Commit c77da486 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Herbert Xu
Browse files

crypto: arm64/chacha - depend on generic chacha library instead of crypto driver 



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.

While at it, drop the logic to prefer the scalar code on short inputs.
Turning the NEON on and off is cheap these days, and one major use case
for ChaCha20 is ChaCha20-Poly1305, which is guaranteed to hit the scalar
path upon every invocation  (when doing the Poly1305 nonce generation)

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 84e03fa3

arch/arm64/crypto/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -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_SKCIPHER

	select CRYPTO_CHACHA20

	select CRYPTO_LIB_CHACHA_GENERIC



config CRYPTO_NHPOLY1305_NEON

	tristate "NHPoly1305 hash function using NEON instructions (for Adiantum)"

arch/arm64/crypto/chacha-neon-glue.c

+22 −18
Original line number Diff line number Diff line
@@ -68,7 +68,7 @@ static int chacha_neon_stream_xor(struct skcipher_request *req, 


	err = skcipher_walk_virt(&walk, req, false);



	crypto_chacha_init(state, ctx, iv);

	chacha_init_generic(state, ctx->key, iv);



	while (walk.nbytes > 0) {

		unsigned int nbytes = walk.nbytes;
@@ -76,10 +76,16 @@ static int chacha_neon_stream_xor(struct skcipher_request *req, 
		if (nbytes < walk.total)

			nbytes = rounddown(nbytes, walk.stride);



		if (!crypto_simd_usable()) {

			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);

			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 +97,6 @@ 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 +108,15 @@ 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);



	crypto_chacha_init(state, ctx, req->iv);

	chacha_init_generic(state, ctx->key, req->iv);



	if (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);
@@ -134,7 +138,7 @@ 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 +154,7 @@ 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 +170,7 @@ 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,

	}

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