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_PLT32: {
403 uint64_t Result = Value + Addend - FinalAddress;
404 assert(static_cast<int64_t>(Result) >= INT32_MIN &&
405 static_cast<int64_t>(Result) <= INT32_MAX);
406 write(isBE, TargetPtr, static_cast<uint32_t>(Result));
407 break;
408 }
409 case ELF::R_AARCH64_PREL32: {
410 uint64_t Result = Value + Addend - FinalAddress;
411 assert(static_cast<int64_t>(Result) >= INT32_MIN &&
412 static_cast<int64_t>(Result) <= UINT32_MAX);
413 write(isBE, TargetPtr, static_cast<uint32_t>(Result & 0xffffffffU));
414 break;
415 }
416 case ELF::R_AARCH64_PREL64:
417 write(isBE, TargetPtr, Value + Addend - FinalAddress);
418 break;
419 case ELF::R_AARCH64_CALL26: // fallthrough
420 case ELF::R_AARCH64_JUMP26: {
421 // Operation: S+A-P. Set Call or B immediate value to bits fff_fffc of the
422 // calculation.
423 uint64_t BranchImm = Value + Addend - FinalAddress;
424
425 // "Check that -2^27 <= result < 2^27".
426 assert(isInt<28>(BranchImm));
427 or32le(TargetPtr, (BranchImm & 0x0FFFFFFC) >> 2);
428 break;
429 }
430 case ELF::R_AARCH64_MOVW_UABS_G3:
431 or32le(TargetPtr, ((Value + Addend) & 0xFFFF000000000000) >> 43);
432 break;
433 case ELF::R_AARCH64_MOVW_UABS_G2_NC:
434 or32le(TargetPtr, ((Value + Addend) & 0xFFFF00000000) >> 27);
435 break;
436 case ELF::R_AARCH64_MOVW_UABS_G1_NC:
437 or32le(TargetPtr, ((Value + Addend) & 0xFFFF0000) >> 11);
438 break;
439 case ELF::R_AARCH64_MOVW_UABS_G0_NC:
440 or32le(TargetPtr, ((Value + Addend) & 0xFFFF) << 5);
441 break;
442 case ELF::R_AARCH64_ADR_PREL_PG_HI21: {
443 // Operation: Page(S+A) - Page(P)
444 uint64_t Result =
445 ((Value + Addend) & ~0xfffULL) - (FinalAddress & ~0xfffULL);
446
447 // Check that -2^32 <= X < 2^32
448 assert(isInt<33>(Result) && "overflow check failed for relocation");
449
450 // Immediate goes in bits 30:29 + 5:23 of ADRP instruction, taken
451 // from bits 32:12 of X.
452 write32AArch64Addr(TargetPtr, Result >> 12);
453 break;
454 }
455 case ELF::R_AARCH64_ADD_ABS_LO12_NC:
456 // Operation: S + A
457 // Immediate goes in bits 21:10 of LD/ST instruction, taken
458 // from bits 11:0 of X
459 or32AArch64Imm(TargetPtr, Value + Addend);
460 break;
461 case ELF::R_AARCH64_LDST8_ABS_LO12_NC:
462 // Operation: S + A
463 // Immediate goes in bits 21:10 of LD/ST instruction, taken
464 // from bits 11:0 of X
465 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 0, 11));
466 break;
467 case ELF::R_AARCH64_LDST16_ABS_LO12_NC:
468 // Operation: S + A
469 // Immediate goes in bits 21:10 of LD/ST instruction, taken
470 // from bits 11:1 of X
471 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 1, 11));
472 break;
473 case ELF::R_AARCH64_LDST32_ABS_LO12_NC:
474 // Operation: S + A
475 // Immediate goes in bits 21:10 of LD/ST instruction, taken
476 // from bits 11:2 of X
477 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 2, 11));
478 break;
479 case ELF::R_AARCH64_LDST64_ABS_LO12_NC:
480 // Operation: S + A
481 // Immediate goes in bits 21:10 of LD/ST instruction, taken
482 // from bits 11:3 of X
483 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 3, 11));
484 break;
485 case ELF::R_AARCH64_LDST128_ABS_LO12_NC:
486 // Operation: S + A
487 // Immediate goes in bits 21:10 of LD/ST instruction, taken
488 // from bits 11:4 of X
489 or32AArch64Imm(TargetPtr, getBits(Value + Addend, 4, 11));
490 break;
491 }
492 }
493
resolveARMRelocation(const SectionEntry & Section,uint64_t Offset,uint32_t Value,uint32_t Type,int32_t Addend)494 void RuntimeDyldELF::resolveARMRelocation(const SectionEntry &Section,
495 uint64_t Offset, uint32_t Value,
496 uint32_t Type, int32_t Addend) {
497 // TODO: Add Thumb relocations.
498 uint32_t *TargetPtr =
499 reinterpret_cast<uint32_t *>(Section.getAddressWithOffset(Offset));
500 uint32_t FinalAddress = Section.getLoadAddressWithOffset(Offset) & 0xFFFFFFFF;
501 Value += Addend;
502
503 LLVM_DEBUG(dbgs() << "resolveARMRelocation, LocalAddress: "
504 << Section.getAddressWithOffset(Offset)
505 << " FinalAddress: " << format("%p", FinalAddress)
506 << " Value: " << format("%x", Value)
507 << " Type: " << format("%x", Type)
508 << " Addend: " << format("%x", Addend) << "\n");
509
510 switch (Type) {
511 default:
512 llvm_unreachable("Not implemented relocation type!");
513
514 case ELF::R_ARM_NONE:
515 break;
516 // Write a 31bit signed offset
517 case ELF::R_ARM_PREL31:
518 support::ulittle32_t::ref{TargetPtr} =
519 (support::ulittle32_t::ref{TargetPtr} & 0x80000000) |
520 ((Value - FinalAddress) & ~0x80000000);
521 break;
522 case ELF::R_ARM_TARGET1:
523 case ELF::R_ARM_ABS32:
524 support::ulittle32_t::ref{TargetPtr} = Value;
525 break;
526 // Write first 16 bit of 32 bit value to the mov instruction.
527 // Last 4 bit should be shifted.
528 case ELF::R_ARM_MOVW_ABS_NC:
529 case ELF::R_ARM_MOVT_ABS:
530 if (Type == ELF::R_ARM_MOVW_ABS_NC)
531 Value = Value & 0xFFFF;
532 else if (Type == ELF::R_ARM_MOVT_ABS)
533 Value = (Value >> 16) & 0xFFFF;
534 support::ulittle32_t::ref{TargetPtr} =
535 (support::ulittle32_t::ref{TargetPtr} & ~0x000F0FFF) | (Value & 0xFFF) |
536 (((Value >> 12) & 0xF) << 16);
537 break;
538 // Write 24 bit relative value to the branch instruction.
539 case ELF::R_ARM_PC24: // Fall through.
540 case ELF::R_ARM_CALL: // Fall through.
541 case ELF::R_ARM_JUMP24:
542 int32_t RelValue = static_cast<int32_t>(Value - FinalAddress - 8);
543 RelValue = (RelValue & 0x03FFFFFC) >> 2;
544 assert((support::ulittle32_t::ref{TargetPtr} & 0xFFFFFF) == 0xFFFFFE);
545 support::ulittle32_t::ref{TargetPtr} =
546 (support::ulittle32_t::ref{TargetPtr} & 0xFF000000) | RelValue;
547 break;
548 }
549 }
550
setMipsABI(const ObjectFile & Obj)551 void RuntimeDyldELF::setMipsABI(const ObjectFile &Obj) {
552 if (Arch == Triple::UnknownArch ||
553 !StringRef(Triple::getArchTypePrefix(Arch)).equals("mips")) {
554 IsMipsO32ABI = false;
555 IsMipsN32ABI = false;
556 IsMipsN64ABI = false;
557 return;
558 }
559 if (auto *E = dyn_cast<ELFObjectFileBase>(&Obj)) {
560 unsigned AbiVariant = E->getPlatformFlags();
561 IsMipsO32ABI = AbiVariant & ELF::EF_MIPS_ABI_O32;
562 IsMipsN32ABI = AbiVariant & ELF::EF_MIPS_ABI2;
563 }
564 IsMipsN64ABI = Obj.getFileFormatName().equals("elf64-mips");
565 }
566
567 // Return the .TOC. section and offset.
findPPC64TOCSection(const ELFObjectFileBase & Obj,ObjSectionToIDMap & LocalSections,RelocationValueRef & Rel)568 Error RuntimeDyldELF::findPPC64TOCSection(const ELFObjectFileBase &Obj,
569 ObjSectionToIDMap &LocalSections,
570 RelocationValueRef &Rel) {
571 // Set a default SectionID in case we do not find a TOC section below.
572 // This may happen for references to TOC base base (sym@toc, .odp
573 // relocation) without a .toc directive. In this case just use the
574 // first section (which is usually the .odp) since the code won't
575 // reference the .toc base directly.
576 Rel.SymbolName = nullptr;
577 Rel.SectionID = 0;
578
579 // The TOC consists of sections .got, .toc, .tocbss, .plt in that
580 // order. The TOC starts where the first of these sections starts.
581 for (auto &Section : Obj.sections()) {
582 Expected<StringRef> NameOrErr = Section.getName();
583 if (!NameOrErr)
584 return NameOrErr.takeError();
585 StringRef SectionName = *NameOrErr;
586
587 if (SectionName == ".got"
588 || SectionName == ".toc"
589 || SectionName == ".tocbss"
590 || SectionName == ".plt") {
591 if (auto SectionIDOrErr =
592 findOrEmitSection(Obj, Section, false, LocalSections))
593 Rel.SectionID = *SectionIDOrErr;
594 else
595 return SectionIDOrErr.takeError();
596 break;
597 }
598 }
599
600 // Per the ppc64-elf-linux ABI, The TOC base is TOC value plus 0x8000
601 // thus permitting a full 64 Kbytes segment.
602 Rel.Addend = 0x8000;
603
604 return Error::success();
605 }
606
607 // Returns the sections and offset associated with the ODP entry referenced
608 // by Symbol.
findOPDEntrySection(const ELFObjectFileBase & Obj,ObjSectionToIDMap & LocalSections,RelocationValueRef & Rel)609 Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
610 ObjSectionToIDMap &LocalSections,
611 RelocationValueRef &Rel) {
612 // Get the ELF symbol value (st_value) to compare with Relocation offset in
613 // .opd entries
614 for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
615 si != se; ++si) {
616
617 Expected<section_iterator> RelSecOrErr = si->getRelocatedSection();
618 if (!RelSecOrErr)
619 report_fatal_error(toString(RelSecOrErr.takeError()));
620
621 section_iterator RelSecI = *RelSecOrErr;
622 if (RelSecI == Obj.section_end())
623 continue;
624
625 Expected<StringRef> NameOrErr = RelSecI->getName();
626 if (!NameOrErr)
627 return NameOrErr.takeError();
628 StringRef RelSectionName = *NameOrErr;
629
630 if (RelSectionName != ".opd")
631 continue;
632
633 for (elf_relocation_iterator i = si->relocation_begin(),
634 e = si->relocation_end();
635 i != e;) {
636 // The R_PPC64_ADDR64 relocation indicates the first field
637 // of a .opd entry
638 uint64_t TypeFunc = i->getType();
639 if (TypeFunc != ELF::R_PPC64_ADDR64) {
640 ++i;
641 continue;
642 }
643
644 uint64_t TargetSymbolOffset = i->getOffset();
645 symbol_iterator TargetSymbol = i->getSymbol();
646 int64_t Addend;
647 if (auto AddendOrErr = i->getAddend())
648 Addend = *AddendOrErr;
649 else
650 return AddendOrErr.takeError();
651
652 ++i;
653 if (i == e)
654 break;
655
656 // Just check if following relocation is a R_PPC64_TOC
657 uint64_t TypeTOC = i->getType();
658 if (TypeTOC != ELF::R_PPC64_TOC)
659 continue;
660
661 // Finally compares the Symbol value and the target symbol offset
662 // to check if this .opd entry refers to the symbol the relocation
663 // points to.
664 if (Rel.Addend != (int64_t)TargetSymbolOffset)
665 continue;
666
667 section_iterator TSI = Obj.section_end();
668 if (auto TSIOrErr = TargetSymbol->getSection())
669 TSI = *TSIOrErr;
670 else
671 return TSIOrErr.takeError();
672 assert(TSI != Obj.section_end() && "TSI should refer to a valid section");
673
674 bool IsCode = TSI->isText();
675 if (auto SectionIDOrErr = findOrEmitSection(Obj, *TSI, IsCode,
676 LocalSections))
677 Rel.SectionID = *SectionIDOrErr;
678 else
679 return SectionIDOrErr.takeError();
680 Rel.Addend = (intptr_t)Addend;
681 return Error::success();
682 }
683 }
684 llvm_unreachable("Attempting to get address of ODP entry!");
685 }
686
687 // Relocation masks following the #lo(value), #hi(value), #ha(value),
688 // #higher(value), #highera(value), #highest(value), and #highesta(value)
689 // macros defined in section 4.5.1. Relocation Types of the PPC-elf64abi
690 // document.
691
applyPPClo(uint64_t value)692 static inline uint16_t applyPPClo(uint64_t value) { return value & 0xffff; }
693
applyPPChi(uint64_t value)694 static inline uint16_t applyPPChi(uint64_t value) {
695 return (value >> 16) & 0xffff;
696 }
697
applyPPCha(uint64_t value)698 static inline uint16_t applyPPCha (uint64_t value) {
699 return ((value + 0x8000) >> 16) & 0xffff;
700 }
701
applyPPChigher(uint64_t value)702 static inline uint16_t applyPPChigher(uint64_t value) {
703 return (value >> 32) & 0xffff;
704 }
705
applyPPChighera(uint64_t value)706 static inline uint16_t applyPPChighera (uint64_t value) {
707 return ((value + 0x8000) >> 32) & 0xffff;
708 }
709
applyPPChighest(uint64_t value)710 static inline uint16_t applyPPChighest(uint64_t value) {
711 return (value >> 48) & 0xffff;
712 }
713
applyPPChighesta(uint64_t value)714 static inline uint16_t applyPPChighesta (uint64_t value) {
715 return ((value + 0x8000) >> 48) & 0xffff;
716 }
717
resolvePPC32Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)718 void RuntimeDyldELF::resolvePPC32Relocation(const SectionEntry &Section,
719 uint64_t Offset, uint64_t Value,
720 uint32_t Type, int64_t Addend) {
721 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
722 switch (Type) {
723 default:
724 llvm_unreachable("Relocation type not implemented yet!");
725 break;
726 case ELF::R_PPC_ADDR16_LO:
727 writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
728 break;
729 case ELF::R_PPC_ADDR16_HI:
730 writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
731 break;
732 case ELF::R_PPC_ADDR16_HA:
733 writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
734 break;
735 }
736 }
737
resolvePPC64Relocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)738 void RuntimeDyldELF::resolvePPC64Relocation(const SectionEntry &Section,
739 uint64_t Offset, uint64_t Value,
740 uint32_t Type, int64_t Addend) {
741 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
742 switch (Type) {
743 default:
744 llvm_unreachable("Relocation type not implemented yet!");
745 break;
746 case ELF::R_PPC64_ADDR16:
747 writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
748 break;
749 case ELF::R_PPC64_ADDR16_DS:
750 writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
751 break;
752 case ELF::R_PPC64_ADDR16_LO:
753 writeInt16BE(LocalAddress, applyPPClo(Value + Addend));
754 break;
755 case ELF::R_PPC64_ADDR16_LO_DS:
756 writeInt16BE(LocalAddress, applyPPClo(Value + Addend) & ~3);
757 break;
758 case ELF::R_PPC64_ADDR16_HI:
759 case ELF::R_PPC64_ADDR16_HIGH:
760 writeInt16BE(LocalAddress, applyPPChi(Value + Addend));
761 break;
762 case ELF::R_PPC64_ADDR16_HA:
763 case ELF::R_PPC64_ADDR16_HIGHA:
764 writeInt16BE(LocalAddress, applyPPCha(Value + Addend));
765 break;
766 case ELF::R_PPC64_ADDR16_HIGHER:
767 writeInt16BE(LocalAddress, applyPPChigher(Value + Addend));
768 break;
769 case ELF::R_PPC64_ADDR16_HIGHERA:
770 writeInt16BE(LocalAddress, applyPPChighera(Value + Addend));
771 break;
772 case ELF::R_PPC64_ADDR16_HIGHEST:
773 writeInt16BE(LocalAddress, applyPPChighest(Value + Addend));
774 break;
775 case ELF::R_PPC64_ADDR16_HIGHESTA:
776 writeInt16BE(LocalAddress, applyPPChighesta(Value + Addend));
777 break;
778 case ELF::R_PPC64_ADDR14: {
779 assert(((Value + Addend) & 3) == 0);
780 // Preserve the AA/LK bits in the branch instruction
781 uint8_t aalk = *(LocalAddress + 3);
782 writeInt16BE(LocalAddress + 2, (aalk & 3) | ((Value + Addend) & 0xfffc));
783 } break;
784 case ELF::R_PPC64_REL16_LO: {
785 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
786 uint64_t Delta = Value - FinalAddress + Addend;
787 writeInt16BE(LocalAddress, applyPPClo(Delta));
788 } break;
789 case ELF::R_PPC64_REL16_HI: {
790 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
791 uint64_t Delta = Value - FinalAddress + Addend;
792 writeInt16BE(LocalAddress, applyPPChi(Delta));
793 } break;
794 case ELF::R_PPC64_REL16_HA: {
795 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
796 uint64_t Delta = Value - FinalAddress + Addend;
797 writeInt16BE(LocalAddress, applyPPCha(Delta));
798 } break;
799 case ELF::R_PPC64_ADDR32: {
800 int64_t Result = static_cast<int64_t>(Value + Addend);
801 if (SignExtend64<32>(Result) != Result)
802 llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
803 writeInt32BE(LocalAddress, Result);
804 } break;
805 case ELF::R_PPC64_REL24: {
806 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
807 int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
808 if (SignExtend64<26>(delta) != delta)
809 llvm_unreachable("Relocation R_PPC64_REL24 overflow");
810 // We preserve bits other than LI field, i.e. PO and AA/LK fields.
811 uint32_t Inst = readBytesUnaligned(LocalAddress, 4);
812 writeInt32BE(LocalAddress, (Inst & 0xFC000003) | (delta & 0x03FFFFFC));
813 } break;
814 case ELF::R_PPC64_REL32: {
815 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
816 int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
817 if (SignExtend64<32>(delta) != delta)
818 llvm_unreachable("Relocation R_PPC64_REL32 overflow");
819 writeInt32BE(LocalAddress, delta);
820 } break;
821 case ELF::R_PPC64_REL64: {
822 uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
823 uint64_t Delta = Value - FinalAddress + Addend;
824 writeInt64BE(LocalAddress, Delta);
825 } break;
826 case ELF::R_PPC64_ADDR64:
827 writeInt64BE(LocalAddress, Value + Addend);
828 break;
829 }
830 }
831
resolveSystemZRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)832 void RuntimeDyldELF::resolveSystemZRelocation(const SectionEntry &Section,
833 uint64_t Offset, uint64_t Value,
834 uint32_t Type, int64_t Addend) {
835 uint8_t *LocalAddress = Section.getAddressWithOffset(Offset);
836 switch (Type) {
837 default:
838 llvm_unreachable("Relocation type not implemented yet!");
839 break;
840 case ELF::R_390_PC16DBL:
841 case ELF::R_390_PLT16DBL: {
842 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
843 assert(int16_t(Delta / 2) * 2 == Delta && "R_390_PC16DBL overflow");
844 writeInt16BE(LocalAddress, Delta / 2);
845 break;
846 }
847 case ELF::R_390_PC32DBL:
848 case ELF::R_390_PLT32DBL: {
849 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
850 assert(int32_t(Delta / 2) * 2 == Delta && "R_390_PC32DBL overflow");
851 writeInt32BE(LocalAddress, Delta / 2);
852 break;
853 }
854 case ELF::R_390_PC16: {
855 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
856 assert(int16_t(Delta) == Delta && "R_390_PC16 overflow");
857 writeInt16BE(LocalAddress, Delta);
858 break;
859 }
860 case ELF::R_390_PC32: {
861 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
862 assert(int32_t(Delta) == Delta && "R_390_PC32 overflow");
863 writeInt32BE(LocalAddress, Delta);
864 break;
865 }
866 case ELF::R_390_PC64: {
867 int64_t Delta = (Value + Addend) - Section.getLoadAddressWithOffset(Offset);
868 writeInt64BE(LocalAddress, Delta);
869 break;
870 }
871 case ELF::R_390_8:
872 *LocalAddress = (uint8_t)(Value + Addend);
873 break;
874 case ELF::R_390_16:
875 writeInt16BE(LocalAddress, Value + Addend);
876 break;
877 case ELF::R_390_32:
878 writeInt32BE(LocalAddress, Value + Addend);
879 break;
880 case ELF::R_390_64:
881 writeInt64BE(LocalAddress, Value + Addend);
882 break;
883 }
884 }
885
resolveBPFRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend)886 void RuntimeDyldELF::resolveBPFRelocation(const SectionEntry &Section,
887 uint64_t Offset, uint64_t Value,
888 uint32_t Type, int64_t Addend) {
889 bool isBE = Arch == Triple::bpfeb;
890
891 switch (Type) {
892 default:
893 llvm_unreachable("Relocation type not implemented yet!");
894 break;
895 case ELF::R_BPF_NONE:
896 break;
897 case ELF::R_BPF_64_64: {
898 write(isBE, Section.getAddressWithOffset(Offset), Value + Addend);
899 LLVM_DEBUG(dbgs() << "Writing " << format("%p", (Value + Addend)) << " at "
900 << format("%p\n", Section.getAddressWithOffset(Offset)));
901 break;
902 }
903 case ELF::R_BPF_64_32: {
904 Value += Addend;
905 assert(Value <= UINT32_MAX);
906 write(isBE, Section.getAddressWithOffset(Offset), static_cast<uint32_t>(Value));
907 LLVM_DEBUG(dbgs() << "Writing " << format("%p", Value) << " at "
908 << format("%p\n", Section.getAddressWithOffset(Offset)));
909 break;
910 }
911 }
912 }
913
914 // The target location for the relocation is described by RE.SectionID and
915 // RE.Offset. RE.SectionID can be used to find the SectionEntry. Each
916 // SectionEntry has three members describing its location.
917 // SectionEntry::Address is the address at which the section has been loaded
918 // into memory in the current (host) process. SectionEntry::LoadAddress is the
919 // address that the section will have in the target process.
920 // SectionEntry::ObjAddress is the address of the bits for this section in the
921 // original emitted object image (also in the current address space).
922 //
923 // Relocations will be applied as if the section were loaded at
924 // SectionEntry::LoadAddress, but they will be applied at an address based
925 // on SectionEntry::Address. SectionEntry::ObjAddress will be used to refer to
926 // Target memory contents if they are required for value calculations.
927 //
928 // The Value parameter here is the load address of the symbol for the
929 // relocation to be applied. For relocations which refer to symbols in the
930 // current object Value will be the LoadAddress of the section in which
931 // the symbol resides (RE.Addend provides additional information about the
932 // symbol location). For external symbols, Value will be the address of the
933 // symbol in the target address space.
resolveRelocation(const RelocationEntry & RE,uint64_t Value)934 void RuntimeDyldELF::resolveRelocation(const RelocationEntry &RE,
935 uint64_t Value) {
936 const SectionEntry &Section = Sections[RE.SectionID];
937 return resolveRelocation(Section, RE.Offset, Value, RE.RelType, RE.Addend,
938 RE.SymOffset, RE.SectionID);
939 }
940
resolveRelocation(const SectionEntry & Section,uint64_t Offset,uint64_t Value,uint32_t Type,int64_t Addend,uint64_t SymOffset,SID SectionID)941 void RuntimeDyldELF::resolveRelocation(const SectionEntry &Section,
942 uint64_t Offset, uint64_t Value,
943 uint32_t Type, int64_t Addend,
944 uint64_t SymOffset, SID SectionID) {
945 switch (Arch) {
946 case Triple::x86_64:
947 resolveX86_64Relocation(Section, Offset, Value, Type, Addend, SymOffset);
948 break;
949 case Triple::x86:
950 resolveX86Relocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
951 (uint32_t)(Addend & 0xffffffffL));
952 break;
953 case Triple::aarch64:
954 case Triple::aarch64_be:
955 resolveAArch64Relocation(Section, Offset, Value, Type, Addend);
956 break;
957 case Triple::arm: // Fall through.
958 case Triple::armeb:
959 case Triple::thumb:
960 case Triple::thumbeb:
961 resolveARMRelocation(Section, Offset, (uint32_t)(Value & 0xffffffffL), Type,
962 (uint32_t)(Addend & 0xffffffffL));
963 break;
964 case Triple::ppc:
965 resolvePPC32Relocation(Section, Offset, Value, Type, Addend);
966 break;
967 case Triple::ppc64: // Fall through.
968 case Triple::ppc64le:
969 resolvePPC64Relocation(Section, Offset, Value, Type, Addend);
970 break;
971 case Triple::systemz:
972 resolveSystemZRelocation(Section, Offset, Value, Type, Addend);
973 break;
974 case Triple::bpfel:
975 case Triple::bpfeb:
976 resolveBPFRelocation(Section, Offset, Value, Type, Addend);
977 break;
978 default:
979 llvm_unreachable("Unsupported CPU type!");
980 }
981 }
982
computePlaceholderAddress(unsigned SectionID,uint64_t Offset) const983 void *RuntimeDyldELF::computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const {
984 return (void *)(Sections[SectionID].getObjAddress() + Offset);
985 }
986
processSimpleRelocation(unsigned SectionID,uint64_t Offset,unsigned RelType,RelocationValueRef Value)987 void RuntimeDyldELF::processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value) {
988 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend, Value.Offset);
989 if (Value.SymbolName)
990 addRelocationForSymbol(RE, Value.SymbolName);
991 else
992 addRelocationForSection(RE, Value.SectionID);
993 }
994
getMatchingLoRelocation(uint32_t RelType,bool IsLocal) const995 uint32_t RuntimeDyldELF::getMatchingLoRelocation(uint32_t RelType,
996 bool IsLocal) const {
997 switch (RelType) {
998 case ELF::R_MICROMIPS_GOT16:
999 if (IsLocal)
1000 return ELF::R_MICROMIPS_LO16;
1001 break;
1002 case ELF::R_MICROMIPS_HI16:
1003 return ELF::R_MICROMIPS_LO16;
1004 case ELF::R_MIPS_GOT16:
1005 if (IsLocal)
1006 return ELF::R_MIPS_LO16;
1007 break;
1008 case ELF::R_MIPS_HI16:
1009 return ELF::R_MIPS_LO16;
1010 case ELF::R_MIPS_PCHI16:
1011 return ELF::R_MIPS_PCLO16;
1012 default:
1013 break;
1014 }
1015 return ELF::R_MIPS_NONE;
1016 }
1017
1018 // Sometimes we don't need to create thunk for a branch.
1019 // This typically happens when branch target is located
1020 // in the same object file. In such case target is either
1021 // a weak symbol or symbol in a different executable section.
1022 // This function checks if branch target is located in the
1023 // same object file and if distance between source and target
1024 // fits R_AARCH64_CALL26 relocation. If both conditions are
1025 // met, it emits direct jump to the target and returns true.
1026 // Otherwise false is returned and thunk is created.
resolveAArch64ShortBranch(unsigned SectionID,relocation_iterator RelI,const RelocationValueRef & Value)1027 bool RuntimeDyldELF::resolveAArch64ShortBranch(
1028 unsigned SectionID, relocation_iterator RelI,
1029 const RelocationValueRef &Value) {
1030 uint64_t Address;
1031 if (Value.SymbolName) {
1032 auto Loc = GlobalSymbolTable.find(Value.SymbolName);
1033
1034 // Don't create direct branch for external symbols.
1035 if (Loc == GlobalSymbolTable.end())
1036 return false;
1037
1038 const auto &SymInfo = Loc->second;
1039 Address =
1040 uint64_t(Sections[SymInfo.getSectionID()].getLoadAddressWithOffset(
1041 SymInfo.getOffset()));
1042 } else {
1043 Address = uint64_t(Sections[Value.SectionID].getLoadAddress());
1044 }
1045 uint64_t Offset = RelI->getOffset();
1046 uint64_t SourceAddress = Sections[SectionID].getLoadAddressWithOffset(Offset);
1047
1048 // R_AARCH64_CALL26 requires immediate to be in range -2^27 <= imm < 2^27
1049 // If distance between source and target is out of range then we should
1050 // create thunk.
1051 if (!isInt<28>(Address + Value.Addend - SourceAddress))
1052 return false;
1053
1054 resolveRelocation(Sections[SectionID], Offset, Address, RelI->getType(),
1055 Value.Addend);
1056
1057 return true;
1058 }
1059
resolveAArch64Branch(unsigned SectionID,const RelocationValueRef & Value,relocation_iterator RelI,StubMap & Stubs)1060 void RuntimeDyldELF::resolveAArch64Branch(unsigned SectionID,
1061 const RelocationValueRef &Value,
1062 relocation_iterator RelI,
1063 StubMap &Stubs) {
1064
1065 LLVM_DEBUG(dbgs() << "\t\tThis is an AArch64 branch relocation.");
1066 SectionEntry &Section = Sections[SectionID];
1067
1068 uint64_t Offset = RelI->getOffset();
1069 unsigned RelType = RelI->getType();
1070 // Look for an existing stub.
1071 StubMap::const_iterator i = Stubs.find(Value);
1072 if (i != Stubs.end()) {
1073 resolveRelocation(Section, Offset,
1074 (uint64_t)Section.getAddressWithOffset(i->second),
1075 RelType, 0);
1076 LLVM_DEBUG(dbgs() << " Stub function found\n");
1077 } else if (!resolveAArch64ShortBranch(SectionID, RelI, Value)) {
1078 // Create a new stub function.
1079 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1080 Stubs[Value] = Section.getStubOffset();
1081 uint8_t *StubTargetAddr = createStubFunction(
1082 Section.getAddressWithOffset(Section.getStubOffset()));
1083
1084 RelocationEntry REmovz_g3(SectionID, StubTargetAddr - Section.getAddress(),
1085 ELF::R_AARCH64_MOVW_UABS_G3, Value.Addend);
1086 RelocationEntry REmovk_g2(SectionID,
1087 StubTargetAddr - Section.getAddress() + 4,
1088 ELF::R_AARCH64_MOVW_UABS_G2_NC, Value.Addend);
1089 RelocationEntry REmovk_g1(SectionID,
1090 StubTargetAddr - Section.getAddress() + 8,
1091 ELF::R_AARCH64_MOVW_UABS_G1_NC, Value.Addend);
1092 RelocationEntry REmovk_g0(SectionID,
1093 StubTargetAddr - Section.getAddress() + 12,
1094 ELF::R_AARCH64_MOVW_UABS_G0_NC, Value.Addend);
1095
1096 if (Value.SymbolName) {
1097 addRelocationForSymbol(REmovz_g3, Value.SymbolName);
1098 addRelocationForSymbol(REmovk_g2, Value.SymbolName);
1099 addRelocationForSymbol(REmovk_g1, Value.SymbolName);
1100 addRelocationForSymbol(REmovk_g0, Value.SymbolName);
1101 } else {
1102 addRelocationForSection(REmovz_g3, Value.SectionID);
1103 addRelocationForSection(REmovk_g2, Value.SectionID);
1104 addRelocationForSection(REmovk_g1, Value.SectionID);
1105 addRelocationForSection(REmovk_g0, Value.SectionID);
1106 }
1107 resolveRelocation(Section, Offset,
1108 reinterpret_cast<uint64_t>(Section.getAddressWithOffset(
1109 Section.getStubOffset())),
1110 RelType, 0);
1111 Section.advanceStubOffset(getMaxStubSize());
1112 }
1113 }
1114
1115 Expected<relocation_iterator>
processRelocationRef(unsigned SectionID,relocation_iterator RelI,const ObjectFile & O,ObjSectionToIDMap & ObjSectionToID,StubMap & Stubs)1116 RuntimeDyldELF::processRelocationRef(
1117 unsigned SectionID, relocation_iterator RelI, const ObjectFile &O,
1118 ObjSectionToIDMap &ObjSectionToID, StubMap &Stubs) {
1119 const auto &Obj = cast<ELFObjectFileBase>(O);
1120 uint64_t RelType = RelI->getType();
1121 int64_t Addend = 0;
1122 if (Expected<int64_t> AddendOrErr = ELFRelocationRef(*RelI).getAddend())
1123 Addend = *AddendOrErr;
1124 else
1125 consumeError(AddendOrErr.takeError());
1126 elf_symbol_iterator Symbol = RelI->getSymbol();
1127
1128 // Obtain the symbol name which is referenced in the relocation
1129 StringRef TargetName;
1130 if (Symbol != Obj.symbol_end()) {
1131 if (auto TargetNameOrErr = Symbol->getName())
1132 TargetName = *TargetNameOrErr;
1133 else
1134 return TargetNameOrErr.takeError();
1135 }
1136 LLVM_DEBUG(dbgs() << "\t\tRelType: " << RelType << " Addend: " << Addend
1137 << " TargetName: " << TargetName << "\n");
1138 RelocationValueRef Value;
1139 // First search for the symbol in the local symbol table
1140 SymbolRef::Type SymType = SymbolRef::ST_Unknown;
1141
1142 // Search for the symbol in the global symbol table
1143 RTDyldSymbolTable::const_iterator gsi = GlobalSymbolTable.end();
1144 if (Symbol != Obj.symbol_end()) {
1145 gsi = GlobalSymbolTable.find(TargetName.data());
1146 Expected<SymbolRef::Type> SymTypeOrErr = Symbol->getType();
1147 if (!SymTypeOrErr) {
1148 std::string Buf;
1149 raw_string_ostream OS(Buf);
1150 logAllUnhandledErrors(SymTypeOrErr.takeError(), OS);
1151 OS.flush();
1152 report_fatal_error(Buf);
1153 }
1154 SymType = *SymTypeOrErr;
1155 }
1156 if (gsi != GlobalSymbolTable.end()) {
1157 const auto &SymInfo = gsi->second;
1158 Value.SectionID = SymInfo.getSectionID();
1159 Value.Offset = SymInfo.getOffset();
1160 Value.Addend = SymInfo.getOffset() + Addend;
1161 } else {
1162 switch (SymType) {
1163 case SymbolRef::ST_Debug: {
1164 // TODO: Now ELF SymbolRef::ST_Debug = STT_SECTION, it's not obviously
1165 // and can be changed by another developers. Maybe best way is add
1166 // a new symbol type ST_Section to SymbolRef and use it.
1167 auto SectionOrErr = Symbol->getSection();
1168 if (!SectionOrErr) {
1169 std::string Buf;
1170 raw_string_ostream OS(Buf);
1171 logAllUnhandledErrors(SectionOrErr.takeError(), OS);
1172 OS.flush();
1173 report_fatal_error(Buf);
1174 }
1175 section_iterator si = *SectionOrErr;
1176 if (si == Obj.section_end())
1177 llvm_unreachable("Symbol section not found, bad object file format!");
1178 LLVM_DEBUG(dbgs() << "\t\tThis is section symbol\n");
1179 bool isCode = si->isText();
1180 if (auto SectionIDOrErr = findOrEmitSection(Obj, (*si), isCode,
1181 ObjSectionToID))
1182 Value.SectionID = *SectionIDOrErr;
1183 else
1184 return SectionIDOrErr.takeError();
1185 Value.Addend = Addend;
1186 break;
1187 }
1188 case SymbolRef::ST_Data:
1189 case SymbolRef::ST_Function:
1190 case SymbolRef::ST_Unknown: {
1191 Value.SymbolName = TargetName.data();
1192 Value.Addend = Addend;
1193
1194 // Absolute relocations will have a zero symbol ID (STN_UNDEF), which
1195 // will manifest here as a NULL symbol name.
1196 // We can set this as a valid (but empty) symbol name, and rely
1197 // on addRelocationForSymbol to handle this.
1198 if (!Value.SymbolName)
1199 Value.SymbolName = "";
1200 break;
1201 }
1202 default:
1203 llvm_unreachable("Unresolved symbol type!");
1204 break;
1205 }
1206 }
1207
1208 uint64_t Offset = RelI->getOffset();
1209
1210 LLVM_DEBUG(dbgs() << "\t\tSectionID: " << SectionID << " Offset: " << Offset
1211 << "\n");
1212 if ((Arch == Triple::aarch64 || Arch == Triple::aarch64_be)) {
1213 if (RelType == ELF::R_AARCH64_CALL26 || RelType == ELF::R_AARCH64_JUMP26) {
1214 resolveAArch64Branch(SectionID, Value, RelI, Stubs);
1215 } else if (RelType == ELF::R_AARCH64_ADR_GOT_PAGE) {
1216 // Craete new GOT entry or find existing one. If GOT entry is
1217 // to be created, then we also emit ABS64 relocation for it.
1218 uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1219 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1220 ELF::R_AARCH64_ADR_PREL_PG_HI21);
1221
1222 } else if (RelType == ELF::R_AARCH64_LD64_GOT_LO12_NC) {
1223 uint64_t GOTOffset = findOrAllocGOTEntry(Value, ELF::R_AARCH64_ABS64);
1224 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1225 ELF::R_AARCH64_LDST64_ABS_LO12_NC);
1226 } else {
1227 processSimpleRelocation(SectionID, Offset, RelType, Value);
1228 }
1229 } else if (Arch == Triple::arm) {
1230 if (RelType == ELF::R_ARM_PC24 || RelType == ELF::R_ARM_CALL ||
1231 RelType == ELF::R_ARM_JUMP24) {
1232 // This is an ARM branch relocation, need to use a stub function.
1233 LLVM_DEBUG(dbgs() << "\t\tThis is an ARM branch relocation.\n");
1234 SectionEntry &Section = Sections[SectionID];
1235
1236 // Look for an existing stub.
1237 StubMap::const_iterator i = Stubs.find(Value);
1238 if (i != Stubs.end()) {
1239 resolveRelocation(
1240 Section, Offset,
1241 reinterpret_cast<uint64_t>(Section.getAddressWithOffset(i->second)),
1242 RelType, 0);
1243 LLVM_DEBUG(dbgs() << " Stub function found\n");
1244 } else {
1245 // Create a new stub function.
1246 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1247 Stubs[Value] = Section.getStubOffset();
1248 uint8_t *StubTargetAddr = createStubFunction(
1249 Section.getAddressWithOffset(Section.getStubOffset()));
1250 RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1251 ELF::R_ARM_ABS32, Value.Addend);
1252 if (Value.SymbolName)
1253 addRelocationForSymbol(RE, Value.SymbolName);
1254 else
1255 addRelocationForSection(RE, Value.SectionID);
1256
1257 resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1258 Section.getAddressWithOffset(
1259 Section.getStubOffset())),
1260 RelType, 0);
1261 Section.advanceStubOffset(getMaxStubSize());
1262 }
1263 } else {
1264 uint32_t *Placeholder =
1265 reinterpret_cast<uint32_t*>(computePlaceholderAddress(SectionID, Offset));
1266 if (RelType == ELF::R_ARM_PREL31 || RelType == ELF::R_ARM_TARGET1 ||
1267 RelType == ELF::R_ARM_ABS32) {
1268 Value.Addend += *Placeholder;
1269 } else if (RelType == ELF::R_ARM_MOVW_ABS_NC || RelType == ELF::R_ARM_MOVT_ABS) {
1270 // See ELF for ARM documentation
1271 Value.Addend += (int16_t)((*Placeholder & 0xFFF) | (((*Placeholder >> 16) & 0xF) << 12));
1272 }
1273 processSimpleRelocation(SectionID, Offset, RelType, Value);
1274 }
1275 } else if (IsMipsO32ABI) {
1276 uint8_t *Placeholder = reinterpret_cast<uint8_t *>(
1277 computePlaceholderAddress(SectionID, Offset));
1278 uint32_t Opcode = readBytesUnaligned(Placeholder, 4);
1279 if (RelType == ELF::R_MIPS_26) {
1280 // This is an Mips branch relocation, need to use a stub function.
1281 LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1282 SectionEntry &Section = Sections[SectionID];
1283
1284 // Extract the addend from the instruction.
1285 // We shift up by two since the Value will be down shifted again
1286 // when applying the relocation.
1287 uint32_t Addend = (Opcode & 0x03ffffff) << 2;
1288
1289 Value.Addend += Addend;
1290
1291 // Look up for existing stub.
1292 StubMap::const_iterator i = Stubs.find(Value);
1293 if (i != Stubs.end()) {
1294 RelocationEntry RE(SectionID, Offset, RelType, i->second);
1295 addRelocationForSection(RE, SectionID);
1296 LLVM_DEBUG(dbgs() << " Stub function found\n");
1297 } else {
1298 // Create a new stub function.
1299 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1300 Stubs[Value] = Section.getStubOffset();
1301
1302 unsigned AbiVariant = Obj.getPlatformFlags();
1303
1304 uint8_t *StubTargetAddr = createStubFunction(
1305 Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1306
1307 // Creating Hi and Lo relocations for the filled stub instructions.
1308 RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1309 ELF::R_MIPS_HI16, Value.Addend);
1310 RelocationEntry RELo(SectionID,
1311 StubTargetAddr - Section.getAddress() + 4,
1312 ELF::R_MIPS_LO16, Value.Addend);
1313
1314 if (Value.SymbolName) {
1315 addRelocationForSymbol(REHi, Value.SymbolName);
1316 addRelocationForSymbol(RELo, Value.SymbolName);
1317 } else {
1318 addRelocationForSection(REHi, Value.SectionID);
1319 addRelocationForSection(RELo, Value.SectionID);
1320 }
1321
1322 RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1323 addRelocationForSection(RE, SectionID);
1324 Section.advanceStubOffset(getMaxStubSize());
1325 }
1326 } else if (RelType == ELF::R_MIPS_HI16 || RelType == ELF::R_MIPS_PCHI16) {
1327 int64_t Addend = (Opcode & 0x0000ffff) << 16;
1328 RelocationEntry RE(SectionID, Offset, RelType, Addend);
1329 PendingRelocs.push_back(std::make_pair(Value, RE));
1330 } else if (RelType == ELF::R_MIPS_LO16 || RelType == ELF::R_MIPS_PCLO16) {
1331 int64_t Addend = Value.Addend + SignExtend32<16>(Opcode & 0x0000ffff);
1332 for (auto I = PendingRelocs.begin(); I != PendingRelocs.end();) {
1333 const RelocationValueRef &MatchingValue = I->first;
1334 RelocationEntry &Reloc = I->second;
1335 if (MatchingValue == Value &&
1336 RelType == getMatchingLoRelocation(Reloc.RelType) &&
1337 SectionID == Reloc.SectionID) {
1338 Reloc.Addend += Addend;
1339 if (Value.SymbolName)
1340 addRelocationForSymbol(Reloc, Value.SymbolName);
1341 else
1342 addRelocationForSection(Reloc, Value.SectionID);
1343 I = PendingRelocs.erase(I);
1344 } else
1345 ++I;
1346 }
1347 RelocationEntry RE(SectionID, Offset, RelType, Addend);
1348 if (Value.SymbolName)
1349 addRelocationForSymbol(RE, Value.SymbolName);
1350 else
1351 addRelocationForSection(RE, Value.SectionID);
1352 } else {
1353 if (RelType == ELF::R_MIPS_32)
1354 Value.Addend += Opcode;
1355 else if (RelType == ELF::R_MIPS_PC16)
1356 Value.Addend += SignExtend32<18>((Opcode & 0x0000ffff) << 2);
1357 else if (RelType == ELF::R_MIPS_PC19_S2)
1358 Value.Addend += SignExtend32<21>((Opcode & 0x0007ffff) << 2);
1359 else if (RelType == ELF::R_MIPS_PC21_S2)
1360 Value.Addend += SignExtend32<23>((Opcode & 0x001fffff) << 2);
1361 else if (RelType == ELF::R_MIPS_PC26_S2)
1362 Value.Addend += SignExtend32<28>((Opcode & 0x03ffffff) << 2);
1363 processSimpleRelocation(SectionID, Offset, RelType, Value);
1364 }
1365 } else if (IsMipsN32ABI || IsMipsN64ABI) {
1366 uint32_t r_type = RelType & 0xff;
1367 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1368 if (r_type == ELF::R_MIPS_CALL16 || r_type == ELF::R_MIPS_GOT_PAGE
1369 || r_type == ELF::R_MIPS_GOT_DISP) {
1370 StringMap<uint64_t>::iterator i = GOTSymbolOffsets.find(TargetName);
1371 if (i != GOTSymbolOffsets.end())
1372 RE.SymOffset = i->second;
1373 else {
1374 RE.SymOffset = allocateGOTEntries(1);
1375 GOTSymbolOffsets[TargetName] = RE.SymOffset;
1376 }
1377 if (Value.SymbolName)
1378 addRelocationForSymbol(RE, Value.SymbolName);
1379 else
1380 addRelocationForSection(RE, Value.SectionID);
1381 } else if (RelType == ELF::R_MIPS_26) {
1382 // This is an Mips branch relocation, need to use a stub function.
1383 LLVM_DEBUG(dbgs() << "\t\tThis is a Mips branch relocation.");
1384 SectionEntry &Section = Sections[SectionID];
1385
1386 // Look up for existing stub.
1387 StubMap::const_iterator i = Stubs.find(Value);
1388 if (i != Stubs.end()) {
1389 RelocationEntry RE(SectionID, Offset, RelType, i->second);
1390 addRelocationForSection(RE, SectionID);
1391 LLVM_DEBUG(dbgs() << " Stub function found\n");
1392 } else {
1393 // Create a new stub function.
1394 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1395 Stubs[Value] = Section.getStubOffset();
1396
1397 unsigned AbiVariant = Obj.getPlatformFlags();
1398
1399 uint8_t *StubTargetAddr = createStubFunction(
1400 Section.getAddressWithOffset(Section.getStubOffset()), AbiVariant);
1401
1402 if (IsMipsN32ABI) {
1403 // Creating Hi and Lo relocations for the filled stub instructions.
1404 RelocationEntry REHi(SectionID, StubTargetAddr - Section.getAddress(),
1405 ELF::R_MIPS_HI16, Value.Addend);
1406 RelocationEntry RELo(SectionID,
1407 StubTargetAddr - Section.getAddress() + 4,
1408 ELF::R_MIPS_LO16, Value.Addend);
1409 if (Value.SymbolName) {
1410 addRelocationForSymbol(REHi, Value.SymbolName);
1411 addRelocationForSymbol(RELo, Value.SymbolName);
1412 } else {
1413 addRelocationForSection(REHi, Value.SectionID);
1414 addRelocationForSection(RELo, Value.SectionID);
1415 }
1416 } else {
1417 // Creating Highest, Higher, Hi and Lo relocations for the filled stub
1418 // instructions.
1419 RelocationEntry REHighest(SectionID,
1420 StubTargetAddr - Section.getAddress(),
1421 ELF::R_MIPS_HIGHEST, Value.Addend);
1422 RelocationEntry REHigher(SectionID,
1423 StubTargetAddr - Section.getAddress() + 4,
1424 ELF::R_MIPS_HIGHER, Value.Addend);
1425 RelocationEntry REHi(SectionID,
1426 StubTargetAddr - Section.getAddress() + 12,
1427 ELF::R_MIPS_HI16, Value.Addend);
1428 RelocationEntry RELo(SectionID,
1429 StubTargetAddr - Section.getAddress() + 20,
1430 ELF::R_MIPS_LO16, Value.Addend);
1431 if (Value.SymbolName) {
1432 addRelocationForSymbol(REHighest, Value.SymbolName);
1433 addRelocationForSymbol(REHigher, Value.SymbolName);
1434 addRelocationForSymbol(REHi, Value.SymbolName);
1435 addRelocationForSymbol(RELo, Value.SymbolName);
1436 } else {
1437 addRelocationForSection(REHighest, Value.SectionID);
1438 addRelocationForSection(REHigher, Value.SectionID);
1439 addRelocationForSection(REHi, Value.SectionID);
1440 addRelocationForSection(RELo, Value.SectionID);
1441 }
1442 }
1443 RelocationEntry RE(SectionID, Offset, RelType, Section.getStubOffset());
1444 addRelocationForSection(RE, SectionID);
1445 Section.advanceStubOffset(getMaxStubSize());
1446 }
1447 } else {
1448 processSimpleRelocation(SectionID, Offset, RelType, Value);
1449 }
1450
1451 } else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
1452 if (RelType == ELF::R_PPC64_REL24) {
1453 // Determine ABI variant in use for this object.
1454 unsigned AbiVariant = Obj.getPlatformFlags();
1455 AbiVariant &= ELF::EF_PPC64_ABI;
1456 // A PPC branch relocation will need a stub function if the target is
1457 // an external symbol (either Value.SymbolName is set, or SymType is
1458 // Symbol::ST_Unknown) or if the target address is not within the
1459 // signed 24-bits branch address.
1460 SectionEntry &Section = Sections[SectionID];
1461 uint8_t *Target = Section.getAddressWithOffset(Offset);
1462 bool RangeOverflow = false;
1463 bool IsExtern = Value.SymbolName || SymType == SymbolRef::ST_Unknown;
1464 if (!IsExtern) {
1465 if (AbiVariant != 2) {
1466 // In the ELFv1 ABI, a function call may point to the .opd entry,
1467 // so the final symbol value is calculated based on the relocation
1468 // values in the .opd section.
1469 if (auto Err = findOPDEntrySection(Obj, ObjSectionToID, Value))
1470 return std::move(Err);
1471 } else {
1472 // In the ELFv2 ABI, a function symbol may provide a local entry
1473 // point, which must be used for direct calls.
1474 if (Value.SectionID == SectionID){
1475 uint8_t SymOther = Symbol->getOther();
1476 Value.Addend += ELF::decodePPC64LocalEntryOffset(SymOther);
1477 }
1478 }
1479 uint8_t *RelocTarget =
1480 Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
1481 int64_t delta = static_cast<int64_t>(Target - RelocTarget);
1482 // If it is within 26-bits branch range, just set the branch target
1483 if (SignExtend64<26>(delta) != delta) {
1484 RangeOverflow = true;
1485 } else if ((AbiVariant != 2) ||
1486 (AbiVariant == 2 && Value.SectionID == SectionID)) {
1487 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1488 addRelocationForSection(RE, Value.SectionID);
1489 }
1490 }
1491 if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID) ||
1492 RangeOverflow) {
1493 // It is an external symbol (either Value.SymbolName is set, or
1494 // SymType is SymbolRef::ST_Unknown) or out of range.
1495 StubMap::const_iterator i = Stubs.find(Value);
1496 if (i != Stubs.end()) {
1497 // Symbol function stub already created, just relocate to it
1498 resolveRelocation(Section, Offset,
1499 reinterpret_cast<uint64_t>(
1500 Section.getAddressWithOffset(i->second)),
1501 RelType, 0);
1502 LLVM_DEBUG(dbgs() << " Stub function found\n");
1503 } else {
1504 // Create a new stub function.
1505 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1506 Stubs[Value] = Section.getStubOffset();
1507 uint8_t *StubTargetAddr = createStubFunction(
1508 Section.getAddressWithOffset(Section.getStubOffset()),
1509 AbiVariant);
1510 RelocationEntry RE(SectionID, StubTargetAddr - Section.getAddress(),
1511 ELF::R_PPC64_ADDR64, Value.Addend);
1512
1513 // Generates the 64-bits address loads as exemplified in section
1514 // 4.5.1 in PPC64 ELF ABI. Note that the relocations need to
1515 // apply to the low part of the instructions, so we have to update
1516 // the offset according to the target endianness.
1517 uint64_t StubRelocOffset = StubTargetAddr - Section.getAddress();
1518 if (!IsTargetLittleEndian)
1519 StubRelocOffset += 2;
1520
1521 RelocationEntry REhst(SectionID, StubRelocOffset + 0,
1522 ELF::R_PPC64_ADDR16_HIGHEST, Value.Addend);
1523 RelocationEntry REhr(SectionID, StubRelocOffset + 4,
1524 ELF::R_PPC64_ADDR16_HIGHER, Value.Addend);
1525 RelocationEntry REh(SectionID, StubRelocOffset + 12,
1526 ELF::R_PPC64_ADDR16_HI, Value.Addend);
1527 RelocationEntry REl(SectionID, StubRelocOffset + 16,
1528 ELF::R_PPC64_ADDR16_LO, Value.Addend);
1529
1530 if (Value.SymbolName) {
1531 addRelocationForSymbol(REhst, Value.SymbolName);
1532 addRelocationForSymbol(REhr, Value.SymbolName);
1533 addRelocationForSymbol(REh, Value.SymbolName);
1534 addRelocationForSymbol(REl, Value.SymbolName);
1535 } else {
1536 addRelocationForSection(REhst, Value.SectionID);
1537 addRelocationForSection(REhr, Value.SectionID);
1538 addRelocationForSection(REh, Value.SectionID);
1539 addRelocationForSection(REl, Value.SectionID);
1540 }
1541
1542 resolveRelocation(Section, Offset, reinterpret_cast<uint64_t>(
1543 Section.getAddressWithOffset(
1544 Section.getStubOffset())),
1545 RelType, 0);
1546 Section.advanceStubOffset(getMaxStubSize());
1547 }
1548 if (IsExtern || (AbiVariant == 2 && Value.SectionID != SectionID)) {
1549 // Restore the TOC for external calls
1550 if (AbiVariant == 2)
1551 writeInt32BE(Target + 4, 0xE8410018); // ld r2,24(r1)
1552 else
1553 writeInt32BE(Target + 4, 0xE8410028); // ld r2,40(r1)
1554 }
1555 }
1556 } else if (RelType == ELF::R_PPC64_TOC16 ||
1557 RelType == ELF::R_PPC64_TOC16_DS ||
1558 RelType == ELF::R_PPC64_TOC16_LO ||
1559 RelType == ELF::R_PPC64_TOC16_LO_DS ||
1560 RelType == ELF::R_PPC64_TOC16_HI ||
1561 RelType == ELF::R_PPC64_TOC16_HA) {
1562 // These relocations are supposed to subtract the TOC address from
1563 // the final value. This does not fit cleanly into the RuntimeDyld
1564 // scheme, since there may be *two* sections involved in determining
1565 // the relocation value (the section of the symbol referred to by the
1566 // relocation, and the TOC section associated with the current module).
1567 //
1568 // Fortunately, these relocations are currently only ever generated
1569 // referring to symbols that themselves reside in the TOC, which means
1570 // that the two sections are actually the same. Thus they cancel out
1571 // and we can immediately resolve the relocation right now.
1572 switch (RelType) {
1573 case ELF::R_PPC64_TOC16: RelType = ELF::R_PPC64_ADDR16; break;
1574 case ELF::R_PPC64_TOC16_DS: RelType = ELF::R_PPC64_ADDR16_DS; break;
1575 case ELF::R_PPC64_TOC16_LO: RelType = ELF::R_PPC64_ADDR16_LO; break;
1576 case ELF::R_PPC64_TOC16_LO_DS: RelType = ELF::R_PPC64_ADDR16_LO_DS; break;
1577 case ELF::R_PPC64_TOC16_HI: RelType = ELF::R_PPC64_ADDR16_HI; break;
1578 case ELF::R_PPC64_TOC16_HA: RelType = ELF::R_PPC64_ADDR16_HA; break;
1579 default: llvm_unreachable("Wrong relocation type.");
1580 }
1581
1582 RelocationValueRef TOCValue;
1583 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, TOCValue))
1584 return std::move(Err);
1585 if (Value.SymbolName || Value.SectionID != TOCValue.SectionID)
1586 llvm_unreachable("Unsupported TOC relocation.");
1587 Value.Addend -= TOCValue.Addend;
1588 resolveRelocation(Sections[SectionID], Offset, Value.Addend, RelType, 0);
1589 } else {
1590 // There are two ways to refer to the TOC address directly: either
1591 // via a ELF::R_PPC64_TOC relocation (where both symbol and addend are
1592 // ignored), or via any relocation that refers to the magic ".TOC."
1593 // symbols (in which case the addend is respected).
1594 if (RelType == ELF::R_PPC64_TOC) {
1595 RelType = ELF::R_PPC64_ADDR64;
1596 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1597 return std::move(Err);
1598 } else if (TargetName == ".TOC.") {
1599 if (auto Err = findPPC64TOCSection(Obj, ObjSectionToID, Value))
1600 return std::move(Err);
1601 Value.Addend += Addend;
1602 }
1603
1604 RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
1605
1606 if (Value.SymbolName)
1607 addRelocationForSymbol(RE, Value.SymbolName);
1608 else
1609 addRelocationForSection(RE, Value.SectionID);
1610 }
1611 } else if (Arch == Triple::systemz &&
1612 (RelType == ELF::R_390_PLT32DBL || RelType == ELF::R_390_GOTENT)) {
1613 // Create function stubs for both PLT and GOT references, regardless of
1614 // whether the GOT reference is to data or code. The stub contains the
1615 // full address of the symbol, as needed by GOT references, and the
1616 // executable part only adds an overhead of 8 bytes.
1617 //
1618 // We could try to conserve space by allocating the code and data
1619 // parts of the stub separately. However, as things stand, we allocate
1620 // a stub for every relocation, so using a GOT in JIT code should be
1621 // no less space efficient than using an explicit constant pool.
1622 LLVM_DEBUG(dbgs() << "\t\tThis is a SystemZ indirect relocation.");
1623 SectionEntry &Section = Sections[SectionID];
1624
1625 // Look for an existing stub.
1626 StubMap::const_iterator i = Stubs.find(Value);
1627 uintptr_t StubAddress;
1628 if (i != Stubs.end()) {
1629 StubAddress = uintptr_t(Section.getAddressWithOffset(i->second));
1630 LLVM_DEBUG(dbgs() << " Stub function found\n");
1631 } else {
1632 // Create a new stub function.
1633 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1634
1635 uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1636 uintptr_t StubAlignment = getStubAlignment();
1637 StubAddress =
1638 (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1639 -StubAlignment;
1640 unsigned StubOffset = StubAddress - BaseAddress;
1641
1642 Stubs[Value] = StubOffset;
1643 createStubFunction((uint8_t *)StubAddress);
1644 RelocationEntry RE(SectionID, StubOffset + 8, ELF::R_390_64,
1645 Value.Offset);
1646 if (Value.SymbolName)
1647 addRelocationForSymbol(RE, Value.SymbolName);
1648 else
1649 addRelocationForSection(RE, Value.SectionID);
1650 Section.advanceStubOffset(getMaxStubSize());
1651 }
1652
1653 if (RelType == ELF::R_390_GOTENT)
1654 resolveRelocation(Section, Offset, StubAddress + 8, ELF::R_390_PC32DBL,
1655 Addend);
1656 else
1657 resolveRelocation(Section, Offset, StubAddress, RelType, Addend);
1658 } else if (Arch == Triple::x86_64) {
1659 if (RelType == ELF::R_X86_64_PLT32) {
1660 // The way the PLT relocations normally work is that the linker allocates
1661 // the
1662 // PLT and this relocation makes a PC-relative call into the PLT. The PLT
1663 // entry will then jump to an address provided by the GOT. On first call,
1664 // the
1665 // GOT address will point back into PLT code that resolves the symbol. After
1666 // the first call, the GOT entry points to the actual function.
1667 //
1668 // For local functions we're ignoring all of that here and just replacing
1669 // the PLT32 relocation type with PC32, which will translate the relocation
1670 // into a PC-relative call directly to the function. For external symbols we
1671 // can't be sure the function will be within 2^32 bytes of the call site, so
1672 // we need to create a stub, which calls into the GOT. This case is
1673 // equivalent to the usual PLT implementation except that we use the stub
1674 // mechanism in RuntimeDyld (which puts stubs at the end of the section)
1675 // rather than allocating a PLT section.
1676 if (Value.SymbolName) {
1677 // This is a call to an external function.
1678 // Look for an existing stub.
1679 SectionEntry &Section = Sections[SectionID];
1680 StubMap::const_iterator i = Stubs.find(Value);
1681 uintptr_t StubAddress;
1682 if (i != Stubs.end()) {
1683 StubAddress = uintptr_t(Section.getAddress()) + i->second;
1684 LLVM_DEBUG(dbgs() << " Stub function found\n");
1685 } else {
1686 // Create a new stub function (equivalent to a PLT entry).
1687 LLVM_DEBUG(dbgs() << " Create a new stub function\n");
1688
1689 uintptr_t BaseAddress = uintptr_t(Section.getAddress());
1690 uintptr_t StubAlignment = getStubAlignment();
1691 StubAddress =
1692 (BaseAddress + Section.getStubOffset() + StubAlignment - 1) &
1693 -StubAlignment;
1694 unsigned StubOffset = StubAddress - BaseAddress;
1695 Stubs[Value] = StubOffset;
1696 createStubFunction((uint8_t *)StubAddress);
1697
1698 // Bump our stub offset counter
1699 Section.advanceStubOffset(getMaxStubSize());
1700
1701 // Allocate a GOT Entry
1702 uint64_t GOTOffset = allocateGOTEntries(1);
1703
1704 // The load of the GOT address has an addend of -4
1705 resolveGOTOffsetRelocation(SectionID, StubOffset + 2, GOTOffset - 4,
1706 ELF::R_X86_64_PC32);
1707
1708 // Fill in the value of the symbol we're targeting into the GOT
1709 addRelocationForSymbol(
1710 computeGOTOffsetRE(GOTOffset, 0, ELF::R_X86_64_64),
1711 Value.SymbolName);
1712 }
1713
1714 // Make the target call a call into the stub table.
1715 resolveRelocation(Section, Offset, StubAddress, ELF::R_X86_64_PC32,
1716 Addend);
1717 } else {
1718 RelocationEntry RE(SectionID, Offset, ELF::R_X86_64_PC32, Value.Addend,
1719 Value.Offset);
1720 addRelocationForSection(RE, Value.SectionID);
1721 }
1722 } else if (RelType == ELF::R_X86_64_GOTPCREL ||
1723 RelType == ELF::R_X86_64_GOTPCRELX ||
1724 RelType == ELF::R_X86_64_REX_GOTPCRELX) {
1725 uint64_t GOTOffset = allocateGOTEntries(1);
1726 resolveGOTOffsetRelocation(SectionID, Offset, GOTOffset + Addend,
1727 ELF::R_X86_64_PC32);
1728
1729 // Fill in the value of the symbol we're targeting into the GOT
1730 RelocationEntry RE =
1731 computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1732 if (Value.SymbolName)
1733 addRelocationForSymbol(RE, Value.SymbolName);
1734 else
1735 addRelocationForSection(RE, Value.SectionID);
1736 } else if (RelType == ELF::R_X86_64_GOT64) {
1737 // Fill in a 64-bit GOT offset.
1738 uint64_t GOTOffset = allocateGOTEntries(1);
1739 resolveRelocation(Sections[SectionID], Offset, GOTOffset,
1740 ELF::R_X86_64_64, 0);
1741
1742 // Fill in the value of the symbol we're targeting into the GOT
1743 RelocationEntry RE =
1744 computeGOTOffsetRE(GOTOffset, Value.Offset, ELF::R_X86_64_64);
1745 if (Value.SymbolName)
1746 addRelocationForSymbol(RE, Value.SymbolName);
1747 else
1748 addRelocationForSection(RE, Value.SectionID);
1749 } else if (RelType == ELF::R_X86_64_GOTPC64) {
1750 // Materialize the address of the base of the GOT relative to the PC.
1751 // This doesn't create a GOT entry, but it does mean we need a GOT
1752 // section.
1753 (void)allocateGOTEntries(0);
1754 resolveGOTOffsetRelocation(SectionID, Offset, Addend, ELF::R_X86_64_PC64);
1755 } else if (RelType == ELF::R_X86_64_GOTOFF64) {
1756 // GOTOFF relocations ultimately require a section difference relocation.
1757 (void)allocateGOTEntries(0);
1758 processSimpleRelocation(SectionID, Offset, RelType, Value);
1759 } else if (RelType == ELF::R_X86_64_PC32) {
1760 Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1761 processSimpleRelocation(SectionID, Offset, RelType, Value);
1762 } else if (RelType == ELF::R_X86_64_PC64) {
1763 Value.Addend += support::ulittle64_t::ref(computePlaceholderAddress(SectionID, Offset));
1764 processSimpleRelocation(SectionID, Offset, RelType, Value);
1765 } else {
1766 processSimpleRelocation(SectionID, Offset, RelType, Value);
1767 }
1768 } else {
1769 if (Arch == Triple::x86) {
1770 Value.Addend += support::ulittle32_t::ref(computePlaceholderAddress(SectionID, Offset));
1771 }
1772 processSimpleRelocation(SectionID, Offset, RelType, Value);
1773 }
1774 return ++RelI;
1775 }
1776
getGOTEntrySize()1777 size_t RuntimeDyldELF::getGOTEntrySize() {
1778 // We don't use the GOT in all of these cases, but it's essentially free
1779 // to put them all here.
1780 size_t Result = 0;
1781 switch (Arch) {
1782 case Triple::x86_64:
1783 case Triple::aarch64:
1784 case Triple::aarch64_be:
1785 case Triple::ppc64:
1786 case Triple::ppc64le:
1787 case Triple::systemz:
1788 Result = sizeof(uint64_t);
1789 break;
1790 case Triple::x86:
1791 case Triple::arm:
1792 case Triple::thumb:
1793 Result = sizeof(uint32_t);
1794 break;
1795 case Triple::mips:
1796 case Triple::mipsel:
1797 case Triple::mips64:
1798 case Triple::mips64el:
1799 if (IsMipsO32ABI || IsMipsN32ABI)
1800 Result = sizeof(uint32_t);
1801 else if (IsMipsN64ABI)
1802 Result = sizeof(uint64_t);
1803 else
1804 llvm_unreachable("Mips ABI not handled");
1805 break;
1806 default:
1807 llvm_unreachable("Unsupported CPU type!");
1808 }
1809 return Result;
1810 }
1811
allocateGOTEntries(unsigned no)1812 uint64_t RuntimeDyldELF::allocateGOTEntries(unsigned no) {
1813 if (GOTSectionID == 0) {
1814 GOTSectionID = Sections.size();
1815 // Reserve a section id. We'll allocate the section later
1816 // once we know the total size
1817 Sections.push_back(SectionEntry(".got", nullptr, 0, 0, 0));
1818 }
1819 uint64_t StartOffset = CurrentGOTIndex * getGOTEntrySize();
1820 CurrentGOTIndex += no;
1821 return StartOffset;
1822 }
1823
findOrAllocGOTEntry(const RelocationValueRef & Value,unsigned GOTRelType)1824 uint64_t RuntimeDyldELF::findOrAllocGOTEntry(const RelocationValueRef &Value,
1825 unsigned GOTRelType) {
1826 auto E = GOTOffsetMap.insert({Value, 0});
1827 if (E.second) {
1828 uint64_t GOTOffset = allocateGOTEntries(1);
1829
1830 // Create relocation for newly created GOT entry
1831 RelocationEntry RE =
1832 computeGOTOffsetRE(GOTOffset, Value.Offset, GOTRelType);
1833 if (Value.SymbolName)
1834 addRelocationForSymbol(RE, Value.SymbolName);
1835 else
1836 addRelocationForSection(RE, Value.SectionID);
1837
1838 E.first->second = GOTOffset;
1839 }
1840
1841 return E.first->second;
1842 }
1843
resolveGOTOffsetRelocation(unsigned SectionID,uint64_t Offset,uint64_t GOTOffset,uint32_t Type)1844 void RuntimeDyldELF::resolveGOTOffsetRelocation(unsigned SectionID,
1845 uint64_t Offset,
1846 uint64_t GOTOffset,
1847 uint32_t Type) {
1848 // Fill in the relative address of the GOT Entry into the stub
1849 RelocationEntry GOTRE(SectionID, Offset, Type, GOTOffset);
1850 addRelocationForSection(GOTRE, GOTSectionID);
1851 }
1852
computeGOTOffsetRE(uint64_t GOTOffset,uint64_t SymbolOffset,uint32_t Type)1853 RelocationEntry RuntimeDyldELF::computeGOTOffsetRE(uint64_t GOTOffset,
1854 uint64_t SymbolOffset,
1855 uint32_t Type) {
1856 return RelocationEntry(GOTSectionID, GOTOffset, Type, SymbolOffset);
1857 }
1858
finalizeLoad(const ObjectFile & Obj,ObjSectionToIDMap & SectionMap)1859 Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
1860 ObjSectionToIDMap &SectionMap) {
1861 if (IsMipsO32ABI)
1862 if (!PendingRelocs.empty())
1863 return make_error<RuntimeDyldError>("Can't find matching LO16 reloc");
1864
1865 // If necessary, allocate the global offset table
1866 if (GOTSectionID != 0) {
1867 // Allocate memory for the section
1868 size_t TotalSize = CurrentGOTIndex * getGOTEntrySize();
1869 uint8_t *Addr = MemMgr.allocateDataSection(TotalSize, getGOTEntrySize(),
1870 GOTSectionID, ".got", false);
1871 if (!Addr)
1872 return make_error<RuntimeDyldError>("Unable to allocate memory for GOT!");
1873
1874 Sections[GOTSectionID] =
1875 SectionEntry(".got", Addr, TotalSize, TotalSize, 0);
1876
1877 // For now, initialize all GOT entries to zero. We'll fill them in as
1878 // needed when GOT-based relocations are applied.
1879 memset(Addr, 0, TotalSize);
1880 if (IsMipsN32ABI || IsMipsN64ABI) {
1881 // To correctly resolve Mips GOT relocations, we need a mapping from
1882 // object's sections to GOTs.
1883 for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
1884 SI != SE; ++SI) {
1885 if (SI->relocation_begin() != SI->relocation_end()) {
1886 Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
1887 if (!RelSecOrErr)
1888 return make_error<RuntimeDyldError>(
1889 toString(RelSecOrErr.takeError()));
1890
1891 section_iterator RelocatedSection = *RelSecOrErr;
1892 ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
1893 assert (i != SectionMap.end());
1894 SectionToGOTMap[i->second] = GOTSectionID;
1895 }
1896 }
1897 GOTSymbolOffsets.clear();
1898 }
1899 }
1900
1901 // Look for and record the EH frame section.
1902 ObjSectionToIDMap::iterator i, e;
1903 for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
1904 const SectionRef &Section = i->first;
1905
1906 StringRef Name;
1907 Expected<StringRef> NameOrErr = Section.getName();
1908 if (NameOrErr)
1909 Name = *NameOrErr;
1910 else
1911 consumeError(NameOrErr.takeError());
1912
1913 if (Name == ".eh_frame") {
1914 UnregisteredEHFrameSections.push_back(i->second);
1915 break;
1916 }
1917 }
1918
1919 GOTSectionID = 0;
1920 CurrentGOTIndex = 0;
1921
1922 return Error::success();
1923 }
1924
isCompatibleFile(const object::ObjectFile & Obj) const1925 bool RuntimeDyldELF::isCompatibleFile(const object::ObjectFile &Obj) const {
1926 return Obj.isELF();
1927 }
1928
relocationNeedsGot(const RelocationRef & R) const1929 bool RuntimeDyldELF::relocationNeedsGot(const RelocationRef &R) const {
1930 unsigned RelTy = R.getType();
1931 if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
1932 return RelTy == ELF::R_AARCH64_ADR_GOT_PAGE ||
1933 RelTy == ELF::R_AARCH64_LD64_GOT_LO12_NC;
1934
1935 if (Arch == Triple::x86_64)
1936 return RelTy == ELF::R_X86_64_GOTPCREL ||
1937 RelTy == ELF::R_X86_64_GOTPCRELX ||
1938 RelTy == ELF::R_X86_64_GOT64 ||
1939 RelTy == ELF::R_X86_64_REX_GOTPCRELX;
1940 return false;
1941 }
1942
relocationNeedsStub(const RelocationRef & R) const1943 bool RuntimeDyldELF::relocationNeedsStub(const RelocationRef &R) const {
1944 if (Arch != Triple::x86_64)
1945 return true; // Conservative answer
1946
1947 switch (R.getType()) {
1948 default:
1949 return true; // Conservative answer
1950
1951
1952 case ELF::R_X86_64_GOTPCREL:
1953 case ELF::R_X86_64_GOTPCRELX:
1954 case ELF::R_X86_64_REX_GOTPCRELX:
1955 case ELF::R_X86_64_GOTPC64:
1956 case ELF::R_X86_64_GOT64:
1957 case ELF::R_X86_64_GOTOFF64:
1958 case ELF::R_X86_64_PC32:
1959 case ELF::R_X86_64_PC64:
1960 case ELF::R_X86_64_64:
1961 // We know that these reloation types won't need a stub function. This list
1962 // can be extended as needed.
1963 return false;
1964 }
1965 }
1966
1967 } // namespace llvm
1968