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