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 #define DM_VERITY_OPT_FEC_DEV "use_fec_from_device"
27 #define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks"
28 #define DM_VERITY_OPT_FEC_START "fec_start"
29 #define DM_VERITY_OPT_FEC_ROOTS "fec_roots"
30
31 /* configuration */
32 struct dm_verity_fec {
33 struct dm_dev *dev; /* parity data device */
34 struct dm_bufio_client *data_bufio; /* for data dev access */
35 struct dm_bufio_client *bufio; /* for parity data access */
36 size_t io_size; /* IO size for roots */
37 sector_t start; /* parity data start in blocks */
38 sector_t blocks; /* number of blocks covered */
39 sector_t rounds; /* number of interleaving rounds */
40 sector_t hash_blocks; /* blocks covered after v->hash_start */
41 unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
42 unsigned char rsn; /* N of RS(M, N) */
43 mempool_t rs_pool; /* mempool for fio->rs */
44 mempool_t prealloc_pool; /* mempool for preallocated buffers */
45 mempool_t output_pool; /* mempool for output */
46 struct kmem_cache *cache; /* cache for buffers */
47 atomic64_t corrected; /* corrected errors */
48 };
49
50 /* per-bio data */
51 struct dm_verity_fec_io {
52 struct rs_control *rs; /* Reed-Solomon state */
53 int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */
54 u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */
55 unsigned int nbufs; /* number of buffers allocated */
56 u8 *output; /* buffer for corrected output */
57 unsigned int level; /* recursion level */
58 };
59
60 #ifdef CONFIG_DM_VERITY_FEC
61
62 /* each feature parameter requires a value */
63 #define DM_VERITY_OPTS_FEC 8
64
65 extern bool verity_fec_is_enabled(struct dm_verity *v);
66
67 extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
68 enum verity_block_type type, const u8 *want_digest,
69 sector_t block, u8 *dest);
70
71 extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz,
72 char *result, unsigned int maxlen);
73
74 extern void verity_fec_finish_io(struct dm_verity_io *io);
75 extern void verity_fec_init_io(struct dm_verity_io *io);
76
77 extern bool verity_is_fec_opt_arg(const char *arg_name);
78 extern int verity_fec_parse_opt_args(struct dm_arg_set *as,
79 struct dm_verity *v, unsigned int *argc,
80 const char *arg_name);
81
82 extern void verity_fec_dtr(struct dm_verity *v);
83
84 extern int verity_fec_ctr_alloc(struct dm_verity *v);
85 extern int verity_fec_ctr(struct dm_verity *v);
86
87 #else /* !CONFIG_DM_VERITY_FEC */
88
89 #define DM_VERITY_OPTS_FEC 0
90
verity_fec_is_enabled(struct dm_verity * v)91 static inline bool verity_fec_is_enabled(struct dm_verity *v)
92 {
93 return false;
94 }
95
verity_fec_decode(struct dm_verity * v,struct dm_verity_io * io,enum verity_block_type type,const u8 * want_digest,sector_t block,u8 * dest)96 static inline int verity_fec_decode(struct dm_verity *v,
97 struct dm_verity_io *io,
98 enum verity_block_type type,
99 const u8 *want_digest,
100 sector_t block, u8 *dest)
101 {
102 return -EOPNOTSUPP;
103 }
104
verity_fec_status_table(struct dm_verity * v,unsigned int sz,char * result,unsigned int maxlen)105 static inline unsigned int verity_fec_status_table(struct dm_verity *v,
106 unsigned int sz, char *result,
107 unsigned int maxlen)
108 {
109 return sz;
110 }
111
verity_fec_finish_io(struct dm_verity_io * io)112 static inline void verity_fec_finish_io(struct dm_verity_io *io)
113 {
114 }
115
verity_fec_init_io(struct dm_verity_io * io)116 static inline void verity_fec_init_io(struct dm_verity_io *io)
117 {
118 }
119
verity_is_fec_opt_arg(const char * arg_name)120 static inline bool verity_is_fec_opt_arg(const char *arg_name)
121 {
122 return false;
123 }
124
verity_fec_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,unsigned int * argc,const char * arg_name)125 static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
126 struct dm_verity *v,
127 unsigned int *argc,
128 const char *arg_name)
129 {
130 return -EINVAL;
131 }
132
verity_fec_dtr(struct dm_verity * v)133 static inline void verity_fec_dtr(struct dm_verity *v)
134 {
135 }
136
verity_fec_ctr_alloc(struct dm_verity * v)137 static inline int verity_fec_ctr_alloc(struct dm_verity *v)
138 {
139 return 0;
140 }
141
verity_fec_ctr(struct dm_verity * v)142 static inline int verity_fec_ctr(struct dm_verity *v)
143 {
144 return 0;
145 }
146
147 #endif /* CONFIG_DM_VERITY_FEC */
148
149 #endif /* DM_VERITY_FEC_H */
150