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/g1BSCodeGen.hpp"
28 #include "gc/g1/g1CardTable.inline.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/g1/heapRegion.hpp"
31 #include "gc/g1/satbMarkQueue.hpp"
32 #include "logging/log.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/mutexLocker.hpp"
35 #include "runtime/thread.inline.hpp"
36
37 G1BarrierSet::G1BarrierSet(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 BarrierSetCodeGen *G1BarrierSet::make_code_gen() {
58 return new G1BSCodeGen();
59 }
60
61 void G1BarrierSet::write_ref_array_pre_oop_entry(oop* dst, size_t length) {
62 assert(length <= (size_t)max_intx, "count too large");
63 G1BarrierSet *bs = barrier_set_cast<G1BarrierSet>(BarrierSet::barrier_set());
64 bs->G1BarrierSet::write_ref_array_pre(dst, (int)length, false);
65 }
66
67 void G1BarrierSet::write_ref_array_pre_narrow_oop_entry(narrowOop* dst, size_t length) {
68 assert(length <= (size_t)max_intx, "count too large");
69 G1BarrierSet *bs = barrier_set_cast<G1BarrierSet>(BarrierSet::barrier_set());
70 bs->G1BarrierSet::write_ref_array_pre(dst, (int)length, false);
71 }
72
73 void G1BarrierSet::write_ref_array_post_entry(HeapWord* dst, size_t length) {
74 G1BarrierSet *bs = barrier_set_cast<G1BarrierSet>(BarrierSet::barrier_set());
75 bs->G1BarrierSet::write_ref_array(dst, (int)length);
76 }
77
78
79 template <class T> void
80 G1BarrierSet::write_ref_array_pre_work(T* dst, int count) {
81 if (!JavaThread::satb_mark_queue_set().is_active()) return;
82 T* elem_ptr = dst;
83 for (int i = 0; i < count; i++, elem_ptr++) {
84 T heap_oop = oopDesc::load_heap_oop(elem_ptr);
85 if (!oopDesc::is_null(heap_oop)) {
86 enqueue(oopDesc::decode_heap_oop_not_null(heap_oop));
87 }
88 }
89 }
90
91 void G1BarrierSet::write_ref_array_pre(oop* dst, int count, bool dest_uninitialized) {
92 if (!dest_uninitialized) {
93 write_ref_array_pre_work(dst, count);
94 }
95 }
96
97 void G1BarrierSet::write_ref_array_pre(narrowOop* dst, int count, bool dest_uninitialized) {
98 if (!dest_uninitialized) {
99 write_ref_array_pre_work(dst, count);
100 }
101 }
102
103 void G1BarrierSet::write_ref_field_post_slow(volatile jbyte* byte) {
104 // In the slow path, we know a card is not young
105 assert(*byte != G1CardTable::g1_young_card_val(), "slow path invoked without filtering");
106 OrderAccess::storeload();
107 if (*byte != G1CardTable::dirty_card_val()) {
108 *byte = G1CardTable::dirty_card_val();
109 Thread* thr = Thread::current();
110 if (thr->is_Java_thread()) {
111 JavaThread* jt = (JavaThread*)thr;
112 jt->dirty_card_queue().enqueue(byte);
113 } else {
114 MutexLockerEx x(Shared_DirtyCardQ_lock,
115 Mutex::_no_safepoint_check_flag);
116 _dcqs.shared_dirty_card_queue()->enqueue(byte);
117 }
118 }
119 }
120
121 void G1BarrierSet::invalidate(MemRegion mr) {
122 if (mr.is_empty()) {
123 return;
124 }
125 volatile jbyte* byte = _card_table->byte_for(mr.start());
126 jbyte* last_byte = _card_table->byte_for(mr.last());
127 Thread* thr = Thread::current();
128 // skip all consecutive young cards
129 for (; byte <= last_byte && *byte == G1CardTable::g1_young_card_val(); byte++);
130
131 if (byte <= last_byte) {
132 OrderAccess::storeload();
133 // Enqueue if necessary.
134 if (thr->is_Java_thread()) {
135 JavaThread* jt = (JavaThread*)thr;
136 for (; byte <= last_byte; byte++) {
137 if (*byte == G1CardTable::g1_young_card_val()) {
138 continue;
139 }
140 if (*byte != G1CardTable::dirty_card_val()) {
141 *byte = G1CardTable::dirty_card_val();
142 jt->dirty_card_queue().enqueue(byte);
143 }
144 }
145 } else {
146 MutexLockerEx x(Shared_DirtyCardQ_lock,
147 Mutex::_no_safepoint_check_flag);
148 for (; byte <= last_byte; byte++) {
149 if (*byte == G1CardTable::g1_young_card_val()) {
150 continue;
151 }
152 if (*byte != G1CardTable::dirty_card_val()) {
153 *byte = G1CardTable::dirty_card_val();
154 _dcqs.shared_dirty_card_queue()->enqueue(byte);
155 }
156 }
157 }
158 }
159 }
160
161 void G1BarrierSet::on_thread_attach(JavaThread* thread) {
162 // This method initializes the SATB and dirty card queues before a
163 // JavaThread is added to the Java thread list. Right now, we don't
164 // have to do anything to the dirty card queue (it should have been
165 // activated when the thread was created), but we have to activate
166 // the SATB queue if the thread is created while a marking cycle is
167 // in progress. The activation / de-activation of the SATB queues at
168 // the beginning / end of a marking cycle is done during safepoints
169 // so we have to make sure this method is called outside one to be
170 // able to safely read the active field of the SATB queue set. Right
171 // now, it is called just before the thread is added to the Java
172 // thread list in the Threads::add() method. That method is holding
173 // the Threads_lock which ensures we are outside a safepoint. We
174 // cannot do the obvious and set the active field of the SATB queue
175 // when the thread is created given that, in some cases, safepoints
176 // might happen between the JavaThread constructor being called and the
177 // thread being added to the Java thread list (an example of this is
178 // when the structure for the DestroyJavaVM thread is created).
179 assert(!SafepointSynchronize::is_at_safepoint(), "We should not be at a safepoint");
180 assert(!thread->satb_mark_queue().is_active(), "SATB queue should not be active");
181 assert(thread->satb_mark_queue().is_empty(), "SATB queue should be empty");
182 assert(thread->dirty_card_queue().is_active(), "Dirty card queue should be active");
183
184 // If we are creating the thread during a marking cycle, we should
185 // set the active field of the SATB queue to true.
186 if (thread->satb_mark_queue_set().is_active()) {
187 thread->satb_mark_queue().set_active(true);
188 }
189 }
190
191 void G1BarrierSet::on_thread_detach(JavaThread* thread) {
192 // Flush any deferred card marks, SATB buffers and dirty card queue buffers
193 CardTableModRefBS::on_thread_detach(thread);
194 thread->satb_mark_queue().flush();
195 thread->dirty_card_queue().flush();
196 }