1 /*
   2  * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/g1/g1Allocator.inline.hpp"
  27 #include "gc/g1/g1CollectedHeap.hpp"
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1ConcurrentMarkThread.hpp"
  30 #include "gc/g1/g1HeapVerifier.hpp"
  31 #include "gc/g1/g1Policy.hpp"
  32 #include "gc/g1/g1RemSet.hpp"
  33 #include "gc/g1/g1RootProcessor.hpp"
  34 #include "gc/g1/heapRegion.hpp"
  35 #include "gc/g1/heapRegion.inline.hpp"
  36 #include "gc/g1/heapRegionRemSet.hpp"
  37 #include "gc/g1/g1StringDedup.hpp"
  38 #include "logging/log.hpp"
  39 #include "logging/logStream.hpp"
  40 #include "memory/resourceArea.hpp"
  41 #include "oops/access.inline.hpp"
  42 #include "oops/compressedOops.inline.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "runtime/handles.inline.hpp"
  45 
  46 int G1HeapVerifier::_enabled_verification_types = G1HeapVerifier::G1VerifyAll;
  47 
  48 class VerifyRootsClosure: public OopClosure {
  49 private:
  50   G1CollectedHeap* _g1h;
  51   VerifyOption     _vo;
  52   bool             _failures;
  53 public:
  54   // _vo == UsePrevMarking -> use "prev" marking information,
  55   // _vo == UseNextMarking -> use "next" marking information,
  56   // _vo == UseFullMarking -> use "next" marking bitmap but no TAMS
  57   VerifyRootsClosure(VerifyOption vo) :
  58     _g1h(G1CollectedHeap::heap()),
  59     _vo(vo),
  60     _failures(false) { }
  61 
  62   bool failures() { return _failures; }
  63 
  64   template <class T> void do_oop_nv(T* p) {
  65     T heap_oop = RawAccess<>::oop_load(p);
  66     if (!CompressedOops::is_null(heap_oop)) {
  67       oop obj = CompressedOops::decode_not_null(heap_oop);
  68       if (_g1h->is_obj_dead_cond(obj, _vo)) {
  69         Log(gc, verify) log;
  70         log.error("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
  71         ResourceMark rm;
  72         LogStream ls(log.error());
  73         obj->print_on(&ls);
  74         _failures = true;
  75       }
  76     }
  77   }
  78 
  79   void do_oop(oop* p)       { do_oop_nv(p); }
  80   void do_oop(narrowOop* p) { do_oop_nv(p); }
  81 };
  82 
  83 class G1VerifyCodeRootOopClosure: public OopClosure {
  84   G1CollectedHeap* _g1h;
  85   OopClosure* _root_cl;
  86   nmethod* _nm;
  87   VerifyOption _vo;
  88   bool _failures;
  89 
  90   template <class T> void do_oop_work(T* p) {
  91     // First verify that this root is live
  92     _root_cl->do_oop(p);
  93 
  94     if (!G1VerifyHeapRegionCodeRoots) {
  95       // We're not verifying the code roots attached to heap region.
  96       return;
  97     }
  98 
  99     // Don't check the code roots during marking verification in a full GC
 100     if (_vo == VerifyOption_G1UseFullMarking) {
 101       return;
 102     }
 103 
 104     // Now verify that the current nmethod (which contains p) is
 105     // in the code root list of the heap region containing the
 106     // object referenced by p.
 107 
 108     T heap_oop = RawAccess<>::oop_load(p);
 109     if (!CompressedOops::is_null(heap_oop)) {
 110       oop obj = CompressedOops::decode_not_null(heap_oop);
 111 
 112       // Now fetch the region containing the object
 113       HeapRegion* hr = _g1h->heap_region_containing(obj);
 114       HeapRegionRemSet* hrrs = hr->rem_set();
 115       // Verify that the strong code root list for this region
 116       // contains the nmethod
 117       if (!hrrs->strong_code_roots_list_contains(_nm)) {
 118         log_error(gc, verify)("Code root location " PTR_FORMAT " "
 119                               "from nmethod " PTR_FORMAT " not in strong "
 120                               "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
 121                               p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
 122         _failures = true;
 123       }
 124     }
 125   }
 126 
 127 public:
 128   G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
 129     _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
 130 
 131   void do_oop(oop* p) { do_oop_work(p); }
 132   void do_oop(narrowOop* p) { do_oop_work(p); }
 133 
 134   void set_nmethod(nmethod* nm) { _nm = nm; }
 135   bool failures() { return _failures; }
 136 };
 137 
 138 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
 139   G1VerifyCodeRootOopClosure* _oop_cl;
 140 
 141 public:
 142   G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
 143     _oop_cl(oop_cl) {}
 144 
 145   void do_code_blob(CodeBlob* cb) {
 146     nmethod* nm = cb->as_nmethod_or_null();
 147     if (nm != NULL) {
 148       _oop_cl->set_nmethod(nm);
 149       nm->oops_do(_oop_cl);
 150     }
 151   }
 152 };
 153 
 154 class YoungRefCounterClosure : public OopClosure {
 155   G1CollectedHeap* _g1h;
 156   int              _count;
 157  public:
 158   YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
 159   void do_oop(oop* p)       { if (_g1h->is_in_young(*p)) { _count++; } }
 160   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 161 
 162   int count() { return _count; }
 163   void reset_count() { _count = 0; };
 164 };
 165 
 166 class VerifyCLDClosure: public CLDClosure {
 167   YoungRefCounterClosure _young_ref_counter_closure;
 168   OopClosure *_oop_closure;
 169  public:
 170   VerifyCLDClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
 171   void do_cld(ClassLoaderData* cld) {
 172     cld->oops_do(_oop_closure, false);
 173 
 174     _young_ref_counter_closure.reset_count();
 175     cld->oops_do(&_young_ref_counter_closure, false);
 176     if (_young_ref_counter_closure.count() > 0) {
 177       guarantee(cld->has_modified_oops(), "CLD " PTR_FORMAT ", has young %d refs but is not dirty.", p2i(cld), _young_ref_counter_closure.count());
 178     }
 179   }
 180 };
 181 
 182 class VerifyLivenessOopClosure: public OopClosure {
 183   G1CollectedHeap* _g1h;
 184   VerifyOption _vo;
 185 public:
 186   VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
 187     _g1h(g1h), _vo(vo)
 188   { }
 189   void do_oop(narrowOop *p) { do_oop_work(p); }
 190   void do_oop(      oop *p) { do_oop_work(p); }
 191 
 192   template <class T> void do_oop_work(T *p) {
 193     oop obj = RawAccess<>::oop_load(p);
 194     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
 195               "Dead object referenced by a not dead object");
 196   }
 197 };
 198 
 199 class VerifyObjsInRegionClosure: public ObjectClosure {
 200 private:
 201   G1CollectedHeap* _g1h;
 202   size_t _live_bytes;
 203   HeapRegion *_hr;
 204   VerifyOption _vo;
 205 public:
 206   // _vo == UsePrevMarking -> use "prev" marking information,
 207   // _vo == UseNextMarking -> use "next" marking information,
 208   // _vo == UseFullMarking -> use "next" marking bitmap but no TAMS.
 209   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
 210     : _live_bytes(0), _hr(hr), _vo(vo) {
 211     _g1h = G1CollectedHeap::heap();
 212   }
 213   void do_object(oop o) {
 214     VerifyLivenessOopClosure isLive(_g1h, _vo);
 215     assert(o != NULL, "Huh?");
 216     if (!_g1h->is_obj_dead_cond(o, _vo)) {
 217       // If the object is alive according to the full gc mark,
 218       // then verify that the marking information agrees.
 219       // Note we can't verify the contra-positive of the
 220       // above: if the object is dead (according to the mark
 221       // word), it may not be marked, or may have been marked
 222       // but has since became dead, or may have been allocated
 223       // since the last marking.
 224       if (_vo == VerifyOption_G1UseFullMarking) {
 225         guarantee(!_g1h->is_obj_dead(o), "Full GC marking and concurrent mark mismatch");
 226       }
 227 
 228       o->oop_iterate_no_header(&isLive);
 229       if (!_hr->obj_allocated_since_prev_marking(o)) {
 230         size_t obj_size = o->size();    // Make sure we don't overflow
 231         _live_bytes += (obj_size * HeapWordSize);
 232       }
 233     }
 234   }
 235   size_t live_bytes() { return _live_bytes; }
 236 };
 237 
 238 class VerifyArchiveOopClosure: public OopClosure {
 239   HeapRegion* _hr;
 240 public:
 241   VerifyArchiveOopClosure(HeapRegion *hr)
 242     : _hr(hr) { }
 243   void do_oop(narrowOop *p) { do_oop_work(p); }
 244   void do_oop(      oop *p) { do_oop_work(p); }
 245 
 246   template <class T> void do_oop_work(T *p) {
 247     oop obj = RawAccess<>::oop_load(p);
 248 
 249     if (_hr->is_open_archive()) {
 250       guarantee(obj == NULL || G1ArchiveAllocator::is_archive_object(obj),
 251                 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
 252                 p2i(p), p2i(obj));
 253     } else {
 254       assert(_hr->is_closed_archive(), "should be closed archive region");
 255       guarantee(obj == NULL || G1ArchiveAllocator::is_closed_archive_object(obj),
 256                 "Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
 257                 p2i(p), p2i(obj));
 258     }
 259   }
 260 };
 261 
 262 class VerifyObjectInArchiveRegionClosure: public ObjectClosure {
 263   HeapRegion* _hr;
 264 public:
 265   VerifyObjectInArchiveRegionClosure(HeapRegion *hr, bool verbose)
 266     : _hr(hr) { }
 267   // Verify that all object pointers are to archive regions.
 268   void do_object(oop o) {
 269     VerifyArchiveOopClosure checkOop(_hr);
 270     assert(o != NULL, "Should not be here for NULL oops");
 271     o->oop_iterate_no_header(&checkOop);
 272   }
 273 };
 274 
 275 // Should be only used at CDS dump time
 276 class VerifyArchivePointerRegionClosure: public HeapRegionClosure {
 277 private:
 278   G1CollectedHeap* _g1h;
 279 public:
 280   VerifyArchivePointerRegionClosure(G1CollectedHeap* g1h) { }
 281   virtual bool do_heap_region(HeapRegion* r) {
 282    if (r->is_archive()) {
 283       VerifyObjectInArchiveRegionClosure verify_oop_pointers(r, false);
 284       r->object_iterate(&verify_oop_pointers);
 285     }
 286     return false;
 287   }
 288 };
 289 
 290 void G1HeapVerifier::verify_archive_regions() {
 291   G1CollectedHeap*  g1h = G1CollectedHeap::heap();
 292   VerifyArchivePointerRegionClosure cl(NULL);
 293   g1h->heap_region_iterate(&cl);
 294 }
 295 
 296 class VerifyRegionClosure: public HeapRegionClosure {
 297 private:
 298   bool             _par;
 299   VerifyOption     _vo;
 300   bool             _failures;
 301 public:
 302   // _vo == UsePrevMarking -> use "prev" marking information,
 303   // _vo == UseNextMarking -> use "next" marking information,
 304   // _vo == UseFullMarking -> use "next" marking bitmap but no TAMS
 305   VerifyRegionClosure(bool par, VerifyOption vo)
 306     : _par(par),
 307       _vo(vo),
 308       _failures(false) {}
 309 
 310   bool failures() {
 311     return _failures;
 312   }
 313 
 314   bool do_heap_region(HeapRegion* r) {
 315     guarantee(!r->is_young() || r->rem_set()->is_complete(), "Remembered set for Young region %u must be complete, is %s", r->hrm_index(), r->rem_set()->get_state_str());
 316     // Humongous and old regions regions might be of any state, so can't check here.
 317     guarantee(!r->is_free() || !r->rem_set()->is_tracked(), "Remembered set for free region %u must be untracked, is %s", r->hrm_index(), r->rem_set()->get_state_str());
 318     // Verify that the continues humongous regions' remembered set state matches the
 319     // one from the starts humongous region.
 320     if (r->is_continues_humongous()) {
 321       if (r->rem_set()->get_state_str() != r->humongous_start_region()->rem_set()->get_state_str()) {
 322          log_error(gc, verify)("Remset states differ: Region %u (%s) remset %s with starts region %u (%s) remset %s",
 323                                r->hrm_index(),
 324                                r->get_short_type_str(),
 325                                r->rem_set()->get_state_str(),
 326                                r->humongous_start_region()->hrm_index(),
 327                                r->humongous_start_region()->get_short_type_str(),
 328                                r->humongous_start_region()->rem_set()->get_state_str());
 329          _failures = true;
 330       }
 331     }
 332     // For archive regions, verify there are no heap pointers to
 333     // non-pinned regions. For all others, verify liveness info.
 334     if (r->is_closed_archive()) {
 335       VerifyObjectInArchiveRegionClosure verify_oop_pointers(r, false);
 336       r->object_iterate(&verify_oop_pointers);
 337       return true;
 338     } else if (r->is_open_archive()) {
 339       VerifyObjsInRegionClosure verify_open_archive_oop(r, _vo);
 340       r->object_iterate(&verify_open_archive_oop);
 341       return true;
 342     } else if (!r->is_continues_humongous()) {
 343       bool failures = false;
 344       r->verify(_vo, &failures);
 345       if (failures) {
 346         _failures = true;
 347       } else if (!r->is_starts_humongous()) {
 348         VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
 349         r->object_iterate(&not_dead_yet_cl);
 350         if (_vo != VerifyOption_G1UseNextMarking) {
 351           if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
 352             log_error(gc, verify)("[" PTR_FORMAT "," PTR_FORMAT "] max_live_bytes " SIZE_FORMAT " < calculated " SIZE_FORMAT,
 353                                   p2i(r->bottom()), p2i(r->end()), r->max_live_bytes(), not_dead_yet_cl.live_bytes());
 354             _failures = true;
 355           }
 356         } else {
 357           // When vo == UseNextMarking we cannot currently do a sanity
 358           // check on the live bytes as the calculation has not been
 359           // finalized yet.
 360         }
 361       }
 362     }
 363     return false; // stop the region iteration if we hit a failure
 364   }
 365 };
 366 
 367 // This is the task used for parallel verification of the heap regions
 368 
 369 class G1ParVerifyTask: public AbstractGangTask {
 370 private:
 371   G1CollectedHeap*  _g1h;
 372   VerifyOption      _vo;
 373   bool              _failures;
 374   HeapRegionClaimer _hrclaimer;
 375 
 376 public:
 377   // _vo == UsePrevMarking -> use "prev" marking information,
 378   // _vo == UseNextMarking -> use "next" marking information,
 379   // _vo == UseFullMarking -> use "next" marking bitmap but no TAMS
 380   G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
 381       AbstractGangTask("Parallel verify task"),
 382       _g1h(g1h),
 383       _vo(vo),
 384       _failures(false),
 385       _hrclaimer(g1h->workers()->active_workers()) {}
 386 
 387   bool failures() {
 388     return _failures;
 389   }
 390 
 391   void work(uint worker_id) {
 392     HandleMark hm;
 393     VerifyRegionClosure blk(true, _vo);
 394     _g1h->heap_region_par_iterate_from_worker_offset(&blk, &_hrclaimer, worker_id);
 395     if (blk.failures()) {
 396       _failures = true;
 397     }
 398   }
 399 };
 400 
 401 void G1HeapVerifier::enable_verification_type(G1VerifyType type) {
 402   // First enable will clear _enabled_verification_types.
 403   if (_enabled_verification_types == G1VerifyAll) {
 404     _enabled_verification_types = type;
 405   } else {
 406     _enabled_verification_types |= type;
 407   }
 408 }
 409 
 410 bool G1HeapVerifier::should_verify(G1VerifyType type) {
 411   return (_enabled_verification_types & type) == type;
 412 }
 413 
 414 void G1HeapVerifier::verify(VerifyOption vo) {
 415   if (!SafepointSynchronize::is_at_safepoint()) {
 416     log_info(gc, verify)("Skipping verification. Not at safepoint.");
 417   }
 418 
 419   assert(Thread::current()->is_VM_thread(),
 420          "Expected to be executed serially by the VM thread at this point");
 421 
 422   log_debug(gc, verify)("Roots");
 423   VerifyRootsClosure rootsCl(vo);
 424   VerifyCLDClosure cldCl(_g1h, &rootsCl);
 425 
 426   // We apply the relevant closures to all the oops in the
 427   // system dictionary, class loader data graph, the string table
 428   // and the nmethods in the code cache.
 429   G1VerifyCodeRootOopClosure codeRootsCl(_g1h, &rootsCl, vo);
 430   G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
 431 
 432   {
 433     G1RootProcessor root_processor(_g1h, 1);
 434     root_processor.process_all_roots(&rootsCl,
 435                                      &cldCl,
 436                                      &blobsCl);
 437   }
 438 
 439   bool failures = rootsCl.failures() || codeRootsCl.failures();
 440 
 441   if (!_g1h->g1_policy()->collector_state()->in_full_gc()) {
 442     // If we're verifying during a full GC then the region sets
 443     // will have been torn down at the start of the GC. Therefore
 444     // verifying the region sets will fail. So we only verify
 445     // the region sets when not in a full GC.
 446     log_debug(gc, verify)("HeapRegionSets");
 447     verify_region_sets();
 448   }
 449 
 450   log_debug(gc, verify)("HeapRegions");
 451   if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
 452 
 453     G1ParVerifyTask task(_g1h, vo);
 454     _g1h->workers()->run_task(&task);
 455     if (task.failures()) {
 456       failures = true;
 457     }
 458 
 459   } else {
 460     VerifyRegionClosure blk(false, vo);
 461     _g1h->heap_region_iterate(&blk);
 462     if (blk.failures()) {
 463       failures = true;
 464     }
 465   }
 466 
 467   if (G1StringDedup::is_enabled()) {
 468     log_debug(gc, verify)("StrDedup");
 469     G1StringDedup::verify();
 470   }
 471 
 472   if (failures) {
 473     log_error(gc, verify)("Heap after failed verification (kind %d):", vo);
 474     // It helps to have the per-region information in the output to
 475     // help us track down what went wrong. This is why we call
 476     // print_extended_on() instead of print_on().
 477     Log(gc, verify) log;
 478     ResourceMark rm;
 479     LogStream ls(log.error());
 480     _g1h->print_extended_on(&ls);
 481   }
 482   guarantee(!failures, "there should not have been any failures");
 483 }
 484 
 485 // Heap region set verification
 486 
 487 class VerifyRegionListsClosure : public HeapRegionClosure {
 488 private:
 489   HeapRegionSet*   _old_set;
 490   HeapRegionSet*   _humongous_set;
 491   HeapRegionManager*   _hrm;
 492 
 493 public:
 494   uint _old_count;
 495   uint _humongous_count;
 496   uint _free_count;
 497 
 498   VerifyRegionListsClosure(HeapRegionSet* old_set,
 499                            HeapRegionSet* humongous_set,
 500                            HeapRegionManager* hrm) :
 501     _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
 502     _old_count(), _humongous_count(), _free_count(){ }
 503 
 504   bool do_heap_region(HeapRegion* hr) {
 505     if (hr->is_young()) {
 506       // TODO
 507     } else if (hr->is_humongous()) {
 508       assert(hr->containing_set() == _humongous_set, "Heap region %u is humongous but not in humongous set.", hr->hrm_index());
 509       _humongous_count++;
 510     } else if (hr->is_empty()) {
 511       assert(_hrm->is_free(hr), "Heap region %u is empty but not on the free list.", hr->hrm_index());
 512       _free_count++;
 513     } else if (hr->is_old()) {
 514       assert(hr->containing_set() == _old_set, "Heap region %u is old but not in the old set.", hr->hrm_index());
 515       _old_count++;
 516     } else {
 517       // There are no other valid region types. Check for one invalid
 518       // one we can identify: pinned without old or humongous set.
 519       assert(!hr->is_pinned(), "Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index());
 520       ShouldNotReachHere();
 521     }
 522     return false;
 523   }
 524 
 525   void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
 526     guarantee(old_set->length() == _old_count, "Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count);
 527     guarantee(humongous_set->length() == _humongous_count, "Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count);
 528     guarantee(free_list->num_free_regions() == _free_count, "Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count);
 529   }
 530 };
 531 
 532 void G1HeapVerifier::verify_region_sets() {
 533   assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
 534 
 535   // First, check the explicit lists.
 536   _g1h->_hrm.verify();
 537 
 538   // Finally, make sure that the region accounting in the lists is
 539   // consistent with what we see in the heap.
 540 
 541   VerifyRegionListsClosure cl(&_g1h->_old_set, &_g1h->_humongous_set, &_g1h->_hrm);
 542   _g1h->heap_region_iterate(&cl);
 543   cl.verify_counts(&_g1h->_old_set, &_g1h->_humongous_set, &_g1h->_hrm);
 544 }
 545 
 546 void G1HeapVerifier::prepare_for_verify() {
 547   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
 548     _g1h->ensure_parsability(false);
 549   }
 550 }
 551 
 552 double G1HeapVerifier::verify(G1VerifyType type, VerifyOption vo, const char* msg) {
 553   double verify_time_ms = 0.0;
 554 
 555   if (should_verify(type) && _g1h->total_collections() >= VerifyGCStartAt) {
 556     double verify_start = os::elapsedTime();
 557     HandleMark hm;  // Discard invalid handles created during verification
 558     prepare_for_verify();
 559     Universe::verify(vo, msg);
 560     verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
 561   }
 562 
 563   return verify_time_ms;
 564 }
 565 
 566 void G1HeapVerifier::verify_before_gc(G1VerifyType type) {
 567   if (VerifyBeforeGC) {
 568     double verify_time_ms = verify(type, VerifyOption_G1UsePrevMarking, "Before GC");
 569     _g1h->g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
 570   }
 571 }
 572 
 573 void G1HeapVerifier::verify_after_gc(G1VerifyType type) {
 574   if (VerifyAfterGC) {
 575     double verify_time_ms = verify(type, VerifyOption_G1UsePrevMarking, "After GC");
 576     _g1h->g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
 577   }
 578 }
 579 
 580 
 581 #ifndef PRODUCT
 582 class G1VerifyCardTableCleanup: public HeapRegionClosure {
 583   G1HeapVerifier* _verifier;
 584 public:
 585   G1VerifyCardTableCleanup(G1HeapVerifier* verifier)
 586     : _verifier(verifier) { }
 587   virtual bool do_heap_region(HeapRegion* r) {
 588     if (r->is_survivor()) {
 589       _verifier->verify_dirty_region(r);
 590     } else {
 591       _verifier->verify_not_dirty_region(r);
 592     }
 593     return false;
 594   }
 595 };
 596 
 597 void G1HeapVerifier::verify_card_table_cleanup() {
 598   if (G1VerifyCTCleanup || VerifyAfterGC) {
 599     G1VerifyCardTableCleanup cleanup_verifier(this);
 600     _g1h->heap_region_iterate(&cleanup_verifier);
 601   }
 602 }
 603 
 604 void G1HeapVerifier::verify_not_dirty_region(HeapRegion* hr) {
 605   // All of the region should be clean.
 606   G1CardTable* ct = _g1h->card_table();
 607   MemRegion mr(hr->bottom(), hr->end());
 608   ct->verify_not_dirty_region(mr);
 609 }
 610 
 611 void G1HeapVerifier::verify_dirty_region(HeapRegion* hr) {
 612   // We cannot guarantee that [bottom(),end()] is dirty.  Threads
 613   // dirty allocated blocks as they allocate them. The thread that
 614   // retires each region and replaces it with a new one will do a
 615   // maximal allocation to fill in [pre_dummy_top(),end()] but will
 616   // not dirty that area (one less thing to have to do while holding
 617   // a lock). So we can only verify that [bottom(),pre_dummy_top()]
 618   // is dirty.
 619   G1CardTable* ct = _g1h->card_table();
 620   MemRegion mr(hr->bottom(), hr->pre_dummy_top());
 621   if (hr->is_young()) {
 622     ct->verify_g1_young_region(mr);
 623   } else {
 624     ct->verify_dirty_region(mr);
 625   }
 626 }
 627 
 628 class G1VerifyDirtyYoungListClosure : public HeapRegionClosure {
 629 private:
 630   G1HeapVerifier* _verifier;
 631 public:
 632   G1VerifyDirtyYoungListClosure(G1HeapVerifier* verifier) : HeapRegionClosure(), _verifier(verifier) { }
 633   virtual bool do_heap_region(HeapRegion* r) {
 634     _verifier->verify_dirty_region(r);
 635     return false;
 636   }
 637 };
 638 
 639 void G1HeapVerifier::verify_dirty_young_regions() {
 640   G1VerifyDirtyYoungListClosure cl(this);
 641   _g1h->collection_set()->iterate(&cl);
 642 }
 643 
 644 bool G1HeapVerifier::verify_no_bits_over_tams(const char* bitmap_name, const G1CMBitMap* const bitmap,
 645                                                HeapWord* tams, HeapWord* end) {
 646   guarantee(tams <= end,
 647             "tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end));
 648   HeapWord* result = bitmap->get_next_marked_addr(tams, end);
 649   if (result < end) {
 650     log_error(gc, verify)("## wrong marked address on %s bitmap: " PTR_FORMAT, bitmap_name, p2i(result));
 651     log_error(gc, verify)("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT, bitmap_name, p2i(tams), p2i(end));
 652     return false;
 653   }
 654   return true;
 655 }
 656 
 657 bool G1HeapVerifier::verify_bitmaps(const char* caller, HeapRegion* hr) {
 658   const G1CMBitMap* const prev_bitmap = _g1h->concurrent_mark()->prev_mark_bitmap();
 659   const G1CMBitMap* const next_bitmap = _g1h->concurrent_mark()->next_mark_bitmap();
 660 
 661   HeapWord* ptams  = hr->prev_top_at_mark_start();
 662   HeapWord* ntams  = hr->next_top_at_mark_start();
 663   HeapWord* end    = hr->end();
 664 
 665   bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
 666 
 667   bool res_n = true;
 668   // We cannot verify the next bitmap while we are about to clear it.
 669   if (!_g1h->collector_state()->clearing_next_bitmap()) {
 670     res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
 671   }
 672   if (!res_p || !res_n) {
 673     log_error(gc, verify)("#### Bitmap verification failed for " HR_FORMAT, HR_FORMAT_PARAMS(hr));
 674     log_error(gc, verify)("#### Caller: %s", caller);
 675     return false;
 676   }
 677   return true;
 678 }
 679 
 680 void G1HeapVerifier::check_bitmaps(const char* caller, HeapRegion* hr) {
 681   if (!G1VerifyBitmaps) {
 682     return;
 683   }
 684 
 685   guarantee(verify_bitmaps(caller, hr), "bitmap verification");
 686 }
 687 
 688 class G1VerifyBitmapClosure : public HeapRegionClosure {
 689 private:
 690   const char* _caller;
 691   G1HeapVerifier* _verifier;
 692   bool _failures;
 693 
 694 public:
 695   G1VerifyBitmapClosure(const char* caller, G1HeapVerifier* verifier) :
 696     _caller(caller), _verifier(verifier), _failures(false) { }
 697 
 698   bool failures() { return _failures; }
 699 
 700   virtual bool do_heap_region(HeapRegion* hr) {
 701     bool result = _verifier->verify_bitmaps(_caller, hr);
 702     if (!result) {
 703       _failures = true;
 704     }
 705     return false;
 706   }
 707 };
 708 
 709 void G1HeapVerifier::check_bitmaps(const char* caller) {
 710   if (!G1VerifyBitmaps) {
 711     return;
 712   }
 713 
 714   G1VerifyBitmapClosure cl(caller, this);
 715   _g1h->heap_region_iterate(&cl);
 716   guarantee(!cl.failures(), "bitmap verification");
 717 }
 718 
 719 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
 720  private:
 721   bool _failures;
 722  public:
 723   G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
 724 
 725   virtual bool do_heap_region(HeapRegion* hr) {
 726     uint i = hr->hrm_index();
 727     InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
 728     if (hr->is_humongous()) {
 729       if (hr->in_collection_set()) {
 730         log_error(gc, verify)("## humongous region %u in CSet", i);
 731         _failures = true;
 732         return true;
 733       }
 734       if (cset_state.is_in_cset()) {
 735         log_error(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for humongous region %u", cset_state.value(), i);
 736         _failures = true;
 737         return true;
 738       }
 739       if (hr->is_continues_humongous() && cset_state.is_humongous()) {
 740         log_error(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for continues humongous region %u", cset_state.value(), i);
 741         _failures = true;
 742         return true;
 743       }
 744     } else {
 745       if (cset_state.is_humongous()) {
 746         log_error(gc, verify)("## inconsistent cset state " CSETSTATE_FORMAT " for non-humongous region %u", cset_state.value(), i);
 747         _failures = true;
 748         return true;
 749       }
 750       if (hr->in_collection_set() != cset_state.is_in_cset()) {
 751         log_error(gc, verify)("## in CSet %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
 752                              hr->in_collection_set(), cset_state.value(), i);
 753         _failures = true;
 754         return true;
 755       }
 756       if (cset_state.is_in_cset()) {
 757         if (hr->is_young() != (cset_state.is_young())) {
 758           log_error(gc, verify)("## is_young %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
 759                                hr->is_young(), cset_state.value(), i);
 760           _failures = true;
 761           return true;
 762         }
 763         if (hr->is_old() != (cset_state.is_old())) {
 764           log_error(gc, verify)("## is_old %d / cset state " CSETSTATE_FORMAT " inconsistency for region %u",
 765                                hr->is_old(), cset_state.value(), i);
 766           _failures = true;
 767           return true;
 768         }
 769       }
 770     }
 771     return false;
 772   }
 773 
 774   bool failures() const { return _failures; }
 775 };
 776 
 777 bool G1HeapVerifier::check_cset_fast_test() {
 778   G1CheckCSetFastTableClosure cl;
 779   _g1h->_hrm.iterate(&cl);
 780   return !cl.failures();
 781 }
 782 #endif // PRODUCT