1 /*

     2  * Copyright (c) 2019, 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 #ifndef OS_BSD_GC_Z_ZBACKINGFILE_BSD_HPP

    25 #define OS_BSD_GC_Z_ZBACKINGFILE_BSD_HPP

    26 

    27 #include "memory/allocation.hpp"

    28 

    29 class ZPhysicalMemory;

    30 

    31 // On macOS, we use a virtual backing file. It is represented by a reserved virtual

    32 // address space, in which we commit physical memory using the mach_vm_map() API.

    33 // The multi-mapping API simply remaps these addresses using mach_vm_remap() into

    34 // the different heap views. This works as-if there was a backing file, it's just

    35 // that the file is represented with memory mappings instead.

    36 

    37 class ZBackingFile {

    38 private:

    39   uintptr_t _base;

    40   size_t    _size;

    41   bool      _initialized;

    42 

    43   bool commit_inner(size_t offset, size_t length);

    44 

    45 public:

    46   ZBackingFile();

    47 

    48   bool is_initialized() const;

    49 

    50   size_t size() const;

    51 

    52   size_t commit(size_t offset, size_t length);

    53   size_t uncommit(size_t offset, size_t length);

    54 

    55   void map(uintptr_t addr, size_t size, uintptr_t offset) const;

    56   void unmap(uintptr_t addr, size_t size) const;

    57 };

    58 

    59 #endif // OS_BSD_GC_Z_ZBACKINGFILE_BSD_HPP