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 "MachOLinkGraphBuilder.h"
16 #include "PerGraphGOTAndPLTStubsBuilder.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, Triple("arm64-apple-darwin"),
30                               getMachOARM64RelocationKindName),
31         NumSymbols(Obj.getSymtabLoadCommand().nsyms) {}
32 
33 private:
34   static Expected<MachOARM64RelocationKind>
35   getRelocationKind(const MachO::relocation_info &RI) {
36     switch (RI.r_type) {
37     case MachO::ARM64_RELOC_UNSIGNED:
38       if (!RI.r_pcrel) {
39         if (RI.r_length == 3)
40           return RI.r_extern ? Pointer64 : Pointer64Anon;
41         else if (RI.r_length == 2)
42           return Pointer32;
43       }
44       break;
45     case MachO::ARM64_RELOC_SUBTRACTOR:
46       // SUBTRACTOR must be non-pc-rel, extern, with length 2 or 3.
47       // Initially represent SUBTRACTOR relocations with 'Delta<W>'.
48       // They may be turned into NegDelta<W> by parsePairRelocation.
49       if (!RI.r_pcrel && RI.r_extern) {
50         if (RI.r_length == 2)
51           return Delta32;
52         else if (RI.r_length == 3)
53           return Delta64;
54       }
55       break;
56     case MachO::ARM64_RELOC_BRANCH26:
57       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
58         return Branch26;
59       break;
60     case MachO::ARM64_RELOC_PAGE21:
61       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
62         return Page21;
63       break;
64     case MachO::ARM64_RELOC_PAGEOFF12:
65       if (!RI.r_pcrel && RI.r_extern && RI.r_length == 2)
66         return PageOffset12;
67       break;
68     case MachO::ARM64_RELOC_GOT_LOAD_PAGE21:
69       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
70         return GOTPage21;
71       break;
72     case MachO::ARM64_RELOC_GOT_LOAD_PAGEOFF12:
73       if (!RI.r_pcrel && RI.r_extern && RI.r_length == 2)
74         return GOTPageOffset12;
75       break;
76     case MachO::ARM64_RELOC_POINTER_TO_GOT:
77       if (RI.r_pcrel && RI.r_extern && RI.r_length == 2)
78         return PointerToGOT;
79       break;
80     case MachO::ARM64_RELOC_ADDEND:
81       if (!RI.r_pcrel && !RI.r_extern && RI.r_length == 2)
82         return PairedAddend;
83       break;
84     }
85 
86     return make_error<JITLinkError>(
87         "Unsupported arm64 relocation: address=" +
88         formatv("{0:x8}", RI.r_address) +
89         ", symbolnum=" + formatv("{0:x6}", RI.r_symbolnum) +
90         ", kind=" + formatv("{0:x1}", RI.r_type) +
91         ", pc_rel=" + (RI.r_pcrel ? "true" : "false") +
92         ", extern=" + (RI.r_extern ? "true" : "false") +
93         ", length=" + formatv("{0:d}", RI.r_length));
94   }
95 
96   using PairRelocInfo =
97       std::tuple<MachOARM64RelocationKind, Symbol *, uint64_t>;
98 
99   // Parses paired SUBTRACTOR/UNSIGNED relocations and, on success,
100   // returns the edge kind and addend to be used.
101   Expected<PairRelocInfo>
102   parsePairRelocation(Block &BlockToFix, Edge::Kind SubtractorKind,
103                       const MachO::relocation_info &SubRI,
104                       JITTargetAddress FixupAddress, const char *FixupContent,
105                       object::relocation_iterator &UnsignedRelItr,
106                       object::relocation_iterator &RelEnd) {
107     using namespace support;
108 
109     assert(((SubtractorKind == Delta32 && SubRI.r_length == 2) ||
110             (SubtractorKind == Delta64 && SubRI.r_length == 3)) &&
111            "Subtractor kind should match length");
112     assert(SubRI.r_extern && "SUBTRACTOR reloc symbol should be extern");
113     assert(!SubRI.r_pcrel && "SUBTRACTOR reloc should not be PCRel");
114 
115     if (UnsignedRelItr == RelEnd)
116       return make_error<JITLinkError>("arm64 SUBTRACTOR without paired "
117                                       "UNSIGNED relocation");
118 
119     auto UnsignedRI = getRelocationInfo(UnsignedRelItr);
120 
121     if (SubRI.r_address != UnsignedRI.r_address)
122       return make_error<JITLinkError>("arm64 SUBTRACTOR and paired UNSIGNED "
123                                       "point to different addresses");
124 
125     if (SubRI.r_length != UnsignedRI.r_length)
126       return make_error<JITLinkError>("length of arm64 SUBTRACTOR and paired "
127                                       "UNSIGNED reloc must match");
128 
129     Symbol *FromSymbol;
130     if (auto FromSymbolOrErr = findSymbolByIndex(SubRI.r_symbolnum))
131       FromSymbol = FromSymbolOrErr->GraphSymbol;
132     else
133       return FromSymbolOrErr.takeError();
134 
135     // Read the current fixup value.
136     uint64_t FixupValue = 0;
137     if (SubRI.r_length == 3)
138       FixupValue = *(const little64_t *)FixupContent;
139     else
140       FixupValue = *(const little32_t *)FixupContent;
141 
142     // Find 'ToSymbol' using symbol number or address, depending on whether the
143     // paired UNSIGNED relocation is extern.
144     Symbol *ToSymbol = nullptr;
145     if (UnsignedRI.r_extern) {
146       // Find target symbol by symbol index.
147       if (auto ToSymbolOrErr = findSymbolByIndex(UnsignedRI.r_symbolnum))
148         ToSymbol = ToSymbolOrErr->GraphSymbol;
149       else
150         return ToSymbolOrErr.takeError();
151     } else {
152       auto ToSymbolSec = findSectionByIndex(UnsignedRI.r_symbolnum - 1);
153       if (!ToSymbolSec)
154         return ToSymbolSec.takeError();
155       ToSymbol = getSymbolByAddress(ToSymbolSec->Address);
156       assert(ToSymbol && "No symbol for section");
157       FixupValue -= ToSymbol->getAddress();
158     }
159 
160     MachOARM64RelocationKind DeltaKind;
161     Symbol *TargetSymbol;
162     uint64_t Addend;
163     if (&BlockToFix == &FromSymbol->getAddressable()) {
164       TargetSymbol = ToSymbol;
165       DeltaKind = (SubRI.r_length == 3) ? Delta64 : Delta32;
166       Addend = FixupValue + (FixupAddress - FromSymbol->getAddress());
167       // FIXME: handle extern 'from'.
168     } else if (&BlockToFix == &ToSymbol->getAddressable()) {
169       TargetSymbol = &*FromSymbol;
170       DeltaKind = (SubRI.r_length == 3) ? NegDelta64 : NegDelta32;
171       Addend = FixupValue - (FixupAddress - ToSymbol->getAddress());
172     } else {
173       // BlockToFix was neither FromSymbol nor ToSymbol.
174       return make_error<JITLinkError>("SUBTRACTOR relocation must fix up "
175                                       "either 'A' or 'B' (or a symbol in one "
176                                       "of their alt-entry groups)");
177     }
178 
179     return PairRelocInfo(DeltaKind, TargetSymbol, Addend);
180   }
181 
182   Error addRelocations() override {
183     using namespace support;
184     auto &Obj = getObject();
185 
186     LLVM_DEBUG(dbgs() << "Processing relocations:\n");
187 
188     for (auto &S : Obj.sections()) {
189 
190       JITTargetAddress SectionAddress = S.getAddress();
191 
192       // Skip relocations virtual sections.
193       if (S.isVirtual()) {
194         if (S.relocation_begin() != S.relocation_end())
195           return make_error<JITLinkError>("Virtual section contains "
196                                           "relocations");
197         continue;
198       }
199 
200       // Skip relocations for debug symbols.
201       {
202         auto &NSec =
203             getSectionByIndex(Obj.getSectionIndex(S.getRawDataRefImpl()));
204         if (!NSec.GraphSection) {
205           LLVM_DEBUG({
206             dbgs() << "  Skipping relocations for MachO section "
207                    << NSec.SegName << "/" << NSec.SectName
208                    << " which has no associated graph section\n";
209           });
210           continue;
211         }
212       }
213 
214       for (auto RelItr = S.relocation_begin(), RelEnd = S.relocation_end();
215            RelItr != RelEnd; ++RelItr) {
216 
217         MachO::relocation_info RI = getRelocationInfo(RelItr);
218 
219         // Sanity check the relocation kind.
220         auto Kind = getRelocationKind(RI);
221         if (!Kind)
222           return Kind.takeError();
223 
224         // Find the address of the value to fix up.
225         JITTargetAddress FixupAddress = SectionAddress + (uint32_t)RI.r_address;
226 
227         LLVM_DEBUG({
228           auto &NSec =
229               getSectionByIndex(Obj.getSectionIndex(S.getRawDataRefImpl()));
230           dbgs() << "  " << NSec.SectName << " + "
231                  << formatv("{0:x8}", RI.r_address) << ":\n";
232         });
233 
234         // Find the block that the fixup points to.
235         Block *BlockToFix = nullptr;
236         {
237           auto SymbolToFixOrErr = findSymbolByAddress(FixupAddress);
238           if (!SymbolToFixOrErr)
239             return SymbolToFixOrErr.takeError();
240           BlockToFix = &SymbolToFixOrErr->getBlock();
241         }
242 
243         if (FixupAddress + static_cast<JITTargetAddress>(1ULL << RI.r_length) >
244             BlockToFix->getAddress() + BlockToFix->getContent().size())
245           return make_error<JITLinkError>(
246               "Relocation content extends past end of fixup block");
247 
248         // Get a pointer to the fixup content.
249         const char *FixupContent = BlockToFix->getContent().data() +
250                                    (FixupAddress - BlockToFix->getAddress());
251 
252         // The target symbol and addend will be populated by the switch below.
253         Symbol *TargetSymbol = nullptr;
254         uint64_t Addend = 0;
255 
256         if (*Kind == PairedAddend) {
257           // If this is an Addend relocation then process it and move to the
258           // paired reloc.
259 
260           Addend = SignExtend64(RI.r_symbolnum, 24);
261 
262           if (RelItr == RelEnd)
263             return make_error<JITLinkError>("Unpaired Addend reloc at " +
264                                             formatv("{0:x16}", FixupAddress));
265           ++RelItr;
266           RI = getRelocationInfo(RelItr);
267 
268           Kind = getRelocationKind(RI);
269           if (!Kind)
270             return Kind.takeError();
271 
272           if (*Kind != Branch26 && *Kind != Page21 && *Kind != PageOffset12)
273             return make_error<JITLinkError>(
274                 "Invalid relocation pair: Addend + " +
275                 StringRef(getMachOARM64RelocationKindName(*Kind)));
276 
277           LLVM_DEBUG({
278             dbgs() << "    Addend: value = " << formatv("{0:x6}", Addend)
279                    << ", pair is " << getMachOARM64RelocationKindName(*Kind)
280                    << "\n";
281           });
282 
283           // Find the address of the value to fix up.
284           JITTargetAddress PairedFixupAddress =
285               SectionAddress + (uint32_t)RI.r_address;
286           if (PairedFixupAddress != FixupAddress)
287             return make_error<JITLinkError>("Paired relocation points at "
288                                             "different target");
289         }
290 
291         switch (*Kind) {
292         case Branch26: {
293           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
294             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
295           else
296             return TargetSymbolOrErr.takeError();
297           uint32_t Instr = *(const ulittle32_t *)FixupContent;
298           if ((Instr & 0x7fffffff) != 0x14000000)
299             return make_error<JITLinkError>("BRANCH26 target is not a B or BL "
300                                             "instruction with a zero addend");
301           break;
302         }
303         case Pointer32:
304           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
305             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
306           else
307             return TargetSymbolOrErr.takeError();
308           Addend = *(const ulittle32_t *)FixupContent;
309           break;
310         case Pointer64:
311           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
312             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
313           else
314             return TargetSymbolOrErr.takeError();
315           Addend = *(const ulittle64_t *)FixupContent;
316           break;
317         case Pointer64Anon: {
318           JITTargetAddress TargetAddress = *(const ulittle64_t *)FixupContent;
319           if (auto TargetSymbolOrErr = findSymbolByAddress(TargetAddress))
320             TargetSymbol = &*TargetSymbolOrErr;
321           else
322             return TargetSymbolOrErr.takeError();
323           Addend = TargetAddress - TargetSymbol->getAddress();
324           break;
325         }
326         case Page21:
327         case GOTPage21: {
328           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
329             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
330           else
331             return TargetSymbolOrErr.takeError();
332           uint32_t Instr = *(const ulittle32_t *)FixupContent;
333           if ((Instr & 0xffffffe0) != 0x90000000)
334             return make_error<JITLinkError>("PAGE21/GOTPAGE21 target is not an "
335                                             "ADRP instruction with a zero "
336                                             "addend");
337           break;
338         }
339         case PageOffset12: {
340           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
341             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
342           else
343             return TargetSymbolOrErr.takeError();
344           uint32_t Instr = *(const ulittle32_t *)FixupContent;
345           uint32_t EncodedAddend = (Instr & 0x003FFC00) >> 10;
346           if (EncodedAddend != 0)
347             return make_error<JITLinkError>("GOTPAGEOFF12 target has non-zero "
348                                             "encoded addend");
349           break;
350         }
351         case GOTPageOffset12: {
352           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
353             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
354           else
355             return TargetSymbolOrErr.takeError();
356           uint32_t Instr = *(const ulittle32_t *)FixupContent;
357           if ((Instr & 0xfffffc00) != 0xf9400000)
358             return make_error<JITLinkError>("GOTPAGEOFF12 target is not an LDR "
359                                             "immediate instruction with a zero "
360                                             "addend");
361           break;
362         }
363         case PointerToGOT:
364           if (auto TargetSymbolOrErr = findSymbolByIndex(RI.r_symbolnum))
365             TargetSymbol = TargetSymbolOrErr->GraphSymbol;
366           else
367             return TargetSymbolOrErr.takeError();
368           break;
369         case Delta32:
370         case Delta64: {
371           // We use Delta32/Delta64 to represent SUBTRACTOR relocations.
372           // parsePairRelocation handles the paired reloc, and returns the
373           // edge kind to be used (either Delta32/Delta64, or
374           // NegDelta32/NegDelta64, depending on the direction of the
375           // subtraction) along with the addend.
376           auto PairInfo =
377               parsePairRelocation(*BlockToFix, *Kind, RI, FixupAddress,
378                                   FixupContent, ++RelItr, RelEnd);
379           if (!PairInfo)
380             return PairInfo.takeError();
381           std::tie(*Kind, TargetSymbol, Addend) = *PairInfo;
382           assert(TargetSymbol && "No target symbol from parsePairRelocation?");
383           break;
384         }
385         default:
386           llvm_unreachable("Special relocation kind should not appear in "
387                            "mach-o file");
388         }
389 
390         LLVM_DEBUG({
391           dbgs() << "    ";
392           Edge GE(*Kind, FixupAddress - BlockToFix->getAddress(), *TargetSymbol,
393                   Addend);
394           printEdge(dbgs(), *BlockToFix, GE,
395                     getMachOARM64RelocationKindName(*Kind));
396           dbgs() << "\n";
397         });
398         BlockToFix->addEdge(*Kind, FixupAddress - BlockToFix->getAddress(),
399                             *TargetSymbol, Addend);
400       }
401     }
402     return Error::success();
403   }
404 
405   unsigned NumSymbols = 0;
406 };
407 
408 class PerGraphGOTAndPLTStubsBuilder_MachO_arm64
409     : public PerGraphGOTAndPLTStubsBuilder<
410           PerGraphGOTAndPLTStubsBuilder_MachO_arm64> {
411 public:
412   using PerGraphGOTAndPLTStubsBuilder<
413       PerGraphGOTAndPLTStubsBuilder_MachO_arm64>::PerGraphGOTAndPLTStubsBuilder;
414 
415   bool isGOTEdgeToFix(Edge &E) const {
416     return E.getKind() == GOTPage21 || E.getKind() == GOTPageOffset12 ||
417            E.getKind() == PointerToGOT;
418   }
419 
420   Symbol &createGOTEntry(Symbol &Target) {
421     auto &GOTEntryBlock = G.createContentBlock(
422         getGOTSection(), getGOTEntryBlockContent(), 0, 8, 0);
423     GOTEntryBlock.addEdge(Pointer64, 0, Target, 0);
424     return G.addAnonymousSymbol(GOTEntryBlock, 0, 8, false, false);
425   }
426 
427   void fixGOTEdge(Edge &E, Symbol &GOTEntry) {
428     if (E.getKind() == GOTPage21 || E.getKind() == GOTPageOffset12) {
429       // Update the target, but leave the edge addend as-is.
430       E.setTarget(GOTEntry);
431     } else if (E.getKind() == PointerToGOT) {
432       E.setTarget(GOTEntry);
433       E.setKind(Delta32);
434     } else
435       llvm_unreachable("Not a GOT edge?");
436   }
437 
438   bool isExternalBranchEdge(Edge &E) {
439     return E.getKind() == Branch26 && !E.getTarget().isDefined();
440   }
441 
442   Symbol &createPLTStub(Symbol &Target) {
443     auto &StubContentBlock =
444         G.createContentBlock(getStubsSection(), getStubBlockContent(), 0, 1, 0);
445     // Re-use GOT entries for stub targets.
446     auto &GOTEntrySymbol = getGOTEntry(Target);
447     StubContentBlock.addEdge(LDRLiteral19, 0, GOTEntrySymbol, 0);
448     return G.addAnonymousSymbol(StubContentBlock, 0, 8, true, false);
449   }
450 
451   void fixPLTEdge(Edge &E, Symbol &Stub) {
452     assert(E.getKind() == Branch26 && "Not a Branch32 edge?");
453     assert(E.getAddend() == 0 && "Branch32 edge has non-zero addend?");
454     E.setTarget(Stub);
455   }
456 
457 private:
458   Section &getGOTSection() {
459     if (!GOTSection)
460       GOTSection = &G.createSection("$__GOT", MemProt::Read);
461     return *GOTSection;
462   }
463 
464   Section &getStubsSection() {
465     if (!StubsSection)
466       StubsSection =
467           &G.createSection("$__STUBS", MemProt::Read | MemProt::Exec);
468     return *StubsSection;
469   }
470 
471   ArrayRef<char> getGOTEntryBlockContent() {
472     return {reinterpret_cast<const char *>(NullGOTEntryContent),
473             sizeof(NullGOTEntryContent)};
474   }
475 
476   ArrayRef<char> getStubBlockContent() {
477     return {reinterpret_cast<const char *>(StubContent), sizeof(StubContent)};
478   }
479 
480   static const uint8_t NullGOTEntryContent[8];
481   static const uint8_t StubContent[8];
482   Section *GOTSection = nullptr;
483   Section *StubsSection = nullptr;
484 };
485 
486 const uint8_t
487     PerGraphGOTAndPLTStubsBuilder_MachO_arm64::NullGOTEntryContent[8] = {
488         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
489 const uint8_t PerGraphGOTAndPLTStubsBuilder_MachO_arm64::StubContent[8] = {
490     0x10, 0x00, 0x00, 0x58, // LDR x16, <literal>
491     0x00, 0x02, 0x1f, 0xd6  // BR  x16
492 };
493 
494 } // namespace
495 
496 namespace llvm {
497 namespace jitlink {
498 
499 class MachOJITLinker_arm64 : public JITLinker<MachOJITLinker_arm64> {
500   friend class JITLinker<MachOJITLinker_arm64>;
501 
502 public:
503   MachOJITLinker_arm64(std::unique_ptr<JITLinkContext> Ctx,
504                        std::unique_ptr<LinkGraph> G,
505                        PassConfiguration PassConfig)
506       : JITLinker(std::move(Ctx), std::move(G), std::move(PassConfig)) {}
507 
508 private:
509 
510   static unsigned getPageOffset12Shift(uint32_t Instr) {
511     constexpr uint32_t LoadStoreImm12Mask = 0x3b000000;
512     constexpr uint32_t Vec128Mask = 0x04800000;
513 
514     if ((Instr & LoadStoreImm12Mask) == 0x39000000) {
515       uint32_t ImplicitShift = Instr >> 30;
516       if (ImplicitShift == 0)
517         if ((Instr & Vec128Mask) == Vec128Mask)
518           ImplicitShift = 4;
519 
520       return ImplicitShift;
521     }
522 
523     return 0;
524   }
525 
526   Error applyFixup(LinkGraph &G, Block &B, const Edge &E) const {
527     using namespace support;
528 
529     char *BlockWorkingMem = B.getAlreadyMutableContent().data();
530     char *FixupPtr = BlockWorkingMem + E.getOffset();
531     JITTargetAddress FixupAddress = B.getAddress() + E.getOffset();
532 
533     switch (E.getKind()) {
534     case Branch26: {
535       assert((FixupAddress & 0x3) == 0 && "Branch-inst is not 32-bit aligned");
536 
537       int64_t Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
538 
539       if (static_cast<uint64_t>(Value) & 0x3)
540         return make_error<JITLinkError>("Branch26 target is not 32-bit "
541                                         "aligned");
542 
543       if (Value < -(1 << 27) || Value > ((1 << 27) - 1))
544         return makeTargetOutOfRangeError(G, B, E);
545 
546       uint32_t RawInstr = *(little32_t *)FixupPtr;
547       assert((RawInstr & 0x7fffffff) == 0x14000000 &&
548              "RawInstr isn't a B or BR immediate instruction");
549       uint32_t Imm = (static_cast<uint32_t>(Value) & ((1 << 28) - 1)) >> 2;
550       uint32_t FixedInstr = RawInstr | Imm;
551       *(little32_t *)FixupPtr = FixedInstr;
552       break;
553     }
554     case Pointer32: {
555       uint64_t Value = E.getTarget().getAddress() + E.getAddend();
556       if (Value > std::numeric_limits<uint32_t>::max())
557         return makeTargetOutOfRangeError(G, B, E);
558       *(ulittle32_t *)FixupPtr = Value;
559       break;
560     }
561     case Pointer64:
562     case Pointer64Anon: {
563       uint64_t Value = E.getTarget().getAddress() + E.getAddend();
564       *(ulittle64_t *)FixupPtr = Value;
565       break;
566     }
567     case Page21:
568     case GOTPage21: {
569       assert((E.getKind() != GOTPage21 || E.getAddend() == 0) &&
570              "GOTPAGE21 with non-zero addend");
571       uint64_t TargetPage =
572           (E.getTarget().getAddress() + E.getAddend()) &
573             ~static_cast<uint64_t>(4096 - 1);
574       uint64_t PCPage = FixupAddress & ~static_cast<uint64_t>(4096 - 1);
575 
576       int64_t PageDelta = TargetPage - PCPage;
577       if (PageDelta < -(1 << 30) || PageDelta > ((1 << 30) - 1))
578         return makeTargetOutOfRangeError(G, B, E);
579 
580       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
581       assert((RawInstr & 0xffffffe0) == 0x90000000 &&
582              "RawInstr isn't an ADRP instruction");
583       uint32_t ImmLo = (static_cast<uint64_t>(PageDelta) >> 12) & 0x3;
584       uint32_t ImmHi = (static_cast<uint64_t>(PageDelta) >> 14) & 0x7ffff;
585       uint32_t FixedInstr = RawInstr | (ImmLo << 29) | (ImmHi << 5);
586       *(ulittle32_t *)FixupPtr = FixedInstr;
587       break;
588     }
589     case PageOffset12: {
590       uint64_t TargetOffset =
591         (E.getTarget().getAddress() + E.getAddend()) & 0xfff;
592 
593       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
594       unsigned ImmShift = getPageOffset12Shift(RawInstr);
595 
596       if (TargetOffset & ((1 << ImmShift) - 1))
597         return make_error<JITLinkError>("PAGEOFF12 target is not aligned");
598 
599       uint32_t EncodedImm = (TargetOffset >> ImmShift) << 10;
600       uint32_t FixedInstr = RawInstr | EncodedImm;
601       *(ulittle32_t *)FixupPtr = FixedInstr;
602       break;
603     }
604     case GOTPageOffset12: {
605       assert(E.getAddend() == 0 && "GOTPAGEOF12 with non-zero addend");
606 
607       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
608       assert((RawInstr & 0xfffffc00) == 0xf9400000 &&
609              "RawInstr isn't a 64-bit LDR immediate");
610 
611       uint32_t TargetOffset = E.getTarget().getAddress() & 0xfff;
612       assert((TargetOffset & 0x7) == 0 && "GOT entry is not 8-byte aligned");
613       uint32_t EncodedImm = (TargetOffset >> 3) << 10;
614       uint32_t FixedInstr = RawInstr | EncodedImm;
615       *(ulittle32_t *)FixupPtr = FixedInstr;
616       break;
617     }
618     case LDRLiteral19: {
619       assert((FixupAddress & 0x3) == 0 && "LDR is not 32-bit aligned");
620       assert(E.getAddend() == 0 && "LDRLiteral19 with non-zero addend");
621       uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
622       assert(RawInstr == 0x58000010 && "RawInstr isn't a 64-bit LDR literal");
623       int64_t Delta = E.getTarget().getAddress() - FixupAddress;
624       if (Delta & 0x3)
625         return make_error<JITLinkError>("LDR literal target is not 32-bit "
626                                         "aligned");
627       if (Delta < -(1 << 20) || Delta > ((1 << 20) - 1))
628         return makeTargetOutOfRangeError(G, B, E);
629 
630       uint32_t EncodedImm =
631         ((static_cast<uint32_t>(Delta) >> 2) & 0x7ffff) << 5;
632       uint32_t FixedInstr = RawInstr | EncodedImm;
633       *(ulittle32_t *)FixupPtr = FixedInstr;
634       break;
635     }
636     case Delta32:
637     case Delta64:
638     case NegDelta32:
639     case NegDelta64: {
640       int64_t Value;
641       if (E.getKind() == Delta32 || E.getKind() == Delta64)
642         Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
643       else
644         Value = FixupAddress - E.getTarget().getAddress() + E.getAddend();
645 
646       if (E.getKind() == Delta32 || E.getKind() == NegDelta32) {
647         if (Value < std::numeric_limits<int32_t>::min() ||
648             Value > std::numeric_limits<int32_t>::max())
649           return makeTargetOutOfRangeError(G, B, E);
650         *(little32_t *)FixupPtr = Value;
651       } else
652         *(little64_t *)FixupPtr = Value;
653       break;
654     }
655     default:
656       llvm_unreachable("Unrecognized edge kind");
657     }
658 
659     return Error::success();
660   }
661 
662   uint64_t NullValue = 0;
663 };
664 
665 Expected<std::unique_ptr<LinkGraph>>
666 createLinkGraphFromMachOObject_arm64(MemoryBufferRef ObjectBuffer) {
667   auto MachOObj = object::ObjectFile::createMachOObjectFile(ObjectBuffer);
668   if (!MachOObj)
669     return MachOObj.takeError();
670   return MachOLinkGraphBuilder_arm64(**MachOObj).buildGraph();
671 }
672 
673 void link_MachO_arm64(std::unique_ptr<LinkGraph> G,
674                       std::unique_ptr<JITLinkContext> Ctx) {
675 
676   PassConfiguration Config;
677 
678   if (Ctx->shouldAddDefaultTargetPasses(G->getTargetTriple())) {
679     // Add a mark-live pass.
680     if (auto MarkLive = Ctx->getMarkLivePass(G->getTargetTriple()))
681       Config.PrePrunePasses.push_back(std::move(MarkLive));
682     else
683       Config.PrePrunePasses.push_back(markAllSymbolsLive);
684 
685     // Add compact unwind splitter pass.
686     Config.PrePrunePasses.push_back(
687         CompactUnwindSplitter("__LD,__compact_unwind"));
688 
689     // Add an in-place GOT/Stubs pass.
690     Config.PostPrunePasses.push_back(
691         PerGraphGOTAndPLTStubsBuilder_MachO_arm64::asPass);
692   }
693 
694   if (auto Err = Ctx->modifyPassConfig(*G, Config))
695     return Ctx->notifyFailed(std::move(Err));
696 
697   // Construct a JITLinker and run the link function.
698   MachOJITLinker_arm64::link(std::move(Ctx), std::move(G), std::move(Config));
699 }
700 
701 const char *getMachOARM64RelocationKindName(Edge::Kind R) {
702   switch (R) {
703   case Branch26:
704     return "Branch26";
705   case Pointer64:
706     return "Pointer64";
707   case Pointer64Anon:
708     return "Pointer64Anon";
709   case Page21:
710     return "Page21";
711   case PageOffset12:
712     return "PageOffset12";
713   case GOTPage21:
714     return "GOTPage21";
715   case GOTPageOffset12:
716     return "GOTPageOffset12";
717   case PointerToGOT:
718     return "PointerToGOT";
719   case PairedAddend:
720     return "PairedAddend";
721   case LDRLiteral19:
722     return "LDRLiteral19";
723   case Delta32:
724     return "Delta32";
725   case Delta64:
726     return "Delta64";
727   case NegDelta32:
728     return "NegDelta32";
729   case NegDelta64:
730     return "NegDelta64";
731   default:
732     return getGenericEdgeKindName(static_cast<Edge::Kind>(R));
733   }
734 }
735 
736 } // end namespace jitlink
737 } // end namespace llvm
738