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 "llvm/ExecutionEngine/RuntimeDyld.h"
  16 #include "ObjectImageCommon.h"
  17 #include "RuntimeDyldELF.h"
  18 #include "RuntimeDyldImpl.h"
  19 #include "RuntimeDyldMachO.h"
  20 #include "llvm/Support/MathExtras.h"
  21 #include "llvm/Support/Path.h"
  22
  23 using namespace llvm;
  24 using namespace llvm::object;
  25
  26 // Empty out-of-line virtual destructor as the key function.
  27 RTDyldMemoryManager::~RTDyldMemoryManager() {}
  28 RuntimeDyldImpl::~RuntimeDyldImpl() {}
  29
  30 namespace llvm {
  31
  32 // Resolve the relocations for all symbols we currently know about.
  33 void RuntimeDyldImpl::resolveRelocations() {
  34   // First, resolve relocations associated with external symbols.
  35   resolveExternalSymbols();
  36
  37   // Just iterate over the sections we have and resolve all the relocations
  38   // in them. Gross overkill, but it gets the job done.
  39   for (int i = 0, e = Sections.size(); i != e; ++i) {
  40     uint64_t Addr = Sections[i].LoadAddress;
  41     DEBUG(dbgs() << "Resolving relocations Section #" << i
  42             << "\t" << format("%p", (uint8_t *)Addr)
  43             << "\n");
  44     resolveRelocationList(Relocations[i], Addr);
  45   }
  46 }
  47
  48 void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
  49                                         uint64_t TargetAddress) {
  50   for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
  51     if (Sections[i].Address == LocalAddress) {
  52       reassignSectionAddress(i, TargetAddress);
  53       return;
  54     }
  55   }
  56   llvm_unreachable("Attempting to remap address of unknown section!");
  57 }
  58
  59 // Subclasses can implement this method to create specialized image instances.
  60 // The caller owns the pointer that is returned.
  61 ObjectImage *RuntimeDyldImpl::createObjectImage(ObjectBuffer *InputBuffer) {
  62   return new ObjectImageCommon(InputBuffer);
  63 }
  64
  65 ObjectImage *RuntimeDyldImpl::loadObject(ObjectBuffer *InputBuffer) {
  66   OwningPtr<ObjectImage> obj(createObjectImage(InputBuffer));
  67   if (!obj)
  68     report_fatal_error("Unable to create object image from memory buffer!");
  69
  70   Arch = (Triple::ArchType)obj->getArch();
  71
  72   // Symbols found in this object
  73   StringMap<SymbolLoc> LocalSymbols;
  74   // Used sections from the object file
  75   ObjSectionToIDMap LocalSections;
  76
  77   // Common symbols requiring allocation, with their sizes and alignments
  78   CommonSymbolMap CommonSymbols;
  79   // Maximum required total memory to allocate all common symbols
  80   uint64_t CommonSize = 0;
  81
  82   error_code err;
  83   // Parse symbols
  84   DEBUG(dbgs() << "Parse symbols:\n");
  85   for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
  86        i != e; i.increment(err)) {
  87     Check(err);
  88     object::SymbolRef::Type SymType;
  89     StringRef Name;
  90     Check(i->getType(SymType));
  91     Check(i->getName(Name));
  92
  93     uint32_t flags;
  94     Check(i->getFlags(flags));
  95
  96     bool isCommon = flags & SymbolRef::SF_Common;
  97     if (isCommon) {
  98       // Add the common symbols to a list.  We'll allocate them all below.
  99       uint64_t Align = getCommonSymbolAlignment(*i);
 100       uint64_t Size = 0;
 101       Check(i->getSize(Size));
 102       CommonSize += Size + Align;
 103       CommonSymbols[*i] = CommonSymbolInfo(Size, Align);
 104     } else {
 105       if (SymType == object::SymbolRef::ST_Function ||
 106           SymType == object::SymbolRef::ST_Data ||
 107           SymType == object::SymbolRef::ST_Unknown) {
 108         uint64_t FileOffset;
 109         StringRef SectionData;
 110         bool IsCode;
 111         section_iterator si = obj->end_sections();
 112         Check(i->getFileOffset(FileOffset));
 113         Check(i->getSection(si));
 114         if (si == obj->end_sections()) continue;
 115         Check(si->getContents(SectionData));
 116         Check(si->isText(IsCode));
 117         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
 118                                 (uintptr_t)FileOffset;
 119         uintptr_t SectOffset = (uintptr_t)(SymPtr -
 120                                            (const uint8_t*)SectionData.begin());
 121         unsigned SectionID = findOrEmitSection(*obj, *si, IsCode, LocalSections);
 122         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 123         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 124                      << " flags: " << flags
 125                      << " SID: " << SectionID
 126                      << " Offset: " << format("%p", SectOffset));
 127         GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 128       }
 129     }
 130     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 131   }
 132
 133   // Allocate common symbols
 134   if (CommonSize != 0)
 135     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 136
 137   // Parse and process relocations
 138   DEBUG(dbgs() << "Parse relocations:\n");
 139   for (section_iterator si = obj->begin_sections(),
 140        se = obj->end_sections(); si != se; si.increment(err)) {
 141     Check(err);
 142     bool isFirstRelocation = true;
 143     unsigned SectionID = 0;
 144     StubMap Stubs;
 145
 146     for (relocation_iterator i = si->begin_relocations(),
 147          e = si->end_relocations(); i != e; i.increment(err)) {
 148       Check(err);
 149
 150       // If it's the first relocation in this section, find its SectionID
 151       if (isFirstRelocation) {
 152         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
 153         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 154         isFirstRelocation = false;
 155       }
 156
 157       ObjRelocationInfo RI;
 158       RI.SectionID = SectionID;
 159       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 160       Check(i->getOffset(RI.Offset));
 161       Check(i->getSymbol(RI.Symbol));
 162       Check(i->getType(RI.Type));
 163
 164       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 165                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 166                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 167                    << "\n");
 168       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 169     }
 170   }
 171
 172   return obj.take();
 173 }
 174
 175 void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 176                                         const CommonSymbolMap &CommonSymbols,
 177                                         uint64_t TotalSize,
 178                                         SymbolTableMap &SymbolTable) {
 179   // Allocate memory for the section
 180   unsigned SectionID = Sections.size();
 181   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 182                                               SectionID, false);
 183   if (!Addr)
 184     report_fatal_error("Unable to allocate memory for common symbols!");
 185   uint64_t Offset = 0;
 186   Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, TotalSize, 0));
 187   memset(Addr, 0, TotalSize);
 188
 189   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 190                << " new addr: " << format("%p", Addr)
 191                << " DataSize: " << TotalSize
 192                << "\n");
 193
 194   // Assign the address of each symbol
 195   for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
 196        itEnd = CommonSymbols.end(); it != itEnd; it++) {
 197     uint64_t Size = it->second.first;
 198     uint64_t Align = it->second.second;
 199     StringRef Name;
 200     it->first.getName(Name);
 201     if (Align) {
 202       // This symbol has an alignment requirement.
 203       uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
 204       Addr += AlignOffset;
 205       Offset += AlignOffset;
 206       DEBUG(dbgs() << "Allocating common symbol " << Name << " address " <<
 207                       format("%p\n", Addr));
 208     }
 209     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 210     SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
 211     Offset += Size;
 212     Addr += Size;
 213   }
 214 }
 215
 216 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
 217                                       const SectionRef &Section,
 218                                       bool IsCode) {
 219
 220   unsigned StubBufSize = 0,
 221            StubSize = getMaxStubSize();
 222   error_code err;
 223   if (StubSize > 0) {
 224     for (relocation_iterator i = Section.begin_relocations(),
 225          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 226       StubBufSize += StubSize;
 227   }
 228   StringRef data;
 229   uint64_t Alignment64;
 230   Check(Section.getContents(data));
 231   Check(Section.getAlignment(Alignment64));
 232
 233   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 234   bool IsRequired;
 235   bool IsVirtual;
 236   bool IsZeroInit;
 237   bool IsReadOnly;
 238   uint64_t DataSize;
 239   StringRef Name;
 240   Check(Section.isRequiredForExecution(IsRequired));
 241   Check(Section.isVirtual(IsVirtual));
 242   Check(Section.isZeroInit(IsZeroInit));
 243   Check(Section.isReadOnlyData(IsReadOnly));
 244   Check(Section.getSize(DataSize));
 245   Check(Section.getName(Name));
 246
 247   unsigned Allocate;
 248   unsigned SectionID = Sections.size();
 249   uint8_t *Addr;
 250   const char *pData = 0;
 251
 252   // Some sections, such as debug info, don't need to be loaded for execution.
 253   // Leave those where they are.
 254   if (IsRequired) {
 255     Allocate = DataSize + StubBufSize;
 256     Addr = IsCode
 257       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 258       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID, IsReadOnly);
 259     if (!Addr)
 260       report_fatal_error("Unable to allocate section memory!");
 261
 262     // Virtual sections have no data in the object image, so leave pData = 0
 263     if (!IsVirtual)
 264       pData = data.data();
 265
 266     // Zero-initialize or copy the data from the image
 267     if (IsZeroInit || IsVirtual)
 268       memset(Addr, 0, DataSize);
 269     else
 270       memcpy(Addr, pData, DataSize);
 271
 272     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 273                  << " Name: " << Name
 274                  << " obj addr: " << format("%p", pData)
 275                  << " new addr: " << format("%p", Addr)
 276                  << " DataSize: " << DataSize
 277                  << " StubBufSize: " << StubBufSize
 278                  << " Allocate: " << Allocate
 279                  << "\n");
 280     Obj.updateSectionAddress(Section, (uint64_t)Addr);
 281   }
 282   else {
 283     // Even if we didn't load the section, we need to record an entry for it
 284     // to handle later processing (and by 'handle' I mean don't do anything
 285     // with these sections).
 286     Allocate = 0;
 287     Addr = 0;
 288     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 289                  << " Name: " << Name
 290                  << " obj addr: " << format("%p", data.data())
 291                  << " new addr: 0"
 292                  << " DataSize: " << DataSize
 293                  << " StubBufSize: " << StubBufSize
 294                  << " Allocate: " << Allocate
 295                  << "\n");
 296   }
 297
 298   Sections.push_back(SectionEntry(Name, Addr, Allocate, DataSize,
 299                                   (uintptr_t)pData));
 300   return SectionID;
 301 }
 302
 303 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
 304                                             const SectionRef &Section,
 305                                             bool IsCode,
 306                                             ObjSectionToIDMap &LocalSections) {
 307
 308   unsigned SectionID = 0;
 309   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 310   if (i != LocalSections.end())
 311     SectionID = i->second;
 312   else {
 313     SectionID = emitSection(Obj, Section, IsCode);
 314     LocalSections[Section] = SectionID;
 315   }
 316   return SectionID;
 317 }
 318
 319 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
 320                                               unsigned SectionID) {
 321   Relocations[SectionID].push_back(RE);
 322 }
 323
 324 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
 325                                              StringRef SymbolName) {
 326   // Relocation by symbol.  If the symbol is found in the global symbol table,
 327   // create an appropriate section relocation.  Otherwise, add it to
 328   // ExternalSymbolRelocations.
 329   SymbolTableMap::const_iterator Loc =
 330       GlobalSymbolTable.find(SymbolName);
 331   if (Loc == GlobalSymbolTable.end()) {
 332     ExternalSymbolRelocations[SymbolName].push_back(RE);
 333   } else {
 334     // Copy the RE since we want to modify its addend.
 335     RelocationEntry RECopy = RE;
 336     RECopy.Addend += Loc->second.second;
 337     Relocations[Loc->second.first].push_back(RECopy);
 338   }
 339 }
 340
 341 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 342   if (Arch == Triple::arm) {
 343     // TODO: There is only ARM far stub now. We should add the Thumb stub,
 344     // and stubs for branches Thumb - ARM and ARM - Thumb.
 345     uint32_t *StubAddr = (uint32_t*)Addr;
 346     *StubAddr = 0xe51ff004; // ldr pc,<label>
 347     return (uint8_t*)++StubAddr;
 348   } else if (Arch == Triple::mipsel || Arch == Triple::mips) {
 349     uint32_t *StubAddr = (uint32_t*)Addr;
 350     // 0:   3c190000        lui     t9,%hi(addr).
 351     // 4:   27390000        addiu   t9,t9,%lo(addr).
 352     // 8:   03200008        jr      t9.
 353     // c:   00000000        nop.
 354     const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
 355     const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
 356
 357     *StubAddr = LuiT9Instr;
 358     StubAddr++;
 359     *StubAddr = AdduiT9Instr;
 360     StubAddr++;
 361     *StubAddr = JrT9Instr;
 362     StubAddr++;
 363     *StubAddr = NopInstr;
 364     return Addr;
 365   } else if (Arch == Triple::ppc64) {
 366     // PowerPC64 stub: the address points to a function descriptor
 367     // instead of the function itself. Load the function address
 368     // on r11 and sets it to control register. Also loads the function
 369     // TOC in r2 and environment pointer to r11.
 370     writeInt32BE(Addr,    0x3D800000); // lis   r12, highest(addr)
 371     writeInt32BE(Addr+4,  0x618C0000); // ori   r12, higher(addr)
 372     writeInt32BE(Addr+8,  0x798C07C6); // sldi  r12, r12, 32
 373     writeInt32BE(Addr+12, 0x658C0000); // oris  r12, r12, h(addr)
 374     writeInt32BE(Addr+16, 0x618C0000); // ori   r12, r12, l(addr)
 375     writeInt32BE(Addr+20, 0xF8410028); // std   r2,  40(r1)
 376     writeInt32BE(Addr+24, 0xE96C0000); // ld    r11, 0(r12)
 377     writeInt32BE(Addr+28, 0xE84C0008); // ld    r2,  0(r12)
 378     writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
 379     writeInt32BE(Addr+36, 0xE96C0010); // ld    r11, 16(r2)
 380     writeInt32BE(Addr+40, 0x4E800420); // bctr
 381
 382     return Addr;
 383   }
 384   return Addr;
 385 }
 386
 387 // Assign an address to a symbol name and resolve all the relocations
 388 // associated with it.
 389 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 390                                              uint64_t Addr) {
 391   // The address to use for relocation resolution is not
 392   // the address of the local section buffer. We must be doing
 393   // a remote execution environment of some sort. Relocations can't
 394   // be applied until all the sections have been moved.  The client must
 395   // trigger this with a call to MCJIT::finalize() or
 396   // RuntimeDyld::resolveRelocations().
 397   //
 398   // Addr is a uint64_t because we can't assume the pointer width
 399   // of the target is the same as that of the host. Just use a generic
 400   // "big enough" type.
 401   Sections[SectionID].LoadAddress = Addr;
 402 }
 403
 404 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
 405                                              uint64_t Value) {
 406   // Ignore relocations for sections that were not loaded
 407   if (Sections[RE.SectionID].Address != 0) {
 408     DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
 409           << " + " << RE.Offset << " ("
 410           << format("%p", Sections[RE.SectionID].Address + RE.Offset) << ")"
 411           << " RelType: " << RE.RelType
 412           << " Addend: " << RE.Addend
 413           << "\n");
 414
 415     resolveRelocation(Sections[RE.SectionID], RE.Offset,
 416                       Value, RE.RelType, RE.Addend);
 417   }
 418 }
 419
 420 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 421                                             uint64_t Value) {
 422   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 423     resolveRelocationEntry(Relocs[i], Value);
 424   }
 425 }
 426
 427 void RuntimeDyldImpl::resolveExternalSymbols() {
 428   StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
 429                                       e = ExternalSymbolRelocations.end();
 430   for (; i != e; i++) {
 431     StringRef Name = i->first();
 432     RelocationList &Relocs = i->second;
 433     SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
 434     if (Loc == GlobalSymbolTable.end()) {
 435       // This is an external symbol, try to get it address from
 436       // MemoryManager.
 437       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 438                                                                    true);
 439       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 440               << "\t" << format("%p", Addr)
 441               << "\n");
 442       resolveRelocationList(Relocs, (uintptr_t)Addr);
 443     } else {
 444       report_fatal_error("Expected external symbol");
 445     }
 446   }
 447 }
 448
 449
 450 //===----------------------------------------------------------------------===//
 451 // RuntimeDyld class implementation
 452 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 453   // FIXME: There's a potential issue lurking here if a single instance of
 454   // RuntimeDyld is used to load multiple objects.  The current implementation
 455   // associates a single memory manager with a RuntimeDyld instance.  Even
 456   // though the public class spawns a new 'impl' instance for each load,
 457   // they share a single memory manager.  This can become a problem when page
 458   // permissions are applied.
 459   Dyld = 0;
 460   MM = mm;
 461 }
 462
 463 RuntimeDyld::~RuntimeDyld() {
 464   delete Dyld;
 465 }
 466
 467 ObjectImage *RuntimeDyld::loadObject(ObjectBuffer *InputBuffer) {
 468   if (!Dyld) {
 469     sys::LLVMFileType type = sys::IdentifyFileType(
 470             InputBuffer->getBufferStart(),
 471             static_cast<unsigned>(InputBuffer->getBufferSize()));
 472     switch (type) {
 473       case sys::ELF_Relocatable_FileType:
 474       case sys::ELF_Executable_FileType:
 475       case sys::ELF_SharedObject_FileType:
 476       case sys::ELF_Core_FileType:
 477         Dyld = new RuntimeDyldELF(MM);
 478         break;
 479       case sys::Mach_O_Object_FileType:
 480       case sys::Mach_O_Executable_FileType:
 481       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 482       case sys::Mach_O_Core_FileType:
 483       case sys::Mach_O_PreloadExecutable_FileType:
 484       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 485       case sys::Mach_O_DynamicLinker_FileType:
 486       case sys::Mach_O_Bundle_FileType:
 487       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 488       case sys::Mach_O_DSYMCompanion_FileType:
 489         Dyld = new RuntimeDyldMachO(MM);
 490         break;
 491       case sys::Unknown_FileType:
 492       case sys::Bitcode_FileType:
 493       case sys::Archive_FileType:
 494       case sys::COFF_FileType:
 495         report_fatal_error("Incompatible object format!");
 496     }
 497   } else {
 498     if (!Dyld->isCompatibleFormat(InputBuffer))
 499       report_fatal_error("Incompatible object format!");
 500   }
 501
 502   return Dyld->loadObject(InputBuffer);
 503 }
 504
 505 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 506   return Dyld->getSymbolAddress(Name);
 507 }
 508
 509 uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
 510   return Dyld->getSymbolLoadAddress(Name);
 511 }
 512
 513 void RuntimeDyld::resolveRelocations() {
 514   Dyld->resolveRelocations();
 515 }
 516
 517 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 518                                          uint64_t Addr) {
 519   Dyld->reassignSectionAddress(SectionID, Addr);
 520 }
 521
 522 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
 523                                     uint64_t TargetAddress) {
 524   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 525 }
 526
 527 StringRef RuntimeDyld::getErrorString() {
 528   return Dyld->getErrorString();
 529 }
 530
 531 } // end namespace llvm