1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Cryptographic scatter and gather helpers. 4 * 5 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 6 * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com> 7 * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com> 8 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> 9 */ 10 11 #ifndef _CRYPTO_SCATTERWALK_H 12 #define _CRYPTO_SCATTERWALK_H 13 14 #include <crypto/algapi.h> 15 16 #include <linux/highmem.h> 17 #include <linux/mm.h> 18 #include <linux/scatterlist.h> 19 20 static inline void scatterwalk_crypto_chain(struct scatterlist *head, 21 struct scatterlist *sg, int num) 22 { 23 if (sg) 24 sg_chain(head, num, sg); 25 else 26 sg_mark_end(head); 27 } 28 29 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk) 30 { 31 unsigned int len = walk->sg->offset + walk->sg->length - walk->offset; 32 unsigned int len_this_page = offset_in_page(~walk->offset) + 1; 33 return len_this_page > len ? len : len_this_page; 34 } 35 36 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk, 37 unsigned int nbytes) 38 { 39 unsigned int len_this_page = scatterwalk_pagelen(walk); 40 return nbytes > len_this_page ? len_this_page : nbytes; 41 } 42 43 static inline void scatterwalk_advance(struct scatter_walk *walk, 44 unsigned int nbytes) 45 { 46 walk->offset += nbytes; 47 } 48 49 static inline struct page *scatterwalk_page(struct scatter_walk *walk) 50 { 51 return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT); 52 } 53 54 static inline void scatterwalk_unmap(void *vaddr) 55 { 56 kunmap_atomic(vaddr); 57 } 58 59 static inline void scatterwalk_start(struct scatter_walk *walk, 60 struct scatterlist *sg) 61 { 62 walk->sg = sg; 63 walk->offset = sg->offset; 64 } 65 66 static inline void *scatterwalk_map(struct scatter_walk *walk) 67 { 68 return kmap_atomic(scatterwalk_page(walk)) + 69 offset_in_page(walk->offset); 70 } 71 72 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out, 73 unsigned int more) 74 { 75 if (out) { 76 struct page *page; 77 78 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); 79 flush_dcache_page(page); 80 } 81 82 if (more && walk->offset >= walk->sg->offset + walk->sg->length) 83 scatterwalk_start(walk, sg_next(walk->sg)); 84 } 85 86 static inline void scatterwalk_done(struct scatter_walk *walk, int out, 87 int more) 88 { 89 if (!more || walk->offset >= walk->sg->offset + walk->sg->length || 90 !(walk->offset & (PAGE_SIZE - 1))) 91 scatterwalk_pagedone(walk, out, more); 92 } 93 94 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 95 size_t nbytes, int out); 96 97 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 98 unsigned int start, unsigned int nbytes, int out); 99 100 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], 101 struct scatterlist *src, 102 unsigned int len); 103 104 #endif /* _CRYPTO_SCATTERWALK_H */ 105