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crypto/scatterwalk.c
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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> |
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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; void *dst = out ? sgdata : buf; memcpy(dst, src, nbytes); |
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} void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg) { |
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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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EXPORT_SYMBOL_GPL(scatterwalk_start); |
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void *scatterwalk_map(struct scatter_walk *walk, int out) |
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{ |
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return crypto_kmap(scatterwalk_page(walk), out) + 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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if (!PageSlab(page)) 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, scatterwalk_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; vaddr = scatterwalk_map(walk, out); memcpy_dir(buf, vaddr, len_this_page, out); scatterwalk_unmap(vaddr, out); |
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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); |
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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; unsigned int offset = 0; |
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if (!nbytes) return; |
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for (;;) { scatterwalk_start(&walk, sg); if (start < offset + sg->length) break; offset += sg->length; |
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sg = scatterwalk_sg_next(sg); |
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} scatterwalk_advance(&walk, start - offset); scatterwalk_copychunks(buf, &walk, nbytes, out); scatterwalk_done(&walk, out, 0); } EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); |