crypto: Fix memcpy_sglist()

index 1d010e2a1b1a..af6c17bfcadb 100644
@@ -99,30 +99,107 @@ void memcpy_to_sglist(struct scatterlist *sg, unsigned int start,
 	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 overlap.  Hence this really acts like memmove(), not
+ * memcpy().
+ *
+ * Context: Any context
+ */
 void memcpy_sglist(struct scatterlist *dst, struct scatterlist *src,
 		   unsigned int nbytes)
 {
-	struct skcipher_walk walk = {};
+	unsigned int src_offset, dst_offset;
 
-	if (unlikely(nbytes == 0)) /* in case sg == NULL */
+	if (unlikely(nbytes == 0)) /* in case src and/or dst is NULL */
 		return;
 
-	walk.total = nbytes;
-
-	scatterwalk_start(&walk.in, src);
-	scatterwalk_start(&walk.out, dst);
+	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.
+				 * No need for memmove(), as the pages differ.
+				 */
+				src_virt = kmap_local_page(src_page);
+				dst_virt = kmap_local_page(dst_page);
+				memcpy(dst_virt + dst_oip, src_virt + src_oip,
+				       len);
+				flush_dcache_page(dst_page);
+				kunmap_local(dst_virt);
+				kunmap_local(src_virt);
+			} else if (src_oip != dst_oip) {
+				/* Copy between different parts of same page */
+				dst_virt = kmap_local_page(dst_page);
+				memmove(dst_virt + dst_oip, dst_virt + src_oip,
+					len);
+				flush_dcache_page(dst_page);
+				kunmap_local(dst_virt);
+			} /* Exact overlap.  No action needed. */
+		} else {
+			/*
+			 * !HIGHMEM: no mapping needed.  Just work in the linear
+			 * buffer of each sg entry.
+			 */
+			src_virt = page_address(src_page) + src_offset;
+			dst_virt = page_address(dst_page) + dst_offset;
+			if (src_virt != dst_virt) {
+				memmove(dst_virt, src_virt, len);
+				if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE)
+					__scatterwalk_flush_dcache_pages(
+						dst_page, dst_offset, len);
+			}
+		}
+		nbytes -= len;
+		if (nbytes == 0) /* No more to copy? */
+			break;
 
-	skcipher_walk_first(&walk, true);
-	do {
-		if (walk.src.virt.addr != walk.dst.virt.addr)
-			memcpy(walk.dst.virt.addr, walk.src.virt.addr,
-			       walk.nbytes);
-		skcipher_walk_done(&walk, 0);
-	} while (walk.nbytes);
+		/*
+		 * 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,

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index af6c17bfcadb..bf120edfa3ac 100644
@@ -8,29 +8,14 @@
  *               2002 Adam J. Richter <[email protected]>
  *               2004 Jean-Luc Cooke <[email protected]>
  */
 
 #include <crypto/scatterwalk.h>
-#include <linux/crypto.h>
-#include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/scatterlist.h>
-#include <linux/slab.h>
-
-enum {
-	SKCIPHER_WALK_SLOW = 1 << 0,
-	SKCIPHER_WALK_COPY = 1 << 1,
-	SKCIPHER_WALK_DIFF = 1 << 2,
-	SKCIPHER_WALK_SLEEP = 1 << 3,
-};
-
-static inline gfp_t skcipher_walk_gfp(struct skcipher_walk *walk)
-{
-	return walk->flags & SKCIPHER_WALK_SLEEP ? GFP_KERNEL : GFP_ATOMIC;
-}
 
 void scatterwalk_skip(struct scatter_walk *walk, unsigned int nbytes)
 {
 	struct scatterlist *sg = walk->sg;
 

@@ -221,238 +206,5 @@ struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2],
 	scatterwalk_crypto_chain(dst, sg_next(src), 2);
 
 	return dst;
 }
 EXPORT_SYMBOL_GPL(scatterwalk_ffwd);
-
-static int skcipher_next_slow(struct skcipher_walk *walk, unsigned int bsize)
-{
-	unsigned alignmask = walk->alignmask;
-	unsigned n;
-	void *buffer;
-
-	if (!walk->buffer)
-		walk->buffer = walk->page;
-	buffer = walk->buffer;
-	if (!buffer) {
-		/* Min size for a buffer of bsize bytes aligned to alignmask */
-		n = bsize + (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
-
-		buffer = kzalloc(n, skcipher_walk_gfp(walk));
-		if (!buffer)
-			return skcipher_walk_done(walk, -ENOMEM);
-		walk->buffer = buffer;
-	}
-
-	buffer = PTR_ALIGN(buffer, alignmask + 1);
-	memcpy_from_scatterwalk(buffer, &walk->in, bsize);
-	walk->out.__addr = buffer;
-	walk->in.__addr = walk->out.addr;
-
-	walk->nbytes = bsize;
-	walk->flags |= SKCIPHER_WALK_SLOW;
-
-	return 0;
-}
-
-static int skcipher_next_copy(struct skcipher_walk *walk)
-{
-	void *tmp = walk->page;
-
-	scatterwalk_map(&walk->in);
-	memcpy(tmp, walk->in.addr, walk->nbytes);
-	scatterwalk_unmap(&walk->in);
-	/*
-	 * walk->in is advanced later when the number of bytes actually
-	 * processed (which might be less than walk->nbytes) is known.
-	 */
-
-	walk->in.__addr = tmp;
-	walk->out.__addr = tmp;
-	return 0;
-}
-
-static int skcipher_next_fast(struct skcipher_walk *walk)
-{
-	unsigned long diff;
-
-	diff = offset_in_page(walk->in.offset) -
-	       offset_in_page(walk->out.offset);
-	diff |= (u8 *)(sg_page(walk->in.sg) + (walk->in.offset >> PAGE_SHIFT)) -
-		(u8 *)(sg_page(walk->out.sg) + (walk->out.offset >> PAGE_SHIFT));
-
-	scatterwalk_map(&walk->out);
-	walk->in.__addr = walk->out.__addr;
-
-	if (diff) {
-		walk->flags |= SKCIPHER_WALK_DIFF;
-		scatterwalk_map(&walk->in);
-	}
-
-	return 0;
-}
-
-static int skcipher_walk_next(struct skcipher_walk *walk)
-{
-	unsigned int bsize;
-	unsigned int n;
-
-	n = walk->total;
-	bsize = min(walk->stride, max(n, walk->blocksize));
-	n = scatterwalk_clamp(&walk->in, n);
-	n = scatterwalk_clamp(&walk->out, n);
-
-	if (unlikely(n < bsize)) {
-		if (unlikely(walk->total < walk->blocksize))
-			return skcipher_walk_done(walk, -EINVAL);
-
-slow_path:
-		return skcipher_next_slow(walk, bsize);
-	}
-	walk->nbytes = n;
-
-	if (unlikely((walk->in.offset | walk->out.offset) & walk->alignmask)) {
-		if (!walk->page) {
-			gfp_t gfp = skcipher_walk_gfp(walk);
-
-			walk->page = (void *)__get_free_page(gfp);
-			if (!walk->page)
-				goto slow_path;
-		}
-		walk->flags |= SKCIPHER_WALK_COPY;
-		return skcipher_next_copy(walk);
-	}
-
-	return skcipher_next_fast(walk);
-}
-
-static int skcipher_copy_iv(struct skcipher_walk *walk)
-{
-	unsigned alignmask = walk->alignmask;
-	unsigned ivsize = walk->ivsize;
-	unsigned aligned_stride = ALIGN(walk->stride, alignmask + 1);
-	unsigned size;
-	u8 *iv;
-
-	/* Min size for a buffer of stride + ivsize, aligned to alignmask */
-	size = aligned_stride + ivsize +
-	       (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
-
-	walk->buffer = kmalloc(size, skcipher_walk_gfp(walk));
-	if (!walk->buffer)
-		return -ENOMEM;
-
-	iv = PTR_ALIGN(walk->buffer, alignmask + 1) + aligned_stride;
-
-	walk->iv = memcpy(iv, walk->iv, walk->ivsize);
-	return 0;
-}
-
-int skcipher_walk_first(struct skcipher_walk *walk, bool atomic)
-{
-	if (WARN_ON_ONCE(in_hardirq()))
-		return -EDEADLK;
-
-	walk->flags = atomic ? 0 : SKCIPHER_WALK_SLEEP;
-
-	walk->buffer = NULL;
-	if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
-		int err = skcipher_copy_iv(walk);
-		if (err)
-			return err;
-	}
-
-	walk->page = NULL;
-
-	return skcipher_walk_next(walk);
-}
-EXPORT_SYMBOL_GPL(skcipher_walk_first);
-
-/**
- * skcipher_walk_done() - finish one step of a skcipher_walk
- * @walk: the skcipher_walk
- * @res: number of bytes *not* processed (>= 0) from walk->nbytes,
- *	 or a -errno value to terminate the walk due to an error
- *
- * This function cleans up after one step of walking through the source and
- * destination scatterlists, and advances to the next step if applicable.
- * walk->nbytes is set to the number of bytes available in the next step,
- * walk->total is set to the new total number of bytes remaining, and
- * walk->{src,dst}.virt.addr is set to the next pair of data pointers.  If there
- * is no more data, or if an error occurred (i.e. -errno return), then
- * walk->nbytes and walk->total are set to 0 and all resources owned by the
- * skcipher_walk are freed.
- *
- * Return: 0 or a -errno value.  If @res was a -errno value then it will be
- *	   returned, but other errors may occur too.
- */
-int skcipher_walk_done(struct skcipher_walk *walk, int res)
-{
-	unsigned int n = walk->nbytes; /* num bytes processed this step */
-	unsigned int total = 0; /* new total remaining */
-
-	if (!n)
-		goto finish;
-
-	if (likely(res >= 0)) {
-		n -= res; /* subtract num bytes *not* processed */
-		total = walk->total - n;
-	}
-
-	if (likely(!(walk->flags & (SKCIPHER_WALK_SLOW |
-				    SKCIPHER_WALK_COPY |
-				    SKCIPHER_WALK_DIFF)))) {
-		scatterwalk_advance(&walk->in, n);
-	} else if (walk->flags & SKCIPHER_WALK_DIFF) {
-		scatterwalk_done_src(&walk->in, n);
-	} else if (walk->flags & SKCIPHER_WALK_COPY) {
-		scatterwalk_advance(&walk->in, n);
-		scatterwalk_map(&walk->out);
-		memcpy(walk->out.addr, walk->page, n);
-	} else { /* SKCIPHER_WALK_SLOW */
-		if (res > 0) {
-			/*
-			 * Didn't process all bytes.  Either the algorithm is
-			 * broken, or this was the last step and it turned out
-			 * the message wasn't evenly divisible into blocks but
-			 * the algorithm requires it.
-			 */
-			res = -EINVAL;
-			total = 0;
-		} else
-			memcpy_to_scatterwalk(&walk->out, walk->out.addr, n);
-		goto dst_done;
-	}
-
-	scatterwalk_done_dst(&walk->out, n);
-dst_done:
-
-	if (res > 0)
-		res = 0;
-
-	walk->total = total;
-	walk->nbytes = 0;
-
-	if (total) {
-		if (walk->flags & SKCIPHER_WALK_SLEEP)
-			cond_resched();
-		walk->flags &= ~(SKCIPHER_WALK_SLOW | SKCIPHER_WALK_COPY |
-				 SKCIPHER_WALK_DIFF);
-		return skcipher_walk_next(walk);
-	}
-
-finish:
-	/* Short-circuit for the common/fast path. */
-	if (!((unsigned long)walk->buffer | (unsigned long)walk->page))
-		goto out;
-
-	if (walk->iv != walk->oiv)
-		memcpy(walk->oiv, walk->iv, walk->ivsize);
-	if (walk->buffer != walk->page)
-		kfree(walk->buffer);
-	if (walk->page)
-		free_page((unsigned long)walk->page);
-
-out:
-	return res;
-}
-EXPORT_SYMBOL_GPL(skcipher_walk_done);

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index fc4574940636..05deea9dac5e 100644
@@ -105,10 +105,22 @@ struct crypto_queue {
 
 	unsigned int qlen;
 	unsigned int max_qlen;
 };
 
+struct scatter_walk {
+	/* Must be the first member, see struct skcipher_walk. */
+	union {
+		void *const addr;
+
+		/* Private API field, do not touch. */
+		union crypto_no_such_thing *__addr;
+	};
+	struct scatterlist *sg;
+	unsigned int offset;
+};
+
 struct crypto_attr_alg {
 	char name[CRYPTO_MAX_ALG_NAME];
 };
 
 struct crypto_attr_type {

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