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/scatterlist.h> 22 23 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) 24 { 25 void *src = out ? buf : sgdata; 26 void *dst = out ? sgdata : buf; 27 28 memcpy(dst, src, nbytes); 29 } 30 31 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 32 size_t nbytes, int out) 33 { 34 for (;;) { 35 unsigned int len_this_page = scatterwalk_pagelen(walk); 36 u8 *vaddr; 37 38 if (len_this_page > nbytes) 39 len_this_page = nbytes; 40 41 if (out != 2) { 42 vaddr = scatterwalk_map(walk); 43 memcpy_dir(buf, vaddr, len_this_page, out); 44 scatterwalk_unmap(vaddr); 45 } 46 47 scatterwalk_advance(walk, len_this_page); 48 49 if (nbytes == len_this_page) 50 break; 51 52 buf += len_this_page; 53 nbytes -= len_this_page; 54 55 scatterwalk_pagedone(walk, out & 1, 1); 56 } 57 } 58 EXPORT_SYMBOL_GPL(scatterwalk_copychunks); 59 60 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 61 unsigned int start, unsigned int nbytes, int out) 62 { 63 struct scatter_walk walk; 64 struct scatterlist tmp[2]; 65 66 if (!nbytes) 67 return; 68 69 sg = scatterwalk_ffwd(tmp, sg, start); 70 71 if (sg_page(sg) == virt_to_page(buf) && 72 sg->offset == offset_in_page(buf)) 73 return; 74 75 scatterwalk_start(&walk, sg); 76 scatterwalk_copychunks(buf, &walk, nbytes, out); 77 scatterwalk_done(&walk, out, 0); 78 } 79 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); 80 81 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], 82 struct scatterlist *src, 83 unsigned int len) 84 { 85 for (;;) { 86 if (!len) 87 return src; 88 89 if (src->length > len) 90 break; 91 92 len -= src->length; 93 src = sg_next(src); 94 } 95 96 sg_init_table(dst, 2); 97 sg_set_page(dst, sg_page(src), src->length - len, src->offset + len); 98 scatterwalk_crypto_chain(dst, sg_next(src), 0, 2); 99 100 return dst; 101 } 102 EXPORT_SYMBOL_GPL(scatterwalk_ffwd); 103