1 /* 2 * Copyright (C) 2015 Google, Inc. 3 * 4 * Author: Sami Tolvanen <samitolvanen@google.com> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License as published by the Free 8 * Software Foundation; either version 2 of the License, or (at your option) 9 * any later version. 10 */ 11 12 #ifndef DM_VERITY_FEC_H 13 #define DM_VERITY_FEC_H 14 15 #include "dm-verity.h" 16 #include <linux/rslib.h> 17 18 /* Reed-Solomon(M, N) parameters */ 19 #define DM_VERITY_FEC_RSM 255 20 #define DM_VERITY_FEC_MAX_RSN 253 21 #define DM_VERITY_FEC_MIN_RSN 231 /* ~10% space overhead */ 22 23 /* buffers for deinterleaving and decoding */ 24 #define DM_VERITY_FEC_BUF_PREALLOC 1 /* buffers to preallocate */ 25 #define DM_VERITY_FEC_BUF_RS_BITS 4 /* 1 << RS blocks per buffer */ 26 /* we need buffers for at most 1 << block size RS blocks */ 27 #define DM_VERITY_FEC_BUF_MAX \ 28 (1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS)) 29 30 /* maximum recursion level for verity_fec_decode */ 31 #define DM_VERITY_FEC_MAX_RECURSION 4 32 33 #define DM_VERITY_OPT_FEC_DEV "use_fec_from_device" 34 #define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks" 35 #define DM_VERITY_OPT_FEC_START "fec_start" 36 #define DM_VERITY_OPT_FEC_ROOTS "fec_roots" 37 38 /* configuration */ 39 struct dm_verity_fec { 40 struct dm_dev *dev; /* parity data device */ 41 struct dm_bufio_client *data_bufio; /* for data dev access */ 42 struct dm_bufio_client *bufio; /* for parity data access */ 43 sector_t start; /* parity data start in blocks */ 44 sector_t blocks; /* number of blocks covered */ 45 sector_t rounds; /* number of interleaving rounds */ 46 sector_t hash_blocks; /* blocks covered after v->hash_start */ 47 unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */ 48 unsigned char rsn; /* N of RS(M, N) */ 49 mempool_t *rs_pool; /* mempool for fio->rs */ 50 mempool_t *prealloc_pool; /* mempool for preallocated buffers */ 51 mempool_t *extra_pool; /* mempool for extra buffers */ 52 mempool_t *output_pool; /* mempool for output */ 53 struct kmem_cache *cache; /* cache for buffers */ 54 }; 55 56 /* per-bio data */ 57 struct dm_verity_fec_io { 58 struct rs_control *rs; /* Reed-Solomon state */ 59 int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */ 60 u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */ 61 unsigned nbufs; /* number of buffers allocated */ 62 u8 *output; /* buffer for corrected output */ 63 size_t output_pos; 64 unsigned level; /* recursion level */ 65 }; 66 67 #ifdef CONFIG_DM_VERITY_FEC 68 69 /* each feature parameter requires a value */ 70 #define DM_VERITY_OPTS_FEC 8 71 72 extern bool verity_fec_is_enabled(struct dm_verity *v); 73 74 extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, 75 enum verity_block_type type, sector_t block, 76 u8 *dest, struct bvec_iter *iter); 77 78 extern unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz, 79 char *result, unsigned maxlen); 80 81 extern void verity_fec_finish_io(struct dm_verity_io *io); 82 extern void verity_fec_init_io(struct dm_verity_io *io); 83 84 extern bool verity_is_fec_opt_arg(const char *arg_name); 85 extern int verity_fec_parse_opt_args(struct dm_arg_set *as, 86 struct dm_verity *v, unsigned *argc, 87 const char *arg_name); 88 89 extern void verity_fec_dtr(struct dm_verity *v); 90 91 extern int verity_fec_ctr_alloc(struct dm_verity *v); 92 extern int verity_fec_ctr(struct dm_verity *v); 93 94 #else /* !CONFIG_DM_VERITY_FEC */ 95 96 #define DM_VERITY_OPTS_FEC 0 97 98 static inline bool verity_fec_is_enabled(struct dm_verity *v) 99 { 100 return false; 101 } 102 103 static inline int verity_fec_decode(struct dm_verity *v, 104 struct dm_verity_io *io, 105 enum verity_block_type type, 106 sector_t block, u8 *dest, 107 struct bvec_iter *iter) 108 { 109 return -EOPNOTSUPP; 110 } 111 112 static inline unsigned verity_fec_status_table(struct dm_verity *v, 113 unsigned sz, char *result, 114 unsigned maxlen) 115 { 116 return sz; 117 } 118 119 static inline void verity_fec_finish_io(struct dm_verity_io *io) 120 { 121 } 122 123 static inline void verity_fec_init_io(struct dm_verity_io *io) 124 { 125 } 126 127 static inline bool verity_is_fec_opt_arg(const char *arg_name) 128 { 129 return false; 130 } 131 132 static inline int verity_fec_parse_opt_args(struct dm_arg_set *as, 133 struct dm_verity *v, 134 unsigned *argc, 135 const char *arg_name) 136 { 137 return -EINVAL; 138 } 139 140 static inline void verity_fec_dtr(struct dm_verity *v) 141 { 142 } 143 144 static inline int verity_fec_ctr_alloc(struct dm_verity *v) 145 { 146 return 0; 147 } 148 149 static inline int verity_fec_ctr(struct dm_verity *v) 150 { 151 return 0; 152 } 153 154 #endif /* CONFIG_DM_VERITY_FEC */ 155 156 #endif /* DM_VERITY_FEC_H */ 157