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/bug.h> 21 #include <asm/scatterlist.h> 22 #include "internal.h" 23 #include "scatterwalk.h" 24 25 enum km_type crypto_km_types[] = { 26 KM_USER0, 27 KM_USER1, 28 KM_SOFTIRQ0, 29 KM_SOFTIRQ1, 30 }; 31 32 static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) 33 { 34 if (out) 35 memcpy(sgdata, buf, nbytes); 36 else 37 memcpy(buf, sgdata, nbytes); 38 } 39 40 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg) 41 { 42 unsigned int rest_of_page; 43 44 walk->sg = sg; 45 46 walk->page = sg->page; 47 walk->len_this_segment = sg->length; 48 49 BUG_ON(!sg->length); 50 51 rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1)); 52 walk->len_this_page = min(sg->length, rest_of_page); 53 walk->offset = sg->offset; 54 } 55 56 void scatterwalk_map(struct scatter_walk *walk, int out) 57 { 58 walk->data = crypto_kmap(walk->page, out) + walk->offset; 59 } 60 61 static inline void scatterwalk_unmap(struct scatter_walk *walk, int out) 62 { 63 /* walk->data may be pointing the first byte of the next page; 64 however, we know we transfered at least one byte. So, 65 walk->data - 1 will be a virtual address in the mapped page. */ 66 crypto_kunmap(walk->data - 1, out); 67 } 68 69 static void scatterwalk_pagedone(struct scatter_walk *walk, int out, 70 unsigned int more) 71 { 72 if (out) 73 flush_dcache_page(walk->page); 74 75 if (more) { 76 walk->len_this_segment -= walk->len_this_page; 77 78 if (walk->len_this_segment) { 79 walk->page++; 80 walk->len_this_page = min(walk->len_this_segment, 81 (unsigned)PAGE_CACHE_SIZE); 82 walk->offset = 0; 83 } 84 else 85 scatterwalk_start(walk, sg_next(walk->sg)); 86 } 87 } 88 89 void scatterwalk_done(struct scatter_walk *walk, int out, int more) 90 { 91 scatterwalk_unmap(walk, out); 92 if (walk->len_this_page == 0 || !more) 93 scatterwalk_pagedone(walk, out, more); 94 } 95 96 /* 97 * Do not call this unless the total length of all of the fragments 98 * has been verified as multiple of the block size. 99 */ 100 int scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 101 size_t nbytes, int out) 102 { 103 do { 104 memcpy_dir(buf, walk->data, walk->len_this_page, out); 105 buf += walk->len_this_page; 106 nbytes -= walk->len_this_page; 107 108 scatterwalk_unmap(walk, out); 109 scatterwalk_pagedone(walk, out, 1); 110 scatterwalk_map(walk, out); 111 } while (nbytes > walk->len_this_page); 112 113 memcpy_dir(buf, walk->data, nbytes, out); 114 return nbytes; 115 } 116