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