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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
Herbert Xu42c271c2007-12-07 18:52:49 +080016
17#include <crypto/scatterwalk.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/kernel.h>
19#include <linux/mm.h>
Herbert Xu5c640972006-08-12 21:56:17 +100020#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/pagemap.h>
22#include <linux/highmem.h>
Herbert Xu5c640972006-08-12 21:56:17 +100023#include <linux/scatterlist.h>
24
Herbert Xu5c640972006-08-12 21:56:17 +100025static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
Linus Torvalds1da177e2005-04-16 15:20:36 -070026{
Herbert Xu5c640972006-08-12 21:56:17 +100027 void *src = out ? buf : sgdata;
28 void *dst = out ? sgdata : buf;
29
30 memcpy(dst, src, nbytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -070031}
32
33void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
34{
Linus Torvalds1da177e2005-04-16 15:20:36 -070035 walk->sg = sg;
36
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 BUG_ON(!sg->length);
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 walk->offset = sg->offset;
40}
Herbert Xu5c640972006-08-12 21:56:17 +100041EXPORT_SYMBOL_GPL(scatterwalk_start);
Linus Torvalds1da177e2005-04-16 15:20:36 -070042
Herbert Xu5c640972006-08-12 21:56:17 +100043void *scatterwalk_map(struct scatter_walk *walk, int out)
Linus Torvalds1da177e2005-04-16 15:20:36 -070044{
Herbert Xu5c640972006-08-12 21:56:17 +100045 return crypto_kmap(scatterwalk_page(walk), out) +
46 offset_in_page(walk->offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -070047}
Herbert Xu5c640972006-08-12 21:56:17 +100048EXPORT_SYMBOL_GPL(scatterwalk_map);
Linus Torvalds1da177e2005-04-16 15:20:36 -070049
50static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
51 unsigned int more)
52{
Herbert Xu9f116722007-03-31 12:58:20 +100053 if (out) {
54 struct page *page;
55
Jens Axboe78c2f0b2007-10-22 19:40:16 +020056 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
Herbert Xu9f116722007-03-31 12:58:20 +100057 flush_dcache_page(page);
58 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60 if (more) {
Herbert Xu5c640972006-08-12 21:56:17 +100061 walk->offset += PAGE_SIZE - 1;
62 walk->offset &= PAGE_MASK;
63 if (walk->offset >= walk->sg->offset + walk->sg->length)
Herbert Xu468577a2007-11-15 12:08:45 +080064 scatterwalk_start(walk, sg_next(walk->sg));
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 }
66}
67
68void scatterwalk_done(struct scatter_walk *walk, int out, int more)
69{
Herbert Xu5c640972006-08-12 21:56:17 +100070 if (!offset_in_page(walk->offset) || !more)
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 scatterwalk_pagedone(walk, out, more);
72}
Herbert Xu5c640972006-08-12 21:56:17 +100073EXPORT_SYMBOL_GPL(scatterwalk_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -070074
Herbert Xu5c640972006-08-12 21:56:17 +100075void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
76 size_t nbytes, int out)
Linus Torvalds1da177e2005-04-16 15:20:36 -070077{
Herbert Xu5c640972006-08-12 21:56:17 +100078 for (;;) {
79 unsigned int len_this_page = scatterwalk_pagelen(walk);
80 u8 *vaddr;
Linus Torvalds1da177e2005-04-16 15:20:36 -070081
Herbert Xu5c640972006-08-12 21:56:17 +100082 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
Herbert Xu4ee531a2007-03-31 12:16:20 +100089 scatterwalk_advance(walk, len_this_page);
J. Bruce Fieldsf70ee5e2007-03-21 08:50:12 +110090
Herbert Xu5c640972006-08-12 21:56:17 +100091 if (nbytes == len_this_page)
92 break;
93
94 buf += len_this_page;
95 nbytes -= len_this_page;
96
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 scatterwalk_pagedone(walk, out, 1);
Herbert Xuc774e932005-07-06 13:51:31 -070098 }
Linus Torvalds1da177e2005-04-16 15:20:36 -070099}
Herbert Xu5c640972006-08-12 21:56:17 +1000100EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
Herbert Xu5fa0fea2007-08-29 16:31:34 +0800101
102void 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 for (;;) {
109 scatterwalk_start(&walk, sg);
110
111 if (start < offset + sg->length)
112 break;
113
114 offset += sg->length;
115 sg = sg_next(sg);
116 }
117
118 scatterwalk_advance(&walk, start - offset);
119 scatterwalk_copychunks(buf, &walk, nbytes, out);
120 scatterwalk_done(&walk, out, 0);
121}
122EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);