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#include "llvm/ExecutionEngine/RuntimeDyld.h"
15#include "RuntimeDyldCheckerImpl.h"
16#include "RuntimeDyldCOFF.h"
17#include "RuntimeDyldELF.h"
18#include "RuntimeDyldImpl.h"
19#include "RuntimeDyldMachO.h"
20#include "llvm/Object/ELFObjectFile.h"
21#include "llvm/Object/COFF.h"
22#include "llvm/Support/MathExtras.h"
23#include "llvm/Support/MutexGuard.h"
24
25using namespace llvm;
26using namespace llvm::object;
27
28#define DEBUG_TYPE "dyld"
29
30// Empty out-of-line virtual destructor as the key function.
31RuntimeDyldImpl::~RuntimeDyldImpl() {}
32
33// Pin LoadedObjectInfo's vtables to this file.
34void RuntimeDyld::LoadedObjectInfo::anchor() {}
35
36namespace llvm {
37
38void RuntimeDyldImpl::registerEHFrames() {}
39
40void RuntimeDyldImpl::deregisterEHFrames() {}
41
42#ifndef NDEBUG
43static void dumpSectionMemory(const SectionEntry &S, StringRef State) {
44  dbgs() << "----- Contents of section " << S.Name << " " << State << " -----";
45
46  if (S.Address == nullptr) {
47    dbgs() << "\n          <section not emitted>\n";
48    return;
49  }
50
51  const unsigned ColsPerRow = 16;
52
53  uint8_t *DataAddr = S.Address;
54  uint64_t LoadAddr = S.LoadAddress;
55
56  unsigned StartPadding = LoadAddr & (ColsPerRow - 1);
57  unsigned BytesRemaining = S.Size;
58
59  if (StartPadding) {
60    dbgs() << "\n" << format("0x%016" PRIx64,
61                             LoadAddr & ~(uint64_t)(ColsPerRow - 1)) << ":";
62    while (StartPadding--)
63      dbgs() << "   ";
64  }
65
66  while (BytesRemaining > 0) {
67    if ((LoadAddr & (ColsPerRow - 1)) == 0)
68      dbgs() << "\n" << format("0x%016" PRIx64, LoadAddr) << ":";
69
70    dbgs() << " " << format("%02x", *DataAddr);
71
72    ++DataAddr;
73    ++LoadAddr;
74    --BytesRemaining;
75  }
76
77  dbgs() << "\n";
78}
79#endif
80
81// Resolve the relocations for all symbols we currently know about.
82void RuntimeDyldImpl::resolveRelocations() {
83  MutexGuard locked(lock);
84
85  // First, resolve relocations associated with external symbols.
86  resolveExternalSymbols();
87
88  // Just iterate over the sections we have and resolve all the relocations
89  // in them. Gross overkill, but it gets the job done.
90  for (int i = 0, e = Sections.size(); i != e; ++i) {
91    // The Section here (Sections[i]) refers to the section in which the
92    // symbol for the relocation is located.  The SectionID in the relocation
93    // entry provides the section to which the relocation will be applied.
94    uint64_t Addr = Sections[i].LoadAddress;
95    DEBUG(dbgs() << "Resolving relocations Section #" << i << "\t"
96                 << format("%p", (uintptr_t)Addr) << "\n");
97    DEBUG(dumpSectionMemory(Sections[i], "before relocations"));
98    resolveRelocationList(Relocations[i], Addr);
99    DEBUG(dumpSectionMemory(Sections[i], "after relocations"));
100    Relocations.erase(i);
101  }
102}
103
104void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
105                                        uint64_t TargetAddress) {
106  MutexGuard locked(lock);
107  for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
108    if (Sections[i].Address == LocalAddress) {
109      reassignSectionAddress(i, TargetAddress);
110      return;
111    }
112  }
113  llvm_unreachable("Attempting to remap address of unknown section!");
114}
115
116static std::error_code getOffset(const SymbolRef &Sym, uint64_t &Result) {
117  uint64_t Address;
118  if (std::error_code EC = Sym.getAddress(Address))
119    return EC;
120
121  if (Address == UnknownAddressOrSize) {
122    Result = UnknownAddressOrSize;
123    return object_error::success;
124  }
125
126  const ObjectFile *Obj = Sym.getObject();
127  section_iterator SecI(Obj->section_begin());
128  if (std::error_code EC = Sym.getSection(SecI))
129    return EC;
130
131  if (SecI == Obj->section_end()) {
132    Result = UnknownAddressOrSize;
133    return object_error::success;
134  }
135
136  uint64_t SectionAddress = SecI->getAddress();
137  Result = Address - SectionAddress;
138  return object_error::success;
139}
140
141std::pair<unsigned, unsigned>
142RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
143  MutexGuard locked(lock);
144
145  // Grab the first Section ID. We'll use this later to construct the underlying
146  // range for the returned LoadedObjectInfo.
147  unsigned SectionsAddedBeginIdx = Sections.size();
148
149  // Save information about our target
150  Arch = (Triple::ArchType)Obj.getArch();
151  IsTargetLittleEndian = Obj.isLittleEndian();
152
153  // Compute the memory size required to load all sections to be loaded
154  // and pass this information to the memory manager
155  if (MemMgr.needsToReserveAllocationSpace()) {
156    uint64_t CodeSize = 0, DataSizeRO = 0, DataSizeRW = 0;
157    computeTotalAllocSize(Obj, CodeSize, DataSizeRO, DataSizeRW);
158    MemMgr.reserveAllocationSpace(CodeSize, DataSizeRO, DataSizeRW);
159  }
160
161  // Used sections from the object file
162  ObjSectionToIDMap LocalSections;
163
164  // Common symbols requiring allocation, with their sizes and alignments
165  CommonSymbolList CommonSymbols;
166
167  // Parse symbols
168  DEBUG(dbgs() << "Parse symbols:\n");
169  for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
170       ++I) {
171    uint32_t Flags = I->getFlags();
172
173    bool IsCommon = Flags & SymbolRef::SF_Common;
174    if (IsCommon)
175      CommonSymbols.push_back(*I);
176    else {
177      object::SymbolRef::Type SymType;
178      Check(I->getType(SymType));
179
180      if (SymType == object::SymbolRef::ST_Function ||
181          SymType == object::SymbolRef::ST_Data ||
182          SymType == object::SymbolRef::ST_Unknown) {
183
184        StringRef Name;
185        uint64_t SectOffset;
186        Check(I->getName(Name));
187        Check(getOffset(*I, SectOffset));
188        section_iterator SI = Obj.section_end();
189        Check(I->getSection(SI));
190        if (SI == Obj.section_end())
191          continue;
192        StringRef SectionData;
193        Check(SI->getContents(SectionData));
194        bool IsCode = SI->isText();
195        unsigned SectionID =
196            findOrEmitSection(Obj, *SI, IsCode, LocalSections);
197        DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name
198                     << " SID: " << SectionID << " Offset: "
199                     << format("%p", (uintptr_t)SectOffset)
200                     << " flags: " << Flags << "\n");
201        JITSymbolFlags RTDyldSymFlags = JITSymbolFlags::None;
202        if (Flags & SymbolRef::SF_Weak)
203          RTDyldSymFlags |= JITSymbolFlags::Weak;
204        if (Flags & SymbolRef::SF_Exported)
205          RTDyldSymFlags |= JITSymbolFlags::Exported;
206        GlobalSymbolTable[Name] =
207          SymbolTableEntry(SectionID, SectOffset, RTDyldSymFlags);
208      }
209    }
210  }
211
212  // Allocate common symbols
213  emitCommonSymbols(Obj, CommonSymbols);
214
215  // Parse and process relocations
216  DEBUG(dbgs() << "Parse relocations:\n");
217  for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
218       SI != SE; ++SI) {
219    unsigned SectionID = 0;
220    StubMap Stubs;
221    section_iterator RelocatedSection = SI->getRelocatedSection();
222
223    if (RelocatedSection == SE)
224      continue;
225
226    relocation_iterator I = SI->relocation_begin();
227    relocation_iterator E = SI->relocation_end();
228
229    if (I == E && !ProcessAllSections)
230      continue;
231
232    bool IsCode = RelocatedSection->isText();
233    SectionID =
234        findOrEmitSection(Obj, *RelocatedSection, IsCode, LocalSections);
235    DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
236
237    for (; I != E;)
238      I = processRelocationRef(SectionID, I, Obj, LocalSections, Stubs);
239
240    // If there is an attached checker, notify it about the stubs for this
241    // section so that they can be verified.
242    if (Checker)
243      Checker->registerStubMap(Obj.getFileName(), SectionID, Stubs);
244  }
245
246  // Give the subclasses a chance to tie-up any loose ends.
247  finalizeLoad(Obj, LocalSections);
248
249  unsigned SectionsAddedEndIdx = Sections.size();
250
251  return std::make_pair(SectionsAddedBeginIdx, SectionsAddedEndIdx);
252}
253
254// A helper method for computeTotalAllocSize.
255// Computes the memory size required to allocate sections with the given sizes,
256// assuming that all sections are allocated with the given alignment
257static uint64_t
258computeAllocationSizeForSections(std::vector<uint64_t> &SectionSizes,
259                                 uint64_t Alignment) {
260  uint64_t TotalSize = 0;
261  for (size_t Idx = 0, Cnt = SectionSizes.size(); Idx < Cnt; Idx++) {
262    uint64_t AlignedSize =
263        (SectionSizes[Idx] + Alignment - 1) / Alignment * Alignment;
264    TotalSize += AlignedSize;
265  }
266  return TotalSize;
267}
268
269static bool isRequiredForExecution(const SectionRef &Section) {
270  const ObjectFile *Obj = Section.getObject();
271  if (auto *ELFObj = dyn_cast<object::ELFObjectFileBase>(Obj))
272    return ELFObj->getSectionFlags(Section) & ELF::SHF_ALLOC;
273  if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj)) {
274    const coff_section *CoffSection = COFFObj->getCOFFSection(Section);
275    // Avoid loading zero-sized COFF sections.
276    // In PE files, VirtualSize gives the section size, and SizeOfRawData
277    // may be zero for sections with content. In Obj files, SizeOfRawData
278    // gives the section size, and VirtualSize is always zero. Hence
279    // the need to check for both cases below.
280    bool HasContent = (CoffSection->VirtualSize > 0)
281      || (CoffSection->SizeOfRawData > 0);
282    bool IsDiscardable = CoffSection->Characteristics &
283      (COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_LNK_INFO);
284    return HasContent && !IsDiscardable;
285  }
286
287  assert(isa<MachOObjectFile>(Obj));
288  return true;
289 }
290
291static bool isReadOnlyData(const SectionRef &Section) {
292  const ObjectFile *Obj = Section.getObject();
293  if (auto *ELFObj = dyn_cast<object::ELFObjectFileBase>(Obj))
294    return !(ELFObj->getSectionFlags(Section) &
295             (ELF::SHF_WRITE | ELF::SHF_EXECINSTR));
296  if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
297    return ((COFFObj->getCOFFSection(Section)->Characteristics &
298             (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
299             | COFF::IMAGE_SCN_MEM_READ
300             | COFF::IMAGE_SCN_MEM_WRITE))
301             ==
302             (COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
303             | COFF::IMAGE_SCN_MEM_READ));
304
305  assert(isa<MachOObjectFile>(Obj));
306  return false;
307}
308
309static bool isZeroInit(const SectionRef &Section) {
310  const ObjectFile *Obj = Section.getObject();
311  if (auto *ELFObj = dyn_cast<object::ELFObjectFileBase>(Obj))
312    return ELFObj->getSectionType(Section) == ELF::SHT_NOBITS;
313  if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj))
314    return COFFObj->getCOFFSection(Section)->Characteristics &
315            COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA;
316
317  auto *MachO = cast<MachOObjectFile>(Obj);
318  unsigned SectionType = MachO->getSectionType(Section);
319  return SectionType == MachO::S_ZEROFILL ||
320         SectionType == MachO::S_GB_ZEROFILL;
321}
322
323// Compute an upper bound of the memory size that is required to load all
324// sections
325void RuntimeDyldImpl::computeTotalAllocSize(const ObjectFile &Obj,
326                                            uint64_t &CodeSize,
327                                            uint64_t &DataSizeRO,
328                                            uint64_t &DataSizeRW) {
329  // Compute the size of all sections required for execution
330  std::vector<uint64_t> CodeSectionSizes;
331  std::vector<uint64_t> ROSectionSizes;
332  std::vector<uint64_t> RWSectionSizes;
333  uint64_t MaxAlignment = sizeof(void *);
334
335  // Collect sizes of all sections to be loaded;
336  // also determine the max alignment of all sections
337  for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
338       SI != SE; ++SI) {
339    const SectionRef &Section = *SI;
340
341    bool IsRequired = isRequiredForExecution(Section);
342
343    // Consider only the sections that are required to be loaded for execution
344    if (IsRequired) {
345      StringRef Name;
346      uint64_t DataSize = Section.getSize();
347      uint64_t Alignment64 = Section.getAlignment();
348      bool IsCode = Section.isText();
349      bool IsReadOnly = isReadOnlyData(Section);
350      Check(Section.getName(Name));
351      unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
352
353      uint64_t StubBufSize = computeSectionStubBufSize(Obj, Section);
354      uint64_t SectionSize = DataSize + StubBufSize;
355
356      // The .eh_frame section (at least on Linux) needs an extra four bytes
357      // padded
358      // with zeroes added at the end.  For MachO objects, this section has a
359      // slightly different name, so this won't have any effect for MachO
360      // objects.
361      if (Name == ".eh_frame")
362        SectionSize += 4;
363
364      if (!SectionSize)
365        SectionSize = 1;
366
367      if (IsCode) {
368        CodeSectionSizes.push_back(SectionSize);
369      } else if (IsReadOnly) {
370        ROSectionSizes.push_back(SectionSize);
371      } else {
372        RWSectionSizes.push_back(SectionSize);
373      }
374
375      // update the max alignment
376      if (Alignment > MaxAlignment) {
377        MaxAlignment = Alignment;
378      }
379    }
380  }
381
382  // Compute the size of all common symbols
383  uint64_t CommonSize = 0;
384  for (symbol_iterator I = Obj.symbol_begin(), E = Obj.symbol_end(); I != E;
385       ++I) {
386    uint32_t Flags = I->getFlags();
387    if (Flags & SymbolRef::SF_Common) {
388      // Add the common symbols to a list.  We'll allocate them all below.
389      uint64_t Size = 0;
390      Check(I->getSize(Size));
391      CommonSize += Size;
392    }
393  }
394  if (CommonSize != 0) {
395    RWSectionSizes.push_back(CommonSize);
396  }
397
398  // Compute the required allocation space for each different type of sections
399  // (code, read-only data, read-write data) assuming that all sections are
400  // allocated with the max alignment. Note that we cannot compute with the
401  // individual alignments of the sections, because then the required size
402  // depends on the order, in which the sections are allocated.
403  CodeSize = computeAllocationSizeForSections(CodeSectionSizes, MaxAlignment);
404  DataSizeRO = computeAllocationSizeForSections(ROSectionSizes, MaxAlignment);
405  DataSizeRW = computeAllocationSizeForSections(RWSectionSizes, MaxAlignment);
406}
407
408// compute stub buffer size for the given section
409unsigned RuntimeDyldImpl::computeSectionStubBufSize(const ObjectFile &Obj,
410                                                    const SectionRef &Section) {
411  unsigned StubSize = getMaxStubSize();
412  if (StubSize == 0) {
413    return 0;
414  }
415  // FIXME: this is an inefficient way to handle this. We should computed the
416  // necessary section allocation size in loadObject by walking all the sections
417  // once.
418  unsigned StubBufSize = 0;
419  for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
420       SI != SE; ++SI) {
421    section_iterator RelSecI = SI->getRelocatedSection();
422    if (!(RelSecI == Section))
423      continue;
424
425    for (const RelocationRef &Reloc : SI->relocations()) {
426      (void)Reloc;
427      StubBufSize += StubSize;
428    }
429  }
430
431  // Get section data size and alignment
432  uint64_t DataSize = Section.getSize();
433  uint64_t Alignment64 = Section.getAlignment();
434
435  // Add stubbuf size alignment
436  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
437  unsigned StubAlignment = getStubAlignment();
438  unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
439  if (StubAlignment > EndAlignment)
440    StubBufSize += StubAlignment - EndAlignment;
441  return StubBufSize;
442}
443
444uint64_t RuntimeDyldImpl::readBytesUnaligned(uint8_t *Src,
445                                             unsigned Size) const {
446  uint64_t Result = 0;
447  if (IsTargetLittleEndian) {
448    Src += Size - 1;
449    while (Size--)
450      Result = (Result << 8) | *Src--;
451  } else
452    while (Size--)
453      Result = (Result << 8) | *Src++;
454
455  return Result;
456}
457
458void RuntimeDyldImpl::writeBytesUnaligned(uint64_t Value, uint8_t *Dst,
459                                          unsigned Size) const {
460  if (IsTargetLittleEndian) {
461    while (Size--) {
462      *Dst++ = Value & 0xFF;
463      Value >>= 8;
464    }
465  } else {
466    Dst += Size - 1;
467    while (Size--) {
468      *Dst-- = Value & 0xFF;
469      Value >>= 8;
470    }
471  }
472}
473
474void RuntimeDyldImpl::emitCommonSymbols(const ObjectFile &Obj,
475                                        CommonSymbolList &CommonSymbols) {
476  if (CommonSymbols.empty())
477    return;
478
479  uint64_t CommonSize = 0;
480  CommonSymbolList SymbolsToAllocate;
481
482  DEBUG(dbgs() << "Processing common symbols...\n");
483
484  for (const auto &Sym : CommonSymbols) {
485    StringRef Name;
486    Check(Sym.getName(Name));
487
488    // Skip common symbols already elsewhere.
489    if (GlobalSymbolTable.count(Name) ||
490        Resolver.findSymbolInLogicalDylib(Name)) {
491      DEBUG(dbgs() << "\tSkipping already emitted common symbol '" << Name
492                   << "'\n");
493      continue;
494    }
495
496    uint32_t Align = 0;
497    uint64_t Size = 0;
498    Check(Sym.getAlignment(Align));
499    Check(Sym.getSize(Size));
500
501    CommonSize += Align + Size;
502    SymbolsToAllocate.push_back(Sym);
503  }
504
505  // Allocate memory for the section
506  unsigned SectionID = Sections.size();
507  uint8_t *Addr = MemMgr.allocateDataSection(CommonSize, sizeof(void *),
508                                             SectionID, StringRef(), false);
509  if (!Addr)
510    report_fatal_error("Unable to allocate memory for common symbols!");
511  uint64_t Offset = 0;
512  Sections.push_back(SectionEntry("<common symbols>", Addr, CommonSize, 0));
513  memset(Addr, 0, CommonSize);
514
515  DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID << " new addr: "
516               << format("%p", Addr) << " DataSize: " << CommonSize << "\n");
517
518  // Assign the address of each symbol
519  for (auto &Sym : SymbolsToAllocate) {
520    uint32_t Align;
521    uint64_t Size;
522    StringRef Name;
523    Check(Sym.getAlignment(Align));
524    Check(Sym.getSize(Size));
525    Check(Sym.getName(Name));
526    if (Align) {
527      // This symbol has an alignment requirement.
528      uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
529      Addr += AlignOffset;
530      Offset += AlignOffset;
531    }
532    uint32_t Flags = Sym.getFlags();
533    JITSymbolFlags RTDyldSymFlags = JITSymbolFlags::None;
534    if (Flags & SymbolRef::SF_Weak)
535      RTDyldSymFlags |= JITSymbolFlags::Weak;
536    if (Flags & SymbolRef::SF_Exported)
537      RTDyldSymFlags |= JITSymbolFlags::Exported;
538    DEBUG(dbgs() << "Allocating common symbol " << Name << " address "
539                 << format("%p", Addr) << "\n");
540    GlobalSymbolTable[Name] =
541      SymbolTableEntry(SectionID, Offset, RTDyldSymFlags);
542    Offset += Size;
543    Addr += Size;
544  }
545}
546
547unsigned RuntimeDyldImpl::emitSection(const ObjectFile &Obj,
548                                      const SectionRef &Section, bool IsCode) {
549
550  StringRef data;
551  uint64_t Alignment64 = Section.getAlignment();
552
553  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
554  unsigned PaddingSize = 0;
555  unsigned StubBufSize = 0;
556  StringRef Name;
557  bool IsRequired = isRequiredForExecution(Section);
558  bool IsVirtual = Section.isVirtual();
559  bool IsZeroInit = isZeroInit(Section);
560  bool IsReadOnly = isReadOnlyData(Section);
561  uint64_t DataSize = Section.getSize();
562  Check(Section.getName(Name));
563
564  StubBufSize = computeSectionStubBufSize(Obj, Section);
565
566  // The .eh_frame section (at least on Linux) needs an extra four bytes padded
567  // with zeroes added at the end.  For MachO objects, this section has a
568  // slightly different name, so this won't have any effect for MachO objects.
569  if (Name == ".eh_frame")
570    PaddingSize = 4;
571
572  uintptr_t Allocate;
573  unsigned SectionID = Sections.size();
574  uint8_t *Addr;
575  const char *pData = nullptr;
576
577  // Some sections, such as debug info, don't need to be loaded for execution.
578  // Leave those where they are.
579  if (IsRequired) {
580    Check(Section.getContents(data));
581    Allocate = DataSize + PaddingSize + StubBufSize;
582    if (!Allocate)
583      Allocate = 1;
584    Addr = IsCode ? MemMgr.allocateCodeSection(Allocate, Alignment, SectionID,
585                                               Name)
586                  : MemMgr.allocateDataSection(Allocate, Alignment, SectionID,
587                                               Name, IsReadOnly);
588    if (!Addr)
589      report_fatal_error("Unable to allocate section memory!");
590
591    // Virtual sections have no data in the object image, so leave pData = 0
592    if (!IsVirtual)
593      pData = data.data();
594
595    // Zero-initialize or copy the data from the image
596    if (IsZeroInit || IsVirtual)
597      memset(Addr, 0, DataSize);
598    else
599      memcpy(Addr, pData, DataSize);
600
601    // Fill in any extra bytes we allocated for padding
602    if (PaddingSize != 0) {
603      memset(Addr + DataSize, 0, PaddingSize);
604      // Update the DataSize variable so that the stub offset is set correctly.
605      DataSize += PaddingSize;
606    }
607
608    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
609                 << " obj addr: " << format("%p", pData)
610                 << " new addr: " << format("%p", Addr)
611                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
612                 << " Allocate: " << Allocate << "\n");
613  } else {
614    // Even if we didn't load the section, we need to record an entry for it
615    // to handle later processing (and by 'handle' I mean don't do anything
616    // with these sections).
617    Allocate = 0;
618    Addr = nullptr;
619    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
620                 << " obj addr: " << format("%p", data.data()) << " new addr: 0"
621                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
622                 << " Allocate: " << Allocate << "\n");
623  }
624
625  Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
626
627  if (Checker)
628    Checker->registerSection(Obj.getFileName(), SectionID);
629
630  return SectionID;
631}
632
633unsigned RuntimeDyldImpl::findOrEmitSection(const ObjectFile &Obj,
634                                            const SectionRef &Section,
635                                            bool IsCode,
636                                            ObjSectionToIDMap &LocalSections) {
637
638  unsigned SectionID = 0;
639  ObjSectionToIDMap::iterator i = LocalSections.find(Section);
640  if (i != LocalSections.end())
641    SectionID = i->second;
642  else {
643    SectionID = emitSection(Obj, Section, IsCode);
644    LocalSections[Section] = SectionID;
645  }
646  return SectionID;
647}
648
649void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
650                                              unsigned SectionID) {
651  Relocations[SectionID].push_back(RE);
652}
653
654void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
655                                             StringRef SymbolName) {
656  // Relocation by symbol.  If the symbol is found in the global symbol table,
657  // create an appropriate section relocation.  Otherwise, add it to
658  // ExternalSymbolRelocations.
659  RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(SymbolName);
660  if (Loc == GlobalSymbolTable.end()) {
661    ExternalSymbolRelocations[SymbolName].push_back(RE);
662  } else {
663    // Copy the RE since we want to modify its addend.
664    RelocationEntry RECopy = RE;
665    const auto &SymInfo = Loc->second;
666    RECopy.Addend += SymInfo.getOffset();
667    Relocations[SymInfo.getSectionID()].push_back(RECopy);
668  }
669}
670
671uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr,
672                                             unsigned AbiVariant) {
673  if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be) {
674    // This stub has to be able to access the full address space,
675    // since symbol lookup won't necessarily find a handy, in-range,
676    // PLT stub for functions which could be anywhere.
677    // Stub can use ip0 (== x16) to calculate address
678    writeBytesUnaligned(0xd2e00010, Addr,    4); // movz ip0, #:abs_g3:<addr>
679    writeBytesUnaligned(0xf2c00010, Addr+4,  4); // movk ip0, #:abs_g2_nc:<addr>
680    writeBytesUnaligned(0xf2a00010, Addr+8,  4); // movk ip0, #:abs_g1_nc:<addr>
681    writeBytesUnaligned(0xf2800010, Addr+12, 4); // movk ip0, #:abs_g0_nc:<addr>
682    writeBytesUnaligned(0xd61f0200, Addr+16, 4); // br ip0
683
684    return Addr;
685  } else if (Arch == Triple::arm || Arch == Triple::armeb) {
686    // TODO: There is only ARM far stub now. We should add the Thumb stub,
687    // and stubs for branches Thumb - ARM and ARM - Thumb.
688    writeBytesUnaligned(0xe51ff004, Addr, 4); // ldr pc,<label>
689    return Addr + 4;
690  } else if (Arch == Triple::mipsel || Arch == Triple::mips) {
691    // 0:   3c190000        lui     t9,%hi(addr).
692    // 4:   27390000        addiu   t9,t9,%lo(addr).
693    // 8:   03200008        jr      t9.
694    // c:   00000000        nop.
695    const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
696    const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
697
698    writeBytesUnaligned(LuiT9Instr, Addr, 4);
699    writeBytesUnaligned(AdduiT9Instr, Addr+4, 4);
700    writeBytesUnaligned(JrT9Instr, Addr+8, 4);
701    writeBytesUnaligned(NopInstr, Addr+12, 4);
702    return Addr;
703  } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
704    // Depending on which version of the ELF ABI is in use, we need to
705    // generate one of two variants of the stub.  They both start with
706    // the same sequence to load the target address into r12.
707    writeInt32BE(Addr,    0x3D800000); // lis   r12, highest(addr)
708    writeInt32BE(Addr+4,  0x618C0000); // ori   r12, higher(addr)
709    writeInt32BE(Addr+8,  0x798C07C6); // sldi  r12, r12, 32
710    writeInt32BE(Addr+12, 0x658C0000); // oris  r12, r12, h(addr)
711    writeInt32BE(Addr+16, 0x618C0000); // ori   r12, r12, l(addr)
712    if (AbiVariant == 2) {
713      // PowerPC64 stub ELFv2 ABI: The address points to the function itself.
714      // The address is already in r12 as required by the ABI.  Branch to it.
715      writeInt32BE(Addr+20, 0xF8410018); // std   r2,  24(r1)
716      writeInt32BE(Addr+24, 0x7D8903A6); // mtctr r12
717      writeInt32BE(Addr+28, 0x4E800420); // bctr
718    } else {
719      // PowerPC64 stub ELFv1 ABI: The address points to a function descriptor.
720      // Load the function address on r11 and sets it to control register. Also
721      // loads the function TOC in r2 and environment pointer to r11.
722      writeInt32BE(Addr+20, 0xF8410028); // std   r2,  40(r1)
723      writeInt32BE(Addr+24, 0xE96C0000); // ld    r11, 0(r12)
724      writeInt32BE(Addr+28, 0xE84C0008); // ld    r2,  0(r12)
725      writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
726      writeInt32BE(Addr+36, 0xE96C0010); // ld    r11, 16(r2)
727      writeInt32BE(Addr+40, 0x4E800420); // bctr
728    }
729    return Addr;
730  } else if (Arch == Triple::systemz) {
731    writeInt16BE(Addr,    0xC418);     // lgrl %r1,.+8
732    writeInt16BE(Addr+2,  0x0000);
733    writeInt16BE(Addr+4,  0x0004);
734    writeInt16BE(Addr+6,  0x07F1);     // brc 15,%r1
735    // 8-byte address stored at Addr + 8
736    return Addr;
737  } else if (Arch == Triple::x86_64) {
738    *Addr      = 0xFF; // jmp
739    *(Addr+1)  = 0x25; // rip
740    // 32-bit PC-relative address of the GOT entry will be stored at Addr+2
741  } else if (Arch == Triple::x86) {
742    *Addr      = 0xE9; // 32-bit pc-relative jump.
743  }
744  return Addr;
745}
746
747// Assign an address to a symbol name and resolve all the relocations
748// associated with it.
749void RuntimeDyldImpl::reassignSectionAddress(unsigned SectionID,
750                                             uint64_t Addr) {
751  // The address to use for relocation resolution is not
752  // the address of the local section buffer. We must be doing
753  // a remote execution environment of some sort. Relocations can't
754  // be applied until all the sections have been moved.  The client must
755  // trigger this with a call to MCJIT::finalize() or
756  // RuntimeDyld::resolveRelocations().
757  //
758  // Addr is a uint64_t because we can't assume the pointer width
759  // of the target is the same as that of the host. Just use a generic
760  // "big enough" type.
761  DEBUG(dbgs() << "Reassigning address for section "
762               << SectionID << " (" << Sections[SectionID].Name << "): "
763               << format("0x%016" PRIx64, Sections[SectionID].LoadAddress) << " -> "
764               << format("0x%016" PRIx64, Addr) << "\n");
765  Sections[SectionID].LoadAddress = Addr;
766}
767
768void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
769                                            uint64_t Value) {
770  for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
771    const RelocationEntry &RE = Relocs[i];
772    // Ignore relocations for sections that were not loaded
773    if (Sections[RE.SectionID].Address == nullptr)
774      continue;
775    resolveRelocation(RE, Value);
776  }
777}
778
779void RuntimeDyldImpl::resolveExternalSymbols() {
780  while (!ExternalSymbolRelocations.empty()) {
781    StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin();
782
783    StringRef Name = i->first();
784    if (Name.size() == 0) {
785      // This is an absolute symbol, use an address of zero.
786      DEBUG(dbgs() << "Resolving absolute relocations."
787                   << "\n");
788      RelocationList &Relocs = i->second;
789      resolveRelocationList(Relocs, 0);
790    } else {
791      uint64_t Addr = 0;
792      RTDyldSymbolTable::const_iterator Loc = GlobalSymbolTable.find(Name);
793      if (Loc == GlobalSymbolTable.end()) {
794        // This is an external symbol, try to get its address from the symbol
795        // resolver.
796        Addr = Resolver.findSymbol(Name.data()).getAddress();
797        // The call to getSymbolAddress may have caused additional modules to
798        // be loaded, which may have added new entries to the
799        // ExternalSymbolRelocations map.  Consquently, we need to update our
800        // iterator.  This is also why retrieval of the relocation list
801        // associated with this symbol is deferred until below this point.
802        // New entries may have been added to the relocation list.
803        i = ExternalSymbolRelocations.find(Name);
804      } else {
805        // We found the symbol in our global table.  It was probably in a
806        // Module that we loaded previously.
807        const auto &SymInfo = Loc->second;
808        Addr = getSectionLoadAddress(SymInfo.getSectionID()) +
809               SymInfo.getOffset();
810      }
811
812      // FIXME: Implement error handling that doesn't kill the host program!
813      if (!Addr)
814        report_fatal_error("Program used external function '" + Name +
815                           "' which could not be resolved!");
816
817      DEBUG(dbgs() << "Resolving relocations Name: " << Name << "\t"
818                   << format("0x%lx", Addr) << "\n");
819      // This list may have been updated when we called getSymbolAddress, so
820      // don't change this code to get the list earlier.
821      RelocationList &Relocs = i->second;
822      resolveRelocationList(Relocs, Addr);
823    }
824
825    ExternalSymbolRelocations.erase(i);
826  }
827}
828
829//===----------------------------------------------------------------------===//
830// RuntimeDyld class implementation
831
832uint64_t RuntimeDyld::LoadedObjectInfo::getSectionLoadAddress(
833                                                  StringRef SectionName) const {
834  for (unsigned I = BeginIdx; I != EndIdx; ++I)
835    if (RTDyld.Sections[I].Name == SectionName)
836      return RTDyld.Sections[I].LoadAddress;
837
838  return 0;
839}
840
841void RuntimeDyld::MemoryManager::anchor() {}
842void RuntimeDyld::SymbolResolver::anchor() {}
843
844RuntimeDyld::RuntimeDyld(RuntimeDyld::MemoryManager &MemMgr,
845                         RuntimeDyld::SymbolResolver &Resolver)
846    : MemMgr(MemMgr), Resolver(Resolver) {
847  // FIXME: There's a potential issue lurking here if a single instance of
848  // RuntimeDyld is used to load multiple objects.  The current implementation
849  // associates a single memory manager with a RuntimeDyld instance.  Even
850  // though the public class spawns a new 'impl' instance for each load,
851  // they share a single memory manager.  This can become a problem when page
852  // permissions are applied.
853  Dyld = nullptr;
854  ProcessAllSections = false;
855  Checker = nullptr;
856}
857
858RuntimeDyld::~RuntimeDyld() {}
859
860static std::unique_ptr<RuntimeDyldCOFF>
861createRuntimeDyldCOFF(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
862                      RuntimeDyld::SymbolResolver &Resolver,
863                      bool ProcessAllSections, RuntimeDyldCheckerImpl *Checker) {
864  std::unique_ptr<RuntimeDyldCOFF> Dyld =
865    RuntimeDyldCOFF::create(Arch, MM, Resolver);
866  Dyld->setProcessAllSections(ProcessAllSections);
867  Dyld->setRuntimeDyldChecker(Checker);
868  return Dyld;
869}
870
871static std::unique_ptr<RuntimeDyldELF>
872createRuntimeDyldELF(RuntimeDyld::MemoryManager &MM,
873                     RuntimeDyld::SymbolResolver &Resolver,
874                     bool ProcessAllSections, RuntimeDyldCheckerImpl *Checker) {
875  std::unique_ptr<RuntimeDyldELF> Dyld(new RuntimeDyldELF(MM, Resolver));
876  Dyld->setProcessAllSections(ProcessAllSections);
877  Dyld->setRuntimeDyldChecker(Checker);
878  return Dyld;
879}
880
881static std::unique_ptr<RuntimeDyldMachO>
882createRuntimeDyldMachO(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MM,
883                       RuntimeDyld::SymbolResolver &Resolver,
884                       bool ProcessAllSections,
885                       RuntimeDyldCheckerImpl *Checker) {
886  std::unique_ptr<RuntimeDyldMachO> Dyld =
887    RuntimeDyldMachO::create(Arch, MM, Resolver);
888  Dyld->setProcessAllSections(ProcessAllSections);
889  Dyld->setRuntimeDyldChecker(Checker);
890  return Dyld;
891}
892
893std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
894RuntimeDyld::loadObject(const ObjectFile &Obj) {
895  if (!Dyld) {
896    if (Obj.isELF())
897      Dyld = createRuntimeDyldELF(MemMgr, Resolver, ProcessAllSections, Checker);
898    else if (Obj.isMachO())
899      Dyld = createRuntimeDyldMachO(
900               static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
901               ProcessAllSections, Checker);
902    else if (Obj.isCOFF())
903      Dyld = createRuntimeDyldCOFF(
904               static_cast<Triple::ArchType>(Obj.getArch()), MemMgr, Resolver,
905               ProcessAllSections, Checker);
906    else
907      report_fatal_error("Incompatible object format!");
908  }
909
910  if (!Dyld->isCompatibleFile(Obj))
911    report_fatal_error("Incompatible object format!");
912
913  return Dyld->loadObject(Obj);
914}
915
916void *RuntimeDyld::getSymbolLocalAddress(StringRef Name) const {
917  if (!Dyld)
918    return nullptr;
919  return Dyld->getSymbolLocalAddress(Name);
920}
921
922RuntimeDyld::SymbolInfo RuntimeDyld::getSymbol(StringRef Name) const {
923  if (!Dyld)
924    return nullptr;
925  return Dyld->getSymbol(Name);
926}
927
928void RuntimeDyld::resolveRelocations() { Dyld->resolveRelocations(); }
929
930void RuntimeDyld::reassignSectionAddress(unsigned SectionID, uint64_t Addr) {
931  Dyld->reassignSectionAddress(SectionID, Addr);
932}
933
934void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
935                                    uint64_t TargetAddress) {
936  Dyld->mapSectionAddress(LocalAddress, TargetAddress);
937}
938
939bool RuntimeDyld::hasError() { return Dyld->hasError(); }
940
941StringRef RuntimeDyld::getErrorString() { return Dyld->getErrorString(); }
942
943void RuntimeDyld::registerEHFrames() {
944  if (Dyld)
945    Dyld->registerEHFrames();
946}
947
948void RuntimeDyld::deregisterEHFrames() {
949  if (Dyld)
950    Dyld->deregisterEHFrames();
951}
952
953} // end namespace llvm
954