xref: /linux/drivers/md/dm-verity-fec.h (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
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 */
35 struct 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 */
54 struct 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 
68 extern bool verity_fec_is_enabled(struct dm_verity *v);
69 
70 extern 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 
74 extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz,
75 					char *result, unsigned int maxlen);
76 
77 extern void verity_fec_finish_io(struct dm_verity_io *io);
78 extern void verity_fec_init_io(struct dm_verity_io *io);
79 
80 extern bool verity_is_fec_opt_arg(const char *arg_name);
81 extern 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 
85 extern void verity_fec_dtr(struct dm_verity *v);
86 
87 extern int verity_fec_ctr_alloc(struct dm_verity *v);
88 extern int verity_fec_ctr(struct dm_verity *v);
89 
90 #else /* !CONFIG_DM_VERITY_FEC */
91 
92 #define DM_VERITY_OPTS_FEC	0
93 
verity_fec_is_enabled(struct dm_verity * v)94 static inline bool verity_fec_is_enabled(struct dm_verity *v)
95 {
96 	return false;
97 }
98 
verity_fec_decode(struct dm_verity * v,struct dm_verity_io * io,enum verity_block_type type,sector_t block,u8 * dest)99 static 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 
verity_fec_status_table(struct dm_verity * v,unsigned int sz,char * result,unsigned int maxlen)107 static 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 
verity_fec_finish_io(struct dm_verity_io * io)114 static inline void verity_fec_finish_io(struct dm_verity_io *io)
115 {
116 }
117 
verity_fec_init_io(struct dm_verity_io * io)118 static inline void verity_fec_init_io(struct dm_verity_io *io)
119 {
120 }
121 
verity_is_fec_opt_arg(const char * arg_name)122 static inline bool verity_is_fec_opt_arg(const char *arg_name)
123 {
124 	return false;
125 }
126 
verity_fec_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,unsigned int * argc,const char * arg_name)127 static 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 
verity_fec_dtr(struct dm_verity * v)135 static inline void verity_fec_dtr(struct dm_verity *v)
136 {
137 }
138 
verity_fec_ctr_alloc(struct dm_verity * v)139 static inline int verity_fec_ctr_alloc(struct dm_verity *v)
140 {
141 	return 0;
142 }
143 
verity_fec_ctr(struct dm_verity * v)144 static 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 */
152