1 /*
2 * Copyright (c) 2017, 2021, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "precompiled.hpp"
27 #include "gc/shared/tlab_globals.hpp"
28 #include "gc/shenandoah/shenandoahAsserts.hpp"
29 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
30 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
31 #include "gc/shenandoah/shenandoahGeneration.hpp"
32 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
33 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
34 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
35 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
36 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
37 #include "gc/shenandoah/shenandoahUtils.hpp"
38 #include "gc/shenandoah/shenandoahVerifier.hpp"
39 #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
40 #include "memory/allocation.hpp"
41 #include "memory/iterator.inline.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "oops/compressedOops.inline.hpp"
44 #include "runtime/atomic.hpp"
45 #include "runtime/orderAccess.hpp"
46 #include "runtime/threads.hpp"
47 #include "utilities/align.hpp"
48
49 // Avoid name collision on verify_oop (defined in macroAssembler_arm.hpp)
50 #ifdef verify_oop
51 #undef verify_oop
52 #endif
53
54 static bool is_instance_ref_klass(Klass* k) {
55 return k->is_instance_klass() && InstanceKlass::cast(k)->reference_type() != REF_NONE;
56 }
57
58 class ShenandoahIgnoreReferenceDiscoverer : public ReferenceDiscoverer {
59 public:
60 virtual bool discover_reference(oop obj, ReferenceType type) {
61 return true;
62 }
63 };
64
65 class ShenandoahVerifyOopClosure : public BasicOopIterateClosure {
66 private:
67 const char* _phase;
68 ShenandoahVerifier::VerifyOptions _options;
69 ShenandoahVerifierStack* _stack;
70 ShenandoahHeap* _heap;
71 MarkBitMap* _map;
72 ShenandoahLivenessData* _ld;
73 void* _interior_loc;
74 oop _loc;
75 ShenandoahGeneration* _generation;
76
77 public:
78 ShenandoahVerifyOopClosure(ShenandoahVerifierStack* stack, MarkBitMap* map, ShenandoahLivenessData* ld,
79 const char* phase, ShenandoahVerifier::VerifyOptions options) :
80 _phase(phase),
81 _options(options),
82 _stack(stack),
83 _heap(ShenandoahHeap::heap()),
84 _map(map),
85 _ld(ld),
86 _interior_loc(nullptr),
87 _loc(nullptr),
88 _generation(nullptr) {
89 if (options._verify_marked == ShenandoahVerifier::_verify_marked_complete_except_references ||
90 options._verify_marked == ShenandoahVerifier::_verify_marked_complete_satb_empty ||
91 options._verify_marked == ShenandoahVerifier::_verify_marked_disable) {
92 set_ref_discoverer_internal(new ShenandoahIgnoreReferenceDiscoverer());
93 }
94
95 if (_heap->mode()->is_generational()) {
96 _generation = _heap->active_generation();
97 assert(_generation != nullptr, "Expected active generation in this mode");
98 }
99 }
100
101 private:
102 void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {
103 if (!test) {
104 ShenandoahAsserts::print_failure(level, obj, _interior_loc, _loc, _phase, label, __FILE__, __LINE__);
105 }
106 }
107
108 template <class T>
109 void do_oop_work(T* p) {
110 T o = RawAccess<>::oop_load(p);
111 if (!CompressedOops::is_null(o)) {
112 oop obj = CompressedOops::decode_not_null(o);
113 if (is_instance_ref_klass(obj->klass())) {
114 obj = ShenandoahForwarding::get_forwardee(obj);
115 }
116 // Single threaded verification can use faster non-atomic stack and bitmap
117 // methods.
118 //
119 // For performance reasons, only fully verify non-marked field values.
120 // We are here when the host object for *p is already marked.
121
122 // TODO: We should consider specializing this closure by generation ==/!= null,
123 // to avoid in_generation check on fast path here for non-generational mode.
124 if (in_generation(obj) && _map->par_mark(obj)) {
125 verify_oop_at(p, obj);
126 _stack->push(ShenandoahVerifierTask(obj));
127 }
128 }
129 }
130
131 bool in_generation(oop obj) {
132 if (_generation == nullptr) {
133 return true;
134 }
135
136 ShenandoahHeapRegion* region = _heap->heap_region_containing(obj);
137 return _generation->contains(region);
138 }
139
140 void verify_oop(oop obj) {
141 // Perform consistency checks with gradually decreasing safety level. This guarantees
142 // that failure report would not try to touch something that was not yet verified to be
143 // safe to process.
144
145 check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in(obj),
146 "oop must be in heap");
147 check(ShenandoahAsserts::_safe_unknown, obj, is_object_aligned(obj),
148 "oop must be aligned");
149
150 ShenandoahHeapRegion *obj_reg = _heap->heap_region_containing(obj);
151 Klass* obj_klass = obj->klass_or_null();
152
153 // Verify that obj is not in dead space:
154 {
155 // Do this before touching obj->size()
156 check(ShenandoahAsserts::_safe_unknown, obj, obj_klass != nullptr,
157 "Object klass pointer should not be null");
158 check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),
159 "Object klass pointer must go to metaspace");
160
161 HeapWord *obj_addr = cast_from_oop<HeapWord*>(obj);
162 check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),
163 "Object start should be within the region");
164
165 if (!obj_reg->is_humongous()) {
166 check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + obj->size()) <= obj_reg->top(),
167 "Object end should be within the region");
168 } else {
169 size_t humongous_start = obj_reg->index();
170 size_t humongous_end = humongous_start + (obj->size() >> ShenandoahHeapRegion::region_size_words_shift());
171 for (size_t idx = humongous_start + 1; idx < humongous_end; idx++) {
172 check(ShenandoahAsserts::_safe_unknown, obj, _heap->get_region(idx)->is_humongous_continuation(),
173 "Humongous object is in continuation that fits it");
174 }
175 }
176
177 // ------------ obj is safe at this point --------------
178
179 check(ShenandoahAsserts::_safe_oop, obj, obj_reg->is_active(),
180 "Object should be in active region");
181
182 switch (_options._verify_liveness) {
183 case ShenandoahVerifier::_verify_liveness_disable:
184 // skip
185 break;
186 case ShenandoahVerifier::_verify_liveness_complete:
187 Atomic::add(&_ld[obj_reg->index()], (uint) obj->size(), memory_order_relaxed);
188 // fallthrough for fast failure for un-live regions:
189 case ShenandoahVerifier::_verify_liveness_conservative:
190 check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live() ||
191 (obj_reg->is_old() && ShenandoahHeap::heap()->is_gc_generation_young()),
192 "Object must belong to region with live data");
193 break;
194 default:
195 assert(false, "Unhandled liveness verification");
196 }
197 }
198
199 oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
200
201 ShenandoahHeapRegion* fwd_reg = nullptr;
202
203 if (obj != fwd) {
204 check(ShenandoahAsserts::_safe_oop, obj, _heap->is_in(fwd),
205 "Forwardee must be in heap");
206 check(ShenandoahAsserts::_safe_oop, obj, !CompressedOops::is_null(fwd),
207 "Forwardee is set");
208 check(ShenandoahAsserts::_safe_oop, obj, is_object_aligned(fwd),
209 "Forwardee must be aligned");
210
211 // Do this before touching fwd->size()
212 Klass* fwd_klass = fwd->klass_or_null();
213 check(ShenandoahAsserts::_safe_oop, obj, fwd_klass != nullptr,
214 "Forwardee klass pointer should not be null");
215 check(ShenandoahAsserts::_safe_oop, obj, Metaspace::contains(fwd_klass),
216 "Forwardee klass pointer must go to metaspace");
217 check(ShenandoahAsserts::_safe_oop, obj, obj_klass == fwd_klass,
218 "Forwardee klass pointer must go to metaspace");
219
220 fwd_reg = _heap->heap_region_containing(fwd);
221
222 // Verify that forwardee is not in the dead space:
223 check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),
224 "Should have no humongous forwardees");
225
226 HeapWord *fwd_addr = cast_from_oop<HeapWord *>(fwd);
227 check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),
228 "Forwardee start should be within the region");
229 check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + fwd->size()) <= fwd_reg->top(),
230 "Forwardee end should be within the region");
231
232 oop fwd2 = ShenandoahForwarding::get_forwardee_raw_unchecked(fwd);
233 check(ShenandoahAsserts::_safe_oop, obj, (fwd == fwd2),
234 "Double forwarding");
235 } else {
236 fwd_reg = obj_reg;
237 }
238
239 // ------------ obj and fwd are safe at this point --------------
240 // We allow for marked or old here for two reasons:
241 // 1. If this is a young collect, old objects wouldn't be marked. We've
242 // recently change the verifier traversal to only follow young objects
243 // during a young collect so this _shouldn't_ be necessary.
244 // 2. At present, we do not clear dead objects from the remembered set.
245 // Everything in the remembered set is old (ipso facto), so allowing for
246 // 'marked_or_old' covers the case of stale objects in rset.
247 // TODO: Just use 'is_marked' here.
248 switch (_options._verify_marked) {
249 case ShenandoahVerifier::_verify_marked_disable:
250 // skip
251 break;
252 case ShenandoahVerifier::_verify_marked_incomplete:
253 check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked_or_old(obj),
254 "Must be marked in incomplete bitmap");
255 break;
256 case ShenandoahVerifier::_verify_marked_complete:
257 check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked_or_old(obj),
258 "Must be marked in complete bitmap");
259 break;
260 case ShenandoahVerifier::_verify_marked_complete_except_references:
261 case ShenandoahVerifier::_verify_marked_complete_satb_empty:
262 check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked_or_old(obj),
263 "Must be marked in complete bitmap, except j.l.r.Reference referents");
264 break;
265 default:
266 assert(false, "Unhandled mark verification");
267 }
268
269 switch (_options._verify_forwarded) {
270 case ShenandoahVerifier::_verify_forwarded_disable:
271 // skip
272 break;
273 case ShenandoahVerifier::_verify_forwarded_none: {
274 check(ShenandoahAsserts::_safe_all, obj, (obj == fwd),
275 "Should not be forwarded");
276 break;
277 }
278 case ShenandoahVerifier::_verify_forwarded_allow: {
279 if (obj != fwd) {
280 check(ShenandoahAsserts::_safe_all, obj, obj_reg != fwd_reg,
281 "Forwardee should be in another region");
282 }
283 break;
284 }
285 default:
286 assert(false, "Unhandled forwarding verification");
287 }
288
289 switch (_options._verify_cset) {
290 case ShenandoahVerifier::_verify_cset_disable:
291 // skip
292 break;
293 case ShenandoahVerifier::_verify_cset_none:
294 check(ShenandoahAsserts::_safe_all, obj, !_heap->in_collection_set(obj),
295 "Should not have references to collection set");
296 break;
297 case ShenandoahVerifier::_verify_cset_forwarded:
298 if (_heap->in_collection_set(obj)) {
299 check(ShenandoahAsserts::_safe_all, obj, (obj != fwd),
300 "Object in collection set, should have forwardee");
301 }
302 break;
303 default:
304 assert(false, "Unhandled cset verification");
305 }
306
307 }
308
309 public:
310 /**
311 * Verify object with known interior reference.
312 * @param p interior reference where the object is referenced from; can be off-heap
313 * @param obj verified object
314 */
315 template <class T>
316 void verify_oop_at(T* p, oop obj) {
317 _interior_loc = p;
318 verify_oop(obj);
319 _interior_loc = nullptr;
320 }
321
322 /**
323 * Verify object without known interior reference.
324 * Useful when picking up the object at known offset in heap,
325 * but without knowing what objects reference it.
326 * @param obj verified object
327 */
328 void verify_oop_standalone(oop obj) {
329 _interior_loc = nullptr;
330 verify_oop(obj);
331 _interior_loc = nullptr;
332 }
333
334 /**
335 * Verify oop fields from this object.
336 * @param obj host object for verified fields
337 */
338 void verify_oops_from(oop obj) {
339 _loc = obj;
340 obj->oop_iterate(this);
341 _loc = nullptr;
342 }
343
344 virtual void do_oop(oop* p) { do_oop_work(p); }
345 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
346 };
347
348 // This closure computes the amounts of used, committed, and garbage memory and the number of regions contained within
349 // a subset (e.g. the young generation or old generation) of the total heap.
350 class ShenandoahCalculateRegionStatsClosure : public ShenandoahHeapRegionClosure {
351 private:
352 size_t _used, _committed, _garbage, _regions, _humongous_waste;
353 public:
354 ShenandoahCalculateRegionStatsClosure() : _used(0), _committed(0), _garbage(0), _regions(0), _humongous_waste(0) {};
355
356 void heap_region_do(ShenandoahHeapRegion* r) {
357 _used += r->used();
358 _garbage += r->garbage();
359 _committed += r->is_committed() ? ShenandoahHeapRegion::region_size_bytes() : 0;
360 if (r->is_humongous()) {
361 _humongous_waste += r->free();
362 }
363 _regions++;
364 log_debug(gc)("ShenandoahCalculateRegionStatsClosure: adding " SIZE_FORMAT " for %s Region " SIZE_FORMAT ", yielding: " SIZE_FORMAT,
365 r->used(), (r->is_humongous() ? "humongous" : "regular"), r->index(), _used);
366 }
367
368 size_t used() { return _used; }
369 size_t committed() { return _committed; }
370 size_t garbage() { return _garbage; }
371 size_t regions() { return _regions; }
372 size_t waste() { return _humongous_waste; }
373
374 // span is the total memory affiliated with these stats (some of which is in use and other is available)
375 size_t span() { return _regions * ShenandoahHeapRegion::region_size_bytes(); }
376 };
377
378 class ShenandoahGenerationStatsClosure : public ShenandoahHeapRegionClosure {
379 public:
380 ShenandoahCalculateRegionStatsClosure old;
381 ShenandoahCalculateRegionStatsClosure young;
382 ShenandoahCalculateRegionStatsClosure global;
383
384 void heap_region_do(ShenandoahHeapRegion* r) override {
385 switch (r->affiliation()) {
386 case FREE:
387 return;
388 case YOUNG_GENERATION:
389 young.heap_region_do(r);
390 global.heap_region_do(r);
391 break;
392 case OLD_GENERATION:
393 old.heap_region_do(r);
394 global.heap_region_do(r);
395 break;
396 default:
397 ShouldNotReachHere();
398 }
399 }
400
401 static void log_usage(ShenandoahGeneration* generation, ShenandoahCalculateRegionStatsClosure& stats) {
402 log_debug(gc)("Safepoint verification: %s verified usage: " SIZE_FORMAT "%s, recorded usage: " SIZE_FORMAT "%s",
403 generation->name(),
404 byte_size_in_proper_unit(generation->used()), proper_unit_for_byte_size(generation->used()),
405 byte_size_in_proper_unit(stats.used()), proper_unit_for_byte_size(stats.used()));
406 }
407
408 static void validate_usage(const bool adjust_for_padding,
409 const char* label, ShenandoahGeneration* generation, ShenandoahCalculateRegionStatsClosure& stats) {
410 ShenandoahHeap* heap = ShenandoahHeap::heap();
411 size_t generation_used = generation->used();
412 size_t generation_used_regions = generation->used_regions();
413 if (adjust_for_padding && (generation->is_young() || generation->is_global())) {
414 size_t pad = ShenandoahHeap::heap()->get_pad_for_promote_in_place();
415 generation_used += pad;
416 }
417
418 guarantee(stats.used() == generation_used,
419 "%s: generation (%s) used size must be consistent: generation-used: " SIZE_FORMAT "%s, regions-used: " SIZE_FORMAT "%s",
420 label, generation->name(),
421 byte_size_in_proper_unit(generation_used), proper_unit_for_byte_size(generation_used),
422 byte_size_in_proper_unit(stats.used()), proper_unit_for_byte_size(stats.used()));
423
424 guarantee(stats.regions() == generation_used_regions,
425 "%s: generation (%s) used regions (" SIZE_FORMAT ") must equal regions that are in use (" SIZE_FORMAT ")",
426 label, generation->name(), generation->used_regions(), stats.regions());
427
428 size_t generation_capacity = generation->max_capacity();
429 size_t humongous_regions_promoted = 0;
430 guarantee(stats.span() <= generation_capacity,
431 "%s: generation (%s) size spanned by regions (" SIZE_FORMAT ") must not exceed current capacity (" SIZE_FORMAT "%s)",
432 label, generation->name(), stats.regions(),
433 byte_size_in_proper_unit(generation_capacity), proper_unit_for_byte_size(generation_capacity));
434
435 size_t humongous_waste = generation->get_humongous_waste();
436 guarantee(stats.waste() == humongous_waste,
437 "%s: generation (%s) humongous waste must be consistent: generation: " SIZE_FORMAT "%s, regions: " SIZE_FORMAT "%s",
438 label, generation->name(),
439 byte_size_in_proper_unit(humongous_waste), proper_unit_for_byte_size(humongous_waste),
440 byte_size_in_proper_unit(stats.waste()), proper_unit_for_byte_size(stats.waste()));
441 }
442 };
443
444 class ShenandoahVerifyHeapRegionClosure : public ShenandoahHeapRegionClosure {
445 private:
446 ShenandoahHeap* _heap;
447 const char* _phase;
448 ShenandoahVerifier::VerifyRegions _regions;
449 public:
450 ShenandoahVerifyHeapRegionClosure(const char* phase, ShenandoahVerifier::VerifyRegions regions) :
451 _heap(ShenandoahHeap::heap()),
452 _phase(phase),
453 _regions(regions) {};
454
455 void print_failure(ShenandoahHeapRegion* r, const char* label) {
456 ResourceMark rm;
457
458 ShenandoahMessageBuffer msg("Shenandoah verification failed; %s: %s\n\n", _phase, label);
459
460 stringStream ss;
461 r->print_on(&ss);
462 msg.append("%s", ss.as_string());
463
464 report_vm_error(__FILE__, __LINE__, msg.buffer());
465 }
466
467 void verify(ShenandoahHeapRegion* r, bool test, const char* msg) {
468 if (!test) {
469 print_failure(r, msg);
470 }
471 }
472
473 void heap_region_do(ShenandoahHeapRegion* r) {
474 switch (_regions) {
475 case ShenandoahVerifier::_verify_regions_disable:
476 break;
477 case ShenandoahVerifier::_verify_regions_notrash:
478 verify(r, !r->is_trash(),
479 "Should not have trash regions");
480 break;
481 case ShenandoahVerifier::_verify_regions_nocset:
482 verify(r, !r->is_cset(),
483 "Should not have cset regions");
484 break;
485 case ShenandoahVerifier::_verify_regions_notrash_nocset:
486 verify(r, !r->is_trash(),
487 "Should not have trash regions");
488 verify(r, !r->is_cset(),
489 "Should not have cset regions");
490 break;
491 default:
492 ShouldNotReachHere();
493 }
494
495 verify(r, r->capacity() == ShenandoahHeapRegion::region_size_bytes(),
496 "Capacity should match region size");
497
498 verify(r, r->bottom() <= r->top(),
499 "Region top should not be less than bottom");
500
501 verify(r, r->bottom() <= _heap->marking_context()->top_at_mark_start(r),
502 "Region TAMS should not be less than bottom");
503
504 verify(r, _heap->marking_context()->top_at_mark_start(r) <= r->top(),
505 "Complete TAMS should not be larger than top");
506
507 verify(r, r->get_live_data_bytes() <= r->capacity(),
508 "Live data cannot be larger than capacity");
509
510 verify(r, r->garbage() <= r->capacity(),
511 "Garbage cannot be larger than capacity");
512
513 verify(r, r->used() <= r->capacity(),
514 "Used cannot be larger than capacity");
515
516 verify(r, r->get_shared_allocs() <= r->capacity(),
517 "Shared alloc count should not be larger than capacity");
518
519 verify(r, r->get_tlab_allocs() <= r->capacity(),
520 "TLAB alloc count should not be larger than capacity");
521
522 verify(r, r->get_gclab_allocs() <= r->capacity(),
523 "GCLAB alloc count should not be larger than capacity");
524
525 verify(r, r->get_plab_allocs() <= r->capacity(),
526 "PLAB alloc count should not be larger than capacity");
527
528 verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() + r->get_plab_allocs() == r->used(),
529 "Accurate accounting: shared + TLAB + GCLAB + PLAB = used");
530
531 verify(r, !r->is_empty() || !r->has_live(),
532 "Empty regions should not have live data");
533
534 verify(r, r->is_cset() == _heap->collection_set()->is_in(r),
535 "Transitional: region flags and collection set agree");
536 }
537 };
538
539 class ShenandoahVerifierReachableTask : public WorkerTask {
540 private:
541 const char* _label;
542 ShenandoahVerifier::VerifyOptions _options;
543 ShenandoahHeap* _heap;
544 ShenandoahLivenessData* _ld;
545 MarkBitMap* _bitmap;
546 volatile size_t _processed;
547
548 public:
549 ShenandoahVerifierReachableTask(MarkBitMap* bitmap,
550 ShenandoahLivenessData* ld,
551 const char* label,
552 ShenandoahVerifier::VerifyOptions options) :
553 WorkerTask("Shenandoah Verifier Reachable Objects"),
554 _label(label),
555 _options(options),
556 _heap(ShenandoahHeap::heap()),
557 _ld(ld),
558 _bitmap(bitmap),
559 _processed(0) {};
560
561 size_t processed() {
562 return _processed;
563 }
564
565 virtual void work(uint worker_id) {
566 ResourceMark rm;
567 ShenandoahVerifierStack stack;
568
569 // On level 2, we need to only check the roots once.
570 // On level 3, we want to check the roots, and seed the local stack.
571 // It is a lesser evil to accept multiple root scans at level 3, because
572 // extended parallelism would buy us out.
573 if (((ShenandoahVerifyLevel == 2) && (worker_id == 0))
574 || (ShenandoahVerifyLevel >= 3)) {
575 ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
576 ShenandoahMessageBuffer("%s, Roots", _label),
577 _options);
578 if (_heap->unload_classes()) {
579 ShenandoahRootVerifier::strong_roots_do(&cl);
580 } else {
581 ShenandoahRootVerifier::roots_do(&cl);
582 }
583 }
584
585 size_t processed = 0;
586
587 if (ShenandoahVerifyLevel >= 3) {
588 ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
589 ShenandoahMessageBuffer("%s, Reachable", _label),
590 _options);
591 while (!stack.is_empty()) {
592 processed++;
593 ShenandoahVerifierTask task = stack.pop();
594 cl.verify_oops_from(task.obj());
595 }
596 }
597
598 Atomic::add(&_processed, processed, memory_order_relaxed);
599 }
600 };
601
602 class ShenandoahVerifyNoIncompleteSatbBuffers : public ThreadClosure {
603 public:
604 virtual void do_thread(Thread* thread) {
605 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
606 if (!queue.is_empty()) {
607 fatal("All SATB buffers should have been flushed during mark");
608 }
609 }
610 };
611
612 class ShenandoahVerifierMarkedRegionTask : public WorkerTask {
613 private:
614 const char* _label;
615 ShenandoahVerifier::VerifyOptions _options;
616 ShenandoahHeap *_heap;
617 MarkBitMap* _bitmap;
618 ShenandoahLivenessData* _ld;
619 volatile size_t _claimed;
620 volatile size_t _processed;
621 ShenandoahGeneration* _generation;
622
623 public:
624 ShenandoahVerifierMarkedRegionTask(MarkBitMap* bitmap,
625 ShenandoahLivenessData* ld,
626 const char* label,
627 ShenandoahVerifier::VerifyOptions options) :
628 WorkerTask("Shenandoah Verifier Marked Objects"),
629 _label(label),
630 _options(options),
631 _heap(ShenandoahHeap::heap()),
632 _bitmap(bitmap),
633 _ld(ld),
634 _claimed(0),
635 _processed(0),
636 _generation(nullptr) {
637 if (_options._verify_marked == ShenandoahVerifier::_verify_marked_complete_satb_empty) {
638 Threads::change_thread_claim_token();
639 }
640
641 if (_heap->mode()->is_generational()) {
642 _generation = _heap->active_generation();
643 assert(_generation != nullptr, "Expected active generation in this mode.");
644 }
645 };
646
647 size_t processed() {
648 return Atomic::load(&_processed);
649 }
650
651 virtual void work(uint worker_id) {
652 if (_options._verify_marked == ShenandoahVerifier::_verify_marked_complete_satb_empty) {
653 ShenandoahVerifyNoIncompleteSatbBuffers verify_satb;
654 Threads::possibly_parallel_threads_do(true, &verify_satb);
655 }
656
657 ShenandoahVerifierStack stack;
658 ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
659 ShenandoahMessageBuffer("%s, Marked", _label),
660 _options);
661
662 while (true) {
663 size_t v = Atomic::fetch_then_add(&_claimed, 1u, memory_order_relaxed);
664 if (v < _heap->num_regions()) {
665 ShenandoahHeapRegion* r = _heap->get_region(v);
666 if (!in_generation(r)) {
667 continue;
668 }
669
670 if (!r->is_humongous() && !r->is_trash()) {
671 work_regular(r, stack, cl);
672 } else if (r->is_humongous_start()) {
673 work_humongous(r, stack, cl);
674 }
675 } else {
676 break;
677 }
678 }
679 }
680
681 bool in_generation(ShenandoahHeapRegion* r) {
682 return _generation == nullptr || _generation->contains(r);
683 }
684
685 virtual void work_humongous(ShenandoahHeapRegion *r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {
686 size_t processed = 0;
687 HeapWord* obj = r->bottom();
688 if (_heap->complete_marking_context()->is_marked(cast_to_oop(obj))) {
689 verify_and_follow(obj, stack, cl, &processed);
690 }
691 Atomic::add(&_processed, processed, memory_order_relaxed);
692 }
693
694 virtual void work_regular(ShenandoahHeapRegion *r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {
695 size_t processed = 0;
696 ShenandoahMarkingContext* ctx = _heap->complete_marking_context();
697 HeapWord* tams = ctx->top_at_mark_start(r);
698
699 // Bitmaps, before TAMS
700 if (tams > r->bottom()) {
701 HeapWord* start = r->bottom();
702 HeapWord* addr = ctx->get_next_marked_addr(start, tams);
703
704 while (addr < tams) {
705 verify_and_follow(addr, stack, cl, &processed);
706 addr += 1;
707 if (addr < tams) {
708 addr = ctx->get_next_marked_addr(addr, tams);
709 }
710 }
711 }
712
713 // Size-based, after TAMS
714 {
715 HeapWord* limit = r->top();
716 HeapWord* addr = tams;
717
718 while (addr < limit) {
719 verify_and_follow(addr, stack, cl, &processed);
720 addr += cast_to_oop(addr)->size();
721 }
722 }
723
724 Atomic::add(&_processed, processed, memory_order_relaxed);
725 }
726
727 void verify_and_follow(HeapWord *addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t *processed) {
728 if (!_bitmap->par_mark(addr)) return;
729
730 // Verify the object itself:
731 oop obj = cast_to_oop(addr);
732 cl.verify_oop_standalone(obj);
733
734 // Verify everything reachable from that object too, hopefully realizing
735 // everything was already marked, and never touching further:
736 if (!is_instance_ref_klass(obj->klass())) {
737 cl.verify_oops_from(obj);
738 (*processed)++;
739 }
740 while (!stack.is_empty()) {
741 ShenandoahVerifierTask task = stack.pop();
742 cl.verify_oops_from(task.obj());
743 (*processed)++;
744 }
745 }
746 };
747
748 class VerifyThreadGCState : public ThreadClosure {
749 private:
750 const char* const _label;
751 char const _expected;
752
753 public:
754 VerifyThreadGCState(const char* label, char expected) : _label(label), _expected(expected) {}
755 void do_thread(Thread* t) {
756 char actual = ShenandoahThreadLocalData::gc_state(t);
757 if (!verify_gc_state(actual, _expected)) {
758 fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);
759 }
760 }
761
762 static bool verify_gc_state(char actual, char expected) {
763 // Old generation marking is allowed in all states.
764 if (ShenandoahHeap::heap()->mode()->is_generational()) {
765 return ((actual & ~(ShenandoahHeap::OLD_MARKING | ShenandoahHeap::MARKING)) == expected);
766 } else {
767 assert((actual & ShenandoahHeap::OLD_MARKING) == 0, "Should not mark old in non-generational mode");
768 return (actual == expected);
769 }
770 }
771 };
772
773 void ShenandoahVerifier::verify_at_safepoint(const char* label,
774 VerifyRememberedSet remembered,
775 VerifyForwarded forwarded, VerifyMarked marked,
776 VerifyCollectionSet cset,
777 VerifyLiveness liveness, VerifyRegions regions,
778 VerifySize sizeness,
779 VerifyGCState gcstate) {
780 guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");
781 guarantee(ShenandoahVerify, "only when enabled, and bitmap is initialized in ShenandoahHeap::initialize");
782
783 // Avoid side-effect of changing workers' active thread count, but bypass concurrent/parallel protocol check
784 ShenandoahPushWorkerScope verify_worker_scope(_heap->workers(), _heap->max_workers(), false /*bypass check*/);
785
786 log_info(gc,start)("Verify %s, Level " INTX_FORMAT, label, ShenandoahVerifyLevel);
787
788 // GC state checks
789 {
790 char expected = -1;
791 bool enabled;
792 switch (gcstate) {
793 case _verify_gcstate_disable:
794 enabled = false;
795 break;
796 case _verify_gcstate_forwarded:
797 enabled = true;
798 expected = ShenandoahHeap::HAS_FORWARDED;
799 break;
800 case _verify_gcstate_evacuation:
801 enabled = true;
802 expected = ShenandoahHeap::EVACUATION;
803 if (!_heap->is_stw_gc_in_progress()) {
804 // Only concurrent GC sets this.
805 expected |= ShenandoahHeap::WEAK_ROOTS;
806 }
807 break;
808 case _verify_gcstate_updating:
809 enabled = true;
810 expected = ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::UPDATEREFS;
811 break;
812 case _verify_gcstate_stable:
813 enabled = true;
814 expected = ShenandoahHeap::STABLE;
815 break;
816 case _verify_gcstate_stable_weakroots:
817 enabled = true;
818 expected = ShenandoahHeap::STABLE;
819 if (!_heap->is_stw_gc_in_progress()) {
820 // Only concurrent GC sets this.
821 expected |= ShenandoahHeap::WEAK_ROOTS;
822 }
823 break;
824 default:
825 enabled = false;
826 assert(false, "Unhandled gc-state verification");
827 }
828
829 if (enabled) {
830 char actual = _heap->gc_state();
831
832 bool is_marking = (actual & ShenandoahHeap::MARKING)? 1: 0;
833 bool is_marking_young_or_old = (actual & (ShenandoahHeap::YOUNG_MARKING | ShenandoahHeap::OLD_MARKING))? 1: 0;
834 assert(is_marking == is_marking_young_or_old, "MARKING iff (YOUNG_MARKING or OLD_MARKING), gc_state is: %x", actual);
835
836 // Old generation marking is allowed in all states.
837 if (!VerifyThreadGCState::verify_gc_state(actual, expected)) {
838 fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);
839 }
840
841 VerifyThreadGCState vtgcs(label, expected);
842 Threads::java_threads_do(&vtgcs);
843 }
844 }
845
846 // Deactivate barriers temporarily: Verifier wants plain heap accesses
847 ShenandoahGCStateResetter resetter;
848
849 // Heap size checks
850 {
851 ShenandoahHeapLocker lock(_heap->lock());
852
853 ShenandoahCalculateRegionStatsClosure cl;
854 _heap->heap_region_iterate(&cl);
855 size_t heap_used;
856 if (_heap->mode()->is_generational() && (sizeness == _verify_size_adjusted_for_padding)) {
857 // Prior to evacuation, regular regions that are to be evacuated in place are padded to prevent further allocations
858 heap_used = _heap->used() + _heap->get_pad_for_promote_in_place();
859 } else if (sizeness != _verify_size_disable) {
860 heap_used = _heap->used();
861 }
862 if (sizeness != _verify_size_disable) {
863 guarantee(cl.used() == heap_used,
864 "%s: heap used size must be consistent: heap-used = " SIZE_FORMAT "%s, regions-used = " SIZE_FORMAT "%s",
865 label,
866 byte_size_in_proper_unit(heap_used), proper_unit_for_byte_size(heap_used),
867 byte_size_in_proper_unit(cl.used()), proper_unit_for_byte_size(cl.used()));
868 }
869 size_t heap_committed = _heap->committed();
870 guarantee(cl.committed() == heap_committed,
871 "%s: heap committed size must be consistent: heap-committed = " SIZE_FORMAT "%s, regions-committed = " SIZE_FORMAT "%s",
872 label,
873 byte_size_in_proper_unit(heap_committed), proper_unit_for_byte_size(heap_committed),
874 byte_size_in_proper_unit(cl.committed()), proper_unit_for_byte_size(cl.committed()));
875 }
876
877 log_debug(gc)("Safepoint verification finished heap usage verification");
878
879 ShenandoahGeneration* generation;
880 if (_heap->mode()->is_generational()) {
881 generation = _heap->active_generation();
882 guarantee(generation != nullptr, "Need to know which generation to verify.");
883 } else {
884 generation = nullptr;
885 }
886
887 if (generation != nullptr) {
888 ShenandoahHeapLocker lock(_heap->lock());
889
890 switch (remembered) {
891 case _verify_remembered_disable:
892 break;
893 case _verify_remembered_before_marking:
894 log_debug(gc)("Safepoint verification of remembered set at mark");
895 verify_rem_set_before_mark();
896 break;
897 case _verify_remembered_before_updating_references:
898 log_debug(gc)("Safepoint verification of remembered set at update ref");
899 verify_rem_set_before_update_ref();
900 break;
901 case _verify_remembered_after_full_gc:
902 log_debug(gc)("Safepoint verification of remembered set after full gc");
903 verify_rem_set_after_full_gc();
904 break;
905 default:
906 fatal("Unhandled remembered set verification mode");
907 }
908
909 ShenandoahGenerationStatsClosure cl;
910 _heap->heap_region_iterate(&cl);
911
912 if (LogTarget(Debug, gc)::is_enabled()) {
913 ShenandoahGenerationStatsClosure::log_usage(_heap->old_generation(), cl.old);
914 ShenandoahGenerationStatsClosure::log_usage(_heap->young_generation(), cl.young);
915 ShenandoahGenerationStatsClosure::log_usage(_heap->global_generation(), cl.global);
916 }
917 if (sizeness == _verify_size_adjusted_for_padding) {
918 ShenandoahGenerationStatsClosure::validate_usage(false, label, _heap->old_generation(), cl.old);
919 ShenandoahGenerationStatsClosure::validate_usage(true, label, _heap->young_generation(), cl.young);
920 ShenandoahGenerationStatsClosure::validate_usage(true, label, _heap->global_generation(), cl.global);
921 } else if (sizeness == _verify_size_exact) {
922 ShenandoahGenerationStatsClosure::validate_usage(false, label, _heap->old_generation(), cl.old);
923 ShenandoahGenerationStatsClosure::validate_usage(false, label, _heap->young_generation(), cl.young);
924 ShenandoahGenerationStatsClosure::validate_usage(false, label, _heap->global_generation(), cl.global);
925 }
926 // else: sizeness must equal _verify_size_disable
927 }
928
929 log_debug(gc)("Safepoint verification finished remembered set verification");
930
931 // Internal heap region checks
932 if (ShenandoahVerifyLevel >= 1) {
933 ShenandoahVerifyHeapRegionClosure cl(label, regions);
934 if (generation != nullptr) {
935 generation->heap_region_iterate(&cl);
936 } else {
937 _heap->heap_region_iterate(&cl);
938 }
939 }
940
941 log_debug(gc)("Safepoint verification finished heap region closure verification");
942
943 OrderAccess::fence();
944
945 if (UseTLAB) {
946 _heap->labs_make_parsable();
947 }
948
949 // Allocate temporary bitmap for storing marking wavefront:
950 _verification_bit_map->clear();
951
952 // Allocate temporary array for storing liveness data
953 ShenandoahLivenessData* ld = NEW_C_HEAP_ARRAY(ShenandoahLivenessData, _heap->num_regions(), mtGC);
954 Copy::fill_to_bytes((void*)ld, _heap->num_regions()*sizeof(ShenandoahLivenessData), 0);
955
956 const VerifyOptions& options = ShenandoahVerifier::VerifyOptions(forwarded, marked, cset, liveness, regions, gcstate);
957
958 // Steps 1-2. Scan root set to get initial reachable set. Finish walking the reachable heap.
959 // This verifies what application can see, since it only cares about reachable objects.
960 size_t count_reachable = 0;
961 if (ShenandoahVerifyLevel >= 2) {
962 ShenandoahVerifierReachableTask task(_verification_bit_map, ld, label, options);
963 _heap->workers()->run_task(&task);
964 count_reachable = task.processed();
965 }
966
967 log_debug(gc)("Safepoint verification finished getting initial reachable set");
968
969 // Step 3. Walk marked objects. Marked objects might be unreachable. This verifies what collector,
970 // not the application, can see during the region scans. There is no reason to process the objects
971 // that were already verified, e.g. those marked in verification bitmap. There is interaction with TAMS:
972 // before TAMS, we verify the bitmaps, if available; after TAMS, we walk until the top(). It mimics
973 // what marked_object_iterate is doing, without calling into that optimized (and possibly incorrect)
974 // version
975
976 size_t count_marked = 0;
977 if (ShenandoahVerifyLevel >= 4 &&
978 (marked == _verify_marked_complete ||
979 marked == _verify_marked_complete_except_references ||
980 marked == _verify_marked_complete_satb_empty)) {
981 guarantee(_heap->marking_context()->is_complete(), "Marking context should be complete");
982 ShenandoahVerifierMarkedRegionTask task(_verification_bit_map, ld, label, options);
983 _heap->workers()->run_task(&task);
984 count_marked = task.processed();
985 } else {
986 guarantee(ShenandoahVerifyLevel < 4 || marked == _verify_marked_incomplete || marked == _verify_marked_disable, "Should be");
987 }
988
989 log_debug(gc)("Safepoint verification finished walking marked objects");
990
991 // Step 4. Verify accumulated liveness data, if needed. Only reliable if verification level includes
992 // marked objects.
993
994 if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete && liveness == _verify_liveness_complete) {
995 for (size_t i = 0; i < _heap->num_regions(); i++) {
996 ShenandoahHeapRegion* r = _heap->get_region(i);
997 if (generation != nullptr && !generation->contains(r)) {
998 continue;
999 }
1000
1001 juint verf_live = 0;
1002 if (r->is_humongous()) {
1003 // For humongous objects, test if start region is marked live, and if so,
1004 // all humongous regions in that chain have live data equal to their "used".
1005 juint start_live = Atomic::load(&ld[r->humongous_start_region()->index()]);
1006 if (start_live > 0) {
1007 verf_live = (juint)(r->used() / HeapWordSize);
1008 }
1009 } else {
1010 verf_live = Atomic::load(&ld[r->index()]);
1011 }
1012
1013 size_t reg_live = r->get_live_data_words();
1014 if (reg_live != verf_live) {
1015 stringStream ss;
1016 r->print_on(&ss);
1017 fatal("%s: Live data should match: region-live = " SIZE_FORMAT ", verifier-live = " UINT32_FORMAT "\n%s",
1018 label, reg_live, verf_live, ss.freeze());
1019 }
1020 }
1021 }
1022
1023 log_debug(gc)("Safepoint verification finished accumulation of liveness data");
1024
1025
1026 log_info(gc)("Verify %s, Level " INTX_FORMAT " (" SIZE_FORMAT " reachable, " SIZE_FORMAT " marked)",
1027 label, ShenandoahVerifyLevel, count_reachable, count_marked);
1028
1029 FREE_C_HEAP_ARRAY(ShenandoahLivenessData, ld);
1030 }
1031
1032 void ShenandoahVerifier::verify_generic(VerifyOption vo) {
1033 verify_at_safepoint(
1034 "Generic Verification",
1035 _verify_remembered_disable, // do not verify remembered set
1036 _verify_forwarded_allow, // conservatively allow forwarded
1037 _verify_marked_disable, // do not verify marked: lots ot time wasted checking dead allocations
1038 _verify_cset_disable, // cset may be inconsistent
1039 _verify_liveness_disable, // no reliable liveness data
1040 _verify_regions_disable, // no reliable region data
1041 _verify_size_exact, // expect generation and heap sizes to match exactly
1042 _verify_gcstate_disable // no data about gcstate
1043 );
1044 }
1045
1046 void ShenandoahVerifier::verify_before_concmark() {
1047 verify_at_safepoint(
1048 "Before Mark",
1049 _verify_remembered_before_marking,
1050 // verify read-only remembered set from bottom() to top()
1051 _verify_forwarded_none, // UR should have fixed up
1052 _verify_marked_disable, // do not verify marked: lots ot time wasted checking dead allocations
1053 _verify_cset_none, // UR should have fixed this
1054 _verify_liveness_disable, // no reliable liveness data
1055 _verify_regions_notrash, // no trash regions
1056 _verify_size_exact, // expect generation and heap sizes to match exactly
1057 _verify_gcstate_stable // there are no forwarded objects
1058 );
1059 }
1060
1061 void ShenandoahVerifier::verify_after_concmark() {
1062 verify_at_safepoint(
1063 "After Mark",
1064 _verify_remembered_disable, // do not verify remembered set
1065 _verify_forwarded_none, // no forwarded references
1066 _verify_marked_complete_satb_empty,
1067 // bitmaps as precise as we can get, except dangling j.l.r.Refs
1068 _verify_cset_none, // no references to cset anymore
1069 _verify_liveness_complete, // liveness data must be complete here
1070 _verify_regions_disable, // trash regions not yet recycled
1071 _verify_size_exact, // expect generation and heap sizes to match exactly
1072 _verify_gcstate_stable_weakroots // heap is still stable, weakroots are in progress
1073 );
1074 }
1075
1076 void ShenandoahVerifier::verify_before_evacuation() {
1077 verify_at_safepoint(
1078 "Before Evacuation",
1079 _verify_remembered_disable, // do not verify remembered set
1080 _verify_forwarded_none, // no forwarded references
1081 _verify_marked_complete_except_references, // walk over marked objects too
1082 _verify_cset_disable, // non-forwarded references to cset expected
1083 _verify_liveness_complete, // liveness data must be complete here
1084 _verify_regions_disable, // trash regions not yet recycled
1085 _verify_size_adjusted_for_padding, // expect generation and heap sizes to match after adjustments
1086 // for promote in place padding
1087 _verify_gcstate_stable_weakroots // heap is still stable, weakroots are in progress
1088 );
1089 }
1090
1091 void ShenandoahVerifier::verify_during_evacuation() {
1092 verify_at_safepoint(
1093 "During Evacuation",
1094 _verify_remembered_disable, // do not verify remembered set
1095 _verify_forwarded_allow, // some forwarded references are allowed
1096 _verify_marked_disable, // walk only roots
1097 _verify_cset_disable, // some cset references are not forwarded yet
1098 _verify_liveness_disable, // liveness data might be already stale after pre-evacs
1099 _verify_regions_disable, // trash regions not yet recycled
1100 _verify_size_disable, // we don't know how much of promote-in-place work has been completed
1101 _verify_gcstate_evacuation // evacuation is in progress
1102 );
1103 }
1104
1105 void ShenandoahVerifier::verify_after_evacuation() {
1106 verify_at_safepoint(
1107 "After Evacuation",
1108 _verify_remembered_disable, // do not verify remembered set
1109 _verify_forwarded_allow, // objects are still forwarded
1110 _verify_marked_complete, // bitmaps might be stale, but alloc-after-mark should be well
1111 _verify_cset_forwarded, // all cset refs are fully forwarded
1112 _verify_liveness_disable, // no reliable liveness data anymore
1113 _verify_regions_notrash, // trash regions have been recycled already
1114 _verify_size_exact, // expect generation and heap sizes to match exactly
1115 _verify_gcstate_forwarded // evacuation produced some forwarded objects
1116 );
1117 }
1118
1119 void ShenandoahVerifier::verify_before_updaterefs() {
1120 verify_at_safepoint(
1121 "Before Updating References",
1122 _verify_remembered_before_updating_references, // verify read-write remembered set
1123 _verify_forwarded_allow, // forwarded references allowed
1124 _verify_marked_complete, // bitmaps might be stale, but alloc-after-mark should be well
1125 _verify_cset_forwarded, // all cset refs are fully forwarded
1126 _verify_liveness_disable, // no reliable liveness data anymore
1127 _verify_regions_notrash, // trash regions have been recycled already
1128 _verify_size_exact, // expect generation and heap sizes to match exactly
1129 _verify_gcstate_updating // evacuation should have produced some forwarded objects
1130 );
1131 }
1132
1133 // We have not yet cleanup (reclaimed) the collection set
1134 void ShenandoahVerifier::verify_after_updaterefs() {
1135 verify_at_safepoint(
1136 "After Updating References",
1137 _verify_remembered_disable, // do not verify remembered set
1138 _verify_forwarded_none, // no forwarded references
1139 _verify_marked_complete, // bitmaps might be stale, but alloc-after-mark should be well
1140 _verify_cset_none, // no cset references, all updated
1141 _verify_liveness_disable, // no reliable liveness data anymore
1142 _verify_regions_nocset, // no cset regions, trash regions have appeared
1143 _verify_size_exact, // expect generation and heap sizes to match exactly
1144 _verify_gcstate_stable // update refs had cleaned up forwarded objects
1145 );
1146 }
1147
1148 void ShenandoahVerifier::verify_after_degenerated() {
1149 verify_at_safepoint(
1150 "After Degenerated GC",
1151 _verify_remembered_disable, // do not verify remembered set
1152 _verify_forwarded_none, // all objects are non-forwarded
1153 _verify_marked_complete, // all objects are marked in complete bitmap
1154 _verify_cset_none, // no cset references
1155 _verify_liveness_disable, // no reliable liveness data anymore
1156 _verify_regions_notrash_nocset, // no trash, no cset
1157 _verify_size_exact, // expect generation and heap sizes to match exactly
1158 _verify_gcstate_stable // degenerated refs had cleaned up forwarded objects
1159 );
1160 }
1161
1162 void ShenandoahVerifier::verify_before_fullgc() {
1163 verify_at_safepoint(
1164 "Before Full GC",
1165 _verify_remembered_disable, // do not verify remembered set
1166 _verify_forwarded_allow, // can have forwarded objects
1167 _verify_marked_disable, // do not verify marked: lots ot time wasted checking dead allocations
1168 _verify_cset_disable, // cset might be foobared
1169 _verify_liveness_disable, // no reliable liveness data anymore
1170 _verify_regions_disable, // no reliable region data here
1171 _verify_size_disable, // if we degenerate during evacuation, usage not valid: padding and deferred accounting
1172 _verify_gcstate_disable // no reliable gcstate data
1173 );
1174 }
1175
1176 void ShenandoahVerifier::verify_after_fullgc() {
1177 verify_at_safepoint(
1178 "After Full GC",
1179 _verify_remembered_after_full_gc, // verify read-write remembered set
1180 _verify_forwarded_none, // all objects are non-forwarded
1181 _verify_marked_complete, // all objects are marked in complete bitmap
1182 _verify_cset_none, // no cset references
1183 _verify_liveness_disable, // no reliable liveness data anymore
1184 _verify_regions_notrash_nocset, // no trash, no cset
1185 _verify_size_exact, // expect generation and heap sizes to match exactly
1186 _verify_gcstate_stable // full gc cleaned up everything
1187 );
1188 }
1189
1190 // TODO: Why this closure does not visit metadata?
1191 class ShenandoahVerifyNoForwared : public BasicOopIterateClosure {
1192 private:
1193 template <class T>
1194 void do_oop_work(T* p) {
1195 T o = RawAccess<>::oop_load(p);
1196 if (!CompressedOops::is_null(o)) {
1197 oop obj = CompressedOops::decode_not_null(o);
1198 oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1199 if (obj != fwd) {
1200 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1201 "Verify Roots", "Should not be forwarded", __FILE__, __LINE__);
1202 }
1203 }
1204 }
1205
1206 public:
1207 void do_oop(narrowOop* p) { do_oop_work(p); }
1208 void do_oop(oop* p) { do_oop_work(p); }
1209 };
1210
1211 // TODO: Why this closure does not visit metadata?
1212 class ShenandoahVerifyInToSpaceClosure : public BasicOopIterateClosure {
1213 private:
1214 template <class T>
1215 void do_oop_work(T* p) {
1216 T o = RawAccess<>::oop_load(p);
1217 if (!CompressedOops::is_null(o)) {
1218 oop obj = CompressedOops::decode_not_null(o);
1219 ShenandoahHeap* heap = ShenandoahHeap::heap();
1220
1221 if (!heap->marking_context()->is_marked_or_old(obj)) {
1222 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1223 "Verify Roots In To-Space", "Should be marked", __FILE__, __LINE__);
1224 }
1225
1226 if (heap->in_collection_set(obj)) {
1227 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1228 "Verify Roots In To-Space", "Should not be in collection set", __FILE__, __LINE__);
1229 }
1230
1231 oop fwd = ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1232 if (obj != fwd) {
1233 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1234 "Verify Roots In To-Space", "Should not be forwarded", __FILE__, __LINE__);
1235 }
1236 }
1237 }
1238
1239 public:
1240 void do_oop(narrowOop* p) { do_oop_work(p); }
1241 void do_oop(oop* p) { do_oop_work(p); }
1242 };
1243
1244 void ShenandoahVerifier::verify_roots_in_to_space() {
1245 ShenandoahVerifyInToSpaceClosure cl;
1246 ShenandoahRootVerifier::roots_do(&cl);
1247 }
1248
1249 void ShenandoahVerifier::verify_roots_no_forwarded() {
1250 ShenandoahVerifyNoForwared cl;
1251 ShenandoahRootVerifier::roots_do(&cl);
1252 }
1253
1254 class ShenandoahVerifyRemSetClosure : public BasicOopIterateClosure {
1255 protected:
1256 bool const _init_mark;
1257 ShenandoahHeap* const _heap;
1258 RememberedScanner* const _scanner;
1259
1260 public:
1261 // Argument distinguishes between initial mark or start of update refs verification.
1262 ShenandoahVerifyRemSetClosure(bool init_mark) :
1263 _init_mark(init_mark),
1264 _heap(ShenandoahHeap::heap()),
1265 _scanner(_heap->card_scan()) {}
1266
1267 template<class T>
1268 inline void work(T* p) {
1269 T o = RawAccess<>::oop_load(p);
1270 if (!CompressedOops::is_null(o)) {
1271 oop obj = CompressedOops::decode_not_null(o);
1272 if (_heap->is_in_young(obj)) {
1273 size_t card_index = _scanner->card_index_for_addr((HeapWord*) p);
1274 if (_init_mark && !_scanner->is_card_dirty(card_index)) {
1275 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1276 "Verify init-mark remembered set violation", "clean card should be dirty", __FILE__, __LINE__);
1277 } else if (!_init_mark && !_scanner->is_write_card_dirty(card_index)) {
1278 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, nullptr,
1279 "Verify init-update-refs remembered set violation", "clean card should be dirty", __FILE__, __LINE__);
1280 }
1281 }
1282 }
1283 }
1284
1285 virtual void do_oop(narrowOop* p) { work(p); }
1286 virtual void do_oop(oop* p) { work(p); }
1287 };
1288
1289 void ShenandoahVerifier::help_verify_region_rem_set(ShenandoahHeapRegion* r, ShenandoahMarkingContext* ctx, HeapWord* from,
1290 HeapWord* top, HeapWord* registration_watermark, const char* message) {
1291 RememberedScanner* scanner = _heap->card_scan();
1292 ShenandoahVerifyRemSetClosure check_interesting_pointers(false);
1293
1294 HeapWord* obj_addr = from;
1295 if (r->is_humongous_start()) {
1296 oop obj = cast_to_oop(obj_addr);
1297 if ((ctx == nullptr) || ctx->is_marked(obj)) {
1298 size_t card_index = scanner->card_index_for_addr(obj_addr);
1299 // For humongous objects, the typical object is an array, so the following checks may be overkill
1300 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
1301 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
1302 if (!scanner->is_write_card_dirty(card_index) || obj->is_objArray()) {
1303 obj->oop_iterate(&check_interesting_pointers);
1304 }
1305 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
1306 }
1307 // else, this humongous object is not live so no need to verify its internal pointers
1308
1309 if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
1310 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr, message,
1311 "object not properly registered", __FILE__, __LINE__);
1312 }
1313 } else if (!r->is_humongous()) {
1314 while (obj_addr < top) {
1315 oop obj = cast_to_oop(obj_addr);
1316 // ctx->is_marked() returns true if mark bit set or if obj above TAMS.
1317 if ((ctx == nullptr) || ctx->is_marked(obj)) {
1318 size_t card_index = scanner->card_index_for_addr(obj_addr);
1319 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
1320 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
1321 if (!scanner->is_write_card_dirty(card_index) || obj->is_objArray()) {
1322 obj->oop_iterate(&check_interesting_pointers);
1323 }
1324 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
1325
1326 if ((obj_addr < registration_watermark) && !scanner->verify_registration(obj_addr, ctx)) {
1327 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, obj_addr, nullptr, message,
1328 "object not properly registered", __FILE__, __LINE__);
1329 }
1330 obj_addr += obj->size();
1331 } else {
1332 // This object is not live so we don't verify dirty cards contained therein
1333 HeapWord* tams = ctx->top_at_mark_start(r);
1334 obj_addr = ctx->get_next_marked_addr(obj_addr, tams);
1335 }
1336 }
1337 }
1338 }
1339
1340 // Assure that the remember set has a dirty card everywhere there is an interesting pointer.
1341 // This examines the read_card_table between bottom() and top() since all PLABS are retired
1342 // before the safepoint for init_mark. Actually, we retire them before update-references and don't
1343 // restore them until the start of evacuation.
1344 void ShenandoahVerifier::verify_rem_set_before_mark() {
1345 shenandoah_assert_safepoint();
1346 assert(_heap->mode()->is_generational(), "Only verify remembered set for generational operational modes");
1347
1348 ShenandoahRegionIterator iterator;
1349 RememberedScanner* scanner = _heap->card_scan();
1350 ShenandoahVerifyRemSetClosure check_interesting_pointers(true);
1351 ShenandoahMarkingContext* ctx;
1352
1353 log_debug(gc)("Verifying remembered set at %s mark", _heap->doing_mixed_evacuations()? "mixed": "young");
1354
1355 if (_heap->is_old_bitmap_stable() || _heap->active_generation()->is_global()) {
1356 ctx = _heap->complete_marking_context();
1357 } else {
1358 ctx = nullptr;
1359 }
1360
1361 while (iterator.has_next()) {
1362 ShenandoahHeapRegion* r = iterator.next();
1363 if (r == nullptr) {
1364 // TODO: Can this really happen?
1365 break;
1366 }
1367
1368 HeapWord* tams = (ctx != nullptr) ? ctx->top_at_mark_start(r) : nullptr;
1369
1370 // TODO: Is this replaceable with call to help_verify_region_rem_set?
1371
1372 if (r->is_old() && r->is_active()) {
1373 HeapWord* obj_addr = r->bottom();
1374 if (r->is_humongous_start()) {
1375 oop obj = cast_to_oop(obj_addr);
1376 if ((ctx == nullptr) || ctx->is_marked(obj)) {
1377 // For humongous objects, the typical object is an array, so the following checks may be overkill
1378 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
1379 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
1380 if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
1381 obj->oop_iterate(&check_interesting_pointers);
1382 }
1383 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
1384 }
1385 // else, this humongous object is not marked so no need to verify its internal pointers
1386 if (!scanner->verify_registration(obj_addr, ctx)) {
1387 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, nullptr, nullptr,
1388 "Verify init-mark remembered set violation", "object not properly registered", __FILE__, __LINE__);
1389 }
1390 } else if (!r->is_humongous()) {
1391 HeapWord* top = r->top();
1392 while (obj_addr < top) {
1393 oop obj = cast_to_oop(obj_addr);
1394 // ctx->is_marked() returns true if mark bit set (TAMS not relevant during init mark)
1395 if ((ctx == nullptr) || ctx->is_marked(obj)) {
1396 // For regular objects (not object arrays), if the card holding the start of the object is dirty,
1397 // we do not need to verify that cards spanning interesting pointers within this object are dirty.
1398 if (!scanner->is_card_dirty(obj_addr) || obj->is_objArray()) {
1399 obj->oop_iterate(&check_interesting_pointers);
1400 }
1401 // else, object's start is marked dirty and obj is not an objArray, so any interesting pointers are covered
1402 if (!scanner->verify_registration(obj_addr, ctx)) {
1403 ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, nullptr, nullptr,
1404 "Verify init-mark remembered set violation", "object not properly registered", __FILE__, __LINE__);
1405 }
1406 obj_addr += obj->size();
1407 } else {
1408 // This object is not live so we don't verify dirty cards contained therein
1409 assert(tams != nullptr, "If object is not live, ctx and tams should be non-null");
1410 obj_addr = ctx->get_next_marked_addr(obj_addr, tams);
1411 }
1412 }
1413 } // else, we ignore humongous continuation region
1414 } // else, this is not an OLD region so we ignore it
1415 } // all regions have been processed
1416 }
1417
1418 void ShenandoahVerifier::verify_rem_set_after_full_gc() {
1419 shenandoah_assert_safepoint();
1420 assert(_heap->mode()->is_generational(), "Only verify remembered set for generational operational modes");
1421
1422 ShenandoahRegionIterator iterator;
1423
1424 while (iterator.has_next()) {
1425 ShenandoahHeapRegion* r = iterator.next();
1426 if (r == nullptr) {
1427 // TODO: Can this really happen?
1428 break;
1429 }
1430 if (r->is_old() && !r->is_cset()) {
1431 help_verify_region_rem_set(r, nullptr, r->bottom(), r->top(), r->top(), "Remembered set violation at end of Full GC");
1432 }
1433 }
1434 }
1435
1436 // Assure that the remember set has a dirty card everywhere there is an interesting pointer. Even though
1437 // the update-references scan of remembered set only examines cards up to update_watermark, the remembered
1438 // set should be valid through top. This examines the write_card_table between bottom() and top() because
1439 // all PLABS are retired immediately before the start of update refs.
1440 void ShenandoahVerifier::verify_rem_set_before_update_ref() {
1441 shenandoah_assert_safepoint();
1442 assert(_heap->mode()->is_generational(), "Only verify remembered set for generational operational modes");
1443
1444 ShenandoahRegionIterator iterator;
1445 ShenandoahMarkingContext* ctx;
1446
1447 if (_heap->is_old_bitmap_stable() || _heap->active_generation()->is_global()) {
1448 ctx = _heap->complete_marking_context();
1449 } else {
1450 ctx = nullptr;
1451 }
1452
1453 while (iterator.has_next()) {
1454 ShenandoahHeapRegion* r = iterator.next();
1455 if (r == nullptr) {
1456 // TODO: Can this really happen?
1457 break;
1458 }
1459 if (r->is_old() && !r->is_cset()) {
1460 help_verify_region_rem_set(r, ctx, r->bottom(), r->top(), r->get_update_watermark(),
1461 "Remembered set violation at init-update-references");
1462 }
1463 }
1464 }