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   resolveExternalSymbols();
  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   // Symbols found in this object
  79   StringMap<SymbolLoc> LocalSymbols;
  80   // Used sections from the object file
  81   ObjSectionToIDMap LocalSections;
  82
  83   // Common symbols requiring allocation, and the total size required to
  84   // allocate all common symbols.
  85   CommonSymbolMap CommonSymbols;
  86   uint64_t CommonSize = 0;
  87
  88   error_code err;
  89   // Parse symbols
  90   DEBUG(dbgs() << "Parse symbols:\n");
  91   for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
  92        i != e; i.increment(err)) {
  93     Check(err);
  94     object::SymbolRef::Type SymType;
  95     StringRef Name;
  96     Check(i->getType(SymType));
  97     Check(i->getName(Name));
  98
  99     uint32_t flags;
 100     Check(i->getFlags(flags));
 101
 102     bool isCommon = flags & SymbolRef::SF_Common;
 103     if (isCommon) {
 104       // Add the common symbols to a list.  We'll allocate them all below.
 105       uint64_t Size = 0;
 106       Check(i->getSize(Size));
 107       CommonSize += Size;
 108       CommonSymbols[*i] = Size;
 109     } else {
 110       if (SymType == object::SymbolRef::ST_Function ||
 111           SymType == object::SymbolRef::ST_Data) {
 112         uint64_t FileOffset;
 113         StringRef SectionData;
 114         section_iterator si = obj->end_sections();
 115         Check(i->getFileOffset(FileOffset));
 116         Check(i->getSection(si));
 117         if (si == obj->end_sections()) continue;
 118         Check(si->getContents(SectionData));
 119         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
 120                                 (uintptr_t)FileOffset;
 121         uintptr_t SectOffset = (uintptr_t)(SymPtr -
 122                                            (const uint8_t*)SectionData.begin());
 123         unsigned SectionID =
 124           findOrEmitSection(*obj,
 125                             *si,
 126                             SymType == object::SymbolRef::ST_Function,
 127                             LocalSections);
 128         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 129         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 130                      << " flags: " << flags
 131                      << " SID: " << SectionID
 132                      << " Offset: " << format("%p", SectOffset));
 133         bool isGlobal = flags & SymbolRef::SF_Global;
 134         if (isGlobal)
 135           GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 136       }
 137     }
 138     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 139   }
 140
 141   // Allocate common symbols
 142   if (CommonSize != 0)
 143     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 144
 145   // Parse and process relocations
 146   DEBUG(dbgs() << "Parse relocations:\n");
 147   for (section_iterator si = obj->begin_sections(),
 148        se = obj->end_sections(); si != se; si.increment(err)) {
 149     Check(err);
 150     bool isFirstRelocation = true;
 151     unsigned SectionID = 0;
 152     StubMap Stubs;
 153
 154     for (relocation_iterator i = si->begin_relocations(),
 155          e = si->end_relocations(); i != e; i.increment(err)) {
 156       Check(err);
 157
 158       // If it's the first relocation in this section, find its SectionID
 159       if (isFirstRelocation) {
 160         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
 161         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 162         isFirstRelocation = false;
 163       }
 164
 165       ObjRelocationInfo RI;
 166       RI.SectionID = SectionID;
 167       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 168       Check(i->getOffset(RI.Offset));
 169       Check(i->getSymbol(RI.Symbol));
 170       Check(i->getType(RI.Type));
 171
 172       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 173                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 174                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 175                    << "\n");
 176       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 177     }
 178   }
 179
 180   handleObjectLoaded(obj.take());
 181
 182   return false;
 183 }
 184
 185 void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 186                                         const CommonSymbolMap &CommonSymbols,
 187                                         uint64_t TotalSize,
 188                                         SymbolTableMap &SymbolTable) {
 189   // Allocate memory for the section
 190   unsigned SectionID = Sections.size();
 191   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 192                                               SectionID);
 193   if (!Addr)
 194     report_fatal_error("Unable to allocate memory for common symbols!");
 195   uint64_t Offset = 0;
 196   Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
 197   memset(Addr, 0, TotalSize);
 198
 199   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 200                << " new addr: " << format("%p", Addr)
 201                << " DataSize: " << TotalSize
 202                << "\n");
 203
 204   // Assign the address of each symbol
 205   for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
 206        itEnd = CommonSymbols.end(); it != itEnd; it++) {
 207     StringRef Name;
 208     it->first.getName(Name);
 209     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 210     SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
 211     uint64_t Size = it->second;
 212     Offset += Size;
 213     Addr += Size;
 214   }
 215 }
 216
 217 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
 218                                       const SectionRef &Section,
 219                                       bool IsCode) {
 220
 221   unsigned StubBufSize = 0,
 222            StubSize = getMaxStubSize();
 223   error_code err;
 224   if (StubSize > 0) {
 225     for (relocation_iterator i = Section.begin_relocations(),
 226          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 227       StubBufSize += StubSize;
 228   }
 229   StringRef data;
 230   uint64_t Alignment64;
 231   Check(Section.getContents(data));
 232   Check(Section.getAlignment(Alignment64));
 233
 234   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 235   bool IsRequired;
 236   bool IsVirtual;
 237   bool IsZeroInit;
 238   uint64_t DataSize;
 239   Check(Section.isRequiredForExecution(IsRequired));
 240   Check(Section.isVirtual(IsVirtual));
 241   Check(Section.isZeroInit(IsZeroInit));
 242   Check(Section.getSize(DataSize));
 243
 244   unsigned Allocate;
 245   unsigned SectionID = Sections.size();
 246   uint8_t *Addr;
 247   const char *pData = 0;
 248
 249   // Some sections, such as debug info, don't need to be loaded for execution.
 250   // Leave those where they are.
 251   if (IsRequired) {
 252     Allocate = DataSize + StubBufSize;
 253     Addr = IsCode
 254       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 255       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
 256     if (!Addr)
 257       report_fatal_error("Unable to allocate section memory!");
 258
 259     // Virtual sections have no data in the object image, so leave pData = 0
 260     if (!IsVirtual)
 261       pData = data.data();
 262
 263     // Zero-initialize or copy the data from the image
 264     if (IsZeroInit || IsVirtual)
 265       memset(Addr, 0, DataSize);
 266     else
 267       memcpy(Addr, pData, DataSize);
 268
 269     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 270                  << " obj addr: " << format("%p", pData)
 271                  << " new addr: " << format("%p", Addr)
 272                  << " DataSize: " << DataSize
 273                  << " StubBufSize: " << StubBufSize
 274                  << " Allocate: " << Allocate
 275                  << "\n");
 276     Obj.updateSectionAddress(Section, (uint64_t)Addr);
 277   }
 278   else {
 279     // Even if we didn't load the section, we need to record an entry for it
 280     // to handle later processing (and by 'handle' I mean don't do anything
 281     // with these sections).
 282     Allocate = 0;
 283     Addr = 0;
 284     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 285                  << " obj addr: " << format("%p", data.data())
 286                  << " new addr: 0"
 287                  << " DataSize: " << DataSize
 288                  << " StubBufSize: " << StubBufSize
 289                  << " Allocate: " << Allocate
 290                  << "\n");
 291   }
 292
 293   Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
 294   return SectionID;
 295 }
 296
 297 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
 298                                             const SectionRef &Section,
 299                                             bool IsCode,
 300                                             ObjSectionToIDMap &LocalSections) {
 301
 302   unsigned SectionID = 0;
 303   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 304   if (i != LocalSections.end())
 305     SectionID = i->second;
 306   else {
 307     SectionID = emitSection(Obj, Section, IsCode);
 308     LocalSections[Section] = SectionID;
 309   }
 310   return SectionID;
 311 }
 312
 313 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
 314                                               unsigned SectionID) {
 315   Relocations[SectionID].push_back(RE);
 316 }
 317
 318 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
 319                                              StringRef SymbolName) {
 320   // Relocation by symbol.  If the symbol is found in the global symbol table,
 321   // create an appropriate section relocation.  Otherwise, add it to
 322   // ExternalSymbolRelocations.
 323   SymbolTableMap::const_iterator Loc =
 324       GlobalSymbolTable.find(SymbolName);
 325   if (Loc == GlobalSymbolTable.end()) {
 326     ExternalSymbolRelocations[SymbolName].push_back(RE);
 327   } else {
 328     // Copy the RE since we want to modify its addend.
 329     RelocationEntry RECopy = RE;
 330     RECopy.Addend += Loc->second.second;
 331     Relocations[Loc->second.first].push_back(RECopy);
 332   }
 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 void RuntimeDyldImpl::resolveExternalSymbols() {
 390   StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
 391                                       e = ExternalSymbolRelocations.end();
 392   for (; i != e; i++) {
 393     StringRef Name = i->first();
 394     RelocationList &Relocs = i->second;
 395     SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
 396     if (Loc == GlobalSymbolTable.end()) {
 397       // This is an external symbol, try to get it address from
 398       // MemoryManager.
 399       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 400                                                                    true);
 401       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 402               << "\t" << format("%p", Addr)
 403               << "\n");
 404       resolveRelocationList(Relocs, (uintptr_t)Addr);
 405     } else {
 406       report_fatal_error("Expected external symbol");
 407     }
 408   }
 409 }
 410
 411
 412 //===----------------------------------------------------------------------===//
 413 // RuntimeDyld class implementation
 414 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 415   Dyld = 0;
 416   MM = mm;
 417 }
 418
 419 RuntimeDyld::~RuntimeDyld() {
 420   delete Dyld;
 421 }
 422
 423 bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
 424   if (!Dyld) {
 425     sys::LLVMFileType type = sys::IdentifyFileType(
 426             InputBuffer->getBufferStart(),
 427             static_cast<unsigned>(InputBuffer->getBufferSize()));
 428     switch (type) {
 429       case sys::ELF_Relocatable_FileType:
 430       case sys::ELF_Executable_FileType:
 431       case sys::ELF_SharedObject_FileType:
 432       case sys::ELF_Core_FileType:
 433         Dyld = new RuntimeDyldELF(MM);
 434         break;
 435       case sys::Mach_O_Object_FileType:
 436       case sys::Mach_O_Executable_FileType:
 437       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 438       case sys::Mach_O_Core_FileType:
 439       case sys::Mach_O_PreloadExecutable_FileType:
 440       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 441       case sys::Mach_O_DynamicLinker_FileType:
 442       case sys::Mach_O_Bundle_FileType:
 443       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 444       case sys::Mach_O_DSYMCompanion_FileType:
 445         Dyld = new RuntimeDyldMachO(MM);
 446         break;
 447       case sys::Unknown_FileType:
 448       case sys::Bitcode_FileType:
 449       case sys::Archive_FileType:
 450       case sys::COFF_FileType:
 451         report_fatal_error("Incompatible object format!");
 452     }
 453   } else {
 454     if (!Dyld->isCompatibleFormat(InputBuffer))
 455       report_fatal_error("Incompatible object format!");
 456   }
 457
 458   return Dyld->loadObject(InputBuffer);
 459 }
 460
 461 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 462   return Dyld->getSymbolAddress(Name);
 463 }
 464
 465 void RuntimeDyld::resolveRelocations() {
 466   Dyld->resolveRelocations();
 467 }
 468
 469 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 470                                          uint64_t Addr) {
 471   Dyld->reassignSectionAddress(SectionID, Addr);
 472 }
 473
 474 void RuntimeDyld::mapSectionAddress(void *LocalAddress,
 475                                     uint64_t TargetAddress) {
 476   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 477 }
 478
 479 StringRef RuntimeDyld::getErrorString() {
 480   return Dyld->getErrorString();
 481 }
 482
 483 } // end namespace llvm