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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/scatterlist.h>

#include "internal.h"

#include "scatterwalk.h"

enum km_type crypto_km_types[] = {

        KM_USER0,

        KM_USER1,

        KM_SOFTIRQ0,

        KM_SOFTIRQ1,

};

void *scatterwalk_whichbuf(struct scatter_walk *walk, unsigned int nbytes, void *scratch)

{

        if (nbytes <= walk->len_this_page &&

            (((unsigned long)walk->data) & (PAGE_CACHE_SIZE - 1)) + nbytes <=

            PAGE_CACHE_SIZE)

                return walk->data;

        else

                return scratch;

}

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;

        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 void scatterwalk_pagedone(struct scatter_walk *walk, int out,

                                 unsigned int more)

{

        /* 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 virutual address in the mapped page. */

        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)

{

        crypto_kunmap(walk->data, 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)

{

        if (buf != walk->data) {

                while (nbytes > walk->len_this_page) {

                        memcpy_dir(buf, walk->data, walk->len_this_page, out);

                        buf += walk->len_this_page;

                        nbytes -= walk->len_this_page;

                        crypto_kunmap(walk->data, out);

                        scatterwalk_pagedone(walk, out, 1);

                        scatterwalk_map(walk, out);

                }

                memcpy_dir(buf, walk->data, nbytes, out);

        }

        walk->offset += nbytes;

        walk->len_this_page -= nbytes;

        walk->len_this_segment -= nbytes;

        return 0;

}