1 /*
   2  * Copyright (c) 2001, 2016, 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/g1CollectedHeap.inline.hpp"
  27 #include "gc/g1/g1SATBCardTableModRefBS.inline.hpp"
  28 #include "gc/g1/heapRegion.hpp"
  29 #include "gc/g1/satbMarkQueue.hpp"
  30 #include "gc/shared/memset_with_concurrent_readers.hpp"
  31 #include "logging/log.hpp"
  32 #include "oops/oop.inline.hpp"
  33 #include "runtime/atomic.hpp"
  34 #include "runtime/mutexLocker.hpp"
  35 #include "runtime/orderAccess.inline.hpp"
  36 #include "runtime/thread.inline.hpp"
  37 
  38 G1SATBCardTableModRefBS::G1SATBCardTableModRefBS(
  39   MemRegion whole_heap,
  40   const BarrierSet::FakeRtti& fake_rtti) :
  41   CardTableModRefBS(whole_heap, fake_rtti.add_tag(BarrierSet::G1SATBCT))
  42 { }
  43 
  44 void G1SATBCardTableModRefBS::enqueue(oop pre_val) {
  45   // Nulls should have been already filtered.
  46   assert(pre_val->is_oop(true), "Error");
  47 
  48   if (!JavaThread::satb_mark_queue_set().is_active()) return;
  49   Thread* thr = Thread::current();
  50   if (thr->is_Java_thread()) {
  51     JavaThread* jt = (JavaThread*)thr;
  52     jt->satb_mark_queue().enqueue(pre_val);
  53   } else {
  54     MutexLockerEx x(Shared_SATB_Q_lock, Mutex::_no_safepoint_check_flag);
  55     JavaThread::satb_mark_queue_set().shared_satb_queue()->enqueue(pre_val);
  56   }
  57 }
  58 
  59 template <class T> void
  60 G1SATBCardTableModRefBS::write_ref_array_pre_work(T* dst, int count) {
  61   if (!JavaThread::satb_mark_queue_set().is_active()) return;
  62   T* elem_ptr = dst;
  63   for (int i = 0; i < count; i++, elem_ptr++) {
  64     T heap_oop = oopDesc::load_heap_oop(elem_ptr);
  65     if (!oopDesc::is_null(heap_oop)) {
  66       enqueue(oopDesc::decode_heap_oop_not_null(heap_oop));
  67     }
  68   }
  69 }
  70 
  71 void G1SATBCardTableModRefBS::write_ref_array_pre(oop* dst, int count, bool dest_uninitialized) {
  72   if (!dest_uninitialized) {
  73     write_ref_array_pre_work(dst, count);
  74   }
  75 }
  76 void G1SATBCardTableModRefBS::write_ref_array_pre(narrowOop* dst, int count, bool dest_uninitialized) {
  77   if (!dest_uninitialized) {
  78     write_ref_array_pre_work(dst, count);
  79   }
  80 }
  81 
  82 bool G1SATBCardTableModRefBS::mark_card_deferred(size_t card_index) {
  83   jbyte val = _byte_map[card_index];
  84   // It's already processed
  85   if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) {
  86     return false;
  87   }
  88 
  89   // Cached bit can be installed either on a clean card or on a claimed card.
  90   jbyte new_val = val;
  91   if (val == clean_card_val()) {
  92     new_val = (jbyte)deferred_card_val();
  93   } else {
  94     if (val & claimed_card_val()) {
  95       new_val = val | (jbyte)deferred_card_val();
  96     }
  97   }
  98   if (new_val != val) {
  99     Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
 100   }
 101   return true;
 102 }
 103 
 104 void G1SATBCardTableModRefBS::g1_mark_as_young(const MemRegion& mr) {
 105   jbyte *const first = byte_for(mr.start());
 106   jbyte *const last = byte_after(mr.last());
 107 
 108   memset_with_concurrent_readers(first, g1_young_gen, last - first);
 109 }
 110 
 111 #ifndef PRODUCT
 112 void G1SATBCardTableModRefBS::verify_g1_young_region(MemRegion mr) {
 113   verify_region(mr, g1_young_gen,  true);
 114 }
 115 #endif
 116 
 117 void G1SATBCardTableLoggingModRefBSChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 118   // Default value for a clean card on the card table is -1. So we cannot take advantage of the zero_filled parameter.
 119   MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
 120   _card_table->clear(mr);
 121 }
 122 
 123 G1SATBCardTableLoggingModRefBS::
 124 G1SATBCardTableLoggingModRefBS(MemRegion whole_heap) :
 125   G1SATBCardTableModRefBS(whole_heap, BarrierSet::FakeRtti(G1SATBCTLogging)),
 126   _dcqs(JavaThread::dirty_card_queue_set()),
 127   _listener()
 128 {
 129   _listener.set_card_table(this);
 130 }
 131 
 132 void G1SATBCardTableLoggingModRefBS::initialize(G1RegionToSpaceMapper* mapper) {
 133   mapper->set_mapping_changed_listener(&_listener);
 134 
 135   _byte_map_size = mapper->reserved().byte_size();
 136 
 137   _guard_index = cards_required(_whole_heap.word_size()) - 1;
 138   _last_valid_index = _guard_index - 1;
 139 
 140   HeapWord* low_bound  = _whole_heap.start();
 141   HeapWord* high_bound = _whole_heap.end();
 142 
 143   _cur_covered_regions = 1;
 144   _covered[0] = _whole_heap;
 145 
 146   _byte_map = (jbyte*) mapper->reserved().start();
 147   byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
 148   assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
 149   assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
 150 
 151   log_trace(gc, barrier)("G1SATBCardTableModRefBS::G1SATBCardTableModRefBS: ");
 152   log_trace(gc, barrier)("    &_byte_map[0]: " INTPTR_FORMAT "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
 153                          p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index]));
 154   log_trace(gc, barrier)("    byte_map_base: " INTPTR_FORMAT,  p2i(byte_map_base));
 155 }
 156 
 157 void
 158 G1SATBCardTableLoggingModRefBS::write_ref_field_work(void* field,
 159                                                      oop new_val,
 160                                                      bool release) {
 161   volatile jbyte* byte = byte_for(field);
 162   if (*byte == g1_young_gen) {
 163     return;
 164   }
 165   OrderAccess::storeload();
 166   if (*byte != dirty_card) {
 167     *byte = dirty_card;
 168     Thread* thr = Thread::current();
 169     if (thr->is_Java_thread()) {
 170       JavaThread* jt = (JavaThread*)thr;
 171       jt->dirty_card_queue().enqueue(byte);
 172     } else {
 173       MutexLockerEx x(Shared_DirtyCardQ_lock,
 174                       Mutex::_no_safepoint_check_flag);
 175       _dcqs.shared_dirty_card_queue()->enqueue(byte);
 176     }
 177   }
 178 }
 179 
 180 void
 181 G1SATBCardTableLoggingModRefBS::invalidate(MemRegion mr) {
 182   volatile jbyte* byte = byte_for(mr.start());
 183   jbyte* last_byte = byte_for(mr.last());
 184   Thread* thr = Thread::current();
 185     // skip all consecutive young cards
 186   for (; byte <= last_byte && *byte == g1_young_gen; byte++);
 187 
 188   if (byte <= last_byte) {
 189     OrderAccess::storeload();
 190     // Enqueue if necessary.
 191     if (thr->is_Java_thread()) {
 192       JavaThread* jt = (JavaThread*)thr;
 193       for (; byte <= last_byte; byte++) {
 194         if (*byte == g1_young_gen) {
 195           continue;
 196         }
 197         if (*byte != dirty_card) {
 198           *byte = dirty_card;
 199           jt->dirty_card_queue().enqueue(byte);
 200         }
 201       }
 202     } else {
 203       MutexLockerEx x(Shared_DirtyCardQ_lock,
 204                       Mutex::_no_safepoint_check_flag);
 205       for (; byte <= last_byte; byte++) {
 206         if (*byte == g1_young_gen) {
 207           continue;
 208         }
 209         if (*byte != dirty_card) {
 210           *byte = dirty_card;
 211           _dcqs.shared_dirty_card_queue()->enqueue(byte);
 212         }
 213       }
 214     }
 215   }
 216 }
 217 
 218 void G1SATBCardTableModRefBS::write_ref_nmethod_post(oop* dst, nmethod* nm) {
 219   oop obj = oopDesc::load_heap_oop(dst);
 220   if (obj != NULL) {
 221     G1CollectedHeap* g1h = G1CollectedHeap::heap();
 222     HeapRegion* hr = g1h->heap_region_containing(obj);
 223     hr->add_strong_code_root(nm);
 224   }
 225 }
 226 
 227 class G1EnsureLastRefToRegion : public OopClosure {
 228   G1CollectedHeap* _g1h;
 229   HeapRegion* _hr;
 230   oop* _dst;
 231 
 232   bool _value;
 233 public:
 234   G1EnsureLastRefToRegion(G1CollectedHeap* g1h, HeapRegion* hr, oop* dst) :
 235     _g1h(g1h), _hr(hr), _dst(dst), _value(true) {}
 236 
 237   void do_oop(oop* p) {
 238     if (_value && p != _dst) {
 239       oop obj = oopDesc::load_heap_oop(p);
 240       if (obj != NULL) {
 241         HeapRegion* hr = _g1h->heap_region_containing(obj);
 242         if (hr == _hr) {
 243           // Another reference to the same region.
 244           _value = false;
 245         }
 246       }
 247     }
 248   }
 249   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 250   bool value() const        { return _value;  }
 251 };
 252 
 253 void G1SATBCardTableModRefBS::write_ref_nmethod_pre(oop* dst, nmethod* nm) {
 254   oop obj = oopDesc::load_heap_oop(dst);
 255   if (obj != NULL) {
 256     G1CollectedHeap* g1h = G1CollectedHeap::heap();
 257     HeapRegion* hr = g1h->heap_region_containing(obj);
 258     G1EnsureLastRefToRegion ensure_last_ref(g1h, hr, dst);
 259     nm->oops_do(&ensure_last_ref);
 260     if (ensure_last_ref.value()) {
 261       // Last reference to this region, remove the nmethod from the rset.
 262       hr->remove_strong_code_root(nm);
 263     }
 264   }
 265 }