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