// SPDX-License-Identifier: GPL-2.0-or-later/* * 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> */ #include <crypto/scatterwalk.h>#include <linux/kernel.h>#include <linux/mm.h>#include <linux/module.h>#include <linux/scatterlist.h> void scatterwalk_skip(struct scatter_walk *walk, unsigned int nbytes){	struct scatterlist *sg = walk->sg; 	nbytes += walk->offset - sg->offset; 	while (nbytes > sg->length) {		nbytes -= sg->length;		sg = sg_next(sg);	}	walk->sg = sg;	walk->offset = sg->offset + nbytes;}EXPORT_SYMBOL_GPL(scatterwalk_skip); inline void memcpy_from_scatterwalk(void *buf, struct scatter_walk *walk,				    unsigned int nbytes){	do {		unsigned int to_copy; 		to_copy = scatterwalk_next(walk, nbytes);		memcpy(buf, walk->addr, to_copy);		scatterwalk_done_src(walk, to_copy);		buf += to_copy;		nbytes -= to_copy;	} while (nbytes);}EXPORT_SYMBOL_GPL(memcpy_from_scatterwalk); inline void memcpy_to_scatterwalk(struct scatter_walk *walk, const void *buf,				  unsigned int nbytes){	do {		unsigned int to_copy; 		to_copy = scatterwalk_next(walk, nbytes);		memcpy(walk->addr, buf, to_copy);		scatterwalk_done_dst(walk, to_copy);		buf += to_copy;		nbytes -= to_copy;	} while (nbytes);}EXPORT_SYMBOL_GPL(memcpy_to_scatterwalk); void memcpy_from_sglist(void *buf, struct scatterlist *sg,			unsigned int start, unsigned int nbytes){	struct scatter_walk walk; 	if (unlikely(nbytes == 0)) /* in case sg == NULL */		return; 	scatterwalk_start_at_pos(&walk, sg, start);	memcpy_from_scatterwalk(buf, &walk, nbytes);}EXPORT_SYMBOL_GPL(memcpy_from_sglist); void memcpy_to_sglist(struct scatterlist *sg, unsigned int start,		      const void *buf, unsigned int nbytes){	struct scatter_walk walk; 	if (unlikely(nbytes == 0)) /* in case sg == NULL */		return; 	scatterwalk_start_at_pos(&walk, sg, start);	memcpy_to_scatterwalk(&walk, buf, nbytes);}EXPORT_SYMBOL_GPL(memcpy_to_sglist); /** * memcpy_sglist() - Copy data from one scatterlist to another * @dst: The destination scatterlist.  Can be NULL if @nbytes == 0. * @src: The source scatterlist.  Can be NULL if @nbytes == 0. * @nbytes: Number of bytes to copy * * The scatterlists can describe exactly the same memory, in which case this * function is a no-op.  No other overlaps are supported. * * Context: Any context */void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src,		   unsigned int nbytes){	unsigned int src_offset, dst_offset; 	if (unlikely(nbytes == 0)) /* in case src and/or dst is NULL */		return; 	src_offset = src->offset;	dst_offset = dst->offset;	for (;;) {		/* Compute the length to copy this step. */		unsigned int len = min3(src->offset + src->length - src_offset,					dst->offset + dst->length - dst_offset,					nbytes);		struct page *src_page = sg_page(src);		struct page *dst_page = sg_page(dst);		const void *src_virt;		void *dst_virt; 		if (IS_ENABLED(CONFIG_HIGHMEM)) {			/* HIGHMEM: we may have to actually map the pages. */			const unsigned int src_oip = offset_in_page(src_offset);			const unsigned int dst_oip = offset_in_page(dst_offset);			const unsigned int limit = PAGE_SIZE; 			/* Further limit len to not cross a page boundary. */			len = min3(len, limit - src_oip, limit - dst_oip); 			/* Compute the source and destination pages. */			src_page += src_offset / PAGE_SIZE;			dst_page += dst_offset / PAGE_SIZE; 			if (src_page != dst_page) {				/* Copy between different pages. */				memcpy_page(dst_page, dst_oip,					    src_page, src_oip, len);				flush_dcache_page(dst_page);			} else if (src_oip != dst_oip) {				/* Copy between different parts of same page. */				dst_virt = kmap_local_page(dst_page);				memcpy(dst_virt + dst_oip, dst_virt + src_oip,				       len);				kunmap_local(dst_virt);				flush_dcache_page(dst_page);			} /* Else, it's the same memory.  No action needed. */		} else {			/*			 * !HIGHMEM: no mapping needed.  Just work in the linear			 * buffer of each sg entry.  Note that we can cross page			 * boundaries, as they are not significant in this case.			 */			src_virt = page_address(src_page) + src_offset;			dst_virt = page_address(dst_page) + dst_offset;			if (src_virt != dst_virt) {				memcpy(dst_virt, src_virt, len);				if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE)					__scatterwalk_flush_dcache_pages(						dst_page, dst_offset, len);			} /* Else, it's the same memory.  No action needed. */		}		nbytes -= len;		if (nbytes == 0) /* No more to copy? */			break; 		/*		 * There's more to copy.  Advance the offsets by the length		 * copied this step, and advance the sg entries as needed.		 */		src_offset += len;		if (src_offset >= src->offset + src->length) {			src = sg_next(src);			src_offset = src->offset;		}		dst_offset += len;		if (dst_offset >= dst->offset + dst->length) {			dst = sg_next(dst);			dst_offset = dst->offset;		}	}}EXPORT_SYMBOL_GPL(memcpy_sglist); struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],				     struct scatterlist *src,				     unsigned int len){	for (;;) {		if (!len)			return src; 		if (src->length > len)			break; 		len -= src->length;		src = sg_next(src);	} 	sg_init_table(dst, 2);	sg_set_page(dst, sg_page(src), src->length - len, src->offset + len);	scatterwalk_crypto_chain(dst, sg_next(src), 2); 	return dst;}EXPORT_SYMBOL_GPL(scatterwalk_ffwd);