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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Cryptographic API.4 *5 * Cipher operations.6 *7 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>8 * 2002 Adam J. Richter <adam@yggdrasil.com>9 * 2004 Jean-Luc Cooke <jlcooke@certainkey.com>10 */11 12#include <crypto/scatterwalk.h>13#include <linux/kernel.h>14#include <linux/mm.h>15#include <linux/module.h>16#include <linux/scatterlist.h>17 18static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)19{20 void *src = out ? buf : sgdata;21 void *dst = out ? sgdata : buf;22 23 memcpy(dst, src, nbytes);24}25 26void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,27 size_t nbytes, int out)28{29 for (;;) {30 unsigned int len_this_page = scatterwalk_pagelen(walk);31 u8 *vaddr;32 33 if (len_this_page > nbytes)34 len_this_page = nbytes;35 36 if (out != 2) {37 vaddr = scatterwalk_map(walk);38 memcpy_dir(buf, vaddr, len_this_page, out);39 scatterwalk_unmap(vaddr);40 }41 42 scatterwalk_advance(walk, len_this_page);43 44 if (nbytes == len_this_page)45 break;46 47 buf += len_this_page;48 nbytes -= len_this_page;49 50 scatterwalk_pagedone(walk, out & 1, 1);51 }52}53EXPORT_SYMBOL_GPL(scatterwalk_copychunks);54 55void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,56 unsigned int start, unsigned int nbytes, int out)57{58 struct scatter_walk walk;59 struct scatterlist tmp[2];60 61 if (!nbytes)62 return;63 64 sg = scatterwalk_ffwd(tmp, sg, start);65 66 scatterwalk_start(&walk, sg);67 scatterwalk_copychunks(buf, &walk, nbytes, out);68 scatterwalk_done(&walk, out, 0);69}70EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);71 72struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],73 struct scatterlist *src,74 unsigned int len)75{76 for (;;) {77 if (!len)78 return src;79 80 if (src->length > len)81 break;82 83 len -= src->length;84 src = sg_next(src);85 }86 87 sg_init_table(dst, 2);88 sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);89 scatterwalk_crypto_chain(dst, sg_next(src), 2);90 91 return dst;92}93EXPORT_SYMBOL_GPL(scatterwalk_ffwd);94