Root/include/crypto/scatterwalk.h

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    sg1[num - 1].page_link |= 0x01;
40}
41
42static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist *sg)
43{
44    if (sg_is_last(sg))
45        return NULL;
46
47    return (++sg)->length ? sg : sg_chain_ptr(sg);
48}
49
50static inline void scatterwalk_crypto_chain(struct scatterlist *head,
51                        struct scatterlist *sg,
52                        int chain, int num)
53{
54    if (chain) {
55        head->length += sg->length;
56        sg = scatterwalk_sg_next(sg);
57    }
58
59    if (sg)
60        scatterwalk_sg_chain(head, num, sg);
61    else
62        sg_mark_end(head);
63}
64
65static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
66                        struct scatter_walk *walk_out)
67{
68    return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
69         (int)(walk_in->offset - walk_out->offset));
70}
71
72static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
73{
74    unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
75    unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
76    return len_this_page > len ? len : len_this_page;
77}
78
79static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
80                         unsigned int nbytes)
81{
82    unsigned int len_this_page = scatterwalk_pagelen(walk);
83    return nbytes > len_this_page ? len_this_page : nbytes;
84}
85
86static inline void scatterwalk_advance(struct scatter_walk *walk,
87                       unsigned int nbytes)
88{
89    walk->offset += nbytes;
90}
91
92static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
93                           unsigned int alignmask)
94{
95    return !(walk->offset & alignmask);
96}
97
98static inline struct page *scatterwalk_page(struct scatter_walk *walk)
99{
100    return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
101}
102
103static inline void scatterwalk_unmap(void *vaddr)
104{
105    kunmap_atomic(vaddr);
106}
107
108void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
109void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
110                size_t nbytes, int out);
111void *scatterwalk_map(struct scatter_walk *walk);
112void scatterwalk_done(struct scatter_walk *walk, int out, int more);
113
114void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
115                  unsigned int start, unsigned int nbytes, int out);
116
117int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes);
118
119#endif /* _CRYPTO_SCATTERWALK_H */
120

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