RuntimeDyldELF.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
1//===-- RuntimeDyldELF.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 ELF support for the MC-JIT runtime dynamic linker.
11//
12//===----------------------------------------------------------------------===//
13
14#include "RuntimeDyldELF.h"
15#include "JITRegistrar.h"
16#include "ObjectImageCommon.h"
17#include "llvm/ADT/IntervalMap.h"
18#include "llvm/ADT/STLExtras.h"
19#include "llvm/ADT/StringRef.h"
20#include "llvm/ADT/Triple.h"
21#include "llvm/ExecutionEngine/ObjectBuffer.h"
22#include "llvm/ExecutionEngine/ObjectImage.h"
23#include "llvm/Object/ELFObjectFile.h"
24#include "llvm/Object/ObjectFile.h"
25#include "llvm/Support/ELF.h"
26#include "llvm/Support/MemoryBuffer.h"
27
28using namespace llvm;
29using namespace llvm::object;
30
31#define DEBUG_TYPE "dyld"
32
33namespace {
34
35static inline error_code check(error_code Err) {
36  if (Err) {
37    report_fatal_error(Err.message());
38  }
39  return Err;
40}
41
42template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> {
43  LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
44
45  typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
46  typedef Elf_Sym_Impl<ELFT> Elf_Sym;
47  typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
48  typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
49
50  typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
51
52  typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type;
53
54  std::unique_ptr<ObjectFile> UnderlyingFile;
55
56public:
57  DyldELFObject(std::unique_ptr<ObjectFile> UnderlyingFile,
58                MemoryBuffer *Wrapper, error_code &ec);
59
60  DyldELFObject(MemoryBuffer *Wrapper, error_code &ec);
61
62  void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
63  void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr);
64
65  // Methods for type inquiry through isa, cast and dyn_cast
66  static inline bool classof(const Binary *v) {
67    return (isa<ELFObjectFile<ELFT>>(v) &&
68            classof(cast<ELFObjectFile<ELFT>>(v)));
69  }
70  static inline bool classof(const ELFObjectFile<ELFT> *v) {
71    return v->isDyldType();
72  }
73};
74
75template <class ELFT> class ELFObjectImage : public ObjectImageCommon {
76  bool Registered;
77
78public:
79  ELFObjectImage(ObjectBuffer *Input, std::unique_ptr<DyldELFObject<ELFT>> Obj)
80      : ObjectImageCommon(Input, std::move(Obj)), Registered(false) {}
81
82  virtual ~ELFObjectImage() {
83    if (Registered)
84      deregisterWithDebugger();
85  }
86
87  // Subclasses can override these methods to update the image with loaded
88  // addresses for sections and common symbols
89  void updateSectionAddress(const SectionRef &Sec, uint64_t Addr) override {
90    static_cast<DyldELFObject<ELFT>*>(getObjectFile())
91        ->updateSectionAddress(Sec, Addr);
92  }
93
94  void updateSymbolAddress(const SymbolRef &Sym, uint64_t Addr) override {
95    static_cast<DyldELFObject<ELFT>*>(getObjectFile())
96        ->updateSymbolAddress(Sym, Addr);
97  }
98
99  void registerWithDebugger() override {
100    JITRegistrar::getGDBRegistrar().registerObject(*Buffer);
101    Registered = true;
102  }
103  void deregisterWithDebugger() override {
104    JITRegistrar::getGDBRegistrar().deregisterObject(*Buffer);
105  }
106};
107
108// The MemoryBuffer passed into this constructor is just a wrapper around the
109// actual memory.  Ultimately, the Binary parent class will take ownership of
110// this MemoryBuffer object but not the underlying memory.
111template <class ELFT>
112DyldELFObject<ELFT>::DyldELFObject(MemoryBuffer *Wrapper, error_code &ec)
113    : ELFObjectFile<ELFT>(Wrapper, ec) {
114  this->isDyldELFObject = true;
115}
116
117template <class ELFT>
118DyldELFObject<ELFT>::DyldELFObject(std::unique_ptr<ObjectFile> UnderlyingFile,
119                                   MemoryBuffer *Wrapper, error_code &ec)
120    : ELFObjectFile<ELFT>(Wrapper, ec),
121      UnderlyingFile(std::move(UnderlyingFile)) {
122  this->isDyldELFObject = true;
123}
124
125template <class ELFT>
126void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
127                                               uint64_t Addr) {
128  DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
129  Elf_Shdr *shdr =
130      const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
131
132  // This assumes the address passed in matches the target address bitness
133  // The template-based type cast handles everything else.
134  shdr->sh_addr = static_cast<addr_type>(Addr);
135}
136
137template <class ELFT>
138void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
139                                              uint64_t Addr) {
140
141  Elf_Sym *sym = const_cast<Elf_Sym *>(
142      ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
143
144  // This assumes the address passed in matches the target address bitness
145  // The template-based type cast handles everything else.
146  sym->st_value = static_cast<addr_type>(Addr);
147}
148
149} // namespace
150
151namespace llvm {
152
153void RuntimeDyldELF::registerEHFrames() {
154  if (!MemMgr)
155    return;
156  for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
157    SID EHFrameSID = UnregisteredEHFrameSections[i];
158    uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
159    uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
160    size_t EHFrameSize = Sections[EHFrameSID].Size;
161    MemMgr->registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
162    RegisteredEHFrameSections.push_back(EHFrameSID);
163  }
164  UnregisteredEHFrameSections.clear();
165}
166
167void RuntimeDyldELF::deregisterEHFrames() {
168  if (!MemMgr)
169    return;
170  for (int i = 0, e = RegisteredEHFrameSections.size(); i != e; ++i) {
171    SID EHFrameSID = RegisteredEHFrameSections[i];
172    uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
173    uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
174    size_t EHFrameSize = Sections[EHFrameSID].Size;
175    MemMgr->deregisterEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
176  }
177  RegisteredEHFrameSections.clear();
178}
179
180ObjectImage *
181RuntimeDyldELF::createObjectImageFromFile(std::unique_ptr<object::ObjectFile> ObjFile) {
182  if (!ObjFile)
183    return nullptr;
184
185  error_code ec;
186  MemoryBuffer *Buffer =
187      MemoryBuffer::getMemBuffer(ObjFile->getData(), "", false);
188
189  if (ObjFile->getBytesInAddress() == 4 && ObjFile->isLittleEndian()) {
190    auto Obj =
191        llvm::make_unique<DyldELFObject<ELFType<support::little, 2, false>>>(
192            std::move(ObjFile), Buffer, ec);
193    return new ELFObjectImage<ELFType<support::little, 2, false>>(
194        nullptr, std::move(Obj));
195  } else if (ObjFile->getBytesInAddress() == 4 && !ObjFile->isLittleEndian()) {
196    auto Obj =
197        llvm::make_unique<DyldELFObject<ELFType<support::big, 2, false>>>(
198            std::move(ObjFile), Buffer, ec);
199    return new ELFObjectImage<ELFType<support::big, 2, false>>(nullptr, std::move(Obj));
200  } else if (ObjFile->getBytesInAddress() == 8 && !ObjFile->isLittleEndian()) {
201    auto Obj = llvm::make_unique<DyldELFObject<ELFType<support::big, 2, true>>>(
202        std::move(ObjFile), Buffer, ec);
203    return new ELFObjectImage<ELFType<support::big, 2, true>>(nullptr,
204                                                              std::move(Obj));
205  } else if (ObjFile->getBytesInAddress() == 8 && ObjFile->isLittleEndian()) {
206    auto Obj =
207        llvm::make_unique<DyldELFObject<ELFType<support::little, 2, true>>>(
208            std::move(ObjFile), Buffer, ec);
209    return new ELFObjectImage<ELFType<support::little, 2, true>>(
210        nullptr, std::move(Obj));
211  } else
212    llvm_unreachable("Unexpected ELF format");
213}
214
215ObjectImage *RuntimeDyldELF::createObjectImage(ObjectBuffer *Buffer) {
216  if (Buffer->getBufferSize() < ELF::EI_NIDENT)
217    llvm_unreachable("Unexpected ELF object size");
218  std::pair<unsigned char, unsigned char> Ident =
219      std::make_pair((uint8_t)Buffer->getBufferStart()[ELF::EI_CLASS],
220                     (uint8_t)Buffer->getBufferStart()[ELF::EI_DATA]);
221  error_code ec;
222
223  if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) {
224    auto Obj =
225        llvm::make_unique<DyldELFObject<ELFType<support::little, 4, false>>>(
226            Buffer->getMemBuffer(), ec);
227    return new ELFObjectImage<ELFType<support::little, 4, false>>(
228        Buffer, std::move(Obj));
229  } else if (Ident.first == ELF::ELFCLASS32 &&
230             Ident.second == ELF::ELFDATA2MSB) {
231    auto Obj =
232        llvm::make_unique<DyldELFObject<ELFType<support::big, 4, false>>>(
233            Buffer->getMemBuffer(), ec);
234    return new ELFObjectImage<ELFType<support::big, 4, false>>(Buffer,
235                                                               std::move(Obj));
236  } else if (Ident.first == ELF::ELFCLASS64 &&
237             Ident.second == ELF::ELFDATA2MSB) {
238    auto Obj = llvm::make_unique<DyldELFObject<ELFType<support::big, 8, true>>>(
239        Buffer->getMemBuffer(), ec);
240    return new ELFObjectImage<ELFType<support::big, 8, true>>(Buffer, std::move(Obj));
241  } else if (Ident.first == ELF::ELFCLASS64 &&
242             Ident.second == ELF::ELFDATA2LSB) {
243    auto Obj =
244        llvm::make_unique<DyldELFObject<ELFType<support::little, 8, true>>>(
245            Buffer->getMemBuffer(), ec);
246    return new ELFObjectImage<ELFType<support::little, 8, true>>(Buffer, std::move(Obj));
247  } else
248    llvm_unreachable("Unexpected ELF format");
249}
250
251RuntimeDyldELF::~RuntimeDyldELF() {}
252
253void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
254                                             uint64_t Offset, uint64_t Value,
255                                             uint32_t Type, int64_t Addend,
256                                             uint64_t SymOffset) {
257  switch (Type) {
258  default:
259    llvm_unreachable("Relocation type not implemented yet!");
260    break;
261  case ELF::R_X86_64_64: {
262    uint64_t *Target = reinterpret_cast<uint64_t *>(Section.Address + Offset);
263    *Target = Value + Addend;
264    DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
265                 << format("%p\n", Target));
266    break;
267  }
268  case ELF::R_X86_64_32:
269  case ELF::R_X86_64_32S: {
270    Value += Addend;
271    assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
272           (Type == ELF::R_X86_64_32S &&
273            ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
274    uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
275    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
276    *Target = TruncatedAddr;
277    DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
278                 << format("%p\n", Target));
279    break;
280  }
281  case ELF::R_X86_64_GOTPCREL: {
282    // findGOTEntry returns the 'G + GOT' part of the relocation calculation
283    // based on the load/target address of the GOT (not the current/local addr).
284    uint64_t GOTAddr = findGOTEntry(Value, SymOffset);
285    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
286    uint64_t FinalAddress = Section.LoadAddress + Offset;
287    // The processRelocationRef method combines the symbol offset and the addend
288    // and in most cases that's what we want.  For this relocation type, we need
289    // the raw addend, so we subtract the symbol offset to get it.
290    int64_t RealOffset = GOTAddr + Addend - SymOffset - FinalAddress;
291    assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
292    int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
293    *Target = TruncOffset;
294    break;
295  }
296  case ELF::R_X86_64_PC32: {
297    // Get the placeholder value from the generated object since
298    // a previous relocation attempt may have overwritten the loaded version
299    uint32_t *Placeholder =
300        reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
301    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
302    uint64_t FinalAddress = Section.LoadAddress + Offset;
303    int64_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
304    assert(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
305    int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
306    *Target = TruncOffset;
307    break;
308  }
309  case ELF::R_X86_64_PC64: {
310    // Get the placeholder value from the generated object since
311    // a previous relocation attempt may have overwritten the loaded version
312    uint64_t *Placeholder =
313        reinterpret_cast<uint64_t *>(Section.ObjAddress + Offset);
314    uint64_t *Target = reinterpret_cast<uint64_t *>(Section.Address + Offset);
315    uint64_t FinalAddress = Section.LoadAddress + Offset;
316    *Target = *Placeholder + Value + Addend - FinalAddress;
317    break;
318  }
319  }
320}
321
322void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
323                                          uint64_t Offset, uint32_t Value,
324                                          uint32_t Type, int32_t Addend) {
325  switch (Type) {
326  case ELF::R_386_32: {
327    // Get the placeholder value from the generated object since
328    // a previous relocation attempt may have overwritten the loaded version
329    uint32_t *Placeholder =
330        reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
331    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
332    *Target = *Placeholder + Value + Addend;
333    break;
334  }
335  case ELF::R_386_PC32: {
336    // Get the placeholder value from the generated object since
337    // a previous relocation attempt may have overwritten the loaded version
338    uint32_t *Placeholder =
339        reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
340    uint32_t *Target = reinterpret_cast<uint32_t *>(Section.Address + Offset);
341    uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
342    uint32_t RealOffset = *Placeholder + Value + Addend - FinalAddress;
343    *Target = RealOffset;
344    break;
345  }
346  default:
347    // There are other relocation types, but it appears these are the
348    // only ones currently used by the LLVM ELF object writer
349    llvm_unreachable("Relocation type not implemented yet!");
350    break;
351  }
352}
353
354void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
355                                              uint64_t Offset, uint64_t Value,
356                                              uint32_t Type, int64_t Addend) {
357  uint32_t *TargetPtr = reinterpret_cast<uint32_t *>(Section.Address + Offset);
358  uint64_t FinalAddress = Section.LoadAddress + Offset;
359
360  DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
361               << format("%llx", Section.Address + Offset)
362               << " FinalAddress: 0x" << format("%llx", FinalAddress)
363               << " Value: 0x" << format("%llx", Value) << " Type: 0x"
364               << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
365               << "\n");
366
367  switch (Type) {
368  default:
369    llvm_unreachable("Relocation type not implemented yet!");
370    break;
371  case ELF::R_AARCH64_ABS64: {
372    uint64_t *TargetPtr =
373        reinterpret_cast<uint64_t *>(Section.Address + Offset);
374    *TargetPtr = Value + Addend;
375    break;
376  }
377  case ELF::R_AARCH64_PREL32: {
378    uint64_t Result = Value + Addend - FinalAddress;
379    assert(static_cast<int64_t>(Result) >= INT32_MIN &&
380           static_cast<int64_t>(Result) <= UINT32_MAX);
381    *TargetPtr = static_cast<uint32_t>(Result & 0xffffffffU);
382    break;
383  }
384  case ELF::R_AARCH64_CALL26: // fallthrough
385  case ELF::R_AARCH64_JUMP26: {
386    // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
387    // calculation.
388    uint64_t BranchImm = Value + Addend - FinalAddress;
389
390    // "Check that -2^27 <= result < 2^27".
391    assert(-(1LL << 27) <= static_cast<int64_t>(BranchImm) &&
392           static_cast<int64_t>(BranchImm) < (1LL << 27));
393
394    // AArch64 code is emitted with .rela relocations. The data already in any
395    // bits affected by the relocation on entry is garbage.
396    *TargetPtr &= 0xfc000000U;
397    // Immediate goes in bits 25:0 of B and BL.
398    *TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
399    break;
400  }
401  case ELF::R_AARCH64_MOVW_UABS_G3: {
402    uint64_t Result = Value + Addend;
403
404    // AArch64 code is emitted with .rela relocations. The data already in any
405    // bits affected by the relocation on entry is garbage.
406    *TargetPtr &= 0xffe0001fU;
407    // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
408    *TargetPtr |= Result >> (48 - 5);
409    // Shift must be "lsl #48", in bits 22:21
410    assert((*TargetPtr >> 21 & 0x3) == 3 && "invalid shift for relocation");
411    break;
412  }
413  case ELF::R_AARCH64_MOVW_UABS_G2_NC: {
414    uint64_t Result = Value + Addend;
415
416    // AArch64 code is emitted with .rela relocations. The data already in any
417    // bits affected by the relocation on entry is garbage.
418    *TargetPtr &= 0xffe0001fU;
419    // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
420    *TargetPtr |= ((Result & 0xffff00000000ULL) >> (32 - 5));
421    // Shift must be "lsl #32", in bits 22:21
422    assert((*TargetPtr >> 21 & 0x3) == 2 && "invalid shift for relocation");
423    break;
424  }
425  case ELF::R_AARCH64_MOVW_UABS_G1_NC: {
426    uint64_t Result = Value + Addend;
427
428    // AArch64 code is emitted with .rela relocations. The data already in any
429    // bits affected by the relocation on entry is garbage.
430    *TargetPtr &= 0xffe0001fU;
431    // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
432    *TargetPtr |= ((Result & 0xffff0000U) >> (16 - 5));
433    // Shift must be "lsl #16", in bits 22:2
434    assert((*TargetPtr >> 21 & 0x3) == 1 && "invalid shift for relocation");
435    break;
436  }
437  case ELF::R_AARCH64_MOVW_UABS_G0_NC: {
438    uint64_t Result = Value + Addend;
439
440    // AArch64 code is emitted with .rela relocations. The data already in any
441    // bits affected by the relocation on entry is garbage.
442    *TargetPtr &= 0xffe0001fU;
443    // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
444    *TargetPtr |= ((Result & 0xffffU) << 5);
445    // Shift must be "lsl #0", in bits 22:21.
446    assert((*TargetPtr >> 21 & 0x3) == 0 && "invalid shift for relocation");
447    break;
448  }
449  case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
450    // Operation: Page(S+A) - Page(P)
451    uint64_t Result =
452        ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
453
454    // Check that -2^32 <= X < 2^32
455    assert(static_cast<int64_t>(Result) >= (-1LL << 32) &&
456           static_cast<int64_t>(Result) < (1LL << 32) &&
457           "overflow check failed for relocation");
458
459    // AArch64 code is emitted with .rela relocations. The data already in any
460    // bits affected by the relocation on entry is garbage.
461    *TargetPtr &= 0x9f00001fU;
462    // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
463    // from bits 32:12 of X.
464    *TargetPtr |= ((Result & 0x3000U) << (29 - 12));
465    *TargetPtr |= ((Result & 0x1ffffc000ULL) >> (14 - 5));
466    break;
467  }
468  case ELF::R_AARCH64_LDST32_ABS_LO12_NC: {
469    // Operation: S + A
470    uint64_t Result = Value + Addend;
471
472    // AArch64 code is emitted with .rela relocations. The data already in any
473    // bits affected by the relocation on entry is garbage.
474    *TargetPtr &= 0xffc003ffU;
475    // Immediate goes in bits 21:10 of LD/ST instruction, taken
476    // from bits 11:2 of X
477    *TargetPtr |= ((Result & 0xffc) << (10 - 2));
478    break;
479  }
480  case ELF::R_AARCH64_LDST64_ABS_LO12_NC: {
481    // Operation: S + A
482    uint64_t Result = Value + Addend;
483
484    // AArch64 code is emitted with .rela relocations. The data already in any
485    // bits affected by the relocation on entry is garbage.
486    *TargetPtr &= 0xffc003ffU;
487    // Immediate goes in bits 21:10 of LD/ST instruction, taken
488    // from bits 11:3 of X
489    *TargetPtr |= ((Result & 0xff8) << (10 - 3));
490    break;
491  }
492  }
493}
494
495void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
496                                          uint64_t Offset, uint32_t Value,
497                                          uint32_t Type, int32_t Addend) {
498  // TODO: Add Thumb relocations.
499  uint32_t *Placeholder =
500      reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
501  uint32_t *TargetPtr = (uint32_t *)(Section.Address + Offset);
502  uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
503  Value += Addend;
504
505  DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
506               << Section.Address + Offset
507               << " FinalAddress: " << format("%p", FinalAddress) << " Value: "
508               << format("%x", Value) << " Type: " << format("%x", Type)
509               << " Addend: " << format("%x", Addend) << "\n");
510
511  switch (Type) {
512  default:
513    llvm_unreachable("Not implemented relocation type!");
514
515  case ELF::R_ARM_NONE:
516    break;
517  // Write a 32bit value to relocation address, taking into account the
518  // implicit addend encoded in the target.
519  case ELF::R_ARM_PREL31:
520  case ELF::R_ARM_TARGET1:
521  case ELF::R_ARM_ABS32:
522    *TargetPtr = *Placeholder + Value;
523    break;
524  // Write first 16 bit of 32 bit value to the mov instruction.
525  // Last 4 bit should be shifted.
526  case ELF::R_ARM_MOVW_ABS_NC:
527    // We are not expecting any other addend in the relocation address.
528    // Using 0x000F0FFF because MOVW has its 16 bit immediate split into 2
529    // non-contiguous fields.
530    assert((*Placeholder & 0x000F0FFF) == 0);
531    Value = Value & 0xFFFF;
532    *TargetPtr = *Placeholder | (Value & 0xFFF);
533    *TargetPtr |= ((Value >> 12) & 0xF) << 16;
534    break;
535  // Write last 16 bit of 32 bit value to the mov instruction.
536  // Last 4 bit should be shifted.
537  case ELF::R_ARM_MOVT_ABS:
538    // We are not expecting any other addend in the relocation address.
539    // Use 0x000F0FFF for the same reason as R_ARM_MOVW_ABS_NC.
540    assert((*Placeholder & 0x000F0FFF) == 0);
541
542    Value = (Value >> 16) & 0xFFFF;
543    *TargetPtr = *Placeholder | (Value & 0xFFF);
544    *TargetPtr |= ((Value >> 12) & 0xF) << 16;
545    break;
546  // Write 24 bit relative value to the branch instruction.
547  case ELF::R_ARM_PC24: // Fall through.
548  case ELF::R_ARM_CALL: // Fall through.
549  case ELF::R_ARM_JUMP24: {
550    int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
551    RelValue = (RelValue & 0x03FFFFFC) >> 2;
552    assert((*TargetPtr & 0xFFFFFF) == 0xFFFFFE);
553    *TargetPtr &= 0xFF000000;
554    *TargetPtr |= RelValue;
555    break;
556  }
557  case ELF::R_ARM_PRIVATE_0:
558    // This relocation is reserved by the ARM ELF ABI for internal use. We
559    // appropriate it here to act as an R_ARM_ABS32 without any addend for use
560    // in the stubs created during JIT (which can't put an addend into the
561    // original object file).
562    *TargetPtr = Value;
563    break;
564  }
565}
566
567void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
568                                           uint64_t Offset, uint32_t Value,
569                                           uint32_t Type, int32_t Addend) {
570  uint32_t *Placeholder =
571      reinterpret_cast<uint32_t *>(Section.ObjAddress + Offset);
572  uint32_t *TargetPtr = (uint32_t *)(Section.Address + Offset);
573  Value += Addend;
574
575  DEBUG(dbgs() << "resolveMipselocation, LocalAddress: "
576               << Section.Address + Offset << " FinalAddress: "
577               << format("%p", Section.LoadAddress + Offset) << " Value: "
578               << format("%x", Value) << " Type: " << format("%x", Type)
579               << " Addend: " << format("%x", Addend) << "\n");
580
581  switch (Type) {
582  default:
583    llvm_unreachable("Not implemented relocation type!");
584    break;
585  case ELF::R_MIPS_32:
586    *TargetPtr = Value + (*Placeholder);
587    break;
588  case ELF::R_MIPS_26:
589    *TargetPtr = ((*Placeholder) & 0xfc000000) | ((Value & 0x0fffffff) >> 2);
590    break;
591  case ELF::R_MIPS_HI16:
592    // Get the higher 16-bits. Also add 1 if bit 15 is 1.
593    Value += ((*Placeholder) & 0x0000ffff) << 16;
594    *TargetPtr =
595        ((*Placeholder) & 0xffff0000) | (((Value + 0x8000) >> 16) & 0xffff);
596    break;
597  case ELF::R_MIPS_LO16:
598    Value += ((*Placeholder) & 0x0000ffff);
599    *TargetPtr = ((*Placeholder) & 0xffff0000) | (Value & 0xffff);
600    break;
601  case ELF::R_MIPS_UNUSED1:
602    // Similar to ELF::R_ARM_PRIVATE_0, R_MIPS_UNUSED1 and R_MIPS_UNUSED2
603    // are used for internal JIT purpose. These relocations are similar to
604    // R_MIPS_HI16 and R_MIPS_LO16, but they do not take any addend into
605    // account.
606    *TargetPtr =
607        ((*TargetPtr) & 0xffff0000) | (((Value + 0x8000) >> 16) & 0xffff);
608    break;
609  case ELF::R_MIPS_UNUSED2:
610    *TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
611    break;
612  }
613}
614
615// Return the .TOC. section address to R_PPC64_TOC relocations.
616uint64_t RuntimeDyldELF::findPPC64TOC() const {
617  // The TOC consists of sections .got, .toc, .tocbss, .plt in that
618  // order. The TOC starts where the first of these sections starts.
619  SectionList::const_iterator it = Sections.begin();
620  SectionList::const_iterator ite = Sections.end();
621  for (; it != ite; ++it) {
622    if (it->Name == ".got" || it->Name == ".toc" || it->Name == ".tocbss" ||
623        it->Name == ".plt")
624      break;
625  }
626  if (it == ite) {
627    // This may happen for
628    // * references to TOC base base (sym@toc, .odp relocation) without
629    // a .toc directive.
630    // In this case just use the first section (which is usually
631    // the .odp) since the code won't reference the .toc base
632    // directly.
633    it = Sections.begin();
634  }
635  assert(it != ite);
636  // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
637  // thus permitting a full 64 Kbytes segment.
638  return it->LoadAddress + 0x8000;
639}
640
641// Returns the sections and offset associated with the ODP entry referenced
642// by Symbol.
643void RuntimeDyldELF::findOPDEntrySection(ObjectImage &Obj,
644                                         ObjSectionToIDMap &LocalSections,
645                                         RelocationValueRef &Rel) {
646  // Get the ELF symbol value (st_value) to compare with Relocation offset in
647  // .opd entries
648  for (section_iterator si = Obj.begin_sections(), se = Obj.end_sections();
649       si != se; ++si) {
650    section_iterator RelSecI = si->getRelocatedSection();
651    if (RelSecI == Obj.end_sections())
652      continue;
653
654    StringRef RelSectionName;
655    check(RelSecI->getName(RelSectionName));
656    if (RelSectionName != ".opd")
657      continue;
658
659    for (relocation_iterator i = si->relocation_begin(),
660                             e = si->relocation_end();
661         i != e;) {
662      // The R_PPC64_ADDR64 relocation indicates the first field
663      // of a .opd entry
664      uint64_t TypeFunc;
665      check(i->getType(TypeFunc));
666      if (TypeFunc != ELF::R_PPC64_ADDR64) {
667        ++i;
668        continue;
669      }
670
671      uint64_t TargetSymbolOffset;
672      symbol_iterator TargetSymbol = i->getSymbol();
673      check(i->getOffset(TargetSymbolOffset));
674      int64_t Addend;
675      check(getELFRelocationAddend(*i, Addend));
676
677      ++i;
678      if (i == e)
679        break;
680
681      // Just check if following relocation is a R_PPC64_TOC
682      uint64_t TypeTOC;
683      check(i->getType(TypeTOC));
684      if (TypeTOC != ELF::R_PPC64_TOC)
685        continue;
686
687      // Finally compares the Symbol value and the target symbol offset
688      // to check if this .opd entry refers to the symbol the relocation
689      // points to.
690      if (Rel.Addend != (int64_t)TargetSymbolOffset)
691        continue;
692
693      section_iterator tsi(Obj.end_sections());
694      check(TargetSymbol->getSection(tsi));
695      bool IsCode = false;
696      tsi->isText(IsCode);
697      Rel.SectionID = findOrEmitSection(Obj, (*tsi), IsCode, LocalSections);
698      Rel.Addend = (intptr_t)Addend;
699      return;
700    }
701  }
702  llvm_unreachable("Attempting to get address of ODP entry!");
703}
704
705// Relocation masks following the #lo(value), #hi(value), #higher(value),
706// and #highest(value) macros defined in section 4.5.1. Relocation Types
707// in PPC-elf64abi document.
708//
709static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
710
711static inline uint16_t applyPPChi(uint64_t value) {
712  return (value >> 16) & 0xffff;
713}
714
715static inline uint16_t applyPPChigher(uint64_t value) {
716  return (value >> 32) & 0xffff;
717}
718
719static inline uint16_t applyPPChighest(uint64_t value) {
720  return (value >> 48) & 0xffff;
721}
722
723void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
724                                            uint64_t Offset, uint64_t Value,
725                                            uint32_t Type, int64_t Addend) {
726  uint8_t *LocalAddress = Section.Address + Offset;
727  switch (Type) {
728  default:
729    llvm_unreachable("Relocation type not implemented yet!");
730    break;
731  case ELF::R_PPC64_ADDR16_LO:
732    writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
733    break;
734  case ELF::R_PPC64_ADDR16_HI:
735    writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
736    break;
737  case ELF::R_PPC64_ADDR16_HIGHER:
738    writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
739    break;
740  case ELF::R_PPC64_ADDR16_HIGHEST:
741    writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
742    break;
743  case ELF::R_PPC64_ADDR14: {
744    assert(((Value + Addend) & 3) == 0);
745    // Preserve the AA/LK bits in the branch instruction
746    uint8_t aalk = *(LocalAddress + 3);
747    writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
748  } break;
749  case ELF::R_PPC64_ADDR32: {
750    int32_t Result = static_cast<int32_t>(Value + Addend);
751    if (SignExtend32<32>(Result) != Result)
752      llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
753    writeInt32BE(LocalAddress, Result);
754  } break;
755  case ELF::R_PPC64_REL24: {
756    uint64_t FinalAddress = (Section.LoadAddress + Offset);
757    int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
758    if (SignExtend32<24>(delta) != delta)
759      llvm_unreachable("Relocation R_PPC64_REL24 overflow");
760    // Generates a 'bl <address>' instruction
761    writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
762  } break;
763  case ELF::R_PPC64_REL32: {
764    uint64_t FinalAddress = (Section.LoadAddress + Offset);
765    int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
766    if (SignExtend32<32>(delta) != delta)
767      llvm_unreachable("Relocation R_PPC64_REL32 overflow");
768    writeInt32BE(LocalAddress, delta);
769  } break;
770  case ELF::R_PPC64_REL64: {
771    uint64_t FinalAddress = (Section.LoadAddress + Offset);
772    uint64_t Delta = Value - FinalAddress + Addend;
773    writeInt64BE(LocalAddress, Delta);
774  } break;
775  case ELF::R_PPC64_ADDR64:
776    writeInt64BE(LocalAddress, Value + Addend);
777    break;
778  case ELF::R_PPC64_TOC:
779    writeInt64BE(LocalAddress, findPPC64TOC());
780    break;
781  case ELF::R_PPC64_TOC16: {
782    uint64_t TOCStart = findPPC64TOC();
783    Value = applyPPClo((Value + Addend) - TOCStart);
784    writeInt16BE(LocalAddress, applyPPClo(Value));
785  } break;
786  case ELF::R_PPC64_TOC16_DS: {
787    uint64_t TOCStart = findPPC64TOC();
788    Value = ((Value + Addend) - TOCStart);
789    writeInt16BE(LocalAddress, applyPPClo(Value));
790  } break;
791  }
792}
793
794void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
795                                              uint64_t Offset, uint64_t Value,
796                                              uint32_t Type, int64_t Addend) {
797  uint8_t *LocalAddress = Section.Address + Offset;
798  switch (Type) {
799  default:
800    llvm_unreachable("Relocation type not implemented yet!");
801    break;
802  case ELF::R_390_PC16DBL:
803  case ELF::R_390_PLT16DBL: {
804    int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
805    assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
806    writeInt16BE(LocalAddress, Delta / 2);
807    break;
808  }
809  case ELF::R_390_PC32DBL:
810  case ELF::R_390_PLT32DBL: {
811    int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
812    assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
813    writeInt32BE(LocalAddress, Delta / 2);
814    break;
815  }
816  case ELF::R_390_PC32: {
817    int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
818    assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
819    writeInt32BE(LocalAddress, Delta);
820    break;
821  }
822  case ELF::R_390_64:
823    writeInt64BE(LocalAddress, Value + Addend);
824    break;
825  }
826}
827
828// The target location for the relocation is described by RE.SectionID and
829// RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
830// SectionEntry has three members describing its location.
831// SectionEntry::Address is the address at which the section has been loaded
832// into memory in the current (host) process.  SectionEntry::LoadAddress is the
833// address that the section will have in the target process.
834// SectionEntry::ObjAddress is the address of the bits for this section in the
835// original emitted object image (also in the current address space).
836//
837// Relocations will be applied as if the section were loaded at
838// SectionEntry::LoadAddress, but they will be applied at an address based
839// on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
840// Target memory contents if they are required for value calculations.
841//
842// The Value parameter here is the load address of the symbol for the
843// relocation to be applied.  For relocations which refer to symbols in the
844// current object Value will be the LoadAddress of the section in which
845// the symbol resides (RE.Addend provides additional information about the
846// symbol location).  For external symbols, Value will be the address of the
847// symbol in the target address space.
848void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
849                                       uint64_t Value) {
850  const SectionEntry &Section = Sections[RE.SectionID];
851  return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
852                           RE.SymOffset);
853}
854
855void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
856                                       uint64_t Offset, uint64_t Value,
857                                       uint32_t Type, int64_t Addend,
858                                       uint64_t SymOffset) {
859  switch (Arch) {
860  case Triple::x86_64:
861    resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
862    break;
863  case Triple::x86:
864    resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
865                         (uint32_t)(Addend & 0xffffffffL));
866    break;
867  case Triple::aarch64:
868  case Triple::aarch64_be:
869  case Triple::arm64:
870  case Triple::arm64_be:
871    resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
872    break;
873  case Triple::arm: // Fall through.
874  case Triple::armeb:
875  case Triple::thumb:
876  case Triple::thumbeb:
877    resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
878                         (uint32_t)(Addend & 0xffffffffL));
879    break;
880  case Triple::mips: // Fall through.
881  case Triple::mipsel:
882    resolveMIPSRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL),
883                          Type, (uint32_t)(Addend & 0xffffffffL));
884    break;
885  case Triple::ppc64: // Fall through.
886  case Triple::ppc64le:
887    resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
888    break;
889  case Triple::systemz:
890    resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
891    break;
892  default:
893    llvm_unreachable("Unsupported CPU type!");
894  }
895}
896
897relocation_iterator RuntimeDyldELF::processRelocationRef(
898    unsigned SectionID, relocation_iterator RelI, ObjectImage &Obj,
899    ObjSectionToIDMap &ObjSectionToID, const SymbolTableMap &Symbols,
900    StubMap &Stubs) {
901  uint64_t RelType;
902  Check(RelI->getType(RelType));
903  int64_t Addend;
904  Check(getELFRelocationAddend(*RelI, Addend));
905  symbol_iterator Symbol = RelI->getSymbol();
906
907  // Obtain the symbol name which is referenced in the relocation
908  StringRef TargetName;
909  if (Symbol != Obj.end_symbols())
910    Symbol->getName(TargetName);
911  DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
912               << " TargetName: " << TargetName << "\n");
913  RelocationValueRef Value;
914  // First search for the symbol in the local symbol table
915  SymbolTableMap::const_iterator lsi = Symbols.end();
916  SymbolRef::Type SymType = SymbolRef::ST_Unknown;
917  if (Symbol != Obj.end_symbols()) {
918    lsi = Symbols.find(TargetName.data());
919    Symbol->getType(SymType);
920  }
921  if (lsi != Symbols.end()) {
922    Value.SectionID = lsi->second.first;
923    Value.Offset = lsi->second.second;
924    Value.Addend = lsi->second.second + Addend;
925  } else {
926    // Search for the symbol in the global symbol table
927    SymbolTableMap::const_iterator gsi = GlobalSymbolTable.end();
928    if (Symbol != Obj.end_symbols())
929      gsi = GlobalSymbolTable.find(TargetName.data());
930    if (gsi != GlobalSymbolTable.end()) {
931      Value.SectionID = gsi->second.first;
932      Value.Offset = gsi->second.second;
933      Value.Addend = gsi->second.second + Addend;
934    } else {
935      switch (SymType) {
936      case SymbolRef::ST_Debug: {
937        // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
938        // and can be changed by another developers. Maybe best way is add
939        // a new symbol type ST_Section to SymbolRef and use it.
940        section_iterator si(Obj.end_sections());
941        Symbol->getSection(si);
942        if (si == Obj.end_sections())
943          llvm_unreachable("Symbol section not found, bad object file format!");
944        DEBUG(dbgs() << "\t\tThis is section symbol\n");
945        // Default to 'true' in case isText fails (though it never does).
946        bool isCode = true;
947        si->isText(isCode);
948        Value.SectionID = findOrEmitSection(Obj, (*si), isCode, ObjSectionToID);
949        Value.Addend = Addend;
950        break;
951      }
952      case SymbolRef::ST_Data:
953      case SymbolRef::ST_Unknown: {
954        Value.SymbolName = TargetName.data();
955        Value.Addend = Addend;
956
957        // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
958        // will manifest here as a NULL symbol name.
959        // We can set this as a valid (but empty) symbol name, and rely
960        // on addRelocationForSymbol to handle this.
961        if (!Value.SymbolName)
962          Value.SymbolName = "";
963        break;
964      }
965      default:
966        llvm_unreachable("Unresolved symbol type!");
967        break;
968      }
969    }
970  }
971  uint64_t Offset;
972  Check(RelI->getOffset(Offset));
973
974  DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
975               << "\n");
976  if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be ||
977       Arch == Triple::arm64 || Arch == Triple::arm64_be) &&
978      (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26)) {
979    // This is an AArch64 branch relocation, need to use a stub function.
980    DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
981    SectionEntry &Section = Sections[SectionID];
982
983    // Look for an existing stub.
984    StubMap::const_iterator i = Stubs.find(Value);
985    if (i != Stubs.end()) {
986      resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
987                        RelType, 0);
988      DEBUG(dbgs() << " Stub function found\n");
989    } else {
990      // Create a new stub function.
991      DEBUG(dbgs() << " Create a new stub function\n");
992      Stubs[Value] = Section.StubOffset;
993      uint8_t *StubTargetAddr =
994          createStubFunction(Section.Address + Section.StubOffset);
995
996      RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.Address,
997                                ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
998      RelocationEntry REmovk_g2(SectionID, StubTargetAddr - Section.Address + 4,
999                                ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1000      RelocationEntry REmovk_g1(SectionID, StubTargetAddr - Section.Address + 8,
1001                                ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1002      RelocationEntry REmovk_g0(SectionID,
1003                                StubTargetAddr - Section.Address + 12,
1004                                ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1005
1006      if (Value.SymbolName) {
1007        addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1008        addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1009        addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1010        addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1011      } else {
1012        addRelocationForSection(REmovz_g3, Value.SectionID);
1013        addRelocationForSection(REmovk_g2, Value.SectionID);
1014        addRelocationForSection(REmovk_g1, Value.SectionID);
1015        addRelocationForSection(REmovk_g0, Value.SectionID);
1016      }
1017      resolveRelocation(Section, Offset,
1018                        (uint64_t)Section.Address + Section.StubOffset, RelType,
1019                        0);
1020      Section.StubOffset += getMaxStubSize();
1021    }
1022  } else if (Arch == Triple::arm &&
1023             (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1024              RelType == ELF::R_ARM_JUMP24)) {
1025    // This is an ARM branch relocation, need to use a stub function.
1026    DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
1027    SectionEntry &Section = Sections[SectionID];
1028
1029    // Look for an existing stub.
1030    StubMap::const_iterator i = Stubs.find(Value);
1031    if (i != Stubs.end()) {
1032      resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
1033                        RelType, 0);
1034      DEBUG(dbgs() << " Stub function found\n");
1035    } else {
1036      // Create a new stub function.
1037      DEBUG(dbgs() << " Create a new stub function\n");
1038      Stubs[Value] = Section.StubOffset;
1039      uint8_t *StubTargetAddr =
1040          createStubFunction(Section.Address + Section.StubOffset);
1041      RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1042                         ELF::R_ARM_PRIVATE_0, Value.Addend);
1043      if (Value.SymbolName)
1044        addRelocationForSymbol(RE, Value.SymbolName);
1045      else
1046        addRelocationForSection(RE, Value.SectionID);
1047
1048      resolveRelocation(Section, Offset,
1049                        (uint64_t)Section.Address + Section.StubOffset, RelType,
1050                        0);
1051      Section.StubOffset += getMaxStubSize();
1052    }
1053  } else if ((Arch == Triple::mipsel || Arch == Triple::mips) &&
1054             RelType == ELF::R_MIPS_26) {
1055    // This is an Mips branch relocation, need to use a stub function.
1056    DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1057    SectionEntry &Section = Sections[SectionID];
1058    uint8_t *Target = Section.Address + Offset;
1059    uint32_t *TargetAddress = (uint32_t *)Target;
1060
1061    // Extract the addend from the instruction.
1062    uint32_t Addend = ((*TargetAddress) & 0x03ffffff) << 2;
1063
1064    Value.Addend += Addend;
1065
1066    //  Look up for existing stub.
1067    StubMap::const_iterator i = Stubs.find(Value);
1068    if (i != Stubs.end()) {
1069      RelocationEntry RE(SectionID, Offset, RelType, i->second);
1070      addRelocationForSection(RE, SectionID);
1071      DEBUG(dbgs() << " Stub function found\n");
1072    } else {
1073      // Create a new stub function.
1074      DEBUG(dbgs() << " Create a new stub function\n");
1075      Stubs[Value] = Section.StubOffset;
1076      uint8_t *StubTargetAddr =
1077          createStubFunction(Section.Address + Section.StubOffset);
1078
1079      // Creating Hi and Lo relocations for the filled stub instructions.
1080      RelocationEntry REHi(SectionID, StubTargetAddr - Section.Address,
1081                           ELF::R_MIPS_UNUSED1, Value.Addend);
1082      RelocationEntry RELo(SectionID, StubTargetAddr - Section.Address + 4,
1083                           ELF::R_MIPS_UNUSED2, Value.Addend);
1084
1085      if (Value.SymbolName) {
1086        addRelocationForSymbol(REHi, Value.SymbolName);
1087        addRelocationForSymbol(RELo, Value.SymbolName);
1088      } else {
1089        addRelocationForSection(REHi, Value.SectionID);
1090        addRelocationForSection(RELo, Value.SectionID);
1091      }
1092
1093      RelocationEntry RE(SectionID, Offset, RelType, Section.StubOffset);
1094      addRelocationForSection(RE, SectionID);
1095      Section.StubOffset += getMaxStubSize();
1096    }
1097  } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1098    if (RelType == ELF::R_PPC64_REL24) {
1099      // A PPC branch relocation will need a stub function if the target is
1100      // an external symbol (Symbol::ST_Unknown) or if the target address
1101      // is not within the signed 24-bits branch address.
1102      SectionEntry &Section = Sections[SectionID];
1103      uint8_t *Target = Section.Address + Offset;
1104      bool RangeOverflow = false;
1105      if (SymType != SymbolRef::ST_Unknown) {
1106        // A function call may points to the .opd entry, so the final symbol
1107        // value
1108        // in calculated based in the relocation values in .opd section.
1109        findOPDEntrySection(Obj, ObjSectionToID, Value);
1110        uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
1111        int32_t delta = static_cast<int32_t>(Target - RelocTarget);
1112        // If it is within 24-bits branch range, just set the branch target
1113        if (SignExtend32<24>(delta) == delta) {
1114          RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1115          if (Value.SymbolName)
1116            addRelocationForSymbol(RE, Value.SymbolName);
1117          else
1118            addRelocationForSection(RE, Value.SectionID);
1119        } else {
1120          RangeOverflow = true;
1121        }
1122      }
1123      if (SymType == SymbolRef::ST_Unknown || RangeOverflow == true) {
1124        // It is an external symbol (SymbolRef::ST_Unknown) or within a range
1125        // larger than 24-bits.
1126        StubMap::const_iterator i = Stubs.find(Value);
1127        if (i != Stubs.end()) {
1128          // Symbol function stub already created, just relocate to it
1129          resolveRelocation(Section, Offset,
1130                            (uint64_t)Section.Address + i->second, RelType, 0);
1131          DEBUG(dbgs() << " Stub function found\n");
1132        } else {
1133          // Create a new stub function.
1134          DEBUG(dbgs() << " Create a new stub function\n");
1135          Stubs[Value] = Section.StubOffset;
1136          uint8_t *StubTargetAddr =
1137              createStubFunction(Section.Address + Section.StubOffset);
1138          RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1139                             ELF::R_PPC64_ADDR64, Value.Addend);
1140
1141          // Generates the 64-bits address loads as exemplified in section
1142          // 4.5.1 in PPC64 ELF ABI.
1143          RelocationEntry REhst(SectionID, StubTargetAddr - Section.Address + 2,
1144                                ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1145          RelocationEntry REhr(SectionID, StubTargetAddr - Section.Address + 6,
1146                               ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1147          RelocationEntry REh(SectionID, StubTargetAddr - Section.Address + 14,
1148                              ELF::R_PPC64_ADDR16_HI, Value.Addend);
1149          RelocationEntry REl(SectionID, StubTargetAddr - Section.Address + 18,
1150                              ELF::R_PPC64_ADDR16_LO, Value.Addend);
1151
1152          if (Value.SymbolName) {
1153            addRelocationForSymbol(REhst, Value.SymbolName);
1154            addRelocationForSymbol(REhr, Value.SymbolName);
1155            addRelocationForSymbol(REh, Value.SymbolName);
1156            addRelocationForSymbol(REl, Value.SymbolName);
1157          } else {
1158            addRelocationForSection(REhst, Value.SectionID);
1159            addRelocationForSection(REhr, Value.SectionID);
1160            addRelocationForSection(REh, Value.SectionID);
1161            addRelocationForSection(REl, Value.SectionID);
1162          }
1163
1164          resolveRelocation(Section, Offset,
1165                            (uint64_t)Section.Address + Section.StubOffset,
1166                            RelType, 0);
1167          Section.StubOffset += getMaxStubSize();
1168        }
1169        if (SymType == SymbolRef::ST_Unknown)
1170          // Restore the TOC for external calls
1171          writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1172      }
1173    } else {
1174      RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1175      // Extra check to avoid relocation againt empty symbols (usually
1176      // the R_PPC64_TOC).
1177      if (SymType != SymbolRef::ST_Unknown && TargetName.empty())
1178        Value.SymbolName = nullptr;
1179
1180      if (Value.SymbolName)
1181        addRelocationForSymbol(RE, Value.SymbolName);
1182      else
1183        addRelocationForSection(RE, Value.SectionID);
1184    }
1185  } else if (Arch == Triple::systemz &&
1186             (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1187    // Create function stubs for both PLT and GOT references, regardless of
1188    // whether the GOT reference is to data or code.  The stub contains the
1189    // full address of the symbol, as needed by GOT references, and the
1190    // executable part only adds an overhead of 8 bytes.
1191    //
1192    // We could try to conserve space by allocating the code and data
1193    // parts of the stub separately.  However, as things stand, we allocate
1194    // a stub for every relocation, so using a GOT in JIT code should be
1195    // no less space efficient than using an explicit constant pool.
1196    DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1197    SectionEntry &Section = Sections[SectionID];
1198
1199    // Look for an existing stub.
1200    StubMap::const_iterator i = Stubs.find(Value);
1201    uintptr_t StubAddress;
1202    if (i != Stubs.end()) {
1203      StubAddress = uintptr_t(Section.Address) + i->second;
1204      DEBUG(dbgs() << " Stub function found\n");
1205    } else {
1206      // Create a new stub function.
1207      DEBUG(dbgs() << " Create a new stub function\n");
1208
1209      uintptr_t BaseAddress = uintptr_t(Section.Address);
1210      uintptr_t StubAlignment = getStubAlignment();
1211      StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1212                    -StubAlignment;
1213      unsigned StubOffset = StubAddress - BaseAddress;
1214
1215      Stubs[Value] = StubOffset;
1216      createStubFunction((uint8_t *)StubAddress);
1217      RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1218                         Value.Addend - Addend);
1219      if (Value.SymbolName)
1220        addRelocationForSymbol(RE, Value.SymbolName);
1221      else
1222        addRelocationForSection(RE, Value.SectionID);
1223      Section.StubOffset = StubOffset + getMaxStubSize();
1224    }
1225
1226    if (RelType == ELF::R_390_GOTENT)
1227      resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1228                        Addend);
1229    else
1230      resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1231  } else if (Arch == Triple::x86_64 && RelType == ELF::R_X86_64_PLT32) {
1232    // The way the PLT relocations normally work is that the linker allocates
1233    // the
1234    // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1235    // entry will then jump to an address provided by the GOT.  On first call,
1236    // the
1237    // GOT address will point back into PLT code that resolves the symbol. After
1238    // the first call, the GOT entry points to the actual function.
1239    //
1240    // For local functions we're ignoring all of that here and just replacing
1241    // the PLT32 relocation type with PC32, which will translate the relocation
1242    // into a PC-relative call directly to the function. For external symbols we
1243    // can't be sure the function will be within 2^32 bytes of the call site, so
1244    // we need to create a stub, which calls into the GOT.  This case is
1245    // equivalent to the usual PLT implementation except that we use the stub
1246    // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1247    // rather than allocating a PLT section.
1248    if (Value.SymbolName) {
1249      // This is a call to an external function.
1250      // Look for an existing stub.
1251      SectionEntry &Section = Sections[SectionID];
1252      StubMap::const_iterator i = Stubs.find(Value);
1253      uintptr_t StubAddress;
1254      if (i != Stubs.end()) {
1255        StubAddress = uintptr_t(Section.Address) + i->second;
1256        DEBUG(dbgs() << " Stub function found\n");
1257      } else {
1258        // Create a new stub function (equivalent to a PLT entry).
1259        DEBUG(dbgs() << " Create a new stub function\n");
1260
1261        uintptr_t BaseAddress = uintptr_t(Section.Address);
1262        uintptr_t StubAlignment = getStubAlignment();
1263        StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1264                      -StubAlignment;
1265        unsigned StubOffset = StubAddress - BaseAddress;
1266        Stubs[Value] = StubOffset;
1267        createStubFunction((uint8_t *)StubAddress);
1268
1269        // Create a GOT entry for the external function.
1270        GOTEntries.push_back(Value);
1271
1272        // Make our stub function a relative call to the GOT entry.
1273        RelocationEntry RE(SectionID, StubOffset + 2, ELF::R_X86_64_GOTPCREL,
1274                           -4);
1275        addRelocationForSymbol(RE, Value.SymbolName);
1276
1277        // Bump our stub offset counter
1278        Section.StubOffset = StubOffset + getMaxStubSize();
1279      }
1280
1281      // Make the target call a call into the stub table.
1282      resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1283                        Addend);
1284    } else {
1285      RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1286                         Value.Offset);
1287      addRelocationForSection(RE, Value.SectionID);
1288    }
1289  } else {
1290    if (Arch == Triple::x86_64 && RelType == ELF::R_X86_64_GOTPCREL) {
1291      GOTEntries.push_back(Value);
1292    }
1293    RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
1294    if (Value.SymbolName)
1295      addRelocationForSymbol(RE, Value.SymbolName);
1296    else
1297      addRelocationForSection(RE, Value.SectionID);
1298  }
1299  return ++RelI;
1300}
1301
1302void RuntimeDyldELF::updateGOTEntries(StringRef Name, uint64_t Addr) {
1303
1304  SmallVectorImpl<std::pair<SID, GOTRelocations>>::iterator it;
1305  SmallVectorImpl<std::pair<SID, GOTRelocations>>::iterator end = GOTs.end();
1306
1307  for (it = GOTs.begin(); it != end; ++it) {
1308    GOTRelocations &GOTEntries = it->second;
1309    for (int i = 0, e = GOTEntries.size(); i != e; ++i) {
1310      if (GOTEntries[i].SymbolName != nullptr &&
1311          GOTEntries[i].SymbolName == Name) {
1312        GOTEntries[i].Offset = Addr;
1313      }
1314    }
1315  }
1316}
1317
1318size_t RuntimeDyldELF::getGOTEntrySize() {
1319  // We don't use the GOT in all of these cases, but it's essentially free
1320  // to put them all here.
1321  size_t Result = 0;
1322  switch (Arch) {
1323  case Triple::x86_64:
1324  case Triple::aarch64:
1325  case Triple::aarch64_be:
1326  case Triple::arm64:
1327  case Triple::arm64_be:
1328  case Triple::ppc64:
1329  case Triple::ppc64le:
1330  case Triple::systemz:
1331    Result = sizeof(uint64_t);
1332    break;
1333  case Triple::x86:
1334  case Triple::arm:
1335  case Triple::thumb:
1336  case Triple::mips:
1337  case Triple::mipsel:
1338    Result = sizeof(uint32_t);
1339    break;
1340  default:
1341    llvm_unreachable("Unsupported CPU type!");
1342  }
1343  return Result;
1344}
1345
1346uint64_t RuntimeDyldELF::findGOTEntry(uint64_t LoadAddress, uint64_t Offset) {
1347
1348  const size_t GOTEntrySize = getGOTEntrySize();
1349
1350  SmallVectorImpl<std::pair<SID, GOTRelocations>>::const_iterator it;
1351  SmallVectorImpl<std::pair<SID, GOTRelocations>>::const_iterator end =
1352      GOTs.end();
1353
1354  int GOTIndex = -1;
1355  for (it = GOTs.begin(); it != end; ++it) {
1356    SID GOTSectionID = it->first;
1357    const GOTRelocations &GOTEntries = it->second;
1358
1359    // Find the matching entry in our vector.
1360    uint64_t SymbolOffset = 0;
1361    for (int i = 0, e = GOTEntries.size(); i != e; ++i) {
1362      if (!GOTEntries[i].SymbolName) {
1363        if (getSectionLoadAddress(GOTEntries[i].SectionID) == LoadAddress &&
1364            GOTEntries[i].Offset == Offset) {
1365          GOTIndex = i;
1366          SymbolOffset = GOTEntries[i].Offset;
1367          break;
1368        }
1369      } else {
1370        // GOT entries for external symbols use the addend as the address when
1371        // the external symbol has been resolved.
1372        if (GOTEntries[i].Offset == LoadAddress) {
1373          GOTIndex = i;
1374          // Don't use the Addend here.  The relocation handler will use it.
1375          break;
1376        }
1377      }
1378    }
1379
1380    if (GOTIndex != -1) {
1381      if (GOTEntrySize == sizeof(uint64_t)) {
1382        uint64_t *LocalGOTAddr = (uint64_t *)getSectionAddress(GOTSectionID);
1383        // Fill in this entry with the address of the symbol being referenced.
1384        LocalGOTAddr[GOTIndex] = LoadAddress + SymbolOffset;
1385      } else {
1386        uint32_t *LocalGOTAddr = (uint32_t *)getSectionAddress(GOTSectionID);
1387        // Fill in this entry with the address of the symbol being referenced.
1388        LocalGOTAddr[GOTIndex] = (uint32_t)(LoadAddress + SymbolOffset);
1389      }
1390
1391      // Calculate the load address of this entry
1392      return getSectionLoadAddress(GOTSectionID) + (GOTIndex * GOTEntrySize);
1393    }
1394  }
1395
1396  assert(GOTIndex != -1 && "Unable to find requested GOT entry.");
1397  return 0;
1398}
1399
1400void RuntimeDyldELF::finalizeLoad(ObjectImage &ObjImg,
1401                                  ObjSectionToIDMap &SectionMap) {
1402  // If necessary, allocate the global offset table
1403  if (MemMgr) {
1404    // Allocate the GOT if necessary
1405    size_t numGOTEntries = GOTEntries.size();
1406    if (numGOTEntries != 0) {
1407      // Allocate memory for the section
1408      unsigned SectionID = Sections.size();
1409      size_t TotalSize = numGOTEntries * getGOTEntrySize();
1410      uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, getGOTEntrySize(),
1411                                                  SectionID, ".got", false);
1412      if (!Addr)
1413        report_fatal_error("Unable to allocate memory for GOT!");
1414
1415      GOTs.push_back(std::make_pair(SectionID, GOTEntries));
1416      Sections.push_back(SectionEntry(".got", Addr, TotalSize, 0));
1417      // For now, initialize all GOT entries to zero.  We'll fill them in as
1418      // needed when GOT-based relocations are applied.
1419      memset(Addr, 0, TotalSize);
1420    }
1421  } else {
1422    report_fatal_error("Unable to allocate memory for GOT!");
1423  }
1424
1425  // Look for and record the EH frame section.
1426  ObjSectionToIDMap::iterator i, e;
1427  for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1428    const SectionRef &Section = i->first;
1429    StringRef Name;
1430    Section.getName(Name);
1431    if (Name == ".eh_frame") {
1432      UnregisteredEHFrameSections.push_back(i->second);
1433      break;
1434    }
1435  }
1436}
1437
1438bool RuntimeDyldELF::isCompatibleFormat(const ObjectBuffer *Buffer) const {
1439  if (Buffer->getBufferSize() < strlen(ELF::ElfMagic))
1440    return false;
1441  return (memcmp(Buffer->getBufferStart(), ELF::ElfMagic,
1442                 strlen(ELF::ElfMagic))) == 0;
1443}
1444
1445bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile *Obj) const {
1446  return Obj->isELF();
1447}
1448
1449} // namespace llvm
1450