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.inline.hpp"
  30 #include "utilities/globalDefinitions.hpp"
  31 
  32 SafepointMechanism::PollingType SafepointMechanism::_polling_type = SafepointMechanism::_global_page_poll;
  33 void* SafepointMechanism::_poll_armed_value;
  34 void* SafepointMechanism::_poll_disarmed_value;
  35 
  36 void SafepointMechanism::default_initialize() {
  37   if (ThreadLocalHandshakes) {
  38     set_uses_thread_local_poll();
  39     const size_t page_size = os::vm_page_size();
  40     const size_t allocation_size = 2 * page_size;
  41     char* polling_page = os::reserve_memory(allocation_size, NULL, page_size);
  42     os::commit_memory_or_exit(polling_page, allocation_size, false, "Unable to commit Safepoint polling page");
  43 
  44     char* bad_page  = polling_page;
  45     char* good_page = polling_page + page_size;
  46 
  47     os::protect_memory(bad_page, page_size, os::MEM_PROT_NONE);
  48     os::protect_memory(good_page, page_size, os::MEM_PROT_READ);
  49 
  50     log_info(os)("SafePoint Polling address, bad (protected) page:" INTPTR_FORMAT ", good (unprotected) page:" INTPTR_FORMAT, p2i(bad_page), p2i(good_page));
  51     os::set_polling_page((address)(bad_page));
  52 
  53     intptr_t poll_page_val = reinterpret_cast<intptr_t>(bad_page);
  54     _poll_armed_value = reinterpret_cast<void*>(poll_page_val | poll_bit());
  55     _poll_disarmed_value = good_page;
  56   } else {
  57     const size_t page_size = os::vm_page_size();
  58     char* polling_page = os::reserve_memory(page_size, NULL, page_size);
  59     os::commit_memory_or_exit(polling_page, page_size, false, "Unable to commit Safepoint polling page");
  60     os::protect_memory(polling_page, page_size, os::MEM_PROT_READ);
  61 
  62     log_info(os)("SafePoint Polling address: " INTPTR_FORMAT, p2i(polling_page));
  63     os::set_polling_page((address)(polling_page));
  64   }
  65 }
  66 
  67 void SafepointMechanism::initialize_header(JavaThread* thread) {
  68   disarm_local_poll(thread);
  69 }
  70 
  71 void SafepointMechanism::initialize_serialize_page() {
  72   if (!UseMembar) {
  73     const size_t page_size = os::vm_page_size();
  74     char* serialize_page = os::reserve_memory(page_size, NULL, page_size);
  75     os::commit_memory_or_exit(serialize_page, page_size, false, "Unable to commit memory serialization page");
  76     log_info(os)("Memory Serialize Page address: " INTPTR_FORMAT, p2i(serialize_page));
  77     os::set_memory_serialize_page((address)(serialize_page));
  78   }
  79 }
  80 
  81 void SafepointMechanism::initialize() {
  82   pd_initialize();
  83   initialize_serialize_page();
  84 }