1 /*
   2  * Copyright (c) 2017, 2019, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #include "precompiled.hpp"
  25 
  26 #include "gc/shenandoah/shenandoahAsserts.hpp"
  27 #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
  28 #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
  29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  30 #include "gc/shenandoah/shenandoahRootProcessor.hpp"
  31 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
  32 #include "gc/shenandoah/shenandoahUtils.hpp"
  33 #include "gc/shenandoah/shenandoahVerifier.hpp"
  34 #include "memory/allocation.hpp"
  35 #include "memory/iterator.inline.hpp"
  36 #include "memory/resourceArea.hpp"
  37 #include "oops/compressedOops.inline.hpp"
  38 
  39 // Avoid name collision on verify_oop (defined in macroAssembler_arm.hpp)
  40 #ifdef verify_oop
  41 #undef verify_oop
  42 #endif
  43 
  44 class ShenandoahVerifyOopClosure : public BasicOopIterateClosure {
  45 private:
  46   const char* _phase;
  47   ShenandoahVerifier::VerifyOptions _options;
  48   ShenandoahVerifierStack* _stack;
  49   ShenandoahHeap* _heap;
  50   MarkBitMap* _map;
  51   ShenandoahLivenessData* _ld;
  52   void* _interior_loc;
  53   oop _loc;
  54 
  55 public:
  56   ShenandoahVerifyOopClosure(ShenandoahVerifierStack* stack, MarkBitMap* map, ShenandoahLivenessData* ld,
  57                              const char* phase, ShenandoahVerifier::VerifyOptions options) :
  58     _phase(phase),
  59     _options(options),
  60     _stack(stack),
  61     _heap(ShenandoahHeap::heap()),
  62     _map(map),
  63     _ld(ld),
  64     _interior_loc(NULL),
  65     _loc(NULL) { }
  66 
  67 private:
  68   void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {
  69     if (!test) {
  70       ShenandoahAsserts::print_failure(level, obj, _interior_loc, _loc, _phase, label, __FILE__, __LINE__);
  71     }
  72   }
  73 
  74   template <class T>
  75   void do_oop_work(T* p) {
  76     T o = RawAccess<>::oop_load(p);
  77     if (!CompressedOops::is_null(o)) {
  78       oop obj = CompressedOops::decode_not_null(o);
  79 
  80       // Single threaded verification can use faster non-atomic stack and bitmap
  81       // methods.
  82       //
  83       // For performance reasons, only fully verify non-marked field values.
  84       // We are here when the host object for *p is already marked.
  85 
  86       HeapWord* addr = (HeapWord*) obj;
  87       if (_map->par_mark(addr)) {
  88         verify_oop_at(p, obj);
  89         _stack->push(ShenandoahVerifierTask(obj));
  90       }
  91     }
  92   }
  93 
  94   void verify_oop(oop obj) {
  95     // Perform consistency checks with gradually decreasing safety level. This guarantees
  96     // that failure report would not try to touch something that was not yet verified to be
  97     // safe to process.
  98 
  99     check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in(obj),
 100               "oop must be in heap");
 101     check(ShenandoahAsserts::_safe_unknown, obj, check_obj_alignment(obj),
 102               "oop must be aligned");
 103 
 104     ShenandoahHeapRegion *obj_reg = _heap->heap_region_containing(obj);
 105     Klass* obj_klass = obj->klass_or_null();
 106 
 107     // Verify that obj is not in dead space:
 108     {
 109       // Do this before touching obj->size()
 110       check(ShenandoahAsserts::_safe_unknown, obj, obj_klass != NULL,
 111              "Object klass pointer should not be NULL");
 112       check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),
 113              "Object klass pointer must go to metaspace");
 114 
 115       HeapWord *obj_addr = (HeapWord *) obj;
 116       check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),
 117              "Object start should be within the region");
 118 
 119       if (!obj_reg->is_humongous()) {
 120         check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + obj->size()) <= obj_reg->top(),
 121                "Object end should be within the region");
 122       } else {
 123         size_t humongous_start = obj_reg->region_number();
 124         size_t humongous_end = humongous_start + (obj->size() >> ShenandoahHeapRegion::region_size_words_shift());
 125         for (size_t idx = humongous_start + 1; idx < humongous_end; idx++) {
 126           check(ShenandoahAsserts::_safe_unknown, obj, _heap->get_region(idx)->is_humongous_continuation(),
 127                  "Humongous object is in continuation that fits it");
 128         }
 129       }
 130 
 131       // ------------ obj is safe at this point --------------
 132 
 133       check(ShenandoahAsserts::_safe_oop, obj, obj_reg->is_active(),
 134             "Object should be in active region");
 135 
 136       switch (_options._verify_liveness) {
 137         case ShenandoahVerifier::_verify_liveness_disable:
 138           // skip
 139           break;
 140         case ShenandoahVerifier::_verify_liveness_complete:
 141           Atomic::add((uint) obj->size(), &_ld[obj_reg->region_number()]);
 142           // fallthrough for fast failure for un-live regions:
 143         case ShenandoahVerifier::_verify_liveness_conservative:
 144           check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live(),
 145                    "Object must belong to region with live data");
 146           break;
 147         default:
 148           assert(false, "Unhandled liveness verification");
 149       }
 150     }
 151 
 152     oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
 153 
 154     ShenandoahHeapRegion* fwd_reg = NULL;
 155 
 156     if (!oopDesc::equals_raw(obj, fwd)) {
 157       check(ShenandoahAsserts::_safe_oop, obj, _heap->is_in(fwd),
 158              "Forwardee must be in heap");
 159       check(ShenandoahAsserts::_safe_oop, obj, !CompressedOops::is_null(fwd),
 160              "Forwardee is set");
 161       check(ShenandoahAsserts::_safe_oop, obj, check_obj_alignment(fwd),
 162              "Forwardee must be aligned");
 163 
 164       // Do this before touching fwd->size()
 165       Klass* fwd_klass = fwd->klass_or_null();
 166       check(ShenandoahAsserts::_safe_oop, obj, fwd_klass != NULL,
 167              "Forwardee klass pointer should not be NULL");
 168       check(ShenandoahAsserts::_safe_oop, obj, Metaspace::contains(fwd_klass),
 169              "Forwardee klass pointer must go to metaspace");
 170       check(ShenandoahAsserts::_safe_oop, obj, obj_klass == fwd_klass,
 171              "Forwardee klass pointer must go to metaspace");
 172 
 173       fwd_reg = _heap->heap_region_containing(fwd);
 174 
 175       // Verify that forwardee is not in the dead space:
 176       check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),
 177              "Should have no humongous forwardees");
 178 
 179       HeapWord *fwd_addr = (HeapWord *) fwd;
 180       check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),
 181              "Forwardee start should be within the region");
 182       check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + fwd->size()) <= fwd_reg->top(),
 183              "Forwardee end should be within the region");
 184 
 185       oop fwd2 = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(fwd);
 186       check(ShenandoahAsserts::_safe_oop, obj, oopDesc::equals_raw(fwd, fwd2),
 187              "Double forwarding");
 188     } else {
 189       fwd_reg = obj_reg;
 190     }
 191 
 192     // ------------ obj and fwd are safe at this point --------------
 193 
 194     switch (_options._verify_marked) {
 195       case ShenandoahVerifier::_verify_marked_disable:
 196         // skip
 197         break;
 198       case ShenandoahVerifier::_verify_marked_incomplete:
 199         check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked(obj),
 200                "Must be marked in incomplete bitmap");
 201         break;
 202       case ShenandoahVerifier::_verify_marked_complete:
 203         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked(obj),
 204                "Must be marked in complete bitmap");
 205         break;
 206       default:
 207         assert(false, "Unhandled mark verification");
 208     }
 209 
 210     switch (_options._verify_forwarded) {
 211       case ShenandoahVerifier::_verify_forwarded_disable:
 212         // skip
 213         break;
 214       case ShenandoahVerifier::_verify_forwarded_none: {
 215         check(ShenandoahAsserts::_safe_all, obj, oopDesc::equals_raw(obj, fwd),
 216                "Should not be forwarded");
 217         break;
 218       }
 219       case ShenandoahVerifier::_verify_forwarded_allow: {
 220         if (!oopDesc::equals_raw(obj, fwd)) {
 221           check(ShenandoahAsserts::_safe_all, obj, obj_reg != fwd_reg,
 222                  "Forwardee should be in another region");
 223         }
 224         break;
 225       }
 226       default:
 227         assert(false, "Unhandled forwarding verification");
 228     }
 229 
 230     switch (_options._verify_cset) {
 231       case ShenandoahVerifier::_verify_cset_disable:
 232         // skip
 233         break;
 234       case ShenandoahVerifier::_verify_cset_none:
 235         check(ShenandoahAsserts::_safe_all, obj, !_heap->in_collection_set(obj),
 236                "Should not have references to collection set");
 237         break;
 238       case ShenandoahVerifier::_verify_cset_forwarded:
 239         if (_heap->in_collection_set(obj)) {
 240           check(ShenandoahAsserts::_safe_all, obj, !oopDesc::equals_raw(obj, fwd),
 241                  "Object in collection set, should have forwardee");
 242         }
 243         break;
 244       default:
 245         assert(false, "Unhandled cset verification");
 246     }
 247 
 248   }
 249 
 250 public:
 251   /**
 252    * Verify object with known interior reference.
 253    * @param p interior reference where the object is referenced from; can be off-heap
 254    * @param obj verified object
 255    */
 256   template <class T>
 257   void verify_oop_at(T* p, oop obj) {
 258     _interior_loc = p;
 259     verify_oop(obj);
 260     _interior_loc = NULL;
 261   }
 262 
 263   /**
 264    * Verify object without known interior reference.
 265    * Useful when picking up the object at known offset in heap,
 266    * but without knowing what objects reference it.
 267    * @param obj verified object
 268    */
 269   void verify_oop_standalone(oop obj) {
 270     _interior_loc = NULL;
 271     verify_oop(obj);
 272     _interior_loc = NULL;
 273   }
 274 
 275   /**
 276    * Verify oop fields from this object.
 277    * @param obj host object for verified fields
 278    */
 279   void verify_oops_from(oop obj) {
 280     _loc = obj;
 281     obj->oop_iterate(this);
 282     _loc = NULL;
 283   }
 284 
 285   virtual void do_oop(oop* p) { do_oop_work(p); }
 286   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 287 };
 288 
 289 class ShenandoahCalculateRegionStatsClosure : public ShenandoahHeapRegionClosure {
 290 private:
 291   size_t _used, _committed, _garbage;
 292 public:
 293   ShenandoahCalculateRegionStatsClosure() : _used(0), _committed(0), _garbage(0) {};
 294 
 295   void heap_region_do(ShenandoahHeapRegion* r) {
 296     _used += r->used();
 297     _garbage += r->garbage();
 298     _committed += r->is_committed() ? ShenandoahHeapRegion::region_size_bytes() : 0;
 299   }
 300 
 301   size_t used() { return _used; }
 302   size_t committed() { return _committed; }
 303   size_t garbage() { return _garbage; }
 304 };
 305 
 306 class ShenandoahVerifyHeapRegionClosure : public ShenandoahHeapRegionClosure {
 307 private:
 308   ShenandoahHeap* _heap;
 309   const char* _phase;
 310   ShenandoahVerifier::VerifyRegions _regions;
 311 public:
 312   ShenandoahVerifyHeapRegionClosure(const char* phase, ShenandoahVerifier::VerifyRegions regions) :
 313     _heap(ShenandoahHeap::heap()),
 314     _phase(phase),
 315     _regions(regions) {};
 316 
 317   void print_failure(ShenandoahHeapRegion* r, const char* label) {
 318     ResourceMark rm;
 319 
 320     ShenandoahMessageBuffer msg("Shenandoah verification failed; %s: %s\n\n", _phase, label);
 321 
 322     stringStream ss;
 323     r->print_on(&ss);
 324     msg.append("%s", ss.as_string());
 325 
 326     report_vm_error(__FILE__, __LINE__, msg.buffer());
 327   }
 328 
 329   void verify(ShenandoahHeapRegion* r, bool test, const char* msg) {
 330     if (!test) {
 331       print_failure(r, msg);
 332     }
 333   }
 334 
 335   void heap_region_do(ShenandoahHeapRegion* r) {
 336     switch (_regions) {
 337       case ShenandoahVerifier::_verify_regions_disable:
 338         break;
 339       case ShenandoahVerifier::_verify_regions_notrash:
 340         verify(r, !r->is_trash(),
 341                "Should not have trash regions");
 342         break;
 343       case ShenandoahVerifier::_verify_regions_nocset:
 344         verify(r, !r->is_cset(),
 345                "Should not have cset regions");
 346         break;
 347       case ShenandoahVerifier::_verify_regions_notrash_nocset:
 348         verify(r, !r->is_trash(),
 349                "Should not have trash regions");
 350         verify(r, !r->is_cset(),
 351                "Should not have cset regions");
 352         break;
 353       default:
 354         ShouldNotReachHere();
 355     }
 356 
 357     verify(r, r->capacity() == ShenandoahHeapRegion::region_size_bytes(),
 358            "Capacity should match region size");
 359 
 360     verify(r, r->bottom() <= r->top(),
 361            "Region top should not be less than bottom");
 362 
 363     verify(r, r->bottom() <= _heap->marking_context()->top_at_mark_start(r),
 364            "Region TAMS should not be less than bottom");
 365 
 366     verify(r, _heap->marking_context()->top_at_mark_start(r) <= r->top(),
 367            "Complete TAMS should not be larger than top");
 368 
 369     verify(r, r->get_live_data_bytes() <= r->capacity(),
 370            "Live data cannot be larger than capacity");
 371 
 372     verify(r, r->garbage() <= r->capacity(),
 373            "Garbage cannot be larger than capacity");
 374 
 375     verify(r, r->used() <= r->capacity(),
 376            "Used cannot be larger than capacity");
 377 
 378     verify(r, r->get_shared_allocs() <= r->capacity(),
 379            "Shared alloc count should not be larger than capacity");
 380 
 381     verify(r, r->get_tlab_allocs() <= r->capacity(),
 382            "TLAB alloc count should not be larger than capacity");
 383 
 384     verify(r, r->get_gclab_allocs() <= r->capacity(),
 385            "GCLAB alloc count should not be larger than capacity");
 386 
 387     verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() == r->used(),
 388            "Accurate accounting: shared + TLAB + GCLAB = used");
 389 
 390     verify(r, !r->is_empty() || !r->has_live(),
 391            "Empty regions should not have live data");
 392 
 393     verify(r, r->is_cset() == _heap->collection_set()->is_in(r),
 394            "Transitional: region flags and collection set agree");
 395 
 396     verify(r, r->is_empty() || r->seqnum_first_alloc() != 0,
 397            "Non-empty regions should have first seqnum set");
 398 
 399     verify(r, r->is_empty() || (r->seqnum_first_alloc_mutator() != 0 || r->seqnum_first_alloc_gc() != 0),
 400            "Non-empty regions should have first seqnum set to either GC or mutator");
 401 
 402     verify(r, r->is_empty() || r->seqnum_last_alloc() != 0,
 403            "Non-empty regions should have last seqnum set");
 404 
 405     verify(r, r->is_empty() || (r->seqnum_last_alloc_mutator() != 0 || r->seqnum_last_alloc_gc() != 0),
 406            "Non-empty regions should have last seqnum set to either GC or mutator");
 407 
 408     verify(r, r->seqnum_first_alloc() <= r->seqnum_last_alloc(),
 409            "First seqnum should not be greater than last timestamp");
 410 
 411     verify(r, r->seqnum_first_alloc_mutator() <= r->seqnum_last_alloc_mutator(),
 412            "First mutator seqnum should not be greater than last seqnum");
 413 
 414     verify(r, r->seqnum_first_alloc_gc() <= r->seqnum_last_alloc_gc(),
 415            "First GC seqnum should not be greater than last seqnum");
 416   }
 417 };
 418 
 419 class ShenandoahVerifierReachableTask : public AbstractGangTask {
 420 private:
 421   const char* _label;
 422   ShenandoahRootVerifier* _verifier;
 423   ShenandoahVerifier::VerifyOptions _options;
 424   ShenandoahHeap* _heap;
 425   ShenandoahLivenessData* _ld;
 426   MarkBitMap* _bitmap;
 427   volatile size_t _processed;
 428 
 429 public:
 430   ShenandoahVerifierReachableTask(MarkBitMap* bitmap,
 431                                   ShenandoahLivenessData* ld,
 432                                   ShenandoahRootVerifier* verifier,
 433                                   const char* label,
 434                                   ShenandoahVerifier::VerifyOptions options) :
 435     AbstractGangTask("Shenandoah Parallel Verifier Reachable Task"),
 436     _label(label),
 437     _verifier(verifier),
 438     _options(options),
 439     _heap(ShenandoahHeap::heap()),
 440     _ld(ld),
 441     _bitmap(bitmap),
 442     _processed(0) {};
 443 
 444   size_t processed() {
 445     return _processed;
 446   }
 447 
 448   virtual void work(uint worker_id) {
 449     ResourceMark rm;
 450     ShenandoahVerifierStack stack;
 451 
 452     // On level 2, we need to only check the roots once.
 453     // On level 3, we want to check the roots, and seed the local stack.
 454     // It is a lesser evil to accept multiple root scans at level 3, because
 455     // extended parallelism would buy us out.
 456     if (((ShenandoahVerifyLevel == 2) && (worker_id == 0))
 457         || (ShenandoahVerifyLevel >= 3)) {
 458         ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
 459                                       ShenandoahMessageBuffer("%s, Roots", _label),
 460                                       _options);
 461         if (_heap->unload_classes()) {
 462           _verifier->strong_roots_do(&cl);
 463         } else {
 464           _verifier->roots_do(&cl);
 465         }
 466     }
 467 
 468     size_t processed = 0;
 469 
 470     if (ShenandoahVerifyLevel >= 3) {
 471       ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
 472                                     ShenandoahMessageBuffer("%s, Reachable", _label),
 473                                     _options);
 474       while (!stack.is_empty()) {
 475         processed++;
 476         ShenandoahVerifierTask task = stack.pop();
 477         cl.verify_oops_from(task.obj());
 478       }
 479     }
 480 
 481     Atomic::add(processed, &_processed);
 482   }
 483 };
 484 
 485 class ShenandoahVerifierMarkedRegionTask : public AbstractGangTask {
 486 private:
 487   const char* _label;
 488   ShenandoahVerifier::VerifyOptions _options;
 489   ShenandoahHeap *_heap;
 490   MarkBitMap* _bitmap;
 491   ShenandoahLivenessData* _ld;
 492   volatile size_t _claimed;
 493   volatile size_t _processed;
 494 
 495 public:
 496   ShenandoahVerifierMarkedRegionTask(MarkBitMap* bitmap,
 497                                      ShenandoahLivenessData* ld,
 498                                      const char* label,
 499                                      ShenandoahVerifier::VerifyOptions options) :
 500           AbstractGangTask("Shenandoah Parallel Verifier Marked Region"),
 501           _label(label),
 502           _options(options),
 503           _heap(ShenandoahHeap::heap()),
 504           _bitmap(bitmap),
 505           _ld(ld),
 506           _claimed(0),
 507           _processed(0) {};
 508 
 509   size_t processed() {
 510     return _processed;
 511   }
 512 
 513   virtual void work(uint worker_id) {
 514     ShenandoahVerifierStack stack;
 515     ShenandoahVerifyOopClosure cl(&stack, _bitmap, _ld,
 516                                   ShenandoahMessageBuffer("%s, Marked", _label),
 517                                   _options);
 518 
 519     while (true) {
 520       size_t v = Atomic::add(1u, &_claimed) - 1;
 521       if (v < _heap->num_regions()) {
 522         ShenandoahHeapRegion* r = _heap->get_region(v);
 523         if (!r->is_humongous() && !r->is_trash()) {
 524           work_regular(r, stack, cl);
 525         } else if (r->is_humongous_start()) {
 526           work_humongous(r, stack, cl);
 527         }
 528       } else {
 529         break;
 530       }
 531     }
 532   }
 533 
 534   virtual void work_humongous(ShenandoahHeapRegion *r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {
 535     size_t processed = 0;
 536     HeapWord* obj = r->bottom();
 537     if (_heap->complete_marking_context()->is_marked((oop)obj)) {
 538       verify_and_follow(obj, stack, cl, &processed);
 539     }
 540     Atomic::add(processed, &_processed);
 541   }
 542 
 543   virtual void work_regular(ShenandoahHeapRegion *r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {
 544     size_t processed = 0;
 545     MarkBitMap* mark_bit_map = _heap->complete_marking_context()->mark_bit_map();
 546     HeapWord* tams = _heap->complete_marking_context()->top_at_mark_start(r);
 547 
 548     // Bitmaps, before TAMS
 549     if (tams > r->bottom()) {
 550       HeapWord* start = r->bottom();
 551       HeapWord* addr = mark_bit_map->get_next_marked_addr(start, tams);
 552 
 553       while (addr < tams) {
 554         verify_and_follow(addr, stack, cl, &processed);
 555         addr += 1;
 556         if (addr < tams) {
 557           addr = mark_bit_map->get_next_marked_addr(addr, tams);
 558         }
 559       }
 560     }
 561 
 562     // Size-based, after TAMS
 563     {
 564       HeapWord* limit = r->top();
 565       HeapWord* addr = tams;
 566 
 567       while (addr < limit) {
 568         verify_and_follow(addr, stack, cl, &processed);
 569         addr += oop(addr)->size();
 570       }
 571     }
 572 
 573     Atomic::add(processed, &_processed);
 574   }
 575 
 576   void verify_and_follow(HeapWord *addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t *processed) {
 577     if (!_bitmap->par_mark(addr)) return;
 578 
 579     // Verify the object itself:
 580     oop obj = oop(addr);
 581     cl.verify_oop_standalone(obj);
 582 
 583     // Verify everything reachable from that object too, hopefully realizing
 584     // everything was already marked, and never touching further:
 585     cl.verify_oops_from(obj);
 586     (*processed)++;
 587 
 588     while (!stack.is_empty()) {
 589       ShenandoahVerifierTask task = stack.pop();
 590       cl.verify_oops_from(task.obj());
 591       (*processed)++;
 592     }
 593   }
 594 };
 595 
 596 class VerifyThreadGCState : public ThreadClosure {
 597 private:
 598   const char* _label;
 599   char _expected;
 600 
 601 public:
 602   VerifyThreadGCState(const char* label, char expected) : _expected(expected) {}
 603   void do_thread(Thread* t) {
 604     char actual = ShenandoahThreadLocalData::gc_state(t);
 605     if (actual != _expected) {
 606       fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);
 607     }
 608   }
 609 };
 610 
 611 class ShenandoahGCStateResetter : public StackObj {
 612 private:
 613   ShenandoahHeap* const _heap;
 614   char _gc_state;
 615 
 616 public:
 617   ShenandoahGCStateResetter() : _heap(ShenandoahHeap::heap()) {
 618     _gc_state = _heap->gc_state();
 619     _heap->_gc_state.clear();
 620   }
 621 
 622   ~ShenandoahGCStateResetter() {
 623     _heap->_gc_state.set(_gc_state);
 624     assert(_heap->gc_state() == _gc_state, "Should be restored");
 625   }
 626 };
 627 
 628 void ShenandoahVerifier::verify_at_safepoint(const char *label,
 629                                              VerifyForwarded forwarded, VerifyMarked marked,
 630                                              VerifyCollectionSet cset,
 631                                              VerifyLiveness liveness, VerifyRegions regions,
 632                                              VerifyGCState gcstate) {
 633   guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");
 634   guarantee(ShenandoahVerify, "only when enabled, and bitmap is initialized in ShenandoahHeap::initialize");
 635 
 636   // Avoid side-effect of changing workers' active thread count, but bypass concurrent/parallel protocol check
 637   ShenandoahPushWorkerScope verify_worker_scope(_heap->workers(), _heap->max_workers(), false /*bypass check*/);
 638 
 639   log_info(gc,start)("Verify %s, Level " INTX_FORMAT, label, ShenandoahVerifyLevel);
 640 
 641   // GC state checks
 642   {
 643     char expected = -1;
 644     bool enabled;
 645     switch (gcstate) {
 646       case _verify_gcstate_disable:
 647         enabled = false;
 648         break;
 649       case _verify_gcstate_forwarded:
 650         enabled = true;
 651         expected = ShenandoahHeap::HAS_FORWARDED;
 652         break;
 653       case _verify_gcstate_evacuation:
 654         enabled = true;
 655         expected = ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::EVACUATION;
 656         break;
 657       case _verify_gcstate_stable:
 658         enabled = true;
 659         expected = ShenandoahHeap::STABLE;
 660         break;
 661       default:
 662         enabled = false;
 663         assert(false, "Unhandled gc-state verification");
 664     }
 665 
 666     if (enabled) {
 667       char actual = _heap->gc_state();
 668       if (actual != expected) {
 669         fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);
 670       }
 671 
 672       VerifyThreadGCState vtgcs(label, expected);
 673       Threads::java_threads_do(&vtgcs);
 674     }
 675   }
 676 
 677   // Deactivate barriers temporarily: Verifier wants plain heap accesses
 678   ShenandoahGCStateResetter resetter;
 679 
 680   // Heap size checks
 681   {
 682     ShenandoahHeapLocker lock(_heap->lock());
 683 
 684     ShenandoahCalculateRegionStatsClosure cl;
 685     _heap->heap_region_iterate(&cl);
 686     size_t heap_used = _heap->used();
 687     guarantee(cl.used() == heap_used,
 688               "%s: heap used size must be consistent: heap-used = " SIZE_FORMAT "K, regions-used = " SIZE_FORMAT "K",
 689               label, heap_used/K, cl.used()/K);
 690 
 691     size_t heap_committed = _heap->committed();
 692     guarantee(cl.committed() == heap_committed,
 693               "%s: heap committed size must be consistent: heap-committed = " SIZE_FORMAT "K, regions-committed = " SIZE_FORMAT "K",
 694               label, heap_committed/K, cl.committed()/K);
 695   }
 696 
 697   // Internal heap region checks
 698   if (ShenandoahVerifyLevel >= 1) {
 699     ShenandoahVerifyHeapRegionClosure cl(label, regions);
 700     _heap->heap_region_iterate(&cl);
 701   }
 702 
 703   OrderAccess::fence();
 704   _heap->make_parsable(false);
 705 
 706   // Allocate temporary bitmap for storing marking wavefront:
 707   _verification_bit_map->clear();
 708 
 709   // Allocate temporary array for storing liveness data
 710   ShenandoahLivenessData* ld = NEW_C_HEAP_ARRAY(ShenandoahLivenessData, _heap->num_regions(), mtGC);
 711   Copy::fill_to_bytes((void*)ld, _heap->num_regions()*sizeof(ShenandoahLivenessData), 0);
 712 
 713   const VerifyOptions& options = ShenandoahVerifier::VerifyOptions(forwarded, marked, cset, liveness, regions, gcstate);
 714 
 715   // Steps 1-2. Scan root set to get initial reachable set. Finish walking the reachable heap.
 716   // This verifies what application can see, since it only cares about reachable objects.
 717   size_t count_reachable = 0;
 718   if (ShenandoahVerifyLevel >= 2) {
 719     ShenandoahRootVerifier verifier;
 720 
 721     ShenandoahVerifierReachableTask task(_verification_bit_map, ld, &verifier, label, options);
 722     _heap->workers()->run_task(&task);
 723     count_reachable = task.processed();
 724   }
 725 
 726   // Step 3. Walk marked objects. Marked objects might be unreachable. This verifies what collector,
 727   // not the application, can see during the region scans. There is no reason to process the objects
 728   // that were already verified, e.g. those marked in verification bitmap. There is interaction with TAMS:
 729   // before TAMS, we verify the bitmaps, if available; after TAMS, we walk until the top(). It mimics
 730   // what marked_object_iterate is doing, without calling into that optimized (and possibly incorrect)
 731   // version
 732 
 733   size_t count_marked = 0;
 734   if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete) {
 735     guarantee(_heap->marking_context()->is_complete(), "Marking context should be complete");
 736     ShenandoahVerifierMarkedRegionTask task(_verification_bit_map, ld, label, options);
 737     _heap->workers()->run_task(&task);
 738     count_marked = task.processed();
 739   } else {
 740     guarantee(ShenandoahVerifyLevel < 4 || marked == _verify_marked_incomplete || marked == _verify_marked_disable, "Should be");
 741   }
 742 
 743   // Step 4. Verify accumulated liveness data, if needed. Only reliable if verification level includes
 744   // marked objects.
 745 
 746   if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete && liveness == _verify_liveness_complete) {
 747     for (size_t i = 0; i < _heap->num_regions(); i++) {
 748       ShenandoahHeapRegion* r = _heap->get_region(i);
 749 
 750       juint verf_live = 0;
 751       if (r->is_humongous()) {
 752         // For humongous objects, test if start region is marked live, and if so,
 753         // all humongous regions in that chain have live data equal to their "used".
 754         juint start_live = OrderAccess::load_acquire(&ld[r->humongous_start_region()->region_number()]);
 755         if (start_live > 0) {
 756           verf_live = (juint)(r->used() / HeapWordSize);
 757         }
 758       } else {
 759         verf_live = OrderAccess::load_acquire(&ld[r->region_number()]);
 760       }
 761 
 762       size_t reg_live = r->get_live_data_words();
 763       if (reg_live != verf_live) {
 764         ResourceMark rm;
 765         stringStream ss;
 766         r->print_on(&ss);
 767         fatal("%s: Live data should match: region-live = " SIZE_FORMAT ", verifier-live = " UINT32_FORMAT "\n%s",
 768               label, reg_live, verf_live, ss.as_string());
 769       }
 770     }
 771   }
 772 
 773   log_info(gc)("Verify %s, Level " INTX_FORMAT " (" SIZE_FORMAT " reachable, " SIZE_FORMAT " marked)",
 774                label, ShenandoahVerifyLevel, count_reachable, count_marked);
 775 
 776   FREE_C_HEAP_ARRAY(ShenandoahLivenessData, ld);
 777 }
 778 
 779 void ShenandoahVerifier::verify_generic(VerifyOption vo) {
 780   verify_at_safepoint(
 781           "Generic Verification",
 782           _verify_forwarded_allow,     // conservatively allow forwarded
 783           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 784           _verify_cset_disable,        // cset may be inconsistent
 785           _verify_liveness_disable,    // no reliable liveness data
 786           _verify_regions_disable,     // no reliable region data
 787           _verify_gcstate_disable      // no data about gcstate
 788   );
 789 }
 790 
 791 void ShenandoahVerifier::verify_before_concmark() {
 792   if (_heap->has_forwarded_objects()) {
 793     verify_at_safepoint(
 794             "Before Mark",
 795             _verify_forwarded_allow,     // may have forwarded references
 796             _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 797             _verify_cset_forwarded,      // allow forwarded references to cset
 798             _verify_liveness_disable,    // no reliable liveness data
 799             _verify_regions_notrash,     // no trash regions
 800             _verify_gcstate_forwarded    // there are forwarded objects
 801     );
 802   } else {
 803     verify_at_safepoint(
 804             "Before Mark",
 805             _verify_forwarded_none,      // UR should have fixed up
 806             _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 807             _verify_cset_none,           // UR should have fixed this
 808             _verify_liveness_disable,    // no reliable liveness data
 809             _verify_regions_notrash,     // no trash regions
 810             _verify_gcstate_stable       // there are no forwarded objects
 811     );
 812   }
 813 }
 814 
 815 void ShenandoahVerifier::verify_after_concmark() {
 816   verify_at_safepoint(
 817           "After Mark",
 818           _verify_forwarded_none,      // no forwarded references
 819           _verify_marked_complete,     // bitmaps as precise as we can get
 820           _verify_cset_none,           // no references to cset anymore
 821           _verify_liveness_complete,   // liveness data must be complete here
 822           _verify_regions_disable,     // trash regions not yet recycled
 823           _verify_gcstate_stable       // mark should have stabilized the heap
 824   );
 825 }
 826 
 827 void ShenandoahVerifier::verify_before_evacuation() {
 828   verify_at_safepoint(
 829           "Before Evacuation",
 830           _verify_forwarded_none,    // no forwarded references
 831           _verify_marked_complete,   // walk over marked objects too
 832           _verify_cset_disable,      // non-forwarded references to cset expected
 833           _verify_liveness_complete, // liveness data must be complete here
 834           _verify_regions_disable,   // trash regions not yet recycled
 835           _verify_gcstate_stable     // mark should have stabilized the heap
 836   );
 837 }
 838 
 839 void ShenandoahVerifier::verify_during_evacuation() {
 840   verify_at_safepoint(
 841           "During Evacuation",
 842           _verify_forwarded_allow,   // some forwarded references are allowed
 843           _verify_marked_disable,    // walk only roots
 844           _verify_cset_disable,      // some cset references are not forwarded yet
 845           _verify_liveness_disable,  // liveness data might be already stale after pre-evacs
 846           _verify_regions_disable,   // trash regions not yet recycled
 847           _verify_gcstate_evacuation // evacuation is in progress
 848   );
 849 }
 850 
 851 void ShenandoahVerifier::verify_after_evacuation() {
 852   verify_at_safepoint(
 853           "After Evacuation",
 854           _verify_forwarded_allow,     // objects are still forwarded
 855           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
 856           _verify_cset_forwarded,      // all cset refs are fully forwarded
 857           _verify_liveness_disable,    // no reliable liveness data anymore
 858           _verify_regions_notrash,     // trash regions have been recycled already
 859           _verify_gcstate_forwarded    // evacuation produced some forwarded objects
 860   );
 861 }
 862 
 863 void ShenandoahVerifier::verify_before_updaterefs() {
 864   verify_at_safepoint(
 865           "Before Updating References",
 866           _verify_forwarded_allow,     // forwarded references allowed
 867           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
 868           _verify_cset_forwarded,      // all cset refs are fully forwarded
 869           _verify_liveness_disable,    // no reliable liveness data anymore
 870           _verify_regions_notrash,     // trash regions have been recycled already
 871           _verify_gcstate_forwarded    // evacuation should have produced some forwarded objects
 872   );
 873 }
 874 
 875 void ShenandoahVerifier::verify_after_updaterefs() {
 876   verify_at_safepoint(
 877           "After Updating References",
 878           _verify_forwarded_none,      // no forwarded references
 879           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
 880           _verify_cset_none,           // no cset references, all updated
 881           _verify_liveness_disable,    // no reliable liveness data anymore
 882           _verify_regions_nocset,      // no cset regions, trash regions have appeared
 883           _verify_gcstate_stable       // update refs had cleaned up forwarded objects
 884   );
 885 }
 886 
 887 void ShenandoahVerifier::verify_after_degenerated() {
 888   verify_at_safepoint(
 889           "After Degenerated GC",
 890           _verify_forwarded_none,      // all objects are non-forwarded
 891           _verify_marked_complete,     // all objects are marked in complete bitmap
 892           _verify_cset_none,           // no cset references
 893           _verify_liveness_disable,    // no reliable liveness data anymore
 894           _verify_regions_notrash_nocset, // no trash, no cset
 895           _verify_gcstate_stable       // degenerated refs had cleaned up forwarded objects
 896   );
 897 }
 898 
 899 void ShenandoahVerifier::verify_before_traversal() {
 900   verify_at_safepoint(
 901           "Before Traversal",
 902           _verify_forwarded_none,      // cannot have forwarded objects
 903           _verify_marked_disable,      // bitmaps are not relevant before traversal
 904           _verify_cset_none,           // no cset references before traversal
 905           _verify_liveness_disable,    // no reliable liveness data anymore
 906           _verify_regions_notrash_nocset, // no trash and no cset regions
 907           _verify_gcstate_stable       // nothing forwarded before traversal
 908   );
 909 }
 910 
 911 void ShenandoahVerifier::verify_after_traversal() {
 912   verify_at_safepoint(
 913           "After Traversal",
 914           _verify_forwarded_none,      // cannot have forwarded objects
 915           _verify_marked_complete,     // should have complete marking after traversal
 916           _verify_cset_none,           // no cset references left after traversal
 917           _verify_liveness_disable,    // liveness data is not collected for new allocations
 918           _verify_regions_nocset,      // no cset regions, trash regions allowed
 919           _verify_gcstate_stable       // nothing forwarded after traversal
 920   );
 921 }
 922 
 923 void ShenandoahVerifier::verify_before_fullgc() {
 924   verify_at_safepoint(
 925           "Before Full GC",
 926           _verify_forwarded_allow,     // can have forwarded objects
 927           _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
 928           _verify_cset_disable,        // cset might be foobared
 929           _verify_liveness_disable,    // no reliable liveness data anymore
 930           _verify_regions_disable,     // no reliable region data here
 931           _verify_gcstate_disable      // no reliable gcstate data
 932   );
 933 }
 934 
 935 void ShenandoahVerifier::verify_after_fullgc() {
 936   verify_at_safepoint(
 937           "After Full GC",
 938           _verify_forwarded_none,      // all objects are non-forwarded
 939           _verify_marked_complete,     // all objects are marked in complete bitmap
 940           _verify_cset_none,           // no cset references
 941           _verify_liveness_disable,    // no reliable liveness data anymore
 942           _verify_regions_notrash_nocset, // no trash, no cset
 943           _verify_gcstate_stable       // full gc cleaned up everything
 944   );
 945 }
 946 
 947 class ShenandoahVerifyNoForwared : public OopClosure {
 948 private:
 949   template <class T>
 950   void do_oop_work(T* p) {
 951     T o = RawAccess<>::oop_load(p);
 952     if (!CompressedOops::is_null(o)) {
 953       oop obj = CompressedOops::decode_not_null(o);
 954       oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
 955       if (!oopDesc::equals_raw(obj, fwd)) {
 956         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
 957                                          "Verify Roots", "Should not be forwarded", __FILE__, __LINE__);
 958       }
 959     }
 960   }
 961 
 962 public:
 963   void do_oop(narrowOop* p) { do_oop_work(p); }
 964   void do_oop(oop* p)       { do_oop_work(p); }
 965 };
 966 
 967 class ShenandoahVerifyInToSpaceClosure : public OopClosure {
 968 private:
 969   template <class T>
 970   void do_oop_work(T* p) {
 971     T o = RawAccess<>::oop_load(p);
 972     if (!CompressedOops::is_null(o)) {
 973       oop obj = CompressedOops::decode_not_null(o);
 974       ShenandoahHeap* heap = ShenandoahHeap::heap_no_check();
 975 
 976       if (!heap->marking_context()->is_marked(obj)) {
 977         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
 978                 "Verify Roots In To-Space", "Should be marked", __FILE__, __LINE__);
 979       }
 980 
 981       if (heap->in_collection_set(obj)) {
 982         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
 983                 "Verify Roots In To-Space", "Should not be in collection set", __FILE__, __LINE__);
 984       }
 985 
 986       oop fwd = (oop) ShenandoahForwarding::get_forwardee_raw_unchecked(obj);
 987       if (!oopDesc::equals_raw(obj, fwd)) {
 988         ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
 989                 "Verify Roots In To-Space", "Should not be forwarded", __FILE__, __LINE__);
 990       }
 991     }
 992   }
 993 
 994 public:
 995   void do_oop(narrowOop* p) { do_oop_work(p); }
 996   void do_oop(oop* p)       { do_oop_work(p); }
 997 };
 998 
 999 void ShenandoahVerifier::verify_roots_in_to_space() {
1000   ShenandoahRootVerifier verifier;
1001   ShenandoahVerifyInToSpaceClosure cl;
1002   verifier.oops_do(&cl);
1003 }
1004 
1005 void ShenandoahVerifier::verify_roots_no_forwarded() {
1006   ShenandoahRootVerifier verifier;
1007   ShenandoahVerifyNoForwared cl;
1008   verifier.oops_do(&cl);
1009 }
1010 
1011 void ShenandoahVerifier::verify_roots_no_forwarded_except(ShenandoahRootVerifier::RootTypes types) {
1012   ShenandoahRootVerifier verifier;
1013   verifier.excludes(types);
1014   ShenandoahVerifyNoForwared cl;
1015   verifier.oops_do(&cl);
1016 }