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 size_t output_pos; 61 unsigned int level; /* recursion level */ 62 }; 63 64 #ifdef CONFIG_DM_VERITY_FEC 65 66 /* each feature parameter requires a value */ 67 #define DM_VERITY_OPTS_FEC 8 68 69 extern bool verity_fec_is_enabled(struct dm_verity *v); 70 71 extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, 72 enum verity_block_type type, sector_t block, 73 u8 *dest, struct bvec_iter *iter); 74 75 extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz, 76 char *result, unsigned int maxlen); 77 78 extern void verity_fec_finish_io(struct dm_verity_io *io); 79 extern void verity_fec_init_io(struct dm_verity_io *io); 80 81 extern bool verity_is_fec_opt_arg(const char *arg_name); 82 extern int verity_fec_parse_opt_args(struct dm_arg_set *as, 83 struct dm_verity *v, unsigned int *argc, 84 const char *arg_name); 85 86 extern void verity_fec_dtr(struct dm_verity *v); 87 88 extern int verity_fec_ctr_alloc(struct dm_verity *v); 89 extern int verity_fec_ctr(struct dm_verity *v); 90 91 #else /* !CONFIG_DM_VERITY_FEC */ 92 93 #define DM_VERITY_OPTS_FEC 0 94 95 static inline bool verity_fec_is_enabled(struct dm_verity *v) 96 { 97 return false; 98 } 99 100 static inline int verity_fec_decode(struct dm_verity *v, 101 struct dm_verity_io *io, 102 enum verity_block_type type, 103 sector_t block, u8 *dest, 104 struct bvec_iter *iter) 105 { 106 return -EOPNOTSUPP; 107 } 108 109 static inline unsigned int verity_fec_status_table(struct dm_verity *v, 110 unsigned int sz, char *result, 111 unsigned int maxlen) 112 { 113 return sz; 114 } 115 116 static inline void verity_fec_finish_io(struct dm_verity_io *io) 117 { 118 } 119 120 static inline void verity_fec_init_io(struct dm_verity_io *io) 121 { 122 } 123 124 static inline bool verity_is_fec_opt_arg(const char *arg_name) 125 { 126 return false; 127 } 128 129 static inline int verity_fec_parse_opt_args(struct dm_arg_set *as, 130 struct dm_verity *v, 131 unsigned int *argc, 132 const char *arg_name) 133 { 134 return -EINVAL; 135 } 136 137 static inline void verity_fec_dtr(struct dm_verity *v) 138 { 139 } 140 141 static inline int verity_fec_ctr_alloc(struct dm_verity *v) 142 { 143 return 0; 144 } 145 146 static inline int verity_fec_ctr(struct dm_verity *v) 147 { 148 return 0; 149 } 150 151 #endif /* CONFIG_DM_VERITY_FEC */ 152 153 #endif /* DM_VERITY_FEC_H */ 154