1 files changed, 105 insertions, 0 deletions
diff --git a/include/crypto/scatterwalk.h b/include/crypto/scatterwalk.h
new file mode 100644
index 000000000..ccdb05f68
--- /dev/null
+++ b/include/crypto/scatterwalk.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Cryptographic scatter and gather helpers.
+ *
+ * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
+ * Copyright (c) 2002 Adam J. Richter <adam@yggdrasil.com>
+ * Copyright (c) 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
+ * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#ifndef _CRYPTO_SCATTERWALK_H
+#define _CRYPTO_SCATTERWALK_H
+
+#include <crypto/algapi.h>
+
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/scatterlist.h>
+
+static inline void scatterwalk_crypto_chain(struct scatterlist *head,
+					    struct scatterlist *sg, int num)
+{
+	if (sg)
+		sg_chain(head, num, sg);
+	else
+		sg_mark_end(head);
+}
+
+static inline unsigned int scatterwalk_pagelen(struct scatter_walk *walk)
+{
+	unsigned int len = walk->sg->offset + walk->sg->length - walk->offset;
+	unsigned int len_this_page = offset_in_page(~walk->offset) + 1;
+	return len_this_page > len ? len : len_this_page;
+}
+
+static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
+					     unsigned int nbytes)
+{
+	unsigned int len_this_page = scatterwalk_pagelen(walk);
+	return nbytes > len_this_page ? len_this_page : nbytes;
+}
+
+static inline void scatterwalk_advance(struct scatter_walk *walk,
+				       unsigned int nbytes)
+{
+	walk->offset += nbytes;
+}
+
+static inline struct page *scatterwalk_page(struct scatter_walk *walk)
+{
+	return sg_page(walk->sg) + (walk->offset >> PAGE_SHIFT);
+}
+
+static inline void scatterwalk_unmap(void *vaddr)
+{
+	kunmap_atomic(vaddr);
+}
+
+static inline void scatterwalk_start(struct scatter_walk *walk,
+				     struct scatterlist *sg)
+{
+	walk->sg = sg;
+	walk->offset = sg->offset;
+}
+
+static inline void *scatterwalk_map(struct scatter_walk *walk)
+{
+	return kmap_atomic(scatterwalk_page(walk)) +
+	       offset_in_page(walk->offset);
+}
+
+static inline 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);
+		flush_dcache_page(page);
+	}
+
+	if (more && walk->offset >= walk->sg->offset + walk->sg->length)
+		scatterwalk_start(walk, sg_next(walk->sg));
+}
+
+static inline void scatterwalk_done(struct scatter_walk *walk, int out,
+				    int more)
+{
+	if (!more || walk->offset >= walk->sg->offset + walk->sg->length ||
+	    !(walk->offset & (PAGE_SIZE - 1)))
+		scatterwalk_pagedone(walk, out, more);
+}
+
+void scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
+			    size_t nbytes, int out);
+void *scatterwalk_map(struct scatter_walk *walk);
+
+void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
+			      unsigned int start, unsigned int nbytes, int out);
+
+struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
+				     struct scatterlist *src,
+				     unsigned int len);
+
+#endif  /* _CRYPTO_SCATTERWALK_H */