1 /*
2 * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2017, 2022, Red Hat, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
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24 */
25
26 #include "code/codeCache.hpp"
27 #include "code/nmethod.hpp"
28 #include "gc/shared/classUnloadingContext.hpp"
29 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahNMethod.inline.hpp"
32 #include "gc/shenandoah/shenandoahStackWatermark.hpp"
33 #include "gc/shenandoah/shenandoahUtils.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "memory/universe.hpp"
36 #include "runtime/atomicAccess.hpp"
37 #include "utilities/powerOfTwo.hpp"
38
39
40 ShenandoahNMethodTable* ShenandoahCodeRoots::_nmethod_table;
41 int ShenandoahCodeRoots::_disarmed_value = 1;
42
43 void ShenandoahCodeRoots::initialize() {
44 _nmethod_table = new ShenandoahNMethodTable();
45 }
46
47 void ShenandoahCodeRoots::register_nmethod(nmethod* nm) {
48 assert(CodeCache_lock->owned_by_self(), "Must have CodeCache_lock held");
49 _nmethod_table->register_nmethod(nm);
50 }
51
52 void ShenandoahCodeRoots::unregister_nmethod(nmethod* nm) {
53 assert_locked_or_safepoint(CodeCache_lock);
54 _nmethod_table->unregister_nmethod(nm);
55 }
56
57 void ShenandoahCodeRoots::arm_nmethods() {
58 BarrierSet::barrier_set()->barrier_set_nmethod()->arm_all_nmethods();
59
60 // nmethod entry barriers are used to update nmethods. In order to guarantee
61 // that nmethod execution is not interleaved with nmethod entry barrier fixups,
62 // we need to also activate stack watermark machinery.
63 ShenandoahStackWatermark::change_epoch_id();
64 }
65
66 class ShenandoahNMethodUnlinkClosure : public NMethodClosure {
67 private:
68 bool _unloading_occurred;
69 ShenandoahHeap* const _heap;
70 BarrierSetNMethod* const _bs;
71
72 public:
73 ShenandoahNMethodUnlinkClosure(bool unloading_occurred) :
74 _unloading_occurred(unloading_occurred),
75 _heap(ShenandoahHeap::heap()),
76 _bs(ShenandoahBarrierSet::barrier_set()->barrier_set_nmethod()) {}
77
78 virtual void do_nmethod(nmethod* nm) {
79 assert(_heap->is_concurrent_weak_root_in_progress(), "Only this phase");
80
81 ShenandoahNMethod* nm_data = ShenandoahNMethod::gc_data(nm);
82 assert(!nm_data->is_unregistered(), "Should not see unregistered entry");
83
84 if (nm->is_unloading()) {
85 ShenandoahNMethodLocker locker(nm_data->lock());
86 nm->unlink();
87 return;
88 }
89
90 if (_heap->is_evacuation_in_progress()) {
91 ShenandoahNMethodLocker locker(nm_data->lock());
92
93 // Heal oops
94 if (_bs->is_armed(nm)) {
95 ShenandoahNMethod::heal_nmethod_metadata(nm_data);
96 // Must remain armed to complete remaining work in nmethod entry barrier
97 assert(_bs->is_armed(nm), "Should remain armed");
98 }
99 }
100
101 // Clear compiled ICs and exception caches
102 ShenandoahNMethodLocker locker(nm_data->ic_lock());
103 nm->unload_nmethod_caches(_unloading_occurred);
104 }
105 };
106
107 class ShenandoahUnlinkTask : public WorkerTask {
108 private:
109 ShenandoahNMethodUnlinkClosure _cl;
110 ShenandoahConcurrentNMethodIterator _iterator;
111
112 public:
113 ShenandoahUnlinkTask(bool unloading_occurred) :
114 WorkerTask("Shenandoah Unlink NMethods"),
115 _cl(unloading_occurred),
116 _iterator(ShenandoahCodeRoots::table()) {}
117
118 virtual void work(uint worker_id) {
119 _iterator.nmethods_do(&_cl);
120 }
121 };
122
123 void ShenandoahCodeRoots::unlink(WorkerThreads* workers, bool unloading_occurred) {
124 assert(ShenandoahHeap::heap()->unload_classes(), "Only when running concurrent class unloading");
125
126 ShenandoahUnlinkTask task(unloading_occurred);
127 workers->run_task(&task);
128 }
129
130 void ShenandoahCodeRoots::purge() {
131 assert(ShenandoahHeap::heap()->unload_classes(), "Only when running concurrent class unloading");
132
133 ClassUnloadingContext::context()->purge_and_free_nmethods();
134 }
135
136 ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
137 _table_snapshot(nullptr) {
138 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
139 MutexLocker locker(CodeCache_lock, Mutex::_no_safepoint_check_flag);
140 _table_snapshot = ShenandoahCodeRoots::table()->snapshot_for_iteration();
141 }
142
143 ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
144 MonitorLocker locker(CodeCache_lock, Mutex::_no_safepoint_check_flag);
145 ShenandoahCodeRoots::table()->finish_iteration(_table_snapshot);
146 _table_snapshot = nullptr;
147 locker.notify_all();
148 }
149
150 void ShenandoahCodeRootsIterator::possibly_parallel_nmethods_do(NMethodClosure *f) {
151 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
152 assert(_table_snapshot != nullptr, "Sanity");
153 _table_snapshot->parallel_nmethods_do(f);
154 }