1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classFileParser.hpp"
27 #include "classfile/classFileStream.hpp"
28 #include "classfile/classLoader.hpp"
29 #include "classfile/classLoaderData.inline.hpp"
30 #include "classfile/classLoaderExt.hpp"
31 #include "classfile/dictionary.hpp"
32 #include "classfile/javaClasses.inline.hpp"
33 #include "classfile/klassFactory.hpp"
34 #include "classfile/loaderConstraints.hpp"
35 #include "classfile/placeholders.hpp"
36 #include "classfile/resolutionErrors.hpp"
37 #include "classfile/stringTable.hpp"
38 #include "classfile/systemDictionary.hpp"
39 #include "classfile/vmSymbols.hpp"
40 #include "code/codeCache.hpp"
41 #include "compiler/compileBroker.hpp"
42 #include "gc/shared/gcLocker.hpp"
43 #include "interpreter/bytecodeStream.hpp"
44 #include "interpreter/interpreter.hpp"
45 #include "memory/filemap.hpp"
46 #include "memory/oopFactory.hpp"
47 #include "oops/instanceKlass.hpp"
48 #include "oops/instanceRefKlass.hpp"
49 #include "oops/klass.inline.hpp"
50 #include "oops/methodData.hpp"
51 #include "oops/objArrayKlass.hpp"
52 #include "oops/objArrayOop.inline.hpp"
53 #include "oops/oop.inline.hpp"
54 #include "oops/typeArrayKlass.hpp"
55 #include "prims/jvmtiEnvBase.hpp"
56 #include "prims/methodHandles.hpp"
57 #include "runtime/arguments.hpp"
58 #include "runtime/biasedLocking.hpp"
59 #include "runtime/fieldType.hpp"
60 #include "runtime/handles.inline.hpp"
61 #include "runtime/java.hpp"
62 #include "runtime/javaCalls.hpp"
63 #include "runtime/mutexLocker.hpp"
64 #include "runtime/orderAccess.inline.hpp"
65 #include "runtime/signature.hpp"
66 #include "services/classLoadingService.hpp"
67 #include "services/threadService.hpp"
68 #include "utilities/macros.hpp"
69 #include "utilities/ticks.hpp"
70 #if INCLUDE_CDS
71 #include "classfile/sharedClassUtil.hpp"
72 #include "classfile/systemDictionaryShared.hpp"
73 #endif
74 #if INCLUDE_JVMCI
75 #include "jvmci/jvmciRuntime.hpp"
76 #endif
77 #if INCLUDE_TRACE
78 #include "trace/tracing.hpp"
79 #endif
80
81 Dictionary* SystemDictionary::_dictionary = NULL;
82 PlaceholderTable* SystemDictionary::_placeholders = NULL;
83 Dictionary* SystemDictionary::_shared_dictionary = NULL;
84 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
85 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
86 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
87
88
89 int SystemDictionary::_number_of_modifications = 0;
90 int SystemDictionary::_sdgeneration = 0;
91 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
92 20201,40423,99991};
93
94 oop SystemDictionary::_system_loader_lock_obj = NULL;
95
96 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
97 = { NULL /*, NULL...*/ };
98
99 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
100
101 oop SystemDictionary::_java_system_loader = NULL;
102
103 bool SystemDictionary::_has_loadClassInternal = false;
104 bool SystemDictionary::_has_checkPackageAccess = false;
105
106 // lazily initialized klass variables
107 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
108
109
110 // ----------------------------------------------------------------------------
111 // Java-level SystemLoader
112
113 oop SystemDictionary::java_system_loader() {
114 return _java_system_loader;
115 }
116
117 void SystemDictionary::compute_java_system_loader(TRAPS) {
118 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
119 JavaValue result(T_OBJECT);
120 JavaCalls::call_static(&result,
121 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
122 vmSymbols::getSystemClassLoader_name(),
123 vmSymbols::void_classloader_signature(),
124 CHECK);
125
126 _java_system_loader = (oop)result.get_jobject();
127
128 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
129 }
130
131
132 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
133 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
134 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
135 }
136
137 // ----------------------------------------------------------------------------
138 // debugging
139
140 #ifdef ASSERT
141
142 // return true if class_name contains no '.' (internal format is '/')
143 bool SystemDictionary::is_internal_format(Symbol* class_name) {
144 if (class_name != NULL) {
145 ResourceMark rm;
146 char* name = class_name->as_C_string();
147 return strchr(name, '.') == NULL;
148 } else {
149 return true;
150 }
151 }
152
153 #endif
154
155 // ----------------------------------------------------------------------------
156 // Parallel class loading check
157
158 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
159 if (UnsyncloadClass || class_loader.is_null()) return true;
160 if (AlwaysLockClassLoader) return false;
161 return java_lang_ClassLoader::parallelCapable(class_loader());
162 }
163 // ----------------------------------------------------------------------------
164 // ParallelDefineClass flag does not apply to bootclass loader
165 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
166 if (class_loader.is_null()) return false;
167 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
168 return true;
169 }
170 return false;
171 }
172
173 /**
174 * Returns true if the passed class loader is the extension class loader.
175 */
176 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
177 if (class_loader.is_null()) {
178 return false;
179 }
180 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
181 }
182
183 // ----------------------------------------------------------------------------
184 // Resolving of classes
185
186 // Forwards to resolve_or_null
187
188 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
189 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
190 if (HAS_PENDING_EXCEPTION || klass == NULL) {
191 KlassHandle k_h(THREAD, klass);
192 // can return a null klass
193 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD);
194 }
195 return klass;
196 }
197
198 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
199 bool throw_error,
200 KlassHandle klass_h, TRAPS) {
201 if (HAS_PENDING_EXCEPTION) {
202 // If we have a pending exception we forward it to the caller, unless throw_error is true,
203 // in which case we have to check whether the pending exception is a ClassNotFoundException,
204 // and if so convert it to a NoClassDefFoundError
205 // And chain the original ClassNotFoundException
206 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
207 ResourceMark rm(THREAD);
208 assert(klass_h() == NULL, "Should not have result with exception pending");
209 Handle e(THREAD, PENDING_EXCEPTION);
210 CLEAR_PENDING_EXCEPTION;
211 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
212 } else {
213 return NULL;
214 }
215 }
216 // Class not found, throw appropriate error or exception depending on value of throw_error
217 if (klass_h() == NULL) {
218 ResourceMark rm(THREAD);
219 if (throw_error) {
220 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
221 } else {
222 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
223 }
224 }
225 return (Klass*)klass_h();
226 }
227
228
229 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
230 bool throw_error, TRAPS)
231 {
232 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
233 }
234
235
236 // Forwards to resolve_instance_class_or_null
237
238 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
239 assert(THREAD->can_call_java(),
240 "can not load classes with compiler thread: class=%s, classloader=%s",
241 class_name->as_C_string(),
242 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
243 if (FieldType::is_array(class_name)) {
244 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
245 } else if (FieldType::is_obj(class_name)) {
246 ResourceMark rm(THREAD);
247 // Ignore wrapping L and ;.
248 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
249 class_name->utf8_length() - 2, CHECK_NULL);
250 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
251 } else {
252 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
253 }
254 }
255
256 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
257 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
258 }
259
260 // Forwards to resolve_instance_class_or_null
261
262 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
263 Handle class_loader,
264 Handle protection_domain,
265 TRAPS) {
266 assert(FieldType::is_array(class_name), "must be array");
267 Klass* k = NULL;
268 FieldArrayInfo fd;
269 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
270 // of this call
271 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
272 if (t == T_OBJECT) {
273 // naked oop "k" is OK here -- we assign back into it
274 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
275 class_loader,
276 protection_domain,
277 CHECK_NULL);
278 if (k != NULL) {
279 k = k->array_klass(fd.dimension(), CHECK_NULL);
280 }
281 } else {
282 k = Universe::typeArrayKlassObj(t);
283 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
284 }
285 return k;
286 }
287
288
289 // Must be called for any super-class or super-interface resolution
290 // during class definition to allow class circularity checking
291 // super-interface callers:
292 // parse_interfaces - for defineClass & jvmtiRedefineClasses
293 // super-class callers:
294 // ClassFileParser - for defineClass & jvmtiRedefineClasses
295 // load_shared_class - while loading a class from shared archive
296 // resolve_instance_class_or_null:
297 // via: handle_parallel_super_load
298 // when resolving a class that has an existing placeholder with
299 // a saved superclass [i.e. a defineClass is currently in progress]
300 // if another thread is trying to resolve the class, it must do
301 // super-class checks on its own thread to catch class circularity
302 // This last call is critical in class circularity checking for cases
303 // where classloading is delegated to different threads and the
304 // classloader lock is released.
305 // Take the case: Base->Super->Base
306 // 1. If thread T1 tries to do a defineClass of class Base
307 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
308 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
309 // so it tries to load Super
310 // 3. If we load the class internally, or user classloader uses same thread
311 // loadClassFromxxx or defineClass via parseClassFile Super ...
312 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
313 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
314 // 3.4 calls resolve_super_or_fail Base
315 // 3.5 finds T1,Base -> throws class circularity
316 //OR 4. If T2 tries to resolve Super via defineClass Super ...
317 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
318 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
319 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
320 // 4.4 finds T2, Super -> throws class circularity
321 // Must be called, even if superclass is null, since this is
322 // where the placeholder entry is created which claims this
323 // thread is loading this class/classloader.
324 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
325 Symbol* class_name,
326 Handle class_loader,
327 Handle protection_domain,
328 bool is_superclass,
329 TRAPS) {
330 #if INCLUDE_CDS
331 if (DumpSharedSpaces) {
332 // Special processing for CDS dump time.
333 Klass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
334 class_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
335 if (k) {
336 return k;
337 }
338 }
339 #endif // INCLUDE_CDS
340
341 // Double-check, if child class is already loaded, just return super-class,interface
342 // Don't add a placedholder if already loaded, i.e. already in system dictionary
343 // Make sure there's a placeholder for the *child* before resolving.
344 // Used as a claim that this thread is currently loading superclass/classloader
345 // Used here for ClassCircularity checks and also for heap verification
346 // (every InstanceKlass in the heap needs to be in the system dictionary
347 // or have a placeholder).
348 // Must check ClassCircularity before checking if super class is already loaded
349 //
350 // We might not already have a placeholder if this child_name was
351 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
352 // the name of the class might not be known until the stream is actually
353 // parsed.
354 // Bugs 4643874, 4715493
355 // compute_hash can have a safepoint
356
357 ClassLoaderData* loader_data = class_loader_data(class_loader);
358 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
359 int d_index = dictionary()->hash_to_index(d_hash);
360 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
361 int p_index = placeholders()->hash_to_index(p_hash);
362 // can't throw error holding a lock
363 bool child_already_loaded = false;
364 bool throw_circularity_error = false;
365 {
366 MutexLocker mu(SystemDictionary_lock, THREAD);
367 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
368 Klass* quicksuperk;
369 // to support // loading: if child done loading, just return superclass
370 // if class_name, & class_loader don't match:
371 // if initial define, SD update will give LinkageError
372 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
373 // so we don't throw an exception here.
374 // see: nsk redefclass014 & java.lang.instrument Instrument032
375 if ((childk != NULL ) && (is_superclass) &&
376 ((quicksuperk = childk->super()) != NULL) &&
377
378 ((quicksuperk->name() == class_name) &&
379 (quicksuperk->class_loader() == class_loader()))) {
380 return quicksuperk;
381 } else {
382 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
383 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
384 throw_circularity_error = true;
385 }
386 }
387 if (!throw_circularity_error) {
388 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
389 }
390 }
391 if (throw_circularity_error) {
392 ResourceMark rm(THREAD);
393 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
394 }
395
396 // java.lang.Object should have been found above
397 assert(class_name != NULL, "null super class for resolving");
398 // Resolve the super class or interface, check results on return
399 Klass* superk = SystemDictionary::resolve_or_null(class_name,
400 class_loader,
401 protection_domain,
402 THREAD);
403
404 KlassHandle superk_h(THREAD, superk);
405
406 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
407 // It is no longer necessary to keep the placeholder table alive until update_dictionary
408 // or error. GC used to walk the placeholder table as strong roots.
409 // The instanceKlass is kept alive because the class loader is on the stack,
410 // which keeps the loader_data alive, as well as all instanceKlasses in
411 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
412 {
413 MutexLocker mu(SystemDictionary_lock, THREAD);
414 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
415 SystemDictionary_lock->notify_all();
416 }
417 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
418 // can null superk
419 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD));
420 }
421
422 return superk_h();
423 }
424
425 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
426 Handle class_loader,
427 Handle protection_domain,
428 TRAPS) {
429 if(!has_checkPackageAccess()) return;
430
431 // Now we have to call back to java to check if the initating class has access
432 JavaValue result(T_VOID);
433 if (TraceProtectionDomainVerification) {
434 // Print out trace information
435 tty->print_cr("Checking package access");
436 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
437 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
438 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
439 }
440
441 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
442 JavaCalls::call_special(&result,
443 class_loader,
444 system_loader,
445 vmSymbols::checkPackageAccess_name(),
446 vmSymbols::class_protectiondomain_signature(),
447 Handle(THREAD, klass->java_mirror()),
448 protection_domain,
449 THREAD);
450
451 if (TraceProtectionDomainVerification) {
452 if (HAS_PENDING_EXCEPTION) {
453 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
454 } else {
455 tty->print_cr(" -> granted");
456 }
457 tty->cr();
458 }
459
460 if (HAS_PENDING_EXCEPTION) return;
461
462 // If no exception has been thrown, we have validated the protection domain
463 // Insert the protection domain of the initiating class into the set.
464 {
465 // We recalculate the entry here -- we've called out to java since
466 // the last time it was calculated.
467 ClassLoaderData* loader_data = class_loader_data(class_loader);
468
469 Symbol* kn = klass->name();
470 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
471 int d_index = dictionary()->hash_to_index(d_hash);
472
473 MutexLocker mu(SystemDictionary_lock, THREAD);
474 {
475 // Note that we have an entry, and entries can be deleted only during GC,
476 // so we cannot allow GC to occur while we're holding this entry.
477
478 // We're using a No_Safepoint_Verifier to catch any place where we
479 // might potentially do a GC at all.
480 // Dictionary::do_unloading() asserts that classes in SD are only
481 // unloaded at a safepoint. Anonymous classes are not in SD.
482 No_Safepoint_Verifier nosafepoint;
483 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
484 protection_domain, THREAD);
485 }
486 }
487 }
488
489 // We only get here if this thread finds that another thread
490 // has already claimed the placeholder token for the current operation,
491 // but that other thread either never owned or gave up the
492 // object lock
493 // Waits on SystemDictionary_lock to indicate placeholder table updated
494 // On return, caller must recheck placeholder table state
495 //
496 // We only get here if
497 // 1) custom classLoader, i.e. not bootstrap classloader
498 // 2) UnsyncloadClass not set
499 // 3) custom classLoader has broken the class loader objectLock
500 // so another thread got here in parallel
501 //
502 // lockObject must be held.
503 // Complicated dance due to lock ordering:
504 // Must first release the classloader object lock to
505 // allow initial definer to complete the class definition
506 // and to avoid deadlock
507 // Reclaim classloader lock object with same original recursion count
508 // Must release SystemDictionary_lock after notify, since
509 // class loader lock must be claimed before SystemDictionary_lock
510 // to prevent deadlocks
511 //
512 // The notify allows applications that did an untimed wait() on
513 // the classloader object lock to not hang.
514 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
515 assert_lock_strong(SystemDictionary_lock);
516
517 bool calledholdinglock
518 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
519 assert(calledholdinglock,"must hold lock for notify");
520 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
521 ObjectSynchronizer::notifyall(lockObject, THREAD);
522 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
523 SystemDictionary_lock->wait();
524 SystemDictionary_lock->unlock();
525 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
526 SystemDictionary_lock->lock();
527 }
528
529 // If the class in is in the placeholder table, class loading is in progress
530 // For cases where the application changes threads to load classes, it
531 // is critical to ClassCircularity detection that we try loading
532 // the superclass on the same thread internally, so we do parallel
533 // super class loading here.
534 // This also is critical in cases where the original thread gets stalled
535 // even in non-circularity situations.
536 // Note: must call resolve_super_or_fail even if null super -
537 // to force placeholder entry creation for this class for circularity detection
538 // Caller must check for pending exception
539 // Returns non-null Klass* if other thread has completed load
540 // and we are done,
541 // If return null Klass* and no pending exception, the caller must load the class
542 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
543 Symbol* name, Symbol* superclassname, Handle class_loader,
544 Handle protection_domain, Handle lockObject, TRAPS) {
545
546 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
547 ClassLoaderData* loader_data = class_loader_data(class_loader);
548 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
549 int d_index = dictionary()->hash_to_index(d_hash);
550 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
551 int p_index = placeholders()->hash_to_index(p_hash);
552
553 // superk is not used, resolve_super called for circularity check only
554 // This code is reached in two situations. One if this thread
555 // is loading the same class twice (e.g. ClassCircularity, or
556 // java.lang.instrument).
557 // The second is if another thread started the resolve_super first
558 // and has not yet finished.
559 // In both cases the original caller will clean up the placeholder
560 // entry on error.
561 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
562 superclassname,
563 class_loader,
564 protection_domain,
565 true,
566 CHECK_(nh));
567
568 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
569 // Serial class loaders and bootstrap classloader do wait for superclass loads
570 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
571 MutexLocker mu(SystemDictionary_lock, THREAD);
572 // Check if classloading completed while we were loading superclass or waiting
573 Klass* check = find_class(d_index, d_hash, name, loader_data);
574 if (check != NULL) {
575 // Klass is already loaded, so just return it
576 return(instanceKlassHandle(THREAD, check));
577 } else {
578 return nh;
579 }
580 }
581
582 // must loop to both handle other placeholder updates
583 // and spurious notifications
584 bool super_load_in_progress = true;
585 PlaceholderEntry* placeholder;
586 while (super_load_in_progress) {
587 MutexLocker mu(SystemDictionary_lock, THREAD);
588 // Check if classloading completed while we were loading superclass or waiting
589 Klass* check = find_class(d_index, d_hash, name, loader_data);
590 if (check != NULL) {
591 // Klass is already loaded, so just return it
592 return(instanceKlassHandle(THREAD, check));
593 } else {
594 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
595 if (placeholder && placeholder->super_load_in_progress() ){
596 // Before UnsyncloadClass:
597 // We only get here if the application has released the
598 // classloader lock when another thread was in the middle of loading a
599 // superclass/superinterface for this class, and now
600 // this thread is also trying to load this class.
601 // To minimize surprises, the first thread that started to
602 // load a class should be the one to complete the loading
603 // with the classfile it initially expected.
604 // This logic has the current thread wait once it has done
605 // all the superclass/superinterface loading it can, until
606 // the original thread completes the class loading or fails
607 // If it completes we will use the resulting InstanceKlass
608 // which we will find below in the systemDictionary.
609 // We also get here for parallel bootstrap classloader
610 if (class_loader.is_null()) {
611 SystemDictionary_lock->wait();
612 } else {
613 double_lock_wait(lockObject, THREAD);
614 }
615 } else {
616 // If not in SD and not in PH, other thread's load must have failed
617 super_load_in_progress = false;
618 }
619 }
620 }
621 return (nh);
622 }
623
624 // utility function for class load event
625 static void post_class_load_event(const Ticks& start_time,
626 instanceKlassHandle k,
627 Handle initiating_loader) {
628 #if INCLUDE_TRACE
629 EventClassLoad event(UNTIMED);
630 if (event.should_commit()) {
631 event.set_starttime(start_time);
632 event.set_loadedClass(k());
633 oop defining_class_loader = k->class_loader();
634 event.set_definingClassLoader(defining_class_loader != NULL ?
635 defining_class_loader->klass() : (Klass*)NULL);
636 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
637 event.set_initiatingClassLoader(class_loader != NULL ?
638 class_loader->klass() : (Klass*)NULL);
639 event.commit();
640 }
641 #endif // INCLUDE_TRACE
642 }
643
644 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
645 Handle class_loader,
646 Handle protection_domain,
647 TRAPS) {
648 assert(name != NULL && !FieldType::is_array(name) &&
649 !FieldType::is_obj(name), "invalid class name");
650
651 Ticks class_load_start_time = Ticks::now();
652
653 // Fix for 4474172; see evaluation for more details
654 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
655 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
656
657 // Do lookup to see if class already exist and the protection domain
658 // has the right access
659 // This call uses find which checks protection domain already matches
660 // All subsequent calls use find_class, and set has_loaded_class so that
661 // before we return a result we call out to java to check for valid protection domain
662 // to allow returning the Klass* and add it to the pd_set if it is valid
663 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
664 int d_index = dictionary()->hash_to_index(d_hash);
665 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
666 protection_domain, THREAD);
667 if (probe != NULL) return probe;
668
669
670 // Non-bootstrap class loaders will call out to class loader and
671 // define via jvm/jni_DefineClass which will acquire the
672 // class loader object lock to protect against multiple threads
673 // defining the class in parallel by accident.
674 // This lock must be acquired here so the waiter will find
675 // any successful result in the SystemDictionary and not attempt
676 // the define
677 // ParallelCapable Classloaders and the bootstrap classloader,
678 // or all classloaders with UnsyncloadClass do not acquire lock here
679 bool DoObjectLock = true;
680 if (is_parallelCapable(class_loader)) {
681 DoObjectLock = false;
682 }
683
684 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
685 int p_index = placeholders()->hash_to_index(p_hash);
686
687 // Class is not in SystemDictionary so we have to do loading.
688 // Make sure we are synchronized on the class loader before we proceed
689 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
690 check_loader_lock_contention(lockObject, THREAD);
691 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
692
693 // Check again (after locking) if class already exist in SystemDictionary
694 bool class_has_been_loaded = false;
695 bool super_load_in_progress = false;
696 bool havesupername = false;
697 instanceKlassHandle k;
698 PlaceholderEntry* placeholder;
699 Symbol* superclassname = NULL;
700
701 {
702 MutexLocker mu(SystemDictionary_lock, THREAD);
703 Klass* check = find_class(d_index, d_hash, name, loader_data);
704 if (check != NULL) {
705 // Klass is already loaded, so just return it
706 class_has_been_loaded = true;
707 k = instanceKlassHandle(THREAD, check);
708 } else {
709 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
710 if (placeholder && placeholder->super_load_in_progress()) {
711 super_load_in_progress = true;
712 if (placeholder->havesupername() == true) {
713 superclassname = placeholder->supername();
714 havesupername = true;
715 }
716 }
717 }
718 }
719
720 // If the class is in the placeholder table, class loading is in progress
721 if (super_load_in_progress && havesupername==true) {
722 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
723 class_loader, protection_domain, lockObject, THREAD);
724 if (HAS_PENDING_EXCEPTION) {
725 return NULL;
726 }
727 if (!k.is_null()) {
728 class_has_been_loaded = true;
729 }
730 }
731
732 bool throw_circularity_error = false;
733 if (!class_has_been_loaded) {
734 bool load_instance_added = false;
735
736 // add placeholder entry to record loading instance class
737 // Five cases:
738 // All cases need to prevent modifying bootclasssearchpath
739 // in parallel with a classload of same classname
740 // Redefineclasses uses existence of the placeholder for the duration
741 // of the class load to prevent concurrent redefinition of not completely
742 // defined classes.
743 // case 1. traditional classloaders that rely on the classloader object lock
744 // - no other need for LOAD_INSTANCE
745 // case 2. traditional classloaders that break the classloader object lock
746 // as a deadlock workaround. Detection of this case requires that
747 // this check is done while holding the classloader object lock,
748 // and that lock is still held when calling classloader's loadClass.
749 // For these classloaders, we ensure that the first requestor
750 // completes the load and other requestors wait for completion.
751 // case 3. UnsyncloadClass - don't use objectLocker
752 // With this flag, we allow parallel classloading of a
753 // class/classloader pair
754 // case4. Bootstrap classloader - don't own objectLocker
755 // This classloader supports parallelism at the classloader level,
756 // but only allows a single load of a class/classloader pair.
757 // No performance benefit and no deadlock issues.
758 // case 5. parallelCapable user level classloaders - without objectLocker
759 // Allow parallel classloading of a class/classloader pair
760
761 {
762 MutexLocker mu(SystemDictionary_lock, THREAD);
763 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
764 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
765 if (oldprobe) {
766 // only need check_seen_thread once, not on each loop
767 // 6341374 java/lang/Instrument with -Xcomp
768 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
769 throw_circularity_error = true;
770 } else {
771 // case 1: traditional: should never see load_in_progress.
772 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
773
774 // case 4: bootstrap classloader: prevent futile classloading,
775 // wait on first requestor
776 if (class_loader.is_null()) {
777 SystemDictionary_lock->wait();
778 } else {
779 // case 2: traditional with broken classloader lock. wait on first
780 // requestor.
781 double_lock_wait(lockObject, THREAD);
782 }
783 // Check if classloading completed while we were waiting
784 Klass* check = find_class(d_index, d_hash, name, loader_data);
785 if (check != NULL) {
786 // Klass is already loaded, so just return it
787 k = instanceKlassHandle(THREAD, check);
788 class_has_been_loaded = true;
789 }
790 // check if other thread failed to load and cleaned up
791 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
792 }
793 }
794 }
795 }
796 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
797 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
798 // LOAD_INSTANCE in parallel
799
800 if (!throw_circularity_error && !class_has_been_loaded) {
801 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
802 load_instance_added = true;
803 // For class loaders that do not acquire the classloader object lock,
804 // if they did not catch another thread holding LOAD_INSTANCE,
805 // need a check analogous to the acquire ObjectLocker/find_class
806 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
807 // one final check if the load has already completed
808 // class loaders holding the ObjectLock shouldn't find the class here
809 Klass* check = find_class(d_index, d_hash, name, loader_data);
810 if (check != NULL) {
811 // Klass is already loaded, so return it after checking/adding protection domain
812 k = instanceKlassHandle(THREAD, check);
813 class_has_been_loaded = true;
814 }
815 }
816 }
817
818 // must throw error outside of owning lock
819 if (throw_circularity_error) {
820 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
821 ResourceMark rm(THREAD);
822 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
823 }
824
825 if (!class_has_been_loaded) {
826
827 // Do actual loading
828 k = load_instance_class(name, class_loader, THREAD);
829
830 // For UnsyncloadClass only
831 // If they got a linkageError, check if a parallel class load succeeded.
832 // If it did, then for bytecode resolution the specification requires
833 // that we return the same result we did for the other thread, i.e. the
834 // successfully loaded InstanceKlass
835 // Should not get here for classloaders that support parallelism
836 // with the new cleaner mechanism, even with AllowParallelDefineClass
837 // Bootstrap goes through here to allow for an extra guarantee check
838 if (UnsyncloadClass || (class_loader.is_null())) {
839 if (k.is_null() && HAS_PENDING_EXCEPTION
840 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
841 MutexLocker mu(SystemDictionary_lock, THREAD);
842 Klass* check = find_class(d_index, d_hash, name, loader_data);
843 if (check != NULL) {
844 // Klass is already loaded, so just use it
845 k = instanceKlassHandle(THREAD, check);
846 CLEAR_PENDING_EXCEPTION;
847 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
848 }
849 }
850 }
851
852 // If everything was OK (no exceptions, no null return value), and
853 // class_loader is NOT the defining loader, do a little more bookkeeping.
854 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
855 k->class_loader() != class_loader()) {
856
857 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
858
859 // Need to check for a PENDING_EXCEPTION again; check_constraints
860 // can throw and doesn't use the CHECK macro.
861 if (!HAS_PENDING_EXCEPTION) {
862 { // Grabbing the Compile_lock prevents systemDictionary updates
863 // during compilations.
864 MutexLocker mu(Compile_lock, THREAD);
865 update_dictionary(d_index, d_hash, p_index, p_hash,
866 k, class_loader, THREAD);
867 }
868
869 if (JvmtiExport::should_post_class_load()) {
870 Thread *thread = THREAD;
871 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
872 JvmtiExport::post_class_load((JavaThread *) thread, k());
873 }
874 }
875 }
876 } // load_instance_class loop
877
878 if (load_instance_added == true) {
879 // clean up placeholder entries for LOAD_INSTANCE success or error
880 // This brackets the SystemDictionary updates for both defining
881 // and initiating loaders
882 MutexLocker mu(SystemDictionary_lock, THREAD);
883 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
884 SystemDictionary_lock->notify_all();
885 }
886 }
887
888 if (HAS_PENDING_EXCEPTION || k.is_null()) {
889 return NULL;
890 }
891
892 post_class_load_event(class_load_start_time, k, class_loader);
893
894 #ifdef ASSERT
895 {
896 ClassLoaderData* loader_data = k->class_loader_data();
897 MutexLocker mu(SystemDictionary_lock, THREAD);
898 Klass* kk = find_class(name, loader_data);
899 assert(kk == k(), "should be present in dictionary");
900 }
901 #endif
902
903 // return if the protection domain in NULL
904 if (protection_domain() == NULL) return k();
905
906 // Check the protection domain has the right access
907 {
908 MutexLocker mu(SystemDictionary_lock, THREAD);
909 // Note that we have an entry, and entries can be deleted only during GC,
910 // so we cannot allow GC to occur while we're holding this entry.
911 // We're using a No_Safepoint_Verifier to catch any place where we
912 // might potentially do a GC at all.
913 // Dictionary::do_unloading() asserts that classes in SD are only
914 // unloaded at a safepoint. Anonymous classes are not in SD.
915 No_Safepoint_Verifier nosafepoint;
916 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
917 loader_data,
918 protection_domain)) {
919 return k();
920 }
921 }
922
923 // Verify protection domain. If it fails an exception is thrown
924 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
925
926 return k();
927 }
928
929
930 // This routine does not lock the system dictionary.
931 //
932 // Since readers don't hold a lock, we must make sure that system
933 // dictionary entries are only removed at a safepoint (when only one
934 // thread is running), and are added to in a safe way (all links must
935 // be updated in an MT-safe manner).
936 //
937 // Callers should be aware that an entry could be added just after
938 // _dictionary->bucket(index) is read here, so the caller will not see
939 // the new entry.
940
941 Klass* SystemDictionary::find(Symbol* class_name,
942 Handle class_loader,
943 Handle protection_domain,
944 TRAPS) {
945
946 // The result of this call should be consistent with the result
947 // of the call to resolve_instance_class_or_null().
948 // See evaluation 6790209 and 4474172 for more details.
949 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
950 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
951
952 if (loader_data == NULL) {
953 // If the ClassLoaderData has not been setup,
954 // then the class loader has no entries in the dictionary.
955 return NULL;
956 }
957
958 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
959 int d_index = dictionary()->hash_to_index(d_hash);
960
961 {
962 // Note that we have an entry, and entries can be deleted only during GC,
963 // so we cannot allow GC to occur while we're holding this entry.
964 // We're using a No_Safepoint_Verifier to catch any place where we
965 // might potentially do a GC at all.
966 // Dictionary::do_unloading() asserts that classes in SD are only
967 // unloaded at a safepoint. Anonymous classes are not in SD.
968 No_Safepoint_Verifier nosafepoint;
969 return dictionary()->find(d_index, d_hash, class_name, loader_data,
970 protection_domain, THREAD);
971 }
972 }
973
974
975 // Look for a loaded instance or array klass by name. Do not do any loading.
976 // return NULL in case of error.
977 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
978 Handle class_loader,
979 Handle protection_domain,
980 TRAPS) {
981 Klass* k = NULL;
982 assert(class_name != NULL, "class name must be non NULL");
983
984 if (FieldType::is_array(class_name)) {
985 // The name refers to an array. Parse the name.
986 // dimension and object_key in FieldArrayInfo are assigned as a
987 // side-effect of this call
988 FieldArrayInfo fd;
989 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
990 if (t != T_OBJECT) {
991 k = Universe::typeArrayKlassObj(t);
992 } else {
993 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
994 }
995 if (k != NULL) {
996 k = k->array_klass_or_null(fd.dimension());
997 }
998 } else {
999 k = find(class_name, class_loader, protection_domain, THREAD);
1000 }
1001 return k;
1002 }
1003
1004 // Note: this method is much like resolve_from_stream, but
1005 // updates no supplemental data structures.
1006 // TODO consolidate the two methods with a helper routine?
1007 Klass* SystemDictionary::parse_stream(Symbol* class_name,
1008 Handle class_loader,
1009 Handle protection_domain,
1010 ClassFileStream* st,
1011 const Klass* host_klass,
1012 GrowableArray<Handle>* cp_patches,
1013 TRAPS) {
1014
1015 Ticks class_load_start_time = Ticks::now();
1016
1017 ClassLoaderData* loader_data;
1018 if (host_klass != NULL) {
1019 // Create a new CLD for anonymous class, that uses the same class loader
1020 // as the host_klass
1021 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1022 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
1023 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1024 loader_data->record_dependency(host_klass, CHECK_NULL);
1025 } else {
1026 loader_data = ClassLoaderData::class_loader_data(class_loader());
1027 }
1028
1029 assert(st != NULL, "invariant");
1030 assert(st->need_verify(), "invariant");
1031
1032 // Parse stream and create a klass.
1033 // Note that we do this even though this klass might
1034 // already be present in the SystemDictionary, otherwise we would not
1035 // throw potential ClassFormatErrors.
1036
1037 instanceKlassHandle k = KlassFactory::create_from_stream(st,
1038 class_name,
1039 loader_data,
1040 protection_domain,
1041 host_klass,
1042 cp_patches,
1043 NULL, // parsed_name
1044 THREAD);
1045
1046 if (host_klass != NULL && k.not_null()) {
1047 // If it's anonymous, initialize it now, since nobody else will.
1048
1049 {
1050 MutexLocker mu_r(Compile_lock, THREAD);
1051
1052 // Add to class hierarchy, initialize vtables, and do possible
1053 // deoptimizations.
1054 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1055
1056 // But, do not add to system dictionary.
1057
1058 // compiled code dependencies need to be validated anyway
1059 notice_modification();
1060 }
1061
1062 // Rewrite and patch constant pool here.
1063 k->link_class(CHECK_NULL);
1064 if (cp_patches != NULL) {
1065 k->constants()->patch_resolved_references(cp_patches);
1066 }
1067 k->eager_initialize(CHECK_NULL);
1068
1069 // notify jvmti
1070 if (JvmtiExport::should_post_class_load()) {
1071 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1072 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1073 }
1074
1075 post_class_load_event(class_load_start_time, k, class_loader);
1076 }
1077 assert(host_klass != NULL || NULL == cp_patches,
1078 "cp_patches only found with host_klass");
1079
1080 return k();
1081 }
1082
1083 // Add a klass to the system from a stream (called by jni_DefineClass and
1084 // JVM_DefineClass).
1085 // Note: class_name can be NULL. In that case we do not know the name of
1086 // the class until we have parsed the stream.
1087
1088 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1089 Handle class_loader,
1090 Handle protection_domain,
1091 ClassFileStream* st,
1092 TRAPS) {
1093
1094 // Classloaders that support parallelism, e.g. bootstrap classloader,
1095 // or all classloaders with UnsyncloadClass do not acquire lock here
1096 bool DoObjectLock = true;
1097 if (is_parallelCapable(class_loader)) {
1098 DoObjectLock = false;
1099 }
1100
1101 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1102
1103 // Make sure we are synchronized on the class loader before we proceed
1104 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1105 check_loader_lock_contention(lockObject, THREAD);
1106 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1107
1108 assert(st != NULL, "invariant");
1109
1110 // Parse the stream and create a klass.
1111 // Note that we do this even though this klass might
1112 // already be present in the SystemDictionary, otherwise we would not
1113 // throw potential ClassFormatErrors.
1114 //
1115 // Note: "parsed_name" is updated.
1116 TempNewSymbol parsed_name = NULL;
1117
1118 instanceKlassHandle k;
1119
1120 #if INCLUDE_CDS
1121 k = SystemDictionaryShared::lookup_from_stream(class_name,
1122 class_loader,
1123 protection_domain,
1124 st,
1125 CHECK_NULL);
1126 #endif
1127
1128 if (k.not_null()) {
1129 parsed_name = k->name();
1130 } else {
1131 if (st->buffer() == NULL) {
1132 return NULL;
1133 }
1134 k = KlassFactory::create_from_stream(st,
1135 class_name,
1136 loader_data,
1137 protection_domain,
1138 NULL, // host_klass
1139 NULL, // cp_patches
1140 &parsed_name,
1141 THREAD);
1142 }
1143
1144 const char* pkg = "java/";
1145 if (!HAS_PENDING_EXCEPTION &&
1146 !class_loader.is_null() &&
1147 parsed_name != NULL &&
1148 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1149 // It is illegal to define classes in the "java." package from
1150 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1151 ResourceMark rm(THREAD);
1152 char* name = parsed_name->as_C_string();
1153 char* index = strrchr(name, '/');
1154 *index = '\0'; // chop to just the package name
1155 while ((index = strchr(name, '/')) != NULL) {
1156 *index = '.'; // replace '/' with '.' in package name
1157 }
1158 const char* fmt = "Prohibited package name: %s";
1159 size_t len = strlen(fmt) + strlen(name);
1160 char* message = NEW_RESOURCE_ARRAY(char, len);
1161 jio_snprintf(message, len, fmt, name);
1162 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1163 vmSymbols::java_lang_SecurityException(), message);
1164 }
1165
1166 if (!HAS_PENDING_EXCEPTION) {
1167 assert(parsed_name != NULL, "Sanity");
1168 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1169 // Verification prevents us from creating names with dots in them, this
1170 // asserts that that's the case.
1171 assert(is_internal_format(parsed_name),
1172 "external class name format used internally");
1173
1174 // Add class just loaded
1175 // If a class loader supports parallel classloading handle parallel define requests
1176 // find_or_define_instance_class may return a different InstanceKlass
1177 if (is_parallelCapable(class_loader)) {
1178 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1179 } else {
1180 define_instance_class(k, THREAD);
1181 }
1182 }
1183
1184 // Make sure we have an entry in the SystemDictionary on success
1185 debug_only( {
1186 if (!HAS_PENDING_EXCEPTION) {
1187 assert(parsed_name != NULL, "parsed_name is still null?");
1188 Symbol* h_name = k->name();
1189 ClassLoaderData *defining_loader_data = k->class_loader_data();
1190
1191 MutexLocker mu(SystemDictionary_lock, THREAD);
1192
1193 Klass* check = find_class(parsed_name, loader_data);
1194 assert(check == k(), "should be present in the dictionary");
1195
1196 Klass* check2 = find_class(h_name, defining_loader_data);
1197 assert(check == check2, "name inconsistancy in SystemDictionary");
1198 }
1199 } );
1200
1201 return k();
1202 }
1203
1204 #if INCLUDE_CDS
1205 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1206 int number_of_entries) {
1207 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1208 "bad shared dictionary size.");
1209 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1210 }
1211
1212
1213 // If there is a shared dictionary, then find the entry for the
1214 // given shared system class, if any.
1215
1216 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1217 if (shared_dictionary() != NULL) {
1218 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1219 int d_index = shared_dictionary()->hash_to_index(d_hash);
1220
1221 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1222 } else {
1223 return NULL;
1224 }
1225 }
1226
1227
1228 // Load a class from the shared spaces (found through the shared system
1229 // dictionary). Force the superclass and all interfaces to be loaded.
1230 // Update the class definition to include sibling classes and no
1231 // subclasses (yet). [Classes in the shared space are not part of the
1232 // object hierarchy until loaded.]
1233
1234 instanceKlassHandle SystemDictionary::load_shared_class(
1235 Symbol* class_name, Handle class_loader, TRAPS) {
1236 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1237 // Make sure we only return the boot class for the NULL classloader.
1238 if (ik.not_null() &&
1239 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1240 Handle protection_domain;
1241 return load_shared_class(ik, class_loader, protection_domain, THREAD);
1242 }
1243 return instanceKlassHandle();
1244 }
1245
1246 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1247 Handle class_loader,
1248 Handle protection_domain, TRAPS) {
1249 if (ik.not_null()) {
1250 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1251 Symbol* class_name = ik->name();
1252
1253 // Found the class, now load the superclass and interfaces. If they
1254 // are shared, add them to the main system dictionary and reset
1255 // their hierarchy references (supers, subs, and interfaces).
1256
1257 if (ik->super() != NULL) {
1258 Symbol* cn = ik->super()->name();
1259 Klass *s = resolve_super_or_fail(class_name, cn,
1260 class_loader, protection_domain, true, CHECK_(nh));
1261 if (s != ik->super()) {
1262 // The dynamically resolved super class is not the same as the one we used during dump time,
1263 // so we cannot use ik.
1264 return nh;
1265 }
1266 }
1267
1268 Array<Klass*>* interfaces = ik->local_interfaces();
1269 int num_interfaces = interfaces->length();
1270 for (int index = 0; index < num_interfaces; index++) {
1271 Klass* k = interfaces->at(index);
1272
1273 // Note: can not use InstanceKlass::cast here because
1274 // interfaces' InstanceKlass's C++ vtbls haven't been
1275 // reinitialized yet (they will be once the interface classes
1276 // are loaded)
1277 Symbol* name = k->name();
1278 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1279 if (k != i) {
1280 // The dynamically resolved interface class is not the same as the one we used during dump time,
1281 // so we cannot use ik.
1282 return nh;
1283 }
1284 }
1285
1286 // Adjust methods to recover missing data. They need addresses for
1287 // interpreter entry points and their default native method address
1288 // must be reset.
1289
1290 // Updating methods must be done under a lock so multiple
1291 // threads don't update these in parallel
1292 //
1293 // Shared classes are all currently loaded by either the bootstrap or
1294 // internal parallel class loaders, so this will never cause a deadlock
1295 // on a custom class loader lock.
1296
1297 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1298 {
1299 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1300 check_loader_lock_contention(lockObject, THREAD);
1301 ObjectLocker ol(lockObject, THREAD, true);
1302 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1303 }
1304
1305 if (TraceClassLoading) {
1306 ResourceMark rm;
1307 tty->print("[Loaded %s", ik->external_name());
1308 tty->print(" from shared objects file");
1309 if (class_loader.not_null()) {
1310 tty->print(" by %s", loader_data->loader_name());
1311 }
1312 tty->print_cr("]");
1313 }
1314
1315 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1316 // Only dump the classes that can be stored into CDS archive
1317 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1318 ResourceMark rm(THREAD);
1319 classlist_file->print_cr("%s", ik->name()->as_C_string());
1320 classlist_file->flush();
1321 }
1322 }
1323
1324 // notify a class loaded from shared object
1325 ClassLoadingService::notify_class_loaded(ik(), true /* shared class */);
1326 }
1327 return ik;
1328 }
1329 #endif // INCLUDE_CDS
1330
1331 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1332 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1333 if (class_loader.is_null()) {
1334
1335 // Search the shared system dictionary for classes preloaded into the
1336 // shared spaces.
1337 instanceKlassHandle k;
1338 {
1339 #if INCLUDE_CDS
1340 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1341 k = load_shared_class(class_name, class_loader, THREAD);
1342 #endif
1343 }
1344
1345 if (k.is_null()) {
1346 // Use VM class loader
1347 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1348 k = ClassLoader::load_class(class_name, CHECK_(nh));
1349 }
1350
1351 // find_or_define_instance_class may return a different InstanceKlass
1352 if (!k.is_null()) {
1353 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1354 }
1355 return k;
1356 } else {
1357 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1358 ResourceMark rm(THREAD);
1359
1360 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1361 JavaThread* jt = (JavaThread*) THREAD;
1362
1363 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1364 ClassLoader::perf_app_classload_selftime(),
1365 ClassLoader::perf_app_classload_count(),
1366 jt->get_thread_stat()->perf_recursion_counts_addr(),
1367 jt->get_thread_stat()->perf_timers_addr(),
1368 PerfClassTraceTime::CLASS_LOAD);
1369
1370 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1371 // Translate to external class name format, i.e., convert '/' chars to '.'
1372 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1373
1374 JavaValue result(T_OBJECT);
1375
1376 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1377
1378 // Call public unsynchronized loadClass(String) directly for all class loaders
1379 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1380 // acquire a class-name based lock rather than the class loader object lock.
1381 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1382 // so the call to loadClassInternal() was not required.
1383 //
1384 // UnsyncloadClass flag means both call loadClass(String) and do
1385 // not acquire the class loader lock even for class loaders that are
1386 // not parallelCapable. This was a risky transitional
1387 // flag for diagnostic purposes only. It is risky to call
1388 // custom class loaders without synchronization.
1389 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1390 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1391 // Do NOT assume this will be supported in future releases.
1392 //
1393 // Added MustCallLoadClassInternal in case we discover in the field
1394 // a customer that counts on this call
1395 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1396 JavaCalls::call_special(&result,
1397 class_loader,
1398 spec_klass,
1399 vmSymbols::loadClassInternal_name(),
1400 vmSymbols::string_class_signature(),
1401 string,
1402 CHECK_(nh));
1403 } else {
1404 JavaCalls::call_virtual(&result,
1405 class_loader,
1406 spec_klass,
1407 vmSymbols::loadClass_name(),
1408 vmSymbols::string_class_signature(),
1409 string,
1410 CHECK_(nh));
1411 }
1412
1413 assert(result.get_type() == T_OBJECT, "just checking");
1414 oop obj = (oop) result.get_jobject();
1415
1416 // Primitive classes return null since forName() can not be
1417 // used to obtain any of the Class objects representing primitives or void
1418 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1419 instanceKlassHandle k =
1420 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1421 // For user defined Java class loaders, check that the name returned is
1422 // the same as that requested. This check is done for the bootstrap
1423 // loader when parsing the class file.
1424 if (class_name == k->name()) {
1425 return k;
1426 }
1427 }
1428 // Class is not found or has the wrong name, return NULL
1429 return nh;
1430 }
1431 }
1432
1433 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1434
1435 ClassLoaderData* loader_data = k->class_loader_data();
1436 Handle class_loader_h(THREAD, loader_data->class_loader());
1437
1438 // for bootstrap and other parallel classloaders don't acquire lock,
1439 // use placeholder token
1440 // If a parallelCapable class loader calls define_instance_class instead of
1441 // find_or_define_instance_class to get here, we have a timing
1442 // hole with systemDictionary updates and check_constraints
1443 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1444 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1445 compute_loader_lock_object(class_loader_h, THREAD)),
1446 "define called without lock");
1447 }
1448
1449 // Check class-loading constraints. Throw exception if violation is detected.
1450 // Grabs and releases SystemDictionary_lock
1451 // The check_constraints/find_class call and update_dictionary sequence
1452 // must be "atomic" for a specific class/classloader pair so we never
1453 // define two different instanceKlasses for that class/classloader pair.
1454 // Existing classloaders will call define_instance_class with the
1455 // classloader lock held
1456 // Parallel classloaders will call find_or_define_instance_class
1457 // which will require a token to perform the define class
1458 Symbol* name_h = k->name();
1459 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1460 int d_index = dictionary()->hash_to_index(d_hash);
1461 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1462
1463 // Register class just loaded with class loader (placed in Vector)
1464 // Note we do this before updating the dictionary, as this can
1465 // fail with an OutOfMemoryError (if it does, we will *not* put this
1466 // class in the dictionary and will not update the class hierarchy).
1467 // JVMTI FollowReferences needs to find the classes this way.
1468 if (k->class_loader() != NULL) {
1469 methodHandle m(THREAD, Universe::loader_addClass_method());
1470 JavaValue result(T_VOID);
1471 JavaCallArguments args(class_loader_h);
1472 args.push_oop(Handle(THREAD, k->java_mirror()));
1473 JavaCalls::call(&result, m, &args, CHECK);
1474 }
1475
1476 // Add the new class. We need recompile lock during update of CHA.
1477 {
1478 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1479 int p_index = placeholders()->hash_to_index(p_hash);
1480
1481 MutexLocker mu_r(Compile_lock, THREAD);
1482
1483 // Add to class hierarchy, initialize vtables, and do possible
1484 // deoptimizations.
1485 add_to_hierarchy(k, CHECK); // No exception, but can block
1486
1487 // Add to systemDictionary - so other classes can see it.
1488 // Grabs and releases SystemDictionary_lock
1489 update_dictionary(d_index, d_hash, p_index, p_hash,
1490 k, class_loader_h, THREAD);
1491 }
1492 k->eager_initialize(THREAD);
1493
1494 // notify jvmti
1495 if (JvmtiExport::should_post_class_load()) {
1496 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1497 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1498
1499 }
1500
1501 }
1502
1503 // Support parallel classloading
1504 // All parallel class loaders, including bootstrap classloader
1505 // lock a placeholder entry for this class/class_loader pair
1506 // to allow parallel defines of different classes for this class loader
1507 // With AllowParallelDefine flag==true, in case they do not synchronize around
1508 // FindLoadedClass/DefineClass, calls, we check for parallel
1509 // loading for them, wait if a defineClass is in progress
1510 // and return the initial requestor's results
1511 // This flag does not apply to the bootstrap classloader.
1512 // With AllowParallelDefine flag==false, call through to define_instance_class
1513 // which will throw LinkageError: duplicate class definition.
1514 // False is the requested default.
1515 // For better performance, the class loaders should synchronize
1516 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1517 // potentially waste time reading and parsing the bytestream.
1518 // Note: VM callers should ensure consistency of k/class_name,class_loader
1519 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1520
1521 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1522 Symbol* name_h = k->name(); // passed in class_name may be null
1523 ClassLoaderData* loader_data = class_loader_data(class_loader);
1524
1525 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1526 int d_index = dictionary()->hash_to_index(d_hash);
1527
1528 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1529 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1530 int p_index = placeholders()->hash_to_index(p_hash);
1531 PlaceholderEntry* probe;
1532
1533 {
1534 MutexLocker mu(SystemDictionary_lock, THREAD);
1535 // First check if class already defined
1536 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1537 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1538 if (check != NULL) {
1539 return(instanceKlassHandle(THREAD, check));
1540 }
1541 }
1542
1543 // Acquire define token for this class/classloader
1544 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1545 // Wait if another thread defining in parallel
1546 // All threads wait - even those that will throw duplicate class: otherwise
1547 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1548 // if other thread has not finished updating dictionary
1549 while (probe->definer() != NULL) {
1550 SystemDictionary_lock->wait();
1551 }
1552 // Only special cases allow parallel defines and can use other thread's results
1553 // Other cases fall through, and may run into duplicate defines
1554 // caught by finding an entry in the SystemDictionary
1555 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1556 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1557 SystemDictionary_lock->notify_all();
1558 #ifdef ASSERT
1559 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1560 assert(check != NULL, "definer missed recording success");
1561 #endif
1562 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1563 } else {
1564 // This thread will define the class (even if earlier thread tried and had an error)
1565 probe->set_definer(THREAD);
1566 }
1567 }
1568
1569 define_instance_class(k, THREAD);
1570
1571 Handle linkage_exception = Handle(); // null handle
1572
1573 // definer must notify any waiting threads
1574 {
1575 MutexLocker mu(SystemDictionary_lock, THREAD);
1576 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1577 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1578 if (probe != NULL) {
1579 if (HAS_PENDING_EXCEPTION) {
1580 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1581 CLEAR_PENDING_EXCEPTION;
1582 } else {
1583 probe->set_instance_klass(k());
1584 }
1585 probe->set_definer(NULL);
1586 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1587 SystemDictionary_lock->notify_all();
1588 }
1589 }
1590
1591 // Can't throw exception while holding lock due to rank ordering
1592 if (linkage_exception() != NULL) {
1593 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1594 }
1595
1596 return k;
1597 }
1598 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1599 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1600 if (class_loader.is_null()) {
1601 return Handle(THREAD, _system_loader_lock_obj);
1602 } else {
1603 return class_loader;
1604 }
1605 }
1606
1607 // This method is added to check how often we have to wait to grab loader
1608 // lock. The results are being recorded in the performance counters defined in
1609 // ClassLoader::_sync_systemLoaderLockContentionRate and
1610 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1611 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1612 if (!UsePerfData) {
1613 return;
1614 }
1615
1616 assert(!loader_lock.is_null(), "NULL lock object");
1617
1618 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1619 == ObjectSynchronizer::owner_other) {
1620 // contention will likely happen, so increment the corresponding
1621 // contention counter.
1622 if (loader_lock() == _system_loader_lock_obj) {
1623 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1624 } else {
1625 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1626 }
1627 }
1628 }
1629
1630 // ----------------------------------------------------------------------------
1631 // Lookup
1632
1633 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1634 Symbol* class_name,
1635 ClassLoaderData* loader_data) {
1636 assert_locked_or_safepoint(SystemDictionary_lock);
1637 assert (index == dictionary()->index_for(class_name, loader_data),
1638 "incorrect index?");
1639
1640 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1641 return k;
1642 }
1643
1644
1645 // Basic find on classes in the midst of being loaded
1646 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1647 ClassLoaderData* loader_data) {
1648 assert_locked_or_safepoint(SystemDictionary_lock);
1649 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1650 int p_index = placeholders()->hash_to_index(p_hash);
1651 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1652 }
1653
1654
1655 // Used for assertions and verification only
1656 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1657 #ifndef ASSERT
1658 guarantee(VerifyBeforeGC ||
1659 VerifyDuringGC ||
1660 VerifyBeforeExit ||
1661 VerifyDuringStartup ||
1662 VerifyAfterGC, "too expensive");
1663 #endif
1664 assert_locked_or_safepoint(SystemDictionary_lock);
1665
1666 // First look in the loaded class array
1667 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1668 int d_index = dictionary()->hash_to_index(d_hash);
1669 return find_class(d_index, d_hash, class_name, loader_data);
1670 }
1671
1672
1673 // Get the next class in the diictionary.
1674 Klass* SystemDictionary::try_get_next_class() {
1675 return dictionary()->try_get_next_class();
1676 }
1677
1678
1679 // ----------------------------------------------------------------------------
1680 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1681 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1682 // before a new class is used.
1683
1684 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1685 assert(k.not_null(), "just checking");
1686 assert_locked_or_safepoint(Compile_lock);
1687
1688 // Link into hierachy. Make sure the vtables are initialized before linking into
1689 k->append_to_sibling_list(); // add to superklass/sibling list
1690 k->process_interfaces(THREAD); // handle all "implements" declarations
1691 k->set_init_state(InstanceKlass::loaded);
1692 // Now flush all code that depended on old class hierarchy.
1693 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1694 // Also, first reinitialize vtable because it may have gotten out of synch
1695 // while the new class wasn't connected to the class hierarchy.
1696 CodeCache::flush_dependents_on(k);
1697 }
1698
1699 // ----------------------------------------------------------------------------
1700 // GC support
1701
1702 // Following roots during mark-sweep is separated in two phases.
1703 //
1704 // The first phase follows preloaded classes and all other system
1705 // classes, since these will never get unloaded anyway.
1706 //
1707 // The second phase removes (unloads) unreachable classes from the
1708 // system dictionary and follows the remaining classes' contents.
1709
1710 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1711 roots_oops_do(blk, NULL);
1712 }
1713
1714 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1715 // Follow all system classes and temporary placeholders in dictionary
1716 dictionary()->always_strong_classes_do(closure);
1717
1718 // Placeholders. These represent classes we're actively loading.
1719 placeholders()->classes_do(closure);
1720 }
1721
1722 // Calculate a "good" systemdictionary size based
1723 // on predicted or current loaded classes count
1724 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1725 int newsize = _old_default_sdsize;
1726 if ((classcount > 0) && !DumpSharedSpaces) {
1727 int desiredsize = classcount/_average_depth_goal;
1728 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1729 newsize = _primelist[++_sdgeneration]) {
1730 if (desiredsize <= newsize) {
1731 break;
1732 }
1733 }
1734 }
1735 return newsize;
1736 }
1737
1738 #ifdef ASSERT
1739 class VerifySDReachableAndLiveClosure : public OopClosure {
1740 private:
1741 BoolObjectClosure* _is_alive;
1742
1743 template <class T> void do_oop_work(T* p) {
1744 oop obj = oopDesc::load_decode_heap_oop(p);
1745 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1746 }
1747
1748 public:
1749 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1750
1751 virtual void do_oop(oop* p) { do_oop_work(p); }
1752 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1753 };
1754 #endif
1755
1756 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1757 // Note: anonymous classes are not in the SD.
1758 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1759 bool clean_previous_versions) {
1760 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1761 bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1762 clean_previous_versions);
1763 if (unloading_occurred) {
1764 dictionary()->do_unloading();
1765 constraints()->purge_loader_constraints();
1766 resolution_errors()->purge_resolution_errors();
1767 }
1768 // Oops referenced by the system dictionary may get unreachable independently
1769 // of the class loader (eg. cached protection domain oops). So we need to
1770 // explicitly unlink them here instead of in Dictionary::do_unloading.
1771 dictionary()->unlink(is_alive);
1772 #ifdef ASSERT
1773 VerifySDReachableAndLiveClosure cl(is_alive);
1774 dictionary()->oops_do(&cl);
1775 #endif
1776 return unloading_occurred;
1777 }
1778
1779 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1780 strong->do_oop(&_java_system_loader);
1781 strong->do_oop(&_system_loader_lock_obj);
1782 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1783
1784 // Adjust dictionary
1785 dictionary()->roots_oops_do(strong, weak);
1786
1787 // Visit extra methods
1788 invoke_method_table()->oops_do(strong);
1789 }
1790
1791 void SystemDictionary::oops_do(OopClosure* f) {
1792 f->do_oop(&_java_system_loader);
1793 f->do_oop(&_system_loader_lock_obj);
1794 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1795
1796 // Adjust dictionary
1797 dictionary()->oops_do(f);
1798
1799 // Visit extra methods
1800 invoke_method_table()->oops_do(f);
1801 }
1802
1803 // Extended Class redefinition support.
1804 // If one of these classes is replaced, we need to replace it in these places.
1805 // KlassClosure::do_klass should take the address of a class but we can
1806 // change that later.
1807 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1808 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1809 f->do_klass(_well_known_klasses[k]);
1810 }
1811
1812 {
1813 for (int i = 0; i < T_VOID+1; i++) {
1814 if (_box_klasses[i] != NULL) {
1815 assert(i >= T_BOOLEAN, "checking");
1816 f->do_klass(_box_klasses[i]);
1817 }
1818 }
1819 }
1820
1821 FilteredFieldsMap::classes_do(f);
1822 }
1823
1824 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1825 f->do_klass(_abstract_ownable_synchronizer_klass);
1826 }
1827
1828 // Just the classes from defining class loaders
1829 // Don't iterate over placeholders
1830 void SystemDictionary::classes_do(void f(Klass*)) {
1831 dictionary()->classes_do(f);
1832 }
1833
1834 // Added for initialize_itable_for_klass
1835 // Just the classes from defining class loaders
1836 // Don't iterate over placeholders
1837 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1838 dictionary()->classes_do(f, CHECK);
1839 }
1840
1841 // All classes, and their class loaders
1842 // Don't iterate over placeholders
1843 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1844 dictionary()->classes_do(f);
1845 }
1846
1847 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1848 placeholders()->entries_do(f);
1849 }
1850
1851 void SystemDictionary::methods_do(void f(Method*)) {
1852 dictionary()->methods_do(f);
1853 invoke_method_table()->methods_do(f);
1854 }
1855
1856 void SystemDictionary::remove_classes_in_error_state() {
1857 dictionary()->remove_classes_in_error_state();
1858 }
1859
1860 // ----------------------------------------------------------------------------
1861 // Lazily load klasses
1862
1863 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1864 // if multiple threads calling this function, only one thread will load
1865 // the class. The other threads will find the loaded version once the
1866 // class is loaded.
1867 Klass* aos = _abstract_ownable_synchronizer_klass;
1868 if (aos == NULL) {
1869 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1870 // Force a fence to prevent any read before the write completes
1871 OrderAccess::fence();
1872 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1873 }
1874 }
1875
1876 // ----------------------------------------------------------------------------
1877 // Initialization
1878
1879 void SystemDictionary::initialize(TRAPS) {
1880 // Allocate arrays
1881 assert(dictionary() == NULL,
1882 "SystemDictionary should only be initialized once");
1883 _sdgeneration = 0;
1884 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1885 _placeholders = new PlaceholderTable(_nof_buckets);
1886 _number_of_modifications = 0;
1887 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1888 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1889 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1890
1891 // Allocate private object used as system class loader lock
1892 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1893 // Initialize basic classes
1894 initialize_preloaded_classes(CHECK);
1895 }
1896
1897 // Compact table of directions on the initialization of klasses:
1898 static const short wk_init_info[] = {
1899 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1900 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1901 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1902 | (int)SystemDictionary::option ),
1903 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1904 #undef WK_KLASS_INIT_INFO
1905 0
1906 };
1907
1908 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1909 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1910 int info = wk_init_info[id - FIRST_WKID];
1911 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1912 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1913 InstanceKlass** klassp = &_well_known_klasses[id];
1914 bool must_load = (init_opt < SystemDictionary::Opt);
1915 if ((*klassp) == NULL) {
1916 Klass* k;
1917 if (must_load) {
1918 k = resolve_or_fail(symbol, true, CHECK_0); // load required class
1919 } else {
1920 k = resolve_or_null(symbol, CHECK_0); // load optional klass
1921 }
1922 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
1923 }
1924 return ((*klassp) != NULL);
1925 }
1926
1927 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1928 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1929 for (int id = (int)start_id; id < (int)limit_id; id++) {
1930 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1931 int info = wk_init_info[id - FIRST_WKID];
1932 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1933 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1934
1935 initialize_wk_klass((WKID)id, opt, CHECK);
1936 }
1937
1938 // move the starting value forward to the limit:
1939 start_id = limit_id;
1940 }
1941
1942 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1943 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1944 // Preload commonly used klasses
1945 WKID scan = FIRST_WKID;
1946 // first do Object, then String, Class
1947 if (UseSharedSpaces) {
1948 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1949 // Initialize the constant pool for the Object_class
1950 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1951 ik->constants()->restore_unshareable_info(CHECK);
1952 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1953 } else {
1954 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1955 }
1956
1957 // Calculate offsets for String and Class classes since they are loaded and
1958 // can be used after this point.
1959 java_lang_String::compute_offsets();
1960 java_lang_Class::compute_offsets();
1961
1962 // Fixup mirrors for classes loaded before java.lang.Class.
1963 // These calls iterate over the objects currently in the perm gen
1964 // so calling them at this point is matters (not before when there
1965 // are fewer objects and not later after there are more objects
1966 // in the perm gen.
1967 Universe::initialize_basic_type_mirrors(CHECK);
1968 Universe::fixup_mirrors(CHECK);
1969
1970 // do a bunch more:
1971 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1972
1973 // Preload ref klasses and set reference types
1974 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1975 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1976
1977 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1978 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1979 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1980 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1981 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1982 InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
1983
1984 // JSR 292 classes
1985 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1986 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1987 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1988 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1989 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
1990
1991 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1992 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1993 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1994 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1995 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1996 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1997 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1998 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1999 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
2000 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
2001
2002 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2003 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2004 _has_loadClassInternal = (method != NULL);
2005 }
2006 { // Compute whether we should use checkPackageAccess or NOT
2007 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2008 _has_checkPackageAccess = (method != NULL);
2009 }
2010 }
2011
2012 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2013 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2014 BasicType SystemDictionary::box_klass_type(Klass* k) {
2015 assert(k != NULL, "");
2016 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2017 if (_box_klasses[i] == k)
2018 return (BasicType)i;
2019 }
2020 return T_OBJECT;
2021 }
2022
2023 // Constraints on class loaders. The details of the algorithm can be
2024 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2025 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2026 // that the system dictionary needs to maintain a set of contraints that
2027 // must be satisfied by all classes in the dictionary.
2028 // if defining is true, then LinkageError if already in systemDictionary
2029 // if initiating loader, then ok if InstanceKlass matches existing entry
2030
2031 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2032 instanceKlassHandle k,
2033 Handle class_loader, bool defining,
2034 TRAPS) {
2035 const char *linkage_error1 = NULL;
2036 const char *linkage_error2 = NULL;
2037 {
2038 Symbol* name = k->name();
2039 ClassLoaderData *loader_data = class_loader_data(class_loader);
2040
2041 MutexLocker mu(SystemDictionary_lock, THREAD);
2042
2043 Klass* check = find_class(d_index, d_hash, name, loader_data);
2044 if (check != (Klass*)NULL) {
2045 // if different InstanceKlass - duplicate class definition,
2046 // else - ok, class loaded by a different thread in parallel,
2047 // we should only have found it if it was done loading and ok to use
2048 // system dictionary only holds instance classes, placeholders
2049 // also holds array classes
2050
2051 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2052 if ((defining == true) || (k() != check)) {
2053 linkage_error1 = "loader (instance of ";
2054 linkage_error2 = "): attempted duplicate class definition for name: \"";
2055 } else {
2056 return;
2057 }
2058 }
2059
2060 #ifdef ASSERT
2061 Symbol* ph_check = find_placeholder(name, loader_data);
2062 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2063 #endif
2064
2065 if (linkage_error1 == NULL) {
2066 if (constraints()->check_or_update(k, class_loader, name) == false) {
2067 linkage_error1 = "loader constraint violation: loader (instance of ";
2068 linkage_error2 = ") previously initiated loading for a different type with name \"";
2069 }
2070 }
2071 }
2072
2073 // Throw error now if needed (cannot throw while holding
2074 // SystemDictionary_lock because of rank ordering)
2075
2076 if (linkage_error1) {
2077 ResourceMark rm(THREAD);
2078 const char* class_loader_name = loader_name(class_loader());
2079 char* type_name = k->name()->as_C_string();
2080 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2081 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2082 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2083 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2084 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2085 }
2086 }
2087
2088
2089 // Update system dictionary - done after check_constraint and add_to_hierachy
2090 // have been called.
2091 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2092 int p_index, unsigned int p_hash,
2093 instanceKlassHandle k,
2094 Handle class_loader,
2095 TRAPS) {
2096 // Compile_lock prevents systemDictionary updates during compilations
2097 assert_locked_or_safepoint(Compile_lock);
2098 Symbol* name = k->name();
2099 ClassLoaderData *loader_data = class_loader_data(class_loader);
2100
2101 {
2102 MutexLocker mu1(SystemDictionary_lock, THREAD);
2103
2104 // See whether biased locking is enabled and if so set it for this
2105 // klass.
2106 // Note that this must be done past the last potential blocking
2107 // point / safepoint. We enable biased locking lazily using a
2108 // VM_Operation to iterate the SystemDictionary and installing the
2109 // biasable mark word into each InstanceKlass's prototype header.
2110 // To avoid race conditions where we accidentally miss enabling the
2111 // optimization for one class in the process of being added to the
2112 // dictionary, we must not safepoint after the test of
2113 // BiasedLocking::enabled().
2114 if (UseBiasedLocking && BiasedLocking::enabled()) {
2115 // Set biased locking bit for all loaded classes; it will be
2116 // cleared if revocation occurs too often for this type
2117 // NOTE that we must only do this when the class is initally
2118 // defined, not each time it is referenced from a new class loader
2119 if (k->class_loader() == class_loader()) {
2120 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2121 }
2122 }
2123
2124 // Make a new system dictionary entry.
2125 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2126 if (sd_check == NULL) {
2127 dictionary()->add_klass(name, loader_data, k);
2128 notice_modification();
2129 }
2130 #ifdef ASSERT
2131 sd_check = find_class(d_index, d_hash, name, loader_data);
2132 assert (sd_check != NULL, "should have entry in system dictionary");
2133 // Note: there may be a placeholder entry: for circularity testing
2134 // or for parallel defines
2135 #endif
2136 SystemDictionary_lock->notify_all();
2137 }
2138 }
2139
2140
2141 // Try to find a class name using the loader constraints. The
2142 // loader constraints might know about a class that isn't fully loaded
2143 // yet and these will be ignored.
2144 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2145 Symbol* class_name, Handle class_loader, TRAPS) {
2146
2147 // First see if it has been loaded directly.
2148 // Force the protection domain to be null. (This removes protection checks.)
2149 Handle no_protection_domain;
2150 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2151 no_protection_domain, CHECK_NULL);
2152 if (klass != NULL)
2153 return klass;
2154
2155 // Now look to see if it has been loaded elsewhere, and is subject to
2156 // a loader constraint that would require this loader to return the
2157 // klass that is already loaded.
2158 if (FieldType::is_array(class_name)) {
2159 // For array classes, their Klass*s are not kept in the
2160 // constraint table. The element Klass*s are.
2161 FieldArrayInfo fd;
2162 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2163 if (t != T_OBJECT) {
2164 klass = Universe::typeArrayKlassObj(t);
2165 } else {
2166 MutexLocker mu(SystemDictionary_lock, THREAD);
2167 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2168 }
2169 // If element class already loaded, allocate array klass
2170 if (klass != NULL) {
2171 klass = klass->array_klass_or_null(fd.dimension());
2172 }
2173 } else {
2174 MutexLocker mu(SystemDictionary_lock, THREAD);
2175 // Non-array classes are easy: simply check the constraint table.
2176 klass = constraints()->find_constrained_klass(class_name, class_loader);
2177 }
2178
2179 return klass;
2180 }
2181
2182
2183 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2184 Handle class_loader1,
2185 Handle class_loader2,
2186 Thread* THREAD) {
2187 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2188 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2189
2190 Symbol* constraint_name = NULL;
2191 if (!FieldType::is_array(class_name)) {
2192 constraint_name = class_name;
2193 } else {
2194 // For array classes, their Klass*s are not kept in the
2195 // constraint table. The element classes are.
2196 FieldArrayInfo fd;
2197 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2198 // primitive types always pass
2199 if (t != T_OBJECT) {
2200 return true;
2201 } else {
2202 constraint_name = fd.object_key();
2203 }
2204 }
2205 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2206 int d_index1 = dictionary()->hash_to_index(d_hash1);
2207
2208 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2209 int d_index2 = dictionary()->hash_to_index(d_hash2);
2210 {
2211 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2212
2213 // Better never do a GC while we're holding these oops
2214 No_Safepoint_Verifier nosafepoint;
2215
2216 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2217 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2218 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2219 klass2, class_loader2);
2220 }
2221 }
2222
2223 // Add entry to resolution error table to record the error when the first
2224 // attempt to resolve a reference to a class has failed.
2225 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2226 Symbol* error, Symbol* message) {
2227 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2228 int index = resolution_errors()->hash_to_index(hash);
2229 {
2230 MutexLocker ml(SystemDictionary_lock, Thread::current());
2231 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2232 }
2233 }
2234
2235 // Delete a resolution error for RedefineClasses for a constant pool is going away
2236 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2237 resolution_errors()->delete_entry(pool);
2238 }
2239
2240 // Lookup resolution error table. Returns error if found, otherwise NULL.
2241 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2242 Symbol** message) {
2243 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2244 int index = resolution_errors()->hash_to_index(hash);
2245 {
2246 MutexLocker ml(SystemDictionary_lock, Thread::current());
2247 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2248 if (entry != NULL) {
2249 *message = entry->message();
2250 return entry->error();
2251 } else {
2252 return NULL;
2253 }
2254 }
2255 }
2256
2257
2258 // Signature constraints ensure that callers and callees agree about
2259 // the meaning of type names in their signatures. This routine is the
2260 // intake for constraints. It collects them from several places:
2261 //
2262 // * LinkResolver::resolve_method (if check_access is true) requires
2263 // that the resolving class (the caller) and the defining class of
2264 // the resolved method (the callee) agree on each type in the
2265 // method's signature.
2266 //
2267 // * LinkResolver::resolve_interface_method performs exactly the same
2268 // checks.
2269 //
2270 // * LinkResolver::resolve_field requires that the constant pool
2271 // attempting to link to a field agree with the field's defining
2272 // class about the type of the field signature.
2273 //
2274 // * klassVtable::initialize_vtable requires that, when a class
2275 // overrides a vtable entry allocated by a superclass, that the
2276 // overriding method (i.e., the callee) agree with the superclass
2277 // on each type in the method's signature.
2278 //
2279 // * klassItable::initialize_itable requires that, when a class fills
2280 // in its itables, for each non-abstract method installed in an
2281 // itable, the method (i.e., the callee) agree with the interface
2282 // on each type in the method's signature.
2283 //
2284 // All those methods have a boolean (check_access, checkconstraints)
2285 // which turns off the checks. This is used from specialized contexts
2286 // such as bootstrapping, dumping, and debugging.
2287 //
2288 // No direct constraint is placed between the class and its
2289 // supertypes. Constraints are only placed along linked relations
2290 // between callers and callees. When a method overrides or implements
2291 // an abstract method in a supertype (superclass or interface), the
2292 // constraints are placed as if the supertype were the caller to the
2293 // overriding method. (This works well, since callers to the
2294 // supertype have already established agreement between themselves and
2295 // the supertype.) As a result of all this, a class can disagree with
2296 // its supertype about the meaning of a type name, as long as that
2297 // class neither calls a relevant method of the supertype, nor is
2298 // called (perhaps via an override) from the supertype.
2299 //
2300 //
2301 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2302 //
2303 // Make sure all class components (including arrays) in the given
2304 // signature will be resolved to the same class in both loaders.
2305 // Returns the name of the type that failed a loader constraint check, or
2306 // NULL if no constraint failed. No exception except OOME is thrown.
2307 // Arrays are not added to the loader constraint table, their elements are.
2308 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2309 Handle loader1, Handle loader2,
2310 bool is_method, TRAPS) {
2311 // Nothing to do if loaders are the same.
2312 if (loader1() == loader2()) {
2313 return NULL;
2314 }
2315
2316 SignatureStream sig_strm(signature, is_method);
2317 while (!sig_strm.is_done()) {
2318 if (sig_strm.is_object()) {
2319 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2320 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2321 return sig;
2322 }
2323 }
2324 sig_strm.next();
2325 }
2326 return NULL;
2327 }
2328
2329
2330 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2331 Symbol* signature,
2332 TRAPS) {
2333 methodHandle empty;
2334 assert(MethodHandles::is_signature_polymorphic(iid) &&
2335 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2336 iid != vmIntrinsics::_invokeGeneric,
2337 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2338
2339 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2340 int index = invoke_method_table()->hash_to_index(hash);
2341 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2342 methodHandle m;
2343 if (spe == NULL || spe->method() == NULL) {
2344 spe = NULL;
2345 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2346 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2347 if (!Arguments::is_interpreter_only()) {
2348 // Generate a compiled form of the MH intrinsic.
2349 AdapterHandlerLibrary::create_native_wrapper(m);
2350 // Check if have the compiled code.
2351 if (!m->has_compiled_code()) {
2352 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2353 "Out of space in CodeCache for method handle intrinsic", empty);
2354 }
2355 }
2356 // Now grab the lock. We might have to throw away the new method,
2357 // if a racing thread has managed to install one at the same time.
2358 {
2359 MutexLocker ml(SystemDictionary_lock, THREAD);
2360 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2361 if (spe == NULL)
2362 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2363 if (spe->method() == NULL)
2364 spe->set_method(m());
2365 }
2366 }
2367
2368 assert(spe != NULL && spe->method() != NULL, "");
2369 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2370 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2371 "MH intrinsic invariant");
2372 return spe->method();
2373 }
2374
2375 // Helper for unpacking the return value from linkMethod and linkCallSite.
2376 static methodHandle unpack_method_and_appendix(Handle mname,
2377 KlassHandle accessing_klass,
2378 objArrayHandle appendix_box,
2379 Handle* appendix_result,
2380 TRAPS) {
2381 methodHandle empty;
2382 if (mname.not_null()) {
2383 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2384 if (vmtarget != NULL && vmtarget->is_method()) {
2385 Method* m = (Method*)vmtarget;
2386 oop appendix = appendix_box->obj_at(0);
2387 if (TraceMethodHandles) {
2388 #ifndef PRODUCT
2389 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2390 m->print();
2391 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2392 tty->cr();
2393 #endif //PRODUCT
2394 }
2395 (*appendix_result) = Handle(THREAD, appendix);
2396 // the target is stored in the cpCache and if a reference to this
2397 // MethodName is dropped we need a way to make sure the
2398 // class_loader containing this method is kept alive.
2399 // FIXME: the appendix might also preserve this dependency.
2400 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2401 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2402 return methodHandle(THREAD, m);
2403 }
2404 }
2405 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2406 return empty;
2407 }
2408
2409 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2410 Symbol* signature,
2411 KlassHandle accessing_klass,
2412 Handle *appendix_result,
2413 Handle *method_type_result,
2414 TRAPS) {
2415 methodHandle empty;
2416 assert(THREAD->can_call_java() ,"");
2417 Handle method_type =
2418 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2419
2420 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2421 int ref_kind = JVM_REF_invokeVirtual;
2422 Handle name_str = StringTable::intern(name, CHECK_(empty));
2423 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2424 assert(appendix_box->obj_at(0) == NULL, "");
2425
2426 // This should not happen. JDK code should take care of that.
2427 if (accessing_klass.is_null() || method_type.is_null()) {
2428 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2429 }
2430
2431 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2432 JavaCallArguments args;
2433 args.push_oop(accessing_klass()->java_mirror());
2434 args.push_int(ref_kind);
2435 args.push_oop(mh_klass()->java_mirror());
2436 args.push_oop(name_str());
2437 args.push_oop(method_type());
2438 args.push_oop(appendix_box());
2439 JavaValue result(T_OBJECT);
2440 JavaCalls::call_static(&result,
2441 SystemDictionary::MethodHandleNatives_klass(),
2442 vmSymbols::linkMethod_name(),
2443 vmSymbols::linkMethod_signature(),
2444 &args, CHECK_(empty));
2445 Handle mname(THREAD, (oop) result.get_jobject());
2446 (*method_type_result) = method_type;
2447 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2448 }
2449
2450 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2451 // We must ensure that all class loaders everywhere will reach this class, for any client.
2452 // This is a safe bet for public classes in java.lang, such as Object and String.
2453 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2454 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2455 static bool is_always_visible_class(oop mirror) {
2456 Klass* klass = java_lang_Class::as_Klass(mirror);
2457 if (klass->is_objArray_klass()) {
2458 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2459 }
2460 if (klass->is_typeArray_klass()) {
2461 return true; // primitive array
2462 }
2463 assert(klass->is_instance_klass(), "%s", klass->external_name());
2464 return klass->is_public() &&
2465 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2466 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2467 }
2468
2469 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2470 // signature, as interpreted relative to the given class loader.
2471 // Because of class loader constraints, all method handle usage must be
2472 // consistent with this loader.
2473 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2474 KlassHandle accessing_klass,
2475 TRAPS) {
2476 Handle empty;
2477 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2478 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2479 int index = invoke_method_table()->hash_to_index(hash);
2480 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2481 if (spe != NULL && spe->method_type() != NULL) {
2482 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2483 return Handle(THREAD, spe->method_type());
2484 } else if (!THREAD->can_call_java()) {
2485 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2486 return Handle(); // do not attempt from within compiler, unless it was cached
2487 }
2488
2489 Handle class_loader, protection_domain;
2490 if (accessing_klass.not_null()) {
2491 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2492 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2493 }
2494 bool can_be_cached = true;
2495 int npts = ArgumentCount(signature).size();
2496 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2497 int arg = 0;
2498 Handle rt; // the return type from the signature
2499 ResourceMark rm(THREAD);
2500 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2501 oop mirror = NULL;
2502 if (can_be_cached) {
2503 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2504 mirror = ss.as_java_mirror(Handle(), Handle(),
2505 SignatureStream::ReturnNull, CHECK_(empty));
2506 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2507 // Fall back to accessing_klass context.
2508 can_be_cached = false;
2509 }
2510 }
2511 if (!can_be_cached) {
2512 // Resolve, throwing a real error if it doesn't work.
2513 mirror = ss.as_java_mirror(class_loader, protection_domain,
2514 SignatureStream::NCDFError, CHECK_(empty));
2515 }
2516 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2517 if (ss.at_return_type())
2518 rt = Handle(THREAD, mirror);
2519 else
2520 pts->obj_at_put(arg++, mirror);
2521
2522 // Check accessibility.
2523 if (ss.is_object() && accessing_klass.not_null()) {
2524 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2525 mirror = NULL; // safety
2526 // Emulate ConstantPool::verify_constant_pool_resolve.
2527 if (sel_klass->is_objArray_klass())
2528 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2529 if (sel_klass->is_instance_klass()) {
2530 KlassHandle sel_kh(THREAD, sel_klass);
2531 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2532 }
2533 }
2534 }
2535 assert(arg == npts, "");
2536
2537 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2538 JavaCallArguments args(Handle(THREAD, rt()));
2539 args.push_oop(pts());
2540 JavaValue result(T_OBJECT);
2541 JavaCalls::call_static(&result,
2542 SystemDictionary::MethodHandleNatives_klass(),
2543 vmSymbols::findMethodHandleType_name(),
2544 vmSymbols::findMethodHandleType_signature(),
2545 &args, CHECK_(empty));
2546 Handle method_type(THREAD, (oop) result.get_jobject());
2547
2548 if (can_be_cached) {
2549 // We can cache this MethodType inside the JVM.
2550 MutexLocker ml(SystemDictionary_lock, THREAD);
2551 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2552 if (spe == NULL)
2553 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2554 if (spe->method_type() == NULL) {
2555 spe->set_method_type(method_type());
2556 }
2557 }
2558
2559 // report back to the caller with the MethodType
2560 return method_type;
2561 }
2562
2563 // Ask Java code to find or construct a method handle constant.
2564 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2565 int ref_kind, //e.g., JVM_REF_invokeVirtual
2566 KlassHandle callee,
2567 Symbol* name_sym,
2568 Symbol* signature,
2569 TRAPS) {
2570 Handle empty;
2571 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2572 Handle type;
2573 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2574 type = find_method_handle_type(signature, caller, CHECK_(empty));
2575 } else if (caller.is_null()) {
2576 // This should not happen. JDK code should take care of that.
2577 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2578 } else {
2579 ResourceMark rm(THREAD);
2580 SignatureStream ss(signature, false);
2581 if (!ss.is_done()) {
2582 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2583 SignatureStream::NCDFError, CHECK_(empty));
2584 type = Handle(THREAD, mirror);
2585 ss.next();
2586 if (!ss.is_done()) type = Handle(); // error!
2587 }
2588 }
2589 if (type.is_null()) {
2590 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2591 }
2592
2593 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2594 JavaCallArguments args;
2595 args.push_oop(caller->java_mirror()); // the referring class
2596 args.push_int(ref_kind);
2597 args.push_oop(callee->java_mirror()); // the target class
2598 args.push_oop(name());
2599 args.push_oop(type());
2600 JavaValue result(T_OBJECT);
2601 JavaCalls::call_static(&result,
2602 SystemDictionary::MethodHandleNatives_klass(),
2603 vmSymbols::linkMethodHandleConstant_name(),
2604 vmSymbols::linkMethodHandleConstant_signature(),
2605 &args, CHECK_(empty));
2606 return Handle(THREAD, (oop) result.get_jobject());
2607 }
2608
2609 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2610 // name and signature, as interpreted relative to the given class loader.
2611 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2612 Handle bootstrap_specifier,
2613 Symbol* name,
2614 Symbol* type,
2615 Handle *appendix_result,
2616 Handle *method_type_result,
2617 TRAPS) {
2618 methodHandle empty;
2619 Handle bsm, info;
2620 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2621 bsm = bootstrap_specifier;
2622 } else {
2623 assert(bootstrap_specifier->is_objArray(), "");
2624 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2625 int len = args->length();
2626 assert(len >= 1, "");
2627 bsm = Handle(THREAD, args->obj_at(0));
2628 if (len > 1) {
2629 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2630 for (int i = 1; i < len; i++)
2631 args1->obj_at_put(i-1, args->obj_at(i));
2632 info = Handle(THREAD, args1);
2633 }
2634 }
2635 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2636 "caller must supply a valid BSM");
2637
2638 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2639 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2640
2641 // This should not happen. JDK code should take care of that.
2642 if (caller.is_null() || method_type.is_null()) {
2643 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2644 }
2645
2646 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2647 assert(appendix_box->obj_at(0) == NULL, "");
2648
2649 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2650 JavaCallArguments args;
2651 args.push_oop(caller->java_mirror());
2652 args.push_oop(bsm());
2653 args.push_oop(method_name());
2654 args.push_oop(method_type());
2655 args.push_oop(info());
2656 args.push_oop(appendix_box);
2657 JavaValue result(T_OBJECT);
2658 JavaCalls::call_static(&result,
2659 SystemDictionary::MethodHandleNatives_klass(),
2660 vmSymbols::linkCallSite_name(),
2661 vmSymbols::linkCallSite_signature(),
2662 &args, CHECK_(empty));
2663 Handle mname(THREAD, (oop) result.get_jobject());
2664 (*method_type_result) = method_type;
2665 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2666 }
2667
2668 // Since the identity hash code for symbols changes when the symbols are
2669 // moved from the regular perm gen (hash in the mark word) to the shared
2670 // spaces (hash is the address), the classes loaded into the dictionary
2671 // may be in the wrong buckets.
2672
2673 void SystemDictionary::reorder_dictionary() {
2674 dictionary()->reorder_dictionary();
2675 }
2676
2677
2678 void SystemDictionary::copy_buckets(char** top, char* end) {
2679 dictionary()->copy_buckets(top, end);
2680 }
2681
2682
2683 void SystemDictionary::copy_table(char** top, char* end) {
2684 dictionary()->copy_table(top, end);
2685 }
2686
2687
2688 void SystemDictionary::reverse() {
2689 dictionary()->reverse();
2690 }
2691
2692 int SystemDictionary::number_of_classes() {
2693 return dictionary()->number_of_entries();
2694 }
2695
2696
2697 // ----------------------------------------------------------------------------
2698 void SystemDictionary::print_shared(bool details) {
2699 shared_dictionary()->print(details);
2700 }
2701
2702 void SystemDictionary::print(bool details) {
2703 dictionary()->print(details);
2704
2705 // Placeholders
2706 GCMutexLocker mu(SystemDictionary_lock);
2707 placeholders()->print();
2708
2709 // loader constraints - print under SD_lock
2710 constraints()->print();
2711 }
2712
2713
2714 void SystemDictionary::verify() {
2715 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2716 guarantee(constraints() != NULL,
2717 "Verify of loader constraints failed");
2718 guarantee(dictionary()->number_of_entries() >= 0 &&
2719 placeholders()->number_of_entries() >= 0,
2720 "Verify of system dictionary failed");
2721
2722 // Verify dictionary
2723 dictionary()->verify();
2724
2725 GCMutexLocker mu(SystemDictionary_lock);
2726 placeholders()->verify();
2727
2728 // Verify constraint table
2729 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2730 constraints()->verify(dictionary(), placeholders());
2731 }
2732
2733 // caller needs ResourceMark
2734 const char* SystemDictionary::loader_name(const oop loader) {
2735 return ((loader) == NULL ? "<bootloader>" :
2736 InstanceKlass::cast((loader)->klass())->name()->as_C_string());
2737 }
2738
2739 // caller needs ResourceMark
2740 const char* SystemDictionary::loader_name(const ClassLoaderData* loader_data) {
2741 return (loader_data->class_loader() == NULL ? "<bootloader>" :
2742 InstanceKlass::cast((loader_data->class_loader())->klass())->name()->as_C_string());
2743 }