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/access.inline.hpp"
33 #include "oops/compressedOops.inline.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/mutexLocker.hpp"
36 #include "runtime/thread.inline.hpp"
37
38 G1BarrierSet::G1BarrierSet(G1CardTable* card_table) :
39 CardTableModRefBS(card_table, BarrierSet::FakeRtti(BarrierSet::G1BarrierSet)),
40 _dcqs(JavaThread::dirty_card_queue_set())
41 { }
42
43 void G1BarrierSet::enqueue(oop pre_val) {
44 // Nulls should have been already filtered.
45 assert(oopDesc::is_oop(pre_val, 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 G1BarrierSet::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 = RawAccess<>::oop_load(elem_ptr);
64 if (!CompressedOops::is_null(heap_oop)) {
65 enqueue(CompressedOops::decode_not_null(heap_oop));
66 }
67 }
68 }
69
70 void G1BarrierSet::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
76 void G1BarrierSet::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 void G1BarrierSet::write_ref_field_post_slow(volatile jbyte* byte) {
83 // In the slow path, we know a card is not young
84 assert(*byte != G1CardTable::g1_young_card_val(), "slow path invoked without filtering");
85 OrderAccess::storeload();
86 if (*byte != G1CardTable::dirty_card_val()) {
87 *byte = G1CardTable::dirty_card_val();
88 Thread* thr = Thread::current();
89 if (thr->is_Java_thread()) {
90 JavaThread* jt = (JavaThread*)thr;
91 jt->dirty_card_queue().enqueue(byte);
92 } else {
93 MutexLockerEx x(Shared_DirtyCardQ_lock,
94 Mutex::_no_safepoint_check_flag);
95 _dcqs.shared_dirty_card_queue()->enqueue(byte);
96 }
97 }
98 }
99
100 void G1BarrierSet::invalidate(MemRegion mr) {
101 if (mr.is_empty()) {
102 return;
103 }
104 volatile jbyte* byte = _card_table->byte_for(mr.start());
105 jbyte* last_byte = _card_table->byte_for(mr.last());
106 Thread* thr = Thread::current();
107 // skip all consecutive young cards
108 for (; byte <= last_byte && *byte == G1CardTable::g1_young_card_val(); byte++);
109
110 if (byte <= last_byte) {
111 OrderAccess::storeload();
112 // Enqueue if necessary.
113 if (thr->is_Java_thread()) {
114 JavaThread* jt = (JavaThread*)thr;
115 for (; byte <= last_byte; byte++) {
116 if (*byte == G1CardTable::g1_young_card_val()) {
117 continue;
118 }
119 if (*byte != G1CardTable::dirty_card_val()) {
120 *byte = G1CardTable::dirty_card_val();
121 jt->dirty_card_queue().enqueue(byte);
122 }
123 }
124 } else {
125 MutexLockerEx x(Shared_DirtyCardQ_lock,
126 Mutex::_no_safepoint_check_flag);
127 for (; byte <= last_byte; byte++) {
128 if (*byte == G1CardTable::g1_young_card_val()) {
129 continue;
130 }
131 if (*byte != G1CardTable::dirty_card_val()) {
132 *byte = G1CardTable::dirty_card_val();
133 _dcqs.shared_dirty_card_queue()->enqueue(byte);
134 }
135 }
136 }
137 }
138 }
139
140 void G1BarrierSet::on_thread_attach(JavaThread* thread) {
141 // This method initializes the SATB and dirty card queues before a
142 // JavaThread is added to the Java thread list. Right now, we don't
143 // have to do anything to the dirty card queue (it should have been
144 // activated when the thread was created), but we have to activate
145 // the SATB queue if the thread is created while a marking cycle is
146 // in progress. The activation / de-activation of the SATB queues at
147 // the beginning / end of a marking cycle is done during safepoints
148 // so we have to make sure this method is called outside one to be
149 // able to safely read the active field of the SATB queue set. Right
150 // now, it is called just before the thread is added to the Java
151 // thread list in the Threads::add() method. That method is holding
152 // the Threads_lock which ensures we are outside a safepoint. We
153 // cannot do the obvious and set the active field of the SATB queue
154 // when the thread is created given that, in some cases, safepoints
155 // might happen between the JavaThread constructor being called and the
156 // thread being added to the Java thread list (an example of this is
157 // when the structure for the DestroyJavaVM thread is created).
158 assert(!SafepointSynchronize::is_at_safepoint(), "We should not be at a safepoint");
159 assert(!thread->satb_mark_queue().is_active(), "SATB queue should not be active");
160 assert(thread->satb_mark_queue().is_empty(), "SATB queue should be empty");
161 assert(thread->dirty_card_queue().is_active(), "Dirty card queue should be active");
162
163 // If we are creating the thread during a marking cycle, we should
164 // set the active field of the SATB queue to true.
165 if (thread->satb_mark_queue_set().is_active()) {
166 thread->satb_mark_queue().set_active(true);
167 }
168 }
169
170 void G1BarrierSet::on_thread_detach(JavaThread* thread) {
171 // Flush any deferred card marks, SATB buffers and dirty card queue buffers
172 CardTableModRefBS::on_thread_detach(thread);
173 thread->satb_mark_queue().flush();
174 thread->dirty_card_queue().flush();
175 }