1 /*
2 * Copyright (c) 1997, 2024, 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 "precompiled.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/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/packageEntry.hpp"
40 #include "classfile/placeholders.hpp"
41 #include "classfile/protectionDomainCache.hpp"
42 #include "classfile/resolutionErrors.hpp"
43 #include "classfile/stringTable.hpp"
44 #include "classfile/symbolTable.hpp"
45 #include "classfile/systemDictionary.hpp"
46 #include "classfile/vmClasses.hpp"
47 #include "classfile/vmSymbols.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "interpreter/bootstrapInfo.hpp"
50 #include "jfr/jfrEvents.hpp"
51 #include "jvm.h"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/metaspaceClosure.hpp"
55 #include "memory/oopFactory.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/fieldStreams.inline.hpp"
60 #include "oops/instanceKlass.hpp"
61 #include "oops/klass.inline.hpp"
62 #include "oops/method.inline.hpp"
63 #include "oops/objArrayKlass.hpp"
64 #include "oops/objArrayOop.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oop.hpp"
67 #include "oops/oopHandle.hpp"
68 #include "oops/oopHandle.inline.hpp"
69 #include "oops/symbol.hpp"
70 #include "oops/typeArrayKlass.hpp"
71 #include "oops/inlineKlass.inline.hpp"
72 #include "prims/jvmtiExport.hpp"
73 #include "prims/methodHandles.hpp"
74 #include "runtime/arguments.hpp"
75 #include "runtime/atomic.hpp"
76 #include "runtime/handles.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/mutexLocker.hpp"
80 #include "runtime/os.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/signature.hpp"
83 #include "runtime/synchronizer.hpp"
84 #include "services/classLoadingService.hpp"
85 #include "services/diagnosticCommand.hpp"
86 #include "services/finalizerService.hpp"
87 #include "services/threadService.hpp"
88 #include "utilities/macros.hpp"
89 #include "utilities/utf8.hpp"
90 #if INCLUDE_CDS
91 #include "classfile/systemDictionaryShared.hpp"
92 #endif
93 #if INCLUDE_JFR
94 #include "jfr/jfr.hpp"
95 #endif
96
97 class InvokeMethodKey : public StackObj {
98 private:
99 Symbol* _symbol;
100 intptr_t _iid;
101
102 public:
103 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
104 _symbol(symbol),
105 _iid(iid) {}
106
107 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
108 return k1._symbol == k2._symbol && k1._iid == k2._iid;
109 }
110
111 static unsigned int compute_hash(const InvokeMethodKey &k) {
112 Symbol* sym = k._symbol;
113 intptr_t iid = k._iid;
114 unsigned int hash = (unsigned int) sym -> identity_hash();
115 return (unsigned int) (hash ^ iid);
116 }
117
118 };
119
120 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
121 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
122 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
123 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
124 static InvokeMethodTypeTable* _invoke_method_type_table;
125
126 OopHandle SystemDictionary::_java_system_loader;
127 OopHandle SystemDictionary::_java_platform_loader;
128
129 // ----------------------------------------------------------------------------
130 // Java-level SystemLoader and PlatformLoader
131 oop SystemDictionary::java_system_loader() {
132 return _java_system_loader.resolve();
133 }
134
135 oop SystemDictionary::java_platform_loader() {
136 return _java_platform_loader.resolve();
137 }
138
139 void SystemDictionary::compute_java_loaders(TRAPS) {
140 if (_java_system_loader.is_empty()) {
141 oop system_loader = get_system_class_loader_impl(CHECK);
142 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
143 } else {
144 // It must have been restored from the archived module graph
145 assert(UseSharedSpaces, "must be");
146 assert(CDSConfig::is_loading_full_module_graph(), "must be");
147 DEBUG_ONLY(
148 oop system_loader = get_system_class_loader_impl(CHECK);
149 assert(_java_system_loader.resolve() == system_loader, "must be");
150 )
151 }
152
153 if (_java_platform_loader.is_empty()) {
154 oop platform_loader = get_platform_class_loader_impl(CHECK);
155 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
156 } else {
157 // It must have been restored from the archived module graph
158 assert(UseSharedSpaces, "must be");
159 assert(CDSConfig::is_loading_full_module_graph(), "must be");
160 DEBUG_ONLY(
161 oop platform_loader = get_platform_class_loader_impl(CHECK);
162 assert(_java_platform_loader.resolve() == platform_loader, "must be");
163 )
164 }
165 }
166
167 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
168 JavaValue result(T_OBJECT);
169 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
170 JavaCalls::call_static(&result,
171 class_loader_klass,
172 vmSymbols::getSystemClassLoader_name(),
173 vmSymbols::void_classloader_signature(),
174 CHECK_NULL);
175 return result.get_oop();
176 }
177
178 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
179 JavaValue result(T_OBJECT);
180 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
181 JavaCalls::call_static(&result,
182 class_loader_klass,
183 vmSymbols::getPlatformClassLoader_name(),
184 vmSymbols::void_classloader_signature(),
185 CHECK_NULL);
186 return result.get_oop();
187 }
188
189 // Helper function
190 inline ClassLoaderData* class_loader_data(Handle class_loader) {
191 return ClassLoaderData::class_loader_data(class_loader());
192 }
193
194 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
195 if (create_mirror_cld) {
196 // Add a new class loader data to the graph.
197 return ClassLoaderDataGraph::add(class_loader, true);
198 } else {
199 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
200 ClassLoaderDataGraph::find_or_create(class_loader);
201 }
202 }
203
204 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
205 assert(_java_system_loader.is_empty(), "already set!");
206 _java_system_loader = cld->class_loader_handle();
207
208 }
209
210 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
211 assert(_java_platform_loader.is_empty(), "already set!");
212 _java_platform_loader = cld->class_loader_handle();
213 }
214
215 // ----------------------------------------------------------------------------
216 // Parallel class loading check
217
218 bool is_parallelCapable(Handle class_loader) {
219 if (class_loader.is_null()) return true;
220 return java_lang_ClassLoader::parallelCapable(class_loader());
221 }
222 // ----------------------------------------------------------------------------
223 // ParallelDefineClass flag does not apply to bootclass loader
224 bool is_parallelDefine(Handle class_loader) {
225 if (class_loader.is_null()) return false;
226 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
227 return true;
228 }
229 return false;
230 }
231
232 // Returns true if the passed class loader is the builtin application class loader
233 // or a custom system class loader. A customer system class loader can be
234 // specified via -Djava.system.class.loader.
235 bool SystemDictionary::is_system_class_loader(oop class_loader) {
236 if (class_loader == nullptr) {
237 return false;
238 }
239 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
240 class_loader == _java_system_loader.peek());
241 }
242
243 // Returns true if the passed class loader is the platform class loader.
244 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
245 if (class_loader == nullptr) {
246 return false;
247 }
248 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
249 }
250
251 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
252 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
253 if (is_parallelCapable(class_loader)) {
254 return Handle();
255 } else {
256 return class_loader;
257 }
258 }
259
260 // ----------------------------------------------------------------------------
261 // Resolving of classes
262
263 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
264 if (name == nullptr) {
265 THROW_MSG_0(exception, "No class name given");
266 }
267 if ((int)strlen(name) > Symbol::max_length()) {
268 // It's impossible to create this class; the name cannot fit
269 // into the constant pool.
270 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
271 "Class name exceeds maximum length of %d: %s",
272 Symbol::max_length(),
273 name);
274 return nullptr;
275 }
276 // Callers should ensure that the name is never an illegal UTF8 string.
277 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
278 "Class name is not a valid utf8 string.");
279
280 // Make a new symbol for the class name.
281 return SymbolTable::new_symbol(name);
282 }
283
284 #ifdef ASSERT
285 // Used to verify that class loading succeeded in adding k to the dictionary.
286 void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
287 MutexLocker mu(SystemDictionary_lock);
288 ClassLoaderData* loader_data = k->class_loader_data();
289 Dictionary* dictionary = loader_data->dictionary();
290 assert(class_name == k->name(), "Must be the same");
291 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
292 assert(kk == k, "should be present in dictionary");
293 }
294 #endif
295
296 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
297 if (HAS_PENDING_EXCEPTION) {
298 // If we have a pending exception we forward it to the caller, unless throw_error is true,
299 // in which case we have to check whether the pending exception is a ClassNotFoundException,
300 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
301 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
302 ResourceMark rm(THREAD);
303 Handle e(THREAD, PENDING_EXCEPTION);
304 CLEAR_PENDING_EXCEPTION;
305 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
306 } else {
307 return; // the caller will throw the incoming exception
308 }
309 }
310 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
311 // error or exception depending on the value of throw_error.
312 ResourceMark rm(THREAD);
313 if (throw_error) {
314 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
315 } else {
316 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
317 }
318 }
319
320 // Forwards to resolve_or_null
321
322 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
323 bool throw_error, TRAPS) {
324 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
325 // Check for pending exception or null klass, and throw exception
326 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
327 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
328 }
329 return klass;
330 }
331
332 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
333
334 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
335 if (Signature::is_array(class_name)) {
336 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
337 } else {
338 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
339 if (Signature::has_envelope(class_name)) {
340 ResourceMark rm(THREAD);
341 // Ignore wrapping L and ; (and Q and ; for value types).
342 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
343 class_name->utf8_length() - 2);
344 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
345 } else {
346 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
347 }
348 }
349 }
350
351 // Forwards to resolve_instance_class_or_null
352
353 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
354 Handle class_loader,
355 Handle protection_domain,
356 TRAPS) {
357 assert(Signature::is_array(class_name), "must be array");
358 ResourceMark rm(THREAD);
359 SignatureStream ss(class_name, false);
360 int ndims = ss.skip_array_prefix(); // skip all '['s
361 Klass* k = nullptr;
362 BasicType t = ss.type();
363 if (ss.has_envelope()) {
364 Symbol* obj_class = ss.as_symbol();
365 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
366 class_loader,
367 protection_domain,
368 CHECK_NULL);
369 if (k != nullptr) {
370 k = k->array_klass(ndims, CHECK_NULL);
371 }
372 } else {
373 k = Universe::typeArrayKlassObj(t);
374 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
375 }
376 return k;
377 }
378
379 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
380 LogTarget(Debug, class, load, placeholders) lt;
381 if (lt.is_enabled()) {
382 ResourceMark rm;
383 LogStream ls(lt);
384 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
385 probe->print_on(&ls);
386 ls.cr();
387 }
388 }
389
390 // Must be called for any superclass or superinterface resolution
391 // during class definition to allow class circularity checking
392 // superinterface callers:
393 // parse_interfaces - from defineClass
394 // superclass callers:
395 // ClassFileParser - from defineClass
396 // load_shared_class - while loading a class from shared archive
397 // resolve_instance_class_or_null:
398 // via: handle_parallel_super_load
399 // when resolving a class that has an existing placeholder with
400 // a saved superclass [i.e. a defineClass is currently in progress]
401 // If another thread is trying to resolve the class, it must do
402 // superclass checks on its own thread to catch class circularity and
403 // to avoid deadlock.
404 //
405 // resolve_with_circularity_detection_or_fail adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
406 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
407 // placeholder for the same thread, class, classloader is found.
408 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
409 //
410 InstanceKlass* SystemDictionary::resolve_with_circularity_detection_or_fail(Symbol* class_name,
411 Symbol* next_name,
412 Handle class_loader,
413 Handle protection_domain,
414 bool is_superclass,
415 TRAPS) {
416
417 assert(next_name != nullptr, "null superclass for resolving");
418 assert(!Signature::is_array(next_name), "invalid superclass name");
419 #if INCLUDE_CDS
420 if (CDSConfig::is_dumping_static_archive()) {
421 // Special processing for handling UNREGISTERED shared classes.
422 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
423 next_name, is_superclass);
424 if (k) {
425 return k;
426 }
427 }
428 #endif // INCLUDE_CDS
429
430 // If klass is already loaded, just return the superclass or superinterface.
431 // Make sure there's a placeholder for the class_name before resolving.
432 // This is used as a claim that this thread is currently loading superclass/classloader
433 // and for ClassCircularity checks.
434
435 ClassLoaderData* loader_data = class_loader_data(class_loader);
436 Dictionary* dictionary = loader_data->dictionary();
437
438 // can't throw error holding a lock
439 bool throw_circularity_error = false;
440 {
441 MutexLocker mu(THREAD, SystemDictionary_lock);
442 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
443 InstanceKlass* quicksuperk;
444 // To support parallel loading: if class is done loading, just return the superclass
445 // if the next_name matches class->super()->name() and if the class loaders match.
446 // Otherwise, a LinkageError will be thrown later.
447 if (klassk != nullptr && is_superclass &&
448 ((quicksuperk = klassk->java_super()) != nullptr) &&
449 ((quicksuperk->name() == next_name) &&
450 (quicksuperk->class_loader() == class_loader()))) {
451 return quicksuperk;
452 } else {
453 // Must check ClassCircularity before checking if superclass is already loaded.
454 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
455 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
456 log_circularity_error(class_name, probe);
457 throw_circularity_error = true;
458 }
459 }
460
461 if (!throw_circularity_error) {
462 // Be careful not to exit resolve_super without removing this placeholder.
463 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
464 loader_data,
465 PlaceholderTable::DETECT_CIRCULARITY,
466 next_name, THREAD);
467 }
468 }
469
470 if (throw_circularity_error) {
471 ResourceMark rm(THREAD);
472 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
473 }
474
475 // Resolve the superclass or superinterface, check results on return
476 InstanceKlass* superk =
477 SystemDictionary::resolve_instance_class_or_null(next_name,
478 class_loader,
479 protection_domain,
480 THREAD);
481
482 // Clean up placeholder entry.
483 {
484 MutexLocker mu(THREAD, SystemDictionary_lock);
485 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
486 SystemDictionary_lock->notify_all();
487 }
488
489 // Check for pending exception or null superk, and throw exception
490 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
491 handle_resolution_exception(next_name, true, CHECK_NULL);
492 }
493
494 return superk;
495 }
496
497 // If the class in is in the placeholder table, class loading is in progress.
498 // For cases where the application changes threads to load classes, it
499 // is critical to ClassCircularity detection that we try loading
500 // the superclass on the new thread internally, so we do parallel
501 // superclass loading here. This avoids deadlock for ClassCircularity
502 // detection for parallelCapable class loaders that lock on a per-class lock.
503 static void handle_parallel_super_load(Symbol* name,
504 Symbol* superclassname,
505 Handle class_loader,
506 Handle protection_domain, TRAPS) {
507
508 // superk is not used; resolve_super_or_fail is called for circularity check only.
509 Klass* superk = SystemDictionary::resolve_with_circularity_detection_or_fail(name,
510 superclassname,
511 class_loader,
512 protection_domain,
513 false,
514 CHECK);
515 }
516
517 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
518 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
519 static bool needs_load_placeholder(Handle class_loader) {
520 return class_loader.is_null() || !is_parallelCapable(class_loader);
521 }
522
523 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
524 static InstanceKlass* handle_parallel_loading(JavaThread* current,
525 Symbol* name,
526 ClassLoaderData* loader_data,
527 bool must_wait_for_class_loading,
528 bool* throw_circularity_error) {
529 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
530 if (oldprobe != nullptr) {
531 // -Xcomp calls load_signature_classes which might result in loading
532 // a class that's already in the process of loading, so we detect CCE here also.
533 // Only need check_seen_thread once, not on each loop
534 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
535 log_circularity_error(name, oldprobe);
536 *throw_circularity_error = true;
537 return nullptr;
538 } else if (must_wait_for_class_loading) {
539 // Wait until the first thread has finished loading this class. Also wait until all the
540 // threads trying to load its superclass have removed their placeholders.
541 while (oldprobe != nullptr &&
542 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
543
544 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
545 // for the bootclass loader.
546 SystemDictionary_lock->wait();
547
548 // Check if classloading completed while we were waiting
549 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
550 if (check != nullptr) {
551 // Klass is already loaded, so just return it
552 return check;
553 }
554 // check if other thread failed to load and cleaned up
555 oldprobe = PlaceholderTable::get_entry(name, loader_data);
556 }
557 }
558 }
559 return nullptr;
560 }
561
562 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
563 assert(event != nullptr, "invariant");
564 assert(k != nullptr, "invariant");
565 event->set_loadedClass(k);
566 event->set_definingClassLoader(k->class_loader_data());
567 event->set_initiatingClassLoader(init_cld);
568 event->commit();
569 }
570
571 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
572 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
573 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
574 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
575 // This can return null, an exception or an InstanceKlass.
576 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
577 Handle class_loader,
578 Handle protection_domain,
579 TRAPS) {
580 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
581 assert(name != nullptr && !Signature::is_array(name) &&
582 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
583
584 EventClassLoad class_load_start_event;
585
586 HandleMark hm(THREAD);
587
588 // Fix for 4474172; see evaluation for more details
589 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
590 ClassLoaderData* loader_data = register_loader(class_loader);
591 Dictionary* dictionary = loader_data->dictionary();
592
593 // Do lookup to see if class already exists and the protection domain
594 // has the right access.
595 // This call uses find which checks protection domain already matches
596 // All subsequent calls use find_class, and set loaded_class so that
597 // before we return a result, we call out to java to check for valid protection domain.
598 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
599 if (probe != nullptr) return probe;
600
601 // Non-bootstrap class loaders will call out to class loader and
602 // define via jvm/jni_DefineClass which will acquire the
603 // class loader object lock to protect against multiple threads
604 // defining the class in parallel by accident.
605 // This lock must be acquired here so the waiter will find
606 // any successful result in the SystemDictionary and not attempt
607 // the define.
608 // ParallelCapable class loaders and the bootstrap classloader
609 // do not acquire lock here.
610 Handle lockObject = get_loader_lock_or_null(class_loader);
611 ObjectLocker ol(lockObject, THREAD);
612
613 bool circularity_detection_in_progress = false;
614 InstanceKlass* loaded_class = nullptr;
615 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
616
617 guarantee(THREAD->can_call_java(),
618 "can not load classes with compiler thread: class=%s, classloader=%s",
619 name->as_C_string(),
620 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
621
622 // Check again (after locking) if the class already exists in SystemDictionary
623 {
624 MutexLocker mu(THREAD, SystemDictionary_lock);
625 InstanceKlass* check = dictionary->find_class(THREAD, name);
626 if (check != nullptr) {
627 // InstanceKlass is already loaded, but we still need to check protection domain below.
628 loaded_class = check;
629 } else {
630 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
631 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
632 circularity_detection_in_progress = true;
633 superclassname = placeholder->next_klass_name();
634 assert(superclassname != nullptr, "superclass has to have a name");
635 }
636 }
637 }
638
639 // If the class is in the placeholder table with super_class set,
640 // handle superclass loading in progress.
641 if (circularity_detection_in_progress) {
642 handle_parallel_super_load(name, superclassname,
643 class_loader,
644 protection_domain,
645 CHECK_NULL);
646 }
647
648 bool throw_circularity_error = false;
649 if (loaded_class == nullptr) {
650 bool load_placeholder_added = false;
651
652 // Add placeholder entry to record loading instance class
653 // case 1. Bootstrap classloader
654 // This classloader supports parallelism at the classloader level
655 // but only allows a single thread to load a class/classloader pair.
656 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
657 // case 2. parallelCapable user level classloaders
658 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
659 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
660 // case 3. traditional classloaders that rely on the classloader object lock
661 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
662 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
663 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
664 {
665 MutexLocker mu(THREAD, SystemDictionary_lock);
666 if (needs_load_placeholder(class_loader)) {
667 loaded_class = handle_parallel_loading(THREAD,
668 name,
669 loader_data,
670 class_loader.is_null(),
671 &throw_circularity_error);
672 }
673
674 // Recheck if the class has been loaded for all class loader cases and
675 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
676 if (!throw_circularity_error && loaded_class == nullptr) {
677 InstanceKlass* check = dictionary->find_class(THREAD, name);
678 if (check != nullptr) {
679 loaded_class = check;
680 } else if (needs_load_placeholder(class_loader)) {
681 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
682 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
683 PlaceholderTable::LOAD_INSTANCE,
684 nullptr,
685 THREAD);
686 load_placeholder_added = true;
687 }
688 }
689 }
690
691 // Must throw error outside of owning lock
692 if (throw_circularity_error) {
693 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
694 ResourceMark rm(THREAD);
695 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
696 }
697
698 // Be careful when modifying this code: once you have run
699 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
700 // you need to find_and_remove it before returning.
701 // So be careful to not exit with a CHECK_ macro between these calls.
702
703 if (loaded_class == nullptr) {
704 // Do actual loading
705 loaded_class = load_instance_class(name, class_loader, THREAD);
706 }
707
708 if (load_placeholder_added) {
709 // clean up placeholder entries for LOAD_INSTANCE success or error
710 // This brackets the SystemDictionary updates for both defining
711 // and initiating loaders
712 MutexLocker mu(THREAD, SystemDictionary_lock);
713 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
714 SystemDictionary_lock->notify_all();
715 }
716 }
717
718 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
719 return nullptr;
720 }
721
722 if (class_load_start_event.should_commit()) {
723 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
724 }
725
726 // Make sure we have the right class in the dictionary
727 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
728
729 // Check if the protection domain is present it has the right access
730 if (protection_domain() != nullptr) {
731 // Verify protection domain. If it fails an exception is thrown
732 dictionary->validate_protection_domain(loaded_class, class_loader, protection_domain, CHECK_NULL);
733 }
734
735 return loaded_class;
736 }
737
738
739 // This routine does not lock the system dictionary.
740 //
741 // Since readers don't hold a lock, we must make sure that system
742 // dictionary entries are added to in a safe way (all links must
743 // be updated in an MT-safe manner). All entries are removed during class
744 // unloading, when this class loader is no longer referenced.
745 //
746 // Callers should be aware that an entry could be added just after
747 // Dictionary is read here, so the caller will not see
748 // the new entry.
749
750 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
751 Symbol* class_name,
752 Handle class_loader,
753 Handle protection_domain) {
754
755 // The result of this call should be consistent with the result
756 // of the call to resolve_instance_class_or_null().
757 // See evaluation 6790209 and 4474172 for more details.
758 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
759 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
760
761 if (loader_data == nullptr) {
762 // If the ClassLoaderData has not been setup,
763 // then the class loader has no entries in the dictionary.
764 return nullptr;
765 }
766
767 Dictionary* dictionary = loader_data->dictionary();
768 return dictionary->find(current, class_name, protection_domain);
769 }
770
771 // Look for a loaded instance or array klass by name. Do not do any loading.
772 // return null in case of error.
773 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
774 Symbol* class_name,
775 Handle class_loader,
776 Handle protection_domain) {
777 Klass* k = nullptr;
778 assert(class_name != nullptr, "class name must be non nullptr");
779
780 if (Signature::is_array(class_name)) {
781 // The name refers to an array. Parse the name.
782 // dimension and object_key in FieldArrayInfo are assigned as a
783 // side-effect of this call
784 SignatureStream ss(class_name, false);
785 int ndims = ss.skip_array_prefix(); // skip all '['s
786 BasicType t = ss.type();
787 if (t != T_OBJECT) {
788 k = Universe::typeArrayKlassObj(t);
789 } else {
790 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
791 }
792 if (k != nullptr) {
793 k = k->array_klass_or_null(ndims);
794 }
795 } else {
796 k = find_instance_klass(current, class_name, class_loader, protection_domain);
797 }
798 return k;
799 }
800
801 // Note: this method is much like resolve_class_from_stream, but
802 // does not publish the classes in the SystemDictionary.
803 // Handles Lookup.defineClass hidden.
804 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
805 ClassFileStream* st,
806 Symbol* class_name,
807 Handle class_loader,
808 const ClassLoadInfo& cl_info,
809 TRAPS) {
810
811 EventClassLoad class_load_start_event;
812 ClassLoaderData* loader_data;
813
814 // - for hidden classes that are not strong: create a new CLD that has a class holder and
815 // whose loader is the Lookup class's loader.
816 // - for hidden class: add the class to the Lookup class's loader's CLD.
817 assert (cl_info.is_hidden(), "only used for hidden classes");
818 bool create_mirror_cld = !cl_info.is_strong_hidden();
819 loader_data = register_loader(class_loader, create_mirror_cld);
820
821 assert(st != nullptr, "invariant");
822 assert(st->need_verify(), "invariant");
823
824 // Parse stream and create a klass.
825 InstanceKlass* k = KlassFactory::create_from_stream(st,
826 class_name,
827 loader_data,
828 cl_info,
829 CHECK_NULL);
830 assert(k != nullptr, "no klass created");
831
832 // Hidden classes that are not strong must update ClassLoaderData holder
833 // so that they can be unloaded when the mirror is no longer referenced.
834 if (!cl_info.is_strong_hidden()) {
835 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
836 }
837
838 // Add to class hierarchy, and do possible deoptimizations.
839 k->add_to_hierarchy(THREAD);
840 // But, do not add to dictionary.
841
842 k->link_class(CHECK_NULL);
843
844 // notify jvmti
845 if (JvmtiExport::should_post_class_load()) {
846 JvmtiExport::post_class_load(THREAD, k);
847 }
848 if (class_load_start_event.should_commit()) {
849 post_class_load_event(&class_load_start_event, k, loader_data);
850 }
851
852 return k;
853 }
854
855 // Add a klass to the system from a stream (called by jni_DefineClass and
856 // JVM_DefineClass).
857 // Note: class_name can be null. In that case we do not know the name of
858 // the class until we have parsed the stream.
859 // This function either returns an InstanceKlass or throws an exception. It does
860 // not return null without a pending exception.
861 InstanceKlass* SystemDictionary::resolve_class_from_stream(
862 ClassFileStream* st,
863 Symbol* class_name,
864 Handle class_loader,
865 const ClassLoadInfo& cl_info,
866 TRAPS) {
867
868 HandleMark hm(THREAD);
869
870 ClassLoaderData* loader_data = register_loader(class_loader);
871
872 // Classloaders that support parallelism, e.g. bootstrap classloader,
873 // do not acquire lock here
874 Handle lockObject = get_loader_lock_or_null(class_loader);
875 ObjectLocker ol(lockObject, THREAD);
876
877 // Parse the stream and create a klass.
878 // Note that we do this even though this klass might
879 // already be present in the SystemDictionary, otherwise we would not
880 // throw potential ClassFormatErrors.
881 InstanceKlass* k = nullptr;
882
883 #if INCLUDE_CDS
884 if (!CDSConfig::is_dumping_static_archive()) {
885 k = SystemDictionaryShared::lookup_from_stream(class_name,
886 class_loader,
887 cl_info.protection_domain(),
888 st,
889 CHECK_NULL);
890 }
891 #endif
892
893 if (k == nullptr) {
894 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
895 }
896
897 assert(k != nullptr, "no klass created");
898 Symbol* h_name = k->name();
899 assert(class_name == nullptr || class_name == h_name, "name mismatch");
900
901 // Add class just loaded
902 // If a class loader supports parallel classloading, handle parallel define requests.
903 // find_or_define_instance_class may return a different InstanceKlass,
904 // in which case the old k would be deallocated
905 if (is_parallelCapable(class_loader)) {
906 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
907 } else {
908 define_instance_class(k, class_loader, THREAD);
909
910 // If defining the class throws an exception register 'k' for cleanup.
911 if (HAS_PENDING_EXCEPTION) {
912 assert(k != nullptr, "Must have an instance klass here!");
913 loader_data->add_to_deallocate_list(k);
914 return nullptr;
915 }
916 }
917
918 // Make sure we have an entry in the SystemDictionary on success
919 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
920
921 return k;
922 }
923
924 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
925 Symbol* class_name,
926 Handle class_loader,
927 const ClassLoadInfo& cl_info,
928 TRAPS) {
929 if (cl_info.is_hidden()) {
930 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
931 } else {
932 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
933 }
934 }
935
936
937 #if INCLUDE_CDS
938 // Check if a shared class can be loaded by the specific classloader.
939 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
940 InstanceKlass* ik,
941 PackageEntry* pkg_entry,
942 Handle class_loader) {
943 assert(!Arguments::module_patching_disables_cds(), "Cannot use CDS");
944
945 // (1) Check if we are loading into the same loader as in dump time.
946
947 if (ik->is_shared_boot_class()) {
948 if (class_loader() != nullptr) {
949 return false;
950 }
951 } else if (ik->is_shared_platform_class()) {
952 if (class_loader() != java_platform_loader()) {
953 return false;
954 }
955 } else if (ik->is_shared_app_class()) {
956 if (class_loader() != java_system_loader()) {
957 return false;
958 }
959 } else {
960 // ik was loaded by a custom loader during dump time
961 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
962 return false;
963 } else {
964 return true;
965 }
966 }
967
968 // (2) Check if we are loading into the same module from the same location as in dump time.
969
970 if (MetaspaceShared::use_optimized_module_handling()) {
971 // Class visibility has not changed between dump time and run time, so a class
972 // that was visible (and thus archived) during dump time is always visible during runtime.
973 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
974 "visibility cannot change between dump time and runtime");
975 return true;
976 }
977 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
978 }
979
980 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
981 InstanceKlass* ik,
982 PackageEntry* pkg_entry,
983 Handle class_loader) {
984 int scp_index = ik->shared_classpath_index();
985 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
986 assert(scp_index >= 0, "must be");
987 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
988 if (!Universe::is_module_initialized()) {
989 assert(scp_entry != nullptr, "must be");
990 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
991 // has restricted the classes can be loaded at this step to be only:
992 // [1] scp_entry->is_modules_image(): classes in java.base, or,
993 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
994 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
995 "only these classes can be loaded before the module system is initialized");
996 assert(class_loader.is_null(), "sanity");
997 return true;
998 }
999
1000 if (pkg_entry == nullptr) {
1001 // We might have looked up pkg_entry before the module system was initialized.
1002 // Need to reload it now.
1003 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1004 if (pkg_name != nullptr) {
1005 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1006 }
1007 }
1008
1009 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1010 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1011 bool was_archived_from_named_module = scp_entry->in_named_module();
1012 bool visible;
1013
1014 if (was_archived_from_named_module) {
1015 if (should_be_in_named_module) {
1016 // Is the module loaded from the same location as during dump time?
1017 visible = mod_entry->shared_path_index() == scp_index;
1018 if (visible) {
1019 assert(!Arguments::module_patching_disables_cds(), "Cannot use CDS");
1020 }
1021 } else {
1022 // During dump time, this class was in a named module, but at run time, this class should be
1023 // in an unnamed module.
1024 visible = false;
1025 }
1026 } else {
1027 if (should_be_in_named_module) {
1028 // During dump time, this class was in an unnamed, but at run time, this class should be
1029 // in a named module.
1030 visible = false;
1031 } else {
1032 visible = true;
1033 }
1034 }
1035
1036 return visible;
1037 }
1038
1039 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1040 Handle class_loader, Handle protection_domain,
1041 bool is_superclass, TRAPS) {
1042 assert(super_type->is_shared(), "must be");
1043
1044 // Quick check if the super type has been already loaded.
1045 // + Don't do it for unregistered classes -- they can be unloaded so
1046 // super_type->class_loader_data() could be stale.
1047 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1048 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1049 // Check if the superclass is loaded by the current class_loader
1050 Symbol* name = super_type->name();
1051 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1052 if (check == super_type) {
1053 return true;
1054 }
1055 }
1056
1057 Klass *found = resolve_with_circularity_detection_or_fail(klass->name(), super_type->name(),
1058 class_loader, protection_domain, is_superclass, CHECK_0);
1059 if (found == super_type) {
1060 return true;
1061 } else {
1062 // The dynamically resolved super type is not the same as the one we used during dump time,
1063 // so we cannot use the class.
1064 return false;
1065 }
1066 }
1067
1068 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1069 Handle protection_domain, TRAPS) {
1070 // Check the superclass and interfaces. They must be the same
1071 // as in dump time, because the layout of <ik> depends on
1072 // the specific layout of ik->super() and ik->local_interfaces().
1073 //
1074 // If unexpected superclass or interfaces are found, we cannot
1075 // load <ik> from the shared archive.
1076
1077 if (ik->super() != nullptr &&
1078 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1079 class_loader, protection_domain, true, THREAD)) {
1080 return false;
1081 }
1082
1083 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1084 int num_interfaces = interfaces->length();
1085 for (int index = 0; index < num_interfaces; index++) {
1086 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1087 return false;
1088 }
1089 }
1090
1091 return true;
1092 }
1093
1094 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1095 Handle class_loader,
1096 Handle protection_domain,
1097 PackageEntry* pkg_entry,
1098 TRAPS) {
1099 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1100 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1101 Symbol* cn = shared_nest_host->name();
1102 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1103 if (s != shared_nest_host) {
1104 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1105 // so we cannot use ik.
1106 return nullptr;
1107 } else {
1108 assert(s->is_shared(), "must be");
1109 }
1110
1111 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1112
1113 if (loaded_ik != nullptr) {
1114 assert(shared_nest_host->is_same_class_package(ik),
1115 "lambda proxy class and its nest host must be in the same package");
1116 }
1117
1118 // The lambda proxy class and its nest host have the same class loader and class loader data,
1119 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1120 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1121 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1122 ik->set_nest_host(shared_nest_host);
1123
1124 return loaded_ik;
1125 }
1126
1127 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1128 Handle class_loader,
1129 Handle protection_domain,
1130 const ClassFileStream *cfs,
1131 PackageEntry* pkg_entry,
1132 TRAPS) {
1133 assert(ik != nullptr, "sanity");
1134 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1135 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1136 Symbol* class_name = ik->name();
1137
1138 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1139 return nullptr;
1140 }
1141
1142 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1143 return nullptr;
1144 }
1145
1146 if (ik->has_inline_type_fields()) {
1147 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1148 if (fs.access_flags().is_static()) continue;
1149 Symbol* sig = fs.signature();
1150 if (fs.is_null_free_inline_type()) {
1151 // Pre-load inline class
1152 TempNewSymbol name = Signature::strip_envelope(sig);
1153 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1154 class_loader, protection_domain, false, CHECK_NULL);
1155 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1156 if (real_k != k) {
1157 // oops, the app has substituted a different version of k!
1158 return nullptr;
1159 }
1160 } else if (Signature::has_envelope(sig)) {
1161 TempNewSymbol name = Signature::strip_envelope(sig);
1162 if (name != ik->name() && ik->is_class_in_preload_attribute(name)) {
1163 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1164 class_loader, protection_domain, false, THREAD);
1165 if (HAS_PENDING_EXCEPTION) {
1166 CLEAR_PENDING_EXCEPTION;
1167 }
1168 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1169 if (real_k != k) {
1170 // oops, the app has substituted a different version of k!
1171 return nullptr;
1172 }
1173 }
1174 }
1175 }
1176 }
1177
1178 InstanceKlass* new_ik = nullptr;
1179 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1180 // It will be skipped for shared VM hidden lambda proxy classes.
1181 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1182 new_ik = KlassFactory::check_shared_class_file_load_hook(
1183 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1184 }
1185 if (new_ik != nullptr) {
1186 // The class is changed by CFLH. Return the new class. The shared class is
1187 // not used.
1188 return new_ik;
1189 }
1190
1191 // Adjust methods to recover missing data. They need addresses for
1192 // interpreter entry points and their default native method address
1193 // must be reset.
1194
1195 // Shared classes are all currently loaded by either the bootstrap or
1196 // internal parallel class loaders, so this will never cause a deadlock
1197 // on a custom class loader lock.
1198 // Since this class is already locked with parallel capable class
1199 // loaders, including the bootstrap loader via the placeholder table,
1200 // this lock is currently a nop.
1201
1202 ClassLoaderData* loader_data = class_loader_data(class_loader);
1203 {
1204 HandleMark hm(THREAD);
1205 Handle lockObject = get_loader_lock_or_null(class_loader);
1206 ObjectLocker ol(lockObject, THREAD);
1207 // prohibited package check assumes all classes loaded from archive call
1208 // restore_unshareable_info which calls ik->set_package()
1209 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1210 }
1211
1212 load_shared_class_misc(ik, loader_data);
1213
1214 return ik;
1215 }
1216
1217 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1218 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1219
1220 // For boot loader, ensure that GetSystemPackage knows that a class in this
1221 // package was loaded.
1222 if (loader_data->is_the_null_class_loader_data()) {
1223 s2 path_index = ik->shared_classpath_index();
1224 ik->set_classpath_index(path_index);
1225 }
1226
1227 // notify a class loaded from shared object
1228 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1229 }
1230
1231 #endif // INCLUDE_CDS
1232
1233 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1234
1235 if (class_loader.is_null()) {
1236 ResourceMark rm(THREAD);
1237 PackageEntry* pkg_entry = nullptr;
1238 bool search_only_bootloader_append = false;
1239
1240 // Find the package in the boot loader's package entry table.
1241 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1242 if (pkg_name != nullptr) {
1243 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1244 }
1245
1246 // Prior to attempting to load the class, enforce the boot loader's
1247 // visibility boundaries.
1248 if (!Universe::is_module_initialized()) {
1249 // During bootstrapping, prior to module initialization, any
1250 // class attempting to be loaded must be checked against the
1251 // java.base packages in the boot loader's PackageEntryTable.
1252 // No class outside of java.base is allowed to be loaded during
1253 // this bootstrapping window.
1254 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1255 // Class is either in the unnamed package or in
1256 // a named package within the unnamed module. Either
1257 // case is outside of java.base, do not attempt to
1258 // load the class post java.base definition. If
1259 // java.base has not been defined, let the class load
1260 // and its package will be checked later by
1261 // ModuleEntryTable::verify_javabase_packages.
1262 if (ModuleEntryTable::javabase_defined()) {
1263 return nullptr;
1264 }
1265 } else {
1266 // Check that the class' package is defined within java.base.
1267 ModuleEntry* mod_entry = pkg_entry->module();
1268 Symbol* mod_entry_name = mod_entry->name();
1269 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1270 return nullptr;
1271 }
1272 }
1273 } else {
1274 // After the module system has been initialized, check if the class'
1275 // package is in a module defined to the boot loader.
1276 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1277 // Class is either in the unnamed package, in a named package
1278 // within a module not defined to the boot loader or in a
1279 // a named package within the unnamed module. In all cases,
1280 // limit visibility to search for the class only in the boot
1281 // loader's append path.
1282 if (!ClassLoader::has_bootclasspath_append()) {
1283 // If there is no bootclasspath append entry, no need to continue
1284 // searching.
1285 return nullptr;
1286 }
1287 search_only_bootloader_append = true;
1288 }
1289 }
1290
1291 // Prior to bootstrapping's module initialization, never load a class outside
1292 // of the boot loader's module path
1293 assert(Universe::is_module_initialized() ||
1294 !search_only_bootloader_append,
1295 "Attempt to load a class outside of boot loader's module path");
1296
1297 // Search for classes in the CDS archive.
1298 InstanceKlass* k = nullptr;
1299
1300 #if INCLUDE_CDS
1301 if (UseSharedSpaces)
1302 {
1303 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1304 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1305 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1306 SharedClassLoadingMark slm(THREAD, ik);
1307 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1308 }
1309 }
1310 #endif
1311
1312 if (k == nullptr) {
1313 // Use VM class loader
1314 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1315 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1316 }
1317
1318 // find_or_define_instance_class may return a different InstanceKlass
1319 if (k != nullptr) {
1320 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1321 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1322 }
1323 return k;
1324 } else {
1325 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1326 ResourceMark rm(THREAD);
1327
1328 JavaThread* jt = THREAD;
1329
1330 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1331 ClassLoader::perf_app_classload_selftime(),
1332 ClassLoader::perf_app_classload_count(),
1333 jt->get_thread_stat()->perf_recursion_counts_addr(),
1334 jt->get_thread_stat()->perf_timers_addr(),
1335 PerfClassTraceTime::CLASS_LOAD);
1336
1337 // Translate to external class name format, i.e., convert '/' chars to '.'
1338 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1339
1340 JavaValue result(T_OBJECT);
1341
1342 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1343
1344 // Call public unsynchronized loadClass(String) directly for all class loaders.
1345 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1346 // acquire a class-name based lock rather than the class loader object lock.
1347 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1348 JavaCalls::call_virtual(&result,
1349 class_loader,
1350 spec_klass,
1351 vmSymbols::loadClass_name(),
1352 vmSymbols::string_class_signature(),
1353 string,
1354 CHECK_NULL);
1355
1356 assert(result.get_type() == T_OBJECT, "just checking");
1357 oop obj = result.get_oop();
1358
1359 // Primitive classes return null since forName() can not be
1360 // used to obtain any of the Class objects representing primitives or void
1361 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1362 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1363 // For user defined Java class loaders, check that the name returned is
1364 // the same as that requested. This check is done for the bootstrap
1365 // loader when parsing the class file.
1366 if (class_name == k->name()) {
1367 return k;
1368 }
1369 }
1370 // Class is not found or has the wrong name, return null
1371 return nullptr;
1372 }
1373 }
1374
1375 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1376 Handle class_loader,
1377 TRAPS) {
1378
1379 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1380
1381 // If everything was OK (no exceptions, no null return value), and
1382 // class_loader is NOT the defining loader, do a little more bookkeeping.
1383 if (loaded_class != nullptr &&
1384 loaded_class->class_loader() != class_loader()) {
1385
1386 ClassLoaderData* loader_data = class_loader_data(class_loader);
1387 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1388
1389 // Record dependency for non-parent delegation.
1390 // This recording keeps the defining class loader of the klass (loaded_class) found
1391 // from being unloaded while the initiating class loader is loaded
1392 // even if the reference to the defining class loader is dropped
1393 // before references to the initiating class loader.
1394 loader_data->record_dependency(loaded_class);
1395
1396 update_dictionary(THREAD, loaded_class, loader_data);
1397
1398 if (JvmtiExport::should_post_class_load()) {
1399 JvmtiExport::post_class_load(THREAD, loaded_class);
1400 }
1401 }
1402 return loaded_class;
1403 }
1404
1405 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1406 EventClassDefine event;
1407 if (event.should_commit()) {
1408 event.set_definedClass(k);
1409 event.set_definingClassLoader(def_cld);
1410 event.commit();
1411 }
1412 }
1413
1414 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1415
1416 ClassLoaderData* loader_data = k->class_loader_data();
1417 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1418
1419 // Bootstrap and other parallel classloaders don't acquire a lock,
1420 // they use placeholder token.
1421 // If a parallelCapable class loader calls define_instance_class instead of
1422 // find_or_define_instance_class to get here, we have a timing
1423 // hole with systemDictionary updates and check_constraints
1424 if (!is_parallelCapable(class_loader)) {
1425 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1426 get_loader_lock_or_null(class_loader)),
1427 "define called without lock");
1428 }
1429
1430 // Check class-loading constraints. Throw exception if violation is detected.
1431 // Grabs and releases SystemDictionary_lock
1432 // The check_constraints/find_class call and update_dictionary sequence
1433 // must be "atomic" for a specific class/classloader pair so we never
1434 // define two different instanceKlasses for that class/classloader pair.
1435 // Existing classloaders will call define_instance_class with the
1436 // classloader lock held
1437 // Parallel classloaders will call find_or_define_instance_class
1438 // which will require a token to perform the define class
1439 check_constraints(k, loader_data, true, CHECK);
1440
1441 // Register class just loaded with class loader (placed in ArrayList)
1442 // Note we do this before updating the dictionary, as this can
1443 // fail with an OutOfMemoryError (if it does, we will *not* put this
1444 // class in the dictionary and will not update the class hierarchy).
1445 // JVMTI FollowReferences needs to find the classes this way.
1446 if (k->class_loader() != nullptr) {
1447 methodHandle m(THREAD, Universe::loader_addClass_method());
1448 JavaValue result(T_VOID);
1449 JavaCallArguments args(class_loader);
1450 args.push_oop(Handle(THREAD, k->java_mirror()));
1451 JavaCalls::call(&result, m, &args, CHECK);
1452 }
1453
1454 // Add to class hierarchy, and do possible deoptimizations.
1455 k->add_to_hierarchy(THREAD);
1456
1457 // Add to systemDictionary - so other classes can see it.
1458 // Grabs and releases SystemDictionary_lock
1459 update_dictionary(THREAD, k, loader_data);
1460
1461 // notify jvmti
1462 if (JvmtiExport::should_post_class_load()) {
1463 JvmtiExport::post_class_load(THREAD, k);
1464 }
1465 post_class_define_event(k, loader_data);
1466 }
1467
1468 // Support parallel classloading
1469 // All parallel class loaders, including bootstrap classloader
1470 // lock a placeholder entry for this class/class_loader pair
1471 // to allow parallel defines of different classes for this class loader
1472 // With AllowParallelDefine flag==true, in case they do not synchronize around
1473 // FindLoadedClass/DefineClass, calls, we check for parallel
1474 // loading for them, wait if a defineClass is in progress
1475 // and return the initial requestor's results
1476 // This flag does not apply to the bootstrap classloader.
1477 // With AllowParallelDefine flag==false, call through to define_instance_class
1478 // which will throw LinkageError: duplicate class definition.
1479 // False is the requested default.
1480 // For better performance, the class loaders should synchronize
1481 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1482 // potentially waste time reading and parsing the bytestream.
1483 // Note: VM callers should ensure consistency of k/class_name,class_loader
1484 // Be careful when modifying this code: once you have run
1485 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1486 // you need to find_and_remove it before returning.
1487 // So be careful to not exit with a CHECK_ macro between these calls.
1488 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1489 InstanceKlass* k, TRAPS) {
1490
1491 Symbol* name_h = k->name();
1492 ClassLoaderData* loader_data = class_loader_data(class_loader);
1493 Dictionary* dictionary = loader_data->dictionary();
1494
1495 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1496 {
1497 MutexLocker mu(THREAD, SystemDictionary_lock);
1498 // First check if class already defined
1499 if (is_parallelDefine(class_loader)) {
1500 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1501 if (check != nullptr) {
1502 return check;
1503 }
1504 }
1505
1506 // Acquire define token for this class/classloader
1507 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1508 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1509 // Wait if another thread defining in parallel
1510 // All threads wait - even those that will throw duplicate class: otherwise
1511 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1512 // if other thread has not finished updating dictionary
1513 while (probe->definer() != nullptr) {
1514 SystemDictionary_lock->wait();
1515 }
1516 // Only special cases allow parallel defines and can use other thread's results
1517 // Other cases fall through, and may run into duplicate defines
1518 // caught by finding an entry in the SystemDictionary
1519 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1520 InstanceKlass* ik = probe->instance_klass();
1521 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1522 SystemDictionary_lock->notify_all();
1523 #ifdef ASSERT
1524 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1525 assert(check != nullptr, "definer missed recording success");
1526 #endif
1527 return ik;
1528 } else {
1529 // This thread will define the class (even if earlier thread tried and had an error)
1530 probe->set_definer(THREAD);
1531 }
1532 }
1533
1534 define_instance_class(k, class_loader, THREAD);
1535
1536 // definer must notify any waiting threads
1537 {
1538 MutexLocker mu(THREAD, SystemDictionary_lock);
1539 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1540 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1541 if (!HAS_PENDING_EXCEPTION) {
1542 probe->set_instance_klass(k);
1543 }
1544 probe->set_definer(nullptr);
1545 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1546 SystemDictionary_lock->notify_all();
1547 }
1548
1549 return HAS_PENDING_EXCEPTION ? nullptr : k;
1550 }
1551
1552 // If a class loader supports parallel classloading handle parallel define requests.
1553 // find_or_define_instance_class may return a different InstanceKlass
1554 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1555 InstanceKlass* k, TRAPS) {
1556 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1557 // Clean up original InstanceKlass if duplicate or error
1558 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1559 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1560 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1561 k->class_loader_data()->add_to_deallocate_list(k);
1562 } else if (HAS_PENDING_EXCEPTION) {
1563 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1564 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1565 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1566 k->class_loader_data()->add_to_deallocate_list(k);
1567 }
1568 return defined_k;
1569 }
1570
1571
1572 // ----------------------------------------------------------------------------
1573 // GC support
1574
1575 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1576 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1577
1578 bool unloading_occurred;
1579 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1580 {
1581 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1582 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1583 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1584 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1585 if (unloading_occurred) {
1586 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1587 JFR_ONLY(Jfr::on_unloading_classes();)
1588 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1589 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1590 ClassLoaderDataGraph::clean_module_and_package_info();
1591 LoaderConstraintTable::purge_loader_constraints();
1592 ResolutionErrorTable::purge_resolution_errors();
1593 }
1594 }
1595
1596 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1597
1598 if (unloading_occurred) {
1599 SymbolTable::trigger_cleanup();
1600
1601 if (java_lang_System::allow_security_manager()) {
1602 // Oops referenced by the protection domain cache table may get unreachable independently
1603 // of the class loader (eg. cached protection domain oops). So we need to
1604 // explicitly unlink them here.
1605 // All protection domain oops are linked to the caller class, so if nothing
1606 // unloads, this is not needed.
1607 ProtectionDomainCacheTable::trigger_cleanup();
1608 } else {
1609 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1610 }
1611
1612 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1613 InstanceKlass::clean_initialization_error_table();
1614 }
1615
1616 return unloading_occurred;
1617 }
1618
1619 void SystemDictionary::methods_do(void f(Method*)) {
1620 // Walk methods in loaded classes
1621
1622 {
1623 MutexLocker ml(ClassLoaderDataGraph_lock);
1624 ClassLoaderDataGraph::methods_do(f);
1625 }
1626
1627 auto doit = [&] (InvokeMethodKey key, Method* method) {
1628 if (method != nullptr) {
1629 f(method);
1630 }
1631 };
1632
1633 {
1634 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1635 _invoke_method_intrinsic_table->iterate_all(doit);
1636 }
1637
1638 }
1639
1640 // ----------------------------------------------------------------------------
1641 // Initialization
1642
1643 void SystemDictionary::initialize(TRAPS) {
1644 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1645 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1646 ResolutionErrorTable::initialize();
1647 LoaderConstraintTable::initialize();
1648 PlaceholderTable::initialize();
1649 ProtectionDomainCacheTable::initialize();
1650 #if INCLUDE_CDS
1651 SystemDictionaryShared::initialize();
1652 #endif
1653 // Resolve basic classes
1654 vmClasses::resolve_all(CHECK);
1655 // Resolve classes used by archived heap objects
1656 if (UseSharedSpaces) {
1657 HeapShared::resolve_classes(THREAD);
1658 }
1659 }
1660
1661 // Constraints on class loaders. The details of the algorithm can be
1662 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1663 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1664 // that the dictionary needs to maintain a set of constraints that
1665 // must be satisfied by all classes in the dictionary.
1666 // if defining is true, then LinkageError if already in dictionary
1667 // if initiating loader, then ok if InstanceKlass matches existing entry
1668
1669 void SystemDictionary::check_constraints(InstanceKlass* k,
1670 ClassLoaderData* loader_data,
1671 bool defining,
1672 TRAPS) {
1673 ResourceMark rm(THREAD);
1674 stringStream ss;
1675 bool throwException = false;
1676
1677 {
1678 Symbol* name = k->name();
1679
1680 MutexLocker mu(THREAD, SystemDictionary_lock);
1681
1682 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1683 if (check != nullptr) {
1684 // If different InstanceKlass - duplicate class definition,
1685 // else - ok, class loaded by a different thread in parallel.
1686 // We should only have found it if it was done loading and ok to use.
1687
1688 if ((defining == true) || (k != check)) {
1689 throwException = true;
1690 ss.print("loader %s", loader_data->loader_name_and_id());
1691 ss.print(" attempted duplicate %s definition for %s. (%s)",
1692 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1693 } else {
1694 return;
1695 }
1696 }
1697
1698 if (throwException == false) {
1699 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1700 throwException = true;
1701 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1702 ss.print(" wants to load %s %s.",
1703 k->external_kind(), k->external_name());
1704 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1705 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1706 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1707 existing_klass->external_kind(),
1708 existing_klass->class_loader_data()->loader_name_and_id(),
1709 existing_klass->class_in_module_of_loader(false, true));
1710 } else {
1711 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1712 }
1713 }
1714 }
1715 }
1716
1717 // Throw error now if needed (cannot throw while holding
1718 // SystemDictionary_lock because of rank ordering)
1719 if (throwException == true) {
1720 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1721 }
1722 }
1723
1724 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1725 // have been called.
1726 void SystemDictionary::update_dictionary(JavaThread* current,
1727 InstanceKlass* k,
1728 ClassLoaderData* loader_data) {
1729 MonitorLocker mu1(SystemDictionary_lock);
1730
1731 // Make a new dictionary entry.
1732 Symbol* name = k->name();
1733 Dictionary* dictionary = loader_data->dictionary();
1734 InstanceKlass* sd_check = dictionary->find_class(current, name);
1735 if (sd_check == nullptr) {
1736 dictionary->add_klass(current, name, k);
1737 }
1738 mu1.notify_all();
1739 }
1740
1741
1742 // Try to find a class name using the loader constraints. The
1743 // loader constraints might know about a class that isn't fully loaded
1744 // yet and these will be ignored.
1745 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1746 Thread* current, Symbol* class_name, Handle class_loader) {
1747
1748 // First see if it has been loaded directly.
1749 // Force the protection domain to be null. (This removes protection checks.)
1750 Handle no_protection_domain;
1751 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1752 no_protection_domain);
1753 if (klass != nullptr)
1754 return klass;
1755
1756 // Now look to see if it has been loaded elsewhere, and is subject to
1757 // a loader constraint that would require this loader to return the
1758 // klass that is already loaded.
1759 if (Signature::is_array(class_name)) {
1760 // For array classes, their Klass*s are not kept in the
1761 // constraint table. The element Klass*s are.
1762 SignatureStream ss(class_name, false);
1763 int ndims = ss.skip_array_prefix(); // skip all '['s
1764 BasicType t = ss.type();
1765 if (t != T_OBJECT) {
1766 klass = Universe::typeArrayKlassObj(t);
1767 } else {
1768 MutexLocker mu(current, SystemDictionary_lock);
1769 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1770 }
1771 // If element class already loaded, allocate array klass
1772 if (klass != nullptr) {
1773 klass = klass->array_klass_or_null(ndims);
1774 }
1775 } else {
1776 MutexLocker mu(current, SystemDictionary_lock);
1777 // Non-array classes are easy: simply check the constraint table.
1778 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1779 }
1780
1781 return klass;
1782 }
1783
1784 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1785 Klass* klass_being_linked,
1786 Handle class_loader1,
1787 Handle class_loader2) {
1788 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1789 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1790
1791 Symbol* constraint_name = nullptr;
1792
1793 if (!Signature::is_array(class_name)) {
1794 constraint_name = class_name;
1795 } else {
1796 // For array classes, their Klass*s are not kept in the
1797 // constraint table. The element classes are.
1798 SignatureStream ss(class_name, false);
1799 ss.skip_array_prefix(); // skip all '['s
1800 if (!ss.has_envelope()) {
1801 return true; // primitive types always pass
1802 }
1803 constraint_name = ss.as_symbol();
1804 // Increment refcount to keep constraint_name alive after
1805 // SignatureStream is destructed. It will be decremented below
1806 // before returning.
1807 constraint_name->increment_refcount();
1808 }
1809
1810 Dictionary* dictionary1 = loader_data1->dictionary();
1811 Dictionary* dictionary2 = loader_data2->dictionary();
1812
1813 JavaThread* current = JavaThread::current();
1814 {
1815 MutexLocker mu_s(SystemDictionary_lock);
1816 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1817 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1818 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1819 klass2, loader_data2);
1820 #if INCLUDE_CDS
1821 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1822 !klass_being_linked->is_shared()) {
1823 SystemDictionaryShared::record_linking_constraint(constraint_name,
1824 InstanceKlass::cast(klass_being_linked),
1825 class_loader1, class_loader2);
1826 }
1827 #endif // INCLUDE_CDS
1828 if (Signature::is_array(class_name)) {
1829 constraint_name->decrement_refcount();
1830 }
1831 return result;
1832 }
1833 }
1834
1835 // Add entry to resolution error table to record the error when the first
1836 // attempt to resolve a reference to a class has failed.
1837 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1838 Symbol* error, Symbol* message,
1839 Symbol* cause, Symbol* cause_msg) {
1840 {
1841 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1842 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1843 if (entry == nullptr) {
1844 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1845 }
1846 }
1847 }
1848
1849 // Delete a resolution error for RedefineClasses for a constant pool is going away
1850 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1851 ResolutionErrorTable::delete_entry(pool);
1852 }
1853
1854 // Lookup resolution error table. Returns error if found, otherwise null.
1855 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1856 Symbol** message, Symbol** cause, Symbol** cause_msg) {
1857
1858 {
1859 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1860 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1861 if (entry != nullptr) {
1862 *message = entry->message();
1863 *cause = entry->cause();
1864 *cause_msg = entry->cause_msg();
1865 return entry->error();
1866 } else {
1867 return nullptr;
1868 }
1869 }
1870 }
1871
1872 // Add an entry to resolution error table to record an error in resolving or
1873 // validating a nest host. This is used to construct informative error
1874 // messages when IllegalAccessError's occur. If an entry already exists it will
1875 // be updated with the nest host error message.
1876
1877 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1878 int which,
1879 const char* message) {
1880 {
1881 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1882 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1883 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1884 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1885 // still want to add the error message for the higher-level access checks to report. We should
1886 // only reach here under the same error condition, so we can ignore the potential race with setting
1887 // the message. If we see it is already set then we can ignore it.
1888 entry->set_nest_host_error(message);
1889 } else {
1890 ResolutionErrorTable::add_entry(pool, which, message);
1891 }
1892 }
1893 }
1894
1895 // Lookup any nest host error
1896 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1897 {
1898 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1899 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1900 if (entry != nullptr) {
1901 return entry->nest_host_error();
1902 } else {
1903 return nullptr;
1904 }
1905 }
1906 }
1907
1908 // Signature constraints ensure that callers and callees agree about
1909 // the meaning of type names in their signatures. This routine is the
1910 // intake for constraints. It collects them from several places:
1911 //
1912 // * LinkResolver::resolve_method (if check_access is true) requires
1913 // that the resolving class (the caller) and the defining class of
1914 // the resolved method (the callee) agree on each type in the
1915 // method's signature.
1916 //
1917 // * LinkResolver::resolve_interface_method performs exactly the same
1918 // checks.
1919 //
1920 // * LinkResolver::resolve_field requires that the constant pool
1921 // attempting to link to a field agree with the field's defining
1922 // class about the type of the field signature.
1923 //
1924 // * klassVtable::initialize_vtable requires that, when a class
1925 // overrides a vtable entry allocated by a superclass, that the
1926 // overriding method (i.e., the callee) agree with the superclass
1927 // on each type in the method's signature.
1928 //
1929 // * klassItable::initialize_itable requires that, when a class fills
1930 // in its itables, for each non-abstract method installed in an
1931 // itable, the method (i.e., the callee) agree with the interface
1932 // on each type in the method's signature.
1933 //
1934 // All those methods have a boolean (check_access, checkconstraints)
1935 // which turns off the checks. This is used from specialized contexts
1936 // such as bootstrapping, dumping, and debugging.
1937 //
1938 // No direct constraint is placed between the class and its
1939 // supertypes. Constraints are only placed along linked relations
1940 // between callers and callees. When a method overrides or implements
1941 // an abstract method in a supertype (superclass or interface), the
1942 // constraints are placed as if the supertype were the caller to the
1943 // overriding method. (This works well, since callers to the
1944 // supertype have already established agreement between themselves and
1945 // the supertype.) As a result of all this, a class can disagree with
1946 // its supertype about the meaning of a type name, as long as that
1947 // class neither calls a relevant method of the supertype, nor is
1948 // called (perhaps via an override) from the supertype.
1949 //
1950 //
1951 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1952 //
1953 // Make sure all class components (including arrays) in the given
1954 // signature will be resolved to the same class in both loaders.
1955 // Returns the name of the type that failed a loader constraint check, or
1956 // null if no constraint failed. No exception except OOME is thrown.
1957 // Arrays are not added to the loader constraint table, their elements are.
1958 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1959 Klass* klass_being_linked,
1960 Handle loader1, Handle loader2,
1961 bool is_method) {
1962 // Nothing to do if loaders are the same.
1963 if (loader1() == loader2()) {
1964 return nullptr;
1965 }
1966
1967 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1968 if (ss.is_reference()) {
1969 Symbol* sig = ss.as_symbol();
1970 // Note: In the future, if template-like types can take
1971 // arguments, we will want to recognize them and dig out class
1972 // names hiding inside the argument lists.
1973 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1974 return sig;
1975 }
1976 }
1977 }
1978 return nullptr;
1979 }
1980
1981 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1982 Symbol* signature,
1983 TRAPS) {
1984
1985 const int iid_as_int = vmIntrinsics::as_int(iid);
1986 assert(MethodHandles::is_signature_polymorphic(iid) &&
1987 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1988 iid != vmIntrinsics::_invokeGeneric,
1989 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1990
1991 InvokeMethodKey key(signature, iid_as_int);
1992 Method** met = nullptr;
1993
1994 // We only want one entry in the table for this (signature/id, method) pair but the code
1995 // to create the intrinsic method needs to be outside the lock.
1996 // The first thread claims the entry by adding the key and the other threads wait, until the
1997 // Method has been added as the value.
1998 {
1999 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2000 while (true) {
2001 bool created;
2002 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2003 assert(met != nullptr, "either created or found");
2004 if (*met != nullptr) {
2005 return *met;
2006 } else if (created) {
2007 // The current thread won the race and will try to create the full entry.
2008 break;
2009 } else {
2010 // Another thread beat us to it, so wait for them to complete
2011 // and return *met; or if they hit an error we get another try.
2012 ml.wait();
2013 // Note it is not safe to read *met here as that entry could have
2014 // been deleted, so we must loop and try put_if_absent again.
2015 }
2016 }
2017 }
2018
2019 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2020 bool throw_error = HAS_PENDING_EXCEPTION;
2021 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2022 // Generate a compiled form of the MH intrinsic
2023 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2024 AdapterHandlerLibrary::create_native_wrapper(m);
2025 // Check if have the compiled code.
2026 throw_error = (!m->has_compiled_code());
2027 }
2028
2029 {
2030 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2031 if (throw_error) {
2032 // Remove the entry and let another thread try, or get the same exception.
2033 bool removed = _invoke_method_intrinsic_table->remove(key);
2034 assert(removed, "must be the owner");
2035 ml.notify_all();
2036 } else {
2037 signature->make_permanent(); // The signature is never unloaded.
2038 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2039 m->code()->entry_point() == m->from_compiled_entry()),
2040 "MH intrinsic invariant");
2041 *met = m(); // insert the element
2042 ml.notify_all();
2043 return m();
2044 }
2045 }
2046
2047 // Throw VirtualMachineError or the pending exception in the JavaThread
2048 if (throw_error && !HAS_PENDING_EXCEPTION) {
2049 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2050 "Out of space in CodeCache for method handle intrinsic");
2051 }
2052 return nullptr;
2053 }
2054
2055 // Helper for unpacking the return value from linkMethod and linkCallSite.
2056 static Method* unpack_method_and_appendix(Handle mname,
2057 Klass* accessing_klass,
2058 objArrayHandle appendix_box,
2059 Handle* appendix_result,
2060 TRAPS) {
2061 if (mname.not_null()) {
2062 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2063 if (m != nullptr) {
2064 oop appendix = appendix_box->obj_at(0);
2065 LogTarget(Info, methodhandles) lt;
2066 if (lt.develop_is_enabled()) {
2067 ResourceMark rm(THREAD);
2068 LogStream ls(lt);
2069 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2070 m->print_on(&ls);
2071 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2072 ls.cr();
2073 }
2074
2075 (*appendix_result) = Handle(THREAD, appendix);
2076 // the target is stored in the cpCache and if a reference to this
2077 // MemberName is dropped we need a way to make sure the
2078 // class_loader containing this method is kept alive.
2079 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2080 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2081 this_key->record_dependency(m->method_holder());
2082 return mh();
2083 }
2084 }
2085 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2086 }
2087
2088 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2089 Symbol* name,
2090 Symbol* signature,
2091 Klass* accessing_klass,
2092 Handle* appendix_result,
2093 TRAPS) {
2094 guarantee(THREAD->can_call_java(), "");
2095 Handle method_type =
2096 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2097
2098 int ref_kind = JVM_REF_invokeVirtual;
2099 oop name_oop = StringTable::intern(name, CHECK_NULL);
2100 Handle name_str (THREAD, name_oop);
2101 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2102 assert(appendix_box->obj_at(0) == nullptr, "");
2103
2104 // This should not happen. JDK code should take care of that.
2105 if (accessing_klass == nullptr || method_type.is_null()) {
2106 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2107 }
2108
2109 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2110 JavaCallArguments args;
2111 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2112 args.push_int(ref_kind);
2113 args.push_oop(Handle(THREAD, klass->java_mirror()));
2114 args.push_oop(name_str);
2115 args.push_oop(method_type);
2116 args.push_oop(appendix_box);
2117 JavaValue result(T_OBJECT);
2118 JavaCalls::call_static(&result,
2119 vmClasses::MethodHandleNatives_klass(),
2120 vmSymbols::linkMethod_name(),
2121 vmSymbols::linkMethod_signature(),
2122 &args, CHECK_NULL);
2123 Handle mname(THREAD, result.get_oop());
2124 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2125 }
2126
2127 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2128 // We must ensure that all class loaders everywhere will reach this class, for any client.
2129 // This is a safe bet for public classes in java.lang, such as Object and String.
2130 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2131 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2132 static bool is_always_visible_class(oop mirror) {
2133 Klass* klass = java_lang_Class::as_Klass(mirror);
2134 if (klass->is_objArray_klass()) {
2135 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2136 }
2137 if (klass->is_typeArray_klass()) {
2138 return true; // primitive array
2139 }
2140 assert(klass->is_instance_klass(), "%s", klass->external_name());
2141 return klass->is_public() &&
2142 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2143 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2144 }
2145
2146 // Find or construct the Java mirror (java.lang.Class instance) for
2147 // the given field type signature, as interpreted relative to the
2148 // given class loader. Handles primitives, void, references, arrays,
2149 // and all other reflectable types, except method types.
2150 // N.B. Code in reflection should use this entry point.
2151 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2152 Klass* accessing_klass,
2153 Handle class_loader,
2154 Handle protection_domain,
2155 SignatureStream::FailureMode failure_mode,
2156 TRAPS) {
2157 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2158 "one or the other, or perhaps neither");
2159
2160 // What we have here must be a valid field descriptor,
2161 // and all valid field descriptors are supported.
2162 // Produce the same java.lang.Class that reflection reports.
2163 if (accessing_klass != nullptr) {
2164 class_loader = Handle(THREAD, accessing_klass->class_loader());
2165 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2166 }
2167 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2168 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2169 if (mirror_oop == nullptr) {
2170 return Handle(); // report failure this way
2171 }
2172 Handle mirror(THREAD, mirror_oop);
2173
2174 if (accessing_klass != nullptr) {
2175 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2176 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2177 if (sel_klass != nullptr) {
2178 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2179 }
2180 }
2181 return mirror;
2182 }
2183
2184
2185 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2186 // signature, as interpreted relative to the given class loader.
2187 // Because of class loader constraints, all method handle usage must be
2188 // consistent with this loader.
2189 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2190 Klass* accessing_klass,
2191 TRAPS) {
2192 Handle empty;
2193 OopHandle* o;
2194 {
2195 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2196 o = _invoke_method_type_table->get(signature);
2197 }
2198
2199 if (o != nullptr) {
2200 oop mt = o->resolve();
2201 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2202 return Handle(THREAD, mt);
2203 } else if (!THREAD->can_call_java()) {
2204 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2205 return Handle(); // do not attempt from within compiler, unless it was cached
2206 }
2207
2208 Handle class_loader, protection_domain;
2209 if (accessing_klass != nullptr) {
2210 class_loader = Handle(THREAD, accessing_klass->class_loader());
2211 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2212 }
2213 bool can_be_cached = true;
2214 int npts = ArgumentCount(signature).size();
2215 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2216 int arg = 0;
2217 Handle rt; // the return type from the signature
2218 ResourceMark rm(THREAD);
2219 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2220 oop mirror = nullptr;
2221 if (can_be_cached) {
2222 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2223 mirror = ss.as_java_mirror(Handle(), Handle(),
2224 SignatureStream::ReturnNull, CHECK_(empty));
2225 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2226 // Fall back to accessing_klass context.
2227 can_be_cached = false;
2228 }
2229 }
2230 if (!can_be_cached) {
2231 // Resolve, throwing a real error if it doesn't work.
2232 mirror = ss.as_java_mirror(class_loader, protection_domain,
2233 SignatureStream::NCDFError, CHECK_(empty));
2234 }
2235 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2236 if (ss.at_return_type())
2237 rt = Handle(THREAD, mirror);
2238 else
2239 pts->obj_at_put(arg++, mirror);
2240
2241 // Check accessibility.
2242 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2243 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2244 mirror = nullptr; // safety
2245 // Emulate ConstantPool::verify_constant_pool_resolve.
2246 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2247 }
2248 }
2249 assert(arg == npts, "");
2250
2251 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2252 JavaCallArguments args(Handle(THREAD, rt()));
2253 args.push_oop(pts);
2254 JavaValue result(T_OBJECT);
2255 JavaCalls::call_static(&result,
2256 vmClasses::MethodHandleNatives_klass(),
2257 vmSymbols::findMethodHandleType_name(),
2258 vmSymbols::findMethodHandleType_signature(),
2259 &args, CHECK_(empty));
2260 Handle method_type(THREAD, result.get_oop());
2261
2262 if (can_be_cached) {
2263 // We can cache this MethodType inside the JVM.
2264 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2265 bool created = false;
2266 assert(method_type != nullptr, "unexpected null");
2267 OopHandle* h = _invoke_method_type_table->get(signature);
2268 if (h == nullptr) {
2269 signature->make_permanent(); // The signature is never unloaded.
2270 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2271 bool created = _invoke_method_type_table->put(signature, elem);
2272 assert(created, "better be created");
2273 }
2274 }
2275 // report back to the caller with the MethodType
2276 return method_type;
2277 }
2278
2279 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2280 Klass* accessing_klass,
2281 TRAPS) {
2282 Handle empty;
2283 ResourceMark rm(THREAD);
2284 SignatureStream ss(signature, /*is_method=*/ false);
2285 if (!ss.is_done()) {
2286 Handle class_loader, protection_domain;
2287 if (accessing_klass != nullptr) {
2288 class_loader = Handle(THREAD, accessing_klass->class_loader());
2289 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2290 }
2291 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2292 ss.next();
2293 if (ss.is_done()) {
2294 return Handle(THREAD, mirror);
2295 }
2296 }
2297 return empty;
2298 }
2299
2300 // Ask Java code to find or construct a method handle constant.
2301 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2302 int ref_kind, //e.g., JVM_REF_invokeVirtual
2303 Klass* callee,
2304 Symbol* name,
2305 Symbol* signature,
2306 TRAPS) {
2307 Handle empty;
2308 if (caller == nullptr) {
2309 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2310 }
2311 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2312 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2313
2314 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2315 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2316 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2317 java_lang_invoke_MemberName::set_name (mname(), name_str());
2318 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2319 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2320
2321 if (ref_kind == JVM_REF_invokeVirtual &&
2322 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2323 // Skip resolution for public signature polymorphic methods such as
2324 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2325 // They require appendix argument which MemberName resolution doesn't handle.
2326 // There's special logic on JDK side to handle them
2327 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2328 } else {
2329 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2330 }
2331
2332 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2333 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2334
2335 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2336 JavaCallArguments args;
2337 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2338 args.push_int(ref_kind);
2339 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2340 args.push_oop(name_str);
2341 args.push_oop(type);
2342 JavaValue result(T_OBJECT);
2343 JavaCalls::call_static(&result,
2344 vmClasses::MethodHandleNatives_klass(),
2345 vmSymbols::linkMethodHandleConstant_name(),
2346 vmSymbols::linkMethodHandleConstant_signature(),
2347 &args, CHECK_(empty));
2348 return Handle(THREAD, result.get_oop());
2349 }
2350
2351 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2352 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2353 // with linkage results being stored back into the bootstrap specifier.
2354 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2355 // Resolve the bootstrap specifier, its name, type, and static arguments
2356 bootstrap_specifier.resolve_bsm(CHECK);
2357
2358 // This should not happen. JDK code should take care of that.
2359 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2360 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2361 }
2362
2363 bool is_indy = bootstrap_specifier.is_method_call();
2364 objArrayHandle appendix_box;
2365 if (is_indy) {
2366 // Some method calls may require an appendix argument. Arrange to receive it.
2367 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2368 assert(appendix_box->obj_at(0) == nullptr, "");
2369 }
2370
2371 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2372 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2373 JavaCallArguments args;
2374 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2375 args.push_oop(bootstrap_specifier.bsm());
2376 args.push_oop(bootstrap_specifier.name_arg());
2377 args.push_oop(bootstrap_specifier.type_arg());
2378 args.push_oop(bootstrap_specifier.arg_values());
2379 if (is_indy) {
2380 args.push_oop(appendix_box);
2381 }
2382 JavaValue result(T_OBJECT);
2383 JavaCalls::call_static(&result,
2384 vmClasses::MethodHandleNatives_klass(),
2385 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2386 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2387 &args, CHECK);
2388
2389 Handle value(THREAD, result.get_oop());
2390 if (is_indy) {
2391 Handle appendix;
2392 Method* method = unpack_method_and_appendix(value,
2393 bootstrap_specifier.caller(),
2394 appendix_box,
2395 &appendix, CHECK);
2396 methodHandle mh(THREAD, method);
2397 bootstrap_specifier.set_resolved_method(mh, appendix);
2398 } else {
2399 bootstrap_specifier.set_resolved_value(value);
2400 }
2401
2402 // sanity check
2403 assert(bootstrap_specifier.is_resolved() ||
2404 (bootstrap_specifier.is_method_call() &&
2405 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2406 }
2407
2408
2409 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2410 assert(m != nullptr, "Unexpected nullptr Method*");
2411 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2412 }
2413
2414 // ----------------------------------------------------------------------------
2415
2416 void SystemDictionary::print_on(outputStream *st) {
2417 CDS_ONLY(SystemDictionaryShared::print_on(st));
2418 GCMutexLocker mu(SystemDictionary_lock);
2419
2420 ClassLoaderDataGraph::print_dictionary(st);
2421
2422 // Placeholders
2423 PlaceholderTable::print_on(st);
2424 st->cr();
2425
2426 // loader constraints - print under SD_lock
2427 LoaderConstraintTable::print_on(st);
2428 st->cr();
2429
2430 ProtectionDomainCacheTable::print_on(st);
2431 st->cr();
2432 }
2433
2434 void SystemDictionary::print() { print_on(tty); }
2435
2436 void SystemDictionary::verify() {
2437
2438 GCMutexLocker mu(SystemDictionary_lock);
2439
2440 // Verify dictionary
2441 ClassLoaderDataGraph::verify_dictionary();
2442
2443 // Verify constraint table
2444 LoaderConstraintTable::verify();
2445
2446 // Verify protection domain table
2447 ProtectionDomainCacheTable::verify();
2448 }
2449
2450 void SystemDictionary::dump(outputStream *st, bool verbose) {
2451 assert_locked_or_safepoint(SystemDictionary_lock);
2452 if (verbose) {
2453 print_on(st);
2454 } else {
2455 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2456 ClassLoaderDataGraph::print_table_statistics(st);
2457 LoaderConstraintTable::print_table_statistics(st);
2458 ProtectionDomainCacheTable::print_table_statistics(st);
2459 }
2460 }
2461
2462 // Utility for dumping dictionaries.
2463 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2464 DCmdWithParser(output, heap),
2465 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2466 "BOOLEAN", false, "false") {
2467 _dcmdparser.add_dcmd_option(&_verbose);
2468 }
2469
2470 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2471 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2472 _verbose.value());
2473 VMThread::execute(&dumper);
2474 }