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 sData;
 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(sData));
 115         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
 116                                 (uintptr_t)FileOffset;
 117         uintptr_t SectOffset = (uintptr_t)(SymPtr - (const uint8_t*)sData.begin());
 118         unsigned SectionID =
 119           findOrEmitSection(*obj,
 120                             *si,
 121                             SymType == object::SymbolRef::ST_Function,
 122                             LocalSections);
 123         bool isGlobal = flags & SymbolRef::SF_Global;
 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         if (isGlobal)
 130           SymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 131       }
 132     }
 133     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 134   }
 135
 136   // Allocate common symbols
 137   if (CommonSize != 0)
 138     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 139
 140   // Parse and proccess relocations
 141   DEBUG(dbgs() << "Parse relocations:\n");
 142   for (section_iterator si = obj->begin_sections(),
 143        se = obj->end_sections(); si != se; si.increment(err)) {
 144     Check(err);
 145     bool isFirstRelocation = true;
 146     unsigned SectionID = 0;
 147     StubMap Stubs;
 148
 149     for (relocation_iterator i = si->begin_relocations(),
 150          e = si->end_relocations(); i != e; i.increment(err)) {
 151       Check(err);
 152
 153       // If it's first relocation in this section, find its SectionID
 154       if (isFirstRelocation) {
 155         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
 156         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 157         isFirstRelocation = false;
 158       }
 159
 160       ObjRelocationInfo RI;
 161       RI.SectionID = SectionID;
 162       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 163       Check(i->getOffset(RI.Offset));
 164       Check(i->getSymbol(RI.Symbol));
 165       Check(i->getType(RI.Type));
 166
 167       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 168                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 169                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 170                    << "\n");
 171       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 172     }
 173   }
 174
 175   handleObjectLoaded(obj.take());
 176
 177   return false;
 178 }
 179
 180 unsigned RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 181                                             const CommonSymbolMap &Map,
 182                                             uint64_t TotalSize,
 183                                             LocalSymbolMap &LocalSymbols) {
 184   // Allocate memory for the section
 185   unsigned SectionID = Sections.size();
 186   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 187                                               SectionID);
 188   if (!Addr)
 189     report_fatal_error("Unable to allocate memory for common symbols!");
 190   uint64_t Offset = 0;
 191   Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
 192   memset(Addr, 0, TotalSize);
 193
 194   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 195                << " new addr: " << format("%p", Addr)
 196                << " DataSize: " << TotalSize
 197                << "\n");
 198
 199   // Assign the address of each symbol
 200   for (CommonSymbolMap::const_iterator it = Map.begin(), itEnd = Map.end();
 201        it != itEnd; it++) {
 202     uint64_t Size = it->second;
 203     StringRef Name;
 204     it->first.getName(Name);
 205     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 206     LocalSymbols[Name.data()] = SymbolLoc(SectionID, Offset);
 207     Offset += Size;
 208     Addr += Size;
 209   }
 210
 211   return SectionID;
 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::AddRelocation(const RelocationValueRef &Value,
 311                                    unsigned SectionID, uintptr_t Offset,
 312                                    uint32_t RelType) {
 313   DEBUG(dbgs() << "AddRelocation SymNamePtr: " << format("%p", Value.SymbolName)
 314                << " SID: " << Value.SectionID
 315                << " Addend: " << format("%p", Value.Addend)
 316                << " Offset: " << format("%p", Offset)
 317                << " RelType: " << format("%x", RelType)
 318                << "\n");
 319
 320   if (Value.SymbolName == 0) {
 321     Relocations[Value.SectionID].push_back(RelocationEntry(
 322       SectionID,
 323       Offset,
 324       RelType,
 325       Value.Addend));
 326   } else
 327     SymbolRelocations[Value.SymbolName].push_back(RelocationEntry(
 328       SectionID,
 329       Offset,
 330       RelType,
 331       Value.Addend));
 332 }
 333
 334 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 335   // TODO: There is only ARM far stub now. We should add the Thumb stub,
 336   // and stubs for branches Thumb - ARM and ARM - Thumb.
 337   if (Arch == Triple::arm) {
 338     uint32_t *StubAddr = (uint32_t*)Addr;
 339     *StubAddr = 0xe51ff004; // ldr pc,<label>
 340     return (uint8_t*)++StubAddr;
 341   }
 342   else
 343     return Addr;
 344 }
 345
 346 // Assign an address to a symbol name and resolve all the relocations
 347 // associated with it.
 348 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 349                                              uint64_t Addr) {
 350   // The address to use for relocation resolution is not
 351   // the address of the local section buffer. We must be doing
 352   // a remote execution environment of some sort. Re-apply any
 353   // relocations referencing this section with the given address.
 354   //
 355   // Addr is a uint64_t because we can't assume the pointer width
 356   // of the target is the same as that of the host. Just use a generic
 357   // "big enough" type.
 358   Sections[SectionID].LoadAddress = Addr;
 359   DEBUG(dbgs() << "Resolving relocations Section #" << SectionID
 360           << "\t" << format("%p", (uint8_t *)Addr)
 361           << "\n");
 362   resolveRelocationList(Relocations[SectionID], Addr);
 363 }
 364
 365 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
 366                                              uint64_t Value) {
 367     // Ignore relocations for sections that were not loaded
 368     if (Sections[RE.SectionID].Address != 0) {
 369       uint8_t *Target = Sections[RE.SectionID].Address + RE.Offset;
 370       DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
 371             << " + " << RE.Offset << " (" << format("%p", Target) << ")"
 372             << " Data: " << RE.Data
 373             << " Addend: " << RE.Addend
 374             << "\n");
 375
 376       resolveRelocation(Target, Sections[RE.SectionID].LoadAddress + RE.Offset,
 377                         Value, RE.Data, RE.Addend);
 378   }
 379 }
 380
 381 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 382                                             uint64_t Value) {
 383   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 384     resolveRelocationEntry(Relocs[i], Value);
 385   }
 386 }
 387
 388 // resolveSymbols - Resolve any relocations to the specified symbols if
 389 // we know where it lives.
 390 void RuntimeDyldImpl::resolveSymbols() {
 391   StringMap<RelocationList>::iterator i = SymbolRelocations.begin(),
 392                                       e = SymbolRelocations.end();
 393   for (; i != e; i++) {
 394     StringRef Name = i->first();
 395     RelocationList &Relocs = i->second;
 396     StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
 397     if (Loc == SymbolTable.end()) {
 398       // This is an external symbol, try to get it address from
 399       // MemoryManager.
 400       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 401                                                                    true);
 402       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 403               << "\t" << format("%p", Addr)
 404               << "\n");
 405       resolveRelocationList(Relocs, (uintptr_t)Addr);
 406     } else {
 407       // Change the relocation to be section relative rather than symbol
 408       // relative and move it to the resolved relocation list.
 409       DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
 410       for (int i = 0, e = Relocs.size(); i != e; ++i) {
 411         RelocationEntry Entry = Relocs[i];
 412         Entry.Addend += Loc->second.second;
 413         Relocations[Loc->second.first].push_back(Entry);
 414       }
 415       Relocs.clear();
 416     }
 417   }
 418 }
 419
 420
 421 //===----------------------------------------------------------------------===//
 422 // RuntimeDyld class implementation
 423 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 424   Dyld = 0;
 425   MM = mm;
 426 }
 427
 428 RuntimeDyld::~RuntimeDyld() {
 429   delete Dyld;
 430 }
 431
 432 bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
 433   if (!Dyld) {
 434     sys::LLVMFileType type = sys::IdentifyFileType(
 435             InputBuffer->getBufferStart(),
 436             static_cast<unsigned>(InputBuffer->getBufferSize()));
 437     switch (type) {
 438       case sys::ELF_Relocatable_FileType:
 439       case sys::ELF_Executable_FileType:
 440       case sys::ELF_SharedObject_FileType:
 441       case sys::ELF_Core_FileType:
 442         Dyld = new RuntimeDyldELF(MM);
 443         break;
 444       case sys::Mach_O_Object_FileType:
 445       case sys::Mach_O_Executable_FileType:
 446       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 447       case sys::Mach_O_Core_FileType:
 448       case sys::Mach_O_PreloadExecutable_FileType:
 449       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 450       case sys::Mach_O_DynamicLinker_FileType:
 451       case sys::Mach_O_Bundle_FileType:
 452       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 453       case sys::Mach_O_DSYMCompanion_FileType:
 454         Dyld = new RuntimeDyldMachO(MM);
 455         break;
 456       case sys::Unknown_FileType:
 457       case sys::Bitcode_FileType:
 458       case sys::Archive_FileType:
 459       case sys::COFF_FileType:
 460         report_fatal_error("Incompatible object format!");
 461     }
 462   } else {
 463     if (!Dyld->isCompatibleFormat(InputBuffer))
 464       report_fatal_error("Incompatible object format!");
 465   }
 466
 467   return Dyld->loadObject(InputBuffer);
 468 }
 469
 470 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 471   return Dyld->getSymbolAddress(Name);
 472 }
 473
 474 void RuntimeDyld::resolveRelocations() {
 475   Dyld->resolveRelocations();
 476 }
 477
 478 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 479                                          uint64_t Addr) {
 480   Dyld->reassignSectionAddress(SectionID, Addr);
 481 }
 482
 483 void RuntimeDyld::mapSectionAddress(void *LocalAddress,
 484                                     uint64_t TargetAddress) {
 485   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 486 }
 487
 488 StringRef RuntimeDyld::getErrorString() {
 489   return Dyld->getErrorString();
 490 }
 491
 492 } // end namespace llvm