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 <sys/mman.h> 31 32 void SafepointMechanism::pd_initialize() { 33 char* map_address = (char*)MAP_FAILED; 34 const size_t page_size = os::vm_page_size(); 35 // Use optimized addresses for the polling page, 36 // e.g. map it to a special 32-bit address. 37 if (OptimizePollingPageLocation) { 38 // architecture-specific list of address wishes: 39 char* address_wishes[] = { 40 // AIX: addresses lower than 0x30000000 don't seem to work on AIX. 41 // PPC64: all address wishes are non-negative 32 bit values where 42 // the lower 16 bits are all zero. we can load these addresses 43 // with a single ppc_lis instruction. 44 (char*) 0x30000000, (char*) 0x31000000, 45 (char*) 0x32000000, (char*) 0x33000000, 46 (char*) 0x40000000, (char*) 0x41000000, 47 (char*) 0x42000000, (char*) 0x43000000, 48 (char*) 0x50000000, (char*) 0x51000000, 49 (char*) 0x52000000, (char*) 0x53000000, 50 (char*) 0x60000000, (char*) 0x61000000, 51 (char*) 0x62000000, (char*) 0x63000000 52 }; 53 int address_wishes_length = sizeof(address_wishes)/sizeof(char*); 54 55 // iterate over the list of address wishes: 56 for (int i = 0; i < address_wishes_length; i++) { 57 // Try to map with current address wish. 58 // AIX: AIX needs MAP_FIXED if we provide an address and mmap will 59 // fail if the address is already mapped. 60 map_address = (char*) ::mmap(address_wishes[i] - (ssize_t)page_size, 61 page_size, PROT_READ, 62 MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, 63 -1, 0); 64 log_debug(os)("SafePoint Polling Page address: %p (wish) => %p", 65 address_wishes[i], map_address + (ssize_t)page_size); 66 67 if (map_address + (ssize_t)page_size == address_wishes[i]) { 68 // Map succeeded and map_address is at wished address, exit loop. 69 break; 70 } 71 72 if (map_address != (char*)MAP_FAILED) { 73 // Map succeeded, but polling_page is not at wished address, unmap and continue. 74 ::munmap(map_address, page_size); 75 map_address = (char*)MAP_FAILED; 76 } 77 // Map failed, continue loop. 78 } 79 } 80 if (map_address == (char*)MAP_FAILED) { 81 map_address = os::reserve_memory(page_size, NULL, page_size); 82 } 83 guarantee(map_address != (char*)MAP_FAILED, "SafepointMechanism::pd_initialize: failed to allocate polling page"); 84 os::set_polling_page((address)(map_address)); 85 }