tjh.dev
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/* 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 */
35struct 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 */
54struct 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
68extern bool verity_fec_is_enabled(struct dm_verity *v);
69
70extern 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
74extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz,
75 char *result, unsigned int maxlen);
76
77extern void verity_fec_finish_io(struct dm_verity_io *io);
78extern void verity_fec_init_io(struct dm_verity_io *io);
79
80extern bool verity_is_fec_opt_arg(const char *arg_name);
81extern 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
85extern void verity_fec_dtr(struct dm_verity *v);
86
87extern int verity_fec_ctr_alloc(struct dm_verity *v);
88extern int verity_fec_ctr(struct dm_verity *v);
89
90#else /* !CONFIG_DM_VERITY_FEC */
91
92#define DM_VERITY_OPTS_FEC 0
93
94static inline bool verity_fec_is_enabled(struct dm_verity *v)
95{
96 return false;
97}
98
99static 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
107static 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
114static inline void verity_fec_finish_io(struct dm_verity_io *io)
115{
116}
117
118static inline void verity_fec_init_io(struct dm_verity_io *io)
119{
120}
121
122static inline bool verity_is_fec_opt_arg(const char *arg_name)
123{
124 return false;
125}
126
127static 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
135static inline void verity_fec_dtr(struct dm_verity *v)
136{
137}
138
139static inline int verity_fec_ctr_alloc(struct dm_verity *v)
140{
141 return 0;
142}
143
144static 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 */