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