1 /*
2 * Copyright (c) 2022, Red Hat, Inc. All rights reserved.
3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
4 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 *
7 * This code is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 only, as
9 * published by the Free Software Foundation.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
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25 */
26
27 #ifndef SHARE_RUNTIME_LOCKSTACK_INLINE_HPP
28 #define SHARE_RUNTIME_LOCKSTACK_INLINE_HPP
29
30 #include "runtime/lockStack.hpp"
31
32 #include "memory/iterator.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/globals.hpp"
35 #include "runtime/javaThread.hpp"
36 #include "runtime/lightweightSynchronizer.hpp"
37 #include "runtime/objectMonitor.inline.hpp"
38 #include "runtime/safepoint.hpp"
39 #include "runtime/stackWatermark.hpp"
40 #include "runtime/stackWatermarkSet.inline.hpp"
41 #include "runtime/synchronizer.hpp"
42 #include "utilities/align.hpp"
43 #include "utilities/globalDefinitions.hpp"
44
45 inline int LockStack::to_index(uint32_t offset) {
46 assert(is_aligned(offset, oopSize), "Bad alignment: %u", offset);
47 assert((offset <= end_offset()), "lockstack overflow: offset %d end_offset %d", offset, end_offset());
48 assert((offset >= start_offset()), "lockstack underflow: offset %d start_offset %d", offset, start_offset());
49 return (offset - lock_stack_base_offset) / oopSize;
50 }
51
52 JavaThread* LockStack::get_thread() const {
53 char* addr = reinterpret_cast<char*>(const_cast<LockStack*>(this));
54 return reinterpret_cast<JavaThread*>(addr - lock_stack_offset);
55 }
56
57 inline bool LockStack::is_full() const {
58 return to_index(_top) == CAPACITY;
59 }
60
61 inline bool LockStack::can_push(int n) const {
62 return (CAPACITY - to_index(_top)) >= n;
63 }
64
65 inline bool LockStack::is_owning_thread() const {
66 Thread* current = Thread::current();
67 if (current->is_Java_thread()) {
68 JavaThread* thread = JavaThread::cast(current);
69 bool is_owning = &thread->lock_stack() == this;
70 assert(is_owning == (get_thread() == thread), "is_owning sanity");
71 return is_owning;
72 }
73 return false;
74 }
75
76 inline void LockStack::push(oop o) {
77 verify("pre-push");
78 assert(oopDesc::is_oop(o), "must be");
79 assert(!contains(o), "entries must be unique");
80 assert(!is_full(), "must have room");
81 assert(_base[to_index(_top)] == nullptr, "expect zapped entry");
82 _base[to_index(_top)] = o;
83 _top += oopSize;
84 verify("post-push");
85 }
86
87 inline oop LockStack::bottom() const {
88 assert(to_index(_top) > 0, "must contain an oop");
89 return _base[0];
90 }
91
92 inline oop LockStack::top() {
93 assert(to_index(_top) > 0, "may only call with at least one element in the stack");
94 return _base[to_index(_top) - 1];
95 }
96
97 inline bool LockStack::is_empty() const {
98 return to_index(_top) == 0;
99 }
100
101 inline bool LockStack::is_recursive(oop o) const {
102 if (!VM_Version::supports_recursive_lightweight_locking()) {
103 return false;
104 }
105 verify("pre-is_recursive");
106
107 // This will succeed iff there is a consecutive run of oops on the
108 // lock-stack with a length of at least 2.
109
110 assert(contains(o), "at least one entry must exist");
111 int end = to_index(_top);
112 // Start iterating from the top because the runtime code is more
113 // interested in the balanced locking case when the top oop on the
114 // lock-stack matches o. This will cause the for loop to break out
115 // in the first loop iteration if it is non-recursive.
116 for (int i = end - 1; i > 0; i--) {
117 if (_base[i - 1] == o && _base[i] == o) {
118 verify("post-is_recursive");
119 return true;
120 }
121 if (_base[i] == o) {
122 // o can only occur in one consecutive run on the lock-stack.
123 // Only one of the two oops checked matched o, so this run
124 // must be of length 1 and thus not be recursive. Stop the search.
125 break;
126 }
127 }
128
129 verify("post-is_recursive");
130 return false;
131 }
132
133 inline bool LockStack::try_recursive_enter(oop o) {
134 if (!VM_Version::supports_recursive_lightweight_locking()) {
135 return false;
136 }
137 verify("pre-try_recursive_enter");
138
139 // This will succeed iff the top oop on the stack matches o.
140 // When successful o will be pushed to the lock-stack creating
141 // a consecutive run at least 2 oops that matches o on top of
142 // the lock-stack.
143
144 assert(!is_full(), "precond");
145
146 int end = to_index(_top);
147 if (end == 0 || _base[end - 1] != o) {
148 // Topmost oop does not match o.
149 verify("post-try_recursive_enter");
150 return false;
151 }
152
153 _base[end] = o;
154 _top += oopSize;
155 verify("post-try_recursive_enter");
156 return true;
157 }
158
159 inline bool LockStack::try_recursive_exit(oop o) {
160 if (!VM_Version::supports_recursive_lightweight_locking()) {
161 return false;
162 }
163 verify("pre-try_recursive_exit");
164
165 // This will succeed iff the top two oops on the stack matches o.
166 // When successful the top oop will be popped of the lock-stack.
167 // When unsuccessful the lock may still be recursive, in which
168 // case the locking is unbalanced. This case is handled externally.
169
170 assert(contains(o), "entries must exist");
171
172 int end = to_index(_top);
173 if (end <= 1 || _base[end - 1] != o || _base[end - 2] != o) {
174 // The two topmost oops do not match o.
175 verify("post-try_recursive_exit");
176 return false;
177 }
178
179 _top -= oopSize;
180 DEBUG_ONLY(_base[to_index(_top)] = nullptr;)
181 verify("post-try_recursive_exit");
182 return true;
183 }
184
185 inline size_t LockStack::remove(oop o) {
186 verify("pre-remove");
187 assert(contains(o), "entry must be present: " PTR_FORMAT, p2i(o));
188
189 int end = to_index(_top);
190 int inserted = 0;
191 for (int i = 0; i < end; i++) {
192 if (_base[i] != o) {
193 if (inserted != i) {
194 _base[inserted] = _base[i];
195 }
196 inserted++;
197 }
198 }
199
200 #ifdef ASSERT
201 for (int i = inserted; i < end; i++) {
202 _base[i] = nullptr;
203 }
204 #endif
205
206 uint32_t removed = end - inserted;
207 _top -= removed * oopSize;
208 assert(!contains(o), "entry must have been removed: " PTR_FORMAT, p2i(o));
209 verify("post-remove");
210 return removed;
211 }
212
213 inline bool LockStack::contains(oop o) const {
214 verify("pre-contains");
215
216 // Can't poke around in thread oops without having started stack watermark processing.
217 assert(StackWatermarkSet::processing_started(get_thread()), "Processing must have started!");
218
219 int end = to_index(_top);
220 for (int i = end - 1; i >= 0; i--) {
221 if (_base[i] == o) {
222 verify("post-contains");
223 return true;
224 }
225 }
226 verify("post-contains");
227 return false;
228 }
229
230 inline void LockStack::oops_do(OopClosure* cl) {
231 verify("pre-oops-do");
232 int end = to_index(_top);
233 for (int i = 0; i < end; i++) {
234 cl->do_oop(&_base[i]);
235 }
236 verify("post-oops-do");
237 }
238
239 inline void OMCache::set_monitor(ObjectMonitor *monitor) {
240 const int end = OMCacheSize - 1;
241 if (end < 0) {
242 return;
243 }
244
245 oop obj = monitor->object_peek();
246 assert(obj != nullptr, "must be alive");
247 assert(monitor == LightweightSynchronizer::read_monitor(JavaThread::current(), obj), "must be exist in table");
248
249 OMCacheEntry to_insert = {obj, monitor};
250
251 for (int i = 0; i < end; ++i) {
252 if (_entries[i]._oop == obj ||
253 _entries[i]._monitor == nullptr ||
254 _entries[i]._monitor->is_being_async_deflated()) {
255 // Use stale slot.
256 _entries[i] = to_insert;
257 return;
258 }
259 // Swap with the most recent value.
260 ::swap(to_insert, _entries[i]);
261 }
262 _entries[end] = to_insert;
263 }
264
265 inline ObjectMonitor* OMCache::get_monitor(oop o) {
266 for (int i = 0; i < OMCacheSize; ++i) {
267 if (_entries[i]._oop == o) {
268 assert(_entries[i]._monitor != nullptr, "monitor must exist");
269 if (_entries[i]._monitor->is_being_async_deflated()) {
270 // Bad monitor
271 // Shift down rest
272 for (; i < OMCacheSize - 1; ++i) {
273 _entries[i] = _entries[i + 1];
274 }
275 // Clear end
276 _entries[i] = {};
277 return nullptr;
278 }
279 return _entries[i]._monitor;
280 }
281 }
282 return nullptr;
283 }
284
285 inline void OMCache::clear() {
286 for (size_t i = 0 , r = 0; i < CAPACITY; ++i) {
287 // Clear
288 _entries[i] = {};
289 }
290 }
291
292 #endif // SHARE_RUNTIME_LOCKSTACK_INLINE_HPP