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. 8 * 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. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 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 34 class 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 bool local_poll(Thread* thread); 50 static inline bool global_poll(); 51 52 static inline void block_if_requested_local_poll(JavaThread *thread); 53 54 static void default_initialize(); 55 56 static void pd_initialize() NOT_AIX({ default_initialize(); }); 57 58 // By adding 8 to the base address of the protected polling page we can differentiate 59 // between the armed and disarmed value by masking out this bit. 60 const static intptr_t _poll_bit = 8; 61 public: 62 static intptr_t poll_bit() { return _poll_bit; } 63 64 static bool uses_global_page_poll() { return _polling_type == _global_page_poll; } 65 static bool uses_thread_local_poll() { return _polling_type == _thread_local_poll; } 66 67 static bool supports_thread_local_poll() { 68 #ifdef THREAD_LOCAL_POLL 69 return true; 70 #else 71 return false; 72 #endif 73 } 74 75 // Call this method to see if this thread should block for a safepoint. 76 static inline bool should_block(Thread* thread); 77 78 // Blocks a thread until safepoint is completed 79 static inline void block_if_requested(JavaThread* thread); 80 81 // Caller is responsible for using a memory barrier if needed. 82 static inline void arm_local_poll(JavaThread* thread); 83 static inline void disarm_local_poll(JavaThread* thread); 84 85 static inline void arm_local_poll_release(JavaThread* thread); 86 static inline void disarm_local_poll_release(JavaThread* thread); 87 88 // Setup the selected safepoint mechanism 89 static void initialize(); 90 static void initialize_header(JavaThread* thread); 91 }; 92 93 #endif // SHARE_RUNTIME_SAFEPOINTMECHANISM_HPP