Re: [PATCH] crypto: crypto_xor - use helpers for unaligned accesses

From: Herbert Xu <herbert@gondor.apana.org.au>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-crypto@vger.kernel.org, ebiggers@kernel.org
Subject: Re: [PATCH] crypto: crypto_xor - use helpers for unaligned accesses
Date: Wed, 23 Feb 2022 14:50:03 +1200	[thread overview]
Message-ID: <YhWg246ql3Xa0MRR@gondor.apana.org.au> (raw)
In-Reply-To: <20220215105717.184572-1-ardb@kernel.org>

On Tue, Feb 15, 2022 at 11:57:17AM +0100, Ard Biesheuvel wrote:
> Dereferencing a misaligned pointer is undefined behavior in C, and may
> result in codegen on architectures such as ARM that trigger alignments
> traps and expensive fixups in software.
> 
> Instead, use the get_aligned()/put_aligned() accessors, which are cheap
> or even completely free when CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y.
> 
> In the converse case, the prior alignment checks ensure that the casts
> are safe, and so no unaligned accessors are necessary.
> 
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  crypto/algapi.c         | 24 +++++++++++++++++++++---
>  include/crypto/algapi.h | 11 +++++++++--
>  2 files changed, 30 insertions(+), 5 deletions(-)

Ard, could you please take a look at the two kbuild reports and
see if there is an issue that needs to be resolved?

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt