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
 23  * questions.
 24  *
 25  */
 26 
 27 #include "precompiled.hpp"
 28 #include "memory/allocation.hpp"
 29 #include "oops/markWord.hpp"
 30 #include "oops/oop.inline.hpp"
 31 #include "runtime/globals.hpp"
 32 #include "runtime/lockStack.inline.hpp"
 33 #include "runtime/objectMonitor.inline.hpp"
 34 #include "runtime/safepoint.hpp"
 35 #include "runtime/stackWatermark.hpp"
 36 #include "runtime/stackWatermarkSet.inline.hpp"
 37 #include "runtime/synchronizer.inline.hpp"
 38 #include "runtime/thread.hpp"
 39 #include "utilities/copy.hpp"
 40 #include "utilities/debug.hpp"
 41 #include "utilities/globalDefinitions.hpp"
 42 #include "utilities/growableArray.hpp"
 43 #include "utilities/ostream.hpp"
 44 #include "utilities/sizes.hpp"
 45 
 46 #include <type_traits>
 47 
 48 const int LockStack::lock_stack_offset =      in_bytes(JavaThread::lock_stack_offset());
 49 const int LockStack::lock_stack_top_offset =  in_bytes(JavaThread::lock_stack_top_offset());
 50 const int LockStack::lock_stack_base_offset = in_bytes(JavaThread::lock_stack_base_offset());
 51 
 52 LockStack::LockStack(JavaThread* jt) :
 53   _top(lock_stack_base_offset), _base() {
 54   // Make sure the layout of the object is compatible with the emitted code's assumptions.
 55   STATIC_ASSERT(sizeof(_bad_oop_sentinel) == oopSize);
 56   STATIC_ASSERT(sizeof(_base[0]) == oopSize);
 57   STATIC_ASSERT(std::is_standard_layout<LockStack>::value);
 58   STATIC_ASSERT(offsetof(LockStack, _bad_oop_sentinel) == offsetof(LockStack, _base) - oopSize);
 59 #ifdef ASSERT
 60   for (int i = 0; i < CAPACITY; i++) {
 61     _base[i] = nullptr;
 62   }
 63 #endif
 64 }
 65 
 66 uint32_t LockStack::start_offset() {
 67   int offset = lock_stack_base_offset;
 68   assert(offset > 0, "must be positive offset");
 69   return static_cast<uint32_t>(offset);
 70 }
 71 
 72 uint32_t LockStack::end_offset() {
 73   int offset = lock_stack_base_offset + CAPACITY * oopSize;
 74   assert(offset > 0, "must be positive offset");
 75   return static_cast<uint32_t>(offset);
 76 }
 77 
 78 #ifndef PRODUCT
 79 void LockStack::verify(const char* msg) const {
 80   assert(LockingMode == LM_LIGHTWEIGHT, "never use lock-stack when light weight locking is disabled");
 81   assert((_top <= end_offset()), "lockstack overflow: _top %d end_offset %d", _top, end_offset());
 82   assert((_top >= start_offset()), "lockstack underflow: _top %d start_offset %d", _top, start_offset());
 83   if (SafepointSynchronize::is_at_safepoint() || (Thread::current()->is_Java_thread() && is_owning_thread())) {
 84     int top = to_index(_top);
 85     for (int i = 0; i < top; i++) {
 86       assert(_base[i] != nullptr, "no zapped before top");
 87       if (VM_Version::supports_recursive_lightweight_locking()) {
 88         oop o = _base[i];
 89         for (; i < top - 1; i++) {
 90           // Consecutive entries may be the same
 91           if (_base[i + 1] != o) {
 92             break;
 93           }
 94         }
 95       }
 96 
 97       for (int j = i + 1; j < top; j++) {
 98         assert(_base[i] != _base[j], "entries must be unique: %s", msg);
 99       }
100     }
101     for (int i = top; i < CAPACITY; i++) {
102       assert(_base[i] == nullptr, "only zapped entries after top: i: %d, top: %d, entry: " PTR_FORMAT, i, top, p2i(_base[i]));
103     }
104   }
105 }
106 #endif
107 
108 void LockStack::print_on(outputStream* st) {
109   for (int i = to_index(_top); (--i) >= 0;) {
110     st->print("LockStack[%d]: ", i);
111     oop o = _base[i];
112     if (oopDesc::is_oop(o)) {
113       o->print_on(st);
114     } else {
115       st->print_cr("not an oop: " PTR_FORMAT, p2i(o));
116     }
117   }
118 }
119 
120 OMCache::OMCache(JavaThread* jt) : _entries() {
121   STATIC_ASSERT(std::is_standard_layout<OMCache>::value);
122   STATIC_ASSERT(std::is_standard_layout<OMCache::OMCacheEntry>::value);
123   STATIC_ASSERT(offsetof(OMCache, _null_sentinel) == offsetof(OMCache, _entries) +
124                 offsetof(OMCache::OMCacheEntry, _oop) +
125                 OMCache::CAPACITY * in_bytes(oop_to_oop_difference()));
126 }