tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
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 sector_t start; /* parity data start in blocks */
40 sector_t blocks; /* number of blocks covered */
41 sector_t rounds; /* number of interleaving rounds */
42 sector_t hash_blocks; /* blocks covered after v->hash_start */
43 unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */
44 unsigned char rsn; /* N of RS(M, N) */
45 mempool_t rs_pool; /* mempool for fio->rs */
46 mempool_t prealloc_pool; /* mempool for preallocated buffers */
47 mempool_t extra_pool; /* mempool for extra buffers */
48 mempool_t output_pool; /* mempool for output */
49 struct kmem_cache *cache; /* cache for buffers */
50};
51
52/* per-bio data */
53struct dm_verity_fec_io {
54 struct rs_control *rs; /* Reed-Solomon state */
55 int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */
56 u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */
57 unsigned nbufs; /* number of buffers allocated */
58 u8 *output; /* buffer for corrected output */
59 size_t output_pos;
60 unsigned 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, struct bvec_iter *iter);
73
74extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
75 char *result, unsigned 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 *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 struct bvec_iter *iter)
104{
105 return -EOPNOTSUPP;
106}
107
108static inline unsigned verity_fec_status_table(struct dm_verity *v,
109 unsigned sz, char *result,
110 unsigned maxlen)
111{
112 return sz;
113}
114
115static inline void verity_fec_finish_io(struct dm_verity_io *io)
116{
117}
118
119static inline void verity_fec_init_io(struct dm_verity_io *io)
120{
121}
122
123static inline bool verity_is_fec_opt_arg(const char *arg_name)
124{
125 return false;
126}
127
128static inline int verity_fec_parse_opt_args(struct dm_arg_set *as,
129 struct dm_verity *v,
130 unsigned *argc,
131 const char *arg_name)
132{
133 return -EINVAL;
134}
135
136static inline void verity_fec_dtr(struct dm_verity *v)
137{
138}
139
140static inline int verity_fec_ctr_alloc(struct dm_verity *v)
141{
142 return 0;
143}
144
145static inline int verity_fec_ctr(struct dm_verity *v)
146{
147 return 0;
148}
149
150#endif /* CONFIG_DM_VERITY_FEC */
151
152#endif /* DM_VERITY_FEC_H */