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 #include "precompiled.hpp"
26 #include "logging/log.hpp"
27 #include "runtime/globals.hpp"
28 #include "runtime/os.hpp"
29 #include "runtime/safepointMechanism.inline.hpp"
30 #include "services/memTracker.hpp"
31 #include "utilities/globalDefinitions.hpp"
32
33 SafepointMechanism::PollingType SafepointMechanism::_polling_type = SafepointMechanism::_global_page_poll;
34 void* SafepointMechanism::_poll_armed_value;
35 void* SafepointMechanism::_poll_disarmed_value;
36
default_initialize()37 void SafepointMechanism::default_initialize() {
38 if (ThreadLocalHandshakes) {
39 set_uses_thread_local_poll();
40
41 // Poll bit values
42 intptr_t poll_armed_value = poll_bit();
43 intptr_t poll_disarmed_value = 0;
44
45 #ifdef USE_POLL_BIT_ONLY
46 if (!USE_POLL_BIT_ONLY)
47 #endif
48 {
49 // Polling page
50 const size_t page_size = os::vm_page_size();
51 const size_t allocation_size = 2 * page_size;
52 char* polling_page = os::reserve_memory(allocation_size, NULL, page_size);
53 os::commit_memory_or_exit(polling_page, allocation_size, false, "Unable to commit Safepoint polling page");
54 MemTracker::record_virtual_memory_type((address)polling_page, mtSafepoint);
55
56 char* bad_page = polling_page;
57 char* good_page = polling_page + page_size;
58
59 os::protect_memory(bad_page, page_size, os::MEM_PROT_NONE);
60 os::protect_memory(good_page, page_size, os::MEM_PROT_READ);
61
62 log_info(os)("SafePoint Polling address, bad (protected) page:" INTPTR_FORMAT ", good (unprotected) page:" INTPTR_FORMAT, p2i(bad_page), p2i(good_page));
63 os::set_polling_page((address)(bad_page));
64
65 // Poll address values
66 intptr_t bad_page_val = reinterpret_cast<intptr_t>(bad_page),
67 good_page_val = reinterpret_cast<intptr_t>(good_page);
68 poll_armed_value |= bad_page_val;
69 poll_disarmed_value |= good_page_val;
70 }
71
72 _poll_armed_value = reinterpret_cast<void*>(poll_armed_value);
73 _poll_disarmed_value = reinterpret_cast<void*>(poll_disarmed_value);
74 } else {
75 const size_t page_size = os::vm_page_size();
76 char* polling_page = os::reserve_memory(page_size, NULL, page_size);
77 os::commit_memory_or_exit(polling_page, page_size, false, "Unable to commit Safepoint polling page");
78 os::protect_memory(polling_page, page_size, os::MEM_PROT_READ);
79 MemTracker::record_virtual_memory_type((address)polling_page, mtSafepoint);
80
81 log_info(os)("SafePoint Polling address: " INTPTR_FORMAT, p2i(polling_page));
82 os::set_polling_page((address)(polling_page));
83 }
84 }
85
block_or_handshake(JavaThread * thread)86 void SafepointMechanism::block_or_handshake(JavaThread *thread) {
87 if (global_poll()) {
88 // Any load in ::block must not pass the global poll load.
89 // Otherwise we might load an old safepoint counter (for example).
90 OrderAccess::loadload();
91 SafepointSynchronize::block(thread);
92 }
93 if (uses_thread_local_poll() && thread->has_handshake()) {
94 thread->handshake_process_by_self();
95 }
96 }
97
block_if_requested_slow(JavaThread * thread)98 void SafepointMechanism::block_if_requested_slow(JavaThread *thread) {
99 // Read global poll and has_handshake after local poll
100 OrderAccess::loadload();
101
102 // local poll already checked, if used.
103 block_or_handshake(thread);
104
105 OrderAccess::loadload();
106
107 if (uses_thread_local_poll() && local_poll_armed(thread)) {
108 disarm_local_poll_release(thread);
109 // We might have disarmed next safepoint/handshake
110 OrderAccess::storeload();
111 if (global_poll() || thread->has_handshake()) {
112 arm_local_poll(thread);
113 }
114 }
115
116 OrderAccess::cross_modify_fence();
117 }
118
initialize_header(JavaThread * thread)119 void SafepointMechanism::initialize_header(JavaThread* thread) {
120 disarm_local_poll(thread);
121 }
122
initialize()123 void SafepointMechanism::initialize() {
124 pd_initialize();
125 }
126