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 scatterwalk_sg_chain(struct scatterlist *sg1, int num,
  29                                         struct scatterlist *sg2)
  30 {
  31         sg_set_page(&sg1[num - 1], (void *)sg2, 0, 0);
  32         sg1[num - 1].page_link &= ~0x02;
  33         sg1[num - 1].page_link |= 0x01;
  34 }
  35
  36 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
  37                                             struct scatterlist *sg,
  38                                             int chain, int num)
  39 {
  40         if (chain) {
  41                 head->length += sg->length;
  42                 sg = sg_next(sg);
  43         }
  44
  45         if (sg)
  46                 scatterwalk_sg_chain(head, num, sg);
  47         else
  48                 sg_mark_end(head);
  49 }
  50
  51 static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
  52                                                 struct scatter_walk *walk_out)
  53 {
  54         return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
  55                  (int)(walk_in->offset - walk_out->offset));
  56 }
  57
  58 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  59 {
  60         unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  61         unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  62         return len_this_page > len ? len : len_this_page;
  63 }
  64
  65 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
  66                                              unsigned int nbytes)
  67 {
  68         unsigned int len_this_page = scatterwalk_pagelen(walk);
  69         return nbytes > len_this_page ? len_this_page : nbytes;
  70 }
  71
  72 static inline void scatterwalk_advance(struct scatter_walk *walk,
  73                                        unsigned int nbytes)
  74 {
  75         walk->offset += nbytes;
  76 }
  77
  78 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  79                                                unsigned int alignmask)
  80 {
  81         return !(walk->offset & alignmask);
  82 }
  83
  84 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  85 {
  86         return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
  87 }
  88
  89 static inline void scatterwalk_unmap(void *vaddr)
  90 {
  91         kunmap_atomic(vaddr);
  92 }
  93
  94 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
  95 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
  96                             size_t nbytes, int out);
  97 void *scatterwalk_map(struct scatter_walk *walk);
  98 void scatterwalk_done(struct scatter_walk *walk, int out, int more);
  99
 100 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
 101                               unsigned int start, unsigned int nbytes, int out);
 102
 103 int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes);
 104
 105 #endif  /* _CRYPTO_SCATTERWALK_H */