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