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 #include <linux/highmem.h> 16 #include <linux/kernel.h> 17 #include <linux/scatterlist.h> 18 19 static inline void scatterwalk_crypto_chain(struct scatterlist *head, 20 struct scatterlist *sg, int num) 21 { 22 if (sg) 23 sg_chain(head, num, sg); 24 else 25 sg_mark_end(head); 26 } 27 28 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk) 29 { 30 unsigned int len = walk->sg->offset + walk->sg->length - walk->offset; 31 unsigned int len_this_page = offset_in_page(~walk->offset) + 1; 32 return len_this_page > len ? len : len_this_page; 33 } 34 35 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk, 36 unsigned int nbytes) 37 { 38 unsigned int len_this_page = scatterwalk_pagelen(walk); 39 return nbytes > len_this_page ? len_this_page : nbytes; 40 } 41 42 static inline void scatterwalk_advance(struct scatter_walk *walk, 43 unsigned int nbytes) 44 { 45 walk->offset += nbytes; 46 } 47 48 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk, 49 unsigned int alignmask) 50 { 51 return !(walk->offset & alignmask); 52 } 53 54 static inline struct page *scatterwalk_page(struct scatter_walk *walk) 55 { 56 return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT); 57 } 58 59 static inline void scatterwalk_unmap(void *vaddr) 60 { 61 kunmap_atomic(vaddr); 62 } 63 64 static inline void scatterwalk_start(struct scatter_walk *walk, 65 struct scatterlist *sg) 66 { 67 walk->sg = sg; 68 walk->offset = sg->offset; 69 } 70 71 static inline void *scatterwalk_map(struct scatter_walk *walk) 72 { 73 return kmap_atomic(scatterwalk_page(walk)) + 74 offset_in_page(walk->offset); 75 } 76 77 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out, 78 unsigned int more) 79 { 80 if (out) { 81 struct page *page; 82 83 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); 84 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as 85 * PageSlab cannot be optimised away per se due to 86 * use of volatile pointer. 87 */ 88 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page)) 89 flush_dcache_page(page); 90 } 91 92 if (more && walk->offset >= walk->sg->offset + walk->sg->length) 93 scatterwalk_start(walk, sg_next(walk->sg)); 94 } 95 96 static inline void scatterwalk_done(struct scatter_walk *walk, int out, 97 int more) 98 { 99 if (!more || walk->offset >= walk->sg->offset + walk->sg->length || 100 !(walk->offset & (PAGE_SIZE - 1))) 101 scatterwalk_pagedone(walk, out, more); 102 } 103 104 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 105 size_t nbytes, int out); 106 void *scatterwalk_map(struct scatter_walk *walk); 107 108 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 109 unsigned int start, unsigned int nbytes, int out); 110 111 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], 112 struct scatterlist *src, 113 unsigned int len); 114 115 #endif /* _CRYPTO_SCATTERWALK_H */ 116