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/*
* Cryptographic API.
*
* Cipher operations.
*
* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
* 2002 Adam J. Richter <adam@yggdrasil.com>
* 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <asm/bug.h>
#include <asm/scatterlist.h>
#include "internal.h"
#include "scatterwalk.h"
enum km_type crypto_km_types[] = {
KM_USER0,
KM_USER1,
KM_SOFTIRQ0,
KM_SOFTIRQ1,
};
static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
{
if (out)
memcpy(sgdata, buf, nbytes);
else
memcpy(buf, sgdata, nbytes);
}
void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
{
unsigned int rest_of_page;
walk->sg = sg;
walk->page = sg->page;
walk->len_this_segment = sg->length;
BUG_ON(!sg->length);
rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
walk->len_this_page = min(sg->length, rest_of_page);
walk->offset = sg->offset;
}
void scatterwalk_map(struct scatter_walk *walk, int out)
{
walk->data = crypto_kmap(walk->page, out) + walk->offset;
}
static inline void scatterwalk_unmap(struct scatter_walk *walk, int out)
{
/* walk->data may be pointing the first byte of the next page;
however, we know we transfered at least one byte. So,
walk->data - 1 will be a virtual address in the mapped page. */
crypto_kunmap(walk->data - 1, out);
}
static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
unsigned int more)
{
if (out)
flush_dcache_page(walk->page);
if (more) {
walk->len_this_segment -= walk->len_this_page;
if (walk->len_this_segment) {
walk->page++;
walk->len_this_page = min(walk->len_this_segment,
(unsigned)PAGE_CACHE_SIZE);
walk->offset = 0;
}
else
scatterwalk_start(walk, sg_next(walk->sg));
}
}
void scatterwalk_done(struct scatter_walk *walk, int out, int more)
{
scatterwalk_unmap(walk, out);
if (walk->len_this_page == 0 || !more)
scatterwalk_pagedone(walk, out, more);
}
/*
* Do not call this unless the total length of all of the fragments
* has been verified as multiple of the block size.
*/
int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
size_t nbytes, int out)
{
do {
memcpy_dir(buf, walk->data, walk->len_this_page, out);
buf += walk->len_this_page;
nbytes -= walk->len_this_page;
scatterwalk_unmap(walk, out);
scatterwalk_pagedone(walk, out, 1);
scatterwalk_map(walk, out);
} while (nbytes > walk->len_this_page);
memcpy_dir(buf, walk->data, nbytes, out);
return nbytes;
}
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