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 unsigned int 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); 73 74 extern unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz, 75 char *result, unsigned int 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 int *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 { 104 return -EOPNOTSUPP; 105 } 106 107 static inline unsigned int verity_fec_status_table(struct dm_verity *v, 108 unsigned int sz, char *result, 109 unsigned int maxlen) 110 { 111 return sz; 112 } 113 114 static inline void verity_fec_finish_io(struct dm_verity_io *io) 115 { 116 } 117 118 static inline void verity_fec_init_io(struct dm_verity_io *io) 119 { 120 } 121 122 static inline bool verity_is_fec_opt_arg(const char *arg_name) 123 { 124 return false; 125 } 126 127 static inline int verity_fec_parse_opt_args(struct dm_arg_set *as, 128 struct dm_verity *v, 129 unsigned int *argc, 130 const char *arg_name) 131 { 132 return -EINVAL; 133 } 134 135 static inline void verity_fec_dtr(struct dm_verity *v) 136 { 137 } 138 139 static inline int verity_fec_ctr_alloc(struct dm_verity *v) 140 { 141 return 0; 142 } 143 144 static inline int verity_fec_ctr(struct dm_verity *v) 145 { 146 return 0; 147 } 148 149 #endif /* CONFIG_DM_VERITY_FEC */ 150 151 #endif /* DM_VERITY_FEC_H */ 152