diff --git a/crypto/cipher.c b/crypto/cipher.c
index 69264497b48c..c4243345b154 100644
--- a/crypto/cipher.c
+++ b/crypto/cipher.c
@@ -4,6 +4,7 @@
  * Cipher operations.
  *
  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
+ * Copyright (c) 2005 Herbert Xu <herbert@gondor.apana.org.au>
  *
  * 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
@@ -22,9 +23,13 @@
 #include "internal.h"
 #include "scatterwalk.h"
 
-typedef void (cryptfn_t)(void *, u8 *, const u8 *);
-typedef void (procfn_t)(struct crypto_tfm *, u8 *,
-                        u8*, cryptfn_t, void *);
+struct cipher_desc {
+	struct crypto_tfm *tfm;
+	void (*crfn)(void *ctx, u8 *dst, const u8 *src);
+	unsigned int (*prfn)(const struct cipher_desc *desc, u8 *dst,
+			     const u8 *src, unsigned int nbytes);
+	void *info;
+};
 
 static inline void xor_64(u8 *a, const u8 *b)
 {
@@ -39,63 +44,57 @@ static inline void xor_128(u8 *a, const u8 *b)
 	((u32 *)a)[2] ^= ((u32 *)b)[2];
 	((u32 *)a)[3] ^= ((u32 *)b)[3];
 }
- 
-static inline void *prepare_src(struct scatter_walk *walk, int bsize,
-				void *tmp, int in_place)
-{
-	void *src = walk->data;
-	int n = bsize;
 
-	if (unlikely(scatterwalk_across_pages(walk, bsize))) {
-		src = tmp;
-		n = scatterwalk_copychunks(src, walk, bsize, 0);
-	}
-	scatterwalk_advance(walk, n);
-	return src;
+static unsigned int crypt_slow(const struct cipher_desc *desc,
+			       struct scatter_walk *in,
+			       struct scatter_walk *out, unsigned int bsize)
+{
+	u8 src[bsize];
+	u8 dst[bsize];
+	unsigned int n;
+
+	n = scatterwalk_copychunks(src, in, bsize, 0);
+	scatterwalk_advance(in, n);
+
+	desc->prfn(desc, dst, src, bsize);
+
+	n = scatterwalk_copychunks(dst, out, bsize, 1);
+	scatterwalk_advance(out, n);
+
+	return bsize;
 }
 
-static inline void *prepare_dst(struct scatter_walk *walk, int bsize,
-				void *tmp, int in_place)
+static inline unsigned int crypt_fast(const struct cipher_desc *desc,
+				      struct scatter_walk *in,
+				      struct scatter_walk *out,
+				      unsigned int nbytes)
 {
-	void *dst = walk->data;
+	u8 *src, *dst;
 
-	if (unlikely(scatterwalk_across_pages(walk, bsize)) || in_place)
-		dst = tmp;
-	return dst;
-}
+	src = in->data;
+	dst = scatterwalk_samebuf(in, out) ? src : out->data;
 
-static inline void complete_src(struct scatter_walk *walk, int bsize,
-				void *src, int in_place)
-{
-}
+	nbytes = desc->prfn(desc, dst, src, nbytes);
 
-static inline void complete_dst(struct scatter_walk *walk, int bsize,
-				void *dst, int in_place)
-{
-	int n = bsize;
+	scatterwalk_advance(in, nbytes);
+	scatterwalk_advance(out, nbytes);
 
-	if (unlikely(scatterwalk_across_pages(walk, bsize)))
-		n = scatterwalk_copychunks(dst, walk, bsize, 1);
-	else if (in_place)
-		memcpy(walk->data, dst, bsize);
-	scatterwalk_advance(walk, n);
+	return nbytes;
 }
 
 /* 
  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
  * multiple page boundaries by using temporary blocks.  In user context,
- * the kernel is given a chance to schedule us once per block.
+ * the kernel is given a chance to schedule us once per page.
  */
-static int crypt(struct crypto_tfm *tfm,
+static int crypt(const struct cipher_desc *desc,
 		 struct scatterlist *dst,
 		 struct scatterlist *src,
-                 unsigned int nbytes, cryptfn_t crfn,
-                 procfn_t prfn, void *info)
+		 unsigned int nbytes)
 {
 	struct scatter_walk walk_in, walk_out;
+	struct crypto_tfm *tfm = desc->tfm;
 	const unsigned int bsize = crypto_tfm_alg_blocksize(tfm);
-	u8 tmp_src[bsize];
-	u8 tmp_dst[bsize];
 
 	if (!nbytes)
 		return 0;
@@ -109,29 +108,20 @@ static int crypt(struct crypto_tfm *tfm,
 	scatterwalk_start(&walk_out, dst);
 
 	for(;;) {
-		u8 *src_p, *dst_p;
-		int in_place;
+		unsigned int n;
 
 		scatterwalk_map(&walk_in, 0);
 		scatterwalk_map(&walk_out, 1);
 
-		in_place = scatterwalk_samebuf(&walk_in, &walk_out);
+		n = scatterwalk_clamp(&walk_in, nbytes);
+		n = scatterwalk_clamp(&walk_out, n);
 
-		do {
-			src_p = prepare_src(&walk_in, bsize, tmp_src,
-					    in_place);
-			dst_p = prepare_dst(&walk_out, bsize, tmp_dst,
-					    in_place);
+		if (likely(n >= bsize))
+			n = crypt_fast(desc, &walk_in, &walk_out, n);
+		else
+			n = crypt_slow(desc, &walk_in, &walk_out, bsize);
 
-			prfn(tfm, dst_p, src_p, crfn, info);
-
-			complete_src(&walk_in, bsize, src_p, in_place);
-			complete_dst(&walk_out, bsize, dst_p, in_place);
-
-			nbytes -= bsize;
-		} while (nbytes &&
-			 !scatterwalk_across_pages(&walk_in, bsize) &&
-			 !scatterwalk_across_pages(&walk_out, bsize));
+		nbytes -= n;
 
 		scatterwalk_done(&walk_in, 0, nbytes);
 		scatterwalk_done(&walk_out, 1, nbytes);
@@ -143,30 +133,78 @@ static int crypt(struct crypto_tfm *tfm,
 	}
 }
 
-static void cbc_process_encrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
-				cryptfn_t fn, void *info)
+static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
+					u8 *dst, const u8 *src,
+					unsigned int nbytes)
 {
-	u8 *iv = info;
+	struct crypto_tfm *tfm = desc->tfm;
+	void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
+	int bsize = crypto_tfm_alg_blocksize(tfm);
 
-	tfm->crt_u.cipher.cit_xor_block(iv, src);
-	fn(crypto_tfm_ctx(tfm), dst, iv);
-	memcpy(iv, dst, crypto_tfm_alg_blocksize(tfm));
+	void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
+	u8 *iv = desc->info;
+	unsigned int done = 0;
+
+	do {
+		xor(iv, src);
+		fn(crypto_tfm_ctx(tfm), dst, iv);
+		memcpy(iv, dst, bsize);
+
+		src += bsize;
+		dst += bsize;
+	} while ((done += bsize) < nbytes);
+
+	return done;
 }
 
-static void cbc_process_decrypt(struct crypto_tfm *tfm, u8 *dst, u8 *src,
-				cryptfn_t fn, void *info)
+static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
+					u8 *dst, const u8 *src,
+					unsigned int nbytes)
 {
-	u8 *iv = info;
+	struct crypto_tfm *tfm = desc->tfm;
+	void (*xor)(u8 *, const u8 *) = tfm->crt_u.cipher.cit_xor_block;
+	int bsize = crypto_tfm_alg_blocksize(tfm);
 
-	fn(crypto_tfm_ctx(tfm), dst, src);
-	tfm->crt_u.cipher.cit_xor_block(dst, iv);
-	memcpy(iv, src, crypto_tfm_alg_blocksize(tfm));
+	u8 stack[src == dst ? bsize : 0];
+	u8 *buf = stack;
+	u8 **dst_p = src == dst ? &buf : &dst;
+
+	void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
+	u8 *iv = desc->info;
+	unsigned int done = 0;
+
+	do {
+		u8 *tmp_dst = *dst_p;
+
+		fn(crypto_tfm_ctx(tfm), tmp_dst, src);
+		xor(tmp_dst, iv);
+		memcpy(iv, src, bsize);
+		if (tmp_dst != dst)
+			memcpy(dst, tmp_dst, bsize);
+
+		src += bsize;
+		dst += bsize;
+	} while ((done += bsize) < nbytes);
+
+	return done;
 }
 
-static void ecb_process(struct crypto_tfm *tfm, u8 *dst, u8 *src,
-			cryptfn_t fn, void *info)
+static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
+				const u8 *src, unsigned int nbytes)
 {
-	fn(crypto_tfm_ctx(tfm), dst, src);
+	struct crypto_tfm *tfm = desc->tfm;
+	int bsize = crypto_tfm_alg_blocksize(tfm);
+	void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
+	unsigned int done = 0;
+
+	do {
+		fn(crypto_tfm_ctx(tfm), dst, src);
+
+		src += bsize;
+		dst += bsize;
+	} while ((done += bsize) < nbytes);
+
+	return done;
 }
 
 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
@@ -185,9 +223,13 @@ static int ecb_encrypt(struct crypto_tfm *tfm,
 		       struct scatterlist *dst,
                        struct scatterlist *src, unsigned int nbytes)
 {
-	return crypt(tfm, dst, src, nbytes,
-	             tfm->__crt_alg->cra_cipher.cia_encrypt,
-	             ecb_process, NULL);
+	struct cipher_desc desc;
+
+	desc.tfm = tfm;
+	desc.crfn = tfm->__crt_alg->cra_cipher.cia_encrypt;
+	desc.prfn = ecb_process;
+
+	return crypt(&desc, dst, src, nbytes);
 }
 
 static int ecb_decrypt(struct crypto_tfm *tfm,
@@ -195,9 +237,13 @@ static int ecb_decrypt(struct crypto_tfm *tfm,
                        struct scatterlist *src,
 		       unsigned int nbytes)
 {
-	return crypt(tfm, dst, src, nbytes,
-	             tfm->__crt_alg->cra_cipher.cia_decrypt,
-	             ecb_process, NULL);
+	struct cipher_desc desc;
+
+	desc.tfm = tfm;
+	desc.crfn = tfm->__crt_alg->cra_cipher.cia_decrypt;
+	desc.prfn = ecb_process;
+
+	return crypt(&desc, dst, src, nbytes);
 }
 
 static int cbc_encrypt(struct crypto_tfm *tfm,
@@ -205,9 +251,14 @@ static int cbc_encrypt(struct crypto_tfm *tfm,
                        struct scatterlist *src,
 		       unsigned int nbytes)
 {
-	return crypt(tfm, dst, src, nbytes,
-	             tfm->__crt_alg->cra_cipher.cia_encrypt,
-	             cbc_process_encrypt, tfm->crt_cipher.cit_iv);
+	struct cipher_desc desc;
+
+	desc.tfm = tfm;
+	desc.crfn = tfm->__crt_alg->cra_cipher.cia_encrypt;
+	desc.prfn = cbc_process_encrypt;
+	desc.info = tfm->crt_cipher.cit_iv;
+
+	return crypt(&desc, dst, src, nbytes);
 }
 
 static int cbc_encrypt_iv(struct crypto_tfm *tfm,
@@ -215,9 +266,14 @@ static int cbc_encrypt_iv(struct crypto_tfm *tfm,
                           struct scatterlist *src,
                           unsigned int nbytes, u8 *iv)
 {
-	return crypt(tfm, dst, src, nbytes,
-	             tfm->__crt_alg->cra_cipher.cia_encrypt,
-	             cbc_process_encrypt, iv);
+	struct cipher_desc desc;
+
+	desc.tfm = tfm;
+	desc.crfn = tfm->__crt_alg->cra_cipher.cia_encrypt;
+	desc.prfn = cbc_process_encrypt;
+	desc.info = iv;
+
+	return crypt(&desc, dst, src, nbytes);
 }
 
 static int cbc_decrypt(struct crypto_tfm *tfm,
@@ -225,9 +281,14 @@ static int cbc_decrypt(struct crypto_tfm *tfm,
                        struct scatterlist *src,
 		       unsigned int nbytes)
 {
-	return crypt(tfm, dst, src, nbytes,
-	             tfm->__crt_alg->cra_cipher.cia_decrypt,
-	             cbc_process_decrypt, tfm->crt_cipher.cit_iv);
+	struct cipher_desc desc;
+
+	desc.tfm = tfm;
+	desc.crfn = tfm->__crt_alg->cra_cipher.cia_decrypt;
+	desc.prfn = cbc_process_decrypt;
+	desc.info = tfm->crt_cipher.cit_iv;
+
+	return crypt(&desc, dst, src, nbytes);
 }
 
 static int cbc_decrypt_iv(struct crypto_tfm *tfm,
@@ -235,9 +296,14 @@ static int cbc_decrypt_iv(struct crypto_tfm *tfm,
                           struct scatterlist *src,
                           unsigned int nbytes, u8 *iv)
 {
-	return crypt(tfm, dst, src, nbytes,
-	             tfm->__crt_alg->cra_cipher.cia_decrypt,
-	             cbc_process_decrypt, iv);
+	struct cipher_desc desc;
+
+	desc.tfm = tfm;
+	desc.crfn = tfm->__crt_alg->cra_cipher.cia_decrypt;
+	desc.prfn = cbc_process_decrypt;
+	desc.info = iv;
+
+	return crypt(&desc, dst, src, nbytes);
 }
 
 static int nocrypt(struct crypto_tfm *tfm,
diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c
index 50c9461e8cc6..47ac90e615f4 100644
--- a/crypto/scatterwalk.c
+++ b/crypto/scatterwalk.c
@@ -100,7 +100,7 @@ void scatterwalk_done(struct scatter_walk *walk, int out, int more)
 int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 			   size_t nbytes, int out)
 {
-	do {
+	while (nbytes > walk->len_this_page) {
 		memcpy_dir(buf, walk->data, walk->len_this_page, out);
 		buf += walk->len_this_page;
 		nbytes -= walk->len_this_page;
@@ -108,7 +108,7 @@ int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
 		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;
diff --git a/crypto/scatterwalk.h b/crypto/scatterwalk.h
index 02aa56c649b4..5495bb970816 100644
--- a/crypto/scatterwalk.h
+++ b/crypto/scatterwalk.h
@@ -40,10 +40,10 @@ static inline int scatterwalk_samebuf(struct scatter_walk *walk_in,
 	       walk_in->offset == walk_out->offset;
 }
 
-static inline int scatterwalk_across_pages(struct scatter_walk *walk,
-					   unsigned int nbytes)
+static inline unsigned int scatterwalk_clamp(struct scatter_walk *walk,
+					     unsigned int nbytes)
 {
-	return nbytes > walk->len_this_page;
+	return nbytes > walk->len_this_page ? walk->len_this_page : nbytes;
 }
 
 static inline void scatterwalk_advance(struct scatter_walk *walk,