kernel/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_crypto_chain(struct scatterlist *head,
  29                                             struct scatterlist *sg,
  30                                             int chain, int num)
  31 {
  32         if (chain) {
  33                 head->length += sg->length;
  34                 sg = sg_next(sg);
  35         }
  36
  37         if (sg)
  38                 sg_chain(head, num, sg);
  39         else
  40                 sg_mark_end(head);
  41 }
  42
  43 static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
  44                                                 struct scatter_walk *walk_out)
  45 {
  46         return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
  47                  (int)(walk_in->offset - walk_out->offset));
  48 }
  49
  50 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
  51 {
  52         unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
  53         unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
  54         return len_this_page > len ? len : len_this_page;
  55 }
  56
  57 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
  58                                              unsigned int nbytes)
  59 {
  60         unsigned int len_this_page = scatterwalk_pagelen(walk);
  61         return nbytes > len_this_page ? len_this_page : nbytes;
  62 }
  63
  64 static inline void scatterwalk_advance(struct scatter_walk *walk,
  65                                        unsigned int nbytes)
  66 {
  67         walk->offset += nbytes;
  68 }
  69
  70 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
  71                                                unsigned int alignmask)
  72 {
  73         return !(walk->offset & alignmask);
  74 }
  75
  76 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
  77 {
  78         return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
  79 }
  80
  81 static inline void scatterwalk_unmap(void *vaddr)
  82 {
  83         kunmap_atomic(vaddr);
  84 }
  85
  86 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
  87 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
  88                             size_t nbytes, int out);
  89 void *scatterwalk_map(struct scatter_walk *walk);
  90 void scatterwalk_done(struct scatter_walk *walk, int out, int more);
  91
  92 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
  93                               unsigned int start, unsigned int nbytes, int out);
  94
  95 int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes);
  96
  97 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
  98                                      struct scatterlist *src,
  99                                      unsigned int len);
 100
 101 #endif  /* _CRYPTO_SCATTERWALK_H */