1 /*
   2  * Copyright (c) 2001, 2015, 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.hpp"
  28 #include "gc/g1/heapRegion.hpp"
  29 #include "gc/g1/satbQueue.hpp"
  30 #include "gc/shared/memset_with_concurrent_readers.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/atomic.inline.hpp"
  33 #include "runtime/mutexLocker.hpp"
  34 #include "runtime/orderAccess.inline.hpp"
  35 #include "runtime/thread.inline.hpp"
  36 
  37 G1SATBCardTableModRefBS::G1SATBCardTableModRefBS(
  38   MemRegion whole_heap,
  39   const BarrierSet::FakeRtti& fake_rtti) :
  40   CardTableModRefBS(whole_heap, fake_rtti.add_tag(BarrierSet::G1SATBCT))
  41 { }
  42 
  43 void G1SATBCardTableModRefBS::enqueue(oop pre_val) {
  44   // Nulls should have been already filtered.
  45   assert(pre_val->is_oop(true), "Error");
  46 
  47   if (!JavaThread::satb_mark_queue_set().is_active()) return;
  48   Thread* thr = Thread::current();
  49   if (thr->is_Java_thread()) {
  50     JavaThread* jt = (JavaThread*)thr;
  51     jt->satb_mark_queue().enqueue(pre_val);
  52   } else {
  53     MutexLockerEx x(Shared_SATB_Q_lock, Mutex::_no_safepoint_check_flag);
  54     JavaThread::satb_mark_queue_set().shared_satb_queue()->enqueue(pre_val);
  55   }
  56 }
  57 
  58 template <class T> void
  59 G1SATBCardTableModRefBS::write_ref_array_pre_work(T* dst, int count) {
  60   if (!JavaThread::satb_mark_queue_set().is_active()) return;
  61   T* elem_ptr = dst;
  62   for (int i = 0; i < count; i++, elem_ptr++) {
  63     T heap_oop = oopDesc::load_heap_oop(elem_ptr);
  64     if (!oopDesc::is_null(heap_oop)) {
  65       enqueue(oopDesc::decode_heap_oop_not_null(heap_oop));
  66     }
  67   }
  68 }
  69 
  70 void G1SATBCardTableModRefBS::write_ref_array_pre(oop* dst, int count, bool dest_uninitialized) {
  71   if (!dest_uninitialized) {
  72     write_ref_array_pre_work(dst, count);
  73   }
  74 }
  75 void G1SATBCardTableModRefBS::write_ref_array_pre(narrowOop* dst, int count, bool dest_uninitialized) {
  76   if (!dest_uninitialized) {
  77     write_ref_array_pre_work(dst, count);
  78   }
  79 }
  80 
  81 bool G1SATBCardTableModRefBS::mark_card_deferred(size_t card_index) {
  82   jbyte val = _byte_map[card_index];
  83   // It's already processed
  84   if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) {
  85     return false;
  86   }
  87 
  88   if  (val == g1_young_gen) {
  89     // the card is for a young gen region. We don't need to keep track of all pointers into young
  90     return false;
  91   }
  92 
  93   // Cached bit can be installed either on a clean card or on a claimed card.
  94   jbyte new_val = val;
  95   if (val == clean_card_val()) {
  96     new_val = (jbyte)deferred_card_val();
  97   } else {
  98     if (val & claimed_card_val()) {
  99       new_val = val | (jbyte)deferred_card_val();
 100     }
 101   }
 102   if (new_val != val) {
 103     Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
 104   }
 105   return true;
 106 }
 107 
 108 void G1SATBCardTableModRefBS::g1_mark_as_young(const MemRegion& mr) {
 109   jbyte *const first = byte_for(mr.start());
 110   jbyte *const last = byte_after(mr.last());
 111 
 112   memset_with_concurrent_readers(first, g1_young_gen, last - first);
 113 }
 114 
 115 #ifndef PRODUCT
 116 void G1SATBCardTableModRefBS::verify_g1_young_region(MemRegion mr) {
 117   verify_region(mr, g1_young_gen,  true);
 118 }
 119 #endif
 120 
 121 void G1SATBCardTableLoggingModRefBSChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
 122   // Default value for a clean card on the card table is -1. So we cannot take advantage of the zero_filled parameter.
 123   MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
 124   _card_table->clear(mr);
 125 }
 126 
 127 G1SATBCardTableLoggingModRefBS::
 128 G1SATBCardTableLoggingModRefBS(MemRegion whole_heap) :
 129   G1SATBCardTableModRefBS(whole_heap, BarrierSet::FakeRtti(G1SATBCTLogging)),
 130   _dcqs(JavaThread::dirty_card_queue_set()),
 131   _listener()
 132 {
 133   _listener.set_card_table(this);
 134 }
 135 
 136 void G1SATBCardTableLoggingModRefBS::initialize(G1RegionToSpaceMapper* mapper) {
 137   mapper->set_mapping_changed_listener(&_listener);
 138 
 139   _byte_map_size = mapper->reserved().byte_size();
 140 
 141   _guard_index = cards_required(_whole_heap.word_size()) - 1;
 142   _last_valid_index = _guard_index - 1;
 143 
 144   HeapWord* low_bound  = _whole_heap.start();
 145   HeapWord* high_bound = _whole_heap.end();
 146 
 147   _cur_covered_regions = 1;
 148   _covered[0] = _whole_heap;
 149 
 150   _byte_map = (jbyte*) mapper->reserved().start();
 151   byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
 152   assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
 153   assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
 154 
 155   if (TraceCardTableModRefBS) {
 156     gclog_or_tty->print_cr("G1SATBCardTableModRefBS::G1SATBCardTableModRefBS: ");
 157     gclog_or_tty->print_cr("  "
 158                   "  &_byte_map[0]: " INTPTR_FORMAT
 159                   "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
 160                   p2i(&_byte_map[0]),
 161                   p2i(&_byte_map[_last_valid_index]));
 162     gclog_or_tty->print_cr("  "
 163                   "  byte_map_base: " INTPTR_FORMAT,
 164                   p2i(byte_map_base));
 165   }
 166 }
 167 
 168 void
 169 G1SATBCardTableLoggingModRefBS::write_ref_field_work(void* field,
 170                                                      oop new_val,
 171                                                      bool release) {
 172   volatile jbyte* byte = byte_for(field);
 173   if (*byte == g1_young_gen) {
 174     return;
 175   }
 176   OrderAccess::storeload();
 177   if (*byte != dirty_card) {
 178     *byte = dirty_card;
 179     Thread* thr = Thread::current();
 180     if (thr->is_Java_thread()) {
 181       JavaThread* jt = (JavaThread*)thr;
 182       jt->dirty_card_queue().enqueue(byte);
 183     } else {
 184       MutexLockerEx x(Shared_DirtyCardQ_lock,
 185                       Mutex::_no_safepoint_check_flag);
 186       _dcqs.shared_dirty_card_queue()->enqueue(byte);
 187     }
 188   }
 189 }
 190 
 191 void
 192 G1SATBCardTableLoggingModRefBS::write_ref_field_static(void* field,
 193                                                        oop new_val) {
 194   uintptr_t field_uint = (uintptr_t)field;
 195   uintptr_t new_val_uint = cast_from_oop<uintptr_t>(new_val);
 196   uintptr_t comb = field_uint ^ new_val_uint;
 197   comb = comb >> HeapRegion::LogOfHRGrainBytes;
 198   if (comb == 0) return;
 199   if (new_val == NULL) return;
 200   // Otherwise, log it.
 201   G1SATBCardTableLoggingModRefBS* g1_bs =
 202     barrier_set_cast<G1SATBCardTableLoggingModRefBS>(G1CollectedHeap::heap()->barrier_set());
 203   g1_bs->write_ref_field_work(field, new_val, false);
 204 }
 205 
 206 void
 207 G1SATBCardTableLoggingModRefBS::invalidate(MemRegion mr, bool whole_heap) {
 208   volatile jbyte* byte = byte_for(mr.start());
 209   jbyte* last_byte = byte_for(mr.last());
 210   Thread* thr = Thread::current();
 211   if (whole_heap) {
 212     while (byte <= last_byte) {
 213       *byte = dirty_card;
 214       byte++;
 215     }
 216   } else {
 217     // skip all consecutive young cards
 218     for (; byte <= last_byte && *byte == g1_young_gen; byte++);
 219 
 220     if (byte <= last_byte) {
 221       OrderAccess::storeload();
 222       // Enqueue if necessary.
 223       if (thr->is_Java_thread()) {
 224         JavaThread* jt = (JavaThread*)thr;
 225         for (; byte <= last_byte; byte++) {
 226           if (*byte == g1_young_gen) {
 227             continue;
 228           }
 229           if (*byte != dirty_card) {
 230             *byte = dirty_card;
 231             jt->dirty_card_queue().enqueue(byte);
 232           }
 233         }
 234       } else {
 235         MutexLockerEx x(Shared_DirtyCardQ_lock,
 236                         Mutex::_no_safepoint_check_flag);
 237         for (; byte <= last_byte; byte++) {
 238           if (*byte == g1_young_gen) {
 239             continue;
 240           }
 241           if (*byte != dirty_card) {
 242             *byte = dirty_card;
 243             _dcqs.shared_dirty_card_queue()->enqueue(byte);
 244           }
 245         }
 246       }
 247     }
 248   }
 249 }
 250 
 251 void G1SATBCardTableModRefBS::write_ref_nmethod_post(oop* dst, nmethod* nm) {
 252   oop obj = oopDesc::load_heap_oop(dst);
 253   if (obj != NULL) {
 254     G1CollectedHeap* g1h = G1CollectedHeap::heap();
 255     HeapRegion* hr = g1h->heap_region_containing(obj);
 256     hr->add_strong_code_root(nm);
 257   }
 258 }
 259 
 260 class G1EnsureLastRefToRegion : public OopClosure {
 261   G1CollectedHeap* _g1h;
 262   HeapRegion* _hr;
 263   oop* _dst;
 264 
 265   bool _value;
 266 public:
 267   G1EnsureLastRefToRegion(G1CollectedHeap* g1h, HeapRegion* hr, oop* dst) :
 268     _g1h(g1h), _hr(hr), _dst(dst), _value(true) {}
 269 
 270   void do_oop(oop* p) {
 271     if (_value && p != _dst) {
 272       oop obj = oopDesc::load_heap_oop(p);
 273       if (obj != NULL) {
 274         HeapRegion* hr = _g1h->heap_region_containing(obj);
 275         if (hr == _hr) {
 276           // Another reference to the same region.
 277           _value = false;
 278         }
 279       }
 280     }
 281   }
 282   void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 283   bool value() const        { return _value;  }
 284 };
 285 
 286 void G1SATBCardTableModRefBS::write_ref_nmethod_pre(oop* dst, nmethod* nm) {
 287   oop obj = oopDesc::load_heap_oop(dst);
 288   if (obj != NULL) {
 289     G1CollectedHeap* g1h = G1CollectedHeap::heap();
 290     HeapRegion* hr = g1h->heap_region_containing(obj);
 291     G1EnsureLastRefToRegion ensure_last_ref(g1h, hr, dst);
 292     nm->oops_do(&ensure_last_ref);
 293     if (ensure_last_ref.value()) {
 294       // Last reference to this region, remove the nmethod from the rset.
 295       hr->remove_strong_code_root(nm);
 296     }
 297   }
 298 }