1 /*
2 * Copyright (c) 1997, 2025, 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 "gc/shared/barrierSet.hpp"
26 #include "gc/shared/barrierSetAssembler.hpp"
27 #include "gc/shared/barrierSetNMethod.hpp"
28 #include "gc/shared/barrierSetStackChunk.hpp"
29 #include "runtime/continuation.hpp"
30 #include "runtime/javaThread.hpp"
31 #include "utilities/debug.hpp"
32 #include "utilities/macros.hpp"
33
34 BarrierSet* BarrierSet::_barrier_set = nullptr;
35
36 void BarrierSet::set_barrier_set(BarrierSet* barrier_set) {
37 assert(_barrier_set == nullptr, "Already initialized");
38 _barrier_set = barrier_set;
39
40 // Notify barrier set of the current (main) thread. Normally the
41 // Thread constructor deals with this, but the main thread is
42 // created before we get here. Verify it isn't yet on the thread
43 // list, else we'd also need to call BarrierSet::on_thread_attach.
44 // This is the only thread that can exist at this point; the Thread
45 // constructor objects to other threads being created before the
46 // barrier set is available.
47 assert(Thread::current()->is_Java_thread(),
48 "Expected main thread to be a JavaThread");
49 assert(!JavaThread::current()->on_thread_list(),
50 "Main thread already on thread list.");
51 _barrier_set->on_thread_create(Thread::current());
52 }
53
54 static BarrierSetNMethod* select_barrier_set_nmethod(BarrierSetNMethod* barrier_set_nmethod) {
55 if (barrier_set_nmethod != nullptr) {
56 // The GC needs nmethod entry barriers to do concurrent GC
57 return barrier_set_nmethod;
58 } else {
59 // The GC needs nmethod entry barriers to deal with continuations
60 // and code cache unloading
61 return new BarrierSetNMethod();
62 }
63 }
64
65 static BarrierSetStackChunk* select_barrier_set_stack_chunk(BarrierSetStackChunk* barrier_set_stack_chunk) {
66 if (barrier_set_stack_chunk != nullptr) {
67 return barrier_set_stack_chunk;
68 } else {
69 return new BarrierSetStackChunk();
70 }
71 }
72
73 BarrierSet::BarrierSet(BarrierSetAssembler* barrier_set_assembler,
74 BarrierSetC1* barrier_set_c1,
75 BarrierSetC2* barrier_set_c2,
76 BarrierSetNMethod* barrier_set_nmethod,
77 BarrierSetStackChunk* barrier_set_stack_chunk,
78 const FakeRtti& fake_rtti) :
79 _fake_rtti(fake_rtti),
80 _barrier_set_assembler(barrier_set_assembler),
81 _barrier_set_c1(barrier_set_c1),
82 _barrier_set_c2(barrier_set_c2),
83 _barrier_set_nmethod(select_barrier_set_nmethod(barrier_set_nmethod)),
84 _barrier_set_stack_chunk(select_barrier_set_stack_chunk(barrier_set_stack_chunk)) {
85 }
86
87 void BarrierSet::on_thread_attach(Thread* thread) {
88 BarrierSetNMethod* bs_nm = barrier_set_nmethod();
89 thread->set_nmethod_disarmed_guard_value(bs_nm->disarmed_guard_value());
90 }
91
92 // Called from init.cpp
93 void gc_barrier_stubs_init() {
94 BarrierSet* bs = BarrierSet::barrier_set();
95 #ifndef ZERO
96 BarrierSetAssembler* bs_assembler = bs->barrier_set_assembler();
97 bs_assembler->barrier_stubs_init();
98 #endif
99 }