Home | History | Annotate | Download | only in RuntimeDyld 
      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 // Resolve the relocations for all symbols we currently know about.
     40 void RuntimeDyldImpl::resolveRelocations() {
     41   // First, resolve relocations associated with external symbols.
     42   resolveSymbols();
     43 
     44   // Just iterate over the sections we have and resolve all the relocations
     45   // in them. Gross overkill, but it gets the job done.
     46   for (int i = 0, e = Sections.size(); i != e; ++i) {
     47     reassignSectionAddress(i, Sections[i].LoadAddress);
     48   }
     49 }
     50 
     51 void RuntimeDyldImpl::mapSectionAddress(void *LocalAddress,
     52                                         uint64_t TargetAddress) {
     53   for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
     54     if (Sections[i].Address == LocalAddress) {
     55       reassignSectionAddress(i, TargetAddress);
     56       return;
     57     }
     58   }
     59   llvm_unreachable("Attempting to remap address of unknown section!");
     60 }
     61 
     62 // Subclasses can implement this method to create specialized image instances
     63 // The caller owns the the pointer that is returned.
     64 ObjectImage *RuntimeDyldImpl::createObjectImage(const MemoryBuffer *InputBuffer) {
     65   ObjectFile *ObjFile = ObjectFile::createObjectFile(const_cast<MemoryBuffer*>
     66                                                                  (InputBuffer));
     67   ObjectImage *Obj = new ObjectImage(ObjFile);
     68   return Obj;
     69 }
     70 
     71 bool RuntimeDyldImpl::loadObject(const MemoryBuffer *InputBuffer) {
     72   OwningPtr<ObjectImage> obj(createObjectImage(InputBuffer));
     73   if (!obj)
     74     report_fatal_error("Unable to create object image from memory buffer!");
     75 
     76   Arch = (Triple::ArchType)obj->getArch();
     77 
     78   LocalSymbolMap LocalSymbols;     // Functions and data symbols from the
     79                                    // object file.
     80   ObjSectionToIDMap LocalSections; // Used sections from the object file
     81   CommonSymbolMap   CommonSymbols; // Common symbols requiring allocation
     82   uint64_t          CommonSize = 0;
     83 
     84   error_code err;
     85   // Parse symbols
     86   DEBUG(dbgs() << "Parse symbols:\n");
     87   for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
     88        i != e; i.increment(err)) {
     89     Check(err);
     90     object::SymbolRef::Type SymType;
     91     StringRef Name;
     92     Check(i->getType(SymType));
     93     Check(i->getName(Name));
     94 
     95     uint32_t flags;
     96     Check(i->getFlags(flags));
     97 
     98     bool isCommon = flags & SymbolRef::SF_Common;
     99     if (isCommon) {
    100       // Add the common symbols to a list.  We'll allocate them all below.
    101       uint64_t Size = 0;
    102       Check(i->getSize(Size));
    103       CommonSize += Size;
    104       CommonSymbols[*i] = Size;
    105     } else {
    106       if (SymType == object::SymbolRef::ST_Function ||
    107           SymType == object::SymbolRef::ST_Data) {
    108         uint64_t FileOffset;
    109         StringRef sData;
    110         section_iterator si = obj->end_sections();
    111         Check(i->getFileOffset(FileOffset));
    112         Check(i->getSection(si));
    113         if (si == obj->end_sections()) continue;
    114         Check(si->getContents(sData));
    115         const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
    116                                 (uintptr_t)FileOffset;
    117         uintptr_t SectOffset = (uintptr_t)(SymPtr - (const uint8_t*)sData.begin());
    118         unsigned SectionID =
    119           findOrEmitSection(*obj,
    120                             *si,
    121                             SymType == object::SymbolRef::ST_Function,
    122                             LocalSections);
    123         bool isGlobal = flags & SymbolRef::SF_Global;
    124         LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
    125         DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
    126                      << " flags: " << flags
    127                      << " SID: " << SectionID
    128                      << " Offset: " << format("%p", SectOffset));
    129         if (isGlobal)
    130           SymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
    131       }
    132     }
    133     DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
    134   }
    135 
    136   // Allocate common symbols
    137   if (CommonSize != 0)
    138     emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
    139 
    140   // Parse and proccess relocations
    141   DEBUG(dbgs() << "Parse relocations:\n");
    142   for (section_iterator si = obj->begin_sections(),
    143        se = obj->end_sections(); si != se; si.increment(err)) {
    144     Check(err);
    145     bool isFirstRelocation = true;
    146     unsigned SectionID = 0;
    147     StubMap Stubs;
    148 
    149     for (relocation_iterator i = si->begin_relocations(),
    150          e = si->end_relocations(); i != e; i.increment(err)) {
    151       Check(err);
    152 
    153       // If it's first relocation in this section, find its SectionID
    154       if (isFirstRelocation) {
    155         SectionID = findOrEmitSection(*obj, *si, true, LocalSections);
    156         DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
    157         isFirstRelocation = false;
    158       }
    159 
    160       ObjRelocationInfo RI;
    161       RI.SectionID = SectionID;
    162       Check(i->getAdditionalInfo(RI.AdditionalInfo));
    163       Check(i->getOffset(RI.Offset));
    164       Check(i->getSymbol(RI.Symbol));
    165       Check(i->getType(RI.Type));
    166 
    167       DEBUG(dbgs() << "\t\tAddend: " << RI.AdditionalInfo
    168                    << " Offset: " << format("%p", (uintptr_t)RI.Offset)
    169                    << " Type: " << (uint32_t)(RI.Type & 0xffffffffL)
    170                    << "\n");
    171       processRelocationRef(RI, *obj, LocalSections, LocalSymbols, Stubs);
    172     }
    173   }
    174 
    175   handleObjectLoaded(obj.take());
    176 
    177   return false;
    178 }
    179 
    180 unsigned RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
    181                                             const CommonSymbolMap &Map,
    182                                             uint64_t TotalSize,
    183                                             LocalSymbolMap &LocalSymbols) {
    184   // Allocate memory for the section
    185   unsigned SectionID = Sections.size();
    186   uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
    187                                               SectionID);
    188   if (!Addr)
    189     report_fatal_error("Unable to allocate memory for common symbols!");
    190   uint64_t Offset = 0;
    191   Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
    192   memset(Addr, 0, TotalSize);
    193 
    194   DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
    195                << " new addr: " << format("%p", Addr)
    196                << " DataSize: " << TotalSize
    197                << "\n");
    198 
    199   // Assign the address of each symbol
    200   for (CommonSymbolMap::const_iterator it = Map.begin(), itEnd = Map.end();
    201        it != itEnd; it++) {
    202     uint64_t Size = it->second;
    203     StringRef Name;
    204     it->first.getName(Name);
    205     Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
    206     LocalSymbols[Name.data()] = SymbolLoc(SectionID, Offset);
    207     Offset += Size;
    208     Addr += Size;
    209   }
    210 
    211   return SectionID;
    212 }
    213 
    214 unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
    215                                       const SectionRef &Section,
    216                                       bool IsCode) {
    217 
    218   unsigned StubBufSize = 0,
    219            StubSize = getMaxStubSize();
    220   error_code err;
    221   if (StubSize > 0) {
    222     for (relocation_iterator i = Section.begin_relocations(),
    223          e = Section.end_relocations(); i != e; i.increment(err), Check(err))
    224       StubBufSize += StubSize;
    225   }
    226   StringRef data;
    227   uint64_t Alignment64;
    228   Check(Section.getContents(data));
    229   Check(Section.getAlignment(Alignment64));
    230 
    231   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
    232   bool IsRequired;
    233   bool IsVirtual;
    234   bool IsZeroInit;
    235   uint64_t DataSize;
    236   Check(Section.isRequiredForExecution(IsRequired));
    237   Check(Section.isVirtual(IsVirtual));
    238   Check(Section.isZeroInit(IsZeroInit));
    239   Check(Section.getSize(DataSize));
    240 
    241   unsigned Allocate;
    242   unsigned SectionID = Sections.size();
    243   uint8_t *Addr;
    244   const char *pData = 0;
    245 
    246   // Some sections, such as debug info, don't need to be loaded for execution.
    247   // Leave those where they are.
    248   if (IsRequired) {
    249     Allocate = DataSize + StubBufSize;
    250     Addr = IsCode
    251       ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
    252       : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
    253     if (!Addr)
    254       report_fatal_error("Unable to allocate section memory!");
    255 
    256     // Virtual sections have no data in the object image, so leave pData = 0
    257     if (!IsVirtual)
    258       pData = data.data();
    259 
    260     // Zero-initialize or copy the data from the image
    261     if (IsZeroInit || IsVirtual)
    262       memset(Addr, 0, DataSize);
    263     else
    264       memcpy(Addr, pData, DataSize);
    265 
    266     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
    267                  << " obj addr: " << format("%p", pData)
    268                  << " new addr: " << format("%p", Addr)
    269                  << " DataSize: " << DataSize
    270                  << " StubBufSize: " << StubBufSize
    271                  << " Allocate: " << Allocate
    272                  << "\n");
    273     Obj.updateSectionAddress(Section, (uint64_t)Addr);
    274   }
    275   else {
    276     // Even if we didn't load the section, we need to record an entry for it
    277     //   to handle later processing (and by 'handle' I mean don't do anything
    278     //   with these sections).
    279     Allocate = 0;
    280     Addr = 0;
    281     DEBUG(dbgs() << "emitSection SectionID: " << SectionID
    282                  << " obj addr: " << format("%p", data.data())
    283                  << " new addr: 0"
    284                  << " DataSize: " << DataSize
    285                  << " StubBufSize: " << StubBufSize
    286                  << " Allocate: " << Allocate
    287                  << "\n");
    288   }
    289 
    290   Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
    291   return SectionID;
    292 }
    293 
    294 unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
    295                                             const SectionRef &Section,
    296                                             bool IsCode,
    297                                             ObjSectionToIDMap &LocalSections) {
    298 
    299   unsigned SectionID = 0;
    300   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
    301   if (i != LocalSections.end())
    302     SectionID = i->second;
    303   else {
    304     SectionID = emitSection(Obj, Section, IsCode);
    305     LocalSections[Section] = SectionID;
    306   }
    307   return SectionID;
    308 }
    309 
    310 void RuntimeDyldImpl::AddRelocation(const RelocationValueRef &Value,
    311                                    unsigned SectionID, uintptr_t Offset,
    312                                    uint32_t RelType) {
    313   DEBUG(dbgs() << "AddRelocation SymNamePtr: " << format("%p", Value.SymbolName)
    314                << " SID: " << Value.SectionID
    315                << " Addend: " << format("%p", Value.Addend)
    316                << " Offset: " << format("%p", Offset)
    317                << " RelType: " << format("%x", RelType)
    318                << "\n");
    319 
    320   if (Value.SymbolName == 0) {
    321     Relocations[Value.SectionID].push_back(RelocationEntry(
    322       SectionID,
    323       Offset,
    324       RelType,
    325       Value.Addend));
    326   } else
    327     SymbolRelocations[Value.SymbolName].push_back(RelocationEntry(
    328       SectionID,
    329       Offset,
    330       RelType,
    331       Value.Addend));
    332 }
    333 
    334 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
    335   // TODO: There is only ARM far stub now. We should add the Thumb stub,
    336   // and stubs for branches Thumb - ARM and ARM - Thumb.
    337   if (Arch == Triple::arm) {
    338     uint32_t *StubAddr = (uint32_t*)Addr;
    339     *StubAddr = 0xe51ff004; // ldr pc,<label>
    340     return (uint8_t*)++StubAddr;
    341   }
    342   else
    343     return Addr;
    344 }
    345 
    346 // Assign an address to a symbol name and resolve all the relocations
    347 // associated with it.
    348 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
    349                                              uint64_t Addr) {
    350   // The address to use for relocation resolution is not
    351   // the address of the local section buffer. We must be doing
    352   // a remote execution environment of some sort. Re-apply any
    353   // relocations referencing this section with the given address.
    354   //
    355   // Addr is a uint64_t because we can't assume the pointer width
    356   // of the target is the same as that of the host. Just use a generic
    357   // "big enough" type.
    358   Sections[SectionID].LoadAddress = Addr;
    359   DEBUG(dbgs() << "Resolving relocations Section #" << SectionID
    360           << "\t" << format("%p", (uint8_t *)Addr)
    361           << "\n");
    362   resolveRelocationList(Relocations[SectionID], Addr);
    363 }
    364 
    365 void RuntimeDyldImpl::resolveRelocationEntry(const RelocationEntry &RE,
    366                                              uint64_t Value) {
    367     // Ignore relocations for sections that were not loaded
    368     if (Sections[RE.SectionID].Address != 0) {
    369       uint8_t *Target = Sections[RE.SectionID].Address + RE.Offset;
    370       DEBUG(dbgs() << "\tSectionID: " << RE.SectionID
    371             << " + " << RE.Offset << " (" << format("%p", Target) << ")"
    372             << " Data: " << RE.Data
    373             << " Addend: " << RE.Addend
    374             << "\n");
    375 
    376       resolveRelocation(Target, Sections[RE.SectionID].LoadAddress + RE.Offset,
    377                         Value, RE.Data, RE.Addend);
    378   }
    379 }
    380 
    381 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
    382                                             uint64_t Value) {
    383   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
    384     resolveRelocationEntry(Relocs[i], Value);
    385   }
    386 }
    387 
    388 // resolveSymbols - Resolve any relocations to the specified symbols if
    389 // we know where it lives.
    390 void RuntimeDyldImpl::resolveSymbols() {
    391   StringMap<RelocationList>::iterator i = SymbolRelocations.begin(),
    392                                       e = SymbolRelocations.end();
    393   for (; i != e; i++) {
    394     StringRef Name = i->first();
    395     RelocationList &Relocs = i->second;
    396     StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
    397     if (Loc == SymbolTable.end()) {
    398       // This is an external symbol, try to get it address from
    399       // MemoryManager.
    400       uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
    401                                                                    true);
    402       DEBUG(dbgs() << "Resolving relocations Name: " << Name
    403               << "\t" << format("%p", Addr)
    404               << "\n");
    405       resolveRelocationList(Relocs, (uintptr_t)Addr);
    406     } else {
    407       // Change the relocation to be section relative rather than symbol
    408       // relative and move it to the resolved relocation list.
    409       DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
    410       for (int i = 0, e = Relocs.size(); i != e; ++i) {
    411         RelocationEntry Entry = Relocs[i];
    412         Entry.Addend += Loc->second.second;
    413         Relocations[Loc->second.first].push_back(Entry);
    414       }
    415       Relocs.clear();
    416     }
    417   }
    418 }
    419 
    420 
    421 //===----------------------------------------------------------------------===//
    422 // RuntimeDyld class implementation
    423 RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
    424   Dyld = 0;
    425   MM = mm;
    426 }
    427 
    428 RuntimeDyld::~RuntimeDyld() {
    429   delete Dyld;
    430 }
    431 
    432 bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
    433   if (!Dyld) {
    434     sys::LLVMFileType type = sys::IdentifyFileType(
    435             InputBuffer->getBufferStart(),
    436             static_cast<unsigned>(InputBuffer->getBufferSize()));
    437     switch (type) {
    438       case sys::ELF_Relocatable_FileType:
    439       case sys::ELF_Executable_FileType:
    440       case sys::ELF_SharedObject_FileType:
    441       case sys::ELF_Core_FileType:
    442         Dyld = new RuntimeDyldELF(MM);
    443         break;
    444       case sys::Mach_O_Object_FileType:
    445       case sys::Mach_O_Executable_FileType:
    446       case sys::Mach_O_FixedVirtualMemorySharedLib_FileType:
    447       case sys::Mach_O_Core_FileType:
    448       case sys::Mach_O_PreloadExecutable_FileType:
    449       case sys::Mach_O_DynamicallyLinkedSharedLib_FileType:
    450       case sys::Mach_O_DynamicLinker_FileType:
    451       case sys::Mach_O_Bundle_FileType:
    452       case sys::Mach_O_DynamicallyLinkedSharedLibStub_FileType:
    453       case sys::Mach_O_DSYMCompanion_FileType:
    454         Dyld = new RuntimeDyldMachO(MM);
    455         break;
    456       case sys::Unknown_FileType:
    457       case sys::Bitcode_FileType:
    458       case sys::Archive_FileType:
    459       case sys::COFF_FileType:
    460         report_fatal_error("Incompatible object format!");
    461     }
    462   } else {
    463     if (!Dyld->isCompatibleFormat(InputBuffer))
    464       report_fatal_error("Incompatible object format!");
    465   }
    466 
    467   return Dyld->loadObject(InputBuffer);
    468 }
    469 
    470 void *RuntimeDyld::getSymbolAddress(StringRef Name) {
    471   return Dyld->getSymbolAddress(Name);
    472 }
    473 
    474 void RuntimeDyld::resolveRelocations() {
    475   Dyld->resolveRelocations();
    476 }
    477 
    478 void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
    479                                          uint64_t Addr) {
    480   Dyld->reassignSectionAddress(SectionID, Addr);
    481 }
    482 
    483 void RuntimeDyld::mapSectionAddress(void *LocalAddress,
    484                                     uint64_t TargetAddress) {
    485   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
    486 }
    487 
    488 StringRef RuntimeDyld::getErrorString() {
    489   return Dyld->getErrorString();
    490 }
    491 
    492 } // end namespace llvm
    493