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
  40 // Resolve the relocations for all symbols we currently know about.
  41 void RuntimeDyldImpl::resolveRelocations() {
  42   // First, resolve relocations assotiated with external symbols.
  43   resolveSymbols();
  44
  45   // Just iterate over the sections we have and resolve all the relocations
  46   // in them. Gross overkill, but it gets the job done.
  47   for (int i = 0, e = Sections.size(); i != e; ++i) {
  48     reassignSectionAddress(i, Sections[i].LoadAddress);
  49   }
  50 }
  51
  52 void RuntimeDyldImpl::mapSectionAddress(void *LocalAddress,
  53                                         uint64_t TargetAddress) {
  54   for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
  55     if (Sections[i].Address == LocalAddress) {
  56       reassignSectionAddress(i, TargetAddress);
  57       return;
  58     }
  59   }
  60   llvm_unreachable("Attempting to remap address of unknown section!");
  61 }
  62
  63 bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
  64   // FIXME: ObjectFile don't modify MemoryBuffer.
  65   //        It should use const MemoryBuffer as parameter.
  66   ObjectFile *obj
  67     = ObjectFile::createObjectFile(const_cast<MemoryBuffer*>(InputBuffer));
  68
  69   Arch = (Triple::ArchType)obj->getArch();
  70
  71   LocalSymbolMap LocalSymbols;     // Functions and data symbols from the
  72                                    // object file.
  73   ObjSectionToIDMap LocalSections; // Used sections from the object file
  74
  75   error_code err;
  76   // Parse symbols
  77   DEBUG(dbgs() << "Parse symbols:\n");
  78   for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
  79        i != e; i.increment(err)) {
  80     Check(err);
  81     object::SymbolRef::Type SymType;
  82     StringRef Name;
  83     Check(i->getType(SymType));
  84     Check(i->getName(Name));
  85
  86     if (SymType == object::SymbolRef::ST_Function ||
  87         SymType == object::SymbolRef::ST_Data) {
  88       uint64_t FileOffset;
  89       uint32_t flags;
  90       StringRef sData;
  91       section_iterator si = obj->end_sections();
  92       Check(i->getFileOffset(FileOffset));
  93       Check(i->getFlags(flags));
  94       Check(i->getSection(si));
  95       if (si == obj->end_sections()) continue;
  96       Check(si->getContents(sData));
  97       const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
  98                               (uintptr_t)FileOffset;
  99       uintptr_t SectOffset = (uintptr_t)(SymPtr - (const uint8_t*)sData.begin());
 100       unsigned SectionID
 101         = findOrEmitSection(*si,
 102                           SymType == object::SymbolRef::ST_Function,
 103                           LocalSections);
 104       bool isGlobal = flags & SymbolRef::SF_Global;
 105       LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
 106       DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
 107                    << " flags: " << flags
 108                    << " SID: " << SectionID
 109                    << " Offset: " << format("%p", SectOffset));
 110       if (isGlobal)
 111         SymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
 112     }
 113     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
 114   }
 115
 116   // Parse and proccess relocations
 117   DEBUG(dbgs() << "Parse relocations:\n");
 118   for (section_iterator si = obj->begin_sections(),
 119        se = obj->end_sections(); si != se; si.increment(err)) {
 120     Check(err);
 121     bool isFirstRelocation = true;
 122     unsigned SectionID = 0;
 123     StubMap Stubs;
 124
 125     for (relocation_iterator i = si->begin_relocations(),
 126          e = si->end_relocations(); i != e; i.increment(err)) {
 127       Check(err);
 128
 129       // If it's first relocation in this section, find its SectionID
 130       if (isFirstRelocation) {
 131         SectionID = findOrEmitSection(*si, true, LocalSections);
 132         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 133         isFirstRelocation = false;
 134       }
 135
 136       ObjRelocationInfo RI;
 137       RI.SectionID = SectionID;
 138       Check(i->getAdditionalInfo(RI.AdditionalInfo));
 139       Check(i->getOffset(RI.Offset));
 140       Check(i->getSymbol(RI.Symbol));
 141       Check(i->getType(RI.Type));
 142
 143       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
 144                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
 145                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
 146                    << "\n");
 147       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
 148     }
 149   }
 150   return false;
 151 }
 152
 153 unsigned RuntimeDyldImpl::emitSection(const SectionRef &Section,
 154                                       bool IsCode) {
 155
 156   unsigned StubBufSize = 0,
 157            StubSize = getMaxStubSize();
 158   error_code err;
 159   if (StubSize > 0) {
 160     for (relocation_iterator i = Section.begin_relocations(),
 161          e = Section.end_relocations(); i != e; i.increment(err))
 162       StubBufSize += StubSize;
 163   }
 164   StringRef data;
 165   uint64_t Alignment64;
 166   Check(Section.getContents(data));
 167   Check(Section.getAlignment(Alignment64));
 168
 169   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 170   unsigned DataSize = data.size();
 171   unsigned Allocate = DataSize + StubBufSize;
 172   unsigned SectionID = Sections.size();
 173   const char *pData = data.data();
 174   uint8_t *Addr = IsCode
 175     ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
 176     : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
 177
 178   memcpy(Addr, pData, DataSize);
 179   DEBUG(dbgs() << "emitSection SectionID: " << SectionID
 180                << " obj addr: " << format("%p", pData)
 181                << " new addr: " << format("%p", Addr)
 182                << " DataSize: " << DataSize
 183                << " StubBufSize: " << StubBufSize
 184                << " Allocate: " << Allocate
 185                << "\n");
 186   Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
 187   return SectionID;
 188 }
 189
 190 unsigned RuntimeDyldImpl::findOrEmitSection(const SectionRef &Section,
 191                                             bool IsCode,
 192                                             ObjSectionToIDMap &LocalSections) {
 193
 194   unsigned SectionID = 0;
 195   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 196   if (i != LocalSections.end())
 197     SectionID = i->second;
 198   else {
 199     SectionID = emitSection(Section, IsCode);
 200     LocalSections[Section] = SectionID;
 201   }
 202   return SectionID;
 203 }
 204
 205 void RuntimeDyldImpl::AddRelocation(const RelocationValueRef &Value,
 206                                    unsigned SectionID, uintptr_t Offset,
 207                                    uint32_t RelType) {
 208   DEBUG(dbgs() << "AddRelocation SymNamePtr: " << format("%p", Value.SymbolName)
 209                << " SID: " << Value.SectionID
 210                << " Addend: " << format("%p", Value.Addend)
 211                << " Offset: " << format("%p", Offset)
 212                << " RelType: " << format("%x", RelType)
 213                << "\n");
 214
 215   if (Value.SymbolName == 0) {
 216     Relocations[Value.SectionID].push_back(RelocationEntry(
 217       SectionID,
 218       Offset,
 219       RelType,
 220       Value.Addend));
 221   } else
 222     SymbolRelocations[Value.SymbolName].push_back(RelocationEntry(
 223       SectionID,
 224       Offset,
 225       RelType,
 226       Value.Addend));
 227 }
 228
 229 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
 230   // TODO: There is only ARM far stub now. We should add the Thumb stub,
 231   // and stubs for branches Thumb - ARM and ARM - Thumb.
 232   if (Arch == Triple::arm) {
 233     uint32_t *StubAddr = (uint32_t*)Addr;
 234     *StubAddr = 0xe51ff004; // ldr pc,<label>
 235     return (uint8_t*)++StubAddr;
 236   }
 237   else
 238     return Addr;
 239 }
 240
 241 // Assign an address to a symbol name and resolve all the relocations
 242 // associated with it.
 243 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
 244                                              uint64_t Addr) {
 245   // The address to use for relocation resolution is not
 246   // the address of the local section buffer. We must be doing
 247   // a remote execution environment of some sort. Re-apply any
 248   // relocations referencing this section with the given address.
 249   //
 250   // Addr is a uint64_t because we can't assume the pointer width
 251   // of the target is the same as that of the host. Just use a generic
 252   // "big enough" type.
 253   Sections[SectionID].LoadAddress = Addr;
 254   DEBUG(dbgs() << "Resolving relocations Section #" << SectionID
 255           << "\t" << format("%p", (uint8_t *)Addr)
 256           << "\n");
 257   resolveRelocationList(Relocations[SectionID], Addr);
 258 }
 259
 260 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
 261                                              uint64_t Value) {
 262     uint8_t *Target = Sections[RE.SectionID].Address + RE.Offset;
 263     DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
 264           << " + " << RE.Offset << " (" << format("%p", Target) << ")"
 265           << " Data: " << RE.Data
 266           << " Addend: " << RE.Addend
 267           << "\n");
 268
 269     resolveRelocation(Target, Sections[RE.SectionID].LoadAddress + RE.Offset,
 270                       Value, RE.Data, RE.Addend);
 271 }
 272
 273 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
 274                                             uint64_t Value) {
 275   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
 276     resolveRelocationEntry(Relocs[i], Value);
 277   }
 278 }
 279
 280 // resolveSymbols - Resolve any relocations to the specified symbols if
 281 // we know where it lives.
 282 void RuntimeDyldImpl::resolveSymbols() {
 283   StringMap<RelocationList>::iterator i = SymbolRelocations.begin(),
 284                                       e = SymbolRelocations.end();
 285   for (; i != e; i++) {
 286     StringRef Name = i->first();
 287     RelocationList &Relocs = i->second;
 288     StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
 289     if (Loc == SymbolTable.end()) {
 290       // This is an external symbol, try to get it address from
 291       // MemoryManager.
 292       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
 293                                                                    true);
 294       DEBUG(dbgs() << "Resolving relocations Name: " << Name
 295               << "\t" << format("%p", Addr)
 296               << "\n");
 297       resolveRelocationList(Relocs, (uintptr_t)Addr);
 298     } else {
 299       // Change the relocation to be section relative rather than symbol
 300       // relative and move it to the resolved relocation list.
 301       DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
 302       for (int i = 0, e = Relocs.size(); i != e; ++i) {
 303         RelocationEntry Entry = Relocs[i];
 304         Entry.Addend += Loc->second.second;
 305         Relocations[Loc->second.first].push_back(Entry);
 306       }
 307       Relocs.clear();
 308     }
 309   }
 310 }
 311
 312
 313 //===----------------------------------------------------------------------===//
 314 // RuntimeDyld class implementation
 315 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
 316   Dyld = 0;
 317   MM = mm;
 318 }
 319
 320 RuntimeDyld::~RuntimeDyld() {
 321   delete Dyld;
 322 }
 323
 324 bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
 325   if (!Dyld) {
 326     sys::LLVMFileType type = sys::IdentifyFileType(
 327             InputBuffer->getBufferStart(),
 328             static_cast<unsigned>(InputBuffer->getBufferSize()));
 329     switch (type) {
 330       case sys::ELF_Relocatable_FileType:
 331       case sys::ELF_Executable_FileType:
 332       case sys::ELF_SharedObject_FileType:
 333       case sys::ELF_Core_FileType:
 334         Dyld = new RuntimeDyldELF(MM);
 335         break;
 336       case sys::Mach_O_Object_FileType:
 337       case sys::Mach_O_Executable_FileType:
 338       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
 339       case sys::Mach_O_Core_FileType:
 340       case sys::Mach_O_PreloadExecutable_FileType:
 341       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
 342       case sys::Mach_O_DynamicLinker_FileType:
 343       case sys::Mach_O_Bundle_FileType:
 344       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
 345       case sys::Mach_O_DSYMCompanion_FileType:
 346         Dyld = new RuntimeDyldMachO(MM);
 347         break;
 348       case sys::Unknown_FileType:
 349       case sys::Bitcode_FileType:
 350       case sys::Archive_FileType:
 351       case sys::COFF_FileType:
 352         report_fatal_error("Incompatible object format!");
 353     }
 354   } else {
 355     if (!Dyld->isCompatibleFormat(InputBuffer))
 356       report_fatal_error("Incompatible object format!");
 357   }
 358
 359   return Dyld->loadObject(InputBuffer);
 360 }
 361
 362 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
 363   return Dyld->getSymbolAddress(Name);
 364 }
 365
 366 void RuntimeDyld::resolveRelocations() {
 367   Dyld->resolveRelocations();
 368 }
 369
 370 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
 371                                          uint64_t Addr) {
 372   Dyld->reassignSectionAddress(SectionID, Addr);
 373 }
 374
 375 void RuntimeDyld::mapSectionAddress(void *LocalAddress,
 376                                     uint64_t TargetAddress) {
 377   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
 378 }
 379
 380 StringRef RuntimeDyld::getErrorString() {
 381   return Dyld->getErrorString();
 382 }
 383
 384 } // end namespace llvm