/*

 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "logging/log.hpp"

#include "runtime/globals.hpp"

#include "runtime/os.hpp"

#include "runtime/safepointMechanism.hpp"

void SafepointMechanism::pd_initialize() {

  // Use optimized addresses for the polling page,

  // e.g. map it to a special 32-bit address.

  if (OptimizePollingPageLocation) {

    // architecture-specific list of address wishes:

    char* address_wishes[] = {

        // AIX: addresses lower than 0x30000000 don't seem to work on AIX.

        // PPC64: all address wishes are non-negative 32 bit values where

        // the lower 16 bits are all zero. we can load these addresses

        // with a single ppc_lis instruction.

    };

    // iterate over the list of address wishes:

      // Try to map with current address wish.

      // AIX: AIX needs MAP_FIXED if we provide an address and mmap will

      // fail if the address is already mapped.

      log_debug(os)("SafePoint Polling  Page address: %p (wish) => %p",

      if (map_address + (ssize_t)page_size == address_wishes[i]) {

        // Map succeeded and map_address is at wished address, exit loop.

        break;

      }

        // Map succeeded, but polling_page is not at wished address, unmap and continue.

      }

      // Map failed, continue loop.

    }

  }

    map_address = os::reserve_memory(page_size, NULL, page_size);

  }

  os::set_polling_page((address)(map_address));

}