1 /* 2 * Copyright (c) 2003, 2024, 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/classLoaderDataGraph.hpp" 27 #include "classfile/javaClasses.inline.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/vmClasses.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "gc/shared/collectedHeap.hpp" 32 #include "jvmtifiles/jvmtiEnv.hpp" 33 #include "logging/log.hpp" 34 #include "memory/allocation.inline.hpp" 35 #include "memory/resourceArea.hpp" 36 #include "memory/universe.hpp" 37 #include "oops/access.inline.hpp" 38 #include "oops/arrayOop.hpp" 39 #include "oops/constantPool.inline.hpp" 40 #include "oops/instanceMirrorKlass.hpp" 41 #include "oops/klass.inline.hpp" 42 #include "oops/objArrayKlass.hpp" 43 #include "oops/objArrayOop.inline.hpp" 44 #include "oops/oop.inline.hpp" 45 #include "oops/typeArrayOop.inline.hpp" 46 #include "prims/jvmtiEventController.hpp" 47 #include "prims/jvmtiEventController.inline.hpp" 48 #include "prims/jvmtiExport.hpp" 49 #include "prims/jvmtiImpl.hpp" 50 #include "prims/jvmtiTagMap.hpp" 51 #include "prims/jvmtiTagMapTable.hpp" 52 #include "prims/jvmtiThreadState.hpp" 53 #include "runtime/continuationWrapper.inline.hpp" 54 #include "runtime/deoptimization.hpp" 55 #include "runtime/frame.inline.hpp" 56 #include "runtime/handles.inline.hpp" 57 #include "runtime/interfaceSupport.inline.hpp" 58 #include "runtime/javaCalls.hpp" 59 #include "runtime/javaThread.inline.hpp" 60 #include "runtime/jniHandles.inline.hpp" 61 #include "runtime/mutex.hpp" 62 #include "runtime/mutexLocker.hpp" 63 #include "runtime/reflectionUtils.hpp" 64 #include "runtime/safepoint.hpp" 65 #include "runtime/timerTrace.hpp" 66 #include "runtime/threadSMR.hpp" 67 #include "runtime/vframe.hpp" 68 #include "runtime/vmThread.hpp" 69 #include "runtime/vmOperations.hpp" 70 #include "utilities/objectBitSet.inline.hpp" 71 #include "utilities/macros.hpp" 72 73 typedef ObjectBitSet<mtServiceability> JVMTIBitSet; 74 75 bool JvmtiTagMap::_has_object_free_events = false; 76 77 // create a JvmtiTagMap 78 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) : 79 _env(env), 80 _lock(Mutex::nosafepoint, "JvmtiTagMap_lock"), 81 _needs_cleaning(false), 82 _posting_events(false) { 83 84 assert(JvmtiThreadState_lock->is_locked(), "sanity check"); 85 assert(((JvmtiEnvBase *)env)->tag_map() == nullptr, "tag map already exists for environment"); 86 87 _hashmap = new JvmtiTagMapTable(); 88 89 // finally add us to the environment 90 ((JvmtiEnvBase *)env)->release_set_tag_map(this); 91 } 92 93 // destroy a JvmtiTagMap 94 JvmtiTagMap::~JvmtiTagMap() { 95 96 // no lock acquired as we assume the enclosing environment is 97 // also being destroyed. 98 ((JvmtiEnvBase *)_env)->set_tag_map(nullptr); 99 100 // finally destroy the hashmap 101 delete _hashmap; 102 _hashmap = nullptr; 103 } 104 105 // Called by env_dispose() to reclaim memory before deallocation. 106 // Remove all the entries but keep the empty table intact. 107 // This needs the table lock. 108 void JvmtiTagMap::clear() { 109 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag); 110 _hashmap->clear(); 111 } 112 113 // returns the tag map for the given environments. If the tag map 114 // doesn't exist then it is created. 115 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) { 116 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map_acquire(); 117 if (tag_map == nullptr) { 118 MutexLocker mu(JvmtiThreadState_lock); 119 tag_map = ((JvmtiEnvBase*)env)->tag_map(); 120 if (tag_map == nullptr) { 121 tag_map = new JvmtiTagMap(env); 122 } 123 } else { 124 DEBUG_ONLY(JavaThread::current()->check_possible_safepoint()); 125 } 126 return tag_map; 127 } 128 129 // iterate over all entries in the tag map. 130 void JvmtiTagMap::entry_iterate(JvmtiTagMapKeyClosure* closure) { 131 hashmap()->entry_iterate(closure); 132 } 133 134 // returns true if the hashmaps are empty 135 bool JvmtiTagMap::is_empty() { 136 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking"); 137 return hashmap()->is_empty(); 138 } 139 140 // This checks for posting before operations that use 141 // this tagmap table. 142 void JvmtiTagMap::check_hashmap(GrowableArray<jlong>* objects) { 143 assert(is_locked(), "checking"); 144 145 if (is_empty()) { return; } 146 147 if (_needs_cleaning && 148 objects != nullptr && 149 env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) { 150 remove_dead_entries_locked(objects); 151 } 152 } 153 154 // This checks for posting and is called from the heap walks. 155 void JvmtiTagMap::check_hashmaps_for_heapwalk(GrowableArray<jlong>* objects) { 156 assert(SafepointSynchronize::is_at_safepoint(), "called from safepoints"); 157 158 // Verify that the tag map tables are valid and unconditionally post events 159 // that are expected to be posted before gc_notification. 160 JvmtiEnvIterator it; 161 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) { 162 JvmtiTagMap* tag_map = env->tag_map_acquire(); 163 if (tag_map != nullptr) { 164 // The ZDriver may be walking the hashmaps concurrently so this lock is needed. 165 MutexLocker ml(tag_map->lock(), Mutex::_no_safepoint_check_flag); 166 tag_map->check_hashmap(objects); 167 } 168 } 169 } 170 171 // Return the tag value for an object, or 0 if the object is 172 // not tagged 173 // 174 static inline jlong tag_for(JvmtiTagMap* tag_map, oop o) { 175 return tag_map->hashmap()->find(o); 176 } 177 178 // A CallbackWrapper is a support class for querying and tagging an object 179 // around a callback to a profiler. The constructor does pre-callback 180 // work to get the tag value, klass tag value, ... and the destructor 181 // does the post-callback work of tagging or untagging the object. 182 // 183 // { 184 // CallbackWrapper wrapper(tag_map, o); 185 // 186 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...) 187 // 188 // } 189 // wrapper goes out of scope here which results in the destructor 190 // checking to see if the object has been tagged, untagged, or the 191 // tag value has changed. 192 // 193 class CallbackWrapper : public StackObj { 194 private: 195 JvmtiTagMap* _tag_map; 196 JvmtiTagMapTable* _hashmap; 197 oop _o; 198 jlong _obj_size; 199 jlong _obj_tag; 200 jlong _klass_tag; 201 202 protected: 203 JvmtiTagMap* tag_map() const { return _tag_map; } 204 205 // invoked post-callback to tag, untag, or update the tag of an object 206 void inline post_callback_tag_update(oop o, JvmtiTagMapTable* hashmap, 207 jlong obj_tag); 208 public: 209 CallbackWrapper(JvmtiTagMap* tag_map, oop o) { 210 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(), 211 "MT unsafe or must be VM thread"); 212 213 // object to tag 214 _o = o; 215 216 // object size 217 _obj_size = (jlong)_o->size() * wordSize; 218 219 // record the context 220 _tag_map = tag_map; 221 _hashmap = tag_map->hashmap(); 222 223 // get object tag 224 _obj_tag = _hashmap->find(_o); 225 226 // get the class and the class's tag value 227 assert(vmClasses::Class_klass()->is_mirror_instance_klass(), "Is not?"); 228 229 _klass_tag = tag_for(tag_map, _o->klass()->java_mirror()); 230 } 231 232 ~CallbackWrapper() { 233 post_callback_tag_update(_o, _hashmap, _obj_tag); 234 } 235 236 inline jlong* obj_tag_p() { return &_obj_tag; } 237 inline jlong obj_size() const { return _obj_size; } 238 inline jlong obj_tag() const { return _obj_tag; } 239 inline jlong klass_tag() const { return _klass_tag; } 240 }; 241 242 // callback post-callback to tag, untag, or update the tag of an object 243 void inline CallbackWrapper::post_callback_tag_update(oop o, 244 JvmtiTagMapTable* hashmap, 245 jlong obj_tag) { 246 if (obj_tag == 0) { 247 // callback has untagged the object, remove the entry if present 248 hashmap->remove(o); 249 } else { 250 // object was previously tagged or not present - the callback may have 251 // changed the tag value 252 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 253 hashmap->add(o, obj_tag); 254 } 255 } 256 257 // An extended CallbackWrapper used when reporting an object reference 258 // to the agent. 259 // 260 // { 261 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o); 262 // 263 // (*callback)(wrapper.klass_tag(), 264 // wrapper.obj_size(), 265 // wrapper.obj_tag_p() 266 // wrapper.referrer_tag_p(), ...) 267 // 268 // } 269 // wrapper goes out of scope here which results in the destructor 270 // checking to see if the referrer object has been tagged, untagged, 271 // or the tag value has changed. 272 // 273 class TwoOopCallbackWrapper : public CallbackWrapper { 274 private: 275 bool _is_reference_to_self; 276 JvmtiTagMapTable* _referrer_hashmap; 277 oop _referrer; 278 jlong _referrer_obj_tag; 279 jlong _referrer_klass_tag; 280 jlong* _referrer_tag_p; 281 282 bool is_reference_to_self() const { return _is_reference_to_self; } 283 284 public: 285 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, oop referrer, oop o) : 286 CallbackWrapper(tag_map, o) 287 { 288 // self reference needs to be handled in a special way 289 _is_reference_to_self = (referrer == o); 290 291 if (_is_reference_to_self) { 292 _referrer_klass_tag = klass_tag(); 293 _referrer_tag_p = obj_tag_p(); 294 } else { 295 _referrer = referrer; 296 // record the context 297 _referrer_hashmap = tag_map->hashmap(); 298 299 // get object tag 300 _referrer_obj_tag = _referrer_hashmap->find(_referrer); 301 302 _referrer_tag_p = &_referrer_obj_tag; 303 304 // get referrer class tag. 305 _referrer_klass_tag = tag_for(tag_map, _referrer->klass()->java_mirror()); 306 } 307 } 308 309 ~TwoOopCallbackWrapper() { 310 if (!is_reference_to_self()) { 311 post_callback_tag_update(_referrer, 312 _referrer_hashmap, 313 _referrer_obj_tag); 314 } 315 } 316 317 // address of referrer tag 318 // (for a self reference this will return the same thing as obj_tag_p()) 319 inline jlong* referrer_tag_p() { return _referrer_tag_p; } 320 321 // referrer's class tag 322 inline jlong referrer_klass_tag() { return _referrer_klass_tag; } 323 }; 324 325 // tag an object 326 // 327 // This function is performance critical. If many threads attempt to tag objects 328 // around the same time then it's possible that the Mutex associated with the 329 // tag map will be a hot lock. 330 void JvmtiTagMap::set_tag(jobject object, jlong tag) { 331 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag); 332 333 // SetTag should not post events because the JavaThread has to 334 // transition to native for the callback and this cannot stop for 335 // safepoints with the hashmap lock held. 336 check_hashmap(nullptr); /* don't collect dead objects */ 337 338 // resolve the object 339 oop o = JNIHandles::resolve_non_null(object); 340 341 // see if the object is already tagged 342 JvmtiTagMapTable* hashmap = _hashmap; 343 344 if (tag == 0) { 345 // remove the entry if present 346 hashmap->remove(o); 347 } else { 348 // if the object is already tagged or not present then we add/update 349 // the tag 350 hashmap->add(o, tag); 351 } 352 } 353 354 // get the tag for an object 355 jlong JvmtiTagMap::get_tag(jobject object) { 356 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag); 357 358 // GetTag should not post events because the JavaThread has to 359 // transition to native for the callback and this cannot stop for 360 // safepoints with the hashmap lock held. 361 check_hashmap(nullptr); /* don't collect dead objects */ 362 363 // resolve the object 364 oop o = JNIHandles::resolve_non_null(object); 365 366 return tag_for(this, o); 367 } 368 369 370 // Helper class used to describe the static or instance fields of a class. 371 // For each field it holds the field index (as defined by the JVMTI specification), 372 // the field type, and the offset. 373 374 class ClassFieldDescriptor: public CHeapObj<mtInternal> { 375 private: 376 int _field_index; 377 int _field_offset; 378 char _field_type; 379 public: 380 ClassFieldDescriptor(int index, char type, int offset) : 381 _field_index(index), _field_offset(offset), _field_type(type) { 382 } 383 int field_index() const { return _field_index; } 384 char field_type() const { return _field_type; } 385 int field_offset() const { return _field_offset; } 386 }; 387 388 class ClassFieldMap: public CHeapObj<mtInternal> { 389 private: 390 enum { 391 initial_field_count = 5 392 }; 393 394 // list of field descriptors 395 GrowableArray<ClassFieldDescriptor*>* _fields; 396 397 // constructor 398 ClassFieldMap(); 399 400 // calculates number of fields in all interfaces 401 static int interfaces_field_count(InstanceKlass* ik); 402 403 // add a field 404 void add(int index, char type, int offset); 405 406 public: 407 ~ClassFieldMap(); 408 409 // access 410 int field_count() { return _fields->length(); } 411 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); } 412 413 // functions to create maps of static or instance fields 414 static ClassFieldMap* create_map_of_static_fields(Klass* k); 415 static ClassFieldMap* create_map_of_instance_fields(oop obj); 416 }; 417 418 ClassFieldMap::ClassFieldMap() { 419 _fields = new (mtServiceability) 420 GrowableArray<ClassFieldDescriptor*>(initial_field_count, mtServiceability); 421 } 422 423 ClassFieldMap::~ClassFieldMap() { 424 for (int i=0; i<_fields->length(); i++) { 425 delete _fields->at(i); 426 } 427 delete _fields; 428 } 429 430 int ClassFieldMap::interfaces_field_count(InstanceKlass* ik) { 431 const Array<InstanceKlass*>* interfaces = ik->transitive_interfaces(); 432 int count = 0; 433 for (int i = 0; i < interfaces->length(); i++) { 434 FilteredJavaFieldStream fld(interfaces->at(i)); 435 count += fld.field_count(); 436 } 437 return count; 438 } 439 440 void ClassFieldMap::add(int index, char type, int offset) { 441 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, type, offset); 442 _fields->append(field); 443 } 444 445 // Returns a heap allocated ClassFieldMap to describe the static fields 446 // of the given class. 447 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) { 448 InstanceKlass* ik = InstanceKlass::cast(k); 449 450 // create the field map 451 ClassFieldMap* field_map = new ClassFieldMap(); 452 453 // Static fields of interfaces and superclasses are reported as references from the interfaces/superclasses. 454 // Need to calculate start index of this class fields: number of fields in all interfaces and superclasses. 455 int index = interfaces_field_count(ik); 456 for (InstanceKlass* super_klass = ik->java_super(); super_klass != nullptr; super_klass = super_klass->java_super()) { 457 FilteredJavaFieldStream super_fld(super_klass); 458 index += super_fld.field_count(); 459 } 460 461 for (FilteredJavaFieldStream fld(ik); !fld.done(); fld.next(), index++) { 462 // ignore instance fields 463 if (!fld.access_flags().is_static()) { 464 continue; 465 } 466 field_map->add(index, fld.signature()->char_at(0), fld.offset()); 467 } 468 469 return field_map; 470 } 471 472 // Returns a heap allocated ClassFieldMap to describe the instance fields 473 // of the given class. All instance fields are included (this means public 474 // and private fields declared in superclasses too). 475 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(oop obj) { 476 InstanceKlass* ik = InstanceKlass::cast(obj->klass()); 477 478 // create the field map 479 ClassFieldMap* field_map = new ClassFieldMap(); 480 481 // fields of the superclasses are reported first, so need to know total field number to calculate field indices 482 int total_field_number = interfaces_field_count(ik); 483 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->java_super()) { 484 FilteredJavaFieldStream fld(klass); 485 total_field_number += fld.field_count(); 486 } 487 488 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->java_super()) { 489 FilteredJavaFieldStream fld(klass); 490 int start_index = total_field_number - fld.field_count(); 491 for (int index = 0; !fld.done(); fld.next(), index++) { 492 // ignore static fields 493 if (fld.access_flags().is_static()) { 494 continue; 495 } 496 field_map->add(start_index + index, fld.signature()->char_at(0), fld.offset()); 497 } 498 // update total_field_number for superclass (decrease by the field count in the current class) 499 total_field_number = start_index; 500 } 501 502 return field_map; 503 } 504 505 // Helper class used to cache a ClassFileMap for the instance fields of 506 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during 507 // heap iteration and avoid creating a field map for each object in the heap 508 // (only need to create the map when the first instance of a class is encountered). 509 // 510 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> { 511 private: 512 enum { 513 initial_class_count = 200 514 }; 515 ClassFieldMap* _field_map; 516 517 ClassFieldMap* field_map() const { return _field_map; } 518 519 JvmtiCachedClassFieldMap(ClassFieldMap* field_map); 520 ~JvmtiCachedClassFieldMap(); 521 522 static GrowableArray<InstanceKlass*>* _class_list; 523 static void add_to_class_list(InstanceKlass* ik); 524 525 public: 526 // returns the field map for a given object (returning map cached 527 // by InstanceKlass if possible 528 static ClassFieldMap* get_map_of_instance_fields(oop obj); 529 530 // removes the field map from all instanceKlasses - should be 531 // called before VM operation completes 532 static void clear_cache(); 533 534 // returns the number of ClassFieldMap cached by instanceKlasses 535 static int cached_field_map_count(); 536 }; 537 538 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list; 539 540 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) { 541 _field_map = field_map; 542 } 543 544 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() { 545 if (_field_map != nullptr) { 546 delete _field_map; 547 } 548 } 549 550 // Marker class to ensure that the class file map cache is only used in a defined 551 // scope. 552 class ClassFieldMapCacheMark : public StackObj { 553 private: 554 static bool _is_active; 555 public: 556 ClassFieldMapCacheMark() { 557 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 558 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty"); 559 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested"); 560 _is_active = true; 561 } 562 ~ClassFieldMapCacheMark() { 563 JvmtiCachedClassFieldMap::clear_cache(); 564 _is_active = false; 565 } 566 static bool is_active() { return _is_active; } 567 }; 568 569 bool ClassFieldMapCacheMark::_is_active; 570 571 // record that the given InstanceKlass is caching a field map 572 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) { 573 if (_class_list == nullptr) { 574 _class_list = new (mtServiceability) 575 GrowableArray<InstanceKlass*>(initial_class_count, mtServiceability); 576 } 577 _class_list->push(ik); 578 } 579 580 // returns the instance field map for the given object 581 // (returns field map cached by the InstanceKlass if possible) 582 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(oop obj) { 583 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 584 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active"); 585 586 Klass* k = obj->klass(); 587 InstanceKlass* ik = InstanceKlass::cast(k); 588 589 // return cached map if possible 590 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); 591 if (cached_map != nullptr) { 592 assert(cached_map->field_map() != nullptr, "missing field list"); 593 return cached_map->field_map(); 594 } else { 595 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(obj); 596 cached_map = new JvmtiCachedClassFieldMap(field_map); 597 ik->set_jvmti_cached_class_field_map(cached_map); 598 add_to_class_list(ik); 599 return field_map; 600 } 601 } 602 603 // remove the fields maps cached from all instanceKlasses 604 void JvmtiCachedClassFieldMap::clear_cache() { 605 assert(Thread::current()->is_VM_thread(), "must be VMThread"); 606 if (_class_list != nullptr) { 607 for (int i = 0; i < _class_list->length(); i++) { 608 InstanceKlass* ik = _class_list->at(i); 609 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map(); 610 assert(cached_map != nullptr, "should not be null"); 611 ik->set_jvmti_cached_class_field_map(nullptr); 612 delete cached_map; // deletes the encapsulated field map 613 } 614 delete _class_list; 615 _class_list = nullptr; 616 } 617 } 618 619 // returns the number of ClassFieldMap cached by instanceKlasses 620 int JvmtiCachedClassFieldMap::cached_field_map_count() { 621 return (_class_list == nullptr) ? 0 : _class_list->length(); 622 } 623 624 // helper function to indicate if an object is filtered by its tag or class tag 625 static inline bool is_filtered_by_heap_filter(jlong obj_tag, 626 jlong klass_tag, 627 int heap_filter) { 628 // apply the heap filter 629 if (obj_tag != 0) { 630 // filter out tagged objects 631 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true; 632 } else { 633 // filter out untagged objects 634 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true; 635 } 636 if (klass_tag != 0) { 637 // filter out objects with tagged classes 638 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true; 639 } else { 640 // filter out objects with untagged classes. 641 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true; 642 } 643 return false; 644 } 645 646 // helper function to indicate if an object is filtered by a klass filter 647 static inline bool is_filtered_by_klass_filter(oop obj, Klass* klass_filter) { 648 if (klass_filter != nullptr) { 649 if (obj->klass() != klass_filter) { 650 return true; 651 } 652 } 653 return false; 654 } 655 656 // helper function to tell if a field is a primitive field or not 657 static inline bool is_primitive_field_type(char type) { 658 return (type != JVM_SIGNATURE_CLASS && type != JVM_SIGNATURE_ARRAY); 659 } 660 661 // helper function to copy the value from location addr to jvalue. 662 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) { 663 switch (value_type) { 664 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; } 665 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; } 666 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; } 667 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; } 668 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; } 669 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; } 670 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; } 671 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; } 672 default: ShouldNotReachHere(); 673 } 674 } 675 676 // helper function to invoke string primitive value callback 677 // returns visit control flags 678 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb, 679 CallbackWrapper* wrapper, 680 oop str, 681 void* user_data) 682 { 683 assert(str->klass() == vmClasses::String_klass(), "not a string"); 684 685 typeArrayOop s_value = java_lang_String::value(str); 686 687 // JDK-6584008: the value field may be null if a String instance is 688 // partially constructed. 689 if (s_value == nullptr) { 690 return 0; 691 } 692 // get the string value and length 693 // (string value may be offset from the base) 694 int s_len = java_lang_String::length(str); 695 bool is_latin1 = java_lang_String::is_latin1(str); 696 jchar* value; 697 if (s_len > 0) { 698 if (!is_latin1) { 699 value = s_value->char_at_addr(0); 700 } else { 701 // Inflate latin1 encoded string to UTF16 702 jchar* buf = NEW_C_HEAP_ARRAY(jchar, s_len, mtInternal); 703 for (int i = 0; i < s_len; i++) { 704 buf[i] = ((jchar) s_value->byte_at(i)) & 0xff; 705 } 706 value = &buf[0]; 707 } 708 } else { 709 // Don't use char_at_addr(0) if length is 0 710 value = (jchar*) s_value->base(T_CHAR); 711 } 712 713 // invoke the callback 714 jint res = (*cb)(wrapper->klass_tag(), 715 wrapper->obj_size(), 716 wrapper->obj_tag_p(), 717 value, 718 (jint)s_len, 719 user_data); 720 721 if (is_latin1 && s_len > 0) { 722 FREE_C_HEAP_ARRAY(jchar, value); 723 } 724 return res; 725 } 726 727 // helper function to invoke string primitive value callback 728 // returns visit control flags 729 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb, 730 CallbackWrapper* wrapper, 731 oop obj, 732 void* user_data) 733 { 734 assert(obj->is_typeArray(), "not a primitive array"); 735 736 // get base address of first element 737 typeArrayOop array = typeArrayOop(obj); 738 BasicType type = TypeArrayKlass::cast(array->klass())->element_type(); 739 void* elements = array->base(type); 740 741 // jvmtiPrimitiveType is defined so this mapping is always correct 742 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type); 743 744 return (*cb)(wrapper->klass_tag(), 745 wrapper->obj_size(), 746 wrapper->obj_tag_p(), 747 (jint)array->length(), 748 elem_type, 749 elements, 750 user_data); 751 } 752 753 // helper function to invoke the primitive field callback for all static fields 754 // of a given class 755 static jint invoke_primitive_field_callback_for_static_fields 756 (CallbackWrapper* wrapper, 757 oop obj, 758 jvmtiPrimitiveFieldCallback cb, 759 void* user_data) 760 { 761 // for static fields only the index will be set 762 static jvmtiHeapReferenceInfo reference_info = { 0 }; 763 764 assert(obj->klass() == vmClasses::Class_klass(), "not a class"); 765 if (java_lang_Class::is_primitive(obj)) { 766 return 0; 767 } 768 Klass* klass = java_lang_Class::as_Klass(obj); 769 770 // ignore classes for object and type arrays 771 if (!klass->is_instance_klass()) { 772 return 0; 773 } 774 775 // ignore classes which aren't linked yet 776 InstanceKlass* ik = InstanceKlass::cast(klass); 777 if (!ik->is_linked()) { 778 return 0; 779 } 780 781 // get the field map 782 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass); 783 784 // invoke the callback for each static primitive field 785 for (int i=0; i<field_map->field_count(); i++) { 786 ClassFieldDescriptor* field = field_map->field_at(i); 787 788 // ignore non-primitive fields 789 char type = field->field_type(); 790 if (!is_primitive_field_type(type)) { 791 continue; 792 } 793 // one-to-one mapping 794 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 795 796 // get offset and field value 797 int offset = field->field_offset(); 798 address addr = cast_from_oop<address>(klass->java_mirror()) + offset; 799 jvalue value; 800 copy_to_jvalue(&value, addr, value_type); 801 802 // field index 803 reference_info.field.index = field->field_index(); 804 805 // invoke the callback 806 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD, 807 &reference_info, 808 wrapper->klass_tag(), 809 wrapper->obj_tag_p(), 810 value, 811 value_type, 812 user_data); 813 if (res & JVMTI_VISIT_ABORT) { 814 delete field_map; 815 return res; 816 } 817 } 818 819 delete field_map; 820 return 0; 821 } 822 823 // helper function to invoke the primitive field callback for all instance fields 824 // of a given object 825 static jint invoke_primitive_field_callback_for_instance_fields( 826 CallbackWrapper* wrapper, 827 oop obj, 828 jvmtiPrimitiveFieldCallback cb, 829 void* user_data) 830 { 831 // for instance fields only the index will be set 832 static jvmtiHeapReferenceInfo reference_info = { 0 }; 833 834 // get the map of the instance fields 835 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj); 836 837 // invoke the callback for each instance primitive field 838 for (int i=0; i<fields->field_count(); i++) { 839 ClassFieldDescriptor* field = fields->field_at(i); 840 841 // ignore non-primitive fields 842 char type = field->field_type(); 843 if (!is_primitive_field_type(type)) { 844 continue; 845 } 846 // one-to-one mapping 847 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 848 849 // get offset and field value 850 int offset = field->field_offset(); 851 address addr = cast_from_oop<address>(obj) + offset; 852 jvalue value; 853 copy_to_jvalue(&value, addr, value_type); 854 855 // field index 856 reference_info.field.index = field->field_index(); 857 858 // invoke the callback 859 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD, 860 &reference_info, 861 wrapper->klass_tag(), 862 wrapper->obj_tag_p(), 863 value, 864 value_type, 865 user_data); 866 if (res & JVMTI_VISIT_ABORT) { 867 return res; 868 } 869 } 870 return 0; 871 } 872 873 874 // VM operation to iterate over all objects in the heap (both reachable 875 // and unreachable) 876 class VM_HeapIterateOperation: public VM_Operation { 877 private: 878 ObjectClosure* _blk; 879 GrowableArray<jlong>* const _dead_objects; 880 public: 881 VM_HeapIterateOperation(ObjectClosure* blk, GrowableArray<jlong>* objects) : 882 _blk(blk), _dead_objects(objects) { } 883 884 VMOp_Type type() const { return VMOp_HeapIterateOperation; } 885 void doit() { 886 // allows class files maps to be cached during iteration 887 ClassFieldMapCacheMark cm; 888 889 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects); 890 891 // make sure that heap is parsable (fills TLABs with filler objects) 892 Universe::heap()->ensure_parsability(false); // no need to retire TLABs 893 894 // Verify heap before iteration - if the heap gets corrupted then 895 // JVMTI's IterateOverHeap will crash. 896 if (VerifyBeforeIteration) { 897 Universe::verify(); 898 } 899 900 // do the iteration 901 Universe::heap()->object_iterate(_blk); 902 } 903 }; 904 905 906 // An ObjectClosure used to support the deprecated IterateOverHeap and 907 // IterateOverInstancesOfClass functions 908 class IterateOverHeapObjectClosure: public ObjectClosure { 909 private: 910 JvmtiTagMap* _tag_map; 911 Klass* _klass; 912 jvmtiHeapObjectFilter _object_filter; 913 jvmtiHeapObjectCallback _heap_object_callback; 914 const void* _user_data; 915 916 // accessors 917 JvmtiTagMap* tag_map() const { return _tag_map; } 918 jvmtiHeapObjectFilter object_filter() const { return _object_filter; } 919 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; } 920 Klass* klass() const { return _klass; } 921 const void* user_data() const { return _user_data; } 922 923 // indicates if iteration has been aborted 924 bool _iteration_aborted; 925 bool is_iteration_aborted() const { return _iteration_aborted; } 926 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; } 927 928 public: 929 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map, 930 Klass* klass, 931 jvmtiHeapObjectFilter object_filter, 932 jvmtiHeapObjectCallback heap_object_callback, 933 const void* user_data) : 934 _tag_map(tag_map), 935 _klass(klass), 936 _object_filter(object_filter), 937 _heap_object_callback(heap_object_callback), 938 _user_data(user_data), 939 _iteration_aborted(false) 940 { 941 } 942 943 void do_object(oop o); 944 }; 945 946 // invoked for each object in the heap 947 void IterateOverHeapObjectClosure::do_object(oop o) { 948 // check if iteration has been halted 949 if (is_iteration_aborted()) return; 950 951 // instanceof check when filtering by klass 952 if (klass() != nullptr && !o->is_a(klass())) { 953 return; 954 } 955 956 // skip if object is a dormant shared object whose mirror hasn't been loaded 957 if (o != nullptr && o->klass()->java_mirror() == nullptr) { 958 log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(o), 959 o->klass()->external_name()); 960 return; 961 } 962 963 // prepare for the calllback 964 CallbackWrapper wrapper(tag_map(), o); 965 966 // if the object is tagged and we're only interested in untagged objects 967 // then don't invoke the callback. Similarly, if the object is untagged 968 // and we're only interested in tagged objects we skip the callback. 969 if (wrapper.obj_tag() != 0) { 970 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return; 971 } else { 972 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return; 973 } 974 975 // invoke the agent's callback 976 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(), 977 wrapper.obj_size(), 978 wrapper.obj_tag_p(), 979 (void*)user_data()); 980 if (control == JVMTI_ITERATION_ABORT) { 981 set_iteration_aborted(true); 982 } 983 } 984 985 // An ObjectClosure used to support the IterateThroughHeap function 986 class IterateThroughHeapObjectClosure: public ObjectClosure { 987 private: 988 JvmtiTagMap* _tag_map; 989 Klass* _klass; 990 int _heap_filter; 991 const jvmtiHeapCallbacks* _callbacks; 992 const void* _user_data; 993 994 // accessor functions 995 JvmtiTagMap* tag_map() const { return _tag_map; } 996 int heap_filter() const { return _heap_filter; } 997 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; } 998 Klass* klass() const { return _klass; } 999 const void* user_data() const { return _user_data; } 1000 1001 // indicates if the iteration has been aborted 1002 bool _iteration_aborted; 1003 bool is_iteration_aborted() const { return _iteration_aborted; } 1004 1005 // used to check the visit control flags. If the abort flag is set 1006 // then we set the iteration aborted flag so that the iteration completes 1007 // without processing any further objects 1008 bool check_flags_for_abort(jint flags) { 1009 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0; 1010 if (is_abort) { 1011 _iteration_aborted = true; 1012 } 1013 return is_abort; 1014 } 1015 1016 public: 1017 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map, 1018 Klass* klass, 1019 int heap_filter, 1020 const jvmtiHeapCallbacks* heap_callbacks, 1021 const void* user_data) : 1022 _tag_map(tag_map), 1023 _klass(klass), 1024 _heap_filter(heap_filter), 1025 _callbacks(heap_callbacks), 1026 _user_data(user_data), 1027 _iteration_aborted(false) 1028 { 1029 } 1030 1031 void do_object(oop o); 1032 }; 1033 1034 // invoked for each object in the heap 1035 void IterateThroughHeapObjectClosure::do_object(oop obj) { 1036 // check if iteration has been halted 1037 if (is_iteration_aborted()) return; 1038 1039 // apply class filter 1040 if (is_filtered_by_klass_filter(obj, klass())) return; 1041 1042 // skip if object is a dormant shared object whose mirror hasn't been loaded 1043 if (obj != nullptr && obj->klass()->java_mirror() == nullptr) { 1044 log_debug(cds, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(obj), 1045 obj->klass()->external_name()); 1046 return; 1047 } 1048 1049 // prepare for callback 1050 CallbackWrapper wrapper(tag_map(), obj); 1051 1052 // check if filtered by the heap filter 1053 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) { 1054 return; 1055 } 1056 1057 // for arrays we need the length, otherwise -1 1058 bool is_array = obj->is_array(); 1059 int len = is_array ? arrayOop(obj)->length() : -1; 1060 1061 // invoke the object callback (if callback is provided) 1062 if (callbacks()->heap_iteration_callback != nullptr) { 1063 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback; 1064 jint res = (*cb)(wrapper.klass_tag(), 1065 wrapper.obj_size(), 1066 wrapper.obj_tag_p(), 1067 (jint)len, 1068 (void*)user_data()); 1069 if (check_flags_for_abort(res)) return; 1070 } 1071 1072 // for objects and classes we report primitive fields if callback provided 1073 if (callbacks()->primitive_field_callback != nullptr && obj->is_instance()) { 1074 jint res; 1075 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback; 1076 if (obj->klass() == vmClasses::Class_klass()) { 1077 res = invoke_primitive_field_callback_for_static_fields(&wrapper, 1078 obj, 1079 cb, 1080 (void*)user_data()); 1081 } else { 1082 res = invoke_primitive_field_callback_for_instance_fields(&wrapper, 1083 obj, 1084 cb, 1085 (void*)user_data()); 1086 } 1087 if (check_flags_for_abort(res)) return; 1088 } 1089 1090 // string callback 1091 if (!is_array && 1092 callbacks()->string_primitive_value_callback != nullptr && 1093 obj->klass() == vmClasses::String_klass()) { 1094 jint res = invoke_string_value_callback( 1095 callbacks()->string_primitive_value_callback, 1096 &wrapper, 1097 obj, 1098 (void*)user_data() ); 1099 if (check_flags_for_abort(res)) return; 1100 } 1101 1102 // array callback 1103 if (is_array && 1104 callbacks()->array_primitive_value_callback != nullptr && 1105 obj->is_typeArray()) { 1106 jint res = invoke_array_primitive_value_callback( 1107 callbacks()->array_primitive_value_callback, 1108 &wrapper, 1109 obj, 1110 (void*)user_data() ); 1111 if (check_flags_for_abort(res)) return; 1112 } 1113 }; 1114 1115 1116 // Deprecated function to iterate over all objects in the heap 1117 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter, 1118 Klass* klass, 1119 jvmtiHeapObjectCallback heap_object_callback, 1120 const void* user_data) 1121 { 1122 // EA based optimizations on tagged objects are already reverted. 1123 EscapeBarrier eb(object_filter == JVMTI_HEAP_OBJECT_UNTAGGED || 1124 object_filter == JVMTI_HEAP_OBJECT_EITHER, 1125 JavaThread::current()); 1126 eb.deoptimize_objects_all_threads(); 1127 Arena dead_object_arena(mtServiceability); 1128 GrowableArray <jlong> dead_objects(&dead_object_arena, 10, 0, 0); 1129 { 1130 MutexLocker ml(Heap_lock); 1131 IterateOverHeapObjectClosure blk(this, 1132 klass, 1133 object_filter, 1134 heap_object_callback, 1135 user_data); 1136 VM_HeapIterateOperation op(&blk, &dead_objects); 1137 VMThread::execute(&op); 1138 } 1139 // Post events outside of Heap_lock 1140 post_dead_objects(&dead_objects); 1141 } 1142 1143 1144 // Iterates over all objects in the heap 1145 void JvmtiTagMap::iterate_through_heap(jint heap_filter, 1146 Klass* klass, 1147 const jvmtiHeapCallbacks* callbacks, 1148 const void* user_data) 1149 { 1150 // EA based optimizations on tagged objects are already reverted. 1151 EscapeBarrier eb(!(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED), JavaThread::current()); 1152 eb.deoptimize_objects_all_threads(); 1153 1154 Arena dead_object_arena(mtServiceability); 1155 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0); 1156 { 1157 MutexLocker ml(Heap_lock); 1158 IterateThroughHeapObjectClosure blk(this, 1159 klass, 1160 heap_filter, 1161 callbacks, 1162 user_data); 1163 VM_HeapIterateOperation op(&blk, &dead_objects); 1164 VMThread::execute(&op); 1165 } 1166 // Post events outside of Heap_lock 1167 post_dead_objects(&dead_objects); 1168 } 1169 1170 void JvmtiTagMap::remove_dead_entries_locked(GrowableArray<jlong>* objects) { 1171 assert(is_locked(), "precondition"); 1172 if (_needs_cleaning) { 1173 // Recheck whether to post object free events under the lock. 1174 if (!env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) { 1175 objects = nullptr; 1176 } 1177 log_info(jvmti, table)("TagMap table needs cleaning%s", 1178 ((objects != nullptr) ? " and posting" : "")); 1179 hashmap()->remove_dead_entries(objects); 1180 _needs_cleaning = false; 1181 } 1182 } 1183 1184 void JvmtiTagMap::remove_dead_entries(GrowableArray<jlong>* objects) { 1185 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag); 1186 remove_dead_entries_locked(objects); 1187 } 1188 1189 void JvmtiTagMap::post_dead_objects(GrowableArray<jlong>* const objects) { 1190 assert(Thread::current()->is_Java_thread(), "Must post from JavaThread"); 1191 if (objects != nullptr && objects->length() > 0) { 1192 JvmtiExport::post_object_free(env(), objects); 1193 log_info(jvmti, table)("%d free object posted", objects->length()); 1194 } 1195 } 1196 1197 void JvmtiTagMap::remove_and_post_dead_objects() { 1198 ResourceMark rm; 1199 GrowableArray<jlong> objects; 1200 remove_dead_entries(&objects); 1201 post_dead_objects(&objects); 1202 } 1203 1204 void JvmtiTagMap::flush_object_free_events() { 1205 assert_not_at_safepoint(); 1206 if (env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) { 1207 { 1208 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag); 1209 // If another thread is posting events, let it finish 1210 while (_posting_events) { 1211 ml.wait(); 1212 } 1213 1214 if (!_needs_cleaning || is_empty()) { 1215 _needs_cleaning = false; 1216 return; 1217 } 1218 _posting_events = true; 1219 } // Drop the lock so we can do the cleaning on the VM thread. 1220 // Needs both cleaning and event posting (up to some other thread 1221 // getting there first after we dropped the lock). 1222 remove_and_post_dead_objects(); 1223 { 1224 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag); 1225 _posting_events = false; 1226 ml.notify_all(); 1227 } 1228 } else { 1229 remove_dead_entries(nullptr); 1230 } 1231 } 1232 1233 // support class for get_objects_with_tags 1234 1235 class TagObjectCollector : public JvmtiTagMapKeyClosure { 1236 private: 1237 JvmtiEnv* _env; 1238 JavaThread* _thread; 1239 jlong* _tags; 1240 jint _tag_count; 1241 bool _some_dead_found; 1242 1243 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs) 1244 GrowableArray<uint64_t>* _tag_results; // collected tags 1245 1246 public: 1247 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) : 1248 _env(env), 1249 _thread(JavaThread::current()), 1250 _tags((jlong*)tags), 1251 _tag_count(tag_count), 1252 _some_dead_found(false), 1253 _object_results(new (mtServiceability) GrowableArray<jobject>(1, mtServiceability)), 1254 _tag_results(new (mtServiceability) GrowableArray<uint64_t>(1, mtServiceability)) { } 1255 1256 ~TagObjectCollector() { 1257 delete _object_results; 1258 delete _tag_results; 1259 } 1260 1261 bool some_dead_found() const { return _some_dead_found; } 1262 1263 // for each tagged object check if the tag value matches 1264 // - if it matches then we create a JNI local reference to the object 1265 // and record the reference and tag value. 1266 // Always return true so the iteration continues. 1267 bool do_entry(JvmtiTagMapKey& key, jlong& value) { 1268 for (int i = 0; i < _tag_count; i++) { 1269 if (_tags[i] == value) { 1270 // The reference in this tag map could be the only (implicitly weak) 1271 // reference to that object. If we hand it out, we need to keep it live wrt 1272 // SATB marking similar to other j.l.ref.Reference referents. This is 1273 // achieved by using a phantom load in the object() accessor. 1274 oop o = key.object(); 1275 if (o == nullptr) { 1276 _some_dead_found = true; 1277 // skip this whole entry 1278 return true; 1279 } 1280 assert(o != nullptr && Universe::heap()->is_in(o), "sanity check"); 1281 jobject ref = JNIHandles::make_local(_thread, o); 1282 _object_results->append(ref); 1283 _tag_results->append(value); 1284 } 1285 } 1286 return true; 1287 } 1288 1289 // return the results from the collection 1290 // 1291 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { 1292 jvmtiError error; 1293 int count = _object_results->length(); 1294 assert(count >= 0, "sanity check"); 1295 1296 // if object_result_ptr is not null then allocate the result and copy 1297 // in the object references. 1298 if (object_result_ptr != nullptr) { 1299 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr); 1300 if (error != JVMTI_ERROR_NONE) { 1301 return error; 1302 } 1303 for (int i=0; i<count; i++) { 1304 (*object_result_ptr)[i] = _object_results->at(i); 1305 } 1306 } 1307 1308 // if tag_result_ptr is not null then allocate the result and copy 1309 // in the tag values. 1310 if (tag_result_ptr != nullptr) { 1311 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr); 1312 if (error != JVMTI_ERROR_NONE) { 1313 if (object_result_ptr != nullptr) { 1314 _env->Deallocate((unsigned char*)object_result_ptr); 1315 } 1316 return error; 1317 } 1318 for (int i=0; i<count; i++) { 1319 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i); 1320 } 1321 } 1322 1323 *count_ptr = count; 1324 return JVMTI_ERROR_NONE; 1325 } 1326 }; 1327 1328 // return the list of objects with the specified tags 1329 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags, 1330 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) { 1331 1332 TagObjectCollector collector(env(), tags, count); 1333 { 1334 // iterate over all tagged objects 1335 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag); 1336 // Can't post ObjectFree events here from a JavaThread, so this 1337 // will race with the gc_notification thread in the tiny 1338 // window where the object is not marked but hasn't been notified that 1339 // it is collected yet. 1340 entry_iterate(&collector); 1341 } 1342 return collector.result(count_ptr, object_result_ptr, tag_result_ptr); 1343 } 1344 1345 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind 1346 // (not performance critical as only used for roots) 1347 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) { 1348 switch (kind) { 1349 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL; 1350 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS; 1351 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL; 1352 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL; 1353 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD; 1354 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER; 1355 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER; 1356 } 1357 } 1358 1359 // Base class for all heap walk contexts. The base class maintains a flag 1360 // to indicate if the context is valid or not. 1361 class HeapWalkContext { 1362 private: 1363 bool _valid; 1364 public: 1365 HeapWalkContext(bool valid) { _valid = valid; } 1366 void invalidate() { _valid = false; } 1367 bool is_valid() const { return _valid; } 1368 }; 1369 1370 // A basic heap walk context for the deprecated heap walking functions. 1371 // The context for a basic heap walk are the callbacks and fields used by 1372 // the referrer caching scheme. 1373 class BasicHeapWalkContext: public HeapWalkContext { 1374 private: 1375 jvmtiHeapRootCallback _heap_root_callback; 1376 jvmtiStackReferenceCallback _stack_ref_callback; 1377 jvmtiObjectReferenceCallback _object_ref_callback; 1378 1379 // used for caching 1380 oop _last_referrer; 1381 jlong _last_referrer_tag; 1382 1383 public: 1384 BasicHeapWalkContext() : HeapWalkContext(false) { } 1385 1386 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback, 1387 jvmtiStackReferenceCallback stack_ref_callback, 1388 jvmtiObjectReferenceCallback object_ref_callback) : 1389 HeapWalkContext(true), 1390 _heap_root_callback(heap_root_callback), 1391 _stack_ref_callback(stack_ref_callback), 1392 _object_ref_callback(object_ref_callback), 1393 _last_referrer(nullptr), 1394 _last_referrer_tag(0) { 1395 } 1396 1397 // accessors 1398 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; } 1399 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; } 1400 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; } 1401 1402 oop last_referrer() const { return _last_referrer; } 1403 void set_last_referrer(oop referrer) { _last_referrer = referrer; } 1404 jlong last_referrer_tag() const { return _last_referrer_tag; } 1405 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; } 1406 }; 1407 1408 // The advanced heap walk context for the FollowReferences functions. 1409 // The context is the callbacks, and the fields used for filtering. 1410 class AdvancedHeapWalkContext: public HeapWalkContext { 1411 private: 1412 jint _heap_filter; 1413 Klass* _klass_filter; 1414 const jvmtiHeapCallbacks* _heap_callbacks; 1415 1416 public: 1417 AdvancedHeapWalkContext() : HeapWalkContext(false) { } 1418 1419 AdvancedHeapWalkContext(jint heap_filter, 1420 Klass* klass_filter, 1421 const jvmtiHeapCallbacks* heap_callbacks) : 1422 HeapWalkContext(true), 1423 _heap_filter(heap_filter), 1424 _klass_filter(klass_filter), 1425 _heap_callbacks(heap_callbacks) { 1426 } 1427 1428 // accessors 1429 jint heap_filter() const { return _heap_filter; } 1430 Klass* klass_filter() const { return _klass_filter; } 1431 1432 jvmtiHeapReferenceCallback heap_reference_callback() const { 1433 return _heap_callbacks->heap_reference_callback; 1434 }; 1435 jvmtiPrimitiveFieldCallback primitive_field_callback() const { 1436 return _heap_callbacks->primitive_field_callback; 1437 } 1438 jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const { 1439 return _heap_callbacks->array_primitive_value_callback; 1440 } 1441 jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const { 1442 return _heap_callbacks->string_primitive_value_callback; 1443 } 1444 }; 1445 1446 // The CallbackInvoker is a class with static functions that the heap walk can call 1447 // into to invoke callbacks. It works in one of two modes. The "basic" mode is 1448 // used for the deprecated IterateOverReachableObjects functions. The "advanced" 1449 // mode is for the newer FollowReferences function which supports a lot of 1450 // additional callbacks. 1451 class CallbackInvoker : AllStatic { 1452 private: 1453 // heap walk styles 1454 enum { basic, advanced }; 1455 static int _heap_walk_type; 1456 static bool is_basic_heap_walk() { return _heap_walk_type == basic; } 1457 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; } 1458 1459 // context for basic style heap walk 1460 static BasicHeapWalkContext _basic_context; 1461 static BasicHeapWalkContext* basic_context() { 1462 assert(_basic_context.is_valid(), "invalid"); 1463 return &_basic_context; 1464 } 1465 1466 // context for advanced style heap walk 1467 static AdvancedHeapWalkContext _advanced_context; 1468 static AdvancedHeapWalkContext* advanced_context() { 1469 assert(_advanced_context.is_valid(), "invalid"); 1470 return &_advanced_context; 1471 } 1472 1473 // context needed for all heap walks 1474 static JvmtiTagMap* _tag_map; 1475 static const void* _user_data; 1476 static GrowableArray<oop>* _visit_stack; 1477 static JVMTIBitSet* _bitset; 1478 1479 // accessors 1480 static JvmtiTagMap* tag_map() { return _tag_map; } 1481 static const void* user_data() { return _user_data; } 1482 static GrowableArray<oop>* visit_stack() { return _visit_stack; } 1483 1484 // if the object hasn't been visited then push it onto the visit stack 1485 // so that it will be visited later 1486 static inline bool check_for_visit(oop obj) { 1487 if (!_bitset->is_marked(obj)) visit_stack()->push(obj); 1488 return true; 1489 } 1490 1491 // invoke basic style callbacks 1492 static inline bool invoke_basic_heap_root_callback 1493 (jvmtiHeapRootKind root_kind, oop obj); 1494 static inline bool invoke_basic_stack_ref_callback 1495 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method, 1496 int slot, oop obj); 1497 static inline bool invoke_basic_object_reference_callback 1498 (jvmtiObjectReferenceKind ref_kind, oop referrer, oop referree, jint index); 1499 1500 // invoke advanced style callbacks 1501 static inline bool invoke_advanced_heap_root_callback 1502 (jvmtiHeapReferenceKind ref_kind, oop obj); 1503 static inline bool invoke_advanced_stack_ref_callback 1504 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth, 1505 jmethodID method, jlocation bci, jint slot, oop obj); 1506 static inline bool invoke_advanced_object_reference_callback 1507 (jvmtiHeapReferenceKind ref_kind, oop referrer, oop referree, jint index); 1508 1509 // used to report the value of primitive fields 1510 static inline bool report_primitive_field 1511 (jvmtiHeapReferenceKind ref_kind, oop obj, jint index, address addr, char type); 1512 1513 public: 1514 // initialize for basic mode 1515 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, 1516 GrowableArray<oop>* visit_stack, 1517 const void* user_data, 1518 BasicHeapWalkContext context, 1519 JVMTIBitSet* bitset); 1520 1521 // initialize for advanced mode 1522 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, 1523 GrowableArray<oop>* visit_stack, 1524 const void* user_data, 1525 AdvancedHeapWalkContext context, 1526 JVMTIBitSet* bitset); 1527 1528 // functions to report roots 1529 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, oop o); 1530 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth, 1531 jmethodID m, oop o); 1532 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth, 1533 jmethodID method, jlocation bci, jint slot, oop o); 1534 1535 // functions to report references 1536 static inline bool report_array_element_reference(oop referrer, oop referree, jint index); 1537 static inline bool report_class_reference(oop referrer, oop referree); 1538 static inline bool report_class_loader_reference(oop referrer, oop referree); 1539 static inline bool report_signers_reference(oop referrer, oop referree); 1540 static inline bool report_protection_domain_reference(oop referrer, oop referree); 1541 static inline bool report_superclass_reference(oop referrer, oop referree); 1542 static inline bool report_interface_reference(oop referrer, oop referree); 1543 static inline bool report_static_field_reference(oop referrer, oop referree, jint slot); 1544 static inline bool report_field_reference(oop referrer, oop referree, jint slot); 1545 static inline bool report_constant_pool_reference(oop referrer, oop referree, jint index); 1546 static inline bool report_primitive_array_values(oop array); 1547 static inline bool report_string_value(oop str); 1548 static inline bool report_primitive_instance_field(oop o, jint index, address value, char type); 1549 static inline bool report_primitive_static_field(oop o, jint index, address value, char type); 1550 }; 1551 1552 // statics 1553 int CallbackInvoker::_heap_walk_type; 1554 BasicHeapWalkContext CallbackInvoker::_basic_context; 1555 AdvancedHeapWalkContext CallbackInvoker::_advanced_context; 1556 JvmtiTagMap* CallbackInvoker::_tag_map; 1557 const void* CallbackInvoker::_user_data; 1558 GrowableArray<oop>* CallbackInvoker::_visit_stack; 1559 JVMTIBitSet* CallbackInvoker::_bitset; 1560 1561 // initialize for basic heap walk (IterateOverReachableObjects et al) 1562 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map, 1563 GrowableArray<oop>* visit_stack, 1564 const void* user_data, 1565 BasicHeapWalkContext context, 1566 JVMTIBitSet* bitset) { 1567 _tag_map = tag_map; 1568 _visit_stack = visit_stack; 1569 _user_data = user_data; 1570 _basic_context = context; 1571 _advanced_context.invalidate(); // will trigger assertion if used 1572 _heap_walk_type = basic; 1573 _bitset = bitset; 1574 } 1575 1576 // initialize for advanced heap walk (FollowReferences) 1577 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map, 1578 GrowableArray<oop>* visit_stack, 1579 const void* user_data, 1580 AdvancedHeapWalkContext context, 1581 JVMTIBitSet* bitset) { 1582 _tag_map = tag_map; 1583 _visit_stack = visit_stack; 1584 _user_data = user_data; 1585 _advanced_context = context; 1586 _basic_context.invalidate(); // will trigger assertion if used 1587 _heap_walk_type = advanced; 1588 _bitset = bitset; 1589 } 1590 1591 1592 // invoke basic style heap root callback 1593 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, oop obj) { 1594 // if we heap roots should be reported 1595 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback(); 1596 if (cb == nullptr) { 1597 return check_for_visit(obj); 1598 } 1599 1600 CallbackWrapper wrapper(tag_map(), obj); 1601 jvmtiIterationControl control = (*cb)(root_kind, 1602 wrapper.klass_tag(), 1603 wrapper.obj_size(), 1604 wrapper.obj_tag_p(), 1605 (void*)user_data()); 1606 // push root to visit stack when following references 1607 if (control == JVMTI_ITERATION_CONTINUE && 1608 basic_context()->object_ref_callback() != nullptr) { 1609 visit_stack()->push(obj); 1610 } 1611 return control != JVMTI_ITERATION_ABORT; 1612 } 1613 1614 // invoke basic style stack ref callback 1615 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind, 1616 jlong thread_tag, 1617 jint depth, 1618 jmethodID method, 1619 int slot, 1620 oop obj) { 1621 // if we stack refs should be reported 1622 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback(); 1623 if (cb == nullptr) { 1624 return check_for_visit(obj); 1625 } 1626 1627 CallbackWrapper wrapper(tag_map(), obj); 1628 jvmtiIterationControl control = (*cb)(root_kind, 1629 wrapper.klass_tag(), 1630 wrapper.obj_size(), 1631 wrapper.obj_tag_p(), 1632 thread_tag, 1633 depth, 1634 method, 1635 slot, 1636 (void*)user_data()); 1637 // push root to visit stack when following references 1638 if (control == JVMTI_ITERATION_CONTINUE && 1639 basic_context()->object_ref_callback() != nullptr) { 1640 visit_stack()->push(obj); 1641 } 1642 return control != JVMTI_ITERATION_ABORT; 1643 } 1644 1645 // invoke basic style object reference callback 1646 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind, 1647 oop referrer, 1648 oop referree, 1649 jint index) { 1650 1651 BasicHeapWalkContext* context = basic_context(); 1652 1653 // callback requires the referrer's tag. If it's the same referrer 1654 // as the last call then we use the cached value. 1655 jlong referrer_tag; 1656 if (referrer == context->last_referrer()) { 1657 referrer_tag = context->last_referrer_tag(); 1658 } else { 1659 referrer_tag = tag_for(tag_map(), referrer); 1660 } 1661 1662 // do the callback 1663 CallbackWrapper wrapper(tag_map(), referree); 1664 jvmtiObjectReferenceCallback cb = context->object_ref_callback(); 1665 jvmtiIterationControl control = (*cb)(ref_kind, 1666 wrapper.klass_tag(), 1667 wrapper.obj_size(), 1668 wrapper.obj_tag_p(), 1669 referrer_tag, 1670 index, 1671 (void*)user_data()); 1672 1673 // record referrer and referrer tag. For self-references record the 1674 // tag value from the callback as this might differ from referrer_tag. 1675 context->set_last_referrer(referrer); 1676 if (referrer == referree) { 1677 context->set_last_referrer_tag(*wrapper.obj_tag_p()); 1678 } else { 1679 context->set_last_referrer_tag(referrer_tag); 1680 } 1681 1682 if (control == JVMTI_ITERATION_CONTINUE) { 1683 return check_for_visit(referree); 1684 } else { 1685 return control != JVMTI_ITERATION_ABORT; 1686 } 1687 } 1688 1689 // invoke advanced style heap root callback 1690 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind, 1691 oop obj) { 1692 AdvancedHeapWalkContext* context = advanced_context(); 1693 1694 // check that callback is provided 1695 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 1696 if (cb == nullptr) { 1697 return check_for_visit(obj); 1698 } 1699 1700 // apply class filter 1701 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 1702 return check_for_visit(obj); 1703 } 1704 1705 // setup the callback wrapper 1706 CallbackWrapper wrapper(tag_map(), obj); 1707 1708 // apply tag filter 1709 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 1710 wrapper.klass_tag(), 1711 context->heap_filter())) { 1712 return check_for_visit(obj); 1713 } 1714 1715 // for arrays we need the length, otherwise -1 1716 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 1717 1718 // invoke the callback 1719 jint res = (*cb)(ref_kind, 1720 nullptr, // referrer info 1721 wrapper.klass_tag(), 1722 0, // referrer_class_tag is 0 for heap root 1723 wrapper.obj_size(), 1724 wrapper.obj_tag_p(), 1725 nullptr, // referrer_tag_p 1726 len, 1727 (void*)user_data()); 1728 if (res & JVMTI_VISIT_ABORT) { 1729 return false;// referrer class tag 1730 } 1731 if (res & JVMTI_VISIT_OBJECTS) { 1732 check_for_visit(obj); 1733 } 1734 return true; 1735 } 1736 1737 // report a reference from a thread stack to an object 1738 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind, 1739 jlong thread_tag, 1740 jlong tid, 1741 int depth, 1742 jmethodID method, 1743 jlocation bci, 1744 jint slot, 1745 oop obj) { 1746 AdvancedHeapWalkContext* context = advanced_context(); 1747 1748 // check that callback is provider 1749 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 1750 if (cb == nullptr) { 1751 return check_for_visit(obj); 1752 } 1753 1754 // apply class filter 1755 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 1756 return check_for_visit(obj); 1757 } 1758 1759 // setup the callback wrapper 1760 CallbackWrapper wrapper(tag_map(), obj); 1761 1762 // apply tag filter 1763 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 1764 wrapper.klass_tag(), 1765 context->heap_filter())) { 1766 return check_for_visit(obj); 1767 } 1768 1769 // setup the referrer info 1770 jvmtiHeapReferenceInfo reference_info; 1771 reference_info.stack_local.thread_tag = thread_tag; 1772 reference_info.stack_local.thread_id = tid; 1773 reference_info.stack_local.depth = depth; 1774 reference_info.stack_local.method = method; 1775 reference_info.stack_local.location = bci; 1776 reference_info.stack_local.slot = slot; 1777 1778 // for arrays we need the length, otherwise -1 1779 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 1780 1781 // call into the agent 1782 int res = (*cb)(ref_kind, 1783 &reference_info, 1784 wrapper.klass_tag(), 1785 0, // referrer_class_tag is 0 for heap root (stack) 1786 wrapper.obj_size(), 1787 wrapper.obj_tag_p(), 1788 nullptr, // referrer_tag is 0 for root 1789 len, 1790 (void*)user_data()); 1791 1792 if (res & JVMTI_VISIT_ABORT) { 1793 return false; 1794 } 1795 if (res & JVMTI_VISIT_OBJECTS) { 1796 check_for_visit(obj); 1797 } 1798 return true; 1799 } 1800 1801 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback 1802 // only for ref_kinds defined by the JVM TI spec. Otherwise, null is passed. 1803 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \ 1804 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \ 1805 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \ 1806 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \ 1807 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \ 1808 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL)) 1809 1810 // invoke the object reference callback to report a reference 1811 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind, 1812 oop referrer, 1813 oop obj, 1814 jint index) 1815 { 1816 // field index is only valid field in reference_info 1817 static jvmtiHeapReferenceInfo reference_info = { 0 }; 1818 1819 AdvancedHeapWalkContext* context = advanced_context(); 1820 1821 // check that callback is provider 1822 jvmtiHeapReferenceCallback cb = context->heap_reference_callback(); 1823 if (cb == nullptr) { 1824 return check_for_visit(obj); 1825 } 1826 1827 // apply class filter 1828 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 1829 return check_for_visit(obj); 1830 } 1831 1832 // setup the callback wrapper 1833 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj); 1834 1835 // apply tag filter 1836 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 1837 wrapper.klass_tag(), 1838 context->heap_filter())) { 1839 return check_for_visit(obj); 1840 } 1841 1842 // field index is only valid field in reference_info 1843 reference_info.field.index = index; 1844 1845 // for arrays we need the length, otherwise -1 1846 jint len = (jint)(obj->is_array() ? arrayOop(obj)->length() : -1); 1847 1848 // invoke the callback 1849 int res = (*cb)(ref_kind, 1850 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : nullptr, 1851 wrapper.klass_tag(), 1852 wrapper.referrer_klass_tag(), 1853 wrapper.obj_size(), 1854 wrapper.obj_tag_p(), 1855 wrapper.referrer_tag_p(), 1856 len, 1857 (void*)user_data()); 1858 1859 if (res & JVMTI_VISIT_ABORT) { 1860 return false; 1861 } 1862 if (res & JVMTI_VISIT_OBJECTS) { 1863 check_for_visit(obj); 1864 } 1865 return true; 1866 } 1867 1868 // report a "simple root" 1869 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, oop obj) { 1870 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL && 1871 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root"); 1872 1873 if (is_basic_heap_walk()) { 1874 // map to old style root kind 1875 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind); 1876 return invoke_basic_heap_root_callback(root_kind, obj); 1877 } else { 1878 assert(is_advanced_heap_walk(), "wrong heap walk type"); 1879 return invoke_advanced_heap_root_callback(kind, obj); 1880 } 1881 } 1882 1883 1884 // invoke the primitive array values 1885 inline bool CallbackInvoker::report_primitive_array_values(oop obj) { 1886 assert(obj->is_typeArray(), "not a primitive array"); 1887 1888 AdvancedHeapWalkContext* context = advanced_context(); 1889 assert(context->array_primitive_value_callback() != nullptr, "no callback"); 1890 1891 // apply class filter 1892 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 1893 return true; 1894 } 1895 1896 CallbackWrapper wrapper(tag_map(), obj); 1897 1898 // apply tag filter 1899 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 1900 wrapper.klass_tag(), 1901 context->heap_filter())) { 1902 return true; 1903 } 1904 1905 // invoke the callback 1906 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(), 1907 &wrapper, 1908 obj, 1909 (void*)user_data()); 1910 return (!(res & JVMTI_VISIT_ABORT)); 1911 } 1912 1913 // invoke the string value callback 1914 inline bool CallbackInvoker::report_string_value(oop str) { 1915 assert(str->klass() == vmClasses::String_klass(), "not a string"); 1916 1917 AdvancedHeapWalkContext* context = advanced_context(); 1918 assert(context->string_primitive_value_callback() != nullptr, "no callback"); 1919 1920 // apply class filter 1921 if (is_filtered_by_klass_filter(str, context->klass_filter())) { 1922 return true; 1923 } 1924 1925 CallbackWrapper wrapper(tag_map(), str); 1926 1927 // apply tag filter 1928 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 1929 wrapper.klass_tag(), 1930 context->heap_filter())) { 1931 return true; 1932 } 1933 1934 // invoke the callback 1935 int res = invoke_string_value_callback(context->string_primitive_value_callback(), 1936 &wrapper, 1937 str, 1938 (void*)user_data()); 1939 return (!(res & JVMTI_VISIT_ABORT)); 1940 } 1941 1942 // invoke the primitive field callback 1943 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind, 1944 oop obj, 1945 jint index, 1946 address addr, 1947 char type) 1948 { 1949 // for primitive fields only the index will be set 1950 static jvmtiHeapReferenceInfo reference_info = { 0 }; 1951 1952 AdvancedHeapWalkContext* context = advanced_context(); 1953 assert(context->primitive_field_callback() != nullptr, "no callback"); 1954 1955 // apply class filter 1956 if (is_filtered_by_klass_filter(obj, context->klass_filter())) { 1957 return true; 1958 } 1959 1960 CallbackWrapper wrapper(tag_map(), obj); 1961 1962 // apply tag filter 1963 if (is_filtered_by_heap_filter(wrapper.obj_tag(), 1964 wrapper.klass_tag(), 1965 context->heap_filter())) { 1966 return true; 1967 } 1968 1969 // the field index in the referrer 1970 reference_info.field.index = index; 1971 1972 // map the type 1973 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type; 1974 1975 // setup the jvalue 1976 jvalue value; 1977 copy_to_jvalue(&value, addr, value_type); 1978 1979 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback(); 1980 int res = (*cb)(ref_kind, 1981 &reference_info, 1982 wrapper.klass_tag(), 1983 wrapper.obj_tag_p(), 1984 value, 1985 value_type, 1986 (void*)user_data()); 1987 return (!(res & JVMTI_VISIT_ABORT)); 1988 } 1989 1990 1991 // instance field 1992 inline bool CallbackInvoker::report_primitive_instance_field(oop obj, 1993 jint index, 1994 address value, 1995 char type) { 1996 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD, 1997 obj, 1998 index, 1999 value, 2000 type); 2001 } 2002 2003 // static field 2004 inline bool CallbackInvoker::report_primitive_static_field(oop obj, 2005 jint index, 2006 address value, 2007 char type) { 2008 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD, 2009 obj, 2010 index, 2011 value, 2012 type); 2013 } 2014 2015 // report a JNI local (root object) to the profiler 2016 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, oop obj) { 2017 if (is_basic_heap_walk()) { 2018 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL, 2019 thread_tag, 2020 depth, 2021 m, 2022 -1, 2023 obj); 2024 } else { 2025 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL, 2026 thread_tag, tid, 2027 depth, 2028 m, 2029 (jlocation)-1, 2030 -1, 2031 obj); 2032 } 2033 } 2034 2035 2036 // report a local (stack reference, root object) 2037 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag, 2038 jlong tid, 2039 jint depth, 2040 jmethodID method, 2041 jlocation bci, 2042 jint slot, 2043 oop obj) { 2044 if (is_basic_heap_walk()) { 2045 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL, 2046 thread_tag, 2047 depth, 2048 method, 2049 slot, 2050 obj); 2051 } else { 2052 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL, 2053 thread_tag, 2054 tid, 2055 depth, 2056 method, 2057 bci, 2058 slot, 2059 obj); 2060 } 2061 } 2062 2063 // report an object referencing a class. 2064 inline bool CallbackInvoker::report_class_reference(oop referrer, oop referree) { 2065 if (is_basic_heap_walk()) { 2066 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); 2067 } else { 2068 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1); 2069 } 2070 } 2071 2072 // report a class referencing its class loader. 2073 inline bool CallbackInvoker::report_class_loader_reference(oop referrer, oop referree) { 2074 if (is_basic_heap_walk()) { 2075 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1); 2076 } else { 2077 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1); 2078 } 2079 } 2080 2081 // report a class referencing its signers. 2082 inline bool CallbackInvoker::report_signers_reference(oop referrer, oop referree) { 2083 if (is_basic_heap_walk()) { 2084 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1); 2085 } else { 2086 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1); 2087 } 2088 } 2089 2090 // report a class referencing its protection domain.. 2091 inline bool CallbackInvoker::report_protection_domain_reference(oop referrer, oop referree) { 2092 if (is_basic_heap_walk()) { 2093 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); 2094 } else { 2095 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1); 2096 } 2097 } 2098 2099 // report a class referencing its superclass. 2100 inline bool CallbackInvoker::report_superclass_reference(oop referrer, oop referree) { 2101 if (is_basic_heap_walk()) { 2102 // Send this to be consistent with past implementation 2103 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1); 2104 } else { 2105 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1); 2106 } 2107 } 2108 2109 // report a class referencing one of its interfaces. 2110 inline bool CallbackInvoker::report_interface_reference(oop referrer, oop referree) { 2111 if (is_basic_heap_walk()) { 2112 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1); 2113 } else { 2114 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1); 2115 } 2116 } 2117 2118 // report a class referencing one of its static fields. 2119 inline bool CallbackInvoker::report_static_field_reference(oop referrer, oop referree, jint slot) { 2120 if (is_basic_heap_walk()) { 2121 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot); 2122 } else { 2123 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot); 2124 } 2125 } 2126 2127 // report an array referencing an element object 2128 inline bool CallbackInvoker::report_array_element_reference(oop referrer, oop referree, jint index) { 2129 if (is_basic_heap_walk()) { 2130 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); 2131 } else { 2132 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index); 2133 } 2134 } 2135 2136 // report an object referencing an instance field object 2137 inline bool CallbackInvoker::report_field_reference(oop referrer, oop referree, jint slot) { 2138 if (is_basic_heap_walk()) { 2139 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot); 2140 } else { 2141 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot); 2142 } 2143 } 2144 2145 // report an array referencing an element object 2146 inline bool CallbackInvoker::report_constant_pool_reference(oop referrer, oop referree, jint index) { 2147 if (is_basic_heap_walk()) { 2148 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index); 2149 } else { 2150 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index); 2151 } 2152 } 2153 2154 // A supporting closure used to process simple roots 2155 class SimpleRootsClosure : public OopClosure { 2156 private: 2157 jvmtiHeapReferenceKind _kind; 2158 bool _continue; 2159 2160 jvmtiHeapReferenceKind root_kind() { return _kind; } 2161 2162 public: 2163 void set_kind(jvmtiHeapReferenceKind kind) { 2164 _kind = kind; 2165 _continue = true; 2166 } 2167 2168 inline bool stopped() { 2169 return !_continue; 2170 } 2171 2172 void do_oop(oop* obj_p) { 2173 // iteration has terminated 2174 if (stopped()) { 2175 return; 2176 } 2177 2178 oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p); 2179 // ignore null 2180 if (o == nullptr) { 2181 return; 2182 } 2183 2184 assert(Universe::heap()->is_in(o), "should be impossible"); 2185 2186 jvmtiHeapReferenceKind kind = root_kind(); 2187 2188 // invoke the callback 2189 _continue = CallbackInvoker::report_simple_root(kind, o); 2190 2191 } 2192 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } 2193 }; 2194 2195 // A supporting closure used to process JNI locals 2196 class JNILocalRootsClosure : public OopClosure { 2197 private: 2198 jlong _thread_tag; 2199 jlong _tid; 2200 jint _depth; 2201 jmethodID _method; 2202 bool _continue; 2203 public: 2204 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) { 2205 _thread_tag = thread_tag; 2206 _tid = tid; 2207 _depth = depth; 2208 _method = method; 2209 _continue = true; 2210 } 2211 2212 inline bool stopped() { 2213 return !_continue; 2214 } 2215 2216 void do_oop(oop* obj_p) { 2217 // iteration has terminated 2218 if (stopped()) { 2219 return; 2220 } 2221 2222 oop o = *obj_p; 2223 // ignore null 2224 if (o == nullptr) { 2225 return; 2226 } 2227 2228 // invoke the callback 2229 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o); 2230 } 2231 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); } 2232 }; 2233 2234 // Helper class to collect/report stack references. 2235 class StackRefCollector { 2236 private: 2237 JvmtiTagMap* _tag_map; 2238 JNILocalRootsClosure* _blk; 2239 // java_thread is needed only to report JNI local on top native frame; 2240 // I.e. it's required only for platform/carrier threads or mounted virtual threads. 2241 JavaThread* _java_thread; 2242 2243 oop _threadObj; 2244 jlong _thread_tag; 2245 jlong _tid; 2246 2247 bool _is_top_frame; 2248 int _depth; 2249 frame* _last_entry_frame; 2250 2251 bool report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset); 2252 bool report_native_stack_refs(jmethodID method); 2253 2254 public: 2255 StackRefCollector(JvmtiTagMap* tag_map, JNILocalRootsClosure* blk, JavaThread* java_thread) 2256 : _tag_map(tag_map), _blk(blk), _java_thread(java_thread), 2257 _threadObj(nullptr), _thread_tag(0), _tid(0), 2258 _is_top_frame(true), _depth(0), _last_entry_frame(nullptr) 2259 { 2260 } 2261 2262 bool set_thread(oop o); 2263 // Sets the thread and reports the reference to it with the specified kind. 2264 bool set_thread(jvmtiHeapReferenceKind kind, oop o); 2265 2266 bool do_frame(vframe* vf); 2267 // Handles frames until vf->sender() is null. 2268 bool process_frames(vframe* vf); 2269 }; 2270 2271 bool StackRefCollector::set_thread(oop o) { 2272 _threadObj = o; 2273 _thread_tag = tag_for(_tag_map, _threadObj); 2274 _tid = java_lang_Thread::thread_id(_threadObj); 2275 2276 _is_top_frame = true; 2277 _depth = 0; 2278 _last_entry_frame = nullptr; 2279 2280 return true; 2281 } 2282 2283 bool StackRefCollector::set_thread(jvmtiHeapReferenceKind kind, oop o) { 2284 return set_thread(o) 2285 && CallbackInvoker::report_simple_root(kind, _threadObj); 2286 } 2287 2288 bool StackRefCollector::report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset) { 2289 for (int index = 0; index < values->size(); index++) { 2290 if (values->at(index)->type() == T_OBJECT) { 2291 oop obj = values->obj_at(index)(); 2292 if (obj == nullptr) { 2293 continue; 2294 } 2295 // stack reference 2296 if (!CallbackInvoker::report_stack_ref_root(_thread_tag, _tid, _depth, method, 2297 bci, slot_offset + index, obj)) { 2298 return false; 2299 } 2300 } 2301 } 2302 return true; 2303 } 2304 2305 bool StackRefCollector::report_native_stack_refs(jmethodID method) { 2306 _blk->set_context(_thread_tag, _tid, _depth, method); 2307 if (_is_top_frame) { 2308 // JNI locals for the top frame. 2309 if (_java_thread != nullptr) { 2310 _java_thread->active_handles()->oops_do(_blk); 2311 if (_blk->stopped()) { 2312 return false; 2313 } 2314 } 2315 } else { 2316 if (_last_entry_frame != nullptr) { 2317 // JNI locals for the entry frame. 2318 assert(_last_entry_frame->is_entry_frame(), "checking"); 2319 _last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(_blk); 2320 if (_blk->stopped()) { 2321 return false; 2322 } 2323 } 2324 } 2325 return true; 2326 } 2327 2328 bool StackRefCollector::do_frame(vframe* vf) { 2329 if (vf->is_java_frame()) { 2330 // java frame (interpreted, compiled, ...) 2331 javaVFrame* jvf = javaVFrame::cast(vf); 2332 2333 jmethodID method = jvf->method()->jmethod_id(); 2334 2335 if (!(jvf->method()->is_native())) { 2336 jlocation bci = (jlocation)jvf->bci(); 2337 StackValueCollection* locals = jvf->locals(); 2338 if (!report_java_stack_refs(locals, method, bci, 0)) { 2339 return false; 2340 } 2341 if (!report_java_stack_refs(jvf->expressions(), method, bci, locals->size())) { 2342 return false; 2343 } 2344 2345 // Follow oops from compiled nmethod. 2346 if (jvf->cb() != nullptr && jvf->cb()->is_nmethod()) { 2347 _blk->set_context(_thread_tag, _tid, _depth, method); 2348 // Need to apply load barriers for unmounted vthreads. 2349 nmethod* nm = jvf->cb()->as_nmethod(); 2350 nm->run_nmethod_entry_barrier(); 2351 nm->oops_do(_blk); 2352 if (_blk->stopped()) { 2353 return false; 2354 } 2355 } 2356 } else { 2357 // native frame 2358 if (!report_native_stack_refs(method)) { 2359 return false; 2360 } 2361 } 2362 _last_entry_frame = nullptr; 2363 _depth++; 2364 } else { 2365 // externalVFrame - for an entry frame then we report the JNI locals 2366 // when we find the corresponding javaVFrame 2367 frame* fr = vf->frame_pointer(); 2368 assert(fr != nullptr, "sanity check"); 2369 if (fr->is_entry_frame()) { 2370 _last_entry_frame = fr; 2371 } 2372 } 2373 2374 _is_top_frame = false; 2375 2376 return true; 2377 } 2378 2379 bool StackRefCollector::process_frames(vframe* vf) { 2380 while (vf != nullptr) { 2381 if (!do_frame(vf)) { 2382 return false; 2383 } 2384 vf = vf->sender(); 2385 } 2386 return true; 2387 } 2388 2389 2390 // A VM operation to iterate over objects that are reachable from 2391 // a set of roots or an initial object. 2392 // 2393 // For VM_HeapWalkOperation the set of roots used is :- 2394 // 2395 // - All JNI global references 2396 // - All inflated monitors 2397 // - All classes loaded by the boot class loader (or all classes 2398 // in the event that class unloading is disabled) 2399 // - All java threads 2400 // - For each java thread then all locals and JNI local references 2401 // on the thread's execution stack 2402 // - All visible/explainable objects from Universes::oops_do 2403 // 2404 class VM_HeapWalkOperation: public VM_Operation { 2405 private: 2406 enum { 2407 initial_visit_stack_size = 4000 2408 }; 2409 2410 bool _is_advanced_heap_walk; // indicates FollowReferences 2411 JvmtiTagMap* _tag_map; 2412 Handle _initial_object; 2413 GrowableArray<oop>* _visit_stack; // the visit stack 2414 2415 JVMTIBitSet _bitset; 2416 2417 // Dead object tags in JvmtiTagMap 2418 GrowableArray<jlong>* _dead_objects; 2419 2420 bool _following_object_refs; // are we following object references 2421 2422 bool _reporting_primitive_fields; // optional reporting 2423 bool _reporting_primitive_array_values; 2424 bool _reporting_string_values; 2425 2426 GrowableArray<oop>* create_visit_stack() { 2427 return new (mtServiceability) GrowableArray<oop>(initial_visit_stack_size, mtServiceability); 2428 } 2429 2430 // accessors 2431 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; } 2432 JvmtiTagMap* tag_map() const { return _tag_map; } 2433 Handle initial_object() const { return _initial_object; } 2434 2435 bool is_following_references() const { return _following_object_refs; } 2436 2437 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; } 2438 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; } 2439 bool is_reporting_string_values() const { return _reporting_string_values; } 2440 2441 GrowableArray<oop>* visit_stack() const { return _visit_stack; } 2442 2443 // iterate over the various object types 2444 inline bool iterate_over_array(oop o); 2445 inline bool iterate_over_type_array(oop o); 2446 inline bool iterate_over_class(oop o); 2447 inline bool iterate_over_object(oop o); 2448 2449 // root collection 2450 inline bool collect_simple_roots(); 2451 inline bool collect_stack_roots(); 2452 inline bool collect_stack_refs(JavaThread* java_thread, JNILocalRootsClosure* blk); 2453 inline bool collect_vthread_stack_refs(oop vt); 2454 2455 // visit an object 2456 inline bool visit(oop o); 2457 2458 public: 2459 VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2460 Handle initial_object, 2461 BasicHeapWalkContext callbacks, 2462 const void* user_data, 2463 GrowableArray<jlong>* objects); 2464 2465 VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2466 Handle initial_object, 2467 AdvancedHeapWalkContext callbacks, 2468 const void* user_data, 2469 GrowableArray<jlong>* objects); 2470 2471 ~VM_HeapWalkOperation(); 2472 2473 VMOp_Type type() const { return VMOp_HeapWalkOperation; } 2474 void doit(); 2475 }; 2476 2477 2478 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2479 Handle initial_object, 2480 BasicHeapWalkContext callbacks, 2481 const void* user_data, 2482 GrowableArray<jlong>* objects) { 2483 _is_advanced_heap_walk = false; 2484 _tag_map = tag_map; 2485 _initial_object = initial_object; 2486 _following_object_refs = (callbacks.object_ref_callback() != nullptr); 2487 _reporting_primitive_fields = false; 2488 _reporting_primitive_array_values = false; 2489 _reporting_string_values = false; 2490 _visit_stack = create_visit_stack(); 2491 _dead_objects = objects; 2492 2493 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, _visit_stack, user_data, callbacks, &_bitset); 2494 } 2495 2496 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map, 2497 Handle initial_object, 2498 AdvancedHeapWalkContext callbacks, 2499 const void* user_data, 2500 GrowableArray<jlong>* objects) { 2501 _is_advanced_heap_walk = true; 2502 _tag_map = tag_map; 2503 _initial_object = initial_object; 2504 _following_object_refs = true; 2505 _reporting_primitive_fields = (callbacks.primitive_field_callback() != nullptr);; 2506 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != nullptr);; 2507 _reporting_string_values = (callbacks.string_primitive_value_callback() != nullptr);; 2508 _visit_stack = create_visit_stack(); 2509 _dead_objects = objects; 2510 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, _visit_stack, user_data, callbacks, &_bitset); 2511 } 2512 2513 VM_HeapWalkOperation::~VM_HeapWalkOperation() { 2514 if (_following_object_refs) { 2515 assert(_visit_stack != nullptr, "checking"); 2516 delete _visit_stack; 2517 _visit_stack = nullptr; 2518 } 2519 } 2520 2521 // an array references its class and has a reference to 2522 // each element in the array 2523 inline bool VM_HeapWalkOperation::iterate_over_array(oop o) { 2524 objArrayOop array = objArrayOop(o); 2525 2526 // array reference to its class 2527 oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror(); 2528 if (!CallbackInvoker::report_class_reference(o, mirror)) { 2529 return false; 2530 } 2531 2532 // iterate over the array and report each reference to a 2533 // non-null element 2534 for (int index=0; index<array->length(); index++) { 2535 oop elem = array->obj_at(index); 2536 if (elem == nullptr) { 2537 continue; 2538 } 2539 2540 // report the array reference o[index] = elem 2541 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) { 2542 return false; 2543 } 2544 } 2545 return true; 2546 } 2547 2548 // a type array references its class 2549 inline bool VM_HeapWalkOperation::iterate_over_type_array(oop o) { 2550 Klass* k = o->klass(); 2551 oop mirror = k->java_mirror(); 2552 if (!CallbackInvoker::report_class_reference(o, mirror)) { 2553 return false; 2554 } 2555 2556 // report the array contents if required 2557 if (is_reporting_primitive_array_values()) { 2558 if (!CallbackInvoker::report_primitive_array_values(o)) { 2559 return false; 2560 } 2561 } 2562 return true; 2563 } 2564 2565 #ifdef ASSERT 2566 // verify that a static oop field is in range 2567 static inline bool verify_static_oop(InstanceKlass* ik, 2568 oop mirror, int offset) { 2569 address obj_p = cast_from_oop<address>(mirror) + offset; 2570 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror); 2571 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize); 2572 assert(end >= start, "sanity check"); 2573 2574 if (obj_p >= start && obj_p < end) { 2575 return true; 2576 } else { 2577 return false; 2578 } 2579 } 2580 #endif // #ifdef ASSERT 2581 2582 // a class references its super class, interfaces, class loader, ... 2583 // and finally its static fields 2584 inline bool VM_HeapWalkOperation::iterate_over_class(oop java_class) { 2585 int i; 2586 Klass* klass = java_lang_Class::as_Klass(java_class); 2587 2588 if (klass->is_instance_klass()) { 2589 InstanceKlass* ik = InstanceKlass::cast(klass); 2590 2591 // Ignore the class if it hasn't been initialized yet 2592 if (!ik->is_linked()) { 2593 return true; 2594 } 2595 2596 // get the java mirror 2597 oop mirror = klass->java_mirror(); 2598 2599 // super (only if something more interesting than java.lang.Object) 2600 InstanceKlass* java_super = ik->java_super(); 2601 if (java_super != nullptr && java_super != vmClasses::Object_klass()) { 2602 oop super = java_super->java_mirror(); 2603 if (!CallbackInvoker::report_superclass_reference(mirror, super)) { 2604 return false; 2605 } 2606 } 2607 2608 // class loader 2609 oop cl = ik->class_loader(); 2610 if (cl != nullptr) { 2611 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) { 2612 return false; 2613 } 2614 } 2615 2616 // protection domain 2617 oop pd = ik->protection_domain(); 2618 if (pd != nullptr) { 2619 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) { 2620 return false; 2621 } 2622 } 2623 2624 // signers 2625 oop signers = ik->signers(); 2626 if (signers != nullptr) { 2627 if (!CallbackInvoker::report_signers_reference(mirror, signers)) { 2628 return false; 2629 } 2630 } 2631 2632 // references from the constant pool 2633 { 2634 ConstantPool* pool = ik->constants(); 2635 for (int i = 1; i < pool->length(); i++) { 2636 constantTag tag = pool->tag_at(i).value(); 2637 if (tag.is_string() || tag.is_klass() || tag.is_unresolved_klass()) { 2638 oop entry; 2639 if (tag.is_string()) { 2640 entry = pool->resolved_string_at(i); 2641 // If the entry is non-null it is resolved. 2642 if (entry == nullptr) { 2643 continue; 2644 } 2645 } else if (tag.is_klass()) { 2646 entry = pool->resolved_klass_at(i)->java_mirror(); 2647 } else { 2648 // Code generated by JIT compilers might not resolve constant 2649 // pool entries. Treat them as resolved if they are loaded. 2650 assert(tag.is_unresolved_klass(), "must be"); 2651 constantPoolHandle cp(Thread::current(), pool); 2652 Klass* klass = ConstantPool::klass_at_if_loaded(cp, i); 2653 if (klass == nullptr) { 2654 continue; 2655 } 2656 entry = klass->java_mirror(); 2657 } 2658 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) { 2659 return false; 2660 } 2661 } 2662 } 2663 } 2664 2665 // interfaces 2666 // (These will already have been reported as references from the constant pool 2667 // but are specified by IterateOverReachableObjects and must be reported). 2668 Array<InstanceKlass*>* interfaces = ik->local_interfaces(); 2669 for (i = 0; i < interfaces->length(); i++) { 2670 oop interf = interfaces->at(i)->java_mirror(); 2671 if (interf == nullptr) { 2672 continue; 2673 } 2674 if (!CallbackInvoker::report_interface_reference(mirror, interf)) { 2675 return false; 2676 } 2677 } 2678 2679 // iterate over the static fields 2680 2681 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass); 2682 for (i=0; i<field_map->field_count(); i++) { 2683 ClassFieldDescriptor* field = field_map->field_at(i); 2684 char type = field->field_type(); 2685 if (!is_primitive_field_type(type)) { 2686 oop fld_o = mirror->obj_field(field->field_offset()); 2687 assert(verify_static_oop(ik, mirror, field->field_offset()), "sanity check"); 2688 if (fld_o != nullptr) { 2689 int slot = field->field_index(); 2690 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) { 2691 delete field_map; 2692 return false; 2693 } 2694 } 2695 } else { 2696 if (is_reporting_primitive_fields()) { 2697 address addr = cast_from_oop<address>(mirror) + field->field_offset(); 2698 int slot = field->field_index(); 2699 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) { 2700 delete field_map; 2701 return false; 2702 } 2703 } 2704 } 2705 } 2706 delete field_map; 2707 2708 return true; 2709 } 2710 2711 return true; 2712 } 2713 2714 // an object references a class and its instance fields 2715 // (static fields are ignored here as we report these as 2716 // references from the class). 2717 inline bool VM_HeapWalkOperation::iterate_over_object(oop o) { 2718 // reference to the class 2719 if (!CallbackInvoker::report_class_reference(o, o->klass()->java_mirror())) { 2720 return false; 2721 } 2722 2723 // iterate over instance fields 2724 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o); 2725 for (int i=0; i<field_map->field_count(); i++) { 2726 ClassFieldDescriptor* field = field_map->field_at(i); 2727 char type = field->field_type(); 2728 if (!is_primitive_field_type(type)) { 2729 oop fld_o = o->obj_field_access<AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF>(field->field_offset()); 2730 // ignore any objects that aren't visible to profiler 2731 if (fld_o != nullptr) { 2732 assert(Universe::heap()->is_in(fld_o), "unsafe code should not " 2733 "have references to Klass* anymore"); 2734 int slot = field->field_index(); 2735 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) { 2736 return false; 2737 } 2738 } 2739 } else { 2740 if (is_reporting_primitive_fields()) { 2741 // primitive instance field 2742 address addr = cast_from_oop<address>(o) + field->field_offset(); 2743 int slot = field->field_index(); 2744 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) { 2745 return false; 2746 } 2747 } 2748 } 2749 } 2750 2751 // if the object is a java.lang.String 2752 if (is_reporting_string_values() && 2753 o->klass() == vmClasses::String_klass()) { 2754 if (!CallbackInvoker::report_string_value(o)) { 2755 return false; 2756 } 2757 } 2758 return true; 2759 } 2760 2761 2762 // Collects all simple (non-stack) roots except for threads; 2763 // threads are handled in collect_stack_roots() as an optimization. 2764 // if there's a heap root callback provided then the callback is 2765 // invoked for each simple root. 2766 // if an object reference callback is provided then all simple 2767 // roots are pushed onto the marking stack so that they can be 2768 // processed later 2769 // 2770 inline bool VM_HeapWalkOperation::collect_simple_roots() { 2771 SimpleRootsClosure blk; 2772 2773 // JNI globals 2774 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL); 2775 JNIHandles::oops_do(&blk); 2776 if (blk.stopped()) { 2777 return false; 2778 } 2779 2780 // Preloaded classes and loader from the system dictionary 2781 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS); 2782 CLDToOopClosure cld_closure(&blk, false); 2783 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure); 2784 if (blk.stopped()) { 2785 return false; 2786 } 2787 2788 // threads are now handled in collect_stack_roots() 2789 2790 // Other kinds of roots maintained by HotSpot 2791 // Many of these won't be visible but others (such as instances of important 2792 // exceptions) will be visible. 2793 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER); 2794 Universe::vm_global()->oops_do(&blk); 2795 if (blk.stopped()) { 2796 return false; 2797 } 2798 2799 return true; 2800 } 2801 2802 // Reports the thread as JVMTI_HEAP_REFERENCE_THREAD, 2803 // walks the stack of the thread, finds all references (locals 2804 // and JNI calls) and reports these as stack references. 2805 inline bool VM_HeapWalkOperation::collect_stack_refs(JavaThread* java_thread, 2806 JNILocalRootsClosure* blk) 2807 { 2808 oop threadObj = java_thread->threadObj(); 2809 oop mounted_vt = java_thread->is_vthread_mounted() ? java_thread->vthread() : nullptr; 2810 if (mounted_vt != nullptr && !JvmtiEnvBase::is_vthread_alive(mounted_vt)) { 2811 mounted_vt = nullptr; 2812 } 2813 assert(threadObj != nullptr, "sanity check"); 2814 2815 StackRefCollector stack_collector(tag_map(), blk, java_thread); 2816 2817 if (!java_thread->has_last_Java_frame()) { 2818 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) { 2819 return false; 2820 } 2821 // no last java frame but there may be JNI locals 2822 blk->set_context(tag_for(_tag_map, threadObj), java_lang_Thread::thread_id(threadObj), 0, (jmethodID)nullptr); 2823 java_thread->active_handles()->oops_do(blk); 2824 return !blk->stopped(); 2825 } 2826 // vframes are resource allocated 2827 Thread* current_thread = Thread::current(); 2828 ResourceMark rm(current_thread); 2829 HandleMark hm(current_thread); 2830 2831 RegisterMap reg_map(java_thread, 2832 RegisterMap::UpdateMap::include, 2833 RegisterMap::ProcessFrames::include, 2834 RegisterMap::WalkContinuation::include); 2835 2836 // first handle mounted vthread (if any) 2837 if (mounted_vt != nullptr) { 2838 frame f = java_thread->last_frame(); 2839 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread); 2840 // report virtual thread as JVMTI_HEAP_REFERENCE_OTHER 2841 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_OTHER, mounted_vt)) { 2842 return false; 2843 } 2844 // split virtual thread and carrier thread stacks by vthread entry ("enterSpecial") frame, 2845 // consider vthread entry frame as the last vthread stack frame 2846 while (vf != nullptr) { 2847 if (!stack_collector.do_frame(vf)) { 2848 return false; 2849 } 2850 if (vf->is_vthread_entry()) { 2851 break; 2852 } 2853 vf = vf->sender(); 2854 } 2855 } 2856 // Platform or carrier thread. 2857 vframe* vf = JvmtiEnvBase::get_cthread_last_java_vframe(java_thread, ®_map); 2858 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) { 2859 return false; 2860 } 2861 return stack_collector.process_frames(vf); 2862 } 2863 2864 2865 // Collects the simple roots for all threads and collects all 2866 // stack roots - for each thread it walks the execution 2867 // stack to find all references and local JNI refs. 2868 inline bool VM_HeapWalkOperation::collect_stack_roots() { 2869 JNILocalRootsClosure blk; 2870 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) { 2871 oop threadObj = thread->threadObj(); 2872 if (threadObj != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view()) { 2873 if (!collect_stack_refs(thread, &blk)) { 2874 return false; 2875 } 2876 } 2877 } 2878 return true; 2879 } 2880 2881 // Reports stack references for the unmounted virtual thread. 2882 inline bool VM_HeapWalkOperation::collect_vthread_stack_refs(oop vt) { 2883 if (!JvmtiEnvBase::is_vthread_alive(vt)) { 2884 return true; 2885 } 2886 ContinuationWrapper cont(java_lang_VirtualThread::continuation(vt)); 2887 if (cont.is_empty()) { 2888 return true; 2889 } 2890 assert(!cont.is_mounted(), "sanity check"); 2891 2892 stackChunkOop chunk = cont.last_nonempty_chunk(); 2893 if (chunk == nullptr || chunk->is_empty()) { 2894 return true; 2895 } 2896 2897 // vframes are resource allocated 2898 Thread* current_thread = Thread::current(); 2899 ResourceMark rm(current_thread); 2900 HandleMark hm(current_thread); 2901 2902 RegisterMap reg_map(cont.continuation(), RegisterMap::UpdateMap::include); 2903 2904 JNILocalRootsClosure blk; 2905 // JavaThread is not required for unmounted virtual threads 2906 StackRefCollector stack_collector(tag_map(), &blk, nullptr); 2907 // reference to the vthread is already reported 2908 if (!stack_collector.set_thread(vt)) { 2909 return false; 2910 } 2911 2912 frame fr = chunk->top_frame(®_map); 2913 vframe* vf = vframe::new_vframe(&fr, ®_map, nullptr); 2914 return stack_collector.process_frames(vf); 2915 } 2916 2917 // visit an object 2918 // first mark the object as visited 2919 // second get all the outbound references from this object (in other words, all 2920 // the objects referenced by this object). 2921 // 2922 bool VM_HeapWalkOperation::visit(oop o) { 2923 // mark object as visited 2924 assert(!_bitset.is_marked(o), "can't visit same object more than once"); 2925 _bitset.mark_obj(o); 2926 2927 // instance 2928 if (o->is_instance()) { 2929 if (o->klass() == vmClasses::Class_klass()) { 2930 if (!java_lang_Class::is_primitive(o)) { 2931 // a java.lang.Class 2932 return iterate_over_class(o); 2933 } 2934 } else { 2935 // we report stack references only when initial object is not specified 2936 // (in the case we start from heap roots which include platform thread stack references) 2937 if (initial_object().is_null() && java_lang_VirtualThread::is_subclass(o->klass())) { 2938 if (!collect_vthread_stack_refs(o)) { 2939 return false; 2940 } 2941 } 2942 return iterate_over_object(o); 2943 } 2944 } 2945 2946 // object array 2947 if (o->is_objArray()) { 2948 return iterate_over_array(o); 2949 } 2950 2951 // type array 2952 if (o->is_typeArray()) { 2953 return iterate_over_type_array(o); 2954 } 2955 2956 return true; 2957 } 2958 2959 void VM_HeapWalkOperation::doit() { 2960 ResourceMark rm; 2961 ClassFieldMapCacheMark cm; 2962 2963 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects); 2964 2965 assert(visit_stack()->is_empty(), "visit stack must be empty"); 2966 2967 // the heap walk starts with an initial object or the heap roots 2968 if (initial_object().is_null()) { 2969 // can result in a big performance boost for an agent that is 2970 // focused on analyzing references in the thread stacks. 2971 if (!collect_stack_roots()) return; 2972 2973 if (!collect_simple_roots()) return; 2974 } else { 2975 visit_stack()->push(initial_object()()); 2976 } 2977 2978 // object references required 2979 if (is_following_references()) { 2980 2981 // visit each object until all reachable objects have been 2982 // visited or the callback asked to terminate the iteration. 2983 while (!visit_stack()->is_empty()) { 2984 oop o = visit_stack()->pop(); 2985 if (!_bitset.is_marked(o)) { 2986 if (!visit(o)) { 2987 break; 2988 } 2989 } 2990 } 2991 } 2992 } 2993 2994 // iterate over all objects that are reachable from a set of roots 2995 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback, 2996 jvmtiStackReferenceCallback stack_ref_callback, 2997 jvmtiObjectReferenceCallback object_ref_callback, 2998 const void* user_data) { 2999 // VTMS transitions must be disabled before the EscapeBarrier. 3000 JvmtiVTMSTransitionDisabler disabler; 3001 3002 JavaThread* jt = JavaThread::current(); 3003 EscapeBarrier eb(true, jt); 3004 eb.deoptimize_objects_all_threads(); 3005 Arena dead_object_arena(mtServiceability); 3006 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0); 3007 3008 { 3009 MutexLocker ml(Heap_lock); 3010 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback); 3011 VM_HeapWalkOperation op(this, Handle(), context, user_data, &dead_objects); 3012 VMThread::execute(&op); 3013 } 3014 // Post events outside of Heap_lock 3015 post_dead_objects(&dead_objects); 3016 } 3017 3018 // iterate over all objects that are reachable from a given object 3019 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object, 3020 jvmtiObjectReferenceCallback object_ref_callback, 3021 const void* user_data) { 3022 oop obj = JNIHandles::resolve(object); 3023 Handle initial_object(Thread::current(), obj); 3024 3025 Arena dead_object_arena(mtServiceability); 3026 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0); 3027 3028 JvmtiVTMSTransitionDisabler disabler; 3029 3030 { 3031 MutexLocker ml(Heap_lock); 3032 BasicHeapWalkContext context(nullptr, nullptr, object_ref_callback); 3033 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects); 3034 VMThread::execute(&op); 3035 } 3036 // Post events outside of Heap_lock 3037 post_dead_objects(&dead_objects); 3038 } 3039 3040 // follow references from an initial object or the GC roots 3041 void JvmtiTagMap::follow_references(jint heap_filter, 3042 Klass* klass, 3043 jobject object, 3044 const jvmtiHeapCallbacks* callbacks, 3045 const void* user_data) 3046 { 3047 // VTMS transitions must be disabled before the EscapeBarrier. 3048 JvmtiVTMSTransitionDisabler disabler; 3049 3050 oop obj = JNIHandles::resolve(object); 3051 JavaThread* jt = JavaThread::current(); 3052 Handle initial_object(jt, obj); 3053 // EA based optimizations that are tagged or reachable from initial_object are already reverted. 3054 EscapeBarrier eb(initial_object.is_null() && 3055 !(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED), 3056 jt); 3057 eb.deoptimize_objects_all_threads(); 3058 3059 Arena dead_object_arena(mtServiceability); 3060 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0); 3061 3062 { 3063 MutexLocker ml(Heap_lock); 3064 AdvancedHeapWalkContext context(heap_filter, klass, callbacks); 3065 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects); 3066 VMThread::execute(&op); 3067 } 3068 // Post events outside of Heap_lock 3069 post_dead_objects(&dead_objects); 3070 } 3071 3072 // Verify gc_notification follows set_needs_cleaning. 3073 DEBUG_ONLY(static bool notified_needs_cleaning = false;) 3074 3075 void JvmtiTagMap::set_needs_cleaning() { 3076 assert(SafepointSynchronize::is_at_safepoint(), "called in gc pause"); 3077 assert(Thread::current()->is_VM_thread(), "should be the VM thread"); 3078 // Can't assert !notified_needs_cleaning; a partial GC might be upgraded 3079 // to a full GC and do this twice without intervening gc_notification. 3080 DEBUG_ONLY(notified_needs_cleaning = true;) 3081 3082 JvmtiEnvIterator it; 3083 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) { 3084 JvmtiTagMap* tag_map = env->tag_map_acquire(); 3085 if (tag_map != nullptr) { 3086 tag_map->_needs_cleaning = !tag_map->is_empty(); 3087 } 3088 } 3089 } 3090 3091 void JvmtiTagMap::gc_notification(size_t num_dead_entries) { 3092 assert(notified_needs_cleaning, "missing GC notification"); 3093 DEBUG_ONLY(notified_needs_cleaning = false;) 3094 3095 // Notify ServiceThread if there's work to do. 3096 { 3097 MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag); 3098 _has_object_free_events = (num_dead_entries != 0); 3099 if (_has_object_free_events) ml.notify_all(); 3100 } 3101 3102 // If no dead entries then cancel cleaning requests. 3103 if (num_dead_entries == 0) { 3104 JvmtiEnvIterator it; 3105 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) { 3106 JvmtiTagMap* tag_map = env->tag_map_acquire(); 3107 if (tag_map != nullptr) { 3108 MutexLocker ml (tag_map->lock(), Mutex::_no_safepoint_check_flag); 3109 tag_map->_needs_cleaning = false; 3110 } 3111 } 3112 } 3113 } 3114 3115 // Used by ServiceThread to discover there is work to do. 3116 bool JvmtiTagMap::has_object_free_events_and_reset() { 3117 assert_lock_strong(Service_lock); 3118 bool result = _has_object_free_events; 3119 _has_object_free_events = false; 3120 return result; 3121 } 3122 3123 // Used by ServiceThread to clean up tagmaps. 3124 void JvmtiTagMap::flush_all_object_free_events() { 3125 JavaThread* thread = JavaThread::current(); 3126 JvmtiEnvIterator it; 3127 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) { 3128 JvmtiTagMap* tag_map = env->tag_map_acquire(); 3129 if (tag_map != nullptr) { 3130 tag_map->flush_object_free_events(); 3131 ThreadBlockInVM tbiv(thread); // Be safepoint-polite while looping. 3132 } 3133 } 3134 }