1 //===-- RuntimeDyldELF.cpp - Run-time dynamic linker for MC-JIT -*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Implementation of ELF support for the MC-JIT runtime dynamic linker.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "RuntimeDyldELF.h"
14 #include "RuntimeDyldCheckerImpl.h"
15 #include "Targets/RuntimeDyldELFMips.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/ADT/Triple.h"
19 #include "llvm/BinaryFormat/ELF.h"
20 #include "llvm/Object/ELFObjectFile.h"
21 #include "llvm/Object/ObjectFile.h"
22 #include "llvm/Support/Endian.h"
23 #include "llvm/Support/MemoryBuffer.h"
24
25 using namespace llvm;
26 using namespace llvm::object;
27 using namespace llvm::support::endian;
28
29 #define DEBUG_TYPE "dyld"
30
or32le(void * P,int32_t V)31 static void or32le(void *P, int32_t V) { write32le(P, read32le(P) | V); }
32
or32AArch64Imm(void * L,uint64_t Imm)33 static void or32AArch64Imm(void *L, uint64_t Imm) {
34 or32le(L, (Imm & 0xFFF) << 10);
35 }
36
write(bool isBE,void * P,T V)37 template <class T> static void write(bool isBE, void *P, T V) {
38 isBE ? write<T, support::big>(P, V) : write<T, support::little>(P, V);
39 }
40
write32AArch64Addr(void * L,uint64_t Imm)41 static void write32AArch64Addr(void *L, uint64_t Imm) {
42 uint32_t ImmLo = (Imm & 0x3) << 29;
43 uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
44 uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
45 write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
46 }
47
48 // Return the bits [Start, End] from Val shifted Start bits.
49 // For instance, getBits(0xF0, 4, 8) returns 0xF.
getBits(uint64_t Val,int Start,int End)50 static uint64_t getBits(uint64_t Val, int Start, int End) {
51 uint64_t Mask = ((uint64_t)1 << (End + 1 - Start)) - 1;
52 return (Val >> Start) & Mask;
53 }
54
55 namespace {
56
57 template <class ELFT> class DyldELFObject : public ELFObjectFile<ELFT> {
58 LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
59
60 typedef Elf_Shdr_Impl<ELFT> Elf_Shdr;
61 typedef Elf_Sym_Impl<ELFT> Elf_Sym;
62 typedef Elf_Rel_Impl<ELFT, false> Elf_Rel;
63 typedef Elf_Rel_Impl<ELFT, true> Elf_Rela;
64
65 typedef Elf_Ehdr_Impl<ELFT> Elf_Ehdr;
66
67 typedef typename ELFT::uint addr_type;
68
69 DyldELFObject(ELFObjectFile<ELFT> &&Obj);
70
71 public:
72 static Expected<std::unique_ptr<DyldELFObject>>
73 create(MemoryBufferRef Wrapper);
74
75 void updateSectionAddress(const SectionRef &Sec, uint64_t Addr);
76
77 void updateSymbolAddress(const SymbolRef &SymRef, uint64_t Addr);
78
79 // Methods for type inquiry through isa, cast and dyn_cast
classof(const Binary * v)80 static bool classof(const Binary *v) {
81 return (isa<ELFObjectFile<ELFT>>(v) &&
82 classof(cast<ELFObjectFile<ELFT>>(v)));
83 }
classof(const ELFObjectFile<ELFT> * v)84 static bool classof(const ELFObjectFile<ELFT> *v) {
85 return v->isDyldType();
86 }
87 };
88
89
90
91 // The MemoryBuffer passed into this constructor is just a wrapper around the
92 // actual memory. Ultimately, the Binary parent class will take ownership of
93 // this MemoryBuffer object but not the underlying memory.
94 template <class ELFT>
DyldELFObject(ELFObjectFile<ELFT> && Obj)95 DyldELFObject<ELFT>::DyldELFObject(ELFObjectFile<ELFT> &&Obj)
96 : ELFObjectFile<ELFT>(std::move(Obj)) {
97 this->isDyldELFObject = true;
98 }
99
100 template <class ELFT>
101 Expected<std::unique_ptr<DyldELFObject<ELFT>>>
create(MemoryBufferRef Wrapper)102 DyldELFObject<ELFT>::create(MemoryBufferRef Wrapper) {
103 auto Obj = ELFObjectFile<ELFT>::create(Wrapper);
104 if (auto E = Obj.takeError())
105 return std::move(E);
106 std::unique_ptr<DyldELFObject<ELFT>> Ret(
107 new DyldELFObject<ELFT>(std::move(*Obj)));
108 return std::move(Ret);
109 }
110
111 template <class ELFT>
updateSectionAddress(const SectionRef & Sec,uint64_t Addr)112 void DyldELFObject<ELFT>::updateSectionAddress(const SectionRef &Sec,
113 uint64_t Addr) {
114 DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
115 Elf_Shdr *shdr =
116 const_cast<Elf_Shdr *>(reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
117
118 // This assumes the address passed in matches the target address bitness
119 // The template-based type cast handles everything else.
120 shdr->sh_addr = static_cast<addr_type>(Addr);
121 }
122
123 template <class ELFT>
updateSymbolAddress(const SymbolRef & SymRef,uint64_t Addr)124 void DyldELFObject<ELFT>::updateSymbolAddress(const SymbolRef &SymRef,
125 uint64_t Addr) {
126
127 Elf_Sym *sym = const_cast<Elf_Sym *>(
128 ELFObjectFile<ELFT>::getSymbol(SymRef.getRawDataRefImpl()));
129
130 // This assumes the address passed in matches the target address bitness
131 // The template-based type cast handles everything else.
132 sym->st_value = static_cast<addr_type>(Addr);
133 }
134
135 class LoadedELFObjectInfo final
136 : public LoadedObjectInfoHelper<LoadedELFObjectInfo,
137 RuntimeDyld::LoadedObjectInfo> {
138 public:
LoadedELFObjectInfo(RuntimeDyldImpl & RTDyld,ObjSectionToIDMap ObjSecToIDMap)139 LoadedELFObjectInfo(RuntimeDyldImpl &RTDyld, ObjSectionToIDMap ObjSecToIDMap)
140 : LoadedObjectInfoHelper(RTDyld, std::move(ObjSecToIDMap)) {}
141
142 OwningBinary<ObjectFile>
143 getObjectForDebug(const ObjectFile &Obj) const override;
144 };
145
146 template <typename ELFT>
147 static Expected<std::unique_ptr<DyldELFObject<ELFT>>>
createRTDyldELFObject(MemoryBufferRef Buffer,const ObjectFile & SourceObject,const LoadedELFObjectInfo & L)148 createRTDyldELFObject(MemoryBufferRef Buffer, const ObjectFile &SourceObject,
149 const LoadedELFObjectInfo &L) {
150 typedef typename ELFT::Shdr Elf_Shdr;
151 typedef typename ELFT::uint addr_type;
152
153 Expected<std::unique_ptr<DyldELFObject<ELFT>>> ObjOrErr =
154 DyldELFObject<ELFT>::create(Buffer);
155 if (Error E = ObjOrErr.takeError())
156 return std::move(E);
157
158 std::unique_ptr<DyldELFObject<ELFT>> Obj = std::move(*ObjOrErr);
159
160 // Iterate over all sections in the object.
161 auto SI = SourceObject.section_begin();
162 for (const auto &Sec : Obj->sections()) {
163 Expected<StringRef> NameOrErr = Sec.getName();
164 if (!NameOrErr) {
165 consumeError(NameOrErr.takeError());
166 continue;
167 }
168
169 if (*NameOrErr != "") {
170 DataRefImpl ShdrRef = Sec.getRawDataRefImpl();
171 Elf_Shdr *shdr = const_cast<Elf_Shdr *>(
172 reinterpret_cast<const Elf_Shdr *>(ShdrRef.p));
173
174 if (uint64_t SecLoadAddr = L.getSectionLoadAddress(*SI)) {
175 // This assumes that the address passed in matches the target address
176 // bitness. The template-based type cast handles everything else.
177 shdr->sh_addr = static_cast<addr_type>(SecLoadAddr);
178 }
179 }
180 ++SI;
181 }
182
183 return std::move(Obj);
184 }
185
186 static OwningBinary<ObjectFile>
createELFDebugObject(const ObjectFile & Obj,const LoadedELFObjectInfo & L)187 createELFDebugObject(const ObjectFile &Obj, const LoadedELFObjectInfo &L) {
188 assert(Obj.isELF() && "Not an ELF object file.");
189
190 std::unique_ptr<MemoryBuffer> Buffer =
191 MemoryBuffer::getMemBufferCopy(Obj.getData(), Obj.getFileName());
192
193 Expected<std::unique_ptr<ObjectFile>> DebugObj(nullptr);
194 handleAllErrors(DebugObj.takeError());
195 if (Obj.getBytesInAddress() == 4 && Obj.isLittleEndian())
196 DebugObj =
197 createRTDyldELFObject<ELF32LE>(Buffer->getMemBufferRef(), Obj, L);
198 else if (Obj.getBytesInAddress() == 4 && !Obj.isLittleEndian())
199 DebugObj =
200 createRTDyldELFObject<ELF32BE>(Buffer->getMemBufferRef(), Obj, L);
201 else if (Obj.getBytesInAddress() == 8 && !Obj.isLittleEndian())
202 DebugObj =
203 createRTDyldELFObject<ELF64BE>(Buffer->getMemBufferRef(), Obj, L);
204 else if (Obj.getBytesInAddress() == 8 && Obj.isLittleEndian())
205 DebugObj =
206 createRTDyldELFObject<ELF64LE>(Buffer->getMemBufferRef(), Obj, L);
207 else
208 llvm_unreachable("Unexpected ELF format");
209
210 handleAllErrors(DebugObj.takeError());
211 return OwningBinary<ObjectFile>(std::move(*DebugObj), std::move(Buffer));
212 }
213
214 OwningBinary<ObjectFile>
getObjectForDebug(const ObjectFile & Obj) const215 LoadedELFObjectInfo::getObjectForDebug(const ObjectFile &Obj) const {
216 return createELFDebugObject(Obj, *this);
217 }
218
219 } // anonymous namespace
220
221 namespace llvm {
222
RuntimeDyldELF(RuntimeDyld::MemoryManager & MemMgr,JITSymbolResolver & Resolver)223 RuntimeDyldELF::RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
224 JITSymbolResolver &Resolver)
225 : RuntimeDyldImpl(MemMgr, Resolver), GOTSectionID(0), CurrentGOTIndex(0) {}
~RuntimeDyldELF()226 RuntimeDyldELF::~RuntimeDyldELF() {}
227
registerEHFrames()228 void RuntimeDyldELF::registerEHFrames() {
229 for (int i = 0, e = UnregisteredEHFrameSections.size(); i != e; ++i) {
230 SID EHFrameSID = UnregisteredEHFrameSections[i];
231 uint8_t *EHFrameAddr = Sections[EHFrameSID].getAddress();
232 uint64_t EHFrameLoadAddr = Sections[EHFrameSID].getLoadAddress();
233 size_t EHFrameSize = Sections[EHFrameSID].getSize();
234 MemMgr.registerEHFrames(EHFrameAddr, EHFrameLoadAddr, EHFrameSize);
235 }
236 UnregisteredEHFrameSections.clear();
237 }
238
239 std::unique_ptr<RuntimeDyldELF>
create(Triple::ArchType Arch,RuntimeDyld::MemoryManager & MemMgr,JITSymbolResolver & Resolver)240 llvm::RuntimeDyldELF::create(Triple::ArchType Arch,
241 RuntimeDyld::MemoryManager &MemMgr,
242 JITSymbolResolver &Resolver) {
243 switch (Arch) {
244 default:
245 return std::make_unique<RuntimeDyldELF>(MemMgr, Resolver);
246 case Triple::mips:
247 case Triple::mipsel:
248 case Triple::mips64:
249 case Triple::mips64el:
250 return std::make_unique<RuntimeDyldELFMips>(MemMgr, Resolver);
251 }
252 }
253
254 std::unique_ptr<RuntimeDyld::LoadedObjectInfo>
loadObject(const object::ObjectFile & O)255 RuntimeDyldELF::loadObject(const object::ObjectFile &O) {
256 if (auto ObjSectionToIDOrErr = loadObjectImpl(O))
257 return std::make_unique<LoadedELFObjectInfo>(*this, *ObjSectionToIDOrErr);
258 else {
259 HasError = true;
260 raw_string_ostream ErrStream(ErrorStr);
261 logAllUnhandledErrors(ObjSectionToIDOrErr.takeError(), ErrStream);
262 return nullptr;
263 }
264 }
265
resolveX86_64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend,uint64_t SymOffset)266 void RuntimeDyldELF::resolveX86_64Relocation(const SectionEntry &Section,
267 uint64_t Offset, uint64_t Value,
268 uint32_t Type, int64_t Addend,
269 uint64_t SymOffset) {
270 switch (Type) {
271 default:
272 llvm_unreachable("Relocation type not implemented yet!");
273 break;
274 case ELF::R_X86_64_NONE:
275 break;
276 case ELF::R_X86_64_64: {
277 support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
278 Value + Addend;
279 LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
280 << format("%p\n", Section.getAddressWithOffset(Offset)));
281 break;
282 }
283 case ELF::R_X86_64_32:
284 case ELF::R_X86_64_32S: {
285 Value += Addend;
286 assert((Type == ELF::R_X86_64_32 && (Value <= UINT32_MAX)) ||
287 (Type == ELF::R_X86_64_32S &&
288 ((int64_t)Value <= INT32_MAX && (int64_t)Value >= INT32_MIN)));
289 uint32_t TruncatedAddr = (Value & 0xFFFFFFFF);
290 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
291 TruncatedAddr;
292 LLVM_DEBUG(dbgs() << "Writing " << format("%p", TruncatedAddr) << " at "
293 << format("%p\n", Section.getAddressWithOffset(Offset)));
294 break;
295 }
296 case ELF::R_X86_64_PC8: {
297 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
298 int64_t RealOffset = Value + Addend - FinalAddress;
299 assert(isInt<8>(RealOffset));
300 int8_t TruncOffset = (RealOffset & 0xFF);
301 Section.getAddress()[Offset] = TruncOffset;
302 break;
303 }
304 case ELF::R_X86_64_PC32: {
305 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
306 int64_t RealOffset = Value + Addend - FinalAddress;
307 assert(isInt<32>(RealOffset));
308 int32_t TruncOffset = (RealOffset & 0xFFFFFFFF);
309 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
310 TruncOffset;
311 break;
312 }
313 case ELF::R_X86_64_PC64: {
314 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
315 int64_t RealOffset = Value + Addend - FinalAddress;
316 support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) =
317 RealOffset;
318 LLVM_DEBUG(dbgs() << "Writing " << format("%p", RealOffset) << " at "
319 << format("%p\n", FinalAddress));
320 break;
321 }
322 case ELF::R_X86_64_GOTOFF64: {
323 // Compute Value - GOTBase.
324 uint64_t GOTBase = 0;
325 for (const auto &Section : Sections) {
326 if (Section.getName() == ".got") {
327 GOTBase = Section.getLoadAddressWithOffset(0);
328 break;
329 }
330 }
331 assert(GOTBase != 0 && "missing GOT");
332 int64_t GOTOffset = Value - GOTBase + Addend;
333 support::ulittle64_t::ref(Section.getAddressWithOffset(Offset)) = GOTOffset;
334 break;
335 }
336 }
337 }
338
resolveX86Relocation(const SectionEntry & Section,uint64_t Offset,uint32_t Value,uint32_t Type,int32_t Addend)339 void RuntimeDyldELF::resolveX86Relocation(const SectionEntry &Section,
340 uint64_t Offset, uint32_t Value,
341 uint32_t Type, int32_t Addend) {
342 switch (Type) {
343 case ELF::R_386_32: {
344 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
345 Value + Addend;
346 break;
347 }
348 // Handle R_386_PLT32 like R_386_PC32 since it should be able to
349 // reach any 32 bit address.
350 case ELF::R_386_PLT32:
351 case ELF::R_386_PC32: {
352 uint32_t FinalAddress =
353 Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
354 uint32_t RealOffset = Value + Addend - FinalAddress;
355 support::ulittle32_t::ref(Section.getAddressWithOffset(Offset)) =
356 RealOffset;
357 break;
358 }
359 default:
360 // There are other relocation types, but it appears these are the
361 // only ones currently used by the LLVM ELF object writer
362 llvm_unreachable("Relocation type not implemented yet!");
363 break;
364 }
365 }
366
resolveAArch64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)367 void RuntimeDyldELF::resolveAArch64Relocation(const SectionEntry &Section,
368 uint64_t Offset, uint64_t Value,
369 uint32_t Type, int64_t Addend) {
370 uint32_t *TargetPtr =
371 reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
372 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
373 // Data should use target endian. Code should always use little endian.
374 bool isBE = Arch == Triple::aarch64_be;
375
376 LLVM_DEBUG(dbgs() << "resolveAArch64Relocation, LocalAddress: 0x"
377 << format("%llx", Section.getAddressWithOffset(Offset))
378 << " FinalAddress: 0x" << format("%llx", FinalAddress)
379 << " Value: 0x" << format("%llx", Value) << " Type: 0x"
380 << format("%x", Type) << " Addend: 0x"
381 << format("%llx", Addend) << "\n");
382
383 switch (Type) {
384 default:
385 llvm_unreachable("Relocation type not implemented yet!");
386 break;
387 case ELF::R_AARCH64_ABS16: {
388 uint64_t Result = Value + Addend;
389 assert(static_cast<int64_t>(Result) >= INT16_MIN && Result < UINT16_MAX);
390 write(isBE, TargetPtr, static_cast<uint16_t>(Result & 0xffffU));
391 break;
392 }
393 case ELF::R_AARCH64_ABS32: {
394 uint64_t Result = Value + Addend;
395 assert(static_cast<int64_t>(Result) >= INT32_MIN && Result < UINT32_MAX);
396 write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
397 break;
398 }
399 case ELF::R_AARCH64_ABS64:
400 write(isBE, TargetPtr, Value + Addend);
401 break;
402 case ELF::R_AARCH64_PREL32: {
403 uint64_t Result = Value + Addend - FinalAddress;
404 assert(static_cast<int64_t>(Result) >= INT32_MIN &&
405 static_cast<int64_t>(Result) <= UINT32_MAX);
406 write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
407 break;
408 }
409 case ELF::R_AARCH64_PREL64:
410 write(isBE, TargetPtr, Value + Addend - FinalAddress);
411 break;
412 case ELF::R_AARCH64_CALL26: // fallthrough
413 case ELF::R_AARCH64_JUMP26: {
414 // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
415 // calculation.
416 uint64_t BranchImm = Value + Addend - FinalAddress;
417
418 // "Check that -2^27 <= result < 2^27".
419 assert(isInt<28>(BranchImm));
420 or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) >> 2);
421 break;
422 }
423 case ELF::R_AARCH64_MOVW_UABS_G3:
424 or32le(TargetPtr, ((Value + Addend) & 0xFFFF000000000000) >> 43);
425 break;
426 case ELF::R_AARCH64_MOVW_UABS_G2_NC:
427 or32le(TargetPtr, ((Value + Addend) & 0xFFFF00000000) >> 27);
428 break;
429 case ELF::R_AARCH64_MOVW_UABS_G1_NC:
430 or32le(TargetPtr, ((Value + Addend) & 0xFFFF0000) >> 11);
431 break;
432 case ELF::R_AARCH64_MOVW_UABS_G0_NC:
433 or32le(TargetPtr, ((Value + Addend) & 0xFFFF) << 5);
434 break;
435 case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
436 // Operation: Page(S+A) - Page(P)
437 uint64_t Result =
438 ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
439
440 // Check that -2^32 <= X < 2^32
441 assert(isInt<33>(Result) && "overflow check failed for relocation");
442
443 // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
444 // from bits 32:12 of X.
445 write32AArch64Addr(TargetPtr, Result >> 12);
446 break;
447 }
448 case ELF::R_AARCH64_ADD_ABS_LO12_NC:
449 // Operation: S + A
450 // Immediate goes in bits 21:10 of LD/ST instruction, taken
451 // from bits 11:0 of X
452 or32AArch64Imm(TargetPtr, Value + Addend);
453 break;
454 case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
455 // Operation: S + A
456 // Immediate goes in bits 21:10 of LD/ST instruction, taken
457 // from bits 11:0 of X
458 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 0, 11));
459 break;
460 case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
461 // Operation: S + A
462 // Immediate goes in bits 21:10 of LD/ST instruction, taken
463 // from bits 11:1 of X
464 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 1, 11));
465 break;
466 case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
467 // Operation: S + A
468 // Immediate goes in bits 21:10 of LD/ST instruction, taken
469 // from bits 11:2 of X
470 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 2, 11));
471 break;
472 case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
473 // Operation: S + A
474 // Immediate goes in bits 21:10 of LD/ST instruction, taken
475 // from bits 11:3 of X
476 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 3, 11));
477 break;
478 case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
479 // Operation: S + A
480 // Immediate goes in bits 21:10 of LD/ST instruction, taken
481 // from bits 11:4 of X
482 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 4, 11));
483 break;
484 }
485 }
486
resolveARMRelocation(const SectionEntry & Section,uint64_t Offset,uint32_t Value,uint32_t Type,int32_t Addend)487 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
488 uint64_t Offset, uint32_t Value,
489 uint32_t Type, int32_t Addend) {
490 // TODO: Add Thumb relocations.
491 uint32_t *TargetPtr =
492 reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
493 uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
494 Value += Addend;
495
496 LLVM_DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
497 << Section.getAddressWithOffset(Offset)
498 << " FinalAddress: " << format("%p", FinalAddress)
499 << " Value: " << format("%x", Value)
500 << " Type: " << format("%x", Type)
501 << " Addend: " << format("%x", Addend) << "\n");
502
503 switch (Type) {
504 default:
505 llvm_unreachable("Not implemented relocation type!");
506
507 case ELF::R_ARM_NONE:
508 break;
509 // Write a 31bit signed offset
510 case ELF::R_ARM_PREL31:
511 support::ulittle32_t::ref{TargetPtr} =
512 (support::ulittle32_t::ref{TargetPtr} & 0x80000000) |
513 ((Value - FinalAddress) & ~0x80000000);
514 break;
515 case ELF::R_ARM_TARGET1:
516 case ELF::R_ARM_ABS32:
517 support::ulittle32_t::ref{TargetPtr} = Value;
518 break;
519 // Write first 16 bit of 32 bit value to the mov instruction.
520 // Last 4 bit should be shifted.
521 case ELF::R_ARM_MOVW_ABS_NC:
522 case ELF::R_ARM_MOVT_ABS:
523 if (Type == ELF::R_ARM_MOVW_ABS_NC)
524 Value = Value & 0xFFFF;
525 else if (Type == ELF::R_ARM_MOVT_ABS)
526 Value = (Value >> 16) & 0xFFFF;
527 support::ulittle32_t::ref{TargetPtr} =
528 (support::ulittle32_t::ref{TargetPtr} & ~0x000F0FFF) | (Value & 0xFFF) |
529 (((Value >> 12) & 0xF) << 16);
530 break;
531 // Write 24 bit relative value to the branch instruction.
532 case ELF::R_ARM_PC24: // Fall through.
533 case ELF::R_ARM_CALL: // Fall through.
534 case ELF::R_ARM_JUMP24:
535 int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
536 RelValue = (RelValue & 0x03FFFFFC) >> 2;
537 assert((support::ulittle32_t::ref{TargetPtr} & 0xFFFFFF) == 0xFFFFFE);
538 support::ulittle32_t::ref{TargetPtr} =
539 (support::ulittle32_t::ref{TargetPtr} & 0xFF000000) | RelValue;
540 break;
541 }
542 }
543
setMipsABI(const ObjectFile & Obj)544 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
545 if (Arch == Triple::UnknownArch ||
546 !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
547 IsMipsO32ABI = false;
548 IsMipsN32ABI = false;
549 IsMipsN64ABI = false;
550 return;
551 }
552 if (auto *E = dyn_cast<ELFObjectFileBase>(&Obj)) {
553 unsigned AbiVariant = E->getPlatformFlags();
554 IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
555 IsMipsN32ABI = AbiVariant & ELF::EF_MIPS_ABI2;
556 }
557 IsMipsN64ABI = Obj.getFileFormatName().equals("ELF64-mips");
558 }
559
560 // Return the .TOC. section and offset.
findPPC64TOCSection(const ELFObjectFileBase & Obj,ObjSectionToIDMap & LocalSections,RelocationValueRef & Rel)561 Error RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
562 ObjSectionToIDMap &LocalSections,
563 RelocationValueRef &Rel) {
564 // Set a default SectionID in case we do not find a TOC section below.
565 // This may happen for references to TOC base base (sym@toc, .odp
566 // relocation) without a .toc directive. In this case just use the
567 // first section (which is usually the .odp) since the code won't
568 // reference the .toc base directly.
569 Rel.SymbolName = nullptr;
570 Rel.SectionID = 0;
571
572 // The TOC consists of sections .got, .toc, .tocbss, .plt in that
573 // order. The TOC starts where the first of these sections starts.
574 for (auto &Section : Obj.sections()) {
575 Expected<StringRef> NameOrErr = Section.getName();
576 if (!NameOrErr)
577 return NameOrErr.takeError();
578 StringRef SectionName = *NameOrErr;
579
580 if (SectionName == ".got"
581 || SectionName == ".toc"
582 || SectionName == ".tocbss"
583 || SectionName == ".plt") {
584 if (auto SectionIDOrErr =
585 findOrEmitSection(Obj, Section, false, LocalSections))
586 Rel.SectionID = *SectionIDOrErr;
587 else
588 return SectionIDOrErr.takeError();
589 break;
590 }
591 }
592
593 // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
594 // thus permitting a full 64 Kbytes segment.
595 Rel.Addend = 0x8000;
596
597 return Error::success();
598 }
599
600 // Returns the sections and offset associated with the ODP entry referenced
601 // by Symbol.
findOPDEntrySection(const ELFObjectFileBase & Obj,ObjSectionToIDMap & LocalSections,RelocationValueRef & Rel)602 Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
603 ObjSectionToIDMap &LocalSections,
604 RelocationValueRef &Rel) {
605 // Get the ELF symbol value (st_value) to compare with Relocation offset in
606 // .opd entries
607 for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
608 si != se; ++si) {
609
610 Expected<section_iterator> RelSecOrErr = si->getRelocatedSection();
611 if (!RelSecOrErr)
612 report_fatal_error(toString(RelSecOrErr.takeError()));
613
614 section_iterator RelSecI = *RelSecOrErr;
615 if (RelSecI == Obj.section_end())
616 continue;
617
618 Expected<StringRef> NameOrErr = RelSecI->getName();
619 if (!NameOrErr)
620 return NameOrErr.takeError();
621 StringRef RelSectionName = *NameOrErr;
622
623 if (RelSectionName != ".opd")
624 continue;
625
626 for (elf_relocation_iterator i = si->relocation_begin(),
627 e = si->relocation_end();
628 i != e;) {
629 // The R_PPC64_ADDR64 relocation indicates the first field
630 // of a .opd entry
631 uint64_t TypeFunc = i->getType();
632 if (TypeFunc != ELF::R_PPC64_ADDR64) {
633 ++i;
634 continue;
635 }
636
637 uint64_t TargetSymbolOffset = i->getOffset();
638 symbol_iterator TargetSymbol = i->getSymbol();
639 int64_t Addend;
640 if (auto AddendOrErr = i->getAddend())
641 Addend = *AddendOrErr;
642 else
643 return AddendOrErr.takeError();
644
645 ++i;
646 if (i == e)
647 break;
648
649 // Just check if following relocation is a R_PPC64_TOC
650 uint64_t TypeTOC = i->getType();
651 if (TypeTOC != ELF::R_PPC64_TOC)
652 continue;
653
654 // Finally compares the Symbol value and the target symbol offset
655 // to check if this .opd entry refers to the symbol the relocation
656 // points to.
657 if (Rel.Addend != (int64_t)TargetSymbolOffset)
658 continue;
659
660 section_iterator TSI = Obj.section_end();
661 if (auto TSIOrErr = TargetSymbol->getSection())
662 TSI = *TSIOrErr;
663 else
664 return TSIOrErr.takeError();
665 assert(TSI != Obj.section_end() && "TSI should refer to a valid section");
666
667 bool IsCode = TSI->isText();
668 if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode,
669 LocalSections))
670 Rel.SectionID = *SectionIDOrErr;
671 else
672 return SectionIDOrErr.takeError();
673 Rel.Addend = (intptr_t)Addend;
674 return Error::success();
675 }
676 }
677 llvm_unreachable("Attempting to get address of ODP entry!");
678 }
679
680 // Relocation masks following the #lo(value), #hi(value), #ha(value),
681 // #higher(value), #highera(value), #highest(value), and #highesta(value)
682 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
683 // document.
684
applyPPClo(uint64_t value)685 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
686
applyPPChi(uint64_t value)687 static inline uint16_t applyPPChi(uint64_t value) {
688 return (value >> 16) & 0xffff;
689 }
690
applyPPCha(uint64_t value)691 static inline uint16_t applyPPCha (uint64_t value) {
692 return ((value + 0x8000) >> 16) & 0xffff;
693 }
694
applyPPChigher(uint64_t value)695 static inline uint16_t applyPPChigher(uint64_t value) {
696 return (value >> 32) & 0xffff;
697 }
698
applyPPChighera(uint64_t value)699 static inline uint16_t applyPPChighera (uint64_t value) {
700 return ((value + 0x8000) >> 32) & 0xffff;
701 }
702
applyPPChighest(uint64_t value)703 static inline uint16_t applyPPChighest(uint64_t value) {
704 return (value >> 48) & 0xffff;
705 }
706
applyPPChighesta(uint64_t value)707 static inline uint16_t applyPPChighesta (uint64_t value) {
708 return ((value + 0x8000) >> 48) & 0xffff;
709 }
710
resolvePPC32Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)711 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
712 uint64_t Offset, uint64_t Value,
713 uint32_t Type, int64_t Addend) {
714 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
715 switch (Type) {
716 default:
717 llvm_unreachable("Relocation type not implemented yet!");
718 break;
719 case ELF::R_PPC_ADDR16_LO:
720 writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
721 break;
722 case ELF::R_PPC_ADDR16_HI:
723 writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
724 break;
725 case ELF::R_PPC_ADDR16_HA:
726 writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
727 break;
728 }
729 }
730
resolvePPC64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)731 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
732 uint64_t Offset, uint64_t Value,
733 uint32_t Type, int64_t Addend) {
734 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
735 switch (Type) {
736 default:
737 llvm_unreachable("Relocation type not implemented yet!");
738 break;
739 case ELF::R_PPC64_ADDR16:
740 writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
741 break;
742 case ELF::R_PPC64_ADDR16_DS:
743 writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
744 break;
745 case ELF::R_PPC64_ADDR16_LO:
746 writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
747 break;
748 case ELF::R_PPC64_ADDR16_LO_DS:
749 writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
750 break;
751 case ELF::R_PPC64_ADDR16_HI:
752 case ELF::R_PPC64_ADDR16_HIGH:
753 writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
754 break;
755 case ELF::R_PPC64_ADDR16_HA:
756 case ELF::R_PPC64_ADDR16_HIGHA:
757 writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
758 break;
759 case ELF::R_PPC64_ADDR16_HIGHER:
760 writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
761 break;
762 case ELF::R_PPC64_ADDR16_HIGHERA:
763 writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
764 break;
765 case ELF::R_PPC64_ADDR16_HIGHEST:
766 writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
767 break;
768 case ELF::R_PPC64_ADDR16_HIGHESTA:
769 writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
770 break;
771 case ELF::R_PPC64_ADDR14: {
772 assert(((Value + Addend) & 3) == 0);
773 // Preserve the AA/LK bits in the branch instruction
774 uint8_t aalk = *(LocalAddress + 3);
775 writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
776 } break;
777 case ELF::R_PPC64_REL16_LO: {
778 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
779 uint64_t Delta = Value - FinalAddress + Addend;
780 writeInt16BE(LocalAddress, applyPPClo(Delta));
781 } break;
782 case ELF::R_PPC64_REL16_HI: {
783 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
784 uint64_t Delta = Value - FinalAddress + Addend;
785 writeInt16BE(LocalAddress, applyPPChi(Delta));
786 } break;
787 case ELF::R_PPC64_REL16_HA: {
788 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
789 uint64_t Delta = Value - FinalAddress + Addend;
790 writeInt16BE(LocalAddress, applyPPCha(Delta));
791 } break;
792 case ELF::R_PPC64_ADDR32: {
793 int64_t Result = static_cast<int64_t>(Value + Addend);
794 if (SignExtend64<32>(Result) != Result)
795 llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
796 writeInt32BE(LocalAddress, Result);
797 } break;
798 case ELF::R_PPC64_REL24: {
799 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
800 int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
801 if (SignExtend64<26>(delta) != delta)
802 llvm_unreachable("Relocation R_PPC64_REL24 overflow");
803 // We preserve bits other than LI field, i.e. PO and AA/LK fields.
804 uint32_t Inst = readBytesUnaligned(LocalAddress, 4);
805 writeInt32BE(LocalAddress, (Inst & 0xFC000003) | (delta & 0x03FFFFFC));
806 } break;
807 case ELF::R_PPC64_REL32: {
808 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
809 int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
810 if (SignExtend64<32>(delta) != delta)
811 llvm_unreachable("Relocation R_PPC64_REL32 overflow");
812 writeInt32BE(LocalAddress, delta);
813 } break;
814 case ELF::R_PPC64_REL64: {
815 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
816 uint64_t Delta = Value - FinalAddress + Addend;
817 writeInt64BE(LocalAddress, Delta);
818 } break;
819 case ELF::R_PPC64_ADDR64:
820 writeInt64BE(LocalAddress, Value + Addend);
821 break;
822 }
823 }
824
resolveSystemZRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)825 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
826 uint64_t Offset, uint64_t Value,
827 uint32_t Type, int64_t Addend) {
828 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
829 switch (Type) {
830 default:
831 llvm_unreachable("Relocation type not implemented yet!");
832 break;
833 case ELF::R_390_PC16DBL:
834 case ELF::R_390_PLT16DBL: {
835 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
836 assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
837 writeInt16BE(LocalAddress, Delta / 2);
838 break;
839 }
840 case ELF::R_390_PC32DBL:
841 case ELF::R_390_PLT32DBL: {
842 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
843 assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
844 writeInt32BE(LocalAddress, Delta / 2);
845 break;
846 }
847 case ELF::R_390_PC16: {
848 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
849 assert(int16_t(Delta) == Delta && "R_390_PC16 overflow");
850 writeInt16BE(LocalAddress, Delta);
851 break;
852 }
853 case ELF::R_390_PC32: {
854 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
855 assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
856 writeInt32BE(LocalAddress, Delta);
857 break;
858 }
859 case ELF::R_390_PC64: {
860 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
861 writeInt64BE(LocalAddress, Delta);
862 break;
863 }
864 case ELF::R_390_8:
865 *LocalAddress = (uint8_t)(Value + Addend);
866 break;
867 case ELF::R_390_16:
868 writeInt16BE(LocalAddress, Value + Addend);
869 break;
870 case ELF::R_390_32:
871 writeInt32BE(LocalAddress, Value + Addend);
872 break;
873 case ELF::R_390_64:
874 writeInt64BE(LocalAddress, Value + Addend);
875 break;
876 }
877 }
878
resolveBPFRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)879 void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
880 uint64_t Offset, uint64_t Value,
881 uint32_t Type, int64_t Addend) {
882 bool isBE = Arch == Triple::bpfeb;
883
884 switch (Type) {
885 default:
886 llvm_unreachable("Relocation type not implemented yet!");
887 break;
888 case ELF::R_BPF_NONE:
889 break;
890 case ELF::R_BPF_64_64: {
891 write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
892 LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
893 << format("%p\n", Section.getAddressWithOffset(Offset)));
894 break;
895 }
896 case ELF::R_BPF_64_32: {
897 Value += Addend;
898 assert(Value <= UINT32_MAX);
899 write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
900 LLVM_DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
901 << format("%p\n", Section.getAddressWithOffset(Offset)));
902 break;
903 }
904 }
905 }
906
907 // The target location for the relocation is described by RE.SectionID and
908 // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
909 // SectionEntry has three members describing its location.
910 // SectionEntry::Address is the address at which the section has been loaded
911 // into memory in the current (host) process. SectionEntry::LoadAddress is the
912 // address that the section will have in the target process.
913 // SectionEntry::ObjAddress is the address of the bits for this section in the
914 // original emitted object image (also in the current address space).
915 //
916 // Relocations will be applied as if the section were loaded at
917 // SectionEntry::LoadAddress, but they will be applied at an address based
918 // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer to
919 // Target memory contents if they are required for value calculations.
920 //
921 // The Value parameter here is the load address of the symbol for the
922 // relocation to be applied. For relocations which refer to symbols in the
923 // current object Value will be the LoadAddress of the section in which
924 // the symbol resides (RE.Addend provides additional information about the
925 // symbol location). For external symbols, Value will be the address of the
926 // symbol in the target address space.
resolveRelocation(const RelocationEntry & RE,uint64_t Value)927 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
928 uint64_t Value) {
929 const SectionEntry &Section = Sections[RE.SectionID];
930 return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
931 RE.SymOffset, RE.SectionID);
932 }
933
resolveRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend,uint64_t SymOffset,SID SectionID)934 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
935 uint64_t Offset, uint64_t Value,
936 uint32_t Type, int64_t Addend,
937 uint64_t SymOffset, SID SectionID) {
938 switch (Arch) {
939 case Triple::x86_64:
940 resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
941 break;
942 case Triple::x86:
943 resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
944 (uint32_t)(Addend & 0xffffffffL));
945 break;
946 case Triple::aarch64:
947 case Triple::aarch64_be:
948 resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
949 break;
950 case Triple::arm: // Fall through.
951 case Triple::armeb:
952 case Triple::thumb:
953 case Triple::thumbeb:
954 resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
955 (uint32_t)(Addend & 0xffffffffL));
956 break;
957 case Triple::ppc:
958 resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
959 break;
960 case Triple::ppc64: // Fall through.
961 case Triple::ppc64le:
962 resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
963 break;
964 case Triple::systemz:
965 resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
966 break;
967 case Triple::bpfel:
968 case Triple::bpfeb:
969 resolveBPFRelocation(Section, Offset, Value, Type, Addend);
970 break;
971 default:
972 llvm_unreachable("Unsupported CPU type!");
973 }
974 }
975
computePlaceholderAddress(unsigned SectionID,uint64_t Offset) const976 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
977 return (void *)(Sections[SectionID].getObjAddress() + Offset);
978 }
979
processSimpleRelocation(unsigned SectionID,uint64_t Offset,unsigned RelType,RelocationValueRef Value)980 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
981 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
982 if (Value.SymbolName)
983 addRelocationForSymbol(RE, Value.SymbolName);
984 else
985 addRelocationForSection(RE, Value.SectionID);
986 }
987
getMatchingLoRelocation(uint32_t RelType,bool IsLocal) const988 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
989 bool IsLocal) const {
990 switch (RelType) {
991 case ELF::R_MICROMIPS_GOT16:
992 if (IsLocal)
993 return ELF::R_MICROMIPS_LO16;
994 break;
995 case ELF::R_MICROMIPS_HI16:
996 return ELF::R_MICROMIPS_LO16;
997 case ELF::R_MIPS_GOT16:
998 if (IsLocal)
999 return ELF::R_MIPS_LO16;
1000 break;
1001 case ELF::R_MIPS_HI16:
1002 return ELF::R_MIPS_LO16;
1003 case ELF::R_MIPS_PCHI16:
1004 return ELF::R_MIPS_PCLO16;
1005 default:
1006 break;
1007 }
1008 return ELF::R_MIPS_NONE;
1009 }
1010
1011 // Sometimes we don't need to create thunk for a branch.
1012 // This typically happens when branch target is located
1013 // in the same object file. In such case target is either
1014 // a weak symbol or symbol in a different executable section.
1015 // This function checks if branch target is located in the
1016 // same object file and if distance between source and target
1017 // fits R_AARCH64_CALL26 relocation. If both conditions are
1018 // met, it emits direct jump to the target and returns true.
1019 // Otherwise false is returned and thunk is created.
resolveAArch64ShortBranch(unsigned SectionID,relocation_iterator RelI,const RelocationValueRef & Value)1020 bool RuntimeDyldELF::resolveAArch64ShortBranch(
1021 unsigned SectionID, relocation_iterator RelI,
1022 const RelocationValueRef &Value) {
1023 uint64_t Address;
1024 if (Value.SymbolName) {
1025 auto Loc = GlobalSymbolTable.find(Value.SymbolName);
1026
1027 // Don't create direct branch for external symbols.
1028 if (Loc == GlobalSymbolTable.end())
1029 return false;
1030
1031 const auto &SymInfo = Loc->second;
1032 Address =
1033 uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset(
1034 SymInfo.getOffset()));
1035 } else {
1036 Address = uint64_t(Sections[Value.SectionID].getLoadAddress());
1037 }
1038 uint64_t Offset = RelI->getOffset();
1039 uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset);
1040
1041 // R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27
1042 // If distance between source and target is out of range then we should
1043 // create thunk.
1044 if (!isInt<28>(Address + Value.Addend - SourceAddress))
1045 return false;
1046
1047 resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(),
1048 Value.Addend);
1049
1050 return true;
1051 }
1052
resolveAArch64Branch(unsigned SectionID,const RelocationValueRef & Value,relocation_iterator RelI,StubMap & Stubs)1053 void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID,
1054 const RelocationValueRef &Value,
1055 relocation_iterator RelI,
1056 StubMap &Stubs) {
1057
1058 LLVM_DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1059 SectionEntry &Section = Sections[SectionID];
1060
1061 uint64_t Offset = RelI->getOffset();
1062 unsigned RelType = RelI->getType();
1063 // Look for an existing stub.
1064 StubMap::const_iterator i = Stubs.find(Value);
1065 if (i != Stubs.end()) {
1066 resolveRelocation(Section, Offset,
1067 (uint64_t)Section.getAddressWithOffset(i->second),
1068 RelType, 0);
1069 LLVM_DEBUG(dbgs() << " Stub function found\n");
1070 } else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) {
1071 // Create a new stub function.
1072 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1073 Stubs[Value] = Section.getStubOffset();
1074 uint8_t *StubTargetAddr = createStubFunction(
1075 Section.getAddressWithOffset(Section.getStubOffset()));
1076
1077 RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(),
1078 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1079 RelocationEntry REmovk_g2(SectionID,
1080 StubTargetAddr - Section.getAddress() + 4,
1081 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1082 RelocationEntry REmovk_g1(SectionID,
1083 StubTargetAddr - Section.getAddress() + 8,
1084 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1085 RelocationEntry REmovk_g0(SectionID,
1086 StubTargetAddr - Section.getAddress() + 12,
1087 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1088
1089 if (Value.SymbolName) {
1090 addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1091 addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1092 addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1093 addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1094 } else {
1095 addRelocationForSection(REmovz_g3, Value.SectionID);
1096 addRelocationForSection(REmovk_g2, Value.SectionID);
1097 addRelocationForSection(REmovk_g1, Value.SectionID);
1098 addRelocationForSection(REmovk_g0, Value.SectionID);
1099 }
1100 resolveRelocation(Section, Offset,
1101 reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
1102 Section.getStubOffset())),
1103 RelType, 0);
1104 Section.advanceStubOffset(getMaxStubSize());
1105 }
1106 }
1107
1108 Expected<relocation_iterator>
processRelocationRef(unsigned SectionID,relocation_iterator RelI,const ObjectFile & O,ObjSectionToIDMap & ObjSectionToID,StubMap & Stubs)1109 RuntimeDyldELF::processRelocationRef(
1110 unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1111 ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1112 const auto &Obj = cast<ELFObjectFileBase>(O);
1113 uint64_t RelType = RelI->getType();
1114 int64_t Addend = 0;
1115 if (Expected<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend())
1116 Addend = *AddendOrErr;
1117 else
1118 consumeError(AddendOrErr.takeError());
1119 elf_symbol_iterator Symbol = RelI->getSymbol();
1120
1121 // Obtain the symbol name which is referenced in the relocation
1122 StringRef TargetName;
1123 if (Symbol != Obj.symbol_end()) {
1124 if (auto TargetNameOrErr = Symbol->getName())
1125 TargetName = *TargetNameOrErr;
1126 else
1127 return TargetNameOrErr.takeError();
1128 }
1129 LLVM_DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1130 << " TargetName: " << TargetName << "\n");
1131 RelocationValueRef Value;
1132 // First search for the symbol in the local symbol table
1133 SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1134
1135 // Search for the symbol in the global symbol table
1136 RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1137 if (Symbol != Obj.symbol_end()) {
1138 gsi = GlobalSymbolTable.find(TargetName.data());
1139 Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType();
1140 if (!SymTypeOrErr) {
1141 std::string Buf;
1142 raw_string_ostream OS(Buf);
1143 logAllUnhandledErrors(SymTypeOrErr.takeError(), OS);
1144 OS.flush();
1145 report_fatal_error(Buf);
1146 }
1147 SymType = *SymTypeOrErr;
1148 }
1149 if (gsi != GlobalSymbolTable.end()) {
1150 const auto &SymInfo = gsi->second;
1151 Value.SectionID = SymInfo.getSectionID();
1152 Value.Offset = SymInfo.getOffset();
1153 Value.Addend = SymInfo.getOffset() + Addend;
1154 } else {
1155 switch (SymType) {
1156 case SymbolRef::ST_Debug: {
1157 // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1158 // and can be changed by another developers. Maybe best way is add
1159 // a new symbol type ST_Section to SymbolRef and use it.
1160 auto SectionOrErr = Symbol->getSection();
1161 if (!SectionOrErr) {
1162 std::string Buf;
1163 raw_string_ostream OS(Buf);
1164 logAllUnhandledErrors(SectionOrErr.takeError(), OS);
1165 OS.flush();
1166 report_fatal_error(Buf);
1167 }
1168 section_iterator si = *SectionOrErr;
1169 if (si == Obj.section_end())
1170 llvm_unreachable("Symbol section not found, bad object file format!");
1171 LLVM_DEBUG(dbgs() << "\t\tThis is section symbol\n");
1172 bool isCode = si->isText();
1173 if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode,
1174 ObjSectionToID))
1175 Value.SectionID = *SectionIDOrErr;
1176 else
1177 return SectionIDOrErr.takeError();
1178 Value.Addend = Addend;
1179 break;
1180 }
1181 case SymbolRef::ST_Data:
1182 case SymbolRef::ST_Function:
1183 case SymbolRef::ST_Unknown: {
1184 Value.SymbolName = TargetName.data();
1185 Value.Addend = Addend;
1186
1187 // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1188 // will manifest here as a NULL symbol name.
1189 // We can set this as a valid (but empty) symbol name, and rely
1190 // on addRelocationForSymbol to handle this.
1191 if (!Value.SymbolName)
1192 Value.SymbolName = "";
1193 break;
1194 }
1195 default:
1196 llvm_unreachable("Unresolved symbol type!");
1197 break;
1198 }
1199 }
1200
1201 uint64_t Offset = RelI->getOffset();
1202
1203 LLVM_DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1204 << "\n");
1205 if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) {
1206 if (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26) {
1207 resolveAArch64Branch(SectionID, Value, RelI, Stubs);
1208 } else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) {
1209 // Craete new GOT entry or find existing one. If GOT entry is
1210 // to be created, then we also emit ABS64 relocation for it.
1211 uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1212 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1213 ELF::R_AARCH64_ADR_PREL_PG_HI21);
1214
1215 } else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) {
1216 uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1217 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1218 ELF::R_AARCH64_LDST64_ABS_LO12_NC);
1219 } else {
1220 processSimpleRelocation(SectionID, Offset, RelType, Value);
1221 }
1222 } else if (Arch == Triple::arm) {
1223 if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1224 RelType == ELF::R_ARM_JUMP24) {
1225 // This is an ARM branch relocation, need to use a stub function.
1226 LLVM_DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n");
1227 SectionEntry &Section = Sections[SectionID];
1228
1229 // Look for an existing stub.
1230 StubMap::const_iterator i = Stubs.find(Value);
1231 if (i != Stubs.end()) {
1232 resolveRelocation(
1233 Section, Offset,
1234 reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
1235 RelType, 0);
1236 LLVM_DEBUG(dbgs() << " Stub function found\n");
1237 } else {
1238 // Create a new stub function.
1239 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1240 Stubs[Value] = Section.getStubOffset();
1241 uint8_t *StubTargetAddr = createStubFunction(
1242 Section.getAddressWithOffset(Section.getStubOffset()));
1243 RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1244 ELF::R_ARM_ABS32, Value.Addend);
1245 if (Value.SymbolName)
1246 addRelocationForSymbol(RE, Value.SymbolName);
1247 else
1248 addRelocationForSection(RE, Value.SectionID);
1249
1250 resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1251 Section.getAddressWithOffset(
1252 Section.getStubOffset())),
1253 RelType, 0);
1254 Section.advanceStubOffset(getMaxStubSize());
1255 }
1256 } else {
1257 uint32_t *Placeholder =
1258 reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1259 if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1260 RelType == ELF::R_ARM_ABS32) {
1261 Value.Addend += *Placeholder;
1262 } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1263 // See ELF for ARM documentation
1264 Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1265 }
1266 processSimpleRelocation(SectionID, Offset, RelType, Value);
1267 }
1268 } else if (IsMipsO32ABI) {
1269 uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1270 computePlaceholderAddress(SectionID, Offset));
1271 uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1272 if (RelType == ELF::R_MIPS_26) {
1273 // This is an Mips branch relocation, need to use a stub function.
1274 LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1275 SectionEntry &Section = Sections[SectionID];
1276
1277 // Extract the addend from the instruction.
1278 // We shift up by two since the Value will be down shifted again
1279 // when applying the relocation.
1280 uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1281
1282 Value.Addend += Addend;
1283
1284 // Look up for existing stub.
1285 StubMap::const_iterator i = Stubs.find(Value);
1286 if (i != Stubs.end()) {
1287 RelocationEntry RE(SectionID, Offset, RelType, i->second);
1288 addRelocationForSection(RE, SectionID);
1289 LLVM_DEBUG(dbgs() << " Stub function found\n");
1290 } else {
1291 // Create a new stub function.
1292 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1293 Stubs[Value] = Section.getStubOffset();
1294
1295 unsigned AbiVariant = Obj.getPlatformFlags();
1296
1297 uint8_t *StubTargetAddr = createStubFunction(
1298 Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1299
1300 // Creating Hi and Lo relocations for the filled stub instructions.
1301 RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1302 ELF::R_MIPS_HI16, Value.Addend);
1303 RelocationEntry RELo(SectionID,
1304 StubTargetAddr - Section.getAddress() + 4,
1305 ELF::R_MIPS_LO16, Value.Addend);
1306
1307 if (Value.SymbolName) {
1308 addRelocationForSymbol(REHi, Value.SymbolName);
1309 addRelocationForSymbol(RELo, Value.SymbolName);
1310 } else {
1311 addRelocationForSection(REHi, Value.SectionID);
1312 addRelocationForSection(RELo, Value.SectionID);
1313 }
1314
1315 RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1316 addRelocationForSection(RE, SectionID);
1317 Section.advanceStubOffset(getMaxStubSize());
1318 }
1319 } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
1320 int64_t Addend = (Opcode & 0x0000ffff) << 16;
1321 RelocationEntry RE(SectionID, Offset, RelType, Addend);
1322 PendingRelocs.push_back(std::make_pair(Value, RE));
1323 } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
1324 int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
1325 for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
1326 const RelocationValueRef &MatchingValue = I->first;
1327 RelocationEntry &Reloc = I->second;
1328 if (MatchingValue == Value &&
1329 RelType == getMatchingLoRelocation(Reloc.RelType) &&
1330 SectionID == Reloc.SectionID) {
1331 Reloc.Addend += Addend;
1332 if (Value.SymbolName)
1333 addRelocationForSymbol(Reloc, Value.SymbolName);
1334 else
1335 addRelocationForSection(Reloc, Value.SectionID);
1336 I = PendingRelocs.erase(I);
1337 } else
1338 ++I;
1339 }
1340 RelocationEntry RE(SectionID, Offset, RelType, Addend);
1341 if (Value.SymbolName)
1342 addRelocationForSymbol(RE, Value.SymbolName);
1343 else
1344 addRelocationForSection(RE, Value.SectionID);
1345 } else {
1346 if (RelType == ELF::R_MIPS_32)
1347 Value.Addend += Opcode;
1348 else if (RelType == ELF::R_MIPS_PC16)
1349 Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1350 else if (RelType == ELF::R_MIPS_PC19_S2)
1351 Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1352 else if (RelType == ELF::R_MIPS_PC21_S2)
1353 Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1354 else if (RelType == ELF::R_MIPS_PC26_S2)
1355 Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1356 processSimpleRelocation(SectionID, Offset, RelType, Value);
1357 }
1358 } else if (IsMipsN32ABI || IsMipsN64ABI) {
1359 uint32_t r_type = RelType & 0xff;
1360 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1361 if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1362 || r_type == ELF::R_MIPS_GOT_DISP) {
1363 StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1364 if (i != GOTSymbolOffsets.end())
1365 RE.SymOffset = i->second;
1366 else {
1367 RE.SymOffset = allocateGOTEntries(1);
1368 GOTSymbolOffsets[TargetName] = RE.SymOffset;
1369 }
1370 if (Value.SymbolName)
1371 addRelocationForSymbol(RE, Value.SymbolName);
1372 else
1373 addRelocationForSection(RE, Value.SectionID);
1374 } else if (RelType == ELF::R_MIPS_26) {
1375 // This is an Mips branch relocation, need to use a stub function.
1376 LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1377 SectionEntry &Section = Sections[SectionID];
1378
1379 // Look up for existing stub.
1380 StubMap::const_iterator i = Stubs.find(Value);
1381 if (i != Stubs.end()) {
1382 RelocationEntry RE(SectionID, Offset, RelType, i->second);
1383 addRelocationForSection(RE, SectionID);
1384 LLVM_DEBUG(dbgs() << " Stub function found\n");
1385 } else {
1386 // Create a new stub function.
1387 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1388 Stubs[Value] = Section.getStubOffset();
1389
1390 unsigned AbiVariant = Obj.getPlatformFlags();
1391
1392 uint8_t *StubTargetAddr = createStubFunction(
1393 Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1394
1395 if (IsMipsN32ABI) {
1396 // Creating Hi and Lo relocations for the filled stub instructions.
1397 RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1398 ELF::R_MIPS_HI16, Value.Addend);
1399 RelocationEntry RELo(SectionID,
1400 StubTargetAddr - Section.getAddress() + 4,
1401 ELF::R_MIPS_LO16, Value.Addend);
1402 if (Value.SymbolName) {
1403 addRelocationForSymbol(REHi, Value.SymbolName);
1404 addRelocationForSymbol(RELo, Value.SymbolName);
1405 } else {
1406 addRelocationForSection(REHi, Value.SectionID);
1407 addRelocationForSection(RELo, Value.SectionID);
1408 }
1409 } else {
1410 // Creating Highest, Higher, Hi and Lo relocations for the filled stub
1411 // instructions.
1412 RelocationEntry REHighest(SectionID,
1413 StubTargetAddr - Section.getAddress(),
1414 ELF::R_MIPS_HIGHEST, Value.Addend);
1415 RelocationEntry REHigher(SectionID,
1416 StubTargetAddr - Section.getAddress() + 4,
1417 ELF::R_MIPS_HIGHER, Value.Addend);
1418 RelocationEntry REHi(SectionID,
1419 StubTargetAddr - Section.getAddress() + 12,
1420 ELF::R_MIPS_HI16, Value.Addend);
1421 RelocationEntry RELo(SectionID,
1422 StubTargetAddr - Section.getAddress() + 20,
1423 ELF::R_MIPS_LO16, Value.Addend);
1424 if (Value.SymbolName) {
1425 addRelocationForSymbol(REHighest, Value.SymbolName);
1426 addRelocationForSymbol(REHigher, Value.SymbolName);
1427 addRelocationForSymbol(REHi, Value.SymbolName);
1428 addRelocationForSymbol(RELo, Value.SymbolName);
1429 } else {
1430 addRelocationForSection(REHighest, Value.SectionID);
1431 addRelocationForSection(REHigher, Value.SectionID);
1432 addRelocationForSection(REHi, Value.SectionID);
1433 addRelocationForSection(RELo, Value.SectionID);
1434 }
1435 }
1436 RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1437 addRelocationForSection(RE, SectionID);
1438 Section.advanceStubOffset(getMaxStubSize());
1439 }
1440 } else {
1441 processSimpleRelocation(SectionID, Offset, RelType, Value);
1442 }
1443
1444 } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1445 if (RelType == ELF::R_PPC64_REL24) {
1446 // Determine ABI variant in use for this object.
1447 unsigned AbiVariant = Obj.getPlatformFlags();
1448 AbiVariant &= ELF::EF_PPC64_ABI;
1449 // A PPC branch relocation will need a stub function if the target is
1450 // an external symbol (either Value.SymbolName is set, or SymType is
1451 // Symbol::ST_Unknown) or if the target address is not within the
1452 // signed 24-bits branch address.
1453 SectionEntry &Section = Sections[SectionID];
1454 uint8_t *Target = Section.getAddressWithOffset(Offset);
1455 bool RangeOverflow = false;
1456 bool IsExtern = Value.SymbolName || SymType == SymbolRef::ST_Unknown;
1457 if (!IsExtern) {
1458 if (AbiVariant != 2) {
1459 // In the ELFv1 ABI, a function call may point to the .opd entry,
1460 // so the final symbol value is calculated based on the relocation
1461 // values in the .opd section.
1462 if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value))
1463 return std::move(Err);
1464 } else {
1465 // In the ELFv2 ABI, a function symbol may provide a local entry
1466 // point, which must be used for direct calls.
1467 if (Value.SectionID == SectionID){
1468 uint8_t SymOther = Symbol->getOther();
1469 Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1470 }
1471 }
1472 uint8_t *RelocTarget =
1473 Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
1474 int64_t delta = static_cast<int64_t>(Target - RelocTarget);
1475 // If it is within 26-bits branch range, just set the branch target
1476 if (SignExtend64<26>(delta) != delta) {
1477 RangeOverflow = true;
1478 } else if ((AbiVariant != 2) ||
1479 (AbiVariant == 2 && Value.SectionID == SectionID)) {
1480 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1481 addRelocationForSection(RE, Value.SectionID);
1482 }
1483 }
1484 if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID) ||
1485 RangeOverflow) {
1486 // It is an external symbol (either Value.SymbolName is set, or
1487 // SymType is SymbolRef::ST_Unknown) or out of range.
1488 StubMap::const_iterator i = Stubs.find(Value);
1489 if (i != Stubs.end()) {
1490 // Symbol function stub already created, just relocate to it
1491 resolveRelocation(Section, Offset,
1492 reinterpret_cast<uint64_t>(
1493 Section.getAddressWithOffset(i->second)),
1494 RelType, 0);
1495 LLVM_DEBUG(dbgs() << " Stub function found\n");
1496 } else {
1497 // Create a new stub function.
1498 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1499 Stubs[Value] = Section.getStubOffset();
1500 uint8_t *StubTargetAddr = createStubFunction(
1501 Section.getAddressWithOffset(Section.getStubOffset()),
1502 AbiVariant);
1503 RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1504 ELF::R_PPC64_ADDR64, Value.Addend);
1505
1506 // Generates the 64-bits address loads as exemplified in section
1507 // 4.5.1 in PPC64 ELF ABI. Note that the relocations need to
1508 // apply to the low part of the instructions, so we have to update
1509 // the offset according to the target endianness.
1510 uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
1511 if (!IsTargetLittleEndian)
1512 StubRelocOffset += 2;
1513
1514 RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1515 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1516 RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1517 ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1518 RelocationEntry REh(SectionID, StubRelocOffset + 12,
1519 ELF::R_PPC64_ADDR16_HI, Value.Addend);
1520 RelocationEntry REl(SectionID, StubRelocOffset + 16,
1521 ELF::R_PPC64_ADDR16_LO, Value.Addend);
1522
1523 if (Value.SymbolName) {
1524 addRelocationForSymbol(REhst, Value.SymbolName);
1525 addRelocationForSymbol(REhr, Value.SymbolName);
1526 addRelocationForSymbol(REh, Value.SymbolName);
1527 addRelocationForSymbol(REl, Value.SymbolName);
1528 } else {
1529 addRelocationForSection(REhst, Value.SectionID);
1530 addRelocationForSection(REhr, Value.SectionID);
1531 addRelocationForSection(REh, Value.SectionID);
1532 addRelocationForSection(REl, Value.SectionID);
1533 }
1534
1535 resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1536 Section.getAddressWithOffset(
1537 Section.getStubOffset())),
1538 RelType, 0);
1539 Section.advanceStubOffset(getMaxStubSize());
1540 }
1541 if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID)) {
1542 // Restore the TOC for external calls
1543 if (AbiVariant == 2)
1544 writeInt32BE(Target + 4, 0xE8410018); // ld r2,24(r1)
1545 else
1546 writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1547 }
1548 }
1549 } else if (RelType == ELF::R_PPC64_TOC16 ||
1550 RelType == ELF::R_PPC64_TOC16_DS ||
1551 RelType == ELF::R_PPC64_TOC16_LO ||
1552 RelType == ELF::R_PPC64_TOC16_LO_DS ||
1553 RelType == ELF::R_PPC64_TOC16_HI ||
1554 RelType == ELF::R_PPC64_TOC16_HA) {
1555 // These relocations are supposed to subtract the TOC address from
1556 // the final value. This does not fit cleanly into the RuntimeDyld
1557 // scheme, since there may be *two* sections involved in determining
1558 // the relocation value (the section of the symbol referred to by the
1559 // relocation, and the TOC section associated with the current module).
1560 //
1561 // Fortunately, these relocations are currently only ever generated
1562 // referring to symbols that themselves reside in the TOC, which means
1563 // that the two sections are actually the same. Thus they cancel out
1564 // and we can immediately resolve the relocation right now.
1565 switch (RelType) {
1566 case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1567 case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1568 case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1569 case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1570 case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1571 case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1572 default: llvm_unreachable("Wrong relocation type.");
1573 }
1574
1575 RelocationValueRef TOCValue;
1576 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue))
1577 return std::move(Err);
1578 if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1579 llvm_unreachable("Unsupported TOC relocation.");
1580 Value.Addend -= TOCValue.Addend;
1581 resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1582 } else {
1583 // There are two ways to refer to the TOC address directly: either
1584 // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1585 // ignored), or via any relocation that refers to the magic ".TOC."
1586 // symbols (in which case the addend is respected).
1587 if (RelType == ELF::R_PPC64_TOC) {
1588 RelType = ELF::R_PPC64_ADDR64;
1589 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1590 return std::move(Err);
1591 } else if (TargetName == ".TOC.") {
1592 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1593 return std::move(Err);
1594 Value.Addend += Addend;
1595 }
1596
1597 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1598
1599 if (Value.SymbolName)
1600 addRelocationForSymbol(RE, Value.SymbolName);
1601 else
1602 addRelocationForSection(RE, Value.SectionID);
1603 }
1604 } else if (Arch == Triple::systemz &&
1605 (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1606 // Create function stubs for both PLT and GOT references, regardless of
1607 // whether the GOT reference is to data or code. The stub contains the
1608 // full address of the symbol, as needed by GOT references, and the
1609 // executable part only adds an overhead of 8 bytes.
1610 //
1611 // We could try to conserve space by allocating the code and data
1612 // parts of the stub separately. However, as things stand, we allocate
1613 // a stub for every relocation, so using a GOT in JIT code should be
1614 // no less space efficient than using an explicit constant pool.
1615 LLVM_DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1616 SectionEntry &Section = Sections[SectionID];
1617
1618 // Look for an existing stub.
1619 StubMap::const_iterator i = Stubs.find(Value);
1620 uintptr_t StubAddress;
1621 if (i != Stubs.end()) {
1622 StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
1623 LLVM_DEBUG(dbgs() << " Stub function found\n");
1624 } else {
1625 // Create a new stub function.
1626 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1627
1628 uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1629 uintptr_t StubAlignment = getStubAlignment();
1630 StubAddress =
1631 (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1632 -StubAlignment;
1633 unsigned StubOffset = StubAddress - BaseAddress;
1634
1635 Stubs[Value] = StubOffset;
1636 createStubFunction((uint8_t *)StubAddress);
1637 RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1638 Value.Offset);
1639 if (Value.SymbolName)
1640 addRelocationForSymbol(RE, Value.SymbolName);
1641 else
1642 addRelocationForSection(RE, Value.SectionID);
1643 Section.advanceStubOffset(getMaxStubSize());
1644 }
1645
1646 if (RelType == ELF::R_390_GOTENT)
1647 resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1648 Addend);
1649 else
1650 resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1651 } else if (Arch == Triple::x86_64) {
1652 if (RelType == ELF::R_X86_64_PLT32) {
1653 // The way the PLT relocations normally work is that the linker allocates
1654 // the
1655 // PLT and this relocation makes a PC-relative call into the PLT. The PLT
1656 // entry will then jump to an address provided by the GOT. On first call,
1657 // the
1658 // GOT address will point back into PLT code that resolves the symbol. After
1659 // the first call, the GOT entry points to the actual function.
1660 //
1661 // For local functions we're ignoring all of that here and just replacing
1662 // the PLT32 relocation type with PC32, which will translate the relocation
1663 // into a PC-relative call directly to the function. For external symbols we
1664 // can't be sure the function will be within 2^32 bytes of the call site, so
1665 // we need to create a stub, which calls into the GOT. This case is
1666 // equivalent to the usual PLT implementation except that we use the stub
1667 // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1668 // rather than allocating a PLT section.
1669 if (Value.SymbolName) {
1670 // This is a call to an external function.
1671 // Look for an existing stub.
1672 SectionEntry &Section = Sections[SectionID];
1673 StubMap::const_iterator i = Stubs.find(Value);
1674 uintptr_t StubAddress;
1675 if (i != Stubs.end()) {
1676 StubAddress = uintptr_t(Section.getAddress()) + i->second;
1677 LLVM_DEBUG(dbgs() << " Stub function found\n");
1678 } else {
1679 // Create a new stub function (equivalent to a PLT entry).
1680 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1681
1682 uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1683 uintptr_t StubAlignment = getStubAlignment();
1684 StubAddress =
1685 (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1686 -StubAlignment;
1687 unsigned StubOffset = StubAddress - BaseAddress;
1688 Stubs[Value] = StubOffset;
1689 createStubFunction((uint8_t *)StubAddress);
1690
1691 // Bump our stub offset counter
1692 Section.advanceStubOffset(getMaxStubSize());
1693
1694 // Allocate a GOT Entry
1695 uint64_t GOTOffset = allocateGOTEntries(1);
1696
1697 // The load of the GOT address has an addend of -4
1698 resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
1699 ELF::R_X86_64_PC32);
1700
1701 // Fill in the value of the symbol we're targeting into the GOT
1702 addRelocationForSymbol(
1703 computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
1704 Value.SymbolName);
1705 }
1706
1707 // Make the target call a call into the stub table.
1708 resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1709 Addend);
1710 } else {
1711 RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1712 Value.Offset);
1713 addRelocationForSection(RE, Value.SectionID);
1714 }
1715 } else if (RelType == ELF::R_X86_64_GOTPCREL ||
1716 RelType == ELF::R_X86_64_GOTPCRELX ||
1717 RelType == ELF::R_X86_64_REX_GOTPCRELX) {
1718 uint64_t GOTOffset = allocateGOTEntries(1);
1719 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1720 ELF::R_X86_64_PC32);
1721
1722 // Fill in the value of the symbol we're targeting into the GOT
1723 RelocationEntry RE =
1724 computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1725 if (Value.SymbolName)
1726 addRelocationForSymbol(RE, Value.SymbolName);
1727 else
1728 addRelocationForSection(RE, Value.SectionID);
1729 } else if (RelType == ELF::R_X86_64_GOT64) {
1730 // Fill in a 64-bit GOT offset.
1731 uint64_t GOTOffset = allocateGOTEntries(1);
1732 resolveRelocation(Sections[SectionID], Offset, GOTOffset,
1733 ELF::R_X86_64_64, 0);
1734
1735 // Fill in the value of the symbol we're targeting into the GOT
1736 RelocationEntry RE =
1737 computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1738 if (Value.SymbolName)
1739 addRelocationForSymbol(RE, Value.SymbolName);
1740 else
1741 addRelocationForSection(RE, Value.SectionID);
1742 } else if (RelType == ELF::R_X86_64_GOTPC64) {
1743 // Materialize the address of the base of the GOT relative to the PC.
1744 // This doesn't create a GOT entry, but it does mean we need a GOT
1745 // section.
1746 (void)allocateGOTEntries(0);
1747 resolveGOTOffsetRelocation(SectionID, Offset, Addend, ELF::R_X86_64_PC64);
1748 } else if (RelType == ELF::R_X86_64_GOTOFF64) {
1749 // GOTOFF relocations ultimately require a section difference relocation.
1750 (void)allocateGOTEntries(0);
1751 processSimpleRelocation(SectionID, Offset, RelType, Value);
1752 } else if (RelType == ELF::R_X86_64_PC32) {
1753 Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1754 processSimpleRelocation(SectionID, Offset, RelType, Value);
1755 } else if (RelType == ELF::R_X86_64_PC64) {
1756 Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1757 processSimpleRelocation(SectionID, Offset, RelType, Value);
1758 } else {
1759 processSimpleRelocation(SectionID, Offset, RelType, Value);
1760 }
1761 } else {
1762 if (Arch == Triple::x86) {
1763 Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1764 }
1765 processSimpleRelocation(SectionID, Offset, RelType, Value);
1766 }
1767 return ++RelI;
1768 }
1769
getGOTEntrySize()1770 size_t RuntimeDyldELF::getGOTEntrySize() {
1771 // We don't use the GOT in all of these cases, but it's essentially free
1772 // to put them all here.
1773 size_t Result = 0;
1774 switch (Arch) {
1775 case Triple::x86_64:
1776 case Triple::aarch64:
1777 case Triple::aarch64_be:
1778 case Triple::ppc64:
1779 case Triple::ppc64le:
1780 case Triple::systemz:
1781 Result = sizeof(uint64_t);
1782 break;
1783 case Triple::x86:
1784 case Triple::arm:
1785 case Triple::thumb:
1786 Result = sizeof(uint32_t);
1787 break;
1788 case Triple::mips:
1789 case Triple::mipsel:
1790 case Triple::mips64:
1791 case Triple::mips64el:
1792 if (IsMipsO32ABI || IsMipsN32ABI)
1793 Result = sizeof(uint32_t);
1794 else if (IsMipsN64ABI)
1795 Result = sizeof(uint64_t);
1796 else
1797 llvm_unreachable("Mips ABI not handled");
1798 break;
1799 default:
1800 llvm_unreachable("Unsupported CPU type!");
1801 }
1802 return Result;
1803 }
1804
allocateGOTEntries(unsigned no)1805 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) {
1806 if (GOTSectionID == 0) {
1807 GOTSectionID = Sections.size();
1808 // Reserve a section id. We'll allocate the section later
1809 // once we know the total size
1810 Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
1811 }
1812 uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1813 CurrentGOTIndex += no;
1814 return StartOffset;
1815 }
1816
findOrAllocGOTEntry(const RelocationValueRef & Value,unsigned GOTRelType)1817 uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value,
1818 unsigned GOTRelType) {
1819 auto E = GOTOffsetMap.insert({Value, 0});
1820 if (E.second) {
1821 uint64_t GOTOffset = allocateGOTEntries(1);
1822
1823 // Create relocation for newly created GOT entry
1824 RelocationEntry RE =
1825 computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType);
1826 if (Value.SymbolName)
1827 addRelocationForSymbol(RE, Value.SymbolName);
1828 else
1829 addRelocationForSection(RE, Value.SectionID);
1830
1831 E.first->second = GOTOffset;
1832 }
1833
1834 return E.first->second;
1835 }
1836
resolveGOTOffsetRelocation(unsigned SectionID,uint64_t Offset,uint64_t GOTOffset,uint32_t Type)1837 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID,
1838 uint64_t Offset,
1839 uint64_t GOTOffset,
1840 uint32_t Type) {
1841 // Fill in the relative address of the GOT Entry into the stub
1842 RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset);
1843 addRelocationForSection(GOTRE, GOTSectionID);
1844 }
1845
computeGOTOffsetRE(uint64_t GOTOffset,uint64_t SymbolOffset,uint32_t Type)1846 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset,
1847 uint64_t SymbolOffset,
1848 uint32_t Type) {
1849 return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1850 }
1851
finalizeLoad(const ObjectFile & Obj,ObjSectionToIDMap & SectionMap)1852 Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1853 ObjSectionToIDMap &SectionMap) {
1854 if (IsMipsO32ABI)
1855 if (!PendingRelocs.empty())
1856 return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
1857
1858 // If necessary, allocate the global offset table
1859 if (GOTSectionID != 0) {
1860 // Allocate memory for the section
1861 size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1862 uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1863 GOTSectionID, ".got", false);
1864 if (!Addr)
1865 return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!");
1866
1867 Sections[GOTSectionID] =
1868 SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
1869
1870 // For now, initialize all GOT entries to zero. We'll fill them in as
1871 // needed when GOT-based relocations are applied.
1872 memset(Addr, 0, TotalSize);
1873 if (IsMipsN32ABI || IsMipsN64ABI) {
1874 // To correctly resolve Mips GOT relocations, we need a mapping from
1875 // object's sections to GOTs.
1876 for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1877 SI != SE; ++SI) {
1878 if (SI->relocation_begin() != SI->relocation_end()) {
1879 Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
1880 if (!RelSecOrErr)
1881 return make_error<RuntimeDyldError>(
1882 toString(RelSecOrErr.takeError()));
1883
1884 section_iterator RelocatedSection = *RelSecOrErr;
1885 ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1886 assert (i != SectionMap.end());
1887 SectionToGOTMap[i->second] = GOTSectionID;
1888 }
1889 }
1890 GOTSymbolOffsets.clear();
1891 }
1892 }
1893
1894 // Look for and record the EH frame section.
1895 ObjSectionToIDMap::iterator i, e;
1896 for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1897 const SectionRef &Section = i->first;
1898
1899 StringRef Name;
1900 Expected<StringRef> NameOrErr = Section.getName();
1901 if (NameOrErr)
1902 Name = *NameOrErr;
1903 else
1904 consumeError(NameOrErr.takeError());
1905
1906 if (Name == ".eh_frame") {
1907 UnregisteredEHFrameSections.push_back(i->second);
1908 break;
1909 }
1910 }
1911
1912 GOTSectionID = 0;
1913 CurrentGOTIndex = 0;
1914
1915 return Error::success();
1916 }
1917
isCompatibleFile(const object::ObjectFile & Obj) const1918 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1919 return Obj.isELF();
1920 }
1921
relocationNeedsGot(const RelocationRef & R) const1922 bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const {
1923 unsigned RelTy = R.getType();
1924 if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
1925 return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE ||
1926 RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC;
1927
1928 if (Arch == Triple::x86_64)
1929 return RelTy == ELF::R_X86_64_GOTPCREL ||
1930 RelTy == ELF::R_X86_64_GOTPCRELX ||
1931 RelTy == ELF::R_X86_64_GOT64 ||
1932 RelTy == ELF::R_X86_64_REX_GOTPCRELX;
1933 return false;
1934 }
1935
relocationNeedsStub(const RelocationRef & R) const1936 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
1937 if (Arch != Triple::x86_64)
1938 return true; // Conservative answer
1939
1940 switch (R.getType()) {
1941 default:
1942 return true; // Conservative answer
1943
1944
1945 case ELF::R_X86_64_GOTPCREL:
1946 case ELF::R_X86_64_GOTPCRELX:
1947 case ELF::R_X86_64_REX_GOTPCRELX:
1948 case ELF::R_X86_64_GOTPC64:
1949 case ELF::R_X86_64_GOT64:
1950 case ELF::R_X86_64_GOTOFF64:
1951 case ELF::R_X86_64_PC32:
1952 case ELF::R_X86_64_PC64:
1953 case ELF::R_X86_64_64:
1954 // We know that these reloation types won't need a stub function. This list
1955 // can be extended as needed.
1956 return false;
1957 }
1958 }
1959
1960 } // namespace llvm
1961