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 : public RuntimeDyld::LoadedObjectInfo {
108 public:
109   LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, unsigned BeginIdx,
110                       unsigned EndIdx)
111     : RuntimeDyld::LoadedObjectInfo(RTDyld, BeginIdx, EndIdx) {}
112 
113   OwningBinary<ObjectFile>
114   getObjectForDebug(const ObjectFile &Obj) const override;
115 };
116 
117 template <typename ELFT>
118 std::unique_ptr<DyldELFObject<ELFT>>
119 createRTDyldELFObject(MemoryBufferRef Buffer,
120                       const LoadedELFObjectInfo &L,
121                       std::error_code &ec) {
122   typedef typename ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
123   typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type;
124 
125   std::unique_ptr<DyldELFObject<ELFT>> Obj =
126     llvm::make_unique<DyldELFObject<ELFT>>(Buffer, ec);
127 
128   // Iterate over all sections in the object.
129   for (const auto &Sec : Obj->sections()) {
130     StringRef SectionName;
131     Sec.getName(SectionName);
132     if (SectionName != "") {
133       DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
134       Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
135           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
136 
137       if (uint64_t SecLoadAddr = L.getSectionLoadAddress(SectionName)) {
138         // This assumes that the address passed in matches the target address
139         // bitness. The template-based type cast handles everything else.
140         shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
141       }
142     }
143   }
144 
145   return Obj;
146 }
147 
148 OwningBinary<ObjectFile> createELFDebugObject(const ObjectFile &Obj,
149                                               const LoadedELFObjectInfo &L) {
150   assert(Obj.isELF() && "Not an ELF object file.");
151 
152   std::unique_ptr<MemoryBuffer> Buffer =
153     MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
154 
155   std::error_code ec;
156 
157   std::unique_ptr<ObjectFile> DebugObj;
158   if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian()) {
159     typedef ELFType<support::little, 2, false> ELF32LE;
160     DebugObj = createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), L, ec);
161   } else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian()) {
162     typedef ELFType<support::big, 2, false> ELF32BE;
163     DebugObj = createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), L, ec);
164   } else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian()) {
165     typedef ELFType<support::big, 2, true> ELF64BE;
166     DebugObj = createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), L, ec);
167   } else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian()) {
168     typedef ELFType<support::little, 2, true> ELF64LE;
169     DebugObj = createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), L, ec);
170   } else
171     llvm_unreachable("Unexpected ELF format");
172 
173   assert(!ec && "Could not construct copy ELF object file");
174 
175   return OwningBinary<ObjectFile>(std::move(DebugObj), std::move(Buffer));
176 }
177 
178 OwningBinary<ObjectFile>
179 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
180   return createELFDebugObject(Obj, *this);
181 }
182 
183 } // namespace
184 
185 namespace llvm {
186 
187 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
188                                RuntimeDyld::SymbolResolver &Resolver)
189     : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
190 RuntimeDyldELF::~RuntimeDyldELF() {}
191 
192 void RuntimeDyldELF::registerEHFrames() {
193   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
194     SID EHFrameSID = UnregisteredEHFrameSections[i];
195     uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
196     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
197     size_t EHFrameSize = Sections[EHFrameSID].Size;
198     MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
199     RegisteredEHFrameSections.push_back(EHFrameSID);
200   }
201   UnregisteredEHFrameSections.clear();
202 }
203 
204 void RuntimeDyldELF::deregisterEHFrames() {
205   for (int i = 0, e = RegisteredEHFrameSections.size(); i != e; ++i) {
206     SID EHFrameSID = RegisteredEHFrameSections[i];
207     uint8_t *EHFrameAddr = Sections[EHFrameSID].Address;
208     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].LoadAddress;
209     size_t EHFrameSize = Sections[EHFrameSID].Size;
210     MemMgr.deregisterEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
211   }
212   RegisteredEHFrameSections.clear();
213 }
214 
215 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
216 RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
217   unsigned SectionStartIdx, SectionEndIdx;
218   std::tie(SectionStartIdx, SectionEndIdx) = loadObjectImpl(O);
219   return llvm::make_unique<LoadedELFObjectInfo>(*this, SectionStartIdx,
220                                                 SectionEndIdx);
221 }
222 
223 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
224                                              uint64_t Offset, uint64_t Value,
225                                              uint32_t Type, int64_t Addend,
226                                              uint64_t SymOffset) {
227   switch (Type) {
228   default:
229     llvm_unreachable("Relocation type not implemented yet!");
230     break;
231   case ELF::R_X86_64_64: {
232     support::ulittle64_t::ref(Section.Address + Offset) = Value + Addend;
233     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
234                  << format("%p\n", Section.Address + Offset));
235     break;
236   }
237   case ELF::R_X86_64_32:
238   case ELF::R_X86_64_32S: {
239     Value += Addend;
240     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
241            (Type == ELF::R_X86_64_32S &&
242             ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
243     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
244     support::ulittle32_t::ref(Section.Address + Offset) = TruncatedAddr;
245     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
246                  << format("%p\n", Section.Address + Offset));
247     break;
248   }
249   case ELF::R_X86_64_PC32: {
250     uint64_t FinalAddress = Section.LoadAddress + Offset;
251     int64_t RealOffset = Value + Addend - FinalAddress;
252     assert(isInt<32>(RealOffset));
253     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
254     support::ulittle32_t::ref(Section.Address + Offset) = TruncOffset;
255     break;
256   }
257   case ELF::R_X86_64_PC64: {
258     uint64_t FinalAddress = Section.LoadAddress + Offset;
259     int64_t RealOffset = Value + Addend - FinalAddress;
260     support::ulittle64_t::ref(Section.Address + Offset) = RealOffset;
261     break;
262   }
263   }
264 }
265 
266 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
267                                           uint64_t Offset, uint32_t Value,
268                                           uint32_t Type, int32_t Addend) {
269   switch (Type) {
270   case ELF::R_386_32: {
271     support::ulittle32_t::ref(Section.Address + Offset) = Value + Addend;
272     break;
273   }
274   case ELF::R_386_PC32: {
275     uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
276     uint32_t RealOffset = Value + Addend - FinalAddress;
277     support::ulittle32_t::ref(Section.Address + Offset) = RealOffset;
278     break;
279   }
280   default:
281     // There are other relocation types, but it appears these are the
282     // only ones currently used by the LLVM ELF object writer
283     llvm_unreachable("Relocation type not implemented yet!");
284     break;
285   }
286 }
287 
288 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
289                                               uint64_t Offset, uint64_t Value,
290                                               uint32_t Type, int64_t Addend) {
291   uint32_t *TargetPtr = reinterpret_cast<uint32_t *>(Section.Address + Offset);
292   uint64_t FinalAddress = Section.LoadAddress + Offset;
293 
294   DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
295                << format("%llx", Section.Address + Offset)
296                << " FinalAddress: 0x" << format("%llx", FinalAddress)
297                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
298                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
299                << "\n");
300 
301   switch (Type) {
302   default:
303     llvm_unreachable("Relocation type not implemented yet!");
304     break;
305   case ELF::R_AARCH64_ABS64: {
306     uint64_t *TargetPtr =
307         reinterpret_cast<uint64_t *>(Section.Address + Offset);
308     *TargetPtr = Value + Addend;
309     break;
310   }
311   case ELF::R_AARCH64_PREL32: {
312     uint64_t Result = Value + Addend - FinalAddress;
313     assert(static_cast<int64_t>(Result) >= INT32_MIN &&
314            static_cast<int64_t>(Result) <= UINT32_MAX);
315     *TargetPtr = static_cast<uint32_t>(Result & 0xffffffffU);
316     break;
317   }
318   case ELF::R_AARCH64_CALL26: // fallthrough
319   case ELF::R_AARCH64_JUMP26: {
320     // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
321     // calculation.
322     uint64_t BranchImm = Value + Addend - FinalAddress;
323 
324     // "Check that -2^27 <= result < 2^27".
325     assert(isInt<28>(BranchImm));
326 
327     // AArch64 code is emitted with .rela relocations. The data already in any
328     // bits affected by the relocation on entry is garbage.
329     *TargetPtr &= 0xfc000000U;
330     // Immediate goes in bits 25:0 of B and BL.
331     *TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
332     break;
333   }
334   case ELF::R_AARCH64_MOVW_UABS_G3: {
335     uint64_t Result = Value + Addend;
336 
337     // AArch64 code is emitted with .rela relocations. The data already in any
338     // bits affected by the relocation on entry is garbage.
339     *TargetPtr &= 0xffe0001fU;
340     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
341     *TargetPtr |= Result >> (48 - 5);
342     // Shift must be "lsl #48", in bits 22:21
343     assert((*TargetPtr >> 21 & 0x3) == 3 && "invalid shift for relocation");
344     break;
345   }
346   case ELF::R_AARCH64_MOVW_UABS_G2_NC: {
347     uint64_t Result = Value + Addend;
348 
349     // AArch64 code is emitted with .rela relocations. The data already in any
350     // bits affected by the relocation on entry is garbage.
351     *TargetPtr &= 0xffe0001fU;
352     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
353     *TargetPtr |= ((Result & 0xffff00000000ULL) >> (32 - 5));
354     // Shift must be "lsl #32", in bits 22:21
355     assert((*TargetPtr >> 21 & 0x3) == 2 && "invalid shift for relocation");
356     break;
357   }
358   case ELF::R_AARCH64_MOVW_UABS_G1_NC: {
359     uint64_t Result = Value + Addend;
360 
361     // AArch64 code is emitted with .rela relocations. The data already in any
362     // bits affected by the relocation on entry is garbage.
363     *TargetPtr &= 0xffe0001fU;
364     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
365     *TargetPtr |= ((Result & 0xffff0000U) >> (16 - 5));
366     // Shift must be "lsl #16", in bits 22:2
367     assert((*TargetPtr >> 21 & 0x3) == 1 && "invalid shift for relocation");
368     break;
369   }
370   case ELF::R_AARCH64_MOVW_UABS_G0_NC: {
371     uint64_t Result = Value + Addend;
372 
373     // AArch64 code is emitted with .rela relocations. The data already in any
374     // bits affected by the relocation on entry is garbage.
375     *TargetPtr &= 0xffe0001fU;
376     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
377     *TargetPtr |= ((Result & 0xffffU) << 5);
378     // Shift must be "lsl #0", in bits 22:21.
379     assert((*TargetPtr >> 21 & 0x3) == 0 && "invalid shift for relocation");
380     break;
381   }
382   case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
383     // Operation: Page(S+A) - Page(P)
384     uint64_t Result =
385         ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
386 
387     // Check that -2^32 <= X < 2^32
388     assert(isInt<33>(Result) && "overflow check failed for relocation");
389 
390     // AArch64 code is emitted with .rela relocations. The data already in any
391     // bits affected by the relocation on entry is garbage.
392     *TargetPtr &= 0x9f00001fU;
393     // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
394     // from bits 32:12 of X.
395     *TargetPtr |= ((Result & 0x3000U) << (29 - 12));
396     *TargetPtr |= ((Result & 0x1ffffc000ULL) >> (14 - 5));
397     break;
398   }
399   case ELF::R_AARCH64_LDST32_ABS_LO12_NC: {
400     // Operation: S + A
401     uint64_t Result = Value + Addend;
402 
403     // AArch64 code is emitted with .rela relocations. The data already in any
404     // bits affected by the relocation on entry is garbage.
405     *TargetPtr &= 0xffc003ffU;
406     // Immediate goes in bits 21:10 of LD/ST instruction, taken
407     // from bits 11:2 of X
408     *TargetPtr |= ((Result & 0xffc) << (10 - 2));
409     break;
410   }
411   case ELF::R_AARCH64_LDST64_ABS_LO12_NC: {
412     // Operation: S + A
413     uint64_t Result = Value + Addend;
414 
415     // AArch64 code is emitted with .rela relocations. The data already in any
416     // bits affected by the relocation on entry is garbage.
417     *TargetPtr &= 0xffc003ffU;
418     // Immediate goes in bits 21:10 of LD/ST instruction, taken
419     // from bits 11:3 of X
420     *TargetPtr |= ((Result & 0xff8) << (10 - 3));
421     break;
422   }
423   }
424 }
425 
426 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
427                                           uint64_t Offset, uint32_t Value,
428                                           uint32_t Type, int32_t Addend) {
429   // TODO: Add Thumb relocations.
430   uint32_t *TargetPtr = (uint32_t *)(Section.Address + Offset);
431   uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
432   Value += Addend;
433 
434   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
435                << Section.Address + Offset
436                << " FinalAddress: " << format("%p", FinalAddress) << " Value: "
437                << format("%x", Value) << " Type: " << format("%x", Type)
438                << " Addend: " << format("%x", Addend) << "\n");
439 
440   switch (Type) {
441   default:
442     llvm_unreachable("Not implemented relocation type!");
443 
444   case ELF::R_ARM_NONE:
445     break;
446   case ELF::R_ARM_PREL31:
447   case ELF::R_ARM_TARGET1:
448   case ELF::R_ARM_ABS32:
449     *TargetPtr = Value;
450     break;
451     // Write first 16 bit of 32 bit value to the mov instruction.
452     // Last 4 bit should be shifted.
453   case ELF::R_ARM_MOVW_ABS_NC:
454   case ELF::R_ARM_MOVT_ABS:
455     if (Type == ELF::R_ARM_MOVW_ABS_NC)
456       Value = Value & 0xFFFF;
457     else if (Type == ELF::R_ARM_MOVT_ABS)
458       Value = (Value >> 16) & 0xFFFF;
459     *TargetPtr &= ~0x000F0FFF;
460     *TargetPtr |= Value & 0xFFF;
461     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
462     break;
463     // Write 24 bit relative value to the branch instruction.
464   case ELF::R_ARM_PC24: // Fall through.
465   case ELF::R_ARM_CALL: // Fall through.
466   case ELF::R_ARM_JUMP24:
467     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
468     RelValue = (RelValue & 0x03FFFFFC) >> 2;
469     assert((*TargetPtr & 0xFFFFFF) == 0xFFFFFE);
470     *TargetPtr &= 0xFF000000;
471     *TargetPtr |= RelValue;
472     break;
473   }
474 }
475 
476 void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
477                                            uint64_t Offset, uint32_t Value,
478                                            uint32_t Type, int32_t Addend) {
479   uint32_t *TargetPtr = (uint32_t *)(Section.Address + Offset);
480   Value += Addend;
481 
482   DEBUG(dbgs() << "resolveMipselocation, LocalAddress: "
483                << Section.Address + Offset << " FinalAddress: "
484                << format("%p", Section.LoadAddress + Offset) << " Value: "
485                << format("%x", Value) << " Type: " << format("%x", Type)
486                << " Addend: " << format("%x", Addend) << "\n");
487 
488   switch (Type) {
489   default:
490     llvm_unreachable("Not implemented relocation type!");
491     break;
492   case ELF::R_MIPS_32:
493     *TargetPtr = Value;
494     break;
495   case ELF::R_MIPS_26:
496     *TargetPtr = ((*TargetPtr) & 0xfc000000) | ((Value & 0x0fffffff) >> 2);
497     break;
498   case ELF::R_MIPS_HI16:
499     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
500     *TargetPtr =
501       ((*TargetPtr) & 0xffff0000) | (((Value + 0x8000) >> 16) & 0xffff);
502     break;
503   case ELF::R_MIPS_LO16:
504     *TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
505     break;
506   }
507 }
508 
509 // Return the .TOC. section and offset.
510 void RuntimeDyldELF::findPPC64TOCSection(const ObjectFile &Obj,
511                                          ObjSectionToIDMap &LocalSections,
512                                          RelocationValueRef &Rel) {
513   // Set a default SectionID in case we do not find a TOC section below.
514   // This may happen for references to TOC base base (sym@toc, .odp
515   // relocation) without a .toc directive.  In this case just use the
516   // first section (which is usually the .odp) since the code won't
517   // reference the .toc base directly.
518   Rel.SymbolName = NULL;
519   Rel.SectionID = 0;
520 
521   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
522   // order. The TOC starts where the first of these sections starts.
523   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
524        si != se; ++si) {
525 
526     StringRef SectionName;
527     check(si->getName(SectionName));
528 
529     if (SectionName == ".got"
530         || SectionName == ".toc"
531         || SectionName == ".tocbss"
532         || SectionName == ".plt") {
533       Rel.SectionID = findOrEmitSection(Obj, *si, false, LocalSections);
534       break;
535     }
536   }
537 
538   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
539   // thus permitting a full 64 Kbytes segment.
540   Rel.Addend = 0x8000;
541 }
542 
543 // Returns the sections and offset associated with the ODP entry referenced
544 // by Symbol.
545 void RuntimeDyldELF::findOPDEntrySection(const ObjectFile &Obj,
546                                          ObjSectionToIDMap &LocalSections,
547                                          RelocationValueRef &Rel) {
548   // Get the ELF symbol value (st_value) to compare with Relocation offset in
549   // .opd entries
550   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
551        si != se; ++si) {
552     section_iterator RelSecI = si->getRelocatedSection();
553     if (RelSecI == Obj.section_end())
554       continue;
555 
556     StringRef RelSectionName;
557     check(RelSecI->getName(RelSectionName));
558     if (RelSectionName != ".opd")
559       continue;
560 
561     for (relocation_iterator i = si->relocation_begin(),
562                              e = si->relocation_end();
563          i != e;) {
564       // The R_PPC64_ADDR64 relocation indicates the first field
565       // of a .opd entry
566       uint64_t TypeFunc;
567       check(i->getType(TypeFunc));
568       if (TypeFunc != ELF::R_PPC64_ADDR64) {
569         ++i;
570         continue;
571       }
572 
573       uint64_t TargetSymbolOffset;
574       symbol_iterator TargetSymbol = i->getSymbol();
575       check(i->getOffset(TargetSymbolOffset));
576       int64_t Addend;
577       check(getELFRelocationAddend(*i, Addend));
578 
579       ++i;
580       if (i == e)
581         break;
582 
583       // Just check if following relocation is a R_PPC64_TOC
584       uint64_t TypeTOC;
585       check(i->getType(TypeTOC));
586       if (TypeTOC != ELF::R_PPC64_TOC)
587         continue;
588 
589       // Finally compares the Symbol value and the target symbol offset
590       // to check if this .opd entry refers to the symbol the relocation
591       // points to.
592       if (Rel.Addend != (int64_t)TargetSymbolOffset)
593         continue;
594 
595       section_iterator tsi(Obj.section_end());
596       check(TargetSymbol->getSection(tsi));
597       bool IsCode = tsi->isText();
598       Rel.SectionID = findOrEmitSection(Obj, (*tsi), IsCode, LocalSections);
599       Rel.Addend = (intptr_t)Addend;
600       return;
601     }
602   }
603   llvm_unreachable("Attempting to get address of ODP entry!");
604 }
605 
606 // Relocation masks following the #lo(value), #hi(value), #ha(value),
607 // #higher(value), #highera(value), #highest(value), and #highesta(value)
608 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
609 // document.
610 
611 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
612 
613 static inline uint16_t applyPPChi(uint64_t value) {
614   return (value >> 16) & 0xffff;
615 }
616 
617 static inline uint16_t applyPPCha (uint64_t value) {
618   return ((value + 0x8000) >> 16) & 0xffff;
619 }
620 
621 static inline uint16_t applyPPChigher(uint64_t value) {
622   return (value >> 32) & 0xffff;
623 }
624 
625 static inline uint16_t applyPPChighera (uint64_t value) {
626   return ((value + 0x8000) >> 32) & 0xffff;
627 }
628 
629 static inline uint16_t applyPPChighest(uint64_t value) {
630   return (value >> 48) & 0xffff;
631 }
632 
633 static inline uint16_t applyPPChighesta (uint64_t value) {
634   return ((value + 0x8000) >> 48) & 0xffff;
635 }
636 
637 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
638                                             uint64_t Offset, uint64_t Value,
639                                             uint32_t Type, int64_t Addend) {
640   uint8_t *LocalAddress = Section.Address + Offset;
641   switch (Type) {
642   default:
643     llvm_unreachable("Relocation type not implemented yet!");
644     break;
645   case ELF::R_PPC64_ADDR16:
646     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
647     break;
648   case ELF::R_PPC64_ADDR16_DS:
649     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
650     break;
651   case ELF::R_PPC64_ADDR16_LO:
652     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
653     break;
654   case ELF::R_PPC64_ADDR16_LO_DS:
655     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
656     break;
657   case ELF::R_PPC64_ADDR16_HI:
658     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
659     break;
660   case ELF::R_PPC64_ADDR16_HA:
661     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
662     break;
663   case ELF::R_PPC64_ADDR16_HIGHER:
664     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
665     break;
666   case ELF::R_PPC64_ADDR16_HIGHERA:
667     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
668     break;
669   case ELF::R_PPC64_ADDR16_HIGHEST:
670     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
671     break;
672   case ELF::R_PPC64_ADDR16_HIGHESTA:
673     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
674     break;
675   case ELF::R_PPC64_ADDR14: {
676     assert(((Value + Addend) & 3) == 0);
677     // Preserve the AA/LK bits in the branch instruction
678     uint8_t aalk = *(LocalAddress + 3);
679     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
680   } break;
681   case ELF::R_PPC64_REL16_LO: {
682     uint64_t FinalAddress = (Section.LoadAddress + Offset);
683     uint64_t Delta = Value - FinalAddress + Addend;
684     writeInt16BE(LocalAddress, applyPPClo(Delta));
685   } break;
686   case ELF::R_PPC64_REL16_HI: {
687     uint64_t FinalAddress = (Section.LoadAddress + Offset);
688     uint64_t Delta = Value - FinalAddress + Addend;
689     writeInt16BE(LocalAddress, applyPPChi(Delta));
690   } break;
691   case ELF::R_PPC64_REL16_HA: {
692     uint64_t FinalAddress = (Section.LoadAddress + Offset);
693     uint64_t Delta = Value - FinalAddress + Addend;
694     writeInt16BE(LocalAddress, applyPPCha(Delta));
695   } break;
696   case ELF::R_PPC64_ADDR32: {
697     int32_t Result = static_cast<int32_t>(Value + Addend);
698     if (SignExtend32<32>(Result) != Result)
699       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
700     writeInt32BE(LocalAddress, Result);
701   } break;
702   case ELF::R_PPC64_REL24: {
703     uint64_t FinalAddress = (Section.LoadAddress + Offset);
704     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
705     if (SignExtend32<24>(delta) != delta)
706       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
707     // Generates a 'bl <address>' instruction
708     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
709   } break;
710   case ELF::R_PPC64_REL32: {
711     uint64_t FinalAddress = (Section.LoadAddress + Offset);
712     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
713     if (SignExtend32<32>(delta) != delta)
714       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
715     writeInt32BE(LocalAddress, delta);
716   } break;
717   case ELF::R_PPC64_REL64: {
718     uint64_t FinalAddress = (Section.LoadAddress + Offset);
719     uint64_t Delta = Value - FinalAddress + Addend;
720     writeInt64BE(LocalAddress, Delta);
721   } break;
722   case ELF::R_PPC64_ADDR64:
723     writeInt64BE(LocalAddress, Value + Addend);
724     break;
725   }
726 }
727 
728 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
729                                               uint64_t Offset, uint64_t Value,
730                                               uint32_t Type, int64_t Addend) {
731   uint8_t *LocalAddress = Section.Address + Offset;
732   switch (Type) {
733   default:
734     llvm_unreachable("Relocation type not implemented yet!");
735     break;
736   case ELF::R_390_PC16DBL:
737   case ELF::R_390_PLT16DBL: {
738     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
739     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
740     writeInt16BE(LocalAddress, Delta / 2);
741     break;
742   }
743   case ELF::R_390_PC32DBL:
744   case ELF::R_390_PLT32DBL: {
745     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
746     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
747     writeInt32BE(LocalAddress, Delta / 2);
748     break;
749   }
750   case ELF::R_390_PC32: {
751     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
752     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
753     writeInt32BE(LocalAddress, Delta);
754     break;
755   }
756   case ELF::R_390_64:
757     writeInt64BE(LocalAddress, Value + Addend);
758     break;
759   }
760 }
761 
762 // The target location for the relocation is described by RE.SectionID and
763 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
764 // SectionEntry has three members describing its location.
765 // SectionEntry::Address is the address at which the section has been loaded
766 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
767 // address that the section will have in the target process.
768 // SectionEntry::ObjAddress is the address of the bits for this section in the
769 // original emitted object image (also in the current address space).
770 //
771 // Relocations will be applied as if the section were loaded at
772 // SectionEntry::LoadAddress, but they will be applied at an address based
773 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
774 // Target memory contents if they are required for value calculations.
775 //
776 // The Value parameter here is the load address of the symbol for the
777 // relocation to be applied.  For relocations which refer to symbols in the
778 // current object Value will be the LoadAddress of the section in which
779 // the symbol resides (RE.Addend provides additional information about the
780 // symbol location).  For external symbols, Value will be the address of the
781 // symbol in the target address space.
782 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
783                                        uint64_t Value) {
784   const SectionEntry &Section = Sections[RE.SectionID];
785   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
786                            RE.SymOffset);
787 }
788 
789 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
790                                        uint64_t Offset, uint64_t Value,
791                                        uint32_t Type, int64_t Addend,
792                                        uint64_t SymOffset) {
793   switch (Arch) {
794   case Triple::x86_64:
795     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
796     break;
797   case Triple::x86:
798     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
799                          (uint32_t)(Addend & 0xffffffffL));
800     break;
801   case Triple::aarch64:
802   case Triple::aarch64_be:
803     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
804     break;
805   case Triple::arm: // Fall through.
806   case Triple::armeb:
807   case Triple::thumb:
808   case Triple::thumbeb:
809     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
810                          (uint32_t)(Addend & 0xffffffffL));
811     break;
812   case Triple::mips: // Fall through.
813   case Triple::mipsel:
814     resolveMIPSRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL),
815                           Type, (uint32_t)(Addend & 0xffffffffL));
816     break;
817   case Triple::ppc64: // Fall through.
818   case Triple::ppc64le:
819     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
820     break;
821   case Triple::systemz:
822     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
823     break;
824   default:
825     llvm_unreachable("Unsupported CPU type!");
826   }
827 }
828 
829 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
830   return (void*)(Sections[SectionID].ObjAddress + Offset);
831 }
832 
833 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
834   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
835   if (Value.SymbolName)
836     addRelocationForSymbol(RE, Value.SymbolName);
837   else
838     addRelocationForSection(RE, Value.SectionID);
839 }
840 
841 relocation_iterator RuntimeDyldELF::processRelocationRef(
842     unsigned SectionID, relocation_iterator RelI,
843     const ObjectFile &Obj,
844     ObjSectionToIDMap &ObjSectionToID,
845     StubMap &Stubs) {
846   uint64_t RelType;
847   Check(RelI->getType(RelType));
848   int64_t Addend;
849   Check(getELFRelocationAddend(*RelI, Addend));
850   symbol_iterator Symbol = RelI->getSymbol();
851 
852   // Obtain the symbol name which is referenced in the relocation
853   StringRef TargetName;
854   if (Symbol != Obj.symbol_end())
855     Symbol->getName(TargetName);
856   DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
857                << " TargetName: " << TargetName << "\n");
858   RelocationValueRef Value;
859   // First search for the symbol in the local symbol table
860   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
861 
862   // Search for the symbol in the global symbol table
863   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
864   if (Symbol != Obj.symbol_end()) {
865     gsi = GlobalSymbolTable.find(TargetName.data());
866     Symbol->getType(SymType);
867   }
868   if (gsi != GlobalSymbolTable.end()) {
869     const auto &SymInfo = gsi->second;
870     Value.SectionID = SymInfo.getSectionID();
871     Value.Offset = SymInfo.getOffset();
872     Value.Addend = SymInfo.getOffset() + Addend;
873   } else {
874     switch (SymType) {
875     case SymbolRef::ST_Debug: {
876       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
877       // and can be changed by another developers. Maybe best way is add
878       // a new symbol type ST_Section to SymbolRef and use it.
879       section_iterator si(Obj.section_end());
880       Symbol->getSection(si);
881       if (si == Obj.section_end())
882         llvm_unreachable("Symbol section not found, bad object file format!");
883       DEBUG(dbgs() << "\t\tThis is section symbol\n");
884       bool isCode = si->isText();
885       Value.SectionID = findOrEmitSection(Obj, (*si), isCode, ObjSectionToID);
886       Value.Addend = Addend;
887       break;
888     }
889     case SymbolRef::ST_Data:
890     case SymbolRef::ST_Unknown: {
891       Value.SymbolName = TargetName.data();
892       Value.Addend = Addend;
893 
894       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
895       // will manifest here as a NULL symbol name.
896       // We can set this as a valid (but empty) symbol name, and rely
897       // on addRelocationForSymbol to handle this.
898       if (!Value.SymbolName)
899         Value.SymbolName = "";
900       break;
901     }
902     default:
903       llvm_unreachable("Unresolved symbol type!");
904       break;
905     }
906   }
907 
908   uint64_t Offset;
909   Check(RelI->getOffset(Offset));
910 
911   DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
912                << "\n");
913   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be) &&
914       (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26)) {
915     // This is an AArch64 branch relocation, need to use a stub function.
916     DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
917     SectionEntry &Section = Sections[SectionID];
918 
919     // Look for an existing stub.
920     StubMap::const_iterator i = Stubs.find(Value);
921     if (i != Stubs.end()) {
922       resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
923                         RelType, 0);
924       DEBUG(dbgs() << " Stub function found\n");
925     } else {
926       // Create a new stub function.
927       DEBUG(dbgs() << " Create a new stub function\n");
928       Stubs[Value] = Section.StubOffset;
929       uint8_t *StubTargetAddr =
930           createStubFunction(Section.Address + Section.StubOffset);
931 
932       RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.Address,
933                                 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
934       RelocationEntry REmovk_g2(SectionID, StubTargetAddr - Section.Address + 4,
935                                 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
936       RelocationEntry REmovk_g1(SectionID, StubTargetAddr - Section.Address + 8,
937                                 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
938       RelocationEntry REmovk_g0(SectionID,
939                                 StubTargetAddr - Section.Address + 12,
940                                 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
941 
942       if (Value.SymbolName) {
943         addRelocationForSymbol(REmovz_g3, Value.SymbolName);
944         addRelocationForSymbol(REmovk_g2, Value.SymbolName);
945         addRelocationForSymbol(REmovk_g1, Value.SymbolName);
946         addRelocationForSymbol(REmovk_g0, Value.SymbolName);
947       } else {
948         addRelocationForSection(REmovz_g3, Value.SectionID);
949         addRelocationForSection(REmovk_g2, Value.SectionID);
950         addRelocationForSection(REmovk_g1, Value.SectionID);
951         addRelocationForSection(REmovk_g0, Value.SectionID);
952       }
953       resolveRelocation(Section, Offset,
954                         (uint64_t)Section.Address + Section.StubOffset, RelType,
955                         0);
956       Section.StubOffset += getMaxStubSize();
957     }
958   } else if (Arch == Triple::arm) {
959     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
960       RelType == ELF::R_ARM_JUMP24) {
961       // This is an ARM branch relocation, need to use a stub function.
962       DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
963       SectionEntry &Section = Sections[SectionID];
964 
965       // Look for an existing stub.
966       StubMap::const_iterator i = Stubs.find(Value);
967       if (i != Stubs.end()) {
968         resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
969           RelType, 0);
970         DEBUG(dbgs() << " Stub function found\n");
971       } else {
972         // Create a new stub function.
973         DEBUG(dbgs() << " Create a new stub function\n");
974         Stubs[Value] = Section.StubOffset;
975         uint8_t *StubTargetAddr =
976           createStubFunction(Section.Address + Section.StubOffset);
977         RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
978           ELF::R_ARM_ABS32, Value.Addend);
979         if (Value.SymbolName)
980           addRelocationForSymbol(RE, Value.SymbolName);
981         else
982           addRelocationForSection(RE, Value.SectionID);
983 
984         resolveRelocation(Section, Offset,
985           (uint64_t)Section.Address + Section.StubOffset, RelType,
986           0);
987         Section.StubOffset += getMaxStubSize();
988       }
989     } else {
990       uint32_t *Placeholder =
991         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
992       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
993           RelType == ELF::R_ARM_ABS32) {
994         Value.Addend += *Placeholder;
995       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
996         // See ELF for ARM documentation
997         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
998       }
999       processSimpleRelocation(SectionID, Offset, RelType, Value);
1000     }
1001   } else if ((Arch == Triple::mipsel || Arch == Triple::mips)) {
1002     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1003     if (RelType == ELF::R_MIPS_26) {
1004       // This is an Mips branch relocation, need to use a stub function.
1005       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1006       SectionEntry &Section = Sections[SectionID];
1007 
1008       // Extract the addend from the instruction.
1009       // We shift up by two since the Value will be down shifted again
1010       // when applying the relocation.
1011       uint32_t Addend = ((*Placeholder) & 0x03ffffff) << 2;
1012 
1013       Value.Addend += Addend;
1014 
1015       //  Look up for existing stub.
1016       StubMap::const_iterator i = Stubs.find(Value);
1017       if (i != Stubs.end()) {
1018         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1019         addRelocationForSection(RE, SectionID);
1020         DEBUG(dbgs() << " Stub function found\n");
1021       } else {
1022         // Create a new stub function.
1023         DEBUG(dbgs() << " Create a new stub function\n");
1024         Stubs[Value] = Section.StubOffset;
1025         uint8_t *StubTargetAddr =
1026           createStubFunction(Section.Address + Section.StubOffset);
1027 
1028         // Creating Hi and Lo relocations for the filled stub instructions.
1029         RelocationEntry REHi(SectionID, StubTargetAddr - Section.Address,
1030           ELF::R_MIPS_HI16, Value.Addend);
1031         RelocationEntry RELo(SectionID, StubTargetAddr - Section.Address + 4,
1032           ELF::R_MIPS_LO16, Value.Addend);
1033 
1034         if (Value.SymbolName) {
1035           addRelocationForSymbol(REHi, Value.SymbolName);
1036           addRelocationForSymbol(RELo, Value.SymbolName);
1037         }
1038         else {
1039           addRelocationForSection(REHi, Value.SectionID);
1040           addRelocationForSection(RELo, Value.SectionID);
1041         }
1042 
1043         RelocationEntry RE(SectionID, Offset, RelType, Section.StubOffset);
1044         addRelocationForSection(RE, SectionID);
1045         Section.StubOffset += getMaxStubSize();
1046       }
1047     } else {
1048       if (RelType == ELF::R_MIPS_HI16)
1049         Value.Addend += ((*Placeholder) & 0x0000ffff) << 16;
1050       else if (RelType == ELF::R_MIPS_LO16)
1051         Value.Addend += ((*Placeholder) & 0x0000ffff);
1052       else if (RelType == ELF::R_MIPS_32)
1053         Value.Addend += *Placeholder;
1054       processSimpleRelocation(SectionID, Offset, RelType, Value);
1055     }
1056   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1057     if (RelType == ELF::R_PPC64_REL24) {
1058       // Determine ABI variant in use for this object.
1059       unsigned AbiVariant;
1060       Obj.getPlatformFlags(AbiVariant);
1061       AbiVariant &= ELF::EF_PPC64_ABI;
1062       // A PPC branch relocation will need a stub function if the target is
1063       // an external symbol (Symbol::ST_Unknown) or if the target address
1064       // is not within the signed 24-bits branch address.
1065       SectionEntry &Section = Sections[SectionID];
1066       uint8_t *Target = Section.Address + Offset;
1067       bool RangeOverflow = false;
1068       if (SymType != SymbolRef::ST_Unknown) {
1069         if (AbiVariant != 2) {
1070           // In the ELFv1 ABI, a function call may point to the .opd entry,
1071           // so the final symbol value is calculated based on the relocation
1072           // values in the .opd section.
1073           findOPDEntrySection(Obj, ObjSectionToID, Value);
1074         } else {
1075           // In the ELFv2 ABI, a function symbol may provide a local entry
1076           // point, which must be used for direct calls.
1077           uint8_t SymOther;
1078           Symbol->getOther(SymOther);
1079           Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1080         }
1081         uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
1082         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
1083         // If it is within 24-bits branch range, just set the branch target
1084         if (SignExtend32<24>(delta) == delta) {
1085           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1086           if (Value.SymbolName)
1087             addRelocationForSymbol(RE, Value.SymbolName);
1088           else
1089             addRelocationForSection(RE, Value.SectionID);
1090         } else {
1091           RangeOverflow = true;
1092         }
1093       }
1094       if (SymType == SymbolRef::ST_Unknown || RangeOverflow) {
1095         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
1096         // larger than 24-bits.
1097         StubMap::const_iterator i = Stubs.find(Value);
1098         if (i != Stubs.end()) {
1099           // Symbol function stub already created, just relocate to it
1100           resolveRelocation(Section, Offset,
1101                             (uint64_t)Section.Address + i->second, RelType, 0);
1102           DEBUG(dbgs() << " Stub function found\n");
1103         } else {
1104           // Create a new stub function.
1105           DEBUG(dbgs() << " Create a new stub function\n");
1106           Stubs[Value] = Section.StubOffset;
1107           uint8_t *StubTargetAddr =
1108               createStubFunction(Section.Address + Section.StubOffset,
1109                                  AbiVariant);
1110           RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1111                              ELF::R_PPC64_ADDR64, Value.Addend);
1112 
1113           // Generates the 64-bits address loads as exemplified in section
1114           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1115           // apply to the low part of the instructions, so we have to update
1116           // the offset according to the target endianness.
1117           uint64_t StubRelocOffset = StubTargetAddr - Section.Address;
1118           if (!IsTargetLittleEndian)
1119             StubRelocOffset += 2;
1120 
1121           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1122                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1123           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1124                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1125           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1126                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1127           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1128                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1129 
1130           if (Value.SymbolName) {
1131             addRelocationForSymbol(REhst, Value.SymbolName);
1132             addRelocationForSymbol(REhr, Value.SymbolName);
1133             addRelocationForSymbol(REh, Value.SymbolName);
1134             addRelocationForSymbol(REl, Value.SymbolName);
1135           } else {
1136             addRelocationForSection(REhst, Value.SectionID);
1137             addRelocationForSection(REhr, Value.SectionID);
1138             addRelocationForSection(REh, Value.SectionID);
1139             addRelocationForSection(REl, Value.SectionID);
1140           }
1141 
1142           resolveRelocation(Section, Offset,
1143                             (uint64_t)Section.Address + Section.StubOffset,
1144                             RelType, 0);
1145           Section.StubOffset += getMaxStubSize();
1146         }
1147         if (SymType == SymbolRef::ST_Unknown) {
1148           // Restore the TOC for external calls
1149           if (AbiVariant == 2)
1150             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
1151           else
1152             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1153         }
1154       }
1155     } else if (RelType == ELF::R_PPC64_TOC16 ||
1156                RelType == ELF::R_PPC64_TOC16_DS ||
1157                RelType == ELF::R_PPC64_TOC16_LO ||
1158                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1159                RelType == ELF::R_PPC64_TOC16_HI ||
1160                RelType == ELF::R_PPC64_TOC16_HA) {
1161       // These relocations are supposed to subtract the TOC address from
1162       // the final value.  This does not fit cleanly into the RuntimeDyld
1163       // scheme, since there may be *two* sections involved in determining
1164       // the relocation value (the section of the symbol refered to by the
1165       // relocation, and the TOC section associated with the current module).
1166       //
1167       // Fortunately, these relocations are currently only ever generated
1168       // refering to symbols that themselves reside in the TOC, which means
1169       // that the two sections are actually the same.  Thus they cancel out
1170       // and we can immediately resolve the relocation right now.
1171       switch (RelType) {
1172       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1173       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1174       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1175       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1176       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1177       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1178       default: llvm_unreachable("Wrong relocation type.");
1179       }
1180 
1181       RelocationValueRef TOCValue;
1182       findPPC64TOCSection(Obj, ObjSectionToID, TOCValue);
1183       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1184         llvm_unreachable("Unsupported TOC relocation.");
1185       Value.Addend -= TOCValue.Addend;
1186       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1187     } else {
1188       // There are two ways to refer to the TOC address directly: either
1189       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1190       // ignored), or via any relocation that refers to the magic ".TOC."
1191       // symbols (in which case the addend is respected).
1192       if (RelType == ELF::R_PPC64_TOC) {
1193         RelType = ELF::R_PPC64_ADDR64;
1194         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1195       } else if (TargetName == ".TOC.") {
1196         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1197         Value.Addend += Addend;
1198       }
1199 
1200       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1201 
1202       if (Value.SymbolName)
1203         addRelocationForSymbol(RE, Value.SymbolName);
1204       else
1205         addRelocationForSection(RE, Value.SectionID);
1206     }
1207   } else if (Arch == Triple::systemz &&
1208              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1209     // Create function stubs for both PLT and GOT references, regardless of
1210     // whether the GOT reference is to data or code.  The stub contains the
1211     // full address of the symbol, as needed by GOT references, and the
1212     // executable part only adds an overhead of 8 bytes.
1213     //
1214     // We could try to conserve space by allocating the code and data
1215     // parts of the stub separately.  However, as things stand, we allocate
1216     // a stub for every relocation, so using a GOT in JIT code should be
1217     // no less space efficient than using an explicit constant pool.
1218     DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1219     SectionEntry &Section = Sections[SectionID];
1220 
1221     // Look for an existing stub.
1222     StubMap::const_iterator i = Stubs.find(Value);
1223     uintptr_t StubAddress;
1224     if (i != Stubs.end()) {
1225       StubAddress = uintptr_t(Section.Address) + i->second;
1226       DEBUG(dbgs() << " Stub function found\n");
1227     } else {
1228       // Create a new stub function.
1229       DEBUG(dbgs() << " Create a new stub function\n");
1230 
1231       uintptr_t BaseAddress = uintptr_t(Section.Address);
1232       uintptr_t StubAlignment = getStubAlignment();
1233       StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1234                     -StubAlignment;
1235       unsigned StubOffset = StubAddress - BaseAddress;
1236 
1237       Stubs[Value] = StubOffset;
1238       createStubFunction((uint8_t *)StubAddress);
1239       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1240                          Value.Offset);
1241       if (Value.SymbolName)
1242         addRelocationForSymbol(RE, Value.SymbolName);
1243       else
1244         addRelocationForSection(RE, Value.SectionID);
1245       Section.StubOffset = StubOffset + getMaxStubSize();
1246     }
1247 
1248     if (RelType == ELF::R_390_GOTENT)
1249       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1250                         Addend);
1251     else
1252       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1253   } else if (Arch == Triple::x86_64) {
1254     if (RelType == ELF::R_X86_64_PLT32) {
1255       // The way the PLT relocations normally work is that the linker allocates
1256       // the
1257       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1258       // entry will then jump to an address provided by the GOT.  On first call,
1259       // the
1260       // GOT address will point back into PLT code that resolves the symbol. After
1261       // the first call, the GOT entry points to the actual function.
1262       //
1263       // For local functions we're ignoring all of that here and just replacing
1264       // the PLT32 relocation type with PC32, which will translate the relocation
1265       // into a PC-relative call directly to the function. For external symbols we
1266       // can't be sure the function will be within 2^32 bytes of the call site, so
1267       // we need to create a stub, which calls into the GOT.  This case is
1268       // equivalent to the usual PLT implementation except that we use the stub
1269       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1270       // rather than allocating a PLT section.
1271       if (Value.SymbolName) {
1272         // This is a call to an external function.
1273         // Look for an existing stub.
1274         SectionEntry &Section = Sections[SectionID];
1275         StubMap::const_iterator i = Stubs.find(Value);
1276         uintptr_t StubAddress;
1277         if (i != Stubs.end()) {
1278         StubAddress = uintptr_t(Section.Address) + i->second;
1279         DEBUG(dbgs() << " Stub function found\n");
1280         } else {
1281         // Create a new stub function (equivalent to a PLT entry).
1282         DEBUG(dbgs() << " Create a new stub function\n");
1283 
1284         uintptr_t BaseAddress = uintptr_t(Section.Address);
1285         uintptr_t StubAlignment = getStubAlignment();
1286         StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1287                 -StubAlignment;
1288         unsigned StubOffset = StubAddress - BaseAddress;
1289         Stubs[Value] = StubOffset;
1290         createStubFunction((uint8_t *)StubAddress);
1291 
1292         // Bump our stub offset counter
1293         Section.StubOffset = StubOffset + getMaxStubSize();
1294 
1295         // Allocate a GOT Entry
1296         uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1297 
1298         // The load of the GOT address has an addend of -4
1299         resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4);
1300 
1301         // Fill in the value of the symbol we're targeting into the GOT
1302         addRelocationForSymbol(computeGOTOffsetRE(SectionID,GOTOffset,0,ELF::R_X86_64_64),
1303           Value.SymbolName);
1304         }
1305 
1306         // Make the target call a call into the stub table.
1307         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1308                 Addend);
1309       } else {
1310         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1311                   Value.Offset);
1312         addRelocationForSection(RE, Value.SectionID);
1313       }
1314     } else if (RelType == ELF::R_X86_64_GOTPCREL) {
1315       uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1316       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend);
1317 
1318       // Fill in the value of the symbol we're targeting into the GOT
1319       RelocationEntry RE = computeGOTOffsetRE(SectionID, GOTOffset, Value.Offset, ELF::R_X86_64_64);
1320       if (Value.SymbolName)
1321         addRelocationForSymbol(RE, Value.SymbolName);
1322       else
1323         addRelocationForSection(RE, Value.SectionID);
1324     } else if (RelType == ELF::R_X86_64_PC32) {
1325       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1326       processSimpleRelocation(SectionID, Offset, RelType, Value);
1327     } else if (RelType == ELF::R_X86_64_PC64) {
1328       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1329       processSimpleRelocation(SectionID, Offset, RelType, Value);
1330     } else {
1331       processSimpleRelocation(SectionID, Offset, RelType, Value);
1332     }
1333   } else {
1334     if (Arch == Triple::x86) {
1335       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1336     }
1337     processSimpleRelocation(SectionID, Offset, RelType, Value);
1338   }
1339   return ++RelI;
1340 }
1341 
1342 size_t RuntimeDyldELF::getGOTEntrySize() {
1343   // We don't use the GOT in all of these cases, but it's essentially free
1344   // to put them all here.
1345   size_t Result = 0;
1346   switch (Arch) {
1347   case Triple::x86_64:
1348   case Triple::aarch64:
1349   case Triple::aarch64_be:
1350   case Triple::ppc64:
1351   case Triple::ppc64le:
1352   case Triple::systemz:
1353     Result = sizeof(uint64_t);
1354     break;
1355   case Triple::x86:
1356   case Triple::arm:
1357   case Triple::thumb:
1358   case Triple::mips:
1359   case Triple::mipsel:
1360     Result = sizeof(uint32_t);
1361     break;
1362   default:
1363     llvm_unreachable("Unsupported CPU type!");
1364   }
1365   return Result;
1366 }
1367 
1368 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned SectionID, unsigned no)
1369 {
1370   (void)SectionID; // The GOT Section is the same for all section in the object file
1371   if (GOTSectionID == 0) {
1372     GOTSectionID = Sections.size();
1373     // Reserve a section id. We'll allocate the section later
1374     // once we know the total size
1375     Sections.push_back(SectionEntry(".got", 0, 0, 0));
1376   }
1377   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1378   CurrentGOTIndex += no;
1379   return StartOffset;
1380 }
1381 
1382 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset, uint64_t GOTOffset)
1383 {
1384   // Fill in the relative address of the GOT Entry into the stub
1385   RelocationEntry GOTRE(SectionID, Offset, ELF::R_X86_64_PC32, GOTOffset);
1386   addRelocationForSection(GOTRE, GOTSectionID);
1387 }
1388 
1389 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(unsigned SectionID, uint64_t GOTOffset, uint64_t SymbolOffset,
1390                                                    uint32_t Type)
1391 {
1392   (void)SectionID; // The GOT Section is the same for all section in the object file
1393   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1394 }
1395 
1396 void RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1397                                   ObjSectionToIDMap &SectionMap) {
1398   // If necessary, allocate the global offset table
1399   if (GOTSectionID != 0) {
1400     // Allocate memory for the section
1401     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1402     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1403                                                 GOTSectionID, ".got", false);
1404     if (!Addr)
1405       report_fatal_error("Unable to allocate memory for GOT!");
1406 
1407     Sections[GOTSectionID] = SectionEntry(".got", Addr, TotalSize, 0);
1408 
1409     if (Checker)
1410       Checker->registerSection(Obj.getFileName(), GOTSectionID);
1411 
1412     // For now, initialize all GOT entries to zero.  We'll fill them in as
1413     // needed when GOT-based relocations are applied.
1414     memset(Addr, 0, TotalSize);
1415   }
1416 
1417   // Look for and record the EH frame section.
1418   ObjSectionToIDMap::iterator i, e;
1419   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1420     const SectionRef &Section = i->first;
1421     StringRef Name;
1422     Section.getName(Name);
1423     if (Name == ".eh_frame") {
1424       UnregisteredEHFrameSections.push_back(i->second);
1425       break;
1426     }
1427   }
1428 
1429   GOTSectionID = 0;
1430   CurrentGOTIndex = 0;
1431 }
1432 
1433 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1434   return Obj.isELF();
1435 }
1436 
1437 } // namespace llvm
1438