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