[PATCH v4 06/14] crypto: arm/chacha20 - limit the preemption-disabled section

Eric Biggers
2018-11-17T01:30:07Z

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: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
arch/arm/crypto/chacha20-neon-glue.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm/crypto/chacha20-neon-glue.c b/arch/arm/crypto/chacha20-neon-glue.c
index 7386eb1c1889..2bc035cb8f23 100644
--- a/arch/arm/crypto/chacha20-neon-glue.c
+++ b/arch/arm/crypto/chacha20-neon-glue.c
@@ -68,22 +68,22 @@ static int chacha20_neon(struct skcipher_request *req)
if (req->cryptlen <= CHACHA_BLOCK_SIZE || !may_use_simd())
return crypto_chacha_crypt(req);

- err = skcipher_walk_virt(&walk, req, true);
+ err = skcipher_walk_virt(&walk, req, false);

crypto_chacha_init(state, ctx, walk.iv);

- kernel_neon_begin();
while (walk.nbytes > 0) {
unsigned int nbytes = walk.nbytes;

if (nbytes < walk.total)
nbytes = round_down(nbytes, walk.stride);

+ kernel_neon_begin();
chacha20_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
nbytes);
+ kernel_neon_end();
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}
- kernel_neon_end();

return err;
}
--
2.19.1.1215.g8438c0b245-goog