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 "RuntimeDyldCheckerImpl.h"
16 #include "llvm/ADT/IntervalMap.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ADT/Triple.h"
20 #include "llvm/MC/MCStreamer.h"
21 #include "llvm/Object/ELFObjectFile.h"
22 #include "llvm/Object/ObjectFile.h"
23 #include "llvm/Support/ELF.h"
24 #include "llvm/Support/Endian.h"
25 #include "llvm/Support/MemoryBuffer.h"
26 #include "llvm/Support/TargetRegistry.h"
27 
28 using namespace llvm;
29 using namespace llvm::object;
30 
31 #define DEBUG_TYPE "dyld"
32 
33 static inline std::error_code check(std::error_code Err) {
34   if (Err) {
35     report_fatal_error(Err.message());
36   }
37   return Err;
38 }
39 
40 namespace {
41 
42 template <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 public:
55   DyldELFObject(MemoryBufferRef Wrapper, std::error_code &ec);
56 
57   void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
58 
59   void updateSymbolAddress(const SymbolRef &SymRef, uint64_t Addr);
60 
61   // Methods for type inquiry through isa, cast and dyn_cast
62   static inline bool classof(const Binary *v) {
63     return (isa<ELFObjectFile<ELFT>>(v) &&
64             classof(cast<ELFObjectFile<ELFT>>(v)));
65   }
66   static inline bool classof(const ELFObjectFile<ELFT> *v) {
67     return v->isDyldType();
68   }
69 
70 };
71 
72 
73 
74 // The MemoryBuffer passed into this constructor is just a wrapper around the
75 // actual memory.  Ultimately, the Binary parent class will take ownership of
76 // this MemoryBuffer object but not the underlying memory.
77 template <class ELFT>
78 DyldELFObject<ELFT>::DyldELFObject(MemoryBufferRef Wrapper, std::error_code &EC)
79     : ELFObjectFile<ELFT>(Wrapper, EC) {
80   this->isDyldELFObject = true;
81 }
82 
83 template <class ELFT>
84 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
85                                                uint64_t Addr) {
86   DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
87   Elf_Shdr *shdr =
88       const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
89 
90   // This assumes the address passed in matches the target address bitness
91   // The template-based type cast handles everything else.
92   shdr->sh_addr = static_cast<addr_type>(Addr);
93 }
94 
95 template <class ELFT>
96 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
97                                               uint64_t Addr) {
98 
99   Elf_Sym *sym = const_cast<Elf_Sym *>(
100       ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
101 
102   // This assumes the address passed in matches the target address bitness
103   // The template-based type cast handles everything else.
104   sym->st_value = static_cast<addr_type>(Addr);
105 }
106 
107 class LoadedELFObjectInfo
108     : public RuntimeDyld::LoadedObjectInfoHelper<LoadedELFObjectInfo> {
109 public:
110   LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, unsigned BeginIdx,
111                       unsigned EndIdx)
112       : LoadedObjectInfoHelper(RTDyld, BeginIdx, EndIdx) {}
113 
114   OwningBinary<ObjectFile>
115   getObjectForDebug(const ObjectFile &Obj) const override;
116 };
117 
118 template <typename ELFT>
119 std::unique_ptr<DyldELFObject<ELFT>>
120 createRTDyldELFObject(MemoryBufferRef Buffer,
121                       const LoadedELFObjectInfo &L,
122                       std::error_code &ec) {
123   typedef typename ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
124   typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type;
125 
126   std::unique_ptr<DyldELFObject<ELFT>> Obj =
127     llvm::make_unique<DyldELFObject<ELFT>>(Buffer, ec);
128 
129   // Iterate over all sections in the object.
130   for (const auto &Sec : Obj->sections()) {
131     StringRef SectionName;
132     Sec.getName(SectionName);
133     if (SectionName != "") {
134       DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
135       Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
136           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
137 
138       if (uint64_t SecLoadAddr = L.getSectionLoadAddress(SectionName)) {
139         // This assumes that the address passed in matches the target address
140         // bitness. The template-based type cast handles everything else.
141         shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
142       }
143     }
144   }
145 
146   return Obj;
147 }
148 
149 OwningBinary<ObjectFile> createELFDebugObject(const ObjectFile &Obj,
150                                               const LoadedELFObjectInfo &L) {
151   assert(Obj.isELF() && "Not an ELF object file.");
152 
153   std::unique_ptr<MemoryBuffer> Buffer =
154     MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
155 
156   std::error_code ec;
157 
158   std::unique_ptr<ObjectFile> DebugObj;
159   if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian()) {
160     typedef ELFType<support::little, false> ELF32LE;
161     DebugObj = createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), L, ec);
162   } else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian()) {
163     typedef ELFType<support::big, false> ELF32BE;
164     DebugObj = createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), L, ec);
165   } else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian()) {
166     typedef ELFType<support::big, true> ELF64BE;
167     DebugObj = createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), L, ec);
168   } else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian()) {
169     typedef ELFType<support::little, true> ELF64LE;
170     DebugObj = createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), L, ec);
171   } else
172     llvm_unreachable("Unexpected ELF format");
173 
174   assert(!ec && "Could not construct copy ELF object file");
175 
176   return OwningBinary<ObjectFile>(std::move(DebugObj), std::move(Buffer));
177 }
178 
179 OwningBinary<ObjectFile>
180 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
181   return createELFDebugObject(Obj, *this);
182 }
183 
184 } // namespace
185 
186 namespace llvm {
187 
188 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
189                                RuntimeDyld::SymbolResolver &Resolver)
190     : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
191 RuntimeDyldELF::~RuntimeDyldELF() {}
192 
193 void RuntimeDyldELF::registerEHFrames() {
194   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
195     SID EHFrameSID = UnregisteredEHFrameSections[i];
196     uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
197     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
198     size_t EHFrameSize = Sections[EHFrameSID].Size;
199     MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
200     RegisteredEHFrameSections.push_back(EHFrameSID);
201   }
202   UnregisteredEHFrameSections.clear();
203 }
204 
205 void RuntimeDyldELF::deregisterEHFrames() {
206   for (int i = 0, e = RegisteredEHFrameSections.size(); i != e; ++i) {
207     SID EHFrameSID = RegisteredEHFrameSections[i];
208     uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
209     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
210     size_t EHFrameSize = Sections[EHFrameSID].Size;
211     MemMgr.deregisterEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
212   }
213   RegisteredEHFrameSections.clear();
214 }
215 
216 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
217 RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
218   unsigned SectionStartIdx, SectionEndIdx;
219   std::tie(SectionStartIdx, SectionEndIdx) = loadObjectImpl(O);
220   return llvm::make_unique<LoadedELFObjectInfo>(*this, SectionStartIdx,
221                                                 SectionEndIdx);
222 }
223 
224 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
225                                              uint64_t Offset, uint64_t Value,
226                                              uint32_t Type, int64_t Addend,
227                                              uint64_t SymOffset) {
228   switch (Type) {
229   default:
230     llvm_unreachable("Relocation type not implemented yet!");
231     break;
232   case ELF::R_X86_64_64: {
233     support::ulittle64_t::ref(Section.Address + Offset) = Value + Addend;
234     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
235                  << format("%p\n", Section.Address + Offset));
236     break;
237   }
238   case ELF::R_X86_64_32:
239   case ELF::R_X86_64_32S: {
240     Value += Addend;
241     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
242            (Type == ELF::R_X86_64_32S &&
243             ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
244     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
245     support::ulittle32_t::ref(Section.Address + Offset) = TruncatedAddr;
246     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
247                  << format("%p\n", Section.Address + Offset));
248     break;
249   }
250   case ELF::R_X86_64_PC32: {
251     uint64_t FinalAddress = Section.LoadAddress + Offset;
252     int64_t RealOffset = Value + Addend - FinalAddress;
253     assert(isInt<32>(RealOffset));
254     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
255     support::ulittle32_t::ref(Section.Address + Offset) = TruncOffset;
256     break;
257   }
258   case ELF::R_X86_64_PC64: {
259     uint64_t FinalAddress = Section.LoadAddress + Offset;
260     int64_t RealOffset = Value + Addend - FinalAddress;
261     support::ulittle64_t::ref(Section.Address + Offset) = RealOffset;
262     break;
263   }
264   }
265 }
266 
267 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
268                                           uint64_t Offset, uint32_t Value,
269                                           uint32_t Type, int32_t Addend) {
270   switch (Type) {
271   case ELF::R_386_32: {
272     support::ulittle32_t::ref(Section.Address + Offset) = Value + Addend;
273     break;
274   }
275   case ELF::R_386_PC32: {
276     uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
277     uint32_t RealOffset = Value + Addend - FinalAddress;
278     support::ulittle32_t::ref(Section.Address + Offset) = RealOffset;
279     break;
280   }
281   default:
282     // There are other relocation types, but it appears these are the
283     // only ones currently used by the LLVM ELF object writer
284     llvm_unreachable("Relocation type not implemented yet!");
285     break;
286   }
287 }
288 
289 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
290                                               uint64_t Offset, uint64_t Value,
291                                               uint32_t Type, int64_t Addend) {
292   uint32_t *TargetPtr = reinterpret_cast<uint32_t *>(Section.Address + Offset);
293   uint64_t FinalAddress = Section.LoadAddress + Offset;
294 
295   DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
296                << format("%llx", Section.Address + Offset)
297                << " FinalAddress: 0x" << format("%llx", FinalAddress)
298                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
299                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
300                << "\n");
301 
302   switch (Type) {
303   default:
304     llvm_unreachable("Relocation type not implemented yet!");
305     break;
306   case ELF::R_AARCH64_ABS64: {
307     uint64_t *TargetPtr =
308         reinterpret_cast<uint64_t *>(Section.Address + Offset);
309     *TargetPtr = Value + Addend;
310     break;
311   }
312   case ELF::R_AARCH64_PREL32: {
313     uint64_t Result = Value + Addend - FinalAddress;
314     assert(static_cast<int64_t>(Result) >= INT32_MIN &&
315            static_cast<int64_t>(Result) <= UINT32_MAX);
316     *TargetPtr = static_cast<uint32_t>(Result & 0xffffffffU);
317     break;
318   }
319   case ELF::R_AARCH64_CALL26: // fallthrough
320   case ELF::R_AARCH64_JUMP26: {
321     // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
322     // calculation.
323     uint64_t BranchImm = Value + Addend - FinalAddress;
324 
325     // "Check that -2^27 <= result < 2^27".
326     assert(isInt<28>(BranchImm));
327 
328     // AArch64 code is emitted with .rela relocations. The data already in any
329     // bits affected by the relocation on entry is garbage.
330     *TargetPtr &= 0xfc000000U;
331     // Immediate goes in bits 25:0 of B and BL.
332     *TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
333     break;
334   }
335   case ELF::R_AARCH64_MOVW_UABS_G3: {
336     uint64_t Result = Value + Addend;
337 
338     // AArch64 code is emitted with .rela relocations. The data already in any
339     // bits affected by the relocation on entry is garbage.
340     *TargetPtr &= 0xffe0001fU;
341     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
342     *TargetPtr |= Result >> (48 - 5);
343     // Shift must be "lsl #48", in bits 22:21
344     assert((*TargetPtr >> 21 & 0x3) == 3 && "invalid shift for relocation");
345     break;
346   }
347   case ELF::R_AARCH64_MOVW_UABS_G2_NC: {
348     uint64_t Result = Value + Addend;
349 
350     // AArch64 code is emitted with .rela relocations. The data already in any
351     // bits affected by the relocation on entry is garbage.
352     *TargetPtr &= 0xffe0001fU;
353     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
354     *TargetPtr |= ((Result & 0xffff00000000ULL) >> (32 - 5));
355     // Shift must be "lsl #32", in bits 22:21
356     assert((*TargetPtr >> 21 & 0x3) == 2 && "invalid shift for relocation");
357     break;
358   }
359   case ELF::R_AARCH64_MOVW_UABS_G1_NC: {
360     uint64_t Result = Value + Addend;
361 
362     // AArch64 code is emitted with .rela relocations. The data already in any
363     // bits affected by the relocation on entry is garbage.
364     *TargetPtr &= 0xffe0001fU;
365     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
366     *TargetPtr |= ((Result & 0xffff0000U) >> (16 - 5));
367     // Shift must be "lsl #16", in bits 22:2
368     assert((*TargetPtr >> 21 & 0x3) == 1 && "invalid shift for relocation");
369     break;
370   }
371   case ELF::R_AARCH64_MOVW_UABS_G0_NC: {
372     uint64_t Result = Value + Addend;
373 
374     // AArch64 code is emitted with .rela relocations. The data already in any
375     // bits affected by the relocation on entry is garbage.
376     *TargetPtr &= 0xffe0001fU;
377     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
378     *TargetPtr |= ((Result & 0xffffU) << 5);
379     // Shift must be "lsl #0", in bits 22:21.
380     assert((*TargetPtr >> 21 & 0x3) == 0 && "invalid shift for relocation");
381     break;
382   }
383   case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
384     // Operation: Page(S+A) - Page(P)
385     uint64_t Result =
386         ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
387 
388     // Check that -2^32 <= X < 2^32
389     assert(isInt<33>(Result) && "overflow check failed for relocation");
390 
391     // AArch64 code is emitted with .rela relocations. The data already in any
392     // bits affected by the relocation on entry is garbage.
393     *TargetPtr &= 0x9f00001fU;
394     // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
395     // from bits 32:12 of X.
396     *TargetPtr |= ((Result & 0x3000U) << (29 - 12));
397     *TargetPtr |= ((Result & 0x1ffffc000ULL) >> (14 - 5));
398     break;
399   }
400   case ELF::R_AARCH64_LDST32_ABS_LO12_NC: {
401     // Operation: S + A
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 &= 0xffc003ffU;
407     // Immediate goes in bits 21:10 of LD/ST instruction, taken
408     // from bits 11:2 of X
409     *TargetPtr |= ((Result & 0xffc) << (10 - 2));
410     break;
411   }
412   case ELF::R_AARCH64_LDST64_ABS_LO12_NC: {
413     // Operation: S + A
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 &= 0xffc003ffU;
419     // Immediate goes in bits 21:10 of LD/ST instruction, taken
420     // from bits 11:3 of X
421     *TargetPtr |= ((Result & 0xff8) << (10 - 3));
422     break;
423   }
424   }
425 }
426 
427 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
428                                           uint64_t Offset, uint32_t Value,
429                                           uint32_t Type, int32_t Addend) {
430   // TODO: Add Thumb relocations.
431   uint32_t *TargetPtr = (uint32_t *)(Section.Address + Offset);
432   uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
433   Value += Addend;
434 
435   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
436                << Section.Address + Offset
437                << " FinalAddress: " << format("%p", FinalAddress) << " Value: "
438                << format("%x", Value) << " Type: " << format("%x", Type)
439                << " Addend: " << format("%x", Addend) << "\n");
440 
441   switch (Type) {
442   default:
443     llvm_unreachable("Not implemented relocation type!");
444 
445   case ELF::R_ARM_NONE:
446     break;
447   case ELF::R_ARM_PREL31:
448   case ELF::R_ARM_TARGET1:
449   case ELF::R_ARM_ABS32:
450     *TargetPtr = Value;
451     break;
452     // Write first 16 bit of 32 bit value to the mov instruction.
453     // Last 4 bit should be shifted.
454   case ELF::R_ARM_MOVW_ABS_NC:
455   case ELF::R_ARM_MOVT_ABS:
456     if (Type == ELF::R_ARM_MOVW_ABS_NC)
457       Value = Value & 0xFFFF;
458     else if (Type == ELF::R_ARM_MOVT_ABS)
459       Value = (Value >> 16) & 0xFFFF;
460     *TargetPtr &= ~0x000F0FFF;
461     *TargetPtr |= Value & 0xFFF;
462     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
463     break;
464     // Write 24 bit relative value to the branch instruction.
465   case ELF::R_ARM_PC24: // Fall through.
466   case ELF::R_ARM_CALL: // Fall through.
467   case ELF::R_ARM_JUMP24:
468     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
469     RelValue = (RelValue & 0x03FFFFFC) >> 2;
470     assert((*TargetPtr & 0xFFFFFF) == 0xFFFFFE);
471     *TargetPtr &= 0xFF000000;
472     *TargetPtr |= RelValue;
473     break;
474   }
475 }
476 
477 void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
478                                            uint64_t Offset, uint32_t Value,
479                                            uint32_t Type, int32_t Addend) {
480   uint8_t *TargetPtr = Section.Address + Offset;
481   Value += Addend;
482 
483   DEBUG(dbgs() << "resolveMIPSRelocation, LocalAddress: "
484                << Section.Address + Offset << " FinalAddress: "
485                << format("%p", Section.LoadAddress + Offset) << " Value: "
486                << format("%x", Value) << " Type: " << format("%x", Type)
487                << " Addend: " << format("%x", Addend) << "\n");
488 
489   uint32_t Insn = readBytesUnaligned(TargetPtr, 4);
490 
491   switch (Type) {
492   default:
493     llvm_unreachable("Not implemented relocation type!");
494     break;
495   case ELF::R_MIPS_32:
496     writeBytesUnaligned(Value, TargetPtr, 4);
497     break;
498   case ELF::R_MIPS_26:
499     Insn &= 0xfc000000;
500     Insn |= (Value & 0x0fffffff) >> 2;
501     writeBytesUnaligned(Insn, TargetPtr, 4);
502     break;
503   case ELF::R_MIPS_HI16:
504     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
505     Insn &= 0xffff0000;
506     Insn |= ((Value + 0x8000) >> 16) & 0xffff;
507     writeBytesUnaligned(Insn, TargetPtr, 4);
508     break;
509   case ELF::R_MIPS_LO16:
510     Insn &= 0xffff0000;
511     Insn |= Value & 0xffff;
512     writeBytesUnaligned(Insn, TargetPtr, 4);
513     break;
514   case ELF::R_MIPS_PC32:
515     uint32_t FinalAddress = (Section.LoadAddress + Offset);
516     writeBytesUnaligned(Value + Addend - FinalAddress, (uint8_t *)TargetPtr, 4);
517     break;
518   }
519 }
520 
521 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
522   if (Arch == Triple::UnknownArch ||
523       !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
524     IsMipsO32ABI = false;
525     IsMipsN64ABI = false;
526     return;
527   }
528   unsigned AbiVariant;
529   Obj.getPlatformFlags(AbiVariant);
530   IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
531   IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips");
532   if (AbiVariant & ELF::EF_MIPS_ABI2)
533     llvm_unreachable("Mips N32 ABI is not supported yet");
534 }
535 
536 void RuntimeDyldELF::resolveMIPS64Relocation(const SectionEntry &Section,
537                                              uint64_t Offset, uint64_t Value,
538                                              uint32_t Type, int64_t Addend,
539                                              uint64_t SymOffset,
540                                              SID SectionID) {
541   uint32_t r_type = Type & 0xff;
542   uint32_t r_type2 = (Type >> 8) & 0xff;
543   uint32_t r_type3 = (Type >> 16) & 0xff;
544 
545   // RelType is used to keep information for which relocation type we are
546   // applying relocation.
547   uint32_t RelType = r_type;
548   int64_t CalculatedValue = evaluateMIPS64Relocation(Section, Offset, Value,
549                                                      RelType, Addend,
550                                                      SymOffset, SectionID);
551   if (r_type2 != ELF::R_MIPS_NONE) {
552     RelType = r_type2;
553     CalculatedValue = evaluateMIPS64Relocation(Section, Offset, 0, RelType,
554                                                CalculatedValue, SymOffset,
555                                                SectionID);
556   }
557   if (r_type3 != ELF::R_MIPS_NONE) {
558     RelType = r_type3;
559     CalculatedValue = evaluateMIPS64Relocation(Section, Offset, 0, RelType,
560                                                CalculatedValue, SymOffset,
561                                                SectionID);
562   }
563   applyMIPS64Relocation(Section.Address + Offset, CalculatedValue, RelType);
564 }
565 
566 int64_t
567 RuntimeDyldELF::evaluateMIPS64Relocation(const SectionEntry &Section,
568                                          uint64_t Offset, uint64_t Value,
569                                          uint32_t Type, int64_t Addend,
570                                          uint64_t SymOffset, SID SectionID) {
571 
572   DEBUG(dbgs() << "evaluateMIPS64Relocation, LocalAddress: 0x"
573                << format("%llx", Section.Address + Offset)
574                << " FinalAddress: 0x"
575                << format("%llx", Section.LoadAddress + Offset)
576                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
577                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
578                << " SymOffset: " << format("%x", SymOffset)
579                << "\n");
580 
581   switch (Type) {
582   default:
583     llvm_unreachable("Not implemented relocation type!");
584     break;
585   case ELF::R_MIPS_JALR:
586   case ELF::R_MIPS_NONE:
587     break;
588   case ELF::R_MIPS_32:
589   case ELF::R_MIPS_64:
590     return Value + Addend;
591   case ELF::R_MIPS_26:
592     return ((Value + Addend) >> 2) & 0x3ffffff;
593   case ELF::R_MIPS_GPREL16: {
594     uint64_t GOTAddr = getSectionLoadAddress(SectionToGOTMap[SectionID]);
595     return Value + Addend - (GOTAddr + 0x7ff0);
596   }
597   case ELF::R_MIPS_SUB:
598     return Value - Addend;
599   case ELF::R_MIPS_HI16:
600     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
601     return ((Value + Addend + 0x8000) >> 16) & 0xffff;
602   case ELF::R_MIPS_LO16:
603     return (Value + Addend) & 0xffff;
604   case ELF::R_MIPS_CALL16:
605   case ELF::R_MIPS_GOT_DISP:
606   case ELF::R_MIPS_GOT_PAGE: {
607     uint8_t *LocalGOTAddr =
608         getSectionAddress(SectionToGOTMap[SectionID]) + SymOffset;
609     uint64_t GOTEntry = readBytesUnaligned(LocalGOTAddr, 8);
610 
611     Value += Addend;
612     if (Type == ELF::R_MIPS_GOT_PAGE)
613       Value = (Value + 0x8000) & ~0xffff;
614 
615     if (GOTEntry)
616       assert(GOTEntry == Value &&
617                    "GOT entry has two different addresses.");
618     else
619       writeBytesUnaligned(Value, LocalGOTAddr, 8);
620 
621     return (SymOffset - 0x7ff0) & 0xffff;
622   }
623   case ELF::R_MIPS_GOT_OFST: {
624     int64_t page = (Value + Addend + 0x8000) & ~0xffff;
625     return (Value + Addend - page) & 0xffff;
626   }
627   case ELF::R_MIPS_GPREL32: {
628     uint64_t GOTAddr = getSectionLoadAddress(SectionToGOTMap[SectionID]);
629     return Value + Addend - (GOTAddr + 0x7ff0);
630   }
631   case ELF::R_MIPS_PC16: {
632     uint64_t FinalAddress = (Section.LoadAddress + Offset);
633     return ((Value + Addend - FinalAddress) >> 2) & 0xffff;
634   }
635   case ELF::R_MIPS_PC32: {
636     uint64_t FinalAddress = (Section.LoadAddress + Offset);
637     return Value + Addend - FinalAddress;
638   }
639   case ELF::R_MIPS_PC18_S3: {
640     uint64_t FinalAddress = (Section.LoadAddress + Offset);
641     return ((Value + Addend - ((FinalAddress | 7) ^ 7)) >> 3) & 0x3ffff;
642   }
643   case ELF::R_MIPS_PC19_S2: {
644     uint64_t FinalAddress = (Section.LoadAddress + Offset);
645     return ((Value + Addend - FinalAddress) >> 2) & 0x7ffff;
646   }
647   case ELF::R_MIPS_PC21_S2: {
648     uint64_t FinalAddress = (Section.LoadAddress + Offset);
649     return ((Value + Addend - FinalAddress) >> 2) & 0x1fffff;
650   }
651   case ELF::R_MIPS_PC26_S2: {
652     uint64_t FinalAddress = (Section.LoadAddress + Offset);
653     return ((Value + Addend - FinalAddress) >> 2) & 0x3ffffff;
654   }
655   case ELF::R_MIPS_PCHI16: {
656     uint64_t FinalAddress = (Section.LoadAddress + Offset);
657     return ((Value + Addend - FinalAddress + 0x8000) >> 16) & 0xffff;
658   }
659   case ELF::R_MIPS_PCLO16: {
660     uint64_t FinalAddress = (Section.LoadAddress + Offset);
661     return (Value + Addend - FinalAddress) & 0xffff;
662   }
663   }
664   return 0;
665 }
666 
667 void RuntimeDyldELF::applyMIPS64Relocation(uint8_t *TargetPtr,
668                                            int64_t CalculatedValue,
669                                            uint32_t Type) {
670   uint32_t Insn = readBytesUnaligned(TargetPtr, 4);
671 
672   switch (Type) {
673     default:
674       break;
675     case ELF::R_MIPS_32:
676     case ELF::R_MIPS_GPREL32:
677     case ELF::R_MIPS_PC32:
678       writeBytesUnaligned(CalculatedValue & 0xffffffff, TargetPtr, 4);
679       break;
680     case ELF::R_MIPS_64:
681     case ELF::R_MIPS_SUB:
682       writeBytesUnaligned(CalculatedValue, TargetPtr, 8);
683       break;
684     case ELF::R_MIPS_26:
685     case ELF::R_MIPS_PC26_S2:
686       Insn = (Insn & 0xfc000000) | CalculatedValue;
687       writeBytesUnaligned(Insn, TargetPtr, 4);
688       break;
689     case ELF::R_MIPS_GPREL16:
690       Insn = (Insn & 0xffff0000) | (CalculatedValue & 0xffff);
691       writeBytesUnaligned(Insn, TargetPtr, 4);
692       break;
693     case ELF::R_MIPS_HI16:
694     case ELF::R_MIPS_LO16:
695     case ELF::R_MIPS_PCHI16:
696     case ELF::R_MIPS_PCLO16:
697     case ELF::R_MIPS_PC16:
698     case ELF::R_MIPS_CALL16:
699     case ELF::R_MIPS_GOT_DISP:
700     case ELF::R_MIPS_GOT_PAGE:
701     case ELF::R_MIPS_GOT_OFST:
702       Insn = (Insn & 0xffff0000) | CalculatedValue;
703       writeBytesUnaligned(Insn, TargetPtr, 4);
704       break;
705     case ELF::R_MIPS_PC18_S3:
706       Insn = (Insn & 0xfffc0000) | CalculatedValue;
707       writeBytesUnaligned(Insn, TargetPtr, 4);
708       break;
709     case ELF::R_MIPS_PC19_S2:
710       Insn = (Insn & 0xfff80000) | CalculatedValue;
711       writeBytesUnaligned(Insn, TargetPtr, 4);
712       break;
713     case ELF::R_MIPS_PC21_S2:
714       Insn = (Insn & 0xffe00000) | CalculatedValue;
715       writeBytesUnaligned(Insn, TargetPtr, 4);
716       break;
717     }
718 }
719 
720 // Return the .TOC. section and offset.
721 void RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
722                                          ObjSectionToIDMap &LocalSections,
723                                          RelocationValueRef &Rel) {
724   // Set a default SectionID in case we do not find a TOC section below.
725   // This may happen for references to TOC base base (sym@toc, .odp
726   // relocation) without a .toc directive.  In this case just use the
727   // first section (which is usually the .odp) since the code won't
728   // reference the .toc base directly.
729   Rel.SymbolName = NULL;
730   Rel.SectionID = 0;
731 
732   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
733   // order. The TOC starts where the first of these sections starts.
734   for (auto &Section: Obj.sections()) {
735     StringRef SectionName;
736     check(Section.getName(SectionName));
737 
738     if (SectionName == ".got"
739         || SectionName == ".toc"
740         || SectionName == ".tocbss"
741         || SectionName == ".plt") {
742       Rel.SectionID = findOrEmitSection(Obj, Section, false, LocalSections);
743       break;
744     }
745   }
746 
747   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
748   // thus permitting a full 64 Kbytes segment.
749   Rel.Addend = 0x8000;
750 }
751 
752 // Returns the sections and offset associated with the ODP entry referenced
753 // by Symbol.
754 void RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
755                                          ObjSectionToIDMap &LocalSections,
756                                          RelocationValueRef &Rel) {
757   // Get the ELF symbol value (st_value) to compare with Relocation offset in
758   // .opd entries
759   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
760        si != se; ++si) {
761     section_iterator RelSecI = si->getRelocatedSection();
762     if (RelSecI == Obj.section_end())
763       continue;
764 
765     StringRef RelSectionName;
766     check(RelSecI->getName(RelSectionName));
767     if (RelSectionName != ".opd")
768       continue;
769 
770     for (elf_relocation_iterator i = si->relocation_begin(),
771                                  e = si->relocation_end();
772          i != e;) {
773       // The R_PPC64_ADDR64 relocation indicates the first field
774       // of a .opd entry
775       uint64_t TypeFunc = i->getType();
776       if (TypeFunc != ELF::R_PPC64_ADDR64) {
777         ++i;
778         continue;
779       }
780 
781       uint64_t TargetSymbolOffset = i->getOffset();
782       symbol_iterator TargetSymbol = i->getSymbol();
783       ErrorOr<int64_t> AddendOrErr = i->getAddend();
784       Check(AddendOrErr.getError());
785       int64_t Addend = *AddendOrErr;
786 
787       ++i;
788       if (i == e)
789         break;
790 
791       // Just check if following relocation is a R_PPC64_TOC
792       uint64_t TypeTOC = i->getType();
793       if (TypeTOC != ELF::R_PPC64_TOC)
794         continue;
795 
796       // Finally compares the Symbol value and the target symbol offset
797       // to check if this .opd entry refers to the symbol the relocation
798       // points to.
799       if (Rel.Addend != (int64_t)TargetSymbolOffset)
800         continue;
801 
802       section_iterator tsi(Obj.section_end());
803       check(TargetSymbol->getSection(tsi));
804       bool IsCode = tsi->isText();
805       Rel.SectionID = findOrEmitSection(Obj, (*tsi), IsCode, LocalSections);
806       Rel.Addend = (intptr_t)Addend;
807       return;
808     }
809   }
810   llvm_unreachable("Attempting to get address of ODP entry!");
811 }
812 
813 // Relocation masks following the #lo(value), #hi(value), #ha(value),
814 // #higher(value), #highera(value), #highest(value), and #highesta(value)
815 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
816 // document.
817 
818 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
819 
820 static inline uint16_t applyPPChi(uint64_t value) {
821   return (value >> 16) & 0xffff;
822 }
823 
824 static inline uint16_t applyPPCha (uint64_t value) {
825   return ((value + 0x8000) >> 16) & 0xffff;
826 }
827 
828 static inline uint16_t applyPPChigher(uint64_t value) {
829   return (value >> 32) & 0xffff;
830 }
831 
832 static inline uint16_t applyPPChighera (uint64_t value) {
833   return ((value + 0x8000) >> 32) & 0xffff;
834 }
835 
836 static inline uint16_t applyPPChighest(uint64_t value) {
837   return (value >> 48) & 0xffff;
838 }
839 
840 static inline uint16_t applyPPChighesta (uint64_t value) {
841   return ((value + 0x8000) >> 48) & 0xffff;
842 }
843 
844 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
845                                             uint64_t Offset, uint64_t Value,
846                                             uint32_t Type, int64_t Addend) {
847   uint8_t *LocalAddress = Section.Address + Offset;
848   switch (Type) {
849   default:
850     llvm_unreachable("Relocation type not implemented yet!");
851     break;
852   case ELF::R_PPC64_ADDR16:
853     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
854     break;
855   case ELF::R_PPC64_ADDR16_DS:
856     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
857     break;
858   case ELF::R_PPC64_ADDR16_LO:
859     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
860     break;
861   case ELF::R_PPC64_ADDR16_LO_DS:
862     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
863     break;
864   case ELF::R_PPC64_ADDR16_HI:
865     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
866     break;
867   case ELF::R_PPC64_ADDR16_HA:
868     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
869     break;
870   case ELF::R_PPC64_ADDR16_HIGHER:
871     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
872     break;
873   case ELF::R_PPC64_ADDR16_HIGHERA:
874     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
875     break;
876   case ELF::R_PPC64_ADDR16_HIGHEST:
877     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
878     break;
879   case ELF::R_PPC64_ADDR16_HIGHESTA:
880     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
881     break;
882   case ELF::R_PPC64_ADDR14: {
883     assert(((Value + Addend) & 3) == 0);
884     // Preserve the AA/LK bits in the branch instruction
885     uint8_t aalk = *(LocalAddress + 3);
886     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
887   } break;
888   case ELF::R_PPC64_REL16_LO: {
889     uint64_t FinalAddress = (Section.LoadAddress + Offset);
890     uint64_t Delta = Value - FinalAddress + Addend;
891     writeInt16BE(LocalAddress, applyPPClo(Delta));
892   } break;
893   case ELF::R_PPC64_REL16_HI: {
894     uint64_t FinalAddress = (Section.LoadAddress + Offset);
895     uint64_t Delta = Value - FinalAddress + Addend;
896     writeInt16BE(LocalAddress, applyPPChi(Delta));
897   } break;
898   case ELF::R_PPC64_REL16_HA: {
899     uint64_t FinalAddress = (Section.LoadAddress + Offset);
900     uint64_t Delta = Value - FinalAddress + Addend;
901     writeInt16BE(LocalAddress, applyPPCha(Delta));
902   } break;
903   case ELF::R_PPC64_ADDR32: {
904     int32_t Result = static_cast<int32_t>(Value + Addend);
905     if (SignExtend32<32>(Result) != Result)
906       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
907     writeInt32BE(LocalAddress, Result);
908   } break;
909   case ELF::R_PPC64_REL24: {
910     uint64_t FinalAddress = (Section.LoadAddress + Offset);
911     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
912     if (SignExtend32<24>(delta) != delta)
913       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
914     // Generates a 'bl <address>' instruction
915     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
916   } break;
917   case ELF::R_PPC64_REL32: {
918     uint64_t FinalAddress = (Section.LoadAddress + Offset);
919     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
920     if (SignExtend32<32>(delta) != delta)
921       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
922     writeInt32BE(LocalAddress, delta);
923   } break;
924   case ELF::R_PPC64_REL64: {
925     uint64_t FinalAddress = (Section.LoadAddress + Offset);
926     uint64_t Delta = Value - FinalAddress + Addend;
927     writeInt64BE(LocalAddress, Delta);
928   } break;
929   case ELF::R_PPC64_ADDR64:
930     writeInt64BE(LocalAddress, Value + Addend);
931     break;
932   }
933 }
934 
935 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
936                                               uint64_t Offset, uint64_t Value,
937                                               uint32_t Type, int64_t Addend) {
938   uint8_t *LocalAddress = Section.Address + Offset;
939   switch (Type) {
940   default:
941     llvm_unreachable("Relocation type not implemented yet!");
942     break;
943   case ELF::R_390_PC16DBL:
944   case ELF::R_390_PLT16DBL: {
945     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
946     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
947     writeInt16BE(LocalAddress, Delta / 2);
948     break;
949   }
950   case ELF::R_390_PC32DBL:
951   case ELF::R_390_PLT32DBL: {
952     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
953     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
954     writeInt32BE(LocalAddress, Delta / 2);
955     break;
956   }
957   case ELF::R_390_PC32: {
958     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
959     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
960     writeInt32BE(LocalAddress, Delta);
961     break;
962   }
963   case ELF::R_390_64:
964     writeInt64BE(LocalAddress, Value + Addend);
965     break;
966   }
967 }
968 
969 // The target location for the relocation is described by RE.SectionID and
970 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
971 // SectionEntry has three members describing its location.
972 // SectionEntry::Address is the address at which the section has been loaded
973 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
974 // address that the section will have in the target process.
975 // SectionEntry::ObjAddress is the address of the bits for this section in the
976 // original emitted object image (also in the current address space).
977 //
978 // Relocations will be applied as if the section were loaded at
979 // SectionEntry::LoadAddress, but they will be applied at an address based
980 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
981 // Target memory contents if they are required for value calculations.
982 //
983 // The Value parameter here is the load address of the symbol for the
984 // relocation to be applied.  For relocations which refer to symbols in the
985 // current object Value will be the LoadAddress of the section in which
986 // the symbol resides (RE.Addend provides additional information about the
987 // symbol location).  For external symbols, Value will be the address of the
988 // symbol in the target address space.
989 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
990                                        uint64_t Value) {
991   const SectionEntry &Section = Sections[RE.SectionID];
992   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
993                            RE.SymOffset, RE.SectionID);
994 }
995 
996 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
997                                        uint64_t Offset, uint64_t Value,
998                                        uint32_t Type, int64_t Addend,
999                                        uint64_t SymOffset, SID SectionID) {
1000   switch (Arch) {
1001   case Triple::x86_64:
1002     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
1003     break;
1004   case Triple::x86:
1005     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
1006                          (uint32_t)(Addend & 0xffffffffL));
1007     break;
1008   case Triple::aarch64:
1009   case Triple::aarch64_be:
1010     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
1011     break;
1012   case Triple::arm: // Fall through.
1013   case Triple::armeb:
1014   case Triple::thumb:
1015   case Triple::thumbeb:
1016     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
1017                          (uint32_t)(Addend & 0xffffffffL));
1018     break;
1019   case Triple::mips: // Fall through.
1020   case Triple::mipsel:
1021   case Triple::mips64:
1022   case Triple::mips64el:
1023     if (IsMipsO32ABI)
1024       resolveMIPSRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL),
1025                             Type, (uint32_t)(Addend & 0xffffffffL));
1026     else if (IsMipsN64ABI)
1027       resolveMIPS64Relocation(Section, Offset, Value, Type, Addend, SymOffset,
1028                               SectionID);
1029     else
1030       llvm_unreachable("Mips ABI not handled");
1031     break;
1032   case Triple::ppc64: // Fall through.
1033   case Triple::ppc64le:
1034     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
1035     break;
1036   case Triple::systemz:
1037     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
1038     break;
1039   default:
1040     llvm_unreachable("Unsupported CPU type!");
1041   }
1042 }
1043 
1044 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
1045   return (void*)(Sections[SectionID].ObjAddress + Offset);
1046 }
1047 
1048 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
1049   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
1050   if (Value.SymbolName)
1051     addRelocationForSymbol(RE, Value.SymbolName);
1052   else
1053     addRelocationForSection(RE, Value.SectionID);
1054 }
1055 
1056 relocation_iterator RuntimeDyldELF::processRelocationRef(
1057     unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1058     ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1059   const auto &Obj = cast<ELFObjectFileBase>(O);
1060   uint64_t RelType = RelI->getType();
1061   ErrorOr<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend();
1062   int64_t Addend = AddendOrErr ? *AddendOrErr : 0;
1063   elf_symbol_iterator Symbol = RelI->getSymbol();
1064 
1065   // Obtain the symbol name which is referenced in the relocation
1066   StringRef TargetName;
1067   if (Symbol != Obj.symbol_end())
1068     Symbol->getName(TargetName);
1069   DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1070                << " TargetName: " << TargetName << "\n");
1071   RelocationValueRef Value;
1072   // First search for the symbol in the local symbol table
1073   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1074 
1075   // Search for the symbol in the global symbol table
1076   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1077   if (Symbol != Obj.symbol_end()) {
1078     gsi = GlobalSymbolTable.find(TargetName.data());
1079     SymType = Symbol->getType();
1080   }
1081   if (gsi != GlobalSymbolTable.end()) {
1082     const auto &SymInfo = gsi->second;
1083     Value.SectionID = SymInfo.getSectionID();
1084     Value.Offset = SymInfo.getOffset();
1085     Value.Addend = SymInfo.getOffset() + Addend;
1086   } else {
1087     switch (SymType) {
1088     case SymbolRef::ST_Debug: {
1089       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1090       // and can be changed by another developers. Maybe best way is add
1091       // a new symbol type ST_Section to SymbolRef and use it.
1092       section_iterator si(Obj.section_end());
1093       Symbol->getSection(si);
1094       if (si == Obj.section_end())
1095         llvm_unreachable("Symbol section not found, bad object file format!");
1096       DEBUG(dbgs() << "\t\tThis is section symbol\n");
1097       bool isCode = si->isText();
1098       Value.SectionID = findOrEmitSection(Obj, (*si), isCode, ObjSectionToID);
1099       Value.Addend = Addend;
1100       break;
1101     }
1102     case SymbolRef::ST_Data:
1103     case SymbolRef::ST_Unknown: {
1104       Value.SymbolName = TargetName.data();
1105       Value.Addend = Addend;
1106 
1107       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1108       // will manifest here as a NULL symbol name.
1109       // We can set this as a valid (but empty) symbol name, and rely
1110       // on addRelocationForSymbol to handle this.
1111       if (!Value.SymbolName)
1112         Value.SymbolName = "";
1113       break;
1114     }
1115     default:
1116       llvm_unreachable("Unresolved symbol type!");
1117       break;
1118     }
1119   }
1120 
1121   uint64_t Offset = RelI->getOffset();
1122 
1123   DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1124                << "\n");
1125   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be) &&
1126       (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26)) {
1127     // This is an AArch64 branch relocation, need to use a stub function.
1128     DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1129     SectionEntry &Section = Sections[SectionID];
1130 
1131     // Look for an existing stub.
1132     StubMap::const_iterator i = Stubs.find(Value);
1133     if (i != Stubs.end()) {
1134       resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
1135                         RelType, 0);
1136       DEBUG(dbgs() << " Stub function found\n");
1137     } else {
1138       // Create a new stub function.
1139       DEBUG(dbgs() << " Create a new stub function\n");
1140       Stubs[Value] = Section.StubOffset;
1141       uint8_t *StubTargetAddr =
1142           createStubFunction(Section.Address + Section.StubOffset);
1143 
1144       RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.Address,
1145                                 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1146       RelocationEntry REmovk_g2(SectionID, StubTargetAddr - Section.Address + 4,
1147                                 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1148       RelocationEntry REmovk_g1(SectionID, StubTargetAddr - Section.Address + 8,
1149                                 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1150       RelocationEntry REmovk_g0(SectionID,
1151                                 StubTargetAddr - Section.Address + 12,
1152                                 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1153 
1154       if (Value.SymbolName) {
1155         addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1156         addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1157         addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1158         addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1159       } else {
1160         addRelocationForSection(REmovz_g3, Value.SectionID);
1161         addRelocationForSection(REmovk_g2, Value.SectionID);
1162         addRelocationForSection(REmovk_g1, Value.SectionID);
1163         addRelocationForSection(REmovk_g0, Value.SectionID);
1164       }
1165       resolveRelocation(Section, Offset,
1166                         (uint64_t)Section.Address + Section.StubOffset, RelType,
1167                         0);
1168       Section.StubOffset += getMaxStubSize();
1169     }
1170   } else if (Arch == Triple::arm) {
1171     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1172       RelType == ELF::R_ARM_JUMP24) {
1173       // This is an ARM branch relocation, need to use a stub function.
1174       DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
1175       SectionEntry &Section = Sections[SectionID];
1176 
1177       // Look for an existing stub.
1178       StubMap::const_iterator i = Stubs.find(Value);
1179       if (i != Stubs.end()) {
1180         resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
1181           RelType, 0);
1182         DEBUG(dbgs() << " Stub function found\n");
1183       } else {
1184         // Create a new stub function.
1185         DEBUG(dbgs() << " Create a new stub function\n");
1186         Stubs[Value] = Section.StubOffset;
1187         uint8_t *StubTargetAddr =
1188           createStubFunction(Section.Address + Section.StubOffset);
1189         RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1190           ELF::R_ARM_ABS32, Value.Addend);
1191         if (Value.SymbolName)
1192           addRelocationForSymbol(RE, Value.SymbolName);
1193         else
1194           addRelocationForSection(RE, Value.SectionID);
1195 
1196         resolveRelocation(Section, Offset,
1197           (uint64_t)Section.Address + Section.StubOffset, RelType,
1198           0);
1199         Section.StubOffset += getMaxStubSize();
1200       }
1201     } else {
1202       uint32_t *Placeholder =
1203         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1204       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1205           RelType == ELF::R_ARM_ABS32) {
1206         Value.Addend += *Placeholder;
1207       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1208         // See ELF for ARM documentation
1209         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1210       }
1211       processSimpleRelocation(SectionID, Offset, RelType, Value);
1212     }
1213   } else if (IsMipsO32ABI) {
1214     uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1215         computePlaceholderAddress(SectionID, Offset));
1216     uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1217     if (RelType == ELF::R_MIPS_26) {
1218       // This is an Mips branch relocation, need to use a stub function.
1219       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1220       SectionEntry &Section = Sections[SectionID];
1221 
1222       // Extract the addend from the instruction.
1223       // We shift up by two since the Value will be down shifted again
1224       // when applying the relocation.
1225       uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1226 
1227       Value.Addend += Addend;
1228 
1229       //  Look up for existing stub.
1230       StubMap::const_iterator i = Stubs.find(Value);
1231       if (i != Stubs.end()) {
1232         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1233         addRelocationForSection(RE, SectionID);
1234         DEBUG(dbgs() << " Stub function found\n");
1235       } else {
1236         // Create a new stub function.
1237         DEBUG(dbgs() << " Create a new stub function\n");
1238         Stubs[Value] = Section.StubOffset;
1239         uint8_t *StubTargetAddr =
1240           createStubFunction(Section.Address + Section.StubOffset);
1241 
1242         // Creating Hi and Lo relocations for the filled stub instructions.
1243         RelocationEntry REHi(SectionID, StubTargetAddr - Section.Address,
1244           ELF::R_MIPS_HI16, Value.Addend);
1245         RelocationEntry RELo(SectionID, StubTargetAddr - Section.Address + 4,
1246           ELF::R_MIPS_LO16, Value.Addend);
1247 
1248         if (Value.SymbolName) {
1249           addRelocationForSymbol(REHi, Value.SymbolName);
1250           addRelocationForSymbol(RELo, Value.SymbolName);
1251         }
1252         else {
1253           addRelocationForSection(REHi, Value.SectionID);
1254           addRelocationForSection(RELo, Value.SectionID);
1255         }
1256 
1257         RelocationEntry RE(SectionID, Offset, RelType, Section.StubOffset);
1258         addRelocationForSection(RE, SectionID);
1259         Section.StubOffset += getMaxStubSize();
1260       }
1261     } else {
1262       if (RelType == ELF::R_MIPS_HI16)
1263         Value.Addend += (Opcode & 0x0000ffff) << 16;
1264       else if (RelType == ELF::R_MIPS_LO16)
1265         Value.Addend += (Opcode & 0x0000ffff);
1266       else if (RelType == ELF::R_MIPS_32)
1267         Value.Addend += Opcode;
1268       processSimpleRelocation(SectionID, Offset, RelType, Value);
1269     }
1270   } else if (IsMipsN64ABI) {
1271     uint32_t r_type = RelType & 0xff;
1272     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1273     if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1274         || r_type == ELF::R_MIPS_GOT_DISP) {
1275       StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1276       if (i != GOTSymbolOffsets.end())
1277         RE.SymOffset = i->second;
1278       else {
1279         RE.SymOffset = allocateGOTEntries(SectionID, 1);
1280         GOTSymbolOffsets[TargetName] = RE.SymOffset;
1281       }
1282     }
1283     if (Value.SymbolName)
1284       addRelocationForSymbol(RE, Value.SymbolName);
1285     else
1286       addRelocationForSection(RE, Value.SectionID);
1287   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1288     if (RelType == ELF::R_PPC64_REL24) {
1289       // Determine ABI variant in use for this object.
1290       unsigned AbiVariant;
1291       Obj.getPlatformFlags(AbiVariant);
1292       AbiVariant &= ELF::EF_PPC64_ABI;
1293       // A PPC branch relocation will need a stub function if the target is
1294       // an external symbol (Symbol::ST_Unknown) or if the target address
1295       // is not within the signed 24-bits branch address.
1296       SectionEntry &Section = Sections[SectionID];
1297       uint8_t *Target = Section.Address + Offset;
1298       bool RangeOverflow = false;
1299       if (SymType != SymbolRef::ST_Unknown) {
1300         if (AbiVariant != 2) {
1301           // In the ELFv1 ABI, a function call may point to the .opd entry,
1302           // so the final symbol value is calculated based on the relocation
1303           // values in the .opd section.
1304           findOPDEntrySection(Obj, ObjSectionToID, Value);
1305         } else {
1306           // In the ELFv2 ABI, a function symbol may provide a local entry
1307           // point, which must be used for direct calls.
1308           uint8_t SymOther = Symbol->getOther();
1309           Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1310         }
1311         uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
1312         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
1313         // If it is within 24-bits branch range, just set the branch target
1314         if (SignExtend32<24>(delta) == delta) {
1315           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1316           if (Value.SymbolName)
1317             addRelocationForSymbol(RE, Value.SymbolName);
1318           else
1319             addRelocationForSection(RE, Value.SectionID);
1320         } else {
1321           RangeOverflow = true;
1322         }
1323       }
1324       if (SymType == SymbolRef::ST_Unknown || RangeOverflow) {
1325         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
1326         // larger than 24-bits.
1327         StubMap::const_iterator i = Stubs.find(Value);
1328         if (i != Stubs.end()) {
1329           // Symbol function stub already created, just relocate to it
1330           resolveRelocation(Section, Offset,
1331                             (uint64_t)Section.Address + i->second, RelType, 0);
1332           DEBUG(dbgs() << " Stub function found\n");
1333         } else {
1334           // Create a new stub function.
1335           DEBUG(dbgs() << " Create a new stub function\n");
1336           Stubs[Value] = Section.StubOffset;
1337           uint8_t *StubTargetAddr =
1338               createStubFunction(Section.Address + Section.StubOffset,
1339                                  AbiVariant);
1340           RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1341                              ELF::R_PPC64_ADDR64, Value.Addend);
1342 
1343           // Generates the 64-bits address loads as exemplified in section
1344           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1345           // apply to the low part of the instructions, so we have to update
1346           // the offset according to the target endianness.
1347           uint64_t StubRelocOffset = StubTargetAddr - Section.Address;
1348           if (!IsTargetLittleEndian)
1349             StubRelocOffset += 2;
1350 
1351           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1352                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1353           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1354                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1355           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1356                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1357           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1358                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1359 
1360           if (Value.SymbolName) {
1361             addRelocationForSymbol(REhst, Value.SymbolName);
1362             addRelocationForSymbol(REhr, Value.SymbolName);
1363             addRelocationForSymbol(REh, Value.SymbolName);
1364             addRelocationForSymbol(REl, Value.SymbolName);
1365           } else {
1366             addRelocationForSection(REhst, Value.SectionID);
1367             addRelocationForSection(REhr, Value.SectionID);
1368             addRelocationForSection(REh, Value.SectionID);
1369             addRelocationForSection(REl, Value.SectionID);
1370           }
1371 
1372           resolveRelocation(Section, Offset,
1373                             (uint64_t)Section.Address + Section.StubOffset,
1374                             RelType, 0);
1375           Section.StubOffset += getMaxStubSize();
1376         }
1377         if (SymType == SymbolRef::ST_Unknown) {
1378           // Restore the TOC for external calls
1379           if (AbiVariant == 2)
1380             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
1381           else
1382             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1383         }
1384       }
1385     } else if (RelType == ELF::R_PPC64_TOC16 ||
1386                RelType == ELF::R_PPC64_TOC16_DS ||
1387                RelType == ELF::R_PPC64_TOC16_LO ||
1388                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1389                RelType == ELF::R_PPC64_TOC16_HI ||
1390                RelType == ELF::R_PPC64_TOC16_HA) {
1391       // These relocations are supposed to subtract the TOC address from
1392       // the final value.  This does not fit cleanly into the RuntimeDyld
1393       // scheme, since there may be *two* sections involved in determining
1394       // the relocation value (the section of the symbol refered to by the
1395       // relocation, and the TOC section associated with the current module).
1396       //
1397       // Fortunately, these relocations are currently only ever generated
1398       // refering to symbols that themselves reside in the TOC, which means
1399       // that the two sections are actually the same.  Thus they cancel out
1400       // and we can immediately resolve the relocation right now.
1401       switch (RelType) {
1402       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1403       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1404       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1405       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1406       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1407       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1408       default: llvm_unreachable("Wrong relocation type.");
1409       }
1410 
1411       RelocationValueRef TOCValue;
1412       findPPC64TOCSection(Obj, ObjSectionToID, TOCValue);
1413       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1414         llvm_unreachable("Unsupported TOC relocation.");
1415       Value.Addend -= TOCValue.Addend;
1416       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1417     } else {
1418       // There are two ways to refer to the TOC address directly: either
1419       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1420       // ignored), or via any relocation that refers to the magic ".TOC."
1421       // symbols (in which case the addend is respected).
1422       if (RelType == ELF::R_PPC64_TOC) {
1423         RelType = ELF::R_PPC64_ADDR64;
1424         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1425       } else if (TargetName == ".TOC.") {
1426         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1427         Value.Addend += Addend;
1428       }
1429 
1430       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1431 
1432       if (Value.SymbolName)
1433         addRelocationForSymbol(RE, Value.SymbolName);
1434       else
1435         addRelocationForSection(RE, Value.SectionID);
1436     }
1437   } else if (Arch == Triple::systemz &&
1438              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1439     // Create function stubs for both PLT and GOT references, regardless of
1440     // whether the GOT reference is to data or code.  The stub contains the
1441     // full address of the symbol, as needed by GOT references, and the
1442     // executable part only adds an overhead of 8 bytes.
1443     //
1444     // We could try to conserve space by allocating the code and data
1445     // parts of the stub separately.  However, as things stand, we allocate
1446     // a stub for every relocation, so using a GOT in JIT code should be
1447     // no less space efficient than using an explicit constant pool.
1448     DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1449     SectionEntry &Section = Sections[SectionID];
1450 
1451     // Look for an existing stub.
1452     StubMap::const_iterator i = Stubs.find(Value);
1453     uintptr_t StubAddress;
1454     if (i != Stubs.end()) {
1455       StubAddress = uintptr_t(Section.Address) + i->second;
1456       DEBUG(dbgs() << " Stub function found\n");
1457     } else {
1458       // Create a new stub function.
1459       DEBUG(dbgs() << " Create a new stub function\n");
1460 
1461       uintptr_t BaseAddress = uintptr_t(Section.Address);
1462       uintptr_t StubAlignment = getStubAlignment();
1463       StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1464                     -StubAlignment;
1465       unsigned StubOffset = StubAddress - BaseAddress;
1466 
1467       Stubs[Value] = StubOffset;
1468       createStubFunction((uint8_t *)StubAddress);
1469       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1470                          Value.Offset);
1471       if (Value.SymbolName)
1472         addRelocationForSymbol(RE, Value.SymbolName);
1473       else
1474         addRelocationForSection(RE, Value.SectionID);
1475       Section.StubOffset = StubOffset + getMaxStubSize();
1476     }
1477 
1478     if (RelType == ELF::R_390_GOTENT)
1479       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1480                         Addend);
1481     else
1482       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1483   } else if (Arch == Triple::x86_64) {
1484     if (RelType == ELF::R_X86_64_PLT32) {
1485       // The way the PLT relocations normally work is that the linker allocates
1486       // the
1487       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1488       // entry will then jump to an address provided by the GOT.  On first call,
1489       // the
1490       // GOT address will point back into PLT code that resolves the symbol. After
1491       // the first call, the GOT entry points to the actual function.
1492       //
1493       // For local functions we're ignoring all of that here and just replacing
1494       // the PLT32 relocation type with PC32, which will translate the relocation
1495       // into a PC-relative call directly to the function. For external symbols we
1496       // can't be sure the function will be within 2^32 bytes of the call site, so
1497       // we need to create a stub, which calls into the GOT.  This case is
1498       // equivalent to the usual PLT implementation except that we use the stub
1499       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1500       // rather than allocating a PLT section.
1501       if (Value.SymbolName) {
1502         // This is a call to an external function.
1503         // Look for an existing stub.
1504         SectionEntry &Section = Sections[SectionID];
1505         StubMap::const_iterator i = Stubs.find(Value);
1506         uintptr_t StubAddress;
1507         if (i != Stubs.end()) {
1508         StubAddress = uintptr_t(Section.Address) + i->second;
1509         DEBUG(dbgs() << " Stub function found\n");
1510         } else {
1511         // Create a new stub function (equivalent to a PLT entry).
1512         DEBUG(dbgs() << " Create a new stub function\n");
1513 
1514         uintptr_t BaseAddress = uintptr_t(Section.Address);
1515         uintptr_t StubAlignment = getStubAlignment();
1516         StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1517                 -StubAlignment;
1518         unsigned StubOffset = StubAddress - BaseAddress;
1519         Stubs[Value] = StubOffset;
1520         createStubFunction((uint8_t *)StubAddress);
1521 
1522         // Bump our stub offset counter
1523         Section.StubOffset = StubOffset + getMaxStubSize();
1524 
1525         // Allocate a GOT Entry
1526         uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1527 
1528         // The load of the GOT address has an addend of -4
1529         resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4);
1530 
1531         // Fill in the value of the symbol we're targeting into the GOT
1532         addRelocationForSymbol(computeGOTOffsetRE(SectionID,GOTOffset,0,ELF::R_X86_64_64),
1533           Value.SymbolName);
1534         }
1535 
1536         // Make the target call a call into the stub table.
1537         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1538                 Addend);
1539       } else {
1540         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1541                   Value.Offset);
1542         addRelocationForSection(RE, Value.SectionID);
1543       }
1544     } else if (RelType == ELF::R_X86_64_GOTPCREL) {
1545       uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1546       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend);
1547 
1548       // Fill in the value of the symbol we're targeting into the GOT
1549       RelocationEntry RE = computeGOTOffsetRE(SectionID, GOTOffset, Value.Offset, ELF::R_X86_64_64);
1550       if (Value.SymbolName)
1551         addRelocationForSymbol(RE, Value.SymbolName);
1552       else
1553         addRelocationForSection(RE, Value.SectionID);
1554     } else if (RelType == ELF::R_X86_64_PC32) {
1555       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1556       processSimpleRelocation(SectionID, Offset, RelType, Value);
1557     } else if (RelType == ELF::R_X86_64_PC64) {
1558       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1559       processSimpleRelocation(SectionID, Offset, RelType, Value);
1560     } else {
1561       processSimpleRelocation(SectionID, Offset, RelType, Value);
1562     }
1563   } else {
1564     if (Arch == Triple::x86) {
1565       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1566     }
1567     processSimpleRelocation(SectionID, Offset, RelType, Value);
1568   }
1569   return ++RelI;
1570 }
1571 
1572 size_t RuntimeDyldELF::getGOTEntrySize() {
1573   // We don't use the GOT in all of these cases, but it's essentially free
1574   // to put them all here.
1575   size_t Result = 0;
1576   switch (Arch) {
1577   case Triple::x86_64:
1578   case Triple::aarch64:
1579   case Triple::aarch64_be:
1580   case Triple::ppc64:
1581   case Triple::ppc64le:
1582   case Triple::systemz:
1583     Result = sizeof(uint64_t);
1584     break;
1585   case Triple::x86:
1586   case Triple::arm:
1587   case Triple::thumb:
1588     Result = sizeof(uint32_t);
1589     break;
1590   case Triple::mips:
1591   case Triple::mipsel:
1592   case Triple::mips64:
1593   case Triple::mips64el:
1594     if (IsMipsO32ABI)
1595       Result = sizeof(uint32_t);
1596     else if (IsMipsN64ABI)
1597       Result = sizeof(uint64_t);
1598     else
1599       llvm_unreachable("Mips ABI not handled");
1600     break;
1601   default:
1602     llvm_unreachable("Unsupported CPU type!");
1603   }
1604   return Result;
1605 }
1606 
1607 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned SectionID, unsigned no)
1608 {
1609   (void)SectionID; // The GOT Section is the same for all section in the object file
1610   if (GOTSectionID == 0) {
1611     GOTSectionID = Sections.size();
1612     // Reserve a section id. We'll allocate the section later
1613     // once we know the total size
1614     Sections.push_back(SectionEntry(".got", 0, 0, 0));
1615   }
1616   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1617   CurrentGOTIndex += no;
1618   return StartOffset;
1619 }
1620 
1621 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset, uint64_t GOTOffset)
1622 {
1623   // Fill in the relative address of the GOT Entry into the stub
1624   RelocationEntry GOTRE(SectionID, Offset, ELF::R_X86_64_PC32, GOTOffset);
1625   addRelocationForSection(GOTRE, GOTSectionID);
1626 }
1627 
1628 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(unsigned SectionID, uint64_t GOTOffset, uint64_t SymbolOffset,
1629                                                    uint32_t Type)
1630 {
1631   (void)SectionID; // The GOT Section is the same for all section in the object file
1632   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1633 }
1634 
1635 void RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1636                                   ObjSectionToIDMap &SectionMap) {
1637   // If necessary, allocate the global offset table
1638   if (GOTSectionID != 0) {
1639     // Allocate memory for the section
1640     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1641     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1642                                                 GOTSectionID, ".got", false);
1643     if (!Addr)
1644       report_fatal_error("Unable to allocate memory for GOT!");
1645 
1646     Sections[GOTSectionID] = SectionEntry(".got", Addr, TotalSize, 0);
1647 
1648     if (Checker)
1649       Checker->registerSection(Obj.getFileName(), GOTSectionID);
1650 
1651     // For now, initialize all GOT entries to zero.  We'll fill them in as
1652     // needed when GOT-based relocations are applied.
1653     memset(Addr, 0, TotalSize);
1654     if (IsMipsN64ABI) {
1655       // To correctly resolve Mips GOT relocations, we need a mapping from
1656       // object's sections to GOTs.
1657       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1658            SI != SE; ++SI) {
1659         if (SI->relocation_begin() != SI->relocation_end()) {
1660           section_iterator RelocatedSection = SI->getRelocatedSection();
1661           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1662           assert (i != SectionMap.end());
1663           SectionToGOTMap[i->second] = GOTSectionID;
1664         }
1665       }
1666       GOTSymbolOffsets.clear();
1667     }
1668   }
1669 
1670   // Look for and record the EH frame section.
1671   ObjSectionToIDMap::iterator i, e;
1672   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1673     const SectionRef &Section = i->first;
1674     StringRef Name;
1675     Section.getName(Name);
1676     if (Name == ".eh_frame") {
1677       UnregisteredEHFrameSections.push_back(i->second);
1678       break;
1679     }
1680   }
1681 
1682   GOTSectionID = 0;
1683   CurrentGOTIndex = 0;
1684 }
1685 
1686 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1687   return Obj.isELF();
1688 }
1689 
1690 } // namespace llvm
1691