1 /*
2 * Copyright (c) 1997, 2020, 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 "aot/aotLoader.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/dictionary.hpp"
35 #include "classfile/javaClasses.inline.hpp"
36 #include "classfile/klassFactory.hpp"
37 #include "classfile/loaderConstraints.hpp"
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/protectionDomainCache.hpp"
41 #include "classfile/resolutionErrors.hpp"
42 #include "classfile/stringTable.hpp"
43 #include "classfile/symbolTable.hpp"
44 #include "classfile/systemDictionary.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "code/codeCache.hpp"
47 #include "compiler/compileBroker.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "gc/shared/oopStorage.inline.hpp"
50 #include "gc/shared/oopStorageSet.hpp"
51 #include "interpreter/bytecodeStream.hpp"
52 #include "interpreter/interpreter.hpp"
53 #include "jfr/jfrEvents.hpp"
54 #include "logging/log.hpp"
55 #include "logging/logStream.hpp"
56 #include "memory/filemap.hpp"
57 #include "memory/heapShared.hpp"
58 #include "memory/metaspaceClosure.hpp"
59 #include "memory/oopFactory.hpp"
60 #include "memory/resourceArea.hpp"
61 #include "memory/universe.hpp"
62 #include "oops/access.inline.hpp"
63 #include "oops/instanceKlass.hpp"
64 #include "oops/instanceRefKlass.hpp"
65 #include "oops/klass.inline.hpp"
66 #include "oops/method.inline.hpp"
67 #include "oops/methodData.hpp"
68 #include "oops/objArrayKlass.hpp"
69 #include "oops/objArrayOop.inline.hpp"
70 #include "oops/oop.inline.hpp"
71 #include "oops/symbol.hpp"
72 #include "oops/typeArrayKlass.hpp"
73 #include "prims/jvmtiExport.hpp"
74 #include "prims/methodHandles.hpp"
75 #include "runtime/arguments.hpp"
76 #include "runtime/biasedLocking.hpp"
77 #include "runtime/handles.inline.hpp"
78 #include "runtime/java.hpp"
79 #include "runtime/javaCalls.hpp"
80 #include "runtime/mutexLocker.hpp"
81 #include "runtime/sharedRuntime.hpp"
82 #include "runtime/signature.hpp"
83 #include "services/classLoadingService.hpp"
84 #include "services/diagnosticCommand.hpp"
85 #include "services/threadService.hpp"
86 #include "utilities/macros.hpp"
87 #if INCLUDE_CDS
88 #include "classfile/systemDictionaryShared.hpp"
89 #endif
90 #if INCLUDE_JFR
91 #include "jfr/jfr.hpp"
92 #endif
93
94 PlaceholderTable* SystemDictionary::_placeholders = NULL;
95 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
96 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
97 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
98 ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
99
100 oop SystemDictionary::_system_loader_lock_obj = NULL;
101
102 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
103 = { NULL /*, NULL...*/ };
104
105 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
106
107 oop SystemDictionary::_java_system_loader = NULL;
108 oop SystemDictionary::_java_platform_loader = NULL;
109
110 // Default ProtectionDomainCacheSize value
111
112 const int defaultProtectionDomainCacheSize = 1009;
113
114 // ----------------------------------------------------------------------------
115 // Java-level SystemLoader and PlatformLoader
116
117 oop SystemDictionary::java_system_loader() {
118 return _java_system_loader;
119 }
120
121 oop SystemDictionary::java_platform_loader() {
122 return _java_platform_loader;
123 }
124
125 void SystemDictionary::compute_java_loaders(TRAPS) {
126 JavaValue result(T_OBJECT);
127 InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
128 JavaCalls::call_static(&result,
129 class_loader_klass,
130 vmSymbols::getSystemClassLoader_name(),
131 vmSymbols::void_classloader_signature(),
132 CHECK);
133
134 _java_system_loader = (oop)result.get_jobject();
135
136 JavaCalls::call_static(&result,
137 class_loader_klass,
138 vmSymbols::getPlatformClassLoader_name(),
139 vmSymbols::void_classloader_signature(),
140 CHECK);
141
142 _java_platform_loader = (oop)result.get_jobject();
143 }
144
145 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
146 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
147 return ClassLoaderDataGraph::find_or_create(class_loader);
148 }
149
150 // ----------------------------------------------------------------------------
151 // Parallel class loading check
152
153 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
154 if (class_loader.is_null()) return true;
155 if (AlwaysLockClassLoader) return false;
156 return java_lang_ClassLoader::parallelCapable(class_loader());
157 }
158 // ----------------------------------------------------------------------------
159 // ParallelDefineClass flag does not apply to bootclass loader
160 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
161 if (class_loader.is_null()) return false;
162 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
163 return true;
164 }
165 return false;
166 }
167
168 // Returns true if the passed class loader is the builtin application class loader
169 // or a custom system class loader. A customer system class loader can be
170 // specified via -Djava.system.class.loader.
171 bool SystemDictionary::is_system_class_loader(oop class_loader) {
172 if (class_loader == NULL) {
173 return false;
174 }
175 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
176 class_loader == _java_system_loader);
177 }
178
179 // Returns true if the passed class loader is the platform class loader.
180 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
181 if (class_loader == NULL) {
182 return false;
183 }
184 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
185 }
186
187 // ----------------------------------------------------------------------------
188 // Resolving of classes
189
190 // Forwards to resolve_or_null
191
192 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
193 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
194 if (HAS_PENDING_EXCEPTION || klass == NULL) {
195 // can return a null klass
196 klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
197 }
198 return klass;
199 }
200
201 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
202 bool throw_error,
203 Klass* klass, TRAPS) {
204 if (HAS_PENDING_EXCEPTION) {
205 // If we have a pending exception we forward it to the caller, unless throw_error is true,
206 // in which case we have to check whether the pending exception is a ClassNotFoundException,
207 // and if so convert it to a NoClassDefFoundError
208 // And chain the original ClassNotFoundException
209 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
210 ResourceMark rm(THREAD);
211 assert(klass == NULL, "Should not have result with exception pending");
212 Handle e(THREAD, PENDING_EXCEPTION);
213 CLEAR_PENDING_EXCEPTION;
214 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
215 } else {
216 return NULL;
217 }
218 }
219 // Class not found, throw appropriate error or exception depending on value of throw_error
220 if (klass == NULL) {
221 ResourceMark rm(THREAD);
222 if (throw_error) {
223 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
224 } else {
225 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
226 }
227 }
228 return klass;
229 }
230
231
232 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
233 bool throw_error, TRAPS)
234 {
235 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
236 }
237
238
239 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
240
241 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
242 if (Signature::is_array(class_name)) {
243 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
244 } else {
245 return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
246 }
247 }
248
249 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
250 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
251 Handle class_loader,
252 Handle protection_domain,
253 TRAPS) {
254 assert(class_name != NULL && !Signature::is_array(class_name), "must be");
255 if (Signature::has_envelope(class_name)) {
256 ResourceMark rm(THREAD);
257 // Ignore wrapping L and ;.
258 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
259 class_name->utf8_length() - 2);
260 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
261 } else {
262 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
263 }
264 }
265
266 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
267 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
268 }
269
270 // Forwards to resolve_instance_class_or_null
271
272 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
273 Handle class_loader,
274 Handle protection_domain,
275 TRAPS) {
276 assert(Signature::is_array(class_name), "must be array");
277 ResourceMark rm(THREAD);
278 SignatureStream ss(class_name, false);
279 int ndims = ss.skip_array_prefix(); // skip all '['s
280 Klass* k = NULL;
281 BasicType t = ss.type();
282 if (ss.has_envelope()) {
283 Symbol* obj_class = ss.as_symbol();
284 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
285 class_loader,
286 protection_domain,
287 CHECK_NULL);
288 if (k != NULL) {
289 k = k->array_klass(ndims, CHECK_NULL);
290 }
291 } else {
292 k = Universe::typeArrayKlassObj(t);
293 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
294 }
295 return k;
296 }
297
298
299 // Must be called for any super-class or super-interface resolution
300 // during class definition to allow class circularity checking
301 // super-interface callers:
302 // parse_interfaces - for defineClass & jvmtiRedefineClasses
303 // super-class callers:
304 // ClassFileParser - for defineClass & jvmtiRedefineClasses
305 // load_shared_class - while loading a class from shared archive
306 // resolve_instance_class_or_null:
307 // via: handle_parallel_super_load
308 // when resolving a class that has an existing placeholder with
309 // a saved superclass [i.e. a defineClass is currently in progress]
310 // if another thread is trying to resolve the class, it must do
311 // super-class checks on its own thread to catch class circularity
312 // This last call is critical in class circularity checking for cases
313 // where classloading is delegated to different threads and the
314 // classloader lock is released.
315 // Take the case: Base->Super->Base
316 // 1. If thread T1 tries to do a defineClass of class Base
317 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
318 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
319 // so it tries to load Super
320 // 3. If we load the class internally, or user classloader uses same thread
321 // loadClassFromxxx or defineClass via parseClassFile Super ...
322 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
323 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
324 // 3.4 calls resolve_super_or_fail Base
325 // 3.5 finds T1,Base -> throws class circularity
326 //OR 4. If T2 tries to resolve Super via defineClass Super ...
327 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
328 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
329 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
330 // 4.4 finds T2, Super -> throws class circularity
331 // Must be called, even if superclass is null, since this is
332 // where the placeholder entry is created which claims this
333 // thread is loading this class/classloader.
334 // Be careful when modifying this code: once you have run
335 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
336 // you need to find_and_remove it before returning.
337 // So be careful to not exit with a CHECK_ macro betweeen these calls.
338 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
339 Symbol* super_name,
340 Handle class_loader,
341 Handle protection_domain,
342 bool is_superclass,
343 TRAPS) {
344 assert(!Signature::is_array(super_name), "invalid super class name");
345 #if INCLUDE_CDS
346 if (DumpSharedSpaces) {
347 // Special processing for handling UNREGISTERED shared classes.
348 InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
349 super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
350 if (k) {
351 return k;
352 }
353 }
354 #endif // INCLUDE_CDS
355
356 // Double-check, if child class is already loaded, just return super-class,interface
357 // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
358 // dictionary.
359 // Make sure there's a placeholder for the *child* before resolving.
360 // Used as a claim that this thread is currently loading superclass/classloader
361 // Used here for ClassCircularity checks and also for heap verification
362 // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
363 // Must check ClassCircularity before checking if super class is already loaded.
364 //
365 // We might not already have a placeholder if this child_name was
366 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
367 // the name of the class might not be known until the stream is actually
368 // parsed.
369 // Bugs 4643874, 4715493
370
371 ClassLoaderData* loader_data = class_loader_data(class_loader);
372 Dictionary* dictionary = loader_data->dictionary();
373 unsigned int d_hash = dictionary->compute_hash(child_name);
374 unsigned int p_hash = placeholders()->compute_hash(child_name);
375 int p_index = placeholders()->hash_to_index(p_hash);
376 // can't throw error holding a lock
377 bool child_already_loaded = false;
378 bool throw_circularity_error = false;
379 {
380 MutexLocker mu(THREAD, SystemDictionary_lock);
381 InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
382 InstanceKlass* quicksuperk;
383 // to support // loading: if child done loading, just return superclass
384 // if super_name, & class_loader don't match:
385 // if initial define, SD update will give LinkageError
386 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
387 // so we don't throw an exception here.
388 // see: nsk redefclass014 & java.lang.instrument Instrument032
389 if ((childk != NULL ) && (is_superclass) &&
390 ((quicksuperk = childk->java_super()) != NULL) &&
391 ((quicksuperk->name() == super_name) &&
392 (quicksuperk->class_loader() == class_loader()))) {
393 return quicksuperk;
394 } else {
395 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
396 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
397 throw_circularity_error = true;
398 }
399 }
400 if (!throw_circularity_error) {
401 // Be careful not to exit resolve_super
402 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
403 }
404 }
405 if (throw_circularity_error) {
406 ResourceMark rm(THREAD);
407 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
408 }
409
410 // java.lang.Object should have been found above
411 assert(super_name != NULL, "null super class for resolving");
412 // Resolve the super class or interface, check results on return
413 InstanceKlass* superk =
414 SystemDictionary::resolve_instance_class_or_null_helper(super_name,
415 class_loader,
416 protection_domain,
417 THREAD);
418
419 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
420 // It is no longer necessary to keep the placeholder table alive until update_dictionary
421 // or error. GC used to walk the placeholder table as strong roots.
422 // The instanceKlass is kept alive because the class loader is on the stack,
423 // which keeps the loader_data alive, as well as all instanceKlasses in
424 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
425 {
426 MutexLocker mu(THREAD, SystemDictionary_lock);
427 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
428 SystemDictionary_lock->notify_all();
429 }
430 if (HAS_PENDING_EXCEPTION || superk == NULL) {
431 // can null superk
432 Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
433 assert(k == NULL || k == superk, "must be");
434 if (k == NULL) {
435 superk = NULL;
436 }
437 }
438
439 return superk;
440 }
441
442 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
443 Handle class_loader,
444 Handle protection_domain,
445 TRAPS) {
446 // Now we have to call back to java to check if the initating class has access
447 JavaValue result(T_VOID);
448 LogTarget(Debug, protectiondomain) lt;
449 if (lt.is_enabled()) {
450 ResourceMark rm(THREAD);
451 // Print out trace information
452 LogStream ls(lt);
453 ls.print_cr("Checking package access");
454 if (class_loader() != NULL) {
455 ls.print("class loader: ");
456 class_loader()->print_value_on(&ls);
457 } else {
458 ls.print_cr("class loader: NULL");
459 }
460 if (protection_domain() != NULL) {
461 ls.print(" protection domain: ");
462 protection_domain()->print_value_on(&ls);
463 } else {
464 ls.print_cr(" protection domain: NULL");
465 }
466 ls.print(" loading: "); klass->print_value_on(&ls);
467 ls.cr();
468 }
469
470 // This handle and the class_loader handle passed in keeps this class from
471 // being unloaded through several GC points.
472 // The class_loader handle passed in is the initiating loader.
473 Handle mirror(THREAD, klass->java_mirror());
474
475 InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
476 JavaCalls::call_special(&result,
477 class_loader,
478 system_loader,
479 vmSymbols::checkPackageAccess_name(),
480 vmSymbols::class_protectiondomain_signature(),
481 mirror,
482 protection_domain,
483 THREAD);
484
485 if (HAS_PENDING_EXCEPTION) {
486 log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
487 } else {
488 log_debug(protectiondomain)("granted");
489 }
490
491 if (HAS_PENDING_EXCEPTION) return;
492
493 // If no exception has been thrown, we have validated the protection domain
494 // Insert the protection domain of the initiating class into the set.
495 {
496 ClassLoaderData* loader_data = class_loader_data(class_loader);
497 Dictionary* dictionary = loader_data->dictionary();
498
499 Symbol* kn = klass->name();
500 unsigned int d_hash = dictionary->compute_hash(kn);
501
502 MutexLocker mu(THREAD, SystemDictionary_lock);
503 int d_index = dictionary->hash_to_index(d_hash);
504 dictionary->add_protection_domain(d_index, d_hash, klass,
505 protection_domain, THREAD);
506 }
507 }
508
509 // We only get here if this thread finds that another thread
510 // has already claimed the placeholder token for the current operation,
511 // but that other thread either never owned or gave up the
512 // object lock
513 // Waits on SystemDictionary_lock to indicate placeholder table updated
514 // On return, caller must recheck placeholder table state
515 //
516 // We only get here if
517 // 1) custom classLoader, i.e. not bootstrap classloader
518 // 2) custom classLoader has broken the class loader objectLock
519 // so another thread got here in parallel
520 //
521 // lockObject must be held.
522 // Complicated dance due to lock ordering:
523 // Must first release the classloader object lock to
524 // allow initial definer to complete the class definition
525 // and to avoid deadlock
526 // Reclaim classloader lock object with same original recursion count
527 // Must release SystemDictionary_lock after notify, since
528 // class loader lock must be claimed before SystemDictionary_lock
529 // to prevent deadlocks
530 //
531 // The notify allows applications that did an untimed wait() on
532 // the classloader object lock to not hang.
533 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
534 assert_lock_strong(SystemDictionary_lock);
535
536 bool calledholdinglock
537 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
538 assert(calledholdinglock,"must hold lock for notify");
539 assert((lockObject() != _system_loader_lock_obj && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
540 ObjectSynchronizer::notifyall(lockObject, THREAD);
541 intx recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
542 SystemDictionary_lock->wait();
543 SystemDictionary_lock->unlock();
544 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
545 SystemDictionary_lock->lock();
546 }
547
548 // If the class in is in the placeholder table, class loading is in progress
549 // For cases where the application changes threads to load classes, it
550 // is critical to ClassCircularity detection that we try loading
551 // the superclass on the same thread internally, so we do parallel
552 // super class loading here.
553 // This also is critical in cases where the original thread gets stalled
554 // even in non-circularity situations.
555 // Note: must call resolve_super_or_fail even if null super -
556 // to force placeholder entry creation for this class for circularity detection
557 // Caller must check for pending exception
558 // Returns non-null Klass* if other thread has completed load
559 // and we are done,
560 // If return null Klass* and no pending exception, the caller must load the class
561 InstanceKlass* SystemDictionary::handle_parallel_super_load(
562 Symbol* name, Symbol* superclassname, Handle class_loader,
563 Handle protection_domain, Handle lockObject, TRAPS) {
564
565 ClassLoaderData* loader_data = class_loader_data(class_loader);
566 Dictionary* dictionary = loader_data->dictionary();
567 unsigned int d_hash = dictionary->compute_hash(name);
568 unsigned int p_hash = placeholders()->compute_hash(name);
569 int p_index = placeholders()->hash_to_index(p_hash);
570
571 // superk is not used, resolve_super called for circularity check only
572 // This code is reached in two situations. One if this thread
573 // is loading the same class twice (e.g. ClassCircularity, or
574 // java.lang.instrument).
575 // The second is if another thread started the resolve_super first
576 // and has not yet finished.
577 // In both cases the original caller will clean up the placeholder
578 // entry on error.
579 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
580 superclassname,
581 class_loader,
582 protection_domain,
583 true,
584 CHECK_NULL);
585
586 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
587 // Serial class loaders and bootstrap classloader do wait for superclass loads
588 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
589 MutexLocker mu(THREAD, SystemDictionary_lock);
590 // Check if classloading completed while we were loading superclass or waiting
591 return find_class(d_hash, name, dictionary);
592 }
593
594 // must loop to both handle other placeholder updates
595 // and spurious notifications
596 bool super_load_in_progress = true;
597 PlaceholderEntry* placeholder;
598 while (super_load_in_progress) {
599 MutexLocker mu(THREAD, SystemDictionary_lock);
600 // Check if classloading completed while we were loading superclass or waiting
601 InstanceKlass* check = find_class(d_hash, name, dictionary);
602 if (check != NULL) {
603 // Klass is already loaded, so just return it
604 return check;
605 } else {
606 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
607 if (placeholder && placeholder->super_load_in_progress() ){
608 // We only get here if the application has released the
609 // classloader lock when another thread was in the middle of loading a
610 // superclass/superinterface for this class, and now
611 // this thread is also trying to load this class.
612 // To minimize surprises, the first thread that started to
613 // load a class should be the one to complete the loading
614 // with the classfile it initially expected.
615 // This logic has the current thread wait once it has done
616 // all the superclass/superinterface loading it can, until
617 // the original thread completes the class loading or fails
618 // If it completes we will use the resulting InstanceKlass
619 // which we will find below in the systemDictionary.
620 // We also get here for parallel bootstrap classloader
621 if (class_loader.is_null()) {
622 SystemDictionary_lock->wait();
623 } else {
624 double_lock_wait(lockObject, THREAD);
625 }
626 } else {
627 // If not in SD and not in PH, other thread's load must have failed
628 super_load_in_progress = false;
629 }
630 }
631 }
632 return NULL;
633 }
634
635 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
636 assert(event != NULL, "invariant");
637 assert(k != NULL, "invariant");
638 assert(event->should_commit(), "invariant");
639 event->set_loadedClass(k);
640 event->set_definingClassLoader(k->class_loader_data());
641 event->set_initiatingClassLoader(init_cld);
642 event->commit();
643 }
644
645
646 // Be careful when modifying this code: once you have run
647 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
648 // you need to find_and_remove it before returning.
649 // So be careful to not exit with a CHECK_ macro betweeen these calls.
650 //
651 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
652 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
653 Handle class_loader,
654 Handle protection_domain,
655 TRAPS) {
656 assert(name != NULL && !Signature::is_array(name) &&
657 !Signature::has_envelope(name), "invalid class name");
658
659 EventClassLoad class_load_start_event;
660
661 HandleMark hm(THREAD);
662
663 // Fix for 4474172; see evaluation for more details
664 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
665 ClassLoaderData* loader_data = register_loader(class_loader);
666 Dictionary* dictionary = loader_data->dictionary();
667 unsigned int d_hash = dictionary->compute_hash(name);
668
669 // Do lookup to see if class already exist and the protection domain
670 // has the right access
671 // This call uses find which checks protection domain already matches
672 // All subsequent calls use find_class, and set has_loaded_class so that
673 // before we return a result we call out to java to check for valid protection domain
674 // to allow returning the Klass* and add it to the pd_set if it is valid
675 {
676 InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
677 if (probe != NULL) return probe;
678 }
679
680 // Non-bootstrap class loaders will call out to class loader and
681 // define via jvm/jni_DefineClass which will acquire the
682 // class loader object lock to protect against multiple threads
683 // defining the class in parallel by accident.
684 // This lock must be acquired here so the waiter will find
685 // any successful result in the SystemDictionary and not attempt
686 // the define.
687 // ParallelCapable Classloaders and the bootstrap classloader
688 // do not acquire lock here.
689 bool DoObjectLock = true;
690 if (is_parallelCapable(class_loader)) {
691 DoObjectLock = false;
692 }
693
694 unsigned int p_hash = placeholders()->compute_hash(name);
695 int p_index = placeholders()->hash_to_index(p_hash);
696
697 // Class is not in SystemDictionary so we have to do loading.
698 // Make sure we are synchronized on the class loader before we proceed
699 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
700 check_loader_lock_contention(lockObject, THREAD);
701 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
702
703 // Check again (after locking) if class already exist in SystemDictionary
704 bool class_has_been_loaded = false;
705 bool super_load_in_progress = false;
706 bool havesupername = false;
707 InstanceKlass* k = NULL;
708 PlaceholderEntry* placeholder;
709 Symbol* superclassname = NULL;
710
711 assert(THREAD->can_call_java(),
712 "can not load classes with compiler thread: class=%s, classloader=%s",
713 name->as_C_string(),
714 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
715 {
716 MutexLocker mu(THREAD, SystemDictionary_lock);
717 InstanceKlass* check = find_class(d_hash, name, dictionary);
718 if (check != NULL) {
719 // InstanceKlass is already loaded, so just return it
720 class_has_been_loaded = true;
721 k = check;
722 } else {
723 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
724 if (placeholder && placeholder->super_load_in_progress()) {
725 super_load_in_progress = true;
726 if (placeholder->havesupername() == true) {
727 superclassname = placeholder->supername();
728 havesupername = true;
729 }
730 }
731 }
732 }
733
734 // If the class is in the placeholder table, class loading is in progress
735 if (super_load_in_progress && havesupername==true) {
736 k = handle_parallel_super_load(name,
737 superclassname,
738 class_loader,
739 protection_domain,
740 lockObject, THREAD);
741 if (HAS_PENDING_EXCEPTION) {
742 return NULL;
743 }
744 if (k != NULL) {
745 class_has_been_loaded = true;
746 }
747 }
748
749 bool throw_circularity_error = false;
750 if (!class_has_been_loaded) {
751 bool load_instance_added = false;
752
753 // add placeholder entry to record loading instance class
754 // Five cases:
755 // All cases need to prevent modifying bootclasssearchpath
756 // in parallel with a classload of same classname
757 // Redefineclasses uses existence of the placeholder for the duration
758 // of the class load to prevent concurrent redefinition of not completely
759 // defined classes.
760 // case 1. traditional classloaders that rely on the classloader object lock
761 // - no other need for LOAD_INSTANCE
762 // case 2. traditional classloaders that break the classloader object lock
763 // as a deadlock workaround. Detection of this case requires that
764 // this check is done while holding the classloader object lock,
765 // and that lock is still held when calling classloader's loadClass.
766 // For these classloaders, we ensure that the first requestor
767 // completes the load and other requestors wait for completion.
768 // case 3. Bootstrap classloader - don't own objectLocker
769 // This classloader supports parallelism at the classloader level,
770 // but only allows a single load of a class/classloader pair.
771 // No performance benefit and no deadlock issues.
772 // case 4. parallelCapable user level classloaders - without objectLocker
773 // Allow parallel classloading of a class/classloader pair
774
775 {
776 MutexLocker mu(THREAD, SystemDictionary_lock);
777 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
778 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
779 if (oldprobe) {
780 // only need check_seen_thread once, not on each loop
781 // 6341374 java/lang/Instrument with -Xcomp
782 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
783 throw_circularity_error = true;
784 } else {
785 // case 1: traditional: should never see load_in_progress.
786 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
787
788 // case 3: bootstrap classloader: prevent futile classloading,
789 // wait on first requestor
790 if (class_loader.is_null()) {
791 SystemDictionary_lock->wait();
792 } else {
793 // case 2: traditional with broken classloader lock. wait on first
794 // requestor.
795 double_lock_wait(lockObject, THREAD);
796 }
797 // Check if classloading completed while we were waiting
798 InstanceKlass* check = find_class(d_hash, name, dictionary);
799 if (check != NULL) {
800 // Klass is already loaded, so just return it
801 k = check;
802 class_has_been_loaded = true;
803 }
804 // check if other thread failed to load and cleaned up
805 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
806 }
807 }
808 }
809 }
810 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
811 // case 4: parallelCapable: allow competing threads to try
812 // LOAD_INSTANCE in parallel
813
814 if (!throw_circularity_error && !class_has_been_loaded) {
815 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
816 load_instance_added = true;
817 // For class loaders that do not acquire the classloader object lock,
818 // if they did not catch another thread holding LOAD_INSTANCE,
819 // need a check analogous to the acquire ObjectLocker/find_class
820 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
821 // one final check if the load has already completed
822 // class loaders holding the ObjectLock shouldn't find the class here
823 InstanceKlass* check = find_class(d_hash, name, dictionary);
824 if (check != NULL) {
825 // Klass is already loaded, so return it after checking/adding protection domain
826 k = check;
827 class_has_been_loaded = true;
828 }
829 }
830 }
831
832 // must throw error outside of owning lock
833 if (throw_circularity_error) {
834 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
835 ResourceMark rm(THREAD);
836 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
837 }
838
839 if (!class_has_been_loaded) {
840
841 // Do actual loading
842 k = load_instance_class(name, class_loader, THREAD);
843
844 // If everything was OK (no exceptions, no null return value), and
845 // class_loader is NOT the defining loader, do a little more bookkeeping.
846 if (!HAS_PENDING_EXCEPTION && k != NULL &&
847 k->class_loader() != class_loader()) {
848
849 check_constraints(d_hash, k, class_loader, false, THREAD);
850
851 // Need to check for a PENDING_EXCEPTION again; check_constraints
852 // can throw but we may have to remove entry from the placeholder table below.
853 if (!HAS_PENDING_EXCEPTION) {
854 // Record dependency for non-parent delegation.
855 // This recording keeps the defining class loader of the klass (k) found
856 // from being unloaded while the initiating class loader is loaded
857 // even if the reference to the defining class loader is dropped
858 // before references to the initiating class loader.
859 loader_data->record_dependency(k);
860
861 { // Grabbing the Compile_lock prevents systemDictionary updates
862 // during compilations.
863 MutexLocker mu(THREAD, Compile_lock);
864 update_dictionary(d_hash, p_index, p_hash,
865 k, class_loader, THREAD);
866 }
867
868 if (JvmtiExport::should_post_class_load()) {
869 Thread *thread = THREAD;
870 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
871 JvmtiExport::post_class_load((JavaThread *) thread, k);
872 }
873 }
874 }
875 } // load_instance_class
876
877 if (load_instance_added == true) {
878 // clean up placeholder entries for LOAD_INSTANCE success or error
879 // This brackets the SystemDictionary updates for both defining
880 // and initiating loaders
881 MutexLocker mu(THREAD, SystemDictionary_lock);
882 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
883 SystemDictionary_lock->notify_all();
884 }
885 }
886
887 if (HAS_PENDING_EXCEPTION || k == NULL) {
888 return NULL;
889 }
890 if (class_load_start_event.should_commit()) {
891 post_class_load_event(&class_load_start_event, k, loader_data);
892 }
893 #ifdef ASSERT
894 {
895 ClassLoaderData* loader_data = k->class_loader_data();
896 MutexLocker mu(THREAD, SystemDictionary_lock);
897 InstanceKlass* kk = find_class(name, loader_data);
898 assert(kk == k, "should be present in dictionary");
899 }
900 #endif
901
902 // return if the protection domain in NULL
903 if (protection_domain() == NULL) return k;
904
905 // Check the protection domain has the right access
906 if (dictionary->is_valid_protection_domain(d_hash, name,
907 protection_domain)) {
908 return k;
909 }
910
911 // Verify protection domain. If it fails an exception is thrown
912 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
913
914 return k;
915 }
916
917
918 // This routine does not lock the system dictionary.
919 //
920 // Since readers don't hold a lock, we must make sure that system
921 // dictionary entries are only removed at a safepoint (when only one
922 // thread is running), and are added to in a safe way (all links must
923 // be updated in an MT-safe manner).
924 //
925 // Callers should be aware that an entry could be added just after
926 // _dictionary->bucket(index) is read here, so the caller will not see
927 // the new entry.
928
929 Klass* SystemDictionary::find(Symbol* class_name,
930 Handle class_loader,
931 Handle protection_domain,
932 TRAPS) {
933
934 // The result of this call should be consistent with the result
935 // of the call to resolve_instance_class_or_null().
936 // See evaluation 6790209 and 4474172 for more details.
937 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
938 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
939
940 if (loader_data == NULL) {
941 // If the ClassLoaderData has not been setup,
942 // then the class loader has no entries in the dictionary.
943 return NULL;
944 }
945
946 Dictionary* dictionary = loader_data->dictionary();
947 unsigned int d_hash = dictionary->compute_hash(class_name);
948 return dictionary->find(d_hash, class_name,
949 protection_domain);
950 }
951
952
953 // Look for a loaded instance or array klass by name. Do not do any loading.
954 // return NULL in case of error.
955 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
956 Handle class_loader,
957 Handle protection_domain,
958 TRAPS) {
959 Klass* k = NULL;
960 assert(class_name != NULL, "class name must be non NULL");
961
962 if (Signature::is_array(class_name)) {
963 // The name refers to an array. Parse the name.
964 // dimension and object_key in FieldArrayInfo are assigned as a
965 // side-effect of this call
966 SignatureStream ss(class_name, false);
967 int ndims = ss.skip_array_prefix(); // skip all '['s
968 BasicType t = ss.type();
969 if (t != T_OBJECT) {
970 k = Universe::typeArrayKlassObj(t);
971 } else {
972 Symbol* obj_class = ss.as_symbol();
973 k = SystemDictionary::find(obj_class, class_loader, protection_domain, THREAD);
974 }
975 if (k != NULL) {
976 k = k->array_klass_or_null(ndims);
977 }
978 } else {
979 k = find(class_name, class_loader, protection_domain, THREAD);
980 }
981 return k;
982 }
983
984 // Note: this method is much like resolve_from_stream, but
985 // does not publish the classes via the SystemDictionary.
986 // Handles unsafe_DefineAnonymousClass and redefineclasses
987 // RedefinedClasses do not add to the class hierarchy
988 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
989 Handle class_loader,
990 Handle protection_domain,
991 ClassFileStream* st,
992 const InstanceKlass* unsafe_anonymous_host,
993 GrowableArray<Handle>* cp_patches,
994 TRAPS) {
995
996 EventClassLoad class_load_start_event;
997
998 ClassLoaderData* loader_data;
999 if (unsafe_anonymous_host != NULL) {
1000 // Create a new CLD for an unsafe anonymous class, that uses the same class loader
1001 // as the unsafe_anonymous_host
1002 guarantee(unsafe_anonymous_host->class_loader() == class_loader(), "should be the same");
1003 loader_data = ClassLoaderData::unsafe_anonymous_class_loader_data(class_loader);
1004 } else {
1005 loader_data = ClassLoaderData::class_loader_data(class_loader());
1006 }
1007
1008 assert(st != NULL, "invariant");
1009 assert(st->need_verify(), "invariant");
1010
1011 // Parse stream and create a klass.
1012 // Note that we do this even though this klass might
1013 // already be present in the SystemDictionary, otherwise we would not
1014 // throw potential ClassFormatErrors.
1015
1016 InstanceKlass* k = KlassFactory::create_from_stream(st,
1017 class_name,
1018 loader_data,
1019 protection_domain,
1020 unsafe_anonymous_host,
1021 cp_patches,
1022 CHECK_NULL);
1023
1024 if (unsafe_anonymous_host != NULL && k != NULL) {
1025 // Unsafe anonymous classes must update ClassLoaderData holder (was unsafe_anonymous_host loader)
1026 // so that they can be unloaded when the mirror is no longer referenced.
1027 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1028
1029 {
1030 MutexLocker mu_r(THREAD, Compile_lock);
1031
1032 // Add to class hierarchy, initialize vtables, and do possible
1033 // deoptimizations.
1034 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1035 // But, do not add to dictionary.
1036 }
1037
1038 // Rewrite and patch constant pool here.
1039 k->link_class(CHECK_NULL);
1040 if (cp_patches != NULL) {
1041 k->constants()->patch_resolved_references(cp_patches);
1042 }
1043
1044 // If it's anonymous, initialize it now, since nobody else will.
1045 k->eager_initialize(CHECK_NULL);
1046
1047 // notify jvmti
1048 if (JvmtiExport::should_post_class_load()) {
1049 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1050 JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1051 }
1052 if (class_load_start_event.should_commit()) {
1053 post_class_load_event(&class_load_start_event, k, loader_data);
1054 }
1055 }
1056 assert(unsafe_anonymous_host != NULL || NULL == cp_patches,
1057 "cp_patches only found with unsafe_anonymous_host");
1058
1059 return k;
1060 }
1061
1062 // Add a klass to the system from a stream (called by jni_DefineClass and
1063 // JVM_DefineClass).
1064 // Note: class_name can be NULL. In that case we do not know the name of
1065 // the class until we have parsed the stream.
1066
1067 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1068 Handle class_loader,
1069 Handle protection_domain,
1070 ClassFileStream* st,
1071 TRAPS) {
1072
1073 HandleMark hm(THREAD);
1074
1075 // Classloaders that support parallelism, e.g. bootstrap classloader,
1076 // do not acquire lock here
1077 bool DoObjectLock = true;
1078 if (is_parallelCapable(class_loader)) {
1079 DoObjectLock = false;
1080 }
1081
1082 ClassLoaderData* loader_data = register_loader(class_loader);
1083
1084 // Make sure we are synchronized on the class loader before we proceed
1085 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1086 check_loader_lock_contention(lockObject, THREAD);
1087 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1088
1089 assert(st != NULL, "invariant");
1090
1091 // Parse the stream and create a klass.
1092 // Note that we do this even though this klass might
1093 // already be present in the SystemDictionary, otherwise we would not
1094 // throw potential ClassFormatErrors.
1095 InstanceKlass* k = NULL;
1096
1097 #if INCLUDE_CDS
1098 if (!DumpSharedSpaces) {
1099 k = SystemDictionaryShared::lookup_from_stream(class_name,
1100 class_loader,
1101 protection_domain,
1102 st,
1103 CHECK_NULL);
1104 }
1105 #endif
1106
1107 if (k == NULL) {
1108 if (st->buffer() == NULL) {
1109 return NULL;
1110 }
1111 k = KlassFactory::create_from_stream(st,
1112 class_name,
1113 loader_data,
1114 protection_domain,
1115 NULL, // unsafe_anonymous_host
1116 NULL, // cp_patches
1117 CHECK_NULL);
1118 }
1119
1120 assert(k != NULL, "no klass created");
1121 Symbol* h_name = k->name();
1122 assert(class_name == NULL || class_name == h_name, "name mismatch");
1123
1124 // Add class just loaded
1125 // If a class loader supports parallel classloading handle parallel define requests
1126 // find_or_define_instance_class may return a different InstanceKlass
1127 if (is_parallelCapable(class_loader)) {
1128 InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1129 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1130 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1131 assert(defined_k != NULL, "Should have a klass if there's no exception");
1132 loader_data->add_to_deallocate_list(k);
1133 k = defined_k;
1134 }
1135 } else {
1136 define_instance_class(k, THREAD);
1137 }
1138
1139 // If defining the class throws an exception register 'k' for cleanup.
1140 if (HAS_PENDING_EXCEPTION) {
1141 assert(k != NULL, "Must have an instance klass here!");
1142 loader_data->add_to_deallocate_list(k);
1143 return NULL;
1144 }
1145
1146 // Make sure we have an entry in the SystemDictionary on success
1147 debug_only( {
1148 MutexLocker mu(THREAD, SystemDictionary_lock);
1149
1150 Klass* check = find_class(h_name, k->class_loader_data());
1151 assert(check == k, "should be present in the dictionary");
1152 } );
1153
1154 return k;
1155 }
1156
1157 #if INCLUDE_CDS
1158 // Load a class for boot loader from the shared spaces. This also
1159 // forces the super class and all interfaces to be loaded.
1160 InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
1161 TRAPS) {
1162 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1163 if (ik != NULL && ik->is_shared_boot_class()) {
1164 return load_shared_class(ik, Handle(), Handle(), NULL, THREAD);
1165 }
1166 return NULL;
1167 }
1168
1169 // Check if a shared class can be loaded by the specific classloader:
1170 //
1171 // NULL classloader:
1172 // - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1173 // - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1174 // be defined in an unnamed module.
1175 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1176 InstanceKlass* ik,
1177 Handle class_loader, TRAPS) {
1178 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1179 "Cannot use sharing if java.base is patched");
1180 ResourceMark rm(THREAD);
1181 int path_index = ik->shared_classpath_index();
1182 ClassLoaderData* loader_data = class_loader_data(class_loader);
1183 if (path_index < 0) {
1184 // path_index < 0 indicates that the class is intended for a custom loader
1185 // and should not be loaded by boot/platform/app loaders
1186 if (loader_data->is_builtin_class_loader_data()) {
1187 return false;
1188 } else {
1189 return true;
1190 }
1191 }
1192 SharedClassPathEntry* ent =
1193 (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1194 if (!Universe::is_module_initialized()) {
1195 assert(ent != NULL && ent->is_modules_image(),
1196 "Loading non-bootstrap classes before the module system is initialized");
1197 assert(class_loader.is_null(), "sanity");
1198 return true;
1199 }
1200 // Get the pkg_entry from the classloader
1201 TempNewSymbol pkg_name = NULL;
1202 PackageEntry* pkg_entry = NULL;
1203 ModuleEntry* mod_entry = NULL;
1204 pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1205 if (pkg_name != NULL) {
1206 if (loader_data != NULL) {
1207 pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1208 }
1209 if (pkg_entry != NULL) {
1210 mod_entry = pkg_entry->module();
1211 }
1212 }
1213
1214 // If the archived class is from a module that has been patched at runtime,
1215 // the class cannot be loaded from the archive.
1216 if (mod_entry != NULL && mod_entry->is_patched()) {
1217 return false;
1218 }
1219
1220 if (class_loader.is_null()) {
1221 assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1222 // The NULL classloader can load archived class originated from the
1223 // "modules" jimage and the -Xbootclasspath/a. For class from the
1224 // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1225 // by the NULL classloader.
1226 if (mod_entry != NULL) {
1227 // PackageEntry/ModuleEntry is found in the classloader. Check if the
1228 // ModuleEntry's location agrees with the archived class' origination.
1229 if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1230 return true; // Module class from the "module" jimage
1231 }
1232 }
1233
1234 // If the archived class is not from the "module" jimage, the class can be
1235 // loaded by the NULL classloader if
1236 //
1237 // 1. the class is from the unamed package
1238 // 2. or, the class is not from a module defined in the NULL classloader
1239 // 3. or, the class is from an unamed module
1240 if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1241 // the class is from the -Xbootclasspath/a
1242 if (pkg_name == NULL ||
1243 pkg_entry == NULL ||
1244 pkg_entry->in_unnamed_module()) {
1245 assert(mod_entry == NULL ||
1246 mod_entry == loader_data->unnamed_module(),
1247 "the unnamed module is not defined in the classloader");
1248 return true;
1249 }
1250 }
1251 return false;
1252 } else {
1253 bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1254 ik, class_loader, pkg_name, pkg_entry, mod_entry, CHECK_(false));
1255 return res;
1256 }
1257 }
1258
1259 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1260 Handle class_loader,
1261 Handle protection_domain,
1262 const ClassFileStream *cfs,
1263 TRAPS) {
1264 assert(ik != NULL, "sanity");
1265 assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
1266 Symbol* class_name = ik->name();
1267
1268 bool visible = is_shared_class_visible(
1269 class_name, ik, class_loader, CHECK_NULL);
1270 if (!visible) {
1271 return NULL;
1272 }
1273
1274 // Resolve the superclass and interfaces. They must be the same
1275 // as in dump time, because the layout of <ik> depends on
1276 // the specific layout of ik->super() and ik->local_interfaces().
1277 //
1278 // If unexpected superclass or interfaces are found, we cannot
1279 // load <ik> from the shared archive.
1280
1281 if (ik->super() != NULL) {
1282 Symbol* cn = ik->super()->name();
1283 Klass *s = resolve_super_or_fail(class_name, cn,
1284 class_loader, protection_domain, true, CHECK_NULL);
1285 if (s != ik->super()) {
1286 // The dynamically resolved super class is not the same as the one we used during dump time,
1287 // so we cannot use ik.
1288 return NULL;
1289 } else {
1290 assert(s->is_shared(), "must be");
1291 }
1292 }
1293
1294 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1295 int num_interfaces = interfaces->length();
1296 for (int index = 0; index < num_interfaces; index++) {
1297 InstanceKlass* k = interfaces->at(index);
1298 Symbol* name = k->name();
1299 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1300 if (k != i) {
1301 // The dynamically resolved interface class is not the same as the one we used during dump time,
1302 // so we cannot use ik.
1303 return NULL;
1304 } else {
1305 assert(i->is_shared(), "must be");
1306 }
1307 }
1308
1309 InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1310 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1311 if (new_ik != NULL) {
1312 // The class is changed by CFLH. Return the new class. The shared class is
1313 // not used.
1314 return new_ik;
1315 }
1316
1317 // Adjust methods to recover missing data. They need addresses for
1318 // interpreter entry points and their default native method address
1319 // must be reset.
1320
1321 // Updating methods must be done under a lock so multiple
1322 // threads don't update these in parallel
1323 //
1324 // Shared classes are all currently loaded by either the bootstrap or
1325 // internal parallel class loaders, so this will never cause a deadlock
1326 // on a custom class loader lock.
1327
1328 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1329 {
1330 HandleMark hm(THREAD);
1331 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1332 check_loader_lock_contention(lockObject, THREAD);
1333 ObjectLocker ol(lockObject, THREAD, true);
1334 // prohibited package check assumes all classes loaded from archive call
1335 // restore_unshareable_info which calls ik->set_package()
1336 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1337 }
1338
1339 ik->print_class_load_logging(loader_data, NULL, NULL);
1340
1341 // For boot loader, ensure that GetSystemPackage knows that a class in this
1342 // package was loaded.
1343 if (class_loader.is_null()) {
1344 int path_index = ik->shared_classpath_index();
1345 ResourceMark rm(THREAD);
1346 ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1347 }
1348
1349 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1350 // Only dump the classes that can be stored into CDS archive
1351 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1352 ResourceMark rm(THREAD);
1353 classlist_file->print_cr("%s", ik->name()->as_C_string());
1354 classlist_file->flush();
1355 }
1356 }
1357
1358 // notify a class loaded from shared object
1359 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1360
1361 ik->set_has_passed_fingerprint_check(false);
1362 if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1363 uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1364 uint64_t cds_fp = ik->get_stored_fingerprint();
1365 if (aot_fp != 0 && aot_fp == cds_fp) {
1366 // This class matches with a class saved in an AOT library
1367 ik->set_has_passed_fingerprint_check(true);
1368 } else {
1369 if (log_is_enabled(Info, class, fingerprint)) {
1370 ResourceMark rm(THREAD);
1371 log_info(class, fingerprint)("%s : expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1372 }
1373 }
1374 }
1375
1376 return ik;
1377 }
1378 #endif // INCLUDE_CDS
1379
1380 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1381
1382 if (class_loader.is_null()) {
1383 ResourceMark rm(THREAD);
1384 PackageEntry* pkg_entry = NULL;
1385 bool search_only_bootloader_append = false;
1386 ClassLoaderData *loader_data = class_loader_data(class_loader);
1387
1388 // Find the package in the boot loader's package entry table.
1389 TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1390 if (pkg_name != NULL) {
1391 pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1392 }
1393
1394 // Prior to attempting to load the class, enforce the boot loader's
1395 // visibility boundaries.
1396 if (!Universe::is_module_initialized()) {
1397 // During bootstrapping, prior to module initialization, any
1398 // class attempting to be loaded must be checked against the
1399 // java.base packages in the boot loader's PackageEntryTable.
1400 // No class outside of java.base is allowed to be loaded during
1401 // this bootstrapping window.
1402 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1403 // Class is either in the unnamed package or in
1404 // a named package within the unnamed module. Either
1405 // case is outside of java.base, do not attempt to
1406 // load the class post java.base definition. If
1407 // java.base has not been defined, let the class load
1408 // and its package will be checked later by
1409 // ModuleEntryTable::verify_javabase_packages.
1410 if (ModuleEntryTable::javabase_defined()) {
1411 return NULL;
1412 }
1413 } else {
1414 // Check that the class' package is defined within java.base.
1415 ModuleEntry* mod_entry = pkg_entry->module();
1416 Symbol* mod_entry_name = mod_entry->name();
1417 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1418 return NULL;
1419 }
1420 }
1421 } else {
1422 // After the module system has been initialized, check if the class'
1423 // package is in a module defined to the boot loader.
1424 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1425 // Class is either in the unnamed package, in a named package
1426 // within a module not defined to the boot loader or in a
1427 // a named package within the unnamed module. In all cases,
1428 // limit visibility to search for the class only in the boot
1429 // loader's append path.
1430 if (!ClassLoader::has_bootclasspath_append()) {
1431 // If there is no bootclasspath append entry, no need to continue
1432 // searching.
1433 return NULL;
1434 }
1435 search_only_bootloader_append = true;
1436 }
1437 }
1438
1439 // Prior to bootstrapping's module initialization, never load a class outside
1440 // of the boot loader's module path
1441 assert(Universe::is_module_initialized() ||
1442 !search_only_bootloader_append,
1443 "Attempt to load a class outside of boot loader's module path");
1444
1445 // Search for classes in the CDS archive.
1446 InstanceKlass* k = NULL;
1447 {
1448 #if INCLUDE_CDS
1449 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1450 k = load_shared_boot_class(class_name, THREAD);
1451 #endif
1452 }
1453
1454 if (k == NULL) {
1455 // Use VM class loader
1456 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1457 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1458 }
1459
1460 // find_or_define_instance_class may return a different InstanceKlass
1461 if (k != NULL) {
1462 InstanceKlass* defined_k =
1463 find_or_define_instance_class(class_name, class_loader, k, THREAD);
1464 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1465 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1466 assert(defined_k != NULL, "Should have a klass if there's no exception");
1467 loader_data->add_to_deallocate_list(k);
1468 k = defined_k;
1469 } else if (HAS_PENDING_EXCEPTION) {
1470 loader_data->add_to_deallocate_list(k);
1471 return NULL;
1472 }
1473 }
1474 return k;
1475 } else {
1476 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1477 ResourceMark rm(THREAD);
1478
1479 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1480 JavaThread* jt = (JavaThread*) THREAD;
1481
1482 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1483 ClassLoader::perf_app_classload_selftime(),
1484 ClassLoader::perf_app_classload_count(),
1485 jt->get_thread_stat()->perf_recursion_counts_addr(),
1486 jt->get_thread_stat()->perf_timers_addr(),
1487 PerfClassTraceTime::CLASS_LOAD);
1488
1489 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1490 // Translate to external class name format, i.e., convert '/' chars to '.'
1491 Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1492
1493 JavaValue result(T_OBJECT);
1494
1495 InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1496
1497 // Call public unsynchronized loadClass(String) directly for all class loaders.
1498 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1499 // acquire a class-name based lock rather than the class loader object lock.
1500 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1501 JavaCalls::call_virtual(&result,
1502 class_loader,
1503 spec_klass,
1504 vmSymbols::loadClass_name(),
1505 vmSymbols::string_class_signature(),
1506 string,
1507 CHECK_NULL);
1508
1509 assert(result.get_type() == T_OBJECT, "just checking");
1510 oop obj = (oop) result.get_jobject();
1511
1512 // Primitive classes return null since forName() can not be
1513 // used to obtain any of the Class objects representing primitives or void
1514 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1515 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1516 // For user defined Java class loaders, check that the name returned is
1517 // the same as that requested. This check is done for the bootstrap
1518 // loader when parsing the class file.
1519 if (class_name == k->name()) {
1520 return k;
1521 }
1522 }
1523 // Class is not found or has the wrong name, return NULL
1524 return NULL;
1525 }
1526 }
1527
1528 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1529 EventClassDefine event;
1530 if (event.should_commit()) {
1531 event.set_definedClass(k);
1532 event.set_definingClassLoader(def_cld);
1533 event.commit();
1534 }
1535 }
1536
1537 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1538
1539 HandleMark hm(THREAD);
1540 ClassLoaderData* loader_data = k->class_loader_data();
1541 Handle class_loader_h(THREAD, loader_data->class_loader());
1542
1543 // for bootstrap and other parallel classloaders don't acquire lock,
1544 // use placeholder token
1545 // If a parallelCapable class loader calls define_instance_class instead of
1546 // find_or_define_instance_class to get here, we have a timing
1547 // hole with systemDictionary updates and check_constraints
1548 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1549 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1550 compute_loader_lock_object(class_loader_h, THREAD)),
1551 "define called without lock");
1552 }
1553
1554 // Check class-loading constraints. Throw exception if violation is detected.
1555 // Grabs and releases SystemDictionary_lock
1556 // The check_constraints/find_class call and update_dictionary sequence
1557 // must be "atomic" for a specific class/classloader pair so we never
1558 // define two different instanceKlasses for that class/classloader pair.
1559 // Existing classloaders will call define_instance_class with the
1560 // classloader lock held
1561 // Parallel classloaders will call find_or_define_instance_class
1562 // which will require a token to perform the define class
1563 Symbol* name_h = k->name();
1564 Dictionary* dictionary = loader_data->dictionary();
1565 unsigned int d_hash = dictionary->compute_hash(name_h);
1566 check_constraints(d_hash, k, class_loader_h, true, CHECK);
1567
1568 // Register class just loaded with class loader (placed in ArrayList)
1569 // Note we do this before updating the dictionary, as this can
1570 // fail with an OutOfMemoryError (if it does, we will *not* put this
1571 // class in the dictionary and will not update the class hierarchy).
1572 // JVMTI FollowReferences needs to find the classes this way.
1573 if (k->class_loader() != NULL) {
1574 methodHandle m(THREAD, Universe::loader_addClass_method());
1575 JavaValue result(T_VOID);
1576 JavaCallArguments args(class_loader_h);
1577 args.push_oop(Handle(THREAD, k->java_mirror()));
1578 JavaCalls::call(&result, m, &args, CHECK);
1579 }
1580
1581 // Add the new class. We need recompile lock during update of CHA.
1582 {
1583 unsigned int p_hash = placeholders()->compute_hash(name_h);
1584 int p_index = placeholders()->hash_to_index(p_hash);
1585
1586 MutexLocker mu_r(THREAD, Compile_lock);
1587
1588 // Add to class hierarchy, initialize vtables, and do possible
1589 // deoptimizations.
1590 add_to_hierarchy(k, CHECK); // No exception, but can block
1591
1592 // Add to systemDictionary - so other classes can see it.
1593 // Grabs and releases SystemDictionary_lock
1594 update_dictionary(d_hash, p_index, p_hash,
1595 k, class_loader_h, THREAD);
1596 }
1597 k->eager_initialize(THREAD);
1598
1599 // notify jvmti
1600 if (JvmtiExport::should_post_class_load()) {
1601 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1602 JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1603
1604 }
1605 post_class_define_event(k, loader_data);
1606 }
1607
1608 // Support parallel classloading
1609 // All parallel class loaders, including bootstrap classloader
1610 // lock a placeholder entry for this class/class_loader pair
1611 // to allow parallel defines of different classes for this class loader
1612 // With AllowParallelDefine flag==true, in case they do not synchronize around
1613 // FindLoadedClass/DefineClass, calls, we check for parallel
1614 // loading for them, wait if a defineClass is in progress
1615 // and return the initial requestor's results
1616 // This flag does not apply to the bootstrap classloader.
1617 // With AllowParallelDefine flag==false, call through to define_instance_class
1618 // which will throw LinkageError: duplicate class definition.
1619 // False is the requested default.
1620 // For better performance, the class loaders should synchronize
1621 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1622 // potentially waste time reading and parsing the bytestream.
1623 // Note: VM callers should ensure consistency of k/class_name,class_loader
1624 // Be careful when modifying this code: once you have run
1625 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1626 // you need to find_and_remove it before returning.
1627 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1628 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1629 InstanceKlass* k, TRAPS) {
1630
1631 Symbol* name_h = k->name(); // passed in class_name may be null
1632 ClassLoaderData* loader_data = class_loader_data(class_loader);
1633 Dictionary* dictionary = loader_data->dictionary();
1634
1635 unsigned int d_hash = dictionary->compute_hash(name_h);
1636
1637 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1638 unsigned int p_hash = placeholders()->compute_hash(name_h);
1639 int p_index = placeholders()->hash_to_index(p_hash);
1640 PlaceholderEntry* probe;
1641
1642 {
1643 MutexLocker mu(THREAD, SystemDictionary_lock);
1644 // First check if class already defined
1645 if (is_parallelDefine(class_loader)) {
1646 InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1647 if (check != NULL) {
1648 return check;
1649 }
1650 }
1651
1652 // Acquire define token for this class/classloader
1653 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1654 // Wait if another thread defining in parallel
1655 // All threads wait - even those that will throw duplicate class: otherwise
1656 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1657 // if other thread has not finished updating dictionary
1658 while (probe->definer() != NULL) {
1659 SystemDictionary_lock->wait();
1660 }
1661 // Only special cases allow parallel defines and can use other thread's results
1662 // Other cases fall through, and may run into duplicate defines
1663 // caught by finding an entry in the SystemDictionary
1664 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1665 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1666 SystemDictionary_lock->notify_all();
1667 #ifdef ASSERT
1668 InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1669 assert(check != NULL, "definer missed recording success");
1670 #endif
1671 return probe->instance_klass();
1672 } else {
1673 // This thread will define the class (even if earlier thread tried and had an error)
1674 probe->set_definer(THREAD);
1675 }
1676 }
1677
1678 define_instance_class(k, THREAD);
1679
1680 Handle linkage_exception = Handle(); // null handle
1681
1682 // definer must notify any waiting threads
1683 {
1684 MutexLocker mu(THREAD, SystemDictionary_lock);
1685 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1686 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1687 if (probe != NULL) {
1688 if (HAS_PENDING_EXCEPTION) {
1689 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1690 CLEAR_PENDING_EXCEPTION;
1691 } else {
1692 probe->set_instance_klass(k);
1693 }
1694 probe->set_definer(NULL);
1695 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1696 SystemDictionary_lock->notify_all();
1697 }
1698 }
1699
1700 // Can't throw exception while holding lock due to rank ordering
1701 if (linkage_exception() != NULL) {
1702 THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1703 }
1704
1705 return k;
1706 }
1707
1708 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1709 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1710 if (class_loader.is_null()) {
1711 return Handle(THREAD, _system_loader_lock_obj);
1712 } else {
1713 return class_loader;
1714 }
1715 }
1716
1717 // This method is added to check how often we have to wait to grab loader
1718 // lock. The results are being recorded in the performance counters defined in
1719 // ClassLoader::_sync_systemLoaderLockContentionRate and
1720 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1721 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1722 if (!UsePerfData) {
1723 return;
1724 }
1725
1726 assert(!loader_lock.is_null(), "NULL lock object");
1727
1728 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1729 == ObjectSynchronizer::owner_other) {
1730 // contention will likely happen, so increment the corresponding
1731 // contention counter.
1732 if (loader_lock() == _system_loader_lock_obj) {
1733 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1734 } else {
1735 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1736 }
1737 }
1738 }
1739
1740 // ----------------------------------------------------------------------------
1741 // Lookup
1742
1743 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1744 Symbol* class_name,
1745 Dictionary* dictionary) {
1746 assert_locked_or_safepoint(SystemDictionary_lock);
1747 int index = dictionary->hash_to_index(hash);
1748 return dictionary->find_class(index, hash, class_name);
1749 }
1750
1751
1752 // Basic find on classes in the midst of being loaded
1753 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1754 ClassLoaderData* loader_data) {
1755 assert_locked_or_safepoint(SystemDictionary_lock);
1756 unsigned int p_hash = placeholders()->compute_hash(class_name);
1757 int p_index = placeholders()->hash_to_index(p_hash);
1758 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1759 }
1760
1761
1762 // Used for assertions and verification only
1763 // Precalculating the hash and index is an optimization because there are many lookups
1764 // before adding the class.
1765 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1766 assert_locked_or_safepoint(SystemDictionary_lock);
1767 #ifndef ASSERT
1768 guarantee(VerifyBeforeGC ||
1769 VerifyDuringGC ||
1770 VerifyBeforeExit ||
1771 VerifyDuringStartup ||
1772 VerifyAfterGC, "too expensive");
1773 #endif
1774
1775 Dictionary* dictionary = loader_data->dictionary();
1776 unsigned int d_hash = dictionary->compute_hash(class_name);
1777 return find_class(d_hash, class_name, dictionary);
1778 }
1779
1780
1781 // ----------------------------------------------------------------------------
1782 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1783 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1784 // before a new class is used.
1785
1786 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1787 assert(k != NULL, "just checking");
1788 assert_locked_or_safepoint(Compile_lock);
1789
1790 k->set_init_state(InstanceKlass::loaded);
1791 // make sure init_state store is already done.
1792 // The compiler reads the hierarchy outside of the Compile_lock.
1793 // Access ordering is used to add to hierarchy.
1794
1795 // Link into hierachy.
1796 k->append_to_sibling_list(); // add to superklass/sibling list
1797 k->process_interfaces(THREAD); // handle all "implements" declarations
1798
1799 // Now flush all code that depended on old class hierarchy.
1800 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1801 CodeCache::flush_dependents_on(k);
1802 }
1803
1804 // ----------------------------------------------------------------------------
1805 // GC support
1806
1807 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1808 // Note: anonymous classes are not in the SD.
1809 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1810
1811 bool unloading_occurred;
1812 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1813 {
1814 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1815 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1816 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1817 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1818 if (unloading_occurred) {
1819 MutexLocker ml2(is_concurrent ? Module_lock : NULL);
1820 JFR_ONLY(Jfr::on_unloading_classes();)
1821
1822 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
1823 ClassLoaderDataGraph::clean_module_and_package_info();
1824 constraints()->purge_loader_constraints();
1825 resolution_errors()->purge_resolution_errors();
1826 }
1827 }
1828
1829 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1830
1831 if (unloading_occurred) {
1832 SymbolTable::trigger_cleanup();
1833
1834 // Oops referenced by the protection domain cache table may get unreachable independently
1835 // of the class loader (eg. cached protection domain oops). So we need to
1836 // explicitly unlink them here.
1837 // All protection domain oops are linked to the caller class, so if nothing
1838 // unloads, this is not needed.
1839 _pd_cache_table->trigger_cleanup();
1840 }
1841
1842 return unloading_occurred;
1843 }
1844
1845 void SystemDictionary::oops_do(OopClosure* f, bool include_handles) {
1846 f->do_oop(&_java_system_loader);
1847 f->do_oop(&_java_platform_loader);
1848 f->do_oop(&_system_loader_lock_obj);
1849 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1850
1851 // Visit extra methods
1852 invoke_method_table()->oops_do(f);
1853
1854 if (include_handles) {
1855 OopStorageSet::vm_global()->oops_do(f);
1856 }
1857 }
1858
1859 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1860 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1861 for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1862 it->push(well_known_klass_addr((WKID)id));
1863 }
1864 }
1865
1866 void SystemDictionary::methods_do(void f(Method*)) {
1867 // Walk methods in loaded classes
1868 MutexLocker ml(ClassLoaderDataGraph_lock);
1869 ClassLoaderDataGraph::methods_do(f);
1870 // Walk method handle intrinsics
1871 invoke_method_table()->methods_do(f);
1872 }
1873
1874 // ----------------------------------------------------------------------------
1875 // Initialization
1876
1877 void SystemDictionary::initialize(TRAPS) {
1878 // Allocate arrays
1879 _placeholders = new PlaceholderTable(_placeholder_table_size);
1880 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1881 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1882 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1883 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1884
1885 // Allocate private object used as system class loader lock
1886 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1887 // Initialize basic classes
1888 resolve_well_known_classes(CHECK);
1889 }
1890
1891 // Compact table of directions on the initialization of klasses:
1892 static const short wk_init_info[] = {
1893 #define WK_KLASS_INIT_INFO(name, symbol) \
1894 ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
1895
1896 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1897 #undef WK_KLASS_INIT_INFO
1898 0
1899 };
1900
1901 #ifdef ASSERT
1902 bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
1903 int sid;
1904 for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
1905 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1906 if (class_name == symbol) {
1907 return true;
1908 }
1909 }
1910 return false;
1911 }
1912 #endif
1913
1914 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
1915 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1916 int sid = wk_init_info[id - FIRST_WKID];
1917 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1918 InstanceKlass** klassp = &_well_known_klasses[id];
1919
1920 if ((*klassp) == NULL) {
1921 Klass* k = resolve_or_fail(symbol, true, CHECK_0);
1922 (*klassp) = InstanceKlass::cast(k);
1923 }
1924 return ((*klassp) != NULL);
1925 }
1926
1927 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1928 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1929 for (int id = (int)start_id; id < (int)limit_id; id++) {
1930 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1931 resolve_wk_klass((WKID)id, CHECK);
1932 }
1933
1934 // move the starting value forward to the limit:
1935 start_id = limit_id;
1936 }
1937
1938 void SystemDictionary::resolve_well_known_classes(TRAPS) {
1939 assert(WK_KLASS(Object_klass) == NULL, "well-known classes should only be initialized once");
1940
1941 // Create the ModuleEntry for java.base. This call needs to be done here,
1942 // after vmSymbols::initialize() is called but before any classes are pre-loaded.
1943 ClassLoader::classLoader_init2(CHECK);
1944
1945 // Preload commonly used klasses
1946 WKID scan = FIRST_WKID;
1947 // first do Object, then String, Class
1948 #if INCLUDE_CDS
1949 if (UseSharedSpaces) {
1950 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1951
1952 // It's unsafe to access the archived heap regions before they
1953 // are fixed up, so we must do the fixup as early as possible
1954 // before the archived java objects are accessed by functions
1955 // such as java_lang_Class::restore_archived_mirror and
1956 // ConstantPool::restore_unshareable_info (restores the archived
1957 // resolved_references array object).
1958 //
1959 // HeapShared::fixup_mapped_heap_regions() fills the empty
1960 // spaces in the archived heap regions and may use
1961 // SystemDictionary::Object_klass(), so we can do this only after
1962 // Object_klass is resolved. See the above resolve_wk_klasses_through()
1963 // call. No mirror objects are accessed/restored in the above call.
1964 // Mirrors are restored after java.lang.Class is loaded.
1965 HeapShared::fixup_mapped_heap_regions();
1966
1967 // Initialize the constant pool for the Object_class
1968 assert(Object_klass()->is_shared(), "must be");
1969 Object_klass()->constants()->restore_unshareable_info(CHECK);
1970 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1971 } else
1972 #endif
1973 {
1974 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1975 }
1976
1977 assert(WK_KLASS(Object_klass) != NULL, "well-known classes should now be initialized");
1978
1979 java_lang_Object::register_natives(CHECK);
1980
1981 // Calculate offsets for String and Class classes since they are loaded and
1982 // can be used after this point.
1983 java_lang_String::compute_offsets();
1984 java_lang_Class::compute_offsets();
1985
1986 // Fixup mirrors for classes loaded before java.lang.Class.
1987 // These calls iterate over the objects currently in the perm gen
1988 // so calling them at this point is matters (not before when there
1989 // are fewer objects and not later after there are more objects
1990 // in the perm gen.
1991 Universe::initialize_basic_type_mirrors(CHECK);
1992 Universe::fixup_mirrors(CHECK);
1993
1994 // do a bunch more:
1995 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1996
1997 // Preload ref klasses and set reference types
1998 WK_KLASS(Reference_klass)->set_reference_type(REF_OTHER);
1999 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2000
2001 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2002 WK_KLASS(SoftReference_klass)->set_reference_type(REF_SOFT);
2003 WK_KLASS(WeakReference_klass)->set_reference_type(REF_WEAK);
2004 WK_KLASS(FinalReference_klass)->set_reference_type(REF_FINAL);
2005 WK_KLASS(PhantomReference_klass)->set_reference_type(REF_PHANTOM);
2006
2007 // JSR 292 classes
2008 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2009 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2010 resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
2011 resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
2012 WKID last = WKID_LIMIT;
2013 resolve_wk_klasses_until(last, scan, CHECK);
2014
2015 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2016 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
2017 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
2018 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
2019 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
2020 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
2021 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
2022 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
2023 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
2024 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
2025
2026 #ifdef ASSERT
2027 if (UseSharedSpaces) {
2028 assert(JvmtiExport::is_early_phase(),
2029 "All well known classes must be resolved in JVMTI early phase");
2030 for (int i = FIRST_WKID; i < last; i++) {
2031 InstanceKlass* k = _well_known_klasses[i];
2032 assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
2033 }
2034 }
2035 #endif
2036 }
2037
2038 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2039 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2040 BasicType SystemDictionary::box_klass_type(Klass* k) {
2041 assert(k != NULL, "");
2042 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2043 if (_box_klasses[i] == k)
2044 return (BasicType)i;
2045 }
2046 return T_OBJECT;
2047 }
2048
2049 // Constraints on class loaders. The details of the algorithm can be
2050 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2051 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2052 // that the dictionary needs to maintain a set of contraints that
2053 // must be satisfied by all classes in the dictionary.
2054 // if defining is true, then LinkageError if already in dictionary
2055 // if initiating loader, then ok if InstanceKlass matches existing entry
2056
2057 void SystemDictionary::check_constraints(unsigned int d_hash,
2058 InstanceKlass* k,
2059 Handle class_loader,
2060 bool defining,
2061 TRAPS) {
2062 ResourceMark rm(THREAD);
2063 stringStream ss;
2064 bool throwException = false;
2065
2066 {
2067 Symbol *name = k->name();
2068 ClassLoaderData *loader_data = class_loader_data(class_loader);
2069
2070 MutexLocker mu(THREAD, SystemDictionary_lock);
2071
2072 InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2073 if (check != NULL) {
2074 // If different InstanceKlass - duplicate class definition,
2075 // else - ok, class loaded by a different thread in parallel.
2076 // We should only have found it if it was done loading and ok to use.
2077 // The dictionary only holds instance classes, placeholders
2078 // also hold array classes.
2079
2080 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2081 if ((defining == true) || (k != check)) {
2082 throwException = true;
2083 ss.print("loader %s", loader_data->loader_name_and_id());
2084 ss.print(" attempted duplicate %s definition for %s. (%s)",
2085 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
2086 } else {
2087 return;
2088 }
2089 }
2090
2091 #ifdef ASSERT
2092 Symbol* ph_check = find_placeholder(name, loader_data);
2093 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2094 #endif
2095
2096 if (throwException == false) {
2097 if (constraints()->check_or_update(k, class_loader, name) == false) {
2098 throwException = true;
2099 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
2100 ss.print(" wants to load %s %s.",
2101 k->external_kind(), k->external_name());
2102 Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2103 if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
2104 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
2105 existing_klass->external_kind(),
2106 existing_klass->class_loader_data()->loader_name_and_id(),
2107 existing_klass->class_in_module_of_loader(false, true));
2108 } else {
2109 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
2110 }
2111 }
2112 }
2113 }
2114
2115 // Throw error now if needed (cannot throw while holding
2116 // SystemDictionary_lock because of rank ordering)
2117 if (throwException == true) {
2118 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2119 }
2120 }
2121
2122 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2123 // have been called.
2124 void SystemDictionary::update_dictionary(unsigned int d_hash,
2125 int p_index, unsigned int p_hash,
2126 InstanceKlass* k,
2127 Handle class_loader,
2128 TRAPS) {
2129 // Compile_lock prevents systemDictionary updates during compilations
2130 assert_locked_or_safepoint(Compile_lock);
2131 Symbol* name = k->name();
2132 ClassLoaderData *loader_data = class_loader_data(class_loader);
2133
2134 {
2135 MutexLocker mu1(THREAD, SystemDictionary_lock);
2136
2137 // Make a new dictionary entry.
2138 Dictionary* dictionary = loader_data->dictionary();
2139 InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2140 if (sd_check == NULL) {
2141 dictionary->add_klass(d_hash, name, k);
2142 }
2143 #ifdef ASSERT
2144 sd_check = find_class(d_hash, name, dictionary);
2145 assert (sd_check != NULL, "should have entry in dictionary");
2146 // Note: there may be a placeholder entry: for circularity testing
2147 // or for parallel defines
2148 #endif
2149 SystemDictionary_lock->notify_all();
2150 }
2151 }
2152
2153
2154 // Try to find a class name using the loader constraints. The
2155 // loader constraints might know about a class that isn't fully loaded
2156 // yet and these will be ignored.
2157 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2158 Symbol* class_name, Handle class_loader, TRAPS) {
2159
2160 // First see if it has been loaded directly.
2161 // Force the protection domain to be null. (This removes protection checks.)
2162 Handle no_protection_domain;
2163 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2164 no_protection_domain, CHECK_NULL);
2165 if (klass != NULL)
2166 return klass;
2167
2168 // Now look to see if it has been loaded elsewhere, and is subject to
2169 // a loader constraint that would require this loader to return the
2170 // klass that is already loaded.
2171 if (Signature::is_array(class_name)) {
2172 // For array classes, their Klass*s are not kept in the
2173 // constraint table. The element Klass*s are.
2174 SignatureStream ss(class_name, false);
2175 int ndims = ss.skip_array_prefix(); // skip all '['s
2176 BasicType t = ss.type();
2177 if (t != T_OBJECT) {
2178 klass = Universe::typeArrayKlassObj(t);
2179 } else {
2180 MutexLocker mu(THREAD, SystemDictionary_lock);
2181 klass = constraints()->find_constrained_klass(ss.as_symbol(), class_loader);
2182 }
2183 // If element class already loaded, allocate array klass
2184 if (klass != NULL) {
2185 klass = klass->array_klass_or_null(ndims);
2186 }
2187 } else {
2188 MutexLocker mu(THREAD, SystemDictionary_lock);
2189 // Non-array classes are easy: simply check the constraint table.
2190 klass = constraints()->find_constrained_klass(class_name, class_loader);
2191 }
2192
2193 return klass;
2194 }
2195
2196
2197 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2198 Handle class_loader1,
2199 Handle class_loader2,
2200 Thread* THREAD) {
2201 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2202 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2203
2204 Symbol* constraint_name = NULL;
2205
2206 if (!Signature::is_array(class_name)) {
2207 constraint_name = class_name;
2208 } else {
2209 // For array classes, their Klass*s are not kept in the
2210 // constraint table. The element classes are.
2211 SignatureStream ss(class_name, false);
2212 ss.skip_array_prefix(); // skip all '['s
2213 if (!ss.has_envelope()) {
2214 return true; // primitive types always pass
2215 }
2216 constraint_name = ss.as_symbol();
2217 // Increment refcount to keep constraint_name alive after
2218 // SignatureStream is destructed. It will be decremented below
2219 // before returning.
2220 constraint_name->increment_refcount();
2221 }
2222
2223 Dictionary* dictionary1 = loader_data1->dictionary();
2224 unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2225
2226 Dictionary* dictionary2 = loader_data2->dictionary();
2227 unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2228
2229 {
2230 MutexLocker mu_s(THREAD, SystemDictionary_lock);
2231 InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2232 InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2233 bool result = constraints()->add_entry(constraint_name, klass1, class_loader1,
2234 klass2, class_loader2);
2235 if (Signature::is_array(class_name)) {
2236 constraint_name->decrement_refcount();
2237 }
2238 return result;
2239 }
2240 }
2241
2242 // Add entry to resolution error table to record the error when the first
2243 // attempt to resolve a reference to a class has failed.
2244 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2245 Symbol* error, Symbol* message) {
2246 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2247 int index = resolution_errors()->hash_to_index(hash);
2248 {
2249 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2250 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2251 }
2252 }
2253
2254 // Delete a resolution error for RedefineClasses for a constant pool is going away
2255 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2256 resolution_errors()->delete_entry(pool);
2257 }
2258
2259 // Lookup resolution error table. Returns error if found, otherwise NULL.
2260 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2261 Symbol** message) {
2262 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2263 int index = resolution_errors()->hash_to_index(hash);
2264 {
2265 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2266 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2267 if (entry != NULL) {
2268 *message = entry->message();
2269 return entry->error();
2270 } else {
2271 return NULL;
2272 }
2273 }
2274 }
2275
2276
2277 // Signature constraints ensure that callers and callees agree about
2278 // the meaning of type names in their signatures. This routine is the
2279 // intake for constraints. It collects them from several places:
2280 //
2281 // * LinkResolver::resolve_method (if check_access is true) requires
2282 // that the resolving class (the caller) and the defining class of
2283 // the resolved method (the callee) agree on each type in the
2284 // method's signature.
2285 //
2286 // * LinkResolver::resolve_interface_method performs exactly the same
2287 // checks.
2288 //
2289 // * LinkResolver::resolve_field requires that the constant pool
2290 // attempting to link to a field agree with the field's defining
2291 // class about the type of the field signature.
2292 //
2293 // * klassVtable::initialize_vtable requires that, when a class
2294 // overrides a vtable entry allocated by a superclass, that the
2295 // overriding method (i.e., the callee) agree with the superclass
2296 // on each type in the method's signature.
2297 //
2298 // * klassItable::initialize_itable requires that, when a class fills
2299 // in its itables, for each non-abstract method installed in an
2300 // itable, the method (i.e., the callee) agree with the interface
2301 // on each type in the method's signature.
2302 //
2303 // All those methods have a boolean (check_access, checkconstraints)
2304 // which turns off the checks. This is used from specialized contexts
2305 // such as bootstrapping, dumping, and debugging.
2306 //
2307 // No direct constraint is placed between the class and its
2308 // supertypes. Constraints are only placed along linked relations
2309 // between callers and callees. When a method overrides or implements
2310 // an abstract method in a supertype (superclass or interface), the
2311 // constraints are placed as if the supertype were the caller to the
2312 // overriding method. (This works well, since callers to the
2313 // supertype have already established agreement between themselves and
2314 // the supertype.) As a result of all this, a class can disagree with
2315 // its supertype about the meaning of a type name, as long as that
2316 // class neither calls a relevant method of the supertype, nor is
2317 // called (perhaps via an override) from the supertype.
2318 //
2319 //
2320 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2321 //
2322 // Make sure all class components (including arrays) in the given
2323 // signature will be resolved to the same class in both loaders.
2324 // Returns the name of the type that failed a loader constraint check, or
2325 // NULL if no constraint failed. No exception except OOME is thrown.
2326 // Arrays are not added to the loader constraint table, their elements are.
2327 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2328 Handle loader1, Handle loader2,
2329 bool is_method, TRAPS) {
2330 // Nothing to do if loaders are the same.
2331 if (loader1() == loader2()) {
2332 return NULL;
2333 }
2334
2335 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2336 if (ss.is_reference()) {
2337 Symbol* sig = ss.as_symbol();
2338 // Note: In the future, if template-like types can take
2339 // arguments, we will want to recognize them and dig out class
2340 // names hiding inside the argument lists.
2341 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2342 return sig;
2343 }
2344 }
2345 }
2346 return NULL;
2347 }
2348
2349
2350 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2351 Symbol* signature,
2352 TRAPS) {
2353 methodHandle empty;
2354 assert(MethodHandles::is_signature_polymorphic(iid) &&
2355 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2356 iid != vmIntrinsics::_invokeGeneric,
2357 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2358
2359 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2360 int index = invoke_method_table()->hash_to_index(hash);
2361 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2362 methodHandle m;
2363 if (spe == NULL || spe->method() == NULL) {
2364 spe = NULL;
2365 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2366 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
2367 if (!Arguments::is_interpreter_only()) {
2368 // Generate a compiled form of the MH intrinsic.
2369 AdapterHandlerLibrary::create_native_wrapper(m);
2370 // Check if have the compiled code.
2371 if (!m->has_compiled_code()) {
2372 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2373 "Out of space in CodeCache for method handle intrinsic");
2374 }
2375 }
2376 // Now grab the lock. We might have to throw away the new method,
2377 // if a racing thread has managed to install one at the same time.
2378 {
2379 MutexLocker ml(THREAD, SystemDictionary_lock);
2380 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2381 if (spe == NULL)
2382 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2383 if (spe->method() == NULL)
2384 spe->set_method(m());
2385 }
2386 }
2387
2388 assert(spe != NULL && spe->method() != NULL, "");
2389 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2390 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2391 "MH intrinsic invariant");
2392 return spe->method();
2393 }
2394
2395 // Helper for unpacking the return value from linkMethod and linkCallSite.
2396 static Method* unpack_method_and_appendix(Handle mname,
2397 Klass* accessing_klass,
2398 objArrayHandle appendix_box,
2399 Handle* appendix_result,
2400 TRAPS) {
2401 if (mname.not_null()) {
2402 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2403 if (m != NULL) {
2404 oop appendix = appendix_box->obj_at(0);
2405 if (TraceMethodHandles) {
2406 #ifndef PRODUCT
2407 ttyLocker ttyl;
2408 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2409 m->print();
2410 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2411 tty->cr();
2412 #endif //PRODUCT
2413 }
2414 (*appendix_result) = Handle(THREAD, appendix);
2415 // the target is stored in the cpCache and if a reference to this
2416 // MemberName is dropped we need a way to make sure the
2417 // class_loader containing this method is kept alive.
2418 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2419 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2420 this_key->record_dependency(m->method_holder());
2421 return mh();
2422 }
2423 }
2424 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2425 }
2426
2427 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2428 Symbol* name,
2429 Symbol* signature,
2430 Klass* accessing_klass,
2431 Handle *appendix_result,
2432 TRAPS) {
2433 assert(THREAD->can_call_java() ,"");
2434 Handle method_type =
2435 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2436
2437 int ref_kind = JVM_REF_invokeVirtual;
2438 oop name_oop = StringTable::intern(name, CHECK_NULL);
2439 Handle name_str (THREAD, name_oop);
2440 objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_NULL);
2441 assert(appendix_box->obj_at(0) == NULL, "");
2442
2443 // This should not happen. JDK code should take care of that.
2444 if (accessing_klass == NULL || method_type.is_null()) {
2445 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2446 }
2447
2448 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2449 JavaCallArguments args;
2450 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2451 args.push_int(ref_kind);
2452 args.push_oop(Handle(THREAD, klass->java_mirror()));
2453 args.push_oop(name_str);
2454 args.push_oop(method_type);
2455 args.push_oop(appendix_box);
2456 JavaValue result(T_OBJECT);
2457 JavaCalls::call_static(&result,
2458 SystemDictionary::MethodHandleNatives_klass(),
2459 vmSymbols::linkMethod_name(),
2460 vmSymbols::linkMethod_signature(),
2461 &args, CHECK_NULL);
2462 Handle mname(THREAD, (oop) result.get_jobject());
2463 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2464 }
2465
2466 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2467 // We must ensure that all class loaders everywhere will reach this class, for any client.
2468 // This is a safe bet for public classes in java.lang, such as Object and String.
2469 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2470 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2471 static bool is_always_visible_class(oop mirror) {
2472 Klass* klass = java_lang_Class::as_Klass(mirror);
2473 if (klass->is_objArray_klass()) {
2474 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2475 }
2476 if (klass->is_typeArray_klass()) {
2477 return true; // primitive array
2478 }
2479 assert(klass->is_instance_klass(), "%s", klass->external_name());
2480 return klass->is_public() &&
2481 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2482 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2483 }
2484
2485 // Find or construct the Java mirror (java.lang.Class instance) for a
2486 // for the given field type signature, as interpreted relative to the
2487 // given class loader. Handles primitives, void, references, arrays,
2488 // and all other reflectable types, except method types.
2489 // N.B. Code in reflection should use this entry point.
2490 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2491 Klass* accessing_klass,
2492 Handle class_loader,
2493 Handle protection_domain,
2494 SignatureStream::FailureMode failure_mode,
2495 TRAPS) {
2496 Handle empty;
2497
2498 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2499 "one or the other, or perhaps neither");
2500
2501 SignatureStream ss(signature, false);
2502
2503 // What we have here must be a valid field descriptor,
2504 // and all valid field descriptors are supported.
2505 // Produce the same java.lang.Class that reflection reports.
2506 if (ss.is_primitive() || (ss.type() == T_VOID)) {
2507
2508 // It's a primitive. (Void has a primitive mirror too.)
2509 return Handle(THREAD, java_lang_Class::primitive_mirror(ss.type()));
2510
2511 } else if (ss.is_reference()) {
2512
2513 // It's a reference type.
2514 if (accessing_klass != NULL) {
2515 class_loader = Handle(THREAD, accessing_klass->class_loader());
2516 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2517 }
2518 Klass* constant_type_klass;
2519 if (failure_mode == SignatureStream::ReturnNull) {
2520 constant_type_klass = resolve_or_null(signature, class_loader, protection_domain,
2521 CHECK_(empty));
2522 } else {
2523 bool throw_error = (failure_mode == SignatureStream::NCDFError);
2524 constant_type_klass = resolve_or_fail(signature, class_loader, protection_domain,
2525 throw_error, CHECK_(empty));
2526 }
2527 if (constant_type_klass == NULL) {
2528 return Handle(); // report failure this way
2529 }
2530 Handle mirror(THREAD, constant_type_klass->java_mirror());
2531
2532 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2533 if (accessing_klass != NULL) {
2534 Klass* sel_klass = constant_type_klass;
2535 bool fold_type_to_class = true;
2536 LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2537 fold_type_to_class, CHECK_(empty));
2538 }
2539
2540 return mirror;
2541
2542 }
2543
2544 // Fall through to an error.
2545 assert(false, "unsupported mirror syntax");
2546 THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2547 }
2548
2549
2550 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2551 // signature, as interpreted relative to the given class loader.
2552 // Because of class loader constraints, all method handle usage must be
2553 // consistent with this loader.
2554 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2555 Klass* accessing_klass,
2556 TRAPS) {
2557 Handle empty;
2558 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2559 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2560 int index = invoke_method_table()->hash_to_index(hash);
2561 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2562 if (spe != NULL && spe->method_type() != NULL) {
2563 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2564 return Handle(THREAD, spe->method_type());
2565 } else if (!THREAD->can_call_java()) {
2566 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2567 return Handle(); // do not attempt from within compiler, unless it was cached
2568 }
2569
2570 Handle class_loader, protection_domain;
2571 if (accessing_klass != NULL) {
2572 class_loader = Handle(THREAD, accessing_klass->class_loader());
2573 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2574 }
2575 bool can_be_cached = true;
2576 int npts = ArgumentCount(signature).size();
2577 objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2578 int arg = 0;
2579 Handle rt; // the return type from the signature
2580 ResourceMark rm(THREAD);
2581 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2582 oop mirror = NULL;
2583 if (can_be_cached) {
2584 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2585 mirror = ss.as_java_mirror(Handle(), Handle(),
2586 SignatureStream::ReturnNull, CHECK_(empty));
2587 if (mirror == NULL || (ss.is_reference() && !is_always_visible_class(mirror))) {
2588 // Fall back to accessing_klass context.
2589 can_be_cached = false;
2590 }
2591 }
2592 if (!can_be_cached) {
2593 // Resolve, throwing a real error if it doesn't work.
2594 mirror = ss.as_java_mirror(class_loader, protection_domain,
2595 SignatureStream::NCDFError, CHECK_(empty));
2596 }
2597 assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
2598 if (ss.at_return_type())
2599 rt = Handle(THREAD, mirror);
2600 else
2601 pts->obj_at_put(arg++, mirror);
2602
2603 // Check accessibility.
2604 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2605 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2606 mirror = NULL; // safety
2607 // Emulate ConstantPool::verify_constant_pool_resolve.
2608 bool fold_type_to_class = true;
2609 LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2610 fold_type_to_class, CHECK_(empty));
2611 }
2612 }
2613 assert(arg == npts, "");
2614
2615 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2616 JavaCallArguments args(Handle(THREAD, rt()));
2617 args.push_oop(pts);
2618 JavaValue result(T_OBJECT);
2619 JavaCalls::call_static(&result,
2620 SystemDictionary::MethodHandleNatives_klass(),
2621 vmSymbols::findMethodHandleType_name(),
2622 vmSymbols::findMethodHandleType_signature(),
2623 &args, CHECK_(empty));
2624 Handle method_type(THREAD, (oop) result.get_jobject());
2625
2626 if (can_be_cached) {
2627 // We can cache this MethodType inside the JVM.
2628 MutexLocker ml(THREAD, SystemDictionary_lock);
2629 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2630 if (spe == NULL)
2631 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2632 if (spe->method_type() == NULL) {
2633 spe->set_method_type(method_type());
2634 }
2635 }
2636
2637 // report back to the caller with the MethodType
2638 return method_type;
2639 }
2640
2641 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2642 Klass* accessing_klass,
2643 TRAPS) {
2644 Handle empty;
2645 ResourceMark rm(THREAD);
2646 SignatureStream ss(signature, /*is_method=*/ false);
2647 if (!ss.is_done()) {
2648 Handle class_loader, protection_domain;
2649 if (accessing_klass != NULL) {
2650 class_loader = Handle(THREAD, accessing_klass->class_loader());
2651 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2652 }
2653 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2654 ss.next();
2655 if (ss.is_done()) {
2656 return Handle(THREAD, mirror);
2657 }
2658 }
2659 return empty;
2660 }
2661
2662 // Ask Java code to find or construct a method handle constant.
2663 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2664 int ref_kind, //e.g., JVM_REF_invokeVirtual
2665 Klass* callee,
2666 Symbol* name,
2667 Symbol* signature,
2668 TRAPS) {
2669 Handle empty;
2670 if (caller == NULL) {
2671 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2672 }
2673 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2674 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2675
2676 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2677 Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2678 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2679 java_lang_invoke_MemberName::set_name (mname(), name_str());
2680 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2681 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2682
2683 if (ref_kind == JVM_REF_invokeVirtual &&
2684 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2685 // Skip resolution for public signature polymorphic methods such as
2686 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2687 // They require appendix argument which MemberName resolution doesn't handle.
2688 // There's special logic on JDK side to handle them
2689 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2690 } else {
2691 MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2692 }
2693
2694 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2695 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2696
2697 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2698 JavaCallArguments args;
2699 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2700 args.push_int(ref_kind);
2701 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2702 args.push_oop(name_str);
2703 args.push_oop(type);
2704 JavaValue result(T_OBJECT);
2705 JavaCalls::call_static(&result,
2706 SystemDictionary::MethodHandleNatives_klass(),
2707 vmSymbols::linkMethodHandleConstant_name(),
2708 vmSymbols::linkMethodHandleConstant_signature(),
2709 &args, CHECK_(empty));
2710 return Handle(THREAD, (oop) result.get_jobject());
2711 }
2712
2713 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2714 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2715 // with linkage results being stored back into the bootstrap specifier.
2716 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2717 // Resolve the bootstrap specifier, its name, type, and static arguments
2718 bootstrap_specifier.resolve_bsm(CHECK);
2719
2720 // This should not happen. JDK code should take care of that.
2721 if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2722 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2723 }
2724
2725 bool is_indy = bootstrap_specifier.is_method_call();
2726 objArrayHandle appendix_box;
2727 if (is_indy) {
2728 // Some method calls may require an appendix argument. Arrange to receive it.
2729 appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK);
2730 assert(appendix_box->obj_at(0) == NULL, "");
2731 }
2732
2733 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info)
2734 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2735 JavaCallArguments args;
2736 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2737 args.push_int(bootstrap_specifier.bss_index());
2738 args.push_oop(bootstrap_specifier.bsm());
2739 args.push_oop(bootstrap_specifier.name_arg());
2740 args.push_oop(bootstrap_specifier.type_arg());
2741 args.push_oop(bootstrap_specifier.arg_values());
2742 if (is_indy) {
2743 args.push_oop(appendix_box);
2744 }
2745 JavaValue result(T_OBJECT);
2746 JavaCalls::call_static(&result,
2747 SystemDictionary::MethodHandleNatives_klass(),
2748 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2749 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2750 &args, CHECK);
2751
2752 Handle value(THREAD, (oop) result.get_jobject());
2753 if (is_indy) {
2754 Handle appendix;
2755 Method* method = unpack_method_and_appendix(value,
2756 bootstrap_specifier.caller(),
2757 appendix_box,
2758 &appendix, CHECK);
2759 methodHandle mh(THREAD, method);
2760 bootstrap_specifier.set_resolved_method(mh, appendix);
2761 } else {
2762 bootstrap_specifier.set_resolved_value(value);
2763 }
2764
2765 // sanity check
2766 assert(bootstrap_specifier.is_resolved() ||
2767 (bootstrap_specifier.is_method_call() &&
2768 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2769 }
2770
2771 // Protection domain cache table handling
2772
2773 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2774 return _pd_cache_table->get(protection_domain);
2775 }
2776
2777 // ----------------------------------------------------------------------------
2778
2779 void SystemDictionary::print_on(outputStream *st) {
2780 CDS_ONLY(SystemDictionaryShared::print_on(st));
2781 GCMutexLocker mu(SystemDictionary_lock);
2782
2783 ClassLoaderDataGraph::print_dictionary(st);
2784
2785 // Placeholders
2786 placeholders()->print_on(st);
2787 st->cr();
2788
2789 // loader constraints - print under SD_lock
2790 constraints()->print_on(st);
2791 st->cr();
2792
2793 _pd_cache_table->print_on(st);
2794 st->cr();
2795 }
2796
2797 void SystemDictionary::print() { print_on(tty); }
2798
2799 void SystemDictionary::verify() {
2800 guarantee(constraints() != NULL,
2801 "Verify of loader constraints failed");
2802 guarantee(placeholders()->number_of_entries() >= 0,
2803 "Verify of placeholders failed");
2804
2805 GCMutexLocker mu(SystemDictionary_lock);
2806
2807 // Verify dictionary
2808 ClassLoaderDataGraph::verify_dictionary();
2809
2810 placeholders()->verify();
2811
2812 // Verify constraint table
2813 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2814 constraints()->verify(placeholders());
2815
2816 _pd_cache_table->verify();
2817 }
2818
2819 void SystemDictionary::dump(outputStream *st, bool verbose) {
2820 assert_locked_or_safepoint(SystemDictionary_lock);
2821 if (verbose) {
2822 print_on(st);
2823 } else {
2824 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2825 ClassLoaderDataGraph::print_table_statistics(st);
2826 placeholders()->print_table_statistics(st, "Placeholder Table");
2827 constraints()->print_table_statistics(st, "LoaderConstraints Table");
2828 pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table");
2829 }
2830 }
2831
2832 TableStatistics SystemDictionary::placeholders_statistics() {
2833 MutexLocker ml(SystemDictionary_lock);
2834 return placeholders()->statistics_calculate();
2835 }
2836
2837 TableStatistics SystemDictionary::loader_constraints_statistics() {
2838 MutexLocker ml(SystemDictionary_lock);
2839 return constraints()->statistics_calculate();
2840 }
2841
2842 TableStatistics SystemDictionary::protection_domain_cache_statistics() {
2843 MutexLocker ml(SystemDictionary_lock);
2844 return pd_cache_table()->statistics_calculate();
2845 }
2846
2847 // Utility for dumping dictionaries.
2848 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2849 DCmdWithParser(output, heap),
2850 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2851 "BOOLEAN", false, "false") {
2852 _dcmdparser.add_dcmd_option(&_verbose);
2853 }
2854
2855 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2856 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2857 _verbose.value());
2858 VMThread::execute(&dumper);
2859 }
2860
2861 int SystemDictionaryDCmd::num_arguments() {
2862 ResourceMark rm;
2863 SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2864 if (dcmd != NULL) {
2865 DCmdMark mark(dcmd);
2866 return dcmd->_dcmdparser.num_arguments();
2867 } else {
2868 return 0;
2869 }
2870 }