1/*
2 * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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23 */
24
25#ifndef SHARE_RUNTIME_SAFEPOINTMECHANISM_HPP
26#define SHARE_RUNTIME_SAFEPOINTMECHANISM_HPP
27
28#include "runtime/globals.hpp"
29#include "utilities/globalDefinitions.hpp"
30#include "utilities/macros.hpp"
31#include "utilities/sizes.hpp"
32
33// This is the abstracted interface for the safepoint implementation
34class SafepointMechanism : public AllStatic {
35 enum PollingType {
36 _global_page_poll,
37 _thread_local_poll
38 };
39 static PollingType _polling_type;
40 static void* _poll_armed_value;
41 static void* _poll_disarmed_value;
42 static void set_uses_thread_local_poll() { _polling_type = _thread_local_poll; }
43
44 static void* poll_armed_value() { return _poll_armed_value; }
45 static void* poll_disarmed_value() { return _poll_disarmed_value; }
46
47 static inline bool local_poll_armed(JavaThread* thread);
48
49 static inline void disarm_local_poll(JavaThread* thread);
50 static inline void disarm_local_poll_release(JavaThread* thread);
51
52 static inline bool local_poll(Thread* thread);
53 static inline bool global_poll();
54
55 static void block_or_handshake(JavaThread *thread);
56 static void block_if_requested_slow(JavaThread *thread);
57
58 static void default_initialize();
59
60 static void pd_initialize() NOT_AIX({ default_initialize(); });
61
62 // By adding 8 to the base address of the protected polling page we can differentiate
63 // between the armed and disarmed value by masking out this bit.
64 const static intptr_t _poll_bit = 8;
65public:
66 static intptr_t poll_bit() { return _poll_bit; }
67
68 static bool uses_global_page_poll() { return _polling_type == _global_page_poll; }
69 static bool uses_thread_local_poll() { return _polling_type == _thread_local_poll; }
70
71 static bool supports_thread_local_poll() {
72#ifdef THREAD_LOCAL_POLL
73 return true;
74#else
75 return false;
76#endif
77 }
78
79 // Call this method to see if this thread should block for a safepoint or process handshake.
80 static inline bool should_block(Thread* thread);
81
82 // Blocks a thread until safepoint/handshake is completed.
83 static inline void block_if_requested(JavaThread* thread);
84
85 // Caller is responsible for using a memory barrier if needed.
86 static inline void arm_local_poll(JavaThread* thread);
87 // Release semantics
88 static inline void arm_local_poll_release(JavaThread* thread);
89 // Optional release
90 static inline void disarm_if_needed(JavaThread* thread, bool memory_order_release);
91
92 // Setup the selected safepoint mechanism
93 static void initialize();
94 static void initialize_header(JavaThread* thread);
95};
96
97#endif // SHARE_RUNTIME_SAFEPOINTMECHANISM_HPP
98