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Commit d31aa621 authored by Eric Biggers's avatar Eric Biggers
Browse files

BACKPORT, FROMGIT: crypto: arm/chacha20 - limit the preemption-disabled section 



To improve responsivesess, disable preemption for each step of the walk
(which is at most PAGE_SIZE) rather than for the entire
encryption/decryption operation.

Suggested-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>

(cherry picked from commit be2830b15b60011845ad701076511e8b93b2fd76
 https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git

 master)

Conflicts:
	arch/arm/crypto/chacha20-neon-glue.c

Bug: 112008522
Test: As series, see Ic61c13b53facfd2173065be715a7ee5f3af8760b
Change-Id: I21bfa9c14635e695b128c87df53fea505c3cdd4e
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent bb31ed53

arch/arm/crypto/chacha20-neon-glue.c

+4 −5
Original line number Diff line number Diff line
@@ -67,29 +67,28 @@ static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst, 
	if (nbytes <= CHACHA_BLOCK_SIZE || !may_use_simd())

		return crypto_chacha_crypt(desc, dst, src, nbytes);



	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;

	blkcipher_walk_init(&walk, dst, src, nbytes);

	err = blkcipher_walk_virt_block(desc, &walk, CHACHA_BLOCK_SIZE);



	crypto_chacha_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);



	kernel_neon_begin();



	while (walk.nbytes >= CHACHA_BLOCK_SIZE) {

		kernel_neon_begin();

		chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,

				rounddown(walk.nbytes, CHACHA_BLOCK_SIZE));

		kernel_neon_end();

		err = blkcipher_walk_done(desc, &walk,

					  walk.nbytes % CHACHA_BLOCK_SIZE);

	}



	if (walk.nbytes) {

		kernel_neon_begin();

		chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,

				walk.nbytes);

		kernel_neon_end();

		err = blkcipher_walk_done(desc, &walk, 0);

	}



	kernel_neon_end();



	return err;

}