1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | /* |
3 | * Copyright (C) 2015 Google, Inc. |
4 | * |
5 | * Author: Sami Tolvanen <samitolvanen@google.com> |
6 | */ |
7 | |
8 | #ifndef DM_VERITY_FEC_H |
9 | #define DM_VERITY_FEC_H |
10 | |
11 | #include "dm-verity.h" |
12 | #include <linux/rslib.h> |
13 | |
14 | /* Reed-Solomon(M, N) parameters */ |
15 | #define DM_VERITY_FEC_RSM 255 |
16 | #define DM_VERITY_FEC_MAX_RSN 253 |
17 | #define DM_VERITY_FEC_MIN_RSN 231 /* ~10% space overhead */ |
18 | |
19 | /* buffers for deinterleaving and decoding */ |
20 | #define DM_VERITY_FEC_BUF_PREALLOC 1 /* buffers to preallocate */ |
21 | #define DM_VERITY_FEC_BUF_RS_BITS 4 /* 1 << RS blocks per buffer */ |
22 | /* we need buffers for at most 1 << block size RS blocks */ |
23 | #define DM_VERITY_FEC_BUF_MAX \ |
24 | (1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS)) |
25 | |
26 | /* maximum recursion level for verity_fec_decode */ |
27 | #define DM_VERITY_FEC_MAX_RECURSION 4 |
28 | |
29 | #define DM_VERITY_OPT_FEC_DEV "use_fec_from_device" |
30 | #define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks" |
31 | #define DM_VERITY_OPT_FEC_START "fec_start" |
32 | #define DM_VERITY_OPT_FEC_ROOTS "fec_roots" |
33 | |
34 | /* configuration */ |
35 | struct dm_verity_fec { |
36 | struct dm_dev *dev; /* parity data device */ |
37 | struct dm_bufio_client *data_bufio; /* for data dev access */ |
38 | struct dm_bufio_client *bufio; /* for parity data access */ |
39 | size_t io_size; /* IO size for roots */ |
40 | sector_t start; /* parity data start in blocks */ |
41 | sector_t blocks; /* number of blocks covered */ |
42 | sector_t rounds; /* number of interleaving rounds */ |
43 | sector_t hash_blocks; /* blocks covered after v->hash_start */ |
44 | unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */ |
45 | unsigned char rsn; /* N of RS(M, N) */ |
46 | mempool_t rs_pool; /* mempool for fio->rs */ |
47 | mempool_t prealloc_pool; /* mempool for preallocated buffers */ |
48 | mempool_t ; /* mempool for extra buffers */ |
49 | mempool_t output_pool; /* mempool for output */ |
50 | struct kmem_cache *cache; /* cache for buffers */ |
51 | }; |
52 | |
53 | /* per-bio data */ |
54 | struct dm_verity_fec_io { |
55 | struct rs_control *rs; /* Reed-Solomon state */ |
56 | int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */ |
57 | u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */ |
58 | unsigned int nbufs; /* number of buffers allocated */ |
59 | u8 *output; /* buffer for corrected output */ |
60 | unsigned int level; /* recursion level */ |
61 | }; |
62 | |
63 | #ifdef CONFIG_DM_VERITY_FEC |
64 | |
65 | /* each feature parameter requires a value */ |
66 | #define DM_VERITY_OPTS_FEC 8 |
67 | |
68 | extern bool verity_fec_is_enabled(struct dm_verity *v); |
69 | |
70 | extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, |
71 | enum verity_block_type type, sector_t block, |
72 | u8 *dest); |
73 | |
74 | extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz, |
75 | char *result, unsigned int maxlen); |
76 | |
77 | extern void verity_fec_finish_io(struct dm_verity_io *io); |
78 | extern void verity_fec_init_io(struct dm_verity_io *io); |
79 | |
80 | extern bool verity_is_fec_opt_arg(const char *arg_name); |
81 | extern int verity_fec_parse_opt_args(struct dm_arg_set *as, |
82 | struct dm_verity *v, unsigned int *argc, |
83 | const char *arg_name); |
84 | |
85 | extern void verity_fec_dtr(struct dm_verity *v); |
86 | |
87 | extern int verity_fec_ctr_alloc(struct dm_verity *v); |
88 | extern int verity_fec_ctr(struct dm_verity *v); |
89 | |
90 | #else /* !CONFIG_DM_VERITY_FEC */ |
91 | |
92 | #define DM_VERITY_OPTS_FEC 0 |
93 | |
94 | static inline bool verity_fec_is_enabled(struct dm_verity *v) |
95 | { |
96 | return false; |
97 | } |
98 | |
99 | static inline int verity_fec_decode(struct dm_verity *v, |
100 | struct dm_verity_io *io, |
101 | enum verity_block_type type, |
102 | sector_t block, u8 *dest) |
103 | { |
104 | return -EOPNOTSUPP; |
105 | } |
106 | |
107 | static inline unsigned int verity_fec_status_table(struct dm_verity *v, |
108 | unsigned int sz, char *result, |
109 | unsigned int maxlen) |
110 | { |
111 | return sz; |
112 | } |
113 | |
114 | static inline void verity_fec_finish_io(struct dm_verity_io *io) |
115 | { |
116 | } |
117 | |
118 | static inline void verity_fec_init_io(struct dm_verity_io *io) |
119 | { |
120 | } |
121 | |
122 | static inline bool verity_is_fec_opt_arg(const char *arg_name) |
123 | { |
124 | return false; |
125 | } |
126 | |
127 | static inline int verity_fec_parse_opt_args(struct dm_arg_set *as, |
128 | struct dm_verity *v, |
129 | unsigned int *argc, |
130 | const char *arg_name) |
131 | { |
132 | return -EINVAL; |
133 | } |
134 | |
135 | static inline void verity_fec_dtr(struct dm_verity *v) |
136 | { |
137 | } |
138 | |
139 | static inline int verity_fec_ctr_alloc(struct dm_verity *v) |
140 | { |
141 | return 0; |
142 | } |
143 | |
144 | static inline int verity_fec_ctr(struct dm_verity *v) |
145 | { |
146 | return 0; |
147 | } |
148 | |
149 | #endif /* CONFIG_DM_VERITY_FEC */ |
150 | |
151 | #endif /* DM_VERITY_FEC_H */ |
152 | |