1 /*
   2  * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderData.inline.hpp"
  27 #include "classfile/sharedClassUtil.hpp"
  28 #include "classfile/dictionary.hpp"
  29 #include "classfile/protectionDomainCache.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "classfile/systemDictionaryShared.hpp"
  32 #include "gc/shared/gcLocker.hpp"
  33 #include "logging/log.hpp"
  34 #include "logging/logStream.hpp"
  35 #include "memory/iterator.hpp"
  36 #include "memory/metaspaceClosure.hpp"
  37 #include "memory/resourceArea.hpp"
  38 #include "oops/oop.inline.hpp"
  39 #include "runtime/atomic.hpp"
  40 #include "runtime/orderAccess.inline.hpp"
  41 #include "utilities/hashtable.inline.hpp"
  42 
  43 // Optimization: if any dictionary needs resizing, we set this flag,
  44 // so that we dont't have to walk all dictionaries to check if any actually
  45 // needs resizing, which is costly to do at Safepoint.
  46 bool Dictionary::_some_dictionary_needs_resizing = false;
  47 
  48 size_t Dictionary::entry_size() {
  49   if (DumpSharedSpaces) {
  50     return SystemDictionaryShared::dictionary_entry_size();
  51   } else {
  52     return sizeof(DictionaryEntry);
  53   }
  54 }
  55 
  56 Dictionary::Dictionary(ClassLoaderData* loader_data, int table_size, bool resizable)
  57   : _loader_data(loader_data), _resizable(resizable), _needs_resizing(false),
  58   Hashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size()) {
  59 };
  60 
  61 
  62 Dictionary::Dictionary(ClassLoaderData* loader_data,
  63                        int table_size, HashtableBucket<mtClass>* t,
  64                        int number_of_entries, bool resizable)
  65   : _loader_data(loader_data), _resizable(resizable), _needs_resizing(false),
  66   Hashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size(), t, number_of_entries) {
  67 };
  68 
  69 Dictionary::~Dictionary() {
  70   DictionaryEntry* probe = NULL;
  71   for (int index = 0; index < table_size(); index++) {
  72     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
  73       probe = *p;
  74       *p = probe->next();
  75       free_entry(probe);
  76     }
  77   }
  78   assert(number_of_entries() == 0, "should have removed all entries");
  79   assert(new_entry_free_list() == NULL, "entry present on Dictionary's free list");
  80   free_buckets();
  81 }
  82 
  83 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass) {
  84   DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::allocate_new_entry(hash, klass);
  85   entry->set_pd_set(NULL);
  86   assert(klass->is_instance_klass(), "Must be");
  87   if (DumpSharedSpaces) {
  88     SystemDictionaryShared::init_shared_dictionary_entry(klass, entry);
  89   }
  90   return entry;
  91 }
  92 
  93 
  94 void Dictionary::free_entry(DictionaryEntry* entry) {
  95   // avoid recursion when deleting linked list
  96   // pd_set is accessed during a safepoint.
  97   while (entry->pd_set() != NULL) {
  98     ProtectionDomainEntry* to_delete = entry->pd_set();
  99     entry->set_pd_set(to_delete->next());
 100     delete to_delete;
 101   }
 102   // Unlink from the Hashtable prior to freeing
 103   unlink_entry(entry);
 104   FREE_C_HEAP_ARRAY(char, entry);
 105 }
 106 
 107 const int _resize_load_trigger = 5;       // load factor that will trigger the resize
 108 const double _resize_factor    = 2.0;     // by how much we will resize using current number of entries
 109 const int _resize_max_size     = 40423;   // the max dictionary size allowed
 110 const int _primelist[] = {107, 1009, 2017, 4049, 5051, 10103, 20201, _resize_max_size};
 111 const int _prime_array_size = sizeof(_primelist)/sizeof(int);
 112 
 113 // Calculate next "good" dictionary size based on requested count
 114 static int calculate_dictionary_size(int requested) {
 115   int newsize = _primelist[0];
 116   int index = 0;
 117   for (newsize = _primelist[index]; index < (_prime_array_size - 1);
 118        newsize = _primelist[++index]) {
 119     if (requested <= newsize) {
 120       break;
 121     }
 122   }
 123   return newsize;
 124 }
 125 
 126 bool Dictionary::does_any_dictionary_needs_resizing() {
 127   return Dictionary::_some_dictionary_needs_resizing;
 128 }
 129 
 130 void Dictionary::check_if_needs_resize() {
 131   if (_resizable == true) {
 132     if (number_of_entries() > (_resize_load_trigger*table_size())) {
 133       _needs_resizing = true;
 134       Dictionary::_some_dictionary_needs_resizing = true;
 135     }
 136   }
 137 }
 138 
 139 bool Dictionary::resize_if_needed() {
 140   int desired_size = 0;
 141   if (_needs_resizing == true) {
 142     desired_size = calculate_dictionary_size((int)(_resize_factor*number_of_entries()));
 143     if (desired_size >= _resize_max_size) {
 144       desired_size = _resize_max_size;
 145       // We have reached the limit, turn resizing off
 146       _resizable = false;
 147     }
 148     if ((desired_size != 0) && (desired_size != table_size())) {
 149       if (!resize(desired_size)) {
 150         // Something went wrong, turn resizing off
 151         _resizable = false;
 152       }
 153     }
 154   }
 155 
 156   _needs_resizing = false;
 157   Dictionary::_some_dictionary_needs_resizing = false;
 158 
 159   return (desired_size != 0);
 160 }
 161 
 162 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
 163 #ifdef ASSERT
 164   if (protection_domain == instance_klass()->protection_domain()) {
 165     // Ensure this doesn't show up in the pd_set (invariant)
 166     bool in_pd_set = false;
 167     for (ProtectionDomainEntry* current = pd_set_acquire();
 168                                 current != NULL;
 169                                 current = current->next()) {
 170       if (current->protection_domain() == protection_domain) {
 171         in_pd_set = true;
 172         break;
 173       }
 174     }
 175     if (in_pd_set) {
 176       assert(false, "A klass's protection domain should not show up "
 177                     "in its sys. dict. PD set");
 178     }
 179   }
 180 #endif /* ASSERT */
 181 
 182   if (protection_domain == instance_klass()->protection_domain()) {
 183     // Succeeds trivially
 184     return true;
 185   }
 186 
 187   for (ProtectionDomainEntry* current = pd_set_acquire();
 188                               current != NULL;
 189                               current = current->next()) {
 190     if (current->protection_domain() == protection_domain) return true;
 191   }
 192   return false;
 193 }
 194 
 195 
 196 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {
 197   assert_locked_or_safepoint(SystemDictionary_lock);
 198   if (!contains_protection_domain(protection_domain())) {
 199     ProtectionDomainCacheEntry* entry = SystemDictionary::cache_get(protection_domain);
 200     ProtectionDomainEntry* new_head =
 201                 new ProtectionDomainEntry(entry, pd_set());
 202     // Warning: Preserve store ordering.  The SystemDictionary is read
 203     //          without locks.  The new ProtectionDomainEntry must be
 204     //          complete before other threads can be allowed to see it
 205     //          via a store to _pd_set.
 206     release_set_pd_set(new_head);
 207   }
 208   LogTarget(Trace, protectiondomain) lt;
 209   if (lt.is_enabled()) {
 210     LogStream ls(lt);
 211     print_count(&ls);
 212   }
 213 }
 214 
 215 
 216 void Dictionary::do_unloading() {
 217   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
 218 
 219   // The NULL class loader doesn't initiate loading classes from other class loaders
 220   if (loader_data() == ClassLoaderData::the_null_class_loader_data()) {
 221     return;
 222   }
 223 
 224   // Remove unloaded entries and classes from this dictionary
 225   DictionaryEntry* probe = NULL;
 226   for (int index = 0; index < table_size(); index++) {
 227     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
 228       probe = *p;
 229       InstanceKlass* ik = probe->instance_klass();
 230       ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
 231 
 232       // If the klass that this loader initiated is dead,
 233       // (determined by checking the defining class loader)
 234       // remove this entry.
 235       if (k_def_class_loader_data->is_unloading()) {
 236         assert(k_def_class_loader_data != loader_data(),
 237                "cannot have live defining loader and unreachable klass");
 238         *p = probe->next();
 239         free_entry(probe);
 240         continue;
 241       }
 242       p = probe->next_addr();
 243     }
 244   }
 245 }
 246 
 247 void Dictionary::remove_classes_in_error_state() {
 248   assert(DumpSharedSpaces, "supported only when dumping");
 249   DictionaryEntry* probe = NULL;
 250   for (int index = 0; index < table_size(); index++) {
 251     for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
 252       probe = *p;
 253       InstanceKlass* ik = probe->instance_klass();
 254       if (ik->is_in_error_state()) { // purge this entry
 255         *p = probe->next();
 256         free_entry(probe);
 257         ResourceMark rm;
 258         tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name());
 259         continue;
 260       }
 261 
 262       p = probe->next_addr();
 263     }
 264   }
 265 }
 266 
 267 //   Just the classes from defining class loaders
 268 void Dictionary::classes_do(void f(InstanceKlass*)) {
 269   for (int index = 0; index < table_size(); index++) {
 270     for (DictionaryEntry* probe = bucket(index);
 271                           probe != NULL;
 272                           probe = probe->next()) {
 273       InstanceKlass* k = probe->instance_klass();
 274       if (loader_data() == k->class_loader_data()) {
 275         f(k);
 276       }
 277     }
 278   }
 279 }
 280 
 281 // Added for initialize_itable_for_klass to handle exceptions
 282 //   Just the classes from defining class loaders
 283 void Dictionary::classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
 284   for (int index = 0; index < table_size(); index++) {
 285     for (DictionaryEntry* probe = bucket(index);
 286                           probe != NULL;
 287                           probe = probe->next()) {
 288       InstanceKlass* k = probe->instance_klass();
 289       if (loader_data() == k->class_loader_data()) {
 290         f(k, CHECK);
 291       }
 292     }
 293   }
 294 }
 295 
 296 // All classes, and their class loaders, including initiating class loaders
 297 void Dictionary::all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
 298   for (int index = 0; index < table_size(); index++) {
 299     for (DictionaryEntry* probe = bucket(index);
 300                           probe != NULL;
 301                           probe = probe->next()) {
 302       InstanceKlass* k = probe->instance_klass();
 303       f(k, loader_data());
 304     }
 305   }
 306 }
 307 
 308 // Used to scan and relocate the classes during CDS archive dump.
 309 void Dictionary::classes_do(MetaspaceClosure* it) {
 310   assert(DumpSharedSpaces, "dump-time only");
 311   for (int index = 0; index < table_size(); index++) {
 312     for (DictionaryEntry* probe = bucket(index);
 313                           probe != NULL;
 314                           probe = probe->next()) {
 315       it->push(probe->klass_addr());
 316       ((SharedDictionaryEntry*)probe)->metaspace_pointers_do(it);
 317     }
 318   }
 319 }
 320 
 321 
 322 
 323 // Add a loaded class to the dictionary.
 324 // Readers of the SystemDictionary aren't always locked, so _buckets
 325 // is volatile. The store of the next field in the constructor is
 326 // also cast to volatile;  we do this to ensure store order is maintained
 327 // by the compilers.
 328 
 329 void Dictionary::add_klass(unsigned int hash, Symbol* class_name,
 330                            InstanceKlass* obj) {
 331   assert_locked_or_safepoint(SystemDictionary_lock);
 332   assert(obj != NULL, "adding NULL obj");
 333   assert(obj->name() == class_name, "sanity check on name");
 334 
 335   DictionaryEntry* entry = new_entry(hash, obj);
 336   int index = hash_to_index(hash);
 337   add_entry(index, entry);
 338   check_if_needs_resize();
 339 }
 340 
 341 
 342 // This routine does not lock the dictionary.
 343 //
 344 // Since readers don't hold a lock, we must make sure that system
 345 // dictionary entries are only removed at a safepoint (when only one
 346 // thread is running), and are added to in a safe way (all links must
 347 // be updated in an MT-safe manner).
 348 //
 349 // Callers should be aware that an entry could be added just after
 350 // _buckets[index] is read here, so the caller will not see the new entry.
 351 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
 352                                        Symbol* class_name) {
 353   for (DictionaryEntry* entry = bucket(index);
 354                         entry != NULL;
 355                         entry = entry->next()) {
 356     if (entry->hash() == hash && entry->equals(class_name)) {
 357       if (!DumpSharedSpaces || SystemDictionaryShared::is_builtin(entry)) {
 358         return entry;
 359       }
 360     }
 361   }
 362   return NULL;
 363 }
 364 
 365 
 366 InstanceKlass* Dictionary::find(unsigned int hash, Symbol* name,
 367                                 Handle protection_domain) {
 368   NoSafepointVerifier nsv;
 369   
 370   int index = hash_to_index(hash);
 371   DictionaryEntry* entry = get_entry(index, hash, name);
 372   if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
 373     return entry->instance_klass();
 374   } else {
 375     return NULL;
 376   }
 377 }
 378 
 379 
 380 InstanceKlass* Dictionary::find_class(int index, unsigned int hash,
 381                                       Symbol* name) {
 382   assert_locked_or_safepoint(SystemDictionary_lock);
 383   assert (index == index_for(name), "incorrect index?");
 384 
 385   DictionaryEntry* entry = get_entry(index, hash, name);
 386   return (entry != NULL) ? entry->instance_klass() : NULL;
 387 }
 388 
 389 
 390 // Variant of find_class for shared classes.  No locking required, as
 391 // that table is static.
 392 
 393 InstanceKlass* Dictionary::find_shared_class(int index, unsigned int hash,
 394                                              Symbol* name) {
 395   assert (index == index_for(name), "incorrect index?");
 396 
 397   DictionaryEntry* entry = get_entry(index, hash, name);
 398   return (entry != NULL) ? entry->instance_klass() : NULL;
 399 }
 400 
 401 
 402 void Dictionary::add_protection_domain(int index, unsigned int hash,
 403                                        InstanceKlass* klass,
 404                                        Handle protection_domain,
 405                                        TRAPS) {
 406   Symbol*  klass_name = klass->name();
 407   DictionaryEntry* entry = get_entry(index, hash, klass_name);
 408 
 409   assert(entry != NULL,"entry must be present, we just created it");
 410   assert(protection_domain() != NULL,
 411          "real protection domain should be present");
 412 
 413   entry->add_protection_domain(this, protection_domain);
 414 
 415   assert(entry->contains_protection_domain(protection_domain()),
 416          "now protection domain should be present");
 417 }
 418 
 419 
 420 bool Dictionary::is_valid_protection_domain(unsigned int hash,
 421                                             Symbol* name,
 422                                             Handle protection_domain) {
 423   int index = hash_to_index(hash);
 424   DictionaryEntry* entry = get_entry(index, hash, name);
 425   return entry->is_valid_protection_domain(protection_domain);
 426 }
 427 
 428 
 429 void Dictionary::reorder_dictionary_for_sharing() {
 430 
 431   // Copy all the dictionary entries into a single master list.
 432 
 433   DictionaryEntry* master_list = NULL;
 434   for (int i = 0; i < table_size(); ++i) {
 435     DictionaryEntry* p = bucket(i);
 436     while (p != NULL) {
 437       DictionaryEntry* next = p->next();
 438       InstanceKlass*ik = p->instance_klass();
 439       // we cannot include signed classes in the archive because the certificates
 440       // used during dump time may be different than those used during
 441       // runtime (due to expiration, etc).
 442       if (ik->signers() != NULL) {
 443         ResourceMark rm;
 444         tty->print_cr("Preload Warning: Skipping %s from signed JAR",
 445                        ik->name()->as_C_string());
 446         free_entry(p);
 447       } else {
 448         p->set_next(master_list);
 449         master_list = p;
 450       }
 451       p = next;
 452     }
 453     set_entry(i, NULL);
 454   }
 455 
 456   // Add the dictionary entries back to the list in the correct buckets.
 457   while (master_list != NULL) {
 458     DictionaryEntry* p = master_list;
 459     master_list = master_list->next();
 460     p->set_next(NULL);
 461     Symbol* class_name = p->instance_klass()->name();
 462     // Since the null class loader data isn't copied to the CDS archive,
 463     // compute the hash with NULL for loader data.
 464     unsigned int hash = compute_hash(class_name);
 465     int index = hash_to_index(hash);
 466     p->set_hash(hash);
 467     p->set_next(bucket(index));
 468     set_entry(index, p);
 469   }
 470 }
 471 
 472 
 473 SymbolPropertyTable::SymbolPropertyTable(int table_size)
 474   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
 475 {
 476 }
 477 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
 478                                          int number_of_entries)
 479   : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
 480 {
 481 }
 482 
 483 
 484 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
 485                                                      Symbol* sym,
 486                                                      intptr_t sym_mode) {
 487   assert(index == index_for(sym, sym_mode), "incorrect index?");
 488   for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 489     if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
 490       return p;
 491     }
 492   }
 493   return NULL;
 494 }
 495 
 496 
 497 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
 498                                                     Symbol* sym, intptr_t sym_mode) {
 499   assert_locked_or_safepoint(SystemDictionary_lock);
 500   assert(index == index_for(sym, sym_mode), "incorrect index?");
 501   assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
 502 
 503   SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
 504   Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
 505   return p;
 506 }
 507 
 508 void SymbolPropertyTable::oops_do(OopClosure* f) {
 509   for (int index = 0; index < table_size(); index++) {
 510     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 511       if (p->method_type() != NULL) {
 512         f->do_oop(p->method_type_addr());
 513       }
 514     }
 515   }
 516 }
 517 
 518 void SymbolPropertyTable::methods_do(void f(Method*)) {
 519   for (int index = 0; index < table_size(); index++) {
 520     for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
 521       Method* prop = p->method();
 522       if (prop != NULL) {
 523         f((Method*)prop);
 524       }
 525     }
 526   }
 527 }
 528 
 529 
 530 // ----------------------------------------------------------------------------
 531 
 532 void Dictionary::print_on(outputStream* st) const {
 533   ResourceMark rm;
 534 
 535   assert(loader_data() != NULL, "loader data should not be null");
 536   st->print_cr("Java dictionary (table_size=%d, classes=%d)",
 537                table_size(), number_of_entries());
 538   st->print_cr("^ indicates that initiating loader is different from defining loader");
 539 
 540   for (int index = 0; index < table_size(); index++) {
 541     for (DictionaryEntry* probe = bucket(index);
 542                           probe != NULL;
 543                           probe = probe->next()) {
 544       Klass* e = probe->instance_klass();
 545       bool is_defining_class =
 546          (loader_data() == e->class_loader_data());
 547       st->print("%4d: %s%s, loader ", index, is_defining_class ? " " : "^", e->external_name());
 548       ClassLoaderData* loader_data = e->class_loader_data();
 549       if (loader_data == NULL) {
 550         // Shared class not restored yet in shared dictionary
 551         st->print("<shared, not restored>");
 552       } else {
 553         loader_data->print_value_on(st);
 554       }
 555       st->cr();
 556     }
 557   }
 558   tty->cr();
 559 }
 560 
 561 void DictionaryEntry::verify() {
 562   Klass* e = instance_klass();
 563   guarantee(e->is_instance_klass(),
 564                           "Verify of dictionary failed");
 565   e->verify();
 566   verify_protection_domain_set();
 567 }
 568 
 569 void Dictionary::verify() {
 570   guarantee(number_of_entries() >= 0, "Verify of dictionary failed");
 571 
 572   ClassLoaderData* cld = loader_data();
 573   // class loader must be present;  a null class loader is the
 574   // boostrap loader
 575   guarantee(cld != NULL || DumpSharedSpaces ||
 576             cld->class_loader() == NULL ||
 577             cld->class_loader()->is_instance(),
 578             "checking type of class_loader");
 579 
 580   ResourceMark rm;
 581   stringStream tempst;
 582   tempst.print("System Dictionary for %s", cld->loader_name());
 583   verify_table<DictionaryEntry>(tempst.as_string());
 584 }