1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classFileParser.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/classLoaderData.inline.hpp"
30 #include "classfile/classLoaderExt.hpp"
31 #include "classfile/dictionary.hpp"
32 #include "classfile/javaClasses.inline.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "classfile/loaderConstraints.hpp"
35 #include "classfile/placeholders.hpp"
36 #include "classfile/resolutionErrors.hpp"
37 #include "classfile/stringTable.hpp"
38 #include "classfile/systemDictionary.hpp"
39 #include "classfile/vmSymbols.hpp"
40 #include "code/codeCache.hpp"
41 #include "compiler/compileBroker.hpp"
42 #include "gc/shared/gcLocker.hpp"
43 #include "interpreter/bytecodeStream.hpp"
44 #include "interpreter/interpreter.hpp"
45 #include "logging/log.hpp"
46 #include "memory/filemap.hpp"
47 #include "memory/oopFactory.hpp"
48 #include "oops/instanceKlass.hpp"
49 #include "oops/instanceRefKlass.hpp"
50 #include "oops/klass.inline.hpp"
51 #include "oops/methodData.hpp"
52 #include "oops/objArrayKlass.hpp"
53 #include "oops/objArrayOop.inline.hpp"
54 #include "oops/oop.inline.hpp"
55 #include "oops/typeArrayKlass.hpp"
56 #include "prims/jvmtiEnvBase.hpp"
57 #include "prims/methodHandles.hpp"
58 #include "runtime/arguments.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/fieldType.hpp"
61 #include "runtime/handles.inline.hpp"
62 #include "runtime/java.hpp"
63 #include "runtime/javaCalls.hpp"
64 #include "runtime/mutexLocker.hpp"
65 #include "runtime/orderAccess.inline.hpp"
66 #include "runtime/signature.hpp"
67 #include "services/classLoadingService.hpp"
68 #include "services/threadService.hpp"
69 #include "utilities/macros.hpp"
70 #include "utilities/ticks.hpp"
71 #if INCLUDE_CDS
72 #include "classfile/sharedClassUtil.hpp"
73 #include "classfile/systemDictionaryShared.hpp"
74 #endif
75 #if INCLUDE_JVMCI
76 #include "jvmci/jvmciRuntime.hpp"
77 #endif
78 #if INCLUDE_TRACE
79 #include "trace/tracing.hpp"
80 #endif
81
82 Dictionary* SystemDictionary::_dictionary = NULL;
83 PlaceholderTable* SystemDictionary::_placeholders = NULL;
84 Dictionary* SystemDictionary::_shared_dictionary = NULL;
85 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
86 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
87 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
88
89
90 int SystemDictionary::_number_of_modifications = 0;
91 int SystemDictionary::_sdgeneration = 0;
92 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
93 20201,40423,99991};
94
95 oop SystemDictionary::_system_loader_lock_obj = NULL;
96
97 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
98 = { NULL /*, NULL...*/ };
99
100 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
101
102 oop SystemDictionary::_java_system_loader = NULL;
103
104 bool SystemDictionary::_has_loadClassInternal = false;
105 bool SystemDictionary::_has_checkPackageAccess = false;
106
107 // lazily initialized klass variables
108 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
109
110
111 // ----------------------------------------------------------------------------
112 // Java-level SystemLoader
113
114 oop SystemDictionary::java_system_loader() {
115 return _java_system_loader;
116 }
117
118 void SystemDictionary::compute_java_system_loader(TRAPS) {
119 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
120 JavaValue result(T_OBJECT);
121 JavaCalls::call_static(&result,
122 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
123 vmSymbols::getSystemClassLoader_name(),
124 vmSymbols::void_classloader_signature(),
125 CHECK);
126
127 _java_system_loader = (oop)result.get_jobject();
128
129 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
130 }
131
132
133 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
134 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
135 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
136 }
137
138 // ----------------------------------------------------------------------------
139 // debugging
140
141 #ifdef ASSERT
142
143 // return true if class_name contains no '.' (internal format is '/')
144 bool SystemDictionary::is_internal_format(Symbol* class_name) {
145 if (class_name != NULL) {
146 ResourceMark rm;
147 char* name = class_name->as_C_string();
148 return strchr(name, '.') == NULL;
149 } else {
150 return true;
151 }
152 }
153
154 #endif
155
156 // ----------------------------------------------------------------------------
157 // Parallel class loading check
158
159 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
160 if (UnsyncloadClass || class_loader.is_null()) return true;
161 if (AlwaysLockClassLoader) return false;
162 return java_lang_ClassLoader::parallelCapable(class_loader());
163 }
164 // ----------------------------------------------------------------------------
165 // ParallelDefineClass flag does not apply to bootclass loader
166 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
167 if (class_loader.is_null()) return false;
168 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
169 return true;
170 }
171 return false;
172 }
173
174 /**
175 * Returns true if the passed class loader is the extension class loader.
176 */
177 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
178 if (class_loader.is_null()) {
179 return false;
180 }
181 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
182 }
183
184 // ----------------------------------------------------------------------------
185 // Resolving of classes
186
187 // Forwards to resolve_or_null
188
189 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
190 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
191 if (HAS_PENDING_EXCEPTION || klass == NULL) {
192 KlassHandle k_h(THREAD, klass);
193 // can return a null klass
194 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD);
195 }
196 return klass;
197 }
198
199 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
200 bool throw_error,
201 KlassHandle klass_h, TRAPS) {
202 if (HAS_PENDING_EXCEPTION) {
203 // If we have a pending exception we forward it to the caller, unless throw_error is true,
204 // in which case we have to check whether the pending exception is a ClassNotFoundException,
205 // and if so convert it to a NoClassDefFoundError
206 // And chain the original ClassNotFoundException
207 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
208 ResourceMark rm(THREAD);
209 assert(klass_h() == NULL, "Should not have result with exception pending");
210 Handle e(THREAD, PENDING_EXCEPTION);
211 CLEAR_PENDING_EXCEPTION;
212 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
213 } else {
214 return NULL;
215 }
216 }
217 // Class not found, throw appropriate error or exception depending on value of throw_error
218 if (klass_h() == NULL) {
219 ResourceMark rm(THREAD);
220 if (throw_error) {
221 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
222 } else {
223 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
224 }
225 }
226 return (Klass*)klass_h();
227 }
228
229
230 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
231 bool throw_error, TRAPS)
232 {
233 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
234 }
235
236
237 // Forwards to resolve_instance_class_or_null
238
239 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
240 assert(THREAD->can_call_java(),
241 "can not load classes with compiler thread: class=%s, classloader=%s",
242 class_name->as_C_string(),
243 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
244 if (FieldType::is_array(class_name)) {
245 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
246 } else if (FieldType::is_obj(class_name)) {
247 ResourceMark rm(THREAD);
248 // Ignore wrapping L and ;.
249 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
250 class_name->utf8_length() - 2, CHECK_NULL);
251 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
252 } else {
253 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
254 }
255 }
256
257 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
258 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
259 }
260
261 // Forwards to resolve_instance_class_or_null
262
263 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
264 Handle class_loader,
265 Handle protection_domain,
266 TRAPS) {
267 assert(FieldType::is_array(class_name), "must be array");
268 Klass* k = NULL;
269 FieldArrayInfo fd;
270 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
271 // of this call
272 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
273 if (t == T_OBJECT) {
274 // naked oop "k" is OK here -- we assign back into it
275 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
276 class_loader,
277 protection_domain,
278 CHECK_NULL);
279 if (k != NULL) {
280 k = k->array_klass(fd.dimension(), CHECK_NULL);
281 }
282 } else {
283 k = Universe::typeArrayKlassObj(t);
284 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
285 }
286 return k;
287 }
288
289
290 // Must be called for any super-class or super-interface resolution
291 // during class definition to allow class circularity checking
292 // super-interface callers:
293 // parse_interfaces - for defineClass & jvmtiRedefineClasses
294 // super-class callers:
295 // ClassFileParser - for defineClass & jvmtiRedefineClasses
296 // load_shared_class - while loading a class from shared archive
297 // resolve_instance_class_or_null:
298 // via: handle_parallel_super_load
299 // when resolving a class that has an existing placeholder with
300 // a saved superclass [i.e. a defineClass is currently in progress]
301 // if another thread is trying to resolve the class, it must do
302 // super-class checks on its own thread to catch class circularity
303 // This last call is critical in class circularity checking for cases
304 // where classloading is delegated to different threads and the
305 // classloader lock is released.
306 // Take the case: Base->Super->Base
307 // 1. If thread T1 tries to do a defineClass of class Base
308 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
309 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
310 // so it tries to load Super
311 // 3. If we load the class internally, or user classloader uses same thread
312 // loadClassFromxxx or defineClass via parseClassFile Super ...
313 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
314 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
315 // 3.4 calls resolve_super_or_fail Base
316 // 3.5 finds T1,Base -> throws class circularity
317 //OR 4. If T2 tries to resolve Super via defineClass Super ...
318 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
319 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
320 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
321 // 4.4 finds T2, Super -> throws class circularity
322 // Must be called, even if superclass is null, since this is
323 // where the placeholder entry is created which claims this
324 // thread is loading this class/classloader.
325 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
326 Symbol* class_name,
327 Handle class_loader,
328 Handle protection_domain,
329 bool is_superclass,
330 TRAPS) {
331 #if INCLUDE_CDS
332 if (DumpSharedSpaces) {
333 // Special processing for CDS dump time.
334 Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
335 class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
336 if (k) {
337 return k;
338 }
339 }
340 #endif // INCLUDE_CDS
341
342 // Double-check, if child class is already loaded, just return super-class,interface
343 // Don't add a placedholder if already loaded, i.e. already in system dictionary
344 // Make sure there's a placeholder for the *child* before resolving.
345 // Used as a claim that this thread is currently loading superclass/classloader
346 // Used here for ClassCircularity checks and also for heap verification
347 // (every InstanceKlass in the heap needs to be in the system dictionary
348 // or have a placeholder).
349 // Must check ClassCircularity before checking if super class is already loaded
350 //
351 // We might not already have a placeholder if this child_name was
352 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
353 // the name of the class might not be known until the stream is actually
354 // parsed.
355 // Bugs 4643874, 4715493
356 // compute_hash can have a safepoint
357
358 ClassLoaderData* loader_data = class_loader_data(class_loader);
359 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
360 int d_index = dictionary()->hash_to_index(d_hash);
361 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
362 int p_index = placeholders()->hash_to_index(p_hash);
363 // can't throw error holding a lock
364 bool child_already_loaded = false;
365 bool throw_circularity_error = false;
366 {
367 MutexLocker mu(SystemDictionary_lock, THREAD);
368 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
369 Klass* quicksuperk;
370 // to support // loading: if child done loading, just return superclass
371 // if class_name, & class_loader don't match:
372 // if initial define, SD update will give LinkageError
373 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
374 // so we don't throw an exception here.
375 // see: nsk redefclass014 & java.lang.instrument Instrument032
376 if ((childk != NULL ) && (is_superclass) &&
377 ((quicksuperk = childk->super()) != NULL) &&
378
379 ((quicksuperk->name() == class_name) &&
380 (quicksuperk->class_loader() == class_loader()))) {
381 return quicksuperk;
382 } else {
383 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
384 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
385 throw_circularity_error = true;
386 }
387 }
388 if (!throw_circularity_error) {
389 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
390 }
391 }
392 if (throw_circularity_error) {
393 ResourceMark rm(THREAD);
394 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
395 }
396
397 // java.lang.Object should have been found above
398 assert(class_name != NULL, "null super class for resolving");
399 // Resolve the super class or interface, check results on return
400 Klass* superk = SystemDictionary::resolve_or_null(class_name,
401 class_loader,
402 protection_domain,
403 THREAD);
404
405 KlassHandle superk_h(THREAD, superk);
406
407 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
408 // It is no longer necessary to keep the placeholder table alive until update_dictionary
409 // or error. GC used to walk the placeholder table as strong roots.
410 // The instanceKlass is kept alive because the class loader is on the stack,
411 // which keeps the loader_data alive, as well as all instanceKlasses in
412 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
413 {
414 MutexLocker mu(SystemDictionary_lock, THREAD);
415 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
416 SystemDictionary_lock->notify_all();
417 }
418 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
419 // can null superk
420 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD));
421 }
422
423 return superk_h();
424 }
425
426 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
427 Handle class_loader,
428 Handle protection_domain,
429 TRAPS) {
430 if(!has_checkPackageAccess()) return;
431
432 // Now we have to call back to java to check if the initating class has access
433 JavaValue result(T_VOID);
434 if (TraceProtectionDomainVerification) {
435 // Print out trace information
436 tty->print_cr("Checking package access");
437 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
438 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
439 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
440 }
441
442 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
443 JavaCalls::call_special(&result,
444 class_loader,
445 system_loader,
446 vmSymbols::checkPackageAccess_name(),
447 vmSymbols::class_protectiondomain_signature(),
448 Handle(THREAD, klass->java_mirror()),
449 protection_domain,
450 THREAD);
451
452 if (TraceProtectionDomainVerification) {
453 if (HAS_PENDING_EXCEPTION) {
454 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
455 } else {
456 tty->print_cr(" -> granted");
457 }
458 tty->cr();
459 }
460
461 if (HAS_PENDING_EXCEPTION) return;
462
463 // If no exception has been thrown, we have validated the protection domain
464 // Insert the protection domain of the initiating class into the set.
465 {
466 // We recalculate the entry here -- we've called out to java since
467 // the last time it was calculated.
468 ClassLoaderData* loader_data = class_loader_data(class_loader);
469
470 Symbol* kn = klass->name();
471 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
472 int d_index = dictionary()->hash_to_index(d_hash);
473
474 MutexLocker mu(SystemDictionary_lock, THREAD);
475 {
476 // Note that we have an entry, and entries can be deleted only during GC,
477 // so we cannot allow GC to occur while we're holding this entry.
478
479 // We're using a No_Safepoint_Verifier to catch any place where we
480 // might potentially do a GC at all.
481 // Dictionary::do_unloading() asserts that classes in SD are only
482 // unloaded at a safepoint. Anonymous classes are not in SD.
483 No_Safepoint_Verifier nosafepoint;
484 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
485 protection_domain, THREAD);
486 }
487 }
488 }
489
490 // We only get here if this thread finds that another thread
491 // has already claimed the placeholder token for the current operation,
492 // but that other thread either never owned or gave up the
493 // object lock
494 // Waits on SystemDictionary_lock to indicate placeholder table updated
495 // On return, caller must recheck placeholder table state
496 //
497 // We only get here if
498 // 1) custom classLoader, i.e. not bootstrap classloader
499 // 2) UnsyncloadClass not set
500 // 3) custom classLoader has broken the class loader objectLock
501 // so another thread got here in parallel
502 //
503 // lockObject must be held.
504 // Complicated dance due to lock ordering:
505 // Must first release the classloader object lock to
506 // allow initial definer to complete the class definition
507 // and to avoid deadlock
508 // Reclaim classloader lock object with same original recursion count
509 // Must release SystemDictionary_lock after notify, since
510 // class loader lock must be claimed before SystemDictionary_lock
511 // to prevent deadlocks
512 //
513 // The notify allows applications that did an untimed wait() on
514 // the classloader object lock to not hang.
515 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
516 assert_lock_strong(SystemDictionary_lock);
517
518 bool calledholdinglock
519 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
520 assert(calledholdinglock,"must hold lock for notify");
521 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
522 ObjectSynchronizer::notifyall(lockObject, THREAD);
523 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
524 SystemDictionary_lock->wait();
525 SystemDictionary_lock->unlock();
526 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
527 SystemDictionary_lock->lock();
528 }
529
530 // If the class in is in the placeholder table, class loading is in progress
531 // For cases where the application changes threads to load classes, it
532 // is critical to ClassCircularity detection that we try loading
533 // the superclass on the same thread internally, so we do parallel
534 // super class loading here.
535 // This also is critical in cases where the original thread gets stalled
536 // even in non-circularity situations.
537 // Note: must call resolve_super_or_fail even if null super -
538 // to force placeholder entry creation for this class for circularity detection
539 // Caller must check for pending exception
540 // Returns non-null Klass* if other thread has completed load
541 // and we are done,
542 // If return null Klass* and no pending exception, the caller must load the class
543 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
544 Symbol* name, Symbol* superclassname, Handle class_loader,
545 Handle protection_domain, Handle lockObject, TRAPS) {
546
547 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
548 ClassLoaderData* loader_data = class_loader_data(class_loader);
549 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
550 int d_index = dictionary()->hash_to_index(d_hash);
551 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
552 int p_index = placeholders()->hash_to_index(p_hash);
553
554 // superk is not used, resolve_super called for circularity check only
555 // This code is reached in two situations. One if this thread
556 // is loading the same class twice (e.g. ClassCircularity, or
557 // java.lang.instrument).
558 // The second is if another thread started the resolve_super first
559 // and has not yet finished.
560 // In both cases the original caller will clean up the placeholder
561 // entry on error.
562 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
563 superclassname,
564 class_loader,
565 protection_domain,
566 true,
567 CHECK_(nh));
568
569 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
570 // Serial class loaders and bootstrap classloader do wait for superclass loads
571 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
572 MutexLocker mu(SystemDictionary_lock, THREAD);
573 // Check if classloading completed while we were loading superclass or waiting
574 Klass* check = find_class(d_index, d_hash, name, loader_data);
575 if (check != NULL) {
576 // Klass is already loaded, so just return it
577 return(instanceKlassHandle(THREAD, check));
578 } else {
579 return nh;
580 }
581 }
582
583 // must loop to both handle other placeholder updates
584 // and spurious notifications
585 bool super_load_in_progress = true;
586 PlaceholderEntry* placeholder;
587 while (super_load_in_progress) {
588 MutexLocker mu(SystemDictionary_lock, THREAD);
589 // Check if classloading completed while we were loading superclass or waiting
590 Klass* check = find_class(d_index, d_hash, name, loader_data);
591 if (check != NULL) {
592 // Klass is already loaded, so just return it
593 return(instanceKlassHandle(THREAD, check));
594 } else {
595 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
596 if (placeholder && placeholder->super_load_in_progress() ){
597 // Before UnsyncloadClass:
598 // We only get here if the application has released the
599 // classloader lock when another thread was in the middle of loading a
600 // superclass/superinterface for this class, and now
601 // this thread is also trying to load this class.
602 // To minimize surprises, the first thread that started to
603 // load a class should be the one to complete the loading
604 // with the classfile it initially expected.
605 // This logic has the current thread wait once it has done
606 // all the superclass/superinterface loading it can, until
607 // the original thread completes the class loading or fails
608 // If it completes we will use the resulting InstanceKlass
609 // which we will find below in the systemDictionary.
610 // We also get here for parallel bootstrap classloader
611 if (class_loader.is_null()) {
612 SystemDictionary_lock->wait();
613 } else {
614 double_lock_wait(lockObject, THREAD);
615 }
616 } else {
617 // If not in SD and not in PH, other thread's load must have failed
618 super_load_in_progress = false;
619 }
620 }
621 }
622 return (nh);
623 }
624
625 // utility function for class load event
626 static void post_class_load_event(const Ticks& start_time,
627 instanceKlassHandle k,
628 Handle initiating_loader) {
629 #if INCLUDE_TRACE
630 EventClassLoad event(UNTIMED);
631 if (event.should_commit()) {
632 event.set_starttime(start_time);
633 event.set_loadedClass(k());
634 oop defining_class_loader = k->class_loader();
635 event.set_definingClassLoader(defining_class_loader != NULL ?
636 defining_class_loader->klass() : (Klass*)NULL);
637 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
638 event.set_initiatingClassLoader(class_loader != NULL ?
639 class_loader->klass() : (Klass*)NULL);
640 event.commit();
641 }
642 #endif // INCLUDE_TRACE
643 }
644
645 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
646 Handle class_loader,
647 Handle protection_domain,
648 TRAPS) {
649 assert(name != NULL && !FieldType::is_array(name) &&
650 !FieldType::is_obj(name), "invalid class name");
651
652 Ticks class_load_start_time = Ticks::now();
653
654 // Fix for 4474172; see evaluation for more details
655 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
656 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
657
658 // Do lookup to see if class already exist and the protection domain
659 // has the right access
660 // This call uses find which checks protection domain already matches
661 // All subsequent calls use find_class, and set has_loaded_class so that
662 // before we return a result we call out to java to check for valid protection domain
663 // to allow returning the Klass* and add it to the pd_set if it is valid
664 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
665 int d_index = dictionary()->hash_to_index(d_hash);
666 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
667 protection_domain, THREAD);
668 if (probe != NULL) return probe;
669
670
671 // Non-bootstrap class loaders will call out to class loader and
672 // define via jvm/jni_DefineClass which will acquire the
673 // class loader object lock to protect against multiple threads
674 // defining the class in parallel by accident.
675 // This lock must be acquired here so the waiter will find
676 // any successful result in the SystemDictionary and not attempt
677 // the define
678 // ParallelCapable Classloaders and the bootstrap classloader,
679 // or all classloaders with UnsyncloadClass do not acquire lock here
680 bool DoObjectLock = true;
681 if (is_parallelCapable(class_loader)) {
682 DoObjectLock = false;
683 }
684
685 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
686 int p_index = placeholders()->hash_to_index(p_hash);
687
688 // Class is not in SystemDictionary so we have to do loading.
689 // Make sure we are synchronized on the class loader before we proceed
690 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
691 check_loader_lock_contention(lockObject, THREAD);
692 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
693
694 // Check again (after locking) if class already exist in SystemDictionary
695 bool class_has_been_loaded = false;
696 bool super_load_in_progress = false;
697 bool havesupername = false;
698 instanceKlassHandle k;
699 PlaceholderEntry* placeholder;
700 Symbol* superclassname = NULL;
701
702 {
703 MutexLocker mu(SystemDictionary_lock, THREAD);
704 Klass* check = find_class(d_index, d_hash, name, loader_data);
705 if (check != NULL) {
706 // Klass is already loaded, so just return it
707 class_has_been_loaded = true;
708 k = instanceKlassHandle(THREAD, check);
709 } else {
710 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
711 if (placeholder && placeholder->super_load_in_progress()) {
712 super_load_in_progress = true;
713 if (placeholder->havesupername() == true) {
714 superclassname = placeholder->supername();
715 havesupername = true;
716 }
717 }
718 }
719 }
720
721 // If the class is in the placeholder table, class loading is in progress
722 if (super_load_in_progress && havesupername==true) {
723 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
724 class_loader, protection_domain, lockObject, THREAD);
725 if (HAS_PENDING_EXCEPTION) {
726 return NULL;
727 }
728 if (!k.is_null()) {
729 class_has_been_loaded = true;
730 }
731 }
732
733 bool throw_circularity_error = false;
734 if (!class_has_been_loaded) {
735 bool load_instance_added = false;
736
737 // add placeholder entry to record loading instance class
738 // Five cases:
739 // All cases need to prevent modifying bootclasssearchpath
740 // in parallel with a classload of same classname
741 // Redefineclasses uses existence of the placeholder for the duration
742 // of the class load to prevent concurrent redefinition of not completely
743 // defined classes.
744 // case 1. traditional classloaders that rely on the classloader object lock
745 // - no other need for LOAD_INSTANCE
746 // case 2. traditional classloaders that break the classloader object lock
747 // as a deadlock workaround. Detection of this case requires that
748 // this check is done while holding the classloader object lock,
749 // and that lock is still held when calling classloader's loadClass.
750 // For these classloaders, we ensure that the first requestor
751 // completes the load and other requestors wait for completion.
752 // case 3. UnsyncloadClass - don't use objectLocker
753 // With this flag, we allow parallel classloading of a
754 // class/classloader pair
755 // case4. Bootstrap classloader - don't own objectLocker
756 // This classloader supports parallelism at the classloader level,
757 // but only allows a single load of a class/classloader pair.
758 // No performance benefit and no deadlock issues.
759 // case 5. parallelCapable user level classloaders - without objectLocker
760 // Allow parallel classloading of a class/classloader pair
761
762 {
763 MutexLocker mu(SystemDictionary_lock, THREAD);
764 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
765 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
766 if (oldprobe) {
767 // only need check_seen_thread once, not on each loop
768 // 6341374 java/lang/Instrument with -Xcomp
769 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
770 throw_circularity_error = true;
771 } else {
772 // case 1: traditional: should never see load_in_progress.
773 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
774
775 // case 4: bootstrap classloader: prevent futile classloading,
776 // wait on first requestor
777 if (class_loader.is_null()) {
778 SystemDictionary_lock->wait();
779 } else {
780 // case 2: traditional with broken classloader lock. wait on first
781 // requestor.
782 double_lock_wait(lockObject, THREAD);
783 }
784 // Check if classloading completed while we were waiting
785 Klass* check = find_class(d_index, d_hash, name, loader_data);
786 if (check != NULL) {
787 // Klass is already loaded, so just return it
788 k = instanceKlassHandle(THREAD, check);
789 class_has_been_loaded = true;
790 }
791 // check if other thread failed to load and cleaned up
792 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
793 }
794 }
795 }
796 }
797 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
798 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
799 // LOAD_INSTANCE in parallel
800
801 if (!throw_circularity_error && !class_has_been_loaded) {
802 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
803 load_instance_added = true;
804 // For class loaders that do not acquire the classloader object lock,
805 // if they did not catch another thread holding LOAD_INSTANCE,
806 // need a check analogous to the acquire ObjectLocker/find_class
807 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
808 // one final check if the load has already completed
809 // class loaders holding the ObjectLock shouldn't find the class here
810 Klass* check = find_class(d_index, d_hash, name, loader_data);
811 if (check != NULL) {
812 // Klass is already loaded, so return it after checking/adding protection domain
813 k = instanceKlassHandle(THREAD, check);
814 class_has_been_loaded = true;
815 }
816 }
817 }
818
819 // must throw error outside of owning lock
820 if (throw_circularity_error) {
821 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
822 ResourceMark rm(THREAD);
823 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
824 }
825
826 if (!class_has_been_loaded) {
827
828 // Do actual loading
829 k = load_instance_class(name, class_loader, THREAD);
830
831 // For UnsyncloadClass only
832 // If they got a linkageError, check if a parallel class load succeeded.
833 // If it did, then for bytecode resolution the specification requires
834 // that we return the same result we did for the other thread, i.e. the
835 // successfully loaded InstanceKlass
836 // Should not get here for classloaders that support parallelism
837 // with the new cleaner mechanism, even with AllowParallelDefineClass
838 // Bootstrap goes through here to allow for an extra guarantee check
839 if (UnsyncloadClass || (class_loader.is_null())) {
840 if (k.is_null() && HAS_PENDING_EXCEPTION
841 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
842 MutexLocker mu(SystemDictionary_lock, THREAD);
843 Klass* check = find_class(d_index, d_hash, name, loader_data);
844 if (check != NULL) {
845 // Klass is already loaded, so just use it
846 k = instanceKlassHandle(THREAD, check);
847 CLEAR_PENDING_EXCEPTION;
848 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
849 }
850 }
851 }
852
853 // If everything was OK (no exceptions, no null return value), and
854 // class_loader is NOT the defining loader, do a little more bookkeeping.
855 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
856 k->class_loader() != class_loader()) {
857
858 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
859
860 // Need to check for a PENDING_EXCEPTION again; check_constraints
861 // can throw and doesn't use the CHECK macro.
862 if (!HAS_PENDING_EXCEPTION) {
863 { // Grabbing the Compile_lock prevents systemDictionary updates
864 // during compilations.
865 MutexLocker mu(Compile_lock, THREAD);
866 update_dictionary(d_index, d_hash, p_index, p_hash,
867 k, class_loader, THREAD);
868 }
869
870 if (JvmtiExport::should_post_class_load()) {
871 Thread *thread = THREAD;
872 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
873 JvmtiExport::post_class_load((JavaThread *) thread, k());
874 }
875 }
876 }
877 } // load_instance_class loop
878
879 if (load_instance_added == true) {
880 // clean up placeholder entries for LOAD_INSTANCE success or error
881 // This brackets the SystemDictionary updates for both defining
882 // and initiating loaders
883 MutexLocker mu(SystemDictionary_lock, THREAD);
884 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
885 SystemDictionary_lock->notify_all();
886 }
887 }
888
889 if (HAS_PENDING_EXCEPTION || k.is_null()) {
890 return NULL;
891 }
892
893 post_class_load_event(class_load_start_time, k, class_loader);
894
895 #ifdef ASSERT
896 {
897 ClassLoaderData* loader_data = k->class_loader_data();
898 MutexLocker mu(SystemDictionary_lock, THREAD);
899 Klass* kk = find_class(name, loader_data);
900 assert(kk == k(), "should be present in dictionary");
901 }
902 #endif
903
904 // return if the protection domain in NULL
905 if (protection_domain() == NULL) return k();
906
907 // Check the protection domain has the right access
908 {
909 MutexLocker mu(SystemDictionary_lock, THREAD);
910 // Note that we have an entry, and entries can be deleted only during GC,
911 // so we cannot allow GC to occur while we're holding this entry.
912 // We're using a No_Safepoint_Verifier to catch any place where we
913 // might potentially do a GC at all.
914 // Dictionary::do_unloading() asserts that classes in SD are only
915 // unloaded at a safepoint. Anonymous classes are not in SD.
916 No_Safepoint_Verifier nosafepoint;
917 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
918 loader_data,
919 protection_domain)) {
920 return k();
921 }
922 }
923
924 // Verify protection domain. If it fails an exception is thrown
925 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
926
927 return k();
928 }
929
930
931 // This routine does not lock the system dictionary.
932 //
933 // Since readers don't hold a lock, we must make sure that system
934 // dictionary entries are only removed at a safepoint (when only one
935 // thread is running), and are added to in a safe way (all links must
936 // be updated in an MT-safe manner).
937 //
938 // Callers should be aware that an entry could be added just after
939 // _dictionary->bucket(index) is read here, so the caller will not see
940 // the new entry.
941
942 Klass* SystemDictionary::find(Symbol* class_name,
943 Handle class_loader,
944 Handle protection_domain,
945 TRAPS) {
946
947 // The result of this call should be consistent with the result
948 // of the call to resolve_instance_class_or_null().
949 // See evaluation 6790209 and 4474172 for more details.
950 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
951 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
952
953 if (loader_data == NULL) {
954 // If the ClassLoaderData has not been setup,
955 // then the class loader has no entries in the dictionary.
956 return NULL;
957 }
958
959 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
960 int d_index = dictionary()->hash_to_index(d_hash);
961
962 {
963 // Note that we have an entry, and entries can be deleted only during GC,
964 // so we cannot allow GC to occur while we're holding this entry.
965 // We're using a No_Safepoint_Verifier to catch any place where we
966 // might potentially do a GC at all.
967 // Dictionary::do_unloading() asserts that classes in SD are only
968 // unloaded at a safepoint. Anonymous classes are not in SD.
969 No_Safepoint_Verifier nosafepoint;
970 return dictionary()->find(d_index, d_hash, class_name, loader_data,
971 protection_domain, THREAD);
972 }
973 }
974
975
976 // Look for a loaded instance or array klass by name. Do not do any loading.
977 // return NULL in case of error.
978 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
979 Handle class_loader,
980 Handle protection_domain,
981 TRAPS) {
982 Klass* k = NULL;
983 assert(class_name != NULL, "class name must be non NULL");
984
985 if (FieldType::is_array(class_name)) {
986 // The name refers to an array. Parse the name.
987 // dimension and object_key in FieldArrayInfo are assigned as a
988 // side-effect of this call
989 FieldArrayInfo fd;
990 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
991 if (t != T_OBJECT) {
992 k = Universe::typeArrayKlassObj(t);
993 } else {
994 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
995 }
996 if (k != NULL) {
997 k = k->array_klass_or_null(fd.dimension());
998 }
999 } else {
1000 k = find(class_name, class_loader, protection_domain, THREAD);
1001 }
1002 return k;
1003 }
1004
1005 // Note: this method is much like resolve_from_stream, but
1006 // updates no supplemental data structures.
1007 // TODO consolidate the two methods with a helper routine?
1008 Klass* SystemDictionary::parse_stream(Symbol* class_name,
1009 Handle class_loader,
1010 Handle protection_domain,
1011 ClassFileStream* st,
1012 const Klass* host_klass,
1013 GrowableArray<Handle>* cp_patches,
1014 TRAPS) {
1015
1016 Ticks class_load_start_time = Ticks::now();
1017
1018 ClassLoaderData* loader_data;
1019 if (host_klass != NULL) {
1020 // Create a new CLD for anonymous class, that uses the same class loader
1021 // as the host_klass
1022 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1023 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
1024 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1025 loader_data->record_dependency(host_klass, CHECK_NULL);
1026 } else {
1027 loader_data = ClassLoaderData::class_loader_data(class_loader());
1028 }
1029
1030 assert(st != NULL, "invariant");
1031 assert(st->need_verify(), "invariant");
1032
1033 // Parse stream and create a klass.
1034 // Note that we do this even though this klass might
1035 // already be present in the SystemDictionary, otherwise we would not
1036 // throw potential ClassFormatErrors.
1037
1038 instanceKlassHandle k = KlassFactory::create_from_stream(st,
1039 class_name,
1040 loader_data,
1041 protection_domain,
1042 host_klass,
1043 cp_patches,
1044 NULL, // parsed_name
1045 THREAD);
1046
1047 if (host_klass != NULL && k.not_null()) {
1048 // If it's anonymous, initialize it now, since nobody else will.
1049
1050 {
1051 MutexLocker mu_r(Compile_lock, THREAD);
1052
1053 // Add to class hierarchy, initialize vtables, and do possible
1054 // deoptimizations.
1055 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1056
1057 // But, do not add to system dictionary.
1058
1059 // compiled code dependencies need to be validated anyway
1060 notice_modification();
1061 }
1062
1063 // Rewrite and patch constant pool here.
1064 k->link_class(CHECK_NULL);
1065 if (cp_patches != NULL) {
1066 k->constants()->patch_resolved_references(cp_patches);
1067 }
1068 k->eager_initialize(CHECK_NULL);
1069
1070 // notify jvmti
1071 if (JvmtiExport::should_post_class_load()) {
1072 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1073 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1074 }
1075
1076 post_class_load_event(class_load_start_time, k, class_loader);
1077 }
1078 assert(host_klass != NULL || NULL == cp_patches,
1079 "cp_patches only found with host_klass");
1080
1081 return k();
1082 }
1083
1084 // Add a klass to the system from a stream (called by jni_DefineClass and
1085 // JVM_DefineClass).
1086 // Note: class_name can be NULL. In that case we do not know the name of
1087 // the class until we have parsed the stream.
1088
1089 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1090 Handle class_loader,
1091 Handle protection_domain,
1092 ClassFileStream* st,
1093 TRAPS) {
1094
1095 // Classloaders that support parallelism, e.g. bootstrap classloader,
1096 // or all classloaders with UnsyncloadClass do not acquire lock here
1097 bool DoObjectLock = true;
1098 if (is_parallelCapable(class_loader)) {
1099 DoObjectLock = false;
1100 }
1101
1102 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1103
1104 // Make sure we are synchronized on the class loader before we proceed
1105 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1106 check_loader_lock_contention(lockObject, THREAD);
1107 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1108
1109 assert(st != NULL, "invariant");
1110
1111 // Parse the stream and create a klass.
1112 // Note that we do this even though this klass might
1113 // already be present in the SystemDictionary, otherwise we would not
1114 // throw potential ClassFormatErrors.
1115 //
1116 // Note: "parsed_name" is updated.
1117 TempNewSymbol parsed_name = NULL;
1118
1119 instanceKlassHandle k;
1120
1121 #if INCLUDE_CDS
1122 k = SystemDictionaryShared::lookup_from_stream(class_name,
1123 class_loader,
1124 protection_domain,
1125 st,
1126 CHECK_NULL);
1127 #endif
1128
1129 if (k.not_null()) {
1130 parsed_name = k->name();
1131 } else {
1132 if (st->buffer() == NULL) {
1133 return NULL;
1134 }
1135 k = KlassFactory::create_from_stream(st,
1136 class_name,
1137 loader_data,
1138 protection_domain,
1139 NULL, // host_klass
1140 NULL, // cp_patches
1141 &parsed_name,
1142 THREAD);
1143 }
1144
1145 const char* pkg = "java/";
1146 if (!HAS_PENDING_EXCEPTION &&
1147 !class_loader.is_null() &&
1148 parsed_name != NULL &&
1149 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1150 // It is illegal to define classes in the "java." package from
1151 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1152 ResourceMark rm(THREAD);
1153 char* name = parsed_name->as_C_string();
1154 char* index = strrchr(name, '/');
1155 *index = '\0'; // chop to just the package name
1156 while ((index = strchr(name, '/')) != NULL) {
1157 *index = '.'; // replace '/' with '.' in package name
1158 }
1159 const char* fmt = "Prohibited package name: %s";
1160 size_t len = strlen(fmt) + strlen(name);
1161 char* message = NEW_RESOURCE_ARRAY(char, len);
1162 jio_snprintf(message, len, fmt, name);
1163 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1164 vmSymbols::java_lang_SecurityException(), message);
1165 }
1166
1167 if (!HAS_PENDING_EXCEPTION) {
1168 assert(parsed_name != NULL, "Sanity");
1169 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1170 // Verification prevents us from creating names with dots in them, this
1171 // asserts that that's the case.
1172 assert(is_internal_format(parsed_name),
1173 "external class name format used internally");
1174
1175 // Add class just loaded
1176 // If a class loader supports parallel classloading handle parallel define requests
1177 // find_or_define_instance_class may return a different InstanceKlass
1178 if (is_parallelCapable(class_loader)) {
1179 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1180 } else {
1181 define_instance_class(k, THREAD);
1182 }
1183 }
1184
1185 // Make sure we have an entry in the SystemDictionary on success
1186 debug_only( {
1187 if (!HAS_PENDING_EXCEPTION) {
1188 assert(parsed_name != NULL, "parsed_name is still null?");
1189 Symbol* h_name = k->name();
1190 ClassLoaderData *defining_loader_data = k->class_loader_data();
1191
1192 MutexLocker mu(SystemDictionary_lock, THREAD);
1193
1194 Klass* check = find_class(parsed_name, loader_data);
1195 assert(check == k(), "should be present in the dictionary");
1196
1197 Klass* check2 = find_class(h_name, defining_loader_data);
1198 assert(check == check2, "name inconsistancy in SystemDictionary");
1199 }
1200 } );
1201
1202 return k();
1203 }
1204
1205 #if INCLUDE_CDS
1206 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1207 int number_of_entries) {
1208 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1209 "bad shared dictionary size.");
1210 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1211 }
1212
1213
1214 // If there is a shared dictionary, then find the entry for the
1215 // given shared system class, if any.
1216
1217 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1218 if (shared_dictionary() != NULL) {
1219 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1220 int d_index = shared_dictionary()->hash_to_index(d_hash);
1221
1222 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1223 } else {
1224 return NULL;
1225 }
1226 }
1227
1228
1229 // Load a class from the shared spaces (found through the shared system
1230 // dictionary). Force the superclass and all interfaces to be loaded.
1231 // Update the class definition to include sibling classes and no
1232 // subclasses (yet). [Classes in the shared space are not part of the
1233 // object hierarchy until loaded.]
1234
1235 instanceKlassHandle SystemDictionary::load_shared_class(
1236 Symbol* class_name, Handle class_loader, TRAPS) {
1237 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1238 // Make sure we only return the boot class for the NULL classloader.
1239 if (ik.not_null() &&
1240 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1241 Handle protection_domain;
1242 return load_shared_class(ik, class_loader, protection_domain, THREAD);
1243 }
1244 return instanceKlassHandle();
1245 }
1246
1247 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1248 Handle class_loader,
1249 Handle protection_domain, TRAPS) {
1250 if (ik.not_null()) {
1251 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1252 Symbol* class_name = ik->name();
1253
1254 // Found the class, now load the superclass and interfaces. If they
1255 // are shared, add them to the main system dictionary and reset
1256 // their hierarchy references (supers, subs, and interfaces).
1257
1258 if (ik->super() != NULL) {
1259 Symbol* cn = ik->super()->name();
1260 Klass *s = resolve_super_or_fail(class_name, cn,
1261 class_loader, protection_domain, true, CHECK_(nh));
1262 if (s != ik->super()) {
1263 // The dynamically resolved super class is not the same as the one we used during dump time,
1264 // so we cannot use ik.
1265 return nh;
1266 }
1267 }
1268
1269 Array<Klass*>* interfaces = ik->local_interfaces();
1270 int num_interfaces = interfaces->length();
1271 for (int index = 0; index < num_interfaces; index++) {
1272 Klass* k = interfaces->at(index);
1273
1274 // Note: can not use InstanceKlass::cast here because
1275 // interfaces' InstanceKlass's C++ vtbls haven't been
1276 // reinitialized yet (they will be once the interface classes
1277 // are loaded)
1278 Symbol* name = k->name();
1279 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1280 if (k != i) {
1281 // The dynamically resolved interface class is not the same as the one we used during dump time,
1282 // so we cannot use ik.
1283 return nh;
1284 }
1285 }
1286
1287 // Adjust methods to recover missing data. They need addresses for
1288 // interpreter entry points and their default native method address
1289 // must be reset.
1290
1291 // Updating methods must be done under a lock so multiple
1292 // threads don't update these in parallel
1293 //
1294 // Shared classes are all currently loaded by either the bootstrap or
1295 // internal parallel class loaders, so this will never cause a deadlock
1296 // on a custom class loader lock.
1297
1298 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1299 {
1300 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1301 check_loader_lock_contention(lockObject, THREAD);
1302 ObjectLocker ol(lockObject, THREAD, true);
1303 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1304 }
1305
1306 if (log_is_enabled(Info, classload)) {
1307 ik()->print_loading_log(LogLevel::Info, loader_data, NULL);
1308 }
1309 if (log_is_enabled(Debug, classload)) {
1310 ik()->print_loading_log(LogLevel::Debug, loader_data, NULL);
1311 }
1312
1313 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1314 // Only dump the classes that can be stored into CDS archive
1315 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1316 ResourceMark rm(THREAD);
1317 classlist_file->print_cr("%s", ik->name()->as_C_string());
1318 classlist_file->flush();
1319 }
1320 }
1321
1322 // notify a class loaded from shared object
1323 ClassLoadingService::notify_class_loaded(ik(), true /* shared class */);
1324 }
1325 return ik;
1326 }
1327 #endif // INCLUDE_CDS
1328
1329 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1330 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1331 if (class_loader.is_null()) {
1332
1333 // Search the shared system dictionary for classes preloaded into the
1334 // shared spaces.
1335 instanceKlassHandle k;
1336 {
1337 #if INCLUDE_CDS
1338 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1339 k = load_shared_class(class_name, class_loader, THREAD);
1340 #endif
1341 }
1342
1343 if (k.is_null()) {
1344 // Use VM class loader
1345 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1346 k = ClassLoader::load_class(class_name, CHECK_(nh));
1347 }
1348
1349 // find_or_define_instance_class may return a different InstanceKlass
1350 if (!k.is_null()) {
1351 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1352 }
1353 return k;
1354 } else {
1355 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1356 ResourceMark rm(THREAD);
1357
1358 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1359 JavaThread* jt = (JavaThread*) THREAD;
1360
1361 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1362 ClassLoader::perf_app_classload_selftime(),
1363 ClassLoader::perf_app_classload_count(),
1364 jt->get_thread_stat()->perf_recursion_counts_addr(),
1365 jt->get_thread_stat()->perf_timers_addr(),
1366 PerfClassTraceTime::CLASS_LOAD);
1367
1368 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1369 // Translate to external class name format, i.e., convert '/' chars to '.'
1370 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1371
1372 JavaValue result(T_OBJECT);
1373
1374 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1375
1376 // Call public unsynchronized loadClass(String) directly for all class loaders
1377 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1378 // acquire a class-name based lock rather than the class loader object lock.
1379 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1380 // so the call to loadClassInternal() was not required.
1381 //
1382 // UnsyncloadClass flag means both call loadClass(String) and do
1383 // not acquire the class loader lock even for class loaders that are
1384 // not parallelCapable. This was a risky transitional
1385 // flag for diagnostic purposes only. It is risky to call
1386 // custom class loaders without synchronization.
1387 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1388 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1389 // Do NOT assume this will be supported in future releases.
1390 //
1391 // Added MustCallLoadClassInternal in case we discover in the field
1392 // a customer that counts on this call
1393 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1394 JavaCalls::call_special(&result,
1395 class_loader,
1396 spec_klass,
1397 vmSymbols::loadClassInternal_name(),
1398 vmSymbols::string_class_signature(),
1399 string,
1400 CHECK_(nh));
1401 } else {
1402 JavaCalls::call_virtual(&result,
1403 class_loader,
1404 spec_klass,
1405 vmSymbols::loadClass_name(),
1406 vmSymbols::string_class_signature(),
1407 string,
1408 CHECK_(nh));
1409 }
1410
1411 assert(result.get_type() == T_OBJECT, "just checking");
1412 oop obj = (oop) result.get_jobject();
1413
1414 // Primitive classes return null since forName() can not be
1415 // used to obtain any of the Class objects representing primitives or void
1416 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1417 instanceKlassHandle k =
1418 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1419 // For user defined Java class loaders, check that the name returned is
1420 // the same as that requested. This check is done for the bootstrap
1421 // loader when parsing the class file.
1422 if (class_name == k->name()) {
1423 return k;
1424 }
1425 }
1426 // Class is not found or has the wrong name, return NULL
1427 return nh;
1428 }
1429 }
1430
1431 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1432
1433 ClassLoaderData* loader_data = k->class_loader_data();
1434 Handle class_loader_h(THREAD, loader_data->class_loader());
1435
1436 // for bootstrap and other parallel classloaders don't acquire lock,
1437 // use placeholder token
1438 // If a parallelCapable class loader calls define_instance_class instead of
1439 // find_or_define_instance_class to get here, we have a timing
1440 // hole with systemDictionary updates and check_constraints
1441 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1442 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1443 compute_loader_lock_object(class_loader_h, THREAD)),
1444 "define called without lock");
1445 }
1446
1447 // Check class-loading constraints. Throw exception if violation is detected.
1448 // Grabs and releases SystemDictionary_lock
1449 // The check_constraints/find_class call and update_dictionary sequence
1450 // must be "atomic" for a specific class/classloader pair so we never
1451 // define two different instanceKlasses for that class/classloader pair.
1452 // Existing classloaders will call define_instance_class with the
1453 // classloader lock held
1454 // Parallel classloaders will call find_or_define_instance_class
1455 // which will require a token to perform the define class
1456 Symbol* name_h = k->name();
1457 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1458 int d_index = dictionary()->hash_to_index(d_hash);
1459 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1460
1461 // Register class just loaded with class loader (placed in Vector)
1462 // Note we do this before updating the dictionary, as this can
1463 // fail with an OutOfMemoryError (if it does, we will *not* put this
1464 // class in the dictionary and will not update the class hierarchy).
1465 // JVMTI FollowReferences needs to find the classes this way.
1466 if (k->class_loader() != NULL) {
1467 methodHandle m(THREAD, Universe::loader_addClass_method());
1468 JavaValue result(T_VOID);
1469 JavaCallArguments args(class_loader_h);
1470 args.push_oop(Handle(THREAD, k->java_mirror()));
1471 JavaCalls::call(&result, m, &args, CHECK);
1472 }
1473
1474 // Add the new class. We need recompile lock during update of CHA.
1475 {
1476 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1477 int p_index = placeholders()->hash_to_index(p_hash);
1478
1479 MutexLocker mu_r(Compile_lock, THREAD);
1480
1481 // Add to class hierarchy, initialize vtables, and do possible
1482 // deoptimizations.
1483 add_to_hierarchy(k, CHECK); // No exception, but can block
1484
1485 // Add to systemDictionary - so other classes can see it.
1486 // Grabs and releases SystemDictionary_lock
1487 update_dictionary(d_index, d_hash, p_index, p_hash,
1488 k, class_loader_h, THREAD);
1489 }
1490 k->eager_initialize(THREAD);
1491
1492 // notify jvmti
1493 if (JvmtiExport::should_post_class_load()) {
1494 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1495 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1496
1497 }
1498
1499 }
1500
1501 // Support parallel classloading
1502 // All parallel class loaders, including bootstrap classloader
1503 // lock a placeholder entry for this class/class_loader pair
1504 // to allow parallel defines of different classes for this class loader
1505 // With AllowParallelDefine flag==true, in case they do not synchronize around
1506 // FindLoadedClass/DefineClass, calls, we check for parallel
1507 // loading for them, wait if a defineClass is in progress
1508 // and return the initial requestor's results
1509 // This flag does not apply to the bootstrap classloader.
1510 // With AllowParallelDefine flag==false, call through to define_instance_class
1511 // which will throw LinkageError: duplicate class definition.
1512 // False is the requested default.
1513 // For better performance, the class loaders should synchronize
1514 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1515 // potentially waste time reading and parsing the bytestream.
1516 // Note: VM callers should ensure consistency of k/class_name,class_loader
1517 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1518
1519 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1520 Symbol* name_h = k->name(); // passed in class_name may be null
1521 ClassLoaderData* loader_data = class_loader_data(class_loader);
1522
1523 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1524 int d_index = dictionary()->hash_to_index(d_hash);
1525
1526 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1527 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1528 int p_index = placeholders()->hash_to_index(p_hash);
1529 PlaceholderEntry* probe;
1530
1531 {
1532 MutexLocker mu(SystemDictionary_lock, THREAD);
1533 // First check if class already defined
1534 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1535 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1536 if (check != NULL) {
1537 return(instanceKlassHandle(THREAD, check));
1538 }
1539 }
1540
1541 // Acquire define token for this class/classloader
1542 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1543 // Wait if another thread defining in parallel
1544 // All threads wait - even those that will throw duplicate class: otherwise
1545 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1546 // if other thread has not finished updating dictionary
1547 while (probe->definer() != NULL) {
1548 SystemDictionary_lock->wait();
1549 }
1550 // Only special cases allow parallel defines and can use other thread's results
1551 // Other cases fall through, and may run into duplicate defines
1552 // caught by finding an entry in the SystemDictionary
1553 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1554 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1555 SystemDictionary_lock->notify_all();
1556 #ifdef ASSERT
1557 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1558 assert(check != NULL, "definer missed recording success");
1559 #endif
1560 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1561 } else {
1562 // This thread will define the class (even if earlier thread tried and had an error)
1563 probe->set_definer(THREAD);
1564 }
1565 }
1566
1567 define_instance_class(k, THREAD);
1568
1569 Handle linkage_exception = Handle(); // null handle
1570
1571 // definer must notify any waiting threads
1572 {
1573 MutexLocker mu(SystemDictionary_lock, THREAD);
1574 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1575 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1576 if (probe != NULL) {
1577 if (HAS_PENDING_EXCEPTION) {
1578 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1579 CLEAR_PENDING_EXCEPTION;
1580 } else {
1581 probe->set_instance_klass(k());
1582 }
1583 probe->set_definer(NULL);
1584 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1585 SystemDictionary_lock->notify_all();
1586 }
1587 }
1588
1589 // Can't throw exception while holding lock due to rank ordering
1590 if (linkage_exception() != NULL) {
1591 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1592 }
1593
1594 return k;
1595 }
1596 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1597 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1598 if (class_loader.is_null()) {
1599 return Handle(THREAD, _system_loader_lock_obj);
1600 } else {
1601 return class_loader;
1602 }
1603 }
1604
1605 // This method is added to check how often we have to wait to grab loader
1606 // lock. The results are being recorded in the performance counters defined in
1607 // ClassLoader::_sync_systemLoaderLockContentionRate and
1608 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1609 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1610 if (!UsePerfData) {
1611 return;
1612 }
1613
1614 assert(!loader_lock.is_null(), "NULL lock object");
1615
1616 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1617 == ObjectSynchronizer::owner_other) {
1618 // contention will likely happen, so increment the corresponding
1619 // contention counter.
1620 if (loader_lock() == _system_loader_lock_obj) {
1621 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1622 } else {
1623 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1624 }
1625 }
1626 }
1627
1628 // ----------------------------------------------------------------------------
1629 // Lookup
1630
1631 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1632 Symbol* class_name,
1633 ClassLoaderData* loader_data) {
1634 assert_locked_or_safepoint(SystemDictionary_lock);
1635 assert (index == dictionary()->index_for(class_name, loader_data),
1636 "incorrect index?");
1637
1638 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1639 return k;
1640 }
1641
1642
1643 // Basic find on classes in the midst of being loaded
1644 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1645 ClassLoaderData* loader_data) {
1646 assert_locked_or_safepoint(SystemDictionary_lock);
1647 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1648 int p_index = placeholders()->hash_to_index(p_hash);
1649 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1650 }
1651
1652
1653 // Used for assertions and verification only
1654 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1655 #ifndef ASSERT
1656 guarantee(VerifyBeforeGC ||
1657 VerifyDuringGC ||
1658 VerifyBeforeExit ||
1659 VerifyDuringStartup ||
1660 VerifyAfterGC, "too expensive");
1661 #endif
1662 assert_locked_or_safepoint(SystemDictionary_lock);
1663
1664 // First look in the loaded class array
1665 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1666 int d_index = dictionary()->hash_to_index(d_hash);
1667 return find_class(d_index, d_hash, class_name, loader_data);
1668 }
1669
1670
1671 // Get the next class in the diictionary.
1672 Klass* SystemDictionary::try_get_next_class() {
1673 return dictionary()->try_get_next_class();
1674 }
1675
1676
1677 // ----------------------------------------------------------------------------
1678 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1679 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1680 // before a new class is used.
1681
1682 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1683 assert(k.not_null(), "just checking");
1684 assert_locked_or_safepoint(Compile_lock);
1685
1686 // Link into hierachy. Make sure the vtables are initialized before linking into
1687 k->append_to_sibling_list(); // add to superklass/sibling list
1688 k->process_interfaces(THREAD); // handle all "implements" declarations
1689 k->set_init_state(InstanceKlass::loaded);
1690 // Now flush all code that depended on old class hierarchy.
1691 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1692 // Also, first reinitialize vtable because it may have gotten out of synch
1693 // while the new class wasn't connected to the class hierarchy.
1694 CodeCache::flush_dependents_on(k);
1695 }
1696
1697 // ----------------------------------------------------------------------------
1698 // GC support
1699
1700 // Following roots during mark-sweep is separated in two phases.
1701 //
1702 // The first phase follows preloaded classes and all other system
1703 // classes, since these will never get unloaded anyway.
1704 //
1705 // The second phase removes (unloads) unreachable classes from the
1706 // system dictionary and follows the remaining classes' contents.
1707
1708 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1709 roots_oops_do(blk, NULL);
1710 }
1711
1712 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1713 // Follow all system classes and temporary placeholders in dictionary
1714 dictionary()->always_strong_classes_do(closure);
1715
1716 // Placeholders. These represent classes we're actively loading.
1717 placeholders()->classes_do(closure);
1718 }
1719
1720 // Calculate a "good" systemdictionary size based
1721 // on predicted or current loaded classes count
1722 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1723 int newsize = _old_default_sdsize;
1724 if ((classcount > 0) && !DumpSharedSpaces) {
1725 int desiredsize = classcount/_average_depth_goal;
1726 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1727 newsize = _primelist[++_sdgeneration]) {
1728 if (desiredsize <= newsize) {
1729 break;
1730 }
1731 }
1732 }
1733 return newsize;
1734 }
1735
1736 #ifdef ASSERT
1737 class VerifySDReachableAndLiveClosure : public OopClosure {
1738 private:
1739 BoolObjectClosure* _is_alive;
1740
1741 template <class T> void do_oop_work(T* p) {
1742 oop obj = oopDesc::load_decode_heap_oop(p);
1743 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1744 }
1745
1746 public:
1747 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1748
1749 virtual void do_oop(oop* p) { do_oop_work(p); }
1750 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1751 };
1752 #endif
1753
1754 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1755 // Note: anonymous classes are not in the SD.
1756 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1757 bool clean_previous_versions) {
1758 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1759 bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1760 clean_previous_versions);
1761 if (unloading_occurred) {
1762 dictionary()->do_unloading();
1763 constraints()->purge_loader_constraints();
1764 resolution_errors()->purge_resolution_errors();
1765 }
1766 // Oops referenced by the system dictionary may get unreachable independently
1767 // of the class loader (eg. cached protection domain oops). So we need to
1768 // explicitly unlink them here instead of in Dictionary::do_unloading.
1769 dictionary()->unlink(is_alive);
1770 #ifdef ASSERT
1771 VerifySDReachableAndLiveClosure cl(is_alive);
1772 dictionary()->oops_do(&cl);
1773 #endif
1774 return unloading_occurred;
1775 }
1776
1777 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1778 strong->do_oop(&_java_system_loader);
1779 strong->do_oop(&_system_loader_lock_obj);
1780 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1781
1782 // Adjust dictionary
1783 dictionary()->roots_oops_do(strong, weak);
1784
1785 // Visit extra methods
1786 invoke_method_table()->oops_do(strong);
1787 }
1788
1789 void SystemDictionary::oops_do(OopClosure* f) {
1790 f->do_oop(&_java_system_loader);
1791 f->do_oop(&_system_loader_lock_obj);
1792 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1793
1794 // Adjust dictionary
1795 dictionary()->oops_do(f);
1796
1797 // Visit extra methods
1798 invoke_method_table()->oops_do(f);
1799 }
1800
1801 // Extended Class redefinition support.
1802 // If one of these classes is replaced, we need to replace it in these places.
1803 // KlassClosure::do_klass should take the address of a class but we can
1804 // change that later.
1805 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1806 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1807 f->do_klass(_well_known_klasses[k]);
1808 }
1809
1810 {
1811 for (int i = 0; i < T_VOID+1; i++) {
1812 if (_box_klasses[i] != NULL) {
1813 assert(i >= T_BOOLEAN, "checking");
1814 f->do_klass(_box_klasses[i]);
1815 }
1816 }
1817 }
1818
1819 FilteredFieldsMap::classes_do(f);
1820 }
1821
1822 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1823 f->do_klass(_abstract_ownable_synchronizer_klass);
1824 }
1825
1826 // Just the classes from defining class loaders
1827 // Don't iterate over placeholders
1828 void SystemDictionary::classes_do(void f(Klass*)) {
1829 dictionary()->classes_do(f);
1830 }
1831
1832 // Added for initialize_itable_for_klass
1833 // Just the classes from defining class loaders
1834 // Don't iterate over placeholders
1835 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1836 dictionary()->classes_do(f, CHECK);
1837 }
1838
1839 // All classes, and their class loaders
1840 // Don't iterate over placeholders
1841 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1842 dictionary()->classes_do(f);
1843 }
1844
1845 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1846 placeholders()->entries_do(f);
1847 }
1848
1849 void SystemDictionary::methods_do(void f(Method*)) {
1850 dictionary()->methods_do(f);
1851 invoke_method_table()->methods_do(f);
1852 }
1853
1854 void SystemDictionary::remove_classes_in_error_state() {
1855 dictionary()->remove_classes_in_error_state();
1856 }
1857
1858 // ----------------------------------------------------------------------------
1859 // Lazily load klasses
1860
1861 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1862 // if multiple threads calling this function, only one thread will load
1863 // the class. The other threads will find the loaded version once the
1864 // class is loaded.
1865 Klass* aos = _abstract_ownable_synchronizer_klass;
1866 if (aos == NULL) {
1867 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1868 // Force a fence to prevent any read before the write completes
1869 OrderAccess::fence();
1870 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1871 }
1872 }
1873
1874 // ----------------------------------------------------------------------------
1875 // Initialization
1876
1877 void SystemDictionary::initialize(TRAPS) {
1878 // Allocate arrays
1879 assert(dictionary() == NULL,
1880 "SystemDictionary should only be initialized once");
1881 _sdgeneration = 0;
1882 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1883 _placeholders = new PlaceholderTable(_nof_buckets);
1884 _number_of_modifications = 0;
1885 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1886 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1887 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1888
1889 // Allocate private object used as system class loader lock
1890 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1891 // Initialize basic classes
1892 initialize_preloaded_classes(CHECK);
1893 }
1894
1895 // Compact table of directions on the initialization of klasses:
1896 static const short wk_init_info[] = {
1897 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1898 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1899 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1900 | (int)SystemDictionary::option ),
1901 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1902 #undef WK_KLASS_INIT_INFO
1903 0
1904 };
1905
1906 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1907 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1908 int info = wk_init_info[id - FIRST_WKID];
1909 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1910 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1911 InstanceKlass** klassp = &_well_known_klasses[id];
1912 bool must_load = (init_opt < SystemDictionary::Opt);
1913 if ((*klassp) == NULL) {
1914 Klass* k;
1915 if (must_load) {
1916 k = resolve_or_fail(symbol, true, CHECK_0); // load required class
1917 } else {
1918 k = resolve_or_null(symbol, CHECK_0); // load optional klass
1919 }
1920 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
1921 }
1922 return ((*klassp) != NULL);
1923 }
1924
1925 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1926 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1927 for (int id = (int)start_id; id < (int)limit_id; id++) {
1928 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1929 int info = wk_init_info[id - FIRST_WKID];
1930 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1931 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1932
1933 initialize_wk_klass((WKID)id, opt, CHECK);
1934 }
1935
1936 // move the starting value forward to the limit:
1937 start_id = limit_id;
1938 }
1939
1940 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1941 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1942 // Preload commonly used klasses
1943 WKID scan = FIRST_WKID;
1944 // first do Object, then String, Class
1945 if (UseSharedSpaces) {
1946 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1947 // Initialize the constant pool for the Object_class
1948 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1949 ik->constants()->restore_unshareable_info(CHECK);
1950 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1951 } else {
1952 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1953 }
1954
1955 // Calculate offsets for String and Class classes since they are loaded and
1956 // can be used after this point.
1957 java_lang_String::compute_offsets();
1958 java_lang_Class::compute_offsets();
1959
1960 // Fixup mirrors for classes loaded before java.lang.Class.
1961 // These calls iterate over the objects currently in the perm gen
1962 // so calling them at this point is matters (not before when there
1963 // are fewer objects and not later after there are more objects
1964 // in the perm gen.
1965 Universe::initialize_basic_type_mirrors(CHECK);
1966 Universe::fixup_mirrors(CHECK);
1967
1968 // do a bunch more:
1969 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1970
1971 // Preload ref klasses and set reference types
1972 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1973 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1974
1975 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1976 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1977 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1978 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1979 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1980 InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
1981
1982 // JSR 292 classes
1983 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1984 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1985 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1986 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1987 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
1988
1989 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1990 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1991 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1992 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1993 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1994 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1995 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1996 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1997 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1998 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1999
2000 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2001 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2002 _has_loadClassInternal = (method != NULL);
2003 }
2004 { // Compute whether we should use checkPackageAccess or NOT
2005 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2006 _has_checkPackageAccess = (method != NULL);
2007 }
2008 }
2009
2010 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2011 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2012 BasicType SystemDictionary::box_klass_type(Klass* k) {
2013 assert(k != NULL, "");
2014 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2015 if (_box_klasses[i] == k)
2016 return (BasicType)i;
2017 }
2018 return T_OBJECT;
2019 }
2020
2021 // Constraints on class loaders. The details of the algorithm can be
2022 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2023 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2024 // that the system dictionary needs to maintain a set of contraints that
2025 // must be satisfied by all classes in the dictionary.
2026 // if defining is true, then LinkageError if already in systemDictionary
2027 // if initiating loader, then ok if InstanceKlass matches existing entry
2028
2029 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2030 instanceKlassHandle k,
2031 Handle class_loader, bool defining,
2032 TRAPS) {
2033 const char *linkage_error1 = NULL;
2034 const char *linkage_error2 = NULL;
2035 {
2036 Symbol* name = k->name();
2037 ClassLoaderData *loader_data = class_loader_data(class_loader);
2038
2039 MutexLocker mu(SystemDictionary_lock, THREAD);
2040
2041 Klass* check = find_class(d_index, d_hash, name, loader_data);
2042 if (check != (Klass*)NULL) {
2043 // if different InstanceKlass - duplicate class definition,
2044 // else - ok, class loaded by a different thread in parallel,
2045 // we should only have found it if it was done loading and ok to use
2046 // system dictionary only holds instance classes, placeholders
2047 // also holds array classes
2048
2049 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2050 if ((defining == true) || (k() != check)) {
2051 linkage_error1 = "loader (instance of ";
2052 linkage_error2 = "): attempted duplicate class definition for name: \"";
2053 } else {
2054 return;
2055 }
2056 }
2057
2058 #ifdef ASSERT
2059 Symbol* ph_check = find_placeholder(name, loader_data);
2060 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2061 #endif
2062
2063 if (linkage_error1 == NULL) {
2064 if (constraints()->check_or_update(k, class_loader, name) == false) {
2065 linkage_error1 = "loader constraint violation: loader (instance of ";
2066 linkage_error2 = ") previously initiated loading for a different type with name \"";
2067 }
2068 }
2069 }
2070
2071 // Throw error now if needed (cannot throw while holding
2072 // SystemDictionary_lock because of rank ordering)
2073
2074 if (linkage_error1) {
2075 ResourceMark rm(THREAD);
2076 const char* class_loader_name = loader_name(class_loader());
2077 char* type_name = k->name()->as_C_string();
2078 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2079 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2080 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2081 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2082 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2083 }
2084 }
2085
2086
2087 // Update system dictionary - done after check_constraint and add_to_hierachy
2088 // have been called.
2089 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2090 int p_index, unsigned int p_hash,
2091 instanceKlassHandle k,
2092 Handle class_loader,
2093 TRAPS) {
2094 // Compile_lock prevents systemDictionary updates during compilations
2095 assert_locked_or_safepoint(Compile_lock);
2096 Symbol* name = k->name();
2097 ClassLoaderData *loader_data = class_loader_data(class_loader);
2098
2099 {
2100 MutexLocker mu1(SystemDictionary_lock, THREAD);
2101
2102 // See whether biased locking is enabled and if so set it for this
2103 // klass.
2104 // Note that this must be done past the last potential blocking
2105 // point / safepoint. We enable biased locking lazily using a
2106 // VM_Operation to iterate the SystemDictionary and installing the
2107 // biasable mark word into each InstanceKlass's prototype header.
2108 // To avoid race conditions where we accidentally miss enabling the
2109 // optimization for one class in the process of being added to the
2110 // dictionary, we must not safepoint after the test of
2111 // BiasedLocking::enabled().
2112 if (UseBiasedLocking && BiasedLocking::enabled()) {
2113 // Set biased locking bit for all loaded classes; it will be
2114 // cleared if revocation occurs too often for this type
2115 // NOTE that we must only do this when the class is initally
2116 // defined, not each time it is referenced from a new class loader
2117 if (k->class_loader() == class_loader()) {
2118 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2119 }
2120 }
2121
2122 // Make a new system dictionary entry.
2123 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2124 if (sd_check == NULL) {
2125 dictionary()->add_klass(name, loader_data, k);
2126 notice_modification();
2127 }
2128 #ifdef ASSERT
2129 sd_check = find_class(d_index, d_hash, name, loader_data);
2130 assert (sd_check != NULL, "should have entry in system dictionary");
2131 // Note: there may be a placeholder entry: for circularity testing
2132 // or for parallel defines
2133 #endif
2134 SystemDictionary_lock->notify_all();
2135 }
2136 }
2137
2138
2139 // Try to find a class name using the loader constraints. The
2140 // loader constraints might know about a class that isn't fully loaded
2141 // yet and these will be ignored.
2142 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2143 Symbol* class_name, Handle class_loader, TRAPS) {
2144
2145 // First see if it has been loaded directly.
2146 // Force the protection domain to be null. (This removes protection checks.)
2147 Handle no_protection_domain;
2148 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2149 no_protection_domain, CHECK_NULL);
2150 if (klass != NULL)
2151 return klass;
2152
2153 // Now look to see if it has been loaded elsewhere, and is subject to
2154 // a loader constraint that would require this loader to return the
2155 // klass that is already loaded.
2156 if (FieldType::is_array(class_name)) {
2157 // For array classes, their Klass*s are not kept in the
2158 // constraint table. The element Klass*s are.
2159 FieldArrayInfo fd;
2160 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2161 if (t != T_OBJECT) {
2162 klass = Universe::typeArrayKlassObj(t);
2163 } else {
2164 MutexLocker mu(SystemDictionary_lock, THREAD);
2165 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2166 }
2167 // If element class already loaded, allocate array klass
2168 if (klass != NULL) {
2169 klass = klass->array_klass_or_null(fd.dimension());
2170 }
2171 } else {
2172 MutexLocker mu(SystemDictionary_lock, THREAD);
2173 // Non-array classes are easy: simply check the constraint table.
2174 klass = constraints()->find_constrained_klass(class_name, class_loader);
2175 }
2176
2177 return klass;
2178 }
2179
2180
2181 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2182 Handle class_loader1,
2183 Handle class_loader2,
2184 Thread* THREAD) {
2185 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2186 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2187
2188 Symbol* constraint_name = NULL;
2189 if (!FieldType::is_array(class_name)) {
2190 constraint_name = class_name;
2191 } else {
2192 // For array classes, their Klass*s are not kept in the
2193 // constraint table. The element classes are.
2194 FieldArrayInfo fd;
2195 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2196 // primitive types always pass
2197 if (t != T_OBJECT) {
2198 return true;
2199 } else {
2200 constraint_name = fd.object_key();
2201 }
2202 }
2203 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2204 int d_index1 = dictionary()->hash_to_index(d_hash1);
2205
2206 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2207 int d_index2 = dictionary()->hash_to_index(d_hash2);
2208 {
2209 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2210
2211 // Better never do a GC while we're holding these oops
2212 No_Safepoint_Verifier nosafepoint;
2213
2214 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2215 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2216 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2217 klass2, class_loader2);
2218 }
2219 }
2220
2221 // Add entry to resolution error table to record the error when the first
2222 // attempt to resolve a reference to a class has failed.
2223 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2224 Symbol* error, Symbol* message) {
2225 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2226 int index = resolution_errors()->hash_to_index(hash);
2227 {
2228 MutexLocker ml(SystemDictionary_lock, Thread::current());
2229 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2230 }
2231 }
2232
2233 // Delete a resolution error for RedefineClasses for a constant pool is going away
2234 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2235 resolution_errors()->delete_entry(pool);
2236 }
2237
2238 // Lookup resolution error table. Returns error if found, otherwise NULL.
2239 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2240 Symbol** message) {
2241 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2242 int index = resolution_errors()->hash_to_index(hash);
2243 {
2244 MutexLocker ml(SystemDictionary_lock, Thread::current());
2245 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2246 if (entry != NULL) {
2247 *message = entry->message();
2248 return entry->error();
2249 } else {
2250 return NULL;
2251 }
2252 }
2253 }
2254
2255
2256 // Signature constraints ensure that callers and callees agree about
2257 // the meaning of type names in their signatures. This routine is the
2258 // intake for constraints. It collects them from several places:
2259 //
2260 // * LinkResolver::resolve_method (if check_access is true) requires
2261 // that the resolving class (the caller) and the defining class of
2262 // the resolved method (the callee) agree on each type in the
2263 // method's signature.
2264 //
2265 // * LinkResolver::resolve_interface_method performs exactly the same
2266 // checks.
2267 //
2268 // * LinkResolver::resolve_field requires that the constant pool
2269 // attempting to link to a field agree with the field's defining
2270 // class about the type of the field signature.
2271 //
2272 // * klassVtable::initialize_vtable requires that, when a class
2273 // overrides a vtable entry allocated by a superclass, that the
2274 // overriding method (i.e., the callee) agree with the superclass
2275 // on each type in the method's signature.
2276 //
2277 // * klassItable::initialize_itable requires that, when a class fills
2278 // in its itables, for each non-abstract method installed in an
2279 // itable, the method (i.e., the callee) agree with the interface
2280 // on each type in the method's signature.
2281 //
2282 // All those methods have a boolean (check_access, checkconstraints)
2283 // which turns off the checks. This is used from specialized contexts
2284 // such as bootstrapping, dumping, and debugging.
2285 //
2286 // No direct constraint is placed between the class and its
2287 // supertypes. Constraints are only placed along linked relations
2288 // between callers and callees. When a method overrides or implements
2289 // an abstract method in a supertype (superclass or interface), the
2290 // constraints are placed as if the supertype were the caller to the
2291 // overriding method. (This works well, since callers to the
2292 // supertype have already established agreement between themselves and
2293 // the supertype.) As a result of all this, a class can disagree with
2294 // its supertype about the meaning of a type name, as long as that
2295 // class neither calls a relevant method of the supertype, nor is
2296 // called (perhaps via an override) from the supertype.
2297 //
2298 //
2299 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2300 //
2301 // Make sure all class components (including arrays) in the given
2302 // signature will be resolved to the same class in both loaders.
2303 // Returns the name of the type that failed a loader constraint check, or
2304 // NULL if no constraint failed. No exception except OOME is thrown.
2305 // Arrays are not added to the loader constraint table, their elements are.
2306 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2307 Handle loader1, Handle loader2,
2308 bool is_method, TRAPS) {
2309 // Nothing to do if loaders are the same.
2310 if (loader1() == loader2()) {
2311 return NULL;
2312 }
2313
2314 SignatureStream sig_strm(signature, is_method);
2315 while (!sig_strm.is_done()) {
2316 if (sig_strm.is_object()) {
2317 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2318 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2319 return sig;
2320 }
2321 }
2322 sig_strm.next();
2323 }
2324 return NULL;
2325 }
2326
2327
2328 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2329 Symbol* signature,
2330 TRAPS) {
2331 methodHandle empty;
2332 assert(MethodHandles::is_signature_polymorphic(iid) &&
2333 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2334 iid != vmIntrinsics::_invokeGeneric,
2335 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2336
2337 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2338 int index = invoke_method_table()->hash_to_index(hash);
2339 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2340 methodHandle m;
2341 if (spe == NULL || spe->method() == NULL) {
2342 spe = NULL;
2343 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2344 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2345 if (!Arguments::is_interpreter_only()) {
2346 // Generate a compiled form of the MH intrinsic.
2347 AdapterHandlerLibrary::create_native_wrapper(m);
2348 // Check if have the compiled code.
2349 if (!m->has_compiled_code()) {
2350 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2351 "Out of space in CodeCache for method handle intrinsic", empty);
2352 }
2353 }
2354 // Now grab the lock. We might have to throw away the new method,
2355 // if a racing thread has managed to install one at the same time.
2356 {
2357 MutexLocker ml(SystemDictionary_lock, THREAD);
2358 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2359 if (spe == NULL)
2360 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2361 if (spe->method() == NULL)
2362 spe->set_method(m());
2363 }
2364 }
2365
2366 assert(spe != NULL && spe->method() != NULL, "");
2367 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2368 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2369 "MH intrinsic invariant");
2370 return spe->method();
2371 }
2372
2373 // Helper for unpacking the return value from linkMethod and linkCallSite.
2374 static methodHandle unpack_method_and_appendix(Handle mname,
2375 KlassHandle accessing_klass,
2376 objArrayHandle appendix_box,
2377 Handle* appendix_result,
2378 TRAPS) {
2379 methodHandle empty;
2380 if (mname.not_null()) {
2381 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2382 if (vmtarget != NULL && vmtarget->is_method()) {
2383 Method* m = (Method*)vmtarget;
2384 oop appendix = appendix_box->obj_at(0);
2385 if (TraceMethodHandles) {
2386 #ifndef PRODUCT
2387 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2388 m->print();
2389 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2390 tty->cr();
2391 #endif //PRODUCT
2392 }
2393 (*appendix_result) = Handle(THREAD, appendix);
2394 // the target is stored in the cpCache and if a reference to this
2395 // MethodName is dropped we need a way to make sure the
2396 // class_loader containing this method is kept alive.
2397 // FIXME: the appendix might also preserve this dependency.
2398 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2399 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2400 return methodHandle(THREAD, m);
2401 }
2402 }
2403 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2404 return empty;
2405 }
2406
2407 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2408 Symbol* signature,
2409 KlassHandle accessing_klass,
2410 Handle *appendix_result,
2411 Handle *method_type_result,
2412 TRAPS) {
2413 methodHandle empty;
2414 assert(THREAD->can_call_java() ,"");
2415 Handle method_type =
2416 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2417
2418 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2419 int ref_kind = JVM_REF_invokeVirtual;
2420 Handle name_str = StringTable::intern(name, CHECK_(empty));
2421 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2422 assert(appendix_box->obj_at(0) == NULL, "");
2423
2424 // This should not happen. JDK code should take care of that.
2425 if (accessing_klass.is_null() || method_type.is_null()) {
2426 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2427 }
2428
2429 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2430 JavaCallArguments args;
2431 args.push_oop(accessing_klass()->java_mirror());
2432 args.push_int(ref_kind);
2433 args.push_oop(mh_klass()->java_mirror());
2434 args.push_oop(name_str());
2435 args.push_oop(method_type());
2436 args.push_oop(appendix_box());
2437 JavaValue result(T_OBJECT);
2438 JavaCalls::call_static(&result,
2439 SystemDictionary::MethodHandleNatives_klass(),
2440 vmSymbols::linkMethod_name(),
2441 vmSymbols::linkMethod_signature(),
2442 &args, CHECK_(empty));
2443 Handle mname(THREAD, (oop) result.get_jobject());
2444 (*method_type_result) = method_type;
2445 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2446 }
2447
2448 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2449 // We must ensure that all class loaders everywhere will reach this class, for any client.
2450 // This is a safe bet for public classes in java.lang, such as Object and String.
2451 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2452 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2453 static bool is_always_visible_class(oop mirror) {
2454 Klass* klass = java_lang_Class::as_Klass(mirror);
2455 if (klass->is_objArray_klass()) {
2456 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2457 }
2458 if (klass->is_typeArray_klass()) {
2459 return true; // primitive array
2460 }
2461 assert(klass->is_instance_klass(), "%s", klass->external_name());
2462 return klass->is_public() &&
2463 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2464 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2465 }
2466
2467 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2468 // signature, as interpreted relative to the given class loader.
2469 // Because of class loader constraints, all method handle usage must be
2470 // consistent with this loader.
2471 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2472 KlassHandle accessing_klass,
2473 TRAPS) {
2474 Handle empty;
2475 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2476 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2477 int index = invoke_method_table()->hash_to_index(hash);
2478 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2479 if (spe != NULL && spe->method_type() != NULL) {
2480 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2481 return Handle(THREAD, spe->method_type());
2482 } else if (!THREAD->can_call_java()) {
2483 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2484 return Handle(); // do not attempt from within compiler, unless it was cached
2485 }
2486
2487 Handle class_loader, protection_domain;
2488 if (accessing_klass.not_null()) {
2489 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2490 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2491 }
2492 bool can_be_cached = true;
2493 int npts = ArgumentCount(signature).size();
2494 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2495 int arg = 0;
2496 Handle rt; // the return type from the signature
2497 ResourceMark rm(THREAD);
2498 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2499 oop mirror = NULL;
2500 if (can_be_cached) {
2501 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2502 mirror = ss.as_java_mirror(Handle(), Handle(),
2503 SignatureStream::ReturnNull, CHECK_(empty));
2504 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2505 // Fall back to accessing_klass context.
2506 can_be_cached = false;
2507 }
2508 }
2509 if (!can_be_cached) {
2510 // Resolve, throwing a real error if it doesn't work.
2511 mirror = ss.as_java_mirror(class_loader, protection_domain,
2512 SignatureStream::NCDFError, CHECK_(empty));
2513 }
2514 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2515 if (ss.at_return_type())
2516 rt = Handle(THREAD, mirror);
2517 else
2518 pts->obj_at_put(arg++, mirror);
2519
2520 // Check accessibility.
2521 if (ss.is_object() && accessing_klass.not_null()) {
2522 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2523 mirror = NULL; // safety
2524 // Emulate ConstantPool::verify_constant_pool_resolve.
2525 if (sel_klass->is_objArray_klass())
2526 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2527 if (sel_klass->is_instance_klass()) {
2528 KlassHandle sel_kh(THREAD, sel_klass);
2529 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2530 }
2531 }
2532 }
2533 assert(arg == npts, "");
2534
2535 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2536 JavaCallArguments args(Handle(THREAD, rt()));
2537 args.push_oop(pts());
2538 JavaValue result(T_OBJECT);
2539 JavaCalls::call_static(&result,
2540 SystemDictionary::MethodHandleNatives_klass(),
2541 vmSymbols::findMethodHandleType_name(),
2542 vmSymbols::findMethodHandleType_signature(),
2543 &args, CHECK_(empty));
2544 Handle method_type(THREAD, (oop) result.get_jobject());
2545
2546 if (can_be_cached) {
2547 // We can cache this MethodType inside the JVM.
2548 MutexLocker ml(SystemDictionary_lock, THREAD);
2549 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2550 if (spe == NULL)
2551 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2552 if (spe->method_type() == NULL) {
2553 spe->set_method_type(method_type());
2554 }
2555 }
2556
2557 // report back to the caller with the MethodType
2558 return method_type;
2559 }
2560
2561 // Ask Java code to find or construct a method handle constant.
2562 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2563 int ref_kind, //e.g., JVM_REF_invokeVirtual
2564 KlassHandle callee,
2565 Symbol* name_sym,
2566 Symbol* signature,
2567 TRAPS) {
2568 Handle empty;
2569 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2570 Handle type;
2571 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2572 type = find_method_handle_type(signature, caller, CHECK_(empty));
2573 } else if (caller.is_null()) {
2574 // This should not happen. JDK code should take care of that.
2575 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2576 } else {
2577 ResourceMark rm(THREAD);
2578 SignatureStream ss(signature, false);
2579 if (!ss.is_done()) {
2580 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2581 SignatureStream::NCDFError, CHECK_(empty));
2582 type = Handle(THREAD, mirror);
2583 ss.next();
2584 if (!ss.is_done()) type = Handle(); // error!
2585 }
2586 }
2587 if (type.is_null()) {
2588 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2589 }
2590
2591 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2592 JavaCallArguments args;
2593 args.push_oop(caller->java_mirror()); // the referring class
2594 args.push_int(ref_kind);
2595 args.push_oop(callee->java_mirror()); // the target class
2596 args.push_oop(name());
2597 args.push_oop(type());
2598 JavaValue result(T_OBJECT);
2599 JavaCalls::call_static(&result,
2600 SystemDictionary::MethodHandleNatives_klass(),
2601 vmSymbols::linkMethodHandleConstant_name(),
2602 vmSymbols::linkMethodHandleConstant_signature(),
2603 &args, CHECK_(empty));
2604 return Handle(THREAD, (oop) result.get_jobject());
2605 }
2606
2607 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2608 // name and signature, as interpreted relative to the given class loader.
2609 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2610 Handle bootstrap_specifier,
2611 Symbol* name,
2612 Symbol* type,
2613 Handle *appendix_result,
2614 Handle *method_type_result,
2615 TRAPS) {
2616 methodHandle empty;
2617 Handle bsm, info;
2618 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2619 bsm = bootstrap_specifier;
2620 } else {
2621 assert(bootstrap_specifier->is_objArray(), "");
2622 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2623 int len = args->length();
2624 assert(len >= 1, "");
2625 bsm = Handle(THREAD, args->obj_at(0));
2626 if (len > 1) {
2627 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2628 for (int i = 1; i < len; i++)
2629 args1->obj_at_put(i-1, args->obj_at(i));
2630 info = Handle(THREAD, args1);
2631 }
2632 }
2633 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2634 "caller must supply a valid BSM");
2635
2636 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2637 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2638
2639 // This should not happen. JDK code should take care of that.
2640 if (caller.is_null() || method_type.is_null()) {
2641 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2642 }
2643
2644 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2645 assert(appendix_box->obj_at(0) == NULL, "");
2646
2647 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2648 JavaCallArguments args;
2649 args.push_oop(caller->java_mirror());
2650 args.push_oop(bsm());
2651 args.push_oop(method_name());
2652 args.push_oop(method_type());
2653 args.push_oop(info());
2654 args.push_oop(appendix_box);
2655 JavaValue result(T_OBJECT);
2656 JavaCalls::call_static(&result,
2657 SystemDictionary::MethodHandleNatives_klass(),
2658 vmSymbols::linkCallSite_name(),
2659 vmSymbols::linkCallSite_signature(),
2660 &args, CHECK_(empty));
2661 Handle mname(THREAD, (oop) result.get_jobject());
2662 (*method_type_result) = method_type;
2663 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2664 }
2665
2666 // Since the identity hash code for symbols changes when the symbols are
2667 // moved from the regular perm gen (hash in the mark word) to the shared
2668 // spaces (hash is the address), the classes loaded into the dictionary
2669 // may be in the wrong buckets.
2670
2671 void SystemDictionary::reorder_dictionary() {
2672 dictionary()->reorder_dictionary();
2673 }
2674
2675
2676 void SystemDictionary::copy_buckets(char** top, char* end) {
2677 dictionary()->copy_buckets(top, end);
2678 }
2679
2680
2681 void SystemDictionary::copy_table(char** top, char* end) {
2682 dictionary()->copy_table(top, end);
2683 }
2684
2685
2686 void SystemDictionary::reverse() {
2687 dictionary()->reverse();
2688 }
2689
2690 int SystemDictionary::number_of_classes() {
2691 return dictionary()->number_of_entries();
2692 }
2693
2694
2695 // ----------------------------------------------------------------------------
2696 void SystemDictionary::print_shared(bool details) {
2697 shared_dictionary()->print(details);
2698 }
2699
2700 void SystemDictionary::print(bool details) {
2701 dictionary()->print(details);
2702
2703 // Placeholders
2704 GCMutexLocker mu(SystemDictionary_lock);
2705 placeholders()->print();
2706
2707 // loader constraints - print under SD_lock
2708 constraints()->print();
2709 }
2710
2711
2712 void SystemDictionary::verify() {
2713 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2714 guarantee(constraints() != NULL,
2715 "Verify of loader constraints failed");
2716 guarantee(dictionary()->number_of_entries() >= 0 &&
2717 placeholders()->number_of_entries() >= 0,
2718 "Verify of system dictionary failed");
2719
2720 // Verify dictionary
2721 dictionary()->verify();
2722
2723 GCMutexLocker mu(SystemDictionary_lock);
2724 placeholders()->verify();
2725
2726 // Verify constraint table
2727 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2728 constraints()->verify(dictionary(), placeholders());
2729 }
2730
2731 // caller needs ResourceMark
2732 const char* SystemDictionary::loader_name(const oop loader) {
2733 return ((loader) == NULL ? "<bootloader>" :
2734 InstanceKlass::cast((loader)->klass())->name()->as_C_string());
2735 }
2736
2737 // caller needs ResourceMark
2738 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
2739 return (loader_data->class_loader() == NULL ? "<bootloader>" :
2740 InstanceKlass::cast((loader_data->class_loader())->klass())->name()->as_C_string());
2741 }