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 | size_t output_pos; |
61 | unsigned int level; /* recursion level */ |
62 | }; |
63 | |
64 | #ifdef CONFIG_DM_VERITY_FEC |
65 | |
66 | /* each feature parameter requires a value */ |
67 | #define DM_VERITY_OPTS_FEC 8 |
68 | |
69 | extern bool verity_fec_is_enabled(struct dm_verity *v); |
70 | |
71 | extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, |
72 | enum verity_block_type type, sector_t block, |
73 | u8 *dest, struct bvec_iter *iter); |
74 | |
75 | extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz, |
76 | char *result, unsigned int maxlen); |
77 | |
78 | extern void verity_fec_finish_io(struct dm_verity_io *io); |
79 | extern void verity_fec_init_io(struct dm_verity_io *io); |
80 | |
81 | extern bool verity_is_fec_opt_arg(const char *arg_name); |
82 | extern int verity_fec_parse_opt_args(struct dm_arg_set *as, |
83 | struct dm_verity *v, unsigned int *argc, |
84 | const char *arg_name); |
85 | |
86 | extern void verity_fec_dtr(struct dm_verity *v); |
87 | |
88 | extern int verity_fec_ctr_alloc(struct dm_verity *v); |
89 | extern int verity_fec_ctr(struct dm_verity *v); |
90 | |
91 | #else /* !CONFIG_DM_VERITY_FEC */ |
92 | |
93 | #define DM_VERITY_OPTS_FEC 0 |
94 | |
95 | static inline bool verity_fec_is_enabled(struct dm_verity *v) |
96 | { |
97 | return false; |
98 | } |
99 | |
100 | static inline int verity_fec_decode(struct dm_verity *v, |
101 | struct dm_verity_io *io, |
102 | enum verity_block_type type, |
103 | sector_t block, u8 *dest, |
104 | struct bvec_iter *iter) |
105 | { |
106 | return -EOPNOTSUPP; |
107 | } |
108 | |
109 | static inline unsigned int verity_fec_status_table(struct dm_verity *v, |
110 | unsigned int sz, char *result, |
111 | unsigned int maxlen) |
112 | { |
113 | return sz; |
114 | } |
115 | |
116 | static inline void verity_fec_finish_io(struct dm_verity_io *io) |
117 | { |
118 | } |
119 | |
120 | static inline void verity_fec_init_io(struct dm_verity_io *io) |
121 | { |
122 | } |
123 | |
124 | static inline bool verity_is_fec_opt_arg(const char *arg_name) |
125 | { |
126 | return false; |
127 | } |
128 | |
129 | static inline int verity_fec_parse_opt_args(struct dm_arg_set *as, |
130 | struct dm_verity *v, |
131 | unsigned int *argc, |
132 | const char *arg_name) |
133 | { |
134 | return -EINVAL; |
135 | } |
136 | |
137 | static inline void verity_fec_dtr(struct dm_verity *v) |
138 | { |
139 | } |
140 | |
141 | static inline int verity_fec_ctr_alloc(struct dm_verity *v) |
142 | { |
143 | return 0; |
144 | } |
145 | |
146 | static inline int verity_fec_ctr(struct dm_verity *v) |
147 | { |
148 | return 0; |
149 | } |
150 | |
151 | #endif /* CONFIG_DM_VERITY_FEC */ |
152 | |
153 | #endif /* DM_VERITY_FEC_H */ |
154 | |