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 
check(std::error_code Err)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
classof(const Binary * v)62   static inline bool classof(const Binary *v) {
63     return (isa<ELFObjectFile<ELFT>>(v) &&
64             classof(cast<ELFObjectFile<ELFT>>(v)));
65   }
classof(const ELFObjectFile<ELFT> * v)66   static inline bool classof(const ELFObjectFile<ELFT> *v) {
67     return v->isDyldType();
68   }
69 };
70 
71 
72 
73 // The MemoryBuffer passed into this constructor is just a wrapper around the
74 // actual memory.  Ultimately, the Binary parent class will take ownership of
75 // this MemoryBuffer object but not the underlying memory.
76 template <class ELFT>
DyldELFObject(MemoryBufferRef Wrapper,std::error_code & EC)77 DyldELFObject<ELFT>::DyldELFObject(MemoryBufferRef Wrapper, std::error_code &EC)
78     : ELFObjectFile<ELFT>(Wrapper, EC) {
79   this->isDyldELFObject = true;
80 }
81 
82 template <class ELFT>
updateSectionAddress(const SectionRef & Sec,uint64_t Addr)83 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
84                                                uint64_t Addr) {
85   DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
86   Elf_Shdr *shdr =
87       const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
88 
89   // This assumes the address passed in matches the target address bitness
90   // The template-based type cast handles everything else.
91   shdr->sh_addr = static_cast<addr_type>(Addr);
92 }
93 
94 template <class ELFT>
updateSymbolAddress(const SymbolRef & SymRef,uint64_t Addr)95 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
96                                               uint64_t Addr) {
97 
98   Elf_Sym *sym = const_cast<Elf_Sym *>(
99       ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
100 
101   // This assumes the address passed in matches the target address bitness
102   // The template-based type cast handles everything else.
103   sym->st_value = static_cast<addr_type>(Addr);
104 }
105 
106 class LoadedELFObjectInfo final
107     : public RuntimeDyld::LoadedObjectInfoHelper<LoadedELFObjectInfo> {
108 public:
LoadedELFObjectInfo(RuntimeDyldImpl & RTDyld,ObjSectionToIDMap ObjSecToIDMap)109   LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
110       : LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {}
111 
112   OwningBinary<ObjectFile>
113   getObjectForDebug(const ObjectFile &Obj) const override;
114 };
115 
116 template <typename ELFT>
117 std::unique_ptr<DyldELFObject<ELFT>>
createRTDyldELFObject(MemoryBufferRef Buffer,const ObjectFile & SourceObject,const LoadedELFObjectInfo & L,std::error_code & ec)118 createRTDyldELFObject(MemoryBufferRef Buffer,
119                       const ObjectFile &SourceObject,
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   auto SI = SourceObject.section_begin();
130   for (const auto &Sec : Obj->sections()) {
131     StringRef SectionName;
132     Sec.getName(SectionName);
133     if (SectionName != "") {
134       DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
135       Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
136           reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
137 
138       if (uint64_t SecLoadAddr = L.getSectionLoadAddress(*SI)) {
139         // This assumes that the address passed in matches the target address
140         // bitness. The template-based type cast handles everything else.
141         shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
142       }
143     }
144     ++SI;
145   }
146 
147   return Obj;
148 }
149 
createELFDebugObject(const ObjectFile & Obj,const LoadedELFObjectInfo & L)150 OwningBinary<ObjectFile> createELFDebugObject(const ObjectFile &Obj,
151                                               const LoadedELFObjectInfo &L) {
152   assert(Obj.isELF() && "Not an ELF object file.");
153 
154   std::unique_ptr<MemoryBuffer> Buffer =
155     MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
156 
157   std::error_code ec;
158 
159   std::unique_ptr<ObjectFile> DebugObj;
160   if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian()) {
161     typedef ELFType<support::little, false> ELF32LE;
162     DebugObj = createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), Obj, L,
163                                               ec);
164   } else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian()) {
165     typedef ELFType<support::big, false> ELF32BE;
166     DebugObj = createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), Obj, L,
167                                               ec);
168   } else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian()) {
169     typedef ELFType<support::big, true> ELF64BE;
170     DebugObj = createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), Obj, L,
171                                               ec);
172   } else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian()) {
173     typedef ELFType<support::little, true> ELF64LE;
174     DebugObj = createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), Obj, L,
175                                               ec);
176   } else
177     llvm_unreachable("Unexpected ELF format");
178 
179   assert(!ec && "Could not construct copy ELF object file");
180 
181   return OwningBinary<ObjectFile>(std::move(DebugObj), std::move(Buffer));
182 }
183 
184 OwningBinary<ObjectFile>
getObjectForDebug(const ObjectFile & Obj) const185 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
186   return createELFDebugObject(Obj, *this);
187 }
188 
189 } // anonymous namespace
190 
191 namespace llvm {
192 
RuntimeDyldELF(RuntimeDyld::MemoryManager & MemMgr,RuntimeDyld::SymbolResolver & Resolver)193 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
194                                RuntimeDyld::SymbolResolver &Resolver)
195     : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
~RuntimeDyldELF()196 RuntimeDyldELF::~RuntimeDyldELF() {}
197 
registerEHFrames()198 void RuntimeDyldELF::registerEHFrames() {
199   for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
200     SID EHFrameSID = UnregisteredEHFrameSections[i];
201     uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
202     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
203     size_t EHFrameSize = Sections[EHFrameSID].getSize();
204     MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
205     RegisteredEHFrameSections.push_back(EHFrameSID);
206   }
207   UnregisteredEHFrameSections.clear();
208 }
209 
deregisterEHFrames()210 void RuntimeDyldELF::deregisterEHFrames() {
211   for (int i = 0, e = RegisteredEHFrameSections.size(); i != e; ++i) {
212     SID EHFrameSID = RegisteredEHFrameSections[i];
213     uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
214     uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
215     size_t EHFrameSize = Sections[EHFrameSID].getSize();
216     MemMgr.deregisterEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
217   }
218   RegisteredEHFrameSections.clear();
219 }
220 
221 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
loadObject(const object::ObjectFile & O)222 RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
223   return llvm::make_unique<LoadedELFObjectInfo>(*this, loadObjectImpl(O));
224 }
225 
resolveX86_64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend,uint64_t SymOffset)226 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
227                                              uint64_t Offset, uint64_t Value,
228                                              uint32_t Type, int64_t Addend,
229                                              uint64_t SymOffset) {
230   switch (Type) {
231   default:
232     llvm_unreachable("Relocation type not implemented yet!");
233     break;
234   case ELF::R_X86_64_64: {
235     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
236         Value + Addend;
237     DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
238                  << format("%p\n", Section.getAddressWithOffset(Offset)));
239     break;
240   }
241   case ELF::R_X86_64_32:
242   case ELF::R_X86_64_32S: {
243     Value += Addend;
244     assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
245            (Type == ELF::R_X86_64_32S &&
246             ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
247     uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
248     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
249         TruncatedAddr;
250     DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
251                  << format("%p\n", Section.getAddressWithOffset(Offset)));
252     break;
253   }
254   case ELF::R_X86_64_PC8: {
255     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
256     int64_t RealOffset = Value + Addend - FinalAddress;
257     assert(isInt<8>(RealOffset));
258     int8_t TruncOffset = (RealOffset & 0xFF);
259     Section.getAddress()[Offset] = TruncOffset;
260     break;
261   }
262   case ELF::R_X86_64_PC32: {
263     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
264     int64_t RealOffset = Value + Addend - FinalAddress;
265     assert(isInt<32>(RealOffset));
266     int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
267     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
268         TruncOffset;
269     break;
270   }
271   case ELF::R_X86_64_PC64: {
272     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
273     int64_t RealOffset = Value + Addend - FinalAddress;
274     support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
275         RealOffset;
276     break;
277   }
278   }
279 }
280 
resolveX86Relocation(const SectionEntry & Section,uint64_t Offset,uint32_t Value,uint32_t Type,int32_t Addend)281 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
282                                           uint64_t Offset, uint32_t Value,
283                                           uint32_t Type, int32_t Addend) {
284   switch (Type) {
285   case ELF::R_386_32: {
286     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
287         Value + Addend;
288     break;
289   }
290   case ELF::R_386_PC32: {
291     uint32_t FinalAddress =
292         Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
293     uint32_t RealOffset = Value + Addend - FinalAddress;
294     support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
295         RealOffset;
296     break;
297   }
298   default:
299     // There are other relocation types, but it appears these are the
300     // only ones currently used by the LLVM ELF object writer
301     llvm_unreachable("Relocation type not implemented yet!");
302     break;
303   }
304 }
305 
resolveAArch64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)306 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
307                                               uint64_t Offset, uint64_t Value,
308                                               uint32_t Type, int64_t Addend) {
309   uint32_t *TargetPtr =
310       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
311   uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
312 
313   DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
314                << format("%llx", Section.getAddressWithOffset(Offset))
315                << " FinalAddress: 0x" << format("%llx", FinalAddress)
316                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
317                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
318                << "\n");
319 
320   switch (Type) {
321   default:
322     llvm_unreachable("Relocation type not implemented yet!");
323     break;
324   case ELF::R_AARCH64_ABS64: {
325     uint64_t *TargetPtr =
326         reinterpret_cast<uint64_t *>(Section.getAddressWithOffset(Offset));
327     *TargetPtr = Value + Addend;
328     break;
329   }
330   case ELF::R_AARCH64_PREL32: {
331     uint64_t Result = Value + Addend - FinalAddress;
332     assert(static_cast<int64_t>(Result) >= INT32_MIN &&
333            static_cast<int64_t>(Result) <= UINT32_MAX);
334     *TargetPtr = static_cast<uint32_t>(Result & 0xffffffffU);
335     break;
336   }
337   case ELF::R_AARCH64_CALL26: // fallthrough
338   case ELF::R_AARCH64_JUMP26: {
339     // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
340     // calculation.
341     uint64_t BranchImm = Value + Addend - FinalAddress;
342 
343     // "Check that -2^27 <= result < 2^27".
344     assert(isInt<28>(BranchImm));
345 
346     // AArch64 code is emitted with .rela relocations. The data already in any
347     // bits affected by the relocation on entry is garbage.
348     *TargetPtr &= 0xfc000000U;
349     // Immediate goes in bits 25:0 of B and BL.
350     *TargetPtr |= static_cast<uint32_t>(BranchImm & 0xffffffcU) >> 2;
351     break;
352   }
353   case ELF::R_AARCH64_MOVW_UABS_G3: {
354     uint64_t Result = Value + Addend;
355 
356     // AArch64 code is emitted with .rela relocations. The data already in any
357     // bits affected by the relocation on entry is garbage.
358     *TargetPtr &= 0xffe0001fU;
359     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
360     *TargetPtr |= Result >> (48 - 5);
361     // Shift must be "lsl #48", in bits 22:21
362     assert((*TargetPtr >> 21 & 0x3) == 3 && "invalid shift for relocation");
363     break;
364   }
365   case ELF::R_AARCH64_MOVW_UABS_G2_NC: {
366     uint64_t Result = Value + Addend;
367 
368     // AArch64 code is emitted with .rela relocations. The data already in any
369     // bits affected by the relocation on entry is garbage.
370     *TargetPtr &= 0xffe0001fU;
371     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
372     *TargetPtr |= ((Result & 0xffff00000000ULL) >> (32 - 5));
373     // Shift must be "lsl #32", in bits 22:21
374     assert((*TargetPtr >> 21 & 0x3) == 2 && "invalid shift for relocation");
375     break;
376   }
377   case ELF::R_AARCH64_MOVW_UABS_G1_NC: {
378     uint64_t Result = Value + Addend;
379 
380     // AArch64 code is emitted with .rela relocations. The data already in any
381     // bits affected by the relocation on entry is garbage.
382     *TargetPtr &= 0xffe0001fU;
383     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
384     *TargetPtr |= ((Result & 0xffff0000U) >> (16 - 5));
385     // Shift must be "lsl #16", in bits 22:2
386     assert((*TargetPtr >> 21 & 0x3) == 1 && "invalid shift for relocation");
387     break;
388   }
389   case ELF::R_AARCH64_MOVW_UABS_G0_NC: {
390     uint64_t Result = Value + Addend;
391 
392     // AArch64 code is emitted with .rela relocations. The data already in any
393     // bits affected by the relocation on entry is garbage.
394     *TargetPtr &= 0xffe0001fU;
395     // Immediate goes in bits 20:5 of MOVZ/MOVK instruction
396     *TargetPtr |= ((Result & 0xffffU) << 5);
397     // Shift must be "lsl #0", in bits 22:21.
398     assert((*TargetPtr >> 21 & 0x3) == 0 && "invalid shift for relocation");
399     break;
400   }
401   case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
402     // Operation: Page(S+A) - Page(P)
403     uint64_t Result =
404         ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
405 
406     // Check that -2^32 <= X < 2^32
407     assert(isInt<33>(Result) && "overflow check failed for relocation");
408 
409     // AArch64 code is emitted with .rela relocations. The data already in any
410     // bits affected by the relocation on entry is garbage.
411     *TargetPtr &= 0x9f00001fU;
412     // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
413     // from bits 32:12 of X.
414     *TargetPtr |= ((Result & 0x3000U) << (29 - 12));
415     *TargetPtr |= ((Result & 0x1ffffc000ULL) >> (14 - 5));
416     break;
417   }
418   case ELF::R_AARCH64_LDST32_ABS_LO12_NC: {
419     // Operation: S + A
420     uint64_t Result = Value + Addend;
421 
422     // AArch64 code is emitted with .rela relocations. The data already in any
423     // bits affected by the relocation on entry is garbage.
424     *TargetPtr &= 0xffc003ffU;
425     // Immediate goes in bits 21:10 of LD/ST instruction, taken
426     // from bits 11:2 of X
427     *TargetPtr |= ((Result & 0xffc) << (10 - 2));
428     break;
429   }
430   case ELF::R_AARCH64_LDST64_ABS_LO12_NC: {
431     // Operation: S + A
432     uint64_t Result = Value + Addend;
433 
434     // AArch64 code is emitted with .rela relocations. The data already in any
435     // bits affected by the relocation on entry is garbage.
436     *TargetPtr &= 0xffc003ffU;
437     // Immediate goes in bits 21:10 of LD/ST instruction, taken
438     // from bits 11:3 of X
439     *TargetPtr |= ((Result & 0xff8) << (10 - 3));
440     break;
441   }
442   }
443 }
444 
resolveARMRelocation(const SectionEntry & Section,uint64_t Offset,uint32_t Value,uint32_t Type,int32_t Addend)445 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
446                                           uint64_t Offset, uint32_t Value,
447                                           uint32_t Type, int32_t Addend) {
448   // TODO: Add Thumb relocations.
449   uint32_t *TargetPtr =
450       reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
451   uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
452   Value += Addend;
453 
454   DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
455                << Section.getAddressWithOffset(Offset)
456                << " FinalAddress: " << format("%p", FinalAddress) << " Value: "
457                << format("%x", Value) << " Type: " << format("%x", Type)
458                << " Addend: " << format("%x", Addend) << "\n");
459 
460   switch (Type) {
461   default:
462     llvm_unreachable("Not implemented relocation type!");
463 
464   case ELF::R_ARM_NONE:
465     break;
466   case ELF::R_ARM_PREL31:
467   case ELF::R_ARM_TARGET1:
468   case ELF::R_ARM_ABS32:
469     *TargetPtr = Value;
470     break;
471     // Write first 16 bit of 32 bit value to the mov instruction.
472     // Last 4 bit should be shifted.
473   case ELF::R_ARM_MOVW_ABS_NC:
474   case ELF::R_ARM_MOVT_ABS:
475     if (Type == ELF::R_ARM_MOVW_ABS_NC)
476       Value = Value & 0xFFFF;
477     else if (Type == ELF::R_ARM_MOVT_ABS)
478       Value = (Value >> 16) & 0xFFFF;
479     *TargetPtr &= ~0x000F0FFF;
480     *TargetPtr |= Value & 0xFFF;
481     *TargetPtr |= ((Value >> 12) & 0xF) << 16;
482     break;
483     // Write 24 bit relative value to the branch instruction.
484   case ELF::R_ARM_PC24: // Fall through.
485   case ELF::R_ARM_CALL: // Fall through.
486   case ELF::R_ARM_JUMP24:
487     int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
488     RelValue = (RelValue & 0x03FFFFFC) >> 2;
489     assert((*TargetPtr & 0xFFFFFF) == 0xFFFFFE);
490     *TargetPtr &= 0xFF000000;
491     *TargetPtr |= RelValue;
492     break;
493   }
494 }
495 
resolveMIPSRelocation(const SectionEntry & Section,uint64_t Offset,uint32_t Value,uint32_t Type,int32_t Addend)496 void RuntimeDyldELF::resolveMIPSRelocation(const SectionEntry &Section,
497                                            uint64_t Offset, uint32_t Value,
498                                            uint32_t Type, int32_t Addend) {
499   uint8_t *TargetPtr = Section.getAddressWithOffset(Offset);
500   Value += Addend;
501 
502   DEBUG(dbgs() << "resolveMIPSRelocation, LocalAddress: "
503                << Section.getAddressWithOffset(Offset) << " FinalAddress: "
504                << format("%p", Section.getLoadAddressWithOffset(Offset))
505                << " Value: " << format("%x", Value)
506                << " Type: " << format("%x", Type)
507                << " Addend: " << format("%x", Addend) << "\n");
508 
509   uint32_t Insn = readBytesUnaligned(TargetPtr, 4);
510 
511   switch (Type) {
512   default:
513     llvm_unreachable("Not implemented relocation type!");
514     break;
515   case ELF::R_MIPS_32:
516     writeBytesUnaligned(Value, TargetPtr, 4);
517     break;
518   case ELF::R_MIPS_26:
519     Insn &= 0xfc000000;
520     Insn |= (Value & 0x0fffffff) >> 2;
521     writeBytesUnaligned(Insn, TargetPtr, 4);
522     break;
523   case ELF::R_MIPS_HI16:
524     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
525     Insn &= 0xffff0000;
526     Insn |= ((Value + 0x8000) >> 16) & 0xffff;
527     writeBytesUnaligned(Insn, TargetPtr, 4);
528     break;
529   case ELF::R_MIPS_LO16:
530     Insn &= 0xffff0000;
531     Insn |= Value & 0xffff;
532     writeBytesUnaligned(Insn, TargetPtr, 4);
533     break;
534   case ELF::R_MIPS_PC32: {
535     uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
536     writeBytesUnaligned(Value - FinalAddress, (uint8_t *)TargetPtr, 4);
537     break;
538   }
539   case ELF::R_MIPS_PC16: {
540     uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
541     Insn &= 0xffff0000;
542     Insn |= ((Value - FinalAddress) >> 2) & 0xffff;
543     writeBytesUnaligned(Insn, TargetPtr, 4);
544     break;
545   }
546   case ELF::R_MIPS_PC19_S2: {
547     uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
548     Insn &= 0xfff80000;
549     Insn |= ((Value - (FinalAddress & ~0x3)) >> 2) & 0x7ffff;
550     writeBytesUnaligned(Insn, TargetPtr, 4);
551     break;
552   }
553   case ELF::R_MIPS_PC21_S2: {
554     uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
555     Insn &= 0xffe00000;
556     Insn |= ((Value - FinalAddress) >> 2) & 0x1fffff;
557     writeBytesUnaligned(Insn, TargetPtr, 4);
558     break;
559   }
560   case ELF::R_MIPS_PC26_S2: {
561     uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
562     Insn &= 0xfc000000;
563     Insn |= ((Value - FinalAddress) >> 2) & 0x3ffffff;
564     writeBytesUnaligned(Insn, TargetPtr, 4);
565     break;
566   }
567   case ELF::R_MIPS_PCHI16: {
568     uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
569     Insn &= 0xffff0000;
570     Insn |= ((Value - FinalAddress + 0x8000) >> 16) & 0xffff;
571     writeBytesUnaligned(Insn, TargetPtr, 4);
572     break;
573   }
574   case ELF::R_MIPS_PCLO16: {
575     uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
576     Insn &= 0xffff0000;
577     Insn |= (Value - FinalAddress) & 0xffff;
578     writeBytesUnaligned(Insn, TargetPtr, 4);
579     break;
580   }
581   }
582 }
583 
setMipsABI(const ObjectFile & Obj)584 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
585   if (Arch == Triple::UnknownArch ||
586       !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
587     IsMipsO32ABI = false;
588     IsMipsN64ABI = false;
589     return;
590   }
591   unsigned AbiVariant;
592   Obj.getPlatformFlags(AbiVariant);
593   IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
594   IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips");
595   if (AbiVariant & ELF::EF_MIPS_ABI2)
596     llvm_unreachable("Mips N32 ABI is not supported yet");
597 }
598 
resolveMIPS64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend,uint64_t SymOffset,SID SectionID)599 void RuntimeDyldELF::resolveMIPS64Relocation(const SectionEntry &Section,
600                                              uint64_t Offset, uint64_t Value,
601                                              uint32_t Type, int64_t Addend,
602                                              uint64_t SymOffset,
603                                              SID SectionID) {
604   uint32_t r_type = Type & 0xff;
605   uint32_t r_type2 = (Type >> 8) & 0xff;
606   uint32_t r_type3 = (Type >> 16) & 0xff;
607 
608   // RelType is used to keep information for which relocation type we are
609   // applying relocation.
610   uint32_t RelType = r_type;
611   int64_t CalculatedValue = evaluateMIPS64Relocation(Section, Offset, Value,
612                                                      RelType, Addend,
613                                                      SymOffset, SectionID);
614   if (r_type2 != ELF::R_MIPS_NONE) {
615     RelType = r_type2;
616     CalculatedValue = evaluateMIPS64Relocation(Section, Offset, 0, RelType,
617                                                CalculatedValue, SymOffset,
618                                                SectionID);
619   }
620   if (r_type3 != ELF::R_MIPS_NONE) {
621     RelType = r_type3;
622     CalculatedValue = evaluateMIPS64Relocation(Section, Offset, 0, RelType,
623                                                CalculatedValue, SymOffset,
624                                                SectionID);
625   }
626   applyMIPS64Relocation(Section.getAddressWithOffset(Offset), CalculatedValue,
627                         RelType);
628 }
629 
630 int64_t
evaluateMIPS64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend,uint64_t SymOffset,SID SectionID)631 RuntimeDyldELF::evaluateMIPS64Relocation(const SectionEntry &Section,
632                                          uint64_t Offset, uint64_t Value,
633                                          uint32_t Type, int64_t Addend,
634                                          uint64_t SymOffset, SID SectionID) {
635 
636   DEBUG(dbgs() << "evaluateMIPS64Relocation, LocalAddress: 0x"
637                << format("%llx", Section.getAddressWithOffset(Offset))
638                << " FinalAddress: 0x"
639                << format("%llx", Section.getLoadAddressWithOffset(Offset))
640                << " Value: 0x" << format("%llx", Value) << " Type: 0x"
641                << format("%x", Type) << " Addend: 0x" << format("%llx", Addend)
642                << " SymOffset: " << format("%x", SymOffset) << "\n");
643 
644   switch (Type) {
645   default:
646     llvm_unreachable("Not implemented relocation type!");
647     break;
648   case ELF::R_MIPS_JALR:
649   case ELF::R_MIPS_NONE:
650     break;
651   case ELF::R_MIPS_32:
652   case ELF::R_MIPS_64:
653     return Value + Addend;
654   case ELF::R_MIPS_26:
655     return ((Value + Addend) >> 2) & 0x3ffffff;
656   case ELF::R_MIPS_GPREL16: {
657     uint64_t GOTAddr = getSectionLoadAddress(SectionToGOTMap[SectionID]);
658     return Value + Addend - (GOTAddr + 0x7ff0);
659   }
660   case ELF::R_MIPS_SUB:
661     return Value - Addend;
662   case ELF::R_MIPS_HI16:
663     // Get the higher 16-bits. Also add 1 if bit 15 is 1.
664     return ((Value + Addend + 0x8000) >> 16) & 0xffff;
665   case ELF::R_MIPS_LO16:
666     return (Value + Addend) & 0xffff;
667   case ELF::R_MIPS_CALL16:
668   case ELF::R_MIPS_GOT_DISP:
669   case ELF::R_MIPS_GOT_PAGE: {
670     uint8_t *LocalGOTAddr =
671         getSectionAddress(SectionToGOTMap[SectionID]) + SymOffset;
672     uint64_t GOTEntry = readBytesUnaligned(LocalGOTAddr, 8);
673 
674     Value += Addend;
675     if (Type == ELF::R_MIPS_GOT_PAGE)
676       Value = (Value + 0x8000) & ~0xffff;
677 
678     if (GOTEntry)
679       assert(GOTEntry == Value &&
680                    "GOT entry has two different addresses.");
681     else
682       writeBytesUnaligned(Value, LocalGOTAddr, 8);
683 
684     return (SymOffset - 0x7ff0) & 0xffff;
685   }
686   case ELF::R_MIPS_GOT_OFST: {
687     int64_t page = (Value + Addend + 0x8000) & ~0xffff;
688     return (Value + Addend - page) & 0xffff;
689   }
690   case ELF::R_MIPS_GPREL32: {
691     uint64_t GOTAddr = getSectionLoadAddress(SectionToGOTMap[SectionID]);
692     return Value + Addend - (GOTAddr + 0x7ff0);
693   }
694   case ELF::R_MIPS_PC16: {
695     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
696     return ((Value + Addend - FinalAddress) >> 2) & 0xffff;
697   }
698   case ELF::R_MIPS_PC32: {
699     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
700     return Value + Addend - FinalAddress;
701   }
702   case ELF::R_MIPS_PC18_S3: {
703     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
704     return ((Value + Addend - (FinalAddress & ~0x7)) >> 3) & 0x3ffff;
705   }
706   case ELF::R_MIPS_PC19_S2: {
707     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
708     return ((Value + Addend - (FinalAddress & ~0x3)) >> 2) & 0x7ffff;
709   }
710   case ELF::R_MIPS_PC21_S2: {
711     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
712     return ((Value + Addend - FinalAddress) >> 2) & 0x1fffff;
713   }
714   case ELF::R_MIPS_PC26_S2: {
715     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
716     return ((Value + Addend - FinalAddress) >> 2) & 0x3ffffff;
717   }
718   case ELF::R_MIPS_PCHI16: {
719     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
720     return ((Value + Addend - FinalAddress + 0x8000) >> 16) & 0xffff;
721   }
722   case ELF::R_MIPS_PCLO16: {
723     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
724     return (Value + Addend - FinalAddress) & 0xffff;
725   }
726   }
727   return 0;
728 }
729 
applyMIPS64Relocation(uint8_t * TargetPtr,int64_t CalculatedValue,uint32_t Type)730 void RuntimeDyldELF::applyMIPS64Relocation(uint8_t *TargetPtr,
731                                            int64_t CalculatedValue,
732                                            uint32_t Type) {
733   uint32_t Insn = readBytesUnaligned(TargetPtr, 4);
734 
735   switch (Type) {
736     default:
737       break;
738     case ELF::R_MIPS_32:
739     case ELF::R_MIPS_GPREL32:
740     case ELF::R_MIPS_PC32:
741       writeBytesUnaligned(CalculatedValue & 0xffffffff, TargetPtr, 4);
742       break;
743     case ELF::R_MIPS_64:
744     case ELF::R_MIPS_SUB:
745       writeBytesUnaligned(CalculatedValue, TargetPtr, 8);
746       break;
747     case ELF::R_MIPS_26:
748     case ELF::R_MIPS_PC26_S2:
749       Insn = (Insn & 0xfc000000) | CalculatedValue;
750       writeBytesUnaligned(Insn, TargetPtr, 4);
751       break;
752     case ELF::R_MIPS_GPREL16:
753       Insn = (Insn & 0xffff0000) | (CalculatedValue & 0xffff);
754       writeBytesUnaligned(Insn, TargetPtr, 4);
755       break;
756     case ELF::R_MIPS_HI16:
757     case ELF::R_MIPS_LO16:
758     case ELF::R_MIPS_PCHI16:
759     case ELF::R_MIPS_PCLO16:
760     case ELF::R_MIPS_PC16:
761     case ELF::R_MIPS_CALL16:
762     case ELF::R_MIPS_GOT_DISP:
763     case ELF::R_MIPS_GOT_PAGE:
764     case ELF::R_MIPS_GOT_OFST:
765       Insn = (Insn & 0xffff0000) | CalculatedValue;
766       writeBytesUnaligned(Insn, TargetPtr, 4);
767       break;
768     case ELF::R_MIPS_PC18_S3:
769       Insn = (Insn & 0xfffc0000) | CalculatedValue;
770       writeBytesUnaligned(Insn, TargetPtr, 4);
771       break;
772     case ELF::R_MIPS_PC19_S2:
773       Insn = (Insn & 0xfff80000) | CalculatedValue;
774       writeBytesUnaligned(Insn, TargetPtr, 4);
775       break;
776     case ELF::R_MIPS_PC21_S2:
777       Insn = (Insn & 0xffe00000) | CalculatedValue;
778       writeBytesUnaligned(Insn, TargetPtr, 4);
779       break;
780     }
781 }
782 
783 // Return the .TOC. section and offset.
findPPC64TOCSection(const ELFObjectFileBase & Obj,ObjSectionToIDMap & LocalSections,RelocationValueRef & Rel)784 void RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
785                                          ObjSectionToIDMap &LocalSections,
786                                          RelocationValueRef &Rel) {
787   // Set a default SectionID in case we do not find a TOC section below.
788   // This may happen for references to TOC base base (sym@toc, .odp
789   // relocation) without a .toc directive.  In this case just use the
790   // first section (which is usually the .odp) since the code won't
791   // reference the .toc base directly.
792   Rel.SymbolName = nullptr;
793   Rel.SectionID = 0;
794 
795   // The TOC consists of sections .got, .toc, .tocbss, .plt in that
796   // order. The TOC starts where the first of these sections starts.
797   for (auto &Section: Obj.sections()) {
798     StringRef SectionName;
799     check(Section.getName(SectionName));
800 
801     if (SectionName == ".got"
802         || SectionName == ".toc"
803         || SectionName == ".tocbss"
804         || SectionName == ".plt") {
805       Rel.SectionID = findOrEmitSection(Obj, Section, false, LocalSections);
806       break;
807     }
808   }
809 
810   // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
811   // thus permitting a full 64 Kbytes segment.
812   Rel.Addend = 0x8000;
813 }
814 
815 // Returns the sections and offset associated with the ODP entry referenced
816 // by Symbol.
findOPDEntrySection(const ELFObjectFileBase & Obj,ObjSectionToIDMap & LocalSections,RelocationValueRef & Rel)817 void RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
818                                          ObjSectionToIDMap &LocalSections,
819                                          RelocationValueRef &Rel) {
820   // Get the ELF symbol value (st_value) to compare with Relocation offset in
821   // .opd entries
822   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
823        si != se; ++si) {
824     section_iterator RelSecI = si->getRelocatedSection();
825     if (RelSecI == Obj.section_end())
826       continue;
827 
828     StringRef RelSectionName;
829     check(RelSecI->getName(RelSectionName));
830     if (RelSectionName != ".opd")
831       continue;
832 
833     for (elf_relocation_iterator i = si->relocation_begin(),
834                                  e = si->relocation_end();
835          i != e;) {
836       // The R_PPC64_ADDR64 relocation indicates the first field
837       // of a .opd entry
838       uint64_t TypeFunc = i->getType();
839       if (TypeFunc != ELF::R_PPC64_ADDR64) {
840         ++i;
841         continue;
842       }
843 
844       uint64_t TargetSymbolOffset = i->getOffset();
845       symbol_iterator TargetSymbol = i->getSymbol();
846       ErrorOr<int64_t> AddendOrErr = i->getAddend();
847       Check(AddendOrErr.getError());
848       int64_t Addend = *AddendOrErr;
849 
850       ++i;
851       if (i == e)
852         break;
853 
854       // Just check if following relocation is a R_PPC64_TOC
855       uint64_t TypeTOC = i->getType();
856       if (TypeTOC != ELF::R_PPC64_TOC)
857         continue;
858 
859       // Finally compares the Symbol value and the target symbol offset
860       // to check if this .opd entry refers to the symbol the relocation
861       // points to.
862       if (Rel.Addend != (int64_t)TargetSymbolOffset)
863         continue;
864 
865       ErrorOr<section_iterator> TSIOrErr = TargetSymbol->getSection();
866       check(TSIOrErr.getError());
867       section_iterator tsi = *TSIOrErr;
868       bool IsCode = tsi->isText();
869       Rel.SectionID = findOrEmitSection(Obj, (*tsi), IsCode, LocalSections);
870       Rel.Addend = (intptr_t)Addend;
871       return;
872     }
873   }
874   llvm_unreachable("Attempting to get address of ODP entry!");
875 }
876 
877 // Relocation masks following the #lo(value), #hi(value), #ha(value),
878 // #higher(value), #highera(value), #highest(value), and #highesta(value)
879 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
880 // document.
881 
applyPPClo(uint64_t value)882 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
883 
applyPPChi(uint64_t value)884 static inline uint16_t applyPPChi(uint64_t value) {
885   return (value >> 16) & 0xffff;
886 }
887 
applyPPCha(uint64_t value)888 static inline uint16_t applyPPCha (uint64_t value) {
889   return ((value + 0x8000) >> 16) & 0xffff;
890 }
891 
applyPPChigher(uint64_t value)892 static inline uint16_t applyPPChigher(uint64_t value) {
893   return (value >> 32) & 0xffff;
894 }
895 
applyPPChighera(uint64_t value)896 static inline uint16_t applyPPChighera (uint64_t value) {
897   return ((value + 0x8000) >> 32) & 0xffff;
898 }
899 
applyPPChighest(uint64_t value)900 static inline uint16_t applyPPChighest(uint64_t value) {
901   return (value >> 48) & 0xffff;
902 }
903 
applyPPChighesta(uint64_t value)904 static inline uint16_t applyPPChighesta (uint64_t value) {
905   return ((value + 0x8000) >> 48) & 0xffff;
906 }
907 
resolvePPC32Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)908 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
909                                             uint64_t Offset, uint64_t Value,
910                                             uint32_t Type, int64_t Addend) {
911   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
912   switch (Type) {
913   default:
914     llvm_unreachable("Relocation type not implemented yet!");
915     break;
916   case ELF::R_PPC_ADDR16_LO:
917     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
918     break;
919   case ELF::R_PPC_ADDR16_HI:
920     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
921     break;
922   case ELF::R_PPC_ADDR16_HA:
923     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
924     break;
925   }
926 }
927 
resolvePPC64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)928 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
929                                             uint64_t Offset, uint64_t Value,
930                                             uint32_t Type, int64_t Addend) {
931   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
932   switch (Type) {
933   default:
934     llvm_unreachable("Relocation type not implemented yet!");
935     break;
936   case ELF::R_PPC64_ADDR16:
937     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
938     break;
939   case ELF::R_PPC64_ADDR16_DS:
940     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
941     break;
942   case ELF::R_PPC64_ADDR16_LO:
943     writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
944     break;
945   case ELF::R_PPC64_ADDR16_LO_DS:
946     writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
947     break;
948   case ELF::R_PPC64_ADDR16_HI:
949     writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
950     break;
951   case ELF::R_PPC64_ADDR16_HA:
952     writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
953     break;
954   case ELF::R_PPC64_ADDR16_HIGHER:
955     writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
956     break;
957   case ELF::R_PPC64_ADDR16_HIGHERA:
958     writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
959     break;
960   case ELF::R_PPC64_ADDR16_HIGHEST:
961     writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
962     break;
963   case ELF::R_PPC64_ADDR16_HIGHESTA:
964     writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
965     break;
966   case ELF::R_PPC64_ADDR14: {
967     assert(((Value + Addend) & 3) == 0);
968     // Preserve the AA/LK bits in the branch instruction
969     uint8_t aalk = *(LocalAddress + 3);
970     writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
971   } break;
972   case ELF::R_PPC64_REL16_LO: {
973     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
974     uint64_t Delta = Value - FinalAddress + Addend;
975     writeInt16BE(LocalAddress, applyPPClo(Delta));
976   } break;
977   case ELF::R_PPC64_REL16_HI: {
978     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
979     uint64_t Delta = Value - FinalAddress + Addend;
980     writeInt16BE(LocalAddress, applyPPChi(Delta));
981   } break;
982   case ELF::R_PPC64_REL16_HA: {
983     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
984     uint64_t Delta = Value - FinalAddress + Addend;
985     writeInt16BE(LocalAddress, applyPPCha(Delta));
986   } break;
987   case ELF::R_PPC64_ADDR32: {
988     int32_t Result = static_cast<int32_t>(Value + Addend);
989     if (SignExtend32<32>(Result) != Result)
990       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
991     writeInt32BE(LocalAddress, Result);
992   } break;
993   case ELF::R_PPC64_REL24: {
994     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
995     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
996     if (SignExtend32<26>(delta) != delta)
997       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
998     // Generates a 'bl <address>' instruction
999     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
1000   } break;
1001   case ELF::R_PPC64_REL32: {
1002     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
1003     int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
1004     if (SignExtend32<32>(delta) != delta)
1005       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
1006     writeInt32BE(LocalAddress, delta);
1007   } break;
1008   case ELF::R_PPC64_REL64: {
1009     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
1010     uint64_t Delta = Value - FinalAddress + Addend;
1011     writeInt64BE(LocalAddress, Delta);
1012   } break;
1013   case ELF::R_PPC64_ADDR64:
1014     writeInt64BE(LocalAddress, Value + Addend);
1015     break;
1016   }
1017 }
1018 
resolveSystemZRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)1019 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
1020                                               uint64_t Offset, uint64_t Value,
1021                                               uint32_t Type, int64_t Addend) {
1022   uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
1023   switch (Type) {
1024   default:
1025     llvm_unreachable("Relocation type not implemented yet!");
1026     break;
1027   case ELF::R_390_PC16DBL:
1028   case ELF::R_390_PLT16DBL: {
1029     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
1030     assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
1031     writeInt16BE(LocalAddress, Delta / 2);
1032     break;
1033   }
1034   case ELF::R_390_PC32DBL:
1035   case ELF::R_390_PLT32DBL: {
1036     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
1037     assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
1038     writeInt32BE(LocalAddress, Delta / 2);
1039     break;
1040   }
1041   case ELF::R_390_PC32: {
1042     int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
1043     assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
1044     writeInt32BE(LocalAddress, Delta);
1045     break;
1046   }
1047   case ELF::R_390_64:
1048     writeInt64BE(LocalAddress, Value + Addend);
1049     break;
1050   }
1051 }
1052 
1053 // The target location for the relocation is described by RE.SectionID and
1054 // RE.Offset.  RE.SectionID can be used to find the SectionEntry.  Each
1055 // SectionEntry has three members describing its location.
1056 // SectionEntry::Address is the address at which the section has been loaded
1057 // into memory in the current (host) process.  SectionEntry::LoadAddress is the
1058 // address that the section will have in the target process.
1059 // SectionEntry::ObjAddress is the address of the bits for this section in the
1060 // original emitted object image (also in the current address space).
1061 //
1062 // Relocations will be applied as if the section were loaded at
1063 // SectionEntry::LoadAddress, but they will be applied at an address based
1064 // on SectionEntry::Address.  SectionEntry::ObjAddress will be used to refer to
1065 // Target memory contents if they are required for value calculations.
1066 //
1067 // The Value parameter here is the load address of the symbol for the
1068 // relocation to be applied.  For relocations which refer to symbols in the
1069 // current object Value will be the LoadAddress of the section in which
1070 // the symbol resides (RE.Addend provides additional information about the
1071 // symbol location).  For external symbols, Value will be the address of the
1072 // symbol in the target address space.
resolveRelocation(const RelocationEntry & RE,uint64_t Value)1073 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
1074                                        uint64_t Value) {
1075   const SectionEntry &Section = Sections[RE.SectionID];
1076   return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
1077                            RE.SymOffset, RE.SectionID);
1078 }
1079 
resolveRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend,uint64_t SymOffset,SID SectionID)1080 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
1081                                        uint64_t Offset, uint64_t Value,
1082                                        uint32_t Type, int64_t Addend,
1083                                        uint64_t SymOffset, SID SectionID) {
1084   switch (Arch) {
1085   case Triple::x86_64:
1086     resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
1087     break;
1088   case Triple::x86:
1089     resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
1090                          (uint32_t)(Addend & 0xffffffffL));
1091     break;
1092   case Triple::aarch64:
1093   case Triple::aarch64_be:
1094     resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
1095     break;
1096   case Triple::arm: // Fall through.
1097   case Triple::armeb:
1098   case Triple::thumb:
1099   case Triple::thumbeb:
1100     resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
1101                          (uint32_t)(Addend & 0xffffffffL));
1102     break;
1103   case Triple::mips: // Fall through.
1104   case Triple::mipsel:
1105   case Triple::mips64:
1106   case Triple::mips64el:
1107     if (IsMipsO32ABI)
1108       resolveMIPSRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL),
1109                             Type, (uint32_t)(Addend & 0xffffffffL));
1110     else if (IsMipsN64ABI)
1111       resolveMIPS64Relocation(Section, Offset, Value, Type, Addend, SymOffset,
1112                               SectionID);
1113     else
1114       llvm_unreachable("Mips ABI not handled");
1115     break;
1116   case Triple::ppc:
1117     resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
1118     break;
1119   case Triple::ppc64: // Fall through.
1120   case Triple::ppc64le:
1121     resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
1122     break;
1123   case Triple::systemz:
1124     resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
1125     break;
1126   default:
1127     llvm_unreachable("Unsupported CPU type!");
1128   }
1129 }
1130 
computePlaceholderAddress(unsigned SectionID,uint64_t Offset) const1131 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
1132   return (void *)(Sections[SectionID].getObjAddress() + Offset);
1133 }
1134 
processSimpleRelocation(unsigned SectionID,uint64_t Offset,unsigned RelType,RelocationValueRef Value)1135 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
1136   RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
1137   if (Value.SymbolName)
1138     addRelocationForSymbol(RE, Value.SymbolName);
1139   else
1140     addRelocationForSection(RE, Value.SectionID);
1141 }
1142 
getMatchingLoRelocation(uint32_t RelType,bool IsLocal) const1143 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
1144                                                  bool IsLocal) const {
1145   switch (RelType) {
1146   case ELF::R_MICROMIPS_GOT16:
1147     if (IsLocal)
1148       return ELF::R_MICROMIPS_LO16;
1149     break;
1150   case ELF::R_MICROMIPS_HI16:
1151     return ELF::R_MICROMIPS_LO16;
1152   case ELF::R_MIPS_GOT16:
1153     if (IsLocal)
1154       return ELF::R_MIPS_LO16;
1155     break;
1156   case ELF::R_MIPS_HI16:
1157     return ELF::R_MIPS_LO16;
1158   case ELF::R_MIPS_PCHI16:
1159     return ELF::R_MIPS_PCLO16;
1160   default:
1161     break;
1162   }
1163   return ELF::R_MIPS_NONE;
1164 }
1165 
processRelocationRef(unsigned SectionID,relocation_iterator RelI,const ObjectFile & O,ObjSectionToIDMap & ObjSectionToID,StubMap & Stubs)1166 relocation_iterator RuntimeDyldELF::processRelocationRef(
1167     unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1168     ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1169   const auto &Obj = cast<ELFObjectFileBase>(O);
1170   uint64_t RelType = RelI->getType();
1171   ErrorOr<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend();
1172   int64_t Addend = AddendOrErr ? *AddendOrErr : 0;
1173   elf_symbol_iterator Symbol = RelI->getSymbol();
1174 
1175   // Obtain the symbol name which is referenced in the relocation
1176   StringRef TargetName;
1177   if (Symbol != Obj.symbol_end()) {
1178     ErrorOr<StringRef> TargetNameOrErr = Symbol->getName();
1179     if (std::error_code EC = TargetNameOrErr.getError())
1180       report_fatal_error(EC.message());
1181     TargetName = *TargetNameOrErr;
1182   }
1183   DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1184                << " TargetName: " << TargetName << "\n");
1185   RelocationValueRef Value;
1186   // First search for the symbol in the local symbol table
1187   SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1188 
1189   // Search for the symbol in the global symbol table
1190   RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1191   if (Symbol != Obj.symbol_end()) {
1192     gsi = GlobalSymbolTable.find(TargetName.data());
1193     SymType = Symbol->getType();
1194   }
1195   if (gsi != GlobalSymbolTable.end()) {
1196     const auto &SymInfo = gsi->second;
1197     Value.SectionID = SymInfo.getSectionID();
1198     Value.Offset = SymInfo.getOffset();
1199     Value.Addend = SymInfo.getOffset() + Addend;
1200   } else {
1201     switch (SymType) {
1202     case SymbolRef::ST_Debug: {
1203       // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1204       // and can be changed by another developers. Maybe best way is add
1205       // a new symbol type ST_Section to SymbolRef and use it.
1206       section_iterator si = *Symbol->getSection();
1207       if (si == Obj.section_end())
1208         llvm_unreachable("Symbol section not found, bad object file format!");
1209       DEBUG(dbgs() << "\t\tThis is section symbol\n");
1210       bool isCode = si->isText();
1211       Value.SectionID = findOrEmitSection(Obj, (*si), isCode, ObjSectionToID);
1212       Value.Addend = Addend;
1213       break;
1214     }
1215     case SymbolRef::ST_Data:
1216     case SymbolRef::ST_Unknown: {
1217       Value.SymbolName = TargetName.data();
1218       Value.Addend = Addend;
1219 
1220       // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1221       // will manifest here as a NULL symbol name.
1222       // We can set this as a valid (but empty) symbol name, and rely
1223       // on addRelocationForSymbol to handle this.
1224       if (!Value.SymbolName)
1225         Value.SymbolName = "";
1226       break;
1227     }
1228     default:
1229       llvm_unreachable("Unresolved symbol type!");
1230       break;
1231     }
1232   }
1233 
1234   uint64_t Offset = RelI->getOffset();
1235 
1236   DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1237                << "\n");
1238   if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be) &&
1239       (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26)) {
1240     // This is an AArch64 branch relocation, need to use a stub function.
1241     DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1242     SectionEntry &Section = Sections[SectionID];
1243 
1244     // Look for an existing stub.
1245     StubMap::const_iterator i = Stubs.find(Value);
1246     if (i != Stubs.end()) {
1247       resolveRelocation(Section, Offset,
1248                         (uint64_t)Section.getAddressWithOffset(i->second),
1249                         RelType, 0);
1250       DEBUG(dbgs() << " Stub function found\n");
1251     } else {
1252       // Create a new stub function.
1253       DEBUG(dbgs() << " Create a new stub function\n");
1254       Stubs[Value] = Section.getStubOffset();
1255       uint8_t *StubTargetAddr = createStubFunction(
1256           Section.getAddressWithOffset(Section.getStubOffset()));
1257 
1258       RelocationEntry REmovz_g3(SectionID,
1259                                 StubTargetAddr - Section.getAddress(),
1260                                 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1261       RelocationEntry REmovk_g2(SectionID, StubTargetAddr -
1262                                                Section.getAddress() + 4,
1263                                 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1264       RelocationEntry REmovk_g1(SectionID, StubTargetAddr -
1265                                                Section.getAddress() + 8,
1266                                 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1267       RelocationEntry REmovk_g0(SectionID, StubTargetAddr -
1268                                                Section.getAddress() + 12,
1269                                 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1270 
1271       if (Value.SymbolName) {
1272         addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1273         addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1274         addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1275         addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1276       } else {
1277         addRelocationForSection(REmovz_g3, Value.SectionID);
1278         addRelocationForSection(REmovk_g2, Value.SectionID);
1279         addRelocationForSection(REmovk_g1, Value.SectionID);
1280         addRelocationForSection(REmovk_g0, Value.SectionID);
1281       }
1282       resolveRelocation(Section, Offset,
1283                         reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
1284                             Section.getStubOffset())),
1285                         RelType, 0);
1286       Section.advanceStubOffset(getMaxStubSize());
1287     }
1288   } else if (Arch == Triple::arm) {
1289     if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1290       RelType == ELF::R_ARM_JUMP24) {
1291       // This is an ARM branch relocation, need to use a stub function.
1292       DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.");
1293       SectionEntry &Section = Sections[SectionID];
1294 
1295       // Look for an existing stub.
1296       StubMap::const_iterator i = Stubs.find(Value);
1297       if (i != Stubs.end()) {
1298         resolveRelocation(
1299             Section, Offset,
1300             reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
1301             RelType, 0);
1302         DEBUG(dbgs() << " Stub function found\n");
1303       } else {
1304         // Create a new stub function.
1305         DEBUG(dbgs() << " Create a new stub function\n");
1306         Stubs[Value] = Section.getStubOffset();
1307         uint8_t *StubTargetAddr = createStubFunction(
1308             Section.getAddressWithOffset(Section.getStubOffset()));
1309         RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1310                            ELF::R_ARM_ABS32, Value.Addend);
1311         if (Value.SymbolName)
1312           addRelocationForSymbol(RE, Value.SymbolName);
1313         else
1314           addRelocationForSection(RE, Value.SectionID);
1315 
1316         resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1317                                                Section.getAddressWithOffset(
1318                                                    Section.getStubOffset())),
1319                           RelType, 0);
1320         Section.advanceStubOffset(getMaxStubSize());
1321       }
1322     } else {
1323       uint32_t *Placeholder =
1324         reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1325       if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1326           RelType == ELF::R_ARM_ABS32) {
1327         Value.Addend += *Placeholder;
1328       } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1329         // See ELF for ARM documentation
1330         Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1331       }
1332       processSimpleRelocation(SectionID, Offset, RelType, Value);
1333     }
1334   } else if (IsMipsO32ABI) {
1335     uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1336         computePlaceholderAddress(SectionID, Offset));
1337     uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1338     if (RelType == ELF::R_MIPS_26) {
1339       // This is an Mips branch relocation, need to use a stub function.
1340       DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1341       SectionEntry &Section = Sections[SectionID];
1342 
1343       // Extract the addend from the instruction.
1344       // We shift up by two since the Value will be down shifted again
1345       // when applying the relocation.
1346       uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1347 
1348       Value.Addend += Addend;
1349 
1350       //  Look up for existing stub.
1351       StubMap::const_iterator i = Stubs.find(Value);
1352       if (i != Stubs.end()) {
1353         RelocationEntry RE(SectionID, Offset, RelType, i->second);
1354         addRelocationForSection(RE, SectionID);
1355         DEBUG(dbgs() << " Stub function found\n");
1356       } else {
1357         // Create a new stub function.
1358         DEBUG(dbgs() << " Create a new stub function\n");
1359         Stubs[Value] = Section.getStubOffset();
1360         uint8_t *StubTargetAddr = createStubFunction(
1361             Section.getAddressWithOffset(Section.getStubOffset()));
1362 
1363         // Creating Hi and Lo relocations for the filled stub instructions.
1364         RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1365                              ELF::R_MIPS_HI16, Value.Addend);
1366         RelocationEntry RELo(SectionID,
1367                              StubTargetAddr - Section.getAddress() + 4,
1368                              ELF::R_MIPS_LO16, Value.Addend);
1369 
1370         if (Value.SymbolName) {
1371           addRelocationForSymbol(REHi, Value.SymbolName);
1372           addRelocationForSymbol(RELo, Value.SymbolName);
1373         }
1374         else {
1375           addRelocationForSection(REHi, Value.SectionID);
1376           addRelocationForSection(RELo, Value.SectionID);
1377         }
1378 
1379         RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1380         addRelocationForSection(RE, SectionID);
1381         Section.advanceStubOffset(getMaxStubSize());
1382       }
1383     } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
1384       int64_t Addend = (Opcode & 0x0000ffff) << 16;
1385       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1386       PendingRelocs.push_back(std::make_pair(Value, RE));
1387     } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
1388       int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
1389       for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
1390         const RelocationValueRef &MatchingValue = I->first;
1391         RelocationEntry &Reloc = I->second;
1392         if (MatchingValue == Value &&
1393             RelType == getMatchingLoRelocation(Reloc.RelType) &&
1394             SectionID == Reloc.SectionID) {
1395           Reloc.Addend += Addend;
1396           if (Value.SymbolName)
1397             addRelocationForSymbol(Reloc, Value.SymbolName);
1398           else
1399             addRelocationForSection(Reloc, Value.SectionID);
1400           I = PendingRelocs.erase(I);
1401         } else
1402           ++I;
1403       }
1404       RelocationEntry RE(SectionID, Offset, RelType, Addend);
1405       if (Value.SymbolName)
1406         addRelocationForSymbol(RE, Value.SymbolName);
1407       else
1408         addRelocationForSection(RE, Value.SectionID);
1409     } else {
1410       if (RelType == ELF::R_MIPS_32)
1411         Value.Addend += Opcode;
1412       else if (RelType == ELF::R_MIPS_PC16)
1413         Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1414       else if (RelType == ELF::R_MIPS_PC19_S2)
1415         Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1416       else if (RelType == ELF::R_MIPS_PC21_S2)
1417         Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1418       else if (RelType == ELF::R_MIPS_PC26_S2)
1419         Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1420       processSimpleRelocation(SectionID, Offset, RelType, Value);
1421     }
1422   } else if (IsMipsN64ABI) {
1423     uint32_t r_type = RelType & 0xff;
1424     RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1425     if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1426         || r_type == ELF::R_MIPS_GOT_DISP) {
1427       StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1428       if (i != GOTSymbolOffsets.end())
1429         RE.SymOffset = i->second;
1430       else {
1431         RE.SymOffset = allocateGOTEntries(SectionID, 1);
1432         GOTSymbolOffsets[TargetName] = RE.SymOffset;
1433       }
1434     }
1435     if (Value.SymbolName)
1436       addRelocationForSymbol(RE, Value.SymbolName);
1437     else
1438       addRelocationForSection(RE, Value.SectionID);
1439   } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1440     if (RelType == ELF::R_PPC64_REL24) {
1441       // Determine ABI variant in use for this object.
1442       unsigned AbiVariant;
1443       Obj.getPlatformFlags(AbiVariant);
1444       AbiVariant &= ELF::EF_PPC64_ABI;
1445       // A PPC branch relocation will need a stub function if the target is
1446       // an external symbol (Symbol::ST_Unknown) or if the target address
1447       // is not within the signed 24-bits branch address.
1448       SectionEntry &Section = Sections[SectionID];
1449       uint8_t *Target = Section.getAddressWithOffset(Offset);
1450       bool RangeOverflow = false;
1451       if (SymType != SymbolRef::ST_Unknown) {
1452         if (AbiVariant != 2) {
1453           // In the ELFv1 ABI, a function call may point to the .opd entry,
1454           // so the final symbol value is calculated based on the relocation
1455           // values in the .opd section.
1456           findOPDEntrySection(Obj, ObjSectionToID, Value);
1457         } else {
1458           // In the ELFv2 ABI, a function symbol may provide a local entry
1459           // point, which must be used for direct calls.
1460           uint8_t SymOther = Symbol->getOther();
1461           Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1462         }
1463         uint8_t *RelocTarget =
1464             Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
1465         int32_t delta = static_cast<int32_t>(Target - RelocTarget);
1466         // If it is within 26-bits branch range, just set the branch target
1467         if (SignExtend32<26>(delta) == delta) {
1468           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1469           if (Value.SymbolName)
1470             addRelocationForSymbol(RE, Value.SymbolName);
1471           else
1472             addRelocationForSection(RE, Value.SectionID);
1473         } else {
1474           RangeOverflow = true;
1475         }
1476       }
1477       if (SymType == SymbolRef::ST_Unknown || RangeOverflow) {
1478         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
1479         // larger than 24-bits.
1480         StubMap::const_iterator i = Stubs.find(Value);
1481         if (i != Stubs.end()) {
1482           // Symbol function stub already created, just relocate to it
1483           resolveRelocation(Section, Offset,
1484                             reinterpret_cast<uint64_t>(
1485                                 Section.getAddressWithOffset(i->second)),
1486                             RelType, 0);
1487           DEBUG(dbgs() << " Stub function found\n");
1488         } else {
1489           // Create a new stub function.
1490           DEBUG(dbgs() << " Create a new stub function\n");
1491           Stubs[Value] = Section.getStubOffset();
1492           uint8_t *StubTargetAddr = createStubFunction(
1493               Section.getAddressWithOffset(Section.getStubOffset()),
1494               AbiVariant);
1495           RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1496                              ELF::R_PPC64_ADDR64, Value.Addend);
1497 
1498           // Generates the 64-bits address loads as exemplified in section
1499           // 4.5.1 in PPC64 ELF ABI.  Note that the relocations need to
1500           // apply to the low part of the instructions, so we have to update
1501           // the offset according to the target endianness.
1502           uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
1503           if (!IsTargetLittleEndian)
1504             StubRelocOffset += 2;
1505 
1506           RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1507                                 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1508           RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1509                                ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1510           RelocationEntry REh(SectionID, StubRelocOffset + 12,
1511                               ELF::R_PPC64_ADDR16_HI, Value.Addend);
1512           RelocationEntry REl(SectionID, StubRelocOffset + 16,
1513                               ELF::R_PPC64_ADDR16_LO, Value.Addend);
1514 
1515           if (Value.SymbolName) {
1516             addRelocationForSymbol(REhst, Value.SymbolName);
1517             addRelocationForSymbol(REhr, Value.SymbolName);
1518             addRelocationForSymbol(REh, Value.SymbolName);
1519             addRelocationForSymbol(REl, Value.SymbolName);
1520           } else {
1521             addRelocationForSection(REhst, Value.SectionID);
1522             addRelocationForSection(REhr, Value.SectionID);
1523             addRelocationForSection(REh, Value.SectionID);
1524             addRelocationForSection(REl, Value.SectionID);
1525           }
1526 
1527           resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1528                                                  Section.getAddressWithOffset(
1529                                                      Section.getStubOffset())),
1530                             RelType, 0);
1531           Section.advanceStubOffset(getMaxStubSize());
1532         }
1533         if (SymType == SymbolRef::ST_Unknown) {
1534           // Restore the TOC for external calls
1535           if (AbiVariant == 2)
1536             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)
1537           else
1538             writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1539         }
1540       }
1541     } else if (RelType == ELF::R_PPC64_TOC16 ||
1542                RelType == ELF::R_PPC64_TOC16_DS ||
1543                RelType == ELF::R_PPC64_TOC16_LO ||
1544                RelType == ELF::R_PPC64_TOC16_LO_DS ||
1545                RelType == ELF::R_PPC64_TOC16_HI ||
1546                RelType == ELF::R_PPC64_TOC16_HA) {
1547       // These relocations are supposed to subtract the TOC address from
1548       // the final value.  This does not fit cleanly into the RuntimeDyld
1549       // scheme, since there may be *two* sections involved in determining
1550       // the relocation value (the section of the symbol referred to by the
1551       // relocation, and the TOC section associated with the current module).
1552       //
1553       // Fortunately, these relocations are currently only ever generated
1554       // referring to symbols that themselves reside in the TOC, which means
1555       // that the two sections are actually the same.  Thus they cancel out
1556       // and we can immediately resolve the relocation right now.
1557       switch (RelType) {
1558       case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1559       case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1560       case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1561       case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1562       case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1563       case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1564       default: llvm_unreachable("Wrong relocation type.");
1565       }
1566 
1567       RelocationValueRef TOCValue;
1568       findPPC64TOCSection(Obj, ObjSectionToID, TOCValue);
1569       if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1570         llvm_unreachable("Unsupported TOC relocation.");
1571       Value.Addend -= TOCValue.Addend;
1572       resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1573     } else {
1574       // There are two ways to refer to the TOC address directly: either
1575       // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1576       // ignored), or via any relocation that refers to the magic ".TOC."
1577       // symbols (in which case the addend is respected).
1578       if (RelType == ELF::R_PPC64_TOC) {
1579         RelType = ELF::R_PPC64_ADDR64;
1580         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1581       } else if (TargetName == ".TOC.") {
1582         findPPC64TOCSection(Obj, ObjSectionToID, Value);
1583         Value.Addend += Addend;
1584       }
1585 
1586       RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1587 
1588       if (Value.SymbolName)
1589         addRelocationForSymbol(RE, Value.SymbolName);
1590       else
1591         addRelocationForSection(RE, Value.SectionID);
1592     }
1593   } else if (Arch == Triple::systemz &&
1594              (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1595     // Create function stubs for both PLT and GOT references, regardless of
1596     // whether the GOT reference is to data or code.  The stub contains the
1597     // full address of the symbol, as needed by GOT references, and the
1598     // executable part only adds an overhead of 8 bytes.
1599     //
1600     // We could try to conserve space by allocating the code and data
1601     // parts of the stub separately.  However, as things stand, we allocate
1602     // a stub for every relocation, so using a GOT in JIT code should be
1603     // no less space efficient than using an explicit constant pool.
1604     DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1605     SectionEntry &Section = Sections[SectionID];
1606 
1607     // Look for an existing stub.
1608     StubMap::const_iterator i = Stubs.find(Value);
1609     uintptr_t StubAddress;
1610     if (i != Stubs.end()) {
1611       StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
1612       DEBUG(dbgs() << " Stub function found\n");
1613     } else {
1614       // Create a new stub function.
1615       DEBUG(dbgs() << " Create a new stub function\n");
1616 
1617       uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1618       uintptr_t StubAlignment = getStubAlignment();
1619       StubAddress =
1620           (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1621           -StubAlignment;
1622       unsigned StubOffset = StubAddress - BaseAddress;
1623 
1624       Stubs[Value] = StubOffset;
1625       createStubFunction((uint8_t *)StubAddress);
1626       RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1627                          Value.Offset);
1628       if (Value.SymbolName)
1629         addRelocationForSymbol(RE, Value.SymbolName);
1630       else
1631         addRelocationForSection(RE, Value.SectionID);
1632       Section.advanceStubOffset(getMaxStubSize());
1633     }
1634 
1635     if (RelType == ELF::R_390_GOTENT)
1636       resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1637                         Addend);
1638     else
1639       resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1640   } else if (Arch == Triple::x86_64) {
1641     if (RelType == ELF::R_X86_64_PLT32) {
1642       // The way the PLT relocations normally work is that the linker allocates
1643       // the
1644       // PLT and this relocation makes a PC-relative call into the PLT.  The PLT
1645       // entry will then jump to an address provided by the GOT.  On first call,
1646       // the
1647       // GOT address will point back into PLT code that resolves the symbol. After
1648       // the first call, the GOT entry points to the actual function.
1649       //
1650       // For local functions we're ignoring all of that here and just replacing
1651       // the PLT32 relocation type with PC32, which will translate the relocation
1652       // into a PC-relative call directly to the function. For external symbols we
1653       // can't be sure the function will be within 2^32 bytes of the call site, so
1654       // we need to create a stub, which calls into the GOT.  This case is
1655       // equivalent to the usual PLT implementation except that we use the stub
1656       // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1657       // rather than allocating a PLT section.
1658       if (Value.SymbolName) {
1659         // This is a call to an external function.
1660         // Look for an existing stub.
1661         SectionEntry &Section = Sections[SectionID];
1662         StubMap::const_iterator i = Stubs.find(Value);
1663         uintptr_t StubAddress;
1664         if (i != Stubs.end()) {
1665           StubAddress = uintptr_t(Section.getAddress()) + i->second;
1666           DEBUG(dbgs() << " Stub function found\n");
1667         } else {
1668           // Create a new stub function (equivalent to a PLT entry).
1669           DEBUG(dbgs() << " Create a new stub function\n");
1670 
1671           uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1672           uintptr_t StubAlignment = getStubAlignment();
1673           StubAddress =
1674               (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1675               -StubAlignment;
1676           unsigned StubOffset = StubAddress - BaseAddress;
1677           Stubs[Value] = StubOffset;
1678           createStubFunction((uint8_t *)StubAddress);
1679 
1680           // Bump our stub offset counter
1681           Section.advanceStubOffset(getMaxStubSize());
1682 
1683           // Allocate a GOT Entry
1684           uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1685 
1686           // The load of the GOT address has an addend of -4
1687           resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4);
1688 
1689           // Fill in the value of the symbol we're targeting into the GOT
1690           addRelocationForSymbol(
1691               computeGOTOffsetRE(SectionID, GOTOffset, 0, ELF::R_X86_64_64),
1692               Value.SymbolName);
1693         }
1694 
1695         // Make the target call a call into the stub table.
1696         resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1697                           Addend);
1698       } else {
1699         RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1700                   Value.Offset);
1701         addRelocationForSection(RE, Value.SectionID);
1702       }
1703     } else if (RelType == ELF::R_X86_64_GOTPCREL) {
1704       uint64_t GOTOffset = allocateGOTEntries(SectionID, 1);
1705       resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend);
1706 
1707       // Fill in the value of the symbol we're targeting into the GOT
1708       RelocationEntry RE = computeGOTOffsetRE(SectionID, GOTOffset, Value.Offset, ELF::R_X86_64_64);
1709       if (Value.SymbolName)
1710         addRelocationForSymbol(RE, Value.SymbolName);
1711       else
1712         addRelocationForSection(RE, Value.SectionID);
1713     } else if (RelType == ELF::R_X86_64_PC32) {
1714       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1715       processSimpleRelocation(SectionID, Offset, RelType, Value);
1716     } else if (RelType == ELF::R_X86_64_PC64) {
1717       Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1718       processSimpleRelocation(SectionID, Offset, RelType, Value);
1719     } else {
1720       processSimpleRelocation(SectionID, Offset, RelType, Value);
1721     }
1722   } else {
1723     if (Arch == Triple::x86) {
1724       Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1725     }
1726     processSimpleRelocation(SectionID, Offset, RelType, Value);
1727   }
1728   return ++RelI;
1729 }
1730 
getGOTEntrySize()1731 size_t RuntimeDyldELF::getGOTEntrySize() {
1732   // We don't use the GOT in all of these cases, but it's essentially free
1733   // to put them all here.
1734   size_t Result = 0;
1735   switch (Arch) {
1736   case Triple::x86_64:
1737   case Triple::aarch64:
1738   case Triple::aarch64_be:
1739   case Triple::ppc64:
1740   case Triple::ppc64le:
1741   case Triple::systemz:
1742     Result = sizeof(uint64_t);
1743     break;
1744   case Triple::x86:
1745   case Triple::arm:
1746   case Triple::thumb:
1747     Result = sizeof(uint32_t);
1748     break;
1749   case Triple::mips:
1750   case Triple::mipsel:
1751   case Triple::mips64:
1752   case Triple::mips64el:
1753     if (IsMipsO32ABI)
1754       Result = sizeof(uint32_t);
1755     else if (IsMipsN64ABI)
1756       Result = sizeof(uint64_t);
1757     else
1758       llvm_unreachable("Mips ABI not handled");
1759     break;
1760   default:
1761     llvm_unreachable("Unsupported CPU type!");
1762   }
1763   return Result;
1764 }
1765 
allocateGOTEntries(unsigned SectionID,unsigned no)1766 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned SectionID, unsigned no)
1767 {
1768   (void)SectionID; // The GOT Section is the same for all section in the object file
1769   if (GOTSectionID == 0) {
1770     GOTSectionID = Sections.size();
1771     // Reserve a section id. We'll allocate the section later
1772     // once we know the total size
1773     Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
1774   }
1775   uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1776   CurrentGOTIndex += no;
1777   return StartOffset;
1778 }
1779 
resolveGOTOffsetRelocation(unsigned SectionID,uint64_t Offset,uint64_t GOTOffset)1780 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset, uint64_t GOTOffset)
1781 {
1782   // Fill in the relative address of the GOT Entry into the stub
1783   RelocationEntry GOTRE(SectionID, Offset, ELF::R_X86_64_PC32, GOTOffset);
1784   addRelocationForSection(GOTRE, GOTSectionID);
1785 }
1786 
computeGOTOffsetRE(unsigned SectionID,uint64_t GOTOffset,uint64_t SymbolOffset,uint32_t Type)1787 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(unsigned SectionID, uint64_t GOTOffset, uint64_t SymbolOffset,
1788                                                    uint32_t Type)
1789 {
1790   (void)SectionID; // The GOT Section is the same for all section in the object file
1791   return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1792 }
1793 
finalizeLoad(const ObjectFile & Obj,ObjSectionToIDMap & SectionMap)1794 void RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1795                                   ObjSectionToIDMap &SectionMap) {
1796   if (IsMipsO32ABI)
1797     if (!PendingRelocs.empty())
1798       report_fatal_error("Can't find matching LO16 reloc");
1799 
1800   // If necessary, allocate the global offset table
1801   if (GOTSectionID != 0) {
1802     // Allocate memory for the section
1803     size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1804     uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1805                                                 GOTSectionID, ".got", false);
1806     if (!Addr)
1807       report_fatal_error("Unable to allocate memory for GOT!");
1808 
1809     Sections[GOTSectionID] =
1810         SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
1811 
1812     if (Checker)
1813       Checker->registerSection(Obj.getFileName(), GOTSectionID);
1814 
1815     // For now, initialize all GOT entries to zero.  We'll fill them in as
1816     // needed when GOT-based relocations are applied.
1817     memset(Addr, 0, TotalSize);
1818     if (IsMipsN64ABI) {
1819       // To correctly resolve Mips GOT relocations, we need a mapping from
1820       // object's sections to GOTs.
1821       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1822            SI != SE; ++SI) {
1823         if (SI->relocation_begin() != SI->relocation_end()) {
1824           section_iterator RelocatedSection = SI->getRelocatedSection();
1825           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1826           assert (i != SectionMap.end());
1827           SectionToGOTMap[i->second] = GOTSectionID;
1828         }
1829       }
1830       GOTSymbolOffsets.clear();
1831     }
1832   }
1833 
1834   // Look for and record the EH frame section.
1835   ObjSectionToIDMap::iterator i, e;
1836   for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1837     const SectionRef &Section = i->first;
1838     StringRef Name;
1839     Section.getName(Name);
1840     if (Name == ".eh_frame") {
1841       UnregisteredEHFrameSections.push_back(i->second);
1842       break;
1843     }
1844   }
1845 
1846   GOTSectionID = 0;
1847   CurrentGOTIndex = 0;
1848 }
1849 
isCompatibleFile(const object::ObjectFile & Obj) const1850 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1851   return Obj.isELF();
1852 }
1853 
relocationNeedsStub(const RelocationRef & R) const1854 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
1855   if (Arch != Triple::x86_64)
1856     return true;  // Conservative answer
1857 
1858   switch (R.getType()) {
1859   default:
1860     return true;  // Conservative answer
1861 
1862 
1863   case ELF::R_X86_64_GOTPCREL:
1864   case ELF::R_X86_64_PC32:
1865   case ELF::R_X86_64_PC64:
1866   case ELF::R_X86_64_64:
1867     // We know that these reloation types won't need a stub function.  This list
1868     // can be extended as needed.
1869     return false;
1870   }
1871 }
1872 
1873 } // namespace llvm
1874