1 /*
2 * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/packageEntry.hpp"
40 #include "classfile/placeholders.hpp"
41 #include "classfile/protectionDomainCache.hpp"
42 #include "classfile/resolutionErrors.hpp"
43 #include "classfile/stringTable.hpp"
44 #include "classfile/symbolTable.hpp"
45 #include "classfile/systemDictionary.hpp"
46 #include "classfile/vmClasses.hpp"
47 #include "classfile/vmSymbols.hpp"
48 #include "code/codeCache.hpp"
49 #include "gc/shared/gcTraceTime.inline.hpp"
50 #include "interpreter/bootstrapInfo.hpp"
51 #include "jfr/jfrEvents.hpp"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/metaspaceClosure.hpp"
55 #include "memory/oopFactory.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/fieldStreams.inline.hpp"
60 #include "oops/instanceKlass.hpp"
61 #include "oops/klass.inline.hpp"
62 #include "oops/method.inline.hpp"
63 #include "oops/objArrayKlass.hpp"
64 #include "oops/objArrayOop.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oopHandle.inline.hpp"
67 #include "oops/symbol.hpp"
68 #include "oops/typeArrayKlass.hpp"
69 #include "oops/inlineKlass.inline.hpp"
70 #include "prims/jvmtiExport.hpp"
71 #include "prims/methodHandles.hpp"
72 #include "runtime/arguments.hpp"
73 #include "runtime/handles.inline.hpp"
74 #include "runtime/java.hpp"
75 #include "runtime/javaCalls.hpp"
76 #include "runtime/mutexLocker.hpp"
77 #include "runtime/os.hpp"
78 #include "runtime/sharedRuntime.hpp"
79 #include "runtime/signature.hpp"
80 #include "services/classLoadingService.hpp"
81 #include "services/diagnosticCommand.hpp"
82 #include "services/threadService.hpp"
83 #include "utilities/macros.hpp"
84 #include "utilities/utf8.hpp"
85 #if INCLUDE_CDS
86 #include "classfile/systemDictionaryShared.hpp"
87 #endif
88 #if INCLUDE_JFR
89 #include "jfr/jfr.hpp"
90 #endif
91
92 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
93 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
94 ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
95
96 OopHandle SystemDictionary::_java_system_loader;
97 OopHandle SystemDictionary::_java_platform_loader;
98
99 // Default ProtectionDomainCacheSize value
100 const int defaultProtectionDomainCacheSize = 1009;
101
102 const int _resolution_error_size = 107; // number of entries in resolution error table
103 const int _invoke_method_size = 139; // number of entries in invoke method table
104
105 // Hashtable holding placeholders for classes being loaded.
106 const int _placeholder_table_size = 1009;
107 static PlaceholderTable* _placeholders = NULL;
108 static PlaceholderTable* placeholders() { return _placeholders; }
109
110 // Constraints on class loaders
111 const int _loader_constraint_size = 107; // number of entries in constraint table
112 static LoaderConstraintTable* _loader_constraints;
113 static LoaderConstraintTable* constraints() { return _loader_constraints; }
114
115 // ----------------------------------------------------------------------------
116 // Java-level SystemLoader and PlatformLoader
117 oop SystemDictionary::java_system_loader() {
118 return _java_system_loader.resolve();
119 }
120
121 oop SystemDictionary::java_platform_loader() {
122 return _java_platform_loader.resolve();
123 }
124
125 void SystemDictionary::compute_java_loaders(TRAPS) {
126 JavaValue result(T_OBJECT);
127 InstanceKlass* class_loader_klass = vmClasses::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 = OopHandle(Universe::vm_global(), result.get_oop());
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 = OopHandle(Universe::vm_global(), result.get_oop());
143 }
144
145 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
146 if (create_mirror_cld) {
147 // Add a new class loader data to the graph.
148 return ClassLoaderDataGraph::add(class_loader, true);
149 } else {
150 return (class_loader() == NULL) ? ClassLoaderData::the_null_class_loader_data() :
151 ClassLoaderDataGraph::find_or_create(class_loader);
152 }
153 }
154
155 // ----------------------------------------------------------------------------
156 // Parallel class loading check
157
158 bool is_parallelCapable(Handle class_loader) {
159 if (class_loader.is_null()) return true;
160 return java_lang_ClassLoader::parallelCapable(class_loader());
161 }
162 // ----------------------------------------------------------------------------
163 // ParallelDefineClass flag does not apply to bootclass loader
164 bool is_parallelDefine(Handle class_loader) {
165 if (class_loader.is_null()) return false;
166 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
167 return true;
168 }
169 return false;
170 }
171
172 // Returns true if the passed class loader is the builtin application class loader
173 // or a custom system class loader. A customer system class loader can be
174 // specified via -Djava.system.class.loader.
175 bool SystemDictionary::is_system_class_loader(oop class_loader) {
176 if (class_loader == NULL) {
177 return false;
178 }
179 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
180 class_loader == _java_system_loader.peek());
181 }
182
183 // Returns true if the passed class loader is the platform class loader.
184 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
185 if (class_loader == NULL) {
186 return false;
187 }
188 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
189 }
190
191 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
192 // If class_loader is NULL or parallelCapable, the JVM doesn't acquire a lock while loading.
193 if (is_parallelCapable(class_loader)) {
194 return Handle();
195 } else {
196 return class_loader;
197 }
198 }
199
200 // ----------------------------------------------------------------------------
201 // Resolving of classes
202
203 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
204 if (name == NULL) {
205 THROW_MSG_0(exception, "No class name given");
206 }
207 if ((int)strlen(name) > Symbol::max_length()) {
208 // It's impossible to create this class; the name cannot fit
209 // into the constant pool.
210 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
211 "Class name exceeds maximum length of %d: %s",
212 Symbol::max_length(),
213 name);
214 return NULL;
215 }
216 // Callers should ensure that the name is never an illegal UTF8 string.
217 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
218 "Class name is not a valid utf8 string.");
219
220 // Make a new symbol for the class name.
221 return SymbolTable::new_symbol(name);
222 }
223
224 #ifdef ASSERT
225 // Used to verify that class loading succeeded in adding k to the dictionary.
226 void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
227 MutexLocker mu(SystemDictionary_lock);
228 ClassLoaderData* loader_data = k->class_loader_data();
229 Dictionary* dictionary = loader_data->dictionary();
230 assert(class_name == k->name(), "Must be the same");
231 unsigned int name_hash = dictionary->compute_hash(class_name);
232 InstanceKlass* kk = dictionary->find_class(name_hash, class_name);
233 assert(kk == k, "should be present in dictionary");
234 }
235 #endif
236
237 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
238 if (HAS_PENDING_EXCEPTION) {
239 // If we have a pending exception we forward it to the caller, unless throw_error is true,
240 // in which case we have to check whether the pending exception is a ClassNotFoundException,
241 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
242 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
243 ResourceMark rm(THREAD);
244 Handle e(THREAD, PENDING_EXCEPTION);
245 CLEAR_PENDING_EXCEPTION;
246 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
247 } else {
248 return; // the caller will throw the incoming exception
249 }
250 }
251 // If the class is not found, ie, caller has checked that klass is NULL, throw the appropriate
252 // error or exception depending on the value of throw_error.
253 ResourceMark rm(THREAD);
254 if (throw_error) {
255 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
256 } else {
257 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
258 }
259 }
260
261 // Forwards to resolve_or_null
262
263 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
264 bool throw_error, TRAPS) {
265 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
266 // Check for pending exception or null klass, and throw exception
267 if (HAS_PENDING_EXCEPTION || klass == NULL) {
268 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
269 }
270 return klass;
271 }
272
273 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
274
275 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
276 if (Signature::is_array(class_name)) {
277 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
278 } else {
279 return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
280 }
281 }
282
283 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
284 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
285 Handle class_loader,
286 Handle protection_domain,
287 TRAPS) {
288 assert(class_name != NULL && !Signature::is_array(class_name), "must be");
289 if (Signature::has_envelope(class_name)) {
290 ResourceMark rm(THREAD);
291 // Ignore wrapping L and ;. (and Q and ; for value types);
292 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
293 class_name->utf8_length() - 2);
294 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
295 } else {
296 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
297 }
298 }
299
300 // Forwards to resolve_instance_class_or_null
301
302 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
303 Handle class_loader,
304 Handle protection_domain,
305 TRAPS) {
306 assert(Signature::is_array(class_name), "must be array");
307 ResourceMark rm(THREAD);
308 SignatureStream ss(class_name, false);
309 int ndims = ss.skip_array_prefix(); // skip all '['s
310 Klass* k = NULL;
311 BasicType t = ss.type();
312 if (ss.has_envelope()) {
313 Symbol* obj_class = ss.as_symbol();
314 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
315 class_loader,
316 protection_domain,
317 CHECK_NULL);
318 if (k != NULL) {
319 if (class_name->is_Q_array_signature()) {
320 if (!k->is_inline_klass()) {
321 THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), "L/Q mismatch on bottom type");
322 }
323 k = InlineKlass::cast(k)->null_free_inline_array_klass(ndims, CHECK_NULL);
324 } else {
325 k = k->array_klass(ndims, CHECK_NULL);
326 }
327 }
328 } else {
329 k = Universe::typeArrayKlassObj(t);
330 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
331 }
332 return k;
333 }
334
335 static inline void log_circularity_error(Thread* thread, PlaceholderEntry* probe) {
336 LogTarget(Debug, class, load, placeholders) lt;
337 if (lt.is_enabled()) {
338 ResourceMark rm(thread);
339 LogStream ls(lt);
340 ls.print("ClassCircularityError detected for placeholder ");
341 probe->print_entry(&ls);
342 ls.cr();
343 }
344 }
345
346 // Must be called for any superclass or superinterface resolution
347 // during class definition to allow class circularity checking
348 // superinterface callers:
349 // parse_interfaces - from defineClass
350 // superclass callers:
351 // ClassFileParser - from defineClass
352 // load_shared_class - while loading a class from shared archive
353 // resolve_instance_class_or_null:
354 // via: handle_parallel_super_load
355 // when resolving a class that has an existing placeholder with
356 // a saved superclass [i.e. a defineClass is currently in progress]
357 // If another thread is trying to resolve the class, it must do
358 // superclass checks on its own thread to catch class circularity and
359 // to avoid deadlock.
360 //
361 // resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
362 // resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
363 // placeholder for the same thread, class, classloader is found.
364 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
365 //
366 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
367 Symbol* super_name,
368 Handle class_loader,
369 Handle protection_domain,
370 bool is_superclass,
371 TRAPS) {
372
373 assert(super_name != NULL, "null superclass for resolving");
374 assert(!Signature::is_array(super_name), "invalid superclass name");
375 #if INCLUDE_CDS
376 if (DumpSharedSpaces) {
377 // Special processing for handling UNREGISTERED shared classes.
378 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
379 super_name, is_superclass);
380 if (k) {
381 return k;
382 }
383 }
384 #endif // INCLUDE_CDS
385
386 // If klass is already loaded, just return the superclass or superinterface.
387 // Make sure there's a placeholder for the class_name before resolving.
388 // This is used as a claim that this thread is currently loading superclass/classloader
389 // and for ClassCircularity checks.
390
391 ClassLoaderData* loader_data = class_loader_data(class_loader);
392 Dictionary* dictionary = loader_data->dictionary();
393 unsigned int name_hash = dictionary->compute_hash(class_name);
394 assert(placeholders()->compute_hash(class_name) == name_hash, "they're the same hashcode");
395
396 // can't throw error holding a lock
397 bool throw_circularity_error = false;
398 {
399 MutexLocker mu(THREAD, SystemDictionary_lock);
400 InstanceKlass* klassk = dictionary->find_class(name_hash, class_name);
401 InstanceKlass* quicksuperk;
402 // To support parallel loading: if class is done loading, just return the superclass
403 // if the super_name matches class->super()->name() and if the class loaders match.
404 // Otherwise, a LinkageError will be thrown later.
405 if (klassk != NULL && is_superclass &&
406 ((quicksuperk = klassk->java_super()) != NULL) &&
407 ((quicksuperk->name() == super_name) &&
408 (quicksuperk->class_loader() == class_loader()))) {
409 return quicksuperk;
410 } else {
411 // Must check ClassCircularity before checking if superclass is already loaded.
412 PlaceholderEntry* probe = placeholders()->get_entry(name_hash, class_name, loader_data);
413 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
414 log_circularity_error(THREAD, probe);
415 throw_circularity_error = true;
416 }
417 }
418
419 if (!throw_circularity_error) {
420 // Be careful not to exit resolve_super without removing this placeholder.
421 PlaceholderEntry* newprobe = placeholders()->find_and_add(name_hash,
422 class_name,
423 loader_data,
424 PlaceholderTable::LOAD_SUPER,
425 super_name, THREAD);
426 }
427 }
428
429 if (throw_circularity_error) {
430 ResourceMark rm(THREAD);
431 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
432 }
433
434 // Resolve the superclass or superinterface, check results on return
435 InstanceKlass* superk =
436 SystemDictionary::resolve_instance_class_or_null_helper(super_name,
437 class_loader,
438 protection_domain,
439 THREAD);
440
441 // Clean up placeholder entry.
442 {
443 MutexLocker mu(THREAD, SystemDictionary_lock);
444 placeholders()->find_and_remove(name_hash, class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
445 SystemDictionary_lock->notify_all();
446 }
447
448 // Check for pending exception or null superk, and throw exception
449 if (HAS_PENDING_EXCEPTION || superk == NULL) {
450 handle_resolution_exception(super_name, true, CHECK_NULL);
451 }
452
453 return superk;
454 }
455
456 Klass* SystemDictionary::resolve_inline_type_field_or_fail(AllFieldStream* fs,
457 Handle class_loader,
458 Handle protection_domain,
459 bool throw_error,
460 TRAPS) {
461 Symbol* class_name = fs->signature()->fundamental_name(THREAD);
462 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
463 ClassLoaderData* loader_data = class_loader_data(class_loader);
464 unsigned int p_hash = placeholders()->compute_hash(class_name);
465 bool throw_circularity_error = false;
466 PlaceholderEntry* oldprobe;
467
468 {
469 MutexLocker mu(THREAD, SystemDictionary_lock);
470 oldprobe = placeholders()->get_entry(p_hash, class_name, loader_data);
471 if (oldprobe != NULL &&
472 oldprobe->check_seen_thread(THREAD, PlaceholderTable::INLINE_TYPE_FIELD)) {
473 throw_circularity_error = true;
474
475 } else {
476 placeholders()->find_and_add(p_hash, class_name, loader_data,
477 PlaceholderTable::INLINE_TYPE_FIELD, NULL, THREAD);
478 }
479 }
480
481 Klass* klass = NULL;
482 if (!throw_circularity_error) {
483 klass = SystemDictionary::resolve_or_fail(class_name, class_loader,
484 protection_domain, true, THREAD);
485 } else {
486 ResourceMark rm(THREAD);
487 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
488 }
489
490 {
491 MutexLocker mu(THREAD, SystemDictionary_lock);
492 placeholders()->find_and_remove(p_hash, class_name, loader_data,
493 PlaceholderTable::INLINE_TYPE_FIELD, THREAD);
494 }
495
496 class_name->decrement_refcount();
497 return klass;
498 }
499
500 // We only get here if this thread finds that another thread
501 // has already claimed the placeholder token for the current operation,
502 // but that other thread either never owned or gave up the
503 // object lock
504 // Waits on SystemDictionary_lock to indicate placeholder table updated
505 // On return, caller must recheck placeholder table state
506 //
507 // We only get here if
508 // 1) custom classLoader, i.e. not bootstrap classloader
509 // 2) custom classLoader has broken the class loader objectLock
510 // so another thread got here in parallel
511 //
512 // lockObject must be held.
513 // Complicated dance due to lock ordering:
514 // Must first release the classloader object lock to
515 // allow initial definer to complete the class definition
516 // and to avoid deadlock
517 // Reclaim classloader lock object with same original recursion count
518 // Must release SystemDictionary_lock after notify, since
519 // class loader lock must be claimed before SystemDictionary_lock
520 // to prevent deadlocks
521 //
522 // The notify allows applications that did an untimed wait() on
523 // the classloader object lock to not hang.
524 static void double_lock_wait(JavaThread* thread, Handle lockObject) {
525 assert_lock_strong(SystemDictionary_lock);
526
527 assert(lockObject() != NULL, "lockObject must be non-NULL");
528 bool calledholdinglock
529 = ObjectSynchronizer::current_thread_holds_lock(thread, lockObject);
530 assert(calledholdinglock, "must hold lock for notify");
531 assert(!is_parallelCapable(lockObject), "lockObject must not be parallelCapable");
532 // These don't throw exceptions.
533 ObjectSynchronizer::notifyall(lockObject, thread);
534 intx recursions = ObjectSynchronizer::complete_exit(lockObject, thread);
535 SystemDictionary_lock->wait();
536 SystemDictionary_lock->unlock();
537 ObjectSynchronizer::reenter(lockObject, recursions, thread);
538 SystemDictionary_lock->lock();
539 }
540
541 // If the class in is in the placeholder table, class loading is in progress.
542 // For cases where the application changes threads to load classes, it
543 // is critical to ClassCircularity detection that we try loading
544 // the superclass on the new thread internally, so we do parallel
545 // superclass loading here. This avoids deadlock for ClassCircularity
546 // detection for parallelCapable class loaders that lock on a per-class lock.
547 static void handle_parallel_super_load(Symbol* name,
548 Symbol* superclassname,
549 Handle class_loader,
550 Handle protection_domain, TRAPS) {
551
552 // superk is not used; resolve_super_or_fail is called for circularity check only.
553 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
554 superclassname,
555 class_loader,
556 protection_domain,
557 true,
558 CHECK);
559 }
560
561 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
562 // Serial class loaders and bootstrap classloader do wait for superclass loads
563 static bool should_wait_for_loading(Handle class_loader) {
564 return class_loader.is_null() || !is_parallelCapable(class_loader);
565 }
566
567 // For bootstrap and non-parallelCapable class loaders, check and wait for
568 // another thread to complete loading this class.
569 InstanceKlass* SystemDictionary::handle_parallel_loading(JavaThread* current,
570 unsigned int name_hash,
571 Symbol* name,
572 ClassLoaderData* loader_data,
573 Handle lockObject,
574 bool* throw_circularity_error) {
575 PlaceholderEntry* oldprobe = placeholders()->get_entry(name_hash, name, loader_data);
576 if (oldprobe != NULL) {
577 // only need check_seen_thread once, not on each loop
578 // 6341374 java/lang/Instrument with -Xcomp
579 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
580 log_circularity_error(current, oldprobe);
581 *throw_circularity_error = true;
582 return NULL;
583 } else {
584 // Wait until the first thread has finished loading this class. Also wait until all the
585 // threads trying to load its superclass have removed their placeholders.
586 while (oldprobe != NULL &&
587 (oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {
588
589 // We only get here if the application has released the
590 // classloader lock when another thread was in the middle of loading a
591 // superclass/superinterface for this class, and now
592 // this thread is also trying to load this class.
593 // To minimize surprises, the first thread that started to
594 // load a class should be the one to complete the loading
595 // with the classfile it initially expected.
596 // This logic has the current thread wait once it has done
597 // all the superclass/superinterface loading it can, until
598 // the original thread completes the class loading or fails
599 // If it completes we will use the resulting InstanceKlass
600 // which we will find below in the systemDictionary.
601 oldprobe = NULL; // Other thread could delete this placeholder entry
602
603 if (lockObject.is_null()) {
604 SystemDictionary_lock->wait();
605 } else {
606 double_lock_wait(current, lockObject);
607 }
608
609 // Check if classloading completed while we were waiting
610 InstanceKlass* check = loader_data->dictionary()->find_class(name_hash, name);
611 if (check != NULL) {
612 // Klass is already loaded, so just return it
613 return check;
614 }
615 // check if other thread failed to load and cleaned up
616 oldprobe = placeholders()->get_entry(name_hash, name, loader_data);
617 }
618 }
619 }
620 return NULL;
621 }
622
623 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
624 assert(event != NULL, "invariant");
625 assert(k != NULL, "invariant");
626 assert(event->should_commit(), "invariant");
627 event->set_loadedClass(k);
628 event->set_definingClassLoader(k->class_loader_data());
629 event->set_initiatingClassLoader(init_cld);
630 event->commit();
631 }
632
633 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
634 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
635 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
636 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
637 // This can return NULL, an exception or an InstanceKlass.
638 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
639 Handle class_loader,
640 Handle protection_domain,
641 TRAPS) {
642 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
643 assert(name != NULL && !Signature::is_array(name) &&
644 !Signature::has_envelope(name), "invalid class name");
645
646 EventClassLoad class_load_start_event;
647
648 HandleMark hm(THREAD);
649
650 // Fix for 4474172; see evaluation for more details
651 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
652 ClassLoaderData* loader_data = register_loader(class_loader);
653 Dictionary* dictionary = loader_data->dictionary();
654 unsigned int name_hash = dictionary->compute_hash(name);
655
656 // Do lookup to see if class already exists and the protection domain
657 // has the right access.
658 // This call uses find which checks protection domain already matches
659 // All subsequent calls use find_class, and set loaded_class so that
660 // before we return a result, we call out to java to check for valid protection domain.
661 InstanceKlass* probe = dictionary->find(name_hash, name, protection_domain);
662 if (probe != NULL) return probe;
663
664 // Non-bootstrap class loaders will call out to class loader and
665 // define via jvm/jni_DefineClass which will acquire the
666 // class loader object lock to protect against multiple threads
667 // defining the class in parallel by accident.
668 // This lock must be acquired here so the waiter will find
669 // any successful result in the SystemDictionary and not attempt
670 // the define.
671 // ParallelCapable class loaders and the bootstrap classloader
672 // do not acquire lock here.
673 Handle lockObject = get_loader_lock_or_null(class_loader);
674 ObjectLocker ol(lockObject, THREAD);
675
676 bool super_load_in_progress = false;
677 InstanceKlass* loaded_class = NULL;
678 Symbol* superclassname = NULL;
679
680 assert(THREAD->can_call_java(),
681 "can not load classes with compiler thread: class=%s, classloader=%s",
682 name->as_C_string(),
683 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
684
685 assert(placeholders()->compute_hash(name) == name_hash, "they're the same hashcode");
686
687 // Check again (after locking) if the class already exists in SystemDictionary
688 {
689 MutexLocker mu(THREAD, SystemDictionary_lock);
690 InstanceKlass* check = dictionary->find_class(name_hash, name);
691 if (check != NULL) {
692 // InstanceKlass is already loaded, but we still need to check protection domain below.
693 loaded_class = check;
694 } else {
695 PlaceholderEntry* placeholder = placeholders()->get_entry(name_hash, name, loader_data);
696 if (placeholder != NULL && placeholder->super_load_in_progress()) {
697 super_load_in_progress = true;
698 superclassname = placeholder->supername();
699 assert(superclassname != NULL, "superclass has to have a name");
700 }
701 }
702 }
703
704 // If the class is in the placeholder table with super_class set,
705 // handle superclass loading in progress.
706 if (super_load_in_progress) {
707 handle_parallel_super_load(name, superclassname,
708 class_loader,
709 protection_domain,
710 CHECK_NULL);
711 }
712
713 bool throw_circularity_error = false;
714 if (loaded_class == NULL) {
715 bool load_placeholder_added = false;
716
717 // Add placeholder entry to record loading instance class
718 // Four cases:
719 // case 1. Bootstrap classloader
720 // This classloader supports parallelism at the classloader level
721 // but only allows a single thread to load a class/classloader pair.
722 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
723 // case 2. parallelCapable user level classloaders
724 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
725 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
726 // case 3. traditional classloaders that rely on the classloader object lock
727 // There should be no need for need for LOAD_INSTANCE, except:
728 // case 4. traditional class loaders that break the classloader object lock
729 // as a legacy deadlock workaround. Detection of this case requires that
730 // this check is done while holding the classloader object lock,
731 // and that lock is still held when calling classloader's loadClass.
732 // For these classloaders, we ensure that the first requestor
733 // completes the load and other requestors wait for completion.
734 {
735 MutexLocker mu(THREAD, SystemDictionary_lock);
736 if (should_wait_for_loading(class_loader)) {
737 loaded_class = handle_parallel_loading(THREAD,
738 name_hash,
739 name,
740 loader_data,
741 lockObject,
742 &throw_circularity_error);
743 }
744
745 // Recheck if the class has been loaded for all class loader cases and
746 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
747 if (!throw_circularity_error && loaded_class == NULL) {
748 InstanceKlass* check = dictionary->find_class(name_hash, name);
749 if (check != NULL) {
750 loaded_class = check;
751 } else if (should_wait_for_loading(class_loader)) {
752 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
753 PlaceholderEntry* newprobe = placeholders()->find_and_add(name_hash, name, loader_data,
754 PlaceholderTable::LOAD_INSTANCE,
755 NULL,
756 THREAD);
757 load_placeholder_added = true;
758 }
759 }
760 }
761
762 // Must throw error outside of owning lock
763 if (throw_circularity_error) {
764 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
765 ResourceMark rm(THREAD);
766 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
767 }
768
769 // Be careful when modifying this code: once you have run
770 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
771 // you need to find_and_remove it before returning.
772 // So be careful to not exit with a CHECK_ macro between these calls.
773
774 if (loaded_class == NULL) {
775 // Do actual loading
776 loaded_class = load_instance_class(name_hash, name, class_loader, THREAD);
777 }
778
779 if (load_placeholder_added) {
780 // clean up placeholder entries for LOAD_INSTANCE success or error
781 // This brackets the SystemDictionary updates for both defining
782 // and initiating loaders
783 MutexLocker mu(THREAD, SystemDictionary_lock);
784 placeholders()->find_and_remove(name_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
785 SystemDictionary_lock->notify_all();
786 }
787 }
788
789 if (HAS_PENDING_EXCEPTION || loaded_class == NULL) {
790 return NULL;
791 }
792
793 if (class_load_start_event.should_commit()) {
794 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
795 }
796
797 // Make sure we have the right class in the dictionary
798 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
799
800 // Check if the protection domain is present it has the right access
801 if (protection_domain() != NULL) {
802 // Verify protection domain. If it fails an exception is thrown
803 dictionary->validate_protection_domain(name_hash, loaded_class, class_loader, protection_domain, CHECK_NULL);
804 }
805
806 return loaded_class;
807 }
808
809
810 // This routine does not lock the system dictionary.
811 //
812 // Since readers don't hold a lock, we must make sure that system
813 // dictionary entries are added to in a safe way (all links must
814 // be updated in an MT-safe manner). All entries are removed during class
815 // unloading, when this class loader is no longer referenced.
816 //
817 // Callers should be aware that an entry could be added just after
818 // _dictionary->bucket(index) is read here, so the caller will not see
819 // the new entry.
820
821 InstanceKlass* SystemDictionary::find_instance_klass(Symbol* class_name,
822 Handle class_loader,
823 Handle protection_domain) {
824
825 // The result of this call should be consistent with the result
826 // of the call to resolve_instance_class_or_null().
827 // See evaluation 6790209 and 4474172 for more details.
828 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
829 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
830
831 if (loader_data == NULL) {
832 // If the ClassLoaderData has not been setup,
833 // then the class loader has no entries in the dictionary.
834 return NULL;
835 }
836
837 Dictionary* dictionary = loader_data->dictionary();
838 unsigned int name_hash = dictionary->compute_hash(class_name);
839 return dictionary->find(name_hash, class_name, protection_domain);
840 }
841
842 // Look for a loaded instance or array klass by name. Do not do any loading.
843 // return NULL in case of error.
844 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
845 Handle class_loader,
846 Handle protection_domain) {
847 Klass* k = NULL;
848 assert(class_name != NULL, "class name must be non NULL");
849
850 if (Signature::is_array(class_name)) {
851 // The name refers to an array. Parse the name.
852 // dimension and object_key in FieldArrayInfo are assigned as a
853 // side-effect of this call
854 SignatureStream ss(class_name, false);
855 int ndims = ss.skip_array_prefix(); // skip all '['s
856 BasicType t = ss.type();
857 if (t != T_OBJECT && t != T_INLINE_TYPE) {
858 k = Universe::typeArrayKlassObj(t);
859 } else {
860 k = SystemDictionary::find_instance_klass(ss.as_symbol(), class_loader, protection_domain);
861 }
862 if (k != NULL) {
863 if (class_name->is_Q_array_signature()) {
864 k = InlineKlass::cast(k)->null_free_inline_array_klass_or_null(ndims);
865 } else {
866 k = k->array_klass_or_null(ndims);
867 }
868 }
869 } else {
870 k = find_instance_klass(class_name, class_loader, protection_domain);
871 }
872 return k;
873 }
874
875 // Note: this method is much like resolve_class_from_stream, but
876 // does not publish the classes in the SystemDictionary.
877 // Handles Lookup.defineClass hidden.
878 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
879 ClassFileStream* st,
880 Symbol* class_name,
881 Handle class_loader,
882 const ClassLoadInfo& cl_info,
883 TRAPS) {
884
885 EventClassLoad class_load_start_event;
886 ClassLoaderData* loader_data;
887
888 // - for hidden classes that are not strong: create a new CLD that has a class holder and
889 // whose loader is the Lookup class's loader.
890 // - for hidden class: add the class to the Lookup class's loader's CLD.
891 assert (cl_info.is_hidden(), "only used for hidden classes");
892 bool create_mirror_cld = !cl_info.is_strong_hidden();
893 loader_data = register_loader(class_loader, create_mirror_cld);
894
895 assert(st != NULL, "invariant");
896 assert(st->need_verify(), "invariant");
897
898 // Parse stream and create a klass.
899 InstanceKlass* k = KlassFactory::create_from_stream(st,
900 class_name,
901 loader_data,
902 cl_info,
903 CHECK_NULL);
904 assert(k != NULL, "no klass created");
905
906 // Hidden classes that are not strong must update ClassLoaderData holder
907 // so that they can be unloaded when the mirror is no longer referenced.
908 if (!cl_info.is_strong_hidden()) {
909 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
910 }
911
912 {
913 MutexLocker mu_r(THREAD, Compile_lock);
914 // Add to class hierarchy, and do possible deoptimizations.
915 add_to_hierarchy(k);
916 // But, do not add to dictionary.
917 }
918
919 k->link_class(CHECK_NULL);
920
921 // notify jvmti
922 if (JvmtiExport::should_post_class_load()) {
923 JvmtiExport::post_class_load(THREAD, k);
924 }
925 if (class_load_start_event.should_commit()) {
926 post_class_load_event(&class_load_start_event, k, loader_data);
927 }
928
929 return k;
930 }
931
932 // Add a klass to the system from a stream (called by jni_DefineClass and
933 // JVM_DefineClass).
934 // Note: class_name can be NULL. In that case we do not know the name of
935 // the class until we have parsed the stream.
936 // This function either returns an InstanceKlass or throws an exception. It does
937 // not return NULL without a pending exception.
938 InstanceKlass* SystemDictionary::resolve_class_from_stream(
939 ClassFileStream* st,
940 Symbol* class_name,
941 Handle class_loader,
942 const ClassLoadInfo& cl_info,
943 TRAPS) {
944
945 HandleMark hm(THREAD);
946
947 ClassLoaderData* loader_data = register_loader(class_loader);
948
949 // Classloaders that support parallelism, e.g. bootstrap classloader,
950 // do not acquire lock here
951 Handle lockObject = get_loader_lock_or_null(class_loader);
952 ObjectLocker ol(lockObject, THREAD);
953
954 // Parse the stream and create a klass.
955 // Note that we do this even though this klass might
956 // already be present in the SystemDictionary, otherwise we would not
957 // throw potential ClassFormatErrors.
958 InstanceKlass* k = NULL;
959
960 #if INCLUDE_CDS
961 if (!DumpSharedSpaces) {
962 k = SystemDictionaryShared::lookup_from_stream(class_name,
963 class_loader,
964 cl_info.protection_domain(),
965 st,
966 CHECK_NULL);
967 }
968 #endif
969
970 if (k == NULL) {
971 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
972 }
973
974 assert(k != NULL, "no klass created");
975 Symbol* h_name = k->name();
976 assert(class_name == NULL || class_name == h_name, "name mismatch");
977
978 // Add class just loaded
979 // If a class loader supports parallel classloading, handle parallel define requests.
980 // find_or_define_instance_class may return a different InstanceKlass,
981 // in which case the old k would be deallocated
982 if (is_parallelCapable(class_loader)) {
983 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
984 } else {
985 define_instance_class(k, class_loader, THREAD);
986
987 // If defining the class throws an exception register 'k' for cleanup.
988 if (HAS_PENDING_EXCEPTION) {
989 assert(k != NULL, "Must have an instance klass here!");
990 loader_data->add_to_deallocate_list(k);
991 return NULL;
992 }
993 }
994
995 // Make sure we have an entry in the SystemDictionary on success
996 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
997
998 return k;
999 }
1000
1001 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
1002 Symbol* class_name,
1003 Handle class_loader,
1004 const ClassLoadInfo& cl_info,
1005 TRAPS) {
1006 if (cl_info.is_hidden()) {
1007 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
1008 } else {
1009 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
1010 }
1011 }
1012
1013
1014 #if INCLUDE_CDS
1015 // Check if a shared class can be loaded by the specific classloader.
1016 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1017 InstanceKlass* ik,
1018 PackageEntry* pkg_entry,
1019 Handle class_loader) {
1020 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1021 "Cannot use sharing if java.base is patched");
1022
1023 // (1) Check if we are loading into the same loader as in dump time.
1024
1025 if (ik->is_shared_boot_class()) {
1026 if (class_loader() != NULL) {
1027 return false;
1028 }
1029 } else if (ik->is_shared_platform_class()) {
1030 if (class_loader() != java_platform_loader()) {
1031 return false;
1032 }
1033 } else if (ik->is_shared_app_class()) {
1034 if (class_loader() != java_system_loader()) {
1035 return false;
1036 }
1037 } else {
1038 // ik was loaded by a custom loader during dump time
1039 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
1040 return false;
1041 } else {
1042 return true;
1043 }
1044 }
1045
1046 // (2) Check if we are loading into the same module from the same location as in dump time.
1047
1048 if (MetaspaceShared::use_optimized_module_handling()) {
1049 // Class visibility has not changed between dump time and run time, so a class
1050 // that was visible (and thus archived) during dump time is always visible during runtime.
1051 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
1052 "visibility cannot change between dump time and runtime");
1053 return true;
1054 }
1055 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
1056 }
1057
1058 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
1059 InstanceKlass* ik,
1060 PackageEntry* pkg_entry,
1061 Handle class_loader) {
1062 int scp_index = ik->shared_classpath_index();
1063 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
1064 assert(scp_index >= 0, "must be");
1065 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
1066 if (!Universe::is_module_initialized()) {
1067 assert(scp_entry != NULL && scp_entry->is_modules_image(),
1068 "Loading non-bootstrap classes before the module system is initialized");
1069 assert(class_loader.is_null(), "sanity");
1070 return true;
1071 }
1072
1073 ModuleEntry* mod_entry = (pkg_entry == NULL) ? NULL : pkg_entry->module();
1074 bool should_be_in_named_module = (mod_entry != NULL && mod_entry->is_named());
1075 bool was_archived_from_named_module = scp_entry->in_named_module();
1076 bool visible;
1077
1078 if (was_archived_from_named_module) {
1079 if (should_be_in_named_module) {
1080 // Is the module loaded from the same location as during dump time?
1081 visible = mod_entry->shared_path_index() == scp_index;
1082 if (visible) {
1083 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1084 }
1085 } else {
1086 // During dump time, this class was in a named module, but at run time, this class should be
1087 // in an unnamed module.
1088 visible = false;
1089 }
1090 } else {
1091 if (should_be_in_named_module) {
1092 // During dump time, this class was in an unnamed, but at run time, this class should be
1093 // in a named module.
1094 visible = false;
1095 } else {
1096 visible = true;
1097 }
1098 }
1099
1100 return visible;
1101 }
1102
1103 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1104 Handle class_loader, Handle protection_domain,
1105 bool is_superclass, TRAPS) {
1106 assert(super_type->is_shared(), "must be");
1107
1108 // Quick check if the super type has been already loaded.
1109 // + Don't do it for unregistered classes -- they can be unloaded so
1110 // super_type->class_loader_data() could be stale.
1111 // + Don't check if loader data is NULL, ie. the super_type isn't fully loaded.
1112 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != NULL) {
1113 // Check if the superclass is loaded by the current class_loader
1114 Symbol* name = super_type->name();
1115 InstanceKlass* check = find_instance_klass(name, class_loader, protection_domain);
1116 if (check == super_type) {
1117 return true;
1118 }
1119 }
1120
1121 Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1122 class_loader, protection_domain, is_superclass, CHECK_0);
1123 if (found == super_type) {
1124 return true;
1125 } else {
1126 // The dynamically resolved super type is not the same as the one we used during dump time,
1127 // so we cannot use the class.
1128 return false;
1129 }
1130 }
1131
1132 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1133 Handle protection_domain, TRAPS) {
1134 // Check the superclass and interfaces. They must be the same
1135 // as in dump time, because the layout of <ik> depends on
1136 // the specific layout of ik->super() and ik->local_interfaces().
1137 //
1138 // If unexpected superclass or interfaces are found, we cannot
1139 // load <ik> from the shared archive.
1140
1141 if (ik->super() != NULL &&
1142 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1143 class_loader, protection_domain, true, THREAD)) {
1144 return false;
1145 }
1146
1147 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1148 int num_interfaces = interfaces->length();
1149 for (int index = 0; index < num_interfaces; index++) {
1150 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1151 return false;
1152 }
1153 }
1154
1155 return true;
1156 }
1157
1158 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1159 Handle class_loader,
1160 Handle protection_domain,
1161 PackageEntry* pkg_entry,
1162 TRAPS) {
1163 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1164 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1165 Symbol* cn = shared_nest_host->name();
1166 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1167 if (s != shared_nest_host) {
1168 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1169 // so we cannot use ik.
1170 return NULL;
1171 } else {
1172 assert(s->is_shared(), "must be");
1173 }
1174
1175 // The lambda proxy class and its nest host have the same class loader and class loader data,
1176 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1177 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1178 assert(shared_nest_host->class_loader_data() == ClassLoaderData::class_loader_data(class_loader()), "mismatched class loader data");
1179 ik->set_nest_host(shared_nest_host);
1180
1181 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, NULL, pkg_entry, CHECK_NULL);
1182
1183 if (loaded_ik != NULL) {
1184 assert(shared_nest_host->is_same_class_package(ik),
1185 "lambda proxy class and its nest host must be in the same package");
1186 }
1187
1188 return loaded_ik;
1189 }
1190
1191 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1192 Handle class_loader,
1193 Handle protection_domain,
1194 const ClassFileStream *cfs,
1195 PackageEntry* pkg_entry,
1196 TRAPS) {
1197 assert(ik != NULL, "sanity");
1198 assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
1199 Symbol* class_name = ik->name();
1200
1201 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1202 return NULL;
1203 }
1204
1205 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1206 return NULL;
1207 }
1208
1209
1210 if (ik->has_inline_type_fields()) {
1211 for (AllFieldStream fs(ik->fields(), ik->constants()); !fs.done(); fs.next()) {
1212 if (Signature::basic_type(fs.signature()) == T_INLINE_TYPE) {
1213 if (!fs.access_flags().is_static()) {
1214 // Pre-load inline class
1215 Klass* real_k = SystemDictionary::resolve_inline_type_field_or_fail(&fs,
1216 class_loader, protection_domain, true, CHECK_NULL);
1217 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1218 if (real_k != k) {
1219 // oops, the app has substituted a different version of k!
1220 return NULL;
1221 }
1222 }
1223 }
1224 }
1225 }
1226
1227 InstanceKlass* new_ik = NULL;
1228 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1229 // It will be skipped for shared VM hidden lambda proxy classes.
1230 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1231 new_ik = KlassFactory::check_shared_class_file_load_hook(
1232 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1233 }
1234 if (new_ik != NULL) {
1235 // The class is changed by CFLH. Return the new class. The shared class is
1236 // not used.
1237 return new_ik;
1238 }
1239
1240 // Adjust methods to recover missing data. They need addresses for
1241 // interpreter entry points and their default native method address
1242 // must be reset.
1243
1244 // Shared classes are all currently loaded by either the bootstrap or
1245 // internal parallel class loaders, so this will never cause a deadlock
1246 // on a custom class loader lock.
1247 // Since this class is already locked with parallel capable class
1248 // loaders, including the bootstrap loader via the placeholder table,
1249 // this lock is currently a nop.
1250
1251 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1252 {
1253 HandleMark hm(THREAD);
1254 Handle lockObject = get_loader_lock_or_null(class_loader);
1255 ObjectLocker ol(lockObject, THREAD);
1256 // prohibited package check assumes all classes loaded from archive call
1257 // restore_unshareable_info which calls ik->set_package()
1258 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1259 }
1260
1261 load_shared_class_misc(ik, loader_data);
1262
1263 if (ik->is_inline_klass()) {
1264 InlineKlass* vk = InlineKlass::cast(ik);
1265 oop val = ik->allocate_instance(CHECK_NULL);
1266 vk->set_default_value(val);
1267 }
1268
1269 return ik;
1270 }
1271
1272 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1273 ik->print_class_load_logging(loader_data, NULL, NULL);
1274
1275 // For boot loader, ensure that GetSystemPackage knows that a class in this
1276 // package was loaded.
1277 if (loader_data->is_the_null_class_loader_data()) {
1278 int path_index = ik->shared_classpath_index();
1279 ik->set_classpath_index(path_index);
1280 }
1281
1282 // notify a class loaded from shared object
1283 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1284 }
1285
1286 #endif // INCLUDE_CDS
1287
1288 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1289
1290 if (class_loader.is_null()) {
1291 ResourceMark rm(THREAD);
1292 PackageEntry* pkg_entry = NULL;
1293 bool search_only_bootloader_append = false;
1294 ClassLoaderData *loader_data = class_loader_data(class_loader);
1295
1296 // Find the package in the boot loader's package entry table.
1297 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1298 if (pkg_name != NULL) {
1299 pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1300 }
1301
1302 // Prior to attempting to load the class, enforce the boot loader's
1303 // visibility boundaries.
1304 if (!Universe::is_module_initialized()) {
1305 // During bootstrapping, prior to module initialization, any
1306 // class attempting to be loaded must be checked against the
1307 // java.base packages in the boot loader's PackageEntryTable.
1308 // No class outside of java.base is allowed to be loaded during
1309 // this bootstrapping window.
1310 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1311 // Class is either in the unnamed package or in
1312 // a named package within the unnamed module. Either
1313 // case is outside of java.base, do not attempt to
1314 // load the class post java.base definition. If
1315 // java.base has not been defined, let the class load
1316 // and its package will be checked later by
1317 // ModuleEntryTable::verify_javabase_packages.
1318 if (ModuleEntryTable::javabase_defined()) {
1319 return NULL;
1320 }
1321 } else {
1322 // Check that the class' package is defined within java.base.
1323 ModuleEntry* mod_entry = pkg_entry->module();
1324 Symbol* mod_entry_name = mod_entry->name();
1325 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1326 return NULL;
1327 }
1328 }
1329 } else {
1330 // After the module system has been initialized, check if the class'
1331 // package is in a module defined to the boot loader.
1332 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1333 // Class is either in the unnamed package, in a named package
1334 // within a module not defined to the boot loader or in a
1335 // a named package within the unnamed module. In all cases,
1336 // limit visibility to search for the class only in the boot
1337 // loader's append path.
1338 if (!ClassLoader::has_bootclasspath_append()) {
1339 // If there is no bootclasspath append entry, no need to continue
1340 // searching.
1341 return NULL;
1342 }
1343 search_only_bootloader_append = true;
1344 }
1345 }
1346
1347 // Prior to bootstrapping's module initialization, never load a class outside
1348 // of the boot loader's module path
1349 assert(Universe::is_module_initialized() ||
1350 !search_only_bootloader_append,
1351 "Attempt to load a class outside of boot loader's module path");
1352
1353 // Search for classes in the CDS archive.
1354 InstanceKlass* k = NULL;
1355
1356 #if INCLUDE_CDS
1357 if (UseSharedSpaces)
1358 {
1359 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1360 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1361 if (ik != NULL && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1362 SharedClassLoadingMark slm(THREAD, ik);
1363 k = load_shared_class(ik, class_loader, Handle(), NULL, pkg_entry, CHECK_NULL);
1364 }
1365 }
1366 #endif
1367
1368 if (k == NULL) {
1369 // Use VM class loader
1370 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1371 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1372 }
1373
1374 // find_or_define_instance_class may return a different InstanceKlass
1375 if (k != NULL) {
1376 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1377 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1378 }
1379 return k;
1380 } else {
1381 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1382 ResourceMark rm(THREAD);
1383
1384 JavaThread* jt = THREAD;
1385
1386 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1387 ClassLoader::perf_app_classload_selftime(),
1388 ClassLoader::perf_app_classload_count(),
1389 jt->get_thread_stat()->perf_recursion_counts_addr(),
1390 jt->get_thread_stat()->perf_timers_addr(),
1391 PerfClassTraceTime::CLASS_LOAD);
1392
1393 // Translate to external class name format, i.e., convert '/' chars to '.'
1394 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1395
1396 JavaValue result(T_OBJECT);
1397
1398 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1399
1400 // Call public unsynchronized loadClass(String) directly for all class loaders.
1401 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1402 // acquire a class-name based lock rather than the class loader object lock.
1403 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1404 JavaCalls::call_virtual(&result,
1405 class_loader,
1406 spec_klass,
1407 vmSymbols::loadClass_name(),
1408 vmSymbols::string_class_signature(),
1409 string,
1410 CHECK_NULL);
1411
1412 assert(result.get_type() == T_OBJECT, "just checking");
1413 oop obj = result.get_oop();
1414
1415 // Primitive classes return null since forName() can not be
1416 // used to obtain any of the Class objects representing primitives or void
1417 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1418 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1419 // For user defined Java class loaders, check that the name returned is
1420 // the same as that requested. This check is done for the bootstrap
1421 // loader when parsing the class file.
1422 if (class_name == k->name()) {
1423 return k;
1424 }
1425 }
1426 // Class is not found or has the wrong name, return NULL
1427 return NULL;
1428 }
1429 }
1430
1431 InstanceKlass* SystemDictionary::load_instance_class(unsigned int name_hash,
1432 Symbol* name,
1433 Handle class_loader,
1434 TRAPS) {
1435
1436 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1437
1438 // If everything was OK (no exceptions, no null return value), and
1439 // class_loader is NOT the defining loader, do a little more bookkeeping.
1440 if (loaded_class != NULL &&
1441 loaded_class->class_loader() != class_loader()) {
1442
1443 check_constraints(name_hash, loaded_class, class_loader, false, CHECK_NULL);
1444
1445 // Record dependency for non-parent delegation.
1446 // This recording keeps the defining class loader of the klass (loaded_class) found
1447 // from being unloaded while the initiating class loader is loaded
1448 // even if the reference to the defining class loader is dropped
1449 // before references to the initiating class loader.
1450 ClassLoaderData* loader_data = class_loader_data(class_loader);
1451 loader_data->record_dependency(loaded_class);
1452
1453 { // Grabbing the Compile_lock prevents systemDictionary updates
1454 // during compilations.
1455 MutexLocker mu(THREAD, Compile_lock);
1456 update_dictionary(name_hash, loaded_class, class_loader);
1457 }
1458
1459 if (JvmtiExport::should_post_class_load()) {
1460 JvmtiExport::post_class_load(THREAD, loaded_class);
1461 }
1462 }
1463 return loaded_class;
1464 }
1465
1466 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1467 EventClassDefine event;
1468 if (event.should_commit()) {
1469 event.set_definedClass(k);
1470 event.set_definingClassLoader(def_cld);
1471 event.commit();
1472 }
1473 }
1474
1475 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1476
1477 ClassLoaderData* loader_data = k->class_loader_data();
1478 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1479
1480 // Bootstrap and other parallel classloaders don't acquire a lock,
1481 // they use placeholder token.
1482 // If a parallelCapable class loader calls define_instance_class instead of
1483 // find_or_define_instance_class to get here, we have a timing
1484 // hole with systemDictionary updates and check_constraints
1485 if (!is_parallelCapable(class_loader)) {
1486 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1487 get_loader_lock_or_null(class_loader)),
1488 "define called without lock");
1489 }
1490
1491 // Check class-loading constraints. Throw exception if violation is detected.
1492 // Grabs and releases SystemDictionary_lock
1493 // The check_constraints/find_class call and update_dictionary sequence
1494 // must be "atomic" for a specific class/classloader pair so we never
1495 // define two different instanceKlasses for that class/classloader pair.
1496 // Existing classloaders will call define_instance_class with the
1497 // classloader lock held
1498 // Parallel classloaders will call find_or_define_instance_class
1499 // which will require a token to perform the define class
1500 Symbol* name_h = k->name();
1501 Dictionary* dictionary = loader_data->dictionary();
1502 unsigned int name_hash = dictionary->compute_hash(name_h);
1503 check_constraints(name_hash, k, class_loader, true, CHECK);
1504
1505 // Register class just loaded with class loader (placed in ArrayList)
1506 // Note we do this before updating the dictionary, as this can
1507 // fail with an OutOfMemoryError (if it does, we will *not* put this
1508 // class in the dictionary and will not update the class hierarchy).
1509 // JVMTI FollowReferences needs to find the classes this way.
1510 if (k->class_loader() != NULL) {
1511 methodHandle m(THREAD, Universe::loader_addClass_method());
1512 JavaValue result(T_VOID);
1513 JavaCallArguments args(class_loader);
1514 args.push_oop(Handle(THREAD, k->java_mirror()));
1515 JavaCalls::call(&result, m, &args, CHECK);
1516 }
1517
1518 // Add the new class. We need recompile lock during update of CHA.
1519 {
1520 MutexLocker mu_r(THREAD, Compile_lock);
1521
1522 // Add to class hierarchy, and do possible deoptimizations.
1523 add_to_hierarchy(k);
1524
1525 // Add to systemDictionary - so other classes can see it.
1526 // Grabs and releases SystemDictionary_lock
1527 update_dictionary(name_hash, k, class_loader);
1528 }
1529 k->eager_initialize(THREAD);
1530
1531 // notify jvmti
1532 if (JvmtiExport::should_post_class_load()) {
1533 JvmtiExport::post_class_load(THREAD, k);
1534 }
1535 post_class_define_event(k, loader_data);
1536 }
1537
1538 // Support parallel classloading
1539 // All parallel class loaders, including bootstrap classloader
1540 // lock a placeholder entry for this class/class_loader pair
1541 // to allow parallel defines of different classes for this class loader
1542 // With AllowParallelDefine flag==true, in case they do not synchronize around
1543 // FindLoadedClass/DefineClass, calls, we check for parallel
1544 // loading for them, wait if a defineClass is in progress
1545 // and return the initial requestor's results
1546 // This flag does not apply to the bootstrap classloader.
1547 // With AllowParallelDefine flag==false, call through to define_instance_class
1548 // which will throw LinkageError: duplicate class definition.
1549 // False is the requested default.
1550 // For better performance, the class loaders should synchronize
1551 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1552 // potentially waste time reading and parsing the bytestream.
1553 // Note: VM callers should ensure consistency of k/class_name,class_loader
1554 // Be careful when modifying this code: once you have run
1555 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1556 // you need to find_and_remove it before returning.
1557 // So be careful to not exit with a CHECK_ macro between these calls.
1558 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1559 InstanceKlass* k, TRAPS) {
1560
1561 Symbol* name_h = k->name(); // passed in class_name may be null
1562 ClassLoaderData* loader_data = class_loader_data(class_loader);
1563 Dictionary* dictionary = loader_data->dictionary();
1564
1565 unsigned int name_hash = dictionary->compute_hash(name_h);
1566
1567 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1568 {
1569 MutexLocker mu(THREAD, SystemDictionary_lock);
1570 // First check if class already defined
1571 if (is_parallelDefine(class_loader)) {
1572 InstanceKlass* check = dictionary->find_class(name_hash, name_h);
1573 if (check != NULL) {
1574 return check;
1575 }
1576 }
1577
1578 // Acquire define token for this class/classloader
1579 assert(placeholders()->compute_hash(name_h) == name_hash, "they're the same hashcode");
1580 PlaceholderEntry* probe = placeholders()->find_and_add(name_hash, name_h, loader_data,
1581 PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1582 // Wait if another thread defining in parallel
1583 // All threads wait - even those that will throw duplicate class: otherwise
1584 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1585 // if other thread has not finished updating dictionary
1586 while (probe->definer() != NULL) {
1587 SystemDictionary_lock->wait();
1588 }
1589 // Only special cases allow parallel defines and can use other thread's results
1590 // Other cases fall through, and may run into duplicate defines
1591 // caught by finding an entry in the SystemDictionary
1592 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1593 InstanceKlass* ik = probe->instance_klass();
1594 placeholders()->find_and_remove(name_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1595 SystemDictionary_lock->notify_all();
1596 #ifdef ASSERT
1597 InstanceKlass* check = dictionary->find_class(name_hash, name_h);
1598 assert(check != NULL, "definer missed recording success");
1599 #endif
1600 return ik;
1601 } else {
1602 // This thread will define the class (even if earlier thread tried and had an error)
1603 probe->set_definer(THREAD);
1604 }
1605 }
1606
1607 define_instance_class(k, class_loader, THREAD);
1608
1609 // definer must notify any waiting threads
1610 {
1611 MutexLocker mu(THREAD, SystemDictionary_lock);
1612 PlaceholderEntry* probe = placeholders()->get_entry(name_hash, name_h, loader_data);
1613 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1614 if (!HAS_PENDING_EXCEPTION) {
1615 probe->set_instance_klass(k);
1616 }
1617 probe->set_definer(NULL);
1618 placeholders()->find_and_remove(name_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1619 SystemDictionary_lock->notify_all();
1620 }
1621
1622 return HAS_PENDING_EXCEPTION ? NULL : k;
1623 }
1624
1625 // If a class loader supports parallel classloading handle parallel define requests.
1626 // find_or_define_instance_class may return a different InstanceKlass
1627 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1628 InstanceKlass* k, TRAPS) {
1629 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1630 // Clean up original InstanceKlass if duplicate or error
1631 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1632 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1633 assert(defined_k != NULL, "Should have a klass if there's no exception");
1634 k->class_loader_data()->add_to_deallocate_list(k);
1635 } else if (HAS_PENDING_EXCEPTION) {
1636 assert(defined_k == NULL, "Should not have a klass if there's an exception");
1637 k->class_loader_data()->add_to_deallocate_list(k);
1638 }
1639 return defined_k;
1640 }
1641
1642
1643 // ----------------------------------------------------------------------------
1644 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Compile_lock
1645 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1646 // before a new class is used.
1647
1648 void SystemDictionary::add_to_hierarchy(InstanceKlass* k) {
1649 assert(k != NULL, "just checking");
1650 if (Universe::is_fully_initialized()) {
1651 assert_locked_or_safepoint(Compile_lock);
1652 }
1653
1654 k->set_init_state(InstanceKlass::loaded);
1655 // make sure init_state store is already done.
1656 // The compiler reads the hierarchy outside of the Compile_lock.
1657 // Access ordering is used to add to hierarchy.
1658
1659 // Link into hierachy.
1660 k->append_to_sibling_list(); // add to superklass/sibling list
1661 k->process_interfaces(); // handle all "implements" declarations
1662
1663 // Now flush all code that depended on old class hierarchy.
1664 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1665 if (Universe::is_fully_initialized()) {
1666 CodeCache::flush_dependents_on(k);
1667 }
1668 }
1669
1670 // ----------------------------------------------------------------------------
1671 // GC support
1672
1673 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1674 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1675
1676 bool unloading_occurred;
1677 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1678 {
1679 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1680 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1681 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1682 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1683 if (unloading_occurred) {
1684 MutexLocker ml2(is_concurrent ? Module_lock : NULL);
1685 JFR_ONLY(Jfr::on_unloading_classes();)
1686
1687 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
1688 ClassLoaderDataGraph::clean_module_and_package_info();
1689 constraints()->purge_loader_constraints();
1690 resolution_errors()->purge_resolution_errors();
1691 }
1692 }
1693
1694 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1695
1696 if (unloading_occurred) {
1697 SymbolTable::trigger_cleanup();
1698
1699 if (java_lang_System::allow_security_manager()) {
1700 // Oops referenced by the protection domain cache table may get unreachable independently
1701 // of the class loader (eg. cached protection domain oops). So we need to
1702 // explicitly unlink them here.
1703 // All protection domain oops are linked to the caller class, so if nothing
1704 // unloads, this is not needed.
1705 _pd_cache_table->trigger_cleanup();
1706 } else {
1707 assert(_pd_cache_table->number_of_entries() == 0, "should be empty");
1708 }
1709
1710 InstanceKlass::clean_initialization_error_table();
1711 }
1712
1713 return unloading_occurred;
1714 }
1715
1716 void SystemDictionary::methods_do(void f(Method*)) {
1717 // Walk methods in loaded classes
1718 MutexLocker ml(ClassLoaderDataGraph_lock);
1719 ClassLoaderDataGraph::methods_do(f);
1720 // Walk method handle intrinsics
1721 invoke_method_table()->methods_do(f);
1722 }
1723
1724 // ----------------------------------------------------------------------------
1725 // Initialization
1726
1727 void SystemDictionary::initialize(TRAPS) {
1728 // Allocate arrays
1729 _placeholders = new PlaceholderTable(_placeholder_table_size);
1730 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1731 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1732 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1733 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1734
1735 // Resolve basic classes
1736 vmClasses::resolve_all(CHECK);
1737 // Resolve classes used by archived heap objects
1738 if (UseSharedSpaces) {
1739 HeapShared::resolve_classes(THREAD);
1740 }
1741 }
1742
1743 // Constraints on class loaders. The details of the algorithm can be
1744 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1745 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1746 // that the dictionary needs to maintain a set of contraints that
1747 // must be satisfied by all classes in the dictionary.
1748 // if defining is true, then LinkageError if already in dictionary
1749 // if initiating loader, then ok if InstanceKlass matches existing entry
1750
1751 void SystemDictionary::check_constraints(unsigned int name_hash,
1752 InstanceKlass* k,
1753 Handle class_loader,
1754 bool defining,
1755 TRAPS) {
1756 ResourceMark rm(THREAD);
1757 stringStream ss;
1758 bool throwException = false;
1759
1760 {
1761 Symbol *name = k->name();
1762 ClassLoaderData *loader_data = class_loader_data(class_loader);
1763
1764 MutexLocker mu(THREAD, SystemDictionary_lock);
1765
1766 InstanceKlass* check = loader_data->dictionary()->find_class(name_hash, name);
1767 if (check != NULL) {
1768 // If different InstanceKlass - duplicate class definition,
1769 // else - ok, class loaded by a different thread in parallel.
1770 // We should only have found it if it was done loading and ok to use.
1771
1772 if ((defining == true) || (k != check)) {
1773 throwException = true;
1774 ss.print("loader %s", loader_data->loader_name_and_id());
1775 ss.print(" attempted duplicate %s definition for %s. (%s)",
1776 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1777 } else {
1778 return;
1779 }
1780 }
1781
1782 if (throwException == false) {
1783 if (constraints()->check_or_update(k, class_loader, name) == false) {
1784 throwException = true;
1785 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1786 ss.print(" wants to load %s %s.",
1787 k->external_kind(), k->external_name());
1788 Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
1789 if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
1790 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1791 existing_klass->external_kind(),
1792 existing_klass->class_loader_data()->loader_name_and_id(),
1793 existing_klass->class_in_module_of_loader(false, true));
1794 } else {
1795 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1796 }
1797 }
1798 }
1799 }
1800
1801 // Throw error now if needed (cannot throw while holding
1802 // SystemDictionary_lock because of rank ordering)
1803 if (throwException == true) {
1804 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1805 }
1806 }
1807
1808 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
1809 // have been called.
1810 void SystemDictionary::update_dictionary(unsigned int hash,
1811 InstanceKlass* k,
1812 Handle class_loader) {
1813 // Compile_lock prevents systemDictionary updates during compilations
1814 assert_locked_or_safepoint(Compile_lock);
1815 Symbol* name = k->name();
1816 ClassLoaderData *loader_data = class_loader_data(class_loader);
1817
1818 {
1819 MutexLocker mu1(SystemDictionary_lock);
1820
1821 // Make a new dictionary entry.
1822 Dictionary* dictionary = loader_data->dictionary();
1823 InstanceKlass* sd_check = dictionary->find_class(hash, name);
1824 if (sd_check == NULL) {
1825 dictionary->add_klass(hash, name, k);
1826 }
1827 SystemDictionary_lock->notify_all();
1828 }
1829 }
1830
1831
1832 // Try to find a class name using the loader constraints. The
1833 // loader constraints might know about a class that isn't fully loaded
1834 // yet and these will be ignored.
1835 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1836 Thread* current, Symbol* class_name, Handle class_loader) {
1837
1838 // First see if it has been loaded directly.
1839 // Force the protection domain to be null. (This removes protection checks.)
1840 Handle no_protection_domain;
1841 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
1842 no_protection_domain);
1843 if (klass != NULL)
1844 return klass;
1845
1846 // Now look to see if it has been loaded elsewhere, and is subject to
1847 // a loader constraint that would require this loader to return the
1848 // klass that is already loaded.
1849 if (Signature::is_array(class_name)) {
1850 // For array classes, their Klass*s are not kept in the
1851 // constraint table. The element Klass*s are.
1852 SignatureStream ss(class_name, false);
1853 int ndims = ss.skip_array_prefix(); // skip all '['s
1854 BasicType t = ss.type();
1855 if (t != T_OBJECT && t != T_INLINE_TYPE) {
1856 klass = Universe::typeArrayKlassObj(t);
1857 } else {
1858 MutexLocker mu(current, SystemDictionary_lock);
1859 klass = constraints()->find_constrained_klass(ss.as_symbol(), class_loader);
1860 }
1861 // If element class already loaded, allocate array klass
1862 if (klass != NULL) {
1863 if (class_name->is_Q_array_signature()) {
1864 klass = InlineKlass::cast(klass)->null_free_inline_array_klass_or_null(ndims);
1865 } else {
1866 klass = klass->array_klass_or_null(ndims);
1867 }
1868 }
1869 } else {
1870 MutexLocker mu(current, SystemDictionary_lock);
1871 // Non-array classes are easy: simply check the constraint table.
1872 klass = constraints()->find_constrained_klass(class_name, class_loader);
1873 }
1874
1875 return klass;
1876 }
1877
1878 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1879 Klass* klass_being_linked,
1880 Handle class_loader1,
1881 Handle class_loader2) {
1882 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1883 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1884
1885 Symbol* constraint_name = NULL;
1886
1887 if (!Signature::is_array(class_name)) {
1888 constraint_name = class_name;
1889 } else {
1890 // For array classes, their Klass*s are not kept in the
1891 // constraint table. The element classes are.
1892 SignatureStream ss(class_name, false);
1893 ss.skip_array_prefix(); // skip all '['s
1894 if (!ss.has_envelope()) {
1895 return true; // primitive types always pass
1896 }
1897 constraint_name = ss.as_symbol();
1898 // Increment refcount to keep constraint_name alive after
1899 // SignatureStream is destructed. It will be decremented below
1900 // before returning.
1901 constraint_name->increment_refcount();
1902 }
1903
1904 Dictionary* dictionary1 = loader_data1->dictionary();
1905 unsigned int name_hash1 = dictionary1->compute_hash(constraint_name);
1906
1907 Dictionary* dictionary2 = loader_data2->dictionary();
1908 unsigned int name_hash2 = dictionary2->compute_hash(constraint_name);
1909
1910 {
1911 MutexLocker mu_s(SystemDictionary_lock);
1912 InstanceKlass* klass1 = dictionary1->find_class(name_hash1, constraint_name);
1913 InstanceKlass* klass2 = dictionary2->find_class(name_hash2, constraint_name);
1914 bool result = constraints()->add_entry(constraint_name, klass1, class_loader1,
1915 klass2, class_loader2);
1916 #if INCLUDE_CDS
1917 if (Arguments::is_dumping_archive() && klass_being_linked != NULL &&
1918 !klass_being_linked->is_shared()) {
1919 SystemDictionaryShared::record_linking_constraint(constraint_name,
1920 InstanceKlass::cast(klass_being_linked),
1921 class_loader1, class_loader2);
1922 }
1923 #endif // INCLUDE_CDS
1924 if (Signature::is_array(class_name)) {
1925 constraint_name->decrement_refcount();
1926 }
1927 return result;
1928 }
1929 }
1930
1931 // Add entry to resolution error table to record the error when the first
1932 // attempt to resolve a reference to a class has failed.
1933 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1934 Symbol* error, Symbol* message,
1935 Symbol* cause, Symbol* cause_msg) {
1936 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1937 int index = resolution_errors()->hash_to_index(hash);
1938 {
1939 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1940 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
1941 if (entry == NULL) {
1942 resolution_errors()->add_entry(index, hash, pool, which, error, message, cause, cause_msg);
1943 }
1944 }
1945 }
1946
1947 // Delete a resolution error for RedefineClasses for a constant pool is going away
1948 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1949 resolution_errors()->delete_entry(pool);
1950 }
1951
1952 // Lookup resolution error table. Returns error if found, otherwise NULL.
1953 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1954 Symbol** message, Symbol** cause, Symbol** cause_msg) {
1955 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1956 int index = resolution_errors()->hash_to_index(hash);
1957 {
1958 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1959 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
1960 if (entry != NULL) {
1961 *message = entry->message();
1962 *cause = entry->cause();
1963 *cause_msg = entry->cause_msg();
1964 return entry->error();
1965 } else {
1966 return NULL;
1967 }
1968 }
1969 }
1970
1971 // Add an entry to resolution error table to record an error in resolving or
1972 // validating a nest host. This is used to construct informative error
1973 // messages when IllegalAccessError's occur. If an entry already exists it will
1974 // be updated with the nest host error message.
1975 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1976 int which,
1977 const char* message) {
1978 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1979 int index = resolution_errors()->hash_to_index(hash);
1980 {
1981 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1982 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
1983 if (entry != NULL && entry->nest_host_error() == NULL) {
1984 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1985 // still want to add the error message for the higher-level access checks to report. We should
1986 // only reach here under the same error condition, so we can ignore the potential race with setting
1987 // the message. If we see it is already set then we can ignore it.
1988 entry->set_nest_host_error(message);
1989 } else {
1990 resolution_errors()->add_entry(index, hash, pool, which, message);
1991 }
1992 }
1993 }
1994
1995 // Lookup any nest host error
1996 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1997 unsigned int hash = resolution_errors()->compute_hash(pool, which);
1998 int index = resolution_errors()->hash_to_index(hash);
1999 {
2000 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2001 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2002 if (entry != NULL) {
2003 return entry->nest_host_error();
2004 } else {
2005 return NULL;
2006 }
2007 }
2008 }
2009
2010
2011 // Signature constraints ensure that callers and callees agree about
2012 // the meaning of type names in their signatures. This routine is the
2013 // intake for constraints. It collects them from several places:
2014 //
2015 // * LinkResolver::resolve_method (if check_access is true) requires
2016 // that the resolving class (the caller) and the defining class of
2017 // the resolved method (the callee) agree on each type in the
2018 // method's signature.
2019 //
2020 // * LinkResolver::resolve_interface_method performs exactly the same
2021 // checks.
2022 //
2023 // * LinkResolver::resolve_field requires that the constant pool
2024 // attempting to link to a field agree with the field's defining
2025 // class about the type of the field signature.
2026 //
2027 // * klassVtable::initialize_vtable requires that, when a class
2028 // overrides a vtable entry allocated by a superclass, that the
2029 // overriding method (i.e., the callee) agree with the superclass
2030 // on each type in the method's signature.
2031 //
2032 // * klassItable::initialize_itable requires that, when a class fills
2033 // in its itables, for each non-abstract method installed in an
2034 // itable, the method (i.e., the callee) agree with the interface
2035 // on each type in the method's signature.
2036 //
2037 // All those methods have a boolean (check_access, checkconstraints)
2038 // which turns off the checks. This is used from specialized contexts
2039 // such as bootstrapping, dumping, and debugging.
2040 //
2041 // No direct constraint is placed between the class and its
2042 // supertypes. Constraints are only placed along linked relations
2043 // between callers and callees. When a method overrides or implements
2044 // an abstract method in a supertype (superclass or interface), the
2045 // constraints are placed as if the supertype were the caller to the
2046 // overriding method. (This works well, since callers to the
2047 // supertype have already established agreement between themselves and
2048 // the supertype.) As a result of all this, a class can disagree with
2049 // its supertype about the meaning of a type name, as long as that
2050 // class neither calls a relevant method of the supertype, nor is
2051 // called (perhaps via an override) from the supertype.
2052 //
2053 //
2054 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
2055 //
2056 // Make sure all class components (including arrays) in the given
2057 // signature will be resolved to the same class in both loaders.
2058 // Returns the name of the type that failed a loader constraint check, or
2059 // NULL if no constraint failed. No exception except OOME is thrown.
2060 // Arrays are not added to the loader constraint table, their elements are.
2061 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2062 Klass* klass_being_linked,
2063 Handle loader1, Handle loader2,
2064 bool is_method) {
2065 // Nothing to do if loaders are the same.
2066 if (loader1() == loader2()) {
2067 return NULL;
2068 }
2069
2070 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2071 if (ss.is_reference()) {
2072 Symbol* sig = ss.as_symbol();
2073 // Note: In the future, if template-like types can take
2074 // arguments, we will want to recognize them and dig out class
2075 // names hiding inside the argument lists.
2076 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2077 return sig;
2078 }
2079 }
2080 }
2081 return NULL;
2082 }
2083
2084 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2085 Symbol* signature,
2086 TRAPS) {
2087 methodHandle empty;
2088 const int iid_as_int = vmIntrinsics::as_int(iid);
2089 assert(MethodHandles::is_signature_polymorphic(iid) &&
2090 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2091 iid != vmIntrinsics::_invokeGeneric,
2092 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2093
2094 unsigned int hash = invoke_method_table()->compute_hash(signature, iid_as_int);
2095 int index = invoke_method_table()->hash_to_index(hash);
2096 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid_as_int);
2097 methodHandle m;
2098 if (spe == NULL || spe->method() == NULL) {
2099 spe = NULL;
2100 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2101 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
2102 if (!Arguments::is_interpreter_only()) {
2103 // Generate a compiled form of the MH intrinsic.
2104 AdapterHandlerLibrary::create_native_wrapper(m);
2105 // Check if have the compiled code.
2106 if (!m->has_compiled_code()) {
2107 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2108 "Out of space in CodeCache for method handle intrinsic");
2109 }
2110 }
2111 // Now grab the lock. We might have to throw away the new method,
2112 // if a racing thread has managed to install one at the same time.
2113 {
2114 MutexLocker ml(THREAD, SystemDictionary_lock);
2115 spe = invoke_method_table()->find_entry(index, hash, signature, iid_as_int);
2116 if (spe == NULL)
2117 spe = invoke_method_table()->add_entry(index, hash, signature, iid_as_int);
2118 if (spe->method() == NULL)
2119 spe->set_method(m());
2120 }
2121 }
2122
2123 assert(spe != NULL && spe->method() != NULL, "");
2124 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2125 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2126 "MH intrinsic invariant");
2127 return spe->method();
2128 }
2129
2130 // Helper for unpacking the return value from linkMethod and linkCallSite.
2131 static Method* unpack_method_and_appendix(Handle mname,
2132 Klass* accessing_klass,
2133 objArrayHandle appendix_box,
2134 Handle* appendix_result,
2135 TRAPS) {
2136 if (mname.not_null()) {
2137 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2138 if (m != NULL) {
2139 oop appendix = appendix_box->obj_at(0);
2140 LogTarget(Info, methodhandles) lt;
2141 if (lt.develop_is_enabled()) {
2142 ResourceMark rm(THREAD);
2143 LogStream ls(lt);
2144 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2145 m->print_on(&ls);
2146 if (appendix != NULL) { ls.print("appendix = "); appendix->print_on(&ls); }
2147 ls.cr();
2148 }
2149
2150 (*appendix_result) = Handle(THREAD, appendix);
2151 // the target is stored in the cpCache and if a reference to this
2152 // MemberName is dropped we need a way to make sure the
2153 // class_loader containing this method is kept alive.
2154 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2155 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2156 this_key->record_dependency(m->method_holder());
2157 return mh();
2158 }
2159 }
2160 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2161 }
2162
2163 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2164 Symbol* name,
2165 Symbol* signature,
2166 Klass* accessing_klass,
2167 Handle *appendix_result,
2168 TRAPS) {
2169 assert(THREAD->can_call_java() ,"");
2170 Handle method_type =
2171 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2172
2173 int ref_kind = JVM_REF_invokeVirtual;
2174 oop name_oop = StringTable::intern(name, CHECK_NULL);
2175 Handle name_str (THREAD, name_oop);
2176 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2177 assert(appendix_box->obj_at(0) == NULL, "");
2178
2179 // This should not happen. JDK code should take care of that.
2180 if (accessing_klass == NULL || method_type.is_null()) {
2181 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2182 }
2183
2184 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2185 JavaCallArguments args;
2186 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2187 args.push_int(ref_kind);
2188 args.push_oop(Handle(THREAD, klass->java_mirror()));
2189 args.push_oop(name_str);
2190 args.push_oop(method_type);
2191 args.push_oop(appendix_box);
2192 JavaValue result(T_OBJECT);
2193 JavaCalls::call_static(&result,
2194 vmClasses::MethodHandleNatives_klass(),
2195 vmSymbols::linkMethod_name(),
2196 vmSymbols::linkMethod_signature(),
2197 &args, CHECK_NULL);
2198 Handle mname(THREAD, result.get_oop());
2199 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2200 }
2201
2202 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2203 // We must ensure that all class loaders everywhere will reach this class, for any client.
2204 // This is a safe bet for public classes in java.lang, such as Object and String.
2205 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2206 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2207 static bool is_always_visible_class(oop mirror) {
2208 Klass* klass = java_lang_Class::as_Klass(mirror);
2209 if (klass->is_objArray_klass()) {
2210 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2211 }
2212 if (klass->is_typeArray_klass()) {
2213 return true; // primitive array
2214 }
2215 assert(klass->is_instance_klass(), "%s", klass->external_name());
2216 return klass->is_public() &&
2217 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2218 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2219 }
2220
2221 // Find or construct the Java mirror (java.lang.Class instance) for
2222 // the given field type signature, as interpreted relative to the
2223 // given class loader. Handles primitives, void, references, arrays,
2224 // and all other reflectable types, except method types.
2225 // N.B. Code in reflection should use this entry point.
2226 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2227 Klass* accessing_klass,
2228 Handle class_loader,
2229 Handle protection_domain,
2230 SignatureStream::FailureMode failure_mode,
2231 TRAPS) {
2232 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2233 "one or the other, or perhaps neither");
2234
2235 // What we have here must be a valid field descriptor,
2236 // and all valid field descriptors are supported.
2237 // Produce the same java.lang.Class that reflection reports.
2238 if (accessing_klass != NULL) {
2239 class_loader = Handle(THREAD, accessing_klass->class_loader());
2240 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2241 }
2242 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2243 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2244 if (mirror_oop == NULL) {
2245 return Handle(); // report failure this way
2246 }
2247 Handle mirror(THREAD, mirror_oop);
2248
2249 if (accessing_klass != NULL) {
2250 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2251 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2252 if (sel_klass != NULL) {
2253 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2254 }
2255 }
2256 return mirror;
2257 }
2258
2259
2260 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2261 // signature, as interpreted relative to the given class loader.
2262 // Because of class loader constraints, all method handle usage must be
2263 // consistent with this loader.
2264 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2265 Klass* accessing_klass,
2266 TRAPS) {
2267 Handle empty;
2268 int null_iid = vmIntrinsics::as_int(vmIntrinsics::_none); // distinct from all method handle invoker intrinsics
2269 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2270 int index = invoke_method_table()->hash_to_index(hash);
2271 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2272 if (spe != NULL && spe->method_type() != NULL) {
2273 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2274 return Handle(THREAD, spe->method_type());
2275 } else if (!THREAD->can_call_java()) {
2276 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2277 return Handle(); // do not attempt from within compiler, unless it was cached
2278 }
2279
2280 Handle class_loader, protection_domain;
2281 if (accessing_klass != NULL) {
2282 class_loader = Handle(THREAD, accessing_klass->class_loader());
2283 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2284 }
2285 bool can_be_cached = true;
2286 int npts = ArgumentCount(signature).size();
2287 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2288 int arg = 0;
2289 Handle rt; // the return type from the signature
2290 ResourceMark rm(THREAD);
2291 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2292 oop mirror = NULL;
2293 if (can_be_cached) {
2294 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2295 mirror = ss.as_java_mirror(Handle(), Handle(),
2296 SignatureStream::ReturnNull, CHECK_(empty));
2297 if (mirror == NULL || (ss.is_reference() && !is_always_visible_class(mirror))) {
2298 // Fall back to accessing_klass context.
2299 can_be_cached = false;
2300 }
2301 }
2302 if (!can_be_cached) {
2303 // Resolve, throwing a real error if it doesn't work.
2304 mirror = ss.as_java_mirror(class_loader, protection_domain,
2305 SignatureStream::NCDFError, CHECK_(empty));
2306 }
2307 assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
2308 if (ss.at_return_type())
2309 rt = Handle(THREAD, mirror);
2310 else
2311 pts->obj_at_put(arg++, mirror);
2312
2313 // Check accessibility.
2314 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2315 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2316 mirror = NULL; // safety
2317 // Emulate ConstantPool::verify_constant_pool_resolve.
2318 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2319 }
2320 }
2321 assert(arg == npts, "");
2322
2323 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2324 JavaCallArguments args(Handle(THREAD, rt()));
2325 args.push_oop(pts);
2326 JavaValue result(T_OBJECT);
2327 JavaCalls::call_static(&result,
2328 vmClasses::MethodHandleNatives_klass(),
2329 vmSymbols::findMethodHandleType_name(),
2330 vmSymbols::findMethodHandleType_signature(),
2331 &args, CHECK_(empty));
2332 Handle method_type(THREAD, result.get_oop());
2333
2334 if (can_be_cached) {
2335 // We can cache this MethodType inside the JVM.
2336 MutexLocker ml(THREAD, SystemDictionary_lock);
2337 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2338 if (spe == NULL)
2339 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2340 if (spe->method_type() == NULL) {
2341 spe->set_method_type(method_type());
2342 }
2343 }
2344
2345 // report back to the caller with the MethodType
2346 return method_type;
2347 }
2348
2349 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2350 Klass* accessing_klass,
2351 TRAPS) {
2352 Handle empty;
2353 ResourceMark rm(THREAD);
2354 SignatureStream ss(signature, /*is_method=*/ false);
2355 if (!ss.is_done()) {
2356 Handle class_loader, protection_domain;
2357 if (accessing_klass != NULL) {
2358 class_loader = Handle(THREAD, accessing_klass->class_loader());
2359 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2360 }
2361 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2362 ss.next();
2363 if (ss.is_done()) {
2364 return Handle(THREAD, mirror);
2365 }
2366 }
2367 return empty;
2368 }
2369
2370 // Ask Java code to find or construct a method handle constant.
2371 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2372 int ref_kind, //e.g., JVM_REF_invokeVirtual
2373 Klass* callee,
2374 Symbol* name,
2375 Symbol* signature,
2376 TRAPS) {
2377 Handle empty;
2378 if (caller == NULL) {
2379 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2380 }
2381 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2382 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2383
2384 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2385 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2386 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2387 java_lang_invoke_MemberName::set_name (mname(), name_str());
2388 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2389 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2390
2391 if (ref_kind == JVM_REF_invokeVirtual &&
2392 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2393 // Skip resolution for public signature polymorphic methods such as
2394 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2395 // They require appendix argument which MemberName resolution doesn't handle.
2396 // There's special logic on JDK side to handle them
2397 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2398 } else {
2399 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2400 }
2401
2402 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2403 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2404
2405 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2406 JavaCallArguments args;
2407 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2408 args.push_int(ref_kind);
2409 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2410 args.push_oop(name_str);
2411 args.push_oop(type);
2412 JavaValue result(T_OBJECT);
2413 JavaCalls::call_static(&result,
2414 vmClasses::MethodHandleNatives_klass(),
2415 vmSymbols::linkMethodHandleConstant_name(),
2416 vmSymbols::linkMethodHandleConstant_signature(),
2417 &args, CHECK_(empty));
2418 return Handle(THREAD, result.get_oop());
2419 }
2420
2421 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2422 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2423 // with linkage results being stored back into the bootstrap specifier.
2424 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2425 // Resolve the bootstrap specifier, its name, type, and static arguments
2426 bootstrap_specifier.resolve_bsm(CHECK);
2427
2428 // This should not happen. JDK code should take care of that.
2429 if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2430 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2431 }
2432
2433 bool is_indy = bootstrap_specifier.is_method_call();
2434 objArrayHandle appendix_box;
2435 if (is_indy) {
2436 // Some method calls may require an appendix argument. Arrange to receive it.
2437 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2438 assert(appendix_box->obj_at(0) == NULL, "");
2439 }
2440
2441 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info)
2442 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2443 JavaCallArguments args;
2444 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2445 args.push_int(bootstrap_specifier.bss_index());
2446 args.push_oop(bootstrap_specifier.bsm());
2447 args.push_oop(bootstrap_specifier.name_arg());
2448 args.push_oop(bootstrap_specifier.type_arg());
2449 args.push_oop(bootstrap_specifier.arg_values());
2450 if (is_indy) {
2451 args.push_oop(appendix_box);
2452 }
2453 JavaValue result(T_OBJECT);
2454 JavaCalls::call_static(&result,
2455 vmClasses::MethodHandleNatives_klass(),
2456 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2457 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2458 &args, CHECK);
2459
2460 Handle value(THREAD, result.get_oop());
2461 if (is_indy) {
2462 Handle appendix;
2463 Method* method = unpack_method_and_appendix(value,
2464 bootstrap_specifier.caller(),
2465 appendix_box,
2466 &appendix, CHECK);
2467 methodHandle mh(THREAD, method);
2468 bootstrap_specifier.set_resolved_method(mh, appendix);
2469 } else {
2470 bootstrap_specifier.set_resolved_value(value);
2471 }
2472
2473 // sanity check
2474 assert(bootstrap_specifier.is_resolved() ||
2475 (bootstrap_specifier.is_method_call() &&
2476 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2477 }
2478
2479
2480 ClassLoaderData* SystemDictionary::class_loader_data(Handle class_loader) {
2481 return ClassLoaderData::class_loader_data(class_loader());
2482 }
2483
2484 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2485 assert(m != NULL, "Unexpected NULL Method*");
2486 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2487 }
2488
2489 // ----------------------------------------------------------------------------
2490
2491 void SystemDictionary::print_on(outputStream *st) {
2492 CDS_ONLY(SystemDictionaryShared::print_on(st));
2493 GCMutexLocker mu(SystemDictionary_lock);
2494
2495 ClassLoaderDataGraph::print_dictionary(st);
2496
2497 // Placeholders
2498 placeholders()->print_on(st);
2499 st->cr();
2500
2501 // loader constraints - print under SD_lock
2502 constraints()->print_on(st);
2503 st->cr();
2504
2505 _pd_cache_table->print_on(st);
2506 st->cr();
2507 }
2508
2509 void SystemDictionary::print() { print_on(tty); }
2510
2511 void SystemDictionary::verify() {
2512 guarantee(constraints() != NULL,
2513 "Verify of loader constraints failed");
2514 guarantee(placeholders()->number_of_entries() >= 0,
2515 "Verify of placeholders failed");
2516
2517 GCMutexLocker mu(SystemDictionary_lock);
2518
2519 // Verify dictionary
2520 ClassLoaderDataGraph::verify_dictionary();
2521
2522 placeholders()->verify();
2523
2524 // Verify constraint table
2525 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2526 constraints()->verify(placeholders());
2527
2528 _pd_cache_table->verify();
2529 }
2530
2531 void SystemDictionary::dump(outputStream *st, bool verbose) {
2532 assert_locked_or_safepoint(SystemDictionary_lock);
2533 if (verbose) {
2534 print_on(st);
2535 } else {
2536 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2537 ClassLoaderDataGraph::print_table_statistics(st);
2538 placeholders()->print_table_statistics(st, "Placeholder Table");
2539 constraints()->print_table_statistics(st, "LoaderConstraints Table");
2540 pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table");
2541 }
2542 }
2543
2544 TableStatistics SystemDictionary::placeholders_statistics() {
2545 MutexLocker ml(SystemDictionary_lock);
2546 return placeholders()->statistics_calculate();
2547 }
2548
2549 TableStatistics SystemDictionary::loader_constraints_statistics() {
2550 MutexLocker ml(SystemDictionary_lock);
2551 return constraints()->statistics_calculate();
2552 }
2553
2554 TableStatistics SystemDictionary::protection_domain_cache_statistics() {
2555 MutexLocker ml(SystemDictionary_lock);
2556 return pd_cache_table()->statistics_calculate();
2557 }
2558
2559 // Utility for dumping dictionaries.
2560 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2561 DCmdWithParser(output, heap),
2562 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2563 "BOOLEAN", false, "false") {
2564 _dcmdparser.add_dcmd_option(&_verbose);
2565 }
2566
2567 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2568 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2569 _verbose.value());
2570 VMThread::execute(&dumper);
2571 }