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.
23 *
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 class ShenandoahNMethodUnlinkClosure : public NMethodClosure {
58 private:
59 bool _unloading_occurred;
60 ShenandoahHeap* const _heap;
61 BarrierSetNMethod* const _bs;
62
63 public:
64 ShenandoahNMethodUnlinkClosure(bool unloading_occurred) :
65 _unloading_occurred(unloading_occurred),
66 _heap(ShenandoahHeap::heap()),
67 _bs(ShenandoahBarrierSet::barrier_set()->barrier_set_nmethod()) {}
68
69 virtual void do_nmethod(nmethod* nm) {
70 assert(_heap->is_concurrent_weak_root_in_progress(), "Only this phase");
71
72 ShenandoahNMethod* nm_data = ShenandoahNMethod::gc_data(nm);
73 assert(!nm_data->is_unregistered(), "Should not see unregistered entry");
74
75 if (nm->is_unloading()) {
76 ShenandoahNMethodLocker locker(nm_data->lock());
77 nm->unlink();
78 return;
79 }
80
81 if (_heap->is_evacuation_in_progress()) {
82 ShenandoahNMethodLocker locker(nm_data->lock());
83
84 // Heal oops
85 if (_bs->is_armed(nm)) {
86 ShenandoahNMethod::heal_nmethod_metadata(nm_data);
87 // Must remain armed to complete remaining work in nmethod entry barrier
88 assert(_bs->is_armed(nm), "Should remain armed");
89 }
90 }
91
92 // Clear compiled ICs and exception caches
93 ShenandoahNMethodLocker locker(nm_data->ic_lock());
94 nm->unload_nmethod_caches(_unloading_occurred);
95 }
96 };
97
98 class ShenandoahUnlinkTask : public WorkerTask {
99 private:
100 ShenandoahNMethodUnlinkClosure _cl;
101 ShenandoahConcurrentNMethodIterator _iterator;
102
103 public:
104 ShenandoahUnlinkTask(bool unloading_occurred) :
105 WorkerTask("Shenandoah Unlink NMethods"),
106 _cl(unloading_occurred),
107 _iterator(ShenandoahCodeRoots::table()) {}
108
109 virtual void work(uint worker_id) {
110 _iterator.nmethods_do(&_cl);
111 }
112 };
113
114 void ShenandoahCodeRoots::unlink(WorkerThreads* workers, bool unloading_occurred) {
115 assert(ShenandoahHeap::heap()->unload_classes(), "Only when running concurrent class unloading");
116
117 ShenandoahUnlinkTask task(unloading_occurred);
118 workers->run_task(&task);
119 }
120
121 void ShenandoahCodeRoots::purge() {
122 assert(ShenandoahHeap::heap()->unload_classes(), "Only when running concurrent class unloading");
123
124 ClassUnloadingContext::context()->purge_and_free_nmethods();
125 }
126
127 ShenandoahCodeRootsIterator::ShenandoahCodeRootsIterator() :
128 _table_snapshot(nullptr) {
129 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
130 MutexLocker locker(CodeCache_lock, Mutex::_no_safepoint_check_flag);
131 _table_snapshot = ShenandoahCodeRoots::table()->snapshot_for_iteration();
132 }
133
134 ShenandoahCodeRootsIterator::~ShenandoahCodeRootsIterator() {
135 MonitorLocker locker(CodeCache_lock, Mutex::_no_safepoint_check_flag);
136 ShenandoahCodeRoots::table()->finish_iteration(_table_snapshot);
137 _table_snapshot = nullptr;
138 locker.notify_all();
139 }
140
141 void ShenandoahCodeRootsIterator::possibly_parallel_nmethods_do(NMethodClosure *f) {
142 assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint");
143 assert(_table_snapshot != nullptr, "Sanity");
144 _table_snapshot->parallel_nmethods_do(f);
145 }