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Linux kernel mirror (for testing)
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linux
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 */
32struct 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 */
51struct 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
65extern bool verity_fec_is_enabled(struct dm_verity *v);
66
67extern 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
71extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz,
72 char *result, unsigned int maxlen);
73
74extern void verity_fec_finish_io(struct dm_verity_io *io);
75extern void verity_fec_init_io(struct dm_verity_io *io);
76
77extern bool verity_is_fec_opt_arg(const char *arg_name);
78extern 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
82extern void verity_fec_dtr(struct dm_verity *v);
83
84extern int verity_fec_ctr_alloc(struct dm_verity *v);
85extern int verity_fec_ctr(struct dm_verity *v);
86
87#else /* !CONFIG_DM_VERITY_FEC */
88
89#define DM_VERITY_OPTS_FEC 0
90
91static inline bool verity_fec_is_enabled(struct dm_verity *v)
92{
93 return false;
94}
95
96static 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
105static 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
112static inline void verity_fec_finish_io(struct dm_verity_io *io)
113{
114}
115
116static inline void verity_fec_init_io(struct dm_verity_io *io)
117{
118}
119
120static inline bool verity_is_fec_opt_arg(const char *arg_name)
121{
122 return false;
123}
124
125static 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
133static inline void verity_fec_dtr(struct dm_verity *v)
134{
135}
136
137static inline int verity_fec_ctr_alloc(struct dm_verity *v)
138{
139 return 0;
140}
141
142static 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 */