1 /* 2 * Cryptographic scatter and gather helpers. 3 * 4 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 5 * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com> 6 * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com> 7 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License as published by the Free 11 * Software Foundation; either version 2 of the License, or (at your option) 12 * any later version. 13 * 14 */ 15 16 #ifndef _CRYPTO_SCATTERWALK_H 17 #define _CRYPTO_SCATTERWALK_H 18 19 #include <crypto/algapi.h> 20 #include <linux/highmem.h> 21 #include <linux/kernel.h> 22 #include <linux/scatterlist.h> 23 24 static inline void scatterwalk_crypto_chain(struct scatterlist *head, 25 struct scatterlist *sg, int num) 26 { 27 if (sg) 28 sg_chain(head, num, sg); 29 else 30 sg_mark_end(head); 31 } 32 33 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk) 34 { 35 unsigned int len = walk->sg->offset + walk->sg->length - walk->offset; 36 unsigned int len_this_page = offset_in_page(~walk->offset) + 1; 37 return len_this_page > len ? len : len_this_page; 38 } 39 40 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk, 41 unsigned int nbytes) 42 { 43 unsigned int len_this_page = scatterwalk_pagelen(walk); 44 return nbytes > len_this_page ? len_this_page : nbytes; 45 } 46 47 static inline void scatterwalk_advance(struct scatter_walk *walk, 48 unsigned int nbytes) 49 { 50 walk->offset += nbytes; 51 } 52 53 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk, 54 unsigned int alignmask) 55 { 56 return !(walk->offset & alignmask); 57 } 58 59 static inline struct page *scatterwalk_page(struct scatter_walk *walk) 60 { 61 return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT); 62 } 63 64 static inline void scatterwalk_unmap(void *vaddr) 65 { 66 kunmap_atomic(vaddr); 67 } 68 69 static inline void scatterwalk_start(struct scatter_walk *walk, 70 struct scatterlist *sg) 71 { 72 walk->sg = sg; 73 walk->offset = sg->offset; 74 } 75 76 static inline void *scatterwalk_map(struct scatter_walk *walk) 77 { 78 return kmap_atomic(scatterwalk_page(walk)) + 79 offset_in_page(walk->offset); 80 } 81 82 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out, 83 unsigned int more) 84 { 85 if (out) { 86 struct page *page; 87 88 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); 89 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as 90 * PageSlab cannot be optimised away per se due to 91 * use of volatile pointer. 92 */ 93 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page)) 94 flush_dcache_page(page); 95 } 96 97 if (more && walk->offset >= walk->sg->offset + walk->sg->length) 98 scatterwalk_start(walk, sg_next(walk->sg)); 99 } 100 101 static inline void scatterwalk_done(struct scatter_walk *walk, int out, 102 int more) 103 { 104 if (!more || walk->offset >= walk->sg->offset + walk->sg->length || 105 !(walk->offset & (PAGE_SIZE - 1))) 106 scatterwalk_pagedone(walk, out, more); 107 } 108 109 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 110 size_t nbytes, int out); 111 void *scatterwalk_map(struct scatter_walk *walk); 112 113 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 114 unsigned int start, unsigned int nbytes, int out); 115 116 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], 117 struct scatterlist *src, 118 unsigned int len); 119 120 #endif /* _CRYPTO_SCATTERWALK_H */ 121