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 #define DM_VERITY_OPT_FEC_DEV "use_fec_from_device" 27 #define DM_VERITY_OPT_FEC_BLOCKS "fec_blocks" 28 #define DM_VERITY_OPT_FEC_START "fec_start" 29 #define DM_VERITY_OPT_FEC_ROOTS "fec_roots" 30 31 /* configuration */ 32 struct dm_verity_fec { 33 struct dm_dev *dev; /* parity data device */ 34 struct dm_bufio_client *data_bufio; /* for data dev access */ 35 struct dm_bufio_client *bufio; /* for parity data access */ 36 size_t io_size; /* IO size for roots */ 37 sector_t start; /* parity data start in blocks */ 38 sector_t blocks; /* number of blocks covered */ 39 sector_t rounds; /* number of interleaving rounds */ 40 sector_t hash_blocks; /* blocks covered after v->hash_start */ 41 unsigned char roots; /* number of parity bytes, M-N of RS(M, N) */ 42 unsigned char rsn; /* N of RS(M, N) */ 43 mempool_t rs_pool; /* mempool for fio->rs */ 44 mempool_t prealloc_pool; /* mempool for preallocated buffers */ 45 mempool_t output_pool; /* mempool for output */ 46 struct kmem_cache *cache; /* cache for buffers */ 47 atomic64_t corrected; /* corrected errors */ 48 }; 49 50 /* per-bio data */ 51 struct dm_verity_fec_io { 52 struct rs_control *rs; /* Reed-Solomon state */ 53 int erasures[DM_VERITY_FEC_MAX_RSN]; /* erasures for decode_rs8 */ 54 u8 *bufs[DM_VERITY_FEC_BUF_MAX]; /* bufs for deinterleaving */ 55 unsigned int nbufs; /* number of buffers allocated */ 56 u8 *output; /* buffer for corrected output */ 57 unsigned int level; /* recursion level */ 58 }; 59 60 #ifdef CONFIG_DM_VERITY_FEC 61 62 /* each feature parameter requires a value */ 63 #define DM_VERITY_OPTS_FEC 8 64 65 extern bool verity_fec_is_enabled(struct dm_verity *v); 66 67 extern int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io, 68 enum verity_block_type type, const u8 *want_digest, 69 sector_t block, u8 *dest); 70 71 extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz, 72 char *result, unsigned int maxlen); 73 74 extern void verity_fec_finish_io(struct dm_verity_io *io); 75 extern void verity_fec_init_io(struct dm_verity_io *io); 76 77 extern bool verity_is_fec_opt_arg(const char *arg_name); 78 extern int verity_fec_parse_opt_args(struct dm_arg_set *as, 79 struct dm_verity *v, unsigned int *argc, 80 const char *arg_name); 81 82 extern void verity_fec_dtr(struct dm_verity *v); 83 84 extern int verity_fec_ctr_alloc(struct dm_verity *v); 85 extern int verity_fec_ctr(struct dm_verity *v); 86 87 #else /* !CONFIG_DM_VERITY_FEC */ 88 89 #define DM_VERITY_OPTS_FEC 0 90 91 static inline bool verity_fec_is_enabled(struct dm_verity *v) 92 { 93 return false; 94 } 95 96 static inline int verity_fec_decode(struct dm_verity *v, 97 struct dm_verity_io *io, 98 enum verity_block_type type, 99 const u8 *want_digest, 100 sector_t block, u8 *dest) 101 { 102 return -EOPNOTSUPP; 103 } 104 105 static inline unsigned int verity_fec_status_table(struct dm_verity *v, 106 unsigned int sz, char *result, 107 unsigned int maxlen) 108 { 109 return sz; 110 } 111 112 static inline void verity_fec_finish_io(struct dm_verity_io *io) 113 { 114 } 115 116 static inline void verity_fec_init_io(struct dm_verity_io *io) 117 { 118 } 119 120 static inline bool verity_is_fec_opt_arg(const char *arg_name) 121 { 122 return false; 123 } 124 125 static inline int verity_fec_parse_opt_args(struct dm_arg_set *as, 126 struct dm_verity *v, 127 unsigned int *argc, 128 const char *arg_name) 129 { 130 return -EINVAL; 131 } 132 133 static inline void verity_fec_dtr(struct dm_verity *v) 134 { 135 } 136 137 static inline int verity_fec_ctr_alloc(struct dm_verity *v) 138 { 139 return 0; 140 } 141 142 static inline int verity_fec_ctr(struct dm_verity *v) 143 { 144 return 0; 145 } 146 147 #endif /* CONFIG_DM_VERITY_FEC */ 148 149 #endif /* DM_VERITY_FEC_H */ 150