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https://github.com/torvalds/linux
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fc42bcba97
This patch adds the scatterwalk_ffwd helper which can create an SG list that starts in the middle of an existing SG list. The new list may either be part of the existing list or be a chain that latches onto part of the existing list. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
109 lines
3.1 KiB
C
109 lines
3.1 KiB
C
/*
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* Cryptographic scatter and gather helpers.
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*
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* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
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* Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
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* Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
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* Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
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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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#ifndef _CRYPTO_SCATTERWALK_H
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#define _CRYPTO_SCATTERWALK_H
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#include <asm/kmap_types.h>
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#include <crypto/algapi.h>
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#include <linux/hardirq.h>
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#include <linux/highmem.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/scatterlist.h>
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#include <linux/sched.h>
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static inline void scatterwalk_sg_chain(struct scatterlist *sg1, int num,
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struct scatterlist *sg2)
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{
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sg_set_page(&sg1[num - 1], (void *)sg2, 0, 0);
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sg1[num - 1].page_link &= ~0x02;
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sg1[num - 1].page_link |= 0x01;
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}
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static inline void scatterwalk_crypto_chain(struct scatterlist *head,
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struct scatterlist *sg,
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int chain, int num)
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{
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if (chain) {
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head->length += sg->length;
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sg = sg_next(sg);
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}
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if (sg)
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scatterwalk_sg_chain(head, num, sg);
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else
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sg_mark_end(head);
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}
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static inline unsigned long scatterwalk_samebuf(struct scatter_walk *walk_in,
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struct scatter_walk *walk_out)
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{
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return !(((sg_page(walk_in->sg) - sg_page(walk_out->sg)) << PAGE_SHIFT) +
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(int)(walk_in->offset - walk_out->offset));
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}
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static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
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{
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unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
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unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
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return len_this_page > len ? len : len_this_page;
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}
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static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
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unsigned int nbytes)
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{
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unsigned int len_this_page = scatterwalk_pagelen(walk);
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return nbytes > len_this_page ? len_this_page : nbytes;
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}
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static inline void scatterwalk_advance(struct scatter_walk *walk,
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unsigned int nbytes)
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{
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walk->offset += nbytes;
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}
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static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
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unsigned int alignmask)
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{
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return !(walk->offset & alignmask);
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}
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static inline struct page *scatterwalk_page(struct scatter_walk *walk)
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{
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return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
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}
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static inline void scatterwalk_unmap(void *vaddr)
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{
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kunmap_atomic(vaddr);
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}
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void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg);
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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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void *scatterwalk_map(struct scatter_walk *walk);
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void scatterwalk_done(struct scatter_walk *walk, int out, int more);
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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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int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes);
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struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
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struct scatterlist *src,
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unsigned int len);
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#endif /* _CRYPTO_SCATTERWALK_H */
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