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 "Targets/RuntimeDyldELFMips.h"
17 #include "llvm/ADT/IntervalMap.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/BinaryFormat/ELF.h"
22 #include "llvm/MC/MCStreamer.h"
23 #include "llvm/Object/ELFObjectFile.h"
24 #include "llvm/Object/ObjectFile.h"
25 #include "llvm/Support/Endian.h"
26 #include "llvm/Support/MemoryBuffer.h"
27 
28 using namespace llvm;
29 using namespace llvm::object;
30 using namespace llvm::support::endian;
31 
32 #define DEBUG_TYPE "dyld"
33 
34 static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); }
35 
36 static void or32AArch64Imm(void *L, uint64_t Imm) {
37   or32le(L, (Imm & 0xFFF) << 10);
38 }
39 
40 template <class T> static void write(bool isBE, void *P, T V) {
41   isBE ? write<T, support::big>(P, V) : write<T, support::little>(P, V);
42 }
43 
44 static void write32AArch64Addr(void *L, uint64_t Imm) {
45   uint32_t ImmLo = (Imm & 0x3) << 29;
46   uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
47   uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
48   write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
49 }
50 
51 // Return the bits [Start, End] from Val shifted Start bits.
52 // For instance, getBits(0xF0, 4, 8) returns 0xF.
53 static uint64_t getBits(uint64_t Val, int Start, int End) {
54   uint64_t Mask = ((uint64_t)1 << (End + 1 - Start)) - 1;
55   return (Val >> Start) & Mask;
56 }
57 
58 namespace {
59 
60 template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> {
61   LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
62 
63   typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
64   typedef Elf_Sym_Impl<ELFT> Elf_Sym;
65   typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
66   typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
67 
68   typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
69 
70   typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type;
71 
72   DyldELFObject(ELFObjectFile<ELFT> &&Obj);
73 
74 public:
75   static Expected<std::unique_ptr<DyldELFObject>>
76   create(MemoryBufferRef Wrapper);
77 
78   void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
79 
80   void updateSymbolAddress(const SymbolRef &SymRef, uint64_t Addr);
81 
82   // Methods for type inquiry through isa, cast and dyn_cast
83   static bool classof(const Binary *v) {
84     return (isa<ELFObjectFile<ELFT>>(v) &&
85             classof(cast<ELFObjectFile<ELFT>>(v)));
86   }
87   static bool classof(const ELFObjectFile<ELFT> *v) {
88     return v->isDyldType();
89   }
90 };
91 
92 
93 
94 // The MemoryBuffer passed into this constructor is just a wrapper around the
95 // actual memory.  Ultimately, the Binary parent class will take ownership of
96 // this MemoryBuffer object but not the underlying memory.
97 template <class ELFT>
98 DyldELFObject<ELFT>::DyldELFObject(ELFObjectFile<ELFT> &&Obj)
99     : ELFObjectFile<ELFT>(std::move(Obj)) {
100   this->isDyldELFObject = true;
101 }
102 
103 template <class ELFT>
104 Expected<std::unique_ptr<DyldELFObject<ELFT>>>
105 DyldELFObject<ELFT>::create(MemoryBufferRef Wrapper) {
106   auto Obj = ELFObjectFile<ELFT>::create(Wrapper);
107   if (auto E = Obj.takeError())
108     return std::move(E);
109   std::unique_ptr<DyldELFObject<ELFT>> Ret(
110       new DyldELFObject<ELFT>(std::move(*Obj)));
111   return std::move(Ret);
112 }
113 
114 template <class ELFT>
115 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
116                                                uint64_t Addr) {
117   DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
118   Elf_Shdr *shdr =
119       const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
120 
121   // This assumes the address passed in matches the target address bitness
122   // The template-based type cast handles everything else.
123   shdr->sh_addr = static_cast<addr_type>(Addr);
124 }
125 
126 template <class ELFT>
127 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
128                                               uint64_t Addr) {
129 
130   Elf_Sym *sym = const_cast<Elf_Sym *>(
131       ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
132 
133   // This assumes the address passed in matches the target address bitness
134   // The template-based type cast handles everything else.
135   sym->st_value = static_cast<addr_type>(Addr);
136 }
137 
138 class LoadedELFObjectInfo final
139     : public LoadedObjectInfoHelper<LoadedELFObjectInfo,
140                                     RuntimeDyld::LoadedObjectInfo> {
141 public:
142   LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
143       : LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {}
144 
145   OwningBinary<ObjectFile>
146   getObjectForDebug(const ObjectFile &Obj) const override;
147 };
148 
149 template <typename ELFT>
150 static Expected<std::unique_ptr<DyldELFObject<ELFT>>>
151 createRTDyldELFObject(MemoryBufferRef Buffer, const ObjectFile &SourceObject,
152                       const LoadedELFObjectInfo &L) {
153   typedef typename ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
154   typedef typename ELFDataTypeTypedefHelper<ELFT>::value_type addr_type;
155 
156   Expected<std::unique_ptr<DyldELFObject<ELFT>>> ObjOrErr =
157       DyldELFObject<ELFT>::create(Buffer);
158   if (Error E = ObjOrErr.takeError())
159     return std::move(E);
160 
161   std::unique_ptr<DyldELFObject<ELFT>> Obj = std::move(*ObjOrErr);
162 
163   // Iterate over all sections in the object.
164   auto SI = SourceObject.section_begin();
165   for (const auto &Sec : Obj->sections()) {
166     StringRef SectionName;
167     Sec.getName(SectionName);
168     if (SectionName != "") {
169       DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
170       Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
171           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
172 
173       if (uint64_t SecLoadAddr = L.getSectionLoadAddress(*SI)) {
174         // This assumes that the address passed in matches the target address
175         // bitness. The template-based type cast handles everything else.
176         shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
177       }
178     }
179     ++SI;
180   }
181 
182   return std::move(Obj);
183 }
184 
185 static OwningBinary<ObjectFile>
186 createELFDebugObject(const ObjectFile &Obj, const LoadedELFObjectInfo &L) {
187   assert(Obj.isELF() && "Not an ELF object file.");
188 
189   std::unique_ptr<MemoryBuffer> Buffer =
190     MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
191 
192   Expected<std::unique_ptr<ObjectFile>> DebugObj(nullptr);
193   handleAllErrors(DebugObj.takeError());
194   if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian())
195     DebugObj =
196         createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), Obj, L);
197   else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian())
198     DebugObj =
199         createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), Obj, L);
200   else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian())
201     DebugObj =
202         createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), Obj, L);
203   else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian())
204     DebugObj =
205         createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), Obj, L);
206   else
207     llvm_unreachable("Unexpected ELF format");
208 
209   handleAllErrors(DebugObj.takeError());
210   return OwningBinary<ObjectFile>(std::move(*DebugObj), std::move(Buffer));
211 }
212 
213 OwningBinary<ObjectFile>
214 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
215   return createELFDebugObject(Obj, *this);
216 }
217 
218 } // anonymous namespace
219 
220 namespace llvm {
221 
222 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
223                                JITSymbolResolver &Resolver)
224     : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
225 RuntimeDyldELF::~RuntimeDyldELF() {}
226 
227 void RuntimeDyldELF::registerEHFrames() {
228   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
229     SID EHFrameSID = UnregisteredEHFrameSections[i];
230     uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
231     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
232     size_t EHFrameSize = Sections[EHFrameSID].getSize();
233     MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
234   }
235   UnregisteredEHFrameSections.clear();
236 }
237 
238 std::unique_ptr<RuntimeDyldELF>
239 llvm::RuntimeDyldELF::create(Triple::ArchType Arch,
240                              RuntimeDyld::MemoryManager &MemMgr,
241                              JITSymbolResolver &Resolver) {
242   switch (Arch) {
243   default:
244     return make_unique<RuntimeDyldELF>(MemMgr, Resolver);
245   case Triple::mips:
246   case Triple::mipsel:
247   case Triple::mips64:
248   case Triple::mips64el:
249     return make_unique<RuntimeDyldELFMips>(MemMgr, Resolver);
250   }
251 }
252 
253 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
254 RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
255   if (auto ObjSectionToIDOrErr = loadObjectImpl(O))
256     return llvm::make_unique<LoadedELFObjectInfo>(*this, *ObjSectionToIDOrErr);
257   else {
258     HasError = true;
259     raw_string_ostream ErrStream(ErrorStr);
260     logAllUnhandledErrors(ObjSectionToIDOrErr.takeError(), ErrStream, "");
261     return nullptr;
262   }
263 }
264 
265 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
266                                              uint64_t Offset, uint64_t Value,
267                                              uint32_t Type, int64_t Addend,
268                                              uint64_t SymOffset) {
269   switch (Type) {
270   default:
271     llvm_unreachable("Relocation type not implemented yet!");
272     break;
273   case ELF::R_X86_64_NONE:
274     break;
275   case ELF::R_X86_64_64: {
276     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
277         Value + Addend;
278     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
279                  << format("%p\n", Section.getAddressWithOffset(Offset)));
280     break;
281   }
282   case ELF::R_X86_64_32:
283   case ELF::R_X86_64_32S: {
284     Value += Addend;
285     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
286            (Type == ELF::R_X86_64_32S &&
287             ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
288     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
289     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
290         TruncatedAddr;
291     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
292                  << format("%p\n", Section.getAddressWithOffset(Offset)));
293     break;
294   }
295   case ELF::R_X86_64_PC8: {
296     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
297     int64_t RealOffset = Value + Addend - FinalAddress;
298     assert(isInt<8>(RealOffset));
299     int8_t TruncOffset = (RealOffset & 0xFF);
300     Section.getAddress()[Offset] = TruncOffset;
301     break;
302   }
303   case ELF::R_X86_64_PC32: {
304     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
305     int64_t RealOffset = Value + Addend - FinalAddress;
306     assert(isInt<32>(RealOffset));
307     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
308     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
309         TruncOffset;
310     break;
311   }
312   case ELF::R_X86_64_PC64: {
313     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
314     int64_t RealOffset = Value + Addend - FinalAddress;
315     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
316         RealOffset;
317     break;
318   }
319   }
320 }
321 
322 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
323                                           uint64_t Offset, uint32_t Value,
324                                           uint32_t Type, int32_t Addend) {
325   switch (Type) {
326   case ELF::R_386_32: {
327     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
328         Value + Addend;
329     break;
330   }
331   case ELF::R_386_PC32: {
332     uint32_t FinalAddress =
333         Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
334     uint32_t RealOffset = Value + Addend - FinalAddress;
335     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
336         RealOffset;
337     break;
338   }
339   default:
340     // There are other relocation types, but it appears these are the
341     // only ones currently used by the LLVM ELF object writer
342     llvm_unreachable("Relocation type not implemented yet!");
343     break;
344   }
345 }
346 
347 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
348                                               uint64_t Offset, uint64_t Value,
349                                               uint32_t Type, int64_t Addend) {
350   uint32_t *TargetPtr =
351       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
352   uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
353   // Data should use target endian. Code should always use little endian.
354   bool isBE = Arch == Triple::aarch64_be;
355 
356   DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
357                << format("%llx", Section.getAddressWithOffset(Offset))
358                << " FinalAddress: 0x" << format("%llx", FinalAddress)
359                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
360                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
361                << "\n");
362 
363   switch (Type) {
364   default:
365     llvm_unreachable("Relocation type not implemented yet!");
366     break;
367   case ELF::R_AARCH64_ABS16: {
368     uint64_t Result = Value + Addend;
369     assert(static_cast<int64_t>(Result) >= INT16_MIN && Result < UINT16_MAX);
370     write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU));
371     break;
372   }
373   case ELF::R_AARCH64_ABS32: {
374     uint64_t Result = Value + Addend;
375     assert(static_cast<int64_t>(Result) >= INT32_MIN && Result < UINT32_MAX);
376     write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
377     break;
378   }
379   case ELF::R_AARCH64_ABS64:
380     write(isBE, TargetPtr, Value + Addend);
381     break;
382   case ELF::R_AARCH64_PREL32: {
383     uint64_t Result = Value + Addend - FinalAddress;
384     assert(static_cast<int64_t>(Result) >= INT32_MIN &&
385            static_cast<int64_t>(Result) <= UINT32_MAX);
386     write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
387     break;
388   }
389   case ELF::R_AARCH64_PREL64:
390     write(isBE, TargetPtr, Value + Addend - FinalAddress);
391     break;
392   case ELF::R_AARCH64_CALL26: // fallthrough
393   case ELF::R_AARCH64_JUMP26: {
394     // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
395     // calculation.
396     uint64_t BranchImm = Value + Addend - FinalAddress;
397 
398     // "Check that -2^27 <= result < 2^27".
399     assert(isInt<28>(BranchImm));
400     or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) >> 2);
401     break;
402   }
403   case ELF::R_AARCH64_MOVW_UABS_G3:
404     or32le(TargetPtr, ((Value + Addend) & 0xFFFF000000000000) >> 43);
405     break;
406   case ELF::R_AARCH64_MOVW_UABS_G2_NC:
407     or32le(TargetPtr, ((Value + Addend) & 0xFFFF00000000) >> 27);
408     break;
409   case ELF::R_AARCH64_MOVW_UABS_G1_NC:
410     or32le(TargetPtr, ((Value + Addend) & 0xFFFF0000) >> 11);
411     break;
412   case ELF::R_AARCH64_MOVW_UABS_G0_NC:
413     or32le(TargetPtr, ((Value + Addend) & 0xFFFF) << 5);
414     break;
415   case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
416     // Operation: Page(S+A) - Page(P)
417     uint64_t Result =
418         ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
419 
420     // Check that -2^32 <= X < 2^32
421     assert(isInt<33>(Result) && "overflow check failed for relocation");
422 
423     // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
424     // from bits 32:12 of X.
425     write32AArch64Addr(TargetPtr, Result >> 12);
426     break;
427   }
428   case ELF::R_AARCH64_ADD_ABS_LO12_NC:
429     // Operation: S + A
430     // Immediate goes in bits 21:10 of LD/ST instruction, taken
431     // from bits 11:0 of X
432     or32AArch64Imm(TargetPtr, Value + Addend);
433     break;
434   case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
435     // Operation: S + A
436     // Immediate goes in bits 21:10 of LD/ST instruction, taken
437     // from bits 11:0 of X
438     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 0, 11));
439     break;
440   case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
441     // Operation: S + A
442     // Immediate goes in bits 21:10 of LD/ST instruction, taken
443     // from bits 11:1 of X
444     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 1, 11));
445     break;
446   case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
447     // Operation: S + A
448     // Immediate goes in bits 21:10 of LD/ST instruction, taken
449     // from bits 11:2 of X
450     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 2, 11));
451     break;
452   case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
453     // Operation: S + A
454     // Immediate goes in bits 21:10 of LD/ST instruction, taken
455     // from bits 11:3 of X
456     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 3, 11));
457     break;
458   case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
459     // Operation: S + A
460     // Immediate goes in bits 21:10 of LD/ST instruction, taken
461     // from bits 11:4 of X
462     or32AArch64Imm(TargetPtr, getBits(Value + Addend, 4, 11));
463     break;
464   }
465 }
466 
467 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
468                                           uint64_t Offset, uint32_t Value,
469                                           uint32_t Type, int32_t Addend) {
470   // TODO: Add Thumb relocations.
471   uint32_t *TargetPtr =
472       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
473   uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
474   Value += Addend;
475 
476   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
477                << Section.getAddressWithOffset(Offset)
478                << " FinalAddress: " << format("%p", FinalAddress) << " Value: "
479                << format("%x", Value) << " Type: " << format("%x", Type)
480                << " Addend: " << format("%x", Addend) << "\n");
481 
482   switch (Type) {
483   default:
484     llvm_unreachable("Not implemented relocation type!");
485 
486   case ELF::R_ARM_NONE:
487     break;
488     // Write a 31bit signed offset
489   case ELF::R_ARM_PREL31:
490     support::ulittle32_t::ref{TargetPtr} =
491         (support::ulittle32_t::ref{TargetPtr} & 0x80000000) |
492         ((Value - FinalAddress) & ~0x80000000);
493     break;
494   case ELF::R_ARM_TARGET1:
495   case ELF::R_ARM_ABS32:
496     support::ulittle32_t::ref{TargetPtr} = Value;
497     break;
498     // Write first 16 bit of 32 bit value to the mov instruction.
499     // Last 4 bit should be shifted.
500   case ELF::R_ARM_MOVW_ABS_NC:
501   case ELF::R_ARM_MOVT_ABS:
502     if (Type == ELF::R_ARM_MOVW_ABS_NC)
503       Value = Value & 0xFFFF;
504     else if (Type == ELF::R_ARM_MOVT_ABS)
505       Value = (Value >> 16) & 0xFFFF;
506     support::ulittle32_t::ref{TargetPtr} =
507         (support::ulittle32_t::ref{TargetPtr} & ~0x000F0FFF) | (Value & 0xFFF) |
508         (((Value >> 12) & 0xF) << 16);
509     break;
510     // Write 24 bit relative value to the branch instruction.
511   case ELF::R_ARM_PC24: // Fall through.
512   case ELF::R_ARM_CALL: // Fall through.
513   case ELF::R_ARM_JUMP24:
514     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
515     RelValue = (RelValue & 0x03FFFFFC) >> 2;
516     assert((support::ulittle32_t::ref{TargetPtr} & 0xFFFFFF) == 0xFFFFFE);
517     support::ulittle32_t::ref{TargetPtr} =
518         (support::ulittle32_t::ref{TargetPtr} & 0xFF000000) | RelValue;
519     break;
520   }
521 }
522 
523 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
524   if (Arch == Triple::UnknownArch ||
525       !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
526     IsMipsO32ABI = false;
527     IsMipsN32ABI = false;
528     IsMipsN64ABI = false;
529     return;
530   }
531   unsigned AbiVariant;
532   Obj.getPlatformFlags(AbiVariant);
533   IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
534   IsMipsN32ABI = AbiVariant & ELF::EF_MIPS_ABI2;
535   IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips");
536 }
537 
538 // Return the .TOC. section and offset.
539 Error RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
540                                           ObjSectionToIDMap &LocalSections,
541                                           RelocationValueRef &Rel) {
542   // Set a default SectionID in case we do not find a TOC section below.
543   // This may happen for references to TOC base base (sym@toc, .odp
544   // relocation) without a .toc directive.  In this case just use the
545   // first section (which is usually the .odp) since the code won't
546   // reference the .toc base directly.
547   Rel.SymbolName = nullptr;
548   Rel.SectionID = 0;
549 
550   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
551   // order. The TOC starts where the first of these sections starts.
552   for (auto &Section: Obj.sections()) {
553     StringRef SectionName;
554     if (auto EC = Section.getName(SectionName))
555       return errorCodeToError(EC);
556 
557     if (SectionName == ".got"
558         || SectionName == ".toc"
559         || SectionName == ".tocbss"
560         || SectionName == ".plt") {
561       if (auto SectionIDOrErr =
562             findOrEmitSection(Obj, Section, false, LocalSections))
563         Rel.SectionID = *SectionIDOrErr;
564       else
565         return SectionIDOrErr.takeError();
566       break;
567     }
568   }
569 
570   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
571   // thus permitting a full 64 Kbytes segment.
572   Rel.Addend = 0x8000;
573 
574   return Error::success();
575 }
576 
577 // Returns the sections and offset associated with the ODP entry referenced
578 // by Symbol.
579 Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
580                                           ObjSectionToIDMap &LocalSections,
581                                           RelocationValueRef &Rel) {
582   // Get the ELF symbol value (st_value) to compare with Relocation offset in
583   // .opd entries
584   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
585        si != se; ++si) {
586     section_iterator RelSecI = si->getRelocatedSection();
587     if (RelSecI == Obj.section_end())
588       continue;
589 
590     StringRef RelSectionName;
591     if (auto EC = RelSecI->getName(RelSectionName))
592       return errorCodeToError(EC);
593 
594     if (RelSectionName != ".opd")
595       continue;
596 
597     for (elf_relocation_iterator i = si->relocation_begin(),
598                                  e = si->relocation_end();
599          i != e;) {
600       // The R_PPC64_ADDR64 relocation indicates the first field
601       // of a .opd entry
602       uint64_t TypeFunc = i->getType();
603       if (TypeFunc != ELF::R_PPC64_ADDR64) {
604         ++i;
605         continue;
606       }
607 
608       uint64_t TargetSymbolOffset = i->getOffset();
609       symbol_iterator TargetSymbol = i->getSymbol();
610       int64_t Addend;
611       if (auto AddendOrErr = i->getAddend())
612         Addend = *AddendOrErr;
613       else
614         return AddendOrErr.takeError();
615 
616       ++i;
617       if (i == e)
618         break;
619 
620       // Just check if following relocation is a R_PPC64_TOC
621       uint64_t TypeTOC = i->getType();
622       if (TypeTOC != ELF::R_PPC64_TOC)
623         continue;
624 
625       // Finally compares the Symbol value and the target symbol offset
626       // to check if this .opd entry refers to the symbol the relocation
627       // points to.
628       if (Rel.Addend != (int64_t)TargetSymbolOffset)
629         continue;
630 
631       section_iterator TSI = Obj.section_end();
632       if (auto TSIOrErr = TargetSymbol->getSection())
633         TSI = *TSIOrErr;
634       else
635         return TSIOrErr.takeError();
636       assert(TSI != Obj.section_end() && "TSI should refer to a valid section");
637 
638       bool IsCode = TSI->isText();
639       if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode,
640                                                   LocalSections))
641         Rel.SectionID = *SectionIDOrErr;
642       else
643         return SectionIDOrErr.takeError();
644       Rel.Addend = (intptr_t)Addend;
645       return Error::success();
646     }
647   }
648   llvm_unreachable("Attempting to get address of ODP entry!");
649 }
650 
651 // Relocation masks following the #lo(value), #hi(value), #ha(value),
652 // #higher(value), #highera(value), #highest(value), and #highesta(value)
653 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
654 // document.
655 
656 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
657 
658 static inline uint16_t applyPPChi(uint64_t value) {
659   return (value >> 16) & 0xffff;
660 }
661 
662 static inline uint16_t applyPPCha (uint64_t value) {
663   return ((value + 0x8000) >> 16) & 0xffff;
664 }
665 
666 static inline uint16_t applyPPChigher(uint64_t value) {
667   return (value >> 32) & 0xffff;
668 }
669 
670 static inline uint16_t applyPPChighera (uint64_t value) {
671   return ((value + 0x8000) >> 32) & 0xffff;
672 }
673 
674 static inline uint16_t applyPPChighest(uint64_t value) {
675   return (value >> 48) & 0xffff;
676 }
677 
678 static inline uint16_t applyPPChighesta (uint64_t value) {
679   return ((value + 0x8000) >> 48) & 0xffff;
680 }
681 
682 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
683                                             uint64_t Offset, uint64_t Value,
684                                             uint32_t Type, int64_t Addend) {
685   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
686   switch (Type) {
687   default:
688     llvm_unreachable("Relocation type not implemented yet!");
689     break;
690   case ELF::R_PPC_ADDR16_LO:
691     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
692     break;
693   case ELF::R_PPC_ADDR16_HI:
694     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
695     break;
696   case ELF::R_PPC_ADDR16_HA:
697     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
698     break;
699   }
700 }
701 
702 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
703                                             uint64_t Offset, uint64_t Value,
704                                             uint32_t Type, int64_t Addend) {
705   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
706   switch (Type) {
707   default:
708     llvm_unreachable("Relocation type not implemented yet!");
709     break;
710   case ELF::R_PPC64_ADDR16:
711     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
712     break;
713   case ELF::R_PPC64_ADDR16_DS:
714     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
715     break;
716   case ELF::R_PPC64_ADDR16_LO:
717     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
718     break;
719   case ELF::R_PPC64_ADDR16_LO_DS:
720     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
721     break;
722   case ELF::R_PPC64_ADDR16_HI:
723     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
724     break;
725   case ELF::R_PPC64_ADDR16_HA:
726     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
727     break;
728   case ELF::R_PPC64_ADDR16_HIGHER:
729     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
730     break;
731   case ELF::R_PPC64_ADDR16_HIGHERA:
732     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
733     break;
734   case ELF::R_PPC64_ADDR16_HIGHEST:
735     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
736     break;
737   case ELF::R_PPC64_ADDR16_HIGHESTA:
738     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
739     break;
740   case ELF::R_PPC64_ADDR14: {
741     assert(((Value + Addend) & 3) == 0);
742     // Preserve the AA/LK bits in the branch instruction
743     uint8_t aalk = *(LocalAddress + 3);
744     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
745   } break;
746   case ELF::R_PPC64_REL16_LO: {
747     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
748     uint64_t Delta = Value - FinalAddress + Addend;
749     writeInt16BE(LocalAddress, applyPPClo(Delta));
750   } break;
751   case ELF::R_PPC64_REL16_HI: {
752     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
753     uint64_t Delta = Value - FinalAddress + Addend;
754     writeInt16BE(LocalAddress, applyPPChi(Delta));
755   } break;
756   case ELF::R_PPC64_REL16_HA: {
757     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
758     uint64_t Delta = Value - FinalAddress + Addend;
759     writeInt16BE(LocalAddress, applyPPCha(Delta));
760   } break;
761   case ELF::R_PPC64_ADDR32: {
762     int64_t Result = static_cast<int64_t>(Value + Addend);
763     if (SignExtend64<32>(Result) != Result)
764       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
765     writeInt32BE(LocalAddress, Result);
766   } break;
767   case ELF::R_PPC64_REL24: {
768     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
769     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
770     if (SignExtend64<26>(delta) != delta)
771       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
772     // Generates a 'bl <address>' instruction
773     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
774   } break;
775   case ELF::R_PPC64_REL32: {
776     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
777     int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
778     if (SignExtend64<32>(delta) != delta)
779       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
780     writeInt32BE(LocalAddress, delta);
781   } break;
782   case ELF::R_PPC64_REL64: {
783     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
784     uint64_t Delta = Value - FinalAddress + Addend;
785     writeInt64BE(LocalAddress, Delta);
786   } break;
787   case ELF::R_PPC64_ADDR64:
788     writeInt64BE(LocalAddress, Value + Addend);
789     break;
790   }
791 }
792 
793 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
794                                               uint64_t Offset, uint64_t Value,
795                                               uint32_t Type, int64_t Addend) {
796   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
797   switch (Type) {
798   default:
799     llvm_unreachable("Relocation type not implemented yet!");
800     break;
801   case ELF::R_390_PC16DBL:
802   case ELF::R_390_PLT16DBL: {
803     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
804     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
805     writeInt16BE(LocalAddress, Delta / 2);
806     break;
807   }
808   case ELF::R_390_PC32DBL:
809   case ELF::R_390_PLT32DBL: {
810     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
811     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
812     writeInt32BE(LocalAddress, Delta / 2);
813     break;
814   }
815   case ELF::R_390_PC16: {
816     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
817     assert(int16_t(Delta) == Delta && "R_390_PC16 overflow");
818     writeInt16BE(LocalAddress, Delta);
819     break;
820   }
821   case ELF::R_390_PC32: {
822     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
823     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
824     writeInt32BE(LocalAddress, Delta);
825     break;
826   }
827   case ELF::R_390_PC64: {
828     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
829     writeInt64BE(LocalAddress, Delta);
830     break;
831   }
832   case ELF::R_390_8:
833     *LocalAddress = (uint8_t)(Value + Addend);
834     break;
835   case ELF::R_390_16:
836     writeInt16BE(LocalAddress, Value + Addend);
837     break;
838   case ELF::R_390_32:
839     writeInt32BE(LocalAddress, Value + Addend);
840     break;
841   case ELF::R_390_64:
842     writeInt64BE(LocalAddress, Value + Addend);
843     break;
844   }
845 }
846 
847 void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
848                                           uint64_t Offset, uint64_t Value,
849                                           uint32_t Type, int64_t Addend) {
850   bool isBE = Arch == Triple::bpfeb;
851 
852   switch (Type) {
853   default:
854     llvm_unreachable("Relocation type not implemented yet!");
855     break;
856   case ELF::R_BPF_NONE:
857     break;
858   case ELF::R_BPF_64_64: {
859     write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
860     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
861                  << format("%p\n", Section.getAddressWithOffset(Offset)));
862     break;
863   }
864   case ELF::R_BPF_64_32: {
865     Value += Addend;
866     assert(Value <= UINT32_MAX);
867     write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
868     DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
869                  << format("%p\n", Section.getAddressWithOffset(Offset)));
870     break;
871   }
872   }
873 }
874 
875 // The target location for the relocation is described by RE.SectionID and
876 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
877 // SectionEntry has three members describing its location.
878 // SectionEntry::Address is the address at which the section has been loaded
879 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
880 // address that the section will have in the target process.
881 // SectionEntry::ObjAddress is the address of the bits for this section in the
882 // original emitted object image (also in the current address space).
883 //
884 // Relocations will be applied as if the section were loaded at
885 // SectionEntry::LoadAddress, but they will be applied at an address based
886 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
887 // Target memory contents if they are required for value calculations.
888 //
889 // The Value parameter here is the load address of the symbol for the
890 // relocation to be applied.  For relocations which refer to symbols in the
891 // current object Value will be the LoadAddress of the section in which
892 // the symbol resides (RE.Addend provides additional information about the
893 // symbol location).  For external symbols, Value will be the address of the
894 // symbol in the target address space.
895 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
896                                        uint64_t Value) {
897   const SectionEntry &Section = Sections[RE.SectionID];
898   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
899                            RE.SymOffset, RE.SectionID);
900 }
901 
902 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
903                                        uint64_t Offset, uint64_t Value,
904                                        uint32_t Type, int64_t Addend,
905                                        uint64_t SymOffset, SID SectionID) {
906   switch (Arch) {
907   case Triple::x86_64:
908     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
909     break;
910   case Triple::x86:
911     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
912                          (uint32_t)(Addend & 0xffffffffL));
913     break;
914   case Triple::aarch64:
915   case Triple::aarch64_be:
916     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
917     break;
918   case Triple::arm: // Fall through.
919   case Triple::armeb:
920   case Triple::thumb:
921   case Triple::thumbeb:
922     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
923                          (uint32_t)(Addend & 0xffffffffL));
924     break;
925   case Triple::ppc:
926     resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
927     break;
928   case Triple::ppc64: // Fall through.
929   case Triple::ppc64le:
930     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
931     break;
932   case Triple::systemz:
933     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
934     break;
935   case Triple::bpfel:
936   case Triple::bpfeb:
937     resolveBPFRelocation(Section, Offset, Value, Type, Addend);
938     break;
939   default:
940     llvm_unreachable("Unsupported CPU type!");
941   }
942 }
943 
944 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
945   return (void *)(Sections[SectionID].getObjAddress() + Offset);
946 }
947 
948 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
949   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
950   if (Value.SymbolName)
951     addRelocationForSymbol(RE, Value.SymbolName);
952   else
953     addRelocationForSection(RE, Value.SectionID);
954 }
955 
956 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
957                                                  bool IsLocal) const {
958   switch (RelType) {
959   case ELF::R_MICROMIPS_GOT16:
960     if (IsLocal)
961       return ELF::R_MICROMIPS_LO16;
962     break;
963   case ELF::R_MICROMIPS_HI16:
964     return ELF::R_MICROMIPS_LO16;
965   case ELF::R_MIPS_GOT16:
966     if (IsLocal)
967       return ELF::R_MIPS_LO16;
968     break;
969   case ELF::R_MIPS_HI16:
970     return ELF::R_MIPS_LO16;
971   case ELF::R_MIPS_PCHI16:
972     return ELF::R_MIPS_PCLO16;
973   default:
974     break;
975   }
976   return ELF::R_MIPS_NONE;
977 }
978 
979 // Sometimes we don't need to create thunk for a branch.
980 // This typically happens when branch target is located
981 // in the same object file. In such case target is either
982 // a weak symbol or symbol in a different executable section.
983 // This function checks if branch target is located in the
984 // same object file and if distance between source and target
985 // fits R_AARCH64_CALL26 relocation. If both conditions are
986 // met, it emits direct jump to the target and returns true.
987 // Otherwise false is returned and thunk is created.
988 bool RuntimeDyldELF::resolveAArch64ShortBranch(
989     unsigned SectionID, relocation_iterator RelI,
990     const RelocationValueRef &Value) {
991   uint64_t Address;
992   if (Value.SymbolName) {
993     auto Loc = GlobalSymbolTable.find(Value.SymbolName);
994 
995     // Don't create direct branch for external symbols.
996     if (Loc == GlobalSymbolTable.end())
997       return false;
998 
999     const auto &SymInfo = Loc->second;
1000     Address =
1001         uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset(
1002             SymInfo.getOffset()));
1003   } else {
1004     Address = uint64_t(Sections[Value.SectionID].getLoadAddress());
1005   }
1006   uint64_t Offset = RelI->getOffset();
1007   uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset);
1008 
1009   // R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27
1010   // If distance between source and target is out of range then we should
1011   // create thunk.
1012   if (!isInt<28>(Address + Value.Addend - SourceAddress))
1013     return false;
1014 
1015   resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(),
1016                     Value.Addend);
1017 
1018   return true;
1019 }
1020 
1021 void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID,
1022                                           const RelocationValueRef &Value,
1023                                           relocation_iterator RelI,
1024                                           StubMap &Stubs) {
1025 
1026   DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1027   SectionEntry &Section = Sections[SectionID];
1028 
1029   uint64_t Offset = RelI->getOffset();
1030   unsigned RelType = RelI->getType();
1031   // Look for an existing stub.
1032   StubMap::const_iterator i = Stubs.find(Value);
1033   if (i != Stubs.end()) {
1034     resolveRelocation(Section, Offset,
1035                       (uint64_t)Section.getAddressWithOffset(i->second),
1036                       RelType, 0);
1037     DEBUG(dbgs() << " Stub function found\n");
1038   } else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) {
1039     // Create a new stub function.
1040     DEBUG(dbgs() << " Create a new stub function\n");
1041     Stubs[Value] = Section.getStubOffset();
1042     uint8_t *StubTargetAddr = createStubFunction(
1043         Section.getAddressWithOffset(Section.getStubOffset()));
1044 
1045     RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(),
1046                               ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1047     RelocationEntry REmovk_g2(SectionID,
1048                               StubTargetAddr - Section.getAddress() + 4,
1049                               ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1050     RelocationEntry REmovk_g1(SectionID,
1051                               StubTargetAddr - Section.getAddress() + 8,
1052                               ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1053     RelocationEntry REmovk_g0(SectionID,
1054                               StubTargetAddr - Section.getAddress() + 12,
1055                               ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1056 
1057     if (Value.SymbolName) {
1058       addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1059       addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1060       addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1061       addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1062     } else {
1063       addRelocationForSection(REmovz_g3, Value.SectionID);
1064       addRelocationForSection(REmovk_g2, Value.SectionID);
1065       addRelocationForSection(REmovk_g1, Value.SectionID);
1066       addRelocationForSection(REmovk_g0, Value.SectionID);
1067     }
1068     resolveRelocation(Section, Offset,
1069                       reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
1070                           Section.getStubOffset())),
1071                       RelType, 0);
1072     Section.advanceStubOffset(getMaxStubSize());
1073   }
1074 }
1075 
1076 Expected<relocation_iterator>
1077 RuntimeDyldELF::processRelocationRef(
1078     unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1079     ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1080   const auto &Obj = cast<ELFObjectFileBase>(O);
1081   uint64_t RelType = RelI->getType();
1082   int64_t Addend = 0;
1083   if (Expected<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend())
1084     Addend = *AddendOrErr;
1085   else
1086     consumeError(AddendOrErr.takeError());
1087   elf_symbol_iterator Symbol = RelI->getSymbol();
1088 
1089   // Obtain the symbol name which is referenced in the relocation
1090   StringRef TargetName;
1091   if (Symbol != Obj.symbol_end()) {
1092     if (auto TargetNameOrErr = Symbol->getName())
1093       TargetName = *TargetNameOrErr;
1094     else
1095       return TargetNameOrErr.takeError();
1096   }
1097   DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1098                << " TargetName: " << TargetName << "\n");
1099   RelocationValueRef Value;
1100   // First search for the symbol in the local symbol table
1101   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1102 
1103   // Search for the symbol in the global symbol table
1104   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1105   if (Symbol != Obj.symbol_end()) {
1106     gsi = GlobalSymbolTable.find(TargetName.data());
1107     Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType();
1108     if (!SymTypeOrErr) {
1109       std::string Buf;
1110       raw_string_ostream OS(Buf);
1111       logAllUnhandledErrors(SymTypeOrErr.takeError(), OS, "");
1112       OS.flush();
1113       report_fatal_error(Buf);
1114     }
1115     SymType = *SymTypeOrErr;
1116   }
1117   if (gsi != GlobalSymbolTable.end()) {
1118     const auto &SymInfo = gsi->second;
1119     Value.SectionID = SymInfo.getSectionID();
1120     Value.Offset = SymInfo.getOffset();
1121     Value.Addend = SymInfo.getOffset() + Addend;
1122   } else {
1123     switch (SymType) {
1124     case SymbolRef::ST_Debug: {
1125       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1126       // and can be changed by another developers. Maybe best way is add
1127       // a new symbol type ST_Section to SymbolRef and use it.
1128       auto SectionOrErr = Symbol->getSection();
1129       if (!SectionOrErr) {
1130         std::string Buf;
1131         raw_string_ostream OS(Buf);
1132         logAllUnhandledErrors(SectionOrErr.takeError(), OS, "");
1133         OS.flush();
1134         report_fatal_error(Buf);
1135       }
1136       section_iterator si = *SectionOrErr;
1137       if (si == Obj.section_end())
1138         llvm_unreachable("Symbol section not found, bad object file format!");
1139       DEBUG(dbgs() << "\t\tThis is section symbol\n");
1140       bool isCode = si->isText();
1141       if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode,
1142                                                   ObjSectionToID))
1143         Value.SectionID = *SectionIDOrErr;
1144       else
1145         return SectionIDOrErr.takeError();
1146       Value.Addend = Addend;
1147       break;
1148     }
1149     case SymbolRef::ST_Data:
1150     case SymbolRef::ST_Function:
1151     case SymbolRef::ST_Unknown: {
1152       Value.SymbolName = TargetName.data();
1153       Value.Addend = Addend;
1154 
1155       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1156       // will manifest here as a NULL symbol name.
1157       // We can set this as a valid (but empty) symbol name, and rely
1158       // on addRelocationForSymbol to handle this.
1159       if (!Value.SymbolName)
1160         Value.SymbolName = "";
1161       break;
1162     }
1163     default:
1164       llvm_unreachable("Unresolved symbol type!");
1165       break;
1166     }
1167   }
1168 
1169   uint64_t Offset = RelI->getOffset();
1170 
1171   DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1172                << "\n");
1173   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) {
1174     if (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26) {
1175       resolveAArch64Branch(SectionID, Value, RelI, Stubs);
1176     } else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) {
1177       // Craete new GOT entry or find existing one. If GOT entry is
1178       // to be created, then we also emit ABS64 relocation for it.
1179       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1180       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1181                                  ELF::R_AARCH64_ADR_PREL_PG_HI21);
1182 
1183     } else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) {
1184       uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1185       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1186                                  ELF::R_AARCH64_LDST64_ABS_LO12_NC);
1187     } else {
1188       processSimpleRelocation(SectionID, Offset, RelType, Value);
1189     }
1190   } else if (Arch == Triple::arm) {
1191     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1192       RelType == ELF::R_ARM_JUMP24) {
1193       // This is an ARM branch relocation, need to use a stub function.
1194       DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n");
1195       SectionEntry &Section = Sections[SectionID];
1196 
1197       // Look for an existing stub.
1198       StubMap::const_iterator i = Stubs.find(Value);
1199       if (i != Stubs.end()) {
1200         resolveRelocation(
1201             Section, Offset,
1202             reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
1203             RelType, 0);
1204         DEBUG(dbgs() << " Stub function found\n");
1205       } else {
1206         // Create a new stub function.
1207         DEBUG(dbgs() << " Create a new stub function\n");
1208         Stubs[Value] = Section.getStubOffset();
1209         uint8_t *StubTargetAddr = createStubFunction(
1210             Section.getAddressWithOffset(Section.getStubOffset()));
1211         RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1212                            ELF::R_ARM_ABS32, Value.Addend);
1213         if (Value.SymbolName)
1214           addRelocationForSymbol(RE, Value.SymbolName);
1215         else
1216           addRelocationForSection(RE, Value.SectionID);
1217 
1218         resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1219                                                Section.getAddressWithOffset(
1220                                                    Section.getStubOffset())),
1221                           RelType, 0);
1222         Section.advanceStubOffset(getMaxStubSize());
1223       }
1224     } else {
1225       uint32_t *Placeholder =
1226         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1227       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1228           RelType == ELF::R_ARM_ABS32) {
1229         Value.Addend += *Placeholder;
1230       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1231         // See ELF for ARM documentation
1232         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1233       }
1234       processSimpleRelocation(SectionID, Offset, RelType, Value);
1235     }
1236   } else if (IsMipsO32ABI) {
1237     uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1238         computePlaceholderAddress(SectionID, Offset));
1239     uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1240     if (RelType == ELF::R_MIPS_26) {
1241       // This is an Mips branch relocation, need to use a stub function.
1242       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1243       SectionEntry &Section = Sections[SectionID];
1244 
1245       // Extract the addend from the instruction.
1246       // We shift up by two since the Value will be down shifted again
1247       // when applying the relocation.
1248       uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1249 
1250       Value.Addend += Addend;
1251 
1252       //  Look up for existing stub.
1253       StubMap::const_iterator i = Stubs.find(Value);
1254       if (i != Stubs.end()) {
1255         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1256         addRelocationForSection(RE, SectionID);
1257         DEBUG(dbgs() << " Stub function found\n");
1258       } else {
1259         // Create a new stub function.
1260         DEBUG(dbgs() << " Create a new stub function\n");
1261         Stubs[Value] = Section.getStubOffset();
1262 
1263         unsigned AbiVariant;
1264         O.getPlatformFlags(AbiVariant);
1265 
1266         uint8_t *StubTargetAddr = createStubFunction(
1267             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1268 
1269         // Creating Hi and Lo relocations for the filled stub instructions.
1270         RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1271                              ELF::R_MIPS_HI16, Value.Addend);
1272         RelocationEntry RELo(SectionID,
1273                              StubTargetAddr - Section.getAddress() + 4,
1274                              ELF::R_MIPS_LO16, Value.Addend);
1275 
1276         if (Value.SymbolName) {
1277           addRelocationForSymbol(REHi, Value.SymbolName);
1278           addRelocationForSymbol(RELo, Value.SymbolName);
1279         } else {
1280           addRelocationForSection(REHi, Value.SectionID);
1281           addRelocationForSection(RELo, Value.SectionID);
1282         }
1283 
1284         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1285         addRelocationForSection(RE, SectionID);
1286         Section.advanceStubOffset(getMaxStubSize());
1287       }
1288     } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
1289       int64_t Addend = (Opcode & 0x0000ffff) << 16;
1290       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1291       PendingRelocs.push_back(std::make_pair(Value, RE));
1292     } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
1293       int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
1294       for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
1295         const RelocationValueRef &MatchingValue = I->first;
1296         RelocationEntry &Reloc = I->second;
1297         if (MatchingValue == Value &&
1298             RelType == getMatchingLoRelocation(Reloc.RelType) &&
1299             SectionID == Reloc.SectionID) {
1300           Reloc.Addend += Addend;
1301           if (Value.SymbolName)
1302             addRelocationForSymbol(Reloc, Value.SymbolName);
1303           else
1304             addRelocationForSection(Reloc, Value.SectionID);
1305           I = PendingRelocs.erase(I);
1306         } else
1307           ++I;
1308       }
1309       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1310       if (Value.SymbolName)
1311         addRelocationForSymbol(RE, Value.SymbolName);
1312       else
1313         addRelocationForSection(RE, Value.SectionID);
1314     } else {
1315       if (RelType == ELF::R_MIPS_32)
1316         Value.Addend += Opcode;
1317       else if (RelType == ELF::R_MIPS_PC16)
1318         Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1319       else if (RelType == ELF::R_MIPS_PC19_S2)
1320         Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1321       else if (RelType == ELF::R_MIPS_PC21_S2)
1322         Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1323       else if (RelType == ELF::R_MIPS_PC26_S2)
1324         Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1325       processSimpleRelocation(SectionID, Offset, RelType, Value);
1326     }
1327   } else if (IsMipsN32ABI || IsMipsN64ABI) {
1328     uint32_t r_type = RelType & 0xff;
1329     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1330     if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1331         || r_type == ELF::R_MIPS_GOT_DISP) {
1332       StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1333       if (i != GOTSymbolOffsets.end())
1334         RE.SymOffset = i->second;
1335       else {
1336         RE.SymOffset = allocateGOTEntries(1);
1337         GOTSymbolOffsets[TargetName] = RE.SymOffset;
1338       }
1339       if (Value.SymbolName)
1340         addRelocationForSymbol(RE, Value.SymbolName);
1341       else
1342         addRelocationForSection(RE, Value.SectionID);
1343     } else if (RelType == ELF::R_MIPS_26) {
1344       // This is an Mips branch relocation, need to use a stub function.
1345       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1346       SectionEntry &Section = Sections[SectionID];
1347 
1348       //  Look up for existing stub.
1349       StubMap::const_iterator i = Stubs.find(Value);
1350       if (i != Stubs.end()) {
1351         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1352         addRelocationForSection(RE, SectionID);
1353         DEBUG(dbgs() << " Stub function found\n");
1354       } else {
1355         // Create a new stub function.
1356         DEBUG(dbgs() << " Create a new stub function\n");
1357         Stubs[Value] = Section.getStubOffset();
1358 
1359         unsigned AbiVariant;
1360         O.getPlatformFlags(AbiVariant);
1361 
1362         uint8_t *StubTargetAddr = createStubFunction(
1363             Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1364 
1365         if (IsMipsN32ABI) {
1366           // Creating Hi and Lo relocations for the filled stub instructions.
1367           RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1368                                ELF::R_MIPS_HI16, Value.Addend);
1369           RelocationEntry RELo(SectionID,
1370                                StubTargetAddr - Section.getAddress() + 4,
1371                                ELF::R_MIPS_LO16, Value.Addend);
1372           if (Value.SymbolName) {
1373             addRelocationForSymbol(REHi, Value.SymbolName);
1374             addRelocationForSymbol(RELo, Value.SymbolName);
1375           } else {
1376             addRelocationForSection(REHi, Value.SectionID);
1377             addRelocationForSection(RELo, Value.SectionID);
1378           }
1379         } else {
1380           // Creating Highest, Higher, Hi and Lo relocations for the filled stub
1381           // instructions.
1382           RelocationEntry REHighest(SectionID,
1383                                     StubTargetAddr - Section.getAddress(),
1384                                     ELF::R_MIPS_HIGHEST, Value.Addend);
1385           RelocationEntry REHigher(SectionID,
1386                                    StubTargetAddr - Section.getAddress() + 4,
1387                                    ELF::R_MIPS_HIGHER, Value.Addend);
1388           RelocationEntry REHi(SectionID,
1389                                StubTargetAddr - Section.getAddress() + 12,
1390                                ELF::R_MIPS_HI16, Value.Addend);
1391           RelocationEntry RELo(SectionID,
1392                                StubTargetAddr - Section.getAddress() + 20,
1393                                ELF::R_MIPS_LO16, Value.Addend);
1394           if (Value.SymbolName) {
1395             addRelocationForSymbol(REHighest, Value.SymbolName);
1396             addRelocationForSymbol(REHigher, Value.SymbolName);
1397             addRelocationForSymbol(REHi, Value.SymbolName);
1398             addRelocationForSymbol(RELo, Value.SymbolName);
1399           } else {
1400             addRelocationForSection(REHighest, Value.SectionID);
1401             addRelocationForSection(REHigher, Value.SectionID);
1402             addRelocationForSection(REHi, Value.SectionID);
1403             addRelocationForSection(RELo, Value.SectionID);
1404           }
1405         }
1406         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1407         addRelocationForSection(RE, SectionID);
1408         Section.advanceStubOffset(getMaxStubSize());
1409       }
1410     } else {
1411       processSimpleRelocation(SectionID, Offset, RelType, Value);
1412     }
1413 
1414   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1415     if (RelType == ELF::R_PPC64_REL24) {
1416       // Determine ABI variant in use for this object.
1417       unsigned AbiVariant;
1418       Obj.getPlatformFlags(AbiVariant);
1419       AbiVariant &= ELF::EF_PPC64_ABI;
1420       // A PPC branch relocation will need a stub function if the target is
1421       // an external symbol (either Value.SymbolName is set, or SymType is
1422       // Symbol::ST_Unknown) or if the target address is not within the
1423       // signed 24-bits branch address.
1424       SectionEntry &Section = Sections[SectionID];
1425       uint8_t *Target = Section.getAddressWithOffset(Offset);
1426       bool RangeOverflow = false;
1427       if (!Value.SymbolName && SymType != SymbolRef::ST_Unknown) {
1428         if (AbiVariant != 2) {
1429           // In the ELFv1 ABI, a function call may point to the .opd entry,
1430           // so the final symbol value is calculated based on the relocation
1431           // values in the .opd section.
1432           if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value))
1433             return std::move(Err);
1434         } else {
1435           // In the ELFv2 ABI, a function symbol may provide a local entry
1436           // point, which must be used for direct calls.
1437           uint8_t SymOther = Symbol->getOther();
1438           Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1439         }
1440         uint8_t *RelocTarget =
1441             Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
1442         int64_t delta = static_cast<int64_t>(Target - RelocTarget);
1443         // If it is within 26-bits branch range, just set the branch target
1444         if (SignExtend64<26>(delta) == delta) {
1445           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1446           addRelocationForSection(RE, Value.SectionID);
1447         } else {
1448           RangeOverflow = true;
1449         }
1450       }
1451       if (Value.SymbolName || SymType == SymbolRef::ST_Unknown ||
1452           RangeOverflow) {
1453         // It is an external symbol (either Value.SymbolName is set, or
1454         // SymType is SymbolRef::ST_Unknown) or out of range.
1455         StubMap::const_iterator i = Stubs.find(Value);
1456         if (i != Stubs.end()) {
1457           // Symbol function stub already created, just relocate to it
1458           resolveRelocation(Section, Offset,
1459                             reinterpret_cast<uint64_t>(
1460                                 Section.getAddressWithOffset(i->second)),
1461                             RelType, 0);
1462           DEBUG(dbgs() << " Stub function found\n");
1463         } else {
1464           // Create a new stub function.
1465           DEBUG(dbgs() << " Create a new stub function\n");
1466           Stubs[Value] = Section.getStubOffset();
1467           uint8_t *StubTargetAddr = createStubFunction(
1468               Section.getAddressWithOffset(Section.getStubOffset()),
1469               AbiVariant);
1470           RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1471                              ELF::R_PPC64_ADDR64, Value.Addend);
1472 
1473           // Generates the 64-bits address loads as exemplified in section
1474           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1475           // apply to the low part of the instructions, so we have to update
1476           // the offset according to the target endianness.
1477           uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
1478           if (!IsTargetLittleEndian)
1479             StubRelocOffset += 2;
1480 
1481           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1482                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1483           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1484                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1485           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1486                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1487           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1488                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1489 
1490           if (Value.SymbolName) {
1491             addRelocationForSymbol(REhst, Value.SymbolName);
1492             addRelocationForSymbol(REhr, Value.SymbolName);
1493             addRelocationForSymbol(REh, Value.SymbolName);
1494             addRelocationForSymbol(REl, Value.SymbolName);
1495           } else {
1496             addRelocationForSection(REhst, Value.SectionID);
1497             addRelocationForSection(REhr, Value.SectionID);
1498             addRelocationForSection(REh, Value.SectionID);
1499             addRelocationForSection(REl, Value.SectionID);
1500           }
1501 
1502           resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1503                                                  Section.getAddressWithOffset(
1504                                                      Section.getStubOffset())),
1505                             RelType, 0);
1506           Section.advanceStubOffset(getMaxStubSize());
1507         }
1508         if (Value.SymbolName || SymType == SymbolRef::ST_Unknown) {
1509           // Restore the TOC for external calls
1510           if (AbiVariant == 2)
1511             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
1512           else
1513             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1514         }
1515       }
1516     } else if (RelType == ELF::R_PPC64_TOC16 ||
1517                RelType == ELF::R_PPC64_TOC16_DS ||
1518                RelType == ELF::R_PPC64_TOC16_LO ||
1519                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1520                RelType == ELF::R_PPC64_TOC16_HI ||
1521                RelType == ELF::R_PPC64_TOC16_HA) {
1522       // These relocations are supposed to subtract the TOC address from
1523       // the final value.  This does not fit cleanly into the RuntimeDyld
1524       // scheme, since there may be *two* sections involved in determining
1525       // the relocation value (the section of the symbol referred to by the
1526       // relocation, and the TOC section associated with the current module).
1527       //
1528       // Fortunately, these relocations are currently only ever generated
1529       // referring to symbols that themselves reside in the TOC, which means
1530       // that the two sections are actually the same.  Thus they cancel out
1531       // and we can immediately resolve the relocation right now.
1532       switch (RelType) {
1533       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1534       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1535       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1536       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1537       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1538       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1539       default: llvm_unreachable("Wrong relocation type.");
1540       }
1541 
1542       RelocationValueRef TOCValue;
1543       if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue))
1544         return std::move(Err);
1545       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1546         llvm_unreachable("Unsupported TOC relocation.");
1547       Value.Addend -= TOCValue.Addend;
1548       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1549     } else {
1550       // There are two ways to refer to the TOC address directly: either
1551       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1552       // ignored), or via any relocation that refers to the magic ".TOC."
1553       // symbols (in which case the addend is respected).
1554       if (RelType == ELF::R_PPC64_TOC) {
1555         RelType = ELF::R_PPC64_ADDR64;
1556         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1557           return std::move(Err);
1558       } else if (TargetName == ".TOC.") {
1559         if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1560           return std::move(Err);
1561         Value.Addend += Addend;
1562       }
1563 
1564       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1565 
1566       if (Value.SymbolName)
1567         addRelocationForSymbol(RE, Value.SymbolName);
1568       else
1569         addRelocationForSection(RE, Value.SectionID);
1570     }
1571   } else if (Arch == Triple::systemz &&
1572              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1573     // Create function stubs for both PLT and GOT references, regardless of
1574     // whether the GOT reference is to data or code.  The stub contains the
1575     // full address of the symbol, as needed by GOT references, and the
1576     // executable part only adds an overhead of 8 bytes.
1577     //
1578     // We could try to conserve space by allocating the code and data
1579     // parts of the stub separately.  However, as things stand, we allocate
1580     // a stub for every relocation, so using a GOT in JIT code should be
1581     // no less space efficient than using an explicit constant pool.
1582     DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1583     SectionEntry &Section = Sections[SectionID];
1584 
1585     // Look for an existing stub.
1586     StubMap::const_iterator i = Stubs.find(Value);
1587     uintptr_t StubAddress;
1588     if (i != Stubs.end()) {
1589       StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
1590       DEBUG(dbgs() << " Stub function found\n");
1591     } else {
1592       // Create a new stub function.
1593       DEBUG(dbgs() << " Create a new stub function\n");
1594 
1595       uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1596       uintptr_t StubAlignment = getStubAlignment();
1597       StubAddress =
1598           (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1599           -StubAlignment;
1600       unsigned StubOffset = StubAddress - BaseAddress;
1601 
1602       Stubs[Value] = StubOffset;
1603       createStubFunction((uint8_t *)StubAddress);
1604       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1605                          Value.Offset);
1606       if (Value.SymbolName)
1607         addRelocationForSymbol(RE, Value.SymbolName);
1608       else
1609         addRelocationForSection(RE, Value.SectionID);
1610       Section.advanceStubOffset(getMaxStubSize());
1611     }
1612 
1613     if (RelType == ELF::R_390_GOTENT)
1614       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1615                         Addend);
1616     else
1617       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1618   } else if (Arch == Triple::x86_64) {
1619     if (RelType == ELF::R_X86_64_PLT32) {
1620       // The way the PLT relocations normally work is that the linker allocates
1621       // the
1622       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1623       // entry will then jump to an address provided by the GOT.  On first call,
1624       // the
1625       // GOT address will point back into PLT code that resolves the symbol. After
1626       // the first call, the GOT entry points to the actual function.
1627       //
1628       // For local functions we're ignoring all of that here and just replacing
1629       // the PLT32 relocation type with PC32, which will translate the relocation
1630       // into a PC-relative call directly to the function. For external symbols we
1631       // can't be sure the function will be within 2^32 bytes of the call site, so
1632       // we need to create a stub, which calls into the GOT.  This case is
1633       // equivalent to the usual PLT implementation except that we use the stub
1634       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1635       // rather than allocating a PLT section.
1636       if (Value.SymbolName) {
1637         // This is a call to an external function.
1638         // Look for an existing stub.
1639         SectionEntry &Section = Sections[SectionID];
1640         StubMap::const_iterator i = Stubs.find(Value);
1641         uintptr_t StubAddress;
1642         if (i != Stubs.end()) {
1643           StubAddress = uintptr_t(Section.getAddress()) + i->second;
1644           DEBUG(dbgs() << " Stub function found\n");
1645         } else {
1646           // Create a new stub function (equivalent to a PLT entry).
1647           DEBUG(dbgs() << " Create a new stub function\n");
1648 
1649           uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1650           uintptr_t StubAlignment = getStubAlignment();
1651           StubAddress =
1652               (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1653               -StubAlignment;
1654           unsigned StubOffset = StubAddress - BaseAddress;
1655           Stubs[Value] = StubOffset;
1656           createStubFunction((uint8_t *)StubAddress);
1657 
1658           // Bump our stub offset counter
1659           Section.advanceStubOffset(getMaxStubSize());
1660 
1661           // Allocate a GOT Entry
1662           uint64_t GOTOffset = allocateGOTEntries(1);
1663 
1664           // The load of the GOT address has an addend of -4
1665           resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
1666                                      ELF::R_X86_64_PC32);
1667 
1668           // Fill in the value of the symbol we're targeting into the GOT
1669           addRelocationForSymbol(
1670               computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
1671               Value.SymbolName);
1672         }
1673 
1674         // Make the target call a call into the stub table.
1675         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1676                           Addend);
1677       } else {
1678         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1679                   Value.Offset);
1680         addRelocationForSection(RE, Value.SectionID);
1681       }
1682     } else if (RelType == ELF::R_X86_64_GOTPCREL ||
1683                RelType == ELF::R_X86_64_GOTPCRELX ||
1684                RelType == ELF::R_X86_64_REX_GOTPCRELX) {
1685       uint64_t GOTOffset = allocateGOTEntries(1);
1686       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1687                                  ELF::R_X86_64_PC32);
1688 
1689       // Fill in the value of the symbol we're targeting into the GOT
1690       RelocationEntry RE =
1691           computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1692       if (Value.SymbolName)
1693         addRelocationForSymbol(RE, Value.SymbolName);
1694       else
1695         addRelocationForSection(RE, Value.SectionID);
1696     } else if (RelType == ELF::R_X86_64_PC32) {
1697       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1698       processSimpleRelocation(SectionID, Offset, RelType, Value);
1699     } else if (RelType == ELF::R_X86_64_PC64) {
1700       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1701       processSimpleRelocation(SectionID, Offset, RelType, Value);
1702     } else {
1703       processSimpleRelocation(SectionID, Offset, RelType, Value);
1704     }
1705   } else {
1706     if (Arch == Triple::x86) {
1707       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1708     }
1709     processSimpleRelocation(SectionID, Offset, RelType, Value);
1710   }
1711   return ++RelI;
1712 }
1713 
1714 size_t RuntimeDyldELF::getGOTEntrySize() {
1715   // We don't use the GOT in all of these cases, but it's essentially free
1716   // to put them all here.
1717   size_t Result = 0;
1718   switch (Arch) {
1719   case Triple::x86_64:
1720   case Triple::aarch64:
1721   case Triple::aarch64_be:
1722   case Triple::ppc64:
1723   case Triple::ppc64le:
1724   case Triple::systemz:
1725     Result = sizeof(uint64_t);
1726     break;
1727   case Triple::x86:
1728   case Triple::arm:
1729   case Triple::thumb:
1730     Result = sizeof(uint32_t);
1731     break;
1732   case Triple::mips:
1733   case Triple::mipsel:
1734   case Triple::mips64:
1735   case Triple::mips64el:
1736     if (IsMipsO32ABI || IsMipsN32ABI)
1737       Result = sizeof(uint32_t);
1738     else if (IsMipsN64ABI)
1739       Result = sizeof(uint64_t);
1740     else
1741       llvm_unreachable("Mips ABI not handled");
1742     break;
1743   default:
1744     llvm_unreachable("Unsupported CPU type!");
1745   }
1746   return Result;
1747 }
1748 
1749 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) {
1750   if (GOTSectionID == 0) {
1751     GOTSectionID = Sections.size();
1752     // Reserve a section id. We'll allocate the section later
1753     // once we know the total size
1754     Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
1755   }
1756   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1757   CurrentGOTIndex += no;
1758   return StartOffset;
1759 }
1760 
1761 uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value,
1762                                              unsigned GOTRelType) {
1763   auto E = GOTOffsetMap.insert({Value, 0});
1764   if (E.second) {
1765     uint64_t GOTOffset = allocateGOTEntries(1);
1766 
1767     // Create relocation for newly created GOT entry
1768     RelocationEntry RE =
1769         computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType);
1770     if (Value.SymbolName)
1771       addRelocationForSymbol(RE, Value.SymbolName);
1772     else
1773       addRelocationForSection(RE, Value.SectionID);
1774 
1775     E.first->second = GOTOffset;
1776   }
1777 
1778   return E.first->second;
1779 }
1780 
1781 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID,
1782                                                 uint64_t Offset,
1783                                                 uint64_t GOTOffset,
1784                                                 uint32_t Type) {
1785   // Fill in the relative address of the GOT Entry into the stub
1786   RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset);
1787   addRelocationForSection(GOTRE, GOTSectionID);
1788 }
1789 
1790 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset,
1791                                                    uint64_t SymbolOffset,
1792                                                    uint32_t Type) {
1793   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1794 }
1795 
1796 Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1797                                   ObjSectionToIDMap &SectionMap) {
1798   if (IsMipsO32ABI)
1799     if (!PendingRelocs.empty())
1800       return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
1801 
1802   // If necessary, allocate the global offset table
1803   if (GOTSectionID != 0) {
1804     // Allocate memory for the section
1805     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1806     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1807                                                 GOTSectionID, ".got", false);
1808     if (!Addr)
1809       return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!");
1810 
1811     Sections[GOTSectionID] =
1812         SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
1813 
1814     if (Checker)
1815       Checker->registerSection(Obj.getFileName(), GOTSectionID);
1816 
1817     // For now, initialize all GOT entries to zero.  We'll fill them in as
1818     // needed when GOT-based relocations are applied.
1819     memset(Addr, 0, TotalSize);
1820     if (IsMipsN32ABI || IsMipsN64ABI) {
1821       // To correctly resolve Mips GOT relocations, we need a mapping from
1822       // object's sections to GOTs.
1823       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1824            SI != SE; ++SI) {
1825         if (SI->relocation_begin() != SI->relocation_end()) {
1826           section_iterator RelocatedSection = SI->getRelocatedSection();
1827           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1828           assert (i != SectionMap.end());
1829           SectionToGOTMap[i->second] = GOTSectionID;
1830         }
1831       }
1832       GOTSymbolOffsets.clear();
1833     }
1834   }
1835 
1836   // Look for and record the EH frame section.
1837   ObjSectionToIDMap::iterator i, e;
1838   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1839     const SectionRef &Section = i->first;
1840     StringRef Name;
1841     Section.getName(Name);
1842     if (Name == ".eh_frame") {
1843       UnregisteredEHFrameSections.push_back(i->second);
1844       break;
1845     }
1846   }
1847 
1848   GOTSectionID = 0;
1849   CurrentGOTIndex = 0;
1850 
1851   return Error::success();
1852 }
1853 
1854 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1855   return Obj.isELF();
1856 }
1857 
1858 bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const {
1859   unsigned RelTy = R.getType();
1860   if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
1861     return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE ||
1862            RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC;
1863 
1864   if (Arch == Triple::x86_64)
1865     return RelTy == ELF::R_X86_64_GOTPCREL ||
1866            RelTy == ELF::R_X86_64_GOTPCRELX ||
1867            RelTy == ELF::R_X86_64_REX_GOTPCRELX;
1868   return false;
1869 }
1870 
1871 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
1872   if (Arch != Triple::x86_64)
1873     return true;  // Conservative answer
1874 
1875   switch (R.getType()) {
1876   default:
1877     return true;  // Conservative answer
1878 
1879 
1880   case ELF::R_X86_64_GOTPCREL:
1881   case ELF::R_X86_64_GOTPCRELX:
1882   case ELF::R_X86_64_REX_GOTPCRELX:
1883   case ELF::R_X86_64_PC32:
1884   case ELF::R_X86_64_PC64:
1885   case ELF::R_X86_64_64:
1886     // We know that these reloation types won't need a stub function.  This list
1887     // can be extended as needed.
1888     return false;
1889   }
1890 }
1891 
1892 } // namespace llvm
1893