From: "Ard Biesheuvel" <ardb@kernel.org>
To: "Eric Biggers" <ebiggers@kernel.org>, linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>
Subject: Re: [PATCH] lib/crypto: x86/aes-ctr: Remove some unreachable code
Date: Fri, 02 Oct 2026 11:35:39 +0200 [thread overview]
Message-ID: <421b8d6e-1a95-47ad-9e0a-35b390cb6ade@app.fastmail.com> (raw)
In-Reply-To: <20261002034405.49886-1-ebiggers@kernel.org>
On Fri, 2 Oct 2026, at 05:44, Eric Biggers wrote:
> In the AES-CTR and AES-XCTR code that handles a remainder of '4*VL < LEN
> < 8*VL', first 4 full vectors are processed, leaving 0 < LEN < 4*VL.
> After that, five different cases are handled depending on whether there
> are 0, 1, 2, 3, or 4 full vectors remaining. But the case of 4 vectors
> is never reached there, making the code handling it unused. Remove it.
>
> With that done, the '.Lxor_tail_partial_vec_3\@' block would be reached
> only via an unconditional jump. Therefore, relocate it to the only
> place that jumps to it. This allows removing the jump at the end of the
> '.Lxor_tail_partial_vec_2\@' block and making it fall through.
>
> Signed-off-by: Eric Biggers <ebiggers@kernel.org>
> ---
> lib/crypto/x86/aes-ctr-avx-x86_64.S | 18 ++++++------------
> 1 file changed, 6 insertions(+), 12 deletions(-)
>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
next prev parent reply other threads:[~2026-10-02 9:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-02 3:44 Eric Biggers
2026-10-02 9:35 ` Ard Biesheuvel [this message]
2026-10-02 21:42 ` Eric Biggers
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