1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/aotClassLocation.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoadInfo.hpp"
34 #include "classfile/dictionary.hpp"
35 #include "classfile/javaClasses.inline.hpp"
36 #include "classfile/klassFactory.hpp"
37 #include "classfile/loaderConstraints.hpp"
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/resolutionErrors.hpp"
41 #include "classfile/stringTable.hpp"
42 #include "classfile/symbolTable.hpp"
43 #include "classfile/systemDictionary.hpp"
44 #include "classfile/vmClasses.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "gc/shared/gcTraceTime.inline.hpp"
47 #include "interpreter/bootstrapInfo.hpp"
48 #include "jfr/jfrEvents.hpp"
49 #include "jvm.h"
50 #include "logging/log.hpp"
51 #include "logging/logStream.hpp"
52 #include "memory/metaspaceClosure.hpp"
53 #include "memory/oopFactory.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "memory/universe.hpp"
56 #include "oops/access.inline.hpp"
57 #include "oops/fieldStreams.inline.hpp"
58 #include "oops/inlineKlass.inline.hpp"
59 #include "oops/instanceKlass.hpp"
60 #include "oops/klass.inline.hpp"
61 #include "oops/method.inline.hpp"
62 #include "oops/objArrayKlass.hpp"
63 #include "oops/objArrayOop.inline.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "oops/oopHandle.inline.hpp"
66 #include "oops/symbol.hpp"
67 #include "oops/typeArrayKlass.hpp"
68 #include "prims/jvmtiExport.hpp"
69 #include "prims/methodHandles.hpp"
70 #include "runtime/arguments.hpp"
71 #include "runtime/atomicAccess.hpp"
72 #include "runtime/handles.inline.hpp"
73 #include "runtime/java.hpp"
74 #include "runtime/javaCalls.hpp"
75 #include "runtime/mutexLocker.hpp"
76 #include "runtime/os.hpp"
77 #include "runtime/sharedRuntime.hpp"
78 #include "runtime/signature.hpp"
79 #include "runtime/synchronizer.hpp"
80 #include "services/classLoadingService.hpp"
81 #include "services/diagnosticCommand.hpp"
82 #include "services/finalizerService.hpp"
83 #include "services/threadService.hpp"
84 #include "utilities/growableArray.hpp"
85 #include "utilities/macros.hpp"
86 #include "utilities/utf8.hpp"
87 #if INCLUDE_CDS
88 #include "classfile/systemDictionaryShared.hpp"
89 #endif
90 #if INCLUDE_JFR
91 #include "jfr/jfr.hpp"
92 #endif
93
94 class InvokeMethodKey : public StackObj {
95 private:
96 Symbol* _symbol;
97 intptr_t _iid;
98
99 public:
100 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
101 _symbol(symbol),
102 _iid(iid) {}
103
104 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
105 return k1._symbol == k2._symbol && k1._iid == k2._iid;
106 }
107
108 static unsigned int compute_hash(const InvokeMethodKey &k) {
109 Symbol* sym = k._symbol;
110 intptr_t iid = k._iid;
111 unsigned int hash = (unsigned int) sym -> identity_hash();
112 return (unsigned int) (hash ^ iid);
113 }
114
115 };
116
117 using InvokeMethodIntrinsicTable = HashTable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
118 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
119 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
120 using InvokeMethodTypeTable = HashTable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
121 static InvokeMethodTypeTable* _invoke_method_type_table;
122
123 OopHandle SystemDictionary::_java_system_loader;
124 OopHandle SystemDictionary::_java_platform_loader;
125
126 // ----------------------------------------------------------------------------
127 // Java-level SystemLoader and PlatformLoader
128 oop SystemDictionary::java_system_loader() {
129 return _java_system_loader.resolve();
130 }
131
132 oop SystemDictionary::java_platform_loader() {
133 return _java_platform_loader.resolve();
134 }
135
136 void SystemDictionary::compute_java_loaders(TRAPS) {
137 if (_java_platform_loader.is_empty()) {
138 oop platform_loader = get_platform_class_loader_impl(CHECK);
139 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
140 } else {
141 // It must have been restored from the archived module graph
142 assert(CDSConfig::is_using_archive(), "must be");
143 assert(CDSConfig::is_using_full_module_graph(), "must be");
144 DEBUG_ONLY(
145 oop platform_loader = get_platform_class_loader_impl(CHECK);
146 assert(_java_platform_loader.resolve() == platform_loader, "must be");
147 )
148 }
149
150 if (_java_system_loader.is_empty()) {
151 oop system_loader = get_system_class_loader_impl(CHECK);
152 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
153 } else {
154 // It must have been restored from the archived module graph
155 assert(CDSConfig::is_using_archive(), "must be");
156 assert(CDSConfig::is_using_full_module_graph(), "must be");
157 DEBUG_ONLY(
158 oop system_loader = get_system_class_loader_impl(CHECK);
159 assert(_java_system_loader.resolve() == system_loader, "must be");
160 )
161 }
162 }
163
164 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
165 JavaValue result(T_OBJECT);
166 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
167 JavaCalls::call_static(&result,
168 class_loader_klass,
169 vmSymbols::getSystemClassLoader_name(),
170 vmSymbols::void_classloader_signature(),
171 CHECK_NULL);
172 return result.get_oop();
173 }
174
175 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
176 JavaValue result(T_OBJECT);
177 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
178 JavaCalls::call_static(&result,
179 class_loader_klass,
180 vmSymbols::getPlatformClassLoader_name(),
181 vmSymbols::void_classloader_signature(),
182 CHECK_NULL);
183 return result.get_oop();
184 }
185
186 // Helper function
187 inline ClassLoaderData* class_loader_data(Handle class_loader) {
188 return ClassLoaderData::class_loader_data(class_loader());
189 }
190
191 // These migrated value classes are loaded by the bootstrap class loader but are added to the initiating
192 // loaders automatically so that fields of these types can be found and potentially flattened during
193 // field layout.
194 static void add_migrated_value_classes(ClassLoaderData* cld) {
195 JavaThread* current = JavaThread::current();
196 auto add_klass = [&] (Symbol* classname) {
197 InstanceKlass* ik = SystemDictionary::find_instance_klass(current, classname, Handle(current, nullptr));
198 assert(ik != nullptr, "Must exist");
199 SystemDictionary::add_to_initiating_loader(current, ik, cld);
200 };
201
202 MonitorLocker mu1(SystemDictionary_lock);
203 vmSymbols::migrated_class_names_do(add_klass);
204 }
205
206 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
207 if (create_mirror_cld) {
208 // Add a new class loader data to the graph.
209 return ClassLoaderDataGraph::add(class_loader, true);
210 } else {
211 if (class_loader() == nullptr) {
212 return ClassLoaderData::the_null_class_loader_data();
213 } else {
214 bool Bug8370217_FIXED = false;
215 ClassLoaderData* cld = ClassLoaderDataGraph::find_or_create(class_loader);
216 if (EnableValhalla && Bug8370217_FIXED) {
217 add_migrated_value_classes(cld);
218 }
219 return cld;
220 }
221 }
222 }
223
224 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
225 if (_java_system_loader.is_empty()) {
226 _java_system_loader = cld->class_loader_handle();
227 } else {
228 assert(_java_system_loader.resolve() == cld->class_loader(), "sanity");
229 }
230 }
231
232 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
233 if (_java_platform_loader.is_empty()) {
234 _java_platform_loader = cld->class_loader_handle();
235 } else {
236 assert(_java_platform_loader.resolve() == cld->class_loader(), "sanity");
237 }
238 }
239
240 // ----------------------------------------------------------------------------
241 // Parallel class loading check
242
243 static bool is_parallelCapable(Handle class_loader) {
244 if (class_loader.is_null()) return true;
245 return java_lang_ClassLoader::parallelCapable(class_loader());
246 }
247 // ----------------------------------------------------------------------------
248 // ParallelDefineClass flag does not apply to bootclass loader
249 static bool is_parallelDefine(Handle class_loader) {
250 if (class_loader.is_null()) return false;
251 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
252 return true;
253 }
254 return false;
255 }
256
257 // Returns true if the passed class loader is the builtin application class loader
258 // or a custom system class loader. A customer system class loader can be
259 // specified via -Djava.system.class.loader.
260 bool SystemDictionary::is_system_class_loader(oop class_loader) {
261 if (class_loader == nullptr) {
262 return false;
263 }
264 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
265 class_loader == _java_system_loader.peek());
266 }
267
268 // Returns true if the passed class loader is the platform class loader.
269 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
270 if (class_loader == nullptr) {
271 return false;
272 }
273 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
274 }
275
276 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
277 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
278 if (is_parallelCapable(class_loader)) {
279 return Handle();
280 } else {
281 return class_loader;
282 }
283 }
284
285 // ----------------------------------------------------------------------------
286 // Resolving of classes
287
288 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
289 if (name == nullptr) {
290 THROW_MSG_NULL(exception, "No class name given");
291 }
292 size_t name_len = strlen(name);
293 if (name_len > static_cast<size_t>(Symbol::max_length())) {
294 // It's impossible to create this class; the name cannot fit
295 // into the constant pool. If necessary report an abridged name
296 // in the exception message.
297 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
298 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
299 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
300 Symbol::max_length(),
301 MaxStringPrintSize / 2,
302 name,
303 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
304 MaxStringPrintSize / 2,
305 name + name_len - MaxStringPrintSize / 2);
306 }
307 else {
308 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
309 "Class name exceeds maximum length of %d: %s",
310 Symbol::max_length(),
311 name);
312 }
313 return nullptr;
314 }
315 // Callers should ensure that the name is never an illegal UTF8 string.
316 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
317 "Class name is not a valid utf8 string.");
318
319 // Make a new symbol for the class name.
320 return SymbolTable::new_symbol(name);
321 }
322
323 #ifdef ASSERT
324 // Used to verify that class loading succeeded in adding k to the dictionary.
325 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
326 MutexLocker mu(SystemDictionary_lock);
327 ClassLoaderData* loader_data = k->class_loader_data();
328 Dictionary* dictionary = loader_data->dictionary();
329 assert(class_name == k->name(), "Must be the same");
330 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
331 assert(kk == k, "should be present in dictionary");
332 }
333 #endif
334
335 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
336 if (HAS_PENDING_EXCEPTION) {
337 // If we have a pending exception we forward it to the caller, unless throw_error is true,
338 // in which case we have to check whether the pending exception is a ClassNotFoundException,
339 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
340 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
341 ResourceMark rm(THREAD);
342 Handle e(THREAD, PENDING_EXCEPTION);
343 CLEAR_PENDING_EXCEPTION;
344 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
345 } else {
346 return; // the caller will throw the incoming exception
347 }
348 }
349 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
350 // error or exception depending on the value of throw_error.
351 ResourceMark rm(THREAD);
352 if (throw_error) {
353 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
354 } else {
355 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
356 }
357 }
358
359 // Forwards to resolve_or_null
360
361 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader,
362 bool throw_error, TRAPS) {
363 Klass* klass = resolve_or_null(class_name, class_loader, THREAD);
364 // Check for pending exception or null klass, and throw exception
365 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
366 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
367 }
368 return klass;
369 }
370
371 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
372
373 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, TRAPS) {
374 if (Signature::is_array(class_name)) {
375 return resolve_array_class_or_null(class_name, class_loader, THREAD);
376 } else {
377 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
378 if (Signature::has_envelope(class_name)) {
379 ResourceMark rm(THREAD);
380 // Ignore wrapping L and ;.
381 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
382 class_name->utf8_length() - 2);
383 return resolve_instance_class_or_null(name, class_loader, THREAD);
384 } else {
385 return resolve_instance_class_or_null(class_name, class_loader, THREAD);
386 }
387 }
388 }
389
390 // Forwards to resolve_instance_class_or_null
391
392 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
393 Handle class_loader,
394 TRAPS) {
395 assert(Signature::is_array(class_name), "must be array");
396 ResourceMark rm(THREAD);
397 SignatureStream ss(class_name, false);
398 int ndims = ss.skip_array_prefix(); // skip all '['s
399 Klass* k = nullptr;
400 BasicType t = ss.type();
401 if (ss.has_envelope()) {
402 Symbol* obj_class = ss.as_symbol();
403 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
404 class_loader,
405 CHECK_NULL);
406 if (k != nullptr) {
407 k = k->array_klass(ndims, CHECK_NULL);
408 }
409 } else {
410 k = Universe::typeArrayKlass(t);
411 k = k->array_klass(ndims, CHECK_NULL);
412 }
413 return k;
414 }
415
416 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
417 LogTarget(Debug, class, load, placeholders) lt;
418 if (lt.is_enabled()) {
419 ResourceMark rm;
420 LogStream ls(lt);
421 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
422 probe->print_on(&ls);
423 ls.cr();
424 }
425 }
426
427 // Must be called for any superclass or superinterface resolution
428 // during class definition, or may be called for inline field layout processing
429 // to detect class circularity errors.
430 // superinterface callers:
431 // parse_interfaces - from defineClass
432 // superclass callers:
433 // ClassFileParser - from defineClass
434 // load_shared_class - while loading a class from shared archive
435 // resolve_instance_class_or_null:
436 // via: handle_parallel_super_load
437 // when resolving a class that has an existing placeholder with
438 // a saved superclass [i.e. a defineClass is currently in progress]
439 // If another thread is trying to resolve the class, it must do
440 // superclass checks on its own thread to catch class circularity and
441 // to avoid deadlock.
442 // inline field layout callers:
443 // The field's class must be loaded to determine layout.
444 //
445 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
446 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
447 // placeholder for the same thread, class, and classloader is found.
448 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
449 //
450 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
451 Symbol* next_name,
452 Handle class_loader,
453 bool is_superclass,
454 TRAPS) {
455
456 assert(next_name != nullptr, "null superclass for resolving");
457 assert(!Signature::is_array(next_name), "invalid superclass name");
458
459 ClassLoaderData* loader_data = class_loader_data(class_loader);
460
461 if (is_superclass) {
462 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
463 if (klassk != nullptr) {
464 // We can come here for two reasons:
465 // (a) RedefineClasses -- the class is already loaded
466 // (b) Rarely, the class might have been loaded by a parallel thread
467 // We can do a quick check against the already assigned superclass's name and loader.
468 InstanceKlass* superk = klassk->super();
469 if (superk != nullptr &&
470 superk->name() == next_name &&
471 superk->class_loader() == class_loader()) {
472 return superk;
473 }
474 }
475 }
476
477 // can't throw error holding a lock
478 bool throw_circularity_error = false;
479 {
480 MutexLocker mu(THREAD, SystemDictionary_lock);
481
482 // Must check ClassCircularity before resolving next_name (superclass, interface, field types or speculatively preloaded argument types).
483 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
484 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
485 log_circularity_error(class_name, probe);
486 throw_circularity_error = true;
487 }
488
489 // Make sure there's a placeholder for the class_name before resolving.
490 // This is used as a claim that this thread is currently loading superclass/classloader
491 // and for ClassCircularity checks.
492 if (!throw_circularity_error) {
493 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
494 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
495 loader_data,
496 PlaceholderTable::DETECT_CIRCULARITY,
497 next_name, THREAD);
498 }
499 }
500
501 if (throw_circularity_error) {
502 ResourceMark rm(THREAD);
503 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
504 }
505
506 // Resolve the superclass, superinterface, field type or speculatively preloaded argument types and check results on return.
507 InstanceKlass* superk =
508 SystemDictionary::resolve_instance_class_or_null(next_name,
509 class_loader,
510 THREAD);
511
512 // Clean up placeholder entry.
513 {
514 MutexLocker mu(THREAD, SystemDictionary_lock);
515 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
516 SystemDictionary_lock->notify_all();
517 }
518
519 // Check for pending exception or null superk, and throw exception
520 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
521 handle_resolution_exception(next_name, true, CHECK_NULL);
522 }
523
524 return superk;
525 }
526
527 // If the class in is in the placeholder table, class loading is in progress.
528 // For cases where the application changes threads to load classes, it
529 // is critical to ClassCircularity detection that we try loading
530 // the superclass on the new thread internally, so we do parallel
531 // superclass loading here. This avoids deadlock for ClassCircularity
532 // detection for parallelCapable class loaders that lock on a per-class lock.
533 static void handle_parallel_super_load(Symbol* name,
534 Symbol* superclassname,
535 Handle class_loader,
536 TRAPS) {
537
538 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
539 // This passes false to is_superclass to skip doing the unlikely optimization.
540 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
541 superclassname,
542 class_loader,
543 false,
544 CHECK);
545 }
546
547 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
548 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
549 static bool needs_load_placeholder(Handle class_loader) {
550 return class_loader.is_null() || !is_parallelCapable(class_loader);
551 }
552
553 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
554 static InstanceKlass* handle_parallel_loading(JavaThread* current,
555 Symbol* name,
556 ClassLoaderData* loader_data,
557 bool must_wait_for_class_loading,
558 bool* throw_circularity_error) {
559 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
560 if (oldprobe != nullptr) {
561 // -Xcomp calls load_signature_classes which might result in loading
562 // a class that's already in the process of loading, so we detect CCE here also.
563 // Only need check_seen_thread once, not on each loop
564 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
565 log_circularity_error(name, oldprobe);
566 *throw_circularity_error = true;
567 return nullptr;
568 } else if (must_wait_for_class_loading) {
569 // Wait until the first thread has finished loading this class. Also wait until all the
570 // threads trying to load its superclass have removed their placeholders.
571 while (oldprobe != nullptr &&
572 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
573
574 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
575 // for the bootclass loader.
576 SystemDictionary_lock->wait();
577
578 // Check if classloading completed while we were waiting
579 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
580 if (check != nullptr) {
581 // Klass is already loaded, so just return it
582 return check;
583 }
584 // check if other thread failed to load and cleaned up
585 oldprobe = PlaceholderTable::get_entry(name, loader_data);
586 }
587 }
588 }
589 return nullptr;
590 }
591
592 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
593 assert(event != nullptr, "invariant");
594 assert(k != nullptr, "invariant");
595 event->set_loadedClass(k);
596 event->set_definingClassLoader(k->class_loader_data());
597 event->set_initiatingClassLoader(init_cld);
598 event->commit();
599 }
600
601 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
602 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
603 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
604 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
605 // This can return null, an exception or an InstanceKlass.
606 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
607 Handle class_loader,
608 TRAPS) {
609 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
610 DEBUG_ONLY(ResourceMark rm(THREAD));
611 assert(name != nullptr && !Signature::is_array(name) &&
612 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
613
614 EventClassLoad class_load_start_event;
615
616 HandleMark hm(THREAD);
617
618 ClassLoaderData* loader_data = register_loader(class_loader);
619 Dictionary* dictionary = loader_data->dictionary();
620
621 // Do lookup to see if class already exists.
622 InstanceKlass* probe = dictionary->find_class(THREAD, name);
623 if (probe != nullptr) return probe;
624
625 // Non-bootstrap class loaders will call out to class loader and
626 // define via jvm/jni_DefineClass which will acquire the
627 // class loader object lock to protect against multiple threads
628 // defining the class in parallel by accident.
629 // This lock must be acquired here so the waiter will find
630 // any successful result in the SystemDictionary and not attempt
631 // the define.
632 // ParallelCapable class loaders and the bootstrap classloader
633 // do not acquire lock here.
634 Handle lockObject = get_loader_lock_or_null(class_loader);
635 ObjectLocker ol(lockObject, THREAD);
636
637 bool circularity_detection_in_progress = false;
638 InstanceKlass* loaded_class = nullptr;
639 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
640
641 guarantee(THREAD->can_call_java(),
642 "can not load classes with compiler thread: class=%s, classloader=%s",
643 name->as_C_string(),
644 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
645
646 // Check again (after locking) if the class already exists in SystemDictionary
647 {
648 MutexLocker mu(THREAD, SystemDictionary_lock);
649 InstanceKlass* check = dictionary->find_class(THREAD, name);
650 if (check != nullptr) {
651 // InstanceKlass is already loaded, but we still need to check protection domain below.
652 loaded_class = check;
653 } else {
654 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
655 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
656 circularity_detection_in_progress = true;
657 superclassname = placeholder->next_klass_name();
658 assert(superclassname != nullptr, "superclass has to have a name");
659 }
660 }
661 }
662
663 // If the class is in the placeholder table with super_class set,
664 // handle superclass loading in progress.
665 if (circularity_detection_in_progress) {
666 handle_parallel_super_load(name, superclassname,
667 class_loader,
668 CHECK_NULL);
669 }
670
671 bool throw_circularity_error = false;
672 if (loaded_class == nullptr) {
673 bool load_placeholder_added = false;
674
675 // Add placeholder entry to record loading instance class
676 // case 1. Bootstrap classloader
677 // This classloader supports parallelism at the classloader level
678 // but only allows a single thread to load a class/classloader pair.
679 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
680 // case 2. parallelCapable user level classloaders
681 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
682 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
683 // case 3. traditional classloaders that rely on the classloader object lock
684 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
685 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
686 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
687 {
688 MutexLocker mu(THREAD, SystemDictionary_lock);
689 if (needs_load_placeholder(class_loader)) {
690 loaded_class = handle_parallel_loading(THREAD,
691 name,
692 loader_data,
693 class_loader.is_null(),
694 &throw_circularity_error);
695 }
696
697 // Recheck if the class has been loaded for all class loader cases and
698 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
699 if (!throw_circularity_error && loaded_class == nullptr) {
700 InstanceKlass* check = dictionary->find_class(THREAD, name);
701 if (check != nullptr) {
702 loaded_class = check;
703 } else if (needs_load_placeholder(class_loader)) {
704 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
705 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
706 PlaceholderTable::LOAD_INSTANCE,
707 nullptr,
708 THREAD);
709 load_placeholder_added = true;
710 }
711 }
712 }
713
714 // Must throw error outside of owning lock
715 if (throw_circularity_error) {
716 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
717 ResourceMark rm(THREAD);
718 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
719 }
720
721 // Be careful when modifying this code: once you have run
722 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
723 // you need to find_and_remove it before returning.
724 // So be careful to not exit with a CHECK_ macro between these calls.
725
726 if (loaded_class == nullptr) {
727 // Do actual loading
728 loaded_class = load_instance_class(name, class_loader, THREAD);
729 }
730
731 if (load_placeholder_added) {
732 // clean up placeholder entries for LOAD_INSTANCE success or error
733 // This brackets the SystemDictionary updates for both defining
734 // and initiating loaders
735 MutexLocker mu(THREAD, SystemDictionary_lock);
736 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
737 SystemDictionary_lock->notify_all();
738 }
739 }
740
741 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
742 return nullptr;
743 }
744
745 if (class_load_start_event.should_commit()) {
746 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
747 }
748
749 // Make sure we have the right class in the dictionary
750 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
751
752 return loaded_class;
753 }
754
755
756 // This routine does not lock the system dictionary.
757 //
758 // Since readers don't hold a lock, we must make sure that system
759 // dictionary entries are added to in a safe way (all links must
760 // be updated in an MT-safe manner). All entries are removed during class
761 // unloading, when this class loader is no longer referenced.
762 //
763 // Callers should be aware that an entry could be added just after
764 // Dictionary is read here, so the caller will not see
765 // the new entry.
766
767 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
768 Symbol* class_name,
769 Handle class_loader) {
770
771 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
772 if (loader_data == nullptr) {
773 // If the ClassLoaderData has not been setup,
774 // then the class loader has no entries in the dictionary.
775 return nullptr;
776 }
777
778 Dictionary* dictionary = loader_data->dictionary();
779 return dictionary->find_class(current, class_name);
780 }
781
782 // Look for a loaded instance or array klass by name. Do not do any loading.
783 // return null in case of error.
784 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
785 Symbol* class_name,
786 Handle class_loader) {
787 Klass* k = nullptr;
788 assert(class_name != nullptr, "class name must be non nullptr");
789
790 if (Signature::is_array(class_name)) {
791 // The name refers to an array. Parse the name.
792 // dimension and object_key in FieldArrayInfo are assigned as a
793 // side-effect of this call
794 SignatureStream ss(class_name, false);
795 int ndims = ss.skip_array_prefix(); // skip all '['s
796 BasicType t = ss.type();
797 if (t != T_OBJECT) {
798 k = Universe::typeArrayKlass(t);
799 } else {
800 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader);
801 }
802 if (k != nullptr) {
803 k = k->array_klass_or_null(ndims);
804 }
805 } else {
806 k = find_instance_klass(current, class_name, class_loader);
807 }
808 return k;
809 }
810
811 // Note: this method is much like resolve_class_from_stream, but
812 // does not publish the classes in the SystemDictionary.
813 // Handles Lookup.defineClass hidden.
814 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
815 ClassFileStream* st,
816 Symbol* class_name,
817 Handle class_loader,
818 const ClassLoadInfo& cl_info,
819 TRAPS) {
820
821 EventClassLoad class_load_start_event;
822 ClassLoaderData* loader_data;
823
824 // - for hidden classes that are not strong: create a new CLD that has a class holder and
825 // whose loader is the Lookup class's loader.
826 // - for hidden class: add the class to the Lookup class's loader's CLD.
827 assert (cl_info.is_hidden(), "only used for hidden classes");
828 bool create_mirror_cld = !cl_info.is_strong_hidden();
829 loader_data = register_loader(class_loader, create_mirror_cld);
830
831 assert(st != nullptr, "invariant");
832
833 // Parse stream and create a klass.
834 InstanceKlass* k = KlassFactory::create_from_stream(st,
835 class_name,
836 loader_data,
837 cl_info,
838 CHECK_NULL);
839 assert(k != nullptr, "no klass created");
840
841 // Hidden classes that are not strong must update ClassLoaderData holder
842 // so that they can be unloaded when the mirror is no longer referenced.
843 if (!cl_info.is_strong_hidden()) {
844 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
845 }
846
847 // Add to class hierarchy, and do possible deoptimizations.
848 k->add_to_hierarchy(THREAD);
849 // But, do not add to dictionary.
850
851 k->link_class(CHECK_NULL);
852
853 // notify jvmti
854 if (JvmtiExport::should_post_class_load()) {
855 JvmtiExport::post_class_load(THREAD, k);
856 }
857 if (class_load_start_event.should_commit()) {
858 post_class_load_event(&class_load_start_event, k, loader_data);
859 }
860
861 return k;
862 }
863
864 // Add a klass to the system from a stream (called by jni_DefineClass and
865 // JVM_DefineClass).
866 // Note: class_name can be null. In that case we do not know the name of
867 // the class until we have parsed the stream.
868 // This function either returns an InstanceKlass or throws an exception. It does
869 // not return null without a pending exception.
870 InstanceKlass* SystemDictionary::resolve_class_from_stream(
871 ClassFileStream* st,
872 Symbol* class_name,
873 Handle class_loader,
874 const ClassLoadInfo& cl_info,
875 TRAPS) {
876
877 HandleMark hm(THREAD);
878
879 ClassLoaderData* loader_data = register_loader(class_loader);
880
881 // Classloaders that support parallelism, e.g. bootstrap classloader,
882 // do not acquire lock here
883 Handle lockObject = get_loader_lock_or_null(class_loader);
884 ObjectLocker ol(lockObject, THREAD);
885
886 // Parse the stream and create a klass.
887 // Note that we do this even though this klass might
888 // already be present in the SystemDictionary, otherwise we would not
889 // throw potential ClassFormatErrors.
890 InstanceKlass* k = nullptr;
891
892 #if INCLUDE_CDS
893 if (!CDSConfig::is_dumping_static_archive()) {
894 k = SystemDictionaryShared::lookup_from_stream(class_name,
895 class_loader,
896 cl_info.protection_domain(),
897 st,
898 CHECK_NULL);
899 }
900 #endif
901
902 if (k == nullptr) {
903 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
904 }
905
906 assert(k != nullptr, "no klass created");
907 Symbol* h_name = k->name();
908 assert(class_name == nullptr || class_name == h_name, "name mismatch");
909
910 // Add class just loaded
911 // If a class loader supports parallel classloading, handle parallel define requests.
912 // find_or_define_instance_class may return a different InstanceKlass,
913 // in which case the old k would be deallocated
914 if (is_parallelCapable(class_loader)) {
915 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
916 } else {
917 define_instance_class(k, class_loader, THREAD);
918
919 // If defining the class throws an exception register 'k' for cleanup.
920 if (HAS_PENDING_EXCEPTION) {
921 assert(k != nullptr, "Must have an instance klass here!");
922 loader_data->add_to_deallocate_list(k);
923 return nullptr;
924 }
925 }
926
927 // Make sure we have an entry in the SystemDictionary on success
928 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
929
930 return k;
931 }
932
933 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
934 Symbol* class_name,
935 Handle class_loader,
936 const ClassLoadInfo& cl_info,
937 TRAPS) {
938 if (cl_info.is_hidden()) {
939 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
940 } else {
941 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
942 }
943 }
944
945
946 #if INCLUDE_CDS
947 // Check if a shared class can be loaded by the specific classloader.
948 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
949 InstanceKlass* ik,
950 PackageEntry* pkg_entry,
951 Handle class_loader) {
952 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
953
954 // (1) Check if we are loading into the same loader as in dump time.
955
956 if (ik->defined_by_boot_loader()) {
957 if (class_loader() != nullptr) {
958 return false;
959 }
960 } else if (ik->defined_by_platform_loader()) {
961 if (class_loader() != java_platform_loader()) {
962 return false;
963 }
964 } else if (ik->defined_by_app_loader()) {
965 if (class_loader() != java_system_loader()) {
966 return false;
967 }
968 } else {
969 // ik was loaded by a custom loader during dump time
970 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
971 return false;
972 } else {
973 return true;
974 }
975 }
976
977 // (2) Check if we are loading into the same module from the same location as in dump time.
978
979 if (CDSConfig::is_using_optimized_module_handling()) {
980 // Class visibility has not changed between dump time and run time, so a class
981 // that was visible (and thus archived) during dump time is always visible during runtime.
982 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
983 "visibility cannot change between dump time and runtime");
984 return true;
985 }
986 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
987 }
988
989 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
990 InstanceKlass* ik,
991 PackageEntry* pkg_entry,
992 Handle class_loader) {
993 int scp_index = ik->shared_classpath_index();
994 assert(!ik->defined_by_other_loaders(), "this function should be called for built-in classes only");
995 assert(scp_index >= 0, "must be");
996 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index);
997 if (!Universe::is_module_initialized()) {
998 assert(cl != nullptr, "must be");
999 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
1000 // has restricted the classes can be loaded at this step to be only:
1001 // [1] cs->is_modules_image(): classes in java.base, or,
1002 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
1003 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1004 "only these classes can be loaded before the module system is initialized");
1005 assert(class_loader.is_null(), "sanity");
1006 return true;
1007 }
1008
1009 if (pkg_entry == nullptr) {
1010 // We might have looked up pkg_entry before the module system was initialized.
1011 // Need to reload it now.
1012 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1013 if (pkg_name != nullptr) {
1014 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1015 }
1016 }
1017
1018 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1019 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1020 bool was_archived_from_named_module = !cl->has_unnamed_module();
1021 bool visible;
1022
1023 if (was_archived_from_named_module) {
1024 if (should_be_in_named_module) {
1025 // Is the module loaded from the same location as during dump time?
1026 visible = mod_entry->shared_path_index() == scp_index;
1027 if (visible) {
1028 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
1029 }
1030 } else {
1031 // During dump time, this class was in a named module, but at run time, this class should be
1032 // in an unnamed module.
1033 visible = false;
1034 }
1035 } else {
1036 if (should_be_in_named_module) {
1037 // During dump time, this class was in an unnamed, but at run time, this class should be
1038 // in a named module.
1039 visible = false;
1040 } else {
1041 visible = true;
1042 }
1043 }
1044
1045 return visible;
1046 }
1047
1048 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1049 Handle class_loader, bool is_superclass, TRAPS) {
1050 assert(super_type->in_aot_cache(), "must be");
1051
1052 // Quick check if the super type has been already loaded.
1053 // + Don't do it for unregistered classes -- they can be unloaded so
1054 // super_type->class_loader_data() could be stale.
1055 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1056 if (!super_type->defined_by_other_loaders() && super_type->class_loader_data() != nullptr) {
1057 // Check if the superclass is loaded by the current class_loader
1058 Symbol* name = super_type->name();
1059 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader);
1060 if (check == super_type) {
1061 return true;
1062 }
1063 }
1064
1065 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1066 class_loader, is_superclass, CHECK_false);
1067 if (found == super_type) {
1068 return true;
1069 } else {
1070 // The dynamically resolved super type is not the same as the one we used during dump time,
1071 // so we cannot use the class.
1072 return false;
1073 }
1074 }
1075
1076 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) {
1077 // Check the superclass and interfaces. They must be the same
1078 // as in dump time, because the layout of <ik> depends on
1079 // the specific layout of ik->super() and ik->local_interfaces().
1080 //
1081 // If unexpected superclass or interfaces are found, we cannot
1082 // load <ik> from the shared archive.
1083
1084 if (ik->super() != nullptr) {
1085 bool check_super = check_shared_class_super_type(ik, ik->super(),
1086 class_loader, true,
1087 CHECK_false);
1088 if (!check_super) {
1089 return false;
1090 }
1091 }
1092
1093 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1094 int num_interfaces = interfaces->length();
1095 for (int index = 0; index < num_interfaces; index++) {
1096 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1097 CHECK_false);
1098 if (!check_interface) {
1099 return false;
1100 }
1101 }
1102
1103 return true;
1104 }
1105
1106 // Pre-load class referred to in non-static null-free instance field. These fields trigger MANDATORY loading.
1107 // Some pre-loading does not fail fatally
1108 bool SystemDictionary::preload_from_null_free_field(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1109 TempNewSymbol name = Signature::strip_envelope(sig);
1110 log_info(class, preload)("Preloading of class %s during loading of shared class %s. "
1111 "Cause: a null-free non-static field is declared with this type",
1112 name->as_C_string(), ik->name()->as_C_string());
1113 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection(ik->name(), name,
1114 class_loader, false, CHECK_false);
1115 if (HAS_PENDING_EXCEPTION) {
1116 log_warning(class, preload)("Preloading of class %s during loading of class %s "
1117 "(cause: null-free non-static field) failed: %s",
1118 name->as_C_string(), ik->name()->as_C_string(),
1119 PENDING_EXCEPTION->klass()->name()->as_C_string());
1120 return false; // Exception is still pending
1121 }
1122
1123 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1124 if (real_k != k) {
1125 // oops, the app has substituted a different version of k! Does not fail fatally
1126 log_warning(class, preload)("Preloading of class %s during loading of shared class %s "
1127 "(cause: null-free non-static field) failed : "
1128 "app substituted a different version of %s",
1129 name->as_C_string(), ik->name()->as_C_string(),
1130 name->as_C_string());
1131 return false;
1132 }
1133 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1134 "(cause: null-free non-static field) succeeded",
1135 name->as_C_string(), ik->name()->as_C_string());
1136
1137 assert(real_k != nullptr, "Sanity check");
1138 InstanceKlass::check_can_be_annotated_with_NullRestricted(real_k, ik->name(), CHECK_false);
1139
1140 return true;
1141 }
1142
1143 // Tries to pre-load classes referred to in non-static nullable instance fields if they are found in the
1144 // loadable descriptors attribute. If loading fails, we can fail silently.
1145 void SystemDictionary::try_preload_from_loadable_descriptors(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1146 TempNewSymbol name = Signature::strip_envelope(sig);
1147 if (name != ik->name() && ik->is_class_in_loadable_descriptors_attribute(sig)) {
1148 log_info(class, preload)("Preloading of class %s during loading of shared class %s. "
1149 "Cause: field type in LoadableDescriptors attribute",
1150 name->as_C_string(), ik->name()->as_C_string());
1151 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection(ik->name(), name,
1152 class_loader, false, THREAD);
1153 if (HAS_PENDING_EXCEPTION) {
1154 CLEAR_PENDING_EXCEPTION;
1155 }
1156
1157 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1158 if (real_k != k) {
1159 // oops, the app has substituted a different version of k!
1160 log_warning(class, preload)("Preloading of class %s during loading of shared class %s "
1161 "(cause: field type in LoadableDescriptors attribute) failed : "
1162 "app substituted a different version of %s",
1163 name->as_C_string(), ik->name()->as_C_string(),
1164 k->name()->as_C_string());
1165 return;
1166 } else if (real_k != nullptr) {
1167 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1168 "(cause: field type in LoadableDescriptors attribute) succeeded",
1169 name->as_C_string(), ik->name()->as_C_string());
1170 }
1171 }
1172 }
1173
1174
1175 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1176 Handle class_loader,
1177 Handle protection_domain,
1178 const ClassFileStream *cfs,
1179 PackageEntry* pkg_entry,
1180 TRAPS) {
1181 assert(ik != nullptr, "sanity");
1182 assert(ik->in_aot_cache(), "sanity");
1183 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1184 assert(AtomicAccess::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1185 Symbol* class_name = ik->name();
1186
1187 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1188 ik->set_shared_loading_failed();
1189 return nullptr;
1190 }
1191
1192 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1193 if (!check) {
1194 ik->set_shared_loading_failed();
1195 return nullptr;
1196 }
1197
1198 if (ik->has_inline_type_fields()) {
1199 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1200 if (fs.access_flags().is_static()) continue;
1201
1202 Symbol* sig = fs.signature();
1203 int field_index = fs.index();
1204
1205 if (fs.is_null_free_inline_type()) {
1206 // A false return means that the class didn't load for other reasons than an exception.
1207 bool check = preload_from_null_free_field(ik, class_loader, sig, field_index, CHECK_NULL);
1208 if (!check) {
1209 ik->set_shared_loading_failed();
1210 return nullptr;
1211 }
1212 } else if (Signature::has_envelope(sig)) {
1213 // Pending exceptions are cleared so we can fail silently
1214 try_preload_from_loadable_descriptors(ik, class_loader, sig, field_index, CHECK_NULL);
1215 }
1216 }
1217 }
1218
1219 InstanceKlass* new_ik = nullptr;
1220 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1221 // It will be skipped for shared VM hidden lambda proxy classes.
1222 if (!ik->is_hidden()) {
1223 new_ik = KlassFactory::check_shared_class_file_load_hook(
1224 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1225 }
1226 if (new_ik != nullptr) {
1227 // The class is changed by CFLH. Return the new class. The shared class is
1228 // not used.
1229 return new_ik;
1230 }
1231
1232 // Adjust methods to recover missing data. They need addresses for
1233 // interpreter entry points and their default native method address
1234 // must be reset.
1235
1236 // Shared classes are all currently loaded by either the bootstrap or
1237 // internal parallel class loaders, so this will never cause a deadlock
1238 // on a custom class loader lock.
1239 // Since this class is already locked with parallel capable class
1240 // loaders, including the bootstrap loader via the placeholder table,
1241 // this lock is currently a nop.
1242
1243 ClassLoaderData* loader_data = class_loader_data(class_loader);
1244 {
1245 HandleMark hm(THREAD);
1246 Handle lockObject = get_loader_lock_or_null(class_loader);
1247 ObjectLocker ol(lockObject, THREAD);
1248 // prohibited package check assumes all classes loaded from archive call
1249 // restore_unshareable_info which calls ik->set_package()
1250 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1251 }
1252
1253 load_shared_class_misc(ik, loader_data);
1254
1255 return ik;
1256 }
1257
1258 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1259 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1260
1261 // For boot loader, ensure that GetSystemPackage knows that a class in this
1262 // package was loaded.
1263 if (loader_data->is_the_null_class_loader_data()) {
1264 s2 path_index = ik->shared_classpath_index();
1265 ik->set_classpath_index(path_index);
1266 }
1267
1268 // notify a class loaded from shared object
1269 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1270
1271 if (CDSConfig::is_dumping_final_static_archive()) {
1272 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1273 }
1274 }
1275
1276 // This is much more lightweight than SystemDictionary::resolve_or_null
1277 // - There's only a single Java thread at this point. No need for placeholder.
1278 // - All supertypes of ik have been loaded
1279 // - There's no circularity (checked in AOT assembly phase)
1280 // - There's no need to call java.lang.ClassLoader::load_class() because the boot/platform/app
1281 // loaders are well-behaved
1282 void SystemDictionary::preload_class(Handle class_loader, InstanceKlass* ik, TRAPS) {
1283 precond(Universe::is_bootstrapping());
1284 precond(java_platform_loader() != nullptr && java_system_loader() != nullptr);
1285 precond(class_loader() == nullptr || class_loader() == java_platform_loader() ||class_loader() == java_system_loader());
1286 precond(CDSConfig::is_using_aot_linked_classes());
1287 precond(AOTMetaspace::in_aot_cache_static_region((void*)ik));
1288 precond(!ik->is_loaded());
1289
1290 #ifdef ASSERT
1291 // preload_class() must be called in the correct order -- all super types must have
1292 // already been loaded.
1293 if (ik->java_super() != nullptr) {
1294 assert(ik->java_super()->is_loaded(), "must be");
1295 }
1296
1297 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1298 int num_interfaces = interfaces->length();
1299 for (int index = 0; index < num_interfaces; index++) {
1300 assert(interfaces->at(index)->is_loaded(), "must be");
1301 }
1302 #endif
1303
1304 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1305 oop java_mirror = ik->archived_java_mirror();
1306 precond(java_mirror != nullptr);
1307
1308 Handle pd(THREAD, java_lang_Class::protection_domain(java_mirror));
1309 PackageEntry* pkg_entry = ik->package();
1310 assert(pkg_entry != nullptr || ClassLoader::package_from_class_name(ik->name()) == nullptr,
1311 "non-empty packages must have been archived");
1312
1313 // TODO: the following assert requires JDK-8365580
1314 // assert(is_shared_class_visible(ik->name(), ik, pkg_entry, class_loader), "must be");
1315
1316 ik->restore_unshareable_info(loader_data, pd, pkg_entry, CHECK);
1317 load_shared_class_misc(ik, loader_data);
1318 ik->add_to_hierarchy(THREAD);
1319
1320 if (!ik->is_hidden()) {
1321 update_dictionary(THREAD, ik, loader_data);
1322 }
1323
1324 assert(java_lang_Class::module(java_mirror) != nullptr, "must have been archived");
1325 assert(ik->is_loaded(), "Must be in at least loaded state");
1326 }
1327
1328 #endif // INCLUDE_CDS
1329
1330 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1331
1332 if (class_loader.is_null()) {
1333 ResourceMark rm(THREAD);
1334 PackageEntry* pkg_entry = nullptr;
1335 bool search_only_bootloader_append = false;
1336
1337 // Find the package in the boot loader's package entry table.
1338 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1339 if (pkg_name != nullptr) {
1340 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1341 }
1342
1343 // Prior to attempting to load the class, enforce the boot loader's
1344 // visibility boundaries.
1345 if (!Universe::is_module_initialized()) {
1346 // During bootstrapping, prior to module initialization, any
1347 // class attempting to be loaded must be checked against the
1348 // java.base packages in the boot loader's PackageEntryTable.
1349 // No class outside of java.base is allowed to be loaded during
1350 // this bootstrapping window.
1351 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1352 // Class is either in the unnamed package or in
1353 // a named package within the unnamed module. Either
1354 // case is outside of java.base, do not attempt to
1355 // load the class post java.base definition. If
1356 // java.base has not been defined, let the class load
1357 // and its package will be checked later by
1358 // ModuleEntryTable::verify_javabase_packages.
1359 if (ModuleEntryTable::javabase_defined()) {
1360 return nullptr;
1361 }
1362 } else {
1363 // Check that the class' package is defined within java.base.
1364 ModuleEntry* mod_entry = pkg_entry->module();
1365 Symbol* mod_entry_name = mod_entry->name();
1366 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1367 return nullptr;
1368 }
1369 }
1370 } else {
1371 // After the module system has been initialized, check if the class'
1372 // package is in a module defined to the boot loader.
1373 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1374 // Class is either in the unnamed package, in a named package
1375 // within a module not defined to the boot loader or in a
1376 // a named package within the unnamed module. In all cases,
1377 // limit visibility to search for the class only in the boot
1378 // loader's append path.
1379 if (!ClassLoader::has_bootclasspath_append()) {
1380 // If there is no bootclasspath append entry, no need to continue
1381 // searching.
1382 return nullptr;
1383 }
1384 search_only_bootloader_append = true;
1385 }
1386 }
1387
1388 // Prior to bootstrapping's module initialization, never load a class outside
1389 // of the boot loader's module path
1390 assert(Universe::is_module_initialized() ||
1391 !search_only_bootloader_append,
1392 "Attempt to load a class outside of boot loader's module path");
1393
1394 // Search for classes in the CDS archive.
1395 InstanceKlass* k = nullptr;
1396
1397 #if INCLUDE_CDS
1398 if (CDSConfig::is_using_archive())
1399 {
1400 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1401 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1402 if (ik != nullptr && ik->defined_by_boot_loader() && !ik->shared_loading_failed()) {
1403 SharedClassLoadingMark slm(THREAD, ik);
1404 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1405 }
1406 }
1407 #endif
1408
1409 if (k == nullptr) {
1410 // Use VM class loader
1411 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1412 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1413 }
1414
1415 // find_or_define_instance_class may return a different InstanceKlass
1416 if (k != nullptr) {
1417 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1418 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1419 }
1420 return k;
1421 } else {
1422 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1423 ResourceMark rm(THREAD);
1424
1425 JavaThread* jt = THREAD;
1426
1427 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1428 ClassLoader::perf_app_classload_selftime(),
1429 ClassLoader::perf_app_classload_count(),
1430 jt->get_thread_stat()->perf_recursion_counts_addr(),
1431 jt->get_thread_stat()->perf_timers_addr(),
1432 PerfClassTraceTime::CLASS_LOAD);
1433
1434 // Translate to external class name format, i.e., convert '/' chars to '.'
1435 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1436
1437 JavaValue result(T_OBJECT);
1438
1439 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1440
1441 // Call public unsynchronized loadClass(String) directly for all class loaders.
1442 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1443 // acquire a class-name based lock rather than the class loader object lock.
1444 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1445 JavaCalls::call_virtual(&result,
1446 class_loader,
1447 spec_klass,
1448 vmSymbols::loadClass_name(),
1449 vmSymbols::string_class_signature(),
1450 string,
1451 CHECK_NULL);
1452
1453 assert(result.get_type() == T_OBJECT, "just checking");
1454 oop obj = result.get_oop();
1455
1456 // Primitive classes return null since forName() cannot be
1457 // used to obtain any of the Class objects representing primitives or void
1458 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1459 InstanceKlass* k = java_lang_Class::as_InstanceKlass(obj);
1460 // For user defined Java class loaders, check that the name returned is
1461 // the same as that requested. This check is done for the bootstrap
1462 // loader when parsing the class file.
1463 if (class_name == k->name()) {
1464 return k;
1465 }
1466 }
1467 // Class is not found or has the wrong name, return null
1468 return nullptr;
1469 }
1470 }
1471
1472 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1473 Handle class_loader,
1474 TRAPS) {
1475
1476 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1477
1478 // If everything was OK (no exceptions, no null return value), and
1479 // class_loader is NOT the defining loader, do a little more bookkeeping.
1480 if (loaded_class != nullptr &&
1481 loaded_class->class_loader() != class_loader()) {
1482
1483 ClassLoaderData* loader_data = class_loader_data(class_loader);
1484 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1485
1486 // Record dependency for non-parent delegation.
1487 // This recording keeps the defining class loader of the klass (loaded_class) found
1488 // from being unloaded while the initiating class loader is loaded
1489 // even if the reference to the defining class loader is dropped
1490 // before references to the initiating class loader.
1491 loader_data->record_dependency(loaded_class);
1492
1493 update_dictionary(THREAD, loaded_class, loader_data);
1494
1495 if (JvmtiExport::should_post_class_load()) {
1496 JvmtiExport::post_class_load(THREAD, loaded_class);
1497 }
1498 }
1499 return loaded_class;
1500 }
1501
1502 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1503 EventClassDefine event;
1504 if (event.should_commit()) {
1505 event.set_definedClass(k);
1506 event.set_definingClassLoader(def_cld);
1507 event.commit();
1508 }
1509 }
1510
1511 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1512
1513 ClassLoaderData* loader_data = k->class_loader_data();
1514 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1515
1516 // Bootstrap and other parallel classloaders don't acquire a lock,
1517 // they use placeholder token.
1518 // If a parallelCapable class loader calls define_instance_class instead of
1519 // find_or_define_instance_class to get here, we have a timing
1520 // hole with systemDictionary updates and check_constraints
1521 if (!is_parallelCapable(class_loader)) {
1522 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1523 get_loader_lock_or_null(class_loader)),
1524 "define called without lock");
1525 }
1526
1527 // Check class-loading constraints. Throw exception if violation is detected.
1528 // Grabs and releases SystemDictionary_lock
1529 // The check_constraints/find_class call and update_dictionary sequence
1530 // must be "atomic" for a specific class/classloader pair so we never
1531 // define two different instanceKlasses for that class/classloader pair.
1532 // Existing classloaders will call define_instance_class with the
1533 // classloader lock held
1534 // Parallel classloaders will call find_or_define_instance_class
1535 // which will require a token to perform the define class
1536 check_constraints(k, loader_data, true, CHECK);
1537
1538 // Register class just loaded with class loader (placed in ArrayList)
1539 // Note we do this before updating the dictionary, as this can
1540 // fail with an OutOfMemoryError (if it does, we will *not* put this
1541 // class in the dictionary and will not update the class hierarchy).
1542 // JVMTI FollowReferences needs to find the classes this way.
1543 if (k->class_loader() != nullptr) {
1544 methodHandle m(THREAD, Universe::loader_addClass_method());
1545 JavaValue result(T_VOID);
1546 JavaCallArguments args(class_loader);
1547 args.push_oop(Handle(THREAD, k->java_mirror()));
1548 JavaCalls::call(&result, m, &args, CHECK);
1549 }
1550
1551 // Add to class hierarchy, and do possible deoptimizations.
1552 k->add_to_hierarchy(THREAD);
1553
1554 // Add to systemDictionary - so other classes can see it.
1555 // Grabs and releases SystemDictionary_lock
1556 update_dictionary(THREAD, k, loader_data);
1557
1558 // notify jvmti
1559 if (JvmtiExport::should_post_class_load()) {
1560 JvmtiExport::post_class_load(THREAD, k);
1561 }
1562 post_class_define_event(k, loader_data);
1563 }
1564
1565 // Support parallel classloading
1566 // All parallel class loaders, including bootstrap classloader
1567 // lock a placeholder entry for this class/class_loader pair
1568 // to allow parallel defines of different classes for this class loader
1569 // With AllowParallelDefine flag==true, in case they do not synchronize around
1570 // FindLoadedClass/DefineClass, calls, we check for parallel
1571 // loading for them, wait if a defineClass is in progress
1572 // and return the initial requestor's results
1573 // This flag does not apply to the bootstrap classloader.
1574 // With AllowParallelDefine flag==false, call through to define_instance_class
1575 // which will throw LinkageError: duplicate class definition.
1576 // False is the requested default.
1577 // For better performance, the class loaders should synchronize
1578 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1579 // potentially waste time reading and parsing the bytestream.
1580 // Note: VM callers should ensure consistency of k/class_name,class_loader
1581 // Be careful when modifying this code: once you have run
1582 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1583 // you need to find_and_remove it before returning.
1584 // So be careful to not exit with a CHECK_ macro between these calls.
1585 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1586 InstanceKlass* k, TRAPS) {
1587
1588 Symbol* name_h = k->name();
1589 ClassLoaderData* loader_data = class_loader_data(class_loader);
1590 Dictionary* dictionary = loader_data->dictionary();
1591
1592 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1593 {
1594 MutexLocker mu(THREAD, SystemDictionary_lock);
1595 // First check if class already defined
1596 if (is_parallelDefine(class_loader)) {
1597 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1598 if (check != nullptr) {
1599 return check;
1600 }
1601 }
1602
1603 // Acquire define token for this class/classloader
1604 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1605 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1606 // Wait if another thread defining in parallel
1607 // All threads wait - even those that will throw duplicate class: otherwise
1608 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1609 // if other thread has not finished updating dictionary
1610 while (probe->definer() != nullptr) {
1611 SystemDictionary_lock->wait();
1612 }
1613 // Only special cases allow parallel defines and can use other thread's results
1614 // Other cases fall through, and may run into duplicate defines
1615 // caught by finding an entry in the SystemDictionary
1616 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1617 InstanceKlass* ik = probe->instance_klass();
1618 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1619 SystemDictionary_lock->notify_all();
1620 #ifdef ASSERT
1621 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1622 assert(check != nullptr, "definer missed recording success");
1623 #endif
1624 return ik;
1625 } else {
1626 // This thread will define the class (even if earlier thread tried and had an error)
1627 probe->set_definer(THREAD);
1628 }
1629 }
1630
1631 define_instance_class(k, class_loader, THREAD);
1632
1633 // definer must notify any waiting threads
1634 {
1635 MutexLocker mu(THREAD, SystemDictionary_lock);
1636 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1637 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1638 if (!HAS_PENDING_EXCEPTION) {
1639 probe->set_instance_klass(k);
1640 }
1641 probe->set_definer(nullptr);
1642 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1643 SystemDictionary_lock->notify_all();
1644 }
1645
1646 return HAS_PENDING_EXCEPTION ? nullptr : k;
1647 }
1648
1649 // If a class loader supports parallel classloading handle parallel define requests.
1650 // find_or_define_instance_class may return a different InstanceKlass
1651 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1652 InstanceKlass* k, TRAPS) {
1653 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1654 // Clean up original InstanceKlass if duplicate or error
1655 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1656 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1657 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1658 k->class_loader_data()->add_to_deallocate_list(k);
1659 } else if (HAS_PENDING_EXCEPTION) {
1660 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1661 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1662 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1663 k->class_loader_data()->add_to_deallocate_list(k);
1664 }
1665 return defined_k;
1666 }
1667
1668
1669 // ----------------------------------------------------------------------------
1670 // GC support
1671
1672 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1673 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1674
1675 bool unloading_occurred;
1676 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1677 {
1678 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1679 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1680 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1681 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1682 if (unloading_occurred) {
1683 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1684 JFR_ONLY(Jfr::on_unloading_classes();)
1685 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1686 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1687 ClassLoaderDataGraph::clean_module_and_package_info();
1688 LoaderConstraintTable::purge_loader_constraints();
1689 ResolutionErrorTable::purge_resolution_errors();
1690 }
1691 }
1692
1693 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1694
1695 if (unloading_occurred) {
1696 SymbolTable::trigger_cleanup();
1697
1698 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1699 InstanceKlass::clean_initialization_error_table();
1700 }
1701
1702 return unloading_occurred;
1703 }
1704
1705 void SystemDictionary::methods_do(void f(Method*)) {
1706 // Walk methods in loaded classes
1707
1708 {
1709 MutexLocker ml(ClassLoaderDataGraph_lock);
1710 ClassLoaderDataGraph::methods_do(f);
1711 }
1712
1713 auto doit = [&] (InvokeMethodKey key, Method* method) {
1714 if (method != nullptr) {
1715 f(method);
1716 }
1717 };
1718
1719 {
1720 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1721 _invoke_method_intrinsic_table->iterate_all(doit);
1722 }
1723
1724 }
1725
1726 // ----------------------------------------------------------------------------
1727 // Initialization
1728
1729 void SystemDictionary::initialize(TRAPS) {
1730 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1731 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1732 ResolutionErrorTable::initialize();
1733 LoaderConstraintTable::initialize();
1734 PlaceholderTable::initialize();
1735 #if INCLUDE_CDS
1736 SystemDictionaryShared::initialize();
1737 if (CDSConfig::is_dumping_archive()) {
1738 AOTClassLocationConfig::dumptime_init(THREAD);
1739 }
1740 #endif
1741 // Resolve basic classes
1742 vmClasses::resolve_all(CHECK);
1743 // Resolve classes used by archived heap objects
1744 if (CDSConfig::is_using_archive()) {
1745 HeapShared::resolve_classes(THREAD);
1746 }
1747 }
1748
1749 // Constraints on class loaders. The details of the algorithm can be
1750 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1751 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1752 // that the dictionary needs to maintain a set of constraints that
1753 // must be satisfied by all classes in the dictionary.
1754 // if defining is true, then LinkageError if already in dictionary
1755 // if initiating loader, then ok if InstanceKlass matches existing entry
1756
1757 void SystemDictionary::check_constraints(InstanceKlass* k,
1758 ClassLoaderData* loader_data,
1759 bool defining,
1760 TRAPS) {
1761 ResourceMark rm(THREAD);
1762 stringStream ss;
1763 bool throwException = false;
1764
1765 {
1766 Symbol* name = k->name();
1767
1768 MutexLocker mu(THREAD, SystemDictionary_lock);
1769
1770 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1771 if (check != nullptr) {
1772 // If different InstanceKlass - duplicate class definition,
1773 // else - ok, class loaded by a different thread in parallel.
1774 // We should only have found it if it was done loading and ok to use.
1775
1776 if ((defining == true) || (k != check)) {
1777 throwException = true;
1778 ss.print("loader %s", loader_data->loader_name_and_id());
1779 ss.print(" attempted duplicate %s definition for %s. (%s)",
1780 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1781 } else {
1782 return;
1783 }
1784 }
1785
1786 if (throwException == false) {
1787 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1788 throwException = true;
1789 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1790 ss.print(" wants to load %s %s.",
1791 k->external_kind(), k->external_name());
1792 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1793 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1794 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1795 existing_klass->external_kind(),
1796 existing_klass->class_loader_data()->loader_name_and_id(),
1797 existing_klass->class_in_module_of_loader(false, true));
1798 } else {
1799 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1800 }
1801 }
1802 }
1803 }
1804
1805 // Throw error now if needed (cannot throw while holding
1806 // SystemDictionary_lock because of rank ordering)
1807 if (throwException == true) {
1808 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1809 }
1810 }
1811
1812 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1813 // have been called.
1814 void SystemDictionary::update_dictionary(JavaThread* current,
1815 InstanceKlass* k,
1816 ClassLoaderData* loader_data) {
1817 MonitorLocker mu1(SystemDictionary_lock);
1818
1819 // Make a new dictionary entry.
1820 Symbol* name = k->name();
1821 Dictionary* dictionary = loader_data->dictionary();
1822 InstanceKlass* sd_check = dictionary->find_class(current, name);
1823 if (sd_check == nullptr) {
1824 dictionary->add_klass(current, name, k);
1825 }
1826 mu1.notify_all();
1827 }
1828
1829 // Indicate that loader_data has initiated the loading of class k, which
1830 // has already been defined by a parent loader.
1831 // This API is used by AOTLinkedClassBulkLoader and to register boxing
1832 // classes from java.lang in all class loaders to enable more value
1833 // classes optimizations
1834 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1835 InstanceKlass* k,
1836 ClassLoaderData* loader_data) {
1837 assert_locked_or_safepoint(SystemDictionary_lock);
1838 Symbol* name = k->name();
1839 Dictionary* dictionary = loader_data->dictionary();
1840 assert(k->is_loaded(), "must be");
1841 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1842 if (dictionary->find_class(current, name) == nullptr) {
1843 dictionary->add_klass(current, name, k);
1844 }
1845 }
1846
1847 // Try to find a class name using the loader constraints. The
1848 // loader constraints might know about a class that isn't fully loaded
1849 // yet and these will be ignored.
1850 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1851 Thread* current, Symbol* class_name, Handle class_loader) {
1852
1853 // First see if it has been loaded directly.
1854 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1855 if (klass != nullptr)
1856 return klass;
1857
1858 // Now look to see if it has been loaded elsewhere, and is subject to
1859 // a loader constraint that would require this loader to return the
1860 // klass that is already loaded.
1861 if (Signature::is_array(class_name)) {
1862 // For array classes, their Klass*s are not kept in the
1863 // constraint table. The element Klass*s are.
1864 SignatureStream ss(class_name, false);
1865 int ndims = ss.skip_array_prefix(); // skip all '['s
1866 BasicType t = ss.type();
1867 if (t != T_OBJECT) {
1868 klass = Universe::typeArrayKlass(t);
1869 } else {
1870 MutexLocker mu(current, SystemDictionary_lock);
1871 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1872 }
1873 // If element class already loaded, allocate array klass
1874 if (klass != nullptr) {
1875 klass = klass->array_klass_or_null(ndims);
1876 }
1877 } else {
1878 MutexLocker mu(current, SystemDictionary_lock);
1879 // Non-array classes are easy: simply check the constraint table.
1880 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1881 }
1882
1883 return klass;
1884 }
1885
1886 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1887 Klass* klass_being_linked,
1888 Handle class_loader1,
1889 Handle class_loader2) {
1890 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1891 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1892
1893 Symbol* constraint_name = nullptr;
1894
1895 if (!Signature::is_array(class_name)) {
1896 constraint_name = class_name;
1897 } else {
1898 // For array classes, their Klass*s are not kept in the
1899 // constraint table. The element classes are.
1900 SignatureStream ss(class_name, false);
1901 ss.skip_array_prefix(); // skip all '['s
1902 if (!ss.has_envelope()) {
1903 return true; // primitive types always pass
1904 }
1905 constraint_name = ss.as_symbol();
1906 // Increment refcount to keep constraint_name alive after
1907 // SignatureStream is destructed. It will be decremented below
1908 // before returning.
1909 constraint_name->increment_refcount();
1910 }
1911
1912 Dictionary* dictionary1 = loader_data1->dictionary();
1913 Dictionary* dictionary2 = loader_data2->dictionary();
1914
1915 JavaThread* current = JavaThread::current();
1916 {
1917 MutexLocker mu_s(SystemDictionary_lock);
1918 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1919 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1920 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1921 klass2, loader_data2);
1922 #if INCLUDE_CDS
1923 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1924 !klass_being_linked->in_aot_cache()) {
1925 SystemDictionaryShared::record_linking_constraint(constraint_name,
1926 InstanceKlass::cast(klass_being_linked),
1927 class_loader1, class_loader2);
1928 }
1929 #endif // INCLUDE_CDS
1930 if (Signature::is_array(class_name)) {
1931 constraint_name->decrement_refcount();
1932 }
1933 return result;
1934 }
1935 }
1936
1937 // Add entry to resolution error table to record the error when the first
1938 // attempt to resolve a reference to a class has failed.
1939 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1940 Symbol* error, const char* message,
1941 Symbol* cause, const char* cause_msg) {
1942 {
1943 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1944 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1945 if (entry == nullptr) {
1946 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1947 }
1948 }
1949 }
1950
1951 // Delete a resolution error for RedefineClasses for a constant pool is going away
1952 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1953 ResolutionErrorTable::delete_entry(pool);
1954 }
1955
1956 // Lookup resolution error table. Returns error if found, otherwise null.
1957 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1958 const char** message,
1959 Symbol** cause, const char** cause_msg) {
1960
1961 {
1962 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1963 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1964 if (entry != nullptr) {
1965 *message = entry->message();
1966 *cause = entry->cause();
1967 *cause_msg = entry->cause_msg();
1968 return entry->error();
1969 } else {
1970 return nullptr;
1971 }
1972 }
1973 }
1974
1975 // Add an entry to resolution error table to record an error in resolving or
1976 // validating a nest host. This is used to construct informative error
1977 // messages when IllegalAccessError's occur. If an entry already exists it will
1978 // be updated with the nest host error message.
1979
1980 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1981 int which,
1982 const char* message) {
1983 {
1984 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1985 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1986 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1987 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1988 // still want to add the error message for the higher-level access checks to report. We should
1989 // only reach here under the same error condition, so we can ignore the potential race with setting
1990 // the message. If we see it is already set then we can ignore it.
1991 entry->set_nest_host_error(message);
1992 } else {
1993 ResolutionErrorTable::add_entry(pool, which, message);
1994 }
1995 }
1996 }
1997
1998 // Lookup any nest host error
1999 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
2000 {
2001 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2002 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
2003 if (entry != nullptr) {
2004 return entry->nest_host_error();
2005 } else {
2006 return nullptr;
2007 }
2008 }
2009 }
2010
2011 // Signature constraints ensure that callers and callees agree about
2012 // the meaning of type names in their signatures. This routine is the
2013 // intake for constraints. It collects them from several places:
2014 //
2015 // * LinkResolver::resolve_method (if check_access is true) requires
2016 // that the resolving class (the caller) and the defining class of
2017 // the resolved method (the callee) agree on each type in the
2018 // method's signature.
2019 //
2020 // * LinkResolver::resolve_interface_method performs exactly the same
2021 // checks.
2022 //
2023 // * LinkResolver::resolve_field requires that the constant pool
2024 // attempting to link to a field agree with the field's defining
2025 // class about the type of the field signature.
2026 //
2027 // * klassVtable::initialize_vtable requires that, when a class
2028 // overrides a vtable entry allocated by a superclass, that the
2029 // overriding method (i.e., the callee) agree with the superclass
2030 // on each type in the method's signature.
2031 //
2032 // * klassItable::initialize_itable requires that, when a class fills
2033 // in its itables, for each non-abstract method installed in an
2034 // itable, the method (i.e., the callee) agree with the interface
2035 // on each type in the method's signature.
2036 //
2037 // All those methods have a boolean (check_access, checkconstraints)
2038 // which turns off the checks. This is used from specialized contexts
2039 // such as bootstrapping, dumping, and debugging.
2040 //
2041 // No direct constraint is placed between the class and its
2042 // supertypes. Constraints are only placed along linked relations
2043 // between callers and callees. When a method overrides or implements
2044 // an abstract method in a supertype (superclass or interface), the
2045 // constraints are placed as if the supertype were the caller to the
2046 // overriding method. (This works well, since callers to the
2047 // supertype have already established agreement between themselves and
2048 // the supertype.) As a result of all this, a class can disagree with
2049 // its supertype about the meaning of a type name, as long as that
2050 // class neither calls a relevant method of the supertype, nor is
2051 // called (perhaps via an override) from the supertype.
2052 //
2053 //
2054 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
2055 //
2056 // Make sure all class components (including arrays) in the given
2057 // signature will be resolved to the same class in both loaders.
2058 // Returns the name of the type that failed a loader constraint check, or
2059 // null if no constraint failed. No exception except OOME is thrown.
2060 // Arrays are not added to the loader constraint table, their elements are.
2061 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2062 Klass* klass_being_linked,
2063 Handle loader1, Handle loader2,
2064 bool is_method) {
2065 // Nothing to do if loaders are the same.
2066 if (loader1() == loader2()) {
2067 return nullptr;
2068 }
2069
2070 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2071 if (ss.is_reference()) {
2072 Symbol* sig = ss.as_symbol();
2073 // Note: In the future, if template-like types can take
2074 // arguments, we will want to recognize them and dig out class
2075 // names hiding inside the argument lists.
2076 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2077 return sig;
2078 }
2079 }
2080 }
2081 return nullptr;
2082 }
2083
2084 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2085 Symbol* signature,
2086 TRAPS) {
2087
2088 const int iid_as_int = vmIntrinsics::as_int(iid);
2089 assert(MethodHandles::is_signature_polymorphic(iid) &&
2090 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2091 iid != vmIntrinsics::_invokeGeneric,
2092 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2093
2094 InvokeMethodKey key(signature, iid_as_int);
2095 Method** met = nullptr;
2096
2097 // We only want one entry in the table for this (signature/id, method) pair but the code
2098 // to create the intrinsic method needs to be outside the lock.
2099 // The first thread claims the entry by adding the key and the other threads wait, until the
2100 // Method has been added as the value.
2101 {
2102 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2103 while (true) {
2104 bool created;
2105 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2106 assert(met != nullptr, "either created or found");
2107 if (*met != nullptr) {
2108 return *met;
2109 } else if (created) {
2110 // The current thread won the race and will try to create the full entry.
2111 break;
2112 } else {
2113 // Another thread beat us to it, so wait for them to complete
2114 // and return *met; or if they hit an error we get another try.
2115 ml.wait();
2116 // Note it is not safe to read *met here as that entry could have
2117 // been deleted, so we must loop and try put_if_absent again.
2118 }
2119 }
2120 }
2121
2122 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2123 bool throw_error = HAS_PENDING_EXCEPTION;
2124 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2125 // Generate a compiled form of the MH intrinsic
2126 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2127 AdapterHandlerLibrary::create_native_wrapper(m);
2128 // Check if have the compiled code.
2129 throw_error = (!m->has_compiled_code());
2130 }
2131
2132 {
2133 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2134 if (throw_error) {
2135 // Remove the entry and let another thread try, or get the same exception.
2136 bool removed = _invoke_method_intrinsic_table->remove(key);
2137 assert(removed, "must be the owner");
2138 ml.notify_all();
2139 } else {
2140 signature->make_permanent(); // The signature is never unloaded.
2141 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2142 m->code()->entry_point() == m->from_compiled_entry()),
2143 "MH intrinsic invariant");
2144 *met = m(); // insert the element
2145 ml.notify_all();
2146 return m();
2147 }
2148 }
2149
2150 // Throw OOM or the pending exception in the JavaThread
2151 if (throw_error && !HAS_PENDING_EXCEPTION) {
2152 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2153 "Out of space in CodeCache for method handle intrinsic");
2154 }
2155 return nullptr;
2156 }
2157
2158 #if INCLUDE_CDS
2159 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2160 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2161 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2162 methods->append(m);
2163 };
2164 _invoke_method_intrinsic_table->iterate_all(do_method);
2165 }
2166
2167 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2168 if (UseSharedSpaces) {
2169 EXCEPTION_MARK;
2170 restore_archived_method_handle_intrinsics_impl(THREAD);
2171 if (HAS_PENDING_EXCEPTION) {
2172 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2173 // the archived method handle intrinsics, so we can't really recover from this failure.
2174 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2175 }
2176 }
2177 }
2178
2179 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2180 Array<Method*>* list = AOTMetaspace::archived_method_handle_intrinsics();
2181 for (int i = 0; i < list->length(); i++) {
2182 methodHandle m(THREAD, list->at(i));
2183 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2184 m->constants()->restore_unshareable_info(CHECK);
2185 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2186 AdapterHandlerLibrary::create_native_wrapper(m);
2187 if (!m->has_compiled_code()) {
2188 ResourceMark rm(THREAD);
2189 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2190 }
2191 }
2192
2193 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2194 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2195 // possible to have a contention.
2196 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2197 InvokeMethodKey key(m->signature(), iid_as_int);
2198 bool created = _invoke_method_intrinsic_table->put(key, m());
2199 assert(created, "unexpected contention");
2200 }
2201 }
2202 #endif // INCLUDE_CDS
2203
2204 // Helper for unpacking the return value from linkMethod and linkCallSite.
2205 static Method* unpack_method_and_appendix(Handle mname,
2206 Klass* accessing_klass,
2207 objArrayHandle appendix_box,
2208 Handle* appendix_result,
2209 TRAPS) {
2210 if (mname.not_null()) {
2211 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2212 if (m != nullptr) {
2213 oop appendix = appendix_box->obj_at(0);
2214 LogTarget(Info, methodhandles) lt;
2215 if (lt.develop_is_enabled()) {
2216 ResourceMark rm(THREAD);
2217 LogStream ls(lt);
2218 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2219 m->print_on(&ls);
2220 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2221 ls.cr();
2222 }
2223
2224 (*appendix_result) = Handle(THREAD, appendix);
2225 // the target is stored in the cpCache and if a reference to this
2226 // MemberName is dropped we need a way to make sure the
2227 // class_loader containing this method is kept alive.
2228 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2229 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2230 this_key->record_dependency(m->method_holder());
2231 return mh();
2232 }
2233 }
2234 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2235 }
2236
2237 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2238 Symbol* name,
2239 Symbol* signature,
2240 Klass* accessing_klass,
2241 Handle* appendix_result,
2242 TRAPS) {
2243 guarantee(THREAD->can_call_java(), "");
2244 Handle method_type =
2245 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2246
2247 int ref_kind = JVM_REF_invokeVirtual;
2248 oop name_oop = StringTable::intern(name, CHECK_NULL);
2249 Handle name_str (THREAD, name_oop);
2250 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2251 assert(appendix_box->obj_at(0) == nullptr, "");
2252
2253 // This should not happen. JDK code should take care of that.
2254 if (accessing_klass == nullptr || method_type.is_null()) {
2255 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2256 }
2257
2258 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2259 JavaCallArguments args;
2260 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2261 args.push_int(ref_kind);
2262 args.push_oop(Handle(THREAD, klass->java_mirror()));
2263 args.push_oop(name_str);
2264 args.push_oop(method_type);
2265 args.push_oop(appendix_box);
2266 JavaValue result(T_OBJECT);
2267 JavaCalls::call_static(&result,
2268 vmClasses::MethodHandleNatives_klass(),
2269 vmSymbols::linkMethod_name(),
2270 vmSymbols::linkMethod_signature(),
2271 &args, CHECK_NULL);
2272 Handle mname(THREAD, result.get_oop());
2273 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2274 }
2275
2276 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2277 // We must ensure that all class loaders everywhere will reach this class, for any client.
2278 // This is a safe bet for public classes in java.lang, such as Object and String.
2279 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2280 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2281 static bool is_always_visible_class(oop mirror) {
2282 Klass* klass = java_lang_Class::as_Klass(mirror);
2283 if (klass->is_objArray_klass()) {
2284 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2285 }
2286 if (klass->is_typeArray_klass()) {
2287 return true; // primitive array
2288 }
2289 assert(klass->is_instance_klass(), "%s", klass->external_name());
2290 return klass->is_public() &&
2291 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2292 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2293 }
2294
2295 // Find or construct the Java mirror (java.lang.Class instance) for
2296 // the given field type signature, as interpreted relative to the
2297 // given class loader. Handles primitives, void, references, arrays,
2298 // and all other reflectable types, except method types.
2299 // N.B. Code in reflection should use this entry point.
2300 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2301 Klass* accessing_klass,
2302 SignatureStream::FailureMode failure_mode,
2303 TRAPS) {
2304
2305 Handle class_loader;
2306
2307 // What we have here must be a valid field descriptor,
2308 // and all valid field descriptors are supported.
2309 // Produce the same java.lang.Class that reflection reports.
2310 if (accessing_klass != nullptr) {
2311 class_loader = Handle(THREAD, accessing_klass->class_loader());
2312 }
2313 ResolvingSignatureStream ss(signature, class_loader, false);
2314 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2315 if (mirror_oop == nullptr) {
2316 return Handle(); // report failure this way
2317 }
2318 Handle mirror(THREAD, mirror_oop);
2319
2320 if (accessing_klass != nullptr) {
2321 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2322 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2323 if (sel_klass != nullptr) {
2324 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2325 }
2326 }
2327 return mirror;
2328 }
2329
2330
2331 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2332 // signature, as interpreted relative to the given class loader.
2333 // Because of class loader constraints, all method handle usage must be
2334 // consistent with this loader.
2335 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2336 Klass* accessing_klass,
2337 TRAPS) {
2338 Handle empty;
2339 OopHandle* o;
2340 {
2341 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2342 o = _invoke_method_type_table->get(signature);
2343 }
2344
2345 if (o != nullptr) {
2346 oop mt = o->resolve();
2347 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2348 return Handle(THREAD, mt);
2349 } else if (!THREAD->can_call_java()) {
2350 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2351 return Handle(); // do not attempt from within compiler, unless it was cached
2352 }
2353
2354 Handle class_loader;
2355 if (accessing_klass != nullptr) {
2356 class_loader = Handle(THREAD, accessing_klass->class_loader());
2357 }
2358 bool can_be_cached = true;
2359 int npts = ArgumentCount(signature).size();
2360 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2361 int arg = 0;
2362 Handle rt; // the return type from the signature
2363 ResourceMark rm(THREAD);
2364 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2365 oop mirror = nullptr;
2366 if (can_be_cached) {
2367 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2368 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty));
2369 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2370 // Fall back to accessing_klass context.
2371 can_be_cached = false;
2372 }
2373 }
2374 if (!can_be_cached) {
2375 // Resolve, throwing a real error if it doesn't work.
2376 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2377 }
2378 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2379 if (ss.at_return_type())
2380 rt = Handle(THREAD, mirror);
2381 else
2382 pts->obj_at_put(arg++, mirror);
2383
2384 // Check accessibility.
2385 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2386 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2387 mirror = nullptr; // safety
2388 // Emulate ConstantPool::verify_constant_pool_resolve.
2389 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2390 }
2391 }
2392 assert(arg == npts, "");
2393
2394 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2395 JavaCallArguments args(Handle(THREAD, rt()));
2396 args.push_oop(pts);
2397 JavaValue result(T_OBJECT);
2398 JavaCalls::call_static(&result,
2399 vmClasses::MethodHandleNatives_klass(),
2400 vmSymbols::findMethodHandleType_name(),
2401 vmSymbols::findMethodHandleType_signature(),
2402 &args, CHECK_(empty));
2403 Handle method_type(THREAD, result.get_oop());
2404
2405 if (can_be_cached) {
2406 // We can cache this MethodType inside the JVM.
2407 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2408 bool created = false;
2409 assert(method_type != nullptr, "unexpected null");
2410 OopHandle* h = _invoke_method_type_table->get(signature);
2411 if (h == nullptr) {
2412 signature->make_permanent(); // The signature is never unloaded.
2413 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2414 bool created = _invoke_method_type_table->put(signature, elem);
2415 assert(created, "better be created");
2416 }
2417 }
2418 // report back to the caller with the MethodType
2419 return method_type;
2420 }
2421
2422 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2423 Klass* accessing_klass,
2424 TRAPS) {
2425 Handle empty;
2426 ResourceMark rm(THREAD);
2427 SignatureStream ss(signature, /*is_method=*/ false);
2428 if (!ss.is_done()) {
2429 Handle class_loader;
2430 if (accessing_klass != nullptr) {
2431 class_loader = Handle(THREAD, accessing_klass->class_loader());
2432 }
2433 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2434 ss.next();
2435 if (ss.is_done()) {
2436 return Handle(THREAD, mirror);
2437 }
2438 }
2439 return empty;
2440 }
2441
2442 // Ask Java code to find or construct a method handle constant.
2443 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2444 int ref_kind, //e.g., JVM_REF_invokeVirtual
2445 Klass* callee,
2446 Symbol* name,
2447 Symbol* signature,
2448 TRAPS) {
2449 Handle empty;
2450 if (caller == nullptr) {
2451 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2452 }
2453 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2454 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2455
2456 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2457 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2458 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2459 java_lang_invoke_MemberName::set_name (mname(), name_str());
2460 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2461 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2462
2463 if (ref_kind == JVM_REF_invokeVirtual &&
2464 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2465 // Skip resolution for public signature polymorphic methods such as
2466 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2467 // They require appendix argument which MemberName resolution doesn't handle.
2468 // There's special logic on JDK side to handle them
2469 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2470 } else {
2471 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2472 }
2473
2474 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2475 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2476
2477 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2478 JavaCallArguments args;
2479 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2480 args.push_int(ref_kind);
2481 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2482 args.push_oop(name_str);
2483 args.push_oop(type);
2484 JavaValue result(T_OBJECT);
2485 JavaCalls::call_static(&result,
2486 vmClasses::MethodHandleNatives_klass(),
2487 vmSymbols::linkMethodHandleConstant_name(),
2488 vmSymbols::linkMethodHandleConstant_signature(),
2489 &args, CHECK_(empty));
2490 return Handle(THREAD, result.get_oop());
2491 }
2492
2493 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2494 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2495 // with linkage results being stored back into the bootstrap specifier.
2496 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2497 // Resolve the bootstrap specifier, its name, type, and static arguments
2498 bootstrap_specifier.resolve_bsm(CHECK);
2499
2500 // This should not happen. JDK code should take care of that.
2501 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2502 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2503 }
2504
2505 bool is_indy = bootstrap_specifier.is_method_call();
2506 objArrayHandle appendix_box;
2507 if (is_indy) {
2508 // Some method calls may require an appendix argument. Arrange to receive it.
2509 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2510 assert(appendix_box->obj_at(0) == nullptr, "");
2511 }
2512
2513 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2514 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2515 JavaCallArguments args;
2516 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2517 args.push_oop(bootstrap_specifier.bsm());
2518 args.push_oop(bootstrap_specifier.name_arg());
2519 args.push_oop(bootstrap_specifier.type_arg());
2520 args.push_oop(bootstrap_specifier.arg_values());
2521 if (is_indy) {
2522 args.push_oop(appendix_box);
2523 }
2524 JavaValue result(T_OBJECT);
2525 JavaCalls::call_static(&result,
2526 vmClasses::MethodHandleNatives_klass(),
2527 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2528 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2529 &args, CHECK);
2530
2531 Handle value(THREAD, result.get_oop());
2532 if (is_indy) {
2533 Handle appendix;
2534 Method* method = unpack_method_and_appendix(value,
2535 bootstrap_specifier.caller(),
2536 appendix_box,
2537 &appendix, CHECK);
2538 methodHandle mh(THREAD, method);
2539 bootstrap_specifier.set_resolved_method(mh, appendix);
2540 } else {
2541 bootstrap_specifier.set_resolved_value(value);
2542 }
2543
2544 // sanity check
2545 assert(bootstrap_specifier.is_resolved() ||
2546 (bootstrap_specifier.is_method_call() &&
2547 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2548 }
2549
2550
2551 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2552 assert(m != nullptr, "Unexpected nullptr Method*");
2553 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2554 }
2555
2556 // ----------------------------------------------------------------------------
2557
2558 void SystemDictionary::print_on(outputStream *st) {
2559 CDS_ONLY(SystemDictionaryShared::print_on(st));
2560 GCMutexLocker mu(SystemDictionary_lock);
2561
2562 ClassLoaderDataGraph::print_dictionary(st);
2563
2564 // Placeholders
2565 PlaceholderTable::print_on(st);
2566 st->cr();
2567
2568 // loader constraints - print under SD_lock
2569 LoaderConstraintTable::print_on(st);
2570 st->cr();
2571 }
2572
2573 void SystemDictionary::print() { print_on(tty); }
2574
2575 void SystemDictionary::verify() {
2576
2577 GCMutexLocker mu(SystemDictionary_lock);
2578
2579 // Verify dictionary
2580 ClassLoaderDataGraph::verify_dictionary();
2581
2582 // Verify constraint table
2583 LoaderConstraintTable::verify();
2584 }
2585
2586 void SystemDictionary::dump(outputStream *st, bool verbose) {
2587 assert_locked_or_safepoint(SystemDictionary_lock);
2588 if (verbose) {
2589 print_on(st);
2590 } else {
2591 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2592 ClassLoaderDataGraph::print_table_statistics(st);
2593 LoaderConstraintTable::print_table_statistics(st);
2594 }
2595 }
2596
2597 // Utility for dumping dictionaries.
2598 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2599 DCmdWithParser(output, heap),
2600 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2601 "BOOLEAN", false, "false") {
2602 _dcmdparser.add_dcmd_option(&_verbose);
2603 }
2604
2605 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2606 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2607 _verbose.value());
2608 VMThread::execute(&dumper);
2609 }