1 /*
2 * Copyright (c) 2019, 2020, 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 "memory/archiveUtils.hpp"
27 #include "memory/metaspace.hpp"
28 #include "utilities/bitMap.inline.hpp"
29
30 #if INCLUDE_CDS
31
32 CHeapBitMap* ArchivePtrMarker::_ptrmap = NULL;
33 address* ArchivePtrMarker::_ptr_base;
34 address* ArchivePtrMarker::_ptr_end;
35 bool ArchivePtrMarker::_compacted;
36
37 void ArchivePtrMarker::initialize(CHeapBitMap* ptrmap, address* ptr_base, address* ptr_end) {
38 assert(_ptrmap == NULL, "initialize only once");
39 _ptr_base = ptr_base;
40 _ptr_end = ptr_end;
41 _compacted = false;
42 _ptrmap = ptrmap;
43
44 // Use this as initial guesstimate. We should need less space in the
45 // archive, but if we're wrong the bitmap will be expanded automatically.
46 size_t estimated_archive_size = MetaspaceGC::capacity_until_GC();
47 // But set it smaller in debug builds so we always test the expansion code.
48 // (Default archive is about 12MB).
49 DEBUG_ONLY(estimated_archive_size = 6 * M);
50
51 // We need one bit per pointer in the archive.
52 _ptrmap->initialize(estimated_archive_size / sizeof(intptr_t));
53 }
54
55 void ArchivePtrMarker::mark_pointer(address* ptr_loc) {
56 assert(_ptrmap != NULL, "not initialized");
57 assert(!_compacted, "cannot mark anymore");
58
59 if (_ptr_base <= ptr_loc && ptr_loc < _ptr_end) {
60 address value = *ptr_loc;
61 // We don't want any pointer that points to very bottom of the archive, otherwise when
62 // MetaspaceShared::default_base_address()==0, we can't distinguish between a pointer
63 // to nothing (NULL) vs a pointer to an objects that happens to be at the very bottom
64 // of the archive.
65 assert(value != (address)_ptr_base, "don't point to the bottom of the archive");
66
67 if (value != NULL) {
68 assert(uintx(ptr_loc) % sizeof(intptr_t) == 0, "pointers must be stored in aligned addresses");
69 size_t idx = ptr_loc - _ptr_base;
70 if (_ptrmap->size() <= idx) {
71 _ptrmap->resize((idx + 1) * 2);
72 }
73 assert(idx < _ptrmap->size(), "must be");
74 _ptrmap->set_bit(idx);
75 //tty->print_cr("Marking pointer [%p] -> %p @ " SIZE_FORMAT_W(9), ptr_loc, *ptr_loc, idx);
76 }
77 }
78 }
79
80 class ArchivePtrBitmapCleaner: public BitMapClosure {
81 CHeapBitMap* _ptrmap;
82 address* _ptr_base;
83 address _relocatable_base;
84 address _relocatable_end;
85 size_t _max_non_null_offset;
86
87 public:
88 ArchivePtrBitmapCleaner(CHeapBitMap* ptrmap, address* ptr_base, address relocatable_base, address relocatable_end) :
89 _ptrmap(ptrmap), _ptr_base(ptr_base),
90 _relocatable_base(relocatable_base), _relocatable_end(relocatable_end), _max_non_null_offset(0) {}
91
92 bool do_bit(size_t offset) {
93 address* ptr_loc = _ptr_base + offset;
94 address ptr_value = *ptr_loc;
95 if (ptr_value != NULL) {
96 assert(_relocatable_base <= ptr_value && ptr_value < _relocatable_end, "do not point to arbitrary locations!");
97 if (_max_non_null_offset < offset) {
98 _max_non_null_offset = offset;
99 }
100 } else {
101 _ptrmap->clear_bit(offset);
102 DEBUG_ONLY(log_trace(cds, reloc)("Clearing pointer [" PTR_FORMAT "] -> NULL @ " SIZE_FORMAT_W(9), p2i(ptr_loc), offset));
103 }
104
105 return true;
106 }
107
108 size_t max_non_null_offset() const { return _max_non_null_offset; }
109 };
110
111 void ArchivePtrMarker::compact(address relocatable_base, address relocatable_end) {
112 assert(!_compacted, "cannot compact again");
113 ArchivePtrBitmapCleaner cleaner(_ptrmap, _ptr_base, relocatable_base, relocatable_end);
114 _ptrmap->iterate(&cleaner);
115 compact(cleaner.max_non_null_offset());
116 }
117
118 void ArchivePtrMarker::compact(size_t max_non_null_offset) {
119 assert(!_compacted, "cannot compact again");
120 _ptrmap->resize(max_non_null_offset + 1);
121 _compacted = true;
122 }
123
124 #endif // INCLUDE_CDS