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