1 /*
2 * Copyright (c) 2018, 2025, 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 #ifndef SHARE_INCLUDE_CDS_H
26 #define SHARE_INCLUDE_CDS_H
27
28 #include <stddef.h>
29
30 // This file declares the CDS data structures that are used by the HotSpot Serviceability Agent
31 // (see C sources inside src/jdk.hotspot.agent).
32 //
33 // We should use only standard C types. Do not use custom types such as bool, intx,
34 // etc, to avoid introducing unnecessary dependencies to other HotSpot type declarations.
35 //
36 // Also, this is a C header file. Do not use C++ here.
37
38 #define NUM_CDS_REGIONS 4 // this must be the same as MetaspaceShared::n_regions
39 #define CDS_ARCHIVE_MAGIC 0xf00baba2
40 #define CDS_DYNAMIC_ARCHIVE_MAGIC 0xf00baba8
41 #define CDS_PREIMAGE_ARCHIVE_MAGIC 0xcafea07c
42 #define CDS_GENERIC_HEADER_SUPPORTED_MIN_VERSION 13
43 #define CURRENT_CDS_ARCHIVE_VERSION 18
44
45 typedef struct CDSFileMapRegion {
46 int _crc; // CRC checksum of this region.
47 int _read_only; // read only region?
48 int _allow_exec; // executable code in this region?
49 int _is_heap_region; // Used by SA and debug build.
50 int _is_bitmap_region; // Relocation bitmap for RO/RW regions (used by SA and debug build).
51 int _mapped_from_file; // Is this region mapped from a file?
52 // If false, this region was initialized using ::read().
53 size_t _file_offset; // Data for this region starts at this offset in the archive file.
54 size_t _mapping_offset; // This encodes the requested address for this region to be mapped at runtime.
55 // However, the JVM may choose to map at an alternative location (e.g., for ASLR,
56 // or to adapt to the available ranges in the Java heap range).
57 // - For an RO/RW region, the requested address is:
58 // FileMapHeader::requested_base_address() + _mapping_offset
59 // - For a heap region, the requested address is:
60 // +UseCompressedOops: /*runtime*/ CompressedOops::base() + _mapping_offset
61 // -UseCompressedOops: FileMapHeader::heap_begin() + _mapping_offset
62 // See FileMapInfo::heap_region_requested_address().
63 // - For bitmap regions, the _mapping_offset is always zero. The runtime address
64 // is picked by the OS.
65 size_t _used; // Number of bytes actually used by this region (excluding padding bytes added
66 // for alignment purposed.
67 size_t _oopmap_offset; // Bitmap for relocating oop fields in archived heap objects.
68 // (The base address is the bottom of the BM region)
69 size_t _oopmap_size_in_bits;
70 size_t _ptrmap_offset; // Bitmap for relocating native pointer fields in archived heap objects.
71 // (The base address is the bottom of the BM region).
72 size_t _ptrmap_size_in_bits;
73 char* _mapped_base; // Actually mapped address (null if this region is not mapped).
74 bool _in_reserved_space; // Is this region in a ReservedSpace
75 } CDSFileMapRegion;
76
77 // This portion of the archive file header must remain unchanged for
78 // _version >= CDS_GENERIC_HEADER_SUPPORTED_MIN_VERSION (13).
79 // This makes it possible to read important information from a CDS archive created by
80 // a different version of HotSpot, so that we can automatically regenerate the archive as necessary.
81 typedef struct GenericCDSFileMapHeader {
82 unsigned int _magic; // identification of file type
83 int _crc; // header crc checksum, start from _base_archive_name_offset
84 int _version; // CURRENT_CDS_ARCHIVE_VERSION of the jdk that dumped the this archive
85 unsigned int _header_size; // total size of the header, in bytes
86 unsigned int _base_archive_name_offset; // offset where the base archive name is stored
87 // static archive: 0
88 // dynamic archive:
89 // 0 for default base archive
90 // non-zero for non-default base archive
91 // (char*)this + _base_archive_name_offset
92 // points to a 0-terminated string for the base archive name
93 unsigned int _base_archive_name_size; // size of base archive name including ending '\0'
94 // static: 0
95 // dynamic:
96 // 0 for default base archive
97 // non-zero for non-default base archive
98
99 } GenericCDSFileMapHeader;
100
101 // This type is used by the Serviceability Agent to access the contents of
102 // a memory-mapped CDS archive.
103 typedef struct CDSFileMapHeaderBase {
104 // We cannot inherit from GenericCDSFileMapHeader as this type may be used
105 // by both C and C++ code.
106 GenericCDSFileMapHeader _generic_header;
107 CDSFileMapRegion _regions[NUM_CDS_REGIONS];
108 } CDSFileMapHeaderBase;
109
110 #endif // SHARE_INCLUDE_CDS_H