1 //===------ MachOPlatform.cpp - Utilities for executing MachO in Orc ------===//
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 #include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
10 
11 #include "llvm/BinaryFormat/MachO.h"
12 #include "llvm/ExecutionEngine/JITLink/x86_64.h"
13 #include "llvm/ExecutionEngine/Orc/DebugUtils.h"
14 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
15 #include "llvm/ExecutionEngine/Orc/LookupAndRecordAddrs.h"
16 #include "llvm/Support/BinaryByteStream.h"
17 #include "llvm/Support/Debug.h"
18 
19 #define DEBUG_TYPE "orc"
20 
21 using namespace llvm;
22 using namespace llvm::orc;
23 using namespace llvm::orc::shared;
24 
25 namespace {
26 
27 class MachOHeaderMaterializationUnit : public MaterializationUnit {
28 public:
29   MachOHeaderMaterializationUnit(MachOPlatform &MOP,
30                                  const SymbolStringPtr &HeaderStartSymbol)
31       : MaterializationUnit(createHeaderSymbols(MOP, HeaderStartSymbol),
32                             HeaderStartSymbol),
33         MOP(MOP) {}
34 
35   StringRef getName() const override { return "MachOHeaderMU"; }
36 
37   void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
38     unsigned PointerSize;
39     support::endianness Endianness;
40     const auto &TT =
41         MOP.getExecutionSession().getExecutorProcessControl().getTargetTriple();
42 
43     switch (TT.getArch()) {
44     case Triple::aarch64:
45     case Triple::x86_64:
46       PointerSize = 8;
47       Endianness = support::endianness::little;
48       break;
49     default:
50       llvm_unreachable("Unrecognized architecture");
51     }
52 
53     auto G = std::make_unique<jitlink::LinkGraph>(
54         "<MachOHeaderMU>", TT, PointerSize, Endianness,
55         jitlink::getGenericEdgeKindName);
56     auto &HeaderSection = G->createSection("__header", jitlink::MemProt::Read);
57     auto &HeaderBlock = createHeaderBlock(*G, HeaderSection);
58 
59     // Init symbol is header-start symbol.
60     G->addDefinedSymbol(HeaderBlock, 0, *R->getInitializerSymbol(),
61                         HeaderBlock.getSize(), jitlink::Linkage::Strong,
62                         jitlink::Scope::Default, false, true);
63     for (auto &HS : AdditionalHeaderSymbols)
64       G->addDefinedSymbol(HeaderBlock, HS.Offset, HS.Name,
65                           HeaderBlock.getSize(), jitlink::Linkage::Strong,
66                           jitlink::Scope::Default, false, true);
67 
68     MOP.getObjectLinkingLayer().emit(std::move(R), std::move(G));
69   }
70 
71   void discard(const JITDylib &JD, const SymbolStringPtr &Sym) override {}
72 
73 private:
74   struct HeaderSymbol {
75     const char *Name;
76     uint64_t Offset;
77   };
78 
79   static constexpr HeaderSymbol AdditionalHeaderSymbols[] = {
80       {"___mh_executable_header", 0}};
81 
82   static jitlink::Block &createHeaderBlock(jitlink::LinkGraph &G,
83                                            jitlink::Section &HeaderSection) {
84     MachO::mach_header_64 Hdr;
85     Hdr.magic = MachO::MH_MAGIC_64;
86     switch (G.getTargetTriple().getArch()) {
87     case Triple::aarch64:
88       Hdr.cputype = MachO::CPU_TYPE_ARM64;
89       Hdr.cpusubtype = MachO::CPU_SUBTYPE_ARM64_ALL;
90       break;
91     case Triple::x86_64:
92       Hdr.cputype = MachO::CPU_TYPE_X86_64;
93       Hdr.cpusubtype = MachO::CPU_SUBTYPE_X86_64_ALL;
94       break;
95     default:
96       llvm_unreachable("Unrecognized architecture");
97     }
98     Hdr.filetype = MachO::MH_DYLIB; // Custom file type?
99     Hdr.ncmds = 0;
100     Hdr.sizeofcmds = 0;
101     Hdr.flags = 0;
102     Hdr.reserved = 0;
103 
104     if (G.getEndianness() != support::endian::system_endianness())
105       MachO::swapStruct(Hdr);
106 
107     auto HeaderContent = G.allocateString(
108         StringRef(reinterpret_cast<const char *>(&Hdr), sizeof(Hdr)));
109 
110     return G.createContentBlock(HeaderSection, HeaderContent, 0, 8, 0);
111   }
112 
113   static SymbolFlagsMap
114   createHeaderSymbols(MachOPlatform &MOP,
115                       const SymbolStringPtr &HeaderStartSymbol) {
116     SymbolFlagsMap HeaderSymbolFlags;
117 
118     HeaderSymbolFlags[HeaderStartSymbol] = JITSymbolFlags::Exported;
119     for (auto &HS : AdditionalHeaderSymbols)
120       HeaderSymbolFlags[MOP.getExecutionSession().intern(HS.Name)] =
121           JITSymbolFlags::Exported;
122 
123     return HeaderSymbolFlags;
124   }
125 
126   MachOPlatform &MOP;
127 };
128 
129 constexpr MachOHeaderMaterializationUnit::HeaderSymbol
130     MachOHeaderMaterializationUnit::AdditionalHeaderSymbols[];
131 
132 StringRef EHFrameSectionName = "__TEXT,__eh_frame";
133 StringRef ModInitFuncSectionName = "__DATA,__mod_init_func";
134 StringRef ObjCClassListSectionName = "__DATA,__objc_classlist";
135 StringRef ObjCImageInfoSectionName = "__DATA,__objc_image_info";
136 StringRef ObjCSelRefsSectionName = "__DATA,__objc_selrefs";
137 StringRef Swift5ProtoSectionName = "__TEXT,__swift5_proto";
138 StringRef Swift5ProtosSectionName = "__TEXT,__swift5_protos";
139 StringRef ThreadBSSSectionName = "__DATA,__thread_bss";
140 StringRef ThreadDataSectionName = "__DATA,__thread_data";
141 StringRef ThreadVarsSectionName = "__DATA,__thread_vars";
142 
143 StringRef InitSectionNames[] = {
144     ModInitFuncSectionName, ObjCSelRefsSectionName, ObjCClassListSectionName,
145     Swift5ProtosSectionName, Swift5ProtoSectionName};
146 
147 } // end anonymous namespace
148 
149 namespace llvm {
150 namespace orc {
151 
152 Expected<std::unique_ptr<MachOPlatform>>
153 MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
154                       JITDylib &PlatformJD, const char *OrcRuntimePath,
155                       Optional<SymbolAliasMap> RuntimeAliases) {
156 
157   auto &EPC = ES.getExecutorProcessControl();
158 
159   // If the target is not supported then bail out immediately.
160   if (!supportedTarget(EPC.getTargetTriple()))
161     return make_error<StringError>("Unsupported MachOPlatform triple: " +
162                                        EPC.getTargetTriple().str(),
163                                    inconvertibleErrorCode());
164 
165   // Create default aliases if the caller didn't supply any.
166   if (!RuntimeAliases)
167     RuntimeAliases = standardPlatformAliases(ES);
168 
169   // Define the aliases.
170   if (auto Err = PlatformJD.define(symbolAliases(std::move(*RuntimeAliases))))
171     return std::move(Err);
172 
173   // Add JIT-dispatch function support symbols.
174   if (auto Err = PlatformJD.define(absoluteSymbols(
175           {{ES.intern("___orc_rt_jit_dispatch"),
176             {EPC.getJITDispatchInfo().JITDispatchFunction.getValue(),
177              JITSymbolFlags::Exported}},
178            {ES.intern("___orc_rt_jit_dispatch_ctx"),
179             {EPC.getJITDispatchInfo().JITDispatchContext.getValue(),
180              JITSymbolFlags::Exported}}})))
181     return std::move(Err);
182 
183   // Create a generator for the ORC runtime archive.
184   auto OrcRuntimeArchiveGenerator = StaticLibraryDefinitionGenerator::Load(
185       ObjLinkingLayer, OrcRuntimePath, EPC.getTargetTriple());
186   if (!OrcRuntimeArchiveGenerator)
187     return OrcRuntimeArchiveGenerator.takeError();
188 
189   // Create the instance.
190   Error Err = Error::success();
191   auto P = std::unique_ptr<MachOPlatform>(
192       new MachOPlatform(ES, ObjLinkingLayer, PlatformJD,
193                         std::move(*OrcRuntimeArchiveGenerator), Err));
194   if (Err)
195     return std::move(Err);
196   return std::move(P);
197 }
198 
199 Error MachOPlatform::setupJITDylib(JITDylib &JD) {
200   return JD.define(std::make_unique<MachOHeaderMaterializationUnit>(
201       *this, MachOHeaderStartSymbol));
202 }
203 
204 Error MachOPlatform::notifyAdding(ResourceTracker &RT,
205                                   const MaterializationUnit &MU) {
206   auto &JD = RT.getJITDylib();
207   const auto &InitSym = MU.getInitializerSymbol();
208   if (!InitSym)
209     return Error::success();
210 
211   RegisteredInitSymbols[&JD].add(InitSym,
212                                  SymbolLookupFlags::WeaklyReferencedSymbol);
213   LLVM_DEBUG({
214     dbgs() << "MachOPlatform: Registered init symbol " << *InitSym << " for MU "
215            << MU.getName() << "\n";
216   });
217   return Error::success();
218 }
219 
220 Error MachOPlatform::notifyRemoving(ResourceTracker &RT) {
221   llvm_unreachable("Not supported yet");
222 }
223 
224 static void addAliases(ExecutionSession &ES, SymbolAliasMap &Aliases,
225                        ArrayRef<std::pair<const char *, const char *>> AL) {
226   for (auto &KV : AL) {
227     auto AliasName = ES.intern(KV.first);
228     assert(!Aliases.count(AliasName) && "Duplicate symbol name in alias map");
229     Aliases[std::move(AliasName)] = {ES.intern(KV.second),
230                                      JITSymbolFlags::Exported};
231   }
232 }
233 
234 SymbolAliasMap MachOPlatform::standardPlatformAliases(ExecutionSession &ES) {
235   SymbolAliasMap Aliases;
236   addAliases(ES, Aliases, requiredCXXAliases());
237   addAliases(ES, Aliases, standardRuntimeUtilityAliases());
238   return Aliases;
239 }
240 
241 ArrayRef<std::pair<const char *, const char *>>
242 MachOPlatform::requiredCXXAliases() {
243   static const std::pair<const char *, const char *> RequiredCXXAliases[] = {
244       {"___cxa_atexit", "___orc_rt_macho_cxa_atexit"}};
245 
246   return ArrayRef<std::pair<const char *, const char *>>(RequiredCXXAliases);
247 }
248 
249 ArrayRef<std::pair<const char *, const char *>>
250 MachOPlatform::standardRuntimeUtilityAliases() {
251   static const std::pair<const char *, const char *>
252       StandardRuntimeUtilityAliases[] = {
253           {"___orc_rt_run_program", "___orc_rt_macho_run_program"},
254           {"___orc_rt_log_error", "___orc_rt_log_error_to_stderr"}};
255 
256   return ArrayRef<std::pair<const char *, const char *>>(
257       StandardRuntimeUtilityAliases);
258 }
259 
260 bool MachOPlatform::isInitializerSection(StringRef SegName,
261                                          StringRef SectName) {
262   for (auto &Name : InitSectionNames) {
263     if (Name.startswith(SegName) && Name.substr(7) == SectName)
264       return true;
265   }
266   return false;
267 }
268 
269 bool MachOPlatform::supportedTarget(const Triple &TT) {
270   switch (TT.getArch()) {
271   case Triple::x86_64:
272     return true;
273   default:
274     return false;
275   }
276 }
277 
278 MachOPlatform::MachOPlatform(
279     ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
280     JITDylib &PlatformJD,
281     std::unique_ptr<DefinitionGenerator> OrcRuntimeGenerator, Error &Err)
282     : ES(ES), ObjLinkingLayer(ObjLinkingLayer),
283       MachOHeaderStartSymbol(ES.intern("___dso_handle")) {
284   ErrorAsOutParameter _(&Err);
285 
286   ObjLinkingLayer.addPlugin(std::make_unique<MachOPlatformPlugin>(*this));
287 
288   PlatformJD.addGenerator(std::move(OrcRuntimeGenerator));
289 
290   // PlatformJD hasn't been 'set-up' by the platform yet (since we're creating
291   // the platform now), so set it up.
292   if (auto E2 = setupJITDylib(PlatformJD)) {
293     Err = std::move(E2);
294     return;
295   }
296 
297   RegisteredInitSymbols[&PlatformJD].add(
298       MachOHeaderStartSymbol, SymbolLookupFlags::WeaklyReferencedSymbol);
299 
300   // Associate wrapper function tags with JIT-side function implementations.
301   if (auto E2 = associateRuntimeSupportFunctions(PlatformJD)) {
302     Err = std::move(E2);
303     return;
304   }
305 
306   // Lookup addresses of runtime functions callable by the platform,
307   // call the platform bootstrap function to initialize the platform-state
308   // object in the executor.
309   if (auto E2 = bootstrapMachORuntime(PlatformJD)) {
310     Err = std::move(E2);
311     return;
312   }
313 }
314 
315 Error MachOPlatform::associateRuntimeSupportFunctions(JITDylib &PlatformJD) {
316   ExecutionSession::JITDispatchHandlerAssociationMap WFs;
317 
318   using GetInitializersSPSSig =
319       SPSExpected<SPSMachOJITDylibInitializerSequence>(SPSString);
320   WFs[ES.intern("___orc_rt_macho_get_initializers_tag")] =
321       ES.wrapAsyncWithSPS<GetInitializersSPSSig>(
322           this, &MachOPlatform::rt_getInitializers);
323 
324   using GetDeinitializersSPSSig =
325       SPSExpected<SPSMachOJITDylibDeinitializerSequence>(SPSExecutorAddr);
326   WFs[ES.intern("___orc_rt_macho_get_deinitializers_tag")] =
327       ES.wrapAsyncWithSPS<GetDeinitializersSPSSig>(
328           this, &MachOPlatform::rt_getDeinitializers);
329 
330   using LookupSymbolSPSSig =
331       SPSExpected<SPSExecutorAddr>(SPSExecutorAddr, SPSString);
332   WFs[ES.intern("___orc_rt_macho_symbol_lookup_tag")] =
333       ES.wrapAsyncWithSPS<LookupSymbolSPSSig>(this,
334                                               &MachOPlatform::rt_lookupSymbol);
335 
336   return ES.registerJITDispatchHandlers(PlatformJD, std::move(WFs));
337 }
338 
339 void MachOPlatform::getInitializersBuildSequencePhase(
340     SendInitializerSequenceFn SendResult, JITDylib &JD,
341     std::vector<JITDylibSP> DFSLinkOrder) {
342   MachOJITDylibInitializerSequence FullInitSeq;
343   {
344     std::lock_guard<std::mutex> Lock(PlatformMutex);
345     for (auto &InitJD : reverse(DFSLinkOrder)) {
346       LLVM_DEBUG({
347         dbgs() << "MachOPlatform: Appending inits for \"" << InitJD->getName()
348                << "\" to sequence\n";
349       });
350       auto ISItr = InitSeqs.find(InitJD.get());
351       if (ISItr != InitSeqs.end()) {
352         FullInitSeq.emplace_back(std::move(ISItr->second));
353         InitSeqs.erase(ISItr);
354       }
355     }
356   }
357 
358   SendResult(std::move(FullInitSeq));
359 }
360 
361 void MachOPlatform::getInitializersLookupPhase(
362     SendInitializerSequenceFn SendResult, JITDylib &JD) {
363 
364   auto DFSLinkOrder = JD.getDFSLinkOrder();
365   DenseMap<JITDylib *, SymbolLookupSet> NewInitSymbols;
366   ES.runSessionLocked([&]() {
367     for (auto &InitJD : DFSLinkOrder) {
368       auto RISItr = RegisteredInitSymbols.find(InitJD.get());
369       if (RISItr != RegisteredInitSymbols.end()) {
370         NewInitSymbols[InitJD.get()] = std::move(RISItr->second);
371         RegisteredInitSymbols.erase(RISItr);
372       }
373     }
374   });
375 
376   // If there are no further init symbols to look up then move on to the next
377   // phase.
378   if (NewInitSymbols.empty()) {
379     getInitializersBuildSequencePhase(std::move(SendResult), JD,
380                                       std::move(DFSLinkOrder));
381     return;
382   }
383 
384   // Otherwise issue a lookup and re-run this phase when it completes.
385   lookupInitSymbolsAsync(
386       [this, SendResult = std::move(SendResult), &JD](Error Err) mutable {
387         if (Err)
388           SendResult(std::move(Err));
389         else
390           getInitializersLookupPhase(std::move(SendResult), JD);
391       },
392       ES, std::move(NewInitSymbols));
393 }
394 
395 void MachOPlatform::rt_getInitializers(SendInitializerSequenceFn SendResult,
396                                        StringRef JDName) {
397   LLVM_DEBUG({
398     dbgs() << "MachOPlatform::rt_getInitializers(\"" << JDName << "\")\n";
399   });
400 
401   JITDylib *JD = ES.getJITDylibByName(JDName);
402   if (!JD) {
403     LLVM_DEBUG({
404       dbgs() << "  No such JITDylib \"" << JDName << "\". Sending error.\n";
405     });
406     SendResult(make_error<StringError>("No JITDylib named " + JDName,
407                                        inconvertibleErrorCode()));
408     return;
409   }
410 
411   getInitializersLookupPhase(std::move(SendResult), *JD);
412 }
413 
414 void MachOPlatform::rt_getDeinitializers(SendDeinitializerSequenceFn SendResult,
415                                          ExecutorAddr Handle) {
416   LLVM_DEBUG({
417     dbgs() << "MachOPlatform::rt_getDeinitializers(\""
418            << formatv("{0:x}", Handle.getValue()) << "\")\n";
419   });
420 
421   JITDylib *JD = nullptr;
422 
423   {
424     std::lock_guard<std::mutex> Lock(PlatformMutex);
425     auto I = HeaderAddrToJITDylib.find(Handle.getValue());
426     if (I != HeaderAddrToJITDylib.end())
427       JD = I->second;
428   }
429 
430   if (!JD) {
431     LLVM_DEBUG({
432       dbgs() << "  No JITDylib for handle "
433              << formatv("{0:x}", Handle.getValue()) << "\n";
434     });
435     SendResult(make_error<StringError>("No JITDylib associated with handle " +
436                                            formatv("{0:x}", Handle.getValue()),
437                                        inconvertibleErrorCode()));
438     return;
439   }
440 
441   SendResult(MachOJITDylibDeinitializerSequence());
442 }
443 
444 void MachOPlatform::rt_lookupSymbol(SendSymbolAddressFn SendResult,
445                                     ExecutorAddr Handle, StringRef SymbolName) {
446   LLVM_DEBUG({
447     dbgs() << "MachOPlatform::rt_lookupSymbol(\""
448            << formatv("{0:x}", Handle.getValue()) << "\")\n";
449   });
450 
451   JITDylib *JD = nullptr;
452 
453   {
454     std::lock_guard<std::mutex> Lock(PlatformMutex);
455     auto I = HeaderAddrToJITDylib.find(Handle.getValue());
456     if (I != HeaderAddrToJITDylib.end())
457       JD = I->second;
458   }
459 
460   if (!JD) {
461     LLVM_DEBUG({
462       dbgs() << "  No JITDylib for handle "
463              << formatv("{0:x}", Handle.getValue()) << "\n";
464     });
465     SendResult(make_error<StringError>("No JITDylib associated with handle " +
466                                            formatv("{0:x}", Handle.getValue()),
467                                        inconvertibleErrorCode()));
468     return;
469   }
470 
471   // Use functor class to work around XL build compiler issue on AIX.
472   class RtLookupNotifyComplete {
473   public:
474     RtLookupNotifyComplete(SendSymbolAddressFn &&SendResult)
475         : SendResult(std::move(SendResult)) {}
476     void operator()(Expected<SymbolMap> Result) {
477       if (Result) {
478         assert(Result->size() == 1 && "Unexpected result map count");
479         SendResult(ExecutorAddr(Result->begin()->second.getAddress()));
480       } else {
481         SendResult(Result.takeError());
482       }
483     }
484 
485   private:
486     SendSymbolAddressFn SendResult;
487   };
488 
489   // FIXME: Proper mangling.
490   auto MangledName = ("_" + SymbolName).str();
491   ES.lookup(
492       LookupKind::DLSym, {{JD, JITDylibLookupFlags::MatchExportedSymbolsOnly}},
493       SymbolLookupSet(ES.intern(MangledName)), SymbolState::Ready,
494       RtLookupNotifyComplete(std::move(SendResult)), NoDependenciesToRegister);
495 }
496 
497 Error MachOPlatform::bootstrapMachORuntime(JITDylib &PlatformJD) {
498 
499   if (auto Err = lookupAndRecordAddrs(
500           ES, LookupKind::Static, makeJITDylibSearchOrder(&PlatformJD),
501           {{ES.intern("___orc_rt_macho_platform_bootstrap"),
502             &orc_rt_macho_platform_bootstrap},
503            {ES.intern("___orc_rt_macho_platform_shutdown"),
504             &orc_rt_macho_platform_shutdown},
505            {ES.intern("___orc_rt_macho_register_object_sections"),
506             &orc_rt_macho_register_object_sections},
507            {ES.intern("___orc_rt_macho_create_pthread_key"),
508             &orc_rt_macho_create_pthread_key}}))
509     return Err;
510 
511   if (auto Err = ES.callSPSWrapper<void()>(orc_rt_macho_platform_bootstrap))
512     return Err;
513 
514   // FIXME: Ordering is fuzzy here. We're probably best off saying
515   // "behavior is undefined if code that uses the runtime is added before
516   // the platform constructor returns", then move all this to the constructor.
517   RuntimeBootstrapped = true;
518   std::vector<MachOPerObjectSectionsToRegister> DeferredPOSRs;
519   {
520     std::lock_guard<std::mutex> Lock(PlatformMutex);
521     DeferredPOSRs = std::move(BootstrapPOSRs);
522   }
523 
524   for (auto &D : DeferredPOSRs)
525     if (auto Err = registerPerObjectSections(D))
526       return Err;
527 
528   return Error::success();
529 }
530 
531 Error MachOPlatform::registerInitInfo(
532     JITDylib &JD, ExecutorAddr ObjCImageInfoAddr,
533     ArrayRef<jitlink::Section *> InitSections) {
534 
535   std::unique_lock<std::mutex> Lock(PlatformMutex);
536 
537   MachOJITDylibInitializers *InitSeq = nullptr;
538   {
539     auto I = InitSeqs.find(&JD);
540     if (I == InitSeqs.end()) {
541       // If there's no init sequence entry yet then we need to look up the
542       // header symbol to force creation of one.
543       Lock.unlock();
544 
545       auto SearchOrder =
546           JD.withLinkOrderDo([](const JITDylibSearchOrder &SO) { return SO; });
547       if (auto Err = ES.lookup(SearchOrder, MachOHeaderStartSymbol).takeError())
548         return Err;
549 
550       Lock.lock();
551       I = InitSeqs.find(&JD);
552       assert(I != InitSeqs.end() &&
553              "Entry missing after header symbol lookup?");
554     }
555     InitSeq = &I->second;
556   }
557 
558   InitSeq->ObjCImageInfoAddress = ObjCImageInfoAddr;
559 
560   for (auto *Sec : InitSections) {
561     // FIXME: Avoid copy here.
562     jitlink::SectionRange R(*Sec);
563     InitSeq->InitSections[Sec->getName()].push_back(
564         {ExecutorAddr(R.getStart()), ExecutorAddr(R.getEnd())});
565   }
566 
567   return Error::success();
568 }
569 
570 Error MachOPlatform::registerPerObjectSections(
571     const MachOPerObjectSectionsToRegister &POSR) {
572 
573   if (!orc_rt_macho_register_object_sections)
574     return make_error<StringError>("Attempting to register per-object "
575                                    "sections, but runtime support has not "
576                                    "been loaded yet",
577                                    inconvertibleErrorCode());
578 
579   Error ErrResult = Error::success();
580   if (auto Err = ES.callSPSWrapper<shared::SPSError(
581                      SPSMachOPerObjectSectionsToRegister)>(
582           orc_rt_macho_register_object_sections, ErrResult, POSR))
583     return Err;
584   return ErrResult;
585 }
586 
587 Expected<uint64_t> MachOPlatform::createPThreadKey() {
588   if (!orc_rt_macho_create_pthread_key)
589     return make_error<StringError>(
590         "Attempting to create pthread key in target, but runtime support has "
591         "not been loaded yet",
592         inconvertibleErrorCode());
593 
594   Expected<uint64_t> Result(0);
595   if (auto Err = ES.callSPSWrapper<SPSExpected<uint64_t>(void)>(
596           orc_rt_macho_create_pthread_key, Result))
597     return std::move(Err);
598   return Result;
599 }
600 
601 void MachOPlatform::MachOPlatformPlugin::modifyPassConfig(
602     MaterializationResponsibility &MR, jitlink::LinkGraph &LG,
603     jitlink::PassConfiguration &Config) {
604 
605   // If the initializer symbol is the MachOHeader start symbol then just add
606   // the macho header support passes.
607   if (MR.getInitializerSymbol() == MP.MachOHeaderStartSymbol) {
608     addMachOHeaderSupportPasses(MR, Config);
609     // The header materialization unit doesn't require any other support, so we
610     // can bail out early.
611     return;
612   }
613 
614   // If the object contains initializers then add passes to record them.
615   if (MR.getInitializerSymbol())
616     addInitializerSupportPasses(MR, Config);
617 
618   // Add passes for eh-frame and TLV support.
619   addEHAndTLVSupportPasses(MR, Config);
620 }
621 
622 ObjectLinkingLayer::Plugin::SyntheticSymbolDependenciesMap
623 MachOPlatform::MachOPlatformPlugin::getSyntheticSymbolDependencies(
624     MaterializationResponsibility &MR) {
625   std::lock_guard<std::mutex> Lock(PluginMutex);
626   auto I = InitSymbolDeps.find(&MR);
627   if (I != InitSymbolDeps.end()) {
628     SyntheticSymbolDependenciesMap Result;
629     Result[MR.getInitializerSymbol()] = std::move(I->second);
630     InitSymbolDeps.erase(&MR);
631     return Result;
632   }
633   return SyntheticSymbolDependenciesMap();
634 }
635 
636 void MachOPlatform::MachOPlatformPlugin::addInitializerSupportPasses(
637     MaterializationResponsibility &MR, jitlink::PassConfiguration &Config) {
638 
639   /// Preserve init sections.
640   Config.PrePrunePasses.push_back([this, &MR](jitlink::LinkGraph &G) {
641     if (auto Err = preserveInitSections(G, MR))
642       return Err;
643     return processObjCImageInfo(G, MR);
644   });
645 
646   Config.PostFixupPasses.push_back(
647       [this, &JD = MR.getTargetJITDylib()](jitlink::LinkGraph &G) {
648         return registerInitSections(G, JD);
649       });
650 }
651 
652 void MachOPlatform::MachOPlatformPlugin::addMachOHeaderSupportPasses(
653     MaterializationResponsibility &MR, jitlink::PassConfiguration &Config) {
654 
655   Config.PostAllocationPasses.push_back([this, &JD = MR.getTargetJITDylib()](
656                                             jitlink::LinkGraph &G) -> Error {
657     auto I = llvm::find_if(G.defined_symbols(), [this](jitlink::Symbol *Sym) {
658       return Sym->getName() == *MP.MachOHeaderStartSymbol;
659     });
660     assert(I != G.defined_symbols().end() &&
661            "Missing MachO header start symbol");
662     {
663       std::lock_guard<std::mutex> Lock(MP.PlatformMutex);
664       JITTargetAddress HeaderAddr = (*I)->getAddress();
665       MP.HeaderAddrToJITDylib[HeaderAddr] = &JD;
666       assert(!MP.InitSeqs.count(&JD) && "InitSeq entry for JD already exists");
667       MP.InitSeqs.insert(std::make_pair(
668           &JD,
669           MachOJITDylibInitializers(JD.getName(), ExecutorAddr(HeaderAddr))));
670     }
671     return Error::success();
672   });
673 }
674 
675 void MachOPlatform::MachOPlatformPlugin::addEHAndTLVSupportPasses(
676     MaterializationResponsibility &MR, jitlink::PassConfiguration &Config) {
677 
678   // Insert TLV lowering at the start of the PostPrunePasses, since we want
679   // it to run before GOT/PLT lowering.
680   Config.PostPrunePasses.insert(
681       Config.PostPrunePasses.begin(),
682       [this, &JD = MR.getTargetJITDylib()](jitlink::LinkGraph &G) {
683         return fixTLVSectionsAndEdges(G, JD);
684       });
685 
686   // Add a pass to register the final addresses of the eh-frame and TLV sections
687   // with the runtime.
688   Config.PostFixupPasses.push_back([this](jitlink::LinkGraph &G) -> Error {
689     MachOPerObjectSectionsToRegister POSR;
690 
691     if (auto *EHFrameSection = G.findSectionByName(EHFrameSectionName)) {
692       jitlink::SectionRange R(*EHFrameSection);
693       if (!R.empty())
694         POSR.EHFrameSection = {ExecutorAddr(R.getStart()),
695                                ExecutorAddr(R.getEnd())};
696     }
697 
698     // Get a pointer to the thread data section if there is one. It will be used
699     // below.
700     jitlink::Section *ThreadDataSection =
701         G.findSectionByName(ThreadDataSectionName);
702 
703     // Handle thread BSS section if there is one.
704     if (auto *ThreadBSSSection = G.findSectionByName(ThreadBSSSectionName)) {
705       // If there's already a thread data section in this graph then merge the
706       // thread BSS section content into it, otherwise just treat the thread
707       // BSS section as the thread data section.
708       if (ThreadDataSection)
709         G.mergeSections(*ThreadDataSection, *ThreadBSSSection);
710       else
711         ThreadDataSection = ThreadBSSSection;
712     }
713 
714     // Having merged thread BSS (if present) and thread data (if present),
715     // record the resulting section range.
716     if (ThreadDataSection) {
717       jitlink::SectionRange R(*ThreadDataSection);
718       if (!R.empty())
719         POSR.ThreadDataSection = {ExecutorAddr(R.getStart()),
720                                   ExecutorAddr(R.getEnd())};
721     }
722 
723     if (POSR.EHFrameSection.Start || POSR.ThreadDataSection.Start) {
724 
725       // If we're still bootstrapping the runtime then just record this
726       // frame for now.
727       if (!MP.RuntimeBootstrapped) {
728         std::lock_guard<std::mutex> Lock(MP.PlatformMutex);
729         MP.BootstrapPOSRs.push_back(POSR);
730         return Error::success();
731       }
732 
733       // Otherwise register it immediately.
734       if (auto Err = MP.registerPerObjectSections(POSR))
735         return Err;
736     }
737 
738     return Error::success();
739   });
740 }
741 
742 Error MachOPlatform::MachOPlatformPlugin::preserveInitSections(
743     jitlink::LinkGraph &G, MaterializationResponsibility &MR) {
744 
745   JITLinkSymbolSet InitSectionSymbols;
746   for (auto &InitSectionName : InitSectionNames) {
747     // Skip non-init sections.
748     auto *InitSection = G.findSectionByName(InitSectionName);
749     if (!InitSection)
750       continue;
751 
752     // Make a pass over live symbols in the section: those blocks are already
753     // preserved.
754     DenseSet<jitlink::Block *> AlreadyLiveBlocks;
755     for (auto &Sym : InitSection->symbols()) {
756       auto &B = Sym->getBlock();
757       if (Sym->isLive() && Sym->getOffset() == 0 &&
758           Sym->getSize() == B.getSize() && !AlreadyLiveBlocks.count(&B)) {
759         InitSectionSymbols.insert(Sym);
760         AlreadyLiveBlocks.insert(&B);
761       }
762     }
763 
764     // Add anonymous symbols to preserve any not-already-preserved blocks.
765     for (auto *B : InitSection->blocks())
766       if (!AlreadyLiveBlocks.count(B))
767         InitSectionSymbols.insert(
768             &G.addAnonymousSymbol(*B, 0, B->getSize(), false, true));
769   }
770 
771   if (!InitSectionSymbols.empty()) {
772     std::lock_guard<std::mutex> Lock(PluginMutex);
773     InitSymbolDeps[&MR] = std::move(InitSectionSymbols);
774   }
775 
776   return Error::success();
777 }
778 
779 Error MachOPlatform::MachOPlatformPlugin::processObjCImageInfo(
780     jitlink::LinkGraph &G, MaterializationResponsibility &MR) {
781 
782   // If there's an ObjC imagine info then either
783   //   (1) It's the first __objc_imageinfo we've seen in this JITDylib. In
784   //       this case we name and record it.
785   // OR
786   //   (2) We already have a recorded __objc_imageinfo for this JITDylib,
787   //       in which case we just verify it.
788   auto *ObjCImageInfo = G.findSectionByName(ObjCImageInfoSectionName);
789   if (!ObjCImageInfo)
790     return Error::success();
791 
792   auto ObjCImageInfoBlocks = ObjCImageInfo->blocks();
793 
794   // Check that the section is not empty if present.
795   if (llvm::empty(ObjCImageInfoBlocks))
796     return make_error<StringError>("Empty " + ObjCImageInfoSectionName +
797                                        " section in " + G.getName(),
798                                    inconvertibleErrorCode());
799 
800   // Check that there's only one block in the section.
801   if (std::next(ObjCImageInfoBlocks.begin()) != ObjCImageInfoBlocks.end())
802     return make_error<StringError>("Multiple blocks in " +
803                                        ObjCImageInfoSectionName +
804                                        " section in " + G.getName(),
805                                    inconvertibleErrorCode());
806 
807   // Check that the __objc_imageinfo section is unreferenced.
808   // FIXME: We could optimize this check if Symbols had a ref-count.
809   for (auto &Sec : G.sections()) {
810     if (&Sec != ObjCImageInfo)
811       for (auto *B : Sec.blocks())
812         for (auto &E : B->edges())
813           if (E.getTarget().isDefined() &&
814               &E.getTarget().getBlock().getSection() == ObjCImageInfo)
815             return make_error<StringError>(ObjCImageInfoSectionName +
816                                                " is referenced within file " +
817                                                G.getName(),
818                                            inconvertibleErrorCode());
819   }
820 
821   auto &ObjCImageInfoBlock = **ObjCImageInfoBlocks.begin();
822   auto *ObjCImageInfoData = ObjCImageInfoBlock.getContent().data();
823   auto Version = support::endian::read32(ObjCImageInfoData, G.getEndianness());
824   auto Flags =
825       support::endian::read32(ObjCImageInfoData + 4, G.getEndianness());
826 
827   // Lock the mutex while we verify / update the ObjCImageInfos map.
828   std::lock_guard<std::mutex> Lock(PluginMutex);
829 
830   auto ObjCImageInfoItr = ObjCImageInfos.find(&MR.getTargetJITDylib());
831   if (ObjCImageInfoItr != ObjCImageInfos.end()) {
832     // We've already registered an __objc_imageinfo section. Verify the
833     // content of this new section matches, then delete it.
834     if (ObjCImageInfoItr->second.first != Version)
835       return make_error<StringError>(
836           "ObjC version in " + G.getName() +
837               " does not match first registered version",
838           inconvertibleErrorCode());
839     if (ObjCImageInfoItr->second.second != Flags)
840       return make_error<StringError>("ObjC flags in " + G.getName() +
841                                          " do not match first registered flags",
842                                      inconvertibleErrorCode());
843 
844     // __objc_imageinfo is valid. Delete the block.
845     for (auto *S : ObjCImageInfo->symbols())
846       G.removeDefinedSymbol(*S);
847     G.removeBlock(ObjCImageInfoBlock);
848   } else {
849     // We haven't registered an __objc_imageinfo section yet. Register and
850     // move on. The section should already be marked no-dead-strip.
851     ObjCImageInfos[&MR.getTargetJITDylib()] = std::make_pair(Version, Flags);
852   }
853 
854   return Error::success();
855 }
856 
857 Error MachOPlatform::MachOPlatformPlugin::registerInitSections(
858     jitlink::LinkGraph &G, JITDylib &JD) {
859 
860   ExecutorAddr ObjCImageInfoAddr;
861   SmallVector<jitlink::Section *> InitSections;
862 
863   if (auto *ObjCImageInfoSec = G.findSectionByName(ObjCImageInfoSectionName)) {
864     if (auto Addr = jitlink::SectionRange(*ObjCImageInfoSec).getStart())
865       ObjCImageInfoAddr.setValue(Addr);
866   }
867 
868   for (auto InitSectionName : InitSectionNames)
869     if (auto *Sec = G.findSectionByName(InitSectionName))
870       InitSections.push_back(Sec);
871 
872   // Dump the scraped inits.
873   LLVM_DEBUG({
874     dbgs() << "MachOPlatform: Scraped " << G.getName() << " init sections:\n";
875     if (ObjCImageInfoAddr)
876       dbgs() << "  " << ObjCImageInfoSectionName << ": "
877              << formatv("{0:x}", ObjCImageInfoAddr.getValue()) << "\n";
878     for (auto *Sec : InitSections) {
879       jitlink::SectionRange R(*Sec);
880       dbgs() << "  " << Sec->getName() << ": "
881              << formatv("[ {0:x} -- {1:x} ]", R.getStart(), R.getEnd()) << "\n";
882     }
883   });
884 
885   return MP.registerInitInfo(JD, ObjCImageInfoAddr, InitSections);
886 }
887 
888 Error MachOPlatform::MachOPlatformPlugin::fixTLVSectionsAndEdges(
889     jitlink::LinkGraph &G, JITDylib &JD) {
890 
891   // Rename external references to __tlv_bootstrap to ___orc_rt_tlv_get_addr.
892   for (auto *Sym : G.external_symbols())
893     if (Sym->getName() == "__tlv_bootstrap") {
894       Sym->setName("___orc_rt_macho_tlv_get_addr");
895       break;
896     }
897 
898   // Store key in __thread_vars struct fields.
899   if (auto *ThreadDataSec = G.findSectionByName(ThreadVarsSectionName)) {
900     Optional<uint64_t> Key;
901     {
902       std::lock_guard<std::mutex> Lock(MP.PlatformMutex);
903       auto I = MP.JITDylibToPThreadKey.find(&JD);
904       if (I != MP.JITDylibToPThreadKey.end())
905         Key = I->second;
906     }
907 
908     if (!Key) {
909       if (auto KeyOrErr = MP.createPThreadKey())
910         Key = *KeyOrErr;
911       else
912         return KeyOrErr.takeError();
913     }
914 
915     uint64_t PlatformKeyBits =
916         support::endian::byte_swap(*Key, G.getEndianness());
917 
918     for (auto *B : ThreadDataSec->blocks()) {
919       if (B->getSize() != 3 * G.getPointerSize())
920         return make_error<StringError>("__thread_vars block at " +
921                                            formatv("{0:x}", B->getAddress()) +
922                                            " has unexpected size",
923                                        inconvertibleErrorCode());
924 
925       auto NewBlockContent = G.allocateBuffer(B->getSize());
926       llvm::copy(B->getContent(), NewBlockContent.data());
927       memcpy(NewBlockContent.data() + G.getPointerSize(), &PlatformKeyBits,
928              G.getPointerSize());
929       B->setContent(NewBlockContent);
930     }
931   }
932 
933   // Transform any TLV edges into GOT edges.
934   for (auto *B : G.blocks())
935     for (auto &E : B->edges())
936       if (E.getKind() ==
937           jitlink::x86_64::RequestTLVPAndTransformToPCRel32TLVPLoadREXRelaxable)
938         E.setKind(jitlink::x86_64::
939                       RequestGOTAndTransformToPCRel32GOTLoadREXRelaxable);
940 
941   return Error::success();
942 }
943 
944 } // End namespace orc.
945 } // End namespace llvm.
946