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 unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,

    72 						struct scatter_walk *walk_out)

    73 {

    74 	return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +

    75 		 (int)(walk_in->offset - walk_out->offset));

    76 }

    77 

    78 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)

    79 {

    80 	unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;

    81 	unsigned int len_this_page = offset_in_page(~walk->offset) + 1;

    82 	return len_this_page > len ? len : len_this_page;

    83 }

    84 

    85 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,

    86 					     unsigned int nbytes)

    87 {

    88 	unsigned int len_this_page = scatterwalk_pagelen(walk);

    89 	return nbytes > len_this_page ? len_this_page : nbytes;

    90 }

    91 

    92 static inline void scatterwalk_advance(struct scatter_walk *walk,

    93 				       unsigned int nbytes)

    94 {

    95 	walk->offset += nbytes;

    96 }

    97 

    98 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,

    99 					       unsigned int alignmask)

   100 {

   101 	return !(walk->offset & alignmask);

   102 }

   103 

   104 static inline struct page *scatterwalk_page(struct scatter_walk *walk)

   105 {

   106 	return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);

   107 }

   108 

   109 static inline void scatterwalk_unmap(void *vaddr, int out)

   110 {

   111 	crypto_kunmap(vaddr, out);

   112 }

   113 

   114 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);

   115 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,

   116 			    size_t nbytes, int out);

   117 void *scatterwalk_map(struct scatter_walk *walk, int out);

   118 void scatterwalk_done(struct scatter_walk *walk, int out, int more);

   119 

   120 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,

   121 			      unsigned int start, unsigned int nbytes, int out);

   122 

   123 #endif  /* _CRYPTO_SCATTERWALK_H */