: " << DataSize
 271                  << " StubBufSize: " << StubBufSize
 272                  << " Allocate: " << Allocate
 273                  << "\n");
 274   }
 275
 276   Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
 277   return SectionID;
 278 }
 279
 280 unsigned RuntimeDyldImpl::findOrEmitSection(const SectionRef &Section,
 281                                             bool IsCode,
 282                                             ObjSectionToIDMap &LocalSections) {
 283
 284   unsigned SectionID = 0;
 285   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 286   if (i != LocalSections.end())
 287     SectionID = i->second;
 288   else {
 289     SectionID = emitSection(Section, IsCode);
 290     LocalSections[Section] = SectionID;
 291   }
 292   return SectionID;
 293 }
 294
 295 void RuntimeDyldImpl::AddRelocation(const RelocationValueRef &Value,
 296                                    unsigned SectionID, uintptr_t Offset,
 297                                    uint32_t RelType) {
 298   DEBUG(dbgs() << "AddRelocation SymNamePtr: " << format("%p", Value.SymbolName)
 299                << " SID: " << Value.SectionID
 300                << " Addend: " << format("%p", Value.Addend)
 301                << " Offset: " << format("%p", Offset)
 302                << " RelType: " << format("%x", RelType)
 303                << "\n");
 304
 305   if (Value.SymbolName == 0) {
 306     Relocations[Value.SectionID].push_back(RelocationEntry(
 307       SectionID,
 308       Offset,
 309       RelType,
 310       Value.Addend));
 311   } else
 312     SymbolRelocations[Value.SymbolName].push_back(RelocationEntry(
 313       SectionID,
 314       Offset,
 315       RelType,
 316       Value.Addend));
 317 }
 318
 319 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 320   // TODO: There is only ARM far stub now. We should add the Thumb stub,
 321   // and stubs for branches Thumb - ARM and ARM - Thumb.
 322   if (Arch == Triple::arm) {
 323     uint32_t *StubAddr = (uint32_t*)Addr;
 324     *StubAddr = 0xe51ff004; // ldr pc,<label>
 325     return (uint8_t*)++StubAddr;
 326   }
 327   else
 328     return Addr;
 329 }
 330
 331 // Assign an address to a symbol name and resolve all the relocations
 332 // associated with it.
 333 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 334                                              uint64_t Addr) {
 335   // The address to use for relocation resolution is not
 336   // the address of the local section buffer. We must be doing
 337   // a remote execution environment of some sort. Re-apply any
 338   // relocations referencing this section with the given address.
 339   //
 340   // Addr is a uint64_t because we can't assume the pointer width
 341   // of the target is the same as that of the host. Just use a generic
 342   // "big enough" type.
 343   Sections[SectionID].LoadAddress = Addr;
 344   DEBUG(dbgs() << "Resolving relocations Section #" << SectionID
 345           << "\t" << format("%p", (uint8_t *)Addr)
 346           << "\n");
 347   resolveRelocationList(Relocations[SectionID], Addr);
 348 }
 349
 350 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
 351                                              uint64_t Value) {
 352     // Ignore relocations for sections that were not loaded
 353     if (Sections[RE.SectionID].Address != 0) {
 354       uint8_t *Target = Sections[RE.SectionID].Address + RE.Offset;
 355       DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
 356             << " + " << RE.Offset << " (" << format("%p", Target) << ")"
 357             << " Data: " << RE.Data
 358             << " Addend: " << RE.Addend
 359             << "\n");
 360
 361       resolveRelocation(Target, Sections[RE.SectionID].LoadAddress + RE.Offset,
 362                         Value, RE.Data, RE.Addend);
 363   }
 364 }
 365
 366 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 367                                             uint64_t Value) {
 368   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 369     resolveRelocationEntry(Relocs[i], Value);
 370   }
 371 }
 372
 373 // resolveSymbols - Resolve any relocations to the specified symbols if
 374 // we know where it lives.
 375 void RuntimeDyldImpl::resolveSymbols() {
 376   StringMap<RelocationList>::iterator i = SymbolRelocations.begin(),
 377                                       e = SymbolRelocations.end();
 378   for (; i != e; i++) {
 379     StringRef Name = i->first();
 380     RelocationList &Relocs = i->second;
 381     StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
 382     if (Loc == SymbolTable.end()) {
 383       // This is an external symbol, try to get it address from
 384       // MemoryManager.
 385       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 386                                                                    true);
 387       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 388               << "\t" << format("%p", Addr)
 389               << "\n");
 390       resolveRelocationList(Relocs, (uintptr_t)Addr);
 391     } else {
 392       // Change the relocation to be section relative rather than symbol
 393       // relative and move it to the resolved relocation list.
 394       DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
 395       for (int i = 0, e = Relocs.size(); i != e; ++i) {
 396         RelocationEntry Entry = Relocs[i];
 397         Entry.Addend += Loc->second.second;
 398         Relocations[Loc->second.first].push_back(Entry);
 399       }
 400       Relocs.clear();
 401     }
 402   }
 403 }
 404
 405
 406 //===----------------------------------------------------------------------===//
 407 // RuntimeDyld class implementation
 408 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 409   Dyld = 0;
 410   MM = mm;
 411 }
 412
 413 RuntimeDyld::~RuntimeDyld() {
 414   delete Dyld;
 415 }
 416
 417 bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
 418   if (!Dyld) {
 419     sys::LLVMFileType type = sys::IdentifyFileType(
 420             InputBuffer->getBufferStart(),
 421             static_cast<unsigned>(InputBuffer->getBufferSize()));
 422     switch (type) {
 423       case sys::ELF_Relocatable_FileType:
 424       case sys::ELF_Executable_FileType:
 425       case sys::ELF_SharedObject_FileType:
 426       case sys::ELF_Core_FileType:
 427         Dyld = new RuntimeDyldELF(MM);
 428         break;
 429       case sys::Mach_O_Object_FileType:
 430       case sys::Mach_O_Executable_FileType:
 431       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 432       case sys::Mach_O_Core_FileType:
 433       case sys::Mach_O_PreloadExecutable_FileType:
 434       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 435       case sys::Mach_O_DynamicLinker_FileType:
 436       case sys::Mach_O_Bundle_FileType:
 437       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 438       case sys::Mach_O_DSYMCompanion_FileType:
 439         Dyld = new RuntimeDyldMachO(MM);
 440         break;
 441       case sys::Unknown_FileType:
 442       case sys::Bitcode_FileType:
 443       case sys::Archive_FileType:
 444       case sys::COFF_FileType:
 445         report_fatal_error("Incompatible object format!");
 446     }
 447   } else {
 448     if (!Dyld->isCompatibleFormat(InputBuffer))
 449       report_fatal_error("Incompatible object format!");
 450   }
 451
 452   return Dyld->loadObject(InputBuffer);
 453 }
 454
 455 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 456   return Dyld->getSymbolAddress(Name);
 457 }
 458
 459 void RuntimeDyld::resolveRelocations() {
 460   Dyld->resolveRelocations();
 461 }
 462
 463 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 464                                          uint64_t Addr) {
 465   Dyld->reassignSectionAddress(SectionID, Addr);
 466 }
 467
 468 void RuntimeDyld::mapSectionAddress(void *LocalAddress,
 469                                     uint64_t TargetAddress) {
 470   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 471 }
 472
 473 StringRef RuntimeDyld::getErrorString() {
 474   return Dyld->getErrorString();
 475 }
 476
 477 } // end namespace llvm