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 */