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/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(oopDesc::is_oop(pre_val, 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
77 void G1SATBCardTableModRefBS::write_ref_array_pre(narrowOop* dst, int count, bool dest_uninitialized) {
78 if (!dest_uninitialized) {
79 write_ref_array_pre_work(dst, count);
80 }
81 }
82
83 bool G1SATBCardTableModRefBS::mark_card_deferred(size_t card_index) {
84 jbyte val = _byte_map[card_index];
85 // It's already processed
86 if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) {
87 return false;
88 }
89
90 // Cached bit can be installed either on a clean card or on a claimed card.
91 jbyte new_val = val;
92 if (val == clean_card_val()) {
93 new_val = (jbyte)deferred_card_val();
94 } else {
95 if (val & claimed_card_val()) {
96 new_val = val | (jbyte)deferred_card_val();
97 }
98 }
99 if (new_val != val) {
100 Atomic::cmpxchg(new_val, &_byte_map[card_index], val);
101 }
102 return true;
103 }
104
105 void G1SATBCardTableModRefBS::g1_mark_as_young(const MemRegion& mr) {
106 jbyte *const first = byte_for(mr.start());
107 jbyte *const last = byte_after(mr.last());
108
109 memset_with_concurrent_readers(first, g1_young_gen, last - first);
110 }
111
112 #ifndef PRODUCT
113 void G1SATBCardTableModRefBS::verify_g1_young_region(MemRegion mr) {
114 verify_region(mr, g1_young_gen, true);
115 }
116 #endif
117
118 void G1SATBCardTableLoggingModRefBSChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
119 // Default value for a clean card on the card table is -1. So we cannot take advantage of the zero_filled parameter.
120 MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);
121 _card_table->clear(mr);
122 }
123
124 G1SATBCardTableLoggingModRefBS::
125 G1SATBCardTableLoggingModRefBS(MemRegion whole_heap) :
126 G1SATBCardTableModRefBS(whole_heap, BarrierSet::FakeRtti(G1SATBCTLogging)),
127 _dcqs(JavaThread::dirty_card_queue_set()),
128 _listener()
129 {
130 _listener.set_card_table(this);
131 }
132
133 void G1SATBCardTableLoggingModRefBS::initialize(G1RegionToSpaceMapper* mapper) {
134 initialize_deferred_card_mark_barriers();
135 mapper->set_mapping_changed_listener(&_listener);
136
137 _byte_map_size = mapper->reserved().byte_size();
138
139 _guard_index = cards_required(_whole_heap.word_size()) - 1;
140 _last_valid_index = _guard_index - 1;
141
142 HeapWord* low_bound = _whole_heap.start();
143 HeapWord* high_bound = _whole_heap.end();
144
145 _cur_covered_regions = 1;
146 _covered[0] = _whole_heap;
147
148 _byte_map = (jbyte*) mapper->reserved().start();
149 byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);
150 assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");
151 assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");
152
153 log_trace(gc, barrier)("G1SATBCardTableModRefBS::G1SATBCardTableModRefBS: ");
154 log_trace(gc, barrier)(" &_byte_map[0]: " INTPTR_FORMAT " &_byte_map[_last_valid_index]: " INTPTR_FORMAT,
155 p2i(&_byte_map[0]), p2i(&_byte_map[_last_valid_index]));
156 log_trace(gc, barrier)(" byte_map_base: " INTPTR_FORMAT, p2i(byte_map_base));
157 }
158
159 void G1SATBCardTableLoggingModRefBS::write_ref_field_post_slow(volatile jbyte* byte) {
160 // In the slow path, we know a card is not young
161 assert(*byte != g1_young_gen, "slow path invoked without filtering");
162 OrderAccess::storeload();
163 if (*byte != dirty_card) {
164 *byte = dirty_card;
165 Thread* thr = Thread::current();
166 if (thr->is_Java_thread()) {
167 JavaThread* jt = (JavaThread*)thr;
168 jt->dirty_card_queue().enqueue(byte);
169 } else {
170 MutexLockerEx x(Shared_DirtyCardQ_lock,
171 Mutex::_no_safepoint_check_flag);
172 _dcqs.shared_dirty_card_queue()->enqueue(byte);
173 }
174 }
175 }
176
177 void
178 G1SATBCardTableLoggingModRefBS::invalidate(MemRegion mr) {
179 if (mr.is_empty()) {
180 return;
181 }
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 bool G1SATBCardTableModRefBS::is_in_young(oop obj) const {
219 volatile jbyte* p = byte_for((void*)obj);
220 return *p == g1_young_card_val();
221 }
222
223 void G1SATBCardTableLoggingModRefBS::on_thread_attach(JavaThread* thread) {
224 // This method initializes the SATB and dirty card queues before a
225 // JavaThread is added to the Java thread list. Right now, we don't
226 // have to do anything to the dirty card queue (it should have been
227 // activated when the thread was created), but we have to activate
228 // the SATB queue if the thread is created while a marking cycle is
229 // in progress. The activation / de-activation of the SATB queues at
230 // the beginning / end of a marking cycle is done during safepoints
231 // so we have to make sure this method is called outside one to be
232 // able to safely read the active field of the SATB queue set. Right
233 // now, it is called just before the thread is added to the Java
234 // thread list in the Threads::add() method. That method is holding
235 // the Threads_lock which ensures we are outside a safepoint. We
236 // cannot do the obvious and set the active field of the SATB queue
237 // when the thread is created given that, in some cases, safepoints
238 // might happen between the JavaThread constructor being called and the
239 // thread being added to the Java thread list (an example of this is
240 // when the structure for the DestroyJavaVM thread is created).
241 assert(!SafepointSynchronize::is_at_safepoint(), "We should not be at a safepoint");
242 assert(!thread->satb_mark_queue().is_active(), "SATB queue should not be active");
243 assert(thread->satb_mark_queue().is_empty(), "SATB queue should be empty");
244 assert(thread->dirty_card_queue().is_active(), "Dirty card queue should be active");
245
246 // If we are creating the thread during a marking cycle, we should
247 // set the active field of the SATB queue to true.
248 if (thread->satb_mark_queue_set().is_active()) {
249 thread->satb_mark_queue().set_active(true);
250 }
251 }
252
253 void G1SATBCardTableLoggingModRefBS::on_thread_detach(JavaThread* thread) {
254 // Flush any deferred card marks, SATB buffers and dirty card queue buffers
255 CardTableModRefBS::on_thread_detach(thread);
256 thread->satb_mark_queue().flush();
257 thread->dirty_card_queue().flush();
258 }