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