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(const 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 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           SymType == object::SymbolRef::ST_Unknown) {
 113         uint64_t FileOffset;
 114         StringRef SectionData;
 115         section_iterator si = obj->end_sections();
 116         Check(i->getFileOffset(FileOffset));
 117         Check(i->getSection(si));
 118         if (si == obj->end_sections()) continue;
 119         Check(si->getContents(SectionData));
 120         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
 121                                 (uintptr_t)FileOffset;
 122         uintptr_t SectOffset = (uintptr_t)(SymPtr -
 123                                            (const uint8_t*)SectionData.begin());
 124         unsigned SectionID =
 125           findOrEmitSection(*obj,
 126                             *si,
 127                             SymType == object::SymbolRef::ST_Function,
 128                             LocalSections);
 129         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 130         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 131                      << " flags: " << flags
 132                      << " SID: " << SectionID
 133                      << " Offset: " << format("%p", SectOffset));
 134         bool isGlobal = flags & SymbolRef::SF_Global;
 135         if (isGlobal)
 136           GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 137       }
 138     }
 139     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 140   }
 141
 142   // Allocate common symbols
 143   if (CommonSize != 0)
 144     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 145
 146   // Parse and process relocations
 147   DEBUG(dbgs() << "Parse relocations:\n");
 148   for (section_iterator si = obj->begin_sections(),
 149        se = obj->end_sections(); si != se; si.increment(err)) {
 150     Check(err);
 151     bool isFirstRelocation = true;
 152     unsigned SectionID = 0;
 153     StubMap Stubs;
 154
 155     for (relocation_iterator i = si->begin_relocations(),
 156          e = si->end_relocations(); i != e; i.increment(err)) {
 157       Check(err);
 158
 159       // If it's the first relocation in this section, find its SectionID
 160       if (isFirstRelocation) {
 161         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
 162         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 163         isFirstRelocation = false;
 164       }
 165
 166       ObjRelocationInfo RI;
 167       RI.SectionID = SectionID;
 168       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 169       Check(i->getOffset(RI.Offset));
 170       Check(i->getSymbol(RI.Symbol));
 171       Check(i->getType(RI.Type));
 172
 173       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 174                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 175                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 176                    << "\n");
 177       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 178     }
 179   }
 180
 181   handleObjectLoaded(obj.take());
 182
 183   return false;
 184 }
 185
 186 void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 187                                         const CommonSymbolMap &CommonSymbols,
 188                                         uint64_t TotalSize,
 189                                         SymbolTableMap &SymbolTable) {
 190   // Allocate memory for the section
 191   unsigned SectionID = Sections.size();
 192   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 193                                               SectionID);
 194   if (!Addr)
 195     report_fatal_error("Unable to allocate memory for common symbols!");
 196   uint64_t Offset = 0;
 197   Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
 198   memset(Addr, 0, TotalSize);
 199
 200   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 201                << " new addr: " << format("%p", Addr)
 202                << " DataSize: " << TotalSize
 203                << "\n");
 204
 205   // Assign the address of each symbol
 206   for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
 207        itEnd = CommonSymbols.end(); it != itEnd; it++) {
 208     StringRef Name;
 209     it->first.getName(Name);
 210     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 211     SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
 212     uint64_t Size = it->second;
 213     Offset += Size;
 214     Addr += Size;
 215   }
 216 }
 217
 218 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
 219                                       const SectionRef &Section,
 220                                       bool IsCode) {
 221
 222   unsigned StubBufSize = 0,
 223            StubSize = getMaxStubSize();
 224   error_code err;
 225   if (StubSize > 0) {
 226     for (relocation_iterator i = Section.begin_relocations(),
 227          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 228       StubBufSize += StubSize;
 229   }
 230   StringRef data;
 231   uint64_t Alignment64;
 232   Check(Section.getContents(data));
 233   Check(Section.getAlignment(Alignment64));
 234
 235   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 236   bool IsRequired;
 237   bool IsVirtual;
 238   bool IsZeroInit;
 239   uint64_t DataSize;
 240   Check(Section.isRequiredForExecution(IsRequired));
 241   Check(Section.isVirtual(IsVirtual));
 242   Check(Section.isZeroInit(IsZeroInit));
 243   Check(Section.getSize(DataSize));
 244
 245   unsigned Allocate;
 246   unsigned SectionID = Sections.size();
 247   uint8_t *Addr;
 248   const char *pData = 0;
 249
 250   // Some sections, such as debug info, don't need to be loaded for execution.
 251   // Leave those where they are.
 252   if (IsRequired) {
 253     Allocate = DataSize + StubBufSize;
 254     Addr = IsCode
 255       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 256       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
 257     if (!Addr)
 258       report_fatal_error("Unable to allocate section memory!");
 259
 260     // Virtual sections have no data in the object image, so leave pData = 0
 261     if (!IsVirtual)
 262       pData = data.data();
 263
 264     // Zero-initialize or copy the data from the image
 265     if (IsZeroInit || IsVirtual)
 266       memset(Addr, 0, DataSize);
 267     else
 268       memcpy(Addr, pData, DataSize);
 269
 270     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 271                  << " obj addr: " << format("%p", pData)
 272                  << " new addr: " << format("%p", Addr)
 273                  << " DataSize: " << DataSize
 274                  << " StubBufSize: " << StubBufSize
 275                  << " Allocate: " << Allocate
 276                  << "\n");
 277     Obj.updateSectionAddress(Section, (uint64_t)Addr);
 278   }
 279   else {
 280     // Even if we didn't load the section, we need to record an entry for it
 281     // to handle later processing (and by 'handle' I mean don't do anything
 282     // with these sections).
 283     Allocate = 0;
 284     Addr = 0;
 285     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 286                  << " obj addr: " << format("%p", data.data())
 287                  << " new addr: 0"
 288                  << " DataSize: " << DataSize
 289                  << " StubBufSize: " << StubBufSize
 290                  << " Allocate: " << Allocate
 291                  << "\n");
 292   }
 293
 294   Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
 295   return SectionID;
 296 }
 297
 298 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
 299                                             const SectionRef &Section,
 300                                             bool IsCode,
 301                                             ObjSectionToIDMap &LocalSections) {
 302
 303   unsigned SectionID = 0;
 304   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 305   if (i != LocalSections.end())
 306     SectionID = i->second;
 307   else {
 308     SectionID = emitSection(Obj, Section, IsCode);
 309     LocalSections[Section] = SectionID;
 310   }
 311   return SectionID;
 312 }
 313
 314 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
 315                                               unsigned SectionID) {
 316   Relocations[SectionID].push_back(RE);
 317 }
 318
 319 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
 320                                              StringRef SymbolName) {
 321   // Relocation by symbol.  If the symbol is found in the global symbol table,
 322   // create an appropriate section relocation.  Otherwise, add it to
 323   // ExternalSymbolRelocations.
 324   SymbolTableMap::const_iterator Loc =
 325       GlobalSymbolTable.find(SymbolName);
 326   if (Loc == GlobalSymbolTable.end()) {
 327     ExternalSymbolRelocations[SymbolName].push_back(RE);
 328   } else {
 329     // Copy the RE since we want to modify its addend.
 330     RelocationEntry RECopy = RE;
 331     RECopy.Addend += Loc->second.second;
 332     Relocations[Loc->second.first].push_back(RECopy);
 333   }
 334 }
 335
 336 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 337   if (Arch == Triple::arm) {
 338     // TODO: There is only ARM far stub now. We should add the Thumb stub,
 339     // and stubs for branches Thumb - ARM and ARM - Thumb.
 340     uint32_t *StubAddr = (uint32_t*)Addr;
 341     *StubAddr = 0xe51ff004; // ldr pc,<label>
 342     return (uint8_t*)++StubAddr;
 343   } else if (Arch == Triple::mipsel) {
 344     uint32_t *StubAddr = (uint32_t*)Addr;
 345     // 0:   3c190000        lui     t9,%hi(addr).
 346     // 4:   27390000        addiu   t9,t9,%lo(addr).
 347     // 8:   03200008        jr      t9.
 348     // c:   00000000        nop.
 349     const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
 350     const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
 351
 352     *StubAddr = LuiT9Instr;
 353     StubAddr++;
 354     *StubAddr = AdduiT9Instr;
 355     StubAddr++;
 356     *StubAddr = JrT9Instr;
 357     StubAddr++;
 358     *StubAddr = NopInstr;
 359     return Addr;
 360   }
 361   return Addr;
 362 }
 363
 364 // Assign an address to a symbol name and resolve all the relocations
 365 // associated with it.
 366 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 367                                              uint64_t Addr) {
 368   // The address to use for relocation resolution is not
 369   // the address of the local section buffer. We must be doing
 370   // a remote execution environment of some sort. Re-apply any
 371   // relocations referencing this section with the given address.
 372   //
 373   // Addr is a uint64_t because we can't assume the pointer width
 374   // of the target is the same as that of the host. Just use a generic
 375   // "big enough" type.
 376   Sections[SectionID].LoadAddress = Addr;
 377   DEBUG(dbgs() << "Resolving relocations Section #" << SectionID
 378           << "\t" << format("%p", (uint8_t *)Addr)
 379           << "\n");
 380   resolveRelocationList(Relocations[SectionID], Addr);
 381 }
 382
 383 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
 384                                              uint64_t Value) {
 385     // Ignore relocations for sections that were not loaded
 386     if (Sections[RE.SectionID].Address != 0) {
 387       uint8_t *Target = Sections[RE.SectionID].Address + RE.Offset;
 388       DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
 389             << " + " << RE.Offset << " (" << format("%p", Target) << ")"
 390             << " RelType: " << RE.RelType
 391             << " Addend: " << RE.Addend
 392             << "\n");
 393
 394       resolveRelocation(Target, Sections[RE.SectionID].LoadAddress + RE.Offset,
 395                         Value, RE.RelType, RE.Addend);
 396   }
 397 }
 398
 399 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 400                                             uint64_t Value) {
 401   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 402     resolveRelocationEntry(Relocs[i], Value);
 403   }
 404 }
 405
 406 void RuntimeDyldImpl::resolveExternalSymbols() {
 407   StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
 408                                       e = ExternalSymbolRelocations.end();
 409   for (; i != e; i++) {
 410     StringRef Name = i->first();
 411     RelocationList &Relocs = i->second;
 412     SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
 413     if (Loc == GlobalSymbolTable.end()) {
 414       // This is an external symbol, try to get it address from
 415       // MemoryManager.
 416       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 417                                                                    true);
 418       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 419               << "\t" << format("%p", Addr)
 420               << "\n");
 421       resolveRelocationList(Relocs, (uintptr_t)Addr);
 422     } else {
 423       report_fatal_error("Expected external symbol");
 424     }
 425   }
 426 }
 427
 428
 429 //===----------------------------------------------------------------------===//
 430 // RuntimeDyld class implementation
 431 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 432   Dyld = 0;
 433   MM = mm;
 434 }
 435
 436 RuntimeDyld::~RuntimeDyld() {
 437   delete Dyld;
 438 }
 439
 440 bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
 441   if (!Dyld) {
 442     sys::LLVMFileType type = sys::IdentifyFileType(
 443             InputBuffer->getBufferStart(),
 444             static_cast<unsigned>(InputBuffer->getBufferSize()));
 445     switch (type) {
 446       case sys::ELF_Relocatable_FileType:
 447       case sys::ELF_Executable_FileType:
 448       case sys::ELF_SharedObject_FileType:
 449       case sys::ELF_Core_FileType:
 450         Dyld = new RuntimeDyldELF(MM);
 451         break;
 452       case sys::Mach_O_Object_FileType:
 453       case sys::Mach_O_Executable_FileType:
 454       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 455       case sys::Mach_O_Core_FileType:
 456       case sys::Mach_O_PreloadExecutable_FileType:
 457       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 458       case sys::Mach_O_DynamicLinker_FileType:
 459       case sys::Mach_O_Bundle_FileType:
 460       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 461       case sys::Mach_O_DSYMCompanion_FileType:
 462         Dyld = new RuntimeDyldMachO(MM);
 463         break;
 464       case sys::Unknown_FileType:
 465       case sys::Bitcode_FileType:
 466       case sys::Archive_FileType:
 467       case sys::COFF_FileType:
 468         report_fatal_error("Incompatible object format!");
 469     }
 470   } else {
 471     if (!Dyld->isCompatibleFormat(InputBuffer))
 472       report_fatal_error("Incompatible object format!");
 473   }
 474
 475   return Dyld->loadObject(InputBuffer);
 476 }
 477
 478 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 479   return Dyld->getSymbolAddress(Name);
 480 }
 481
 482 uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
 483   return Dyld->getSymbolLoadAddress(Name);
 484 }
 485
 486 void RuntimeDyld::resolveRelocations() {
 487   Dyld->resolveRelocations();
 488 }
 489
 490 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 491                                          uint64_t Addr) {
 492   Dyld->reassignSectionAddress(SectionID, Addr);
 493 }
 494
 495 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
 496                                     uint64_t TargetAddress) {
 497   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 498 }
 499
 500 StringRef RuntimeDyld::getErrorString() {
 501   return Dyld->getErrorString();
 502 }
 503
 504 } // end namespace llvm