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 "ObjectImageCommon.h"
  16 #include "RuntimeDyldImpl.h"
  17 #include "RuntimeDyldELF.h"
  18 #include "RuntimeDyldMachO.h"
  19 #include "llvm/Support/Path.h"
  20
  21 using namespace llvm;
  22 using namespace llvm::object;
  23
  24 // Empty out-of-line virtual destructor as the key function.
  25 RTDyldMemoryManager::~RTDyldMemoryManager() {}
  26 RuntimeDyldImpl::~RuntimeDyldImpl() {}
  27
  28 namespace llvm {
  29
  30 namespace {
  31   // Helper for extensive error checking in debug builds.
  32   error_code Check(error_code Err) {
  33     if (Err) {
  34       report_fatal_error(Err.message());
  35     }
  36     return Err;
  37   }
  38 } // end anonymous namespace
  39
  40 // Resolve the relocations for all symbols we currently know about.
  41 void RuntimeDyldImpl::resolveRelocations() {
  42   // First, resolve relocations associated with external symbols.
  43   resolveExternalSymbols();
  44
  45   // Just iterate over the sections we have and resolve all the relocations
  46   // in them. Gross overkill, but it gets the job done.
  47   for (int i = 0, e = Sections.size(); i != e; ++i) {
  48     reassignSectionAddress(i, Sections[i].LoadAddress);
  49   }
  50 }
  51
  52 void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
  53                                         uint64_t TargetAddress) {
  54   for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
  55     if (Sections[i].Address == LocalAddress) {
  56       reassignSectionAddress(i, TargetAddress);
  57       return;
  58     }
  59   }
  60   llvm_unreachable("Attempting to remap address of unknown section!");
  61 }
  62
  63 // Subclasses can implement this method to create specialized image instances.
  64 // The caller owns the pointer that is returned.
  65 ObjectImage *RuntimeDyldImpl::createObjectImage(ObjectBuffer *InputBuffer) {
  66   return new ObjectImageCommon(InputBuffer);
  67 }
  68
  69 ObjectImage *RuntimeDyldImpl::loadObject(ObjectBuffer *InputBuffer) {
  70   OwningPtr<ObjectImage> obj(createObjectImage(InputBuffer));
  71   if (!obj)
  72     report_fatal_error("Unable to create object image from memory buffer!");
  73
  74   Arch = (Triple::ArchType)obj->getArch();
  75
  76   // Symbols found in this object
  77   StringMap<SymbolLoc> LocalSymbols;
  78   // Used sections from the object file
  79   ObjSectionToIDMap LocalSections;
  80
  81   // Common symbols requiring allocation, and the total size required to
  82   // allocate all common symbols.
  83   CommonSymbolMap CommonSymbols;
  84   uint64_t CommonSize = 0;
  85
  86   error_code err;
  87   // Parse symbols
  88   DEBUG(dbgs() << "Parse symbols:\n");
  89   for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
  90        i != e; i.increment(err)) {
  91     Check(err);
  92     object::SymbolRef::Type SymType;
  93     StringRef Name;
  94     Check(i->getType(SymType));
  95     Check(i->getName(Name));
  96
  97     uint32_t flags;
  98     Check(i->getFlags(flags));
  99
 100     bool isCommon = flags & SymbolRef::SF_Common;
 101     if (isCommon) {
 102       // Add the common symbols to a list.  We'll allocate them all below.
 103       uint64_t Size = 0;
 104       Check(i->getSize(Size));
 105       CommonSize += Size;
 106       CommonSymbols[*i] = Size;
 107     } else {
 108       if (SymType == object::SymbolRef::ST_Function ||
 109           SymType == object::SymbolRef::ST_Data ||
 110           SymType == object::SymbolRef::ST_Unknown) {
 111         uint64_t FileOffset;
 112         StringRef SectionData;
 113         section_iterator si = obj->end_sections();
 114         Check(i->getFileOffset(FileOffset));
 115         Check(i->getSection(si));
 116         if (si == obj->end_sections()) continue;
 117         Check(si->getContents(SectionData));
 118         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
 119                                 (uintptr_t)FileOffset;
 120         uintptr_t SectOffset = (uintptr_t)(SymPtr -
 121                                            (const uint8_t*)SectionData.begin());
 122         unsigned SectionID =
 123           findOrEmitSection(*obj,
 124                             *si,
 125                             SymType == object::SymbolRef::ST_Function,
 126                             LocalSections);
 127         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 128         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 129                      << " flags: " << flags
 130                      << " SID: " << SectionID
 131                      << " Offset: " << format("%p", SectOffset));
 132         bool isGlobal = flags & SymbolRef::SF_Global;
 133         if (isGlobal)
 134           GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 135       }
 136     }
 137     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 138   }
 139
 140   // Allocate common symbols
 141   if (CommonSize != 0)
 142     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 143
 144   // Parse and process relocations
 145   DEBUG(dbgs() << "Parse relocations:\n");
 146   for (section_iterator si = obj->begin_sections(),
 147        se = obj->end_sections(); si != se; si.increment(err)) {
 148     Check(err);
 149     bool isFirstRelocation = true;
 150     unsigned SectionID = 0;
 151     StubMap Stubs;
 152
 153     for (relocation_iterator i = si->begin_relocations(),
 154          e = si->end_relocations(); i != e; i.increment(err)) {
 155       Check(err);
 156
 157       // If it's the first relocation in this section, find its SectionID
 158       if (isFirstRelocation) {
 159         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
 160         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 161         isFirstRelocation = false;
 162       }
 163
 164       ObjRelocationInfo RI;
 165       RI.SectionID = SectionID;
 166       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 167       Check(i->getOffset(RI.Offset));
 168       Check(i->getSymbol(RI.Symbol));
 169       Check(i->getType(RI.Type));
 170
 171       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 172                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 173                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 174                    << "\n");
 175       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 176     }
 177   }
 178
 179   return obj.take();
 180 }
 181
 182 void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 183                                         const CommonSymbolMap &CommonSymbols,
 184                                         uint64_t TotalSize,
 185                                         SymbolTableMap &SymbolTable) {
 186   // Allocate memory for the section
 187   unsigned SectionID = Sections.size();
 188   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 189                                               SectionID);
 190   if (!Addr)
 191     report_fatal_error("Unable to allocate memory for common symbols!");
 192   uint64_t Offset = 0;
 193   Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
 194   memset(Addr, 0, TotalSize);
 195
 196   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 197                << " new addr: " << format("%p", Addr)
 198                << " DataSize: " << TotalSize
 199                << "\n");
 200
 201   // Assign the address of each symbol
 202   for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
 203        itEnd = CommonSymbols.end(); it != itEnd; it++) {
 204     StringRef Name;
 205     it->first.getName(Name);
 206     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 207     SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
 208     uint64_t Size = it->second;
 209     Offset += Size;
 210     Addr += Size;
 211   }
 212 }
 213
 214 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
 215                                       const SectionRef &Section,
 216                                       bool IsCode) {
 217
 218   unsigned StubBufSize = 0,
 219            StubSize = getMaxStubSize();
 220   error_code err;
 221   if (StubSize > 0) {
 222     for (relocation_iterator i = Section.begin_relocations(),
 223          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 224       StubBufSize += StubSize;
 225   }
 226   StringRef data;
 227   uint64_t Alignment64;
 228   Check(Section.getContents(data));
 229   Check(Section.getAlignment(Alignment64));
 230
 231   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 232   bool IsRequired;
 233   bool IsVirtual;
 234   bool IsZeroInit;
 235   uint64_t DataSize;
 236   Check(Section.isRequiredForExecution(IsRequired));
 237   Check(Section.isVirtual(IsVirtual));
 238   Check(Section.isZeroInit(IsZeroInit));
 239   Check(Section.getSize(DataSize));
 240
 241   unsigned Allocate;
 242   unsigned SectionID = Sections.size();
 243   uint8_t *Addr;
 244   const char *pData = 0;
 245
 246   // Some sections, such as debug info, don't need to be loaded for execution.
 247   // Leave those where they are.
 248   if (IsRequired) {
 249     Allocate = DataSize + StubBufSize;
 250     Addr = IsCode
 251       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 252       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
 253     if (!Addr)
 254       report_fatal_error("Unable to allocate section memory!");
 255
 256     // Virtual sections have no data in the object image, so leave pData = 0
 257     if (!IsVirtual)
 258       pData = data.data();
 259
 260     // Zero-initialize or copy the data from the image
 261     if (IsZeroInit || IsVirtual)
 262       memset(Addr, 0, DataSize);
 263     else
 264       memcpy(Addr, pData, DataSize);
 265
 266     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 267                  << " obj addr: " << format("%p", pData)
 268                  << " new addr: " << format("%p", Addr)
 269                  << " DataSize: " << DataSize
 270                  << " StubBufSize: " << StubBufSize
 271                  << " Allocate: " << Allocate
 272                  << "\n");
 273     Obj.updateSectionAddress(Section, (uint64_t)Addr);
 274   }
 275   else {
 276     // Even if we didn't load the section, we need to record an entry for it
 277     // to handle later processing (and by 'handle' I mean don't do anything
 278     // with these sections).
 279     Allocate = 0;
 280     Addr = 0;
 281     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 282                  << " obj addr: " << format("%p", data.data())
 283                  << " new addr: 0"
 284                  << " DataSize: " << DataSize
 285                  << " StubBufSize: " << StubBufSize
 286                  << " Allocate: " << Allocate
 287                  << "\n");
 288   }
 289
 290   Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
 291   return SectionID;
 292 }
 293
 294 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
 295                                             const SectionRef &Section,
 296                                             bool IsCode,
 297                                             ObjSectionToIDMap &LocalSections) {
 298
 299   unsigned SectionID = 0;
 300   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 301   if (i != LocalSections.end())
 302     SectionID = i->second;
 303   else {
 304     SectionID = emitSection(Obj, Section, IsCode);
 305     LocalSections[Section] = SectionID;
 306   }
 307   return SectionID;
 308 }
 309
 310 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
 311                                               unsigned SectionID) {
 312   Relocations[SectionID].push_back(RE);
 313 }
 314
 315 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
 316                                              StringRef SymbolName) {
 317   // Relocation by symbol.  If the symbol is found in the global symbol table,
 318   // create an appropriate section relocation.  Otherwise, add it to
 319   // ExternalSymbolRelocations.
 320   SymbolTableMap::const_iterator Loc =
 321       GlobalSymbolTable.find(SymbolName);
 322   if (Loc == GlobalSymbolTable.end()) {
 323     ExternalSymbolRelocations[SymbolName].push_back(RE);
 324   } else {
 325     // Copy the RE since we want to modify its addend.
 326     RelocationEntry RECopy = RE;
 327     RECopy.Addend += Loc->second.second;
 328     Relocations[Loc->second.first].push_back(RECopy);
 329   }
 330 }
 331
 332 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 333   if (Arch == Triple::arm) {
 334     // TODO: There is only ARM far stub now. We should add the Thumb stub,
 335     // and stubs for branches Thumb - ARM and ARM - Thumb.
 336     uint32_t *StubAddr = (uint32_t*)Addr;
 337     *StubAddr = 0xe51ff004; // ldr pc,<label>
 338     return (uint8_t*)++StubAddr;
 339   } else if (Arch == Triple::mipsel) {
 340     uint32_t *StubAddr = (uint32_t*)Addr;
 341     // 0:   3c190000        lui     t9,%hi(addr).
 342     // 4:   27390000        addiu   t9,t9,%lo(addr).
 343     // 8:   03200008        jr      t9.
 344     // c:   00000000        nop.
 345     const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
 346     const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
 347
 348     *StubAddr = LuiT9Instr;
 349     StubAddr++;
 350     *StubAddr = AdduiT9Instr;
 351     StubAddr++;
 352     *StubAddr = JrT9Instr;
 353     StubAddr++;
 354     *StubAddr = NopInstr;
 355     return Addr;
 356   }
 357   return Addr;
 358 }
 359
 360 // Assign an address to a symbol name and resolve all the relocations
 361 // associated with it.
 362 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 363                                              uint64_t Addr) {
 364   // The address to use for relocation resolution is not
 365   // the address of the local section buffer. We must be doing
 366   // a remote execution environment of some sort. Re-apply any
 367   // relocations referencing this section with the given address.
 368   //
 369   // Addr is a uint64_t because we can't assume the pointer width
 370   // of the target is the same as that of the host. Just use a generic
 371   // "big enough" type.
 372   Sections[SectionID].LoadAddress = Addr;
 373   DEBUG(dbgs() << "Resolving relocations Section #" << SectionID
 374           << "\t" << format("%p", (uint8_t *)Addr)
 375           << "\n");
 376   resolveRelocationList(Relocations[SectionID], Addr);
 377 }
 378
 379 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
 380                                              uint64_t Value) {
 381   // Ignore relocations for sections that were not loaded
 382   if (Sections[RE.SectionID].Address != 0) {
 383     uint8_t *Target = Sections[RE.SectionID].Address + RE.Offset;
 384     DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
 385           << " + " << RE.Offset << " (" << format("%p", Target) << ")"
 386           << " RelType: " << RE.RelType
 387           << " Addend: " << RE.Addend
 388           << "\n");
 389
 390     resolveRelocation(Target, Sections[RE.SectionID].LoadAddress + RE.Offset,
 391                       Value, RE.RelType, RE.Addend);
 392   }
 393 }
 394
 395 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 396                                             uint64_t Value) {
 397   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 398     resolveRelocationEntry(Relocs[i], Value);
 399   }
 400 }
 401
 402 void RuntimeDyldImpl::resolveExternalSymbols() {
 403   StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
 404                                       e = ExternalSymbolRelocations.end();
 405   for (; i != e; i++) {
 406     StringRef Name = i->first();
 407     RelocationList &Relocs = i->second;
 408     SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
 409     if (Loc == GlobalSymbolTable.end()) {
 410       // This is an external symbol, try to get it address from
 411       // MemoryManager.
 412       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 413                                                                    true);
 414       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 415               << "\t" << format("%p", Addr)
 416               << "\n");
 417       resolveRelocationList(Relocs, (uintptr_t)Addr);
 418     } else {
 419       report_fatal_error("Expected external symbol");
 420     }
 421   }
 422 }
 423
 424
 425 //===----------------------------------------------------------------------===//
 426 // RuntimeDyld class implementation
 427 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 428   Dyld = 0;
 429   MM = mm;
 430 }
 431
 432 RuntimeDyld::~RuntimeDyld() {
 433   delete Dyld;
 434 }
 435
 436 ObjectImage *RuntimeDyld::loadObject(ObjectBuffer *InputBuffer) {
 437   if (!Dyld) {
 438     sys::LLVMFileType type = sys::IdentifyFileType(
 439             InputBuffer->getBufferStart(),
 440             static_cast<unsigned>(InputBuffer->getBufferSize()));
 441     switch (type) {
 442       case sys::ELF_Relocatable_FileType:
 443       case sys::ELF_Executable_FileType:
 444       case sys::ELF_SharedObject_FileType:
 445       case sys::ELF_Core_FileType:
 446         Dyld = new RuntimeDyldELF(MM);
 447         break;
 448       case sys::Mach_O_Object_FileType:
 449       case sys::Mach_O_Executable_FileType:
 450       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 451       case sys::Mach_O_Core_FileType:
 452       case sys::Mach_O_PreloadExecutable_FileType:
 453       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 454       case sys::Mach_O_DynamicLinker_FileType:
 455       case sys::Mach_O_Bundle_FileType:
 456       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 457       case sys::Mach_O_DSYMCompanion_FileType:
 458         Dyld = new RuntimeDyldMachO(MM);
 459         break;
 460       case sys::Unknown_FileType:
 461       case sys::Bitcode_FileType:
 462       case sys::Archive_FileType:
 463       case sys::COFF_FileType:
 464         report_fatal_error("Incompatible object format!");
 465     }
 466   } else {
 467     if (!Dyld->isCompatibleFormat(InputBuffer))
 468       report_fatal_error("Incompatible object format!");
 469   }
 470
 471   return Dyld->loadObject(InputBuffer);
 472 }
 473
 474 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 475   return Dyld->getSymbolAddress(Name);
 476 }
 477
 478 uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
 479   return Dyld->getSymbolLoadAddress(Name);
 480 }
 481
 482 void RuntimeDyld::resolveRelocations() {
 483   Dyld->resolveRelocations();
 484 }
 485
 486 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 487                                          uint64_t Addr) {
 488   Dyld->reassignSectionAddress(SectionID, Addr);
 489 }
 490
 491 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
 492                                     uint64_t TargetAddress) {
 493   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 494 }
 495
 496 StringRef RuntimeDyld::getErrorString() {
 497   return Dyld->getErrorString();
 498 }
 499
 500 } // end namespace llvm