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 - FinalAddress, (uint8_t *)TargetPtr, 4);
517     break;
518   }
519   case ELF::R_MIPS_PC16: {
520     uint32_t FinalAddress = (Section.LoadAddress + Offset);
521     Insn &= 0xffff0000;
522     Insn |= ((Value - FinalAddress) >> 2) & 0xffff;
523     writeBytesUnaligned(Insn, TargetPtr, 4);
524     break;
525   }
526   case ELF::R_MIPS_PC19_S2: {
527     uint32_t FinalAddress = (Section.LoadAddress + Offset);
528     Insn &= 0xfff80000;
529     Insn |= ((Value - (FinalAddress & ~0x3)) >> 2) & 0x7ffff;
530     writeBytesUnaligned(Insn, TargetPtr, 4);
531     break;
532   }
533   case ELF::R_MIPS_PC21_S2: {
534     uint32_t FinalAddress = (Section.LoadAddress + Offset);
535     Insn &= 0xffe00000;
536     Insn |= ((Value - FinalAddress) >> 2) & 0x1fffff;
537     writeBytesUnaligned(Insn, TargetPtr, 4);
538     break;
539   }
540   case ELF::R_MIPS_PC26_S2: {
541     uint32_t FinalAddress = (Section.LoadAddress + Offset);
542     Insn &= 0xfc000000;
543     Insn |= ((Value - FinalAddress) >> 2) & 0x3ffffff;
544     writeBytesUnaligned(Insn, TargetPtr, 4);
545     break;
546   }
547   case ELF::R_MIPS_PCHI16: {
548     uint32_t FinalAddress = (Section.LoadAddress + Offset);
549     Insn &= 0xffff0000;
550     Insn |= ((Value - FinalAddress + 0x8000) >> 16) & 0xffff;
551     writeBytesUnaligned(Insn, TargetPtr, 4);
552     break;
553   }
554   case ELF::R_MIPS_PCLO16: {
555     uint32_t FinalAddress = (Section.LoadAddress + Offset);
556     Insn &= 0xffff0000;
557     Insn |= (Value - FinalAddress) & 0xffff;
558     writeBytesUnaligned(Insn, TargetPtr, 4);
559     break;
560   }
561   }
562 }
563 
564 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
565   if (Arch == Triple::UnknownArch ||
566       !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
567     IsMipsO32ABI = false;
568     IsMipsN64ABI = false;
569     return;
570   }
571   unsigned AbiVariant;
572   Obj.getPlatformFlags(AbiVariant);
573   IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
574   IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips");
575   if (AbiVariant & ELF::EF_MIPS_ABI2)
576     llvm_unreachable("Mips N32 ABI is not supported yet");
577 }
578 
579 void RuntimeDyldELF::resolveMIPS64Relocation(const SectionEntry &Section,
580                                              uint64_t Offset, uint64_t Value,
581                                              uint32_t Type, int64_t Addend,
582                                              uint64_t SymOffset,
583                                              SID SectionID) {
584   uint32_t r_type = Type & 0xff;
585   uint32_t r_type2 = (Type >> 8) & 0xff;
586   uint32_t r_type3 = (Type >> 16) & 0xff;
587 
588   // RelType is used to keep information for which relocation type we are
589   // applying relocation.
590   uint32_t RelType = r_type;
591   int64_t CalculatedValue = evaluateMIPS64Relocation(Section, Offset, Value,
592                                                      RelType, Addend,
593                                                      SymOffset, SectionID);
594   if (r_type2 != ELF::R_MIPS_NONE) {
595     RelType = r_type2;
596     CalculatedValue = evaluateMIPS64Relocation(Section, Offset, 0, RelType,
597                                                CalculatedValue, SymOffset,
598                                                SectionID);
599   }
600   if (r_type3 != ELF::R_MIPS_NONE) {
601     RelType = r_type3;
602     CalculatedValue = evaluateMIPS64Relocation(Section, Offset, 0, RelType,
603                                                CalculatedValue, SymOffset,
604                                                SectionID);
605   }
606   applyMIPS64Relocation(Section.Address + Offset, CalculatedValue, RelType);
607 }
608 
609 int64_t
610 RuntimeDyldELF::evaluateMIPS64Relocation(const SectionEntry &Section,
611                                          uint64_t Offset, uint64_t Value,
612                                          uint32_t Type, int64_t Addend,
613                                          uint64_t SymOffset, SID SectionID) {
614 
615   DEBUG(dbgs() << "evaluateMIPS64Relocation, LocalAddress: 0x"
616                << format("%llx", Section.Address + Offset)
617                << " FinalAddress: 0x"
618                << format("%llx", Section.LoadAddress + Offset)
619                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
620                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
621                << " SymOffset: " << format("%x", SymOffset)
622                << "\n");
623 
624   switch (Type) {
625   default:
626     llvm_unreachable("Not implemented relocation type!");
627     break;
628   case ELF::R_MIPS_JALR:
629   case ELF::R_MIPS_NONE:
630     break;
631   case ELF::R_MIPS_32:
632   case ELF::R_MIPS_64:
633     return Value + Addend;
634   case ELF::R_MIPS_26:
635     return ((Value + Addend) >> 2) & 0x3ffffff;
636   case ELF::R_MIPS_GPREL16: {
637     uint64_t GOTAddr = getSectionLoadAddress(SectionToGOTMap[SectionID]);
638     return Value + Addend - (GOTAddr + 0x7ff0);
639   }
640   case ELF::R_MIPS_SUB:
641     return Value - Addend;
642   case ELF::R_MIPS_HI16:
643     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
644     return ((Value + Addend + 0x8000) >> 16) & 0xffff;
645   case ELF::R_MIPS_LO16:
646     return (Value + Addend) & 0xffff;
647   case ELF::R_MIPS_CALL16:
648   case ELF::R_MIPS_GOT_DISP:
649   case ELF::R_MIPS_GOT_PAGE: {
650     uint8_t *LocalGOTAddr =
651         getSectionAddress(SectionToGOTMap[SectionID]) + SymOffset;
652     uint64_t GOTEntry = readBytesUnaligned(LocalGOTAddr, 8);
653 
654     Value += Addend;
655     if (Type == ELF::R_MIPS_GOT_PAGE)
656       Value = (Value + 0x8000) & ~0xffff;
657 
658     if (GOTEntry)
659       assert(GOTEntry == Value &&
660                    "GOT entry has two different addresses.");
661     else
662       writeBytesUnaligned(Value, LocalGOTAddr, 8);
663 
664     return (SymOffset - 0x7ff0) & 0xffff;
665   }
666   case ELF::R_MIPS_GOT_OFST: {
667     int64_t page = (Value + Addend + 0x8000) & ~0xffff;
668     return (Value + Addend - page) & 0xffff;
669   }
670   case ELF::R_MIPS_GPREL32: {
671     uint64_t GOTAddr = getSectionLoadAddress(SectionToGOTMap[SectionID]);
672     return Value + Addend - (GOTAddr + 0x7ff0);
673   }
674   case ELF::R_MIPS_PC16: {
675     uint64_t FinalAddress = (Section.LoadAddress + Offset);
676     return ((Value + Addend - FinalAddress) >> 2) & 0xffff;
677   }
678   case ELF::R_MIPS_PC32: {
679     uint64_t FinalAddress = (Section.LoadAddress + Offset);
680     return Value + Addend - FinalAddress;
681   }
682   case ELF::R_MIPS_PC18_S3: {
683     uint64_t FinalAddress = (Section.LoadAddress + Offset);
684     return ((Value + Addend - ((FinalAddress | 7) ^ 7)) >> 3) & 0x3ffff;
685   }
686   case ELF::R_MIPS_PC19_S2: {
687     uint64_t FinalAddress = (Section.LoadAddress + Offset);
688     return ((Value + Addend - FinalAddress) >> 2) & 0x7ffff;
689   }
690   case ELF::R_MIPS_PC21_S2: {
691     uint64_t FinalAddress = (Section.LoadAddress + Offset);
692     return ((Value + Addend - FinalAddress) >> 2) & 0x1fffff;
693   }
694   case ELF::R_MIPS_PC26_S2: {
695     uint64_t FinalAddress = (Section.LoadAddress + Offset);
696     return ((Value + Addend - FinalAddress) >> 2) & 0x3ffffff;
697   }
698   case ELF::R_MIPS_PCHI16: {
699     uint64_t FinalAddress = (Section.LoadAddress + Offset);
700     return ((Value + Addend - FinalAddress + 0x8000) >> 16) & 0xffff;
701   }
702   case ELF::R_MIPS_PCLO16: {
703     uint64_t FinalAddress = (Section.LoadAddress + Offset);
704     return (Value + Addend - FinalAddress) & 0xffff;
705   }
706   }
707   return 0;
708 }
709 
710 void RuntimeDyldELF::applyMIPS64Relocation(uint8_t *TargetPtr,
711                                            int64_t CalculatedValue,
712                                            uint32_t Type) {
713   uint32_t Insn = readBytesUnaligned(TargetPtr, 4);
714 
715   switch (Type) {
716     default:
717       break;
718     case ELF::R_MIPS_32:
719     case ELF::R_MIPS_GPREL32:
720     case ELF::R_MIPS_PC32:
721       writeBytesUnaligned(CalculatedValue & 0xffffffff, TargetPtr, 4);
722       break;
723     case ELF::R_MIPS_64:
724     case ELF::R_MIPS_SUB:
725       writeBytesUnaligned(CalculatedValue, TargetPtr, 8);
726       break;
727     case ELF::R_MIPS_26:
728     case ELF::R_MIPS_PC26_S2:
729       Insn = (Insn & 0xfc000000) | CalculatedValue;
730       writeBytesUnaligned(Insn, TargetPtr, 4);
731       break;
732     case ELF::R_MIPS_GPREL16:
733       Insn = (Insn & 0xffff0000) | (CalculatedValue & 0xffff);
734       writeBytesUnaligned(Insn, TargetPtr, 4);
735       break;
736     case ELF::R_MIPS_HI16:
737     case ELF::R_MIPS_LO16:
738     case ELF::R_MIPS_PCHI16:
739     case ELF::R_MIPS_PCLO16:
740     case ELF::R_MIPS_PC16:
741     case ELF::R_MIPS_CALL16:
742     case ELF::R_MIPS_GOT_DISP:
743     case ELF::R_MIPS_GOT_PAGE:
744     case ELF::R_MIPS_GOT_OFST:
745       Insn = (Insn & 0xffff0000) | CalculatedValue;
746       writeBytesUnaligned(Insn, TargetPtr, 4);
747       break;
748     case ELF::R_MIPS_PC18_S3:
749       Insn = (Insn & 0xfffc0000) | CalculatedValue;
750       writeBytesUnaligned(Insn, TargetPtr, 4);
751       break;
752     case ELF::R_MIPS_PC19_S2:
753       Insn = (Insn & 0xfff80000) | CalculatedValue;
754       writeBytesUnaligned(Insn, TargetPtr, 4);
755       break;
756     case ELF::R_MIPS_PC21_S2:
757       Insn = (Insn & 0xffe00000) | CalculatedValue;
758       writeBytesUnaligned(Insn, TargetPtr, 4);
759       break;
760     }
761 }
762 
763 // Return the .TOC. section and offset.
764 void RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
765                                          ObjSectionToIDMap &LocalSections,
766                                          RelocationValueRef &Rel) {
767   // Set a default SectionID in case we do not find a TOC section below.
768   // This may happen for references to TOC base base (sym@toc, .odp
769   // relocation) without a .toc directive.  In this case just use the
770   // first section (which is usually the .odp) since the code won't
771   // reference the .toc base directly.
772   Rel.SymbolName = NULL;
773   Rel.SectionID = 0;
774 
775   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
776   // order. The TOC starts where the first of these sections starts.
777   for (auto &Section: Obj.sections()) {
778     StringRef SectionName;
779     check(Section.getName(SectionName));
780 
781     if (SectionName == ".got"
782         || SectionName == ".toc"
783         || SectionName == ".tocbss"
784         || SectionName == ".plt") {
785       Rel.SectionID = findOrEmitSection(Obj, Section, false, LocalSections);
786       break;
787     }
788   }
789 
790   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
791   // thus permitting a full 64 Kbytes segment.
792   Rel.Addend = 0x8000;
793 }
794 
795 // Returns the sections and offset associated with the ODP entry referenced
796 // by Symbol.
797 void RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
798                                          ObjSectionToIDMap &LocalSections,
799                                          RelocationValueRef &Rel) {
800   // Get the ELF symbol value (st_value) to compare with Relocation offset in
801   // .opd entries
802   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
803        si != se; ++si) {
804     section_iterator RelSecI = si->getRelocatedSection();
805     if (RelSecI == Obj.section_end())
806       continue;
807 
808     StringRef RelSectionName;
809     check(RelSecI->getName(RelSectionName));
810     if (RelSectionName != ".opd")
811       continue;
812 
813     for (elf_relocation_iterator i = si->relocation_begin(),
814                                  e = si->relocation_end();
815          i != e;) {
816       // The R_PPC64_ADDR64 relocation indicates the first field
817       // of a .opd entry
818       uint64_t TypeFunc = i->getType();
819       if (TypeFunc != ELF::R_PPC64_ADDR64) {
820         ++i;
821         continue;
822       }
823 
824       uint64_t TargetSymbolOffset = i->getOffset();
825       symbol_iterator TargetSymbol = i->getSymbol();
826       ErrorOr<int64_t> AddendOrErr = i->getAddend();
827       Check(AddendOrErr.getError());
828       int64_t Addend = *AddendOrErr;
829 
830       ++i;
831       if (i == e)
832         break;
833 
834       // Just check if following relocation is a R_PPC64_TOC
835       uint64_t TypeTOC = i->getType();
836       if (TypeTOC != ELF::R_PPC64_TOC)
837         continue;
838 
839       // Finally compares the Symbol value and the target symbol offset
840       // to check if this .opd entry refers to the symbol the relocation
841       // points to.
842       if (Rel.Addend != (int64_t)TargetSymbolOffset)
843         continue;
844 
845       section_iterator tsi(Obj.section_end());
846       check(TargetSymbol->getSection(tsi));
847       bool IsCode = tsi->isText();
848       Rel.SectionID = findOrEmitSection(Obj, (*tsi), IsCode, LocalSections);
849       Rel.Addend = (intptr_t)Addend;
850       return;
851     }
852   }
853   llvm_unreachable("Attempting to get address of ODP entry!");
854 }
855 
856 // Relocation masks following the #lo(value), #hi(value), #ha(value),
857 // #higher(value), #highera(value), #highest(value), and #highesta(value)
858 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
859 // document.
860 
861 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
862 
863 static inline uint16_t applyPPChi(uint64_t value) {
864   return (value >> 16) & 0xffff;
865 }
866 
867 static inline uint16_t applyPPCha (uint64_t value) {
868   return ((value + 0x8000) >> 16) & 0xffff;
869 }
870 
871 static inline uint16_t applyPPChigher(uint64_t value) {
872   return (value >> 32) & 0xffff;
873 }
874 
875 static inline uint16_t applyPPChighera (uint64_t value) {
876   return ((value + 0x8000) >> 32) & 0xffff;
877 }
878 
879 static inline uint16_t applyPPChighest(uint64_t value) {
880   return (value >> 48) & 0xffff;
881 }
882 
883 static inline uint16_t applyPPChighesta (uint64_t value) {
884   return ((value + 0x8000) >> 48) & 0xffff;
885 }
886 
887 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
888                                             uint64_t Offset, uint64_t Value,
889                                             uint32_t Type, int64_t Addend) {
890   uint8_t *LocalAddress = Section.Address + Offset;
891   switch (Type) {
892   default:
893     llvm_unreachable("Relocation type not implemented yet!");
894     break;
895   case ELF::R_PPC64_ADDR16:
896     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
897     break;
898   case ELF::R_PPC64_ADDR16_DS:
899     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
900     break;
901   case ELF::R_PPC64_ADDR16_LO:
902     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
903     break;
904   case ELF::R_PPC64_ADDR16_LO_DS:
905     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
906     break;
907   case ELF::R_PPC64_ADDR16_HI:
908     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
909     break;
910   case ELF::R_PPC64_ADDR16_HA:
911     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
912     break;
913   case ELF::R_PPC64_ADDR16_HIGHER:
914     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
915     break;
916   case ELF::R_PPC64_ADDR16_HIGHERA:
917     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
918     break;
919   case ELF::R_PPC64_ADDR16_HIGHEST:
920     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
921     break;
922   case ELF::R_PPC64_ADDR16_HIGHESTA:
923     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
924     break;
925   case ELF::R_PPC64_ADDR14: {
926     assert(((Value + Addend) & 3) == 0);
927     // Preserve the AA/LK bits in the branch instruction
928     uint8_t aalk = *(LocalAddress + 3);
929     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
930   } break;
931   case ELF::R_PPC64_REL16_LO: {
932     uint64_t FinalAddress = (Section.LoadAddress + Offset);
933     uint64_t Delta = Value - FinalAddress + Addend;
934     writeInt16BE(LocalAddress, applyPPClo(Delta));
935   } break;
936   case ELF::R_PPC64_REL16_HI: {
937     uint64_t FinalAddress = (Section.LoadAddress + Offset);
938     uint64_t Delta = Value - FinalAddress + Addend;
939     writeInt16BE(LocalAddress, applyPPChi(Delta));
940   } break;
941   case ELF::R_PPC64_REL16_HA: {
942     uint64_t FinalAddress = (Section.LoadAddress + Offset);
943     uint64_t Delta = Value - FinalAddress + Addend;
944     writeInt16BE(LocalAddress, applyPPCha(Delta));
945   } break;
946   case ELF::R_PPC64_ADDR32: {
947     int32_t Result = static_cast<int32_t>(Value + Addend);
948     if (SignExtend32<32>(Result) != Result)
949       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
950     writeInt32BE(LocalAddress, Result);
951   } break;
952   case ELF::R_PPC64_REL24: {
953     uint64_t FinalAddress = (Section.LoadAddress + Offset);
954     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
955     if (SignExtend32<24>(delta) != delta)
956       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
957     // Generates a 'bl <address>' instruction
958     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
959   } break;
960   case ELF::R_PPC64_REL32: {
961     uint64_t FinalAddress = (Section.LoadAddress + Offset);
962     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
963     if (SignExtend32<32>(delta) != delta)
964       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
965     writeInt32BE(LocalAddress, delta);
966   } break;
967   case ELF::R_PPC64_REL64: {
968     uint64_t FinalAddress = (Section.LoadAddress + Offset);
969     uint64_t Delta = Value - FinalAddress + Addend;
970     writeInt64BE(LocalAddress, Delta);
971   } break;
972   case ELF::R_PPC64_ADDR64:
973     writeInt64BE(LocalAddress, Value + Addend);
974     break;
975   }
976 }
977 
978 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
979                                               uint64_t Offset, uint64_t Value,
980                                               uint32_t Type, int64_t Addend) {
981   uint8_t *LocalAddress = Section.Address + Offset;
982   switch (Type) {
983   default:
984     llvm_unreachable("Relocation type not implemented yet!");
985     break;
986   case ELF::R_390_PC16DBL:
987   case ELF::R_390_PLT16DBL: {
988     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
989     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
990     writeInt16BE(LocalAddress, Delta / 2);
991     break;
992   }
993   case ELF::R_390_PC32DBL:
994   case ELF::R_390_PLT32DBL: {
995     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
996     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
997     writeInt32BE(LocalAddress, Delta / 2);
998     break;
999   }
1000   case ELF::R_390_PC32: {
1001     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
1002     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
1003     writeInt32BE(LocalAddress, Delta);
1004     break;
1005   }
1006   case ELF::R_390_64:
1007     writeInt64BE(LocalAddress, Value + Addend);
1008     break;
1009   }
1010 }
1011 
1012 // The target location for the relocation is described by RE.SectionID and
1013 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
1014 // SectionEntry has three members describing its location.
1015 // SectionEntry::Address is the address at which the section has been loaded
1016 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
1017 // address that the section will have in the target process.
1018 // SectionEntry::ObjAddress is the address of the bits for this section in the
1019 // original emitted object image (also in the current address space).
1020 //
1021 // Relocations will be applied as if the section were loaded at
1022 // SectionEntry::LoadAddress, but they will be applied at an address based
1023 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
1024 // Target memory contents if they are required for value calculations.
1025 //
1026 // The Value parameter here is the load address of the symbol for the
1027 // relocation to be applied.  For relocations which refer to symbols in the
1028 // current object Value will be the LoadAddress of the section in which
1029 // the symbol resides (RE.Addend provides additional information about the
1030 // symbol location).  For external symbols, Value will be the address of the
1031 // symbol in the target address space.
1032 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
1033                                        uint64_t Value) {
1034   const SectionEntry &Section = Sections[RE.SectionID];
1035   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
1036                            RE.SymOffset, RE.SectionID);
1037 }
1038 
1039 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
1040                                        uint64_t Offset, uint64_t Value,
1041                                        uint32_t Type, int64_t Addend,
1042                                        uint64_t SymOffset, SID SectionID) {
1043   switch (Arch) {
1044   case Triple::x86_64:
1045     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
1046     break;
1047   case Triple::x86:
1048     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
1049                          (uint32_t)(Addend & 0xffffffffL));
1050     break;
1051   case Triple::aarch64:
1052   case Triple::aarch64_be:
1053     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
1054     break;
1055   case Triple::arm: // Fall through.
1056   case Triple::armeb:
1057   case Triple::thumb:
1058   case Triple::thumbeb:
1059     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
1060                          (uint32_t)(Addend & 0xffffffffL));
1061     break;
1062   case Triple::mips: // Fall through.
1063   case Triple::mipsel:
1064   case Triple::mips64:
1065   case Triple::mips64el:
1066     if (IsMipsO32ABI)
1067       resolveMIPSRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL),
1068                             Type, (uint32_t)(Addend & 0xffffffffL));
1069     else if (IsMipsN64ABI)
1070       resolveMIPS64Relocation(Section, Offset, Value, Type, Addend, SymOffset,
1071                               SectionID);
1072     else
1073       llvm_unreachable("Mips ABI not handled");
1074     break;
1075   case Triple::ppc64: // Fall through.
1076   case Triple::ppc64le:
1077     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
1078     break;
1079   case Triple::systemz:
1080     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
1081     break;
1082   default:
1083     llvm_unreachable("Unsupported CPU type!");
1084   }
1085 }
1086 
1087 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
1088   return (void*)(Sections[SectionID].ObjAddress + Offset);
1089 }
1090 
1091 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
1092   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
1093   if (Value.SymbolName)
1094     addRelocationForSymbol(RE, Value.SymbolName);
1095   else
1096     addRelocationForSection(RE, Value.SectionID);
1097 }
1098 
1099 relocation_iterator RuntimeDyldELF::processRelocationRef(
1100     unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1101     ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1102   const auto &Obj = cast<ELFObjectFileBase>(O);
1103   uint64_t RelType = RelI->getType();
1104   ErrorOr<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend();
1105   int64_t Addend = AddendOrErr ? *AddendOrErr : 0;
1106   elf_symbol_iterator Symbol = RelI->getSymbol();
1107 
1108   // Obtain the symbol name which is referenced in the relocation
1109   StringRef TargetName;
1110   if (Symbol != Obj.symbol_end()) {
1111     ErrorOr<StringRef> TargetNameOrErr = Symbol->getName();
1112     if (std::error_code EC = TargetNameOrErr.getError())
1113       report_fatal_error(EC.message());
1114     TargetName = *TargetNameOrErr;
1115   }
1116   DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1117                << " TargetName: " << TargetName << "\n");
1118   RelocationValueRef Value;
1119   // First search for the symbol in the local symbol table
1120   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1121 
1122   // Search for the symbol in the global symbol table
1123   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1124   if (Symbol != Obj.symbol_end()) {
1125     gsi = GlobalSymbolTable.find(TargetName.data());
1126     SymType = Symbol->getType();
1127   }
1128   if (gsi != GlobalSymbolTable.end()) {
1129     const auto &SymInfo = gsi->second;
1130     Value.SectionID = SymInfo.getSectionID();
1131     Value.Offset = SymInfo.getOffset();
1132     Value.Addend = SymInfo.getOffset() + Addend;
1133   } else {
1134     switch (SymType) {
1135     case SymbolRef::ST_Debug: {
1136       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1137       // and can be changed by another developers. Maybe best way is add
1138       // a new symbol type ST_Section to SymbolRef and use it.
1139       section_iterator si(Obj.section_end());
1140       Symbol->getSection(si);
1141       if (si == Obj.section_end())
1142         llvm_unreachable("Symbol section not found, bad object file format!");
1143       DEBUG(dbgs() << "\t\tThis is section symbol\n");
1144       bool isCode = si->isText();
1145       Value.SectionID = findOrEmitSection(Obj, (*si), isCode, ObjSectionToID);
1146       Value.Addend = Addend;
1147       break;
1148     }
1149     case SymbolRef::ST_Data:
1150     case SymbolRef::ST_Unknown: {
1151       Value.SymbolName = TargetName.data();
1152       Value.Addend = Addend;
1153 
1154       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1155       // will manifest here as a NULL symbol name.
1156       // We can set this as a valid (but empty) symbol name, and rely
1157       // on addRelocationForSymbol to handle this.
1158       if (!Value.SymbolName)
1159         Value.SymbolName = "";
1160       break;
1161     }
1162     default:
1163       llvm_unreachable("Unresolved symbol type!");
1164       break;
1165     }
1166   }
1167 
1168   uint64_t Offset = RelI->getOffset();
1169 
1170   DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1171                << "\n");
1172   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be) &&
1173       (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26)) {
1174     // This is an AArch64 branch relocation, need to use a stub function.
1175     DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1176     SectionEntry &Section = Sections[SectionID];
1177 
1178     // Look for an existing stub.
1179     StubMap::const_iterator i = Stubs.find(Value);
1180     if (i != Stubs.end()) {
1181       resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
1182                         RelType, 0);
1183       DEBUG(dbgs() << " Stub function found\n");
1184     } else {
1185       // Create a new stub function.
1186       DEBUG(dbgs() << " Create a new stub function\n");
1187       Stubs[Value] = Section.StubOffset;
1188       uint8_t *StubTargetAddr =
1189           createStubFunction(Section.Address + Section.StubOffset);
1190 
1191       RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.Address,
1192                                 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1193       RelocationEntry REmovk_g2(SectionID, StubTargetAddr - Section.Address + 4,
1194                                 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1195       RelocationEntry REmovk_g1(SectionID, StubTargetAddr - Section.Address + 8,
1196                                 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1197       RelocationEntry REmovk_g0(SectionID,
1198                                 StubTargetAddr - Section.Address + 12,
1199                                 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1200 
1201       if (Value.SymbolName) {
1202         addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1203         addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1204         addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1205         addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1206       } else {
1207         addRelocationForSection(REmovz_g3, Value.SectionID);
1208         addRelocationForSection(REmovk_g2, Value.SectionID);
1209         addRelocationForSection(REmovk_g1, Value.SectionID);
1210         addRelocationForSection(REmovk_g0, Value.SectionID);
1211       }
1212       resolveRelocation(Section, Offset,
1213                         (uint64_t)Section.Address + Section.StubOffset, RelType,
1214                         0);
1215       Section.StubOffset += getMaxStubSize();
1216     }
1217   } else if (Arch == Triple::arm) {
1218     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1219       RelType == ELF::R_ARM_JUMP24) {
1220       // This is an ARM branch relocation, need to use a stub function.
1221       DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
1222       SectionEntry &Section = Sections[SectionID];
1223 
1224       // Look for an existing stub.
1225       StubMap::const_iterator i = Stubs.find(Value);
1226       if (i != Stubs.end()) {
1227         resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
1228           RelType, 0);
1229         DEBUG(dbgs() << " Stub function found\n");
1230       } else {
1231         // Create a new stub function.
1232         DEBUG(dbgs() << " Create a new stub function\n");
1233         Stubs[Value] = Section.StubOffset;
1234         uint8_t *StubTargetAddr =
1235           createStubFunction(Section.Address + Section.StubOffset);
1236         RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1237           ELF::R_ARM_ABS32, Value.Addend);
1238         if (Value.SymbolName)
1239           addRelocationForSymbol(RE, Value.SymbolName);
1240         else
1241           addRelocationForSection(RE, Value.SectionID);
1242 
1243         resolveRelocation(Section, Offset,
1244           (uint64_t)Section.Address + Section.StubOffset, RelType,
1245           0);
1246         Section.StubOffset += getMaxStubSize();
1247       }
1248     } else {
1249       uint32_t *Placeholder =
1250         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1251       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1252           RelType == ELF::R_ARM_ABS32) {
1253         Value.Addend += *Placeholder;
1254       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1255         // See ELF for ARM documentation
1256         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1257       }
1258       processSimpleRelocation(SectionID, Offset, RelType, Value);
1259     }
1260   } else if (IsMipsO32ABI) {
1261     uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1262         computePlaceholderAddress(SectionID, Offset));
1263     uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1264     if (RelType == ELF::R_MIPS_26) {
1265       // This is an Mips branch relocation, need to use a stub function.
1266       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1267       SectionEntry &Section = Sections[SectionID];
1268 
1269       // Extract the addend from the instruction.
1270       // We shift up by two since the Value will be down shifted again
1271       // when applying the relocation.
1272       uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1273 
1274       Value.Addend += Addend;
1275 
1276       //  Look up for existing stub.
1277       StubMap::const_iterator i = Stubs.find(Value);
1278       if (i != Stubs.end()) {
1279         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1280         addRelocationForSection(RE, SectionID);
1281         DEBUG(dbgs() << " Stub function found\n");
1282       } else {
1283         // Create a new stub function.
1284         DEBUG(dbgs() << " Create a new stub function\n");
1285         Stubs[Value] = Section.StubOffset;
1286         uint8_t *StubTargetAddr =
1287           createStubFunction(Section.Address + Section.StubOffset);
1288 
1289         // Creating Hi and Lo relocations for the filled stub instructions.
1290         RelocationEntry REHi(SectionID, StubTargetAddr - Section.Address,
1291           ELF::R_MIPS_HI16, Value.Addend);
1292         RelocationEntry RELo(SectionID, StubTargetAddr - Section.Address + 4,
1293           ELF::R_MIPS_LO16, Value.Addend);
1294 
1295         if (Value.SymbolName) {
1296           addRelocationForSymbol(REHi, Value.SymbolName);
1297           addRelocationForSymbol(RELo, Value.SymbolName);
1298         }
1299         else {
1300           addRelocationForSection(REHi, Value.SectionID);
1301           addRelocationForSection(RELo, Value.SectionID);
1302         }
1303 
1304         RelocationEntry RE(SectionID, Offset, RelType, Section.StubOffset);
1305         addRelocationForSection(RE, SectionID);
1306         Section.StubOffset += getMaxStubSize();
1307       }
1308     } else {
1309       // FIXME: Calculate correct addends for R_MIPS_HI16, R_MIPS_LO16,
1310       // R_MIPS_PCHI16 and R_MIPS_PCLO16 relocations.
1311       if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16)
1312         Value.Addend += (Opcode & 0x0000ffff) << 16;
1313       else if (RelType == ELF::R_MIPS_LO16)
1314         Value.Addend += (Opcode & 0x0000ffff);
1315       else if (RelType == ELF::R_MIPS_32)
1316         Value.Addend += Opcode;
1317       else if (RelType == ELF::R_MIPS_PCLO16)
1318         Value.Addend += SignExtend32<16>((Opcode & 0x0000ffff));
1319       else if (RelType == ELF::R_MIPS_PC16)
1320         Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1321       else if (RelType == ELF::R_MIPS_PC19_S2)
1322         Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1323       else if (RelType == ELF::R_MIPS_PC21_S2)
1324         Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1325       else if (RelType == ELF::R_MIPS_PC26_S2)
1326         Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1327       processSimpleRelocation(SectionID, Offset, RelType, Value);
1328     }
1329   } else if (IsMipsN64ABI) {
1330     uint32_t r_type = RelType & 0xff;
1331     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1332     if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1333         || r_type == ELF::R_MIPS_GOT_DISP) {
1334       StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1335       if (i != GOTSymbolOffsets.end())
1336         RE.SymOffset = i->second;
1337       else {
1338         RE.SymOffset = allocateGOTEntries(SectionID, 1);
1339         GOTSymbolOffsets[TargetName] = RE.SymOffset;
1340       }
1341     }
1342     if (Value.SymbolName)
1343       addRelocationForSymbol(RE, Value.SymbolName);
1344     else
1345       addRelocationForSection(RE, Value.SectionID);
1346   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1347     if (RelType == ELF::R_PPC64_REL24) {
1348       // Determine ABI variant in use for this object.
1349       unsigned AbiVariant;
1350       Obj.getPlatformFlags(AbiVariant);
1351       AbiVariant &= ELF::EF_PPC64_ABI;
1352       // A PPC branch relocation will need a stub function if the target is
1353       // an external symbol (Symbol::ST_Unknown) or if the target address
1354       // is not within the signed 24-bits branch address.
1355       SectionEntry &Section = Sections[SectionID];
1356       uint8_t *Target = Section.Address + Offset;
1357       bool RangeOverflow = false;
1358       if (SymType != SymbolRef::ST_Unknown) {
1359         if (AbiVariant != 2) {
1360           // In the ELFv1 ABI, a function call may point to the .opd entry,
1361           // so the final symbol value is calculated based on the relocation
1362           // values in the .opd section.
1363           findOPDEntrySection(Obj, ObjSectionToID, Value);
1364         } else {
1365           // In the ELFv2 ABI, a function symbol may provide a local entry
1366           // point, which must be used for direct calls.
1367           uint8_t SymOther = Symbol->getOther();
1368           Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1369         }
1370         uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
1371         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
1372         // If it is within 24-bits branch range, just set the branch target
1373         if (SignExtend32<24>(delta) == delta) {
1374           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1375           if (Value.SymbolName)
1376             addRelocationForSymbol(RE, Value.SymbolName);
1377           else
1378             addRelocationForSection(RE, Value.SectionID);
1379         } else {
1380           RangeOverflow = true;
1381         }
1382       }
1383       if (SymType == SymbolRef::ST_Unknown || RangeOverflow) {
1384         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
1385         // larger than 24-bits.
1386         StubMap::const_iterator i = Stubs.find(Value);
1387         if (i != Stubs.end()) {
1388           // Symbol function stub already created, just relocate to it
1389           resolveRelocation(Section, Offset,
1390                             (uint64_t)Section.Address + i->second, RelType, 0);
1391           DEBUG(dbgs() << " Stub function found\n");
1392         } else {
1393           // Create a new stub function.
1394           DEBUG(dbgs() << " Create a new stub function\n");
1395           Stubs[Value] = Section.StubOffset;
1396           uint8_t *StubTargetAddr =
1397               createStubFunction(Section.Address + Section.StubOffset,
1398                                  AbiVariant);
1399           RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1400                              ELF::R_PPC64_ADDR64, Value.Addend);
1401 
1402           // Generates the 64-bits address loads as exemplified in section
1403           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1404           // apply to the low part of the instructions, so we have to update
1405           // the offset according to the target endianness.
1406           uint64_t StubRelocOffset = StubTargetAddr - Section.Address;
1407           if (!IsTargetLittleEndian)
1408             StubRelocOffset += 2;
1409 
1410           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1411                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1412           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1413                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1414           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1415                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1416           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1417                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1418 
1419           if (Value.SymbolName) {
1420             addRelocationForSymbol(REhst, Value.SymbolName);
1421             addRelocationForSymbol(REhr, Value.SymbolName);
1422             addRelocationForSymbol(REh, Value.SymbolName);
1423             addRelocationForSymbol(REl, Value.SymbolName);
1424           } else {
1425             addRelocationForSection(REhst, Value.SectionID);
1426             addRelocationForSection(REhr, Value.SectionID);
1427             addRelocationForSection(REh, Value.SectionID);
1428             addRelocationForSection(REl, Value.SectionID);
1429           }
1430 
1431           resolveRelocation(Section, Offset,
1432                             (uint64_t)Section.Address + Section.StubOffset,
1433                             RelType, 0);
1434           Section.StubOffset += getMaxStubSize();
1435         }
1436         if (SymType == SymbolRef::ST_Unknown) {
1437           // Restore the TOC for external calls
1438           if (AbiVariant == 2)
1439             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
1440           else
1441             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1442         }
1443       }
1444     } else if (RelType == ELF::R_PPC64_TOC16 ||
1445                RelType == ELF::R_PPC64_TOC16_DS ||
1446                RelType == ELF::R_PPC64_TOC16_LO ||
1447                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1448                RelType == ELF::R_PPC64_TOC16_HI ||
1449                RelType == ELF::R_PPC64_TOC16_HA) {
1450       // These relocations are supposed to subtract the TOC address from
1451       // the final value.  This does not fit cleanly into the RuntimeDyld
1452       // scheme, since there may be *two* sections involved in determining
1453       // the relocation value (the section of the symbol refered to by the
1454       // relocation, and the TOC section associated with the current module).
1455       //
1456       // Fortunately, these relocations are currently only ever generated
1457       // refering to symbols that themselves reside in the TOC, which means
1458       // that the two sections are actually the same.  Thus they cancel out
1459       // and we can immediately resolve the relocation right now.
1460       switch (RelType) {
1461       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1462       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1463       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1464       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1465       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1466       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1467       default: llvm_unreachable("Wrong relocation type.");
1468       }
1469 
1470       RelocationValueRef TOCValue;
1471       findPPC64TOCSection(Obj, ObjSectionToID, TOCValue);
1472       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1473         llvm_unreachable("Unsupported TOC relocation.");
1474       Value.Addend -= TOCValue.Addend;
1475       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1476     } else {
1477       // There are two ways to refer to the TOC address directly: either
1478       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1479       // ignored), or via any relocation that refers to the magic ".TOC."
1480       // symbols (in which case the addend is respected).
1481       if (RelType == ELF::R_PPC64_TOC) {
1482         RelType = ELF::R_PPC64_ADDR64;
1483         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1484       } else if (TargetName == ".TOC.") {
1485         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1486         Value.Addend += Addend;
1487       }
1488 
1489       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1490 
1491       if (Value.SymbolName)
1492         addRelocationForSymbol(RE, Value.SymbolName);
1493       else
1494         addRelocationForSection(RE, Value.SectionID);
1495     }
1496   } else if (Arch == Triple::systemz &&
1497              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1498     // Create function stubs for both PLT and GOT references, regardless of
1499     // whether the GOT reference is to data or code.  The stub contains the
1500     // full address of the symbol, as needed by GOT references, and the
1501     // executable part only adds an overhead of 8 bytes.
1502     //
1503     // We could try to conserve space by allocating the code and data
1504     // parts of the stub separately.  However, as things stand, we allocate
1505     // a stub for every relocation, so using a GOT in JIT code should be
1506     // no less space efficient than using an explicit constant pool.
1507     DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1508     SectionEntry &Section = Sections[SectionID];
1509 
1510     // Look for an existing stub.
1511     StubMap::const_iterator i = Stubs.find(Value);
1512     uintptr_t StubAddress;
1513     if (i != Stubs.end()) {
1514       StubAddress = uintptr_t(Section.Address) + i->second;
1515       DEBUG(dbgs() << " Stub function found\n");
1516     } else {
1517       // Create a new stub function.
1518       DEBUG(dbgs() << " Create a new stub function\n");
1519 
1520       uintptr_t BaseAddress = uintptr_t(Section.Address);
1521       uintptr_t StubAlignment = getStubAlignment();
1522       StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1523                     -StubAlignment;
1524       unsigned StubOffset = StubAddress - BaseAddress;
1525 
1526       Stubs[Value] = StubOffset;
1527       createStubFunction((uint8_t *)StubAddress);
1528       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1529                          Value.Offset);
1530       if (Value.SymbolName)
1531         addRelocationForSymbol(RE, Value.SymbolName);
1532       else
1533         addRelocationForSection(RE, Value.SectionID);
1534       Section.StubOffset = StubOffset + getMaxStubSize();
1535     }
1536 
1537     if (RelType == ELF::R_390_GOTENT)
1538       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1539                         Addend);
1540     else
1541       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1542   } else if (Arch == Triple::x86_64) {
1543     if (RelType == ELF::R_X86_64_PLT32) {
1544       // The way the PLT relocations normally work is that the linker allocates
1545       // the
1546       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1547       // entry will then jump to an address provided by the GOT.  On first call,
1548       // the
1549       // GOT address will point back into PLT code that resolves the symbol. After
1550       // the first call, the GOT entry points to the actual function.
1551       //
1552       // For local functions we're ignoring all of that here and just replacing
1553       // the PLT32 relocation type with PC32, which will translate the relocation
1554       // into a PC-relative call directly to the function. For external symbols we
1555       // can't be sure the function will be within 2^32 bytes of the call site, so
1556       // we need to create a stub, which calls into the GOT.  This case is
1557       // equivalent to the usual PLT implementation except that we use the stub
1558       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1559       // rather than allocating a PLT section.
1560       if (Value.SymbolName) {
1561         // This is a call to an external function.
1562         // Look for an existing stub.
1563         SectionEntry &Section = Sections[SectionID];
1564         StubMap::const_iterator i = Stubs.find(Value);
1565         uintptr_t StubAddress;
1566         if (i != Stubs.end()) {
1567         StubAddress = uintptr_t(Section.Address) + i->second;
1568         DEBUG(dbgs() << " Stub function found\n");
1569         } else {
1570         // Create a new stub function (equivalent to a PLT entry).
1571         DEBUG(dbgs() << " Create a new stub function\n");
1572 
1573         uintptr_t BaseAddress = uintptr_t(Section.Address);
1574         uintptr_t StubAlignment = getStubAlignment();
1575         StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1576                 -StubAlignment;
1577         unsigned StubOffset = StubAddress - BaseAddress;
1578         Stubs[Value] = StubOffset;
1579         createStubFunction((uint8_t *)StubAddress);
1580 
1581         // Bump our stub offset counter
1582         Section.StubOffset = StubOffset + getMaxStubSize();
1583 
1584         // Allocate a GOT Entry
1585         uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1586 
1587         // The load of the GOT address has an addend of -4
1588         resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4);
1589 
1590         // Fill in the value of the symbol we're targeting into the GOT
1591         addRelocationForSymbol(computeGOTOffsetRE(SectionID,GOTOffset,0,ELF::R_X86_64_64),
1592           Value.SymbolName);
1593         }
1594 
1595         // Make the target call a call into the stub table.
1596         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1597                 Addend);
1598       } else {
1599         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1600                   Value.Offset);
1601         addRelocationForSection(RE, Value.SectionID);
1602       }
1603     } else if (RelType == ELF::R_X86_64_GOTPCREL) {
1604       uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1605       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend);
1606 
1607       // Fill in the value of the symbol we're targeting into the GOT
1608       RelocationEntry RE = computeGOTOffsetRE(SectionID, GOTOffset, Value.Offset, ELF::R_X86_64_64);
1609       if (Value.SymbolName)
1610         addRelocationForSymbol(RE, Value.SymbolName);
1611       else
1612         addRelocationForSection(RE, Value.SectionID);
1613     } else if (RelType == ELF::R_X86_64_PC32) {
1614       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1615       processSimpleRelocation(SectionID, Offset, RelType, Value);
1616     } else if (RelType == ELF::R_X86_64_PC64) {
1617       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1618       processSimpleRelocation(SectionID, Offset, RelType, Value);
1619     } else {
1620       processSimpleRelocation(SectionID, Offset, RelType, Value);
1621     }
1622   } else {
1623     if (Arch == Triple::x86) {
1624       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1625     }
1626     processSimpleRelocation(SectionID, Offset, RelType, Value);
1627   }
1628   return ++RelI;
1629 }
1630 
1631 size_t RuntimeDyldELF::getGOTEntrySize() {
1632   // We don't use the GOT in all of these cases, but it's essentially free
1633   // to put them all here.
1634   size_t Result = 0;
1635   switch (Arch) {
1636   case Triple::x86_64:
1637   case Triple::aarch64:
1638   case Triple::aarch64_be:
1639   case Triple::ppc64:
1640   case Triple::ppc64le:
1641   case Triple::systemz:
1642     Result = sizeof(uint64_t);
1643     break;
1644   case Triple::x86:
1645   case Triple::arm:
1646   case Triple::thumb:
1647     Result = sizeof(uint32_t);
1648     break;
1649   case Triple::mips:
1650   case Triple::mipsel:
1651   case Triple::mips64:
1652   case Triple::mips64el:
1653     if (IsMipsO32ABI)
1654       Result = sizeof(uint32_t);
1655     else if (IsMipsN64ABI)
1656       Result = sizeof(uint64_t);
1657     else
1658       llvm_unreachable("Mips ABI not handled");
1659     break;
1660   default:
1661     llvm_unreachable("Unsupported CPU type!");
1662   }
1663   return Result;
1664 }
1665 
1666 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned SectionID, unsigned no)
1667 {
1668   (void)SectionID; // The GOT Section is the same for all section in the object file
1669   if (GOTSectionID == 0) {
1670     GOTSectionID = Sections.size();
1671     // Reserve a section id. We'll allocate the section later
1672     // once we know the total size
1673     Sections.push_back(SectionEntry(".got", 0, 0, 0));
1674   }
1675   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1676   CurrentGOTIndex += no;
1677   return StartOffset;
1678 }
1679 
1680 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset, uint64_t GOTOffset)
1681 {
1682   // Fill in the relative address of the GOT Entry into the stub
1683   RelocationEntry GOTRE(SectionID, Offset, ELF::R_X86_64_PC32, GOTOffset);
1684   addRelocationForSection(GOTRE, GOTSectionID);
1685 }
1686 
1687 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(unsigned SectionID, uint64_t GOTOffset, uint64_t SymbolOffset,
1688                                                    uint32_t Type)
1689 {
1690   (void)SectionID; // The GOT Section is the same for all section in the object file
1691   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1692 }
1693 
1694 void RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1695                                   ObjSectionToIDMap &SectionMap) {
1696   // If necessary, allocate the global offset table
1697   if (GOTSectionID != 0) {
1698     // Allocate memory for the section
1699     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1700     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1701                                                 GOTSectionID, ".got", false);
1702     if (!Addr)
1703       report_fatal_error("Unable to allocate memory for GOT!");
1704 
1705     Sections[GOTSectionID] = SectionEntry(".got", Addr, TotalSize, 0);
1706 
1707     if (Checker)
1708       Checker->registerSection(Obj.getFileName(), GOTSectionID);
1709 
1710     // For now, initialize all GOT entries to zero.  We'll fill them in as
1711     // needed when GOT-based relocations are applied.
1712     memset(Addr, 0, TotalSize);
1713     if (IsMipsN64ABI) {
1714       // To correctly resolve Mips GOT relocations, we need a mapping from
1715       // object's sections to GOTs.
1716       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1717            SI != SE; ++SI) {
1718         if (SI->relocation_begin() != SI->relocation_end()) {
1719           section_iterator RelocatedSection = SI->getRelocatedSection();
1720           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1721           assert (i != SectionMap.end());
1722           SectionToGOTMap[i->second] = GOTSectionID;
1723         }
1724       }
1725       GOTSymbolOffsets.clear();
1726     }
1727   }
1728 
1729   // Look for and record the EH frame section.
1730   ObjSectionToIDMap::iterator i, e;
1731   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1732     const SectionRef &Section = i->first;
1733     StringRef Name;
1734     Section.getName(Name);
1735     if (Name == ".eh_frame") {
1736       UnregisteredEHFrameSections.push_back(i->second);
1737       break;
1738     }
1739   }
1740 
1741   GOTSectionID = 0;
1742   CurrentGOTIndex = 0;
1743 }
1744 
1745 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1746   return Obj.isELF();
1747 }
1748 
1749 } // namespace llvm
1750