1 /*
2 * Copyright (c) 1997, 2022, 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 "jvm.h"
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 "code/codeCache.hpp"
49 #include "gc/shared/gcTraceTime.inline.hpp"
50 #include "interpreter/bootstrapInfo.hpp"
51 #include "jfr/jfrEvents.hpp"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/metaspaceClosure.hpp"
55 #include "memory/oopFactory.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/fieldStreams.inline.hpp"
60 #include "oops/instanceKlass.hpp"
61 #include "oops/klass.inline.hpp"
62 #include "oops/method.inline.hpp"
63 #include "oops/objArrayKlass.hpp"
64 #include "oops/objArrayOop.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oopHandle.inline.hpp"
67 #include "oops/symbol.hpp"
68 #include "oops/typeArrayKlass.hpp"
69 #include "oops/inlineKlass.inline.hpp"
70 #include "prims/jvmtiExport.hpp"
71 #include "prims/methodHandles.hpp"
72 #include "runtime/arguments.hpp"
73 #include "runtime/handles.inline.hpp"
74 #include "runtime/java.hpp"
75 #include "runtime/javaCalls.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/os.hpp"
78 #include "runtime/sharedRuntime.hpp"
79 #include "runtime/signature.hpp"
80 #include "services/classLoadingService.hpp"
81 #include "services/diagnosticCommand.hpp"
82 #include "services/finalizerService.hpp"
83 #include "services/threadService.hpp"
84 #include "utilities/macros.hpp"
85 #include "utilities/utf8.hpp"
86 #if INCLUDE_CDS
87 #include "classfile/systemDictionaryShared.hpp"
88 #endif
89 #if INCLUDE_JFR
90 #include "jfr/jfr.hpp"
91 #endif
92
93 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
94 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
95 ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
96
97 OopHandle SystemDictionary::_java_system_loader;
98 OopHandle SystemDictionary::_java_platform_loader;
99
100 // Default ProtectionDomainCacheSize value
101 const int defaultProtectionDomainCacheSize = 1009;
102
103 const int _resolution_error_size = 107; // number of entries in resolution error table
104 const int _invoke_method_size = 139; // number of entries in invoke method table
105
106 // Hashtable holding placeholders for classes being loaded.
107 const int _placeholder_table_size = 1009;
108 static PlaceholderTable* _placeholders = NULL;
109 static PlaceholderTable* placeholders() { return _placeholders; }
110
111 // Constraints on class loaders
112 const int _loader_constraint_size = 107; // number of entries in constraint table
113 static LoaderConstraintTable* _loader_constraints;
114 static LoaderConstraintTable* constraints() { return _loader_constraints; }
115
116 // ----------------------------------------------------------------------------
117 // Java-level SystemLoader and PlatformLoader
118 oop SystemDictionary::java_system_loader() {
119 return _java_system_loader.resolve();
120 }
121
122 oop SystemDictionary::java_platform_loader() {
123 return _java_platform_loader.resolve();
124 }
125
126 void SystemDictionary::compute_java_loaders(TRAPS) {
127 JavaValue result(T_OBJECT);
128 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
129 JavaCalls::call_static(&result,
130 class_loader_klass,
131 vmSymbols::getSystemClassLoader_name(),
132 vmSymbols::void_classloader_signature(),
133 CHECK);
134
135 _java_system_loader = OopHandle(Universe::vm_global(), result.get_oop());
136
137 JavaCalls::call_static(&result,
138 class_loader_klass,
139 vmSymbols::getPlatformClassLoader_name(),
140 vmSymbols::void_classloader_signature(),
141 CHECK);
142
143 _java_platform_loader = OopHandle(Universe::vm_global(), result.get_oop());
144 }
145
146 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
147 if (create_mirror_cld) {
148 // Add a new class loader data to the graph.
149 return ClassLoaderDataGraph::add(class_loader, true);
150 } else {
151 return (class_loader() == NULL) ? ClassLoaderData::the_null_class_loader_data() :
152 ClassLoaderDataGraph::find_or_create(class_loader);
153 }
154 }
155
156 // ----------------------------------------------------------------------------
157 // Parallel class loading check
158
159 bool is_parallelCapable(Handle class_loader) {
160 if (class_loader.is_null()) return true;
161 return java_lang_ClassLoader::parallelCapable(class_loader());
162 }
163 // ----------------------------------------------------------------------------
164 // ParallelDefineClass flag does not apply to bootclass loader
165 bool is_parallelDefine(Handle class_loader) {
166 if (class_loader.is_null()) return false;
167 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
168 return true;
169 }
170 return false;
171 }
172
173 // Returns true if the passed class loader is the builtin application class loader
174 // or a custom system class loader. A customer system class loader can be
175 // specified via -Djava.system.class.loader.
176 bool SystemDictionary::is_system_class_loader(oop class_loader) {
177 if (class_loader == NULL) {
178 return false;
179 }
180 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
181 class_loader == _java_system_loader.peek());
182 }
183
184 // Returns true if the passed class loader is the platform class loader.
185 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
186 if (class_loader == NULL) {
187 return false;
188 }
189 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
190 }
191
192 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
193 // If class_loader is NULL or parallelCapable, the JVM doesn't acquire a lock while loading.
194 if (is_parallelCapable(class_loader)) {
195 return Handle();
196 } else {
197 return class_loader;
198 }
199 }
200
201 // ----------------------------------------------------------------------------
202 // Resolving of classes
203
204 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
205 if (name == NULL) {
206 THROW_MSG_0(exception, "No class name given");
207 }
208 if ((int)strlen(name) > Symbol::max_length()) {
209 // It's impossible to create this class; the name cannot fit
210 // into the constant pool.
211 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
212 "Class name exceeds maximum length of %d: %s",
213 Symbol::max_length(),
214 name);
215 return NULL;
216 }
217 // Callers should ensure that the name is never an illegal UTF8 string.
218 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
219 "Class name is not a valid utf8 string.");
220
221 // Make a new symbol for the class name.
222 return SymbolTable::new_symbol(name);
223 }
224
225 #ifdef ASSERT
226 // Used to verify that class loading succeeded in adding k to the dictionary.
227 void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
228 MutexLocker mu(SystemDictionary_lock);
229 ClassLoaderData* loader_data = k->class_loader_data();
230 Dictionary* dictionary = loader_data->dictionary();
231 assert(class_name == k->name(), "Must be the same");
232 unsigned int name_hash = dictionary->compute_hash(class_name);
233 InstanceKlass* kk = dictionary->find_class(name_hash, class_name);
234 assert(kk == k, "should be present in dictionary");
235 }
236 #endif
237
238 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
239 if (HAS_PENDING_EXCEPTION) {
240 // If we have a pending exception we forward it to the caller, unless throw_error is true,
241 // in which case we have to check whether the pending exception is a ClassNotFoundException,
242 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
243 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
244 ResourceMark rm(THREAD);
245 Handle e(THREAD, PENDING_EXCEPTION);
246 CLEAR_PENDING_EXCEPTION;
247 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
248 } else {
249 return; // the caller will throw the incoming exception
250 }
251 }
252 // If the class is not found, ie, caller has checked that klass is NULL, throw the appropriate
253 // error or exception depending on the value of throw_error.
254 ResourceMark rm(THREAD);
255 if (throw_error) {
256 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
257 } else {
258 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
259 }
260 }
261
262 // Forwards to resolve_or_null
263
264 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
265 bool throw_error, TRAPS) {
266 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
267 // Check for pending exception or null klass, and throw exception
268 if (HAS_PENDING_EXCEPTION || klass == NULL) {
269 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
270 }
271 return klass;
272 }
273
274 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
275
276 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
277 if (Signature::is_array(class_name)) {
278 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
279 } else {
280 return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
281 }
282 }
283
284 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
285 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
286 Handle class_loader,
287 Handle protection_domain,
288 TRAPS) {
289 assert(class_name != NULL && !Signature::is_array(class_name), "must be");
290 if (Signature::has_envelope(class_name)) {
291 ResourceMark rm(THREAD);
292 // Ignore wrapping L and ;. (and Q and ; for value types);
293 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
294 class_name->utf8_length() - 2);
295 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
296 } else {
297 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
298 }
299 }
300
301 // Forwards to resolve_instance_class_or_null
302
303 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
304 Handle class_loader,
305 Handle protection_domain,
306 TRAPS) {
307 assert(Signature::is_array(class_name), "must be array");
308 ResourceMark rm(THREAD);
309 SignatureStream ss(class_name, false);
310 int ndims = ss.skip_array_prefix(); // skip all '['s
311 Klass* k = NULL;
312 BasicType t = ss.type();
313 if (ss.has_envelope()) {
314 Symbol* obj_class = ss.as_symbol();
315 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
316 class_loader,
317 protection_domain,
318 CHECK_NULL);
319 if (k != NULL) {
320 if (class_name->is_Q_array_signature()) {
321 if (!k->is_inline_klass()) {
322 THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), "L/Q mismatch on bottom type");
323 }
324 k = InlineKlass::cast(k)->value_array_klass(ndims, CHECK_NULL);
325 } else {
326 k = k->array_klass(ndims, CHECK_NULL);
327 }
328 }
329 } else {
330 k = Universe::typeArrayKlassObj(t);
331 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
332 }
333 return k;
334 }
335
336 static inline void log_circularity_error(Thread* thread, PlaceholderEntry* probe) {
337 LogTarget(Debug, class, load, placeholders) lt;
338 if (lt.is_enabled()) {
339 ResourceMark rm(thread);
340 LogStream ls(lt);
341 ls.print("ClassCircularityError detected for placeholder ");
342 probe->print_entry(&ls);
343 ls.cr();
344 }
345 }
346
347 // Must be called for any superclass or superinterface resolution
348 // during class definition to allow class circularity checking
349 // superinterface callers:
350 // parse_interfaces - from defineClass
351 // superclass callers:
352 // ClassFileParser - from defineClass
353 // load_shared_class - while loading a class from shared archive
354 // resolve_instance_class_or_null:
355 // via: handle_parallel_super_load
356 // when resolving a class that has an existing placeholder with
357 // a saved superclass [i.e. a defineClass is currently in progress]
358 // If another thread is trying to resolve the class, it must do
359 // superclass checks on its own thread to catch class circularity and
360 // to avoid deadlock.
361 //
362 // resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
363 // resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
364 // placeholder for the same thread, class, classloader is found.
365 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
366 //
367 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
368 Symbol* super_name,
369 Handle class_loader,
370 Handle protection_domain,
371 bool is_superclass,
372 TRAPS) {
373
374 assert(super_name != NULL, "null superclass for resolving");
375 assert(!Signature::is_array(super_name), "invalid superclass name");
376 #if INCLUDE_CDS
377 if (DumpSharedSpaces) {
378 // Special processing for handling UNREGISTERED shared classes.
379 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
380 super_name, is_superclass);
381 if (k) {
382 return k;
383 }
384 }
385 #endif // INCLUDE_CDS
386
387 // If klass is already loaded, just return the superclass or superinterface.
388 // Make sure there's a placeholder for the class_name before resolving.
389 // This is used as a claim that this thread is currently loading superclass/classloader
390 // and for ClassCircularity checks.
391
392 ClassLoaderData* loader_data = class_loader_data(class_loader);
393 Dictionary* dictionary = loader_data->dictionary();
394 unsigned int name_hash = dictionary->compute_hash(class_name);
395 assert(placeholders()->compute_hash(class_name) == name_hash, "they're the same hashcode");
396
397 // can't throw error holding a lock
398 bool throw_circularity_error = false;
399 {
400 MutexLocker mu(THREAD, SystemDictionary_lock);
401 InstanceKlass* klassk = dictionary->find_class(name_hash, class_name);
402 InstanceKlass* quicksuperk;
403 // To support parallel loading: if class is done loading, just return the superclass
404 // if the super_name matches class->super()->name() and if the class loaders match.
405 // Otherwise, a LinkageError will be thrown later.
406 if (klassk != NULL && is_superclass &&
407 ((quicksuperk = klassk->java_super()) != NULL) &&
408 ((quicksuperk->name() == super_name) &&
409 (quicksuperk->class_loader() == class_loader()))) {
410 return quicksuperk;
411 } else {
412 // Must check ClassCircularity before checking if superclass is already loaded.
413 PlaceholderEntry* probe = placeholders()->get_entry(name_hash, class_name, loader_data);
414 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
415 log_circularity_error(THREAD, probe);
416 throw_circularity_error = true;
417 }
418 }
419
420 if (!throw_circularity_error) {
421 // Be careful not to exit resolve_super without removing this placeholder.
422 PlaceholderEntry* newprobe = placeholders()->find_and_add(name_hash,
423 class_name,
424 loader_data,
425 PlaceholderTable::LOAD_SUPER,
426 super_name, THREAD);
427 }
428 }
429
430 if (throw_circularity_error) {
431 ResourceMark rm(THREAD);
432 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
433 }
434
435 // Resolve the superclass or superinterface, check results on return
436 InstanceKlass* superk =
437 SystemDictionary::resolve_instance_class_or_null_helper(super_name,
438 class_loader,
439 protection_domain,
440 THREAD);
441
442 // Clean up placeholder entry.
443 {
444 MutexLocker mu(THREAD, SystemDictionary_lock);
445 placeholders()->find_and_remove(name_hash, class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
446 SystemDictionary_lock->notify_all();
447 }
448
449 // Check for pending exception or null superk, and throw exception
450 if (HAS_PENDING_EXCEPTION || superk == NULL) {
451 handle_resolution_exception(super_name, true, CHECK_NULL);
452 }
453
454 return superk;
455 }
456
457 Klass* SystemDictionary::resolve_inline_type_field_or_fail(AllFieldStream* fs,
458 Handle class_loader,
459 Handle protection_domain,
460 bool throw_error,
461 TRAPS) {
462 Symbol* class_name = fs->signature()->fundamental_name(THREAD);
463 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
464 ClassLoaderData* loader_data = class_loader_data(class_loader);
465 unsigned int p_hash = placeholders()->compute_hash(class_name);
466 bool throw_circularity_error = false;
467 PlaceholderEntry* oldprobe;
468
469 {
470 MutexLocker mu(THREAD, SystemDictionary_lock);
471 oldprobe = placeholders()->get_entry(p_hash, class_name, loader_data);
472 if (oldprobe != NULL &&
473 oldprobe->check_seen_thread(THREAD, PlaceholderTable::PRIMITIVE_OBJECT_FIELD)) {
474 throw_circularity_error = true;
475
476 } else {
477 placeholders()->find_and_add(p_hash, class_name, loader_data,
478 PlaceholderTable::PRIMITIVE_OBJECT_FIELD, NULL, THREAD);
479 }
480 }
481
482 Klass* klass = NULL;
483 if (!throw_circularity_error) {
484 klass = SystemDictionary::resolve_or_fail(class_name, class_loader,
485 protection_domain, true, THREAD);
486 } else {
487 ResourceMark rm(THREAD);
488 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
489 }
490
491 {
492 MutexLocker mu(THREAD, SystemDictionary_lock);
493 placeholders()->find_and_remove(p_hash, class_name, loader_data,
494 PlaceholderTable::PRIMITIVE_OBJECT_FIELD, THREAD);
495 }
496
497 class_name->decrement_refcount();
498 return klass;
499 }
500
501 // We only get here if this thread finds that another thread
502 // has already claimed the placeholder token for the current operation,
503 // but that other thread either never owned or gave up the
504 // object lock
505 // Waits on SystemDictionary_lock to indicate placeholder table updated
506 // On return, caller must recheck placeholder table state
507 //
508 // We only get here if
509 // 1) custom classLoader, i.e. not bootstrap classloader
510 // 2) custom classLoader has broken the class loader objectLock
511 // so another thread got here in parallel
512 //
513 // lockObject must be held.
514 // Complicated dance due to lock ordering:
515 // Must first release the classloader object lock to
516 // allow initial definer to complete the class definition
517 // and to avoid deadlock
518 // Reclaim classloader lock object with same original recursion count
519 // Must release SystemDictionary_lock after notify, since
520 // class loader lock must be claimed before SystemDictionary_lock
521 // to prevent deadlocks
522 //
523 // The notify allows applications that did an untimed wait() on
524 // the classloader object lock to not hang.
525 static void double_lock_wait(JavaThread* thread, Handle lockObject) {
526 assert_lock_strong(SystemDictionary_lock);
527
528 assert(lockObject() != NULL, "lockObject must be non-NULL");
529 bool calledholdinglock
530 = ObjectSynchronizer::current_thread_holds_lock(thread, lockObject);
531 assert(calledholdinglock, "must hold lock for notify");
532 assert(!is_parallelCapable(lockObject), "lockObject must not be parallelCapable");
533 // These don't throw exceptions.
534 ObjectSynchronizer::notifyall(lockObject, thread);
535 intx recursions = ObjectSynchronizer::complete_exit(lockObject, thread);
536 SystemDictionary_lock->wait();
537 SystemDictionary_lock->unlock();
538 ObjectSynchronizer::reenter(lockObject, recursions, thread);
539 SystemDictionary_lock->lock();
540 }
541
542 // If the class in is in the placeholder table, class loading is in progress.
543 // For cases where the application changes threads to load classes, it
544 // is critical to ClassCircularity detection that we try loading
545 // the superclass on the new thread internally, so we do parallel
546 // superclass loading here. This avoids deadlock for ClassCircularity
547 // detection for parallelCapable class loaders that lock on a per-class lock.
548 static void handle_parallel_super_load(Symbol* name,
549 Symbol* superclassname,
550 Handle class_loader,
551 Handle protection_domain, TRAPS) {
552
553 // superk is not used; resolve_super_or_fail is called for circularity check only.
554 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
555 superclassname,
556 class_loader,
557 protection_domain,
558 true,
559 CHECK);
560 }
561
562 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
563 // Serial class loaders and bootstrap classloader do wait for superclass loads
564 static bool should_wait_for_loading(Handle class_loader) {
565 return class_loader.is_null() || !is_parallelCapable(class_loader);
566 }
567
568 // For bootstrap and non-parallelCapable class loaders, check and wait for
569 // another thread to complete loading this class.
570 InstanceKlass* SystemDictionary::handle_parallel_loading(JavaThread* current,
571 unsigned int name_hash,
572 Symbol* name,
573 ClassLoaderData* loader_data,
574 Handle lockObject,
575 bool* throw_circularity_error) {
576 PlaceholderEntry* oldprobe = placeholders()->get_entry(name_hash, name, loader_data);
577 if (oldprobe != NULL) {
578 // only need check_seen_thread once, not on each loop
579 // 6341374 java/lang/Instrument with -Xcomp
580 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
581 log_circularity_error(current, oldprobe);
582 *throw_circularity_error = true;
583 return NULL;
584 } else {
585 // Wait until the first thread has finished loading this class. Also wait until all the
586 // threads trying to load its superclass have removed their placeholders.
587 while (oldprobe != NULL &&
588 (oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {
589
590 // We only get here if the application has released the
591 // classloader lock when another thread was in the middle of loading a
592 // superclass/superinterface for this class, and now
593 // this thread is also trying to load this class.
594 // To minimize surprises, the first thread that started to
595 // load a class should be the one to complete the loading
596 // with the classfile it initially expected.
597 // This logic has the current thread wait once it has done
598 // all the superclass/superinterface loading it can, until
599 // the original thread completes the class loading or fails
600 // If it completes we will use the resulting InstanceKlass
601 // which we will find below in the systemDictionary.
602 oldprobe = NULL; // Other thread could delete this placeholder entry
603
604 if (lockObject.is_null()) {
605 SystemDictionary_lock->wait();
606 } else {
607 double_lock_wait(current, lockObject);
608 }
609
610 // Check if classloading completed while we were waiting
611 InstanceKlass* check = loader_data->dictionary()->find_class(name_hash, name);
612 if (check != NULL) {
613 // Klass is already loaded, so just return it
614 return check;
615 }
616 // check if other thread failed to load and cleaned up
617 oldprobe = placeholders()->get_entry(name_hash, name, loader_data);
618 }
619 }
620 }
621 return NULL;
622 }
623
624 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
625 assert(event != NULL, "invariant");
626 assert(k != NULL, "invariant");
627 assert(event->should_commit(), "invariant");
628 event->set_loadedClass(k);
629 event->set_definingClassLoader(k->class_loader_data());
630 event->set_initiatingClassLoader(init_cld);
631 event->commit();
632 }
633
634 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
635 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
636 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
637 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
638 // This can return NULL, an exception or an InstanceKlass.
639 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
640 Handle class_loader,
641 Handle protection_domain,
642 TRAPS) {
643 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
644 assert(name != NULL && !Signature::is_array(name) &&
645 !Signature::has_envelope(name), "invalid class name");
646
647 EventClassLoad class_load_start_event;
648
649 HandleMark hm(THREAD);
650
651 // Fix for 4474172; see evaluation for more details
652 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
653 ClassLoaderData* loader_data = register_loader(class_loader);
654 Dictionary* dictionary = loader_data->dictionary();
655 unsigned int name_hash = dictionary->compute_hash(name);
656
657 // Do lookup to see if class already exists and the protection domain
658 // has the right access.
659 // This call uses find which checks protection domain already matches
660 // All subsequent calls use find_class, and set loaded_class so that
661 // before we return a result, we call out to java to check for valid protection domain.
662 InstanceKlass* probe = dictionary->find(name_hash, name, protection_domain);
663 if (probe != NULL) return probe;
664
665 // Non-bootstrap class loaders will call out to class loader and
666 // define via jvm/jni_DefineClass which will acquire the
667 // class loader object lock to protect against multiple threads
668 // defining the class in parallel by accident.
669 // This lock must be acquired here so the waiter will find
670 // any successful result in the SystemDictionary and not attempt
671 // the define.
672 // ParallelCapable class loaders and the bootstrap classloader
673 // do not acquire lock here.
674 Handle lockObject = get_loader_lock_or_null(class_loader);
675 ObjectLocker ol(lockObject, THREAD);
676
677 bool super_load_in_progress = false;
678 InstanceKlass* loaded_class = NULL;
679 Symbol* superclassname = NULL;
680
681 assert(THREAD->can_call_java(),
682 "can not load classes with compiler thread: class=%s, classloader=%s",
683 name->as_C_string(),
684 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
685
686 assert(placeholders()->compute_hash(name) == name_hash, "they're the same hashcode");
687
688 // Check again (after locking) if the class already exists in SystemDictionary
689 {
690 MutexLocker mu(THREAD, SystemDictionary_lock);
691 InstanceKlass* check = dictionary->find_class(name_hash, name);
692 if (check != NULL) {
693 // InstanceKlass is already loaded, but we still need to check protection domain below.
694 loaded_class = check;
695 } else {
696 PlaceholderEntry* placeholder = placeholders()->get_entry(name_hash, name, loader_data);
697 if (placeholder != NULL && placeholder->super_load_in_progress()) {
698 super_load_in_progress = true;
699 superclassname = placeholder->supername();
700 assert(superclassname != NULL, "superclass has to have a name");
701 }
702 }
703 }
704
705 // If the class is in the placeholder table with super_class set,
706 // handle superclass loading in progress.
707 if (super_load_in_progress) {
708 handle_parallel_super_load(name, superclassname,
709 class_loader,
710 protection_domain,
711 CHECK_NULL);
712 }
713
714 bool throw_circularity_error = false;
715 if (loaded_class == NULL) {
716 bool load_placeholder_added = false;
717
718 // Add placeholder entry to record loading instance class
719 // Four cases:
720 // case 1. Bootstrap classloader
721 // This classloader supports parallelism at the classloader level
722 // but only allows a single thread to load a class/classloader pair.
723 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
724 // case 2. parallelCapable user level classloaders
725 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
726 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
727 // case 3. traditional classloaders that rely on the classloader object lock
728 // There should be no need for need for LOAD_INSTANCE, except:
729 // case 4. traditional class loaders that break the classloader object lock
730 // as a legacy deadlock workaround. Detection of this case requires that
731 // this check is done while holding the classloader object lock,
732 // and that lock is still held when calling classloader's loadClass.
733 // For these classloaders, we ensure that the first requestor
734 // completes the load and other requestors wait for completion.
735 {
736 MutexLocker mu(THREAD, SystemDictionary_lock);
737 if (should_wait_for_loading(class_loader)) {
738 loaded_class = handle_parallel_loading(THREAD,
739 name_hash,
740 name,
741 loader_data,
742 lockObject,
743 &throw_circularity_error);
744 }
745
746 // Recheck if the class has been loaded for all class loader cases and
747 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
748 if (!throw_circularity_error && loaded_class == NULL) {
749 InstanceKlass* check = dictionary->find_class(name_hash, name);
750 if (check != NULL) {
751 loaded_class = check;
752 } else if (should_wait_for_loading(class_loader)) {
753 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
754 PlaceholderEntry* newprobe = placeholders()->find_and_add(name_hash, name, loader_data,
755 PlaceholderTable::LOAD_INSTANCE,
756 NULL,
757 THREAD);
758 load_placeholder_added = true;
759 }
760 }
761 }
762
763 // Must throw error outside of owning lock
764 if (throw_circularity_error) {
765 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
766 ResourceMark rm(THREAD);
767 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
768 }
769
770 // Be careful when modifying this code: once you have run
771 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
772 // you need to find_and_remove it before returning.
773 // So be careful to not exit with a CHECK_ macro between these calls.
774
775 if (loaded_class == NULL) {
776 // Do actual loading
777 loaded_class = load_instance_class(name_hash, name, class_loader, THREAD);
778 }
779
780 if (load_placeholder_added) {
781 // clean up placeholder entries for LOAD_INSTANCE success or error
782 // This brackets the SystemDictionary updates for both defining
783 // and initiating loaders
784 MutexLocker mu(THREAD, SystemDictionary_lock);
785 placeholders()->find_and_remove(name_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
786 SystemDictionary_lock->notify_all();
787 }
788 }
789
790 if (HAS_PENDING_EXCEPTION || loaded_class == NULL) {
791 return NULL;
792 }
793
794 if (class_load_start_event.should_commit()) {
795 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
796 }
797
798 // Make sure we have the right class in the dictionary
799 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
800
801 // Check if the protection domain is present it has the right access
802 if (protection_domain() != NULL) {
803 // Verify protection domain. If it fails an exception is thrown
804 dictionary->validate_protection_domain(name_hash, loaded_class, class_loader, protection_domain, CHECK_NULL);
805 }
806
807 return loaded_class;
808 }
809
810
811 // This routine does not lock the system dictionary.
812 //
813 // Since readers don't hold a lock, we must make sure that system
814 // dictionary entries are added to in a safe way (all links must
815 // be updated in an MT-safe manner). All entries are removed during class
816 // unloading, when this class loader is no longer referenced.
817 //
818 // Callers should be aware that an entry could be added just after
819 // _dictionary->bucket(index) is read here, so the caller will not see
820 // the new entry.
821
822 InstanceKlass* SystemDictionary::find_instance_klass(Symbol* class_name,
823 Handle class_loader,
824 Handle protection_domain) {
825
826 // The result of this call should be consistent with the result
827 // of the call to resolve_instance_class_or_null().
828 // See evaluation 6790209 and 4474172 for more details.
829 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
830 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
831
832 if (loader_data == NULL) {
833 // If the ClassLoaderData has not been setup,
834 // then the class loader has no entries in the dictionary.
835 return NULL;
836 }
837
838 Dictionary* dictionary = loader_data->dictionary();
839 unsigned int name_hash = dictionary->compute_hash(class_name);
840 return dictionary->find(name_hash, class_name, protection_domain);
841 }
842
843 // Look for a loaded instance or array klass by name. Do not do any loading.
844 // return NULL in case of error.
845 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
846 Handle class_loader,
847 Handle protection_domain) {
848 Klass* k = NULL;
849 assert(class_name != NULL, "class name must be non NULL");
850
851 if (Signature::is_array(class_name)) {
852 // The name refers to an array. Parse the name.
853 // dimension and object_key in FieldArrayInfo are assigned as a
854 // side-effect of this call
855 SignatureStream ss(class_name, false);
856 int ndims = ss.skip_array_prefix(); // skip all '['s
857 BasicType t = ss.type();
858 if (t != T_OBJECT && t != T_PRIMITIVE_OBJECT) {
859 k = Universe::typeArrayKlassObj(t);
860 } else {
861 k = SystemDictionary::find_instance_klass(ss.as_symbol(), class_loader, protection_domain);
862 }
863 if (k != NULL) {
864 if (class_name->is_Q_array_signature()) {
865 k = InlineKlass::cast(k)->value_array_klass_or_null(ndims);
866 } else {
867 k = k->array_klass_or_null(ndims);
868 }
869 }
870 } else {
871 k = find_instance_klass(class_name, class_loader, protection_domain);
872 }
873 return k;
874 }
875
876 // Note: this method is much like resolve_class_from_stream, but
877 // does not publish the classes in the SystemDictionary.
878 // Handles Lookup.defineClass hidden.
879 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
880 ClassFileStream* st,
881 Symbol* class_name,
882 Handle class_loader,
883 const ClassLoadInfo& cl_info,
884 TRAPS) {
885
886 EventClassLoad class_load_start_event;
887 ClassLoaderData* loader_data;
888
889 // - for hidden classes that are not strong: create a new CLD that has a class holder and
890 // whose loader is the Lookup class's loader.
891 // - for hidden class: add the class to the Lookup class's loader's CLD.
892 assert (cl_info.is_hidden(), "only used for hidden classes");
893 bool create_mirror_cld = !cl_info.is_strong_hidden();
894 loader_data = register_loader(class_loader, create_mirror_cld);
895
896 assert(st != NULL, "invariant");
897 assert(st->need_verify(), "invariant");
898
899 // Parse stream and create a klass.
900 InstanceKlass* k = KlassFactory::create_from_stream(st,
901 class_name,
902 loader_data,
903 cl_info,
904 CHECK_NULL);
905 assert(k != NULL, "no klass created");
906
907 // Hidden classes that are not strong must update ClassLoaderData holder
908 // so that they can be unloaded when the mirror is no longer referenced.
909 if (!cl_info.is_strong_hidden()) {
910 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
911 }
912
913 {
914 MutexLocker mu_r(THREAD, Compile_lock);
915 // Add to class hierarchy, and do possible deoptimizations.
916 add_to_hierarchy(k);
917 // But, do not add to dictionary.
918 }
919
920 k->link_class(CHECK_NULL);
921
922 // notify jvmti
923 if (JvmtiExport::should_post_class_load()) {
924 JvmtiExport::post_class_load(THREAD, k);
925 }
926 if (class_load_start_event.should_commit()) {
927 post_class_load_event(&class_load_start_event, k, loader_data);
928 }
929
930 return k;
931 }
932
933 // Add a klass to the system from a stream (called by jni_DefineClass and
934 // JVM_DefineClass).
935 // Note: class_name can be NULL. In that case we do not know the name of
936 // the class until we have parsed the stream.
937 // This function either returns an InstanceKlass or throws an exception. It does
938 // not return NULL without a pending exception.
939 InstanceKlass* SystemDictionary::resolve_class_from_stream(
940 ClassFileStream* st,
941 Symbol* class_name,
942 Handle class_loader,
943 const ClassLoadInfo& cl_info,
944 TRAPS) {
945
946 HandleMark hm(THREAD);
947
948 ClassLoaderData* loader_data = register_loader(class_loader);
949
950 // Classloaders that support parallelism, e.g. bootstrap classloader,
951 // do not acquire lock here
952 Handle lockObject = get_loader_lock_or_null(class_loader);
953 ObjectLocker ol(lockObject, THREAD);
954
955 // Parse the stream and create a klass.
956 // Note that we do this even though this klass might
957 // already be present in the SystemDictionary, otherwise we would not
958 // throw potential ClassFormatErrors.
959 InstanceKlass* k = NULL;
960
961 #if INCLUDE_CDS
962 if (!DumpSharedSpaces) {
963 k = SystemDictionaryShared::lookup_from_stream(class_name,
964 class_loader,
965 cl_info.protection_domain(),
966 st,
967 CHECK_NULL);
968 }
969 #endif
970
971 if (k == NULL) {
972 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
973 }
974
975 assert(k != NULL, "no klass created");
976 Symbol* h_name = k->name();
977 assert(class_name == NULL || class_name == h_name, "name mismatch");
978
979 // Add class just loaded
980 // If a class loader supports parallel classloading, handle parallel define requests.
981 // find_or_define_instance_class may return a different InstanceKlass,
982 // in which case the old k would be deallocated
983 if (is_parallelCapable(class_loader)) {
984 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
985 } else {
986 define_instance_class(k, class_loader, THREAD);
987
988 // If defining the class throws an exception register 'k' for cleanup.
989 if (HAS_PENDING_EXCEPTION) {
990 assert(k != NULL, "Must have an instance klass here!");
991 loader_data->add_to_deallocate_list(k);
992 return NULL;
993 }
994 }
995
996 // Make sure we have an entry in the SystemDictionary on success
997 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
998
999 return k;
1000 }
1001
1002 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
1003 Symbol* class_name,
1004 Handle class_loader,
1005 const ClassLoadInfo& cl_info,
1006 TRAPS) {
1007 if (cl_info.is_hidden()) {
1008 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
1009 } else {
1010 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
1011 }
1012 }
1013
1014
1015 #if INCLUDE_CDS
1016 // Check if a shared class can be loaded by the specific classloader.
1017 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1018 InstanceKlass* ik,
1019 PackageEntry* pkg_entry,
1020 Handle class_loader) {
1021 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1022 "Cannot use sharing if java.base is patched");
1023
1024 // (1) Check if we are loading into the same loader as in dump time.
1025
1026 if (ik->is_shared_boot_class()) {
1027 if (class_loader() != NULL) {
1028 return false;
1029 }
1030 } else if (ik->is_shared_platform_class()) {
1031 if (class_loader() != java_platform_loader()) {
1032 return false;
1033 }
1034 } else if (ik->is_shared_app_class()) {
1035 if (class_loader() != java_system_loader()) {
1036 return false;
1037 }
1038 } else {
1039 // ik was loaded by a custom loader during dump time
1040 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
1041 return false;
1042 } else {
1043 return true;
1044 }
1045 }
1046
1047 // (2) Check if we are loading into the same module from the same location as in dump time.
1048
1049 if (MetaspaceShared::use_optimized_module_handling()) {
1050 // Class visibility has not changed between dump time and run time, so a class
1051 // that was visible (and thus archived) during dump time is always visible during runtime.
1052 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
1053 "visibility cannot change between dump time and runtime");
1054 return true;
1055 }
1056 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
1057 }
1058
1059 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
1060 InstanceKlass* ik,
1061 PackageEntry* pkg_entry,
1062 Handle class_loader) {
1063 int scp_index = ik->shared_classpath_index();
1064 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
1065 assert(scp_index >= 0, "must be");
1066 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
1067 if (!Universe::is_module_initialized()) {
1068 assert(scp_entry != NULL && scp_entry->is_modules_image(),
1069 "Loading non-bootstrap classes before the module system is initialized");
1070 assert(class_loader.is_null(), "sanity");
1071 return true;
1072 }
1073
1074 ModuleEntry* mod_entry = (pkg_entry == NULL) ? NULL : pkg_entry->module();
1075 bool should_be_in_named_module = (mod_entry != NULL && mod_entry->is_named());
1076 bool was_archived_from_named_module = scp_entry->in_named_module();
1077 bool visible;
1078
1079 if (was_archived_from_named_module) {
1080 if (should_be_in_named_module) {
1081 // Is the module loaded from the same location as during dump time?
1082 visible = mod_entry->shared_path_index() == scp_index;
1083 if (visible) {
1084 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1085 }
1086 } else {
1087 // During dump time, this class was in a named module, but at run time, this class should be
1088 // in an unnamed module.
1089 visible = false;
1090 }
1091 } else {
1092 if (should_be_in_named_module) {
1093 // During dump time, this class was in an unnamed, but at run time, this class should be
1094 // in a named module.
1095 visible = false;
1096 } else {
1097 visible = true;
1098 }
1099 }
1100
1101 return visible;
1102 }
1103
1104 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1105 Handle class_loader, Handle protection_domain,
1106 bool is_superclass, TRAPS) {
1107 assert(super_type->is_shared(), "must be");
1108
1109 // Quick check if the super type has been already loaded.
1110 // + Don't do it for unregistered classes -- they can be unloaded so
1111 // super_type->class_loader_data() could be stale.
1112 // + Don't check if loader data is NULL, ie. the super_type isn't fully loaded.
1113 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != NULL) {
1114 // Check if the superclass is loaded by the current class_loader
1115 Symbol* name = super_type->name();
1116 InstanceKlass* check = find_instance_klass(name, class_loader, protection_domain);
1117 if (check == super_type) {
1118 return true;
1119 }
1120 }
1121
1122 Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1123 class_loader, protection_domain, is_superclass, CHECK_0);
1124 if (found == super_type) {
1125 return true;
1126 } else {
1127 // The dynamically resolved super type is not the same as the one we used during dump time,
1128 // so we cannot use the class.
1129 return false;
1130 }
1131 }
1132
1133 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1134 Handle protection_domain, TRAPS) {
1135 // Check the superclass and interfaces. They must be the same
1136 // as in dump time, because the layout of <ik> depends on
1137 // the specific layout of ik->super() and ik->local_interfaces().
1138 //
1139 // If unexpected superclass or interfaces are found, we cannot
1140 // load <ik> from the shared archive.
1141
1142 if (ik->super() != NULL &&
1143 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1144 class_loader, protection_domain, true, THREAD)) {
1145 return false;
1146 }
1147
1148 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1149 int num_interfaces = interfaces->length();
1150 for (int index = 0; index < num_interfaces; index++) {
1151 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1152 return false;
1153 }
1154 }
1155
1156 return true;
1157 }
1158
1159 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1160 Handle class_loader,
1161 Handle protection_domain,
1162 PackageEntry* pkg_entry,
1163 TRAPS) {
1164 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1165 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1166 Symbol* cn = shared_nest_host->name();
1167 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1168 if (s != shared_nest_host) {
1169 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1170 // so we cannot use ik.
1171 return NULL;
1172 } else {
1173 assert(s->is_shared(), "must be");
1174 }
1175
1176 // The lambda proxy class and its nest host have the same class loader and class loader data,
1177 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1178 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1179 assert(shared_nest_host->class_loader_data() == ClassLoaderData::class_loader_data(class_loader()), "mismatched class loader data");
1180 ik->set_nest_host(shared_nest_host);
1181
1182 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, NULL, pkg_entry, CHECK_NULL);
1183
1184 if (loaded_ik != NULL) {
1185 assert(shared_nest_host->is_same_class_package(ik),
1186 "lambda proxy class and its nest host must be in the same package");
1187 }
1188
1189 return loaded_ik;
1190 }
1191
1192 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1193 Handle class_loader,
1194 Handle protection_domain,
1195 const ClassFileStream *cfs,
1196 PackageEntry* pkg_entry,
1197 TRAPS) {
1198 assert(ik != NULL, "sanity");
1199 assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
1200 Symbol* class_name = ik->name();
1201
1202 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1203 return NULL;
1204 }
1205
1206 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1207 return NULL;
1208 }
1209
1210
1211 if (ik->has_inline_type_fields()) {
1212 for (AllFieldStream fs(ik->fields(), ik->constants()); !fs.done(); fs.next()) {
1213 if (Signature::basic_type(fs.signature()) == T_PRIMITIVE_OBJECT) {
1214 if (!fs.access_flags().is_static()) {
1215 // Pre-load inline class
1216 Klass* real_k = SystemDictionary::resolve_inline_type_field_or_fail(&fs,
1217 class_loader, protection_domain, true, CHECK_NULL);
1218 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1219 if (real_k != k) {
1220 // oops, the app has substituted a different version of k!
1221 return NULL;
1222 }
1223 }
1224 }
1225 }
1226 }
1227
1228 InstanceKlass* new_ik = NULL;
1229 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1230 // It will be skipped for shared VM hidden lambda proxy classes.
1231 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1232 new_ik = KlassFactory::check_shared_class_file_load_hook(
1233 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1234 }
1235 if (new_ik != NULL) {
1236 // The class is changed by CFLH. Return the new class. The shared class is
1237 // not used.
1238 return new_ik;
1239 }
1240
1241 // Adjust methods to recover missing data. They need addresses for
1242 // interpreter entry points and their default native method address
1243 // must be reset.
1244
1245 // Shared classes are all currently loaded by either the bootstrap or
1246 // internal parallel class loaders, so this will never cause a deadlock
1247 // on a custom class loader lock.
1248 // Since this class is already locked with parallel capable class
1249 // loaders, including the bootstrap loader via the placeholder table,
1250 // this lock is currently a nop.
1251
1252 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1253 {
1254 HandleMark hm(THREAD);
1255 Handle lockObject = get_loader_lock_or_null(class_loader);
1256 ObjectLocker ol(lockObject, THREAD);
1257 // prohibited package check assumes all classes loaded from archive call
1258 // restore_unshareable_info which calls ik->set_package()
1259 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1260 }
1261
1262 load_shared_class_misc(ik, loader_data);
1263
1264 return ik;
1265 }
1266
1267 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1268 ik->print_class_load_logging(loader_data, NULL, NULL);
1269
1270 // For boot loader, ensure that GetSystemPackage knows that a class in this
1271 // package was loaded.
1272 if (loader_data->is_the_null_class_loader_data()) {
1273 int path_index = ik->shared_classpath_index();
1274 ik->set_classpath_index(path_index);
1275 }
1276
1277 // notify a class loaded from shared object
1278 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1279 }
1280
1281 #endif // INCLUDE_CDS
1282
1283 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1284
1285 if (class_loader.is_null()) {
1286 ResourceMark rm(THREAD);
1287 PackageEntry* pkg_entry = NULL;
1288 bool search_only_bootloader_append = false;
1289 ClassLoaderData *loader_data = class_loader_data(class_loader);
1290
1291 // Find the package in the boot loader's package entry table.
1292 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1293 if (pkg_name != NULL) {
1294 pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1295 }
1296
1297 // Prior to attempting to load the class, enforce the boot loader's
1298 // visibility boundaries.
1299 if (!Universe::is_module_initialized()) {
1300 // During bootstrapping, prior to module initialization, any
1301 // class attempting to be loaded must be checked against the
1302 // java.base packages in the boot loader's PackageEntryTable.
1303 // No class outside of java.base is allowed to be loaded during
1304 // this bootstrapping window.
1305 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1306 // Class is either in the unnamed package or in
1307 // a named package within the unnamed module. Either
1308 // case is outside of java.base, do not attempt to
1309 // load the class post java.base definition. If
1310 // java.base has not been defined, let the class load
1311 // and its package will be checked later by
1312 // ModuleEntryTable::verify_javabase_packages.
1313 if (ModuleEntryTable::javabase_defined()) {
1314 return NULL;
1315 }
1316 } else {
1317 // Check that the class' package is defined within java.base.
1318 ModuleEntry* mod_entry = pkg_entry->module();
1319 Symbol* mod_entry_name = mod_entry->name();
1320 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1321 return NULL;
1322 }
1323 }
1324 } else {
1325 // After the module system has been initialized, check if the class'
1326 // package is in a module defined to the boot loader.
1327 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1328 // Class is either in the unnamed package, in a named package
1329 // within a module not defined to the boot loader or in a
1330 // a named package within the unnamed module. In all cases,
1331 // limit visibility to search for the class only in the boot
1332 // loader's append path.
1333 if (!ClassLoader::has_bootclasspath_append()) {
1334 // If there is no bootclasspath append entry, no need to continue
1335 // searching.
1336 return NULL;
1337 }
1338 search_only_bootloader_append = true;
1339 }
1340 }
1341
1342 // Prior to bootstrapping's module initialization, never load a class outside
1343 // of the boot loader's module path
1344 assert(Universe::is_module_initialized() ||
1345 !search_only_bootloader_append,
1346 "Attempt to load a class outside of boot loader's module path");
1347
1348 // Search for classes in the CDS archive.
1349 InstanceKlass* k = NULL;
1350
1351 #if INCLUDE_CDS
1352 if (UseSharedSpaces)
1353 {
1354 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1355 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1356 if (ik != NULL && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1357 SharedClassLoadingMark slm(THREAD, ik);
1358 k = load_shared_class(ik, class_loader, Handle(), NULL, pkg_entry, CHECK_NULL);
1359 }
1360 }
1361 #endif
1362
1363 if (k == NULL) {
1364 // Use VM class loader
1365 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1366 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1367 }
1368
1369 // find_or_define_instance_class may return a different InstanceKlass
1370 if (k != NULL) {
1371 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1372 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1373 }
1374 return k;
1375 } else {
1376 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1377 ResourceMark rm(THREAD);
1378
1379 JavaThread* jt = THREAD;
1380
1381 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1382 ClassLoader::perf_app_classload_selftime(),
1383 ClassLoader::perf_app_classload_count(),
1384 jt->get_thread_stat()->perf_recursion_counts_addr(),
1385 jt->get_thread_stat()->perf_timers_addr(),
1386 PerfClassTraceTime::CLASS_LOAD);
1387
1388 // Translate to external class name format, i.e., convert '/' chars to '.'
1389 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1390
1391 JavaValue result(T_OBJECT);
1392
1393 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1394
1395 // Call public unsynchronized loadClass(String) directly for all class loaders.
1396 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1397 // acquire a class-name based lock rather than the class loader object lock.
1398 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1399 JavaCalls::call_virtual(&result,
1400 class_loader,
1401 spec_klass,
1402 vmSymbols::loadClass_name(),
1403 vmSymbols::string_class_signature(),
1404 string,
1405 CHECK_NULL);
1406
1407 assert(result.get_type() == T_OBJECT, "just checking");
1408 oop obj = result.get_oop();
1409
1410 // Primitive classes return null since forName() can not be
1411 // used to obtain any of the Class objects representing primitives or void
1412 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1413 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1414 // For user defined Java class loaders, check that the name returned is
1415 // the same as that requested. This check is done for the bootstrap
1416 // loader when parsing the class file.
1417 if (class_name == k->name()) {
1418 return k;
1419 }
1420 }
1421 // Class is not found or has the wrong name, return NULL
1422 return NULL;
1423 }
1424 }
1425
1426 InstanceKlass* SystemDictionary::load_instance_class(unsigned int name_hash,
1427 Symbol* name,
1428 Handle class_loader,
1429 TRAPS) {
1430
1431 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1432
1433 // If everything was OK (no exceptions, no null return value), and
1434 // class_loader is NOT the defining loader, do a little more bookkeeping.
1435 if (loaded_class != NULL &&
1436 loaded_class->class_loader() != class_loader()) {
1437
1438 check_constraints(name_hash, loaded_class, class_loader, false, CHECK_NULL);
1439
1440 // Record dependency for non-parent delegation.
1441 // This recording keeps the defining class loader of the klass (loaded_class) found
1442 // from being unloaded while the initiating class loader is loaded
1443 // even if the reference to the defining class loader is dropped
1444 // before references to the initiating class loader.
1445 ClassLoaderData* loader_data = class_loader_data(class_loader);
1446 loader_data->record_dependency(loaded_class);
1447
1448 { // Grabbing the Compile_lock prevents systemDictionary updates
1449 // during compilations.
1450 MutexLocker mu(THREAD, Compile_lock);
1451 update_dictionary(name_hash, loaded_class, class_loader);
1452 }
1453
1454 if (JvmtiExport::should_post_class_load()) {
1455 JvmtiExport::post_class_load(THREAD, loaded_class);
1456 }
1457 }
1458 return loaded_class;
1459 }
1460
1461 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1462 EventClassDefine event;
1463 if (event.should_commit()) {
1464 event.set_definedClass(k);
1465 event.set_definingClassLoader(def_cld);
1466 event.commit();
1467 }
1468 }
1469
1470 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1471
1472 ClassLoaderData* loader_data = k->class_loader_data();
1473 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1474
1475 // Bootstrap and other parallel classloaders don't acquire a lock,
1476 // they use placeholder token.
1477 // If a parallelCapable class loader calls define_instance_class instead of
1478 // find_or_define_instance_class to get here, we have a timing
1479 // hole with systemDictionary updates and check_constraints
1480 if (!is_parallelCapable(class_loader)) {
1481 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1482 get_loader_lock_or_null(class_loader)),
1483 "define called without lock");
1484 }
1485
1486 // Check class-loading constraints. Throw exception if violation is detected.
1487 // Grabs and releases SystemDictionary_lock
1488 // The check_constraints/find_class call and update_dictionary sequence
1489 // must be "atomic" for a specific class/classloader pair so we never
1490 // define two different instanceKlasses for that class/classloader pair.
1491 // Existing classloaders will call define_instance_class with the
1492 // classloader lock held
1493 // Parallel classloaders will call find_or_define_instance_class
1494 // which will require a token to perform the define class
1495 Symbol* name_h = k->name();
1496 Dictionary* dictionary = loader_data->dictionary();
1497 unsigned int name_hash = dictionary->compute_hash(name_h);
1498 check_constraints(name_hash, k, class_loader, true, CHECK);
1499
1500 // Register class just loaded with class loader (placed in ArrayList)
1501 // Note we do this before updating the dictionary, as this can
1502 // fail with an OutOfMemoryError (if it does, we will *not* put this
1503 // class in the dictionary and will not update the class hierarchy).
1504 // JVMTI FollowReferences needs to find the classes this way.
1505 if (k->class_loader() != NULL) {
1506 methodHandle m(THREAD, Universe::loader_addClass_method());
1507 JavaValue result(T_VOID);
1508 JavaCallArguments args(class_loader);
1509 args.push_oop(Handle(THREAD, k->java_mirror()));
1510 JavaCalls::call(&result, m, &args, CHECK);
1511 }
1512
1513 // Add the new class. We need recompile lock during update of CHA.
1514 {
1515 MutexLocker mu_r(THREAD, Compile_lock);
1516
1517 // Add to class hierarchy, and do possible deoptimizations.
1518 add_to_hierarchy(k);
1519
1520 // Add to systemDictionary - so other classes can see it.
1521 // Grabs and releases SystemDictionary_lock
1522 update_dictionary(name_hash, k, class_loader);
1523 }
1524 k->eager_initialize(THREAD);
1525
1526 // notify jvmti
1527 if (JvmtiExport::should_post_class_load()) {
1528 JvmtiExport::post_class_load(THREAD, k);
1529 }
1530 post_class_define_event(k, loader_data);
1531 }
1532
1533 // Support parallel classloading
1534 // All parallel class loaders, including bootstrap classloader
1535 // lock a placeholder entry for this class/class_loader pair
1536 // to allow parallel defines of different classes for this class loader
1537 // With AllowParallelDefine flag==true, in case they do not synchronize around
1538 // FindLoadedClass/DefineClass, calls, we check for parallel
1539 // loading for them, wait if a defineClass is in progress
1540 // and return the initial requestor's results
1541 // This flag does not apply to the bootstrap classloader.
1542 // With AllowParallelDefine flag==false, call through to define_instance_class
1543 // which will throw LinkageError: duplicate class definition.
1544 // False is the requested default.
1545 // For better performance, the class loaders should synchronize
1546 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1547 // potentially waste time reading and parsing the bytestream.
1548 // Note: VM callers should ensure consistency of k/class_name,class_loader
1549 // Be careful when modifying this code: once you have run
1550 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1551 // you need to find_and_remove it before returning.
1552 // So be careful to not exit with a CHECK_ macro between these calls.
1553 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1554 InstanceKlass* k, TRAPS) {
1555
1556 Symbol* name_h = k->name(); // passed in class_name may be null
1557 ClassLoaderData* loader_data = class_loader_data(class_loader);
1558 Dictionary* dictionary = loader_data->dictionary();
1559
1560 unsigned int name_hash = dictionary->compute_hash(name_h);
1561
1562 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1563 {
1564 MutexLocker mu(THREAD, SystemDictionary_lock);
1565 // First check if class already defined
1566 if (is_parallelDefine(class_loader)) {
1567 InstanceKlass* check = dictionary->find_class(name_hash, name_h);
1568 if (check != NULL) {
1569 return check;
1570 }
1571 }
1572
1573 // Acquire define token for this class/classloader
1574 assert(placeholders()->compute_hash(name_h) == name_hash, "they're the same hashcode");
1575 PlaceholderEntry* probe = placeholders()->find_and_add(name_hash, name_h, loader_data,
1576 PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1577 // Wait if another thread defining in parallel
1578 // All threads wait - even those that will throw duplicate class: otherwise
1579 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1580 // if other thread has not finished updating dictionary
1581 while (probe->definer() != NULL) {
1582 SystemDictionary_lock->wait();
1583 }
1584 // Only special cases allow parallel defines and can use other thread's results
1585 // Other cases fall through, and may run into duplicate defines
1586 // caught by finding an entry in the SystemDictionary
1587 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1588 InstanceKlass* ik = probe->instance_klass();
1589 placeholders()->find_and_remove(name_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1590 SystemDictionary_lock->notify_all();
1591 #ifdef ASSERT
1592 InstanceKlass* check = dictionary->find_class(name_hash, name_h);
1593 assert(check != NULL, "definer missed recording success");
1594 #endif
1595 return ik;
1596 } else {
1597 // This thread will define the class (even if earlier thread tried and had an error)
1598 probe->set_definer(THREAD);
1599 }
1600 }
1601
1602 define_instance_class(k, class_loader, THREAD);
1603
1604 // definer must notify any waiting threads
1605 {
1606 MutexLocker mu(THREAD, SystemDictionary_lock);
1607 PlaceholderEntry* probe = placeholders()->get_entry(name_hash, name_h, loader_data);
1608 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1609 if (!HAS_PENDING_EXCEPTION) {
1610 probe->set_instance_klass(k);
1611 }
1612 probe->set_definer(NULL);
1613 placeholders()->find_and_remove(name_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1614 SystemDictionary_lock->notify_all();
1615 }
1616
1617 return HAS_PENDING_EXCEPTION ? NULL : k;
1618 }
1619
1620 // If a class loader supports parallel classloading handle parallel define requests.
1621 // find_or_define_instance_class may return a different InstanceKlass
1622 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1623 InstanceKlass* k, TRAPS) {
1624 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1625 // Clean up original InstanceKlass if duplicate or error
1626 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1627 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1628 assert(defined_k != NULL, "Should have a klass if there's no exception");
1629 k->class_loader_data()->add_to_deallocate_list(k);
1630 } else if (HAS_PENDING_EXCEPTION) {
1631 assert(defined_k == NULL, "Should not have a klass if there's an exception");
1632 k->class_loader_data()->add_to_deallocate_list(k);
1633 }
1634 return defined_k;
1635 }
1636
1637
1638 // ----------------------------------------------------------------------------
1639 // Update hierarchy. This is done before the new klass has been added to the SystemDictionary. The Compile_lock
1640 // is held, to ensure that the compiler is not using the class hierarchy, and that deoptimization will kick in
1641 // before a new class is used.
1642
1643 void SystemDictionary::add_to_hierarchy(InstanceKlass* k) {
1644 assert(k != NULL, "just checking");
1645 if (Universe::is_fully_initialized()) {
1646 assert_locked_or_safepoint(Compile_lock);
1647 }
1648
1649 k->set_init_state(InstanceKlass::loaded);
1650 // make sure init_state store is already done.
1651 // The compiler reads the hierarchy outside of the Compile_lock.
1652 // Access ordering is used to add to hierarchy.
1653
1654 // Link into hierarchy.
1655 k->append_to_sibling_list(); // add to superklass/sibling list
1656 k->process_interfaces(); // handle all "implements" declarations
1657
1658 // Now flush all code that depended on old class hierarchy.
1659 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1660 if (Universe::is_fully_initialized()) {
1661 CodeCache::flush_dependents_on(k);
1662 }
1663 }
1664
1665 // ----------------------------------------------------------------------------
1666 // GC support
1667
1668 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1669 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1670
1671 bool unloading_occurred;
1672 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1673 {
1674 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1675 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1676 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1677 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1678 if (unloading_occurred) {
1679 MutexLocker ml2(is_concurrent ? Module_lock : NULL);
1680 JFR_ONLY(Jfr::on_unloading_classes();)
1681 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1682 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
1683 ClassLoaderDataGraph::clean_module_and_package_info();
1684 constraints()->purge_loader_constraints();
1685 resolution_errors()->purge_resolution_errors();
1686 }
1687 }
1688
1689 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1690
1691 if (unloading_occurred) {
1692 SymbolTable::trigger_cleanup();
1693
1694 if (java_lang_System::allow_security_manager()) {
1695 // Oops referenced by the protection domain cache table may get unreachable independently
1696 // of the class loader (eg. cached protection domain oops). So we need to
1697 // explicitly unlink them here.
1698 // All protection domain oops are linked to the caller class, so if nothing
1699 // unloads, this is not needed.
1700 _pd_cache_table->trigger_cleanup();
1701 } else {
1702 assert(_pd_cache_table->number_of_entries() == 0, "should be empty");
1703 }
1704
1705 MutexLocker ml(is_concurrent ? ClassInitError_lock : NULL);
1706 InstanceKlass::clean_initialization_error_table();
1707 }
1708
1709 return unloading_occurred;
1710 }
1711
1712 void SystemDictionary::methods_do(void f(Method*)) {
1713 // Walk methods in loaded classes
1714 MutexLocker ml(ClassLoaderDataGraph_lock);
1715 ClassLoaderDataGraph::methods_do(f);
1716 // Walk method handle intrinsics
1717 invoke_method_table()->methods_do(f);
1718 }
1719
1720 // ----------------------------------------------------------------------------
1721 // Initialization
1722
1723 void SystemDictionary::initialize(TRAPS) {
1724 // Allocate arrays
1725 _placeholders = new PlaceholderTable(_placeholder_table_size);
1726 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1727 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1728 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1729 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1730
1731 // Resolve basic classes
1732 vmClasses::resolve_all(CHECK);
1733 // Resolve classes used by archived heap objects
1734 if (UseSharedSpaces) {
1735 HeapShared::resolve_classes(THREAD);
1736 }
1737 }
1738
1739 // Constraints on class loaders. The details of the algorithm can be
1740 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1741 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1742 // that the dictionary needs to maintain a set of contraints that
1743 // must be satisfied by all classes in the dictionary.
1744 // if defining is true, then LinkageError if already in dictionary
1745 // if initiating loader, then ok if InstanceKlass matches existing entry
1746
1747 void SystemDictionary::check_constraints(unsigned int name_hash,
1748 InstanceKlass* k,
1749 Handle class_loader,
1750 bool defining,
1751 TRAPS) {
1752 ResourceMark rm(THREAD);
1753 stringStream ss;
1754 bool throwException = false;
1755
1756 {
1757 Symbol *name = k->name();
1758 ClassLoaderData *loader_data = class_loader_data(class_loader);
1759
1760 MutexLocker mu(THREAD, SystemDictionary_lock);
1761
1762 InstanceKlass* check = loader_data->dictionary()->find_class(name_hash, name);
1763 if (check != NULL) {
1764 // If different InstanceKlass - duplicate class definition,
1765 // else - ok, class loaded by a different thread in parallel.
1766 // We should only have found it if it was done loading and ok to use.
1767
1768 if ((defining == true) || (k != check)) {
1769 throwException = true;
1770 ss.print("loader %s", loader_data->loader_name_and_id());
1771 ss.print(" attempted duplicate %s definition for %s. (%s)",
1772 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1773 } else {
1774 return;
1775 }
1776 }
1777
1778 if (throwException == false) {
1779 if (constraints()->check_or_update(k, class_loader, name) == false) {
1780 throwException = true;
1781 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1782 ss.print(" wants to load %s %s.",
1783 k->external_kind(), k->external_name());
1784 Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
1785 if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
1786 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1787 existing_klass->external_kind(),
1788 existing_klass->class_loader_data()->loader_name_and_id(),
1789 existing_klass->class_in_module_of_loader(false, true));
1790 } else {
1791 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1792 }
1793 }
1794 }
1795 }
1796
1797 // Throw error now if needed (cannot throw while holding
1798 // SystemDictionary_lock because of rank ordering)
1799 if (throwException == true) {
1800 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1801 }
1802 }
1803
1804 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1805 // have been called.
1806 void SystemDictionary::update_dictionary(unsigned int hash,
1807 InstanceKlass* k,
1808 Handle class_loader) {
1809 // Compile_lock prevents systemDictionary updates during compilations
1810 assert_locked_or_safepoint(Compile_lock);
1811 Symbol* name = k->name();
1812 ClassLoaderData *loader_data = class_loader_data(class_loader);
1813
1814 {
1815 MutexLocker mu1(SystemDictionary_lock);
1816
1817 // Make a new dictionary entry.
1818 Dictionary* dictionary = loader_data->dictionary();
1819 InstanceKlass* sd_check = dictionary->find_class(hash, name);
1820 if (sd_check == NULL) {
1821 dictionary->add_klass(hash, name, k);
1822 }
1823 SystemDictionary_lock->notify_all();
1824 }
1825 }
1826
1827
1828 // Try to find a class name using the loader constraints. The
1829 // loader constraints might know about a class that isn't fully loaded
1830 // yet and these will be ignored.
1831 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1832 Thread* current, Symbol* class_name, Handle class_loader) {
1833
1834 // First see if it has been loaded directly.
1835 // Force the protection domain to be null. (This removes protection checks.)
1836 Handle no_protection_domain;
1837 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
1838 no_protection_domain);
1839 if (klass != NULL)
1840 return klass;
1841
1842 // Now look to see if it has been loaded elsewhere, and is subject to
1843 // a loader constraint that would require this loader to return the
1844 // klass that is already loaded.
1845 if (Signature::is_array(class_name)) {
1846 // For array classes, their Klass*s are not kept in the
1847 // constraint table. The element Klass*s are.
1848 SignatureStream ss(class_name, false);
1849 int ndims = ss.skip_array_prefix(); // skip all '['s
1850 BasicType t = ss.type();
1851 if (t != T_OBJECT && t != T_PRIMITIVE_OBJECT) {
1852 klass = Universe::typeArrayKlassObj(t);
1853 } else {
1854 MutexLocker mu(current, SystemDictionary_lock);
1855 klass = constraints()->find_constrained_klass(ss.as_symbol(), class_loader);
1856 }
1857 // If element class already loaded, allocate array klass
1858 if (klass != NULL) {
1859 if (class_name->is_Q_array_signature()) {
1860 klass = InlineKlass::cast(klass)->value_array_klass_or_null(ndims);
1861 } else {
1862 klass = klass->array_klass_or_null(ndims);
1863 }
1864 }
1865 } else {
1866 MutexLocker mu(current, SystemDictionary_lock);
1867 // Non-array classes are easy: simply check the constraint table.
1868 klass = constraints()->find_constrained_klass(class_name, class_loader);
1869 }
1870
1871 return klass;
1872 }
1873
1874 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1875 Klass* klass_being_linked,
1876 Handle class_loader1,
1877 Handle class_loader2) {
1878 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1879 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1880
1881 Symbol* constraint_name = NULL;
1882
1883 if (!Signature::is_array(class_name)) {
1884 constraint_name = class_name;
1885 } else {
1886 // For array classes, their Klass*s are not kept in the
1887 // constraint table. The element classes are.
1888 SignatureStream ss(class_name, false);
1889 ss.skip_array_prefix(); // skip all '['s
1890 if (!ss.has_envelope()) {
1891 return true; // primitive types always pass
1892 }
1893 constraint_name = ss.as_symbol();
1894 // Increment refcount to keep constraint_name alive after
1895 // SignatureStream is destructed. It will be decremented below
1896 // before returning.
1897 constraint_name->increment_refcount();
1898 }
1899
1900 Dictionary* dictionary1 = loader_data1->dictionary();
1901 unsigned int name_hash1 = dictionary1->compute_hash(constraint_name);
1902
1903 Dictionary* dictionary2 = loader_data2->dictionary();
1904 unsigned int name_hash2 = dictionary2->compute_hash(constraint_name);
1905
1906 {
1907 MutexLocker mu_s(SystemDictionary_lock);
1908 InstanceKlass* klass1 = dictionary1->find_class(name_hash1, constraint_name);
1909 InstanceKlass* klass2 = dictionary2->find_class(name_hash2, constraint_name);
1910 bool result = constraints()->add_entry(constraint_name, klass1, class_loader1,
1911 klass2, class_loader2);
1912 #if INCLUDE_CDS
1913 if (Arguments::is_dumping_archive() && klass_being_linked != NULL &&
1914 !klass_being_linked->is_shared()) {
1915 SystemDictionaryShared::record_linking_constraint(constraint_name,
1916 InstanceKlass::cast(klass_being_linked),
1917 class_loader1, class_loader2);
1918 }
1919 #endif // INCLUDE_CDS
1920 if (Signature::is_array(class_name)) {
1921 constraint_name->decrement_refcount();
1922 }
1923 return result;
1924 }
1925 }
1926
1927 // Add entry to resolution error table to record the error when the first
1928 // attempt to resolve a reference to a class has failed.
1929 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1930 Symbol* error, Symbol* message,
1931 Symbol* cause, Symbol* cause_msg) {
1932 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1933 int index = resolution_errors()->hash_to_index(hash);
1934 {
1935 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1936 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
1937 if (entry == NULL) {
1938 resolution_errors()->add_entry(index, hash, pool, which, error, message, cause, cause_msg);
1939 }
1940 }
1941 }
1942
1943 // Delete a resolution error for RedefineClasses for a constant pool is going away
1944 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1945 resolution_errors()->delete_entry(pool);
1946 }
1947
1948 // Lookup resolution error table. Returns error if found, otherwise NULL.
1949 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1950 Symbol** message, Symbol** cause, Symbol** cause_msg) {
1951 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1952 int index = resolution_errors()->hash_to_index(hash);
1953 {
1954 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1955 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
1956 if (entry != NULL) {
1957 *message = entry->message();
1958 *cause = entry->cause();
1959 *cause_msg = entry->cause_msg();
1960 return entry->error();
1961 } else {
1962 return NULL;
1963 }
1964 }
1965 }
1966
1967 // Add an entry to resolution error table to record an error in resolving or
1968 // validating a nest host. This is used to construct informative error
1969 // messages when IllegalAccessError's occur. If an entry already exists it will
1970 // be updated with the nest host error message.
1971 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1972 int which,
1973 const char* message) {
1974 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1975 int index = resolution_errors()->hash_to_index(hash);
1976 {
1977 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1978 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
1979 if (entry != NULL && entry->nest_host_error() == NULL) {
1980 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1981 // still want to add the error message for the higher-level access checks to report. We should
1982 // only reach here under the same error condition, so we can ignore the potential race with setting
1983 // the message. If we see it is already set then we can ignore it.
1984 entry->set_nest_host_error(message);
1985 } else {
1986 resolution_errors()->add_entry(index, hash, pool, which, message);
1987 }
1988 }
1989 }
1990
1991 // Lookup any nest host error
1992 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1993 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1994 int index = resolution_errors()->hash_to_index(hash);
1995 {
1996 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1997 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
1998 if (entry != NULL) {
1999 return entry->nest_host_error();
2000 } else {
2001 return NULL;
2002 }
2003 }
2004 }
2005
2006
2007 // Signature constraints ensure that callers and callees agree about
2008 // the meaning of type names in their signatures. This routine is the
2009 // intake for constraints. It collects them from several places:
2010 //
2011 // * LinkResolver::resolve_method (if check_access is true) requires
2012 // that the resolving class (the caller) and the defining class of
2013 // the resolved method (the callee) agree on each type in the
2014 // method's signature.
2015 //
2016 // * LinkResolver::resolve_interface_method performs exactly the same
2017 // checks.
2018 //
2019 // * LinkResolver::resolve_field requires that the constant pool
2020 // attempting to link to a field agree with the field's defining
2021 // class about the type of the field signature.
2022 //
2023 // * klassVtable::initialize_vtable requires that, when a class
2024 // overrides a vtable entry allocated by a superclass, that the
2025 // overriding method (i.e., the callee) agree with the superclass
2026 // on each type in the method's signature.
2027 //
2028 // * klassItable::initialize_itable requires that, when a class fills
2029 // in its itables, for each non-abstract method installed in an
2030 // itable, the method (i.e., the callee) agree with the interface
2031 // on each type in the method's signature.
2032 //
2033 // All those methods have a boolean (check_access, checkconstraints)
2034 // which turns off the checks. This is used from specialized contexts
2035 // such as bootstrapping, dumping, and debugging.
2036 //
2037 // No direct constraint is placed between the class and its
2038 // supertypes. Constraints are only placed along linked relations
2039 // between callers and callees. When a method overrides or implements
2040 // an abstract method in a supertype (superclass or interface), the
2041 // constraints are placed as if the supertype were the caller to the
2042 // overriding method. (This works well, since callers to the
2043 // supertype have already established agreement between themselves and
2044 // the supertype.) As a result of all this, a class can disagree with
2045 // its supertype about the meaning of a type name, as long as that
2046 // class neither calls a relevant method of the supertype, nor is
2047 // called (perhaps via an override) from the supertype.
2048 //
2049 //
2050 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
2051 //
2052 // Make sure all class components (including arrays) in the given
2053 // signature will be resolved to the same class in both loaders.
2054 // Returns the name of the type that failed a loader constraint check, or
2055 // NULL if no constraint failed. No exception except OOME is thrown.
2056 // Arrays are not added to the loader constraint table, their elements are.
2057 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2058 Klass* klass_being_linked,
2059 Handle loader1, Handle loader2,
2060 bool is_method) {
2061 // Nothing to do if loaders are the same.
2062 if (loader1() == loader2()) {
2063 return NULL;
2064 }
2065
2066 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2067 if (ss.is_reference()) {
2068 Symbol* sig = ss.as_symbol();
2069 // Note: In the future, if template-like types can take
2070 // arguments, we will want to recognize them and dig out class
2071 // names hiding inside the argument lists.
2072 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2073 return sig;
2074 }
2075 }
2076 }
2077 return NULL;
2078 }
2079
2080 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2081 Symbol* signature,
2082 TRAPS) {
2083 methodHandle empty;
2084 const int iid_as_int = vmIntrinsics::as_int(iid);
2085 assert(MethodHandles::is_signature_polymorphic(iid) &&
2086 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2087 iid != vmIntrinsics::_invokeGeneric,
2088 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2089
2090 unsigned int hash = invoke_method_table()->compute_hash(signature, iid_as_int);
2091 int index = invoke_method_table()->hash_to_index(hash);
2092 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid_as_int);
2093 methodHandle m;
2094 if (spe == NULL || spe->method() == NULL) {
2095 spe = NULL;
2096 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2097 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
2098 if (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative) {
2099 // Generate a compiled form of the MH intrinsic.
2100 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2101 AdapterHandlerLibrary::create_native_wrapper(m);
2102 // Check if have the compiled code.
2103 if (!m->has_compiled_code()) {
2104 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2105 "Out of space in CodeCache for method handle intrinsic");
2106 }
2107 }
2108 // Now grab the lock. We might have to throw away the new method,
2109 // if a racing thread has managed to install one at the same time.
2110 {
2111 MutexLocker ml(THREAD, SystemDictionary_lock);
2112 spe = invoke_method_table()->find_entry(index, hash, signature, iid_as_int);
2113 if (spe == NULL)
2114 spe = invoke_method_table()->add_entry(index, hash, signature, iid_as_int);
2115 if (spe->method() == NULL)
2116 spe->set_method(m());
2117 }
2118 }
2119
2120 assert(spe != NULL && spe->method() != NULL, "");
2121 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2122 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2123 "MH intrinsic invariant");
2124 return spe->method();
2125 }
2126
2127 // Helper for unpacking the return value from linkMethod and linkCallSite.
2128 static Method* unpack_method_and_appendix(Handle mname,
2129 Klass* accessing_klass,
2130 objArrayHandle appendix_box,
2131 Handle* appendix_result,
2132 TRAPS) {
2133 if (mname.not_null()) {
2134 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2135 if (m != NULL) {
2136 oop appendix = appendix_box->obj_at(0);
2137 LogTarget(Info, methodhandles) lt;
2138 if (lt.develop_is_enabled()) {
2139 ResourceMark rm(THREAD);
2140 LogStream ls(lt);
2141 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2142 m->print_on(&ls);
2143 if (appendix != NULL) { ls.print("appendix = "); appendix->print_on(&ls); }
2144 ls.cr();
2145 }
2146
2147 (*appendix_result) = Handle(THREAD, appendix);
2148 // the target is stored in the cpCache and if a reference to this
2149 // MemberName is dropped we need a way to make sure the
2150 // class_loader containing this method is kept alive.
2151 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2152 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2153 this_key->record_dependency(m->method_holder());
2154 return mh();
2155 }
2156 }
2157 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2158 }
2159
2160 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2161 Symbol* name,
2162 Symbol* signature,
2163 Klass* accessing_klass,
2164 Handle* appendix_result,
2165 TRAPS) {
2166 assert(THREAD->can_call_java() ,"");
2167 Handle method_type =
2168 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2169
2170 int ref_kind = JVM_REF_invokeVirtual;
2171 oop name_oop = StringTable::intern(name, CHECK_NULL);
2172 Handle name_str (THREAD, name_oop);
2173 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2174 assert(appendix_box->obj_at(0) == NULL, "");
2175
2176 // This should not happen. JDK code should take care of that.
2177 if (accessing_klass == NULL || method_type.is_null()) {
2178 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2179 }
2180
2181 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2182 JavaCallArguments args;
2183 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2184 args.push_int(ref_kind);
2185 args.push_oop(Handle(THREAD, klass->java_mirror()));
2186 args.push_oop(name_str);
2187 args.push_oop(method_type);
2188 args.push_oop(appendix_box);
2189 JavaValue result(T_OBJECT);
2190 JavaCalls::call_static(&result,
2191 vmClasses::MethodHandleNatives_klass(),
2192 vmSymbols::linkMethod_name(),
2193 vmSymbols::linkMethod_signature(),
2194 &args, CHECK_NULL);
2195 Handle mname(THREAD, result.get_oop());
2196 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2197 }
2198
2199 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2200 // We must ensure that all class loaders everywhere will reach this class, for any client.
2201 // This is a safe bet for public classes in java.lang, such as Object and String.
2202 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2203 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2204 static bool is_always_visible_class(oop mirror) {
2205 Klass* klass = java_lang_Class::as_Klass(mirror);
2206 if (klass->is_objArray_klass()) {
2207 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2208 }
2209 if (klass->is_typeArray_klass()) {
2210 return true; // primitive array
2211 }
2212 assert(klass->is_instance_klass(), "%s", klass->external_name());
2213 return klass->is_public() &&
2214 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2215 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2216 }
2217
2218 // Find or construct the Java mirror (java.lang.Class instance) for
2219 // the given field type signature, as interpreted relative to the
2220 // given class loader. Handles primitives, void, references, arrays,
2221 // and all other reflectable types, except method types.
2222 // N.B. Code in reflection should use this entry point.
2223 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2224 Klass* accessing_klass,
2225 Handle class_loader,
2226 Handle protection_domain,
2227 SignatureStream::FailureMode failure_mode,
2228 TRAPS) {
2229 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2230 "one or the other, or perhaps neither");
2231
2232 // What we have here must be a valid field descriptor,
2233 // and all valid field descriptors are supported.
2234 // Produce the same java.lang.Class that reflection reports.
2235 if (accessing_klass != NULL) {
2236 class_loader = Handle(THREAD, accessing_klass->class_loader());
2237 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2238 }
2239 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2240 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2241 if (mirror_oop == NULL) {
2242 return Handle(); // report failure this way
2243 }
2244 Handle mirror(THREAD, mirror_oop);
2245
2246 if (accessing_klass != NULL) {
2247 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2248 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2249 if (sel_klass != NULL) {
2250 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2251 }
2252 }
2253 return mirror;
2254 }
2255
2256
2257 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2258 // signature, as interpreted relative to the given class loader.
2259 // Because of class loader constraints, all method handle usage must be
2260 // consistent with this loader.
2261 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2262 Klass* accessing_klass,
2263 TRAPS) {
2264 Handle empty;
2265 int null_iid = vmIntrinsics::as_int(vmIntrinsics::_none); // distinct from all method handle invoker intrinsics
2266 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2267 int index = invoke_method_table()->hash_to_index(hash);
2268 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2269 if (spe != NULL && spe->method_type() != NULL) {
2270 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2271 return Handle(THREAD, spe->method_type());
2272 } else if (!THREAD->can_call_java()) {
2273 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2274 return Handle(); // do not attempt from within compiler, unless it was cached
2275 }
2276
2277 Handle class_loader, protection_domain;
2278 if (accessing_klass != NULL) {
2279 class_loader = Handle(THREAD, accessing_klass->class_loader());
2280 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2281 }
2282 bool can_be_cached = true;
2283 int npts = ArgumentCount(signature).size();
2284 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2285 int arg = 0;
2286 Handle rt; // the return type from the signature
2287 ResourceMark rm(THREAD);
2288 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2289 oop mirror = NULL;
2290 if (can_be_cached) {
2291 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2292 mirror = ss.as_java_mirror(Handle(), Handle(),
2293 SignatureStream::ReturnNull, CHECK_(empty));
2294 if (mirror == NULL || (ss.is_reference() && !is_always_visible_class(mirror))) {
2295 // Fall back to accessing_klass context.
2296 can_be_cached = false;
2297 }
2298 }
2299 if (!can_be_cached) {
2300 // Resolve, throwing a real error if it doesn't work.
2301 mirror = ss.as_java_mirror(class_loader, protection_domain,
2302 SignatureStream::NCDFError, CHECK_(empty));
2303 }
2304 assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
2305 if (ss.at_return_type())
2306 rt = Handle(THREAD, mirror);
2307 else
2308 pts->obj_at_put(arg++, mirror);
2309
2310 // Check accessibility.
2311 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2312 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2313 mirror = NULL; // safety
2314 // Emulate ConstantPool::verify_constant_pool_resolve.
2315 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2316 }
2317 }
2318 assert(arg == npts, "");
2319
2320 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2321 JavaCallArguments args(Handle(THREAD, rt()));
2322 args.push_oop(pts);
2323 JavaValue result(T_OBJECT);
2324 JavaCalls::call_static(&result,
2325 vmClasses::MethodHandleNatives_klass(),
2326 vmSymbols::findMethodHandleType_name(),
2327 vmSymbols::findMethodHandleType_signature(),
2328 &args, CHECK_(empty));
2329 Handle method_type(THREAD, result.get_oop());
2330
2331 if (can_be_cached) {
2332 // We can cache this MethodType inside the JVM.
2333 MutexLocker ml(THREAD, SystemDictionary_lock);
2334 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2335 if (spe == NULL)
2336 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2337 if (spe->method_type() == NULL) {
2338 spe->set_method_type(method_type());
2339 }
2340 }
2341
2342 // report back to the caller with the MethodType
2343 return method_type;
2344 }
2345
2346 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2347 Klass* accessing_klass,
2348 TRAPS) {
2349 Handle empty;
2350 ResourceMark rm(THREAD);
2351 SignatureStream ss(signature, /*is_method=*/ false);
2352 if (!ss.is_done()) {
2353 Handle class_loader, protection_domain;
2354 if (accessing_klass != NULL) {
2355 class_loader = Handle(THREAD, accessing_klass->class_loader());
2356 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2357 }
2358 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2359 ss.next();
2360 if (ss.is_done()) {
2361 return Handle(THREAD, mirror);
2362 }
2363 }
2364 return empty;
2365 }
2366
2367 // Ask Java code to find or construct a method handle constant.
2368 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2369 int ref_kind, //e.g., JVM_REF_invokeVirtual
2370 Klass* callee,
2371 Symbol* name,
2372 Symbol* signature,
2373 TRAPS) {
2374 Handle empty;
2375 if (caller == NULL) {
2376 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2377 }
2378 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2379 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2380
2381 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2382 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2383 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2384 java_lang_invoke_MemberName::set_name (mname(), name_str());
2385 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2386 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2387
2388 if (ref_kind == JVM_REF_invokeVirtual &&
2389 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2390 // Skip resolution for public signature polymorphic methods such as
2391 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2392 // They require appendix argument which MemberName resolution doesn't handle.
2393 // There's special logic on JDK side to handle them
2394 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2395 } else {
2396 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2397 }
2398
2399 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2400 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2401
2402 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2403 JavaCallArguments args;
2404 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2405 args.push_int(ref_kind);
2406 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2407 args.push_oop(name_str);
2408 args.push_oop(type);
2409 JavaValue result(T_OBJECT);
2410 JavaCalls::call_static(&result,
2411 vmClasses::MethodHandleNatives_klass(),
2412 vmSymbols::linkMethodHandleConstant_name(),
2413 vmSymbols::linkMethodHandleConstant_signature(),
2414 &args, CHECK_(empty));
2415 return Handle(THREAD, result.get_oop());
2416 }
2417
2418 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2419 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2420 // with linkage results being stored back into the bootstrap specifier.
2421 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2422 // Resolve the bootstrap specifier, its name, type, and static arguments
2423 bootstrap_specifier.resolve_bsm(CHECK);
2424
2425 // This should not happen. JDK code should take care of that.
2426 if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2427 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2428 }
2429
2430 bool is_indy = bootstrap_specifier.is_method_call();
2431 objArrayHandle appendix_box;
2432 if (is_indy) {
2433 // Some method calls may require an appendix argument. Arrange to receive it.
2434 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2435 assert(appendix_box->obj_at(0) == NULL, "");
2436 }
2437
2438 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2439 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2440 JavaCallArguments args;
2441 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2442 args.push_oop(bootstrap_specifier.bsm());
2443 args.push_oop(bootstrap_specifier.name_arg());
2444 args.push_oop(bootstrap_specifier.type_arg());
2445 args.push_oop(bootstrap_specifier.arg_values());
2446 if (is_indy) {
2447 args.push_oop(appendix_box);
2448 }
2449 JavaValue result(T_OBJECT);
2450 JavaCalls::call_static(&result,
2451 vmClasses::MethodHandleNatives_klass(),
2452 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2453 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2454 &args, CHECK);
2455
2456 Handle value(THREAD, result.get_oop());
2457 if (is_indy) {
2458 Handle appendix;
2459 Method* method = unpack_method_and_appendix(value,
2460 bootstrap_specifier.caller(),
2461 appendix_box,
2462 &appendix, CHECK);
2463 methodHandle mh(THREAD, method);
2464 bootstrap_specifier.set_resolved_method(mh, appendix);
2465 } else {
2466 bootstrap_specifier.set_resolved_value(value);
2467 }
2468
2469 // sanity check
2470 assert(bootstrap_specifier.is_resolved() ||
2471 (bootstrap_specifier.is_method_call() &&
2472 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2473 }
2474
2475
2476 ClassLoaderData* SystemDictionary::class_loader_data(Handle class_loader) {
2477 return ClassLoaderData::class_loader_data(class_loader());
2478 }
2479
2480 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2481 assert(m != NULL, "Unexpected NULL Method*");
2482 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2483 }
2484
2485 // ----------------------------------------------------------------------------
2486
2487 void SystemDictionary::print_on(outputStream *st) {
2488 CDS_ONLY(SystemDictionaryShared::print_on(st));
2489 GCMutexLocker mu(SystemDictionary_lock);
2490
2491 ClassLoaderDataGraph::print_dictionary(st);
2492
2493 // Placeholders
2494 placeholders()->print_on(st);
2495 st->cr();
2496
2497 // loader constraints - print under SD_lock
2498 constraints()->print_on(st);
2499 st->cr();
2500
2501 _pd_cache_table->print_on(st);
2502 st->cr();
2503 }
2504
2505 void SystemDictionary::print() { print_on(tty); }
2506
2507 void SystemDictionary::verify() {
2508 guarantee(constraints() != NULL,
2509 "Verify of loader constraints failed");
2510 guarantee(placeholders()->number_of_entries() >= 0,
2511 "Verify of placeholders failed");
2512
2513 GCMutexLocker mu(SystemDictionary_lock);
2514
2515 // Verify dictionary
2516 ClassLoaderDataGraph::verify_dictionary();
2517
2518 placeholders()->verify();
2519
2520 // Verify constraint table
2521 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2522 constraints()->verify(placeholders());
2523
2524 _pd_cache_table->verify();
2525 }
2526
2527 void SystemDictionary::dump(outputStream *st, bool verbose) {
2528 assert_locked_or_safepoint(SystemDictionary_lock);
2529 if (verbose) {
2530 print_on(st);
2531 } else {
2532 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2533 ClassLoaderDataGraph::print_table_statistics(st);
2534 placeholders()->print_table_statistics(st, "Placeholder Table");
2535 constraints()->print_table_statistics(st, "LoaderConstraints Table");
2536 pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table");
2537 }
2538 }
2539
2540 TableStatistics SystemDictionary::placeholders_statistics() {
2541 MutexLocker ml(SystemDictionary_lock);
2542 return placeholders()->statistics_calculate();
2543 }
2544
2545 TableStatistics SystemDictionary::loader_constraints_statistics() {
2546 MutexLocker ml(SystemDictionary_lock);
2547 return constraints()->statistics_calculate();
2548 }
2549
2550 TableStatistics SystemDictionary::protection_domain_cache_statistics() {
2551 MutexLocker ml(SystemDictionary_lock);
2552 return pd_cache_table()->statistics_calculate();
2553 }
2554
2555 // Utility for dumping dictionaries.
2556 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2557 DCmdWithParser(output, heap),
2558 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2559 "BOOLEAN", false, "false") {
2560 _dcmdparser.add_dcmd_option(&_verbose);
2561 }
2562
2563 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2564 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2565 _verbose.value());
2566 VMThread::execute(&dumper);
2567 }