1 files changed, 148 insertions, 0 deletions
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
new file mode 100644
index 000000000..3bd749c7b
--- /dev/null
+++ b/crypto/scatterwalk.c
@@ -0,0 +1,148 @@
+/*
+ * 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)
+{
+	return kmap_atomic(scatterwalk_page(walk)) +
+	       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, 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);
+		memcpy_dir(buf, vaddr, len_this_page, out);
+		scatterwalk_unmap(vaddr);
+
+		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 = 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);
+
+int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes)
+{
+	int offset = 0, n = 0;
+
+	/* num_bytes is too small */
+	if (num_bytes < sg->length)
+		return -1;
+
+	do {
+		offset += sg->length;
+		n++;
+		sg = sg_next(sg);
+
+		/* num_bytes is too large */
+		if (unlikely(!sg && (num_bytes < offset)))
+			return -1;
+	} while (sg && (num_bytes > offset));
+
+	return n;
+}
+EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen);