1 /*
2 * Copyright (c) 1997, 2016, 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 "classfile/classFileParser.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/classLoaderData.inline.hpp"
30 #include "classfile/classLoaderExt.hpp"
31 #include "classfile/dictionary.hpp"
32 #include "classfile/javaClasses.inline.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "classfile/loaderConstraints.hpp"
35 #include "classfile/placeholders.hpp"
36 #include "classfile/resolutionErrors.hpp"
37 #include "classfile/stringTable.hpp"
38 #include "classfile/systemDictionary.hpp"
39 #include "classfile/vmSymbols.hpp"
40 #include "code/codeCache.hpp"
41 #include "compiler/compileBroker.hpp"
42 #include "gc/shared/gcLocker.hpp"
43 #include "interpreter/bytecodeStream.hpp"
44 #include "interpreter/interpreter.hpp"
45 #include "memory/filemap.hpp"
46 #include "memory/oopFactory.hpp"
47 #include "memory/resourceArea.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/instanceRefKlass.hpp"
50 #include "oops/klass.inline.hpp"
51 #include "oops/methodData.hpp"
52 #include "oops/objArrayKlass.hpp"
53 #include "oops/objArrayOop.inline.hpp"
54 #include "oops/oop.inline.hpp"
55 #include "oops/typeArrayKlass.hpp"
56 #include "prims/jvmtiEnvBase.hpp"
57 #include "prims/methodHandles.hpp"
58 #include "runtime/arguments.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/fieldType.hpp"
61 #include "runtime/handles.inline.hpp"
62 #include "runtime/java.hpp"
63 #include "runtime/javaCalls.hpp"
64 #include "runtime/mutexLocker.hpp"
65 #include "runtime/orderAccess.inline.hpp"
66 #include "runtime/signature.hpp"
67 #include "services/classLoadingService.hpp"
68 #include "services/threadService.hpp"
69 #include "utilities/macros.hpp"
70 #include "utilities/ticks.hpp"
71 #if INCLUDE_CDS
72 #include "classfile/sharedClassUtil.hpp"
73 #include "classfile/systemDictionaryShared.hpp"
74 #endif
75 #if INCLUDE_JVMCI
76 #include "jvmci/jvmciRuntime.hpp"
77 #endif
78 #if INCLUDE_TRACE
79 #include "trace/tracing.hpp"
80 #endif
81
82 Dictionary* SystemDictionary::_dictionary = NULL;
83 PlaceholderTable* SystemDictionary::_placeholders = NULL;
84 Dictionary* SystemDictionary::_shared_dictionary = NULL;
85 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
86 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
87 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
88
89
90 int SystemDictionary::_number_of_modifications = 0;
91 int SystemDictionary::_sdgeneration = 0;
92 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
93 20201,40423,99991};
94
95 oop SystemDictionary::_system_loader_lock_obj = NULL;
96
97 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
98 = { NULL /*, NULL...*/ };
99
100 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
101
102 oop SystemDictionary::_java_system_loader = NULL;
103
104 bool SystemDictionary::_has_loadClassInternal = false;
105 bool SystemDictionary::_has_checkPackageAccess = false;
106
107 // lazily initialized klass variables
108 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
109
110
111 // ----------------------------------------------------------------------------
112 // Java-level SystemLoader
113
114 oop SystemDictionary::java_system_loader() {
115 return _java_system_loader;
116 }
117
118 void SystemDictionary::compute_java_system_loader(TRAPS) {
119 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
120 JavaValue result(T_OBJECT);
121 JavaCalls::call_static(&result,
122 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
123 vmSymbols::getSystemClassLoader_name(),
124 vmSymbols::void_classloader_signature(),
125 CHECK);
126
127 _java_system_loader = (oop)result.get_jobject();
128
129 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
130 }
131
132
133 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
134 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
135 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
136 }
137
138 // ----------------------------------------------------------------------------
139 // debugging
140
141 #ifdef ASSERT
142
143 // return true if class_name contains no '.' (internal format is '/')
144 bool SystemDictionary::is_internal_format(Symbol* class_name) {
145 if (class_name != NULL) {
146 ResourceMark rm;
147 char* name = class_name->as_C_string();
148 return strchr(name, '.') == NULL;
149 } else {
150 return true;
151 }
152 }
153
154 #endif
155
156 // ----------------------------------------------------------------------------
157 // Parallel class loading check
158
159 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
160 if (UnsyncloadClass || class_loader.is_null()) return true;
161 if (AlwaysLockClassLoader) return false;
162 return java_lang_ClassLoader::parallelCapable(class_loader());
163 }
164 // ----------------------------------------------------------------------------
165 // ParallelDefineClass flag does not apply to bootclass loader
166 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
167 if (class_loader.is_null()) return false;
168 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
169 return true;
170 }
171 return false;
172 }
173
174 /**
175 * Returns true if the passed class loader is the extension class loader.
176 */
177 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
178 if (class_loader.is_null()) {
179 return false;
180 }
181 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
182 }
183
184 // ----------------------------------------------------------------------------
185 // Resolving of classes
186
187 // Forwards to resolve_or_null
188
189 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
190 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
191 if (HAS_PENDING_EXCEPTION || klass == NULL) {
192 KlassHandle k_h(THREAD, klass);
193 // can return a null klass
194 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD);
195 }
196 return klass;
197 }
198
199 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
200 bool throw_error,
201 KlassHandle klass_h, TRAPS) {
202 if (HAS_PENDING_EXCEPTION) {
203 // If we have a pending exception we forward it to the caller, unless throw_error is true,
204 // in which case we have to check whether the pending exception is a ClassNotFoundException,
205 // and if so convert it to a NoClassDefFoundError
206 // And chain the original ClassNotFoundException
207 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
208 ResourceMark rm(THREAD);
209 assert(klass_h() == NULL, "Should not have result with exception pending");
210 Handle e(THREAD, PENDING_EXCEPTION);
211 CLEAR_PENDING_EXCEPTION;
212 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
213 } else {
214 return NULL;
215 }
216 }
217 // Class not found, throw appropriate error or exception depending on value of throw_error
218 if (klass_h() == NULL) {
219 ResourceMark rm(THREAD);
220 if (throw_error) {
221 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
222 } else {
223 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
224 }
225 }
226 return (Klass*)klass_h();
227 }
228
229
230 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
231 bool throw_error, TRAPS)
232 {
233 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
234 }
235
236
237 // Forwards to resolve_instance_class_or_null
238
239 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
240 assert(THREAD->can_call_java(),
241 "can not load classes with compiler thread: class=%s, classloader=%s",
242 class_name->as_C_string(),
243 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
244 if (FieldType::is_array(class_name)) {
245 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
246 } else if (FieldType::is_obj(class_name)) {
247 ResourceMark rm(THREAD);
248 // Ignore wrapping L and ;.
249 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
250 class_name->utf8_length() - 2, CHECK_NULL);
251 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
252 } else {
253 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
254 }
255 }
256
257 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
258 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
259 }
260
261 // Forwards to resolve_instance_class_or_null
262
263 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
264 Handle class_loader,
265 Handle protection_domain,
266 TRAPS) {
267 assert(FieldType::is_array(class_name), "must be array");
268 Klass* k = NULL;
269 FieldArrayInfo fd;
270 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
271 // of this call
272 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
273 if (t == T_OBJECT) {
274 // naked oop "k" is OK here -- we assign back into it
275 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
276 class_loader,
277 protection_domain,
278 CHECK_NULL);
279 if (k != NULL) {
280 k = k->array_klass(fd.dimension(), CHECK_NULL);
281 }
282 } else {
283 k = Universe::typeArrayKlassObj(t);
284 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
285 }
286 return k;
287 }
288
289
290 // Must be called for any super-class or super-interface resolution
291 // during class definition to allow class circularity checking
292 // super-interface callers:
293 // parse_interfaces - for defineClass & jvmtiRedefineClasses
294 // super-class callers:
295 // ClassFileParser - for defineClass & jvmtiRedefineClasses
296 // load_shared_class - while loading a class from shared archive
297 // resolve_instance_class_or_null:
298 // via: handle_parallel_super_load
299 // when resolving a class that has an existing placeholder with
300 // a saved superclass [i.e. a defineClass is currently in progress]
301 // if another thread is trying to resolve the class, it must do
302 // super-class checks on its own thread to catch class circularity
303 // This last call is critical in class circularity checking for cases
304 // where classloading is delegated to different threads and the
305 // classloader lock is released.
306 // Take the case: Base->Super->Base
307 // 1. If thread T1 tries to do a defineClass of class Base
308 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
309 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
310 // so it tries to load Super
311 // 3. If we load the class internally, or user classloader uses same thread
312 // loadClassFromxxx or defineClass via parseClassFile Super ...
313 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
314 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
315 // 3.4 calls resolve_super_or_fail Base
316 // 3.5 finds T1,Base -> throws class circularity
317 //OR 4. If T2 tries to resolve Super via defineClass Super ...
318 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
319 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
320 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
321 // 4.4 finds T2, Super -> throws class circularity
322 // Must be called, even if superclass is null, since this is
323 // where the placeholder entry is created which claims this
324 // thread is loading this class/classloader.
325 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
326 Symbol* class_name,
327 Handle class_loader,
328 Handle protection_domain,
329 bool is_superclass,
330 TRAPS) {
331 #if INCLUDE_CDS
332 if (DumpSharedSpaces) {
333 // Special processing for CDS dump time.
334 Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
335 class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
336 if (k) {
337 return k;
338 }
339 }
340 #endif // INCLUDE_CDS
341
342 // Double-check, if child class is already loaded, just return super-class,interface
343 // Don't add a placedholder if already loaded, i.e. already in system dictionary
344 // Make sure there's a placeholder for the *child* before resolving.
345 // Used as a claim that this thread is currently loading superclass/classloader
346 // Used here for ClassCircularity checks and also for heap verification
347 // (every InstanceKlass in the heap needs to be in the system dictionary
348 // or have a placeholder).
349 // Must check ClassCircularity before checking if super class is already loaded
350 //
351 // We might not already have a placeholder if this child_name was
352 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
353 // the name of the class might not be known until the stream is actually
354 // parsed.
355 // Bugs 4643874, 4715493
356 // compute_hash can have a safepoint
357
358 ClassLoaderData* loader_data = class_loader_data(class_loader);
359 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
360 int d_index = dictionary()->hash_to_index(d_hash);
361 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
362 int p_index = placeholders()->hash_to_index(p_hash);
363 // can't throw error holding a lock
364 bool child_already_loaded = false;
365 bool throw_circularity_error = false;
366 {
367 MutexLocker mu(SystemDictionary_lock, THREAD);
368 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
369 Klass* quicksuperk;
370 // to support // loading: if child done loading, just return superclass
371 // if class_name, & class_loader don't match:
372 // if initial define, SD update will give LinkageError
373 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
374 // so we don't throw an exception here.
375 // see: nsk redefclass014 & java.lang.instrument Instrument032
376 if ((childk != NULL ) && (is_superclass) &&
377 ((quicksuperk = childk->super()) != NULL) &&
378
379 ((quicksuperk->name() == class_name) &&
380 (quicksuperk->class_loader() == class_loader()))) {
381 return quicksuperk;
382 } else {
383 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
384 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
385 throw_circularity_error = true;
386 }
387 }
388 if (!throw_circularity_error) {
389 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
390 }
391 }
392 if (throw_circularity_error) {
393 ResourceMark rm(THREAD);
394 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
395 }
396
397 // java.lang.Object should have been found above
398 assert(class_name != NULL, "null super class for resolving");
399 // Resolve the super class or interface, check results on return
400 Klass* superk = SystemDictionary::resolve_or_null(class_name,
401 class_loader,
402 protection_domain,
403 THREAD);
404
405 KlassHandle superk_h(THREAD, superk);
406
407 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
408 // It is no longer necessary to keep the placeholder table alive until update_dictionary
409 // or error. GC used to walk the placeholder table as strong roots.
410 // The instanceKlass is kept alive because the class loader is on the stack,
411 // which keeps the loader_data alive, as well as all instanceKlasses in
412 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
413 {
414 MutexLocker mu(SystemDictionary_lock, THREAD);
415 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
416 SystemDictionary_lock->notify_all();
417 }
418 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
419 // can null superk
420 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD));
421 }
422
423 return superk_h();
424 }
425
426 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
427 Handle class_loader,
428 Handle protection_domain,
429 TRAPS) {
430 if(!has_checkPackageAccess()) return;
431
432 // Now we have to call back to java to check if the initating class has access
433 JavaValue result(T_VOID);
434 if (log_is_enabled(Debug, protectiondomain)) {
435 ResourceMark rm;
436 // Print out trace information
437 outputStream* log = LogHandle(protectiondomain)::debug_stream();
438 log->print_cr("Checking package access");
439 log->print("class loader: "); class_loader()->print_value_on(log);
440 log->print(" protection domain: "); protection_domain()->print_value_on(log);
441 log->print(" loading: "); klass()->print_value_on(log);
442 log->cr();
443 }
444
445 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
446 JavaCalls::call_special(&result,
447 class_loader,
448 system_loader,
449 vmSymbols::checkPackageAccess_name(),
450 vmSymbols::class_protectiondomain_signature(),
451 Handle(THREAD, klass->java_mirror()),
452 protection_domain,
453 THREAD);
454
455 if (HAS_PENDING_EXCEPTION) {
456 log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
457 } else {
458 log_debug(protectiondomain)("granted");
459 }
460
461 if (HAS_PENDING_EXCEPTION) return;
462
463 // If no exception has been thrown, we have validated the protection domain
464 // Insert the protection domain of the initiating class into the set.
465 {
466 // We recalculate the entry here -- we've called out to java since
467 // the last time it was calculated.
468 ClassLoaderData* loader_data = class_loader_data(class_loader);
469
470 Symbol* kn = klass->name();
471 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
472 int d_index = dictionary()->hash_to_index(d_hash);
473
474 MutexLocker mu(SystemDictionary_lock, THREAD);
475 {
476 // Note that we have an entry, and entries can be deleted only during GC,
477 // so we cannot allow GC to occur while we're holding this entry.
478
479 // We're using a NoSafepointVerifier to catch any place where we
480 // might potentially do a GC at all.
481 // Dictionary::do_unloading() asserts that classes in SD are only
482 // unloaded at a safepoint. Anonymous classes are not in SD.
483 NoSafepointVerifier nosafepoint;
484 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
485 protection_domain, THREAD);
486 }
487 }
488 }
489
490 // We only get here if this thread finds that another thread
491 // has already claimed the placeholder token for the current operation,
492 // but that other thread either never owned or gave up the
493 // object lock
494 // Waits on SystemDictionary_lock to indicate placeholder table updated
495 // On return, caller must recheck placeholder table state
496 //
497 // We only get here if
498 // 1) custom classLoader, i.e. not bootstrap classloader
499 // 2) UnsyncloadClass not set
500 // 3) custom classLoader has broken the class loader objectLock
501 // so another thread got here in parallel
502 //
503 // lockObject must be held.
504 // Complicated dance due to lock ordering:
505 // Must first release the classloader object lock to
506 // allow initial definer to complete the class definition
507 // and to avoid deadlock
508 // Reclaim classloader lock object with same original recursion count
509 // Must release SystemDictionary_lock after notify, since
510 // class loader lock must be claimed before SystemDictionary_lock
511 // to prevent deadlocks
512 //
513 // The notify allows applications that did an untimed wait() on
514 // the classloader object lock to not hang.
515 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
516 assert_lock_strong(SystemDictionary_lock);
517
518 bool calledholdinglock
519 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
520 assert(calledholdinglock,"must hold lock for notify");
521 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
522 ObjectSynchronizer::notifyall(lockObject, THREAD);
523 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
524 SystemDictionary_lock->wait();
525 SystemDictionary_lock->unlock();
526 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
527 SystemDictionary_lock->lock();
528 }
529
530 // If the class in is in the placeholder table, class loading is in progress
531 // For cases where the application changes threads to load classes, it
532 // is critical to ClassCircularity detection that we try loading
533 // the superclass on the same thread internally, so we do parallel
534 // super class loading here.
535 // This also is critical in cases where the original thread gets stalled
536 // even in non-circularity situations.
537 // Note: must call resolve_super_or_fail even if null super -
538 // to force placeholder entry creation for this class for circularity detection
539 // Caller must check for pending exception
540 // Returns non-null Klass* if other thread has completed load
541 // and we are done,
542 // If return null Klass* and no pending exception, the caller must load the class
543 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
544 Symbol* name, Symbol* superclassname, Handle class_loader,
545 Handle protection_domain, Handle lockObject, TRAPS) {
546
547 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
548 ClassLoaderData* loader_data = class_loader_data(class_loader);
549 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
550 int d_index = dictionary()->hash_to_index(d_hash);
551 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
552 int p_index = placeholders()->hash_to_index(p_hash);
553
554 // superk is not used, resolve_super called for circularity check only
555 // This code is reached in two situations. One if this thread
556 // is loading the same class twice (e.g. ClassCircularity, or
557 // java.lang.instrument).
558 // The second is if another thread started the resolve_super first
559 // and has not yet finished.
560 // In both cases the original caller will clean up the placeholder
561 // entry on error.
562 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
563 superclassname,
564 class_loader,
565 protection_domain,
566 true,
567 CHECK_(nh));
568
569 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
570 // Serial class loaders and bootstrap classloader do wait for superclass loads
571 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
572 MutexLocker mu(SystemDictionary_lock, THREAD);
573 // Check if classloading completed while we were loading superclass or waiting
574 Klass* check = find_class(d_index, d_hash, name, loader_data);
575 if (check != NULL) {
576 // Klass is already loaded, so just return it
577 return(instanceKlassHandle(THREAD, check));
578 } else {
579 return nh;
580 }
581 }
582
583 // must loop to both handle other placeholder updates
584 // and spurious notifications
585 bool super_load_in_progress = true;
586 PlaceholderEntry* placeholder;
587 while (super_load_in_progress) {
588 MutexLocker mu(SystemDictionary_lock, THREAD);
589 // Check if classloading completed while we were loading superclass or waiting
590 Klass* check = find_class(d_index, d_hash, name, loader_data);
591 if (check != NULL) {
592 // Klass is already loaded, so just return it
593 return(instanceKlassHandle(THREAD, check));
594 } else {
595 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
596 if (placeholder && placeholder->super_load_in_progress() ){
597 // Before UnsyncloadClass:
598 // We only get here if the application has released the
599 // classloader lock when another thread was in the middle of loading a
600 // superclass/superinterface for this class, and now
601 // this thread is also trying to load this class.
602 // To minimize surprises, the first thread that started to
603 // load a class should be the one to complete the loading
604 // with the classfile it initially expected.
605 // This logic has the current thread wait once it has done
606 // all the superclass/superinterface loading it can, until
607 // the original thread completes the class loading or fails
608 // If it completes we will use the resulting InstanceKlass
609 // which we will find below in the systemDictionary.
610 // We also get here for parallel bootstrap classloader
611 if (class_loader.is_null()) {
612 SystemDictionary_lock->wait();
613 } else {
614 double_lock_wait(lockObject, THREAD);
615 }
616 } else {
617 // If not in SD and not in PH, other thread's load must have failed
618 super_load_in_progress = false;
619 }
620 }
621 }
622 return (nh);
623 }
624
625 // utility function for class load event
626 static void post_class_load_event(const Ticks& start_time,
627 instanceKlassHandle k,
628 Handle initiating_loader) {
629 #if INCLUDE_TRACE
630 EventClassLoad event(UNTIMED);
631 if (event.should_commit()) {
632 event.set_starttime(start_time);
633 event.set_loadedClass(k());
634 oop defining_class_loader = k->class_loader();
635 event.set_definingClassLoader(defining_class_loader != NULL ?
636 defining_class_loader->klass() : (Klass*)NULL);
637 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
638 event.set_initiatingClassLoader(class_loader != NULL ?
639 class_loader->klass() : (Klass*)NULL);
640 event.commit();
641 }
642 #endif // INCLUDE_TRACE
643 }
644
645 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
646 Handle class_loader,
647 Handle protection_domain,
648 TRAPS) {
649 assert(name != NULL && !FieldType::is_array(name) &&
650 !FieldType::is_obj(name), "invalid class name");
651
652 Ticks class_load_start_time = Ticks::now();
653
654 // Fix for 4474172; see evaluation for more details
655 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
656 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
657
658 // Do lookup to see if class already exist and the protection domain
659 // has the right access
660 // This call uses find which checks protection domain already matches
661 // All subsequent calls use find_class, and set has_loaded_class so that
662 // before we return a result we call out to java to check for valid protection domain
663 // to allow returning the Klass* and add it to the pd_set if it is valid
664 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
665 int d_index = dictionary()->hash_to_index(d_hash);
666 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
667 protection_domain, THREAD);
668 if (probe != NULL) return probe;
669
670
671 // Non-bootstrap class loaders will call out to class loader and
672 // define via jvm/jni_DefineClass which will acquire the
673 // class loader object lock to protect against multiple threads
674 // defining the class in parallel by accident.
675 // This lock must be acquired here so the waiter will find
676 // any successful result in the SystemDictionary and not attempt
677 // the define
678 // ParallelCapable Classloaders and the bootstrap classloader,
679 // or all classloaders with UnsyncloadClass do not acquire lock here
680 bool DoObjectLock = true;
681 if (is_parallelCapable(class_loader)) {
682 DoObjectLock = false;
683 }
684
685 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
686 int p_index = placeholders()->hash_to_index(p_hash);
687
688 // Class is not in SystemDictionary so we have to do loading.
689 // Make sure we are synchronized on the class loader before we proceed
690 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
691 check_loader_lock_contention(lockObject, THREAD);
692 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
693
694 // Check again (after locking) if class already exist in SystemDictionary
695 bool class_has_been_loaded = false;
696 bool super_load_in_progress = false;
697 bool havesupername = false;
698 instanceKlassHandle k;
699 PlaceholderEntry* placeholder;
700 Symbol* superclassname = NULL;
701
702 {
703 MutexLocker mu(SystemDictionary_lock, THREAD);
704 Klass* check = find_class(d_index, d_hash, name, loader_data);
705 if (check != NULL) {
706 // Klass is already loaded, so just return it
707 class_has_been_loaded = true;
708 k = instanceKlassHandle(THREAD, check);
709 } else {
710 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
711 if (placeholder && placeholder->super_load_in_progress()) {
712 super_load_in_progress = true;
713 if (placeholder->havesupername() == true) {
714 superclassname = placeholder->supername();
715 havesupername = true;
716 }
717 }
718 }
719 }
720
721 // If the class is in the placeholder table, class loading is in progress
722 if (super_load_in_progress && havesupername==true) {
723 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
724 class_loader, protection_domain, lockObject, THREAD);
725 if (HAS_PENDING_EXCEPTION) {
726 return NULL;
727 }
728 if (!k.is_null()) {
729 class_has_been_loaded = true;
730 }
731 }
732
733 bool throw_circularity_error = false;
734 if (!class_has_been_loaded) {
735 bool load_instance_added = false;
736
737 // add placeholder entry to record loading instance class
738 // Five cases:
739 // All cases need to prevent modifying bootclasssearchpath
740 // in parallel with a classload of same classname
741 // Redefineclasses uses existence of the placeholder for the duration
742 // of the class load to prevent concurrent redefinition of not completely
743 // defined classes.
744 // case 1. traditional classloaders that rely on the classloader object lock
745 // - no other need for LOAD_INSTANCE
746 // case 2. traditional classloaders that break the classloader object lock
747 // as a deadlock workaround. Detection of this case requires that
748 // this check is done while holding the classloader object lock,
749 // and that lock is still held when calling classloader's loadClass.
750 // For these classloaders, we ensure that the first requestor
751 // completes the load and other requestors wait for completion.
752 // case 3. UnsyncloadClass - don't use objectLocker
753 // With this flag, we allow parallel classloading of a
754 // class/classloader pair
755 // case4. Bootstrap classloader - don't own objectLocker
756 // This classloader supports parallelism at the classloader level,
757 // but only allows a single load of a class/classloader pair.
758 // No performance benefit and no deadlock issues.
759 // case 5. parallelCapable user level classloaders - without objectLocker
760 // Allow parallel classloading of a class/classloader pair
761
762 {
763 MutexLocker mu(SystemDictionary_lock, THREAD);
764 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
765 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
766 if (oldprobe) {
767 // only need check_seen_thread once, not on each loop
768 // 6341374 java/lang/Instrument with -Xcomp
769 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
770 throw_circularity_error = true;
771 } else {
772 // case 1: traditional: should never see load_in_progress.
773 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
774
775 // case 4: bootstrap classloader: prevent futile classloading,
776 // wait on first requestor
777 if (class_loader.is_null()) {
778 SystemDictionary_lock->wait();
779 } else {
780 // case 2: traditional with broken classloader lock. wait on first
781 // requestor.
782 double_lock_wait(lockObject, THREAD);
783 }
784 // Check if classloading completed while we were waiting
785 Klass* check = find_class(d_index, d_hash, name, loader_data);
786 if (check != NULL) {
787 // Klass is already loaded, so just return it
788 k = instanceKlassHandle(THREAD, check);
789 class_has_been_loaded = true;
790 }
791 // check if other thread failed to load and cleaned up
792 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
793 }
794 }
795 }
796 }
797 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
798 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
799 // LOAD_INSTANCE in parallel
800
801 if (!throw_circularity_error && !class_has_been_loaded) {
802 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
803 load_instance_added = true;
804 // For class loaders that do not acquire the classloader object lock,
805 // if they did not catch another thread holding LOAD_INSTANCE,
806 // need a check analogous to the acquire ObjectLocker/find_class
807 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
808 // one final check if the load has already completed
809 // class loaders holding the ObjectLock shouldn't find the class here
810 Klass* check = find_class(d_index, d_hash, name, loader_data);
811 if (check != NULL) {
812 // Klass is already loaded, so return it after checking/adding protection domain
813 k = instanceKlassHandle(THREAD, check);
814 class_has_been_loaded = true;
815 }
816 }
817 }
818
819 // must throw error outside of owning lock
820 if (throw_circularity_error) {
821 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
822 ResourceMark rm(THREAD);
823 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
824 }
825
826 if (!class_has_been_loaded) {
827
828 // Do actual loading
829 k = load_instance_class(name, class_loader, THREAD);
830
831 // For UnsyncloadClass only
832 // If they got a linkageError, check if a parallel class load succeeded.
833 // If it did, then for bytecode resolution the specification requires
834 // that we return the same result we did for the other thread, i.e. the
835 // successfully loaded InstanceKlass
836 // Should not get here for classloaders that support parallelism
837 // with the new cleaner mechanism, even with AllowParallelDefineClass
838 // Bootstrap goes through here to allow for an extra guarantee check
839 if (UnsyncloadClass || (class_loader.is_null())) {
840 if (k.is_null() && HAS_PENDING_EXCEPTION
841 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
842 MutexLocker mu(SystemDictionary_lock, THREAD);
843 Klass* check = find_class(d_index, d_hash, name, loader_data);
844 if (check != NULL) {
845 // Klass is already loaded, so just use it
846 k = instanceKlassHandle(THREAD, check);
847 CLEAR_PENDING_EXCEPTION;
848 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
849 }
850 }
851 }
852
853 // If everything was OK (no exceptions, no null return value), and
854 // class_loader is NOT the defining loader, do a little more bookkeeping.
855 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
856 k->class_loader() != class_loader()) {
857
858 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
859
860 // Need to check for a PENDING_EXCEPTION again; check_constraints
861 // can throw and doesn't use the CHECK macro.
862 if (!HAS_PENDING_EXCEPTION) {
863 { // Grabbing the Compile_lock prevents systemDictionary updates
864 // during compilations.
865 MutexLocker mu(Compile_lock, THREAD);
866 update_dictionary(d_index, d_hash, p_index, p_hash,
867 k, class_loader, THREAD);
868 }
869
870 if (JvmtiExport::should_post_class_load()) {
871 Thread *thread = THREAD;
872 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
873 JvmtiExport::post_class_load((JavaThread *) thread, k());
874 }
875 }
876 }
877 } // load_instance_class loop
878
879 if (load_instance_added == true) {
880 // clean up placeholder entries for LOAD_INSTANCE success or error
881 // This brackets the SystemDictionary updates for both defining
882 // and initiating loaders
883 MutexLocker mu(SystemDictionary_lock, THREAD);
884 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
885 SystemDictionary_lock->notify_all();
886 }
887 }
888
889 if (HAS_PENDING_EXCEPTION || k.is_null()) {
890 return NULL;
891 }
892
893 post_class_load_event(class_load_start_time, k, class_loader);
894
895 #ifdef ASSERT
896 {
897 ClassLoaderData* loader_data = k->class_loader_data();
898 MutexLocker mu(SystemDictionary_lock, THREAD);
899 Klass* kk = find_class(name, loader_data);
900 assert(kk == k(), "should be present in dictionary");
901 }
902 #endif
903
904 // return if the protection domain in NULL
905 if (protection_domain() == NULL) return k();
906
907 // Check the protection domain has the right access
908 {
909 MutexLocker mu(SystemDictionary_lock, THREAD);
910 // Note that we have an entry, and entries can be deleted only during GC,
911 // so we cannot allow GC to occur while we're holding this entry.
912 // We're using a NoSafepointVerifier to catch any place where we
913 // might potentially do a GC at all.
914 // Dictionary::do_unloading() asserts that classes in SD are only
915 // unloaded at a safepoint. Anonymous classes are not in SD.
916 NoSafepointVerifier nosafepoint;
917 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
918 loader_data,
919 protection_domain)) {
920 return k();
921 }
922 }
923
924 // Verify protection domain. If it fails an exception is thrown
925 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
926
927 return k();
928 }
929
930
931 // This routine does not lock the system dictionary.
932 //
933 // Since readers don't hold a lock, we must make sure that system
934 // dictionary entries are only removed at a safepoint (when only one
935 // thread is running), and are added to in a safe way (all links must
936 // be updated in an MT-safe manner).
937 //
938 // Callers should be aware that an entry could be added just after
939 // _dictionary->bucket(index) is read here, so the caller will not see
940 // the new entry.
941
942 Klass* SystemDictionary::find(Symbol* class_name,
943 Handle class_loader,
944 Handle protection_domain,
945 TRAPS) {
946
947 // The result of this call should be consistent with the result
948 // of the call to resolve_instance_class_or_null().
949 // See evaluation 6790209 and 4474172 for more details.
950 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
951 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
952
953 if (loader_data == NULL) {
954 // If the ClassLoaderData has not been setup,
955 // then the class loader has no entries in the dictionary.
956 return NULL;
957 }
958
959 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
960 int d_index = dictionary()->hash_to_index(d_hash);
961
962 {
963 // Note that we have an entry, and entries can be deleted only during GC,
964 // so we cannot allow GC to occur while we're holding this entry.
965 // We're using a NoSafepointVerifier to catch any place where we
966 // might potentially do a GC at all.
967 // Dictionary::do_unloading() asserts that classes in SD are only
968 // unloaded at a safepoint. Anonymous classes are not in SD.
969 NoSafepointVerifier nosafepoint;
970 return dictionary()->find(d_index, d_hash, class_name, loader_data,
971 protection_domain, THREAD);
972 }
973 }
974
975
976 // Look for a loaded instance or array klass by name. Do not do any loading.
977 // return NULL in case of error.
978 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
979 Handle class_loader,
980 Handle protection_domain,
981 TRAPS) {
982 Klass* k = NULL;
983 assert(class_name != NULL, "class name must be non NULL");
984
985 if (FieldType::is_array(class_name)) {
986 // The name refers to an array. Parse the name.
987 // dimension and object_key in FieldArrayInfo are assigned as a
988 // side-effect of this call
989 FieldArrayInfo fd;
990 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
991 if (t != T_OBJECT) {
992 k = Universe::typeArrayKlassObj(t);
993 } else {
994 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
995 }
996 if (k != NULL) {
997 k = k->array_klass_or_null(fd.dimension());
998 }
999 } else {
1000 k = find(class_name, class_loader, protection_domain, THREAD);
1001 }
1002 return k;
1003 }
1004
1005 // Note: this method is much like resolve_from_stream, but
1006 // updates no supplemental data structures.
1007 // TODO consolidate the two methods with a helper routine?
1008 Klass* SystemDictionary::parse_stream(Symbol* class_name,
1009 Handle class_loader,
1010 Handle protection_domain,
1011 ClassFileStream* st,
1012 const Klass* host_klass,
1013 GrowableArray<Handle>* cp_patches,
1014 TRAPS) {
1015
1016 Ticks class_load_start_time = Ticks::now();
1017
1018 ClassLoaderData* loader_data;
1019 if (host_klass != NULL) {
1020 // Create a new CLD for anonymous class, that uses the same class loader
1021 // as the host_klass
1022 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1023 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
1024 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1025 loader_data->record_dependency(host_klass, CHECK_NULL);
1026 } else {
1027 loader_data = ClassLoaderData::class_loader_data(class_loader());
1028 }
1029
1030 assert(st != NULL, "invariant");
1031 assert(st->need_verify(), "invariant");
1032
1033 // Parse stream and create a klass.
1034 // Note that we do this even though this klass might
1035 // already be present in the SystemDictionary, otherwise we would not
1036 // throw potential ClassFormatErrors.
1037
1038 instanceKlassHandle k = KlassFactory::create_from_stream(st,
1039 class_name,
1040 loader_data,
1041 protection_domain,
1042 host_klass,
1043 cp_patches,
1044 NULL, // parsed_name
1045 THREAD);
1046
1047 if (host_klass != NULL && k.not_null()) {
1048 // If it's anonymous, initialize it now, since nobody else will.
1049
1050 {
1051 MutexLocker mu_r(Compile_lock, THREAD);
1052
1053 // Add to class hierarchy, initialize vtables, and do possible
1054 // deoptimizations.
1055 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1056
1057 // But, do not add to system dictionary.
1058
1059 // compiled code dependencies need to be validated anyway
1060 notice_modification();
1061 }
1062
1063 // Rewrite and patch constant pool here.
1064 k->link_class(CHECK_NULL);
1065 if (cp_patches != NULL) {
1066 k->constants()->patch_resolved_references(cp_patches);
1067 }
1068 k->eager_initialize(CHECK_NULL);
1069
1070 // notify jvmti
1071 if (JvmtiExport::should_post_class_load()) {
1072 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1073 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1074 }
1075
1076 post_class_load_event(class_load_start_time, k, class_loader);
1077 }
1078 assert(host_klass != NULL || NULL == cp_patches,
1079 "cp_patches only found with host_klass");
1080
1081 return k();
1082 }
1083
1084 // Add a klass to the system from a stream (called by jni_DefineClass and
1085 // JVM_DefineClass).
1086 // Note: class_name can be NULL. In that case we do not know the name of
1087 // the class until we have parsed the stream.
1088
1089 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1090 Handle class_loader,
1091 Handle protection_domain,
1092 ClassFileStream* st,
1093 TRAPS) {
1094
1095 // Classloaders that support parallelism, e.g. bootstrap classloader,
1096 // or all classloaders with UnsyncloadClass do not acquire lock here
1097 bool DoObjectLock = true;
1098 if (is_parallelCapable(class_loader)) {
1099 DoObjectLock = false;
1100 }
1101
1102 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1103
1104 // Make sure we are synchronized on the class loader before we proceed
1105 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1106 check_loader_lock_contention(lockObject, THREAD);
1107 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1108
1109 assert(st != NULL, "invariant");
1110
1111 // Parse the stream and create a klass.
1112 // Note that we do this even though this klass might
1113 // already be present in the SystemDictionary, otherwise we would not
1114 // throw potential ClassFormatErrors.
1115 //
1116 // Note: "parsed_name" is updated.
1117 TempNewSymbol parsed_name = NULL;
1118
1119 instanceKlassHandle k;
1120
1121 #if INCLUDE_CDS
1122 k = SystemDictionaryShared::lookup_from_stream(class_name,
1123 class_loader,
1124 protection_domain,
1125 st,
1126 CHECK_NULL);
1127 #endif
1128
1129 if (k.not_null()) {
1130 parsed_name = k->name();
1131 } else {
1132 if (st->buffer() == NULL) {
1133 return NULL;
1134 }
1135 k = KlassFactory::create_from_stream(st,
1136 class_name,
1137 loader_data,
1138 protection_domain,
1139 NULL, // host_klass
1140 NULL, // cp_patches
1141 &parsed_name,
1142 THREAD);
1143 }
1144
1145 const char* pkg = "java/";
1146 if (!HAS_PENDING_EXCEPTION &&
1147 !class_loader.is_null() &&
1148 parsed_name != NULL &&
1149 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1150 // It is illegal to define classes in the "java." package from
1151 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1152 ResourceMark rm(THREAD);
1153 char* name = parsed_name->as_C_string();
1154 char* index = strrchr(name, '/');
1155 *index = '\0'; // chop to just the package name
1156 while ((index = strchr(name, '/')) != NULL) {
1157 *index = '.'; // replace '/' with '.' in package name
1158 }
1159 const char* fmt = "Prohibited package name: %s";
1160 size_t len = strlen(fmt) + strlen(name);
1161 char* message = NEW_RESOURCE_ARRAY(char, len);
1162 jio_snprintf(message, len, fmt, name);
1163 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1164 vmSymbols::java_lang_SecurityException(), message);
1165 }
1166
1167 if (!HAS_PENDING_EXCEPTION) {
1168 assert(parsed_name != NULL, "Sanity");
1169 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1170 // Verification prevents us from creating names with dots in them, this
1171 // asserts that that's the case.
1172 assert(is_internal_format(parsed_name),
1173 "external class name format used internally");
1174
1175 // Add class just loaded
1176 // If a class loader supports parallel classloading handle parallel define requests
1177 // find_or_define_instance_class may return a different InstanceKlass
1178 if (is_parallelCapable(class_loader)) {
1179 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1180 } else {
1181 define_instance_class(k, THREAD);
1182 }
1183 }
1184
1185 // Make sure we have an entry in the SystemDictionary on success
1186 debug_only( {
1187 if (!HAS_PENDING_EXCEPTION) {
1188 assert(parsed_name != NULL, "parsed_name is still null?");
1189 Symbol* h_name = k->name();
1190 ClassLoaderData *defining_loader_data = k->class_loader_data();
1191
1192 MutexLocker mu(SystemDictionary_lock, THREAD);
1193
1194 Klass* check = find_class(parsed_name, loader_data);
1195 assert(check == k(), "should be present in the dictionary");
1196
1197 Klass* check2 = find_class(h_name, defining_loader_data);
1198 assert(check == check2, "name inconsistancy in SystemDictionary");
1199 }
1200 } );
1201
1202 return k();
1203 }
1204
1205 #if INCLUDE_CDS
1206 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1207 int number_of_entries) {
1208 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1209 "bad shared dictionary size.");
1210 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1211 }
1212
1213
1214 // If there is a shared dictionary, then find the entry for the
1215 // given shared system class, if any.
1216
1217 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1218 if (shared_dictionary() != NULL) {
1219 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1220 int d_index = shared_dictionary()->hash_to_index(d_hash);
1221
1222 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1223 } else {
1224 return NULL;
1225 }
1226 }
1227
1228
1229 // Load a class from the shared spaces (found through the shared system
1230 // dictionary). Force the superclass and all interfaces to be loaded.
1231 // Update the class definition to include sibling classes and no
1232 // subclasses (yet). [Classes in the shared space are not part of the
1233 // object hierarchy until loaded.]
1234
1235 instanceKlassHandle SystemDictionary::load_shared_class(
1236 Symbol* class_name, Handle class_loader, TRAPS) {
1237 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1238 // Make sure we only return the boot class for the NULL classloader.
1239 if (ik.not_null() &&
1240 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1241 Handle protection_domain;
1242 return load_shared_class(ik, class_loader, protection_domain, THREAD);
1243 }
1244 return instanceKlassHandle();
1245 }
1246
1247 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1248 Handle class_loader,
1249 Handle protection_domain, TRAPS) {
1250 if (ik.not_null()) {
1251 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1252 Symbol* class_name = ik->name();
1253
1254 // Found the class, now load the superclass and interfaces. If they
1255 // are shared, add them to the main system dictionary and reset
1256 // their hierarchy references (supers, subs, and interfaces).
1257
1258 if (ik->super() != NULL) {
1259 Symbol* cn = ik->super()->name();
1260 Klass *s = resolve_super_or_fail(class_name, cn,
1261 class_loader, protection_domain, true, CHECK_(nh));
1262 if (s != ik->super()) {
1263 // The dynamically resolved super class is not the same as the one we used during dump time,
1264 // so we cannot use ik.
1265 return nh;
1266 }
1267 }
1268
1269 Array<Klass*>* interfaces = ik->local_interfaces();
1270 int num_interfaces = interfaces->length();
1271 for (int index = 0; index < num_interfaces; index++) {
1272 Klass* k = interfaces->at(index);
1273
1274 // Note: can not use InstanceKlass::cast here because
1275 // interfaces' InstanceKlass's C++ vtbls haven't been
1276 // reinitialized yet (they will be once the interface classes
1277 // are loaded)
1278 Symbol* name = k->name();
1279 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1280 if (k != i) {
1281 // The dynamically resolved interface class is not the same as the one we used during dump time,
1282 // so we cannot use ik.
1283 return nh;
1284 }
1285 }
1286
1287 // Adjust methods to recover missing data. They need addresses for
1288 // interpreter entry points and their default native method address
1289 // must be reset.
1290
1291 // Updating methods must be done under a lock so multiple
1292 // threads don't update these in parallel
1293 //
1294 // Shared classes are all currently loaded by either the bootstrap or
1295 // internal parallel class loaders, so this will never cause a deadlock
1296 // on a custom class loader lock.
1297
1298 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1299 {
1300 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1301 check_loader_lock_contention(lockObject, THREAD);
1302 ObjectLocker ol(lockObject, THREAD, true);
1303 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1304 }
1305
1306 if (log_is_enabled(Info, classload)) {
1307 ik()->print_loading_log(LogLevel::Info, loader_data, NULL);
1308 }
1309 // No 'else' here as logging levels are not mutually exclusive
1310
1311 if (log_is_enabled(Debug, classload)) {
1312 ik()->print_loading_log(LogLevel::Debug, loader_data, NULL);
1313 }
1314
1315 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1316 // Only dump the classes that can be stored into CDS archive
1317 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1318 ResourceMark rm(THREAD);
1319 classlist_file->print_cr("%s", ik->name()->as_C_string());
1320 classlist_file->flush();
1321 }
1322 }
1323
1324 // notify a class loaded from shared object
1325 ClassLoadingService::notify_class_loaded(ik(), true /* shared class */);
1326 }
1327 return ik;
1328 }
1329 #endif // INCLUDE_CDS
1330
1331 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1332 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1333 if (class_loader.is_null()) {
1334
1335 // Search the shared system dictionary for classes preloaded into the
1336 // shared spaces.
1337 instanceKlassHandle k;
1338 {
1339 #if INCLUDE_CDS
1340 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1341 k = load_shared_class(class_name, class_loader, THREAD);
1342 #endif
1343 }
1344
1345 if (k.is_null()) {
1346 // Use VM class loader
1347 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1348 k = ClassLoader::load_class(class_name, CHECK_(nh));
1349 }
1350
1351 // find_or_define_instance_class may return a different InstanceKlass
1352 if (!k.is_null()) {
1353 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1354 }
1355 return k;
1356 } else {
1357 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1358 ResourceMark rm(THREAD);
1359
1360 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1361 JavaThread* jt = (JavaThread*) THREAD;
1362
1363 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1364 ClassLoader::perf_app_classload_selftime(),
1365 ClassLoader::perf_app_classload_count(),
1366 jt->get_thread_stat()->perf_recursion_counts_addr(),
1367 jt->get_thread_stat()->perf_timers_addr(),
1368 PerfClassTraceTime::CLASS_LOAD);
1369
1370 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1371 // Translate to external class name format, i.e., convert '/' chars to '.'
1372 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1373
1374 JavaValue result(T_OBJECT);
1375
1376 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1377
1378 // Call public unsynchronized loadClass(String) directly for all class loaders
1379 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1380 // acquire a class-name based lock rather than the class loader object lock.
1381 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1382 // so the call to loadClassInternal() was not required.
1383 //
1384 // UnsyncloadClass flag means both call loadClass(String) and do
1385 // not acquire the class loader lock even for class loaders that are
1386 // not parallelCapable. This was a risky transitional
1387 // flag for diagnostic purposes only. It is risky to call
1388 // custom class loaders without synchronization.
1389 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1390 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1391 // Do NOT assume this will be supported in future releases.
1392 //
1393 // Added MustCallLoadClassInternal in case we discover in the field
1394 // a customer that counts on this call
1395 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1396 JavaCalls::call_special(&result,
1397 class_loader,
1398 spec_klass,
1399 vmSymbols::loadClassInternal_name(),
1400 vmSymbols::string_class_signature(),
1401 string,
1402 CHECK_(nh));
1403 } else {
1404 JavaCalls::call_virtual(&result,
1405 class_loader,
1406 spec_klass,
1407 vmSymbols::loadClass_name(),
1408 vmSymbols::string_class_signature(),
1409 string,
1410 CHECK_(nh));
1411 }
1412
1413 assert(result.get_type() == T_OBJECT, "just checking");
1414 oop obj = (oop) result.get_jobject();
1415
1416 // Primitive classes return null since forName() can not be
1417 // used to obtain any of the Class objects representing primitives or void
1418 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1419 instanceKlassHandle k =
1420 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1421 // For user defined Java class loaders, check that the name returned is
1422 // the same as that requested. This check is done for the bootstrap
1423 // loader when parsing the class file.
1424 if (class_name == k->name()) {
1425 return k;
1426 }
1427 }
1428 // Class is not found or has the wrong name, return NULL
1429 return nh;
1430 }
1431 }
1432
1433 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1434
1435 ClassLoaderData* loader_data = k->class_loader_data();
1436 Handle class_loader_h(THREAD, loader_data->class_loader());
1437
1438 // for bootstrap and other parallel classloaders don't acquire lock,
1439 // use placeholder token
1440 // If a parallelCapable class loader calls define_instance_class instead of
1441 // find_or_define_instance_class to get here, we have a timing
1442 // hole with systemDictionary updates and check_constraints
1443 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1444 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1445 compute_loader_lock_object(class_loader_h, THREAD)),
1446 "define called without lock");
1447 }
1448
1449 // Check class-loading constraints. Throw exception if violation is detected.
1450 // Grabs and releases SystemDictionary_lock
1451 // The check_constraints/find_class call and update_dictionary sequence
1452 // must be "atomic" for a specific class/classloader pair so we never
1453 // define two different instanceKlasses for that class/classloader pair.
1454 // Existing classloaders will call define_instance_class with the
1455 // classloader lock held
1456 // Parallel classloaders will call find_or_define_instance_class
1457 // which will require a token to perform the define class
1458 Symbol* name_h = k->name();
1459 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1460 int d_index = dictionary()->hash_to_index(d_hash);
1461 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1462
1463 // Register class just loaded with class loader (placed in Vector)
1464 // Note we do this before updating the dictionary, as this can
1465 // fail with an OutOfMemoryError (if it does, we will *not* put this
1466 // class in the dictionary and will not update the class hierarchy).
1467 // JVMTI FollowReferences needs to find the classes this way.
1468 if (k->class_loader() != NULL) {
1469 methodHandle m(THREAD, Universe::loader_addClass_method());
1470 JavaValue result(T_VOID);
1471 JavaCallArguments args(class_loader_h);
1472 args.push_oop(Handle(THREAD, k->java_mirror()));
1473 JavaCalls::call(&result, m, &args, CHECK);
1474 }
1475
1476 // Add the new class. We need recompile lock during update of CHA.
1477 {
1478 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1479 int p_index = placeholders()->hash_to_index(p_hash);
1480
1481 MutexLocker mu_r(Compile_lock, THREAD);
1482
1483 // Add to class hierarchy, initialize vtables, and do possible
1484 // deoptimizations.
1485 add_to_hierarchy(k, CHECK); // No exception, but can block
1486
1487 // Add to systemDictionary - so other classes can see it.
1488 // Grabs and releases SystemDictionary_lock
1489 update_dictionary(d_index, d_hash, p_index, p_hash,
1490 k, class_loader_h, THREAD);
1491 }
1492 k->eager_initialize(THREAD);
1493
1494 // notify jvmti
1495 if (JvmtiExport::should_post_class_load()) {
1496 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1497 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1498
1499 }
1500
1501 }
1502
1503 // Support parallel classloading
1504 // All parallel class loaders, including bootstrap classloader
1505 // lock a placeholder entry for this class/class_loader pair
1506 // to allow parallel defines of different classes for this class loader
1507 // With AllowParallelDefine flag==true, in case they do not synchronize around
1508 // FindLoadedClass/DefineClass, calls, we check for parallel
1509 // loading for them, wait if a defineClass is in progress
1510 // and return the initial requestor's results
1511 // This flag does not apply to the bootstrap classloader.
1512 // With AllowParallelDefine flag==false, call through to define_instance_class
1513 // which will throw LinkageError: duplicate class definition.
1514 // False is the requested default.
1515 // For better performance, the class loaders should synchronize
1516 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1517 // potentially waste time reading and parsing the bytestream.
1518 // Note: VM callers should ensure consistency of k/class_name,class_loader
1519 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1520
1521 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1522 Symbol* name_h = k->name(); // passed in class_name may be null
1523 ClassLoaderData* loader_data = class_loader_data(class_loader);
1524
1525 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1526 int d_index = dictionary()->hash_to_index(d_hash);
1527
1528 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1529 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1530 int p_index = placeholders()->hash_to_index(p_hash);
1531 PlaceholderEntry* probe;
1532
1533 {
1534 MutexLocker mu(SystemDictionary_lock, THREAD);
1535 // First check if class already defined
1536 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1537 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1538 if (check != NULL) {
1539 return(instanceKlassHandle(THREAD, check));
1540 }
1541 }
1542
1543 // Acquire define token for this class/classloader
1544 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1545 // Wait if another thread defining in parallel
1546 // All threads wait - even those that will throw duplicate class: otherwise
1547 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1548 // if other thread has not finished updating dictionary
1549 while (probe->definer() != NULL) {
1550 SystemDictionary_lock->wait();
1551 }
1552 // Only special cases allow parallel defines and can use other thread's results
1553 // Other cases fall through, and may run into duplicate defines
1554 // caught by finding an entry in the SystemDictionary
1555 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1556 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1557 SystemDictionary_lock->notify_all();
1558 #ifdef ASSERT
1559 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1560 assert(check != NULL, "definer missed recording success");
1561 #endif
1562 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1563 } else {
1564 // This thread will define the class (even if earlier thread tried and had an error)
1565 probe->set_definer(THREAD);
1566 }
1567 }
1568
1569 define_instance_class(k, THREAD);
1570
1571 Handle linkage_exception = Handle(); // null handle
1572
1573 // definer must notify any waiting threads
1574 {
1575 MutexLocker mu(SystemDictionary_lock, THREAD);
1576 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1577 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1578 if (probe != NULL) {
1579 if (HAS_PENDING_EXCEPTION) {
1580 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1581 CLEAR_PENDING_EXCEPTION;
1582 } else {
1583 probe->set_instance_klass(k());
1584 }
1585 probe->set_definer(NULL);
1586 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1587 SystemDictionary_lock->notify_all();
1588 }
1589 }
1590
1591 // Can't throw exception while holding lock due to rank ordering
1592 if (linkage_exception() != NULL) {
1593 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1594 }
1595
1596 return k;
1597 }
1598 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1599 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1600 if (class_loader.is_null()) {
1601 return Handle(THREAD, _system_loader_lock_obj);
1602 } else {
1603 return class_loader;
1604 }
1605 }
1606
1607 // This method is added to check how often we have to wait to grab loader
1608 // lock. The results are being recorded in the performance counters defined in
1609 // ClassLoader::_sync_systemLoaderLockContentionRate and
1610 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1611 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1612 if (!UsePerfData) {
1613 return;
1614 }
1615
1616 assert(!loader_lock.is_null(), "NULL lock object");
1617
1618 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1619 == ObjectSynchronizer::owner_other) {
1620 // contention will likely happen, so increment the corresponding
1621 // contention counter.
1622 if (loader_lock() == _system_loader_lock_obj) {
1623 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1624 } else {
1625 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1626 }
1627 }
1628 }
1629
1630 // ----------------------------------------------------------------------------
1631 // Lookup
1632
1633 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1634 Symbol* class_name,
1635 ClassLoaderData* loader_data) {
1636 assert_locked_or_safepoint(SystemDictionary_lock);
1637 assert (index == dictionary()->index_for(class_name, loader_data),
1638 "incorrect index?");
1639
1640 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1641 return k;
1642 }
1643
1644
1645 // Basic find on classes in the midst of being loaded
1646 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1647 ClassLoaderData* loader_data) {
1648 assert_locked_or_safepoint(SystemDictionary_lock);
1649 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1650 int p_index = placeholders()->hash_to_index(p_hash);
1651 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1652 }
1653
1654
1655 // Used for assertions and verification only
1656 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1657 #ifndef ASSERT
1658 guarantee(VerifyBeforeGC ||
1659 VerifyDuringGC ||
1660 VerifyBeforeExit ||
1661 VerifyDuringStartup ||
1662 VerifyAfterGC, "too expensive");
1663 #endif
1664 assert_locked_or_safepoint(SystemDictionary_lock);
1665
1666 // First look in the loaded class array
1667 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1668 int d_index = dictionary()->hash_to_index(d_hash);
1669 return find_class(d_index, d_hash, class_name, loader_data);
1670 }
1671
1672
1673 // Get the next class in the diictionary.
1674 Klass* SystemDictionary::try_get_next_class() {
1675 return dictionary()->try_get_next_class();
1676 }
1677
1678
1679 // ----------------------------------------------------------------------------
1680 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1681 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1682 // before a new class is used.
1683
1684 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1685 assert(k.not_null(), "just checking");
1686 assert_locked_or_safepoint(Compile_lock);
1687
1688 // Link into hierachy. Make sure the vtables are initialized before linking into
1689 k->append_to_sibling_list(); // add to superklass/sibling list
1690 k->process_interfaces(THREAD); // handle all "implements" declarations
1691 k->set_init_state(InstanceKlass::loaded);
1692 // Now flush all code that depended on old class hierarchy.
1693 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1694 // Also, first reinitialize vtable because it may have gotten out of synch
1695 // while the new class wasn't connected to the class hierarchy.
1696 CodeCache::flush_dependents_on(k);
1697 }
1698
1699 // ----------------------------------------------------------------------------
1700 // GC support
1701
1702 // Following roots during mark-sweep is separated in two phases.
1703 //
1704 // The first phase follows preloaded classes and all other system
1705 // classes, since these will never get unloaded anyway.
1706 //
1707 // The second phase removes (unloads) unreachable classes from the
1708 // system dictionary and follows the remaining classes' contents.
1709
1710 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1711 roots_oops_do(blk, NULL);
1712 }
1713
1714 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1715 // Follow all system classes and temporary placeholders in dictionary
1716 dictionary()->always_strong_classes_do(closure);
1717
1718 // Placeholders. These represent classes we're actively loading.
1719 placeholders()->classes_do(closure);
1720 }
1721
1722 // Calculate a "good" systemdictionary size based
1723 // on predicted or current loaded classes count
1724 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1725 int newsize = _old_default_sdsize;
1726 if ((classcount > 0) && !DumpSharedSpaces) {
1727 int desiredsize = classcount/_average_depth_goal;
1728 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1729 newsize = _primelist[++_sdgeneration]) {
1730 if (desiredsize <= newsize) {
1731 break;
1732 }
1733 }
1734 }
1735 return newsize;
1736 }
1737
1738 #ifdef ASSERT
1739 class VerifySDReachableAndLiveClosure : public OopClosure {
1740 private:
1741 BoolObjectClosure* _is_alive;
1742
1743 template <class T> void do_oop_work(T* p) {
1744 oop obj = oopDesc::load_decode_heap_oop(p);
1745 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1746 }
1747
1748 public:
1749 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1750
1751 virtual void do_oop(oop* p) { do_oop_work(p); }
1752 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1753 };
1754 #endif
1755
1756 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1757 // Note: anonymous classes are not in the SD.
1758 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1759 bool clean_previous_versions) {
1760 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1761 bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1762 clean_previous_versions);
1763 if (unloading_occurred) {
1764 dictionary()->do_unloading();
1765 constraints()->purge_loader_constraints();
1766 resolution_errors()->purge_resolution_errors();
1767 }
1768 // Oops referenced by the system dictionary may get unreachable independently
1769 // of the class loader (eg. cached protection domain oops). So we need to
1770 // explicitly unlink them here instead of in Dictionary::do_unloading.
1771 dictionary()->unlink(is_alive);
1772 #ifdef ASSERT
1773 VerifySDReachableAndLiveClosure cl(is_alive);
1774 dictionary()->oops_do(&cl);
1775 #endif
1776 return unloading_occurred;
1777 }
1778
1779 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1780 strong->do_oop(&_java_system_loader);
1781 strong->do_oop(&_system_loader_lock_obj);
1782 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1783
1784 // Adjust dictionary
1785 dictionary()->roots_oops_do(strong, weak);
1786
1787 // Visit extra methods
1788 invoke_method_table()->oops_do(strong);
1789 }
1790
1791 void SystemDictionary::oops_do(OopClosure* f) {
1792 f->do_oop(&_java_system_loader);
1793 f->do_oop(&_system_loader_lock_obj);
1794 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1795
1796 // Adjust dictionary
1797 dictionary()->oops_do(f);
1798
1799 // Visit extra methods
1800 invoke_method_table()->oops_do(f);
1801 }
1802
1803 // Extended Class redefinition support.
1804 // If one of these classes is replaced, we need to replace it in these places.
1805 // KlassClosure::do_klass should take the address of a class but we can
1806 // change that later.
1807 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1808 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1809 f->do_klass(_well_known_klasses[k]);
1810 }
1811
1812 {
1813 for (int i = 0; i < T_VOID+1; i++) {
1814 if (_box_klasses[i] != NULL) {
1815 assert(i >= T_BOOLEAN, "checking");
1816 f->do_klass(_box_klasses[i]);
1817 }
1818 }
1819 }
1820
1821 FilteredFieldsMap::classes_do(f);
1822 }
1823
1824 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1825 f->do_klass(_abstract_ownable_synchronizer_klass);
1826 }
1827
1828 // Just the classes from defining class loaders
1829 // Don't iterate over placeholders
1830 void SystemDictionary::classes_do(void f(Klass*)) {
1831 dictionary()->classes_do(f);
1832 }
1833
1834 // Added for initialize_itable_for_klass
1835 // Just the classes from defining class loaders
1836 // Don't iterate over placeholders
1837 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1838 dictionary()->classes_do(f, CHECK);
1839 }
1840
1841 // All classes, and their class loaders
1842 // Don't iterate over placeholders
1843 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1844 dictionary()->classes_do(f);
1845 }
1846
1847 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1848 placeholders()->entries_do(f);
1849 }
1850
1851 void SystemDictionary::methods_do(void f(Method*)) {
1852 dictionary()->methods_do(f);
1853 invoke_method_table()->methods_do(f);
1854 }
1855
1856 void SystemDictionary::remove_classes_in_error_state() {
1857 dictionary()->remove_classes_in_error_state();
1858 }
1859
1860 // ----------------------------------------------------------------------------
1861 // Lazily load klasses
1862
1863 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1864 // if multiple threads calling this function, only one thread will load
1865 // the class. The other threads will find the loaded version once the
1866 // class is loaded.
1867 Klass* aos = _abstract_ownable_synchronizer_klass;
1868 if (aos == NULL) {
1869 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1870 // Force a fence to prevent any read before the write completes
1871 OrderAccess::fence();
1872 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1873 }
1874 }
1875
1876 // ----------------------------------------------------------------------------
1877 // Initialization
1878
1879 void SystemDictionary::initialize(TRAPS) {
1880 // Allocate arrays
1881 assert(dictionary() == NULL,
1882 "SystemDictionary should only be initialized once");
1883 _sdgeneration = 0;
1884 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1885 _placeholders = new PlaceholderTable(_nof_buckets);
1886 _number_of_modifications = 0;
1887 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1888 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1889 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1890
1891 // Allocate private object used as system class loader lock
1892 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1893 // Initialize basic classes
1894 initialize_preloaded_classes(CHECK);
1895 }
1896
1897 // Compact table of directions on the initialization of klasses:
1898 static const short wk_init_info[] = {
1899 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1900 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1901 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1902 | (int)SystemDictionary::option ),
1903 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1904 #undef WK_KLASS_INIT_INFO
1905 0
1906 };
1907
1908 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1909 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1910 int info = wk_init_info[id - FIRST_WKID];
1911 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1912 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1913 InstanceKlass** klassp = &_well_known_klasses[id];
1914 bool must_load = (init_opt < SystemDictionary::Opt);
1915 if ((*klassp) == NULL) {
1916 Klass* k;
1917 if (must_load) {
1918 k = resolve_or_fail(symbol, true, CHECK_0); // load required class
1919 } else {
1920 k = resolve_or_null(symbol, CHECK_0); // load optional klass
1921 }
1922 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
1923 }
1924 return ((*klassp) != NULL);
1925 }
1926
1927 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1928 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1929 for (int id = (int)start_id; id < (int)limit_id; id++) {
1930 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1931 int info = wk_init_info[id - FIRST_WKID];
1932 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1933 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1934
1935 initialize_wk_klass((WKID)id, opt, CHECK);
1936 }
1937
1938 // move the starting value forward to the limit:
1939 start_id = limit_id;
1940 }
1941
1942 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1943 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1944 // Preload commonly used klasses
1945 WKID scan = FIRST_WKID;
1946 // first do Object, then String, Class
1947 if (UseSharedSpaces) {
1948 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1949 // Initialize the constant pool for the Object_class
1950 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1951 ik->constants()->restore_unshareable_info(CHECK);
1952 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1953 } else {
1954 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1955 }
1956
1957 // Calculate offsets for String and Class classes since they are loaded and
1958 // can be used after this point.
1959 java_lang_String::compute_offsets();
1960 java_lang_Class::compute_offsets();
1961
1962 // Fixup mirrors for classes loaded before java.lang.Class.
1963 // These calls iterate over the objects currently in the perm gen
1964 // so calling them at this point is matters (not before when there
1965 // are fewer objects and not later after there are more objects
1966 // in the perm gen.
1967 Universe::initialize_basic_type_mirrors(CHECK);
1968 Universe::fixup_mirrors(CHECK);
1969
1970 // do a bunch more:
1971 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1972
1973 // Preload ref klasses and set reference types
1974 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1975 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1976
1977 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1978 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1979 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1980 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1981 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1982
1983 // JSR 292 classes
1984 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1985 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1986 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1987 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1988 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
1989
1990 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1991 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1992 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1993 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1994 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1995 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1996 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1997 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1998 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1999 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
2000
2001 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2002 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2003 _has_loadClassInternal = (method != NULL);
2004 }
2005 { // Compute whether we should use checkPackageAccess or NOT
2006 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2007 _has_checkPackageAccess = (method != NULL);
2008 }
2009 }
2010
2011 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2012 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2013 BasicType SystemDictionary::box_klass_type(Klass* k) {
2014 assert(k != NULL, "");
2015 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2016 if (_box_klasses[i] == k)
2017 return (BasicType)i;
2018 }
2019 return T_OBJECT;
2020 }
2021
2022 // Constraints on class loaders. The details of the algorithm can be
2023 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2024 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2025 // that the system dictionary needs to maintain a set of contraints that
2026 // must be satisfied by all classes in the dictionary.
2027 // if defining is true, then LinkageError if already in systemDictionary
2028 // if initiating loader, then ok if InstanceKlass matches existing entry
2029
2030 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2031 instanceKlassHandle k,
2032 Handle class_loader, bool defining,
2033 TRAPS) {
2034 const char *linkage_error1 = NULL;
2035 const char *linkage_error2 = NULL;
2036 {
2037 Symbol* name = k->name();
2038 ClassLoaderData *loader_data = class_loader_data(class_loader);
2039
2040 MutexLocker mu(SystemDictionary_lock, THREAD);
2041
2042 Klass* check = find_class(d_index, d_hash, name, loader_data);
2043 if (check != (Klass*)NULL) {
2044 // if different InstanceKlass - duplicate class definition,
2045 // else - ok, class loaded by a different thread in parallel,
2046 // we should only have found it if it was done loading and ok to use
2047 // system dictionary only holds instance classes, placeholders
2048 // also holds array classes
2049
2050 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2051 if ((defining == true) || (k() != check)) {
2052 linkage_error1 = "loader (instance of ";
2053 linkage_error2 = "): attempted duplicate class definition for name: \"";
2054 } else {
2055 return;
2056 }
2057 }
2058
2059 #ifdef ASSERT
2060 Symbol* ph_check = find_placeholder(name, loader_data);
2061 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2062 #endif
2063
2064 if (linkage_error1 == NULL) {
2065 if (constraints()->check_or_update(k, class_loader, name) == false) {
2066 linkage_error1 = "loader constraint violation: loader (instance of ";
2067 linkage_error2 = ") previously initiated loading for a different type with name \"";
2068 }
2069 }
2070 }
2071
2072 // Throw error now if needed (cannot throw while holding
2073 // SystemDictionary_lock because of rank ordering)
2074
2075 if (linkage_error1) {
2076 ResourceMark rm(THREAD);
2077 const char* class_loader_name = loader_name(class_loader());
2078 char* type_name = k->name()->as_C_string();
2079 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2080 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2081 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2082 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2083 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2084 }
2085 }
2086
2087
2088 // Update system dictionary - done after check_constraint and add_to_hierachy
2089 // have been called.
2090 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2091 int p_index, unsigned int p_hash,
2092 instanceKlassHandle k,
2093 Handle class_loader,
2094 TRAPS) {
2095 // Compile_lock prevents systemDictionary updates during compilations
2096 assert_locked_or_safepoint(Compile_lock);
2097 Symbol* name = k->name();
2098 ClassLoaderData *loader_data = class_loader_data(class_loader);
2099
2100 {
2101 MutexLocker mu1(SystemDictionary_lock, THREAD);
2102
2103 // See whether biased locking is enabled and if so set it for this
2104 // klass.
2105 // Note that this must be done past the last potential blocking
2106 // point / safepoint. We enable biased locking lazily using a
2107 // VM_Operation to iterate the SystemDictionary and installing the
2108 // biasable mark word into each InstanceKlass's prototype header.
2109 // To avoid race conditions where we accidentally miss enabling the
2110 // optimization for one class in the process of being added to the
2111 // dictionary, we must not safepoint after the test of
2112 // BiasedLocking::enabled().
2113 if (UseBiasedLocking && BiasedLocking::enabled()) {
2114 // Set biased locking bit for all loaded classes; it will be
2115 // cleared if revocation occurs too often for this type
2116 // NOTE that we must only do this when the class is initally
2117 // defined, not each time it is referenced from a new class loader
2118 if (k->class_loader() == class_loader()) {
2119 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2120 }
2121 }
2122
2123 // Make a new system dictionary entry.
2124 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2125 if (sd_check == NULL) {
2126 dictionary()->add_klass(name, loader_data, k);
2127 notice_modification();
2128 }
2129 #ifdef ASSERT
2130 sd_check = find_class(d_index, d_hash, name, loader_data);
2131 assert (sd_check != NULL, "should have entry in system dictionary");
2132 // Note: there may be a placeholder entry: for circularity testing
2133 // or for parallel defines
2134 #endif
2135 SystemDictionary_lock->notify_all();
2136 }
2137 }
2138
2139
2140 // Try to find a class name using the loader constraints. The
2141 // loader constraints might know about a class that isn't fully loaded
2142 // yet and these will be ignored.
2143 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2144 Symbol* class_name, Handle class_loader, TRAPS) {
2145
2146 // First see if it has been loaded directly.
2147 // Force the protection domain to be null. (This removes protection checks.)
2148 Handle no_protection_domain;
2149 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2150 no_protection_domain, CHECK_NULL);
2151 if (klass != NULL)
2152 return klass;
2153
2154 // Now look to see if it has been loaded elsewhere, and is subject to
2155 // a loader constraint that would require this loader to return the
2156 // klass that is already loaded.
2157 if (FieldType::is_array(class_name)) {
2158 // For array classes, their Klass*s are not kept in the
2159 // constraint table. The element Klass*s are.
2160 FieldArrayInfo fd;
2161 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2162 if (t != T_OBJECT) {
2163 klass = Universe::typeArrayKlassObj(t);
2164 } else {
2165 MutexLocker mu(SystemDictionary_lock, THREAD);
2166 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2167 }
2168 // If element class already loaded, allocate array klass
2169 if (klass != NULL) {
2170 klass = klass->array_klass_or_null(fd.dimension());
2171 }
2172 } else {
2173 MutexLocker mu(SystemDictionary_lock, THREAD);
2174 // Non-array classes are easy: simply check the constraint table.
2175 klass = constraints()->find_constrained_klass(class_name, class_loader);
2176 }
2177
2178 return klass;
2179 }
2180
2181
2182 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2183 Handle class_loader1,
2184 Handle class_loader2,
2185 Thread* THREAD) {
2186 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2187 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2188
2189 Symbol* constraint_name = NULL;
2190 if (!FieldType::is_array(class_name)) {
2191 constraint_name = class_name;
2192 } else {
2193 // For array classes, their Klass*s are not kept in the
2194 // constraint table. The element classes are.
2195 FieldArrayInfo fd;
2196 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2197 // primitive types always pass
2198 if (t != T_OBJECT) {
2199 return true;
2200 } else {
2201 constraint_name = fd.object_key();
2202 }
2203 }
2204 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2205 int d_index1 = dictionary()->hash_to_index(d_hash1);
2206
2207 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2208 int d_index2 = dictionary()->hash_to_index(d_hash2);
2209 {
2210 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2211
2212 // Better never do a GC while we're holding these oops
2213 NoSafepointVerifier nosafepoint;
2214
2215 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2216 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2217 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2218 klass2, class_loader2);
2219 }
2220 }
2221
2222 // Add entry to resolution error table to record the error when the first
2223 // attempt to resolve a reference to a class has failed.
2224 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2225 Symbol* error, Symbol* message) {
2226 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2227 int index = resolution_errors()->hash_to_index(hash);
2228 {
2229 MutexLocker ml(SystemDictionary_lock, Thread::current());
2230 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2231 }
2232 }
2233
2234 // Delete a resolution error for RedefineClasses for a constant pool is going away
2235 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2236 resolution_errors()->delete_entry(pool);
2237 }
2238
2239 // Lookup resolution error table. Returns error if found, otherwise NULL.
2240 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2241 Symbol** message) {
2242 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2243 int index = resolution_errors()->hash_to_index(hash);
2244 {
2245 MutexLocker ml(SystemDictionary_lock, Thread::current());
2246 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2247 if (entry != NULL) {
2248 *message = entry->message();
2249 return entry->error();
2250 } else {
2251 return NULL;
2252 }
2253 }
2254 }
2255
2256
2257 // Signature constraints ensure that callers and callees agree about
2258 // the meaning of type names in their signatures. This routine is the
2259 // intake for constraints. It collects them from several places:
2260 //
2261 // * LinkResolver::resolve_method (if check_access is true) requires
2262 // that the resolving class (the caller) and the defining class of
2263 // the resolved method (the callee) agree on each type in the
2264 // method's signature.
2265 //
2266 // * LinkResolver::resolve_interface_method performs exactly the same
2267 // checks.
2268 //
2269 // * LinkResolver::resolve_field requires that the constant pool
2270 // attempting to link to a field agree with the field's defining
2271 // class about the type of the field signature.
2272 //
2273 // * klassVtable::initialize_vtable requires that, when a class
2274 // overrides a vtable entry allocated by a superclass, that the
2275 // overriding method (i.e., the callee) agree with the superclass
2276 // on each type in the method's signature.
2277 //
2278 // * klassItable::initialize_itable requires that, when a class fills
2279 // in its itables, for each non-abstract method installed in an
2280 // itable, the method (i.e., the callee) agree with the interface
2281 // on each type in the method's signature.
2282 //
2283 // All those methods have a boolean (check_access, checkconstraints)
2284 // which turns off the checks. This is used from specialized contexts
2285 // such as bootstrapping, dumping, and debugging.
2286 //
2287 // No direct constraint is placed between the class and its
2288 // supertypes. Constraints are only placed along linked relations
2289 // between callers and callees. When a method overrides or implements
2290 // an abstract method in a supertype (superclass or interface), the
2291 // constraints are placed as if the supertype were the caller to the
2292 // overriding method. (This works well, since callers to the
2293 // supertype have already established agreement between themselves and
2294 // the supertype.) As a result of all this, a class can disagree with
2295 // its supertype about the meaning of a type name, as long as that
2296 // class neither calls a relevant method of the supertype, nor is
2297 // called (perhaps via an override) from the supertype.
2298 //
2299 //
2300 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2301 //
2302 // Make sure all class components (including arrays) in the given
2303 // signature will be resolved to the same class in both loaders.
2304 // Returns the name of the type that failed a loader constraint check, or
2305 // NULL if no constraint failed. No exception except OOME is thrown.
2306 // Arrays are not added to the loader constraint table, their elements are.
2307 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2308 Handle loader1, Handle loader2,
2309 bool is_method, TRAPS) {
2310 // Nothing to do if loaders are the same.
2311 if (loader1() == loader2()) {
2312 return NULL;
2313 }
2314
2315 SignatureStream sig_strm(signature, is_method);
2316 while (!sig_strm.is_done()) {
2317 if (sig_strm.is_object()) {
2318 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2319 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2320 return sig;
2321 }
2322 }
2323 sig_strm.next();
2324 }
2325 return NULL;
2326 }
2327
2328
2329 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2330 Symbol* signature,
2331 TRAPS) {
2332 methodHandle empty;
2333 assert(MethodHandles::is_signature_polymorphic(iid) &&
2334 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2335 iid != vmIntrinsics::_invokeGeneric,
2336 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2337
2338 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2339 int index = invoke_method_table()->hash_to_index(hash);
2340 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2341 methodHandle m;
2342 if (spe == NULL || spe->method() == NULL) {
2343 spe = NULL;
2344 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2345 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2346 if (!Arguments::is_interpreter_only()) {
2347 // Generate a compiled form of the MH intrinsic.
2348 AdapterHandlerLibrary::create_native_wrapper(m);
2349 // Check if have the compiled code.
2350 if (!m->has_compiled_code()) {
2351 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2352 "Out of space in CodeCache for method handle intrinsic", empty);
2353 }
2354 }
2355 // Now grab the lock. We might have to throw away the new method,
2356 // if a racing thread has managed to install one at the same time.
2357 {
2358 MutexLocker ml(SystemDictionary_lock, THREAD);
2359 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2360 if (spe == NULL)
2361 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2362 if (spe->method() == NULL)
2363 spe->set_method(m());
2364 }
2365 }
2366
2367 assert(spe != NULL && spe->method() != NULL, "");
2368 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2369 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2370 "MH intrinsic invariant");
2371 return spe->method();
2372 }
2373
2374 // Helper for unpacking the return value from linkMethod and linkCallSite.
2375 static methodHandle unpack_method_and_appendix(Handle mname,
2376 KlassHandle accessing_klass,
2377 objArrayHandle appendix_box,
2378 Handle* appendix_result,
2379 TRAPS) {
2380 methodHandle empty;
2381 if (mname.not_null()) {
2382 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2383 if (vmtarget != NULL && vmtarget->is_method()) {
2384 Method* m = (Method*)vmtarget;
2385 oop appendix = appendix_box->obj_at(0);
2386 if (TraceMethodHandles) {
2387 #ifndef PRODUCT
2388 ttyLocker ttyl;
2389 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2390 m->print();
2391 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2392 tty->cr();
2393 #endif //PRODUCT
2394 }
2395 (*appendix_result) = Handle(THREAD, appendix);
2396 // the target is stored in the cpCache and if a reference to this
2397 // MethodName is dropped we need a way to make sure the
2398 // class_loader containing this method is kept alive.
2399 // FIXME: the appendix might also preserve this dependency.
2400 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2401 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2402 return methodHandle(THREAD, m);
2403 }
2404 }
2405 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2406 return empty;
2407 }
2408
2409 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2410 Symbol* signature,
2411 KlassHandle accessing_klass,
2412 Handle *appendix_result,
2413 Handle *method_type_result,
2414 TRAPS) {
2415 methodHandle empty;
2416 assert(THREAD->can_call_java() ,"");
2417 Handle method_type =
2418 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2419
2420 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2421 int ref_kind = JVM_REF_invokeVirtual;
2422 Handle name_str = StringTable::intern(name, CHECK_(empty));
2423 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2424 assert(appendix_box->obj_at(0) == NULL, "");
2425
2426 // This should not happen. JDK code should take care of that.
2427 if (accessing_klass.is_null() || method_type.is_null()) {
2428 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2429 }
2430
2431 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2432 JavaCallArguments args;
2433 args.push_oop(accessing_klass()->java_mirror());
2434 args.push_int(ref_kind);
2435 args.push_oop(mh_klass()->java_mirror());
2436 args.push_oop(name_str());
2437 args.push_oop(method_type());
2438 args.push_oop(appendix_box());
2439 JavaValue result(T_OBJECT);
2440 JavaCalls::call_static(&result,
2441 SystemDictionary::MethodHandleNatives_klass(),
2442 vmSymbols::linkMethod_name(),
2443 vmSymbols::linkMethod_signature(),
2444 &args, CHECK_(empty));
2445 Handle mname(THREAD, (oop) result.get_jobject());
2446 (*method_type_result) = method_type;
2447 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2448 }
2449
2450 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2451 // We must ensure that all class loaders everywhere will reach this class, for any client.
2452 // This is a safe bet for public classes in java.lang, such as Object and String.
2453 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2454 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2455 static bool is_always_visible_class(oop mirror) {
2456 Klass* klass = java_lang_Class::as_Klass(mirror);
2457 if (klass->is_objArray_klass()) {
2458 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2459 }
2460 if (klass->is_typeArray_klass()) {
2461 return true; // primitive array
2462 }
2463 assert(klass->is_instance_klass(), "%s", klass->external_name());
2464 return klass->is_public() &&
2465 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2466 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2467 }
2468
2469 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2470 // signature, as interpreted relative to the given class loader.
2471 // Because of class loader constraints, all method handle usage must be
2472 // consistent with this loader.
2473 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2474 KlassHandle accessing_klass,
2475 TRAPS) {
2476 Handle empty;
2477 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2478 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2479 int index = invoke_method_table()->hash_to_index(hash);
2480 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2481 if (spe != NULL && spe->method_type() != NULL) {
2482 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2483 return Handle(THREAD, spe->method_type());
2484 } else if (!THREAD->can_call_java()) {
2485 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2486 return Handle(); // do not attempt from within compiler, unless it was cached
2487 }
2488
2489 Handle class_loader, protection_domain;
2490 if (accessing_klass.not_null()) {
2491 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2492 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2493 }
2494 bool can_be_cached = true;
2495 int npts = ArgumentCount(signature).size();
2496 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2497 int arg = 0;
2498 Handle rt; // the return type from the signature
2499 ResourceMark rm(THREAD);
2500 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2501 oop mirror = NULL;
2502 if (can_be_cached) {
2503 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2504 mirror = ss.as_java_mirror(Handle(), Handle(),
2505 SignatureStream::ReturnNull, CHECK_(empty));
2506 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2507 // Fall back to accessing_klass context.
2508 can_be_cached = false;
2509 }
2510 }
2511 if (!can_be_cached) {
2512 // Resolve, throwing a real error if it doesn't work.
2513 mirror = ss.as_java_mirror(class_loader, protection_domain,
2514 SignatureStream::NCDFError, CHECK_(empty));
2515 }
2516 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2517 if (ss.at_return_type())
2518 rt = Handle(THREAD, mirror);
2519 else
2520 pts->obj_at_put(arg++, mirror);
2521
2522 // Check accessibility.
2523 if (ss.is_object() && accessing_klass.not_null()) {
2524 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2525 mirror = NULL; // safety
2526 // Emulate ConstantPool::verify_constant_pool_resolve.
2527 if (sel_klass->is_objArray_klass())
2528 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2529 if (sel_klass->is_instance_klass()) {
2530 KlassHandle sel_kh(THREAD, sel_klass);
2531 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2532 }
2533 }
2534 }
2535 assert(arg == npts, "");
2536
2537 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2538 JavaCallArguments args(Handle(THREAD, rt()));
2539 args.push_oop(pts());
2540 JavaValue result(T_OBJECT);
2541 JavaCalls::call_static(&result,
2542 SystemDictionary::MethodHandleNatives_klass(),
2543 vmSymbols::findMethodHandleType_name(),
2544 vmSymbols::findMethodHandleType_signature(),
2545 &args, CHECK_(empty));
2546 Handle method_type(THREAD, (oop) result.get_jobject());
2547
2548 if (can_be_cached) {
2549 // We can cache this MethodType inside the JVM.
2550 MutexLocker ml(SystemDictionary_lock, THREAD);
2551 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2552 if (spe == NULL)
2553 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2554 if (spe->method_type() == NULL) {
2555 spe->set_method_type(method_type());
2556 }
2557 }
2558
2559 // report back to the caller with the MethodType
2560 return method_type;
2561 }
2562
2563 // Ask Java code to find or construct a method handle constant.
2564 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2565 int ref_kind, //e.g., JVM_REF_invokeVirtual
2566 KlassHandle callee,
2567 Symbol* name_sym,
2568 Symbol* signature,
2569 TRAPS) {
2570 Handle empty;
2571 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2572 Handle type;
2573 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2574 type = find_method_handle_type(signature, caller, CHECK_(empty));
2575 } else if (caller.is_null()) {
2576 // This should not happen. JDK code should take care of that.
2577 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2578 } else {
2579 ResourceMark rm(THREAD);
2580 SignatureStream ss(signature, false);
2581 if (!ss.is_done()) {
2582 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2583 SignatureStream::NCDFError, CHECK_(empty));
2584 type = Handle(THREAD, mirror);
2585 ss.next();
2586 if (!ss.is_done()) type = Handle(); // error!
2587 }
2588 }
2589 if (type.is_null()) {
2590 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2591 }
2592
2593 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2594 JavaCallArguments args;
2595 args.push_oop(caller->java_mirror()); // the referring class
2596 args.push_int(ref_kind);
2597 args.push_oop(callee->java_mirror()); // the target class
2598 args.push_oop(name());
2599 args.push_oop(type());
2600 JavaValue result(T_OBJECT);
2601 JavaCalls::call_static(&result,
2602 SystemDictionary::MethodHandleNatives_klass(),
2603 vmSymbols::linkMethodHandleConstant_name(),
2604 vmSymbols::linkMethodHandleConstant_signature(),
2605 &args, CHECK_(empty));
2606 return Handle(THREAD, (oop) result.get_jobject());
2607 }
2608
2609 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2610 // name and signature, as interpreted relative to the given class loader.
2611 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2612 Handle bootstrap_specifier,
2613 Symbol* name,
2614 Symbol* type,
2615 Handle *appendix_result,
2616 Handle *method_type_result,
2617 TRAPS) {
2618 methodHandle empty;
2619 Handle bsm, info;
2620 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2621 bsm = bootstrap_specifier;
2622 } else {
2623 assert(bootstrap_specifier->is_objArray(), "");
2624 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2625 int len = args->length();
2626 assert(len >= 1, "");
2627 bsm = Handle(THREAD, args->obj_at(0));
2628 if (len > 1) {
2629 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2630 for (int i = 1; i < len; i++)
2631 args1->obj_at_put(i-1, args->obj_at(i));
2632 info = Handle(THREAD, args1);
2633 }
2634 }
2635 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2636 "caller must supply a valid BSM");
2637
2638 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2639 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2640
2641 // This should not happen. JDK code should take care of that.
2642 if (caller.is_null() || method_type.is_null()) {
2643 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2644 }
2645
2646 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2647 assert(appendix_box->obj_at(0) == NULL, "");
2648
2649 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2650 JavaCallArguments args;
2651 args.push_oop(caller->java_mirror());
2652 args.push_oop(bsm());
2653 args.push_oop(method_name());
2654 args.push_oop(method_type());
2655 args.push_oop(info());
2656 args.push_oop(appendix_box);
2657 JavaValue result(T_OBJECT);
2658 JavaCalls::call_static(&result,
2659 SystemDictionary::MethodHandleNatives_klass(),
2660 vmSymbols::linkCallSite_name(),
2661 vmSymbols::linkCallSite_signature(),
2662 &args, CHECK_(empty));
2663 Handle mname(THREAD, (oop) result.get_jobject());
2664 (*method_type_result) = method_type;
2665 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2666 }
2667
2668 // Since the identity hash code for symbols changes when the symbols are
2669 // moved from the regular perm gen (hash in the mark word) to the shared
2670 // spaces (hash is the address), the classes loaded into the dictionary
2671 // may be in the wrong buckets.
2672
2673 void SystemDictionary::reorder_dictionary() {
2674 dictionary()->reorder_dictionary();
2675 }
2676
2677
2678 void SystemDictionary::copy_buckets(char** top, char* end) {
2679 dictionary()->copy_buckets(top, end);
2680 }
2681
2682
2683 void SystemDictionary::copy_table(char** top, char* end) {
2684 dictionary()->copy_table(top, end);
2685 }
2686
2687
2688 void SystemDictionary::reverse() {
2689 dictionary()->reverse();
2690 }
2691
2692 int SystemDictionary::number_of_classes() {
2693 return dictionary()->number_of_entries();
2694 }
2695
2696
2697 // ----------------------------------------------------------------------------
2698 void SystemDictionary::print_shared(bool details) {
2699 shared_dictionary()->print(details);
2700 }
2701
2702 void SystemDictionary::print(bool details) {
2703 dictionary()->print(details);
2704
2705 // Placeholders
2706 GCMutexLocker mu(SystemDictionary_lock);
2707 placeholders()->print();
2708
2709 // loader constraints - print under SD_lock
2710 constraints()->print();
2711 }
2712
2713
2714 void SystemDictionary::verify() {
2715 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2716 guarantee(constraints() != NULL,
2717 "Verify of loader constraints failed");
2718 guarantee(dictionary()->number_of_entries() >= 0 &&
2719 placeholders()->number_of_entries() >= 0,
2720 "Verify of system dictionary failed");
2721
2722 // Verify dictionary
2723 dictionary()->verify();
2724
2725 GCMutexLocker mu(SystemDictionary_lock);
2726 placeholders()->verify();
2727
2728 // Verify constraint table
2729 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2730 constraints()->verify(dictionary(), placeholders());
2731 }
2732
2733 // caller needs ResourceMark
2734 const char* SystemDictionary::loader_name(const oop loader) {
2735 return ((loader) == NULL ? "<bootloader>" :
2736 InstanceKlass::cast((loader)->klass())->name()->as_C_string());
2737 }
2738
2739 // caller needs ResourceMark
2740 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
2741 return (loader_data->class_loader() == NULL ? "<bootloader>" :
2742 InstanceKlass::cast((loader_data->class_loader())->klass())->name()->as_C_string());
2743 }