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(RealOffset <= INT32_MAX && RealOffset >= INT32_MIN);
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(-(1LL << 27) <= static_cast<int64_t>(BranchImm) &&
326            static_cast<int64_t>(BranchImm) < (1LL << 27));
327 
328     // AArch64 code is emitted with .rela relocations. The data already in any
329     // bits affected by the relocation on entry is garbage.
330     *TargetPtr &= 0xfc000000U;
331     // Immediate goes in bits 25:0 of B and BL.
332     *TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
333     break;
334   }
335   case ELF::R_AARCH64_MOVW_UABS_G3: {
336     uint64_t Result = Value + Addend;
337 
338     // AArch64 code is emitted with .rela relocations. The data already in any
339     // bits affected by the relocation on entry is garbage.
340     *TargetPtr &= 0xffe0001fU;
341     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
342     *TargetPtr |= Result >> (48 - 5);
343     // Shift must be "lsl #48", in bits 22:21
344     assert((*TargetPtr >> 21 & 0x3) == 3 && "invalid shift for relocation");
345     break;
346   }
347   case ELF::R_AARCH64_MOVW_UABS_G2_NC: {
348     uint64_t Result = Value + Addend;
349 
350     // AArch64 code is emitted with .rela relocations. The data already in any
351     // bits affected by the relocation on entry is garbage.
352     *TargetPtr &= 0xffe0001fU;
353     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
354     *TargetPtr |= ((Result & 0xffff00000000ULL) >> (32 - 5));
355     // Shift must be "lsl #32", in bits 22:21
356     assert((*TargetPtr >> 21 & 0x3) == 2 && "invalid shift for relocation");
357     break;
358   }
359   case ELF::R_AARCH64_MOVW_UABS_G1_NC: {
360     uint64_t Result = Value + Addend;
361 
362     // AArch64 code is emitted with .rela relocations. The data already in any
363     // bits affected by the relocation on entry is garbage.
364     *TargetPtr &= 0xffe0001fU;
365     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
366     *TargetPtr |= ((Result & 0xffff0000U) >> (16 - 5));
367     // Shift must be "lsl #16", in bits 22:2
368     assert((*TargetPtr >> 21 & 0x3) == 1 && "invalid shift for relocation");
369     break;
370   }
371   case ELF::R_AARCH64_MOVW_UABS_G0_NC: {
372     uint64_t Result = Value + Addend;
373 
374     // AArch64 code is emitted with .rela relocations. The data already in any
375     // bits affected by the relocation on entry is garbage.
376     *TargetPtr &= 0xffe0001fU;
377     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
378     *TargetPtr |= ((Result & 0xffffU) << 5);
379     // Shift must be "lsl #0", in bits 22:21.
380     assert((*TargetPtr >> 21 & 0x3) == 0 && "invalid shift for relocation");
381     break;
382   }
383   case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
384     // Operation: Page(S+A) - Page(P)
385     uint64_t Result =
386         ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
387 
388     // Check that -2^32 <= X < 2^32
389     assert(static_cast<int64_t>(Result) >= (-1LL << 32) &&
390            static_cast<int64_t>(Result) < (1LL << 32) &&
391            "overflow check failed for relocation");
392 
393     // AArch64 code is emitted with .rela relocations. The data already in any
394     // bits affected by the relocation on entry is garbage.
395     *TargetPtr &= 0x9f00001fU;
396     // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
397     // from bits 32:12 of X.
398     *TargetPtr |= ((Result & 0x3000U) << (29 - 12));
399     *TargetPtr |= ((Result & 0x1ffffc000ULL) >> (14 - 5));
400     break;
401   }
402   case ELF::R_AARCH64_LDST32_ABS_LO12_NC: {
403     // Operation: S + A
404     uint64_t Result = Value + Addend;
405 
406     // AArch64 code is emitted with .rela relocations. The data already in any
407     // bits affected by the relocation on entry is garbage.
408     *TargetPtr &= 0xffc003ffU;
409     // Immediate goes in bits 21:10 of LD/ST instruction, taken
410     // from bits 11:2 of X
411     *TargetPtr |= ((Result & 0xffc) << (10 - 2));
412     break;
413   }
414   case ELF::R_AARCH64_LDST64_ABS_LO12_NC: {
415     // Operation: S + A
416     uint64_t Result = Value + Addend;
417 
418     // AArch64 code is emitted with .rela relocations. The data already in any
419     // bits affected by the relocation on entry is garbage.
420     *TargetPtr &= 0xffc003ffU;
421     // Immediate goes in bits 21:10 of LD/ST instruction, taken
422     // from bits 11:3 of X
423     *TargetPtr |= ((Result & 0xff8) << (10 - 3));
424     break;
425   }
426   }
427 }
428 
429 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
430                                           uint64_t Offset, uint32_t Value,
431                                           uint32_t Type, int32_t Addend) {
432   // TODO: Add Thumb relocations.
433   uint32_t *TargetPtr = (uint32_t *)(Section.Address + Offset);
434   uint32_t FinalAddress = ((Section.LoadAddress + Offset) & 0xFFFFFFFF);
435   Value += Addend;
436 
437   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
438                << Section.Address + Offset
439                << " FinalAddress: " << format("%p", FinalAddress) << " Value: "
440                << format("%x", Value) << " Type: " << format("%x", Type)
441                << " Addend: " << format("%x", Addend) << "\n");
442 
443   switch (Type) {
444   default:
445     llvm_unreachable("Not implemented relocation type!");
446 
447   case ELF::R_ARM_NONE:
448     break;
449   case ELF::R_ARM_PREL31:
450   case ELF::R_ARM_TARGET1:
451   case ELF::R_ARM_ABS32:
452     *TargetPtr = Value;
453     break;
454     // Write first 16 bit of 32 bit value to the mov instruction.
455     // Last 4 bit should be shifted.
456   case ELF::R_ARM_MOVW_ABS_NC:
457   case ELF::R_ARM_MOVT_ABS:
458     if (Type == ELF::R_ARM_MOVW_ABS_NC)
459       Value = Value & 0xFFFF;
460     else if (Type == ELF::R_ARM_MOVT_ABS)
461       Value = (Value >> 16) & 0xFFFF;
462     *TargetPtr &= ~0x000F0FFF;
463     *TargetPtr |= Value & 0xFFF;
464     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
465     break;
466     // Write 24 bit relative value to the branch instruction.
467   case ELF::R_ARM_PC24: // Fall through.
468   case ELF::R_ARM_CALL: // Fall through.
469   case ELF::R_ARM_JUMP24:
470     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
471     RelValue = (RelValue & 0x03FFFFFC) >> 2;
472     assert((*TargetPtr & 0xFFFFFF) == 0xFFFFFE);
473     *TargetPtr &= 0xFF000000;
474     *TargetPtr |= RelValue;
475     break;
476   }
477 }
478 
479 void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
480                                            uint64_t Offset, uint32_t Value,
481                                            uint32_t Type, int32_t Addend) {
482   uint32_t *TargetPtr = (uint32_t *)(Section.Address + Offset);
483   Value += Addend;
484 
485   DEBUG(dbgs() << "resolveMipselocation, LocalAddress: "
486                << Section.Address + Offset << " FinalAddress: "
487                << format("%p", Section.LoadAddress + Offset) << " Value: "
488                << format("%x", Value) << " Type: " << format("%x", Type)
489                << " Addend: " << format("%x", Addend) << "\n");
490 
491   switch (Type) {
492   default:
493     llvm_unreachable("Not implemented relocation type!");
494     break;
495   case ELF::R_MIPS_32:
496     *TargetPtr = Value;
497     break;
498   case ELF::R_MIPS_26:
499     *TargetPtr = ((*TargetPtr) & 0xfc000000) | ((Value & 0x0fffffff) >> 2);
500     break;
501   case ELF::R_MIPS_HI16:
502     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
503     *TargetPtr =
504       ((*TargetPtr) & 0xffff0000) | (((Value + 0x8000) >> 16) & 0xffff);
505     break;
506   case ELF::R_MIPS_LO16:
507     *TargetPtr = ((*TargetPtr) & 0xffff0000) | (Value & 0xffff);
508     break;
509   }
510 }
511 
512 // Return the .TOC. section and offset.
513 void RuntimeDyldELF::findPPC64TOCSection(const ObjectFile &Obj,
514                                          ObjSectionToIDMap &LocalSections,
515                                          RelocationValueRef &Rel) {
516   // Set a default SectionID in case we do not find a TOC section below.
517   // This may happen for references to TOC base base (sym@toc, .odp
518   // relocation) without a .toc directive.  In this case just use the
519   // first section (which is usually the .odp) since the code won't
520   // reference the .toc base directly.
521   Rel.SymbolName = NULL;
522   Rel.SectionID = 0;
523 
524   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
525   // order. The TOC starts where the first of these sections starts.
526   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
527        si != se; ++si) {
528 
529     StringRef SectionName;
530     check(si->getName(SectionName));
531 
532     if (SectionName == ".got"
533         || SectionName == ".toc"
534         || SectionName == ".tocbss"
535         || SectionName == ".plt") {
536       Rel.SectionID = findOrEmitSection(Obj, *si, false, LocalSections);
537       break;
538     }
539   }
540 
541   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
542   // thus permitting a full 64 Kbytes segment.
543   Rel.Addend = 0x8000;
544 }
545 
546 // Returns the sections and offset associated with the ODP entry referenced
547 // by Symbol.
548 void RuntimeDyldELF::findOPDEntrySection(const ObjectFile &Obj,
549                                          ObjSectionToIDMap &LocalSections,
550                                          RelocationValueRef &Rel) {
551   // Get the ELF symbol value (st_value) to compare with Relocation offset in
552   // .opd entries
553   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
554        si != se; ++si) {
555     section_iterator RelSecI = si->getRelocatedSection();
556     if (RelSecI == Obj.section_end())
557       continue;
558 
559     StringRef RelSectionName;
560     check(RelSecI->getName(RelSectionName));
561     if (RelSectionName != ".opd")
562       continue;
563 
564     for (relocation_iterator i = si->relocation_begin(),
565                              e = si->relocation_end();
566          i != e;) {
567       // The R_PPC64_ADDR64 relocation indicates the first field
568       // of a .opd entry
569       uint64_t TypeFunc;
570       check(i->getType(TypeFunc));
571       if (TypeFunc != ELF::R_PPC64_ADDR64) {
572         ++i;
573         continue;
574       }
575 
576       uint64_t TargetSymbolOffset;
577       symbol_iterator TargetSymbol = i->getSymbol();
578       check(i->getOffset(TargetSymbolOffset));
579       int64_t Addend;
580       check(getELFRelocationAddend(*i, Addend));
581 
582       ++i;
583       if (i == e)
584         break;
585 
586       // Just check if following relocation is a R_PPC64_TOC
587       uint64_t TypeTOC;
588       check(i->getType(TypeTOC));
589       if (TypeTOC != ELF::R_PPC64_TOC)
590         continue;
591 
592       // Finally compares the Symbol value and the target symbol offset
593       // to check if this .opd entry refers to the symbol the relocation
594       // points to.
595       if (Rel.Addend != (int64_t)TargetSymbolOffset)
596         continue;
597 
598       section_iterator tsi(Obj.section_end());
599       check(TargetSymbol->getSection(tsi));
600       bool IsCode = tsi->isText();
601       Rel.SectionID = findOrEmitSection(Obj, (*tsi), IsCode, LocalSections);
602       Rel.Addend = (intptr_t)Addend;
603       return;
604     }
605   }
606   llvm_unreachable("Attempting to get address of ODP entry!");
607 }
608 
609 // Relocation masks following the #lo(value), #hi(value), #ha(value),
610 // #higher(value), #highera(value), #highest(value), and #highesta(value)
611 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
612 // document.
613 
614 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
615 
616 static inline uint16_t applyPPChi(uint64_t value) {
617   return (value >> 16) & 0xffff;
618 }
619 
620 static inline uint16_t applyPPCha (uint64_t value) {
621   return ((value + 0x8000) >> 16) & 0xffff;
622 }
623 
624 static inline uint16_t applyPPChigher(uint64_t value) {
625   return (value >> 32) & 0xffff;
626 }
627 
628 static inline uint16_t applyPPChighera (uint64_t value) {
629   return ((value + 0x8000) >> 32) & 0xffff;
630 }
631 
632 static inline uint16_t applyPPChighest(uint64_t value) {
633   return (value >> 48) & 0xffff;
634 }
635 
636 static inline uint16_t applyPPChighesta (uint64_t value) {
637   return ((value + 0x8000) >> 48) & 0xffff;
638 }
639 
640 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
641                                             uint64_t Offset, uint64_t Value,
642                                             uint32_t Type, int64_t Addend) {
643   uint8_t *LocalAddress = Section.Address + Offset;
644   switch (Type) {
645   default:
646     llvm_unreachable("Relocation type not implemented yet!");
647     break;
648   case ELF::R_PPC64_ADDR16:
649     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
650     break;
651   case ELF::R_PPC64_ADDR16_DS:
652     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
653     break;
654   case ELF::R_PPC64_ADDR16_LO:
655     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
656     break;
657   case ELF::R_PPC64_ADDR16_LO_DS:
658     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
659     break;
660   case ELF::R_PPC64_ADDR16_HI:
661     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
662     break;
663   case ELF::R_PPC64_ADDR16_HA:
664     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
665     break;
666   case ELF::R_PPC64_ADDR16_HIGHER:
667     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
668     break;
669   case ELF::R_PPC64_ADDR16_HIGHERA:
670     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
671     break;
672   case ELF::R_PPC64_ADDR16_HIGHEST:
673     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
674     break;
675   case ELF::R_PPC64_ADDR16_HIGHESTA:
676     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
677     break;
678   case ELF::R_PPC64_ADDR14: {
679     assert(((Value + Addend) & 3) == 0);
680     // Preserve the AA/LK bits in the branch instruction
681     uint8_t aalk = *(LocalAddress + 3);
682     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
683   } break;
684   case ELF::R_PPC64_REL16_LO: {
685     uint64_t FinalAddress = (Section.LoadAddress + Offset);
686     uint64_t Delta = Value - FinalAddress + Addend;
687     writeInt16BE(LocalAddress, applyPPClo(Delta));
688   } break;
689   case ELF::R_PPC64_REL16_HI: {
690     uint64_t FinalAddress = (Section.LoadAddress + Offset);
691     uint64_t Delta = Value - FinalAddress + Addend;
692     writeInt16BE(LocalAddress, applyPPChi(Delta));
693   } break;
694   case ELF::R_PPC64_REL16_HA: {
695     uint64_t FinalAddress = (Section.LoadAddress + Offset);
696     uint64_t Delta = Value - FinalAddress + Addend;
697     writeInt16BE(LocalAddress, applyPPCha(Delta));
698   } break;
699   case ELF::R_PPC64_ADDR32: {
700     int32_t Result = static_cast<int32_t>(Value + Addend);
701     if (SignExtend32<32>(Result) != Result)
702       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
703     writeInt32BE(LocalAddress, Result);
704   } break;
705   case ELF::R_PPC64_REL24: {
706     uint64_t FinalAddress = (Section.LoadAddress + Offset);
707     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
708     if (SignExtend32<24>(delta) != delta)
709       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
710     // Generates a 'bl <address>' instruction
711     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
712   } break;
713   case ELF::R_PPC64_REL32: {
714     uint64_t FinalAddress = (Section.LoadAddress + Offset);
715     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
716     if (SignExtend32<32>(delta) != delta)
717       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
718     writeInt32BE(LocalAddress, delta);
719   } break;
720   case ELF::R_PPC64_REL64: {
721     uint64_t FinalAddress = (Section.LoadAddress + Offset);
722     uint64_t Delta = Value - FinalAddress + Addend;
723     writeInt64BE(LocalAddress, Delta);
724   } break;
725   case ELF::R_PPC64_ADDR64:
726     writeInt64BE(LocalAddress, Value + Addend);
727     break;
728   }
729 }
730 
731 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
732                                               uint64_t Offset, uint64_t Value,
733                                               uint32_t Type, int64_t Addend) {
734   uint8_t *LocalAddress = Section.Address + Offset;
735   switch (Type) {
736   default:
737     llvm_unreachable("Relocation type not implemented yet!");
738     break;
739   case ELF::R_390_PC16DBL:
740   case ELF::R_390_PLT16DBL: {
741     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
742     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
743     writeInt16BE(LocalAddress, Delta / 2);
744     break;
745   }
746   case ELF::R_390_PC32DBL:
747   case ELF::R_390_PLT32DBL: {
748     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
749     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
750     writeInt32BE(LocalAddress, Delta / 2);
751     break;
752   }
753   case ELF::R_390_PC32: {
754     int64_t Delta = (Value + Addend) - (Section.LoadAddress + Offset);
755     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
756     writeInt32BE(LocalAddress, Delta);
757     break;
758   }
759   case ELF::R_390_64:
760     writeInt64BE(LocalAddress, Value + Addend);
761     break;
762   }
763 }
764 
765 // The target location for the relocation is described by RE.SectionID and
766 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
767 // SectionEntry has three members describing its location.
768 // SectionEntry::Address is the address at which the section has been loaded
769 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
770 // address that the section will have in the target process.
771 // SectionEntry::ObjAddress is the address of the bits for this section in the
772 // original emitted object image (also in the current address space).
773 //
774 // Relocations will be applied as if the section were loaded at
775 // SectionEntry::LoadAddress, but they will be applied at an address based
776 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
777 // Target memory contents if they are required for value calculations.
778 //
779 // The Value parameter here is the load address of the symbol for the
780 // relocation to be applied.  For relocations which refer to symbols in the
781 // current object Value will be the LoadAddress of the section in which
782 // the symbol resides (RE.Addend provides additional information about the
783 // symbol location).  For external symbols, Value will be the address of the
784 // symbol in the target address space.
785 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
786                                        uint64_t Value) {
787   const SectionEntry &Section = Sections[RE.SectionID];
788   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
789                            RE.SymOffset);
790 }
791 
792 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
793                                        uint64_t Offset, uint64_t Value,
794                                        uint32_t Type, int64_t Addend,
795                                        uint64_t SymOffset) {
796   switch (Arch) {
797   case Triple::x86_64:
798     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
799     break;
800   case Triple::x86:
801     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
802                          (uint32_t)(Addend & 0xffffffffL));
803     break;
804   case Triple::aarch64:
805   case Triple::aarch64_be:
806     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
807     break;
808   case Triple::arm: // Fall through.
809   case Triple::armeb:
810   case Triple::thumb:
811   case Triple::thumbeb:
812     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
813                          (uint32_t)(Addend & 0xffffffffL));
814     break;
815   case Triple::mips: // Fall through.
816   case Triple::mipsel:
817     resolveMIPSRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL),
818                           Type, (uint32_t)(Addend & 0xffffffffL));
819     break;
820   case Triple::ppc64: // Fall through.
821   case Triple::ppc64le:
822     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
823     break;
824   case Triple::systemz:
825     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
826     break;
827   default:
828     llvm_unreachable("Unsupported CPU type!");
829   }
830 }
831 
832 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
833   return (void*)(Sections[SectionID].ObjAddress + Offset);
834 }
835 
836 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
837   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
838   if (Value.SymbolName)
839     addRelocationForSymbol(RE, Value.SymbolName);
840   else
841     addRelocationForSection(RE, Value.SectionID);
842 }
843 
844 relocation_iterator RuntimeDyldELF::processRelocationRef(
845     unsigned SectionID, relocation_iterator RelI,
846     const ObjectFile &Obj,
847     ObjSectionToIDMap &ObjSectionToID,
848     StubMap &Stubs) {
849   uint64_t RelType;
850   Check(RelI->getType(RelType));
851   int64_t Addend;
852   Check(getELFRelocationAddend(*RelI, Addend));
853   symbol_iterator Symbol = RelI->getSymbol();
854 
855   // Obtain the symbol name which is referenced in the relocation
856   StringRef TargetName;
857   if (Symbol != Obj.symbol_end())
858     Symbol->getName(TargetName);
859   DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
860                << " TargetName: " << TargetName << "\n");
861   RelocationValueRef Value;
862   // First search for the symbol in the local symbol table
863   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
864 
865   // Search for the symbol in the global symbol table
866   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
867   if (Symbol != Obj.symbol_end()) {
868     gsi = GlobalSymbolTable.find(TargetName.data());
869     Symbol->getType(SymType);
870   }
871   if (gsi != GlobalSymbolTable.end()) {
872     const auto &SymInfo = gsi->second;
873     Value.SectionID = SymInfo.getSectionID();
874     Value.Offset = SymInfo.getOffset();
875     Value.Addend = SymInfo.getOffset() + Addend;
876   } else {
877     switch (SymType) {
878     case SymbolRef::ST_Debug: {
879       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
880       // and can be changed by another developers. Maybe best way is add
881       // a new symbol type ST_Section to SymbolRef and use it.
882       section_iterator si(Obj.section_end());
883       Symbol->getSection(si);
884       if (si == Obj.section_end())
885         llvm_unreachable("Symbol section not found, bad object file format!");
886       DEBUG(dbgs() << "\t\tThis is section symbol\n");
887       bool isCode = si->isText();
888       Value.SectionID = findOrEmitSection(Obj, (*si), isCode, ObjSectionToID);
889       Value.Addend = Addend;
890       break;
891     }
892     case SymbolRef::ST_Data:
893     case SymbolRef::ST_Unknown: {
894       Value.SymbolName = TargetName.data();
895       Value.Addend = Addend;
896 
897       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
898       // will manifest here as a NULL symbol name.
899       // We can set this as a valid (but empty) symbol name, and rely
900       // on addRelocationForSymbol to handle this.
901       if (!Value.SymbolName)
902         Value.SymbolName = "";
903       break;
904     }
905     default:
906       llvm_unreachable("Unresolved symbol type!");
907       break;
908     }
909   }
910 
911   uint64_t Offset;
912   Check(RelI->getOffset(Offset));
913 
914   DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
915                << "\n");
916   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be) &&
917       (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26)) {
918     // This is an AArch64 branch relocation, need to use a stub function.
919     DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
920     SectionEntry &Section = Sections[SectionID];
921 
922     // Look for an existing stub.
923     StubMap::const_iterator i = Stubs.find(Value);
924     if (i != Stubs.end()) {
925       resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
926                         RelType, 0);
927       DEBUG(dbgs() << " Stub function found\n");
928     } else {
929       // Create a new stub function.
930       DEBUG(dbgs() << " Create a new stub function\n");
931       Stubs[Value] = Section.StubOffset;
932       uint8_t *StubTargetAddr =
933           createStubFunction(Section.Address + Section.StubOffset);
934 
935       RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.Address,
936                                 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
937       RelocationEntry REmovk_g2(SectionID, StubTargetAddr - Section.Address + 4,
938                                 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
939       RelocationEntry REmovk_g1(SectionID, StubTargetAddr - Section.Address + 8,
940                                 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
941       RelocationEntry REmovk_g0(SectionID,
942                                 StubTargetAddr - Section.Address + 12,
943                                 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
944 
945       if (Value.SymbolName) {
946         addRelocationForSymbol(REmovz_g3, Value.SymbolName);
947         addRelocationForSymbol(REmovk_g2, Value.SymbolName);
948         addRelocationForSymbol(REmovk_g1, Value.SymbolName);
949         addRelocationForSymbol(REmovk_g0, Value.SymbolName);
950       } else {
951         addRelocationForSection(REmovz_g3, Value.SectionID);
952         addRelocationForSection(REmovk_g2, Value.SectionID);
953         addRelocationForSection(REmovk_g1, Value.SectionID);
954         addRelocationForSection(REmovk_g0, Value.SectionID);
955       }
956       resolveRelocation(Section, Offset,
957                         (uint64_t)Section.Address + Section.StubOffset, RelType,
958                         0);
959       Section.StubOffset += getMaxStubSize();
960     }
961   } else if (Arch == Triple::arm) {
962     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
963       RelType == ELF::R_ARM_JUMP24) {
964       // This is an ARM branch relocation, need to use a stub function.
965       DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
966       SectionEntry &Section = Sections[SectionID];
967 
968       // Look for an existing stub.
969       StubMap::const_iterator i = Stubs.find(Value);
970       if (i != Stubs.end()) {
971         resolveRelocation(Section, Offset, (uint64_t)Section.Address + i->second,
972           RelType, 0);
973         DEBUG(dbgs() << " Stub function found\n");
974       } else {
975         // Create a new stub function.
976         DEBUG(dbgs() << " Create a new stub function\n");
977         Stubs[Value] = Section.StubOffset;
978         uint8_t *StubTargetAddr =
979           createStubFunction(Section.Address + Section.StubOffset);
980         RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
981           ELF::R_ARM_ABS32, Value.Addend);
982         if (Value.SymbolName)
983           addRelocationForSymbol(RE, Value.SymbolName);
984         else
985           addRelocationForSection(RE, Value.SectionID);
986 
987         resolveRelocation(Section, Offset,
988           (uint64_t)Section.Address + Section.StubOffset, RelType,
989           0);
990         Section.StubOffset += getMaxStubSize();
991       }
992     } else {
993       uint32_t *Placeholder =
994         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
995       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
996           RelType == ELF::R_ARM_ABS32) {
997         Value.Addend += *Placeholder;
998       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
999         // See ELF for ARM documentation
1000         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1001       }
1002       processSimpleRelocation(SectionID, Offset, RelType, Value);
1003     }
1004   } else if ((Arch == Triple::mipsel || Arch == Triple::mips)) {
1005     uint32_t *Placeholder = reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1006     if (RelType == ELF::R_MIPS_26) {
1007       // This is an Mips branch relocation, need to use a stub function.
1008       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1009       SectionEntry &Section = Sections[SectionID];
1010 
1011       // Extract the addend from the instruction.
1012       // We shift up by two since the Value will be down shifted again
1013       // when applying the relocation.
1014       uint32_t Addend = ((*Placeholder) & 0x03ffffff) << 2;
1015 
1016       Value.Addend += Addend;
1017 
1018       //  Look up for existing stub.
1019       StubMap::const_iterator i = Stubs.find(Value);
1020       if (i != Stubs.end()) {
1021         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1022         addRelocationForSection(RE, SectionID);
1023         DEBUG(dbgs() << " Stub function found\n");
1024       } else {
1025         // Create a new stub function.
1026         DEBUG(dbgs() << " Create a new stub function\n");
1027         Stubs[Value] = Section.StubOffset;
1028         uint8_t *StubTargetAddr =
1029           createStubFunction(Section.Address + Section.StubOffset);
1030 
1031         // Creating Hi and Lo relocations for the filled stub instructions.
1032         RelocationEntry REHi(SectionID, StubTargetAddr - Section.Address,
1033           ELF::R_MIPS_HI16, Value.Addend);
1034         RelocationEntry RELo(SectionID, StubTargetAddr - Section.Address + 4,
1035           ELF::R_MIPS_LO16, Value.Addend);
1036 
1037         if (Value.SymbolName) {
1038           addRelocationForSymbol(REHi, Value.SymbolName);
1039           addRelocationForSymbol(RELo, Value.SymbolName);
1040         }
1041         else {
1042           addRelocationForSection(REHi, Value.SectionID);
1043           addRelocationForSection(RELo, Value.SectionID);
1044         }
1045 
1046         RelocationEntry RE(SectionID, Offset, RelType, Section.StubOffset);
1047         addRelocationForSection(RE, SectionID);
1048         Section.StubOffset += getMaxStubSize();
1049       }
1050     } else {
1051       if (RelType == ELF::R_MIPS_HI16)
1052         Value.Addend += ((*Placeholder) & 0x0000ffff) << 16;
1053       else if (RelType == ELF::R_MIPS_LO16)
1054         Value.Addend += ((*Placeholder) & 0x0000ffff);
1055       else if (RelType == ELF::R_MIPS_32)
1056         Value.Addend += *Placeholder;
1057       processSimpleRelocation(SectionID, Offset, RelType, Value);
1058     }
1059   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1060     if (RelType == ELF::R_PPC64_REL24) {
1061       // Determine ABI variant in use for this object.
1062       unsigned AbiVariant;
1063       Obj.getPlatformFlags(AbiVariant);
1064       AbiVariant &= ELF::EF_PPC64_ABI;
1065       // A PPC branch relocation will need a stub function if the target is
1066       // an external symbol (Symbol::ST_Unknown) or if the target address
1067       // is not within the signed 24-bits branch address.
1068       SectionEntry &Section = Sections[SectionID];
1069       uint8_t *Target = Section.Address + Offset;
1070       bool RangeOverflow = false;
1071       if (SymType != SymbolRef::ST_Unknown) {
1072         if (AbiVariant != 2) {
1073           // In the ELFv1 ABI, a function call may point to the .opd entry,
1074           // so the final symbol value is calculated based on the relocation
1075           // values in the .opd section.
1076           findOPDEntrySection(Obj, ObjSectionToID, Value);
1077         } else {
1078           // In the ELFv2 ABI, a function symbol may provide a local entry
1079           // point, which must be used for direct calls.
1080           uint8_t SymOther;
1081           Symbol->getOther(SymOther);
1082           Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1083         }
1084         uint8_t *RelocTarget = Sections[Value.SectionID].Address + Value.Addend;
1085         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
1086         // If it is within 24-bits branch range, just set the branch target
1087         if (SignExtend32<24>(delta) == delta) {
1088           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1089           if (Value.SymbolName)
1090             addRelocationForSymbol(RE, Value.SymbolName);
1091           else
1092             addRelocationForSection(RE, Value.SectionID);
1093         } else {
1094           RangeOverflow = true;
1095         }
1096       }
1097       if (SymType == SymbolRef::ST_Unknown || RangeOverflow) {
1098         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
1099         // larger than 24-bits.
1100         StubMap::const_iterator i = Stubs.find(Value);
1101         if (i != Stubs.end()) {
1102           // Symbol function stub already created, just relocate to it
1103           resolveRelocation(Section, Offset,
1104                             (uint64_t)Section.Address + i->second, RelType, 0);
1105           DEBUG(dbgs() << " Stub function found\n");
1106         } else {
1107           // Create a new stub function.
1108           DEBUG(dbgs() << " Create a new stub function\n");
1109           Stubs[Value] = Section.StubOffset;
1110           uint8_t *StubTargetAddr =
1111               createStubFunction(Section.Address + Section.StubOffset,
1112                                  AbiVariant);
1113           RelocationEntry RE(SectionID, StubTargetAddr - Section.Address,
1114                              ELF::R_PPC64_ADDR64, Value.Addend);
1115 
1116           // Generates the 64-bits address loads as exemplified in section
1117           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1118           // apply to the low part of the instructions, so we have to update
1119           // the offset according to the target endianness.
1120           uint64_t StubRelocOffset = StubTargetAddr - Section.Address;
1121           if (!IsTargetLittleEndian)
1122             StubRelocOffset += 2;
1123 
1124           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1125                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1126           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1127                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1128           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1129                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1130           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1131                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1132 
1133           if (Value.SymbolName) {
1134             addRelocationForSymbol(REhst, Value.SymbolName);
1135             addRelocationForSymbol(REhr, Value.SymbolName);
1136             addRelocationForSymbol(REh, Value.SymbolName);
1137             addRelocationForSymbol(REl, Value.SymbolName);
1138           } else {
1139             addRelocationForSection(REhst, Value.SectionID);
1140             addRelocationForSection(REhr, Value.SectionID);
1141             addRelocationForSection(REh, Value.SectionID);
1142             addRelocationForSection(REl, Value.SectionID);
1143           }
1144 
1145           resolveRelocation(Section, Offset,
1146                             (uint64_t)Section.Address + Section.StubOffset,
1147                             RelType, 0);
1148           Section.StubOffset += getMaxStubSize();
1149         }
1150         if (SymType == SymbolRef::ST_Unknown) {
1151           // Restore the TOC for external calls
1152           if (AbiVariant == 2)
1153             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
1154           else
1155             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1156         }
1157       }
1158     } else if (RelType == ELF::R_PPC64_TOC16 ||
1159                RelType == ELF::R_PPC64_TOC16_DS ||
1160                RelType == ELF::R_PPC64_TOC16_LO ||
1161                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1162                RelType == ELF::R_PPC64_TOC16_HI ||
1163                RelType == ELF::R_PPC64_TOC16_HA) {
1164       // These relocations are supposed to subtract the TOC address from
1165       // the final value.  This does not fit cleanly into the RuntimeDyld
1166       // scheme, since there may be *two* sections involved in determining
1167       // the relocation value (the section of the symbol refered to by the
1168       // relocation, and the TOC section associated with the current module).
1169       //
1170       // Fortunately, these relocations are currently only ever generated
1171       // refering to symbols that themselves reside in the TOC, which means
1172       // that the two sections are actually the same.  Thus they cancel out
1173       // and we can immediately resolve the relocation right now.
1174       switch (RelType) {
1175       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1176       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1177       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1178       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1179       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1180       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1181       default: llvm_unreachable("Wrong relocation type.");
1182       }
1183 
1184       RelocationValueRef TOCValue;
1185       findPPC64TOCSection(Obj, ObjSectionToID, TOCValue);
1186       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1187         llvm_unreachable("Unsupported TOC relocation.");
1188       Value.Addend -= TOCValue.Addend;
1189       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1190     } else {
1191       // There are two ways to refer to the TOC address directly: either
1192       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1193       // ignored), or via any relocation that refers to the magic ".TOC."
1194       // symbols (in which case the addend is respected).
1195       if (RelType == ELF::R_PPC64_TOC) {
1196         RelType = ELF::R_PPC64_ADDR64;
1197         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1198       } else if (TargetName == ".TOC.") {
1199         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1200         Value.Addend += Addend;
1201       }
1202 
1203       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1204 
1205       if (Value.SymbolName)
1206         addRelocationForSymbol(RE, Value.SymbolName);
1207       else
1208         addRelocationForSection(RE, Value.SectionID);
1209     }
1210   } else if (Arch == Triple::systemz &&
1211              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1212     // Create function stubs for both PLT and GOT references, regardless of
1213     // whether the GOT reference is to data or code.  The stub contains the
1214     // full address of the symbol, as needed by GOT references, and the
1215     // executable part only adds an overhead of 8 bytes.
1216     //
1217     // We could try to conserve space by allocating the code and data
1218     // parts of the stub separately.  However, as things stand, we allocate
1219     // a stub for every relocation, so using a GOT in JIT code should be
1220     // no less space efficient than using an explicit constant pool.
1221     DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1222     SectionEntry &Section = Sections[SectionID];
1223 
1224     // Look for an existing stub.
1225     StubMap::const_iterator i = Stubs.find(Value);
1226     uintptr_t StubAddress;
1227     if (i != Stubs.end()) {
1228       StubAddress = uintptr_t(Section.Address) + i->second;
1229       DEBUG(dbgs() << " Stub function found\n");
1230     } else {
1231       // Create a new stub function.
1232       DEBUG(dbgs() << " Create a new stub function\n");
1233 
1234       uintptr_t BaseAddress = uintptr_t(Section.Address);
1235       uintptr_t StubAlignment = getStubAlignment();
1236       StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1237                     -StubAlignment;
1238       unsigned StubOffset = StubAddress - BaseAddress;
1239 
1240       Stubs[Value] = StubOffset;
1241       createStubFunction((uint8_t *)StubAddress);
1242       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1243                          Value.Offset);
1244       if (Value.SymbolName)
1245         addRelocationForSymbol(RE, Value.SymbolName);
1246       else
1247         addRelocationForSection(RE, Value.SectionID);
1248       Section.StubOffset = StubOffset + getMaxStubSize();
1249     }
1250 
1251     if (RelType == ELF::R_390_GOTENT)
1252       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1253                         Addend);
1254     else
1255       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1256   } else if (Arch == Triple::x86_64) {
1257     if (RelType == ELF::R_X86_64_PLT32) {
1258       // The way the PLT relocations normally work is that the linker allocates
1259       // the
1260       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1261       // entry will then jump to an address provided by the GOT.  On first call,
1262       // the
1263       // GOT address will point back into PLT code that resolves the symbol. After
1264       // the first call, the GOT entry points to the actual function.
1265       //
1266       // For local functions we're ignoring all of that here and just replacing
1267       // the PLT32 relocation type with PC32, which will translate the relocation
1268       // into a PC-relative call directly to the function. For external symbols we
1269       // can't be sure the function will be within 2^32 bytes of the call site, so
1270       // we need to create a stub, which calls into the GOT.  This case is
1271       // equivalent to the usual PLT implementation except that we use the stub
1272       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1273       // rather than allocating a PLT section.
1274       if (Value.SymbolName) {
1275         // This is a call to an external function.
1276         // Look for an existing stub.
1277         SectionEntry &Section = Sections[SectionID];
1278         StubMap::const_iterator i = Stubs.find(Value);
1279         uintptr_t StubAddress;
1280         if (i != Stubs.end()) {
1281         StubAddress = uintptr_t(Section.Address) + i->second;
1282         DEBUG(dbgs() << " Stub function found\n");
1283         } else {
1284         // Create a new stub function (equivalent to a PLT entry).
1285         DEBUG(dbgs() << " Create a new stub function\n");
1286 
1287         uintptr_t BaseAddress = uintptr_t(Section.Address);
1288         uintptr_t StubAlignment = getStubAlignment();
1289         StubAddress = (BaseAddress + Section.StubOffset + StubAlignment - 1) &
1290                 -StubAlignment;
1291         unsigned StubOffset = StubAddress - BaseAddress;
1292         Stubs[Value] = StubOffset;
1293         createStubFunction((uint8_t *)StubAddress);
1294 
1295         // Bump our stub offset counter
1296         Section.StubOffset = StubOffset + getMaxStubSize();
1297 
1298         // Allocate a GOT Entry
1299         uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1300 
1301         // The load of the GOT address has an addend of -4
1302         resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4);
1303 
1304         // Fill in the value of the symbol we're targeting into the GOT
1305         addRelocationForSymbol(computeGOTOffsetRE(SectionID,GOTOffset,0,ELF::R_X86_64_64),
1306           Value.SymbolName);
1307         }
1308 
1309         // Make the target call a call into the stub table.
1310         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1311                 Addend);
1312       } else {
1313         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1314                   Value.Offset);
1315         addRelocationForSection(RE, Value.SectionID);
1316       }
1317     } else if (RelType == ELF::R_X86_64_GOTPCREL) {
1318       uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1319       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend);
1320 
1321       // Fill in the value of the symbol we're targeting into the GOT
1322       RelocationEntry RE = computeGOTOffsetRE(SectionID, GOTOffset, Value.Offset, ELF::R_X86_64_64);
1323       if (Value.SymbolName)
1324         addRelocationForSymbol(RE, Value.SymbolName);
1325       else
1326         addRelocationForSection(RE, Value.SectionID);
1327     } else if (RelType == ELF::R_X86_64_PC32) {
1328       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1329       processSimpleRelocation(SectionID, Offset, RelType, Value);
1330     } else if (RelType == ELF::R_X86_64_PC64) {
1331       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1332       processSimpleRelocation(SectionID, Offset, RelType, Value);
1333     } else {
1334       processSimpleRelocation(SectionID, Offset, RelType, Value);
1335     }
1336   } else {
1337     if (Arch == Triple::x86) {
1338       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1339     }
1340     processSimpleRelocation(SectionID, Offset, RelType, Value);
1341   }
1342   return ++RelI;
1343 }
1344 
1345 size_t RuntimeDyldELF::getGOTEntrySize() {
1346   // We don't use the GOT in all of these cases, but it's essentially free
1347   // to put them all here.
1348   size_t Result = 0;
1349   switch (Arch) {
1350   case Triple::x86_64:
1351   case Triple::aarch64:
1352   case Triple::aarch64_be:
1353   case Triple::ppc64:
1354   case Triple::ppc64le:
1355   case Triple::systemz:
1356     Result = sizeof(uint64_t);
1357     break;
1358   case Triple::x86:
1359   case Triple::arm:
1360   case Triple::thumb:
1361   case Triple::mips:
1362   case Triple::mipsel:
1363     Result = sizeof(uint32_t);
1364     break;
1365   default:
1366     llvm_unreachable("Unsupported CPU type!");
1367   }
1368   return Result;
1369 }
1370 
1371 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned SectionID, unsigned no)
1372 {
1373   (void)SectionID; // The GOT Section is the same for all section in the object file
1374   if (GOTSectionID == 0) {
1375     GOTSectionID = Sections.size();
1376     // Reserve a section id. We'll allocate the section later
1377     // once we know the total size
1378     Sections.push_back(SectionEntry(".got", 0, 0, 0));
1379   }
1380   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1381   CurrentGOTIndex += no;
1382   return StartOffset;
1383 }
1384 
1385 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset, uint64_t GOTOffset)
1386 {
1387   // Fill in the relative address of the GOT Entry into the stub
1388   RelocationEntry GOTRE(SectionID, Offset, ELF::R_X86_64_PC32, GOTOffset);
1389   addRelocationForSection(GOTRE, GOTSectionID);
1390 }
1391 
1392 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(unsigned SectionID, uint64_t GOTOffset, uint64_t SymbolOffset,
1393                                                    uint32_t Type)
1394 {
1395   (void)SectionID; // The GOT Section is the same for all section in the object file
1396   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1397 }
1398 
1399 void RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1400                                   ObjSectionToIDMap &SectionMap) {
1401   // If necessary, allocate the global offset table
1402   if (GOTSectionID != 0) {
1403     // Allocate memory for the section
1404     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1405     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1406                                                 GOTSectionID, ".got", false);
1407     if (!Addr)
1408       report_fatal_error("Unable to allocate memory for GOT!");
1409 
1410     Sections[GOTSectionID] = SectionEntry(".got", Addr, TotalSize, 0);
1411 
1412     if (Checker)
1413       Checker->registerSection(Obj.getFileName(), GOTSectionID);
1414 
1415     // For now, initialize all GOT entries to zero.  We'll fill them in as
1416     // needed when GOT-based relocations are applied.
1417     memset(Addr, 0, TotalSize);
1418   }
1419 
1420   // Look for and record the EH frame section.
1421   ObjSectionToIDMap::iterator i, e;
1422   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1423     const SectionRef &Section = i->first;
1424     StringRef Name;
1425     Section.getName(Name);
1426     if (Name == ".eh_frame") {
1427       UnregisteredEHFrameSections.push_back(i->second);
1428       break;
1429     }
1430   }
1431 
1432   GOTSectionID = 0;
1433   CurrentGOTIndex = 0;
1434 }
1435 
1436 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1437   return Obj.isELF();
1438 }
1439 
1440 } // namespace llvm
1441