diff options
Diffstat (limited to 'crypto/scatterwalk.c')
-rw-r--r-- | crypto/scatterwalk.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c new file mode 100644 index 00000000..41e529af --- /dev/null +++ b/crypto/scatterwalk.c @@ -0,0 +1,126 @@ +/* + * 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. + * + */ + +#include <crypto/scatterwalk.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/pagemap.h> +#include <linux/highmem.h> +#include <linux/scatterlist.h> + +static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) +{ + void *src = out ? buf : sgdata; + void *dst = out ? sgdata : buf; + + memcpy(dst, src, nbytes); +} + +void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg) +{ + walk->sg = sg; + + BUG_ON(!sg->length); + + walk->offset = sg->offset; +} +EXPORT_SYMBOL_GPL(scatterwalk_start); + +void *scatterwalk_map(struct scatter_walk *walk, int out) +{ + return crypto_kmap(scatterwalk_page(walk), out) + + offset_in_page(walk->offset); +} +EXPORT_SYMBOL_GPL(scatterwalk_map); + +static void scatterwalk_pagedone(struct scatter_walk *walk, int out, + unsigned int more) +{ + if (out) { + struct page *page; + + page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); + if (!PageSlab(page)) + flush_dcache_page(page); + } + + if (more) { + walk->offset += PAGE_SIZE - 1; + walk->offset &= PAGE_MASK; + if (walk->offset >= walk->sg->offset + walk->sg->length) + scatterwalk_start(walk, scatterwalk_sg_next(walk->sg)); + } +} + +void scatterwalk_done(struct scatter_walk *walk, int out, int more) +{ + if (!(scatterwalk_pagelen(walk) & (PAGE_SIZE - 1)) || !more) + scatterwalk_pagedone(walk, out, more); +} +EXPORT_SYMBOL_GPL(scatterwalk_done); + +void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, + size_t nbytes, int out) +{ + 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); + + scatterwalk_advance(walk, len_this_page); + + if (nbytes == len_this_page) + break; + + buf += len_this_page; + nbytes -= len_this_page; + + scatterwalk_pagedone(walk, out, 1); + } +} +EXPORT_SYMBOL_GPL(scatterwalk_copychunks); + +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; + + if (!nbytes) + return; + + for (;;) { + scatterwalk_start(&walk, sg); + + if (start < offset + sg->length) + break; + + offset += sg->length; + sg = scatterwalk_sg_next(sg); + } + + scatterwalk_advance(&walk, start - offset); + scatterwalk_copychunks(buf, &walk, nbytes, out); + scatterwalk_done(&walk, out, 0); +} +EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); |