1 files changed, 115 insertions, 0 deletions
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
new file mode 100644
index 000000000000..50c9461e8cc6
--- /dev/null
+++ b/crypto/scatterwalk.c
@@ -0,0 +1,115 @@
+/*
+ * 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 <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/highmem.h>
+#include <asm/bug.h>
+#include <asm/scatterlist.h>
+#include "internal.h"
+#include "scatterwalk.h"
+
+enum km_type crypto_km_types[] = {
+	KM_USER0,
+	KM_USER1,
+	KM_SOFTIRQ0,
+	KM_SOFTIRQ1,
+};
+
+static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
+{
+	if (out)
+		memcpy(sgdata, buf, nbytes);
+	else
+		memcpy(buf, sgdata, nbytes);
+}
+
+void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
+{
+	unsigned int rest_of_page;
+
+	walk->sg = sg;
+
+	walk->page = sg->page;
+	walk->len_this_segment = sg->length;
+
+	BUG_ON(!sg->length);
+
+	rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
+	walk->len_this_page = min(sg->length, rest_of_page);
+	walk->offset = sg->offset;
+}
+
+void scatterwalk_map(struct scatter_walk *walk, int out)
+{
+	walk->data = crypto_kmap(walk->page, out) + walk->offset;
+}
+
+static inline void scatterwalk_unmap(struct scatter_walk *walk, int out)
+{
+	/* walk->data may be pointing the first byte of the next page;
+	   however, we know we transfered at least one byte.  So,
+	   walk->data - 1 will be a virtual address in the mapped page. */
+	crypto_kunmap(walk->data - 1, out);
+}
+
+static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
+				 unsigned int more)
+{
+	if (out)
+		flush_dcache_page(walk->page);
+
+	if (more) {
+		walk->len_this_segment -= walk->len_this_page;
+
+		if (walk->len_this_segment) {
+			walk->page++;
+			walk->len_this_page = min(walk->len_this_segment,
+						  (unsigned)PAGE_CACHE_SIZE);
+			walk->offset = 0;
+		}
+		else
+			scatterwalk_start(walk, sg_next(walk->sg));
+	}
+}
+
+void scatterwalk_done(struct scatter_walk *walk, int out, int more)
+{
+	scatterwalk_unmap(walk, out);
+	if (walk->len_this_page == 0 || !more)
+		scatterwalk_pagedone(walk, out, more);
+}
+
+/*
+ * Do not call this unless the total length of all of the fragments
+ * has been verified as multiple of the block size.
+ */
+int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
+			   size_t nbytes, int out)
+{
+	do {
+		memcpy_dir(buf, walk->data, walk->len_this_page, out);
+		buf += walk->len_this_page;
+		nbytes -= walk->len_this_page;
+
+		scatterwalk_unmap(walk, out);
+		scatterwalk_pagedone(walk, out, 1);
+		scatterwalk_map(walk, out);
+	} while (nbytes > walk->len_this_page);
+
+	memcpy_dir(buf, walk->data, nbytes, out);
+	return nbytes;
+}