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	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
69extern bool verity_fec_is_enabled(struct dm_verity *v);
70
71extern 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
75extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz,
76					char *result, unsigned int maxlen);
77
78extern void verity_fec_finish_io(struct dm_verity_io *io);
79extern void verity_fec_init_io(struct dm_verity_io *io);
80
81extern bool verity_is_fec_opt_arg(const char *arg_name);
82extern 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
86extern void verity_fec_dtr(struct dm_verity *v);
87
88extern int verity_fec_ctr_alloc(struct dm_verity *v);
89extern int verity_fec_ctr(struct dm_verity *v);
90
91#else /* !CONFIG_DM_VERITY_FEC */
92
93#define DM_VERITY_OPTS_FEC	0
94
95static inline bool verity_fec_is_enabled(struct dm_verity *v)
96{
97	return false;
98}
99
100static 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
109static 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
116static inline void verity_fec_finish_io(struct dm_verity_io *io)
117{
118}
119
120static inline void verity_fec_init_io(struct dm_verity_io *io)
121{
122}
123
124static inline bool verity_is_fec_opt_arg(const char *arg_name)
125{
126	return false;
127}
128
129static 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
137static inline void verity_fec_dtr(struct dm_verity *v)
138{
139}
140
141static inline int verity_fec_ctr_alloc(struct dm_verity *v)
142{
143	return 0;
144}
145
146static 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