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 */ 153