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 enum km_type crypto_kmap_type(int out)
  29 {
  30         enum km_type type;
  31
  32         if (in_softirq())
  33                 type = out * (KM_SOFTIRQ1 - KM_SOFTIRQ0) + KM_SOFTIRQ0;
  34         else
  35                 type = out * (KM_USER1 - KM_USER0) + KM_USER0;
  36
  37         return type;
  38 }
  39
  40 static inline void *crypto_kmap(struct page *page, int out)
  41 {
  42         return kmap_atomic(page, crypto_kmap_type(out));
  43 }
  44
  45 static inline void crypto_kunmap(void *vaddr, int out)
  46 {
  47         kunmap_atomic(vaddr, crypto_kmap_type(out));
  48 }
  49
  50 static inline void crypto_yield(u32 flags)
  51 {
  52         if (flags & CRYPTO_TFM_REQ_MAY_SLEEP)
  53                 cond_resched();
  54 }
  55
  56 static inline void scatterwalk_sg_chain(struct scatterlist *sg1, int num,
  57                                         struct scatterlist *sg2)
  58 {
  59         sg_set_page(&sg1[num - 1], (void *)sg2, 0, 0);
  60         sg1[num - 1].page_link &= ~0x02;
  61 }
  62
  63 static inline struct scatterlist *scatterwalk_sg_next(struct scatterlist *sg)
  64 {
  65         if (sg_is_last(sg))
  66                 return NULL;
  67
  68         return (++sg)->length ? sg : (void *)sg_page(sg);
  69 }
  70
  71 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
  72                                             struct scatterlist *sg,
  73                                             int chain, int num)
  74 {
  75         if (chain) {
  76                 head->length += sg->length;
  77                 sg = scatterwalk_sg_next(sg);
  78         }
  79
  80         if (sg)
  81                 scatterwalk_sg_chain(head, num, sg);
  82         else
  83                 sg_mark_end(head);
  84 }
  85
  86 static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
  87                                                 struct scatter_walk *walk_out)
  88 {
  89         return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
  90                  (int)(walk_in->offset - walk_out->offset));
  91 }
  92
  93 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  94 {
  95         unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  96         unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  97         return len_this_page > len ? len : len_this_page;
  98 }
  99
 100 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
 101                                              unsigned int nbytes)
 102 {
 103         unsigned int len_this_page = scatterwalk_pagelen(walk);
 104         return nbytes > len_this_page ? len_this_page : nbytes;
 105 }
 106
 107 static inline void scatterwalk_advance(struct scatter_walk *walk,
 108                                        unsigned int nbytes)
 109 {
 110         walk->offset += nbytes;
 111 }
 112
 113 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
 114                                                unsigned int alignmask)
 115 {
 116         return !(walk->offset & alignmask);
 117 }
 118
 119 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
 120 {
 121         return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
 122 }
 123
 124 static inline void scatterwalk_unmap(void *vaddr, int out)
 125 {
 126         crypto_kunmap(vaddr, out);
 127 }
 128
 129 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
 130 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 131                             size_t nbytes, int out);
 132 void *scatterwalk_map(struct scatter_walk *walk, int out);
 133 void scatterwalk_done(struct scatter_walk *walk, int out, int more);
 134
 135 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 136                               unsigned int start, unsigned int nbytes, int out);
 137
 138 #endif  /* _CRYPTO_SCATTERWALK_H */