1 /*
   2  * Copyright (c) 2017, 2020, Red Hat, Inc. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 
  27 #include "gc/shenandoah/shenandoahAsserts.hpp"
  28 #include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
  29 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
  30 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
  31 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  32 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
  33 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
  34 #include "gc/shenandoah/shenandoahUtils.hpp"
  35 #include "gc/shenandoah/shenandoahVerifier.hpp"
  36 #include "memory/allocation.hpp"
  37 #include "memory/iterator.inline.hpp"
  38 #include "memory/resourceArea.hpp"
  39 #include "oops/compressedOops.inline.hpp"
  40 #include "runtime/atomic.hpp"
  41 #include "runtime/orderAccess.hpp"
  42 #include "utilities/align.hpp"
  43 
  44 // Avoid name collision on verify_oop (defined in macroAssembler_arm.hpp)
  45 #ifdef verify_oop
  46 #undef verify_oop
  47 #endif
  48 
  49 class ShenandoahVerifyOopClosure : public BasicOopIterateClosure {
  50 private:
  51   const char* _phase;
  52   ShenandoahVerifier::VerifyOptions _options;
  53   ShenandoahVerifierStack* _stack;
  54   ShenandoahHeap* _heap;
  55   MarkBitMap* _map;
  56   ShenandoahLivenessData* _ld;
  57   void* _interior_loc;
  58   oop _loc;
  59 
  60 public:
  61   ShenandoahVerifyOopClosure(ShenandoahVerifierStack* stack, MarkBitMap* map, ShenandoahLivenessData* ld,
  62                              const char* phase, ShenandoahVerifier::VerifyOptions options) :
  63     _phase(phase),
  64     _options(options),
  65     _stack(stack),
  66     _heap(ShenandoahHeap::heap()),
  67     _map(map),
  68     _ld(ld),
  69     _interior_loc(NULL),
  70     _loc(NULL) { }
  71 
  72 private:
  73   void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {
  74     if (!test) {
  75       ShenandoahAsserts::print_failure(level, obj, _interior_loc, _loc, _phase, label, __FILE__, __LINE__);
  76     }
  77   }
  78 
  79   template <class T>
  80   void do_oop_work(T* p) {
  81     T o = RawAccess<>::oop_load(p);
  82     if (!CompressedOops::is_null(o)) {
  83       oop obj = CompressedOops::decode_not_null(o);
  84 
  85       // Single threaded verification can use faster non-atomic stack and bitmap
  86       // methods.
  87       //
  88       // For performance reasons, only fully verify non-marked field values.
  89       // We are here when the host object for *p is already marked.
  90 
  91       if (_map->par_mark(obj)) {
  92         verify_oop_at(p, obj);
  93         _stack->push(ShenandoahVerifierTask(obj));
  94       }
  95     }
  96   }
  97 
  98   void verify_oop(oop obj) {
  99     // Perform consistency checks with gradually decreasing safety level. This guarantees
 100     // that failure report would not try to touch something that was not yet verified to be
 101     // safe to process.
 102 
 103     check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in(obj),
 104               "oop must be in heap");
 105     check(ShenandoahAsserts::_safe_unknown, obj, is_object_aligned(obj),
 106               "oop must be aligned");
 107 
 108     ShenandoahHeapRegion *obj_reg = _heap->heap_region_containing(obj);
 109     Klass* obj_klass = obj->klass_or_null();
 110 
 111     // Verify that obj is not in dead space:
 112     {
 113       // Do this before touching obj->size()
 114       check(ShenandoahAsserts::_safe_unknown, obj, obj_klass != NULL,
 115              "Object klass pointer should not be NULL");
 116       check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),
 117              "Object klass pointer must go to metaspace");
 118 
 119       HeapWord *obj_addr = cast_from_oop<HeapWord*>(obj);
 120       check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),
 121              "Object start should be within the region");
 122 
 123       if (!obj_reg->is_humongous()) {
 124         check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + obj->size()) <= obj_reg->top(),
 125                "Object end should be within the region");
 126       } else {
 127         size_t humongous_start = obj_reg->region_number();
 128         size_t humongous_end = humongous_start + (obj->size() >> ShenandoahHeapRegion::region_size_words_shift());
 129         for (size_t idx = humongous_start + 1; idx < humongous_end; idx++) {
 130           check(ShenandoahAsserts::_safe_unknown, obj, _heap->get_region(idx)->is_humongous_continuation(),
 131                  "Humongous object is in continuation that fits it");
 132         }
 133       }
 134 
 135       // ------------ obj is safe at this point --------------
 136 
 137       check(ShenandoahAsserts::_safe_oop, obj, obj_reg->is_active(),
 138             "Object should be in active region");
 139 
 140       switch (_options._verify_liveness) {
 141         case ShenandoahVerifier::_verify_liveness_disable:
 142           // skip
 143           break;
 144         case ShenandoahVerifier::_verify_liveness_complete:
 145           Atomic::add(&_ld[obj_reg->region_number()], (uint) obj->size());
 146           // fallthrough for fast failure for un-live regions:
 147         case ShenandoahVerifier::_verify_liveness_conservative:
 148           check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live(),
 149                    "Object must belong to region with live data");
 150           break;
 151         default:
 152           assert(false, "Unhandled liveness verification");
 153       }
 154     }
 155 
 156     oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
 157 
 158     ShenandoahHeapRegion* fwd_reg = NULL;
 159 
 160     if (obj != fwd) {
 161       check(ShenandoahAsserts::_safe_oop, obj, _heap->is_in(fwd),
 162              "Forwardee must be in heap");
 163       check(ShenandoahAsserts::_safe_oop, obj, !CompressedOops::is_null(fwd),
 164              "Forwardee is set");
 165       check(ShenandoahAsserts::_safe_oop, obj, is_object_aligned(fwd),
 166              "Forwardee must be aligned");
 167 
 168       // Do this before touching fwd->size()
 169       Klass* fwd_klass = fwd->klass_or_null();
 170       check(ShenandoahAsserts::_safe_oop, obj, fwd_klass != NULL,
 171              "Forwardee klass pointer should not be NULL");
 172       check(ShenandoahAsserts::_safe_oop, obj, Metaspace::contains(fwd_klass),
 173              "Forwardee klass pointer must go to metaspace");
 174       check(ShenandoahAsserts::_safe_oop, obj, obj_klass == fwd_klass,
 175              "Forwardee klass pointer must go to metaspace");
 176 
 177       fwd_reg = _heap->heap_region_containing(fwd);
 178 
 179       // Verify that forwardee is not in the dead space:
 180       check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),
 181              "Should have no humongous forwardees");
 182 
 183       HeapWord *fwd_addr = cast_from_oop<HeapWord *>(fwd);
 184       check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),
 185              "Forwardee start should be within the region");
 186       check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + fwd->size()) <= fwd_reg->top(),
 187              "Forwardee end should be within the region");
 188 
 189       oop fwd2 = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(fwd);
 190       check(ShenandoahAsserts::_safe_oop, obj, (fwd == fwd2),
 191              "Double forwarding");
 192     } else {
 193       fwd_reg = obj_reg;
 194     }
 195 
 196     // ------------ obj and fwd are safe at this point --------------
 197 
 198     switch (_options._verify_marked) {
 199       case ShenandoahVerifier::_verify_marked_disable:
 200         // skip
 201         break;
 202       case ShenandoahVerifier::_verify_marked_incomplete:
 203         check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked(obj),
 204                "Must be marked in incomplete bitmap");
 205         break;
 206       case ShenandoahVerifier::_verify_marked_complete:
 207         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked(obj),
 208                "Must be marked in complete bitmap");
 209         break;
 210       default:
 211         assert(false, "Unhandled mark verification");
 212     }
 213 
 214     switch (_options._verify_forwarded) {
 215       case ShenandoahVerifier::_verify_forwarded_disable:
 216         // skip
 217         break;
 218       case ShenandoahVerifier::_verify_forwarded_none: {
 219         check(ShenandoahAsserts::_safe_all, obj, (obj == fwd),
 220                "Should not be forwarded");
 221         break;
 222       }
 223       case ShenandoahVerifier::_verify_forwarded_allow: {
 224         if (obj != fwd) {
 225           check(ShenandoahAsserts::_safe_all, obj, obj_reg != fwd_reg,
 226                  "Forwardee should be in another region");
 227         }
 228         break;
 229       }
 230       default:
 231         assert(false, "Unhandled forwarding verification");
 232     }
 233 
 234     switch (_options._verify_cset) {
 235       case ShenandoahVerifier::_verify_cset_disable:
 236         // skip
 237         break;
 238       case ShenandoahVerifier::_verify_cset_none:
 239         check(ShenandoahAsserts::_safe_all, obj, !_heap->in_collection_set(obj),
 240                "Should not have references to collection set");
 241         break;
 242       case ShenandoahVerifier::_verify_cset_forwarded:
 243         if (_heap->in_collection_set(obj)) {
 244           check(ShenandoahAsserts::_safe_all, obj, (obj != fwd),
 245                  "Object in collection set, should have forwardee");
 246         }
 247         break;
 248       default:
 249         assert(false, "Unhandled cset verification");
 250     }
 251 
 252   }
 253 
 254 public:
 255   /**
 256    * Verify object with known interior reference.
 257    * @param p interior reference where the object is referenced from; can be off-heap
 258    * @param obj verified object
 259    */
 260   template <class T>
 261   void verify_oop_at(T* p, oop obj) {
 262     _interior_loc = p;
 263     verify_oop(obj);
 264     _interior_loc = NULL;
 265   }
 266 
 267   /**
 268    * Verify object without known interior reference.
 269    * Useful when picking up the object at known offset in heap,
 270    * but without knowing what objects reference it.
 271    * @param obj verified object
 272    */
 273   void verify_oop_standalone(oop obj) {
 274     _interior_loc = NULL;
 275     verify_oop(obj);
 276     _interior_loc = NULL;
 277   }
 278 
 279   /**
 280    * Verify oop fields from this object.
 281    * @param obj host object for verified fields
 282    */
 283   void verify_oops_from(oop obj) {
 284     _loc = obj;
 285     obj->oop_iterate(this);
 286     _loc = NULL;
 287   }
 288 
 289   virtual void do_oop(oop* p) { do_oop_work(p); }
 290   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 291 };
 292 
 293 class ShenandoahCalculateRegionStatsClosure : public ShenandoahHeapRegionClosure {
 294 private:
 295   size_t _used, _committed, _garbage;
 296 public:
 297   ShenandoahCalculateRegionStatsClosure() : _used(0), _committed(0), _garbage(0) {};
 298 
 299   void heap_region_do(ShenandoahHeapRegion* r) {
 300     _used += r->used();
 301     _garbage += r->garbage();
 302     _committed += r->is_committed() ? ShenandoahHeapRegion::region_size_bytes() : 0;
 303   }
 304 
 305   size_t used() { return _used; }
 306   size_t committed() { return _committed; }
 307   size_t garbage() { return _garbage; }
 308 };
 309 
 310 class ShenandoahVerifyHeapRegionClosure : public ShenandoahHeapRegionClosure {
 311 private:
 312   ShenandoahHeap* _heap;
 313   const char* _phase;
 314   ShenandoahVerifier::VerifyRegions _regions;
 315 public:
 316   ShenandoahVerifyHeapRegionClosure(const char* phase, ShenandoahVerifier::VerifyRegions regions) :
 317     _heap(ShenandoahHeap::heap()),
 318     _phase(phase),
 319     _regions(regions) {};
 320 
 321   void print_failure(ShenandoahHeapRegion* r, const char* label) {
 322     ResourceMark rm;
 323 
 324     ShenandoahMessageBuffer msg("Shenandoah verification failed; %s: %s\n\n", _phase, label);
 325 
 326     stringStream ss;
 327     r->print_on(&ss);
 328     msg.append("%s", ss.as_string());
 329 
 330     report_vm_error(__FILE__, __LINE__, msg.buffer());
 331   }
 332 
 333   void verify(ShenandoahHeapRegion* r, bool test, const char* msg) {
 334     if (!test) {
 335       print_failure(r, msg);
 336     }
 337   }
 338 
 339   void heap_region_do(ShenandoahHeapRegion* r) {
 340     switch (_regions) {
 341       case ShenandoahVerifier::_verify_regions_disable:
 342         break;
 343       case ShenandoahVerifier::_verify_regions_notrash:
 344         verify(r, !r->is_trash(),
 345                "Should not have trash regions");
 346         break;
 347       case ShenandoahVerifier::_verify_regions_nocset:
 348         verify(r, !r->is_cset(),
 349                "Should not have cset regions");
 350         break;
 351       case ShenandoahVerifier::_verify_regions_notrash_nocset:
 352         verify(r, !r->is_trash(),
 353                "Should not have trash regions");
 354         verify(r, !r->is_cset(),
 355                "Should not have cset regions");
 356         break;
 357       default:
 358         ShouldNotReachHere();
 359     }
 360 
 361     verify(r, r->capacity() == ShenandoahHeapRegion::region_size_bytes(),
 362            "Capacity should match region size");
 363 
 364     verify(r, r->bottom() <= r->top(),
 365            "Region top should not be less than bottom");
 366 
 367     verify(r, r->bottom() <= _heap->marking_context()->top_at_mark_start(r),
 368            "Region TAMS should not be less than bottom");
 369 
 370     verify(r, _heap->marking_context()->top_at_mark_start(r) <= r->top(),
 371            "Complete TAMS should not be larger than top");
 372 
 373     verify(r, r->get_live_data_bytes() <= r->capacity(),
 374            "Live data cannot be larger than capacity");
 375 
 376     verify(r, r->garbage() <= r->capacity(),
 377            "Garbage cannot be larger than capacity");
 378 
 379     verify(r, r->used() <= r->capacity(),
 380            "Used cannot be larger than capacity");
 381 
 382     verify(r, r->get_shared_allocs() <= r->capacity(),
 383            "Shared alloc count should not be larger than capacity");
 384 
 385     verify(r, r->get_tlab_allocs() <= r->capacity(),
 386            "TLAB alloc count should not be larger than capacity");
 387 
 388     verify(r, r->get_gclab_allocs() <= r->capacity(),
 389            "GCLAB alloc count should not be larger than capacity");
 390 
 391     verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() == r->used(),
 392            "Accurate accounting: shared + TLAB + GCLAB = used");
 393 
 394     verify(r, !r->is_empty() || !r->has_live(),
 395            "Empty regions should not have live data");
 396 
 397     verify(r, r->is_cset() == _heap->collection_set()->is_in(r),
 398            "Transitional: region flags and collection set agree");
 399 
 400     verify(r, r->is_empty() || r->seqnum_first_alloc() != 0,
 401            "Non-empty regions should have first seqnum set");
 402 
 403     verify(r, r->is_empty() || (r->seqnum_first_alloc_mutator() != 0 || r->seqnum_first_alloc_gc() != 0),
 404            "Non-empty regions should have first seqnum set to either GC or mutator");
 405 
 406     verify(r, r->is_empty() || r->seqnum_last_alloc() != 0,
 407            "Non-empty regions should have last seqnum set");
 408 
 409     verify(r, r->is_empty() || (r->seqnum_last_alloc_mutator() != 0 || r->seqnum_last_alloc_gc() != 0),
 410            "Non-empty regions should have last seqnum set to either GC or mutator");
 411 
 412     verify(r, r->seqnum_first_alloc() <= r->seqnum_last_alloc(),
 413            "First seqnum should not be greater than last timestamp");
 414 
 415     verify(r, r->seqnum_first_alloc_mutator() <= r->seqnum_last_alloc_mutator(),
 416            "First mutator seqnum should not be greater than last seqnum");
 417 
 418     verify(r, r->seqnum_first_alloc_gc() <= r->seqnum_last_alloc_gc(),
 419            "First GC seqnum should not be greater than last seqnum");
 420   }
 421 };
 422 
 423 class ShenandoahVerifierReachableTask : public AbstractGangTask {
 424 private:
 425   const char* _label;
 426   ShenandoahRootVerifier* _verifier;
 427   ShenandoahVerifier::VerifyOptions _options;
 428   ShenandoahHeap* _heap;
 429   ShenandoahLivenessData* _ld;
 430   MarkBitMap* _bitmap;
 431   volatile size_t _processed;
 432 
 433 public:
 434   ShenandoahVerifierReachableTask(MarkBitMap* bitmap,
 435                                   ShenandoahLivenessData* ld,
 436                                   ShenandoahRootVerifier* verifier,
 437                                   const char* label,
 438                                   ShenandoahVerifier::VerifyOptions options) :
 439     AbstractGangTask("Shenandoah Parallel Verifier Reachable Task"),
 440     _label(label),
 441     _verifier(verifier),
 442     _options(options),
 443     _heap(ShenandoahHeap::heap()),
 444     _ld(ld),
 445     _bitmap(bitmap),
 446     _processed(0) {};
 447 
 448   size_t processed() {
 449     return _processed;
 450   }
 451 
 452   virtual void work(uint worker_id) {
 453     ResourceMark rm;
 454     ShenandoahVerifierStack stack;
 455 
 456     // On level 2, we need to only check the roots once.
 457     // On level 3, we want to check the roots, and seed the local stack.
 458     // It is a lesser evil to accept multiple root scans at level 3, because
 459     // extended parallelism would buy us out.
 460     if (((ShenandoahVerifyLevel == 2) && (worker_id == 0))
 461         || (ShenandoahVerifyLevel >= 3)) {
 462         ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
 463                                       ShenandoahMessageBuffer("%s, Roots", _label),
 464                                       _options);
 465         if (_heap->unload_classes()) {
 466           _verifier->strong_roots_do(&cl);
 467         } else {
 468           _verifier->roots_do(&cl);
 469         }
 470     }
 471 
 472     size_t processed = 0;
 473 
 474     if (ShenandoahVerifyLevel >= 3) {
 475       ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
 476                                     ShenandoahMessageBuffer("%s, Reachable", _label),
 477                                     _options);
 478       while (!stack.is_empty()) {
 479         processed++;
 480         ShenandoahVerifierTask task = stack.pop();
 481         cl.verify_oops_from(task.obj());
 482       }
 483     }
 484 
 485     Atomic::add(&_processed, processed);
 486   }
 487 };
 488 
 489 class ShenandoahVerifierMarkedRegionTask : public AbstractGangTask {
 490 private:
 491   const char* _label;
 492   ShenandoahVerifier::VerifyOptions _options;
 493   ShenandoahHeap *_heap;
 494   MarkBitMap* _bitmap;
 495   ShenandoahLivenessData* _ld;
 496   volatile size_t _claimed;
 497   volatile size_t _processed;
 498 
 499 public:
 500   ShenandoahVerifierMarkedRegionTask(MarkBitMap* bitmap,
 501                                      ShenandoahLivenessData* ld,
 502                                      const char* label,
 503                                      ShenandoahVerifier::VerifyOptions options) :
 504           AbstractGangTask("Shenandoah Parallel Verifier Marked Region"),
 505           _label(label),
 506           _options(options),
 507           _heap(ShenandoahHeap::heap()),
 508           _bitmap(bitmap),
 509           _ld(ld),
 510           _claimed(0),
 511           _processed(0) {};
 512 
 513   size_t processed() {
 514     return _processed;
 515   }
 516 
 517   virtual void work(uint worker_id) {
 518     ShenandoahVerifierStack stack;
 519     ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
 520                                   ShenandoahMessageBuffer("%s, Marked", _label),
 521                                   _options);
 522 
 523     while (true) {
 524       size_t v = Atomic::fetch_and_add(&_claimed, 1u);
 525       if (v < _heap->num_regions()) {
 526         ShenandoahHeapRegion* r = _heap->get_region(v);
 527         if (!r->is_humongous() && !r->is_trash()) {
 528           work_regular(r, stack, cl);
 529         } else if (r->is_humongous_start()) {
 530           work_humongous(r, stack, cl);
 531         }
 532       } else {
 533         break;
 534       }
 535     }
 536   }
 537 
 538   virtual void work_humongous(ShenandoahHeapRegion *r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {
 539     size_t processed = 0;
 540     HeapWord* obj = r->bottom();
 541     if (_heap->complete_marking_context()->is_marked((oop)obj)) {
 542       verify_and_follow(obj, stack, cl, &processed);
 543     }
 544     Atomic::add(&_processed, processed);
 545   }
 546 
 547   virtual void work_regular(ShenandoahHeapRegion *r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {
 548     size_t processed = 0;
 549     MarkBitMap* mark_bit_map = _heap->complete_marking_context()->mark_bit_map();
 550     HeapWord* tams = _heap->complete_marking_context()->top_at_mark_start(r);
 551 
 552     // Bitmaps, before TAMS
 553     if (tams > r->bottom()) {
 554       HeapWord* start = r->bottom();
 555       HeapWord* addr = mark_bit_map->get_next_marked_addr(start, tams);
 556 
 557       while (addr < tams) {
 558         verify_and_follow(addr, stack, cl, &processed);
 559         addr += 1;
 560         if (addr < tams) {
 561           addr = mark_bit_map->get_next_marked_addr(addr, tams);
 562         }
 563       }
 564     }
 565 
 566     // Size-based, after TAMS
 567     {
 568       HeapWord* limit = r->top();
 569       HeapWord* addr = tams;
 570 
 571       while (addr < limit) {
 572         verify_and_follow(addr, stack, cl, &processed);
 573         addr += oop(addr)->size();
 574       }
 575     }
 576 
 577     Atomic::add(&_processed, processed);
 578   }
 579 
 580   void verify_and_follow(HeapWord *addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t *processed) {
 581     if (!_bitmap->par_mark(addr)) return;
 582 
 583     // Verify the object itself:
 584     oop obj = oop(addr);
 585     cl.verify_oop_standalone(obj);
 586 
 587     // Verify everything reachable from that object too, hopefully realizing
 588     // everything was already marked, and never touching further:
 589     cl.verify_oops_from(obj);
 590     (*processed)++;
 591 
 592     while (!stack.is_empty()) {
 593       ShenandoahVerifierTask task = stack.pop();
 594       cl.verify_oops_from(task.obj());
 595       (*processed)++;
 596     }
 597   }
 598 };
 599 
 600 class VerifyThreadGCState : public ThreadClosure {
 601 private:
 602   const char* _label;
 603   char _expected;
 604 
 605 public:
 606   VerifyThreadGCState(const char* label, char expected) : _expected(expected) {}
 607   void do_thread(Thread* t) {
 608     char actual = ShenandoahThreadLocalData::gc_state(t);
 609     if (actual != _expected) {
 610       fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);
 611     }
 612   }
 613 };
 614 
 615 class ShenandoahGCStateResetter : public StackObj {
 616 private:
 617   ShenandoahHeap* const _heap;
 618   char _gc_state;
 619 
 620 public:
 621   ShenandoahGCStateResetter() : _heap(ShenandoahHeap::heap()) {
 622     _gc_state = _heap->gc_state();
 623     _heap->_gc_state.clear();
 624   }
 625 
 626   ~ShenandoahGCStateResetter() {
 627     _heap->_gc_state.set(_gc_state);
 628     assert(_heap->gc_state() == _gc_state, "Should be restored");
 629   }
 630 };
 631 
 632 void ShenandoahVerifier::verify_at_safepoint(const char *label,
 633                                              VerifyForwarded forwarded, VerifyMarked marked,
 634                                              VerifyCollectionSet cset,
 635                                              VerifyLiveness liveness, VerifyRegions regions,
 636                                              VerifyGCState gcstate,
 637                                              VerifyWeakRoots weak_roots) {
 638   guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");
 639   guarantee(ShenandoahVerify, "only when enabled, and bitmap is initialized in ShenandoahHeap::initialize");
 640 
 641   // Avoid side-effect of changing workers' active thread count, but bypass concurrent/parallel protocol check
 642   ShenandoahPushWorkerScope verify_worker_scope(_heap->workers(), _heap->max_workers(), false /*bypass check*/);
 643 
 644   log_info(gc,start)("Verify %s, Level " INTX_FORMAT, label, ShenandoahVerifyLevel);
 645 
 646   // GC state checks
 647   {
 648     char expected = -1;
 649     bool enabled;
 650     switch (gcstate) {
 651       case _verify_gcstate_disable:
 652         enabled = false;
 653         break;
 654       case _verify_gcstate_forwarded:
 655         enabled = true;
 656         expected = ShenandoahHeap::HAS_FORWARDED;
 657         break;
 658       case _verify_gcstate_evacuation:
 659         enabled = true;
 660         expected = ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::EVACUATION;
 661         break;
 662       case _verify_gcstate_stable:
 663         enabled = true;
 664         expected = ShenandoahHeap::STABLE;
 665         break;
 666       default:
 667         enabled = false;
 668         assert(false, "Unhandled gc-state verification");
 669     }
 670 
 671     if (enabled) {
 672       char actual = _heap->gc_state();
 673       if (actual != expected) {
 674         fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);
 675       }
 676 
 677       VerifyThreadGCState vtgcs(label, expected);
 678       Threads::java_threads_do(&vtgcs);
 679     }
 680   }
 681 
 682   // Deactivate barriers temporarily: Verifier wants plain heap accesses
 683   ShenandoahGCStateResetter resetter;
 684 
 685   // Heap size checks
 686   {
 687     ShenandoahHeapLocker lock(_heap->lock());
 688 
 689     ShenandoahCalculateRegionStatsClosure cl;
 690     _heap->heap_region_iterate(&cl);
 691     size_t heap_used = _heap->used();
 692     guarantee(cl.used() == heap_used,
 693               "%s: heap used size must be consistent: heap-used = " SIZE_FORMAT "%s, regions-used = " SIZE_FORMAT "%s",
 694               label,
 695               byte_size_in_proper_unit(heap_used), proper_unit_for_byte_size(heap_used),
 696               byte_size_in_proper_unit(cl.used()), proper_unit_for_byte_size(cl.used()));
 697 
 698     size_t heap_committed = _heap->committed();
 699     guarantee(cl.committed() == heap_committed,
 700               "%s: heap committed size must be consistent: heap-committed = " SIZE_FORMAT "%s, regions-committed = " SIZE_FORMAT "%s",
 701               label,
 702               byte_size_in_proper_unit(heap_committed), proper_unit_for_byte_size(heap_committed),
 703               byte_size_in_proper_unit(cl.committed()), proper_unit_for_byte_size(cl.committed()));
 704   }
 705 
 706   // Internal heap region checks
 707   if (ShenandoahVerifyLevel >= 1) {
 708     ShenandoahVerifyHeapRegionClosure cl(label, regions);
 709     _heap->heap_region_iterate(&cl);
 710   }
 711 
 712   OrderAccess::fence();
 713   _heap->make_parsable(false);
 714 
 715   // Allocate temporary bitmap for storing marking wavefront:
 716   _verification_bit_map->clear();
 717 
 718   // Allocate temporary array for storing liveness data
 719   ShenandoahLivenessData* ld = NEW_C_HEAP_ARRAY(ShenandoahLivenessData, _heap->num_regions(), mtGC);
 720   Copy::fill_to_bytes((void*)ld, _heap->num_regions()*sizeof(ShenandoahLivenessData), 0);
 721 
 722   const VerifyOptions& options = ShenandoahVerifier::VerifyOptions(forwarded, marked, cset, liveness, regions, gcstate);
 723 
 724   // Steps 1-2. Scan root set to get initial reachable set. Finish walking the reachable heap.
 725   // This verifies what application can see, since it only cares about reachable objects.
 726   size_t count_reachable = 0;
 727   if (ShenandoahVerifyLevel >= 2) {
 728     ShenandoahRootVerifier verifier;
 729     switch (weak_roots) {
 730       case _verify_serial_weak_roots:
 731         verifier.excludes(ShenandoahRootVerifier::ConcurrentWeakRoots);
 732         break;
 733       case _verify_concurrent_weak_roots:
 734         verifier.excludes(ShenandoahRootVerifier::SerialWeakRoots);
 735         break;
 736       case _verify_all_weak_roots:
 737         break;
 738       default:
 739         ShouldNotReachHere();
 740     }
 741 
 742     ShenandoahVerifierReachableTask task(_verification_bit_map, ld, &verifier, label, options);
 743     _heap->workers()->run_task(&task);
 744     count_reachable = task.processed();
 745   }
 746 
 747   // Step 3. Walk marked objects. Marked objects might be unreachable. This verifies what collector,
 748   // not the application, can see during the region scans. There is no reason to process the objects
 749   // that were already verified, e.g. those marked in verification bitmap. There is interaction with TAMS:
 750   // before TAMS, we verify the bitmaps, if available; after TAMS, we walk until the top(). It mimics
 751   // what marked_object_iterate is doing, without calling into that optimized (and possibly incorrect)
 752   // version
 753 
 754   size_t count_marked = 0;
 755   if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete) {
 756     guarantee(_heap->marking_context()->is_complete(), "Marking context should be complete");
 757     ShenandoahVerifierMarkedRegionTask task(_verification_bit_map, ld, label, options);
 758     _heap->workers()->run_task(&task);
 759     count_marked = task.processed();
 760   } else {
 761     guarantee(ShenandoahVerifyLevel < 4 || marked == _verify_marked_incomplete || marked == _verify_marked_disable, "Should be");
 762   }
 763 
 764   // Step 4. Verify accumulated liveness data, if needed. Only reliable if verification level includes
 765   // marked objects.
 766 
 767   if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete && liveness == _verify_liveness_complete) {
 768     for (size_t i = 0; i < _heap->num_regions(); i++) {
 769       ShenandoahHeapRegion* r = _heap->get_region(i);
 770 
 771       juint verf_live = 0;
 772       if (r->is_humongous()) {
 773         // For humongous objects, test if start region is marked live, and if so,
 774         // all humongous regions in that chain have live data equal to their "used".
 775         juint start_live = Atomic::load_acquire(&ld[r->humongous_start_region()->region_number()]);
 776         if (start_live > 0) {
 777           verf_live = (juint)(r->used() / HeapWordSize);
 778         }
 779       } else {
 780         verf_live = Atomic::load_acquire(&ld[r->region_number()]);
 781       }
 782 
 783       size_t reg_live = r->get_live_data_words();
 784       if (reg_live != verf_live) {
 785         ResourceMark rm;
 786         stringStream ss;
 787         r->print_on(&ss);
 788         fatal("%s: Live data should match: region-live = " SIZE_FORMAT ", verifier-live = " UINT32_FORMAT "\n%s",
 789               label, reg_live, verf_live, ss.as_string());
 790       }
 791     }
 792   }
 793 
 794   log_info(gc)("Verify %s, Level " INTX_FORMAT " (" SIZE_FORMAT " reachable, " SIZE_FORMAT " marked)",
 795                label, ShenandoahVerifyLevel, count_reachable, count_marked);
 796 
 797   FREE_C_HEAP_ARRAY(ShenandoahLivenessData, ld);
 798 }
 799 
 800 void ShenandoahVerifier::verify_generic(VerifyOption vo) {
 801   verify_at_safepoint(
 802           "Generic Verification",
 803           _verify_forwarded_allow,     // conservatively allow forwarded
 804           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 805           _verify_cset_disable,        // cset may be inconsistent
 806           _verify_liveness_disable,    // no reliable liveness data
 807           _verify_regions_disable,     // no reliable region data
 808           _verify_gcstate_disable,     // no data about gcstate
 809           _verify_all_weak_roots
 810   );
 811 }
 812 
 813 void ShenandoahVerifier::verify_before_concmark() {
 814   if (_heap->has_forwarded_objects()) {
 815     verify_at_safepoint(
 816             "Before Mark",
 817             _verify_forwarded_allow,     // may have forwarded references
 818             _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 819             _verify_cset_forwarded,      // allow forwarded references to cset
 820             _verify_liveness_disable,    // no reliable liveness data
 821             _verify_regions_notrash,     // no trash regions
 822             _verify_gcstate_forwarded,   // there are forwarded objects
 823             _verify_all_weak_roots
 824     );
 825   } else {
 826     verify_at_safepoint(
 827             "Before Mark",
 828             _verify_forwarded_none,      // UR should have fixed up
 829             _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 830             _verify_cset_none,           // UR should have fixed this
 831             _verify_liveness_disable,    // no reliable liveness data
 832             _verify_regions_notrash,     // no trash regions
 833             _verify_gcstate_stable,      // there are no forwarded objects
 834             _verify_all_weak_roots
 835     );
 836   }
 837 }
 838 
 839 void ShenandoahVerifier::verify_after_concmark() {
 840   verify_at_safepoint(
 841           "After Mark",
 842           _verify_forwarded_none,      // no forwarded references
 843           _verify_marked_complete,     // bitmaps as precise as we can get
 844           _verify_cset_none,           // no references to cset anymore
 845           _verify_liveness_complete,   // liveness data must be complete here
 846           _verify_regions_disable,     // trash regions not yet recycled
 847           _verify_gcstate_stable,       // mark should have stabilized the heap
 848           _verify_all_weak_roots
 849   );
 850 }
 851 
 852 void ShenandoahVerifier::verify_before_evacuation() {
 853   // Concurrent weak roots are evacuated during concurrent phase
 854   VerifyWeakRoots verify_weak_roots = ShenandoahConcurrentRoots::should_do_concurrent_class_unloading() ?
 855                                       _verify_serial_weak_roots :
 856                                       _verify_all_weak_roots;
 857 
 858   verify_at_safepoint(
 859           "Before Evacuation",
 860           _verify_forwarded_none,    // no forwarded references
 861           _verify_marked_complete,   // walk over marked objects too
 862           _verify_cset_disable,      // non-forwarded references to cset expected
 863           _verify_liveness_complete, // liveness data must be complete here
 864           _verify_regions_disable,   // trash regions not yet recycled
 865           _verify_gcstate_stable,    // mark should have stabilized the heap
 866           verify_weak_roots
 867   );
 868 }
 869 
 870 void ShenandoahVerifier::verify_during_evacuation() {
 871   // Concurrent weak roots are evacuated during concurrent phase
 872   VerifyWeakRoots verify_weak_roots = ShenandoahConcurrentRoots::should_do_concurrent_class_unloading() ?
 873                                       _verify_serial_weak_roots :
 874                                       _verify_all_weak_roots;
 875 
 876   verify_at_safepoint(
 877           "During Evacuation",
 878           _verify_forwarded_allow,    // some forwarded references are allowed
 879           _verify_marked_disable,     // walk only roots
 880           _verify_cset_disable,       // some cset references are not forwarded yet
 881           _verify_liveness_disable,   // liveness data might be already stale after pre-evacs
 882           _verify_regions_disable,    // trash regions not yet recycled
 883           _verify_gcstate_evacuation, // evacuation is in progress
 884           verify_weak_roots
 885   );
 886 }
 887 
 888 void ShenandoahVerifier::verify_after_evacuation() {
 889   verify_at_safepoint(
 890           "After Evacuation",
 891           _verify_forwarded_allow,     // objects are still forwarded
 892           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
 893           _verify_cset_forwarded,      // all cset refs are fully forwarded
 894           _verify_liveness_disable,    // no reliable liveness data anymore
 895           _verify_regions_notrash,     // trash regions have been recycled already
 896           _verify_gcstate_forwarded,   // evacuation produced some forwarded objects
 897           _verify_all_weak_roots
 898   );
 899 }
 900 
 901 void ShenandoahVerifier::verify_before_updaterefs() {
 902   verify_at_safepoint(
 903           "Before Updating References",
 904           _verify_forwarded_allow,     // forwarded references allowed
 905           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
 906           _verify_cset_forwarded,      // all cset refs are fully forwarded
 907           _verify_liveness_disable,    // no reliable liveness data anymore
 908           _verify_regions_notrash,     // trash regions have been recycled already
 909           _verify_gcstate_forwarded,   // evacuation should have produced some forwarded objects
 910           _verify_all_weak_roots
 911   );
 912 }
 913 
 914 void ShenandoahVerifier::verify_after_updaterefs() {
 915   verify_at_safepoint(
 916           "After Updating References",
 917           _verify_forwarded_none,      // no forwarded references
 918           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
 919           _verify_cset_none,           // no cset references, all updated
 920           _verify_liveness_disable,    // no reliable liveness data anymore
 921           _verify_regions_nocset,      // no cset regions, trash regions have appeared
 922           _verify_gcstate_stable,      // update refs had cleaned up forwarded objects
 923           _verify_all_weak_roots
 924   );
 925 }
 926 
 927 void ShenandoahVerifier::verify_after_degenerated() {
 928   verify_at_safepoint(
 929           "After Degenerated GC",
 930           _verify_forwarded_none,      // all objects are non-forwarded
 931           _verify_marked_complete,     // all objects are marked in complete bitmap
 932           _verify_cset_none,           // no cset references
 933           _verify_liveness_disable,    // no reliable liveness data anymore
 934           _verify_regions_notrash_nocset, // no trash, no cset
 935           _verify_gcstate_stable,       // degenerated refs had cleaned up forwarded objects
 936           _verify_all_weak_roots
 937   );
 938 }
 939 
 940 void ShenandoahVerifier::verify_before_traversal() {
 941   verify_at_safepoint(
 942           "Before Traversal",
 943           _verify_forwarded_none,      // cannot have forwarded objects
 944           _verify_marked_disable,      // bitmaps are not relevant before traversal
 945           _verify_cset_none,           // no cset references before traversal
 946           _verify_liveness_disable,    // no reliable liveness data anymore
 947           _verify_regions_notrash_nocset, // no trash and no cset regions
 948           _verify_gcstate_stable,      // nothing forwarded before traversal
 949           _verify_all_weak_roots
 950   );
 951 }
 952 
 953 void ShenandoahVerifier::verify_after_traversal() {
 954   verify_at_safepoint(
 955           "After Traversal",
 956           _verify_forwarded_none,      // cannot have forwarded objects
 957           _verify_marked_complete,     // should have complete marking after traversal
 958           _verify_cset_none,           // no cset references left after traversal
 959           _verify_liveness_disable,    // liveness data is not collected for new allocations
 960           _verify_regions_nocset,      // no cset regions, trash regions allowed
 961           _verify_gcstate_stable,      // nothing forwarded after traversal
 962           _verify_all_weak_roots
 963   );
 964 }
 965 
 966 void ShenandoahVerifier::verify_before_fullgc() {
 967   verify_at_safepoint(
 968           "Before Full GC",
 969           _verify_forwarded_allow,     // can have forwarded objects
 970           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 971           _verify_cset_disable,        // cset might be foobared
 972           _verify_liveness_disable,    // no reliable liveness data anymore
 973           _verify_regions_disable,     // no reliable region data here
 974           _verify_gcstate_disable,     // no reliable gcstate data
 975           _verify_all_weak_roots
 976   );
 977 }
 978 
 979 void ShenandoahVerifier::verify_after_fullgc() {
 980   verify_at_safepoint(
 981           "After Full GC",
 982           _verify_forwarded_none,      // all objects are non-forwarded
 983           _verify_marked_complete,     // all objects are marked in complete bitmap
 984           _verify_cset_none,           // no cset references
 985           _verify_liveness_disable,    // no reliable liveness data anymore
 986           _verify_regions_notrash_nocset, // no trash, no cset
 987           _verify_gcstate_stable,       // full gc cleaned up everything
 988           _verify_all_weak_roots
 989   );
 990 }
 991 
 992 class ShenandoahVerifyNoForwared : public OopClosure {
 993 private:
 994   template <class T>
 995   void do_oop_work(T* p) {
 996     T o = RawAccess<>::oop_load(p);
 997     if (!CompressedOops::is_null(o)) {
 998       oop obj = CompressedOops::decode_not_null(o);
 999       oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1000       if (obj != fwd) {
1001         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
1002                                          "Verify Roots", "Should not be forwarded", __FILE__, __LINE__);
1003       }
1004     }
1005   }
1006 
1007 public:
1008   void do_oop(narrowOop* p) { do_oop_work(p); }
1009   void do_oop(oop* p)       { do_oop_work(p); }
1010 };
1011 
1012 class ShenandoahVerifyInToSpaceClosure : public OopClosure {
1013 private:
1014   template <class T>
1015   void do_oop_work(T* p) {
1016     T o = RawAccess<>::oop_load(p);
1017     if (!CompressedOops::is_null(o)) {
1018       oop obj = CompressedOops::decode_not_null(o);
1019       ShenandoahHeap* heap = ShenandoahHeap::heap_no_check();
1020 
1021       if (!heap->marking_context()->is_marked(obj)) {
1022         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
1023                 "Verify Roots In To-Space", "Should be marked", __FILE__, __LINE__);
1024       }
1025 
1026       if (heap->in_collection_set(obj)) {
1027         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
1028                 "Verify Roots In To-Space", "Should not be in collection set", __FILE__, __LINE__);
1029       }
1030 
1031       oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
1032       if (obj != fwd) {
1033         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
1034                 "Verify Roots In To-Space", "Should not be forwarded", __FILE__, __LINE__);
1035       }
1036     }
1037   }
1038 
1039 public:
1040   void do_oop(narrowOop* p) { do_oop_work(p); }
1041   void do_oop(oop* p)       { do_oop_work(p); }
1042 };
1043 
1044 void ShenandoahVerifier::verify_roots_in_to_space() {
1045   ShenandoahRootVerifier verifier;
1046   ShenandoahVerifyInToSpaceClosure cl;
1047   verifier.oops_do(&cl);
1048 }
1049 
1050 void ShenandoahVerifier::verify_roots_in_to_space_except(ShenandoahRootVerifier::RootTypes types) {
1051   ShenandoahRootVerifier verifier;
1052   verifier.excludes(types);
1053   ShenandoahVerifyInToSpaceClosure cl;
1054   verifier.oops_do(&cl);
1055 }
1056 
1057 void ShenandoahVerifier::verify_roots_no_forwarded() {
1058   ShenandoahRootVerifier verifier;
1059   ShenandoahVerifyNoForwared cl;
1060   verifier.oops_do(&cl);
1061 }
1062 
1063 void ShenandoahVerifier::verify_roots_no_forwarded_except(ShenandoahRootVerifier::RootTypes types) {
1064   ShenandoahRootVerifier verifier;
1065   verifier.excludes(types);
1066   ShenandoahVerifyNoForwared cl;
1067   verifier.oops_do(&cl);
1068 }