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 #include <linux/kernel.h> 17 #include <linux/mm.h> 18 #include <linux/module.h> 19 #include <linux/pagemap.h> 20 #include <linux/highmem.h> 21 #include <linux/scatterlist.h> 22 23 #include "internal.h" 24 #include "scatterwalk.h" 25 26 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) 27 { 28 void *src = out ? buf : sgdata; 29 void *dst = out ? sgdata : buf; 30 31 memcpy(dst, src, nbytes); 32 } 33 34 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg) 35 { 36 walk->sg = sg; 37 38 BUG_ON(!sg->length); 39 40 walk->offset = sg->offset; 41 } 42 EXPORT_SYMBOL_GPL(scatterwalk_start); 43 44 void *scatterwalk_map(struct scatter_walk *walk, int out) 45 { 46 return crypto_kmap(scatterwalk_page(walk), out) + 47 offset_in_page(walk->offset); 48 } 49 EXPORT_SYMBOL_GPL(scatterwalk_map); 50 51 static void scatterwalk_pagedone(struct scatter_walk *walk, int out, 52 unsigned int more) 53 { 54 if (out) { 55 struct page *page; 56 57 page = walk->sg->page + ((walk->offset - 1) >> PAGE_SHIFT); 58 flush_dcache_page(page); 59 } 60 61 if (more) { 62 walk->offset += PAGE_SIZE - 1; 63 walk->offset &= PAGE_MASK; 64 if (walk->offset >= walk->sg->offset + walk->sg->length) 65 scatterwalk_start(walk, scatterwalk_sg_next(walk->sg)); 66 } 67 } 68 69 void scatterwalk_done(struct scatter_walk *walk, int out, int more) 70 { 71 if (!offset_in_page(walk->offset) || !more) 72 scatterwalk_pagedone(walk, out, more); 73 } 74 EXPORT_SYMBOL_GPL(scatterwalk_done); 75 76 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 77 size_t nbytes, int out) 78 { 79 for (;;) { 80 unsigned int len_this_page = scatterwalk_pagelen(walk); 81 u8 *vaddr; 82 83 if (len_this_page > nbytes) 84 len_this_page = nbytes; 85 86 vaddr = scatterwalk_map(walk, out); 87 memcpy_dir(buf, vaddr, len_this_page, out); 88 scatterwalk_unmap(vaddr, out); 89 90 scatterwalk_advance(walk, len_this_page); 91 92 if (nbytes == len_this_page) 93 break; 94 95 buf += len_this_page; 96 nbytes -= len_this_page; 97 98 scatterwalk_pagedone(walk, out, 1); 99 } 100 } 101 EXPORT_SYMBOL_GPL(scatterwalk_copychunks); 102 103 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 104 unsigned int start, unsigned int nbytes, int out) 105 { 106 struct scatter_walk walk; 107 unsigned int offset = 0; 108 109 for (;;) { 110 scatterwalk_start(&walk, sg); 111 112 if (start < offset + sg->length) 113 break; 114 115 offset += sg->length; 116 sg = sg_next(sg); 117 } 118 119 scatterwalk_advance(&walk, start - offset); 120 scatterwalk_copychunks(buf, &walk, nbytes, out); 121 scatterwalk_done(&walk, out, 0); 122 } 123 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); 124