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 // Subclasses can implement this method to create specialized image instances.
  63 // The caller owns the the pointer that is returned.
  64 ObjectImage *RuntimeDyldImpl::createObjectImage(const MemoryBuffer *InputBuffer) {
  65   ObjectFile *ObjFile = ObjectFile::createObjectFile(const_cast<MemoryBuffer*>
  66                                                                  (InputBuffer));
  67   ObjectImage *Obj = new ObjectImage(ObjFile);
  68   return Obj;
  69 }
  70
  71 bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
  72   OwningPtr<ObjectImage> obj(createObjectImage(InputBuffer));
  73   if (!obj)
  74     report_fatal_error("Unable to create object image from memory buffer!");
  75
  76   Arch = (Triple::ArchType)obj->getArch();
  77
  78   LocalSymbolMap    LocalSymbols;  // Functions and data symbols from the
  79                                    // object file.
  80   ObjSectionToIDMap LocalSections; // Used sections from the object file
  81   CommonSymbolMap   CommonSymbols; // Common symbols requiring allocation
  82   uint64_t          CommonSize = 0;
  83
  84   error_code err;
  85   // Parse symbols
  86   DEBUG(dbgs() << "Parse symbols:\n");
  87   for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
  88        i != e; i.increment(err)) {
  89     Check(err);
  90     object::SymbolRef::Type SymType;
  91     StringRef Name;
  92     Check(i->getType(SymType));
  93     Check(i->getName(Name));
  94
  95     uint32_t flags;
  96     Check(i->getFlags(flags));
  97
  98     bool isCommon = flags & SymbolRef::SF_Common;
  99     if (isCommon) {
 100       // Add the common symbols to a list.  We'll allocate them all below.
 101       uint64_t Size = 0;
 102       Check(i->getSize(Size));
 103       CommonSize += Size;
 104       CommonSymbols[*i] = Size;
 105     } else {
 106       if (SymType == object::SymbolRef::ST_Function ||
 107           SymType == object::SymbolRef::ST_Data) {
 108         uint64_t FileOffset;
 109         StringRef SectionData;
 110         section_iterator si = obj->end_sections();
 111         Check(i->getFileOffset(FileOffset));
 112         Check(i->getSection(si));
 113         if (si == obj->end_sections()) continue;
 114         Check(si->getContents(SectionData));
 115         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
 116                                 (uintptr_t)FileOffset;
 117         uintptr_t SectOffset = (uintptr_t)(SymPtr -
 118                                            (const uint8_t*)SectionData.begin());
 119         unsigned SectionID =
 120           findOrEmitSection(*obj,
 121                             *si,
 122                             SymType == object::SymbolRef::ST_Function,
 123                             LocalSections);
 124         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 125         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 126                      << " flags: " << flags
 127                      << " SID: " << SectionID
 128                      << " Offset: " << format("%p", SectOffset));
 129         bool isGlobal = flags & SymbolRef::SF_Global;
 130         if (isGlobal)
 131           SymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 132       }
 133     }
 134     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 135   }
 136
 137   // Allocate common symbols
 138   if (CommonSize != 0)
 139     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 140
 141   // Parse and process relocations
 142   DEBUG(dbgs() << "Parse relocations:\n");
 143   for (section_iterator si = obj->begin_sections(),
 144        se = obj->end_sections(); si != se; si.increment(err)) {
 145     Check(err);
 146     bool isFirstRelocation = true;
 147     unsigned SectionID = 0;
 148     StubMap Stubs;
 149
 150     for (relocation_iterator i = si->begin_relocations(),
 151          e = si->end_relocations(); i != e; i.increment(err)) {
 152       Check(err);
 153
 154       // If it's the first relocation in this section, find its SectionID
 155       if (isFirstRelocation) {
 156         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
 157         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 158         isFirstRelocation = false;
 159       }
 160
 161       ObjRelocationInfo RI;
 162       RI.SectionID = SectionID;
 163       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 164       Check(i->getOffset(RI.Offset));
 165       Check(i->getSymbol(RI.Symbol));
 166       Check(i->getType(RI.Type));
 167
 168       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 169                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 170                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 171                    << "\n");
 172       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 173     }
 174   }
 175
 176   handleObjectLoaded(obj.take());
 177
 178   return false;
 179 }
 180
 181 unsigned RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 182                                             const CommonSymbolMap &Map,
 183                                             uint64_t TotalSize,
 184                                             LocalSymbolMap &LocalSymbols) {
 185   // Allocate memory for the section
 186   unsigned SectionID = Sections.size();
 187   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 188                                               SectionID);
 189   if (!Addr)
 190     report_fatal_error("Unable to allocate memory for common symbols!");
 191   uint64_t Offset = 0;
 192   Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
 193   memset(Addr, 0, TotalSize);
 194
 195   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 196                << " new addr: " << format("%p", Addr)
 197                << " DataSize: " << TotalSize
 198                << "\n");
 199
 200   // Assign the address of each symbol
 201   for (CommonSymbolMap::const_iterator it = Map.begin(), itEnd = Map.end();
 202        it != itEnd; it++) {
 203     uint64_t Size = it->second;
 204     StringRef Name;
 205     it->first.getName(Name);
 206     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 207     LocalSymbols[Name.data()] = SymbolLoc(SectionID, Offset);
 208     Offset += Size;
 209     Addr += Size;
 210   }
 211
 212   return SectionID;
 213 }
 214
 215 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
 216                                       const SectionRef &Section,
 217                                       bool IsCode) {
 218
 219   unsigned StubBufSize = 0,
 220            StubSize = getMaxStubSize();
 221   error_code err;
 222   if (StubSize > 0) {
 223     for (relocation_iterator i = Section.begin_relocations(),
 224          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 225       StubBufSize += StubSize;
 226   }
 227   StringRef data;
 228   uint64_t Alignment64;
 229   Check(Section.getContents(data));
 230   Check(Section.getAlignment(Alignment64));
 231
 232   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 233   bool IsRequired;
 234   bool IsVirtual;
 235   bool IsZeroInit;
 236   uint64_t DataSize;
 237   Check(Section.isRequiredForExecution(IsRequired));
 238   Check(Section.isVirtual(IsVirtual));
 239   Check(Section.isZeroInit(IsZeroInit));
 240   Check(Section.getSize(DataSize));
 241
 242   unsigned Allocate;
 243   unsigned SectionID = Sections.size();
 244   uint8_t *Addr;
 245   const char *pData = 0;
 246
 247   // Some sections, such as debug info, don't need to be loaded for execution.
 248   // Leave those where they are.
 249   if (IsRequired) {
 250     Allocate = DataSize + StubBufSize;
 251     Addr = IsCode
 252       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 253       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
 254     if (!Addr)
 255       report_fatal_error("Unable to allocate section memory!");
 256
 257     // Virtual sections have no data in the object image, so leave pData = 0
 258     if (!IsVirtual)
 259       pData = data.data();
 260
 261     // Zero-initialize or copy the data from the image
 262     if (IsZeroInit || IsVirtual)
 263       memset(Addr, 0, DataSize);
 264     else
 265       memcpy(Addr, pData, DataSize);
 266
 267     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 268                  << " obj addr: " << format("%p", pData)
 269                  << " new addr: " << format("%p", Addr)
 270                  << " DataSize: " << DataSize
 271                  << " StubBufSize: " << StubBufSize
 272                  << " Allocate: " << Allocate
 273                  << "\n");
 274     Obj.updateSectionAddress(Section, (uint64_t)Addr);
 275   }
 276   else {
 277     // Even if we didn't load the section, we need to record an entry for it
 278     // to handle later processing (and by 'handle' I mean don't do anything
 279     // with these sections).
 280     Allocate = 0;
 281     Addr = 0;
 282     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 283                  << " obj addr: " << format("%p", data.data())
 284                  << " new addr: 0"
 285                  << " DataSize: " << DataSize
 286                  << " StubBufSize: " << StubBufSize
 287                  << " Allocate: " << Allocate
 288                  << "\n");
 289   }
 290
 291   Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
 292   return SectionID;
 293 }
 294
 295 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
 296                                             const SectionRef &Section,
 297                                             bool IsCode,
 298                                             ObjSectionToIDMap &LocalSections) {
 299
 300   unsigned SectionID = 0;
 301   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 302   if (i != LocalSections.end())
 303     SectionID = i->second;
 304   else {
 305     SectionID = emitSection(Obj, Section, IsCode);
 306     LocalSections[Section] = SectionID;
 307   }
 308   return SectionID;
 309 }
 310
 311 void RuntimeDyldImpl::addRelocation(const RelocationValueRef &Value,
 312                                     unsigned SectionID, uintptr_t Offset,
 313                                     uint32_t RelType) {
 314   DEBUG(dbgs() << "addRelocation SymNamePtr: " << format("%p", Value.SymbolName)
 315                << " SID: " << Value.SectionID
 316                << " Addend: " << format("%p", Value.Addend)
 317                << " Offset: " << format("%p", Offset)
 318                << " RelType: " << format("%x", RelType)
 319                << "\n");
 320
 321   if (Value.SymbolName == 0) {
 322     Relocations[Value.SectionID].push_back(RelocationEntry(
 323       SectionID,
 324       Offset,
 325       RelType,
 326       Value.Addend));
 327   } else
 328     SymbolRelocations[Value.SymbolName].push_back(RelocationEntry(
 329       SectionID,
 330       Offset,
 331       RelType,
 332       Value.Addend));
 333 }
 334
 335 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 336   // TODO: There is only ARM far stub now. We should add the Thumb stub,
 337   // and stubs for branches Thumb - ARM and ARM - Thumb.
 338   if (Arch == Triple::arm) {
 339     uint32_t *StubAddr = (uint32_t*)Addr;
 340     *StubAddr = 0xe51ff004; // ldr pc,<label>
 341     return (uint8_t*)++StubAddr;
 342   }
 343   else
 344     return Addr;
 345 }
 346
 347 // Assign an address to a symbol name and resolve all the relocations
 348 // associated with it.
 349 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 350                                              uint64_t Addr) {
 351   // The address to use for relocation resolution is not
 352   // the address of the local section buffer. We must be doing
 353   // a remote execution environment of some sort. Re-apply any
 354   // relocations referencing this section with the given address.
 355   //
 356   // Addr is a uint64_t because we can't assume the pointer width
 357   // of the target is the same as that of the host. Just use a generic
 358   // "big enough" type.
 359   Sections[SectionID].LoadAddress = Addr;
 360   DEBUG(dbgs() << "Resolving relocations Section #" << SectionID
 361           << "\t" << format("%p", (uint8_t *)Addr)
 362           << "\n");
 363   resolveRelocationList(Relocations[SectionID], Addr);
 364 }
 365
 366 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
 367                                              uint64_t Value) {
 368     // Ignore relocations for sections that were not loaded
 369     if (Sections[RE.SectionID].Address != 0) {
 370       uint8_t *Target = Sections[RE.SectionID].Address + RE.Offset;
 371       DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
 372             << " + " << RE.Offset << " (" << format("%p", Target) << ")"
 373             << " RelType: " << RE.RelType
 374             << " Addend: " << RE.Addend
 375             << "\n");
 376
 377       resolveRelocation(Target, Sections[RE.SectionID].LoadAddress + RE.Offset,
 378                         Value, RE.RelType, RE.Addend);
 379   }
 380 }
 381
 382 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 383                                             uint64_t Value) {
 384   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 385     resolveRelocationEntry(Relocs[i], Value);
 386   }
 387 }
 388
 389 // resolveSymbols - Resolve any relocations to the specified symbols if
 390 // we know where it lives.
 391 void RuntimeDyldImpl::resolveSymbols() {
 392   StringMap<RelocationList>::iterator i = SymbolRelocations.begin(),
 393                                       e = SymbolRelocations.end();
 394   for (; i != e; i++) {
 395     StringRef Name = i->first();
 396     RelocationList &Relocs = i->second;
 397     StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
 398     if (Loc == SymbolTable.end()) {
 399       // This is an external symbol, try to get it address from
 400       // MemoryManager.
 401       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 402                                                                    true);
 403       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 404               << "\t" << format("%p", Addr)
 405               << "\n");
 406       resolveRelocationList(Relocs, (uintptr_t)Addr);
 407     } else {
 408       // Change the relocation to be section relative rather than symbol
 409       // relative and move it to the resolved relocation list.
 410       DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
 411       for (int i = 0, e = Relocs.size(); i != e; ++i) {
 412         RelocationEntry Entry = Relocs[i];
 413         Entry.Addend += Loc->second.second;
 414         Relocations[Loc->second.first].push_back(Entry);
 415       }
 416       Relocs.clear();
 417     }
 418   }
 419 }
 420
 421
 422 //===----------------------------------------------------------------------===//
 423 // RuntimeDyld class implementation
 424 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 425   Dyld = 0;
 426   MM = mm;
 427 }
 428
 429 RuntimeDyld::~RuntimeDyld() {
 430   delete Dyld;
 431 }
 432
 433 bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
 434   if (!Dyld) {
 435     sys::LLVMFileType type = sys::IdentifyFileType(
 436             InputBuffer->getBufferStart(),
 437             static_cast<unsigned>(InputBuffer->getBufferSize()));
 438     switch (type) {
 439       case sys::ELF_Relocatable_FileType:
 440       case sys::ELF_Executable_FileType:
 441       case sys::ELF_SharedObject_FileType:
 442       case sys::ELF_Core_FileType:
 443         Dyld = new RuntimeDyldELF(MM);
 444         break;
 445       case sys::Mach_O_Object_FileType:
 446       case sys::Mach_O_Executable_FileType:
 447       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 448       case sys::Mach_O_Core_FileType:
 449       case sys::Mach_O_PreloadExecutable_FileType:
 450       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 451       case sys::Mach_O_DynamicLinker_FileType:
 452       case sys::Mach_O_Bundle_FileType:
 453       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 454       case sys::Mach_O_DSYMCompanion_FileType:
 455         Dyld = new RuntimeDyldMachO(MM);
 456         break;
 457       case sys::Unknown_FileType:
 458       case sys::Bitcode_FileType:
 459       case sys::Archive_FileType:
 460       case sys::COFF_FileType:
 461         report_fatal_error("Incompatible object format!");
 462     }
 463   } else {
 464     if (!Dyld->isCompatibleFormat(InputBuffer))
 465       report_fatal_error("Incompatible object format!");
 466   }
 467
 468   return Dyld->loadObject(InputBuffer);
 469 }
 470
 471 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 472   return Dyld->getSymbolAddress(Name);
 473 }
 474
 475 void RuntimeDyld::resolveRelocations() {
 476   Dyld->resolveRelocations();
 477 }
 478
 479 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 480                                          uint64_t Addr) {
 481   Dyld->reassignSectionAddress(SectionID, Addr);
 482 }
 483
 484 void RuntimeDyld::mapSectionAddress(void *LocalAddress,
 485                                     uint64_t TargetAddress) {
 486   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 487 }
 488
 489 StringRef RuntimeDyld::getErrorString() {
 490   return Dyld->getErrorString();
 491 }
 492
 493 } // end namespace llvm