6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7 * 2002 Adam J. Richter <adam@yggdrasil.com>
8 * 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License as published by the Free
12 * Software Foundation; either version 2 of the License, or (at your option)
17 #include <crypto/scatterwalk.h>
18 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/pagemap.h>
22 #include <linux/highmem.h>
23 #include <linux/scatterlist.h>
25 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
27 void *src = out ? buf : sgdata;
28 void *dst = out ? sgdata : buf;
30 memcpy(dst, src, nbytes);
33 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
39 walk->offset = sg->offset;
41 EXPORT_SYMBOL_GPL(scatterwalk_start);
43 void *scatterwalk_map(struct scatter_walk *walk)
45 return kmap_atomic(scatterwalk_page(walk)) +
46 offset_in_page(walk->offset);
48 EXPORT_SYMBOL_GPL(scatterwalk_map);
50 static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
56 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
58 flush_dcache_page(page);
62 walk->offset += PAGE_SIZE - 1;
63 walk->offset &= PAGE_MASK;
64 if (walk->offset >= walk->sg->offset + walk->sg->length)
65 scatterwalk_start(walk, sg_next(walk->sg));
69 void scatterwalk_done(struct scatter_walk *walk, int out, int more)
71 if (!(scatterwalk_pagelen(walk) & (PAGE_SIZE - 1)) || !more)
72 scatterwalk_pagedone(walk, out, more);
74 EXPORT_SYMBOL_GPL(scatterwalk_done);
76 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
77 size_t nbytes, int out)
80 unsigned int len_this_page = scatterwalk_pagelen(walk);
83 if (len_this_page > nbytes)
84 len_this_page = nbytes;
86 vaddr = scatterwalk_map(walk);
87 memcpy_dir(buf, vaddr, len_this_page, out);
88 scatterwalk_unmap(vaddr);
90 scatterwalk_advance(walk, len_this_page);
92 if (nbytes == len_this_page)
96 nbytes -= len_this_page;
98 scatterwalk_pagedone(walk, out, 1);
101 EXPORT_SYMBOL_GPL(scatterwalk_copychunks);
103 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
104 unsigned int start, unsigned int nbytes, int out)
106 struct scatter_walk walk;
107 unsigned int offset = 0;
113 scatterwalk_start(&walk, sg);
115 if (start < offset + sg->length)
118 offset += sg->length;
122 scatterwalk_advance(&walk, start - offset);
123 scatterwalk_copychunks(buf, &walk, nbytes, out);
124 scatterwalk_done(&walk, out, 0);
126 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
128 int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes)
130 int offset = 0, n = 0;
132 /* num_bytes is too small */
133 if (num_bytes < sg->length)
137 offset += sg->length;
141 /* num_bytes is too large */
142 if (unlikely(!sg && (num_bytes < offset)))
144 } while (sg && (num_bytes > offset));
148 EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen);