112 lines
4.5 KiB
C++
112 lines
4.5 KiB
C++
/*
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* Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "logging/log.hpp"
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#include "runtime/globals.hpp"
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#include "runtime/os.hpp"
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#include "runtime/safepointMechanism.hpp"
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#include "services/memTracker.hpp"
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#include <sys/mman.h>
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void SafepointMechanism::pd_initialize() {
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// No special code needed if we can use SIGTRAP
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if (ThreadLocalHandshakes && USE_POLL_BIT_ONLY) {
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default_initialize();
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return;
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}
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// Allocate one protected page
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char* map_address = (char*)MAP_FAILED;
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const size_t map_size = ThreadLocalHandshakes ? 2 * os::vm_page_size() : os::vm_page_size();
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const int prot = PROT_READ;
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const int flags = MAP_PRIVATE | MAP_ANONYMOUS;
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// Use optimized addresses for the polling page,
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// e.g. map it to a special 32-bit address.
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if (OptimizePollingPageLocation) {
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// architecture-specific list of address wishes:
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char* address_wishes[] = {
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// AIX: addresses lower than 0x30000000 don't seem to work on AIX.
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// PPC64: all address wishes are non-negative 32 bit values where
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// the lower 16 bits are all zero. we can load these addresses
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// with a single ppc_lis instruction.
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(char*) 0x30000000, (char*) 0x31000000,
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(char*) 0x32000000, (char*) 0x33000000,
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(char*) 0x40000000, (char*) 0x41000000,
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(char*) 0x42000000, (char*) 0x43000000,
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(char*) 0x50000000, (char*) 0x51000000,
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(char*) 0x52000000, (char*) 0x53000000,
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(char*) 0x60000000, (char*) 0x61000000,
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(char*) 0x62000000, (char*) 0x63000000
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};
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int address_wishes_length = sizeof(address_wishes)/sizeof(char*);
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// iterate over the list of address wishes:
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for (int i = 0; i < address_wishes_length; i++) {
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// Try to map with current address wish.
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// AIX: AIX needs MAP_FIXED if we provide an address and mmap will
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// fail if the address is already mapped.
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map_address = (char*) ::mmap(address_wishes[i],
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map_size, prot,
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flags | MAP_FIXED,
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-1, 0);
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log_debug(os)("SafePoint Polling Page address: %p (wish) => %p",
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address_wishes[i], map_address);
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if (map_address == address_wishes[i]) {
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// Map succeeded and map_address is at wished address, exit loop.
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break;
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}
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if (map_address != (char*)MAP_FAILED) {
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// Map succeeded, but polling_page is not at wished address, unmap and continue.
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::munmap(map_address, map_size);
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map_address = (char*)MAP_FAILED;
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}
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// Map failed, continue loop.
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}
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}
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if (map_address == (char*)MAP_FAILED) {
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map_address = (char*) ::mmap(NULL, map_size, prot, flags, -1, 0);
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}
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guarantee(map_address != (char*)MAP_FAILED && map_address != NULL,
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"SafepointMechanism::pd_initialize: failed to allocate polling page");
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log_info(os)("SafePoint Polling address: " INTPTR_FORMAT, p2i(map_address));
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os::set_polling_page((address)(map_address));
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// Register polling page with NMT.
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MemTracker::record_virtual_memory_reserve_and_commit(map_address, map_size, CALLER_PC, mtSafepoint);
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// Use same page for ThreadLocalHandshakes without SIGTRAP
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if (ThreadLocalHandshakes) {
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set_uses_thread_local_poll();
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os::make_polling_page_unreadable();
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intptr_t bad_page_val = reinterpret_cast<intptr_t>(map_address),
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good_page_val = bad_page_val + os::vm_page_size();
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_poll_armed_value = reinterpret_cast<void*>(bad_page_val + poll_bit());
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_poll_disarmed_value = reinterpret_cast<void*>(good_page_val);
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}
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}
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