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       processRelocationRef(SectionID, i, *obj, LocalSections, LocalSymbols,
 158                            Stubs);
 159     }
 160   }
 161
 162   return obj.take();
 163 }
 164
 165 void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 166                                         const CommonSymbolMap &CommonSymbols,
 167                                         uint64_t TotalSize,
 168                                         SymbolTableMap &SymbolTable) {
 169   // Allocate memory for the section
 170   unsigned SectionID = Sections.size();
 171   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 172                                               SectionID, false);
 173   if (!Addr)
 174     report_fatal_error("Unable to allocate memory for common symbols!");
 175   uint64_t Offset = 0;
 176   Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, TotalSize, 0));
 177   memset(Addr, 0, TotalSize);
 178
 179   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 180                << " new addr: " << format("%p", Addr)
 181                << " DataSize: " << TotalSize
 182                << "\n");
 183
 184   // Assign the address of each symbol
 185   for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
 186        itEnd = CommonSymbols.end(); it != itEnd; it++) {
 187     uint64_t Size = it->second.first;
 188     uint64_t Align = it->second.second;
 189     StringRef Name;
 190     it->first.getName(Name);
 191     if (Align) {
 192       // This symbol has an alignment requirement.
 193       uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
 194       Addr += AlignOffset;
 195       Offset += AlignOffset;
 196       DEBUG(dbgs() << "Allocating common symbol " << Name << " address " <<
 197                       format("%p\n", Addr));
 198     }
 199     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 200     SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
 201     Offset += Size;
 202     Addr += Size;
 203   }
 204 }
 205
 206 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
 207                                       const SectionRef &Section,
 208                                       bool IsCode) {
 209
 210   unsigned StubBufSize = 0,
 211            StubSize = getMaxStubSize();
 212   error_code err;
 213   if (StubSize > 0) {
 214     for (relocation_iterator i = Section.begin_relocations(),
 215          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 216       StubBufSize += StubSize;
 217   }
 218   StringRef data;
 219   uint64_t Alignment64;
 220   Check(Section.getContents(data));
 221   Check(Section.getAlignment(Alignment64));
 222
 223   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 224   bool IsRequired;
 225   bool IsVirtual;
 226   bool IsZeroInit;
 227   bool IsReadOnly;
 228   uint64_t DataSize;
 229   StringRef Name;
 230   Check(Section.isRequiredForExecution(IsRequired));
 231   Check(Section.isVirtual(IsVirtual));
 232   Check(Section.isZeroInit(IsZeroInit));
 233   Check(Section.isReadOnlyData(IsReadOnly));
 234   Check(Section.getSize(DataSize));
 235   Check(Section.getName(Name));
 236
 237   unsigned Allocate;
 238   unsigned SectionID = Sections.size();
 239   uint8_t *Addr;
 240   const char *pData = 0;
 241
 242   // Some sections, such as debug info, don't need to be loaded for execution.
 243   // Leave those where they are.
 244   if (IsRequired) {
 245     Allocate = DataSize + StubBufSize;
 246     Addr = IsCode
 247       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 248       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID, IsReadOnly);
 249     if (!Addr)
 250       report_fatal_error("Unable to allocate section memory!");
 251
 252     // Virtual sections have no data in the object image, so leave pData = 0
 253     if (!IsVirtual)
 254       pData = data.data();
 255
 256     // Zero-initialize or copy the data from the image
 257     if (IsZeroInit || IsVirtual)
 258       memset(Addr, 0, DataSize);
 259     else
 260       memcpy(Addr, pData, DataSize);
 261
 262     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 263                  << " Name: " << Name
 264                  << " obj addr: " << format("%p", pData)
 265                  << " new addr: " << format("%p", Addr)
 266                  << " DataSize: " << DataSize
 267                  << " StubBufSize: " << StubBufSize
 268                  << " Allocate: " << Allocate
 269                  << "\n");
 270     Obj.updateSectionAddress(Section, (uint64_t)Addr);
 271   }
 272   else {
 273     // Even if we didn't load the section, we need to record an entry for it
 274     // to handle later processing (and by 'handle' I mean don't do anything
 275     // with these sections).
 276     Allocate = 0;
 277     Addr = 0;
 278     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 279                  << " Name: " << Name
 280                  << " obj addr: " << format("%p", data.data())
 281                  << " new addr: 0"
 282                  << " DataSize: " << DataSize
 283                  << " StubBufSize: " << StubBufSize
 284                  << " Allocate: " << Allocate
 285                  << "\n");
 286   }
 287
 288   Sections.push_back(SectionEntry(Name, Addr, Allocate, DataSize,
 289                                   (uintptr_t)pData));
 290   return SectionID;
 291 }
 292
 293 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
 294                                             const SectionRef &Section,
 295                                             bool IsCode,
 296                                             ObjSectionToIDMap &LocalSections) {
 297
 298   unsigned SectionID = 0;
 299   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 300   if (i != LocalSections.end())
 301     SectionID = i->second;
 302   else {
 303     SectionID = emitSection(Obj, Section, IsCode);
 304     LocalSections[Section] = SectionID;
 305   }
 306   return SectionID;
 307 }
 308
 309 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
 310                                               unsigned SectionID) {
 311   Relocations[SectionID].push_back(RE);
 312 }
 313
 314 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
 315                                              StringRef SymbolName) {
 316   // Relocation by symbol.  If the symbol is found in the global symbol table,
 317   // create an appropriate section relocation.  Otherwise, add it to
 318   // ExternalSymbolRelocations.
 319   SymbolTableMap::const_iterator Loc =
 320       GlobalSymbolTable.find(SymbolName);
 321   if (Loc == GlobalSymbolTable.end()) {
 322     ExternalSymbolRelocations[SymbolName].push_back(RE);
 323   } else {
 324     // Copy the RE since we want to modify its addend.
 325     RelocationEntry RECopy = RE;
 326     RECopy.Addend += Loc->second.second;
 327     Relocations[Loc->second.first].push_back(RECopy);
 328   }
 329 }
 330
 331 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 332   if (Arch == Triple::arm) {
 333     // TODO: There is only ARM far stub now. We should add the Thumb stub,
 334     // and stubs for branches Thumb - ARM and ARM - Thumb.
 335     uint32_t *StubAddr = (uint32_t*)Addr;
 336     *StubAddr = 0xe51ff004; // ldr pc,<label>
 337     return (uint8_t*)++StubAddr;
 338   } else if (Arch == Triple::mipsel || Arch == Triple::mips) {
 339     uint32_t *StubAddr = (uint32_t*)Addr;
 340     // 0:   3c190000        lui     t9,%hi(addr).
 341     // 4:   27390000        addiu   t9,t9,%lo(addr).
 342     // 8:   03200008        jr      t9.
 343     // c:   00000000        nop.
 344     const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
 345     const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
 346
 347     *StubAddr = LuiT9Instr;
 348     StubAddr++;
 349     *StubAddr = AdduiT9Instr;
 350     StubAddr++;
 351     *StubAddr = JrT9Instr;
 352     StubAddr++;
 353     *StubAddr = NopInstr;
 354     return Addr;
 355   } else if (Arch == Triple::ppc64) {
 356     // PowerPC64 stub: the address points to a function descriptor
 357     // instead of the function itself. Load the function address
 358     // on r11 and sets it to control register. Also loads the function
 359     // TOC in r2 and environment pointer to r11.
 360     writeInt32BE(Addr,    0x3D800000); // lis   r12, highest(addr)
 361     writeInt32BE(Addr+4,  0x618C0000); // ori   r12, higher(addr)
 362     writeInt32BE(Addr+8,  0x798C07C6); // sldi  r12, r12, 32
 363     writeInt32BE(Addr+12, 0x658C0000); // oris  r12, r12, h(addr)
 364     writeInt32BE(Addr+16, 0x618C0000); // ori   r12, r12, l(addr)
 365     writeInt32BE(Addr+20, 0xF8410028); // std   r2,  40(r1)
 366     writeInt32BE(Addr+24, 0xE96C0000); // ld    r11, 0(r12)
 367     writeInt32BE(Addr+28, 0xE84C0008); // ld    r2,  0(r12)
 368     writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
 369     writeInt32BE(Addr+36, 0xE96C0010); // ld    r11, 16(r2)
 370     writeInt32BE(Addr+40, 0x4E800420); // bctr
 371
 372     return Addr;
 373   }
 374   return Addr;
 375 }
 376
 377 // Assign an address to a symbol name and resolve all the relocations
 378 // associated with it.
 379 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 380                                              uint64_t Addr) {
 381   // The address to use for relocation resolution is not
 382   // the address of the local section buffer. We must be doing
 383   // a remote execution environment of some sort. Relocations can't
 384   // be applied until all the sections have been moved.  The client must
 385   // trigger this with a call to MCJIT::finalize() or
 386   // RuntimeDyld::resolveRelocations().
 387   //
 388   // Addr is a uint64_t because we can't assume the pointer width
 389   // of the target is the same as that of the host. Just use a generic
 390   // "big enough" type.
 391   Sections[SectionID].LoadAddress = Addr;
 392 }
 393
 394 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 395                                             uint64_t Value) {
 396   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 397     const RelocationEntry &RE = Relocs[i];
 398     // Ignore relocations for sections that were not loaded
 399     if (Sections[RE.SectionID].Address == 0)
 400       continue;
 401     resolveRelocation(RE, Value);
 402   }
 403 }
 404
 405 void RuntimeDyldImpl::resolveExternalSymbols() {
 406   StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
 407                                       e = ExternalSymbolRelocations.end();
 408   for (; i != e; i++) {
 409     StringRef Name = i->first();
 410     RelocationList &Relocs = i->second;
 411     SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
 412     if (Loc == GlobalSymbolTable.end()) {
 413       if (Name.size() == 0) {
 414         // This is an absolute symbol, use an address of zero.
 415         DEBUG(dbgs() << "Resolving absolute relocations." << "\n");
 416         resolveRelocationList(Relocs, 0);
 417       } else {
 418         // This is an external symbol, try to get its address from
 419         // MemoryManager.
 420         uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 421                                                                    true);
 422         DEBUG(dbgs() << "Resolving relocations Name: " << Name
 423                 << "\t" << format("%p", Addr)
 424                 << "\n");
 425         resolveRelocationList(Relocs, (uintptr_t)Addr);
 426       }
 427     } else {
 428       report_fatal_error("Expected external symbol");
 429     }
 430   }
 431 }
 432
 433
 434 //===----------------------------------------------------------------------===//
 435 // RuntimeDyld class implementation
 436 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 437   // FIXME: There's a potential issue lurking here if a single instance of
 438   // RuntimeDyld is used to load multiple objects.  The current implementation
 439   // associates a single memory manager with a RuntimeDyld instance.  Even
 440   // though the public class spawns a new 'impl' instance for each load,
 441   // they share a single memory manager.  This can become a problem when page
 442   // permissions are applied.
 443   Dyld = 0;
 444   MM = mm;
 445 }
 446
 447 RuntimeDyld::~RuntimeDyld() {
 448   delete Dyld;
 449 }
 450
 451 ObjectImage *RuntimeDyld::loadObject(ObjectBuffer *InputBuffer) {
 452   if (!Dyld) {
 453     sys::LLVMFileType type = sys::IdentifyFileType(
 454             InputBuffer->getBufferStart(),
 455             static_cast<unsigned>(InputBuffer->getBufferSize()));
 456     switch (type) {
 457       case sys::ELF_Relocatable_FileType:
 458       case sys::ELF_Executable_FileType:
 459       case sys::ELF_SharedObject_FileType:
 460       case sys::ELF_Core_FileType:
 461         Dyld = new RuntimeDyldELF(MM);
 462         break;
 463       case sys::Mach_O_Object_FileType:
 464       case sys::Mach_O_Executable_FileType:
 465       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 466       case sys::Mach_O_Core_FileType:
 467       case sys::Mach_O_PreloadExecutable_FileType:
 468       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 469       case sys::Mach_O_DynamicLinker_FileType:
 470       case sys::Mach_O_Bundle_FileType:
 471       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 472       case sys::Mach_O_DSYMCompanion_FileType:
 473         Dyld = new RuntimeDyldMachO(MM);
 474         break;
 475       case sys::Unknown_FileType:
 476       case sys::Bitcode_FileType:
 477       case sys::Archive_FileType:
 478       case sys::COFF_FileType:
 479         report_fatal_error("Incompatible object format!");
 480     }
 481   } else {
 482     if (!Dyld->isCompatibleFormat(InputBuffer))
 483       report_fatal_error("Incompatible object format!");
 484   }
 485
 486   return Dyld->loadObject(InputBuffer);
 487 }
 488
 489 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 490   return Dyld->getSymbolAddress(Name);
 491 }
 492
 493 uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
 494   return Dyld->getSymbolLoadAddress(Name);
 495 }
 496
 497 void RuntimeDyld::resolveRelocations() {
 498   Dyld->resolveRelocations();
 499 }
 500
 501 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 502                                          uint64_t Addr) {
 503   Dyld->reassignSectionAddress(SectionID, Addr);
 504 }
 505
 506 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
 507                                     uint64_t TargetAddress) {
 508   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 509 }
 510
 511 StringRef RuntimeDyld::getErrorString() {
 512   return Dyld->getErrorString();
 513 }
 514
 515 } // end namespace llvm