drivers/md/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 /* 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         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 */
  53 struct 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
  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, struct bvec_iter *iter);
  73
  74 extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
  75                                         char *result, unsigned 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 *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
  94 static inline bool verity_fec_is_enabled(struct dm_verity *v)
  95 {
  96         return false;
  97 }
  98
  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                                     struct bvec_iter *iter)
 104 {
 105         return -EOPNOTSUPP;
 106 }
 107
 108 static inline unsigned verity_fec_status_table(struct dm_verity *v,
 109                                                unsigned sz, char *result,
 110                                                unsigned maxlen)
 111 {
 112         return sz;
 113 }
 114
 115 static inline void verity_fec_finish_io(struct dm_verity_io *io)
 116 {
 117 }
 118
 119 static inline void verity_fec_init_io(struct dm_verity_io *io)
 120 {
 121 }
 122
 123 static inline bool verity_is_fec_opt_arg(const char *arg_name)
 124 {
 125         return false;
 126 }
 127
 128 static 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
 136 static inline void verity_fec_dtr(struct dm_verity *v)
 137 {
 138 }
 139
 140 static inline int verity_fec_ctr_alloc(struct dm_verity *v)
 141 {
 142         return 0;
 143 }
 144
 145 static 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 */