dm-verity-fec.h

  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 */