contrib/llvm-project/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

   1 //===-- RuntimeDyld.cpp - Run-time dynamic linker for MC-JIT ----*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Implementation of the MC-JIT runtime dynamic linker.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/ExecutionEngine/RuntimeDyld.h"
  14 #include "RuntimeDyldCOFF.h"
  15 #include "RuntimeDyldELF.h"
  16 #include "RuntimeDyldImpl.h"
  17 #include "RuntimeDyldMachO.h"
  18 #include "llvm/Object/COFF.h"
  19 #include "llvm/Object/ELFObjectFile.h"
  20 #include "llvm/Support/Alignment.h"
  21 #include "llvm/Support/MSVCErrorWorkarounds.h"
  22 #include "llvm/Support/ManagedStatic.h"
  23 #include "llvm/Support/MathExtras.h"
  24 #include <mutex>
  25
  26 #include <future>
  27
  28 using namespace llvm;
  29 using namespace llvm::object;
  30
  31 #define DEBUG_TYPE "dyld"
  32
  33 namespace {
  34
  35 enum RuntimeDyldErrorCode {
  36   GenericRTDyldError = 1
  37 };
  38
  39 // FIXME: This class is only here to support the transition to llvm::Error. It
  40 // will be removed once this transition is complete. Clients should prefer to
  41 // deal with the Error value directly, rather than converting to error_code.
  42 class RuntimeDyldErrorCategory : public std::error_category {
  43 public:
  44   const char *name() const noexcept override { return "runtimedyld"; }
  45
  46   std::string message(int Condition) const override {
  47     switch (static_cast<RuntimeDyldErrorCode>(Condition)) {
  48       case GenericRTDyldError: return "Generic RuntimeDyld error";
  49     }
  50     llvm_unreachable("Unrecognized RuntimeDyldErrorCode");
  51   }
  52 };
  53
  54 static ManagedStatic<RuntimeDyldErrorCategory> RTDyldErrorCategory;
  55
  56 }
  57
  58 char RuntimeDyldError::ID = 0;
  59
  60 void RuntimeDyldError::log(raw_ostream &OS) const {
  61   OS << ErrMsg << "\n";
  62 }
  63
  64 std::error_code RuntimeDyldError::convertToErrorCode() const {
  65   return std::error_code(GenericRTDyldError, *RTDyldErrorCategory);
  66 }
  67
  68 // Empty out-of-line virtual destructor as the key function.
  69 RuntimeDyldImpl::~RuntimeDyldImpl() {}
  70
  71 // Pin LoadedObjectInfo's vtables to this file.
  72 void RuntimeDyld::LoadedObjectInfo::anchor() {}
  73
  74 namespace llvm {
  75
  76 void RuntimeDyldImpl::registerEHFrames() {}
  77
  78 void RuntimeDyldImpl::deregisterEHFrames() {
  79   MemMgr.deregisterEHFrames();
  80 }
  81
  82 #ifndef NDEBUG
  83 static void dumpSectionMemory(const SectionEntry &S, StringRef State) {
  84   dbgs() << "----- Contents of section " << S.getName() << " " << State
  85          << " -----";
  86
  87   if (S.getAddress() == nullptr) {
  88     dbgs() << "\n          <section not emitted>\n";
  89     return;
  90   }
  91
  92   const unsigned ColsPerRow = 16;
  93
  94   uint8_t *DataAddr = S.getAddress();
  95   uint64_t LoadAddr = S.getLoadAddress();
  96
  97   unsigned StartPadding = LoadAddr & (ColsPerRow - 1);
  98   unsigned BytesRemaining = S.getSize();
  99
 100   if (StartPadding) {
 101     dbgs() << "\n" << format("0x%016" PRIx64,
 102                              LoadAddr & ~(uint64_t)(ColsPerRow - 1)) << ":";
 103     while (StartPadding--)
 104       dbgs() << "   ";
 105   }
 106
 107   while (BytesRemaining > 0) {
 108     if ((LoadAddr & (ColsPerRow - 1)) == 0)
 109       dbgs() << "\n" << format("0x%016" PRIx64, LoadAddr) << ":";
 110
 111     dbgs() << " " << format("%02x", *DataAddr);
 112
 113     ++DataAddr;
 114     ++LoadAddr;
 115     --BytesRemaining;
 116   }
 117
 118   dbgs() << "\n";
 119 }
 120 #endif
 121
 122 // Resolve the relocations for all symbols we currently know about.
 123 void RuntimeDyldImpl::resolveRelocations() {
 124   std::lock_guard<sys::Mutex> locked(lock);
 125
 126   // Print out the sections prior to relocation.
 127   LLVM_DEBUG(for (int i = 0, e = Sections.size(); i != e; ++i)
 128                  dumpSectionMemory(Sections[i], "before relocations"););
 129
 130   // First, resolve relocations associated with external symbols.
 131   if (auto Err = resolveExternalSymbols()) {
 132     HasError = true;
 133     ErrorStr = toString(std::move(Err));
 134   }
 135
 136   resolveLocalRelocations();
 137
 138   // Print out sections after relocation.
 139   LLVM_DEBUG(for (int i = 0, e = Sections.size(); i != e; ++i)
 140                  dumpSectionMemory(Sections[i], "after relocations"););
 141 }
 142
 143 void RuntimeDyldImpl::resolveLocalRelocations() {
 144   // Iterate over all outstanding relocations
 145   for (auto it = Relocations.begin(), e = Relocations.end(); it != e; ++it) {
 146     // The Section here (Sections[i]) refers to the section in which the
 147     // symbol for the relocation is located.  The SectionID in the relocation
 148     // entry provides the section to which the relocation will be applied.
 149     int Idx = it->first;
 150     uint64_t Addr = Sections[Idx].getLoadAddress();
 151     LLVM_DEBUG(dbgs() << "Resolving relocations Section #" << Idx << "\t"
 152                       << format("%p", (uintptr_t)Addr) << "\n");
 153     resolveRelocationList(it->second, Addr);
 154   }
 155   Relocations.clear();
 156 }
 157
 158 void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
 159                                         uint64_t TargetAddress) {
 160   std::lock_guard<sys::Mutex> locked(lock);
 161   for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
 162     if (Sections[i].getAddress() == LocalAddress) {
 163       reassignSectionAddress(i, TargetAddress);
 164       return;
 165     }
 166   }
 167   llvm_unreachable("Attempting to remap address of unknown section!");
 168 }
 169
 170 static Error getOffset(const SymbolRef &Sym, SectionRef Sec,
 171                        uint64_t &Result) {
 172   Expected<uint64_t> AddressOrErr = Sym.getAddress();
 173   if (!AddressOrErr)
 174     return AddressOrErr.takeError();
 175   Result = *AddressOrErr - Sec.getAddress();
 176   return Error::success();
 177 }
 178
 179 Expected<RuntimeDyldImpl::ObjSectionToIDMap>
 180 RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
 181   std::lock_guard<sys::Mutex> locked(lock);
 182
 183   // Save information about our target
 184   Arch = (Triple::ArchType)Obj.getArch();
 185   IsTargetLittleEndian = Obj.isLittleEndian();
 186   setMipsABI(Obj);
 187
 188   // Compute the memory size required to load all sections to be loaded
 189   // and pass this information to the memory manager
 190   if (MemMgr.needsToReserveAllocationSpace()) {
 191     uint64_t CodeSize = 0, RODataSize = 0, RWDataSize = 0;
 192     uint32_t CodeAlign = 1, RODataAlign = 1, RWDataAlign = 1;
 193     if (auto Err = computeTotalAllocSize(Obj,
 194                                          CodeSize, CodeAlign,
 195                                          RODataSize, RODataAlign,
 196                                          RWDataSize, RWDataAlign))
 197       return std::move(Err);
 198     MemMgr.reserveAllocationSpace(CodeSize, CodeAlign, RODataSize, RODataAlign,
 199                                   RWDataSize, RWDataAlign);
 200   }
 201
 202   // Used sections from the object file
 203   ObjSectionToIDMap LocalSections;
 204
 205   // Common symbols requiring allocation, with their sizes and alignments
 206   CommonSymbolList CommonSymbolsToAllocate;
 207
 208   uint64_t CommonSize = 0;
 209   uint32_t CommonAlign = 0;
 210
 211   // First, collect all weak and common symbols. We need to know if stronger
 212   // definitions occur elsewhere.
 213   JITSymbolResolver::LookupSet ResponsibilitySet;
 214   {
 215     JITSymbolResolver::LookupSet Symbols;
 216     for (auto &Sym : Obj.symbols()) {
 217       uint32_t Flags = Sym.getFlags();
 218       if ((Flags & SymbolRef::SF_Common) || (Flags & SymbolRef::SF_Weak)) {
 219         // Get symbol name.
 220         if (auto NameOrErr = Sym.getName())
 221           Symbols.insert(*NameOrErr);
 222         else
 223           return NameOrErr.takeError();
 224       }
 225     }
 226
 227     if (auto ResultOrErr = Resolver.getResponsibilitySet(Symbols))
 228       ResponsibilitySet = std::move(*ResultOrErr);
 229     else
 230       return ResultOrErr.takeError();
 231   }
 232
 233   // Parse symbols
 234   LLVM_DEBUG(dbgs() << "Parse symbols:\n");
 235   for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
 236        ++I) {
 237     uint32_t Flags = I->getFlags();
 238
 239     // Skip undefined symbols.
 240     if (Flags & SymbolRef::SF_Undefined)
 241       continue;
 242
 243     // Get the symbol type.
 244     object::SymbolRef::Type SymType;
 245     if (auto SymTypeOrErr = I->getType())
 246       SymType = *SymTypeOrErr;
 247     else
 248       return SymTypeOrErr.takeError();
 249
 250     // Get symbol name.
 251     StringRef Name;
 252     if (auto NameOrErr = I->getName())
 253       Name = *NameOrErr;
 254     else
 255       return NameOrErr.takeError();
 256
 257     // Compute JIT symbol flags.
 258     auto JITSymFlags = getJITSymbolFlags(*I);
 259     if (!JITSymFlags)
 260       return JITSymFlags.takeError();
 261
 262     // If this is a weak definition, check to see if there's a strong one.
 263     // If there is, skip this symbol (we won't be providing it: the strong
 264     // definition will). If there's no strong definition, make this definition
 265     // strong.
 266     if (JITSymFlags->isWeak() || JITSymFlags->isCommon()) {
 267       // First check whether there's already a definition in this instance.
 268       if (GlobalSymbolTable.count(Name))
 269         continue;
 270
 271       // If we're not responsible for this symbol, skip it.
 272       if (!ResponsibilitySet.count(Name))
 273         continue;
 274
 275       // Otherwise update the flags on the symbol to make this definition
 276       // strong.
 277       if (JITSymFlags->isWeak())
 278         *JITSymFlags &= ~JITSymbolFlags::Weak;
 279       if (JITSymFlags->isCommon()) {
 280         *JITSymFlags &= ~JITSymbolFlags::Common;
 281         uint32_t Align = I->getAlignment();
 282         uint64_t Size = I->getCommonSize();
 283         if (!CommonAlign)
 284           CommonAlign = Align;
 285         CommonSize = alignTo(CommonSize, Align) + Size;
 286         CommonSymbolsToAllocate.push_back(*I);
 287       }
 288     }
 289
 290     if (Flags & SymbolRef::SF_Absolute &&
 291         SymType != object::SymbolRef::ST_File) {
 292       uint64_t Addr = 0;
 293       if (auto AddrOrErr = I->getAddress())
 294         Addr = *AddrOrErr;
 295       else
 296         return AddrOrErr.takeError();
 297
 298       unsigned SectionID = AbsoluteSymbolSection;
 299
 300       LLVM_DEBUG(dbgs() << "\tType: " << SymType << " (absolute) Name: " << Name
 301                         << " SID: " << SectionID
 302                         << " Offset: " << format("%p", (uintptr_t)Addr)
 303                         << " flags: " << Flags << "\n");
 304       GlobalSymbolTable[Name] = SymbolTableEntry(SectionID, Addr, *JITSymFlags);
 305     } else if (SymType == object::SymbolRef::ST_Function ||
 306                SymType == object::SymbolRef::ST_Data ||
 307                SymType == object::SymbolRef::ST_Unknown ||
 308                SymType == object::SymbolRef::ST_Other) {
 309
 310       section_iterator SI = Obj.section_end();
 311       if (auto SIOrErr = I->getSection())
 312         SI = *SIOrErr;
 313       else
 314         return SIOrErr.takeError();
 315
 316       if (SI == Obj.section_end())
 317         continue;
 318
 319       // Get symbol offset.
 320       uint64_t SectOffset;
 321       if (auto Err = getOffset(*I, *SI, SectOffset))
 322         return std::move(Err);
 323
 324       bool IsCode = SI->isText();
 325       unsigned SectionID;
 326       if (auto SectionIDOrErr =
 327               findOrEmitSection(Obj, *SI, IsCode, LocalSections))
 328         SectionID = *SectionIDOrErr;
 329       else
 330         return SectionIDOrErr.takeError();
 331
 332       LLVM_DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name
 333                         << " SID: " << SectionID
 334                         << " Offset: " << format("%p", (uintptr_t)SectOffset)
 335                         << " flags: " << Flags << "\n");
 336       GlobalSymbolTable[Name] =
 337           SymbolTableEntry(SectionID, SectOffset, *JITSymFlags);
 338     }
 339   }
 340
 341   // Allocate common symbols
 342   if (auto Err = emitCommonSymbols(Obj, CommonSymbolsToAllocate, CommonSize,
 343                                    CommonAlign))
 344     return std::move(Err);
 345
 346   // Parse and process relocations
 347   LLVM_DEBUG(dbgs() << "Parse relocations:\n");
 348   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 349        SI != SE; ++SI) {
 350     StubMap Stubs;
 351
 352     Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
 353     if (!RelSecOrErr)
 354       return RelSecOrErr.takeError();
 355
 356     section_iterator RelocatedSection = *RelSecOrErr;
 357     if (RelocatedSection == SE)
 358       continue;
 359
 360     relocation_iterator I = SI->relocation_begin();
 361     relocation_iterator E = SI->relocation_end();
 362
 363     if (I == E && !ProcessAllSections)
 364       continue;
 365
 366     bool IsCode = RelocatedSection->isText();
 367     unsigned SectionID = 0;
 368     if (auto SectionIDOrErr = findOrEmitSection(Obj, *RelocatedSection, IsCode,
 369                                                 LocalSections))
 370       SectionID = *SectionIDOrErr;
 371     else
 372       return SectionIDOrErr.takeError();
 373
 374     LLVM_DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
 375
 376     for (; I != E;)
 377       if (auto IOrErr = processRelocationRef(SectionID, I, Obj, LocalSections, Stubs))
 378         I = *IOrErr;
 379       else
 380         return IOrErr.takeError();
 381
 382     // If there is a NotifyStubEmitted callback set, call it to register any
 383     // stubs created for this section.
 384     if (NotifyStubEmitted) {
 385       StringRef FileName = Obj.getFileName();
 386       StringRef SectionName = Sections[SectionID].getName();
 387       for (auto &KV : Stubs) {
 388
 389         auto &VR = KV.first;
 390         uint64_t StubAddr = KV.second;
 391
 392         // If this is a named stub, just call NotifyStubEmitted.
 393         if (VR.SymbolName) {
 394           NotifyStubEmitted(FileName, SectionName, VR.SymbolName, SectionID,
 395                             StubAddr);
 396           continue;
 397         }
 398
 399         // Otherwise we will have to try a reverse lookup on the globla symbol table.
 400         for (auto &GSTMapEntry : GlobalSymbolTable) {
 401           StringRef SymbolName = GSTMapEntry.first();
 402           auto &GSTEntry = GSTMapEntry.second;
 403           if (GSTEntry.getSectionID() == VR.SectionID &&
 404               GSTEntry.getOffset() == VR.Offset) {
 405             NotifyStubEmitted(FileName, SectionName, SymbolName, SectionID,
 406                               StubAddr);
 407             break;
 408           }
 409         }
 410       }
 411     }
 412   }
 413
 414   // Process remaining sections
 415   if (ProcessAllSections) {
 416     LLVM_DEBUG(dbgs() << "Process remaining sections:\n");
 417     for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 418          SI != SE; ++SI) {
 419
 420       /* Ignore already loaded sections */
 421       if (LocalSections.find(*SI) != LocalSections.end())
 422         continue;
 423
 424       bool IsCode = SI->isText();
 425       if (auto SectionIDOrErr =
 426               findOrEmitSection(Obj, *SI, IsCode, LocalSections))
 427         LLVM_DEBUG(dbgs() << "\tSectionID: " << (*SectionIDOrErr) << "\n");
 428       else
 429         return SectionIDOrErr.takeError();
 430     }
 431   }
 432
 433   // Give the subclasses a chance to tie-up any loose ends.
 434   if (auto Err = finalizeLoad(Obj, LocalSections))
 435     return std::move(Err);
 436
 437 //   for (auto E : LocalSections)
 438 //     llvm::dbgs() << "Added: " << E.first.getRawDataRefImpl() << " -> " << E.second << "\n";
 439
 440   return LocalSections;
 441 }
 442
 443 // A helper method for computeTotalAllocSize.
 444 // Computes the memory size required to allocate sections with the given sizes,
 445 // assuming that all sections are allocated with the given alignment
 446 static uint64_t
 447 computeAllocationSizeForSections(std::vector<uint64_t> &SectionSizes,
 448                                  uint64_t Alignment) {
 449   uint64_t TotalSize = 0;
 450   for (size_t Idx = 0, Cnt = SectionSizes.size(); Idx < Cnt; Idx++) {
 451     uint64_t AlignedSize =
 452         (SectionSizes[Idx] + Alignment - 1) / Alignment * Alignment;
 453     TotalSize += AlignedSize;
 454   }
 455   return TotalSize;
 456 }
 457
 458 static bool isRequiredForExecution(const SectionRef Section) {
 459   const ObjectFile *Obj = Section.getObject();
 460   if (isa<object::ELFObjectFileBase>(Obj))
 461     return ELFSectionRef(Section).getFlags() & ELF::SHF_ALLOC;
 462   if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj)) {
 463     const coff_section *CoffSection = COFFObj->getCOFFSection(Section);
 464     // Avoid loading zero-sized COFF sections.
 465     // In PE files, VirtualSize gives the section size, and SizeOfRawData
 466     // may be zero for sections with content. In Obj files, SizeOfRawData
 467     // gives the section size, and VirtualSize is always zero. Hence
 468     // the need to check for both cases below.
 469     bool HasContent =
 470         (CoffSection->VirtualSize > 0) || (CoffSection->SizeOfRawData > 0);
 471     bool IsDiscardable =
 472         CoffSection->Characteristics &
 473         (COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_LNK_INFO);
 474     return HasContent && !IsDiscardable;
 475   }
 476
 477   assert(isa<MachOObjectFile>(Obj));
 478   return true;
 479 }
 480
 481 static bool isReadOnlyData(const SectionRef Section) {
 482   const ObjectFile *Obj = Section.getObject();
 483   if (isa<object::ELFObjectFileBase>(Obj))
 484     return !(ELFSectionRef(Section).getFlags() &
 485              (ELF::SHF_WRITE | ELF::SHF_EXECINSTR));
 486   if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
 487     return ((COFFObj->getCOFFSection(Section)->Characteristics &
 488              (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
 489              | COFF::IMAGE_SCN_MEM_READ
 490              | COFF::IMAGE_SCN_MEM_WRITE))
 491              ==
 492              (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
 493              | COFF::IMAGE_SCN_MEM_READ));
 494
 495   assert(isa<MachOObjectFile>(Obj));
 496   return false;
 497 }
 498
 499 static bool isZeroInit(const SectionRef Section) {
 500   const ObjectFile *Obj = Section.getObject();
 501   if (isa<object::ELFObjectFileBase>(Obj))
 502     return ELFSectionRef(Section).getType() == ELF::SHT_NOBITS;
 503   if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
 504     return COFFObj->getCOFFSection(Section)->Characteristics &
 505             COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
 506
 507   auto *MachO = cast<MachOObjectFile>(Obj);
 508   unsigned SectionType = MachO->getSectionType(Section);
 509   return SectionType == MachO::S_ZEROFILL ||
 510          SectionType == MachO::S_GB_ZEROFILL;
 511 }
 512
 513 // Compute an upper bound of the memory size that is required to load all
 514 // sections
 515 Error RuntimeDyldImpl::computeTotalAllocSize(const ObjectFile &Obj,
 516                                              uint64_t &CodeSize,
 517                                              uint32_t &CodeAlign,
 518                                              uint64_t &RODataSize,
 519                                              uint32_t &RODataAlign,
 520                                              uint64_t &RWDataSize,
 521                                              uint32_t &RWDataAlign) {
 522   // Compute the size of all sections required for execution
 523   std::vector<uint64_t> CodeSectionSizes;
 524   std::vector<uint64_t> ROSectionSizes;
 525   std::vector<uint64_t> RWSectionSizes;
 526
 527   // Collect sizes of all sections to be loaded;
 528   // also determine the max alignment of all sections
 529   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 530        SI != SE; ++SI) {
 531     const SectionRef &Section = *SI;
 532
 533     bool IsRequired = isRequiredForExecution(Section) || ProcessAllSections;
 534
 535     // Consider only the sections that are required to be loaded for execution
 536     if (IsRequired) {
 537       uint64_t DataSize = Section.getSize();
 538       uint64_t Alignment64 = Section.getAlignment();
 539       unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 540       bool IsCode = Section.isText();
 541       bool IsReadOnly = isReadOnlyData(Section);
 542
 543       Expected<StringRef> NameOrErr = Section.getName();
 544       if (!NameOrErr)
 545         return NameOrErr.takeError();
 546       StringRef Name = *NameOrErr;
 547
 548       uint64_t StubBufSize = computeSectionStubBufSize(Obj, Section);
 549
 550       uint64_t PaddingSize = 0;
 551       if (Name == ".eh_frame")
 552         PaddingSize += 4;
 553       if (StubBufSize != 0)
 554         PaddingSize += getStubAlignment() - 1;
 555
 556       uint64_t SectionSize = DataSize + PaddingSize + StubBufSize;
 557
 558       // The .eh_frame section (at least on Linux) needs an extra four bytes
 559       // padded
 560       // with zeroes added at the end.  For MachO objects, this section has a
 561       // slightly different name, so this won't have any effect for MachO
 562       // objects.
 563       if (Name == ".eh_frame")
 564         SectionSize += 4;
 565
 566       if (!SectionSize)
 567         SectionSize = 1;
 568
 569       if (IsCode) {
 570         CodeAlign = std::max(CodeAlign, Alignment);
 571         CodeSectionSizes.push_back(SectionSize);
 572       } else if (IsReadOnly) {
 573         RODataAlign = std::max(RODataAlign, Alignment);
 574         ROSectionSizes.push_back(SectionSize);
 575       } else {
 576         RWDataAlign = std::max(RWDataAlign, Alignment);
 577         RWSectionSizes.push_back(SectionSize);
 578       }
 579     }
 580   }
 581
 582   // Compute Global Offset Table size. If it is not zero we
 583   // also update alignment, which is equal to a size of a
 584   // single GOT entry.
 585   if (unsigned GotSize = computeGOTSize(Obj)) {
 586     RWSectionSizes.push_back(GotSize);
 587     RWDataAlign = std::max<uint32_t>(RWDataAlign, getGOTEntrySize());
 588   }
 589
 590   // Compute the size of all common symbols
 591   uint64_t CommonSize = 0;
 592   uint32_t CommonAlign = 1;
 593   for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
 594        ++I) {
 595     uint32_t Flags = I->getFlags();
 596     if (Flags & SymbolRef::SF_Common) {
 597       // Add the common symbols to a list.  We'll allocate them all below.
 598       uint64_t Size = I->getCommonSize();
 599       uint32_t Align = I->getAlignment();
 600       // If this is the first common symbol, use its alignment as the alignment
 601       // for the common symbols section.
 602       if (CommonSize == 0)
 603         CommonAlign = Align;
 604       CommonSize = alignTo(CommonSize, Align) + Size;
 605     }
 606   }
 607   if (CommonSize != 0) {
 608     RWSectionSizes.push_back(CommonSize);
 609     RWDataAlign = std::max(RWDataAlign, CommonAlign);
 610   }
 611
 612   // Compute the required allocation space for each different type of sections
 613   // (code, read-only data, read-write data) assuming that all sections are
 614   // allocated with the max alignment. Note that we cannot compute with the
 615   // individual alignments of the sections, because then the required size
 616   // depends on the order, in which the sections are allocated.
 617   CodeSize = computeAllocationSizeForSections(CodeSectionSizes, CodeAlign);
 618   RODataSize = computeAllocationSizeForSections(ROSectionSizes, RODataAlign);
 619   RWDataSize = computeAllocationSizeForSections(RWSectionSizes, RWDataAlign);
 620
 621   return Error::success();
 622 }
 623
 624 // compute GOT size
 625 unsigned RuntimeDyldImpl::computeGOTSize(const ObjectFile &Obj) {
 626   size_t GotEntrySize = getGOTEntrySize();
 627   if (!GotEntrySize)
 628     return 0;
 629
 630   size_t GotSize = 0;
 631   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 632        SI != SE; ++SI) {
 633
 634     for (const RelocationRef &Reloc : SI->relocations())
 635       if (relocationNeedsGot(Reloc))
 636         GotSize += GotEntrySize;
 637   }
 638
 639   return GotSize;
 640 }
 641
 642 // compute stub buffer size for the given section
 643 unsigned RuntimeDyldImpl::computeSectionStubBufSize(const ObjectFile &Obj,
 644                                                     const SectionRef &Section) {
 645   unsigned StubSize = getMaxStubSize();
 646   if (StubSize == 0) {
 647     return 0;
 648   }
 649   // FIXME: this is an inefficient way to handle this. We should computed the
 650   // necessary section allocation size in loadObject by walking all the sections
 651   // once.
 652   unsigned StubBufSize = 0;
 653   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
 654        SI != SE; ++SI) {
 655
 656     Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
 657     if (!RelSecOrErr)
 658       report_fatal_error(toString(RelSecOrErr.takeError()));
 659
 660     section_iterator RelSecI = *RelSecOrErr;
 661     if (!(RelSecI == Section))
 662       continue;
 663
 664     for (const RelocationRef &Reloc : SI->relocations())
 665       if (relocationNeedsStub(Reloc))
 666         StubBufSize += StubSize;
 667   }
 668
 669   // Get section data size and alignment
 670   uint64_t DataSize = Section.getSize();
 671   uint64_t Alignment64 = Section.getAlignment();
 672
 673   // Add stubbuf size alignment
 674   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 675   unsigned StubAlignment = getStubAlignment();
 676   unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
 677   if (StubAlignment > EndAlignment)
 678     StubBufSize += StubAlignment - EndAlignment;
 679   return StubBufSize;
 680 }
 681
 682 uint64_t RuntimeDyldImpl::readBytesUnaligned(uint8_t *Src,
 683                                              unsigned Size) const {
 684   uint64_t Result = 0;
 685   if (IsTargetLittleEndian) {
 686     Src += Size - 1;
 687     while (Size--)
 688       Result = (Result << 8) | *Src--;
 689   } else
 690     while (Size--)
 691       Result = (Result << 8) | *Src++;
 692
 693   return Result;
 694 }
 695
 696 void RuntimeDyldImpl::writeBytesUnaligned(uint64_t Value, uint8_t *Dst,
 697                                           unsigned Size) const {
 698   if (IsTargetLittleEndian) {
 699     while (Size--) {
 700       *Dst++ = Value & 0xFF;
 701       Value >>= 8;
 702     }
 703   } else {
 704     Dst += Size - 1;
 705     while (Size--) {
 706       *Dst-- = Value & 0xFF;
 707       Value >>= 8;
 708     }
 709   }
 710 }
 711
 712 Expected<JITSymbolFlags>
 713 RuntimeDyldImpl::getJITSymbolFlags(const SymbolRef &SR) {
 714   return JITSymbolFlags::fromObjectSymbol(SR);
 715 }
 716
 717 Error RuntimeDyldImpl::emitCommonSymbols(const ObjectFile &Obj,
 718                                          CommonSymbolList &SymbolsToAllocate,
 719                                          uint64_t CommonSize,
 720                                          uint32_t CommonAlign) {
 721   if (SymbolsToAllocate.empty())
 722     return Error::success();
 723
 724   // Allocate memory for the section
 725   unsigned SectionID = Sections.size();
 726   uint8_t *Addr = MemMgr.allocateDataSection(CommonSize, CommonAlign, SectionID,
 727                                              "<common symbols>", false);
 728   if (!Addr)
 729     report_fatal_error("Unable to allocate memory for common symbols!");
 730   uint64_t Offset = 0;
 731   Sections.push_back(
 732       SectionEntry("<common symbols>", Addr, CommonSize, CommonSize, 0));
 733   memset(Addr, 0, CommonSize);
 734
 735   LLVM_DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
 736                     << " new addr: " << format("%p", Addr)
 737                     << " DataSize: " << CommonSize << "\n");
 738
 739   // Assign the address of each symbol
 740   for (auto &Sym : SymbolsToAllocate) {
 741     uint32_t Alignment = Sym.getAlignment();
 742     uint64_t Size = Sym.getCommonSize();
 743     StringRef Name;
 744     if (auto NameOrErr = Sym.getName())
 745       Name = *NameOrErr;
 746     else
 747       return NameOrErr.takeError();
 748     if (Alignment) {
 749       // This symbol has an alignment requirement.
 750       uint64_t AlignOffset =
 751           offsetToAlignment((uint64_t)Addr, Align(Alignment));
 752       Addr += AlignOffset;
 753       Offset += AlignOffset;
 754     }
 755     auto JITSymFlags = getJITSymbolFlags(Sym);
 756
 757     if (!JITSymFlags)
 758       return JITSymFlags.takeError();
 759
 760     LLVM_DEBUG(dbgs() << "Allocating common symbol " << Name << " address "
 761                       << format("%p", Addr) << "\n");
 762     GlobalSymbolTable[Name] =
 763         SymbolTableEntry(SectionID, Offset, std::move(*JITSymFlags));
 764     Offset += Size;
 765     Addr += Size;
 766   }
 767
 768   return Error::success();
 769 }
 770
 771 Expected<unsigned>
 772 RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
 773                              const SectionRef &Section,
 774                              bool IsCode) {
 775   StringRef data;
 776   uint64_t Alignment64 = Section.getAlignment();
 777
 778   unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
 779   unsigned PaddingSize = 0;
 780   unsigned StubBufSize = 0;
 781   bool IsRequired = isRequiredForExecution(Section);
 782   bool IsVirtual = Section.isVirtual();
 783   bool IsZeroInit = isZeroInit(Section);
 784   bool IsReadOnly = isReadOnlyData(Section);
 785   uint64_t DataSize = Section.getSize();
 786
 787   // An alignment of 0 (at least with ELF) is identical to an alignment of 1,
 788   // while being more "polite".  Other formats do not support 0-aligned sections
 789   // anyway, so we should guarantee that the alignment is always at least 1.
 790   Alignment = std::max(1u, Alignment);
 791
 792   Expected<StringRef> NameOrErr = Section.getName();
 793   if (!NameOrErr)
 794     return NameOrErr.takeError();
 795   StringRef Name = *NameOrErr;
 796
 797   StubBufSize = computeSectionStubBufSize(Obj, Section);
 798
 799   // The .eh_frame section (at least on Linux) needs an extra four bytes padded
 800   // with zeroes added at the end.  For MachO objects, this section has a
 801   // slightly different name, so this won't have any effect for MachO objects.
 802   if (Name == ".eh_frame")
 803     PaddingSize = 4;
 804
 805   uintptr_t Allocate;
 806   unsigned SectionID = Sections.size();
 807   uint8_t *Addr;
 808   const char *pData = nullptr;
 809
 810   // If this section contains any bits (i.e. isn't a virtual or bss section),
 811   // grab a reference to them.
 812   if (!IsVirtual && !IsZeroInit) {
 813     // In either case, set the location of the unrelocated section in memory,
 814     // since we still process relocations for it even if we're not applying them.
 815     if (Expected<StringRef> E = Section.getContents())
 816       data = *E;
 817     else
 818       return E.takeError();
 819     pData = data.data();
 820   }
 821
 822   // If there are any stubs then the section alignment needs to be at least as
 823   // high as stub alignment or padding calculations may by incorrect when the
 824   // section is remapped.
 825   if (StubBufSize != 0) {
 826     Alignment = std::max(Alignment, getStubAlignment());
 827     PaddingSize += getStubAlignment() - 1;
 828   }
 829
 830   // Some sections, such as debug info, don't need to be loaded for execution.
 831   // Process those only if explicitly requested.
 832   if (IsRequired || ProcessAllSections) {
 833     Allocate = DataSize + PaddingSize + StubBufSize;
 834     if (!Allocate)
 835       Allocate = 1;
 836     Addr = IsCode ? MemMgr.allocateCodeSection(Allocate, Alignment, SectionID,
 837                                                Name)
 838                   : MemMgr.allocateDataSection(Allocate, Alignment, SectionID,
 839                                                Name, IsReadOnly);
 840     if (!Addr)
 841       report_fatal_error("Unable to allocate section memory!");
 842
 843     // Zero-initialize or copy the data from the image
 844     if (IsZeroInit || IsVirtual)
 845       memset(Addr, 0, DataSize);
 846     else
 847       memcpy(Addr, pData, DataSize);
 848
 849     // Fill in any extra bytes we allocated for padding
 850     if (PaddingSize != 0) {
 851       memset(Addr + DataSize, 0, PaddingSize);
 852       // Update the DataSize variable to include padding.
 853       DataSize += PaddingSize;
 854
 855       // Align DataSize to stub alignment if we have any stubs (PaddingSize will
 856       // have been increased above to account for this).
 857       if (StubBufSize > 0)
 858         DataSize &= -(uint64_t)getStubAlignment();
 859     }
 860
 861     LLVM_DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: "
 862                       << Name << " obj addr: " << format("%p", pData)
 863                       << " new addr: " << format("%p", Addr) << " DataSize: "
 864                       << DataSize << " StubBufSize: " << StubBufSize
 865                       << " Allocate: " << Allocate << "\n");
 866   } else {
 867     // Even if we didn't load the section, we need to record an entry for it
 868     // to handle later processing (and by 'handle' I mean don't do anything
 869     // with these sections).
 870     Allocate = 0;
 871     Addr = nullptr;
 872     LLVM_DEBUG(
 873         dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
 874                << " obj addr: " << format("%p", data.data()) << " new addr: 0"
 875                << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
 876                << " Allocate: " << Allocate << "\n");
 877   }
 878
 879   Sections.push_back(
 880       SectionEntry(Name, Addr, DataSize, Allocate, (uintptr_t)pData));
 881
 882   // Debug info sections are linked as if their load address was zero
 883   if (!IsRequired)
 884     Sections.back().setLoadAddress(0);
 885
 886   return SectionID;
 887 }
 888
 889 Expected<unsigned>
 890 RuntimeDyldImpl::findOrEmitSection(const ObjectFile &Obj,
 891                                    const SectionRef &Section,
 892                                    bool IsCode,
 893                                    ObjSectionToIDMap &LocalSections) {
 894
 895   unsigned SectionID = 0;
 896   ObjSectionToIDMap::iterator i = LocalSections.find(Section);
 897   if (i != LocalSections.end())
 898     SectionID = i->second;
 899   else {
 900     if (auto SectionIDOrErr = emitSection(Obj, Section, IsCode))
 901       SectionID = *SectionIDOrErr;
 902     else
 903       return SectionIDOrErr.takeError();
 904     LocalSections[Section] = SectionID;
 905   }
 906   return SectionID;
 907 }
 908
 909 void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
 910                                               unsigned SectionID) {
 911   Relocations[SectionID].push_back(RE);
 912 }
 913
 914 void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
 915                                              StringRef SymbolName) {
 916   // Relocation by symbol.  If the symbol is found in the global symbol table,
 917   // create an appropriate section relocation.  Otherwise, add it to
 918   // ExternalSymbolRelocations.
 919   RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(SymbolName);
 920   if (Loc == GlobalSymbolTable.end()) {
 921     ExternalSymbolRelocations[SymbolName].push_back(RE);
 922   } else {
 923     // Copy the RE since we want to modify its addend.
 924     RelocationEntry RECopy = RE;
 925     const auto &SymInfo = Loc->second;
 926     RECopy.Addend += SymInfo.getOffset();
 927     Relocations[SymInfo.getSectionID()].push_back(RECopy);
 928   }
 929 }
 930
 931 uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr,
 932                                              unsigned AbiVariant) {
 933   if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be ||
 934       Arch == Triple::aarch64_32) {
 935     // This stub has to be able to access the full address space,
 936     // since symbol lookup won't necessarily find a handy, in-range,
 937     // PLT stub for functions which could be anywhere.
 938     // Stub can use ip0 (== x16) to calculate address
 939     writeBytesUnaligned(0xd2e00010, Addr,    4); // movz ip0, #:abs_g3:<addr>
 940     writeBytesUnaligned(0xf2c00010, Addr+4,  4); // movk ip0, #:abs_g2_nc:<addr>
 941     writeBytesUnaligned(0xf2a00010, Addr+8,  4); // movk ip0, #:abs_g1_nc:<addr>
 942     writeBytesUnaligned(0xf2800010, Addr+12, 4); // movk ip0, #:abs_g0_nc:<addr>
 943     writeBytesUnaligned(0xd61f0200, Addr+16, 4); // br ip0
 944
 945     return Addr;
 946   } else if (Arch == Triple::arm || Arch == Triple::armeb) {
 947     // TODO: There is only ARM far stub now. We should add the Thumb stub,
 948     // and stubs for branches Thumb - ARM and ARM - Thumb.
 949     writeBytesUnaligned(0xe51ff004, Addr, 4); // ldr pc, [pc, #-4]
 950     return Addr + 4;
 951   } else if (IsMipsO32ABI || IsMipsN32ABI) {
 952     // 0:   3c190000        lui     t9,%hi(addr).
 953     // 4:   27390000        addiu   t9,t9,%lo(addr).
 954     // 8:   03200008        jr      t9.
 955     // c:   00000000        nop.
 956     const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
 957     const unsigned NopInstr = 0x0;
 958     unsigned JrT9Instr = 0x03200008;
 959     if ((AbiVariant & ELF::EF_MIPS_ARCH) == ELF::EF_MIPS_ARCH_32R6 ||
 960         (AbiVariant & ELF::EF_MIPS_ARCH) == ELF::EF_MIPS_ARCH_64R6)
 961       JrT9Instr = 0x03200009;
 962
 963     writeBytesUnaligned(LuiT9Instr, Addr, 4);
 964     writeBytesUnaligned(AdduiT9Instr, Addr + 4, 4);
 965     writeBytesUnaligned(JrT9Instr, Addr + 8, 4);
 966     writeBytesUnaligned(NopInstr, Addr + 12, 4);
 967     return Addr;
 968   } else if (IsMipsN64ABI) {
 969     // 0:   3c190000        lui     t9,%highest(addr).
 970     // 4:   67390000        daddiu  t9,t9,%higher(addr).
 971     // 8:   0019CC38        dsll    t9,t9,16.
 972     // c:   67390000        daddiu  t9,t9,%hi(addr).
 973     // 10:  0019CC38        dsll    t9,t9,16.
 974     // 14:  67390000        daddiu  t9,t9,%lo(addr).
 975     // 18:  03200008        jr      t9.
 976     // 1c:  00000000        nop.
 977     const unsigned LuiT9Instr = 0x3c190000, DaddiuT9Instr = 0x67390000,
 978                    DsllT9Instr = 0x19CC38;
 979     const unsigned NopInstr = 0x0;
 980     unsigned JrT9Instr = 0x03200008;
 981     if ((AbiVariant & ELF::EF_MIPS_ARCH) == ELF::EF_MIPS_ARCH_64R6)
 982       JrT9Instr = 0x03200009;
 983
 984     writeBytesUnaligned(LuiT9Instr, Addr, 4);
 985     writeBytesUnaligned(DaddiuT9Instr, Addr + 4, 4);
 986     writeBytesUnaligned(DsllT9Instr, Addr + 8, 4);
 987     writeBytesUnaligned(DaddiuT9Instr, Addr + 12, 4);
 988     writeBytesUnaligned(DsllT9Instr, Addr + 16, 4);
 989     writeBytesUnaligned(DaddiuT9Instr, Addr + 20, 4);
 990     writeBytesUnaligned(JrT9Instr, Addr + 24, 4);
 991     writeBytesUnaligned(NopInstr, Addr + 28, 4);
 992     return Addr;
 993   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
 994     // Depending on which version of the ELF ABI is in use, we need to
 995     // generate one of two variants of the stub.  They both start with
 996     // the same sequence to load the target address into r12.
 997     writeInt32BE(Addr,    0x3D800000); // lis   r12, highest(addr)
 998     writeInt32BE(Addr+4,  0x618C0000); // ori   r12, higher(addr)
 999     writeInt32BE(Addr+8,  0x798C07C6); // sldi  r12, r12, 32
1000     writeInt32BE(Addr+12, 0x658C0000); // oris  r12, r12, h(addr)
1001     writeInt32BE(Addr+16, 0x618C0000); // ori   r12, r12, l(addr)
1002     if (AbiVariant == 2) {
1003       // PowerPC64 stub ELFv2 ABI: The address points to the function itself.
1004       // The address is already in r12 as required by the ABI.  Branch to it.
1005       writeInt32BE(Addr+20, 0xF8410018); // std   r2,  24(r1)
1006       writeInt32BE(Addr+24, 0x7D8903A6); // mtctr r12
1007       writeInt32BE(Addr+28, 0x4E800420); // bctr
1008     } else {
1009       // PowerPC64 stub ELFv1 ABI: The address points to a function descriptor.
1010       // Load the function address on r11 and sets it to control register. Also
1011       // loads the function TOC in r2 and environment pointer to r11.
1012       writeInt32BE(Addr+20, 0xF8410028); // std   r2,  40(r1)
1013       writeInt32BE(Addr+24, 0xE96C0000); // ld    r11, 0(r12)
1014       writeInt32BE(Addr+28, 0xE84C0008); // ld    r2,  0(r12)
1015       writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
1016       writeInt32BE(Addr+36, 0xE96C0010); // ld    r11, 16(r2)
1017       writeInt32BE(Addr+40, 0x4E800420); // bctr
1018     }
1019     return Addr;
1020   } else if (Arch == Triple::systemz) {
1021     writeInt16BE(Addr,    0xC418);     // lgrl %r1,.+8
1022     writeInt16BE(Addr+2,  0x0000);
1023     writeInt16BE(Addr+4,  0x0004);
1024     writeInt16BE(Addr+6,  0x07F1);     // brc 15,%r1
1025     // 8-byte address stored at Addr + 8
1026     return Addr;
1027   } else if (Arch == Triple::x86_64) {
1028     *Addr      = 0xFF; // jmp
1029     *(Addr+1)  = 0x25; // rip
1030     // 32-bit PC-relative address of the GOT entry will be stored at Addr+2
1031   } else if (Arch == Triple::x86) {
1032     *Addr      = 0xE9; // 32-bit pc-relative jump.
1033   }
1034   return Addr;
1035 }
1036
1037 // Assign an address to a symbol name and resolve all the relocations
1038 // associated with it.
1039 void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
1040                                              uint64_t Addr) {
1041   // The address to use for relocation resolution is not
1042   // the address of the local section buffer. We must be doing
1043   // a remote execution environment of some sort. Relocations can't
1044   // be applied until all the sections have been moved.  The client must
1045   // trigger this with a call to MCJIT::finalize() or
1046   // RuntimeDyld::resolveRelocations().
1047   //
1048   // Addr is a uint64_t because we can't assume the pointer width
1049   // of the target is the same as that of the host. Just use a generic
1050   // "big enough" type.
1051   LLVM_DEBUG(
1052       dbgs() << "Reassigning address for section " << SectionID << " ("
1053              << Sections[SectionID].getName() << "): "
1054              << format("0x%016" PRIx64, Sections[SectionID].getLoadAddress())
1055              << " -> " << format("0x%016" PRIx64, Addr) << "\n");
1056   Sections[SectionID].setLoadAddress(Addr);
1057 }
1058
1059 void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
1060                                             uint64_t Value) {
1061   for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1062     const RelocationEntry &RE = Relocs[i];
1063     // Ignore relocations for sections that were not loaded
1064     if (Sections[RE.SectionID].getAddress() == nullptr)
1065       continue;
1066     resolveRelocation(RE, Value);
1067   }
1068 }
1069
1070 void RuntimeDyldImpl::applyExternalSymbolRelocations(
1071     const StringMap<JITEvaluatedSymbol> ExternalSymbolMap) {
1072   while (!ExternalSymbolRelocations.empty()) {
1073
1074     StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin();
1075
1076     StringRef Name = i->first();
1077     if (Name.size() == 0) {
1078       // This is an absolute symbol, use an address of zero.
1079       LLVM_DEBUG(dbgs() << "Resolving absolute relocations."
1080                         << "\n");
1081       RelocationList &Relocs = i->second;
1082       resolveRelocationList(Relocs, 0);
1083     } else {
1084       uint64_t Addr = 0;
1085       JITSymbolFlags Flags;
1086       RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(Name);
1087       if (Loc == GlobalSymbolTable.end()) {
1088         auto RRI = ExternalSymbolMap.find(Name);
1089         assert(RRI != ExternalSymbolMap.end() && "No result for symbol");
1090         Addr = RRI->second.getAddress();
1091         Flags = RRI->second.getFlags();
1092         // The call to getSymbolAddress may have caused additional modules to
1093         // be loaded, which may have added new entries to the
1094         // ExternalSymbolRelocations map.  Consquently, we need to update our
1095         // iterator.  This is also why retrieval of the relocation list
1096         // associated with this symbol is deferred until below this point.
1097         // New entries may have been added to the relocation list.
1098         i = ExternalSymbolRelocations.find(Name);
1099       } else {
1100         // We found the symbol in our global table.  It was probably in a
1101         // Module that we loaded previously.
1102         const auto &SymInfo = Loc->second;
1103         Addr = getSectionLoadAddress(SymInfo.getSectionID()) +
1104                SymInfo.getOffset();
1105         Flags = SymInfo.getFlags();
1106       }
1107
1108       // FIXME: Implement error handling that doesn't kill the host program!
1109       if (!Addr)
1110         report_fatal_error("Program used external function '" + Name +
1111                            "' which could not be resolved!");
1112
1113       // If Resolver returned UINT64_MAX, the client wants to handle this symbol
1114       // manually and we shouldn't resolve its relocations.
1115       if (Addr != UINT64_MAX) {
1116
1117         // Tweak the address based on the symbol flags if necessary.
1118         // For example, this is used by RuntimeDyldMachOARM to toggle the low bit
1119         // if the target symbol is Thumb.
1120         Addr = modifyAddressBasedOnFlags(Addr, Flags);
1121
1122         LLVM_DEBUG(dbgs() << "Resolving relocations Name: " << Name << "\t"
1123                           << format("0x%lx", Addr) << "\n");
1124         // This list may have been updated when we called getSymbolAddress, so
1125         // don't change this code to get the list earlier.
1126         RelocationList &Relocs = i->second;
1127         resolveRelocationList(Relocs, Addr);
1128       }
1129     }
1130
1131     ExternalSymbolRelocations.erase(i);
1132   }
1133 }
1134
1135 Error RuntimeDyldImpl::resolveExternalSymbols() {
1136   StringMap<JITEvaluatedSymbol> ExternalSymbolMap;
1137
1138   // Resolution can trigger emission of more symbols, so iterate until
1139   // we've resolved *everything*.
1140   {
1141     JITSymbolResolver::LookupSet ResolvedSymbols;
1142
1143     while (true) {
1144       JITSymbolResolver::LookupSet NewSymbols;
1145
1146       for (auto &RelocKV : ExternalSymbolRelocations) {
1147         StringRef Name = RelocKV.first();
1148         if (!Name.empty() && !GlobalSymbolTable.count(Name) &&
1149             !ResolvedSymbols.count(Name))
1150           NewSymbols.insert(Name);
1151       }
1152
1153       if (NewSymbols.empty())
1154         break;
1155
1156 #ifdef _MSC_VER
1157       using ExpectedLookupResult =
1158           MSVCPExpected<JITSymbolResolver::LookupResult>;
1159 #else
1160       using ExpectedLookupResult = Expected<JITSymbolResolver::LookupResult>;
1161 #endif
1162
1163       auto NewSymbolsP = std::make_shared<std::promise<ExpectedLookupResult>>();
1164       auto NewSymbolsF = NewSymbolsP->get_future();
1165       Resolver.lookup(NewSymbols,
1166                       [=](Expected<JITSymbolResolver::LookupResult> Result) {
1167                         NewSymbolsP->set_value(std::move(Result));
1168                       });
1169
1170       auto NewResolverResults = NewSymbolsF.get();
1171
1172       if (!NewResolverResults)
1173         return NewResolverResults.takeError();
1174
1175       assert(NewResolverResults->size() == NewSymbols.size() &&
1176              "Should have errored on unresolved symbols");
1177
1178       for (auto &RRKV : *NewResolverResults) {
1179         assert(!ResolvedSymbols.count(RRKV.first) && "Redundant resolution?");
1180         ExternalSymbolMap.insert(RRKV);
1181         ResolvedSymbols.insert(RRKV.first);
1182       }
1183     }
1184   }
1185
1186   applyExternalSymbolRelocations(ExternalSymbolMap);
1187
1188   return Error::success();
1189 }
1190
1191 void RuntimeDyldImpl::finalizeAsync(
1192     std::unique_ptr<RuntimeDyldImpl> This,
1193     unique_function<void(Error)> OnEmitted,
1194     std::unique_ptr<MemoryBuffer> UnderlyingBuffer) {
1195
1196   auto SharedThis = std::shared_ptr<RuntimeDyldImpl>(std::move(This));
1197   auto PostResolveContinuation =
1198       [SharedThis, OnEmitted = std::move(OnEmitted),
1199        UnderlyingBuffer = std::move(UnderlyingBuffer)](
1200           Expected<JITSymbolResolver::LookupResult> Result) mutable {
1201         if (!Result) {
1202           OnEmitted(Result.takeError());
1203           return;
1204         }
1205
1206         /// Copy the result into a StringMap, where the keys are held by value.
1207         StringMap<JITEvaluatedSymbol> Resolved;
1208         for (auto &KV : *Result)
1209           Resolved[KV.first] = KV.second;
1210
1211         SharedThis->applyExternalSymbolRelocations(Resolved);
1212         SharedThis->resolveLocalRelocations();
1213         SharedThis->registerEHFrames();
1214         std::string ErrMsg;
1215         if (SharedThis->MemMgr.finalizeMemory(&ErrMsg))
1216           OnEmitted(make_error<StringError>(std::move(ErrMsg),
1217                                             inconvertibleErrorCode()));
1218         else
1219           OnEmitted(Error::success());
1220       };
1221
1222   JITSymbolResolver::LookupSet Symbols;
1223
1224   for (auto &RelocKV : SharedThis->ExternalSymbolRelocations) {
1225     StringRef Name = RelocKV.first();
1226     assert(!Name.empty() && "Symbol has no name?");
1227     assert(!SharedThis->GlobalSymbolTable.count(Name) &&
1228            "Name already processed. RuntimeDyld instances can not be re-used "
1229            "when finalizing with finalizeAsync.");
1230     Symbols.insert(Name);
1231   }
1232
1233   if (!Symbols.empty()) {
1234     SharedThis->Resolver.lookup(Symbols, std::move(PostResolveContinuation));
1235   } else
1236     PostResolveContinuation(std::map<StringRef, JITEvaluatedSymbol>());
1237 }
1238
1239 //===----------------------------------------------------------------------===//
1240 // RuntimeDyld class implementation
1241
1242 uint64_t RuntimeDyld::LoadedObjectInfo::getSectionLoadAddress(
1243                                           const object::SectionRef &Sec) const {
1244
1245   auto I = ObjSecToIDMap.find(Sec);
1246   if (I != ObjSecToIDMap.end())
1247     return RTDyld.Sections[I->second].getLoadAddress();
1248
1249   return 0;
1250 }
1251
1252 void RuntimeDyld::MemoryManager::anchor() {}
1253 void JITSymbolResolver::anchor() {}
1254 void LegacyJITSymbolResolver::anchor() {}
1255
1256 RuntimeDyld::RuntimeDyld(RuntimeDyld::MemoryManager &MemMgr,
1257                          JITSymbolResolver &Resolver)
1258     : MemMgr(MemMgr), Resolver(Resolver) {
1259   // FIXME: There's a potential issue lurking here if a single instance of
1260   // RuntimeDyld is used to load multiple objects.  The current implementation
1261   // associates a single memory manager with a RuntimeDyld instance.  Even
1262   // though the public class spawns a new 'impl' instance for each load,
1263   // they share a single memory manager.  This can become a problem when page
1264   // permissions are applied.
1265   Dyld = nullptr;
1266   ProcessAllSections = false;
1267 }
1268
1269 RuntimeDyld::~RuntimeDyld() {}
1270
1271 static std::unique_ptr<RuntimeDyldCOFF>
1272 createRuntimeDyldCOFF(
1273                      Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
1274                      JITSymbolResolver &Resolver, bool ProcessAllSections,
1275                      RuntimeDyld::NotifyStubEmittedFunction NotifyStubEmitted) {
1276   std::unique_ptr<RuntimeDyldCOFF> Dyld =
1277     RuntimeDyldCOFF::create(Arch, MM, Resolver);
1278   Dyld->setProcessAllSections(ProcessAllSections);
1279   Dyld->setNotifyStubEmitted(std::move(NotifyStubEmitted));
1280   return Dyld;
1281 }
1282
1283 static std::unique_ptr<RuntimeDyldELF>
1284 createRuntimeDyldELF(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
1285                      JITSymbolResolver &Resolver, bool ProcessAllSections,
1286                      RuntimeDyld::NotifyStubEmittedFunction NotifyStubEmitted) {
1287   std::unique_ptr<RuntimeDyldELF> Dyld =
1288       RuntimeDyldELF::create(Arch, MM, Resolver);
1289   Dyld->setProcessAllSections(ProcessAllSections);
1290   Dyld->setNotifyStubEmitted(std::move(NotifyStubEmitted));
1291   return Dyld;
1292 }
1293
1294 static std::unique_ptr<RuntimeDyldMachO>
1295 createRuntimeDyldMachO(
1296                      Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
1297                      JITSymbolResolver &Resolver,
1298                      bool ProcessAllSections,
1299                      RuntimeDyld::NotifyStubEmittedFunction NotifyStubEmitted) {
1300   std::unique_ptr<RuntimeDyldMachO> Dyld =
1301     RuntimeDyldMachO::create(Arch, MM, Resolver);
1302   Dyld->setProcessAllSections(ProcessAllSections);
1303   Dyld->setNotifyStubEmitted(std::move(NotifyStubEmitted));
1304   return Dyld;
1305 }
1306
1307 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
1308 RuntimeDyld::loadObject(const ObjectFile &Obj) {
1309   if (!Dyld) {
1310     if (Obj.isELF())
1311       Dyld =
1312           createRuntimeDyldELF(static_cast<Triple::ArchType>(Obj.getArch()),
1313                                MemMgr, Resolver, ProcessAllSections,
1314                                std::move(NotifyStubEmitted));
1315     else if (Obj.isMachO())
1316       Dyld = createRuntimeDyldMachO(
1317                static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
1318                ProcessAllSections, std::move(NotifyStubEmitted));
1319     else if (Obj.isCOFF())
1320       Dyld = createRuntimeDyldCOFF(
1321                static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
1322                ProcessAllSections, std::move(NotifyStubEmitted));
1323     else
1324       report_fatal_error("Incompatible object format!");
1325   }
1326
1327   if (!Dyld->isCompatibleFile(Obj))
1328     report_fatal_error("Incompatible object format!");
1329
1330   auto LoadedObjInfo = Dyld->loadObject(Obj);
1331   MemMgr.notifyObjectLoaded(*this, Obj);
1332   return LoadedObjInfo;
1333 }
1334
1335 void *RuntimeDyld::getSymbolLocalAddress(StringRef Name) const {
1336   if (!Dyld)
1337     return nullptr;
1338   return Dyld->getSymbolLocalAddress(Name);
1339 }
1340
1341 unsigned RuntimeDyld::getSymbolSectionID(StringRef Name) const {
1342   assert(Dyld && "No RuntimeDyld instance attached");
1343   return Dyld->getSymbolSectionID(Name);
1344 }
1345
1346 JITEvaluatedSymbol RuntimeDyld::getSymbol(StringRef Name) const {
1347   if (!Dyld)
1348     return nullptr;
1349   return Dyld->getSymbol(Name);
1350 }
1351
1352 std::map<StringRef, JITEvaluatedSymbol> RuntimeDyld::getSymbolTable() const {
1353   if (!Dyld)
1354     return std::map<StringRef, JITEvaluatedSymbol>();
1355   return Dyld->getSymbolTable();
1356 }
1357
1358 void RuntimeDyld::resolveRelocations() { Dyld->resolveRelocations(); }
1359
1360 void RuntimeDyld::reassignSectionAddress(unsigned SectionID, uint64_t Addr) {
1361   Dyld->reassignSectionAddress(SectionID, Addr);
1362 }
1363
1364 void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
1365                                     uint64_t TargetAddress) {
1366   Dyld->mapSectionAddress(LocalAddress, TargetAddress);
1367 }
1368
1369 bool RuntimeDyld::hasError() { return Dyld->hasError(); }
1370
1371 StringRef RuntimeDyld::getErrorString() { return Dyld->getErrorString(); }
1372
1373 void RuntimeDyld::finalizeWithMemoryManagerLocking() {
1374   bool MemoryFinalizationLocked = MemMgr.FinalizationLocked;
1375   MemMgr.FinalizationLocked = true;
1376   resolveRelocations();
1377   registerEHFrames();
1378   if (!MemoryFinalizationLocked) {
1379     MemMgr.finalizeMemory();
1380     MemMgr.FinalizationLocked = false;
1381   }
1382 }
1383
1384 StringRef RuntimeDyld::getSectionContent(unsigned SectionID) const {
1385   assert(Dyld && "No Dyld instance attached");
1386   return Dyld->getSectionContent(SectionID);
1387 }
1388
1389 uint64_t RuntimeDyld::getSectionLoadAddress(unsigned SectionID) const {
1390   assert(Dyld && "No Dyld instance attached");
1391   return Dyld->getSectionLoadAddress(SectionID);
1392 }
1393
1394 void RuntimeDyld::registerEHFrames() {
1395   if (Dyld)
1396     Dyld->registerEHFrames();
1397 }
1398
1399 void RuntimeDyld::deregisterEHFrames() {
1400   if (Dyld)
1401     Dyld->deregisterEHFrames();
1402 }
1403 // FIXME: Kill this with fire once we have a new JIT linker: this is only here
1404 // so that we can re-use RuntimeDyld's implementation without twisting the
1405 // interface any further for ORC's purposes.
1406 void jitLinkForORC(object::ObjectFile &Obj,
1407                    std::unique_ptr<MemoryBuffer> UnderlyingBuffer,
1408                    RuntimeDyld::MemoryManager &MemMgr,
1409                    JITSymbolResolver &Resolver, bool ProcessAllSections,
1410                    unique_function<Error(
1411                        std::unique_ptr<RuntimeDyld::LoadedObjectInfo> LoadedObj,
1412                        std::map<StringRef, JITEvaluatedSymbol>)>
1413                        OnLoaded,
1414                    unique_function<void(Error)> OnEmitted) {
1415
1416   RuntimeDyld RTDyld(MemMgr, Resolver);
1417   RTDyld.setProcessAllSections(ProcessAllSections);
1418
1419   auto Info = RTDyld.loadObject(Obj);
1420
1421   if (RTDyld.hasError()) {
1422     OnEmitted(make_error<StringError>(RTDyld.getErrorString(),
1423                                       inconvertibleErrorCode()));
1424     return;
1425   }
1426
1427   if (auto Err = OnLoaded(std::move(Info), RTDyld.getSymbolTable()))
1428     OnEmitted(std::move(Err));
1429
1430   RuntimeDyldImpl::finalizeAsync(std::move(RTDyld.Dyld), std::move(OnEmitted),
1431                                  std::move(UnderlyingBuffer));
1432 }
1433
1434 } // end namespace llvm