1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "jvm.h"
  27 #include "aot/aotLoader.hpp"
  28 #include "classfile/classFileParser.hpp"
  29 #include "classfile/classFileStream.hpp"
  30 #include "classfile/classLoader.hpp"
  31 #include "classfile/classLoaderData.inline.hpp"
  32 #include "classfile/classLoaderDataGraph.inline.hpp"
  33 #include "classfile/classLoaderExt.hpp"
  34 #include "classfile/dictionary.hpp"
  35 #include "classfile/javaClasses.inline.hpp"
  36 #include "classfile/klassFactory.hpp"
  37 #include "classfile/loaderConstraints.hpp"
  38 #include "classfile/packageEntry.hpp"
  39 #include "classfile/placeholders.hpp"
  40 #include "classfile/protectionDomainCache.hpp"
  41 #include "classfile/resolutionErrors.hpp"
  42 #include "classfile/stringTable.hpp"
  43 #include "classfile/systemDictionary.hpp"
  44 #include "classfile/vmSymbols.hpp"
  45 #include "code/codeCache.hpp"
  46 #include "compiler/compileBroker.hpp"
  47 #include "gc/shared/gcTraceTime.inline.hpp"
  48 #include "gc/shared/oopStorage.inline.hpp"
  49 #include "interpreter/bytecodeStream.hpp"
  50 #include "interpreter/interpreter.hpp"
  51 #include "jfr/jfrEvents.hpp"
  52 #include "logging/log.hpp"
  53 #include "logging/logStream.hpp"
  54 #include "memory/filemap.hpp"
  55 #include "memory/heapShared.hpp"
  56 #include "memory/metaspaceClosure.hpp"
  57 #include "memory/oopFactory.hpp"
  58 #include "memory/resourceArea.hpp"
  59 #include "oops/access.inline.hpp"
  60 #include "oops/instanceKlass.hpp"
  61 #include "oops/instanceRefKlass.hpp"
  62 #include "oops/klass.inline.hpp"
  63 #include "oops/method.inline.hpp"
  64 #include "oops/methodData.hpp"
  65 #include "oops/objArrayKlass.hpp"
  66 #include "oops/objArrayOop.inline.hpp"
  67 #include "oops/oop.inline.hpp"
  68 #include "oops/symbol.hpp"
  69 #include "oops/typeArrayKlass.hpp"
  70 #include "prims/jvmtiEnvBase.hpp"
  71 #include "prims/resolvedMethodTable.hpp"
  72 #include "prims/methodHandles.hpp"
  73 #include "runtime/arguments.hpp"
  74 #include "runtime/arguments_ext.hpp"
  75 #include "runtime/biasedLocking.hpp"
  76 #include "runtime/fieldType.hpp"
  77 #include "runtime/handles.inline.hpp"
  78 #include "runtime/java.hpp"
  79 #include "runtime/javaCalls.hpp"
  80 #include "runtime/mutexLocker.hpp"
  81 #include "runtime/orderAccess.hpp"
  82 #include "runtime/sharedRuntime.hpp"
  83 #include "runtime/signature.hpp"
  84 #include "services/classLoadingService.hpp"
  85 #include "services/diagnosticCommand.hpp"
  86 #include "services/threadService.hpp"
  87 #include "utilities/macros.hpp"
  88 #if INCLUDE_CDS
  89 #include "classfile/systemDictionaryShared.hpp"
  90 #endif
  91 #if INCLUDE_JVMCI
  92 #include "jvmci/jvmciRuntime.hpp"
  93 #endif
  94 #if INCLUDE_JFR
  95 #include "jfr/jfr.hpp"
  96 #endif
  97 
  98 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  99 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
 100 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
 101 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
 102 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
 103 ProtectionDomainCacheTable*   SystemDictionary::_pd_cache_table = NULL;
 104 
 105 int         SystemDictionary::_number_of_modifications = 0;
 106 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 107 
 108 InstanceKlass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
 109                                                           =  { NULL /*, NULL...*/ };
 110 
 111 InstanceKlass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
 112 
 113 oop         SystemDictionary::_java_system_loader         =  NULL;
 114 oop         SystemDictionary::_java_platform_loader       =  NULL;
 115 
 116 bool        SystemDictionary::_has_checkPackageAccess     =  false;
 117 
 118 // Default ProtectionDomainCacheSize value
 119 
 120 const int defaultProtectionDomainCacheSize = 1009;
 121 
 122 OopStorage* SystemDictionary::_vm_weak_oop_storage = NULL;
 123 
 124 
 125 // ----------------------------------------------------------------------------
 126 // Java-level SystemLoader and PlatformLoader
 127 
 128 oop SystemDictionary::java_system_loader() {
 129   return _java_system_loader;
 130 }
 131 
 132 oop SystemDictionary::java_platform_loader() {
 133   return _java_platform_loader;
 134 }
 135 
 136 void SystemDictionary::compute_java_loaders(TRAPS) {
 137   JavaValue result(T_OBJECT);
 138   InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
 139   JavaCalls::call_static(&result,
 140                          class_loader_klass,
 141                          vmSymbols::getSystemClassLoader_name(),
 142                          vmSymbols::void_classloader_signature(),
 143                          CHECK);
 144 
 145   _java_system_loader = (oop)result.get_jobject();
 146 
 147   JavaCalls::call_static(&result,
 148                          class_loader_klass,
 149                          vmSymbols::getPlatformClassLoader_name(),
 150                          vmSymbols::void_classloader_signature(),
 151                          CHECK);
 152 
 153   _java_platform_loader = (oop)result.get_jobject();
 154 }
 155 
 156 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
 157   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 158   return ClassLoaderDataGraph::find_or_create(class_loader);
 159 }
 160 
 161 // ----------------------------------------------------------------------------
 162 // Parallel class loading check
 163 
 164 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 165   if (class_loader.is_null()) return true;
 166   if (AlwaysLockClassLoader) return false;
 167   return java_lang_ClassLoader::parallelCapable(class_loader());
 168 }
 169 // ----------------------------------------------------------------------------
 170 // ParallelDefineClass flag does not apply to bootclass loader
 171 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 172    if (class_loader.is_null()) return false;
 173    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 174      return true;
 175    }
 176    return false;
 177 }
 178 
 179 // Returns true if the passed class loader is the builtin application class loader
 180 // or a custom system class loader. A customer system class loader can be
 181 // specified via -Djava.system.class.loader.
 182 bool SystemDictionary::is_system_class_loader(oop class_loader) {
 183   if (class_loader == NULL) {
 184     return false;
 185   }
 186   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
 187          oopDesc::equals(class_loader, _java_system_loader));
 188 }
 189 
 190 // Returns true if the passed class loader is the platform class loader.
 191 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
 192   if (class_loader == NULL) {
 193     return false;
 194   }
 195   return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
 196 }
 197 
 198 // ----------------------------------------------------------------------------
 199 // Resolving of classes
 200 
 201 // Forwards to resolve_or_null
 202 
 203 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 204   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 205   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 206     // can return a null klass
 207     klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
 208   }
 209   return klass;
 210 }
 211 
 212 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
 213                                                      bool throw_error,
 214                                                      Klass* klass, TRAPS) {
 215   if (HAS_PENDING_EXCEPTION) {
 216     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 217     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 218     // and if so convert it to a NoClassDefFoundError
 219     // And chain the original ClassNotFoundException
 220     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 221       ResourceMark rm(THREAD);
 222       assert(klass == NULL, "Should not have result with exception pending");
 223       Handle e(THREAD, PENDING_EXCEPTION);
 224       CLEAR_PENDING_EXCEPTION;
 225       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 226     } else {
 227       return NULL;
 228     }
 229   }
 230   // Class not found, throw appropriate error or exception depending on value of throw_error
 231   if (klass == NULL) {
 232     ResourceMark rm(THREAD);
 233     if (throw_error) {
 234       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 235     } else {
 236       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 237     }
 238   }
 239   return klass;
 240 }
 241 
 242 
 243 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 244                                            bool throw_error, TRAPS)
 245 {
 246   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 247 }
 248 
 249 
 250 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
 251 
 252 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 253   if (FieldType::is_array(class_name)) {
 254     return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
 255   } else {
 256     return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
 257   }
 258 }
 259 
 260 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
 261 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
 262                                                                        Handle class_loader,
 263                                                                        Handle protection_domain,
 264                                                                        TRAPS) {
 265   assert(class_name != NULL && !FieldType::is_array(class_name), "must be");
 266   if (FieldType::is_obj(class_name)) {
 267     ResourceMark rm(THREAD);
 268     // Ignore wrapping L and ;.
 269     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 270                                    class_name->utf8_length() - 2, CHECK_NULL);
 271     return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
 272   } else {
 273     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
 274   }
 275 }
 276 
 277 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 278   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 279 }
 280 
 281 // Forwards to resolve_instance_class_or_null
 282 
 283 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 284                                                      Handle class_loader,
 285                                                      Handle protection_domain,
 286                                                      TRAPS) {
 287   assert(FieldType::is_array(class_name), "must be array");
 288   Klass* k = NULL;
 289   FieldArrayInfo fd;
 290   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 291   // of this call
 292   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 293   if (t == T_OBJECT) {
 294     // naked oop "k" is OK here -- we assign back into it
 295     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 296                                                          class_loader,
 297                                                          protection_domain,
 298                                                          CHECK_NULL);
 299     if (k != NULL) {
 300       k = k->array_klass(fd.dimension(), CHECK_NULL);
 301     }
 302   } else {
 303     k = Universe::typeArrayKlassObj(t);
 304     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 305   }
 306   return k;
 307 }
 308 
 309 
 310 // Must be called for any super-class or super-interface resolution
 311 // during class definition to allow class circularity checking
 312 // super-interface callers:
 313 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 314 // super-class callers:
 315 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 316 //   load_shared_class - while loading a class from shared archive
 317 //   resolve_instance_class_or_null:
 318 //     via: handle_parallel_super_load
 319 //      when resolving a class that has an existing placeholder with
 320 //      a saved superclass [i.e. a defineClass is currently in progress]
 321 //      if another thread is trying to resolve the class, it must do
 322 //      super-class checks on its own thread to catch class circularity
 323 // This last call is critical in class circularity checking for cases
 324 // where classloading is delegated to different threads and the
 325 // classloader lock is released.
 326 // Take the case: Base->Super->Base
 327 //   1. If thread T1 tries to do a defineClass of class Base
 328 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 329 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 330 //    so it tries to load Super
 331 //   3. If we load the class internally, or user classloader uses same thread
 332 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 333 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 334 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 335 //      3.4 calls resolve_super_or_fail Base
 336 //      3.5 finds T1,Base -> throws class circularity
 337 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 338 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 339 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 340 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 341 //      4.4 finds T2, Super -> throws class circularity
 342 // Must be called, even if superclass is null, since this is
 343 // where the placeholder entry is created which claims this
 344 // thread is loading this class/classloader.
 345 // Be careful when modifying this code: once you have run
 346 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
 347 // you need to find_and_remove it before returning.
 348 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 349 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 350                                                        Symbol* super_name,
 351                                                        Handle class_loader,
 352                                                        Handle protection_domain,
 353                                                        bool is_superclass,
 354                                                        TRAPS) {
 355   assert(!FieldType::is_array(super_name), "invalid super class name");
 356 #if INCLUDE_CDS
 357   if (DumpSharedSpaces) {
 358     // Special processing for CDS dump time.
 359     InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
 360         super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
 361     if (k) {
 362       return k;
 363     }
 364   }
 365 #endif // INCLUDE_CDS
 366 
 367   // Double-check, if child class is already loaded, just return super-class,interface
 368   // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
 369   // dictionary.
 370   // Make sure there's a placeholder for the *child* before resolving.
 371   // Used as a claim that this thread is currently loading superclass/classloader
 372   // Used here for ClassCircularity checks and also for heap verification
 373   // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
 374   // Must check ClassCircularity before checking if super class is already loaded.
 375   //
 376   // We might not already have a placeholder if this child_name was
 377   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 378   // the name of the class might not be known until the stream is actually
 379   // parsed.
 380   // Bugs 4643874, 4715493
 381 
 382   ClassLoaderData* loader_data = class_loader_data(class_loader);
 383   Dictionary* dictionary = loader_data->dictionary();
 384   unsigned int d_hash = dictionary->compute_hash(child_name);
 385   unsigned int p_hash = placeholders()->compute_hash(child_name);
 386   int p_index = placeholders()->hash_to_index(p_hash);
 387   // can't throw error holding a lock
 388   bool child_already_loaded = false;
 389   bool throw_circularity_error = false;
 390   {
 391     MutexLocker mu(SystemDictionary_lock, THREAD);
 392     InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
 393     InstanceKlass* quicksuperk;
 394     // to support // loading: if child done loading, just return superclass
 395     // if super_name, & class_loader don't match:
 396     // if initial define, SD update will give LinkageError
 397     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 398     // so we don't throw an exception here.
 399     // see: nsk redefclass014 & java.lang.instrument Instrument032
 400     if ((childk != NULL ) && (is_superclass) &&
 401         ((quicksuperk = childk->java_super()) != NULL) &&
 402          ((quicksuperk->name() == super_name) &&
 403             (oopDesc::equals(quicksuperk->class_loader(), class_loader())))) {
 404            return quicksuperk;
 405     } else {
 406       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 407       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 408           throw_circularity_error = true;
 409       }
 410     }
 411     if (!throw_circularity_error) {
 412       // Be careful not to exit resolve_super
 413       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
 414     }
 415   }
 416   if (throw_circularity_error) {
 417       ResourceMark rm(THREAD);
 418       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 419   }
 420 
 421 // java.lang.Object should have been found above
 422   assert(super_name != NULL, "null super class for resolving");
 423   // Resolve the super class or interface, check results on return
 424   InstanceKlass* superk =
 425     SystemDictionary::resolve_instance_class_or_null_helper(super_name,
 426                                                             class_loader,
 427                                                             protection_domain,
 428                                                             THREAD);
 429 
 430   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 431   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 432   // or error. GC used to walk the placeholder table as strong roots.
 433   // The instanceKlass is kept alive because the class loader is on the stack,
 434   // which keeps the loader_data alive, as well as all instanceKlasses in
 435   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 436   {
 437     MutexLocker mu(SystemDictionary_lock, THREAD);
 438     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 439     SystemDictionary_lock->notify_all();
 440   }
 441   if (HAS_PENDING_EXCEPTION || superk == NULL) {
 442     // can null superk
 443     Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
 444     assert(k == NULL || k == superk, "must be");
 445     if (k == NULL) {
 446       superk = NULL;
 447     }
 448   }
 449 
 450   return superk;
 451 }
 452 
 453 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
 454                                                   Handle class_loader,
 455                                                   Handle protection_domain,
 456                                                   TRAPS) {
 457   if(!has_checkPackageAccess()) return;
 458 
 459   // Now we have to call back to java to check if the initating class has access
 460   JavaValue result(T_VOID);
 461   LogTarget(Debug, protectiondomain) lt;
 462   if (lt.is_enabled()) {
 463     ResourceMark rm;
 464     // Print out trace information
 465     LogStream ls(lt);
 466     ls.print_cr("Checking package access");
 467     if (class_loader() != NULL) {
 468       ls.print("class loader: ");
 469       class_loader()->print_value_on(&ls);
 470     } else {
 471       ls.print_cr("class loader: NULL");
 472     }
 473     if (protection_domain() != NULL) {
 474       ls.print(" protection domain: ");
 475       protection_domain()->print_value_on(&ls);
 476     } else {
 477       ls.print_cr(" protection domain: NULL");
 478     }
 479     ls.print(" loading: "); klass->print_value_on(&ls);
 480     ls.cr();
 481   }
 482 
 483   // This handle and the class_loader handle passed in keeps this class from
 484   // being unloaded through several GC points.
 485   // The class_loader handle passed in is the initiating loader.
 486   Handle mirror(THREAD, klass->java_mirror());
 487 
 488   InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
 489   JavaCalls::call_special(&result,
 490                          class_loader,
 491                          system_loader,
 492                          vmSymbols::checkPackageAccess_name(),
 493                          vmSymbols::class_protectiondomain_signature(),
 494                          mirror,
 495                          protection_domain,
 496                          THREAD);
 497 
 498   if (HAS_PENDING_EXCEPTION) {
 499     log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
 500   } else {
 501    log_debug(protectiondomain)("granted");
 502   }
 503 
 504   if (HAS_PENDING_EXCEPTION) return;
 505 
 506   // If no exception has been thrown, we have validated the protection domain
 507   // Insert the protection domain of the initiating class into the set.
 508   {
 509     ClassLoaderData* loader_data = class_loader_data(class_loader);
 510     Dictionary* dictionary = loader_data->dictionary();
 511 
 512     Symbol*  kn = klass->name();
 513     unsigned int d_hash = dictionary->compute_hash(kn);
 514 
 515     MutexLocker mu(SystemDictionary_lock, THREAD);
 516     int d_index = dictionary->hash_to_index(d_hash);
 517     dictionary->add_protection_domain(d_index, d_hash, klass,
 518                                       protection_domain, THREAD);
 519   }
 520 }
 521 
 522 // We only get here if this thread finds that another thread
 523 // has already claimed the placeholder token for the current operation,
 524 // but that other thread either never owned or gave up the
 525 // object lock
 526 // Waits on SystemDictionary_lock to indicate placeholder table updated
 527 // On return, caller must recheck placeholder table state
 528 //
 529 // We only get here if
 530 //  1) custom classLoader, i.e. not bootstrap classloader
 531 //  2) custom classLoader has broken the class loader objectLock
 532 //     so another thread got here in parallel
 533 //
 534 // lockObject must be held.
 535 // Complicated dance due to lock ordering:
 536 // Must first release the classloader object lock to
 537 // allow initial definer to complete the class definition
 538 // and to avoid deadlock
 539 // Reclaim classloader lock object with same original recursion count
 540 // Must release SystemDictionary_lock after notify, since
 541 // class loader lock must be claimed before SystemDictionary_lock
 542 // to prevent deadlocks
 543 //
 544 // The notify allows applications that did an untimed wait() on
 545 // the classloader object lock to not hang.
 546 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 547   assert_lock_strong(SystemDictionary_lock);
 548 
 549   bool calledholdinglock
 550       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 551   assert(calledholdinglock,"must hold lock for notify");
 552   assert((!oopDesc::equals(lockObject(), _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 553   ObjectSynchronizer::notifyall(lockObject, THREAD);
 554   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 555   SystemDictionary_lock->wait();
 556   SystemDictionary_lock->unlock();
 557   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 558   SystemDictionary_lock->lock();
 559 }
 560 
 561 // If the class in is in the placeholder table, class loading is in progress
 562 // For cases where the application changes threads to load classes, it
 563 // is critical to ClassCircularity detection that we try loading
 564 // the superclass on the same thread internally, so we do parallel
 565 // super class loading here.
 566 // This also is critical in cases where the original thread gets stalled
 567 // even in non-circularity situations.
 568 // Note: must call resolve_super_or_fail even if null super -
 569 // to force placeholder entry creation for this class for circularity detection
 570 // Caller must check for pending exception
 571 // Returns non-null Klass* if other thread has completed load
 572 // and we are done,
 573 // If return null Klass* and no pending exception, the caller must load the class
 574 InstanceKlass* SystemDictionary::handle_parallel_super_load(
 575     Symbol* name, Symbol* superclassname, Handle class_loader,
 576     Handle protection_domain, Handle lockObject, TRAPS) {
 577 
 578   ClassLoaderData* loader_data = class_loader_data(class_loader);
 579   Dictionary* dictionary = loader_data->dictionary();
 580   unsigned int d_hash = dictionary->compute_hash(name);
 581   unsigned int p_hash = placeholders()->compute_hash(name);
 582   int p_index = placeholders()->hash_to_index(p_hash);
 583 
 584   // superk is not used, resolve_super called for circularity check only
 585   // This code is reached in two situations. One if this thread
 586   // is loading the same class twice (e.g. ClassCircularity, or
 587   // java.lang.instrument).
 588   // The second is if another thread started the resolve_super first
 589   // and has not yet finished.
 590   // In both cases the original caller will clean up the placeholder
 591   // entry on error.
 592   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 593                                                           superclassname,
 594                                                           class_loader,
 595                                                           protection_domain,
 596                                                           true,
 597                                                           CHECK_NULL);
 598 
 599   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 600   // Serial class loaders and bootstrap classloader do wait for superclass loads
 601  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 602     MutexLocker mu(SystemDictionary_lock, THREAD);
 603     // Check if classloading completed while we were loading superclass or waiting
 604     return find_class(d_hash, name, dictionary);
 605   }
 606 
 607   // must loop to both handle other placeholder updates
 608   // and spurious notifications
 609   bool super_load_in_progress = true;
 610   PlaceholderEntry* placeholder;
 611   while (super_load_in_progress) {
 612     MutexLocker mu(SystemDictionary_lock, THREAD);
 613     // Check if classloading completed while we were loading superclass or waiting
 614     InstanceKlass* check = find_class(d_hash, name, dictionary);
 615     if (check != NULL) {
 616       // Klass is already loaded, so just return it
 617       return check;
 618     } else {
 619       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 620       if (placeholder && placeholder->super_load_in_progress() ){
 621         // We only get here if the application has released the
 622         // classloader lock when another thread was in the middle of loading a
 623         // superclass/superinterface for this class, and now
 624         // this thread is also trying to load this class.
 625         // To minimize surprises, the first thread that started to
 626         // load a class should be the one to complete the loading
 627         // with the classfile it initially expected.
 628         // This logic has the current thread wait once it has done
 629         // all the superclass/superinterface loading it can, until
 630         // the original thread completes the class loading or fails
 631         // If it completes we will use the resulting InstanceKlass
 632         // which we will find below in the systemDictionary.
 633         // We also get here for parallel bootstrap classloader
 634         if (class_loader.is_null()) {
 635           SystemDictionary_lock->wait();
 636         } else {
 637           double_lock_wait(lockObject, THREAD);
 638         }
 639       } else {
 640         // If not in SD and not in PH, other thread's load must have failed
 641         super_load_in_progress = false;
 642       }
 643     }
 644   }
 645   return NULL;
 646 }
 647 
 648 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
 649   assert(event != NULL, "invariant");
 650   assert(k != NULL, "invariant");
 651   assert(event->should_commit(), "invariant");
 652   event->set_loadedClass(k);
 653   event->set_definingClassLoader(k->class_loader_data());
 654   event->set_initiatingClassLoader(init_cld);
 655   event->commit();
 656 }
 657 
 658 
 659 // Be careful when modifying this code: once you have run
 660 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
 661 // you need to find_and_remove it before returning.
 662 // So be careful to not exit with a CHECK_ macro betweeen these calls.
 663 //
 664 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
 665 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 666                                                                 Handle class_loader,
 667                                                                 Handle protection_domain,
 668                                                                 TRAPS) {
 669   assert(name != NULL && !FieldType::is_array(name) &&
 670          !FieldType::is_obj(name), "invalid class name");
 671 
 672   EventClassLoad class_load_start_event;
 673 
 674   HandleMark hm(THREAD);
 675 
 676   // Fix for 4474172; see evaluation for more details
 677   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 678   ClassLoaderData* loader_data = register_loader(class_loader);
 679   Dictionary* dictionary = loader_data->dictionary();
 680   unsigned int d_hash = dictionary->compute_hash(name);
 681 
 682   // Do lookup to see if class already exist and the protection domain
 683   // has the right access
 684   // This call uses find which checks protection domain already matches
 685   // All subsequent calls use find_class, and set has_loaded_class so that
 686   // before we return a result we call out to java to check for valid protection domain
 687   // to allow returning the Klass* and add it to the pd_set if it is valid
 688   {
 689     InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
 690     if (probe != NULL) return probe;
 691   }
 692 
 693   // Non-bootstrap class loaders will call out to class loader and
 694   // define via jvm/jni_DefineClass which will acquire the
 695   // class loader object lock to protect against multiple threads
 696   // defining the class in parallel by accident.
 697   // This lock must be acquired here so the waiter will find
 698   // any successful result in the SystemDictionary and not attempt
 699   // the define.
 700   // ParallelCapable Classloaders and the bootstrap classloader
 701   // do not acquire lock here.
 702   bool DoObjectLock = true;
 703   if (is_parallelCapable(class_loader)) {
 704     DoObjectLock = false;
 705   }
 706 
 707   unsigned int p_hash = placeholders()->compute_hash(name);
 708   int p_index = placeholders()->hash_to_index(p_hash);
 709 
 710   // Class is not in SystemDictionary so we have to do loading.
 711   // Make sure we are synchronized on the class loader before we proceed
 712   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 713   check_loader_lock_contention(lockObject, THREAD);
 714   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 715 
 716   // Check again (after locking) if class already exist in SystemDictionary
 717   bool class_has_been_loaded   = false;
 718   bool super_load_in_progress  = false;
 719   bool havesupername = false;
 720   InstanceKlass* k = NULL;
 721   PlaceholderEntry* placeholder;
 722   Symbol* superclassname = NULL;
 723 
 724   assert(THREAD->can_call_java(),
 725          "can not load classes with compiler thread: class=%s, classloader=%s",
 726          name->as_C_string(),
 727          class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
 728   {
 729     MutexLocker mu(SystemDictionary_lock, THREAD);
 730     InstanceKlass* check = find_class(d_hash, name, dictionary);
 731     if (check != NULL) {
 732       // InstanceKlass is already loaded, so just return it
 733       class_has_been_loaded = true;
 734       k = check;
 735     } else {
 736       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 737       if (placeholder && placeholder->super_load_in_progress()) {
 738          super_load_in_progress = true;
 739          if (placeholder->havesupername() == true) {
 740            superclassname = placeholder->supername();
 741            havesupername = true;
 742          }
 743       }
 744     }
 745   }
 746 
 747   // If the class is in the placeholder table, class loading is in progress
 748   if (super_load_in_progress && havesupername==true) {
 749     k = handle_parallel_super_load(name,
 750                                    superclassname,
 751                                    class_loader,
 752                                    protection_domain,
 753                                    lockObject, THREAD);
 754     if (HAS_PENDING_EXCEPTION) {
 755       return NULL;
 756     }
 757     if (k != NULL) {
 758       class_has_been_loaded = true;
 759     }
 760   }
 761 
 762   bool throw_circularity_error = false;
 763   if (!class_has_been_loaded) {
 764     bool load_instance_added = false;
 765 
 766     // add placeholder entry to record loading instance class
 767     // Five cases:
 768     // All cases need to prevent modifying bootclasssearchpath
 769     // in parallel with a classload of same classname
 770     // Redefineclasses uses existence of the placeholder for the duration
 771     // of the class load to prevent concurrent redefinition of not completely
 772     // defined classes.
 773     // case 1. traditional classloaders that rely on the classloader object lock
 774     //   - no other need for LOAD_INSTANCE
 775     // case 2. traditional classloaders that break the classloader object lock
 776     //    as a deadlock workaround. Detection of this case requires that
 777     //    this check is done while holding the classloader object lock,
 778     //    and that lock is still held when calling classloader's loadClass.
 779     //    For these classloaders, we ensure that the first requestor
 780     //    completes the load and other requestors wait for completion.
 781     // case 3. Bootstrap classloader - don't own objectLocker
 782     //    This classloader supports parallelism at the classloader level,
 783     //    but only allows a single load of a class/classloader pair.
 784     //    No performance benefit and no deadlock issues.
 785     // case 4. parallelCapable user level classloaders - without objectLocker
 786     //    Allow parallel classloading of a class/classloader pair
 787 
 788     {
 789       MutexLocker mu(SystemDictionary_lock, THREAD);
 790       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 791         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 792         if (oldprobe) {
 793           // only need check_seen_thread once, not on each loop
 794           // 6341374 java/lang/Instrument with -Xcomp
 795           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 796             throw_circularity_error = true;
 797           } else {
 798             // case 1: traditional: should never see load_in_progress.
 799             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 800 
 801               // case 3: bootstrap classloader: prevent futile classloading,
 802               // wait on first requestor
 803               if (class_loader.is_null()) {
 804                 SystemDictionary_lock->wait();
 805               } else {
 806               // case 2: traditional with broken classloader lock. wait on first
 807               // requestor.
 808                 double_lock_wait(lockObject, THREAD);
 809               }
 810               // Check if classloading completed while we were waiting
 811               InstanceKlass* check = find_class(d_hash, name, dictionary);
 812               if (check != NULL) {
 813                 // Klass is already loaded, so just return it
 814                 k = check;
 815                 class_has_been_loaded = true;
 816               }
 817               // check if other thread failed to load and cleaned up
 818               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 819             }
 820           }
 821         }
 822       }
 823       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 824       // case 4: parallelCapable: allow competing threads to try
 825       // LOAD_INSTANCE in parallel
 826 
 827       if (!throw_circularity_error && !class_has_been_loaded) {
 828         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 829         load_instance_added = true;
 830         // For class loaders that do not acquire the classloader object lock,
 831         // if they did not catch another thread holding LOAD_INSTANCE,
 832         // need a check analogous to the acquire ObjectLocker/find_class
 833         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 834         // one final check if the load has already completed
 835         // class loaders holding the ObjectLock shouldn't find the class here
 836         InstanceKlass* check = find_class(d_hash, name, dictionary);
 837         if (check != NULL) {
 838         // Klass is already loaded, so return it after checking/adding protection domain
 839           k = check;
 840           class_has_been_loaded = true;
 841         }
 842       }
 843     }
 844 
 845     // must throw error outside of owning lock
 846     if (throw_circularity_error) {
 847       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 848       ResourceMark rm(THREAD);
 849       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 850     }
 851 
 852     if (!class_has_been_loaded) {
 853 
 854       // Do actual loading
 855       k = load_instance_class(name, class_loader, THREAD);
 856 
 857       // If everything was OK (no exceptions, no null return value), and
 858       // class_loader is NOT the defining loader, do a little more bookkeeping.
 859       if (!HAS_PENDING_EXCEPTION && k != NULL &&
 860         !oopDesc::equals(k->class_loader(), class_loader())) {
 861 
 862         check_constraints(d_hash, k, class_loader, false, THREAD);
 863 
 864         // Need to check for a PENDING_EXCEPTION again; check_constraints
 865         // can throw and doesn't use the CHECK macro.
 866         if (!HAS_PENDING_EXCEPTION) {
 867           { // Grabbing the Compile_lock prevents systemDictionary updates
 868             // during compilations.
 869             MutexLocker mu(Compile_lock, THREAD);
 870             update_dictionary(d_hash, p_index, p_hash,
 871               k, class_loader, THREAD);
 872           }
 873 
 874           if (JvmtiExport::should_post_class_load()) {
 875             Thread *thread = THREAD;
 876             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 877             JvmtiExport::post_class_load((JavaThread *) thread, k);
 878           }
 879         }
 880       }
 881     } // load_instance_class
 882 
 883     if (load_instance_added == true) {
 884       // clean up placeholder entries for LOAD_INSTANCE success or error
 885       // This brackets the SystemDictionary updates for both defining
 886       // and initiating loaders
 887       MutexLocker mu(SystemDictionary_lock, THREAD);
 888       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 889       SystemDictionary_lock->notify_all();
 890     }
 891   }
 892 
 893   if (HAS_PENDING_EXCEPTION || k == NULL) {
 894     return NULL;
 895   }
 896   if (class_load_start_event.should_commit()) {
 897     post_class_load_event(&class_load_start_event, k, loader_data);
 898   }
 899 #ifdef ASSERT
 900   {
 901     ClassLoaderData* loader_data = k->class_loader_data();
 902     MutexLocker mu(SystemDictionary_lock, THREAD);
 903     InstanceKlass* kk = find_class(name, loader_data);
 904     assert(kk == k, "should be present in dictionary");
 905   }
 906 #endif
 907 
 908   // return if the protection domain in NULL
 909   if (protection_domain() == NULL) return k;
 910 
 911   // Check the protection domain has the right access
 912   if (dictionary->is_valid_protection_domain(d_hash, name,
 913                                              protection_domain)) {
 914     return k;
 915   }
 916 
 917   // Verify protection domain. If it fails an exception is thrown
 918   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 919 
 920   return k;
 921 }
 922 
 923 
 924 // This routine does not lock the system dictionary.
 925 //
 926 // Since readers don't hold a lock, we must make sure that system
 927 // dictionary entries are only removed at a safepoint (when only one
 928 // thread is running), and are added to in a safe way (all links must
 929 // be updated in an MT-safe manner).
 930 //
 931 // Callers should be aware that an entry could be added just after
 932 // _dictionary->bucket(index) is read here, so the caller will not see
 933 // the new entry.
 934 
 935 Klass* SystemDictionary::find(Symbol* class_name,
 936                               Handle class_loader,
 937                               Handle protection_domain,
 938                               TRAPS) {
 939 
 940   // The result of this call should be consistent with the result
 941   // of the call to resolve_instance_class_or_null().
 942   // See evaluation 6790209 and 4474172 for more details.
 943   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 944   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 945 
 946   if (loader_data == NULL) {
 947     // If the ClassLoaderData has not been setup,
 948     // then the class loader has no entries in the dictionary.
 949     return NULL;
 950   }
 951 
 952   Dictionary* dictionary = loader_data->dictionary();
 953   unsigned int d_hash = dictionary->compute_hash(class_name);
 954   return dictionary->find(d_hash, class_name,
 955                           protection_domain);
 956 }
 957 
 958 
 959 // Look for a loaded instance or array klass by name.  Do not do any loading.
 960 // return NULL in case of error.
 961 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 962                                                       Handle class_loader,
 963                                                       Handle protection_domain,
 964                                                       TRAPS) {
 965   Klass* k = NULL;
 966   assert(class_name != NULL, "class name must be non NULL");
 967 
 968   if (FieldType::is_array(class_name)) {
 969     // The name refers to an array.  Parse the name.
 970     // dimension and object_key in FieldArrayInfo are assigned as a
 971     // side-effect of this call
 972     FieldArrayInfo fd;
 973     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 974     if (t != T_OBJECT) {
 975       k = Universe::typeArrayKlassObj(t);
 976     } else {
 977       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 978     }
 979     if (k != NULL) {
 980       k = k->array_klass_or_null(fd.dimension());
 981     }
 982   } else {
 983     k = find(class_name, class_loader, protection_domain, THREAD);
 984   }
 985   return k;
 986 }
 987 
 988 // Note: this method is much like resolve_from_stream, but
 989 // does not publish the classes via the SystemDictionary.
 990 // Handles unsafe_DefineAnonymousClass and redefineclasses
 991 // RedefinedClasses do not add to the class hierarchy
 992 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
 993                                               Handle class_loader,
 994                                               Handle protection_domain,
 995                                               ClassFileStream* st,
 996                                               const InstanceKlass* unsafe_anonymous_host,
 997                                               GrowableArray<Handle>* cp_patches,
 998                                               TRAPS) {
 999 
1000   EventClassLoad class_load_start_event;
1001 
1002   ClassLoaderData* loader_data;
1003   if (unsafe_anonymous_host != NULL) {
1004     // Create a new CLD for an unsafe anonymous class, that uses the same class loader
1005     // as the unsafe_anonymous_host
1006     guarantee(oopDesc::equals(unsafe_anonymous_host->class_loader(), class_loader()), "should be the same");
1007     loader_data = ClassLoaderData::unsafe_anonymous_class_loader_data(class_loader);
1008   } else {
1009     loader_data = ClassLoaderData::class_loader_data(class_loader());
1010   }
1011 
1012   assert(st != NULL, "invariant");
1013   assert(st->need_verify(), "invariant");
1014 
1015   // Parse stream and create a klass.
1016   // Note that we do this even though this klass might
1017   // already be present in the SystemDictionary, otherwise we would not
1018   // throw potential ClassFormatErrors.
1019 
1020   InstanceKlass* k = KlassFactory::create_from_stream(st,
1021                                                       class_name,
1022                                                       loader_data,
1023                                                       protection_domain,
1024                                                       unsafe_anonymous_host,
1025                                                       cp_patches,
1026                                                       CHECK_NULL);
1027 
1028   if (unsafe_anonymous_host != NULL && k != NULL) {
1029     // Unsafe anonymous classes must update ClassLoaderData holder (was unsafe_anonymous_host loader)
1030     // so that they can be unloaded when the mirror is no longer referenced.
1031     k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1032 
1033     {
1034       MutexLocker mu_r(Compile_lock, THREAD);
1035 
1036       // Add to class hierarchy, initialize vtables, and do possible
1037       // deoptimizations.
1038       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1039 
1040       // But, do not add to dictionary.
1041 
1042       // compiled code dependencies need to be validated anyway
1043       notice_modification();
1044     }
1045 
1046     // Rewrite and patch constant pool here.
1047     k->link_class(CHECK_NULL);
1048     if (cp_patches != NULL) {
1049       k->constants()->patch_resolved_references(cp_patches);
1050     }
1051 
1052     // If it's anonymous, initialize it now, since nobody else will.
1053     k->eager_initialize(CHECK_NULL);
1054 
1055     // notify jvmti
1056     if (JvmtiExport::should_post_class_load()) {
1057         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1058         JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1059     }
1060     if (class_load_start_event.should_commit()) {
1061       post_class_load_event(&class_load_start_event, k, loader_data);
1062     }
1063   }
1064   assert(unsafe_anonymous_host != NULL || NULL == cp_patches,
1065          "cp_patches only found with unsafe_anonymous_host");
1066 
1067   return k;
1068 }
1069 
1070 // Add a klass to the system from a stream (called by jni_DefineClass and
1071 // JVM_DefineClass).
1072 // Note: class_name can be NULL. In that case we do not know the name of
1073 // the class until we have parsed the stream.
1074 
1075 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1076                                                      Handle class_loader,
1077                                                      Handle protection_domain,
1078                                                      ClassFileStream* st,
1079                                                      TRAPS) {
1080 
1081   HandleMark hm(THREAD);
1082 
1083   // Classloaders that support parallelism, e.g. bootstrap classloader,
1084   // do not acquire lock here
1085   bool DoObjectLock = true;
1086   if (is_parallelCapable(class_loader)) {
1087     DoObjectLock = false;
1088   }
1089 
1090   ClassLoaderData* loader_data = register_loader(class_loader);
1091 
1092   // Make sure we are synchronized on the class loader before we proceed
1093   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1094   check_loader_lock_contention(lockObject, THREAD);
1095   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1096 
1097   assert(st != NULL, "invariant");
1098 
1099   // Parse the stream and create a klass.
1100   // Note that we do this even though this klass might
1101   // already be present in the SystemDictionary, otherwise we would not
1102   // throw potential ClassFormatErrors.
1103  InstanceKlass* k = NULL;
1104 
1105 #if INCLUDE_CDS
1106   if (!DumpSharedSpaces) {
1107     k = SystemDictionaryShared::lookup_from_stream(class_name,
1108                                                    class_loader,
1109                                                    protection_domain,
1110                                                    st,
1111                                                    CHECK_NULL);
1112   }
1113 #endif
1114 
1115   if (k == NULL) {
1116     if (st->buffer() == NULL) {
1117       return NULL;
1118     }
1119     k = KlassFactory::create_from_stream(st,
1120                                          class_name,
1121                                          loader_data,
1122                                          protection_domain,
1123                                          NULL, // unsafe_anonymous_host
1124                                          NULL, // cp_patches
1125                                          CHECK_NULL);
1126   }
1127 
1128   assert(k != NULL, "no klass created");
1129   Symbol* h_name = k->name();
1130   assert(class_name == NULL || class_name == h_name, "name mismatch");
1131 
1132   // Add class just loaded
1133   // If a class loader supports parallel classloading handle parallel define requests
1134   // find_or_define_instance_class may return a different InstanceKlass
1135   if (is_parallelCapable(class_loader)) {
1136     InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1137     if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1138       // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1139       assert(defined_k != NULL, "Should have a klass if there's no exception");
1140       loader_data->add_to_deallocate_list(k);
1141       k = defined_k;
1142     }
1143   } else {
1144     define_instance_class(k, THREAD);
1145   }
1146 
1147   // If defining the class throws an exception register 'k' for cleanup.
1148   if (HAS_PENDING_EXCEPTION) {
1149     assert(k != NULL, "Must have an instance klass here!");
1150     loader_data->add_to_deallocate_list(k);
1151     return NULL;
1152   }
1153 
1154   // Make sure we have an entry in the SystemDictionary on success
1155   debug_only( {
1156     MutexLocker mu(SystemDictionary_lock, THREAD);
1157 
1158     Klass* check = find_class(h_name, k->class_loader_data());
1159     assert(check == k, "should be present in the dictionary");
1160   } );
1161 
1162   return k;
1163 }
1164 
1165 #if INCLUDE_CDS
1166 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1167                                              int number_of_entries) {
1168   assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
1169   assert(length == _shared_dictionary_size * sizeof(HashtableBucket<mtClass>),
1170          "bad shared dictionary size.");
1171   _shared_dictionary = new Dictionary(ClassLoaderData::the_null_class_loader_data(),
1172                                       _shared_dictionary_size, t, number_of_entries,
1173                                       false /* explicitly set _resizable to false */);
1174 }
1175 
1176 
1177 // If there is a shared dictionary, then find the entry for the
1178 // given shared system class, if any.
1179 
1180 InstanceKlass* SystemDictionary::find_shared_class(Symbol* class_name) {
1181   if (shared_dictionary() != NULL) {
1182     unsigned int d_hash = shared_dictionary()->compute_hash(class_name);
1183     int d_index = shared_dictionary()->hash_to_index(d_hash);
1184 
1185     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1186   } else {
1187     return NULL;
1188   }
1189 }
1190 
1191 
1192 // Load a class from the shared spaces (found through the shared system
1193 // dictionary).  Force the superclass and all interfaces to be loaded.
1194 // Update the class definition to include sibling classes and no
1195 // subclasses (yet).  [Classes in the shared space are not part of the
1196 // object hierarchy until loaded.]
1197 
1198 InstanceKlass* SystemDictionary::load_shared_class(
1199                  Symbol* class_name, Handle class_loader, TRAPS) {
1200   InstanceKlass* ik = find_shared_class(class_name);
1201   // Make sure we only return the boot class for the NULL classloader.
1202   if (ik != NULL &&
1203       ik->is_shared_boot_class() && class_loader.is_null()) {
1204     Handle protection_domain;
1205     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1206   }
1207   return NULL;
1208 }
1209 
1210 // Check if a shared class can be loaded by the specific classloader:
1211 //
1212 // NULL classloader:
1213 //   - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1214 //   - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1215 //     be defined in an unnamed module.
1216 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1217                                                InstanceKlass* ik,
1218                                                Handle class_loader, TRAPS) {
1219   assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1220          "Cannot use sharing if java.base is patched");
1221   ResourceMark rm;
1222   int path_index = ik->shared_classpath_index();
1223   ClassLoaderData* loader_data = class_loader_data(class_loader);
1224   if (path_index < 0) {
1225     // path_index < 0 indicates that the class is intended for a custom loader
1226     // and should not be loaded by boot/platform/app loaders
1227     if (loader_data->is_builtin_class_loader_data()) {
1228       return false;
1229     } else {
1230       return true;
1231     }
1232   }
1233   SharedClassPathEntry* ent =
1234             (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1235   if (!Universe::is_module_initialized()) {
1236     assert(ent != NULL && ent->is_modules_image(),
1237            "Loading non-bootstrap classes before the module system is initialized");
1238     assert(class_loader.is_null(), "sanity");
1239     return true;
1240   }
1241   // Get the pkg_entry from the classloader
1242   TempNewSymbol pkg_name = NULL;
1243   PackageEntry* pkg_entry = NULL;
1244   ModuleEntry* mod_entry = NULL;
1245   const char* pkg_string = NULL;
1246   pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1247   if (pkg_name != NULL) {
1248     pkg_string = pkg_name->as_C_string();
1249     if (loader_data != NULL) {
1250       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1251     }
1252     if (pkg_entry != NULL) {
1253       mod_entry = pkg_entry->module();
1254     }
1255   }
1256 
1257   // If the archived class is from a module that has been patched at runtime,
1258   // the class cannot be loaded from the archive.
1259   if (mod_entry != NULL && mod_entry->is_patched()) {
1260     return false;
1261   }
1262 
1263   if (class_loader.is_null()) {
1264     assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1265     // The NULL classloader can load archived class originated from the
1266     // "modules" jimage and the -Xbootclasspath/a. For class from the
1267     // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1268     // by the NULL classloader.
1269     if (mod_entry != NULL) {
1270       // PackageEntry/ModuleEntry is found in the classloader. Check if the
1271       // ModuleEntry's location agrees with the archived class' origination.
1272       if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1273         return true; // Module class from the "module" jimage
1274       }
1275     }
1276 
1277     // If the archived class is not from the "module" jimage, the class can be
1278     // loaded by the NULL classloader if
1279     //
1280     // 1. the class is from the unamed package
1281     // 2. or, the class is not from a module defined in the NULL classloader
1282     // 3. or, the class is from an unamed module
1283     if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1284       // the class is from the -Xbootclasspath/a
1285       if (pkg_string == NULL ||
1286           pkg_entry == NULL ||
1287           pkg_entry->in_unnamed_module()) {
1288         assert(mod_entry == NULL ||
1289                mod_entry == loader_data->unnamed_module(),
1290                "the unnamed module is not defined in the classloader");
1291         return true;
1292       }
1293     }
1294     return false;
1295   } else {
1296     bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1297               ik, class_loader, pkg_string, pkg_name,
1298               pkg_entry, mod_entry, CHECK_(false));
1299     return res;
1300   }
1301 }
1302 
1303 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1304                                                    Handle class_loader,
1305                                                    Handle protection_domain, TRAPS) {
1306 
1307   if (ik != NULL) {
1308     Symbol* class_name = ik->name();
1309 
1310     bool visible = is_shared_class_visible(
1311                             class_name, ik, class_loader, CHECK_NULL);
1312     if (!visible) {
1313       return NULL;
1314     }
1315 
1316     // Resolve the superclass and interfaces. They must be the same
1317     // as in dump time, because the layout of <ik> depends on
1318     // the specific layout of ik->super() and ik->local_interfaces().
1319     //
1320     // If unexpected superclass or interfaces are found, we cannot
1321     // load <ik> from the shared archive.
1322 
1323     if (ik->super() != NULL) {
1324       Symbol*  cn = ik->super()->name();
1325       Klass *s = resolve_super_or_fail(class_name, cn,
1326                                        class_loader, protection_domain, true, CHECK_NULL);
1327       if (s != ik->super()) {
1328         // The dynamically resolved super class is not the same as the one we used during dump time,
1329         // so we cannot use ik.
1330         return NULL;
1331       } else {
1332         assert(s->is_shared(), "must be");
1333       }
1334     }
1335 
1336     Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1337     int num_interfaces = interfaces->length();
1338     for (int index = 0; index < num_interfaces; index++) {
1339       InstanceKlass* k = interfaces->at(index);
1340       Symbol* name  = k->name();
1341       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1342       if (k != i) {
1343         // The dynamically resolved interface class is not the same as the one we used during dump time,
1344         // so we cannot use ik.
1345         return NULL;
1346       } else {
1347         assert(i->is_shared(), "must be");
1348       }
1349     }
1350 
1351     InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1352         ik, class_name, class_loader, protection_domain, CHECK_NULL);
1353     if (new_ik != NULL) {
1354       // The class is changed by CFLH. Return the new class. The shared class is
1355       // not used.
1356       return new_ik;
1357     }
1358 
1359     // Adjust methods to recover missing data.  They need addresses for
1360     // interpreter entry points and their default native method address
1361     // must be reset.
1362 
1363     // Updating methods must be done under a lock so multiple
1364     // threads don't update these in parallel
1365     //
1366     // Shared classes are all currently loaded by either the bootstrap or
1367     // internal parallel class loaders, so this will never cause a deadlock
1368     // on a custom class loader lock.
1369 
1370     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1371     {
1372       HandleMark hm(THREAD);
1373       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1374       check_loader_lock_contention(lockObject, THREAD);
1375       ObjectLocker ol(lockObject, THREAD, true);
1376       // prohibited package check assumes all classes loaded from archive call
1377       // restore_unshareable_info which calls ik->set_package()
1378       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1379     }
1380 
1381     ik->print_class_load_logging(loader_data, NULL, NULL);
1382 
1383     // For boot loader, ensure that GetSystemPackage knows that a class in this
1384     // package was loaded.
1385     if (class_loader.is_null()) {
1386       int path_index = ik->shared_classpath_index();
1387       ResourceMark rm;
1388       ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1389     }
1390 
1391     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1392       // Only dump the classes that can be stored into CDS archive
1393       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1394         ResourceMark rm(THREAD);
1395         classlist_file->print_cr("%s", ik->name()->as_C_string());
1396         classlist_file->flush();
1397       }
1398     }
1399 
1400     // notify a class loaded from shared object
1401     ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1402 
1403     ik->set_has_passed_fingerprint_check(false);
1404     if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1405       uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1406       uint64_t cds_fp = ik->get_stored_fingerprint();
1407       if (aot_fp != 0 && aot_fp == cds_fp) {
1408         // This class matches with a class saved in an AOT library
1409         ik->set_has_passed_fingerprint_check(true);
1410       } else {
1411         ResourceMark rm;
1412         log_info(class, fingerprint)("%s :  expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1413       }
1414     }
1415   }
1416   return ik;
1417 }
1418 
1419 void SystemDictionary::clear_invoke_method_table() {
1420   SymbolPropertyEntry* spe = NULL;
1421   for (int index = 0; index < _invoke_method_table->table_size(); index++) {
1422     SymbolPropertyEntry* p = _invoke_method_table->bucket(index);
1423     while (p != NULL) {
1424       spe = p;
1425       p = p->next();
1426       _invoke_method_table->free_entry(spe);
1427     }
1428   }
1429 }
1430 #endif // INCLUDE_CDS
1431 
1432 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1433 
1434   if (class_loader.is_null()) {
1435     ResourceMark rm;
1436     PackageEntry* pkg_entry = NULL;
1437     bool search_only_bootloader_append = false;
1438     ClassLoaderData *loader_data = class_loader_data(class_loader);
1439 
1440     // Find the package in the boot loader's package entry table.
1441     TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1442     if (pkg_name != NULL) {
1443       pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1444     }
1445 
1446     // Prior to attempting to load the class, enforce the boot loader's
1447     // visibility boundaries.
1448     if (!Universe::is_module_initialized()) {
1449       // During bootstrapping, prior to module initialization, any
1450       // class attempting to be loaded must be checked against the
1451       // java.base packages in the boot loader's PackageEntryTable.
1452       // No class outside of java.base is allowed to be loaded during
1453       // this bootstrapping window.
1454       if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1455         // Class is either in the unnamed package or in
1456         // a named package within the unnamed module.  Either
1457         // case is outside of java.base, do not attempt to
1458         // load the class post java.base definition.  If
1459         // java.base has not been defined, let the class load
1460         // and its package will be checked later by
1461         // ModuleEntryTable::verify_javabase_packages.
1462         if (ModuleEntryTable::javabase_defined()) {
1463           return NULL;
1464         }
1465       } else {
1466         // Check that the class' package is defined within java.base.
1467         ModuleEntry* mod_entry = pkg_entry->module();
1468         Symbol* mod_entry_name = mod_entry->name();
1469         if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1470           return NULL;
1471         }
1472       }
1473     } else {
1474       // After the module system has been initialized, check if the class'
1475       // package is in a module defined to the boot loader.
1476       if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1477         // Class is either in the unnamed package, in a named package
1478         // within a module not defined to the boot loader or in a
1479         // a named package within the unnamed module.  In all cases,
1480         // limit visibility to search for the class only in the boot
1481         // loader's append path.
1482         search_only_bootloader_append = true;
1483       }
1484     }
1485 
1486     // Prior to bootstrapping's module initialization, never load a class outside
1487     // of the boot loader's module path
1488     assert(Universe::is_module_initialized() ||
1489            !search_only_bootloader_append,
1490            "Attempt to load a class outside of boot loader's module path");
1491 
1492     // Search the shared system dictionary for classes preloaded into the
1493     // shared spaces.
1494     InstanceKlass* k = NULL;
1495     {
1496 #if INCLUDE_CDS
1497       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1498       k = load_shared_class(class_name, class_loader, THREAD);
1499 #endif
1500     }
1501 
1502     if (k == NULL) {
1503       // Use VM class loader
1504       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1505       k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1506     }
1507 
1508     // find_or_define_instance_class may return a different InstanceKlass
1509     if (k != NULL) {
1510       InstanceKlass* defined_k =
1511         find_or_define_instance_class(class_name, class_loader, k, THREAD);
1512       if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1513         // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1514         assert(defined_k != NULL, "Should have a klass if there's no exception");
1515         loader_data->add_to_deallocate_list(k);
1516         k = defined_k;
1517       } else if (HAS_PENDING_EXCEPTION) {
1518         loader_data->add_to_deallocate_list(k);
1519         return NULL;
1520       }
1521     }
1522     return k;
1523   } else {
1524     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1525     ResourceMark rm(THREAD);
1526 
1527     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1528     JavaThread* jt = (JavaThread*) THREAD;
1529 
1530     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1531                                ClassLoader::perf_app_classload_selftime(),
1532                                ClassLoader::perf_app_classload_count(),
1533                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1534                                jt->get_thread_stat()->perf_timers_addr(),
1535                                PerfClassTraceTime::CLASS_LOAD);
1536 
1537     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1538     // Translate to external class name format, i.e., convert '/' chars to '.'
1539     Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1540 
1541     JavaValue result(T_OBJECT);
1542 
1543     InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1544 
1545     // Call public unsynchronized loadClass(String) directly for all class loaders.
1546     // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1547     // acquire a class-name based lock rather than the class loader object lock.
1548     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1549     JavaCalls::call_virtual(&result,
1550                             class_loader,
1551                             spec_klass,
1552                             vmSymbols::loadClass_name(),
1553                             vmSymbols::string_class_signature(),
1554                             string,
1555                             CHECK_NULL);
1556 
1557     assert(result.get_type() == T_OBJECT, "just checking");
1558     oop obj = (oop) result.get_jobject();
1559 
1560     // Primitive classes return null since forName() can not be
1561     // used to obtain any of the Class objects representing primitives or void
1562     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1563       InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1564       // For user defined Java class loaders, check that the name returned is
1565       // the same as that requested.  This check is done for the bootstrap
1566       // loader when parsing the class file.
1567       if (class_name == k->name()) {
1568         return k;
1569       }
1570     }
1571     // Class is not found or has the wrong name, return NULL
1572     return NULL;
1573   }
1574 }
1575 
1576 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1577   EventClassDefine event;
1578   if (event.should_commit()) {
1579     event.set_definedClass(k);
1580     event.set_definingClassLoader(def_cld);
1581     event.commit();
1582   }
1583 }
1584 
1585 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1586 
1587   HandleMark hm(THREAD);
1588   ClassLoaderData* loader_data = k->class_loader_data();
1589   Handle class_loader_h(THREAD, loader_data->class_loader());
1590 
1591  // for bootstrap and other parallel classloaders don't acquire lock,
1592  // use placeholder token
1593  // If a parallelCapable class loader calls define_instance_class instead of
1594  // find_or_define_instance_class to get here, we have a timing
1595  // hole with systemDictionary updates and check_constraints
1596  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1597     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1598          compute_loader_lock_object(class_loader_h, THREAD)),
1599          "define called without lock");
1600   }
1601 
1602   // Check class-loading constraints. Throw exception if violation is detected.
1603   // Grabs and releases SystemDictionary_lock
1604   // The check_constraints/find_class call and update_dictionary sequence
1605   // must be "atomic" for a specific class/classloader pair so we never
1606   // define two different instanceKlasses for that class/classloader pair.
1607   // Existing classloaders will call define_instance_class with the
1608   // classloader lock held
1609   // Parallel classloaders will call find_or_define_instance_class
1610   // which will require a token to perform the define class
1611   Symbol*  name_h = k->name();
1612   Dictionary* dictionary = loader_data->dictionary();
1613   unsigned int d_hash = dictionary->compute_hash(name_h);
1614   check_constraints(d_hash, k, class_loader_h, true, CHECK);
1615 
1616   // Register class just loaded with class loader (placed in Vector)
1617   // Note we do this before updating the dictionary, as this can
1618   // fail with an OutOfMemoryError (if it does, we will *not* put this
1619   // class in the dictionary and will not update the class hierarchy).
1620   // JVMTI FollowReferences needs to find the classes this way.
1621   if (k->class_loader() != NULL) {
1622     methodHandle m(THREAD, Universe::loader_addClass_method());
1623     JavaValue result(T_VOID);
1624     JavaCallArguments args(class_loader_h);
1625     args.push_oop(Handle(THREAD, k->java_mirror()));
1626     JavaCalls::call(&result, m, &args, CHECK);
1627   }
1628 
1629   // Add the new class. We need recompile lock during update of CHA.
1630   {
1631     unsigned int p_hash = placeholders()->compute_hash(name_h);
1632     int p_index = placeholders()->hash_to_index(p_hash);
1633 
1634     MutexLocker mu_r(Compile_lock, THREAD);
1635 
1636     // Add to class hierarchy, initialize vtables, and do possible
1637     // deoptimizations.
1638     add_to_hierarchy(k, CHECK); // No exception, but can block
1639 
1640     // Add to systemDictionary - so other classes can see it.
1641     // Grabs and releases SystemDictionary_lock
1642     update_dictionary(d_hash, p_index, p_hash,
1643                       k, class_loader_h, THREAD);
1644   }
1645   k->eager_initialize(THREAD);
1646 
1647   // notify jvmti
1648   if (JvmtiExport::should_post_class_load()) {
1649       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1650       JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1651 
1652   }
1653   post_class_define_event(k, loader_data);
1654 }
1655 
1656 // Support parallel classloading
1657 // All parallel class loaders, including bootstrap classloader
1658 // lock a placeholder entry for this class/class_loader pair
1659 // to allow parallel defines of different classes for this class loader
1660 // With AllowParallelDefine flag==true, in case they do not synchronize around
1661 // FindLoadedClass/DefineClass, calls, we check for parallel
1662 // loading for them, wait if a defineClass is in progress
1663 // and return the initial requestor's results
1664 // This flag does not apply to the bootstrap classloader.
1665 // With AllowParallelDefine flag==false, call through to define_instance_class
1666 // which will throw LinkageError: duplicate class definition.
1667 // False is the requested default.
1668 // For better performance, the class loaders should synchronize
1669 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1670 // potentially waste time reading and parsing the bytestream.
1671 // Note: VM callers should ensure consistency of k/class_name,class_loader
1672 // Be careful when modifying this code: once you have run
1673 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1674 // you need to find_and_remove it before returning.
1675 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1676 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1677                                                                InstanceKlass* k, TRAPS) {
1678 
1679   Symbol*  name_h = k->name(); // passed in class_name may be null
1680   ClassLoaderData* loader_data = class_loader_data(class_loader);
1681   Dictionary* dictionary = loader_data->dictionary();
1682 
1683   unsigned int d_hash = dictionary->compute_hash(name_h);
1684 
1685   // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1686   unsigned int p_hash = placeholders()->compute_hash(name_h);
1687   int p_index = placeholders()->hash_to_index(p_hash);
1688   PlaceholderEntry* probe;
1689 
1690   {
1691     MutexLocker mu(SystemDictionary_lock, THREAD);
1692     // First check if class already defined
1693     if (is_parallelDefine(class_loader)) {
1694       InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1695       if (check != NULL) {
1696         return check;
1697       }
1698     }
1699 
1700     // Acquire define token for this class/classloader
1701     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1702     // Wait if another thread defining in parallel
1703     // All threads wait - even those that will throw duplicate class: otherwise
1704     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1705     // if other thread has not finished updating dictionary
1706     while (probe->definer() != NULL) {
1707       SystemDictionary_lock->wait();
1708     }
1709     // Only special cases allow parallel defines and can use other thread's results
1710     // Other cases fall through, and may run into duplicate defines
1711     // caught by finding an entry in the SystemDictionary
1712     if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1713         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1714         SystemDictionary_lock->notify_all();
1715 #ifdef ASSERT
1716         InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1717         assert(check != NULL, "definer missed recording success");
1718 #endif
1719         return probe->instance_klass();
1720     } else {
1721       // This thread will define the class (even if earlier thread tried and had an error)
1722       probe->set_definer(THREAD);
1723     }
1724   }
1725 
1726   define_instance_class(k, THREAD);
1727 
1728   Handle linkage_exception = Handle(); // null handle
1729 
1730   // definer must notify any waiting threads
1731   {
1732     MutexLocker mu(SystemDictionary_lock, THREAD);
1733     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1734     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1735     if (probe != NULL) {
1736       if (HAS_PENDING_EXCEPTION) {
1737         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1738         CLEAR_PENDING_EXCEPTION;
1739       } else {
1740         probe->set_instance_klass(k);
1741       }
1742       probe->set_definer(NULL);
1743       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1744       SystemDictionary_lock->notify_all();
1745     }
1746   }
1747 
1748   // Can't throw exception while holding lock due to rank ordering
1749   if (linkage_exception() != NULL) {
1750     THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1751   }
1752 
1753   return k;
1754 }
1755 
1756 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1757   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1758   if (class_loader.is_null()) {
1759     return Handle(THREAD, _system_loader_lock_obj);
1760   } else {
1761     return class_loader;
1762   }
1763 }
1764 
1765 // This method is added to check how often we have to wait to grab loader
1766 // lock. The results are being recorded in the performance counters defined in
1767 // ClassLoader::_sync_systemLoaderLockContentionRate and
1768 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1769 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1770   if (!UsePerfData) {
1771     return;
1772   }
1773 
1774   assert(!loader_lock.is_null(), "NULL lock object");
1775 
1776   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1777       == ObjectSynchronizer::owner_other) {
1778     // contention will likely happen, so increment the corresponding
1779     // contention counter.
1780     if (oopDesc::equals(loader_lock(), _system_loader_lock_obj)) {
1781       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1782     } else {
1783       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1784     }
1785   }
1786 }
1787 
1788 // ----------------------------------------------------------------------------
1789 // Lookup
1790 
1791 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1792                                             Symbol* class_name,
1793                                             Dictionary* dictionary) {
1794   assert_locked_or_safepoint(SystemDictionary_lock);
1795   int index = dictionary->hash_to_index(hash);
1796   return dictionary->find_class(index, hash, class_name);
1797 }
1798 
1799 
1800 // Basic find on classes in the midst of being loaded
1801 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1802                                            ClassLoaderData* loader_data) {
1803   assert_locked_or_safepoint(SystemDictionary_lock);
1804   unsigned int p_hash = placeholders()->compute_hash(class_name);
1805   int p_index = placeholders()->hash_to_index(p_hash);
1806   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1807 }
1808 
1809 
1810 // Used for assertions and verification only
1811 // Precalculating the hash and index is an optimization because there are many lookups
1812 // before adding the class.
1813 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1814   assert_locked_or_safepoint(SystemDictionary_lock);
1815   #ifndef ASSERT
1816   guarantee(VerifyBeforeGC      ||
1817             VerifyDuringGC      ||
1818             VerifyBeforeExit    ||
1819             VerifyDuringStartup ||
1820             VerifyAfterGC, "too expensive");
1821   #endif
1822 
1823   Dictionary* dictionary = loader_data->dictionary();
1824   unsigned int d_hash = dictionary->compute_hash(class_name);
1825   return find_class(d_hash, class_name, dictionary);
1826 }
1827 
1828 
1829 // ----------------------------------------------------------------------------
1830 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1831 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1832 // before a new class is used.
1833 
1834 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1835   assert(k != NULL, "just checking");
1836   assert_locked_or_safepoint(Compile_lock);
1837 
1838   // Link into hierachy. Make sure the vtables are initialized before linking into
1839   k->append_to_sibling_list();                    // add to superklass/sibling list
1840   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1841   k->set_init_state(InstanceKlass::loaded);
1842   // Now flush all code that depended on old class hierarchy.
1843   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1844   // Also, first reinitialize vtable because it may have gotten out of synch
1845   // while the new class wasn't connected to the class hierarchy.
1846   CodeCache::flush_dependents_on(k);
1847 }
1848 
1849 // ----------------------------------------------------------------------------
1850 // GC support
1851 
1852 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1853 // Note: anonymous classes are not in the SD.
1854 bool SystemDictionary::do_unloading(GCTimer* gc_timer,
1855                                     bool do_cleaning) {
1856 
1857   bool unloading_occurred;
1858   {
1859     GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1860 
1861     // First, mark for unload all ClassLoaderData referencing a dead class loader.
1862     unloading_occurred = ClassLoaderDataGraph::do_unloading(do_cleaning);
1863     if (unloading_occurred) {
1864       JFR_ONLY(Jfr::on_unloading_classes();)
1865       ClassLoaderDataGraph::clean_module_and_package_info();
1866     }
1867   }
1868 
1869   // TODO: just return if !unloading_occurred.
1870   if (unloading_occurred) {
1871     {
1872       GCTraceTime(Debug, gc, phases) t("SymbolTable", gc_timer);
1873       // Check if there's work to do in the SymbolTable
1874       SymbolTable::do_check_concurrent_work();
1875     }
1876 
1877     {
1878       GCTraceTime(Debug, gc, phases) t("Dictionary", gc_timer);
1879       constraints()->purge_loader_constraints();
1880       resolution_errors()->purge_resolution_errors();
1881     }
1882   }
1883 
1884   {
1885     GCTraceTime(Debug, gc, phases) t("ProtectionDomainCacheTable", gc_timer);
1886     // Oops referenced by the protection domain cache table may get unreachable independently
1887     // of the class loader (eg. cached protection domain oops). So we need to
1888     // explicitly unlink them here.
1889     _pd_cache_table->trigger_cleanup();
1890   }
1891 
1892   if (do_cleaning) {
1893     GCTraceTime(Debug, gc, phases) t("ResolvedMethodTable", gc_timer);
1894     ResolvedMethodTable::trigger_cleanup();
1895   }
1896 
1897   return unloading_occurred;
1898 }
1899 
1900 void SystemDictionary::oops_do(OopClosure* f) {
1901   f->do_oop(&_java_system_loader);
1902   f->do_oop(&_java_platform_loader);
1903   f->do_oop(&_system_loader_lock_obj);
1904   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1905 
1906   // Visit extra methods
1907   invoke_method_table()->oops_do(f);
1908 }
1909 
1910 // CDS: scan and relocate all classes in the system dictionary.
1911 void SystemDictionary::classes_do(MetaspaceClosure* it) {
1912   ClassLoaderData::the_null_class_loader_data()->dictionary()->classes_do(it);
1913 }
1914 
1915 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1916 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1917   for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1918     it->push(well_known_klass_addr((WKID)id));
1919   }
1920 }
1921 
1922 void SystemDictionary::methods_do(void f(Method*)) {
1923   // Walk methods in loaded classes
1924   MutexLocker ml(ClassLoaderDataGraph_lock);
1925   ClassLoaderDataGraph::methods_do(f);
1926   // Walk method handle intrinsics
1927   invoke_method_table()->methods_do(f);
1928 }
1929 
1930 class RemoveClassesClosure : public CLDClosure {
1931   public:
1932     void do_cld(ClassLoaderData* cld) {
1933       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
1934         cld->dictionary()->remove_classes_in_error_state();
1935       }
1936     }
1937 };
1938 
1939 void SystemDictionary::remove_classes_in_error_state() {
1940   ClassLoaderData::the_null_class_loader_data()->dictionary()->remove_classes_in_error_state();
1941   RemoveClassesClosure rcc;
1942   MutexLocker ml(ClassLoaderDataGraph_lock);
1943   ClassLoaderDataGraph::cld_do(&rcc);
1944 }
1945 
1946 // ----------------------------------------------------------------------------
1947 // Initialization
1948 
1949 void SystemDictionary::initialize(TRAPS) {
1950   // Allocate arrays
1951   _placeholders        = new PlaceholderTable(_placeholder_table_size);
1952   _number_of_modifications = 0;
1953   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1954   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1955   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1956   _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1957 
1958   // Allocate private object used as system class loader lock
1959   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1960   // Initialize basic classes
1961   resolve_preloaded_classes(CHECK);
1962 }
1963 
1964 // Compact table of directions on the initialization of klasses:
1965 static const short wk_init_info[] = {
1966   #define WK_KLASS_INIT_INFO(name, symbol) \
1967     ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
1968 
1969   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1970   #undef WK_KLASS_INIT_INFO
1971   0
1972 };
1973 
















1974 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
1975   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1976   int sid = wk_init_info[id - FIRST_WKID];
1977   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1978   InstanceKlass** klassp = &_well_known_klasses[id];
1979 
1980 
1981 #if INCLUDE_JVMCI
1982   if (id >= FIRST_JVMCI_WKID) {
1983     assert(EnableJVMCI, "resolve JVMCI classes only when EnableJVMCI is true");
1984   }
1985 #endif
1986 
1987   if ((*klassp) == NULL) {
1988     Klass* k = resolve_or_fail(symbol, true, CHECK_0);
1989     (*klassp) = InstanceKlass::cast(k);
1990   }
1991   return ((*klassp) != NULL);
1992 }
1993 
1994 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1995   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1996   for (int id = (int)start_id; id < (int)limit_id; id++) {
1997     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1998     resolve_wk_klass((WKID)id, CHECK);
1999   }
2000 
2001   // move the starting value forward to the limit:
2002   start_id = limit_id;
2003 }
2004 
2005 void SystemDictionary::resolve_preloaded_classes(TRAPS) {
2006   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
2007 
2008   // Create the ModuleEntry for java.base.  This call needs to be done here,
2009   // after vmSymbols::initialize() is called but before any classes are pre-loaded.
2010   ClassLoader::classLoader_init2(CHECK);
2011 
2012   // Preload commonly used klasses
2013   WKID scan = FIRST_WKID;
2014   // first do Object, then String, Class
2015 #if INCLUDE_CDS
2016   if (UseSharedSpaces) {
2017     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
2018 
2019     // It's unsafe to access the archived heap regions before they
2020     // are fixed up, so we must do the fixup as early as possible
2021     // before the archived java objects are accessed by functions
2022     // such as java_lang_Class::restore_archived_mirror and
2023     // ConstantPool::restore_unshareable_info (restores the archived
2024     // resolved_references array object).
2025     //
2026     // HeapShared::fixup_mapped_heap_regions() fills the empty
2027     // spaces in the archived heap regions and may use
2028     // SystemDictionary::Object_klass(), so we can do this only after
2029     // Object_klass is resolved. See the above resolve_wk_klasses_through()
2030     // call. No mirror objects are accessed/restored in the above call.
2031     // Mirrors are restored after java.lang.Class is loaded.
2032     HeapShared::fixup_mapped_heap_regions();
2033 
2034     // Initialize the constant pool for the Object_class
2035     Object_klass()->constants()->restore_unshareable_info(CHECK);
2036     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2037   } else
2038 #endif
2039   {
2040     resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2041   }
2042 
2043   // Calculate offsets for String and Class classes since they are loaded and
2044   // can be used after this point.
2045   java_lang_String::compute_offsets();
2046   java_lang_Class::compute_offsets();
2047 
2048   // Fixup mirrors for classes loaded before java.lang.Class.
2049   // These calls iterate over the objects currently in the perm gen
2050   // so calling them at this point is matters (not before when there
2051   // are fewer objects and not later after there are more objects
2052   // in the perm gen.
2053   Universe::initialize_basic_type_mirrors(CHECK);
2054   Universe::fixup_mirrors(CHECK);
2055 
2056   // do a bunch more:
2057   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2058 
2059   // Preload ref klasses and set reference types
2060   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
2061   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2062 
2063   resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2064   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
2065   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
2066   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
2067   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
2068 
2069   // JSR 292 classes
2070   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2071   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2072   resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
2073   resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
2074   resolve_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);

2075 
2076   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2077   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
2078   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
2079   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
2080   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
2081   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
2082   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
2083   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
2084   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
2085   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
2086 
2087   { // Compute whether we should use checkPackageAccess or NOT
2088     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2089     _has_checkPackageAccess = (method != NULL);









2090   }
2091 }
2092 
2093 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2094 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
2095 BasicType SystemDictionary::box_klass_type(Klass* k) {
2096   assert(k != NULL, "");
2097   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2098     if (_box_klasses[i] == k)
2099       return (BasicType)i;
2100   }
2101   return T_OBJECT;
2102 }
2103 
2104 // Constraints on class loaders. The details of the algorithm can be
2105 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2106 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
2107 // that the dictionary needs to maintain a set of contraints that
2108 // must be satisfied by all classes in the dictionary.
2109 // if defining is true, then LinkageError if already in dictionary
2110 // if initiating loader, then ok if InstanceKlass matches existing entry
2111 
2112 void SystemDictionary::check_constraints(unsigned int d_hash,
2113                                          InstanceKlass* k,
2114                                          Handle class_loader,
2115                                          bool defining,
2116                                          TRAPS) {
2117   ResourceMark rm(THREAD);
2118   stringStream ss;
2119   bool throwException = false;
2120 
2121   {
2122     Symbol *name = k->name();
2123     ClassLoaderData *loader_data = class_loader_data(class_loader);
2124 
2125     MutexLocker mu(SystemDictionary_lock, THREAD);
2126 
2127     InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2128     if (check != NULL) {
2129       // If different InstanceKlass - duplicate class definition,
2130       // else - ok, class loaded by a different thread in parallel.
2131       // We should only have found it if it was done loading and ok to use.
2132       // The dictionary only holds instance classes, placeholders
2133       // also hold array classes.
2134 
2135       assert(check->is_instance_klass(), "noninstance in systemdictionary");
2136       if ((defining == true) || (k != check)) {
2137         throwException = true;
2138         ss.print("loader %s", loader_data->loader_name_and_id());
2139         ss.print(" attempted duplicate %s definition for %s. (%s)",
2140                  k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
2141       } else {
2142         return;
2143       }
2144     }
2145 
2146 #ifdef ASSERT
2147     Symbol* ph_check = find_placeholder(name, loader_data);
2148     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2149 #endif
2150 
2151     if (throwException == false) {
2152       if (constraints()->check_or_update(k, class_loader, name) == false) {
2153         throwException = true;
2154         ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
2155         ss.print(" wants to load %s %s.",
2156                  k->external_kind(), k->external_name());
2157         Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2158         if (existing_klass->class_loader() != class_loader()) {
2159           ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
2160                    existing_klass->external_kind(),
2161                    existing_klass->class_loader_data()->loader_name_and_id(),
2162                    existing_klass->class_in_module_of_loader(false, true));
2163         } else {
2164           ss.print(" (%s)", k->class_in_module_of_loader(false, true));
2165         }
2166       }
2167     }
2168   }
2169 
2170   // Throw error now if needed (cannot throw while holding
2171   // SystemDictionary_lock because of rank ordering)
2172   if (throwException == true) {
2173     THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2174   }
2175 }
2176 
2177 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2178 // have been called.
2179 void SystemDictionary::update_dictionary(unsigned int d_hash,
2180                                          int p_index, unsigned int p_hash,
2181                                          InstanceKlass* k,
2182                                          Handle class_loader,
2183                                          TRAPS) {
2184   // Compile_lock prevents systemDictionary updates during compilations
2185   assert_locked_or_safepoint(Compile_lock);
2186   Symbol*  name  = k->name();
2187   ClassLoaderData *loader_data = class_loader_data(class_loader);
2188 
2189   {
2190     MutexLocker mu1(SystemDictionary_lock, THREAD);
2191 
2192     // See whether biased locking is enabled and if so set it for this
2193     // klass.
2194     // Note that this must be done past the last potential blocking
2195     // point / safepoint. We enable biased locking lazily using a
2196     // VM_Operation to iterate the SystemDictionary and installing the
2197     // biasable mark word into each InstanceKlass's prototype header.
2198     // To avoid race conditions where we accidentally miss enabling the
2199     // optimization for one class in the process of being added to the
2200     // dictionary, we must not safepoint after the test of
2201     // BiasedLocking::enabled().
2202     if (UseBiasedLocking && BiasedLocking::enabled()) {
2203       // Set biased locking bit for all loaded classes; it will be
2204       // cleared if revocation occurs too often for this type
2205       // NOTE that we must only do this when the class is initally
2206       // defined, not each time it is referenced from a new class loader
2207       if (oopDesc::equals(k->class_loader(), class_loader())) {
2208         k->set_prototype_header(markOopDesc::biased_locking_prototype());
2209       }
2210     }
2211 
2212     // Make a new dictionary entry.
2213     Dictionary* dictionary = loader_data->dictionary();
2214     InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2215     if (sd_check == NULL) {
2216       dictionary->add_klass(d_hash, name, k);
2217       notice_modification();
2218     }
2219   #ifdef ASSERT
2220     sd_check = find_class(d_hash, name, dictionary);
2221     assert (sd_check != NULL, "should have entry in dictionary");
2222     // Note: there may be a placeholder entry: for circularity testing
2223     // or for parallel defines
2224   #endif
2225     SystemDictionary_lock->notify_all();
2226   }
2227 }
2228 
2229 
2230 // Try to find a class name using the loader constraints.  The
2231 // loader constraints might know about a class that isn't fully loaded
2232 // yet and these will be ignored.
2233 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2234                     Symbol* class_name, Handle class_loader, TRAPS) {
2235 
2236   // First see if it has been loaded directly.
2237   // Force the protection domain to be null.  (This removes protection checks.)
2238   Handle no_protection_domain;
2239   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2240                                               no_protection_domain, CHECK_NULL);
2241   if (klass != NULL)
2242     return klass;
2243 
2244   // Now look to see if it has been loaded elsewhere, and is subject to
2245   // a loader constraint that would require this loader to return the
2246   // klass that is already loaded.
2247   if (FieldType::is_array(class_name)) {
2248     // For array classes, their Klass*s are not kept in the
2249     // constraint table. The element Klass*s are.
2250     FieldArrayInfo fd;
2251     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2252     if (t != T_OBJECT) {
2253       klass = Universe::typeArrayKlassObj(t);
2254     } else {
2255       MutexLocker mu(SystemDictionary_lock, THREAD);
2256       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2257     }
2258     // If element class already loaded, allocate array klass
2259     if (klass != NULL) {
2260       klass = klass->array_klass_or_null(fd.dimension());
2261     }
2262   } else {
2263     MutexLocker mu(SystemDictionary_lock, THREAD);
2264     // Non-array classes are easy: simply check the constraint table.
2265     klass = constraints()->find_constrained_klass(class_name, class_loader);
2266   }
2267 
2268   return klass;
2269 }
2270 
2271 
2272 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2273                                              Handle class_loader1,
2274                                              Handle class_loader2,
2275                                              Thread* THREAD) {
2276   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2277   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2278 
2279   Symbol* constraint_name = NULL;
2280   // Needs to be in same scope as constraint_name in case a Symbol is created and
2281   // assigned to constraint_name.
2282   FieldArrayInfo fd;
2283   if (!FieldType::is_array(class_name)) {
2284     constraint_name = class_name;
2285   } else {
2286     // For array classes, their Klass*s are not kept in the
2287     // constraint table. The element classes are.
2288     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2289     // primitive types always pass
2290     if (t != T_OBJECT) {
2291       return true;
2292     } else {
2293       constraint_name = fd.object_key();
2294     }
2295   }
2296 
2297   Dictionary* dictionary1 = loader_data1->dictionary();
2298   unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2299 
2300   Dictionary* dictionary2 = loader_data2->dictionary();
2301   unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2302 
2303   {
2304     MutexLocker mu_s(SystemDictionary_lock, THREAD);
2305     InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2306     InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2307     return constraints()->add_entry(constraint_name, klass1, class_loader1,
2308                                     klass2, class_loader2);
2309   }
2310 }
2311 
2312 // Add entry to resolution error table to record the error when the first
2313 // attempt to resolve a reference to a class has failed.
2314 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2315                                             Symbol* error, Symbol* message) {
2316   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2317   int index = resolution_errors()->hash_to_index(hash);
2318   {
2319     MutexLocker ml(SystemDictionary_lock, Thread::current());
2320     resolution_errors()->add_entry(index, hash, pool, which, error, message);
2321   }
2322 }
2323 
2324 // Delete a resolution error for RedefineClasses for a constant pool is going away
2325 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2326   resolution_errors()->delete_entry(pool);
2327 }
2328 
2329 // Lookup resolution error table. Returns error if found, otherwise NULL.
2330 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2331                                                 Symbol** message) {
2332   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2333   int index = resolution_errors()->hash_to_index(hash);
2334   {
2335     MutexLocker ml(SystemDictionary_lock, Thread::current());
2336     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2337     if (entry != NULL) {
2338       *message = entry->message();
2339       return entry->error();
2340     } else {
2341       return NULL;
2342     }
2343   }
2344 }
2345 
2346 
2347 // Signature constraints ensure that callers and callees agree about
2348 // the meaning of type names in their signatures.  This routine is the
2349 // intake for constraints.  It collects them from several places:
2350 //
2351 //  * LinkResolver::resolve_method (if check_access is true) requires
2352 //    that the resolving class (the caller) and the defining class of
2353 //    the resolved method (the callee) agree on each type in the
2354 //    method's signature.
2355 //
2356 //  * LinkResolver::resolve_interface_method performs exactly the same
2357 //    checks.
2358 //
2359 //  * LinkResolver::resolve_field requires that the constant pool
2360 //    attempting to link to a field agree with the field's defining
2361 //    class about the type of the field signature.
2362 //
2363 //  * klassVtable::initialize_vtable requires that, when a class
2364 //    overrides a vtable entry allocated by a superclass, that the
2365 //    overriding method (i.e., the callee) agree with the superclass
2366 //    on each type in the method's signature.
2367 //
2368 //  * klassItable::initialize_itable requires that, when a class fills
2369 //    in its itables, for each non-abstract method installed in an
2370 //    itable, the method (i.e., the callee) agree with the interface
2371 //    on each type in the method's signature.
2372 //
2373 // All those methods have a boolean (check_access, checkconstraints)
2374 // which turns off the checks.  This is used from specialized contexts
2375 // such as bootstrapping, dumping, and debugging.
2376 //
2377 // No direct constraint is placed between the class and its
2378 // supertypes.  Constraints are only placed along linked relations
2379 // between callers and callees.  When a method overrides or implements
2380 // an abstract method in a supertype (superclass or interface), the
2381 // constraints are placed as if the supertype were the caller to the
2382 // overriding method.  (This works well, since callers to the
2383 // supertype have already established agreement between themselves and
2384 // the supertype.)  As a result of all this, a class can disagree with
2385 // its supertype about the meaning of a type name, as long as that
2386 // class neither calls a relevant method of the supertype, nor is
2387 // called (perhaps via an override) from the supertype.
2388 //
2389 //
2390 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2391 //
2392 // Make sure all class components (including arrays) in the given
2393 // signature will be resolved to the same class in both loaders.
2394 // Returns the name of the type that failed a loader constraint check, or
2395 // NULL if no constraint failed.  No exception except OOME is thrown.
2396 // Arrays are not added to the loader constraint table, their elements are.
2397 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2398                                                Handle loader1, Handle loader2,
2399                                                bool is_method, TRAPS)  {
2400   // Nothing to do if loaders are the same.
2401   if (oopDesc::equals(loader1(), loader2())) {
2402     return NULL;
2403   }
2404 
2405   SignatureStream sig_strm(signature, is_method);
2406   while (!sig_strm.is_done()) {
2407     if (sig_strm.is_object()) {
2408       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2409       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2410         return sig;
2411       }
2412     }
2413     sig_strm.next();
2414   }
2415   return NULL;
2416 }
2417 
2418 
2419 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2420                                                             Symbol* signature,
2421                                                             TRAPS) {
2422   methodHandle empty;
2423   assert(MethodHandles::is_signature_polymorphic(iid) &&
2424          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2425          iid != vmIntrinsics::_invokeGeneric,
2426          "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2427 
2428   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2429   int          index = invoke_method_table()->hash_to_index(hash);
2430   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2431   methodHandle m;
2432   if (spe == NULL || spe->method() == NULL) {
2433     spe = NULL;
2434     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2435     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2436     if (!Arguments::is_interpreter_only()) {
2437       // Generate a compiled form of the MH intrinsic.
2438       AdapterHandlerLibrary::create_native_wrapper(m);
2439       // Check if have the compiled code.
2440       if (!m->has_compiled_code()) {
2441         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2442                    "Out of space in CodeCache for method handle intrinsic", empty);
2443       }
2444     }
2445     // Now grab the lock.  We might have to throw away the new method,
2446     // if a racing thread has managed to install one at the same time.
2447     {
2448       MutexLocker ml(SystemDictionary_lock, THREAD);
2449       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2450       if (spe == NULL)
2451         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2452       if (spe->method() == NULL)
2453         spe->set_method(m());
2454     }
2455   }
2456 
2457   assert(spe != NULL && spe->method() != NULL, "");
2458   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2459          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2460          "MH intrinsic invariant");
2461   return spe->method();
2462 }
2463 
2464 // Helper for unpacking the return value from linkMethod and linkCallSite.
2465 static methodHandle unpack_method_and_appendix(Handle mname,
2466                                                Klass* accessing_klass,
2467                                                objArrayHandle appendix_box,
2468                                                Handle* appendix_result,
2469                                                TRAPS) {
2470   methodHandle empty;
2471   if (mname.not_null()) {
2472     Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2473     if (m != NULL) {
2474       oop appendix = appendix_box->obj_at(0);
2475       if (TraceMethodHandles) {
2476     #ifndef PRODUCT
2477         ttyLocker ttyl;
2478         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2479         m->print();
2480         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2481         tty->cr();
2482     #endif //PRODUCT
2483       }
2484       (*appendix_result) = Handle(THREAD, appendix);
2485       // the target is stored in the cpCache and if a reference to this
2486       // MemberName is dropped we need a way to make sure the
2487       // class_loader containing this method is kept alive.
2488       ClassLoaderData* this_key = accessing_klass->class_loader_data();
2489       this_key->record_dependency(m->method_holder());
2490       return methodHandle(THREAD, m);
2491     }
2492   }
2493   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2494   return empty;
2495 }
2496 
2497 methodHandle SystemDictionary::find_method_handle_invoker(Klass* klass,
2498                                                           Symbol* name,
2499                                                           Symbol* signature,
2500                                                           Klass* accessing_klass,
2501                                                           Handle *appendix_result,
2502                                                           Handle *method_type_result,
2503                                                           TRAPS) {
2504   methodHandle empty;
2505   assert(THREAD->can_call_java() ,"");
2506   Handle method_type =
2507     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2508 
2509   int ref_kind = JVM_REF_invokeVirtual;
2510   oop name_oop = StringTable::intern(name, CHECK_(empty));
2511   Handle name_str (THREAD, name_oop);
2512   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2513   assert(appendix_box->obj_at(0) == NULL, "");
2514 
2515   // This should not happen.  JDK code should take care of that.
2516   if (accessing_klass == NULL || method_type.is_null()) {
2517     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2518   }
2519 
2520   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2521   JavaCallArguments args;
2522   args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2523   args.push_int(ref_kind);
2524   args.push_oop(Handle(THREAD, klass->java_mirror()));
2525   args.push_oop(name_str);
2526   args.push_oop(method_type);
2527   args.push_oop(appendix_box);
2528   JavaValue result(T_OBJECT);
2529   JavaCalls::call_static(&result,
2530                          SystemDictionary::MethodHandleNatives_klass(),
2531                          vmSymbols::linkMethod_name(),
2532                          vmSymbols::linkMethod_signature(),
2533                          &args, CHECK_(empty));
2534   Handle mname(THREAD, (oop) result.get_jobject());
2535   (*method_type_result) = method_type;
2536   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2537 }
2538 
2539 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2540 // We must ensure that all class loaders everywhere will reach this class, for any client.
2541 // This is a safe bet for public classes in java.lang, such as Object and String.
2542 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2543 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2544 static bool is_always_visible_class(oop mirror) {
2545   Klass* klass = java_lang_Class::as_Klass(mirror);
2546   if (klass->is_objArray_klass()) {
2547     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2548   }
2549   if (klass->is_typeArray_klass()) {
2550     return true; // primitive array
2551   }
2552   assert(klass->is_instance_klass(), "%s", klass->external_name());
2553   return klass->is_public() &&
2554          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2555           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2556 }
2557 
2558 
2559 // Return the Java mirror (java.lang.Class instance) for a single-character
2560 // descriptor.  This result, when available, is the same as produced by the
2561 // heavier API point of the same name that takes a Symbol.
2562 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2563   return java_lang_Class::primitive_mirror(char2type(signature_char));
2564 }
2565 
2566 // Find or construct the Java mirror (java.lang.Class instance) for a
2567 // for the given field type signature, as interpreted relative to the
2568 // given class loader.  Handles primitives, void, references, arrays,
2569 // and all other reflectable types, except method types.
2570 // N.B.  Code in reflection should use this entry point.
2571 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2572                                                    Klass* accessing_klass,
2573                                                    Handle class_loader,
2574                                                    Handle protection_domain,
2575                                                    SignatureStream::FailureMode failure_mode,
2576                                                    TRAPS) {
2577   Handle empty;
2578 
2579   assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2580          "one or the other, or perhaps neither");
2581 
2582   Symbol* type = signature;
2583 
2584   // What we have here must be a valid field descriptor,
2585   // and all valid field descriptors are supported.
2586   // Produce the same java.lang.Class that reflection reports.
2587   if (type->utf8_length() == 1) {
2588 
2589     // It's a primitive.  (Void has a primitive mirror too.)
2590     char ch = type->char_at(0);
2591     assert(is_java_primitive(char2type(ch)) || ch == 'V', "");
2592     return Handle(THREAD, find_java_mirror_for_type(ch));
2593 
2594   } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2595 
2596     // It's a reference type.
2597     if (accessing_klass != NULL) {
2598       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2599       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2600     }
2601     Klass* constant_type_klass;
2602     if (failure_mode == SignatureStream::ReturnNull) {
2603       constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2604                                             CHECK_(empty));
2605     } else {
2606       bool throw_error = (failure_mode == SignatureStream::NCDFError);
2607       constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2608                                             throw_error, CHECK_(empty));
2609     }
2610     if (constant_type_klass == NULL) {
2611       return Handle();  // report failure this way
2612     }
2613     Handle mirror(THREAD, constant_type_klass->java_mirror());
2614 
2615     // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2616     if (accessing_klass != NULL) {
2617       Klass* sel_klass = constant_type_klass;
2618       bool fold_type_to_class = true;
2619       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2620                                               fold_type_to_class, CHECK_(empty));
2621     }
2622 
2623     return mirror;
2624 
2625   }
2626 
2627   // Fall through to an error.
2628   assert(false, "unsupported mirror syntax");
2629   THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2630 }
2631 
2632 
2633 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2634 // signature, as interpreted relative to the given class loader.
2635 // Because of class loader constraints, all method handle usage must be
2636 // consistent with this loader.
2637 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2638                                                  Klass* accessing_klass,
2639                                                  TRAPS) {
2640   Handle empty;
2641   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2642   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2643   int          index = invoke_method_table()->hash_to_index(hash);
2644   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2645   if (spe != NULL && spe->method_type() != NULL) {
2646     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2647     return Handle(THREAD, spe->method_type());
2648   } else if (!THREAD->can_call_java()) {
2649     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2650     return Handle();  // do not attempt from within compiler, unless it was cached
2651   }
2652 
2653   Handle class_loader, protection_domain;
2654   if (accessing_klass != NULL) {
2655     class_loader      = Handle(THREAD, accessing_klass->class_loader());
2656     protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2657   }
2658   bool can_be_cached = true;
2659   int npts = ArgumentCount(signature).size();
2660   objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2661   int arg = 0;
2662   Handle rt; // the return type from the signature
2663   ResourceMark rm(THREAD);
2664   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2665     oop mirror = NULL;
2666     if (can_be_cached) {
2667       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2668       mirror = ss.as_java_mirror(Handle(), Handle(),
2669                                  SignatureStream::ReturnNull, CHECK_(empty));
2670       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2671         // Fall back to accessing_klass context.
2672         can_be_cached = false;
2673       }
2674     }
2675     if (!can_be_cached) {
2676       // Resolve, throwing a real error if it doesn't work.
2677       mirror = ss.as_java_mirror(class_loader, protection_domain,
2678                                  SignatureStream::NCDFError, CHECK_(empty));
2679     }
2680     assert(mirror != NULL, "%s", ss.as_symbol(THREAD)->as_C_string());
2681     if (ss.at_return_type())
2682       rt = Handle(THREAD, mirror);
2683     else
2684       pts->obj_at_put(arg++, mirror);
2685 
2686     // Check accessibility.
2687     if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2688       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2689       mirror = NULL;  // safety
2690       // Emulate ConstantPool::verify_constant_pool_resolve.
2691       bool fold_type_to_class = true;
2692       LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2693                                               fold_type_to_class, CHECK_(empty));
2694     }
2695   }
2696   assert(arg == npts, "");
2697 
2698   // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2699   JavaCallArguments args(Handle(THREAD, rt()));
2700   args.push_oop(pts);
2701   JavaValue result(T_OBJECT);
2702   JavaCalls::call_static(&result,
2703                          SystemDictionary::MethodHandleNatives_klass(),
2704                          vmSymbols::findMethodHandleType_name(),
2705                          vmSymbols::findMethodHandleType_signature(),
2706                          &args, CHECK_(empty));
2707   Handle method_type(THREAD, (oop) result.get_jobject());
2708 
2709   if (can_be_cached) {
2710     // We can cache this MethodType inside the JVM.
2711     MutexLocker ml(SystemDictionary_lock, THREAD);
2712     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2713     if (spe == NULL)
2714       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2715     if (spe->method_type() == NULL) {
2716       spe->set_method_type(method_type());
2717     }
2718   }
2719 
2720   // report back to the caller with the MethodType
2721   return method_type;
2722 }
2723 
2724 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2725                                                 Klass* accessing_klass,
2726                                                 TRAPS) {
2727   Handle empty;
2728   ResourceMark rm(THREAD);
2729   SignatureStream ss(signature, /*is_method=*/ false);
2730   if (!ss.is_done()) {
2731     Handle class_loader, protection_domain;
2732     if (accessing_klass != NULL) {
2733       class_loader      = Handle(THREAD, accessing_klass->class_loader());
2734       protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2735     }
2736     oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2737     ss.next();
2738     if (ss.is_done()) {
2739       return Handle(THREAD, mirror);
2740     }
2741   }
2742   return empty;
2743 }
2744 
2745 // Ask Java code to find or construct a method handle constant.
2746 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2747                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2748                                                      Klass* callee,
2749                                                      Symbol* name,
2750                                                      Symbol* signature,
2751                                                      TRAPS) {
2752   Handle empty;
2753   if (caller == NULL) {
2754     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2755   }
2756   Handle name_str      = java_lang_String::create_from_symbol(name,      CHECK_(empty));
2757   Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2758 
2759   // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2760   Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2761   java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2762   java_lang_invoke_MemberName::set_name (mname(), name_str());
2763   java_lang_invoke_MemberName::set_type (mname(), signature_str());
2764   java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2765 
2766   if (ref_kind == JVM_REF_invokeVirtual &&
2767       MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2768     // Skip resolution for public signature polymorphic methods such as
2769     // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2770     // They require appendix argument which MemberName resolution doesn't handle.
2771     // There's special logic on JDK side to handle them
2772     // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2773   } else {
2774     MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2775   }
2776 
2777   // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2778   Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2779 
2780   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2781   JavaCallArguments args;
2782   args.push_oop(Handle(THREAD, caller->java_mirror()));  // the referring class
2783   args.push_int(ref_kind);
2784   args.push_oop(Handle(THREAD, callee->java_mirror()));  // the target class
2785   args.push_oop(name_str);
2786   args.push_oop(type);
2787   JavaValue result(T_OBJECT);
2788   JavaCalls::call_static(&result,
2789                          SystemDictionary::MethodHandleNatives_klass(),
2790                          vmSymbols::linkMethodHandleConstant_name(),
2791                          vmSymbols::linkMethodHandleConstant_signature(),
2792                          &args, CHECK_(empty));
2793   return Handle(THREAD, (oop) result.get_jobject());
2794 }
2795 
2796 // Ask Java to compute a constant by invoking a BSM given a Dynamic_info CP entry
2797 Handle SystemDictionary::link_dynamic_constant(Klass* caller,
2798                                                int condy_index,
2799                                                Handle bootstrap_specifier,
2800                                                Symbol* name,
2801                                                Symbol* type,
2802                                                TRAPS) {
2803   Handle empty;
2804   Handle bsm, info;
2805   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2806     bsm = bootstrap_specifier;
2807   } else {
2808     assert(bootstrap_specifier->is_objArray(), "");
2809     objArrayOop args = (objArrayOop) bootstrap_specifier();
2810     assert(args->length() == 2, "");
2811     bsm  = Handle(THREAD, args->obj_at(0));
2812     info = Handle(THREAD, args->obj_at(1));
2813   }
2814   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2815             "caller must supply a valid BSM");
2816 
2817   // This should not happen.  JDK code should take care of that.
2818   if (caller == NULL) {
2819     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad dynamic constant", empty);
2820   }
2821 
2822   Handle constant_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2823 
2824   // Resolve the constant type in the context of the caller class
2825   Handle type_mirror = find_java_mirror_for_type(type, caller, SignatureStream::NCDFError,
2826                                                  CHECK_(empty));
2827 
2828   // call java.lang.invoke.MethodHandleNatives::linkConstantDyanmic(caller, condy_index, bsm, type, info)
2829   JavaCallArguments args;
2830   args.push_oop(Handle(THREAD, caller->java_mirror()));
2831   args.push_int(condy_index);
2832   args.push_oop(bsm);
2833   args.push_oop(constant_name);
2834   args.push_oop(type_mirror);
2835   args.push_oop(info);
2836   JavaValue result(T_OBJECT);
2837   JavaCalls::call_static(&result,
2838                          SystemDictionary::MethodHandleNatives_klass(),
2839                          vmSymbols::linkDynamicConstant_name(),
2840                          vmSymbols::linkDynamicConstant_signature(),
2841                          &args, CHECK_(empty));
2842 
2843   return Handle(THREAD, (oop) result.get_jobject());
2844 }
2845 
2846 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2847 // name and signature, as interpreted relative to the given class loader.
2848 methodHandle SystemDictionary::find_dynamic_call_site_invoker(Klass* caller,
2849                                                               int indy_index,
2850                                                               Handle bootstrap_specifier,
2851                                                               Symbol* name,
2852                                                               Symbol* type,
2853                                                               Handle *appendix_result,
2854                                                               Handle *method_type_result,
2855                                                               TRAPS) {
2856   methodHandle empty;
2857   Handle bsm, info;
2858   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2859     bsm = bootstrap_specifier;
2860   } else {
2861     objArrayOop args = (objArrayOop) bootstrap_specifier();
2862     assert(args->length() == 2, "");
2863     bsm  = Handle(THREAD, args->obj_at(0));
2864     info = Handle(THREAD, args->obj_at(1));
2865   }
2866   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2867             "caller must supply a valid BSM");
2868 
2869   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2870   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2871 
2872   // This should not happen.  JDK code should take care of that.
2873   if (caller == NULL || method_type.is_null()) {
2874     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2875   }
2876 
2877   objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2878   assert(appendix_box->obj_at(0) == NULL, "");
2879 
2880   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2881   JavaCallArguments args;
2882   args.push_oop(Handle(THREAD, caller->java_mirror()));
2883   args.push_int(indy_index);
2884   args.push_oop(bsm);
2885   args.push_oop(method_name);
2886   args.push_oop(method_type);
2887   args.push_oop(info);
2888   args.push_oop(appendix_box);
2889   JavaValue result(T_OBJECT);
2890   JavaCalls::call_static(&result,
2891                          SystemDictionary::MethodHandleNatives_klass(),
2892                          vmSymbols::linkCallSite_name(),
2893                          vmSymbols::linkCallSite_signature(),
2894                          &args, CHECK_(empty));
2895   Handle mname(THREAD, (oop) result.get_jobject());
2896   (*method_type_result) = method_type;
2897   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2898 }
2899 
2900 // Protection domain cache table handling
2901 
2902 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2903   return _pd_cache_table->get(protection_domain);
2904 }
2905 
2906 #if INCLUDE_CDS
2907 void SystemDictionary::reorder_dictionary_for_sharing() {
2908   ClassLoaderData::the_null_class_loader_data()->dictionary()->reorder_dictionary_for_sharing();
2909 }
2910 #endif
2911 
2912 size_t SystemDictionary::count_bytes_for_buckets() {
2913   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_buckets();
2914 }
2915 
2916 size_t SystemDictionary::count_bytes_for_table() {
2917   return ClassLoaderData::the_null_class_loader_data()->dictionary()->count_bytes_for_table();
2918 }
2919 
2920 void SystemDictionary::copy_buckets(char* top, char* end) {
2921   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_buckets(top, end);
2922 }
2923 
2924 void SystemDictionary::copy_table(char* top, char* end) {
2925   ClassLoaderData::the_null_class_loader_data()->dictionary()->copy_table(top, end);
2926 }
2927 
2928 // ----------------------------------------------------------------------------
2929 void SystemDictionary::print_shared(outputStream *st) {
2930   shared_dictionary()->print_on(st);
2931 }
2932 
2933 void SystemDictionary::print_on(outputStream *st) {
2934   if (shared_dictionary() != NULL) {
2935     st->print_cr("Shared Dictionary");
2936     shared_dictionary()->print_on(st);
2937     st->cr();
2938   }
2939 
2940   GCMutexLocker mu(SystemDictionary_lock);
2941 
2942   ClassLoaderDataGraph::print_dictionary(st);
2943 
2944   // Placeholders
2945   placeholders()->print_on(st);
2946   st->cr();
2947 
2948   // loader constraints - print under SD_lock
2949   constraints()->print_on(st);
2950   st->cr();
2951 
2952   _pd_cache_table->print_on(st);
2953   st->cr();
2954 }
2955 
2956 void SystemDictionary::verify() {
2957   guarantee(constraints() != NULL,
2958             "Verify of loader constraints failed");
2959   guarantee(placeholders()->number_of_entries() >= 0,
2960             "Verify of placeholders failed");
2961 
2962   GCMutexLocker mu(SystemDictionary_lock);
2963 
2964   // Verify dictionary
2965   ClassLoaderDataGraph::verify_dictionary();
2966 
2967   placeholders()->verify();
2968 
2969   // Verify constraint table
2970   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2971   constraints()->verify(placeholders());
2972 
2973   _pd_cache_table->verify();
2974 }
2975 
2976 void SystemDictionary::dump(outputStream *st, bool verbose) {
2977   assert_locked_or_safepoint(SystemDictionary_lock);
2978   if (verbose) {
2979     print_on(st);
2980   } else {
2981     if (shared_dictionary() != NULL) {
2982       shared_dictionary()->print_table_statistics(st, "Shared Dictionary");
2983     }
2984     ClassLoaderDataGraph::print_dictionary_statistics(st);
2985     placeholders()->print_table_statistics(st, "Placeholder Table");
2986     constraints()->print_table_statistics(st, "LoaderConstraints Table");
2987     _pd_cache_table->print_table_statistics(st, "ProtectionDomainCache Table");
2988   }
2989 }
2990 
2991 // Utility for dumping dictionaries.
2992 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2993                                  DCmdWithParser(output, heap),
2994   _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2995            "BOOLEAN", false, "false") {
2996   _dcmdparser.add_dcmd_option(&_verbose);
2997 }
2998 
2999 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
3000   VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
3001                          _verbose.value());
3002   VMThread::execute(&dumper);
3003 }
3004 
3005 int SystemDictionaryDCmd::num_arguments() {
3006   ResourceMark rm;
3007   SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
3008   if (dcmd != NULL) {
3009     DCmdMark mark(dcmd);
3010     return dcmd->_dcmdparser.num_arguments();
3011   } else {
3012     return 0;
3013   }
3014 }
3015 
3016 class CombineDictionariesClosure : public CLDClosure {
3017   private:
3018     Dictionary* _master_dictionary;
3019   public:
3020     CombineDictionariesClosure(Dictionary* master_dictionary) :
3021       _master_dictionary(master_dictionary) {}
3022     void do_cld(ClassLoaderData* cld) {
3023       ResourceMark rm;
3024       if (cld->is_unsafe_anonymous()) {
3025         return;
3026       }
3027       if (cld->is_system_class_loader_data() || cld->is_platform_class_loader_data()) {
3028         for (int i = 0; i < cld->dictionary()->table_size(); ++i) {
3029           Dictionary* curr_dictionary = cld->dictionary();
3030           DictionaryEntry* p = curr_dictionary->bucket(i);
3031           while (p != NULL) {
3032             Symbol* name = p->instance_klass()->name();
3033             unsigned int d_hash = _master_dictionary->compute_hash(name);
3034             int d_index = _master_dictionary->hash_to_index(d_hash);
3035             DictionaryEntry* next = p->next();
3036             if (p->literal()->class_loader_data() != cld) {
3037               // This is an initiating class loader entry; don't use it
3038               log_trace(cds)("Skipping initiating cl entry: %s", name->as_C_string());
3039               curr_dictionary->free_entry(p);
3040             } else {
3041               log_trace(cds)("Moved to boot dictionary: %s", name->as_C_string());
3042               curr_dictionary->unlink_entry(p);
3043               p->set_pd_set(NULL); // pd_set is runtime only information and will be reconstructed.
3044               _master_dictionary->add_entry(d_index, p);
3045             }
3046             p = next;
3047           }
3048           *curr_dictionary->bucket_addr(i) = NULL;
3049         }
3050       }
3051     }
3052 };
3053 
3054 // Combining platform and system loader dictionaries into boot loader dictionary.
3055 // During run time, we only have one shared dictionary.
3056 void SystemDictionary::combine_shared_dictionaries() {
3057   assert(DumpSharedSpaces, "dump time only");
3058   Dictionary* master_dictionary = ClassLoaderData::the_null_class_loader_data()->dictionary();
3059   CombineDictionariesClosure cdc(master_dictionary);
3060   ClassLoaderDataGraph::cld_do(&cdc);
3061 
3062   // These tables are no longer valid or necessary. Keeping them around will
3063   // cause SystemDictionary::verify() to fail. Let's empty them.
3064   _placeholders        = new PlaceholderTable(_placeholder_table_size);
3065   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
3066 
3067   NOT_PRODUCT(SystemDictionary::verify());
3068 }
3069 
3070 void SystemDictionary::initialize_oop_storage() {
3071   _vm_weak_oop_storage =
3072     new OopStorage("VM Weak Oop Handles",
3073                    VMWeakAlloc_lock,
3074                    VMWeakActive_lock);
3075 }
3076 
3077 OopStorage* SystemDictionary::vm_weak_oop_storage() {
3078   assert(_vm_weak_oop_storage != NULL, "Uninitialized");
3079   return _vm_weak_oop_storage;
3080 }
--- EOF ---