1 //===---- MachO_arm64.cpp - JIT linker implementation for MachO/arm64 -----===//
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 // MachO/arm64 jit-link implementation.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/ExecutionEngine/JITLink/MachO_arm64.h"
14 
15 #include "BasicGOTAndStubsBuilder.h"
16 #include "MachOLinkGraphBuilder.h"
17 
18 #define DEBUG_TYPE "jitlink"
19 
20 using namespace llvm;
21 using namespace llvm::jitlink;
22 using namespace llvm::jitlink::MachO_arm64_Edges;
23 
24 namespace {
25 
26 class MachOLinkGraphBuilder_arm64 : public MachOLinkGraphBuilder {
27 public:
28   MachOLinkGraphBuilder_arm64(const object::MachOObjectFile &Obj)
29       : MachOLinkGraphBuilder(Obj),
30         NumSymbols(Obj.getSymtabLoadCommand().nsyms) {}
31 
32 private:
33   static Expected<MachOARM64RelocationKind>
34   getRelocationKind(const MachO::relocation_info &RI) {
35     switch (RI.r_type) {
36     case MachO::ARM64_RELOC_UNSIGNED:
37       if (!RI.r_pcrel) {
38         if (RI.r_length == 3)
39           return RI.r_extern ? Pointer64 : Pointer64Anon;
40         else if (RI.r_length == 2)
41           return Pointer32;
42       }
43       break;
44     case MachO::ARM64_RELOC_SUBTRACTOR:
45       // SUBTRACTOR must be non-pc-rel, extern, with length 2 or 3.
46       // Initially represent SUBTRACTOR relocations with 'Delta<W>'.
47       // They may be turned into NegDelta<W> by parsePairRelocation.
48       if (!RI.r_pcrel && RI.r_extern) {
49         if (RI.r_length == 2)
50           return Delta32;
51         else if (RI.r_length == 3)
52           return Delta64;
53       }
54       break;
55     case MachO::ARM64_RELOC_BRANCH26:
56       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
57         return Branch26;
58       break;
59     case MachO::ARM64_RELOC_PAGE21:
60       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
61         return Page21;
62       break;
63     case MachO::ARM64_RELOC_PAGEOFF12:
64       if (!RI.r_pcrel && RI.r_extern && RI.r_length == 2)
65         return PageOffset12;
66       break;
67     case MachO::ARM64_RELOC_GOT_LOAD_PAGE21:
68       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
69         return GOTPage21;
70       break;
71     case MachO::ARM64_RELOC_GOT_LOAD_PAGEOFF12:
72       if (!RI.r_pcrel && RI.r_extern && RI.r_length == 2)
73         return GOTPageOffset12;
74       break;
75     case MachO::ARM64_RELOC_POINTER_TO_GOT:
76       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
77         return PointerToGOT;
78       break;
79     case MachO::ARM64_RELOC_ADDEND:
80       if (!RI.r_pcrel && !RI.r_extern && RI.r_length == 2)
81         return PairedAddend;
82       break;
83     }
84 
85     return make_error<JITLinkError>(
86         "Unsupported arm64 relocation: address=" +
87         formatv("{0:x8}", RI.r_address) +
88         ", symbolnum=" + formatv("{0:x6}", RI.r_symbolnum) +
89         ", kind=" + formatv("{0:x1}", RI.r_type) +
90         ", pc_rel=" + (RI.r_pcrel ? "true" : "false") +
91         ", extern=" + (RI.r_extern ? "true" : "false") +
92         ", length=" + formatv("{0:d}", RI.r_length));
93   }
94 
95   using PairRelocInfo =
96       std::tuple<MachOARM64RelocationKind, Symbol *, uint64_t>;
97 
98   // Parses paired SUBTRACTOR/UNSIGNED relocations and, on success,
99   // returns the edge kind and addend to be used.
100   Expected<PairRelocInfo>
101   parsePairRelocation(Block &BlockToFix, Edge::Kind SubtractorKind,
102                       const MachO::relocation_info &SubRI,
103                       JITTargetAddress FixupAddress, const char *FixupContent,
104                       object::relocation_iterator &UnsignedRelItr,
105                       object::relocation_iterator &RelEnd) {
106     using namespace support;
107 
108     assert(((SubtractorKind == Delta32 && SubRI.r_length == 2) ||
109             (SubtractorKind == Delta64 && SubRI.r_length == 3)) &&
110            "Subtractor kind should match length");
111     assert(SubRI.r_extern && "SUBTRACTOR reloc symbol should be extern");
112     assert(!SubRI.r_pcrel && "SUBTRACTOR reloc should not be PCRel");
113 
114     if (UnsignedRelItr == RelEnd)
115       return make_error<JITLinkError>("arm64 SUBTRACTOR without paired "
116                                       "UNSIGNED relocation");
117 
118     auto UnsignedRI = getRelocationInfo(UnsignedRelItr);
119 
120     if (SubRI.r_address != UnsignedRI.r_address)
121       return make_error<JITLinkError>("arm64 SUBTRACTOR and paired UNSIGNED "
122                                       "point to different addresses");
123 
124     if (SubRI.r_length != UnsignedRI.r_length)
125       return make_error<JITLinkError>("length of arm64 SUBTRACTOR and paired "
126                                       "UNSIGNED reloc must match");
127 
128     Symbol *FromSymbol;
129     if (auto FromSymbolOrErr = findSymbolByIndex(SubRI.r_symbolnum))
130       FromSymbol = FromSymbolOrErr->GraphSymbol;
131     else
132       return FromSymbolOrErr.takeError();
133 
134     // Read the current fixup value.
135     uint64_t FixupValue = 0;
136     if (SubRI.r_length == 3)
137       FixupValue = *(const little64_t *)FixupContent;
138     else
139       FixupValue = *(const little32_t *)FixupContent;
140 
141     // Find 'ToSymbol' using symbol number or address, depending on whether the
142     // paired UNSIGNED relocation is extern.
143     Symbol *ToSymbol = nullptr;
144     if (UnsignedRI.r_extern) {
145       // Find target symbol by symbol index.
146       if (auto ToSymbolOrErr = findSymbolByIndex(UnsignedRI.r_symbolnum))
147         ToSymbol = ToSymbolOrErr->GraphSymbol;
148       else
149         return ToSymbolOrErr.takeError();
150     } else {
151       if (auto ToSymbolOrErr = findSymbolByAddress(FixupValue))
152         ToSymbol = &*ToSymbolOrErr;
153       else
154         return ToSymbolOrErr.takeError();
155       FixupValue -= ToSymbol->getAddress();
156     }
157 
158     MachOARM64RelocationKind DeltaKind;
159     Symbol *TargetSymbol;
160     uint64_t Addend;
161     if (&BlockToFix == &FromSymbol->getAddressable()) {
162       TargetSymbol = ToSymbol;
163       DeltaKind = (SubRI.r_length == 3) ? Delta64 : Delta32;
164       Addend = FixupValue + (FixupAddress - FromSymbol->getAddress());
165       // FIXME: handle extern 'from'.
166     } else if (&BlockToFix == &ToSymbol->getAddressable()) {
167       TargetSymbol = &*FromSymbol;
168       DeltaKind = (SubRI.r_length == 3) ? NegDelta64 : NegDelta32;
169       Addend = FixupValue - (FixupAddress - ToSymbol->getAddress());
170     } else {
171       // BlockToFix was neither FromSymbol nor ToSymbol.
172       return make_error<JITLinkError>("SUBTRACTOR relocation must fix up "
173                                       "either 'A' or 'B' (or a symbol in one "
174                                       "of their alt-entry groups)");
175     }
176 
177     return PairRelocInfo(DeltaKind, TargetSymbol, Addend);
178   }
179 
180   Error addRelocations() override {
181     using namespace support;
182     auto &Obj = getObject();
183 
184     for (auto &S : Obj.sections()) {
185 
186       JITTargetAddress SectionAddress = S.getAddress();
187 
188       for (auto RelItr = S.relocation_begin(), RelEnd = S.relocation_end();
189            RelItr != RelEnd; ++RelItr) {
190 
191         MachO::relocation_info RI = getRelocationInfo(RelItr);
192 
193         // Sanity check the relocation kind.
194         auto Kind = getRelocationKind(RI);
195         if (!Kind)
196           return Kind.takeError();
197 
198         // Find the address of the value to fix up.
199         JITTargetAddress FixupAddress = SectionAddress + (uint32_t)RI.r_address;
200 
201         LLVM_DEBUG({
202           dbgs() << "Processing " << getMachOARM64RelocationKindName(*Kind)
203                  << " relocation at " << format("0x%016" PRIx64, FixupAddress)
204                  << "\n";
205         });
206 
207         // Find the block that the fixup points to.
208         Block *BlockToFix = nullptr;
209         {
210           auto SymbolToFixOrErr = findSymbolByAddress(FixupAddress);
211           if (!SymbolToFixOrErr)
212             return SymbolToFixOrErr.takeError();
213           BlockToFix = &SymbolToFixOrErr->getBlock();
214         }
215 
216         if (FixupAddress + static_cast<JITTargetAddress>(1ULL << RI.r_length) >
217             BlockToFix->getAddress() + BlockToFix->getContent().size())
218           return make_error<JITLinkError>(
219               "Relocation content extends past end of fixup block");
220 
221         // Get a pointer to the fixup content.
222         const char *FixupContent = BlockToFix->getContent().data() +
223                                    (FixupAddress - BlockToFix->getAddress());
224 
225         // The target symbol and addend will be populated by the switch below.
226         Symbol *TargetSymbol = nullptr;
227         uint64_t Addend = 0;
228 
229         if (*Kind == PairedAddend) {
230           // If this is an Addend relocation then process it and move to the
231           // paired reloc.
232 
233           Addend = RI.r_symbolnum;
234 
235           if (RelItr == RelEnd)
236             return make_error<JITLinkError>("Unpaired Addend reloc at " +
237                                             formatv("{0:x16}", FixupAddress));
238           ++RelItr;
239           RI = getRelocationInfo(RelItr);
240 
241           Kind = getRelocationKind(RI);
242           if (!Kind)
243             return Kind.takeError();
244 
245           if (*Kind != Branch26 && *Kind != Page21 && *Kind != PageOffset12)
246             return make_error<JITLinkError>(
247                 "Invalid relocation pair: Addend + " +
248                 getMachOARM64RelocationKindName(*Kind));
249           else
250             LLVM_DEBUG({
251               dbgs() << "  pair is " << getMachOARM64RelocationKindName(*Kind)
252                      << "`\n";
253             });
254 
255           // Find the address of the value to fix up.
256           JITTargetAddress PairedFixupAddress =
257               SectionAddress + (uint32_t)RI.r_address;
258           if (PairedFixupAddress != FixupAddress)
259             return make_error<JITLinkError>("Paired relocation points at "
260                                             "different target");
261         }
262 
263         switch (*Kind) {
264         case Branch26: {
265           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
266             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
267           else
268             return TargetSymbolOrErr.takeError();
269           uint32_t Instr = *(const ulittle32_t *)FixupContent;
270           if ((Instr & 0x7fffffff) != 0x14000000)
271             return make_error<JITLinkError>("BRANCH26 target is not a B or BL "
272                                             "instruction with a zero addend");
273           break;
274         }
275         case Pointer32:
276           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
277             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
278           else
279             return TargetSymbolOrErr.takeError();
280           Addend = *(const ulittle32_t *)FixupContent;
281           break;
282         case Pointer64:
283           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
284             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
285           else
286             return TargetSymbolOrErr.takeError();
287           Addend = *(const ulittle64_t *)FixupContent;
288           break;
289         case Pointer64Anon: {
290           JITTargetAddress TargetAddress = *(const ulittle64_t *)FixupContent;
291           if (auto TargetSymbolOrErr = findSymbolByAddress(TargetAddress))
292             TargetSymbol = &*TargetSymbolOrErr;
293           else
294             return TargetSymbolOrErr.takeError();
295           Addend = TargetAddress - TargetSymbol->getAddress();
296           break;
297         }
298         case Page21:
299         case GOTPage21: {
300           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
301             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
302           else
303             return TargetSymbolOrErr.takeError();
304           uint32_t Instr = *(const ulittle32_t *)FixupContent;
305           if ((Instr & 0xffffffe0) != 0x90000000)
306             return make_error<JITLinkError>("PAGE21/GOTPAGE21 target is not an "
307                                             "ADRP instruction with a zero "
308                                             "addend");
309           break;
310         }
311         case PageOffset12: {
312           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
313             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
314           else
315             return TargetSymbolOrErr.takeError();
316           break;
317         }
318         case GOTPageOffset12: {
319           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
320             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
321           else
322             return TargetSymbolOrErr.takeError();
323           uint32_t Instr = *(const ulittle32_t *)FixupContent;
324           if ((Instr & 0xfffffc00) != 0xf9400000)
325             return make_error<JITLinkError>("GOTPAGEOFF12 target is not an LDR "
326                                             "immediate instruction with a zero "
327                                             "addend");
328           break;
329         }
330         case PointerToGOT:
331           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
332             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
333           else
334             return TargetSymbolOrErr.takeError();
335           break;
336         case Delta32:
337         case Delta64: {
338           // We use Delta32/Delta64 to represent SUBTRACTOR relocations.
339           // parsePairRelocation handles the paired reloc, and returns the
340           // edge kind to be used (either Delta32/Delta64, or
341           // NegDelta32/NegDelta64, depending on the direction of the
342           // subtraction) along with the addend.
343           auto PairInfo =
344               parsePairRelocation(*BlockToFix, *Kind, RI, FixupAddress,
345                                   FixupContent, ++RelItr, RelEnd);
346           if (!PairInfo)
347             return PairInfo.takeError();
348           std::tie(*Kind, TargetSymbol, Addend) = *PairInfo;
349           assert(TargetSymbol && "No target symbol from parsePairRelocation?");
350           break;
351         }
352         default:
353           llvm_unreachable("Special relocation kind should not appear in "
354                            "mach-o file");
355         }
356 
357         LLVM_DEBUG({
358           Edge GE(*Kind, FixupAddress - BlockToFix->getAddress(), *TargetSymbol,
359                   Addend);
360           printEdge(dbgs(), *BlockToFix, GE,
361                     getMachOARM64RelocationKindName(*Kind));
362           dbgs() << "\n";
363         });
364         BlockToFix->addEdge(*Kind, FixupAddress - BlockToFix->getAddress(),
365                             *TargetSymbol, Addend);
366       }
367     }
368     return Error::success();
369   }
370 
371   unsigned NumSymbols = 0;
372 };
373 
374 class MachO_arm64_GOTAndStubsBuilder
375     : public BasicGOTAndStubsBuilder<MachO_arm64_GOTAndStubsBuilder> {
376 public:
377   MachO_arm64_GOTAndStubsBuilder(LinkGraph &G)
378       : BasicGOTAndStubsBuilder<MachO_arm64_GOTAndStubsBuilder>(G) {}
379 
380   bool isGOTEdge(Edge &E) const {
381     return E.getKind() == GOTPage21 || E.getKind() == GOTPageOffset12 ||
382            E.getKind() == PointerToGOT;
383   }
384 
385   Symbol &createGOTEntry(Symbol &Target) {
386     auto &GOTEntryBlock = G.createContentBlock(
387         getGOTSection(), getGOTEntryBlockContent(), 0, 8, 0);
388     GOTEntryBlock.addEdge(Pointer64, 0, Target, 0);
389     return G.addAnonymousSymbol(GOTEntryBlock, 0, 8, false, false);
390   }
391 
392   void fixGOTEdge(Edge &E, Symbol &GOTEntry) {
393     if (E.getKind() == GOTPage21 || E.getKind() == GOTPageOffset12) {
394       // Update the target, but leave the edge addend as-is.
395       E.setTarget(GOTEntry);
396     } else if (E.getKind() == PointerToGOT) {
397       E.setTarget(GOTEntry);
398       E.setKind(Delta32);
399     } else
400       llvm_unreachable("Not a GOT edge?");
401   }
402 
403   bool isExternalBranchEdge(Edge &E) {
404     return E.getKind() == Branch26 && !E.getTarget().isDefined();
405   }
406 
407   Symbol &createStub(Symbol &Target) {
408     auto &StubContentBlock =
409         G.createContentBlock(getStubsSection(), getStubBlockContent(), 0, 1, 0);
410     // Re-use GOT entries for stub targets.
411     auto &GOTEntrySymbol = getGOTEntrySymbol(Target);
412     StubContentBlock.addEdge(LDRLiteral19, 0, GOTEntrySymbol, 0);
413     return G.addAnonymousSymbol(StubContentBlock, 0, 8, true, false);
414   }
415 
416   void fixExternalBranchEdge(Edge &E, Symbol &Stub) {
417     assert(E.getKind() == Branch26 && "Not a Branch32 edge?");
418     assert(E.getAddend() == 0 && "Branch32 edge has non-zero addend?");
419     E.setTarget(Stub);
420   }
421 
422 private:
423   Section &getGOTSection() {
424     if (!GOTSection)
425       GOTSection = &G.createSection("$__GOT", sys::Memory::MF_READ);
426     return *GOTSection;
427   }
428 
429   Section &getStubsSection() {
430     if (!StubsSection) {
431       auto StubsProt = static_cast<sys::Memory::ProtectionFlags>(
432           sys::Memory::MF_READ | sys::Memory::MF_EXEC);
433       StubsSection = &G.createSection("$__STUBS", StubsProt);
434     }
435     return *StubsSection;
436   }
437 
438   StringRef getGOTEntryBlockContent() {
439     return StringRef(reinterpret_cast<const char *>(NullGOTEntryContent),
440                      sizeof(NullGOTEntryContent));
441   }
442 
443   StringRef getStubBlockContent() {
444     return StringRef(reinterpret_cast<const char *>(StubContent),
445                      sizeof(StubContent));
446   }
447 
448   static const uint8_t NullGOTEntryContent[8];
449   static const uint8_t StubContent[8];
450   Section *GOTSection = nullptr;
451   Section *StubsSection = nullptr;
452 };
453 
454 const uint8_t MachO_arm64_GOTAndStubsBuilder::NullGOTEntryContent[8] = {
455     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
456 const uint8_t MachO_arm64_GOTAndStubsBuilder::StubContent[8] = {
457     0x10, 0x00, 0x00, 0x58, // LDR x16, <literal>
458     0x00, 0x02, 0x1f, 0xd6  // BR  x16
459 };
460 
461 } // namespace
462 
463 namespace llvm {
464 namespace jitlink {
465 
466 class MachOJITLinker_arm64 : public JITLinker<MachOJITLinker_arm64> {
467   friend class JITLinker<MachOJITLinker_arm64>;
468 
469 public:
470   MachOJITLinker_arm64(std::unique_ptr<JITLinkContext> Ctx,
471                        PassConfiguration PassConfig)
472       : JITLinker(std::move(Ctx), std::move(PassConfig)) {}
473 
474 private:
475   StringRef getEdgeKindName(Edge::Kind R) const override {
476     return getMachOARM64RelocationKindName(R);
477   }
478 
479   Expected<std::unique_ptr<LinkGraph>>
480   buildGraph(MemoryBufferRef ObjBuffer) override {
481     auto MachOObj = object::ObjectFile::createMachOObjectFile(ObjBuffer);
482     if (!MachOObj)
483       return MachOObj.takeError();
484     return MachOLinkGraphBuilder_arm64(**MachOObj).buildGraph();
485   }
486 
487   static Error targetOutOfRangeError(const Block &B, const Edge &E) {
488     std::string ErrMsg;
489     {
490       raw_string_ostream ErrStream(ErrMsg);
491       ErrStream << "Relocation target out of range: ";
492       printEdge(ErrStream, B, E, getMachOARM64RelocationKindName(E.getKind()));
493       ErrStream << "\n";
494     }
495     return make_error<JITLinkError>(std::move(ErrMsg));
496   }
497 
498   static unsigned getPageOffset12Shift(uint32_t Instr) {
499     constexpr uint32_t LDRLiteralMask = 0x3ffffc00;
500 
501     // Check for a GPR LDR immediate with a zero embedded literal.
502     // If found, the top two bits contain the shift.
503     if ((Instr & LDRLiteralMask) == 0x39400000)
504       return Instr >> 30;
505 
506     // Check for a Neon LDR immediate of size 64-bit or less with a zero
507     // embedded literal. If found, the top two bits contain the shift.
508     if ((Instr & LDRLiteralMask) == 0x3d400000)
509       return Instr >> 30;
510 
511     // Check for a Neon LDR immediate of size 128-bit with a zero embedded
512     // literal.
513     constexpr uint32_t SizeBitsMask = 0xc0000000;
514     if ((Instr & (LDRLiteralMask | SizeBitsMask)) == 0x3dc00000)
515       return 4;
516 
517     return 0;
518   }
519 
520   Error applyFixup(Block &B, const Edge &E, char *BlockWorkingMem) const {
521     using namespace support;
522 
523     char *FixupPtr = BlockWorkingMem + E.getOffset();
524     JITTargetAddress FixupAddress = B.getAddress() + E.getOffset();
525 
526     switch (E.getKind()) {
527     case Branch26: {
528       assert((FixupAddress & 0x3) == 0 && "Branch-inst is not 32-bit aligned");
529 
530       int64_t Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
531 
532       if (static_cast<uint64_t>(Value) & 0x3)
533         return make_error<JITLinkError>("Branch26 target is not 32-bit "
534                                         "aligned");
535 
536       if (Value < -(1 << 27) || Value > ((1 << 27) - 1))
537         return targetOutOfRangeError(B, E);
538 
539       uint32_t RawInstr = *(little32_t *)FixupPtr;
540       assert((RawInstr & 0x7fffffff) == 0x14000000 &&
541              "RawInstr isn't a B or BR immediate instruction");
542       uint32_t Imm = (static_cast<uint32_t>(Value) & ((1 << 28) - 1)) >> 2;
543       uint32_t FixedInstr = RawInstr | Imm;
544       *(little32_t *)FixupPtr = FixedInstr;
545       break;
546     }
547     case Pointer32: {
548       uint64_t Value = E.getTarget().getAddress() + E.getAddend();
549       if (Value > std::numeric_limits<uint32_t>::max())
550         return targetOutOfRangeError(B, E);
551       *(ulittle32_t *)FixupPtr = Value;
552       break;
553     }
554     case Pointer64:
555     case Pointer64Anon: {
556       uint64_t Value = E.getTarget().getAddress() + E.getAddend();
557       *(ulittle64_t *)FixupPtr = Value;
558       break;
559     }
560     case Page21:
561     case GOTPage21: {
562       assert(E.getAddend() == 0 && "PAGE21/GOTPAGE21 with non-zero addend");
563       uint64_t TargetPage =
564           E.getTarget().getAddress() & ~static_cast<uint64_t>(4096 - 1);
565       uint64_t PCPage = B.getAddress() & ~static_cast<uint64_t>(4096 - 1);
566 
567       int64_t PageDelta = TargetPage - PCPage;
568       if (PageDelta < -(1 << 30) || PageDelta > ((1 << 30) - 1))
569         return targetOutOfRangeError(B, E);
570 
571       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
572       assert((RawInstr & 0xffffffe0) == 0x90000000 &&
573              "RawInstr isn't an ADRP instruction");
574       uint32_t ImmLo = (static_cast<uint64_t>(PageDelta) >> 12) & 0x3;
575       uint32_t ImmHi = (static_cast<uint64_t>(PageDelta) >> 14) & 0x7ffff;
576       uint32_t FixedInstr = RawInstr | (ImmLo << 29) | (ImmHi << 5);
577       *(ulittle32_t *)FixupPtr = FixedInstr;
578       break;
579     }
580     case PageOffset12: {
581       assert(E.getAddend() == 0 && "PAGEOFF12 with non-zero addend");
582       uint64_t TargetOffset = E.getTarget().getAddress() & 0xfff;
583 
584       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
585       unsigned ImmShift = getPageOffset12Shift(RawInstr);
586 
587       if (TargetOffset & ((1 << ImmShift) - 1))
588         return make_error<JITLinkError>("PAGEOFF12 target is not aligned");
589 
590       uint32_t EncodedImm = (TargetOffset >> ImmShift) << 10;
591       uint32_t FixedInstr = RawInstr | EncodedImm;
592       *(ulittle32_t *)FixupPtr = FixedInstr;
593       break;
594     }
595     case GOTPageOffset12: {
596       assert(E.getAddend() == 0 && "GOTPAGEOF12 with non-zero addend");
597 
598       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
599       assert((RawInstr & 0xfffffc00) == 0xf9400000 &&
600              "RawInstr isn't a 64-bit LDR immediate");
601 
602       uint32_t TargetOffset = E.getTarget().getAddress() & 0xfff;
603       assert((TargetOffset & 0x7) == 0 && "GOT entry is not 8-byte aligned");
604       uint32_t EncodedImm = (TargetOffset >> 3) << 10;
605       uint32_t FixedInstr = RawInstr | EncodedImm;
606       *(ulittle32_t *)FixupPtr = FixedInstr;
607       break;
608     }
609     case LDRLiteral19: {
610       assert((FixupAddress & 0x3) == 0 && "LDR is not 32-bit aligned");
611       assert(E.getAddend() == 0 && "LDRLiteral19 with non-zero addend");
612       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
613       assert(RawInstr == 0x58000010 && "RawInstr isn't a 64-bit LDR literal");
614       int64_t Delta = E.getTarget().getAddress() - FixupAddress;
615       if (Delta & 0x3)
616         return make_error<JITLinkError>("LDR literal target is not 32-bit "
617                                         "aligned");
618       if (Delta < -(1 << 20) || Delta > ((1 << 20) - 1))
619         return targetOutOfRangeError(B, E);
620 
621       uint32_t EncodedImm = (static_cast<uint32_t>(Delta) >> 2) << 5;
622       uint32_t FixedInstr = RawInstr | EncodedImm;
623       *(ulittle32_t *)FixupPtr = FixedInstr;
624       break;
625     }
626     case Delta32:
627     case Delta64:
628     case NegDelta32:
629     case NegDelta64: {
630       int64_t Value;
631       if (E.getKind() == Delta32 || E.getKind() == Delta64)
632         Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
633       else
634         Value = FixupAddress - E.getTarget().getAddress() + E.getAddend();
635 
636       if (E.getKind() == Delta32 || E.getKind() == NegDelta32) {
637         if (Value < std::numeric_limits<int32_t>::min() ||
638             Value > std::numeric_limits<int32_t>::max())
639           return targetOutOfRangeError(B, E);
640         *(little32_t *)FixupPtr = Value;
641       } else
642         *(little64_t *)FixupPtr = Value;
643       break;
644     }
645     default:
646       llvm_unreachable("Unrecognized edge kind");
647     }
648 
649     return Error::success();
650   }
651 
652   uint64_t NullValue = 0;
653 };
654 
655 void jitLink_MachO_arm64(std::unique_ptr<JITLinkContext> Ctx) {
656   PassConfiguration Config;
657   Triple TT("arm64-apple-ios");
658 
659   if (Ctx->shouldAddDefaultTargetPasses(TT)) {
660     // Add a mark-live pass.
661     if (auto MarkLive = Ctx->getMarkLivePass(TT))
662       Config.PrePrunePasses.push_back(std::move(MarkLive));
663     else
664       Config.PrePrunePasses.push_back(markAllSymbolsLive);
665 
666     // Add an in-place GOT/Stubs pass.
667     Config.PostPrunePasses.push_back([](LinkGraph &G) -> Error {
668       MachO_arm64_GOTAndStubsBuilder(G).run();
669       return Error::success();
670     });
671   }
672 
673   if (auto Err = Ctx->modifyPassConfig(TT, Config))
674     return Ctx->notifyFailed(std::move(Err));
675 
676   // Construct a JITLinker and run the link function.
677   MachOJITLinker_arm64::link(std::move(Ctx), std::move(Config));
678 }
679 
680 StringRef getMachOARM64RelocationKindName(Edge::Kind R) {
681   switch (R) {
682   case Branch26:
683     return "Branch26";
684   case Pointer64:
685     return "Pointer64";
686   case Pointer64Anon:
687     return "Pointer64Anon";
688   case Page21:
689     return "Page21";
690   case PageOffset12:
691     return "PageOffset12";
692   case GOTPage21:
693     return "GOTPage21";
694   case GOTPageOffset12:
695     return "GOTPageOffset12";
696   case PointerToGOT:
697     return "PointerToGOT";
698   case PairedAddend:
699     return "PairedAddend";
700   case LDRLiteral19:
701     return "LDRLiteral19";
702   case Delta32:
703     return "Delta32";
704   case Delta64:
705     return "Delta64";
706   case NegDelta32:
707     return "NegDelta32";
708   case NegDelta64:
709     return "NegDelta64";
710   default:
711     return getGenericEdgeKindName(static_cast<Edge::Kind>(R));
712   }
713 }
714 
715 } // end namespace jitlink
716 } // end namespace llvm
717