1 /* 2 * Cryptographic API. 3 * 4 * Cipher operations. 5 * 6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 7 * 2002 Adam J. Richter <adam@yggdrasil.com> 8 * 2004 Jean-Luc Cooke <jlcooke@certainkey.com> 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License as published by the Free 12 * Software Foundation; either version 2 of the License, or (at your option) 13 * any later version. 14 * 15 */ 16 17 #include <crypto/scatterwalk.h> 18 #include <linux/kernel.h> 19 #include <linux/mm.h> 20 #include <linux/module.h> 21 #include <linux/pagemap.h> 22 #include <linux/highmem.h> 23 #include <linux/scatterlist.h> 24 25 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) 26 { 27 void *src = out ? buf : sgdata; 28 void *dst = out ? sgdata : buf; 29 30 memcpy(dst, src, nbytes); 31 } 32 33 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg) 34 { 35 walk->sg = sg; 36 37 BUG_ON(!sg->length); 38 39 walk->offset = sg->offset; 40 } 41 EXPORT_SYMBOL_GPL(scatterwalk_start); 42 43 void *scatterwalk_map(struct scatter_walk *walk, int out) 44 { 45 return crypto_kmap(scatterwalk_page(walk), out) + 46 offset_in_page(walk->offset); 47 } 48 EXPORT_SYMBOL_GPL(scatterwalk_map); 49 50 static void scatterwalk_pagedone(struct scatter_walk *walk, int out, 51 unsigned int more) 52 { 53 if (out) { 54 struct page *page; 55 56 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); 57 flush_dcache_page(page); 58 } 59 60 if (more) { 61 walk->offset += PAGE_SIZE - 1; 62 walk->offset &= PAGE_MASK; 63 if (walk->offset >= walk->sg->offset + walk->sg->length) 64 scatterwalk_start(walk, scatterwalk_sg_next(walk->sg)); 65 } 66 } 67 68 void scatterwalk_done(struct scatter_walk *walk, int out, int more) 69 { 70 if (!offset_in_page(walk->offset) || !more) 71 scatterwalk_pagedone(walk, out, more); 72 } 73 EXPORT_SYMBOL_GPL(scatterwalk_done); 74 75 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 76 size_t nbytes, int out) 77 { 78 for (;;) { 79 unsigned int len_this_page = scatterwalk_pagelen(walk); 80 u8 *vaddr; 81 82 if (len_this_page > nbytes) 83 len_this_page = nbytes; 84 85 vaddr = scatterwalk_map(walk, out); 86 memcpy_dir(buf, vaddr, len_this_page, out); 87 scatterwalk_unmap(vaddr, out); 88 89 scatterwalk_advance(walk, len_this_page); 90 91 if (nbytes == len_this_page) 92 break; 93 94 buf += len_this_page; 95 nbytes -= len_this_page; 96 97 scatterwalk_pagedone(walk, out, 1); 98 } 99 } 100 EXPORT_SYMBOL_GPL(scatterwalk_copychunks); 101 102 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 103 unsigned int start, unsigned int nbytes, int out) 104 { 105 struct scatter_walk walk; 106 unsigned int offset = 0; 107 108 if (!nbytes) 109 return; 110 111 for (;;) { 112 scatterwalk_start(&walk, sg); 113 114 if (start < offset + sg->length) 115 break; 116 117 offset += sg->length; 118 sg = scatterwalk_sg_next(sg); 119 } 120 121 scatterwalk_advance(&walk, start - offset); 122 scatterwalk_copychunks(buf, &walk, nbytes, out); 123 scatterwalk_done(&walk, out, 0); 124 } 125 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); 126