include/crypto/scatterwalk.h

0001 /* SPDX-License-Identifier: GPL-2.0-or-later */
0002 /*
0003  * Cryptographic scatter and gather helpers.
0004  *
0005  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
0006  * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
0007  * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
0008  * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
0009  */
0010
0011 #ifndef _CRYPTO_SCATTERWALK_H
0012 #define _CRYPTO_SCATTERWALK_H
0013
0014 #include <crypto/algapi.h>
0015
0016 #include <linux/highmem.h>
0017 #include <linux/mm.h>
0018 #include <linux/scatterlist.h>
0019
0020 static inline void scatterwalk_crypto_chain(struct scatterlist *head,
0021                         struct scatterlist *sg, int num)
0022 {
0023     if (sg)
0024         sg_chain(head, num, sg);
0025     else
0026         sg_mark_end(head);
0027 }
0028
0029 static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
0030 {
0031     unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
0032     unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
0033     return len_this_page > len ? len : len_this_page;
0034 }
0035
0036 static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
0037                          unsigned int nbytes)
0038 {
0039     unsigned int len_this_page = scatterwalk_pagelen(walk);
0040     return nbytes > len_this_page ? len_this_page : nbytes;
0041 }
0042
0043 static inline void scatterwalk_advance(struct scatter_walk *walk,
0044                        unsigned int nbytes)
0045 {
0046     walk->offset += nbytes;
0047 }
0048
0049 static inline unsigned int scatterwalk_aligned(struct scatter_walk *walk,
0050                            unsigned int alignmask)
0051 {
0052     return !(walk->offset & alignmask);
0053 }
0054
0055 static inline struct page *scatterwalk_page(struct scatter_walk *walk)
0056 {
0057     return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
0058 }
0059
0060 static inline void scatterwalk_unmap(void *vaddr)
0061 {
0062     kunmap_atomic(vaddr);
0063 }
0064
0065 static inline void scatterwalk_start(struct scatter_walk *walk,
0066                      struct scatterlist *sg)
0067 {
0068     walk->sg = sg;
0069     walk->offset = sg->offset;
0070 }
0071
0072 static inline void *scatterwalk_map(struct scatter_walk *walk)
0073 {
0074     return kmap_atomic(scatterwalk_page(walk)) +
0075            offset_in_page(walk->offset);
0076 }
0077
0078 static inline void scatterwalk_pagedone(struct scatter_walk *walk, int out,
0079                     unsigned int more)
0080 {
0081     if (out) {
0082         struct page *page;
0083
0084         page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
0085         flush_dcache_page(page);
0086     }
0087
0088     if (more && walk->offset >= walk->sg->offset + walk->sg->length)
0089         scatterwalk_start(walk, sg_next(walk->sg));
0090 }
0091
0092 static inline void scatterwalk_done(struct scatter_walk *walk, int out,
0093                     int more)
0094 {
0095     if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
0096         !(walk->offset & (PAGE_SIZE - 1)))
0097         scatterwalk_pagedone(walk, out, more);
0098 }
0099
0100 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
0101                 size_t nbytes, int out);
0102 void *scatterwalk_map(struct scatter_walk *walk);
0103
0104 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
0105                   unsigned int start, unsigned int nbytes, int out);
0106
0107 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
0108                      struct scatterlist *src,
0109                      unsigned int len);
0110
0111 #endif  /* _CRYPTO_SCATTERWALK_H */