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/classPreloader.hpp"
28 #include "cds/heapShared.hpp"
29 #include "classfile/classFileParser.hpp"
30 #include "classfile/classFileStream.hpp"
31 #include "classfile/classLoader.hpp"
32 #include "classfile/classLoaderData.inline.hpp"
33 #include "classfile/classLoaderDataGraph.inline.hpp"
34 #include "classfile/classLoaderExt.hpp"
35 #include "classfile/classLoadInfo.hpp"
36 #include "classfile/dictionary.hpp"
37 #include "classfile/javaClasses.inline.hpp"
38 #include "classfile/klassFactory.hpp"
39 #include "classfile/loaderConstraints.hpp"
40 #include "classfile/modules.hpp"
41 #include "classfile/packageEntry.hpp"
42 #include "classfile/placeholders.hpp"
43 #include "classfile/protectionDomainCache.hpp"
44 #include "classfile/resolutionErrors.hpp"
45 #include "classfile/stringTable.hpp"
46 #include "classfile/symbolTable.hpp"
47 #include "classfile/systemDictionary.hpp"
48 #include "classfile/vmClasses.hpp"
49 #include "classfile/vmSymbols.hpp"
50 #include "gc/shared/gcTraceTime.inline.hpp"
51 #include "interpreter/bootstrapInfo.hpp"
52 #include "jfr/jfrEvents.hpp"
53 #include "jvm.h"
54 #include "logging/log.hpp"
55 #include "logging/logStream.hpp"
56 #include "memory/metaspaceClosure.hpp"
57 #include "memory/oopFactory.hpp"
58 #include "memory/resourceArea.hpp"
59 #include "memory/universe.hpp"
60 #include "oops/access.inline.hpp"
61 #include "oops/instanceKlass.hpp"
62 #include "oops/klass.inline.hpp"
63 #include "oops/method.inline.hpp"
64 #include "oops/objArrayKlass.hpp"
65 #include "oops/objArrayOop.inline.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "oops/oop.hpp"
68 #include "oops/oopHandle.hpp"
69 #include "oops/oopHandle.inline.hpp"
70 #include "oops/symbol.hpp"
71 #include "oops/typeArrayKlass.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/sharedRuntime.hpp"
81 #include "runtime/signature.hpp"
82 #include "runtime/synchronizer.hpp"
83 #include "services/classLoadingService.hpp"
84 #include "services/diagnosticCommand.hpp"
85 #include "services/finalizerService.hpp"
86 #include "services/threadService.hpp"
87 #include "utilities/growableArray.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_platform_loader.is_empty()) {
141 oop platform_loader = get_platform_class_loader_impl(CHECK);
142 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
143 ClassPreloader::runtime_preload(THREAD, Handle(THREAD, java_platform_loader()));
144 } else {
145 // It must have been restored from the archived module graph
146 assert(UseSharedSpaces, "must be");
147 assert(CDSConfig::is_using_full_module_graph(), "must be");
148 DEBUG_ONLY(
149 oop platform_loader = get_platform_class_loader_impl(CHECK);
150 assert(_java_platform_loader.resolve() == platform_loader, "must be");
151 )
152 }
153
154 if (_java_system_loader.is_empty()) {
155 oop system_loader = get_system_class_loader_impl(CHECK);
156 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
157 ClassPreloader::runtime_preload(THREAD, Handle(THREAD, java_system_loader()));
158 } else {
159 // It must have been restored from the archived module graph
160 assert(UseSharedSpaces, "must be");
161 assert(CDSConfig::is_using_full_module_graph(), "must be");
162 DEBUG_ONLY(
163 oop system_loader = get_system_class_loader_impl(CHECK);
164 assert(_java_system_loader.resolve() == system_loader, "must be");
165 )
166 }
167 }
168
169 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
170 JavaValue result(T_OBJECT);
171 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
172 JavaCalls::call_static(&result,
173 class_loader_klass,
174 vmSymbols::getSystemClassLoader_name(),
175 vmSymbols::void_classloader_signature(),
176 CHECK_NULL);
177 return result.get_oop();
178 }
179
180 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
181 JavaValue result(T_OBJECT);
182 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
183 JavaCalls::call_static(&result,
184 class_loader_klass,
185 vmSymbols::getPlatformClassLoader_name(),
186 vmSymbols::void_classloader_signature(),
187 CHECK_NULL);
188 return result.get_oop();
189 }
190
191 // Helper function
192 inline ClassLoaderData* class_loader_data(Handle class_loader) {
193 return ClassLoaderData::class_loader_data(class_loader());
194 }
195
196 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
197 if (create_mirror_cld) {
198 // Add a new class loader data to the graph.
199 return ClassLoaderDataGraph::add(class_loader, true);
200 } else {
201 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
202 ClassLoaderDataGraph::find_or_create(class_loader);
203 }
204 }
205
206 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
207 assert(_java_system_loader.is_empty(), "already set!");
208 _java_system_loader = cld->class_loader_handle();
209
210 }
211
212 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
213 assert(_java_platform_loader.is_empty(), "already set!");
214 _java_platform_loader = cld->class_loader_handle();
215 }
216
217 // ----------------------------------------------------------------------------
218 // Parallel class loading check
219
220 static bool is_parallelCapable(Handle class_loader) {
221 if (class_loader.is_null()) return true;
222 return java_lang_ClassLoader::parallelCapable(class_loader());
223 }
224 // ----------------------------------------------------------------------------
225 // ParallelDefineClass flag does not apply to bootclass loader
226 static bool is_parallelDefine(Handle class_loader) {
227 if (class_loader.is_null()) return false;
228 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
229 return true;
230 }
231 return false;
232 }
233
234 // Returns true if the passed class loader is the builtin application class loader
235 // or a custom system class loader. A customer system class loader can be
236 // specified via -Djava.system.class.loader.
237 bool SystemDictionary::is_system_class_loader(oop class_loader) {
238 if (class_loader == nullptr) {
239 return false;
240 }
241 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
242 class_loader == _java_system_loader.peek());
243 }
244
245 // Returns true if the passed class loader is the platform class loader.
246 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
247 if (class_loader == nullptr) {
248 return false;
249 }
250 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
251 }
252
253 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
254 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
255 if (is_parallelCapable(class_loader)) {
256 return Handle();
257 } else {
258 return class_loader;
259 }
260 }
261
262 // ----------------------------------------------------------------------------
263 // Resolving of classes
264
265 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
266 if (name == nullptr) {
267 THROW_MSG_0(exception, "No class name given");
268 }
269 if ((int)strlen(name) > Symbol::max_length()) {
270 // It's impossible to create this class; the name cannot fit
271 // into the constant pool.
272 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
273 "Class name exceeds maximum length of %d: %s",
274 Symbol::max_length(),
275 name);
276 return nullptr;
277 }
278 // Callers should ensure that the name is never an illegal UTF8 string.
279 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
280 "Class name is not a valid utf8 string.");
281
282 // Make a new symbol for the class name.
283 return SymbolTable::new_symbol(name);
284 }
285
286 #ifdef ASSERT
287 // Used to verify that class loading succeeded in adding k to the dictionary.
288 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
289 MutexLocker mu(SystemDictionary_lock);
290 ClassLoaderData* loader_data = k->class_loader_data();
291 Dictionary* dictionary = loader_data->dictionary();
292 assert(class_name == k->name(), "Must be the same");
293 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
294 assert(kk == k, "should be present in dictionary");
295 }
296 #endif
297
298 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
299 if (HAS_PENDING_EXCEPTION) {
300 // If we have a pending exception we forward it to the caller, unless throw_error is true,
301 // in which case we have to check whether the pending exception is a ClassNotFoundException,
302 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
303 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
304 ResourceMark rm(THREAD);
305 Handle e(THREAD, PENDING_EXCEPTION);
306 CLEAR_PENDING_EXCEPTION;
307 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
308 } else {
309 return; // the caller will throw the incoming exception
310 }
311 }
312 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
313 // error or exception depending on the value of throw_error.
314 ResourceMark rm(THREAD);
315 if (throw_error) {
316 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
317 } else {
318 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
319 }
320 }
321
322 // Forwards to resolve_or_null
323
324 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
325 bool throw_error, TRAPS) {
326 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
327 // Check for pending exception or null klass, and throw exception
328 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
329 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
330 }
331 return klass;
332 }
333
334 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
335
336 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
337 if (Signature::is_array(class_name)) {
338 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
339 } else {
340 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
341 if (Signature::has_envelope(class_name)) {
342 ResourceMark rm(THREAD);
343 // Ignore wrapping L and ;.
344 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
345 class_name->utf8_length() - 2);
346 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
347 } else {
348 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
349 }
350 }
351 }
352
353 // Forwards to resolve_instance_class_or_null
354
355 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
356 Handle class_loader,
357 Handle protection_domain,
358 TRAPS) {
359 assert(Signature::is_array(class_name), "must be array");
360 ResourceMark rm(THREAD);
361 SignatureStream ss(class_name, false);
362 int ndims = ss.skip_array_prefix(); // skip all '['s
363 Klass* k = nullptr;
364 BasicType t = ss.type();
365 if (ss.has_envelope()) {
366 Symbol* obj_class = ss.as_symbol();
367 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
368 class_loader,
369 protection_domain,
370 CHECK_NULL);
371 if (k != nullptr) {
372 k = k->array_klass(ndims, CHECK_NULL);
373 }
374 } else {
375 k = Universe::typeArrayKlass(t);
376 k = k->array_klass(ndims, CHECK_NULL);
377 }
378 return k;
379 }
380
381 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
382 LogTarget(Debug, class, load, placeholders) lt;
383 if (lt.is_enabled()) {
384 ResourceMark rm;
385 LogStream ls(lt);
386 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
387 probe->print_on(&ls);
388 ls.cr();
389 }
390 }
391
392 // Must be called for any superclass or superinterface resolution
393 // during class definition to allow class circularity checking
394 // superinterface callers:
395 // parse_interfaces - from defineClass
396 // superclass callers:
397 // ClassFileParser - from defineClass
398 // load_shared_class - while loading a class from shared archive
399 // resolve_instance_class_or_null:
400 // via: handle_parallel_super_load
401 // when resolving a class that has an existing placeholder with
402 // a saved superclass [i.e. a defineClass is currently in progress]
403 // If another thread is trying to resolve the class, it must do
404 // superclass checks on its own thread to catch class circularity and
405 // to avoid deadlock.
406 //
407 // resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
408 // resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
409 // placeholder for the same thread, class, classloader is found.
410 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
411 //
412 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
413 Symbol* super_name,
414 Handle class_loader,
415 Handle protection_domain,
416 bool is_superclass,
417 TRAPS) {
418
419 assert(super_name != nullptr, "null superclass for resolving");
420 assert(!Signature::is_array(super_name), "invalid superclass name");
421 #if INCLUDE_CDS
422 if (CDSConfig::is_dumping_static_archive()) {
423 // Special processing for handling UNREGISTERED shared classes.
424 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
425 super_name, is_superclass);
426 if (k) {
427 return k;
428 }
429 }
430 #endif // INCLUDE_CDS
431
432 // If klass is already loaded, just return the superclass or superinterface.
433 // Make sure there's a placeholder for the class_name before resolving.
434 // This is used as a claim that this thread is currently loading superclass/classloader
435 // and for ClassCircularity checks.
436
437 ClassLoaderData* loader_data = class_loader_data(class_loader);
438 Dictionary* dictionary = loader_data->dictionary();
439
440 // can't throw error holding a lock
441 bool throw_circularity_error = false;
442 {
443 MutexLocker mu(THREAD, SystemDictionary_lock);
444 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
445 InstanceKlass* quicksuperk;
446 // To support parallel loading: if class is done loading, just return the superclass
447 // if the super_name matches class->super()->name() and if the class loaders match.
448 // Otherwise, a LinkageError will be thrown later.
449 if (klassk != nullptr && is_superclass &&
450 ((quicksuperk = klassk->java_super()) != nullptr) &&
451 ((quicksuperk->name() == super_name) &&
452 (quicksuperk->class_loader() == class_loader()))) {
453 return quicksuperk;
454 } else {
455 // Must check ClassCircularity before checking if superclass is already loaded.
456 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
457 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
458 log_circularity_error(class_name, probe);
459 throw_circularity_error = true;
460 }
461 }
462
463 if (!throw_circularity_error) {
464 // Be careful not to exit resolve_super without removing this placeholder.
465 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
466 loader_data,
467 PlaceholderTable::LOAD_SUPER,
468 super_name, THREAD);
469 }
470 }
471
472 if (throw_circularity_error) {
473 ResourceMark rm(THREAD);
474 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
475 }
476
477 // Resolve the superclass or superinterface, check results on return
478 InstanceKlass* superk =
479 SystemDictionary::resolve_instance_class_or_null(super_name,
480 class_loader,
481 protection_domain,
482 THREAD);
483
484 // Clean up placeholder entry.
485 {
486 MutexLocker mu(THREAD, SystemDictionary_lock);
487 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
488 SystemDictionary_lock->notify_all();
489 }
490
491 // Check for pending exception or null superk, and throw exception
492 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
493 handle_resolution_exception(super_name, true, CHECK_NULL);
494 }
495
496 return superk;
497 }
498
499 // If the class in is in the placeholder table, class loading is in progress.
500 // For cases where the application changes threads to load classes, it
501 // is critical to ClassCircularity detection that we try loading
502 // the superclass on the new thread internally, so we do parallel
503 // superclass loading here. This avoids deadlock for ClassCircularity
504 // detection for parallelCapable class loaders that lock on a per-class lock.
505 static void handle_parallel_super_load(Symbol* name,
506 Symbol* superclassname,
507 Handle class_loader,
508 Handle protection_domain, TRAPS) {
509
510 // superk is not used; resolve_super_or_fail is called for circularity check only.
511 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
512 superclassname,
513 class_loader,
514 protection_domain,
515 true,
516 CHECK);
517 }
518
519 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
520 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
521 static bool needs_load_placeholder(Handle class_loader) {
522 return class_loader.is_null() || !is_parallelCapable(class_loader);
523 }
524
525 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
526 static InstanceKlass* handle_parallel_loading(JavaThread* current,
527 Symbol* name,
528 ClassLoaderData* loader_data,
529 bool must_wait_for_class_loading,
530 bool* throw_circularity_error) {
531 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
532 if (oldprobe != nullptr) {
533 // -Xcomp calls load_signature_classes which might result in loading
534 // a class that's already in the process of loading, so we detect CCE here also.
535 // Only need check_seen_thread once, not on each loop
536 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
537 log_circularity_error(name, oldprobe);
538 *throw_circularity_error = true;
539 return nullptr;
540 } else if (must_wait_for_class_loading) {
541 // Wait until the first thread has finished loading this class. Also wait until all the
542 // threads trying to load its superclass have removed their placeholders.
543 while (oldprobe != nullptr &&
544 (oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {
545
546 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
547 // for the bootclass loader.
548 SystemDictionary_lock->wait();
549
550 // Check if classloading completed while we were waiting
551 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
552 if (check != nullptr) {
553 // Klass is already loaded, so just return it
554 return check;
555 }
556 // check if other thread failed to load and cleaned up
557 oldprobe = PlaceholderTable::get_entry(name, loader_data);
558 }
559 }
560 }
561 return nullptr;
562 }
563
564 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
565 assert(event != nullptr, "invariant");
566 assert(k != nullptr, "invariant");
567 event->set_loadedClass(k);
568 event->set_definingClassLoader(k->class_loader_data());
569 event->set_initiatingClassLoader(init_cld);
570 event->commit();
571 }
572
573 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
574 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
575 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
576 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
577 // This can return null, an exception or an InstanceKlass.
578 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
579 Handle class_loader,
580 Handle protection_domain,
581 TRAPS) {
582 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
583 assert(name != nullptr && !Signature::is_array(name) &&
584 !Signature::has_envelope(name), "invalid class name");
585
586 EventClassLoad class_load_start_event;
587
588 HandleMark hm(THREAD);
589
590 // Fix for 4474172; see evaluation for more details
591 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
592 ClassLoaderData* loader_data = register_loader(class_loader);
593 Dictionary* dictionary = loader_data->dictionary();
594
595 // Do lookup to see if class already exists and the protection domain
596 // has the right access.
597 // This call uses find which checks protection domain already matches
598 // All subsequent calls use find_class, and set loaded_class so that
599 // before we return a result, we call out to java to check for valid protection domain.
600 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
601 if (probe != nullptr) return probe;
602
603 // Non-bootstrap class loaders will call out to class loader and
604 // define via jvm/jni_DefineClass which will acquire the
605 // class loader object lock to protect against multiple threads
606 // defining the class in parallel by accident.
607 // This lock must be acquired here so the waiter will find
608 // any successful result in the SystemDictionary and not attempt
609 // the define.
610 // ParallelCapable class loaders and the bootstrap classloader
611 // do not acquire lock here.
612 Handle lockObject = get_loader_lock_or_null(class_loader);
613 ObjectLocker ol(lockObject, THREAD);
614
615 bool super_load_in_progress = false;
616 InstanceKlass* loaded_class = nullptr;
617 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
618
619 guarantee(THREAD->can_call_java(),
620 "can not load classes with compiler thread: class=%s, classloader=%s",
621 name->as_C_string(),
622 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
623
624 // Check again (after locking) if the class already exists in SystemDictionary
625 {
626 MutexLocker mu(THREAD, SystemDictionary_lock);
627 InstanceKlass* check = dictionary->find_class(THREAD, name);
628 if (check != nullptr) {
629 // InstanceKlass is already loaded, but we still need to check protection domain below.
630 loaded_class = check;
631 } else {
632 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
633 if (placeholder != nullptr && placeholder->super_load_in_progress()) {
634 super_load_in_progress = true;
635 superclassname = placeholder->supername();
636 assert(superclassname != nullptr, "superclass has to have a name");
637 }
638 }
639 }
640
641 // If the class is in the placeholder table with super_class set,
642 // handle superclass loading in progress.
643 if (super_load_in_progress) {
644 handle_parallel_super_load(name, superclassname,
645 class_loader,
646 protection_domain,
647 CHECK_NULL);
648 }
649
650 bool throw_circularity_error = false;
651 if (loaded_class == nullptr) {
652 bool load_placeholder_added = false;
653
654 // Add placeholder entry to record loading instance class
655 // case 1. Bootstrap classloader
656 // This classloader supports parallelism at the classloader level
657 // but only allows a single thread to load a class/classloader pair.
658 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
659 // case 2. parallelCapable user level classloaders
660 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
661 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
662 // case 3. traditional classloaders that rely on the classloader object lock
663 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
664 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
665 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
666 {
667 MutexLocker mu(THREAD, SystemDictionary_lock);
668 if (needs_load_placeholder(class_loader)) {
669 loaded_class = handle_parallel_loading(THREAD,
670 name,
671 loader_data,
672 class_loader.is_null(),
673 &throw_circularity_error);
674 }
675
676 // Recheck if the class has been loaded for all class loader cases and
677 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
678 if (!throw_circularity_error && loaded_class == nullptr) {
679 InstanceKlass* check = dictionary->find_class(THREAD, name);
680 if (check != nullptr) {
681 loaded_class = check;
682 } else if (needs_load_placeholder(class_loader)) {
683 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
684 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
685 PlaceholderTable::LOAD_INSTANCE,
686 nullptr,
687 THREAD);
688 load_placeholder_added = true;
689 }
690 }
691 }
692
693 // Must throw error outside of owning lock
694 if (throw_circularity_error) {
695 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
696 ResourceMark rm(THREAD);
697 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
698 }
699
700 // Be careful when modifying this code: once you have run
701 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
702 // you need to find_and_remove it before returning.
703 // So be careful to not exit with a CHECK_ macro between these calls.
704
705 if (loaded_class == nullptr) {
706 // Do actual loading
707 loaded_class = load_instance_class(name, class_loader, THREAD);
708 }
709
710 if (load_placeholder_added) {
711 // clean up placeholder entries for LOAD_INSTANCE success or error
712 // This brackets the SystemDictionary updates for both defining
713 // and initiating loaders
714 MutexLocker mu(THREAD, SystemDictionary_lock);
715 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
716 SystemDictionary_lock->notify_all();
717 }
718 }
719
720 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
721 return nullptr;
722 }
723
724 if (class_load_start_event.should_commit()) {
725 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
726 }
727
728 // Make sure we have the right class in the dictionary
729 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
730
731 if (protection_domain() != nullptr) {
732 // A SecurityManager (if installed) may prevent this protection_domain from accessing loaded_class
733 // by throwing a SecurityException.
734 dictionary->check_package_access(loaded_class, class_loader, protection_domain, CHECK_NULL);
735 }
736
737 return loaded_class;
738 }
739
740
741 // This routine does not lock the system dictionary.
742 //
743 // Since readers don't hold a lock, we must make sure that system
744 // dictionary entries are added to in a safe way (all links must
745 // be updated in an MT-safe manner). All entries are removed during class
746 // unloading, when this class loader is no longer referenced.
747 //
748 // Callers should be aware that an entry could be added just after
749 // Dictionary is read here, so the caller will not see
750 // the new entry.
751
752 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
753 Symbol* class_name,
754 Handle class_loader,
755 Handle protection_domain) {
756
757 // The result of this call should be consistent with the result
758 // of the call to resolve_instance_class_or_null().
759 // See evaluation 6790209 and 4474172 for more details.
760 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
761 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
762
763 if (loader_data == nullptr) {
764 // If the ClassLoaderData has not been setup,
765 // then the class loader has no entries in the dictionary.
766 return nullptr;
767 }
768
769 Dictionary* dictionary = loader_data->dictionary();
770 return dictionary->find(current, class_name, protection_domain);
771 }
772
773 // Look for a loaded instance or array klass by name. Do not do any loading.
774 // return null in case of error.
775 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
776 Symbol* class_name,
777 Handle class_loader,
778 Handle protection_domain) {
779 Klass* k = nullptr;
780 assert(class_name != nullptr, "class name must be non nullptr");
781
782 if (Signature::is_array(class_name)) {
783 // The name refers to an array. Parse the name.
784 // dimension and object_key in FieldArrayInfo are assigned as a
785 // side-effect of this call
786 SignatureStream ss(class_name, false);
787 int ndims = ss.skip_array_prefix(); // skip all '['s
788 BasicType t = ss.type();
789 if (t != T_OBJECT) {
790 k = Universe::typeArrayKlass(t);
791 } else {
792 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
793 }
794 if (k != nullptr) {
795 k = k->array_klass_or_null(ndims);
796 }
797 } else {
798 k = find_instance_klass(current, class_name, class_loader, protection_domain);
799 }
800 return k;
801 }
802
803 // Note: this method is much like resolve_class_from_stream, but
804 // does not publish the classes in the SystemDictionary.
805 // Handles Lookup.defineClass hidden.
806 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
807 ClassFileStream* st,
808 Symbol* class_name,
809 Handle class_loader,
810 const ClassLoadInfo& cl_info,
811 TRAPS) {
812
813 EventClassLoad class_load_start_event;
814 ClassLoaderData* loader_data;
815
816 // - for hidden classes that are not strong: create a new CLD that has a class holder and
817 // whose loader is the Lookup class's loader.
818 // - for hidden class: add the class to the Lookup class's loader's CLD.
819 assert (cl_info.is_hidden(), "only used for hidden classes");
820 bool create_mirror_cld = !cl_info.is_strong_hidden();
821 loader_data = register_loader(class_loader, create_mirror_cld);
822
823 assert(st != nullptr, "invariant");
824 assert(st->need_verify(), "invariant");
825
826 // Parse stream and create a klass.
827 InstanceKlass* k = KlassFactory::create_from_stream(st,
828 class_name,
829 loader_data,
830 cl_info,
831 CHECK_NULL);
832 assert(k != nullptr, "no klass created");
833
834 // Hidden classes that are not strong must update ClassLoaderData holder
835 // so that they can be unloaded when the mirror is no longer referenced.
836 if (!cl_info.is_strong_hidden()) {
837 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
838 }
839
840 // Add to class hierarchy, and do possible deoptimizations.
841 k->add_to_hierarchy(THREAD);
842 // But, do not add to dictionary.
843
844 k->link_class(CHECK_NULL);
845
846 // notify jvmti
847 if (JvmtiExport::should_post_class_load()) {
848 JvmtiExport::post_class_load(THREAD, k);
849 }
850 if (class_load_start_event.should_commit()) {
851 post_class_load_event(&class_load_start_event, k, loader_data);
852 }
853
854 return k;
855 }
856
857 // Add a klass to the system from a stream (called by jni_DefineClass and
858 // JVM_DefineClass).
859 // Note: class_name can be null. In that case we do not know the name of
860 // the class until we have parsed the stream.
861 // This function either returns an InstanceKlass or throws an exception. It does
862 // not return null without a pending exception.
863 InstanceKlass* SystemDictionary::resolve_class_from_stream(
864 ClassFileStream* st,
865 Symbol* class_name,
866 Handle class_loader,
867 const ClassLoadInfo& cl_info,
868 TRAPS) {
869
870 HandleMark hm(THREAD);
871
872 ClassLoaderData* loader_data = register_loader(class_loader);
873
874 // Classloaders that support parallelism, e.g. bootstrap classloader,
875 // do not acquire lock here
876 Handle lockObject = get_loader_lock_or_null(class_loader);
877 ObjectLocker ol(lockObject, THREAD);
878
879 // Parse the stream and create a klass.
880 // Note that we do this even though this klass might
881 // already be present in the SystemDictionary, otherwise we would not
882 // throw potential ClassFormatErrors.
883 InstanceKlass* k = nullptr;
884
885 #if INCLUDE_CDS
886 if (!CDSConfig::is_dumping_static_archive()) {
887 k = SystemDictionaryShared::lookup_from_stream(class_name,
888 class_loader,
889 cl_info.protection_domain(),
890 st,
891 CHECK_NULL);
892 }
893 #endif
894
895 if (k == nullptr) {
896 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
897 }
898
899 assert(k != nullptr, "no klass created");
900 Symbol* h_name = k->name();
901 assert(class_name == nullptr || class_name == h_name, "name mismatch");
902
903 // Add class just loaded
904 // If a class loader supports parallel classloading, handle parallel define requests.
905 // find_or_define_instance_class may return a different InstanceKlass,
906 // in which case the old k would be deallocated
907 if (is_parallelCapable(class_loader)) {
908 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
909 } else {
910 define_instance_class(k, class_loader, THREAD);
911
912 // If defining the class throws an exception register 'k' for cleanup.
913 if (HAS_PENDING_EXCEPTION) {
914 assert(k != nullptr, "Must have an instance klass here!");
915 loader_data->add_to_deallocate_list(k);
916 return nullptr;
917 }
918 }
919
920 // Make sure we have an entry in the SystemDictionary on success
921 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
922
923 return k;
924 }
925
926 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
927 Symbol* class_name,
928 Handle class_loader,
929 const ClassLoadInfo& cl_info,
930 TRAPS) {
931 if (cl_info.is_hidden()) {
932 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
933 } else {
934 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
935 }
936 }
937
938
939 #if INCLUDE_CDS
940 // Check if a shared class can be loaded by the specific classloader.
941 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
942 InstanceKlass* ik,
943 PackageEntry* pkg_entry,
944 Handle class_loader) {
945 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
946 "Cannot use sharing if java.base is patched");
947
948 // (1) Check if we are loading into the same loader as in dump time.
949
950 if (ik->is_shared_boot_class()) {
951 if (class_loader() != nullptr) {
952 return false;
953 }
954 } else if (ik->is_shared_platform_class()) {
955 if (class_loader() != java_platform_loader()) {
956 return false;
957 }
958 } else if (ik->is_shared_app_class()) {
959 if (class_loader() != java_system_loader()) {
960 return false;
961 }
962 } else {
963 // ik was loaded by a custom loader during dump time
964 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
965 return false;
966 } else {
967 return true;
968 }
969 }
970
971 // (2) Check if we are loading into the same module from the same location as in dump time.
972
973 if (CDSConfig::is_using_optimized_module_handling()) {
974 // Class visibility has not changed between dump time and run time, so a class
975 // that was visible (and thus archived) during dump time is always visible during runtime.
976 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
977 "visibility cannot change between dump time and runtime");
978 return true;
979 }
980 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
981 }
982
983 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
984 InstanceKlass* ik,
985 PackageEntry* pkg_entry,
986 Handle class_loader) {
987 int scp_index = ik->shared_classpath_index();
988 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
989 assert(scp_index >= 0, "must be");
990 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
991 if (!Universe::is_module_initialized()) {
992 assert(scp_entry != nullptr, "must be");
993 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
994 // has restricted the classes can be loaded at this step to be only:
995 // [1] scp_entry->is_modules_image(): classes in java.base, or,
996 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
997 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
998 "only these classes can be loaded before the module system is initialized");
999 assert(class_loader.is_null(), "sanity");
1000 return true;
1001 }
1002
1003 if (pkg_entry == nullptr) {
1004 // We might have looked up pkg_entry before the module system was initialized.
1005 // Need to reload it now.
1006 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1007 if (pkg_name != nullptr) {
1008 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1009 }
1010 }
1011
1012 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1013 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1014 bool was_archived_from_named_module = scp_entry->in_named_module();
1015 bool visible;
1016
1017 if (mod_entry != nullptr && mod_entry->location() == nullptr && mod_entry->is_named()) {
1018 // Archived module for dynamic proxies. It's always visible.
1019 assert(Modules::is_dynamic_proxy_module(mod_entry), "must be");
1020 visible = true;
1021 } else if (was_archived_from_named_module) {
1022 if (should_be_in_named_module) {
1023 // Is the module loaded from the same location as during dump time?
1024 visible = mod_entry->shared_path_index() == scp_index;
1025 if (visible) {
1026 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1027 }
1028 } else {
1029 // During dump time, this class was in a named module, but at run time, this class should be
1030 // in an unnamed module.
1031 visible = false;
1032 }
1033 } else {
1034 if (should_be_in_named_module) {
1035 // During dump time, this class was in an unnamed, but at run time, this class should be
1036 // in a named module.
1037 visible = false;
1038 } else {
1039 visible = true;
1040 }
1041 }
1042
1043 return visible;
1044 }
1045
1046 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1047 Handle class_loader, Handle protection_domain,
1048 bool is_superclass, TRAPS) {
1049 assert(super_type->is_shared(), "must be");
1050
1051 // Quick check if the super type has been already loaded.
1052 // + Don't do it for unregistered classes -- they can be unloaded so
1053 // super_type->class_loader_data() could be stale.
1054 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1055 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1056 // Check if the superclass is loaded by the current class_loader
1057 Symbol* name = super_type->name();
1058 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1059 if (check == super_type) {
1060 return true;
1061 }
1062 }
1063
1064 Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1065 class_loader, protection_domain, is_superclass, CHECK_0);
1066 if (found == super_type) {
1067 return true;
1068 } else {
1069 // The dynamically resolved super type is not the same as the one we used during dump time,
1070 // so we cannot use the class.
1071 return false;
1072 }
1073 }
1074
1075 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1076 Handle protection_domain, TRAPS) {
1077 // Check the superclass and interfaces. They must be the same
1078 // as in dump time, because the layout of <ik> depends on
1079 // the specific layout of ik->super() and ik->local_interfaces().
1080 //
1081 // If unexpected superclass or interfaces are found, we cannot
1082 // load <ik> from the shared archive.
1083
1084 if (ik->super() != nullptr &&
1085 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1086 class_loader, protection_domain, true, THREAD)) {
1087 return false;
1088 }
1089
1090 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1091 int num_interfaces = interfaces->length();
1092 for (int index = 0; index < num_interfaces; index++) {
1093 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1094 return false;
1095 }
1096 }
1097
1098 return true;
1099 }
1100
1101 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1102 Handle class_loader,
1103 Handle protection_domain,
1104 PackageEntry* pkg_entry,
1105 TRAPS) {
1106 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1107 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1108 Symbol* cn = shared_nest_host->name();
1109 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1110 if (s != shared_nest_host) {
1111 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1112 // so we cannot use ik.
1113 return nullptr;
1114 } else {
1115 assert(s->is_shared(), "must be");
1116 }
1117
1118 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1119
1120 if (loaded_ik != nullptr) {
1121 assert(shared_nest_host->is_same_class_package(ik),
1122 "lambda proxy class and its nest host must be in the same package");
1123 // The lambda proxy class and its nest host have the same class loader and class loader data,
1124 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1125 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1126 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1127 ik->set_nest_host(shared_nest_host);
1128 }
1129
1130 return loaded_ik;
1131 }
1132
1133 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1134 Handle class_loader,
1135 Handle protection_domain,
1136 const ClassFileStream *cfs,
1137 PackageEntry* pkg_entry,
1138 TRAPS) {
1139 assert(ik != nullptr, "sanity");
1140 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1141 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1142 Symbol* class_name = ik->name();
1143
1144 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1145 return nullptr;
1146 }
1147
1148 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1149 return nullptr;
1150 }
1151
1152 InstanceKlass* new_ik = nullptr;
1153 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1154 // It will be skipped for shared VM hidden lambda proxy classes.
1155 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1156 new_ik = KlassFactory::check_shared_class_file_load_hook(
1157 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1158 }
1159 if (new_ik != nullptr) {
1160 // The class is changed by CFLH. Return the new class. The shared class is
1161 // not used.
1162 return new_ik;
1163 }
1164
1165 // Adjust methods to recover missing data. They need addresses for
1166 // interpreter entry points and their default native method address
1167 // must be reset.
1168
1169 // Shared classes are all currently loaded by either the bootstrap or
1170 // internal parallel class loaders, so this will never cause a deadlock
1171 // on a custom class loader lock.
1172 // Since this class is already locked with parallel capable class
1173 // loaders, including the bootstrap loader via the placeholder table,
1174 // this lock is currently a nop.
1175
1176 ClassLoaderData* loader_data = class_loader_data(class_loader);
1177 {
1178 HandleMark hm(THREAD);
1179 Handle lockObject = get_loader_lock_or_null(class_loader);
1180 ObjectLocker ol(lockObject, THREAD);
1181 // prohibited package check assumes all classes loaded from archive call
1182 // restore_unshareable_info which calls ik->set_package()
1183 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1184 }
1185
1186 load_shared_class_misc(ik, loader_data);
1187 return ik;
1188 }
1189
1190 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1191 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1192
1193 // For boot loader, ensure that GetSystemPackage knows that a class in this
1194 // package was loaded.
1195 if (loader_data->is_the_null_class_loader_data()) {
1196 s2 path_index = ik->shared_classpath_index();
1197 if (path_index >= 0) { // FIXME ... for lambda form classes
1198 ik->set_classpath_index(path_index);
1199
1200 if (CDSConfig::is_dumping_final_static_archive()) {
1201 if (path_index > ClassLoaderExt::max_used_path_index()) {
1202 ClassLoaderExt::set_max_used_path_index(path_index);
1203 }
1204 }
1205 }
1206 }
1207
1208 // notify a class loaded from shared object
1209 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1210
1211 if (CDSConfig::is_dumping_final_static_archive()) {
1212 SystemDictionaryShared::init_dumptime_info(ik);
1213 if (SystemDictionary::is_platform_class_loader(loader_data->class_loader())) {
1214 ClassLoaderExt::set_has_platform_classes();
1215 } else if (SystemDictionary::is_system_class_loader(loader_data->class_loader())) {
1216 ClassLoaderExt::set_has_app_classes();
1217 }
1218 }
1219 }
1220
1221 #endif // INCLUDE_CDS
1222
1223 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1224
1225 if (class_loader.is_null()) {
1226 ResourceMark rm(THREAD);
1227 PackageEntry* pkg_entry = nullptr;
1228 bool search_only_bootloader_append = false;
1229
1230 // Find the package in the boot loader's package entry table.
1231 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1232 if (pkg_name != nullptr) {
1233 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1234 }
1235
1236 // Prior to attempting to load the class, enforce the boot loader's
1237 // visibility boundaries.
1238 if (!Universe::is_module_initialized()) {
1239 // During bootstrapping, prior to module initialization, any
1240 // class attempting to be loaded must be checked against the
1241 // java.base packages in the boot loader's PackageEntryTable.
1242 // No class outside of java.base is allowed to be loaded during
1243 // this bootstrapping window.
1244 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1245 // Class is either in the unnamed package or in
1246 // a named package within the unnamed module. Either
1247 // case is outside of java.base, do not attempt to
1248 // load the class post java.base definition. If
1249 // java.base has not been defined, let the class load
1250 // and its package will be checked later by
1251 // ModuleEntryTable::verify_javabase_packages.
1252 if (ModuleEntryTable::javabase_defined()) {
1253 return nullptr;
1254 }
1255 } else {
1256 // Check that the class' package is defined within java.base.
1257 ModuleEntry* mod_entry = pkg_entry->module();
1258 Symbol* mod_entry_name = mod_entry->name();
1259 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1260 return nullptr;
1261 }
1262 }
1263 } else {
1264 // After the module system has been initialized, check if the class'
1265 // package is in a module defined to the boot loader.
1266 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1267 // Class is either in the unnamed package, in a named package
1268 // within a module not defined to the boot loader or in a
1269 // a named package within the unnamed module. In all cases,
1270 // limit visibility to search for the class only in the boot
1271 // loader's append path.
1272 if (!ClassLoader::has_bootclasspath_append()) {
1273 // If there is no bootclasspath append entry, no need to continue
1274 // searching.
1275 return nullptr;
1276 }
1277 search_only_bootloader_append = true;
1278 }
1279 }
1280
1281 // Prior to bootstrapping's module initialization, never load a class outside
1282 // of the boot loader's module path
1283 assert(Universe::is_module_initialized() ||
1284 !search_only_bootloader_append,
1285 "Attempt to load a class outside of boot loader's module path");
1286
1287 // Search for classes in the CDS archive.
1288 InstanceKlass* k = nullptr;
1289
1290 #if INCLUDE_CDS
1291 if (UseSharedSpaces)
1292 {
1293 PerfTraceElapsedTime vmtimer(ClassLoader::perf_shared_classload_time());
1294 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1295 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1296 SharedClassLoadingMark slm(THREAD, ik);
1297 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1298 }
1299 }
1300 #endif
1301
1302 if (k == nullptr) {
1303 // Use VM class loader
1304 PerfTraceElapsedTime vmtimer(ClassLoader::perf_sys_classload_time());
1305 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1306 }
1307
1308 // find_or_define_instance_class may return a different InstanceKlass
1309 if (k != nullptr) {
1310 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1311 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1312 }
1313 return k;
1314 } else {
1315 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1316 ResourceMark rm(THREAD);
1317
1318 JavaThread* jt = THREAD;
1319
1320 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1321 ClassLoader::perf_app_classload_selftime(),
1322 ClassLoader::perf_app_classload_count(),
1323 jt->get_thread_stat()->perf_recursion_counts_addr(),
1324 jt->get_thread_stat()->perf_timers_addr(),
1325 PerfClassTraceTime::CLASS_LOAD);
1326
1327 // Translate to external class name format, i.e., convert '/' chars to '.'
1328 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1329
1330 JavaValue result(T_OBJECT);
1331
1332 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1333
1334 // Call public unsynchronized loadClass(String) directly for all class loaders.
1335 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1336 // acquire a class-name based lock rather than the class loader object lock.
1337 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1338 JavaCalls::call_virtual(&result,
1339 class_loader,
1340 spec_klass,
1341 vmSymbols::loadClass_name(),
1342 vmSymbols::string_class_signature(),
1343 string,
1344 CHECK_NULL);
1345
1346 assert(result.get_type() == T_OBJECT, "just checking");
1347 oop obj = result.get_oop();
1348
1349 // Primitive classes return null since forName() can not be
1350 // used to obtain any of the Class objects representing primitives or void
1351 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1352 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1353 // For user defined Java class loaders, check that the name returned is
1354 // the same as that requested. This check is done for the bootstrap
1355 // loader when parsing the class file.
1356 if (class_name == k->name()) {
1357 return k;
1358 }
1359 }
1360 // Class is not found or has the wrong name, return null
1361 return nullptr;
1362 }
1363 }
1364
1365 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1366 Handle class_loader,
1367 TRAPS) {
1368
1369 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1370
1371 // If everything was OK (no exceptions, no null return value), and
1372 // class_loader is NOT the defining loader, do a little more bookkeeping.
1373 if (loaded_class != nullptr &&
1374 loaded_class->class_loader() != class_loader()) {
1375
1376 ClassLoaderData* loader_data = class_loader_data(class_loader);
1377 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1378
1379 // Record dependency for non-parent delegation.
1380 // This recording keeps the defining class loader of the klass (loaded_class) found
1381 // from being unloaded while the initiating class loader is loaded
1382 // even if the reference to the defining class loader is dropped
1383 // before references to the initiating class loader.
1384 loader_data->record_dependency(loaded_class);
1385
1386 update_dictionary(THREAD, loaded_class, loader_data);
1387
1388 if (JvmtiExport::should_post_class_load()) {
1389 JvmtiExport::post_class_load(THREAD, loaded_class);
1390 }
1391 }
1392 return loaded_class;
1393 }
1394
1395 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1396 EventClassDefine event;
1397 if (event.should_commit()) {
1398 event.set_definedClass(k);
1399 event.set_definingClassLoader(def_cld);
1400 event.commit();
1401 }
1402 }
1403
1404 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1405
1406 ClassLoaderData* loader_data = k->class_loader_data();
1407 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1408
1409 // Bootstrap and other parallel classloaders don't acquire a lock,
1410 // they use placeholder token.
1411 // If a parallelCapable class loader calls define_instance_class instead of
1412 // find_or_define_instance_class to get here, we have a timing
1413 // hole with systemDictionary updates and check_constraints
1414 if (!is_parallelCapable(class_loader)) {
1415 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1416 get_loader_lock_or_null(class_loader)),
1417 "define called without lock");
1418 }
1419
1420 // Check class-loading constraints. Throw exception if violation is detected.
1421 // Grabs and releases SystemDictionary_lock
1422 // The check_constraints/find_class call and update_dictionary sequence
1423 // must be "atomic" for a specific class/classloader pair so we never
1424 // define two different instanceKlasses for that class/classloader pair.
1425 // Existing classloaders will call define_instance_class with the
1426 // classloader lock held
1427 // Parallel classloaders will call find_or_define_instance_class
1428 // which will require a token to perform the define class
1429 check_constraints(k, loader_data, true, CHECK);
1430
1431 // Register class just loaded with class loader (placed in ArrayList)
1432 // Note we do this before updating the dictionary, as this can
1433 // fail with an OutOfMemoryError (if it does, we will *not* put this
1434 // class in the dictionary and will not update the class hierarchy).
1435 // JVMTI FollowReferences needs to find the classes this way.
1436 if (k->class_loader() != nullptr) {
1437 methodHandle m(THREAD, Universe::loader_addClass_method());
1438 JavaValue result(T_VOID);
1439 JavaCallArguments args(class_loader);
1440 args.push_oop(Handle(THREAD, k->java_mirror()));
1441 JavaCalls::call(&result, m, &args, CHECK);
1442 }
1443
1444 // Add to class hierarchy, and do possible deoptimizations.
1445 k->add_to_hierarchy(THREAD);
1446
1447 // Add to systemDictionary - so other classes can see it.
1448 // Grabs and releases SystemDictionary_lock
1449 update_dictionary(THREAD, k, loader_data);
1450
1451 // notify jvmti
1452 if (JvmtiExport::should_post_class_load()) {
1453 JvmtiExport::post_class_load(THREAD, k);
1454 }
1455 post_class_define_event(k, loader_data);
1456 }
1457
1458 // Support parallel classloading
1459 // All parallel class loaders, including bootstrap classloader
1460 // lock a placeholder entry for this class/class_loader pair
1461 // to allow parallel defines of different classes for this class loader
1462 // With AllowParallelDefine flag==true, in case they do not synchronize around
1463 // FindLoadedClass/DefineClass, calls, we check for parallel
1464 // loading for them, wait if a defineClass is in progress
1465 // and return the initial requestor's results
1466 // This flag does not apply to the bootstrap classloader.
1467 // With AllowParallelDefine flag==false, call through to define_instance_class
1468 // which will throw LinkageError: duplicate class definition.
1469 // False is the requested default.
1470 // For better performance, the class loaders should synchronize
1471 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1472 // potentially waste time reading and parsing the bytestream.
1473 // Note: VM callers should ensure consistency of k/class_name,class_loader
1474 // Be careful when modifying this code: once you have run
1475 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1476 // you need to find_and_remove it before returning.
1477 // So be careful to not exit with a CHECK_ macro between these calls.
1478 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1479 InstanceKlass* k, TRAPS) {
1480
1481 Symbol* name_h = k->name();
1482 ClassLoaderData* loader_data = class_loader_data(class_loader);
1483 Dictionary* dictionary = loader_data->dictionary();
1484
1485 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1486 {
1487 MutexLocker mu(THREAD, SystemDictionary_lock);
1488 // First check if class already defined
1489 if (is_parallelDefine(class_loader)) {
1490 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1491 if (check != nullptr) {
1492 return check;
1493 }
1494 }
1495
1496 // Acquire define token for this class/classloader
1497 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1498 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1499 // Wait if another thread defining in parallel
1500 // All threads wait - even those that will throw duplicate class: otherwise
1501 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1502 // if other thread has not finished updating dictionary
1503 while (probe->definer() != nullptr) {
1504 SystemDictionary_lock->wait();
1505 }
1506 // Only special cases allow parallel defines and can use other thread's results
1507 // Other cases fall through, and may run into duplicate defines
1508 // caught by finding an entry in the SystemDictionary
1509 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1510 InstanceKlass* ik = probe->instance_klass();
1511 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1512 SystemDictionary_lock->notify_all();
1513 #ifdef ASSERT
1514 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1515 assert(check != nullptr, "definer missed recording success");
1516 #endif
1517 return ik;
1518 } else {
1519 // This thread will define the class (even if earlier thread tried and had an error)
1520 probe->set_definer(THREAD);
1521 }
1522 }
1523
1524 define_instance_class(k, class_loader, THREAD);
1525
1526 // definer must notify any waiting threads
1527 {
1528 MutexLocker mu(THREAD, SystemDictionary_lock);
1529 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1530 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1531 if (!HAS_PENDING_EXCEPTION) {
1532 probe->set_instance_klass(k);
1533 }
1534 probe->set_definer(nullptr);
1535 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1536 SystemDictionary_lock->notify_all();
1537 }
1538
1539 return HAS_PENDING_EXCEPTION ? nullptr : k;
1540 }
1541
1542 // If a class loader supports parallel classloading handle parallel define requests.
1543 // find_or_define_instance_class may return a different InstanceKlass
1544 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1545 InstanceKlass* k, TRAPS) {
1546 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1547 // Clean up original InstanceKlass if duplicate or error
1548 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1549 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1550 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1551 k->class_loader_data()->add_to_deallocate_list(k);
1552 } else if (HAS_PENDING_EXCEPTION) {
1553 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1554 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1555 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1556 k->class_loader_data()->add_to_deallocate_list(k);
1557 }
1558 return defined_k;
1559 }
1560
1561
1562 // ----------------------------------------------------------------------------
1563 // GC support
1564
1565 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1566 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1567
1568 bool unloading_occurred;
1569 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1570 {
1571 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1572 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1573 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1574 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1575 if (unloading_occurred) {
1576 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1577 JFR_ONLY(Jfr::on_unloading_classes();)
1578 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1579 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1580 ClassLoaderDataGraph::clean_module_and_package_info();
1581 LoaderConstraintTable::purge_loader_constraints();
1582 ResolutionErrorTable::purge_resolution_errors();
1583 }
1584 }
1585
1586 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1587
1588 if (unloading_occurred) {
1589 SymbolTable::trigger_cleanup();
1590
1591 if (java_lang_System::allow_security_manager()) {
1592 // Oops referenced by the protection domain cache table may get unreachable independently
1593 // of the class loader (eg. cached protection domain oops). So we need to
1594 // explicitly unlink them here.
1595 // All protection domain oops are linked to the caller class, so if nothing
1596 // unloads, this is not needed.
1597 ProtectionDomainCacheTable::trigger_cleanup();
1598 } else {
1599 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1600 }
1601
1602 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1603 InstanceKlass::clean_initialization_error_table();
1604 }
1605
1606 return unloading_occurred;
1607 }
1608
1609 void SystemDictionary::methods_do(void f(Method*)) {
1610 // Walk methods in loaded classes
1611
1612 {
1613 MutexLocker ml(ClassLoaderDataGraph_lock);
1614 ClassLoaderDataGraph::methods_do(f);
1615 }
1616
1617 auto doit = [&] (InvokeMethodKey key, Method* method) {
1618 if (method != nullptr) {
1619 f(method);
1620 }
1621 };
1622
1623 {
1624 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1625 _invoke_method_intrinsic_table->iterate_all(doit);
1626 }
1627
1628 }
1629
1630 // ----------------------------------------------------------------------------
1631 // Initialization
1632
1633 void SystemDictionary::initialize(TRAPS) {
1634 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1635 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1636 ResolutionErrorTable::initialize();
1637 LoaderConstraintTable::initialize();
1638 PlaceholderTable::initialize();
1639 ProtectionDomainCacheTable::initialize();
1640 #if INCLUDE_CDS
1641 SystemDictionaryShared::initialize();
1642 #endif
1643 // Resolve basic classes
1644 vmClasses::resolve_all(CHECK);
1645 // Resolve classes used by archived heap objects
1646 if (UseSharedSpaces) {
1647 HeapShared::resolve_classes(THREAD);
1648 }
1649 }
1650
1651 // Constraints on class loaders. The details of the algorithm can be
1652 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1653 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1654 // that the dictionary needs to maintain a set of constraints that
1655 // must be satisfied by all classes in the dictionary.
1656 // if defining is true, then LinkageError if already in dictionary
1657 // if initiating loader, then ok if InstanceKlass matches existing entry
1658
1659 void SystemDictionary::check_constraints(InstanceKlass* k,
1660 ClassLoaderData* loader_data,
1661 bool defining,
1662 TRAPS) {
1663 ResourceMark rm(THREAD);
1664 stringStream ss;
1665 bool throwException = false;
1666
1667 {
1668 Symbol* name = k->name();
1669
1670 MutexLocker mu(THREAD, SystemDictionary_lock);
1671
1672 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1673 if (check != nullptr) {
1674 // If different InstanceKlass - duplicate class definition,
1675 // else - ok, class loaded by a different thread in parallel.
1676 // We should only have found it if it was done loading and ok to use.
1677
1678 if ((defining == true) || (k != check)) {
1679 throwException = true;
1680 ss.print("loader %s", loader_data->loader_name_and_id());
1681 ss.print(" attempted duplicate %s definition for %s. (%s)",
1682 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1683 } else {
1684 return;
1685 }
1686 }
1687
1688 if (throwException == false) {
1689 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1690 throwException = true;
1691 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1692 ss.print(" wants to load %s %s.",
1693 k->external_kind(), k->external_name());
1694 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1695 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1696 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1697 existing_klass->external_kind(),
1698 existing_klass->class_loader_data()->loader_name_and_id(),
1699 existing_klass->class_in_module_of_loader(false, true));
1700 } else {
1701 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1702 }
1703 }
1704 }
1705 }
1706
1707 // Throw error now if needed (cannot throw while holding
1708 // SystemDictionary_lock because of rank ordering)
1709 if (throwException == true) {
1710 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1711 }
1712 }
1713
1714 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1715 // have been called.
1716 void SystemDictionary::update_dictionary(JavaThread* current,
1717 InstanceKlass* k,
1718 ClassLoaderData* loader_data) {
1719 MonitorLocker mu1(SystemDictionary_lock);
1720
1721 // Make a new dictionary entry.
1722 Symbol* name = k->name();
1723 Dictionary* dictionary = loader_data->dictionary();
1724 InstanceKlass* sd_check = dictionary->find_class(current, name);
1725 if (sd_check == nullptr) {
1726 dictionary->add_klass(current, name, k);
1727 }
1728 mu1.notify_all();
1729 }
1730
1731 #if INCLUDE_CDS
1732 void SystemDictionary::preload_class(JavaThread* current,
1733 InstanceKlass* k,
1734 ClassLoaderData* loader_data) {
1735 assert_locked_or_safepoint(SystemDictionary_lock);
1736 Symbol* name = k->name();
1737 Dictionary* dictionary = loader_data->dictionary();
1738 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1739 dictionary->add_klass(current, name, k);
1740 }
1741 #endif
1742
1743 // Try to find a class name using the loader constraints. The
1744 // loader constraints might know about a class that isn't fully loaded
1745 // yet and these will be ignored.
1746 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1747 Thread* current, Symbol* class_name, Handle class_loader) {
1748
1749 // First see if it has been loaded directly.
1750 // Force the protection domain to be null. (This removes protection checks.)
1751 Handle no_protection_domain;
1752 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1753 no_protection_domain);
1754 if (klass != nullptr)
1755 return klass;
1756
1757 // Now look to see if it has been loaded elsewhere, and is subject to
1758 // a loader constraint that would require this loader to return the
1759 // klass that is already loaded.
1760 if (Signature::is_array(class_name)) {
1761 // For array classes, their Klass*s are not kept in the
1762 // constraint table. The element Klass*s are.
1763 SignatureStream ss(class_name, false);
1764 int ndims = ss.skip_array_prefix(); // skip all '['s
1765 BasicType t = ss.type();
1766 if (t != T_OBJECT) {
1767 klass = Universe::typeArrayKlass(t);
1768 } else {
1769 MutexLocker mu(current, SystemDictionary_lock);
1770 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1771 }
1772 // If element class already loaded, allocate array klass
1773 if (klass != nullptr) {
1774 klass = klass->array_klass_or_null(ndims);
1775 }
1776 } else {
1777 MutexLocker mu(current, SystemDictionary_lock);
1778 // Non-array classes are easy: simply check the constraint table.
1779 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1780 }
1781
1782 return klass;
1783 }
1784
1785 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1786 Klass* klass_being_linked,
1787 Handle class_loader1,
1788 Handle class_loader2) {
1789 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1790 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1791
1792 Symbol* constraint_name = nullptr;
1793
1794 if (!Signature::is_array(class_name)) {
1795 constraint_name = class_name;
1796 } else {
1797 // For array classes, their Klass*s are not kept in the
1798 // constraint table. The element classes are.
1799 SignatureStream ss(class_name, false);
1800 ss.skip_array_prefix(); // skip all '['s
1801 if (!ss.has_envelope()) {
1802 return true; // primitive types always pass
1803 }
1804 constraint_name = ss.as_symbol();
1805 // Increment refcount to keep constraint_name alive after
1806 // SignatureStream is destructed. It will be decremented below
1807 // before returning.
1808 constraint_name->increment_refcount();
1809 }
1810
1811 Dictionary* dictionary1 = loader_data1->dictionary();
1812 Dictionary* dictionary2 = loader_data2->dictionary();
1813
1814 JavaThread* current = JavaThread::current();
1815 {
1816 MutexLocker mu_s(SystemDictionary_lock);
1817 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1818 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1819 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1820 klass2, loader_data2);
1821 #if INCLUDE_CDS
1822 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1823 !klass_being_linked->is_shared()) {
1824 SystemDictionaryShared::record_linking_constraint(constraint_name,
1825 InstanceKlass::cast(klass_being_linked),
1826 class_loader1, class_loader2);
1827 }
1828 #endif // INCLUDE_CDS
1829 if (Signature::is_array(class_name)) {
1830 constraint_name->decrement_refcount();
1831 }
1832 return result;
1833 }
1834 }
1835
1836 // Add entry to resolution error table to record the error when the first
1837 // attempt to resolve a reference to a class has failed.
1838 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1839 Symbol* error, const char* message,
1840 Symbol* cause, const char* cause_msg) {
1841 {
1842 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1843 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1844 if (entry == nullptr) {
1845 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1846 }
1847 }
1848 }
1849
1850 // Delete a resolution error for RedefineClasses for a constant pool is going away
1851 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1852 ResolutionErrorTable::delete_entry(pool);
1853 }
1854
1855 // Lookup resolution error table. Returns error if found, otherwise null.
1856 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1857 const char** message,
1858 Symbol** cause, const char** cause_msg) {
1859
1860 {
1861 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1862 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1863 if (entry != nullptr) {
1864 *message = entry->message();
1865 *cause = entry->cause();
1866 *cause_msg = entry->cause_msg();
1867 return entry->error();
1868 } else {
1869 return nullptr;
1870 }
1871 }
1872 }
1873
1874 // Add an entry to resolution error table to record an error in resolving or
1875 // validating a nest host. This is used to construct informative error
1876 // messages when IllegalAccessError's occur. If an entry already exists it will
1877 // be updated with the nest host error message.
1878
1879 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1880 int which,
1881 const char* message) {
1882 {
1883 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1884 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1885 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1886 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1887 // still want to add the error message for the higher-level access checks to report. We should
1888 // only reach here under the same error condition, so we can ignore the potential race with setting
1889 // the message. If we see it is already set then we can ignore it.
1890 entry->set_nest_host_error(message);
1891 } else {
1892 ResolutionErrorTable::add_entry(pool, which, message);
1893 }
1894 }
1895 }
1896
1897 // Lookup any nest host error
1898 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1899 {
1900 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1901 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1902 if (entry != nullptr) {
1903 return entry->nest_host_error();
1904 } else {
1905 return nullptr;
1906 }
1907 }
1908 }
1909
1910 // Signature constraints ensure that callers and callees agree about
1911 // the meaning of type names in their signatures. This routine is the
1912 // intake for constraints. It collects them from several places:
1913 //
1914 // * LinkResolver::resolve_method (if check_access is true) requires
1915 // that the resolving class (the caller) and the defining class of
1916 // the resolved method (the callee) agree on each type in the
1917 // method's signature.
1918 //
1919 // * LinkResolver::resolve_interface_method performs exactly the same
1920 // checks.
1921 //
1922 // * LinkResolver::resolve_field requires that the constant pool
1923 // attempting to link to a field agree with the field's defining
1924 // class about the type of the field signature.
1925 //
1926 // * klassVtable::initialize_vtable requires that, when a class
1927 // overrides a vtable entry allocated by a superclass, that the
1928 // overriding method (i.e., the callee) agree with the superclass
1929 // on each type in the method's signature.
1930 //
1931 // * klassItable::initialize_itable requires that, when a class fills
1932 // in its itables, for each non-abstract method installed in an
1933 // itable, the method (i.e., the callee) agree with the interface
1934 // on each type in the method's signature.
1935 //
1936 // All those methods have a boolean (check_access, checkconstraints)
1937 // which turns off the checks. This is used from specialized contexts
1938 // such as bootstrapping, dumping, and debugging.
1939 //
1940 // No direct constraint is placed between the class and its
1941 // supertypes. Constraints are only placed along linked relations
1942 // between callers and callees. When a method overrides or implements
1943 // an abstract method in a supertype (superclass or interface), the
1944 // constraints are placed as if the supertype were the caller to the
1945 // overriding method. (This works well, since callers to the
1946 // supertype have already established agreement between themselves and
1947 // the supertype.) As a result of all this, a class can disagree with
1948 // its supertype about the meaning of a type name, as long as that
1949 // class neither calls a relevant method of the supertype, nor is
1950 // called (perhaps via an override) from the supertype.
1951 //
1952 //
1953 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1954 //
1955 // Make sure all class components (including arrays) in the given
1956 // signature will be resolved to the same class in both loaders.
1957 // Returns the name of the type that failed a loader constraint check, or
1958 // null if no constraint failed. No exception except OOME is thrown.
1959 // Arrays are not added to the loader constraint table, their elements are.
1960 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1961 Klass* klass_being_linked,
1962 Handle loader1, Handle loader2,
1963 bool is_method) {
1964 // Nothing to do if loaders are the same.
1965 if (loader1() == loader2()) {
1966 return nullptr;
1967 }
1968
1969 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1970 if (ss.is_reference()) {
1971 Symbol* sig = ss.as_symbol();
1972 // Note: In the future, if template-like types can take
1973 // arguments, we will want to recognize them and dig out class
1974 // names hiding inside the argument lists.
1975 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1976 return sig;
1977 }
1978 }
1979 }
1980 return nullptr;
1981 }
1982
1983 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1984 Symbol* signature,
1985 TRAPS) {
1986
1987 const int iid_as_int = vmIntrinsics::as_int(iid);
1988 assert(MethodHandles::is_signature_polymorphic(iid) &&
1989 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1990 iid != vmIntrinsics::_invokeGeneric,
1991 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1992
1993 InvokeMethodKey key(signature, iid_as_int);
1994 Method** met = nullptr;
1995
1996 // We only want one entry in the table for this (signature/id, method) pair but the code
1997 // to create the intrinsic method needs to be outside the lock.
1998 // The first thread claims the entry by adding the key and the other threads wait, until the
1999 // Method has been added as the value.
2000 {
2001 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2002 while (true) {
2003 bool created;
2004 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2005 assert(met != nullptr, "either created or found");
2006 if (*met != nullptr) {
2007 return *met;
2008 } else if (created) {
2009 // The current thread won the race and will try to create the full entry.
2010 break;
2011 } else {
2012 // Another thread beat us to it, so wait for them to complete
2013 // and return *met; or if they hit an error we get another try.
2014 ml.wait();
2015 // Note it is not safe to read *met here as that entry could have
2016 // been deleted, so we must loop and try put_if_absent again.
2017 }
2018 }
2019 }
2020
2021 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2022 bool throw_error = HAS_PENDING_EXCEPTION;
2023 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2024 // Generate a compiled form of the MH intrinsic
2025 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2026 AdapterHandlerLibrary::create_native_wrapper(m);
2027 // Check if have the compiled code.
2028 throw_error = (!m->has_compiled_code());
2029 }
2030
2031 {
2032 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2033 if (throw_error) {
2034 // Remove the entry and let another thread try, or get the same exception.
2035 bool removed = _invoke_method_intrinsic_table->remove(key);
2036 assert(removed, "must be the owner");
2037 ml.notify_all();
2038 } else {
2039 signature->make_permanent(); // The signature is never unloaded.
2040 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2041 m->code()->entry_point() == m->from_compiled_entry()),
2042 "MH intrinsic invariant");
2043 *met = m(); // insert the element
2044 ml.notify_all();
2045 return m();
2046 }
2047 }
2048
2049 // Throw OOM or the pending exception in the JavaThread
2050 if (throw_error && !HAS_PENDING_EXCEPTION) {
2051 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2052 "Out of space in CodeCache for method handle intrinsic");
2053 }
2054 return nullptr;
2055 }
2056
2057 #if INCLUDE_CDS
2058 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2059 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2060 methods->append(m);
2061 };
2062 _invoke_method_intrinsic_table->iterate_all(do_method);
2063 }
2064
2065 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2066 if (UseSharedSpaces) {
2067 EXCEPTION_MARK;
2068 restore_archived_method_handle_intrinsics_impl(THREAD);
2069 if (HAS_PENDING_EXCEPTION) {
2070 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics"));
2071 }
2072 }
2073 }
2074
2075 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2076 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics();
2077 for (int i = 0; i < list->length(); i++) {
2078 methodHandle m(THREAD, list->at(i));
2079 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2080 m->constants()->restore_unshareable_info(CHECK);
2081 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2082 AdapterHandlerLibrary::create_native_wrapper(m);
2083 if (!m->has_compiled_code()) {
2084 ResourceMark rm(THREAD);
2085 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2086 }
2087 }
2088
2089 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2090 InvokeMethodKey key(m->signature(), iid_as_int);
2091 bool created = _invoke_method_intrinsic_table->put(key, m());
2092 assert(created, "must be");
2093 }
2094 }
2095 #endif
2096
2097 // Helper for unpacking the return value from linkMethod and linkCallSite.
2098 static Method* unpack_method_and_appendix(Handle mname,
2099 Klass* accessing_klass,
2100 objArrayHandle appendix_box,
2101 Handle* appendix_result,
2102 TRAPS) {
2103 if (mname.not_null()) {
2104 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2105 if (m != nullptr) {
2106 oop appendix = appendix_box->obj_at(0);
2107 LogTarget(Info, methodhandles) lt;
2108 if (lt.develop_is_enabled()) {
2109 ResourceMark rm(THREAD);
2110 LogStream ls(lt);
2111 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2112 m->print_on(&ls);
2113 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2114 ls.cr();
2115 }
2116
2117 (*appendix_result) = Handle(THREAD, appendix);
2118 // the target is stored in the cpCache and if a reference to this
2119 // MemberName is dropped we need a way to make sure the
2120 // class_loader containing this method is kept alive.
2121 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2122 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2123 this_key->record_dependency(m->method_holder());
2124 return mh();
2125 }
2126 }
2127 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2128 }
2129
2130 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2131 Symbol* name,
2132 Symbol* signature,
2133 Klass* accessing_klass,
2134 Handle* appendix_result,
2135 TRAPS) {
2136 guarantee(THREAD->can_call_java(), "");
2137 Handle method_type =
2138 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2139
2140 int ref_kind = JVM_REF_invokeVirtual;
2141 oop name_oop = StringTable::intern(name, CHECK_NULL);
2142 Handle name_str (THREAD, name_oop);
2143 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2144 assert(appendix_box->obj_at(0) == nullptr, "");
2145
2146 // This should not happen. JDK code should take care of that.
2147 if (accessing_klass == nullptr || method_type.is_null()) {
2148 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2149 }
2150
2151 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2152 JavaCallArguments args;
2153 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2154 args.push_int(ref_kind);
2155 args.push_oop(Handle(THREAD, klass->java_mirror()));
2156 args.push_oop(name_str);
2157 args.push_oop(method_type);
2158 args.push_oop(appendix_box);
2159 JavaValue result(T_OBJECT);
2160 JavaCalls::call_static(&result,
2161 vmClasses::MethodHandleNatives_klass(),
2162 vmSymbols::linkMethod_name(),
2163 vmSymbols::linkMethod_signature(),
2164 &args, CHECK_NULL);
2165 Handle mname(THREAD, result.get_oop());
2166 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2167 }
2168
2169 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2170 // We must ensure that all class loaders everywhere will reach this class, for any client.
2171 // This is a safe bet for public classes in java.lang, such as Object and String.
2172 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2173 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2174 static bool is_always_visible_class(oop mirror) {
2175 Klass* klass = java_lang_Class::as_Klass(mirror);
2176 if (klass->is_objArray_klass()) {
2177 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2178 }
2179 if (klass->is_typeArray_klass()) {
2180 return true; // primitive array
2181 }
2182 assert(klass->is_instance_klass(), "%s", klass->external_name());
2183 return klass->is_public() &&
2184 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2185 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2186 }
2187
2188 // Find or construct the Java mirror (java.lang.Class instance) for
2189 // the given field type signature, as interpreted relative to the
2190 // given class loader. Handles primitives, void, references, arrays,
2191 // and all other reflectable types, except method types.
2192 // N.B. Code in reflection should use this entry point.
2193 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2194 Klass* accessing_klass,
2195 Handle class_loader,
2196 Handle protection_domain,
2197 SignatureStream::FailureMode failure_mode,
2198 TRAPS) {
2199 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2200 "one or the other, or perhaps neither");
2201
2202 // What we have here must be a valid field descriptor,
2203 // and all valid field descriptors are supported.
2204 // Produce the same java.lang.Class that reflection reports.
2205 if (accessing_klass != nullptr) {
2206 class_loader = Handle(THREAD, accessing_klass->class_loader());
2207 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2208 }
2209 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2210 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2211 if (mirror_oop == nullptr) {
2212 return Handle(); // report failure this way
2213 }
2214 Handle mirror(THREAD, mirror_oop);
2215
2216 if (accessing_klass != nullptr) {
2217 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2218 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2219 if (sel_klass != nullptr) {
2220 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2221 }
2222 }
2223 return mirror;
2224 }
2225
2226
2227 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2228 // signature, as interpreted relative to the given class loader.
2229 // Because of class loader constraints, all method handle usage must be
2230 // consistent with this loader.
2231 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2232 Klass* accessing_klass,
2233 TRAPS) {
2234 Handle empty;
2235 OopHandle* o;
2236 {
2237 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2238 o = _invoke_method_type_table->get(signature);
2239 }
2240
2241 if (o != nullptr) {
2242 oop mt = o->resolve();
2243 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2244 return Handle(THREAD, mt);
2245 } else if (!THREAD->can_call_java()) {
2246 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2247 return Handle(); // do not attempt from within compiler, unless it was cached
2248 }
2249
2250 Handle class_loader, protection_domain;
2251 if (accessing_klass != nullptr) {
2252 class_loader = Handle(THREAD, accessing_klass->class_loader());
2253 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2254 }
2255 bool can_be_cached = true;
2256 int npts = ArgumentCount(signature).size();
2257 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2258 int arg = 0;
2259 Handle rt; // the return type from the signature
2260 ResourceMark rm(THREAD);
2261 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2262 oop mirror = nullptr;
2263 if (can_be_cached) {
2264 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2265 mirror = ss.as_java_mirror(Handle(), Handle(),
2266 SignatureStream::ReturnNull, CHECK_(empty));
2267 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2268 // Fall back to accessing_klass context.
2269 can_be_cached = false;
2270 }
2271 }
2272 if (!can_be_cached) {
2273 // Resolve, throwing a real error if it doesn't work.
2274 mirror = ss.as_java_mirror(class_loader, protection_domain,
2275 SignatureStream::NCDFError, CHECK_(empty));
2276 }
2277 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2278 if (ss.at_return_type())
2279 rt = Handle(THREAD, mirror);
2280 else
2281 pts->obj_at_put(arg++, mirror);
2282
2283 // Check accessibility.
2284 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2285 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2286 mirror = nullptr; // safety
2287 // Emulate ConstantPool::verify_constant_pool_resolve.
2288 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2289 }
2290 }
2291 assert(arg == npts, "");
2292
2293 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2294 JavaCallArguments args(Handle(THREAD, rt()));
2295 args.push_oop(pts);
2296 JavaValue result(T_OBJECT);
2297 JavaCalls::call_static(&result,
2298 vmClasses::MethodHandleNatives_klass(),
2299 vmSymbols::findMethodHandleType_name(),
2300 vmSymbols::findMethodHandleType_signature(),
2301 &args, CHECK_(empty));
2302 Handle method_type(THREAD, result.get_oop());
2303
2304 if (can_be_cached) {
2305 // We can cache this MethodType inside the JVM.
2306 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2307 bool created = false;
2308 assert(method_type != nullptr, "unexpected null");
2309 OopHandle* h = _invoke_method_type_table->get(signature);
2310 if (h == nullptr) {
2311 signature->make_permanent(); // The signature is never unloaded.
2312 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2313 bool created = _invoke_method_type_table->put(signature, elem);
2314 assert(created, "better be created");
2315 }
2316 }
2317 // report back to the caller with the MethodType
2318 return method_type;
2319 }
2320
2321 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2322 Klass* accessing_klass,
2323 TRAPS) {
2324 Handle empty;
2325 ResourceMark rm(THREAD);
2326 SignatureStream ss(signature, /*is_method=*/ false);
2327 if (!ss.is_done()) {
2328 Handle class_loader, protection_domain;
2329 if (accessing_klass != nullptr) {
2330 class_loader = Handle(THREAD, accessing_klass->class_loader());
2331 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2332 }
2333 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2334 ss.next();
2335 if (ss.is_done()) {
2336 return Handle(THREAD, mirror);
2337 }
2338 }
2339 return empty;
2340 }
2341
2342 // Ask Java code to find or construct a method handle constant.
2343 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2344 int ref_kind, //e.g., JVM_REF_invokeVirtual
2345 Klass* callee,
2346 Symbol* name,
2347 Symbol* signature,
2348 TRAPS) {
2349 Handle empty;
2350 if (caller == nullptr) {
2351 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2352 }
2353 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2354 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2355
2356 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2357 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2358 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2359 java_lang_invoke_MemberName::set_name (mname(), name_str());
2360 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2361 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2362
2363 if (ref_kind == JVM_REF_invokeVirtual &&
2364 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2365 // Skip resolution for public signature polymorphic methods such as
2366 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2367 // They require appendix argument which MemberName resolution doesn't handle.
2368 // There's special logic on JDK side to handle them
2369 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2370 } else {
2371 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2372 }
2373
2374 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2375 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2376
2377 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2378 JavaCallArguments args;
2379 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2380 args.push_int(ref_kind);
2381 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2382 args.push_oop(name_str);
2383 args.push_oop(type);
2384 JavaValue result(T_OBJECT);
2385 JavaCalls::call_static(&result,
2386 vmClasses::MethodHandleNatives_klass(),
2387 vmSymbols::linkMethodHandleConstant_name(),
2388 vmSymbols::linkMethodHandleConstant_signature(),
2389 &args, CHECK_(empty));
2390 return Handle(THREAD, result.get_oop());
2391 }
2392
2393 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2394 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2395 // with linkage results being stored back into the bootstrap specifier.
2396 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2397 // Resolve the bootstrap specifier, its name, type, and static arguments
2398 bootstrap_specifier.resolve_bsm(CHECK);
2399
2400 // This should not happen. JDK code should take care of that.
2401 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2402 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2403 }
2404
2405 bool is_indy = bootstrap_specifier.is_method_call();
2406 objArrayHandle appendix_box;
2407 if (is_indy) {
2408 // Some method calls may require an appendix argument. Arrange to receive it.
2409 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2410 assert(appendix_box->obj_at(0) == nullptr, "");
2411 }
2412
2413 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2414 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2415 JavaCallArguments args;
2416 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2417 args.push_oop(bootstrap_specifier.bsm());
2418 args.push_oop(bootstrap_specifier.name_arg());
2419 args.push_oop(bootstrap_specifier.type_arg());
2420 args.push_oop(bootstrap_specifier.arg_values());
2421 if (is_indy) {
2422 args.push_oop(appendix_box);
2423 }
2424 JavaValue result(T_OBJECT);
2425 JavaCalls::call_static(&result,
2426 vmClasses::MethodHandleNatives_klass(),
2427 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2428 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2429 &args, CHECK);
2430
2431 Handle value(THREAD, result.get_oop());
2432 if (is_indy) {
2433 Handle appendix;
2434 Method* method = unpack_method_and_appendix(value,
2435 bootstrap_specifier.caller(),
2436 appendix_box,
2437 &appendix, CHECK);
2438 methodHandle mh(THREAD, method);
2439 bootstrap_specifier.set_resolved_method(mh, appendix);
2440 } else {
2441 bootstrap_specifier.set_resolved_value(value);
2442 }
2443
2444 // sanity check
2445 assert(bootstrap_specifier.is_resolved() ||
2446 (bootstrap_specifier.is_method_call() &&
2447 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2448 }
2449
2450
2451 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2452 assert(m != nullptr, "Unexpected nullptr Method*");
2453 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2454 }
2455
2456 // ----------------------------------------------------------------------------
2457
2458 void SystemDictionary::print_on(outputStream *st) {
2459 CDS_ONLY(SystemDictionaryShared::print_on(st));
2460 GCMutexLocker mu(SystemDictionary_lock);
2461
2462 ClassLoaderDataGraph::print_dictionary(st);
2463
2464 // Placeholders
2465 PlaceholderTable::print_on(st);
2466 st->cr();
2467
2468 // loader constraints - print under SD_lock
2469 LoaderConstraintTable::print_on(st);
2470 st->cr();
2471
2472 ProtectionDomainCacheTable::print_on(st);
2473 st->cr();
2474 }
2475
2476 void SystemDictionary::print() { print_on(tty); }
2477
2478 void SystemDictionary::verify() {
2479
2480 GCMutexLocker mu(SystemDictionary_lock);
2481
2482 // Verify dictionary
2483 ClassLoaderDataGraph::verify_dictionary();
2484
2485 // Verify constraint table
2486 LoaderConstraintTable::verify();
2487
2488 // Verify protection domain table
2489 ProtectionDomainCacheTable::verify();
2490 }
2491
2492 void SystemDictionary::dump(outputStream *st, bool verbose) {
2493 assert_locked_or_safepoint(SystemDictionary_lock);
2494 if (verbose) {
2495 print_on(st);
2496 } else {
2497 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2498 ClassLoaderDataGraph::print_table_statistics(st);
2499 LoaderConstraintTable::print_table_statistics(st);
2500 ProtectionDomainCacheTable::print_table_statistics(st);
2501 }
2502 }
2503
2504 // Utility for dumping dictionaries.
2505 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2506 DCmdWithParser(output, heap),
2507 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2508 "BOOLEAN", false, "false") {
2509 _dcmdparser.add_dcmd_option(&_verbose);
2510 }
2511
2512 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2513 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2514 _verbose.value());
2515 VMThread::execute(&dumper);
2516 }