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127 lines
2.9 KiB
C
127 lines
2.9 KiB
C
/*
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* Cryptographic API.
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*
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* Cipher operations.
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*
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* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
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* 2002 Adam J. Richter <adam@yggdrasil.com>
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* 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <crypto/scatterwalk.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/scatterlist.h>
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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;
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void *dst = out ? sgdata : buf;
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memcpy(dst, src, nbytes);
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}
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void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
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{
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walk->sg = sg;
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BUG_ON(!sg->length);
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walk->offset = sg->offset;
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}
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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,
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unsigned int more)
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{
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if (out) {
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struct page *page;
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page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
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if (!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;
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walk->offset &= PAGE_MASK;
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if (walk->offset >= walk->sg->offset + walk->sg->length)
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scatterwalk_start(walk, scatterwalk_sg_next(walk->sg));
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}
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}
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void scatterwalk_done(struct scatter_walk *walk, int out, int more)
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{
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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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}
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EXPORT_SYMBOL_GPL(scatterwalk_done);
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void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
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size_t nbytes, int out)
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{
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for (;;) {
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unsigned int len_this_page = scatterwalk_pagelen(walk);
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u8 *vaddr;
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if (len_this_page > nbytes)
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len_this_page = nbytes;
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vaddr = scatterwalk_map(walk);
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memcpy_dir(buf, vaddr, len_this_page, out);
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scatterwalk_unmap(vaddr);
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scatterwalk_advance(walk, len_this_page);
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if (nbytes == len_this_page)
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break;
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buf += len_this_page;
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nbytes -= len_this_page;
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scatterwalk_pagedone(walk, out, 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,
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unsigned int start, unsigned int nbytes, int out)
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{
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struct scatter_walk walk;
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unsigned int offset = 0;
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if (!nbytes)
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return;
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for (;;) {
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scatterwalk_start(&walk, sg);
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if (start < offset + sg->length)
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break;
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offset += sg->length;
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sg = scatterwalk_sg_next(sg);
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}
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scatterwalk_advance(&walk, start - offset);
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scatterwalk_copychunks(buf, &walk, nbytes, out);
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scatterwalk_done(&walk, out, 0);
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}
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EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
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