1/*
  2 * Cryptographic scatter and gather helpers.
  3 *
  4 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
  5 * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
  6 * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
  7 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
  8 *
  9 * This program is free software; you can redistribute it and/or modify it
 10 * under the terms of the GNU General Public License as published by the Free
 11 * Software Foundation; either version 2 of the License, or (at your option)
 12 * any later version.
 13 *
 14 */
 15
 16#ifndef _CRYPTO_SCATTERWALK_H
 17#define _CRYPTO_SCATTERWALK_H
 18
 19#include <asm/kmap_types.h>
 20#include <crypto/algapi.h>
 21#include <linux/hardirq.h>
 22#include <linux/highmem.h>
 23#include <linux/kernel.h>
 24#include <linux/mm.h>
 25#include <linux/scatterlist.h>
 26#include <linux/sched.h>
 27
 28static inline void crypto_yield(u32 flags)
 29{
 30	if (flags & CRYPTO_TFM_REQ_MAY_SLEEP)
 31		cond_resched();
 32}
 33
 34static inline void scatterwalk_sg_chain(struct scatterlist *sg1, int num,
 35					struct scatterlist *sg2)
 36{
 37	sg_set_page(&sg1[num - 1], (void *)sg2, 0, 0);
 38	sg1[num - 1].page_link &= ~0x02;
 39}
 40
 41static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist *sg)
 42{
 43	if (sg_is_last(sg))
 44		return NULL;
 45
 46	return (++sg)->length ? sg : (void *)sg_page(sg);
 47}
 48
 49static inline void scatterwalk_crypto_chain(struct scatterlist *head,
 50					    struct scatterlist *sg,
 51					    int chain, int num)
 52{
 53	if (chain) {
 54		head->length += sg->length;
 55		sg = scatterwalk_sg_next(sg);
 56	}
 57
 58	if (sg)
 59		scatterwalk_sg_chain(head, num, sg);
 60	else
 61		sg_mark_end(head);
 62}
 63
 64static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
 65						struct scatter_walk *walk_out)
 66{
 67	return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
 68		 (int)(walk_in->offset - walk_out->offset));
 69}
 70
 71static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
 72{
 73	unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
 74	unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
 75	return len_this_page > len ? len : len_this_page;
 76}
 77
 78static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
 79					     unsigned int nbytes)
 80{
 81	unsigned int len_this_page = scatterwalk_pagelen(walk);
 82	return nbytes > len_this_page ? len_this_page : nbytes;
 83}
 84
 85static inline void scatterwalk_advance(struct scatter_walk *walk,
 86				       unsigned int nbytes)
 87{
 88	walk->offset += nbytes;
 89}
 90
 91static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
 92					       unsigned int alignmask)
 93{
 94	return !(walk->offset & alignmask);
 95}
 96
 97static inline struct page *scatterwalk_page(struct scatter_walk *walk)
 98{
 99	return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
100}
101
102static inline void scatterwalk_unmap(void *vaddr)
103{
104	kunmap_atomic(vaddr);
105}
106
107void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
108void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
109			    size_t nbytes, int out);
110void *scatterwalk_map(struct scatter_walk *walk);
111void scatterwalk_done(struct scatter_walk *walk, int out, int more);
112
113void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
114			      unsigned int start, unsigned int nbytes, int out);
115
116#endif  /* _CRYPTO_SCATTERWALK_H */