1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _XFS_CKSUM_H 2 #ifndef _XFS_CKSUM_H
3 #define _XFS_CKSUM_H 1 3 #define _XFS_CKSUM_H 1
4 4
5 #define XFS_CRC_SEED (~(uint32_t)0) 5 #define XFS_CRC_SEED (~(uint32_t)0)
6 6
7 /* 7 /*
8 * Calculate the intermediate checksum for a b 8 * Calculate the intermediate checksum for a buffer that has the CRC field
9 * inside it. The offset of the 32bit crc fie 9 * inside it. The offset of the 32bit crc fields is passed as the
10 * cksum_offset parameter. We do not modify th 10 * cksum_offset parameter. We do not modify the buffer during verification,
11 * hence we have to split the CRC calculation 11 * hence we have to split the CRC calculation across the cksum_offset.
12 */ 12 */
13 static inline uint32_t 13 static inline uint32_t
14 xfs_start_cksum_safe(char *buffer, size_t leng 14 xfs_start_cksum_safe(char *buffer, size_t length, unsigned long cksum_offset)
15 { 15 {
16 uint32_t zero = 0; 16 uint32_t zero = 0;
17 uint32_t crc; 17 uint32_t crc;
18 18
19 /* Calculate CRC up to the checksum. * 19 /* Calculate CRC up to the checksum. */
20 crc = crc32c(XFS_CRC_SEED, buffer, cks 20 crc = crc32c(XFS_CRC_SEED, buffer, cksum_offset);
21 21
22 /* Skip checksum field */ 22 /* Skip checksum field */
23 crc = crc32c(crc, &zero, sizeof(__u32) 23 crc = crc32c(crc, &zero, sizeof(__u32));
24 24
25 /* Calculate the rest of the CRC. */ 25 /* Calculate the rest of the CRC. */
26 return crc32c(crc, &buffer[cksum_offse 26 return crc32c(crc, &buffer[cksum_offset + sizeof(__be32)],
27 length - (cksum_offset + 27 length - (cksum_offset + sizeof(__be32)));
28 } 28 }
29 29
30 /* 30 /*
31 * Fast CRC method where the buffer is modifie 31 * Fast CRC method where the buffer is modified. Callers must have exclusive
32 * access to the buffer while the calculation 32 * access to the buffer while the calculation takes place.
33 */ 33 */
34 static inline uint32_t 34 static inline uint32_t
35 xfs_start_cksum_update(char *buffer, size_t le 35 xfs_start_cksum_update(char *buffer, size_t length, unsigned long cksum_offset)
36 { 36 {
37 /* zero the CRC field */ 37 /* zero the CRC field */
38 *(__le32 *)(buffer + cksum_offset) = 0 38 *(__le32 *)(buffer + cksum_offset) = 0;
39 39
40 /* single pass CRC calculation for the 40 /* single pass CRC calculation for the entire buffer */
41 return crc32c(XFS_CRC_SEED, buffer, le 41 return crc32c(XFS_CRC_SEED, buffer, length);
42 } 42 }
43 43
44 /* 44 /*
45 * Convert the intermediate checksum to the fi 45 * Convert the intermediate checksum to the final ondisk format.
46 * 46 *
47 * The CRC32c calculation uses LE format even 47 * The CRC32c calculation uses LE format even on BE machines, but returns the
48 * result in host endian format. Hence we need 48 * result in host endian format. Hence we need to byte swap it back to LE format
49 * so that it is consistent on disk. 49 * so that it is consistent on disk.
50 */ 50 */
51 static inline __le32 51 static inline __le32
52 xfs_end_cksum(uint32_t crc) 52 xfs_end_cksum(uint32_t crc)
53 { 53 {
54 return ~cpu_to_le32(crc); 54 return ~cpu_to_le32(crc);
55 } 55 }
56 56
57 /* 57 /*
58 * Helper to generate the checksum for a buffe 58 * Helper to generate the checksum for a buffer.
59 * 59 *
60 * This modifies the buffer temporarily - call 60 * This modifies the buffer temporarily - callers must have exclusive
61 * access to the buffer while the calculation 61 * access to the buffer while the calculation takes place.
62 */ 62 */
63 static inline void 63 static inline void
64 xfs_update_cksum(char *buffer, size_t length, 64 xfs_update_cksum(char *buffer, size_t length, unsigned long cksum_offset)
65 { 65 {
66 uint32_t crc = xfs_start_cksum_update( 66 uint32_t crc = xfs_start_cksum_update(buffer, length, cksum_offset);
67 67
68 *(__le32 *)(buffer + cksum_offset) = x 68 *(__le32 *)(buffer + cksum_offset) = xfs_end_cksum(crc);
69 } 69 }
70 70
71 /* 71 /*
72 * Helper to verify the checksum for a buffer. 72 * Helper to verify the checksum for a buffer.
73 */ 73 */
74 static inline int 74 static inline int
75 xfs_verify_cksum(char *buffer, size_t length, 75 xfs_verify_cksum(char *buffer, size_t length, unsigned long cksum_offset)
76 { 76 {
77 uint32_t crc = xfs_start_cksum_safe(bu 77 uint32_t crc = xfs_start_cksum_safe(buffer, length, cksum_offset);
78 78
79 return *(__le32 *)(buffer + cksum_offs 79 return *(__le32 *)(buffer + cksum_offset) == xfs_end_cksum(crc);
80 } 80 }
81 81
82 #endif /* _XFS_CKSUM_H */ 82 #endif /* _XFS_CKSUM_H */
83 83
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