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       uint32_t Align;
 100       Check(i->getAlignment(Align));
 101       uint64_t Size = 0;
 102       Check(i->getSize(Size));
 103       CommonSize += Size + Align;
 104       CommonSymbols[*i] = CommonSymbolInfo(Size, Align);
 105     } else {
 106       if (SymType == object::SymbolRef::ST_Function ||
 107           SymType == object::SymbolRef::ST_Data ||
 108           SymType == object::SymbolRef::ST_Unknown) {
 109         uint64_t FileOffset;
 110         StringRef SectionData;
 111         bool IsCode;
 112         section_iterator si = obj->end_sections();
 113         Check(i->getFileOffset(FileOffset));
 114         Check(i->getSection(si));
 115         if (si == obj->end_sections()) continue;
 116         Check(si->getContents(SectionData));
 117         Check(si->isText(IsCode));
 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 = findOrEmitSection(*obj, *si, IsCode, LocalSections);
 123         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 124         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 125                      << " flags: " << flags
 126                      << " SID: " << SectionID
 127                      << " Offset: " << format("%p", SectOffset));
 128         GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 129       }
 130     }
 131     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 132   }
 133
 134   // Allocate common symbols
 135   if (CommonSize != 0)
 136     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
 137
 138   // Parse and process relocations
 139   DEBUG(dbgs() << "Parse relocations:\n");
 140   for (section_iterator si = obj->begin_sections(),
 141        se = obj->end_sections(); si != se; si.increment(err)) {
 142     Check(err);
 143     bool isFirstRelocation = true;
 144     unsigned SectionID = 0;
 145     StubMap Stubs;
 146
 147     for (relocation_iterator i = si->begin_relocations(),
 148          e = si->end_relocations(); i != e; i.increment(err)) {
 149       Check(err);
 150
 151       // If it's the first relocation in this section, find its SectionID
 152       if (isFirstRelocation) {
 153         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
 154         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 155         isFirstRelocation = false;
 156       }
 157
 158       processRelocationRef(SectionID, *i, *obj, LocalSections, LocalSymbols,
 159                            Stubs);
 160     }
 161   }
 162
 163   return obj.take();
 164 }
 165
 166 void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
 167                                         const CommonSymbolMap &CommonSymbols,
 168                                         uint64_t TotalSize,
 169                                         SymbolTableMap &SymbolTable) {
 170   // Allocate memory for the section
 171   unsigned SectionID = Sections.size();
 172   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
 173                                               SectionID, false);
 174   if (!Addr)
 175     report_fatal_error("Unable to allocate memory for common symbols!");
 176   uint64_t Offset = 0;
 177   Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, TotalSize, 0));
 178   memset(Addr, 0, TotalSize);
 179
 180   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 181                << " new addr: " << format("%p", Addr)
 182                << " DataSize: " << TotalSize
 183                << "\n");
 184
 185   // Assign the address of each symbol
 186   for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
 187        itEnd = CommonSymbols.end(); it != itEnd; it++) {
 188     uint64_t Size = it->second.first;
 189     uint64_t Align = it->second.second;
 190     StringRef Name;
 191     it->first.getName(Name);
 192     if (Align) {
 193       // This symbol has an alignment requirement.
 194       uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
 195       Addr += AlignOffset;
 196       Offset += AlignOffset;
 197       DEBUG(dbgs() << "Allocating common symbol " << Name << " address " <<
 198                       format("%p\n", Addr));
 199     }
 200     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
 201     SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
 202     Offset += Size;
 203     Addr += Size;
 204   }
 205 }
 206
 207 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
 208                                       const SectionRef &Section,
 209                                       bool IsCode) {
 210
 211   unsigned StubBufSize = 0,
 212            StubSize = getMaxStubSize();
 213   error_code err;
 214   if (StubSize > 0) {
 215     for (relocation_iterator i = Section.begin_relocations(),
 216          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
 217       StubBufSize += StubSize;
 218   }
 219   StringRef data;
 220   uint64_t Alignment64;
 221   Check(Section.getContents(data));
 222   Check(Section.getAlignment(Alignment64));
 223
 224   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 225   bool IsRequired;
 226   bool IsVirtual;
 227   bool IsZeroInit;
 228   bool IsReadOnly;
 229   uint64_t DataSize;
 230   StringRef Name;
 231   Check(Section.isRequiredForExecution(IsRequired));
 232   Check(Section.isVirtual(IsVirtual));
 233   Check(Section.isZeroInit(IsZeroInit));
 234   Check(Section.isReadOnlyData(IsReadOnly));
 235   Check(Section.getSize(DataSize));
 236   Check(Section.getName(Name));
 237   if (StubSize > 0) {
 238     unsigned StubAlignment = getStubAlignment();
 239     unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
 240     if (StubAlignment > EndAlignment)
 241       StubBufSize += StubAlignment - EndAlignment;
 242   }
 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, IsReadOnly);
 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 || Arch == Triple::mips) {
 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   } else if (Arch == Triple::systemz) {
 381     writeInt16BE(Addr,    0xC418);     // lgrl %r1,.+8
 382     writeInt16BE(Addr+2,  0x0000);
 383     writeInt16BE(Addr+4,  0x0004);
 384     writeInt16BE(Addr+6,  0x07F1);     // brc 15,%r1
 385     // 8-byte address stored at Addr + 8
 386     return Addr;
 387   }
 388   return Addr;
 389 }
 390
 391 // Assign an address to a symbol name and resolve all the relocations
 392 // associated with it.
 393 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 394                                              uint64_t Addr) {
 395   // The address to use for relocation resolution is not
 396   // the address of the local section buffer. We must be doing
 397   // a remote execution environment of some sort. Relocations can't
 398   // be applied until all the sections have been moved.  The client must
 399   // trigger this with a call to MCJIT::finalize() or
 400   // RuntimeDyld::resolveRelocations().
 401   //
 402   // Addr is a uint64_t because we can't assume the pointer width
 403   // of the target is the same as that of the host. Just use a generic
 404   // "big enough" type.
 405   Sections[SectionID].LoadAddress = Addr;
 406 }
 407
 408 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 409                                             uint64_t Value) {
 410   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 411     const RelocationEntry &RE = Relocs[i];
 412     // Ignore relocations for sections that were not loaded
 413     if (Sections[RE.SectionID].Address == 0)
 414       continue;
 415     resolveRelocation(RE, Value);
 416   }
 417 }
 418
 419 void RuntimeDyldImpl::resolveExternalSymbols() {
 420   StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
 421                                       e = ExternalSymbolRelocations.end();
 422   for (; i != e; i++) {
 423     StringRef Name = i->first();
 424     RelocationList &Relocs = i->second;
 425     SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
 426     if (Loc == GlobalSymbolTable.end()) {
 427       if (Name.size() == 0) {
 428         // This is an absolute symbol, use an address of zero.
 429         DEBUG(dbgs() << "Resolving absolute relocations." << "\n");
 430         resolveRelocationList(Relocs, 0);
 431       } else {
 432         // This is an external symbol, try to get its address from
 433         // MemoryManager.
 434         uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 435                                                                    true);
 436         DEBUG(dbgs() << "Resolving relocations Name: " << Name
 437                 << "\t" << format("%p", Addr)
 438                 << "\n");
 439         resolveRelocationList(Relocs, (uintptr_t)Addr);
 440       }
 441     } else {
 442       report_fatal_error("Expected external symbol");
 443     }
 444   }
 445 }
 446
 447
 448 //===----------------------------------------------------------------------===//
 449 // RuntimeDyld class implementation
 450 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 451   // FIXME: There's a potential issue lurking here if a single instance of
 452   // RuntimeDyld is used to load multiple objects.  The current implementation
 453   // associates a single memory manager with a RuntimeDyld instance.  Even
 454   // though the public class spawns a new 'impl' instance for each load,
 455   // they share a single memory manager.  This can become a problem when page
 456   // permissions are applied.
 457   Dyld = 0;
 458   MM = mm;
 459 }
 460
 461 RuntimeDyld::~RuntimeDyld() {
 462   delete Dyld;
 463 }
 464
 465 ObjectImage *RuntimeDyld::loadObject(ObjectBuffer *InputBuffer) {
 466   if (!Dyld) {
 467     sys::LLVMFileType type = sys::IdentifyFileType(
 468             InputBuffer->getBufferStart(),
 469             static_cast<unsigned>(InputBuffer->getBufferSize()));
 470     switch (type) {
 471       case sys::ELF_Relocatable_FileType:
 472       case sys::ELF_Executable_FileType:
 473       case sys::ELF_SharedObject_FileType:
 474       case sys::ELF_Core_FileType:
 475         Dyld = new RuntimeDyldELF(MM);
 476         break;
 477       case sys::Mach_O_Object_FileType:
 478       case sys::Mach_O_Executable_FileType:
 479       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 480       case sys::Mach_O_Core_FileType:
 481       case sys::Mach_O_PreloadExecutable_FileType:
 482       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 483       case sys::Mach_O_DynamicLinker_FileType:
 484       case sys::Mach_O_Bundle_FileType:
 485       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 486       case sys::Mach_O_DSYMCompanion_FileType:
 487         Dyld = new RuntimeDyldMachO(MM);
 488         break;
 489       case sys::Unknown_FileType:
 490       case sys::Bitcode_FileType:
 491       case sys::Archive_FileType:
 492       case sys::COFF_FileType:
 493         report_fatal_error("Incompatible object format!");
 494     }
 495   } else {
 496     if (!Dyld->isCompatibleFormat(InputBuffer))
 497       report_fatal_error("Incompatible object format!");
 498   }
 499
 500   return Dyld->loadObject(InputBuffer);
 501 }
 502
 503 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 504   return Dyld->getSymbolAddress(Name);
 505 }
 506
 507 uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
 508   return Dyld->getSymbolLoadAddress(Name);
 509 }
 510
 511 void RuntimeDyld::resolveRelocations() {
 512   Dyld->resolveRelocations();
 513 }
 514
 515 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 516                                          uint64_t Addr) {
 517   Dyld->reassignSectionAddress(SectionID, Addr);
 518 }
 519
 520 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
 521                                     uint64_t TargetAddress) {
 522   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 523 }
 524
 525 StringRef RuntimeDyld::getErrorString() {
 526   return Dyld->getErrorString();
 527 }
 528
 529 } // end namespace llvm