1 /*
2 * Copyright (c) 2017, 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.hpp"
30 #include "services/memTracker.hpp"
31 #include <sys/mman.h>
32
33 void SafepointMechanism::pd_initialize() {
34 // No special code needed if we can use SIGTRAP
35 if (ThreadLocalHandshakes && USE_POLL_BIT_ONLY) {
36 default_initialize();
37 return;
38 }
39
40 // Allocate one protected page
41 char* map_address = (char*)MAP_FAILED;
42 const size_t map_size = ThreadLocalHandshakes ? 2 * os::vm_page_size() : os::vm_page_size();
43 const int prot = PROT_READ;
44 const int flags = MAP_PRIVATE | MAP_ANONYMOUS;
45
46 // Use optimized addresses for the polling page,
47 // e.g. map it to a special 32-bit address.
48 if (OptimizePollingPageLocation) {
49 // architecture-specific list of address wishes:
50 char* address_wishes[] = {
51 // AIX: addresses lower than 0x30000000 don't seem to work on AIX.
52 // PPC64: all address wishes are non-negative 32 bit values where
53 // the lower 16 bits are all zero. we can load these addresses
54 // with a single ppc_lis instruction.
55 (char*) 0x30000000, (char*) 0x31000000,
56 (char*) 0x32000000, (char*) 0x33000000,
57 (char*) 0x40000000, (char*) 0x41000000,
58 (char*) 0x42000000, (char*) 0x43000000,
59 (char*) 0x50000000, (char*) 0x51000000,
60 (char*) 0x52000000, (char*) 0x53000000,
61 (char*) 0x60000000, (char*) 0x61000000,
62 (char*) 0x62000000, (char*) 0x63000000
63 };
64 int address_wishes_length = sizeof(address_wishes)/sizeof(char*);
65
66 // iterate over the list of address wishes:
67 for (int i = 0; i < address_wishes_length; i++) {
68 // Try to map with current address wish.
69 // AIX: AIX needs MAP_FIXED if we provide an address and mmap will
70 // fail if the address is already mapped.
71 map_address = (char*) ::mmap(address_wishes[i],
72 map_size, prot,
73 flags | MAP_FIXED,
74 -1, 0);
75 log_debug(os)("SafePoint Polling Page address: %p (wish) => %p",
76 address_wishes[i], map_address);
77
78 if (map_address == address_wishes[i]) {
79 // Map succeeded and map_address is at wished address, exit loop.
80 break;
81 }
82
83 if (map_address != (char*)MAP_FAILED) {
84 // Map succeeded, but polling_page is not at wished address, unmap and continue.
85 ::munmap(map_address, map_size);
86 map_address = (char*)MAP_FAILED;
87 }
88 // Map failed, continue loop.
89 }
90 }
91 if (map_address == (char*)MAP_FAILED) {
92 map_address = (char*) ::mmap(NULL, map_size, prot, flags, -1, 0);
93 }
94 guarantee(map_address != (char*)MAP_FAILED && map_address != NULL,
95 "SafepointMechanism::pd_initialize: failed to allocate polling page");
96 log_info(os)("SafePoint Polling address: " INTPTR_FORMAT, p2i(map_address));
97 os::set_polling_page((address)(map_address));
98
99 // Register polling page with NMT.
100 MemTracker::record_virtual_memory_reserve_and_commit(map_address, map_size, CALLER_PC, mtSafepoint);
101
102 // Use same page for ThreadLocalHandshakes without SIGTRAP
103 if (ThreadLocalHandshakes) {
104 set_uses_thread_local_poll();
105 os::make_polling_page_unreadable();
106 intptr_t bad_page_val = reinterpret_cast<intptr_t>(map_address),
107 good_page_val = bad_page_val + os::vm_page_size();
108 _poll_armed_value = reinterpret_cast<void*>(bad_page_val + poll_bit());
109 _poll_disarmed_value = reinterpret_cast<void*>(good_page_val);
110 }
111 }