scatterwalk.h

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/*
 * Cryptographic scatter and gather helpers.
 *
 * Copyright (c) 2002 James Morris <[email protected]>
 * Copyright (c) 2002 Adam J. Richter <[email protected]>
 * Copyright (c) 2004 Jean-Luc Cooke <[email protected]>
 * Copyright (c) 2007 Herbert Xu <[email protected]>
 *
 * 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.
 *
 */

#ifndef _CRYPTO_SCATTERWALK_H
#define _CRYPTO_SCATTERWALK_H

#include <asm/kmap_types.h>
#include <crypto/algapi.h>
#include <linux/hardirq.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>

static inline void crypto_yield(u32 flags)
{
    if (flags & CRYPTO_TFM_REQ_MAY_SLEEP)
        cond_resched();
}

static inline void scatterwalk_sg_chain(struct scatterlist *sg1, int num,
                    struct scatterlist *sg2)
{
    sg_set_page(&sg1[num - 1], (void *)sg2, 0, 0);
    sg1[num - 1].page_link &= ~0x02;
}

static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist *sg)
{
    if (sg_is_last(sg))
        return NULL;

    return (++sg)->length ? sg : (void *)sg_page(sg);
}

static inline void scatterwalk_crypto_chain(struct scatterlist *head,
                        struct scatterlist *sg,
                        int chain, int num)
{
    if (chain) {
        head->length += sg->length;
        sg = scatterwalk_sg_next(sg);
    }

    if (sg)
        scatterwalk_sg_chain(head, num, sg);
    else
        sg_mark_end(head);
}

static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
                        struct scatter_walk *walk_out)
{
    return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
         (int)(walk_in->offset - walk_out->offset));
}

static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
{
    unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
    unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
    return len_this_page > len ? len : len_this_page;
}

static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
                         unsigned int nbytes)
{
    unsigned int len_this_page = scatterwalk_pagelen(walk);
    return nbytes > len_this_page ? len_this_page : nbytes;
}

static inline void scatterwalk_advance(struct scatter_walk *walk,
                       unsigned int nbytes)
{
    walk->offset += nbytes;
}

static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
                           unsigned int alignmask)
{
    return !(walk->offset & alignmask);
}

static inline struct page *scatterwalk_page(struct scatter_walk *walk)
{
    return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
}

static inline void scatterwalk_unmap(void *vaddr)
{
    kunmap_atomic(vaddr);
}

void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
                size_t nbytes, int out);
void *scatterwalk_map(struct scatter_walk *walk);
void scatterwalk_done(struct scatter_walk *walk, int out, int more);

void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
                  unsigned int start, unsigned int nbytes, int out);

#endif  /* _CRYPTO_SCATTERWALK_H */