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 extra_pool; /* 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
verity_fec_is_enabled(struct dm_verity * v)95 static inline bool verity_fec_is_enabled(struct dm_verity *v)
96 {
97 return false;
98 }
99
verity_fec_decode(struct dm_verity * v,struct dm_verity_io * io,enum verity_block_type type,sector_t block,u8 * dest,struct bvec_iter * iter)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
verity_fec_status_table(struct dm_verity * v,unsigned int sz,char * result,unsigned int maxlen)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
verity_fec_finish_io(struct dm_verity_io * io)116 static inline void verity_fec_finish_io(struct dm_verity_io *io)
117 {
118 }
119
verity_fec_init_io(struct dm_verity_io * io)120 static inline void verity_fec_init_io(struct dm_verity_io *io)
121 {
122 }
123
verity_is_fec_opt_arg(const char * arg_name)124 static inline bool verity_is_fec_opt_arg(const char *arg_name)
125 {
126 return false;
127 }
128
verity_fec_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,unsigned int * argc,const char * arg_name)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
verity_fec_dtr(struct dm_verity * v)137 static inline void verity_fec_dtr(struct dm_verity *v)
138 {
139 }
140
verity_fec_ctr_alloc(struct dm_verity * v)141 static inline int verity_fec_ctr_alloc(struct dm_verity *v)
142 {
143 return 0;
144 }
145
verity_fec_ctr(struct dm_verity * v)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