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/*
* Cryptographic API .
*
* Cipher operations .
*
* Copyright ( c ) 2002 James Morris < jmorris @ intercode . com . au >
* 2002 Adam J . Richter < adam @ yggdrasil . com >
* 2004 Jean - Luc Cooke < jlcooke @ certainkey . com >
*
* This program is free software ; you can redistribute it and / or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation ; either version 2 of the License , or ( at your option )
* any later version .
*
*/
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# include <crypto/scatterwalk.h>
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# include <linux/kernel.h>
# include <linux/mm.h>
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# include <linux/module.h>
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# include <linux/pagemap.h>
# include <linux/highmem.h>
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# include <linux/scatterlist.h>
static inline void memcpy_dir ( void * buf , void * sgdata , size_t nbytes , int out )
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{
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void * src = out ? buf : sgdata ;
void * dst = out ? sgdata : buf ;
memcpy ( dst , src , nbytes ) ;
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}
void scatterwalk_start ( struct scatter_walk * walk , struct scatterlist * sg )
{
walk - > sg = sg ;
BUG_ON ( ! sg - > length ) ;
walk - > offset = sg - > offset ;
}
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EXPORT_SYMBOL_GPL ( scatterwalk_start ) ;
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void * scatterwalk_map ( struct scatter_walk * walk )
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{
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return kmap_atomic ( scatterwalk_page ( walk ) ) +
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offset_in_page ( walk - > offset ) ;
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}
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EXPORT_SYMBOL_GPL ( scatterwalk_map ) ;
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static void scatterwalk_pagedone ( struct scatter_walk * walk , int out ,
unsigned int more )
{
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if ( out ) {
struct page * page ;
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page = sg_page ( walk - > sg ) + ( ( walk - > offset - 1 ) > > PAGE_SHIFT ) ;
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/* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
* PageSlab cannot be optimised away per se due to
* use of volatile pointer .
*/
if ( ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE & & ! PageSlab ( page ) )
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flush_dcache_page ( page ) ;
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}
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if ( more ) {
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walk - > offset + = PAGE_SIZE - 1 ;
walk - > offset & = PAGE_MASK ;
if ( walk - > offset > = walk - > sg - > offset + walk - > sg - > length )
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scatterwalk_start ( walk , sg_next ( walk - > sg ) ) ;
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}
}
void scatterwalk_done ( struct scatter_walk * walk , int out , int more )
{
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if ( ! ( scatterwalk_pagelen ( walk ) & ( PAGE_SIZE - 1 ) ) | | ! more )
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scatterwalk_pagedone ( walk , out , more ) ;
}
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EXPORT_SYMBOL_GPL ( scatterwalk_done ) ;
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void scatterwalk_copychunks ( void * buf , struct scatter_walk * walk ,
size_t nbytes , int out )
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{
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for ( ; ; ) {
unsigned int len_this_page = scatterwalk_pagelen ( walk ) ;
u8 * vaddr ;
if ( len_this_page > nbytes )
len_this_page = nbytes ;
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if ( out ! = 2 ) {
vaddr = scatterwalk_map ( walk ) ;
memcpy_dir ( buf , vaddr , len_this_page , out ) ;
scatterwalk_unmap ( vaddr ) ;
}
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scatterwalk_advance ( walk , len_this_page ) ;
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if ( nbytes = = len_this_page )
break ;
buf + = len_this_page ;
nbytes - = len_this_page ;
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scatterwalk_pagedone ( walk , out & 1 , 1 ) ;
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}
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}
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EXPORT_SYMBOL_GPL ( scatterwalk_copychunks ) ;
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void scatterwalk_map_and_copy ( void * buf , struct scatterlist * sg ,
unsigned int start , unsigned int nbytes , int out )
{
struct scatter_walk walk ;
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struct scatterlist tmp [ 2 ] ;
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if ( ! nbytes )
return ;
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sg = scatterwalk_ffwd ( tmp , sg , start ) ;
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if ( sg_page ( sg ) = = virt_to_page ( buf ) & &
sg - > offset = = offset_in_page ( buf ) )
return ;
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scatterwalk_start ( & walk , sg ) ;
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scatterwalk_copychunks ( buf , & walk , nbytes , out ) ;
scatterwalk_done ( & walk , out , 0 ) ;
}
EXPORT_SYMBOL_GPL ( scatterwalk_map_and_copy ) ;
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struct scatterlist * scatterwalk_ffwd ( struct scatterlist dst [ 2 ] ,
struct scatterlist * src ,
unsigned int len )
{
for ( ; ; ) {
if ( ! len )
return src ;
if ( src - > length > len )
break ;
len - = src - > length ;
src = sg_next ( src ) ;
}
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sg_init_table ( dst , 2 ) ;
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sg_set_page ( dst , sg_page ( src ) , src - > length - len , src - > offset + len ) ;
scatterwalk_crypto_chain ( dst , sg_next ( src ) , 0 , 2 ) ;
return dst ;
}
EXPORT_SYMBOL_GPL ( scatterwalk_ffwd ) ;