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/pagemap.h> 19 #include <linux/highmem.h> 20 #include <asm/scatterlist.h> 21 #include "internal.h" 22 #include "scatterwalk.h" 23 24 enum km_type crypto_km_types[] = { 25 KM_USER0, 26 KM_USER1, 27 KM_SOFTIRQ0, 28 KM_SOFTIRQ1, 29 }; 30 31 static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) 32 { 33 if (out) 34 memcpy(sgdata, buf, nbytes); 35 else 36 memcpy(buf, sgdata, nbytes); 37 } 38 39 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg) 40 { 41 unsigned int rest_of_page; 42 43 walk->sg = sg; 44 45 walk->page = sg->page; 46 walk->len_this_segment = sg->length; 47 48 BUG_ON(!sg->length); 49 50 rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1)); 51 walk->len_this_page = min(sg->length, rest_of_page); 52 walk->offset = sg->offset; 53 } 54 55 void scatterwalk_map(struct scatter_walk *walk, int out) 56 { 57 walk->data = crypto_kmap(walk->page, out) + walk->offset; 58 } 59 60 static inline void scatterwalk_unmap(struct scatter_walk *walk, int out) 61 { 62 /* walk->data may be pointing the first byte of the next page; 63 however, we know we transfered at least one byte. So, 64 walk->data - 1 will be a virtual address in the mapped page. */ 65 crypto_kunmap(walk->data - 1, out); 66 } 67 68 static void scatterwalk_pagedone(struct scatter_walk *walk, int out, 69 unsigned int more) 70 { 71 if (out) 72 flush_dcache_page(walk->page); 73 74 if (more) { 75 walk->len_this_segment -= walk->len_this_page; 76 77 if (walk->len_this_segment) { 78 walk->page++; 79 walk->len_this_page = min(walk->len_this_segment, 80 (unsigned)PAGE_CACHE_SIZE); 81 walk->offset = 0; 82 } 83 else 84 scatterwalk_start(walk, sg_next(walk->sg)); 85 } 86 } 87 88 void scatterwalk_done(struct scatter_walk *walk, int out, int more) 89 { 90 scatterwalk_unmap(walk, out); 91 if (walk->len_this_page == 0 || !more) 92 scatterwalk_pagedone(walk, out, more); 93 } 94 95 /* 96 * Do not call this unless the total length of all of the fragments 97 * has been verified as multiple of the block size. 98 */ 99 int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 100 size_t nbytes, int out) 101 { 102 while (nbytes > walk->len_this_page) { 103 memcpy_dir(buf, walk->data, walk->len_this_page, out); 104 buf += walk->len_this_page; 105 nbytes -= walk->len_this_page; 106 107 scatterwalk_unmap(walk, out); 108 scatterwalk_pagedone(walk, out, 1); 109 scatterwalk_map(walk, out); 110 } 111 112 memcpy_dir(buf, walk->data, nbytes, out); 113 return nbytes; 114 } 115