[PATCH v3 04/29] crypto: arm64/chacha - depend on generic chacha library instead of crypto driver

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

Depend on the generic ChaCha library routines instead of pulling in the
generic ChaCha skcipher driver, which is more than we need, and makes
managing the dependencies between the generic library, generic driver,
accelerated library and driver more complicated.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 arch/arm64/crypto/Kconfig            |  2 +-
 arch/arm64/crypto/chacha-neon-glue.c | 54 +++++++++++++-------
 2 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/crypto/Kconfig b/arch/arm64/crypto/Kconfig
index 4922c4451e7c..fdf52d5f18f9 100644
--- a/arch/arm64/crypto/Kconfig
+++ b/arch/arm64/crypto/Kconfig
@@ -103,7 +103,7 @@ config CRYPTO_CHACHA20_NEON
 	tristate "ChaCha20, XChaCha20, and XChaCha12 stream ciphers using NEON instructions"
 	depends on KERNEL_MODE_NEON
 	select CRYPTO_BLKCIPHER
-	select CRYPTO_CHACHA20
+	select CRYPTO_LIB_CHACHA_GENERIC
 
 config CRYPTO_NHPOLY1305_NEON
 	tristate "NHPoly1305 hash function using NEON instructions (for Adiantum)"
diff --git a/arch/arm64/crypto/chacha-neon-glue.c b/arch/arm64/crypto/chacha-neon-glue.c
index d4cc61bfe79d..6450bb9f55f4 100644
--- a/arch/arm64/crypto/chacha-neon-glue.c
+++ b/arch/arm64/crypto/chacha-neon-glue.c
@@ -64,22 +64,30 @@ static int chacha_neon_stream_xor(struct skcipher_request *req,
 {
 	struct skcipher_walk walk;
 	u32 state[16];
+	bool do_neon;
 	int err;
 
 	err = skcipher_walk_virt(&walk, req, false);
 
-	crypto_chacha_init(state, ctx, iv);
+	chacha_init_generic(state, ctx->key, iv);
 
+	do_neon = (req->cryptlen > CHACHA_BLOCK_SIZE) && crypto_simd_usable();
 	while (walk.nbytes > 0) {
 		unsigned int nbytes = walk.nbytes;
 
 		if (nbytes < walk.total)
 			nbytes = rounddown(nbytes, walk.stride);
 
-		kernel_neon_begin();
-		chacha_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
-			      nbytes, ctx->nrounds);
-		kernel_neon_end();
+		if (!do_neon) {
+			chacha_crypt_generic(state, walk.dst.virt.addr,
+					     walk.src.virt.addr, nbytes,
+					     ctx->nrounds);
+		} else {
+			kernel_neon_begin();
+			chacha_doneon(state, walk.dst.virt.addr,
+				      walk.src.virt.addr, nbytes, ctx->nrounds);
+			kernel_neon_end();
+		}
 		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
 	}
 
@@ -91,9 +99,6 @@ static int chacha_neon(struct skcipher_request *req)
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
 
-	if (req->cryptlen <= CHACHA_BLOCK_SIZE || !crypto_simd_usable())
-		return crypto_chacha_crypt(req);
-
 	return chacha_neon_stream_xor(req, ctx, req->iv);
 }
 
@@ -105,14 +110,15 @@ static int xchacha_neon(struct skcipher_request *req)
 	u32 state[16];
 	u8 real_iv[16];
 
-	if (req->cryptlen <= CHACHA_BLOCK_SIZE || !crypto_simd_usable())
-		return crypto_xchacha_crypt(req);
+	chacha_init_generic(state, ctx->key, req->iv);
 
-	crypto_chacha_init(state, ctx, req->iv);
-
-	kernel_neon_begin();
-	hchacha_block_neon(state, subctx.key, ctx->nrounds);
-	kernel_neon_end();
+	if (req->cryptlen > CHACHA_BLOCK_SIZE && crypto_simd_usable()) {
+		kernel_neon_begin();
+		hchacha_block_neon(state, subctx.key, ctx->nrounds);
+		kernel_neon_end();
+	} else {
+		hchacha_block_generic(state, subctx.key, ctx->nrounds);
+	}
 	subctx.nrounds = ctx->nrounds;
 
 	memcpy(&real_iv[0], req->iv + 24, 8);
@@ -120,6 +126,18 @@ static int xchacha_neon(struct skcipher_request *req)
 	return chacha_neon_stream_xor(req, &subctx, real_iv);
 }
 
+static int chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
+		    unsigned int keysize)
+{
+	return chacha_setkey(tfm, key, keysize, 20);
+}
+
+static int chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key,
+		    unsigned int keysize)
+{
+	return chacha_setkey(tfm, key, keysize, 12);
+}
+
 static struct skcipher_alg algs[] = {
 	{
 		.base.cra_name		= "chacha20",
@@ -134,7 +152,7 @@ static struct skcipher_alg algs[] = {
 		.ivsize			= CHACHA_IV_SIZE,
 		.chunksize		= CHACHA_BLOCK_SIZE,
 		.walksize		= 5 * CHACHA_BLOCK_SIZE,
-		.setkey			= crypto_chacha20_setkey,
+		.setkey			= chacha20_setkey,
 		.encrypt		= chacha_neon,
 		.decrypt		= chacha_neon,
 	}, {
@@ -150,7 +168,7 @@ static struct skcipher_alg algs[] = {
 		.ivsize			= XCHACHA_IV_SIZE,
 		.chunksize		= CHACHA_BLOCK_SIZE,
 		.walksize		= 5 * CHACHA_BLOCK_SIZE,
-		.setkey			= crypto_chacha20_setkey,
+		.setkey			= chacha20_setkey,
 		.encrypt		= xchacha_neon,
 		.decrypt		= xchacha_neon,
 	}, {
@@ -166,7 +184,7 @@ static struct skcipher_alg algs[] = {
 		.ivsize			= XCHACHA_IV_SIZE,
 		.chunksize		= CHACHA_BLOCK_SIZE,
 		.walksize		= 5 * CHACHA_BLOCK_SIZE,
-		.setkey			= crypto_chacha12_setkey,
+		.setkey			= chacha12_setkey,
 		.encrypt		= xchacha_neon,
 		.decrypt		= xchacha_neon,
 	}
-- 
2.20.1