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, 26 int chain, int num) 27 { 28 if (chain) { 29 head->length += sg->length; 30 sg = sg_next(sg); 31 } 32 33 if (sg) 34 sg_chain(head, num, sg); 35 else 36 sg_mark_end(head); 37 } 38 39 static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in, 40 struct scatter_walk *walk_out) 41 { 42 return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) + 43 (int)(walk_in->offset - walk_out->offset)); 44 } 45 46 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk) 47 { 48 unsigned int len = walk->sg->offset + walk->sg->length - walk->offset; 49 unsigned int len_this_page = offset_in_page(~walk->offset) + 1; 50 return len_this_page > len ? len : len_this_page; 51 } 52 53 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk, 54 unsigned int nbytes) 55 { 56 unsigned int len_this_page = scatterwalk_pagelen(walk); 57 return nbytes > len_this_page ? len_this_page : nbytes; 58 } 59 60 static inline void scatterwalk_advance(struct scatter_walk *walk, 61 unsigned int nbytes) 62 { 63 walk->offset += nbytes; 64 } 65 66 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk, 67 unsigned int alignmask) 68 { 69 return !(walk->offset & alignmask); 70 } 71 72 static inline struct page *scatterwalk_page(struct scatter_walk *walk) 73 { 74 return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT); 75 } 76 77 static inline void scatterwalk_unmap(void *vaddr) 78 { 79 kunmap_atomic(vaddr); 80 } 81 82 static inline void scatterwalk_start(struct scatter_walk *walk, 83 struct scatterlist *sg) 84 { 85 walk->sg = sg; 86 walk->offset = sg->offset; 87 } 88 89 static inline void *scatterwalk_map(struct scatter_walk *walk) 90 { 91 return kmap_atomic(scatterwalk_page(walk)) + 92 offset_in_page(walk->offset); 93 } 94 95 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out, 96 unsigned int more) 97 { 98 if (out) { 99 struct page *page; 100 101 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); 102 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as 103 * PageSlab cannot be optimised away per se due to 104 * use of volatile pointer. 105 */ 106 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page)) 107 flush_dcache_page(page); 108 } 109 110 if (more && walk->offset >= walk->sg->offset + walk->sg->length) 111 scatterwalk_start(walk, sg_next(walk->sg)); 112 } 113 114 static inline void scatterwalk_done(struct scatter_walk *walk, int out, 115 int more) 116 { 117 if (!more || walk->offset >= walk->sg->offset + walk->sg->length || 118 !(walk->offset & (PAGE_SIZE - 1))) 119 scatterwalk_pagedone(walk, out, more); 120 } 121 122 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 123 size_t nbytes, int out); 124 void *scatterwalk_map(struct scatter_walk *walk); 125 126 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 127 unsigned int start, unsigned int nbytes, int out); 128 129 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], 130 struct scatterlist *src, 131 unsigned int len); 132 133 #endif /* _CRYPTO_SCATTERWALK_H */ 134