crypto: scatterwalk - Use sg_chain_ptr on chain entries
[linux-3.10.git] / 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
28 static inline void crypto_yield(u32 flags)
29 {
30         if (flags & CRYPTO_TFM_REQ_MAY_SLEEP)
31                 cond_resched();
32 }
33
34 static 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
42 static 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
50 static 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
65 static 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
72 static 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
79 static 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
86 static inline void scatterwalk_advance(struct scatter_walk *walk,
87                                        unsigned int nbytes)
88 {
89         walk->offset += nbytes;
90 }
91
92 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
93                                                unsigned int alignmask)
94 {
95         return !(walk->offset & alignmask);
96 }
97
98 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
99 {
100         return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
101 }
102
103 static inline void scatterwalk_unmap(void *vaddr)
104 {
105         kunmap_atomic(vaddr);
106 }
107
108 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
109 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
110                             size_t nbytes, int out);
111 void *scatterwalk_map(struct scatter_walk *walk);
112 void scatterwalk_done(struct scatter_walk *walk, int out, int more);
113
114 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
115                               unsigned int start, unsigned int nbytes, int out);
116
117 #endif  /* _CRYPTO_SCATTERWALK_H */