1 /*
2 * Copyright (c) 2014, 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.
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
27
28 #include "memory/allocation.hpp"
29 #include "memory/memRegion.hpp"
30 #include "runtime/virtualspace.hpp"
31 #include "utilities/bitMap.hpp"
32
33 // Virtual space management helper for a virtual space with an OS page allocation
34 // granularity.
35 // (De-)Allocation requests are always OS page aligned by passing a page index
36 // and multiples of pages.
37 // We only support reservations which base address is aligned to a given commit
38 // size. The length of the area managed need not commit size aligned (but OS default
39 // page size aligned) because some OSes cannot provide a an os_commit_size aligned
40 // reservation without also being size-aligned. Any tail area is committed using OS
41 // small pages.
42 // The implementation gives an error when trying to commit or uncommit pages that
43 // have already been committed or uncommitted.
44 class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
45 friend class VMStructs;
46 private:
47 // Reserved area addresses.
48 char* _low_boundary;
49 char* _high_boundary;
50
51 // The preferred commit/uncommit granularity in bytes.
52 size_t _commit_size;
53
54 // Bitmap used for verification of commit/uncommit operations.
55 BitMap _committed;
56
57 // Bitmap used to keep track of which pages are dirty or not for _special
58 // spaces. This is needed because for those spaces the underlying memory
59 // will only be zero filled the first time it is committed. Calls to commit
60 // will use this bitmap and return whether or not the memory is zero filled.
61 BitMap _dirty;
62
63 // Indicates that the entire space has been committed and pinned in memory,
64 // os::commit_memory() or os::uncommit_memory() have no function.
65 bool _special;
66
67 // Indicates whether the committed space should be executable.
68 bool _executable;
69
70 // Commit the given memory range by using _commit_size pages as much as possible
71 // and the remainder with small sized pages. The start address must be _commit_size
72 // aligned.
73 void commit_int(char* start, char* end);
74 // Uncommit the given memory range.
75 void uncommit_int(char* start, char* end);
76
77 // Returns the index of the page which contains the given address.
78 uintptr_t addr_to_page_index(char* addr) const;
79 // Returns the address of the given page index.
80 char* page_start(uintptr_t index);
81 // Returns the address of the given page index ranging from 0..size_in_pages-1.
82 char* page_end(uintptr_t index);
83
84 // Returns true if the entire area is backed by committed memory.
85 bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
86 // Returns true if the entire area is not backed by committed memory.
87 bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
88
89 public:
90
91 // Commit the given area of pages starting at start being size_in_pages large.
92 // Returns true if the given area is zero filled upon completion.
93 bool commit(uintptr_t start, size_t size_in_pages);
94
95 // Uncommit the given area of pages starting at start being size_in_pages large.
96 void uncommit(uintptr_t start, size_t size_in_pages);
97
98 // Initialization
99 G1PageBasedVirtualSpace();
100 // Initialize the given reserved space with the given base address and actual size.
101 // Prefer to commit in commit_size chunks.
102 bool initialize_with_granularity(ReservedSpace rs, size_t actual_size, size_t commit_size);
103
104 // Destruction
105 ~G1PageBasedVirtualSpace();
106
107 // Amount of reserved memory.
108 size_t reserved_size() const;
109 // Memory used in this virtual space.
110 size_t committed_size() const;
111 // Memory left to use/expand in this virtual space.
112 size_t uncommitted_size() const;
113
114 bool contains(const void* p) const;
115
116 MemRegion reserved() {
117 MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
118 return x;
119 }
120
121 void release();
122
123 void check_for_contiguity() PRODUCT_RETURN;
124
125 // Debugging
126 void print_on(outputStream* out) PRODUCT_RETURN;
127 void print();
128 };
129
130 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP