1 /* 2 * Copyright (c) 2016, 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 "jni.h" 27 #include "classfile/classLoaderData.inline.hpp" 28 #include "classfile/javaClasses.inline.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "logging/log.hpp" 31 #include "memory/resourceArea.hpp" 32 #include "oops/oopHandle.inline.hpp" 33 #include "oops/symbol.hpp" 34 #include "runtime/handles.inline.hpp" 35 #include "runtime/safepoint.hpp" 36 #include "utilities/events.hpp" 37 #include "utilities/growableArray.hpp" 38 #include "utilities/hashtable.inline.hpp" 39 #include "utilities/ostream.hpp" 40 41 ModuleEntry* ModuleEntryTable::_javabase_module = NULL; 42 43 oop ModuleEntry::module() const { return _module.resolve(); } 44 45 void ModuleEntry::set_location(Symbol* location) { 46 if (_location != NULL) { 47 // _location symbol's refcounts are managed by ModuleEntry, 48 // must decrement the old one before updating. 49 _location->decrement_refcount(); 50 } 51 52 _location = location; 53 54 if (location != NULL) { 55 location->increment_refcount(); 56 } 57 } 58 59 bool ModuleEntry::is_non_jdk_module() { 60 ResourceMark rm; 61 if (location() != NULL) { 62 const char* loc = location()->as_C_string(); 63 if (strncmp(loc, "jrt:/java.", 10) != 0 && strncmp(loc, "jrt:/jdk.", 9) != 0) { 64 return true; 65 } 66 } 67 return false; 68 } 69 70 void ModuleEntry::set_version(Symbol* version) { 71 if (_version != NULL) { 72 // _version symbol's refcounts are managed by ModuleEntry, 73 // must decrement the old one before updating. 74 _version->decrement_refcount(); 75 } 76 77 _version = version; 78 79 if (version != NULL) { 80 version->increment_refcount(); 81 } 82 } 83 84 // Returns the shared ProtectionDomain 85 oop ModuleEntry::shared_protection_domain() { 86 return _pd.resolve(); 87 } 88 89 // Set the shared ProtectionDomain atomically 90 void ModuleEntry::set_shared_protection_domain(ClassLoaderData *loader_data, 91 Handle pd_h) { 92 // Create a handle for the shared ProtectionDomain and save it atomically. 93 // init_handle_locked checks if someone beats us setting the _pd cache. 94 loader_data->init_handle_locked(_pd, pd_h); 95 } 96 97 // Returns true if this module can read module m 98 bool ModuleEntry::can_read(ModuleEntry* m) const { 99 assert(m != NULL, "No module to lookup in this module's reads list"); 100 101 // Unnamed modules read everyone and all modules 102 // read java.base. If either of these conditions 103 // hold, readability has been established. 104 if (!this->is_named() || 105 (m == ModuleEntryTable::javabase_moduleEntry())) { 106 return true; 107 } 108 109 MutexLocker m1(Module_lock); 110 // This is a guard against possible race between agent threads that redefine 111 // or retransform classes in this module. Only one of them is adding the 112 // default read edges to the unnamed modules of the boot and app class loaders 113 // with an upcall to jdk.internal.module.Modules.transformedByAgent. 114 // At the same time, another thread can instrument the module classes by 115 // injecting dependencies that require the default read edges for resolution. 116 if (this->has_default_read_edges() && !m->is_named()) { 117 ClassLoaderData* cld = m->loader_data(); 118 if (cld->is_the_null_class_loader_data() || cld->is_system_class_loader_data()) { 119 return true; // default read edge 120 } 121 } 122 if (!has_reads_list()) { 123 return false; 124 } else { 125 return _reads->contains(m); 126 } 127 } 128 129 // Add a new module to this module's reads list 130 void ModuleEntry::add_read(ModuleEntry* m) { 131 // Unnamed module is special cased and can read all modules 132 if (!is_named()) { 133 return; 134 } 135 136 MutexLocker m1(Module_lock); 137 if (m == NULL) { 138 set_can_read_all_unnamed(); 139 } else { 140 if (_reads == NULL) { 141 // Lazily create a module's reads list 142 _reads = new (ResourceObj::C_HEAP, mtModule)GrowableArray<ModuleEntry*>(MODULE_READS_SIZE, true); 143 } 144 145 // Determine, based on this newly established read edge to module m, 146 // if this module's read list should be walked at a GC safepoint. 147 set_read_walk_required(m->loader_data()); 148 149 // Establish readability to module m 150 _reads->append_if_missing(m); 151 } 152 } 153 154 // If the module's loader, that a read edge is being established to, is 155 // not the same loader as this module's and is not one of the 3 builtin 156 // class loaders, then this module's reads list must be walked at GC 157 // safepoint. Modules have the same life cycle as their defining class 158 // loaders and should be removed if dead. 159 void ModuleEntry::set_read_walk_required(ClassLoaderData* m_loader_data) { 160 assert(is_named(), "Cannot call set_read_walk_required on unnamed module"); 161 assert_locked_or_safepoint(Module_lock); 162 if (!_must_walk_reads && 163 loader_data() != m_loader_data && 164 !m_loader_data->is_builtin_class_loader_data()) { 165 _must_walk_reads = true; 166 if (log_is_enabled(Trace, module)) { 167 ResourceMark rm; 168 log_trace(module)("ModuleEntry::set_read_walk_required(): module %s reads list must be walked", 169 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE); 170 } 171 } 172 } 173 174 // Set whether the module is open, i.e. all its packages are unqualifiedly exported 175 void ModuleEntry::set_is_open(bool is_open) { 176 assert_lock_strong(Module_lock); 177 _is_open = is_open; 178 } 179 180 // Returns true if the module has a non-empty reads list. As such, the unnamed 181 // module will return false. 182 bool ModuleEntry::has_reads_list() const { 183 assert_locked_or_safepoint(Module_lock); 184 return ((_reads != NULL) && !_reads->is_empty()); 185 } 186 187 // Purge dead module entries out of reads list. 188 void ModuleEntry::purge_reads() { 189 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 190 191 if (_must_walk_reads && has_reads_list()) { 192 // This module's _must_walk_reads flag will be reset based 193 // on the remaining live modules on the reads list. 194 _must_walk_reads = false; 195 196 if (log_is_enabled(Trace, module)) { 197 ResourceMark rm; 198 log_trace(module)("ModuleEntry::purge_reads(): module %s reads list being walked", 199 (name() != NULL) ? name()->as_C_string() : UNNAMED_MODULE); 200 } 201 202 // Go backwards because this removes entries that are dead. 203 int len = _reads->length(); 204 for (int idx = len - 1; idx >= 0; idx--) { 205 ModuleEntry* module_idx = _reads->at(idx); 206 ClassLoaderData* cld_idx = module_idx->loader_data(); 207 if (cld_idx->is_unloading()) { 208 _reads->delete_at(idx); 209 } else { 210 // Update the need to walk this module's reads based on live modules 211 set_read_walk_required(cld_idx); 212 } 213 } 214 } 215 } 216 217 void ModuleEntry::module_reads_do(ModuleClosure* f) { 218 assert_locked_or_safepoint(Module_lock); 219 assert(f != NULL, "invariant"); 220 221 if (has_reads_list()) { 222 int reads_len = _reads->length(); 223 for (int i = 0; i < reads_len; ++i) { 224 f->do_module(_reads->at(i)); 225 } 226 } 227 } 228 229 void ModuleEntry::delete_reads() { 230 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 231 delete _reads; 232 _reads = NULL; 233 } 234 235 ModuleEntry* ModuleEntry::create_unnamed_module(ClassLoaderData* cld) { 236 // The java.lang.Module for this loader's 237 // corresponding unnamed module can be found in the java.lang.ClassLoader object. 238 oop module = java_lang_ClassLoader::unnamedModule(cld->class_loader()); 239 240 // Ensure that the unnamed module was correctly set when 241 // the class loader was constructed. 242 guarantee(java_lang_Module::is_instance(module), "unnamed module is not an instance of type java.lang.Module"); 243 244 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(Thread::current(), module), cld); 245 246 // Store pointer to the ModuleEntry in the unnamed module's java.lang.Module object. 247 java_lang_Module::set_module_entry(module, unnamed_module); 248 249 return unnamed_module; 250 } 251 252 ModuleEntry* ModuleEntry::create_boot_unnamed_module(ClassLoaderData* cld) { 253 // For the boot loader, the java.lang.Module for the unnamed module 254 // is not known until a call to JVM_SetBootLoaderUnnamedModule is made. At 255 // this point initially create the ModuleEntry for the unnamed module. 256 ModuleEntry* unnamed_module = new_unnamed_module_entry(Handle(), cld); 257 assert(unnamed_module != NULL, "boot loader unnamed module should not be null"); 258 return unnamed_module; 259 } 260 261 // When creating an unnamed module, this is called without holding the Module_lock. 262 // This is okay because the unnamed module gets created before the ClassLoaderData 263 // is available to other threads. 264 ModuleEntry* ModuleEntry::new_unnamed_module_entry(Handle module_handle, ClassLoaderData* cld) { 265 ModuleEntry* entry = (ModuleEntry*) NEW_C_HEAP_ARRAY(char, sizeof(ModuleEntry), mtModule); 266 267 // Initialize everything BasicHashtable would 268 entry->set_next(NULL); 269 entry->set_hash(0); 270 entry->set_literal(NULL); 271 272 // Initialize fields specific to a ModuleEntry 273 entry->init(); 274 275 // Unnamed modules can read all other unnamed modules. 276 entry->set_can_read_all_unnamed(); 277 278 if (!module_handle.is_null()) { 279 entry->set_module(cld->add_handle(module_handle)); 280 } 281 282 entry->set_loader_data(cld); 283 entry->_is_open = true; 284 285 JFR_ONLY(INIT_ID(entry);) 286 287 return entry; 288 } 289 290 void ModuleEntry::delete_unnamed_module() { 291 // Do not need unlink_entry() since the unnamed module is not in the hashtable 292 FREE_C_HEAP_ARRAY(char, this); 293 } 294 295 ModuleEntryTable::ModuleEntryTable(int table_size) 296 : Hashtable<Symbol*, mtModule>(table_size, sizeof(ModuleEntry)) 297 { 298 } 299 300 ModuleEntryTable::~ModuleEntryTable() { 301 assert_locked_or_safepoint(Module_lock); 302 303 // Walk through all buckets and all entries in each bucket, 304 // freeing each entry. 305 for (int i = 0; i < table_size(); ++i) { 306 for (ModuleEntry* m = bucket(i); m != NULL;) { 307 ModuleEntry* to_remove = m; 308 // read next before freeing. 309 m = m->next(); 310 311 ResourceMark rm; 312 if (to_remove->name() != NULL) { 313 log_info(module, unload)("unloading module %s", to_remove->name()->as_C_string()); 314 } 315 log_debug(module)("ModuleEntryTable: deleting module: %s", to_remove->name() != NULL ? 316 to_remove->name()->as_C_string() : UNNAMED_MODULE); 317 318 // Clean out the C heap allocated reads list first before freeing the entry 319 to_remove->delete_reads(); 320 if (to_remove->name() != NULL) { 321 to_remove->name()->decrement_refcount(); 322 } 323 if (to_remove->version() != NULL) { 324 to_remove->version()->decrement_refcount(); 325 } 326 if (to_remove->location() != NULL) { 327 to_remove->location()->decrement_refcount(); 328 } 329 330 // Unlink from the Hashtable prior to freeing 331 unlink_entry(to_remove); 332 FREE_C_HEAP_ARRAY(char, to_remove); 333 } 334 } 335 assert(number_of_entries() == 0, "should have removed all entries"); 336 assert(new_entry_free_list() == NULL, "entry present on ModuleEntryTable's free list"); 337 free_buckets(); 338 } 339 340 ModuleEntry* ModuleEntryTable::new_entry(unsigned int hash, Handle module_handle, 341 bool is_open, Symbol* name, 342 Symbol* version, Symbol* location, 343 ClassLoaderData* loader_data) { 344 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 345 ModuleEntry* entry = (ModuleEntry*)Hashtable<Symbol*, mtModule>::allocate_new_entry(hash, name); 346 347 // Initialize fields specific to a ModuleEntry 348 entry->init(); 349 if (name != NULL) { 350 name->increment_refcount(); 351 } else { 352 // Unnamed modules can read all other unnamed modules. 353 entry->set_can_read_all_unnamed(); 354 } 355 356 if (!module_handle.is_null()) { 357 entry->set_module(loader_data->add_handle(module_handle)); 358 } 359 360 entry->set_loader_data(loader_data); 361 entry->set_version(version); 362 entry->set_location(location); 363 entry->set_is_open(is_open); 364 365 if (ClassLoader::is_in_patch_mod_entries(name)) { 366 entry->set_is_patched(); 367 if (log_is_enabled(Trace, module, patch)) { 368 ResourceMark rm; 369 log_trace(module, patch)("Marked module %s as patched from --patch-module", name->as_C_string()); 370 } 371 } 372 373 JFR_ONLY(INIT_ID(entry);) 374 375 return entry; 376 } 377 378 void ModuleEntryTable::add_entry(int index, ModuleEntry* new_entry) { 379 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 380 Hashtable<Symbol*, mtModule>::add_entry(index, (HashtableEntry<Symbol*, mtModule>*)new_entry); 381 } 382 383 ModuleEntry* ModuleEntryTable::locked_create_entry_or_null(Handle module_handle, 384 bool is_open, 385 Symbol* module_name, 386 Symbol* module_version, 387 Symbol* module_location, 388 ClassLoaderData* loader_data) { 389 assert(module_name != NULL, "ModuleEntryTable locked_create_entry_or_null should never be called for unnamed module."); 390 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 391 // Check if module already exists. 392 if (lookup_only(module_name) != NULL) { 393 return NULL; 394 } else { 395 ModuleEntry* entry = new_entry(compute_hash(module_name), module_handle, is_open, module_name, 396 module_version, module_location, loader_data); 397 add_entry(index_for(module_name), entry); 398 return entry; 399 } 400 } 401 402 // lookup_only by Symbol* to find a ModuleEntry. 403 ModuleEntry* ModuleEntryTable::lookup_only(Symbol* name) { 404 assert(name != NULL, "name cannot be NULL"); 405 int index = index_for(name); 406 for (ModuleEntry* m = bucket(index); m != NULL; m = m->next()) { 407 if (m->name()->fast_compare(name) == 0) { 408 return m; 409 } 410 } 411 return NULL; 412 } 413 414 // Remove dead modules from all other alive modules' reads list. 415 // This should only occur at class unloading. 416 void ModuleEntryTable::purge_all_module_reads() { 417 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 418 for (int i = 0; i < table_size(); i++) { 419 for (ModuleEntry* entry = bucket(i); 420 entry != NULL; 421 entry = entry->next()) { 422 entry->purge_reads(); 423 } 424 } 425 } 426 427 void ModuleEntryTable::finalize_javabase(Handle module_handle, Symbol* version, Symbol* location) { 428 assert(Module_lock->owned_by_self(), "should have the Module_lock"); 429 ClassLoaderData* boot_loader_data = ClassLoaderData::the_null_class_loader_data(); 430 ModuleEntryTable* module_table = boot_loader_data->modules(); 431 432 assert(module_table != NULL, "boot loader's ModuleEntryTable not defined"); 433 434 if (module_handle.is_null()) { 435 fatal("Unable to finalize module definition for " JAVA_BASE_NAME); 436 } 437 438 // Set java.lang.Module, version and location for java.base 439 ModuleEntry* jb_module = javabase_moduleEntry(); 440 assert(jb_module != NULL, JAVA_BASE_NAME " ModuleEntry not defined"); 441 jb_module->set_version(version); 442 jb_module->set_location(location); 443 // Once java.base's ModuleEntry _module field is set with the known 444 // java.lang.Module, java.base is considered "defined" to the VM. 445 jb_module->set_module(boot_loader_data->add_handle(module_handle)); 446 447 // Store pointer to the ModuleEntry for java.base in the java.lang.Module object. 448 java_lang_Module::set_module_entry(module_handle(), jb_module); 449 } 450 451 // Within java.lang.Class instances there is a java.lang.Module field that must 452 // be set with the defining module. During startup, prior to java.base's definition, 453 // classes needing their module field set are added to the fixup_module_list. 454 // Their module field is set once java.base's java.lang.Module is known to the VM. 455 void ModuleEntryTable::patch_javabase_entries(Handle module_handle) { 456 if (module_handle.is_null()) { 457 fatal("Unable to patch the module field of classes loaded prior to " 458 JAVA_BASE_NAME "'s definition, invalid java.lang.Module"); 459 } 460 461 // Do the fixups for the basic primitive types 462 java_lang_Class::set_module(Universe::int_mirror(), module_handle()); 463 java_lang_Class::set_module(Universe::float_mirror(), module_handle()); 464 java_lang_Class::set_module(Universe::double_mirror(), module_handle()); 465 java_lang_Class::set_module(Universe::byte_mirror(), module_handle()); 466 java_lang_Class::set_module(Universe::bool_mirror(), module_handle()); 467 java_lang_Class::set_module(Universe::char_mirror(), module_handle()); 468 java_lang_Class::set_module(Universe::long_mirror(), module_handle()); 469 java_lang_Class::set_module(Universe::short_mirror(), module_handle()); 470 java_lang_Class::set_module(Universe::void_mirror(), module_handle()); 471 472 // Do the fixups for classes that have already been created. 473 GrowableArray <Klass*>* list = java_lang_Class::fixup_module_field_list(); 474 int list_length = list->length(); 475 for (int i = 0; i < list_length; i++) { 476 Klass* k = list->at(i); 477 assert(k->is_klass(), "List should only hold classes"); 478 java_lang_Class::fixup_module_field(k, module_handle); 479 k->class_loader_data()->dec_keep_alive(); 480 } 481 482 delete java_lang_Class::fixup_module_field_list(); 483 java_lang_Class::set_fixup_module_field_list(NULL); 484 } 485 486 void ModuleEntryTable::print(outputStream* st) { 487 st->print_cr("Module Entry Table (table_size=%d, entries=%d)", 488 table_size(), number_of_entries()); 489 for (int i = 0; i < table_size(); i++) { 490 for (ModuleEntry* probe = bucket(i); 491 probe != NULL; 492 probe = probe->next()) { 493 probe->print(st); 494 } 495 } 496 } 497 498 void ModuleEntry::print(outputStream* st) { 499 ResourceMark rm; 500 st->print_cr("entry " PTR_FORMAT " name %s module " PTR_FORMAT " loader %s version %s location %s strict %s next " PTR_FORMAT, 501 p2i(this), 502 name() == NULL ? UNNAMED_MODULE : name()->as_C_string(), 503 p2i(module()), 504 loader_data()->loader_name(), 505 version() != NULL ? version()->as_C_string() : "NULL", 506 location() != NULL ? location()->as_C_string() : "NULL", 507 BOOL_TO_STR(!can_read_all_unnamed()), p2i(next())); 508 } 509 510 void ModuleEntryTable::verify() { 511 verify_table<ModuleEntry>("Module Entry Table"); 512 } 513 514 void ModuleEntry::verify() { 515 guarantee(loader_data() != NULL, "A module entry must be associated with a loader."); 516 }