1 /*
2 * Copyright (c) 2001, 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/g1BarrierSet.inline.hpp"
27 #include "gc/g1/g1CardTable.inline.hpp"
28 #include "gc/g1/g1CollectedHeap.inline.hpp"
29 #include "gc/g1/heapRegion.hpp"
30 #include "gc/g1/satbMarkQueue.hpp"
31 #include "logging/log.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "runtime/mutexLocker.hpp"
34 #include "runtime/thread.inline.hpp"
35
36 G1BarrierSet::G1BarrierSet(
37 G1CardTable* card_table) :
38 CardTableModRefBS(card_table, BarrierSet::FakeRtti(BarrierSet::G1BarrierSet)),
39 _dcqs(JavaThread::dirty_card_queue_set())
40 { }
41
42 void G1BarrierSet::enqueue(oop pre_val) {
43 // Nulls should have been already filtered.
44 assert(oopDesc::is_oop(pre_val, true), "Error");
45
46 if (!JavaThread::satb_mark_queue_set().is_active()) return;
47 Thread* thr = Thread::current();
48 if (thr->is_Java_thread()) {
49 JavaThread* jt = (JavaThread*)thr;
50 jt->satb_mark_queue().enqueue(pre_val);
51 } else {
52 MutexLockerEx x(Shared_SATB_Q_lock, Mutex::_no_safepoint_check_flag);
53 JavaThread::satb_mark_queue_set().shared_satb_queue()->enqueue(pre_val);
54 }
55 }
56
57 template <class T> void
58 G1BarrierSet::write_ref_array_pre_work(T* dst, int count) {
59 if (!JavaThread::satb_mark_queue_set().is_active()) return;
60 T* elem_ptr = dst;
61 for (int i = 0; i < count; i++, elem_ptr++) {
62 T heap_oop = oopDesc::load_heap_oop(elem_ptr);
63 if (!oopDesc::is_null(heap_oop)) {
64 enqueue(oopDesc::decode_heap_oop_not_null(heap_oop));
65 }
66 }
67 }
68
69 void G1BarrierSet::write_ref_array_pre(oop* dst, int count, bool dest_uninitialized) {
70 if (!dest_uninitialized) {
71 write_ref_array_pre_work(dst, count);
72 }
73 }
74
75 void G1BarrierSet::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 void G1BarrierSet::write_ref_field_post_slow(volatile jbyte* byte) {
82 // In the slow path, we know a card is not young
83 assert(*byte != G1CardTable::g1_young_card_val(), "slow path invoked without filtering");
84 OrderAccess::storeload();
85 if (*byte != G1CardTable::dirty_card_val()) {
86 *byte = G1CardTable::dirty_card_val();
87 Thread* thr = Thread::current();
88 if (thr->is_Java_thread()) {
89 JavaThread* jt = (JavaThread*)thr;
90 jt->dirty_card_queue().enqueue(byte);
91 } else {
92 MutexLockerEx x(Shared_DirtyCardQ_lock,
93 Mutex::_no_safepoint_check_flag);
94 _dcqs.shared_dirty_card_queue()->enqueue(byte);
95 }
96 }
97 }
98
99 void G1BarrierSet::invalidate(MemRegion mr) {
100 if (mr.is_empty()) {
101 return;
102 }
103 volatile jbyte* byte = _card_table->byte_for(mr.start());
104 jbyte* last_byte = _card_table->byte_for(mr.last());
105 Thread* thr = Thread::current();
106 // skip all consecutive young cards
107 for (; byte <= last_byte && *byte == G1CardTable::g1_young_card_val(); byte++);
108
109 if (byte <= last_byte) {
110 OrderAccess::storeload();
111 // Enqueue if necessary.
112 if (thr->is_Java_thread()) {
113 JavaThread* jt = (JavaThread*)thr;
114 for (; byte <= last_byte; byte++) {
115 if (*byte == G1CardTable::g1_young_card_val()) {
116 continue;
117 }
118 if (*byte != G1CardTable::dirty_card_val()) {
119 *byte = G1CardTable::dirty_card_val();
120 jt->dirty_card_queue().enqueue(byte);
121 }
122 }
123 } else {
124 MutexLockerEx x(Shared_DirtyCardQ_lock,
125 Mutex::_no_safepoint_check_flag);
126 for (; byte <= last_byte; byte++) {
127 if (*byte == G1CardTable::g1_young_card_val()) {
128 continue;
129 }
130 if (*byte != G1CardTable::dirty_card_val()) {
131 *byte = G1CardTable::dirty_card_val();
132 _dcqs.shared_dirty_card_queue()->enqueue(byte);
133 }
134 }
135 }
136 }
137 }
138
139 void G1BarrierSet::on_thread_attach(JavaThread* thread) {
140 // This method initializes the SATB and dirty card queues before a
141 // JavaThread is added to the Java thread list. Right now, we don't
142 // have to do anything to the dirty card queue (it should have been
143 // activated when the thread was created), but we have to activate
144 // the SATB queue if the thread is created while a marking cycle is
145 // in progress. The activation / de-activation of the SATB queues at
146 // the beginning / end of a marking cycle is done during safepoints
147 // so we have to make sure this method is called outside one to be
148 // able to safely read the active field of the SATB queue set. Right
149 // now, it is called just before the thread is added to the Java
150 // thread list in the Threads::add() method. That method is holding
151 // the Threads_lock which ensures we are outside a safepoint. We
152 // cannot do the obvious and set the active field of the SATB queue
153 // when the thread is created given that, in some cases, safepoints
154 // might happen between the JavaThread constructor being called and the
155 // thread being added to the Java thread list (an example of this is
156 // when the structure for the DestroyJavaVM thread is created).
157 assert(!SafepointSynchronize::is_at_safepoint(), "We should not be at a safepoint");
158 assert(!thread->satb_mark_queue().is_active(), "SATB queue should not be active");
159 assert(thread->satb_mark_queue().is_empty(), "SATB queue should be empty");
160 assert(thread->dirty_card_queue().is_active(), "Dirty card queue should be active");
161
162 // If we are creating the thread during a marking cycle, we should
163 // set the active field of the SATB queue to true.
164 if (thread->satb_mark_queue_set().is_active()) {
165 thread->satb_mark_queue().set_active(true);
166 }
167 }
168
169 void G1BarrierSet::on_thread_detach(JavaThread* thread) {
170 // Flush any deferred card marks, SATB buffers and dirty card queue buffers
171 CardTableModRefBS::on_thread_detach(thread);
172 thread->satb_mark_queue().flush();
173 thread->dirty_card_queue().flush();
174 }