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From: "Ard Biesheuvel" <ardb@kernel.org>
To: "Eric Biggers" <ebiggers@kernel.org>
Cc: linux-crypto@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	"Demian Shulhan" <demyansh@gmail.com>
Subject: Re: [PATCH 1/5] lib/crc: arm64: Drop unnecessary chunking logic from crc64
Date: Wed, 01 Apr 2026 08:57:23 +0200	[thread overview]
Message-ID: <232d35ea-433b-4eef-86e7-5cfb9f033bf5@app.fastmail.com> (raw)
In-Reply-To: <20260331223300.GA45047@quark>



On Wed, 1 Apr 2026, at 00:33, Eric Biggers wrote:
> On Mon, Mar 30, 2026 at 04:46:32PM +0200, Ard Biesheuvel wrote:
>> On arm64, kernel mode NEON executes with preemption enabled, so there is
>> no need to chunk the input by hand.
>> 
>> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
>
> There's still similar "chunking" in other arm64 code:
>
>     $ git grep -E 'SZ_4K|cond_yield' lib/crypto/arm64
>     lib/crypto/arm64/chacha.h:              unsigned int todo = 
> min_t(unsigned int, bytes, SZ_4K);
>     lib/crypto/arm64/poly1305.h:                    unsigned int todo = 
> min_t(unsigned int, len, SZ_4K);
>     lib/crypto/arm64/sha1-ce-core.S:        cond_yield      1f, x5, x6
>     lib/crypto/arm64/sha256-ce.S:   cond_yield      1f, x5, x6
>     lib/crypto/arm64/sha3-ce-core.S:        cond_yield 4f, x8, x9
>     lib/crypto/arm64/sha512-ce-core.S:      cond_yield      3f, x4, x5
>
> I thought it was still sticking around, despite kernel-mode NEON now
> being preemptible on arm64, because of CONFIG_PREEMPT_VOLUNTARY.
>
> However, I see that support for CONFIG_PREEMPT_VOLUNTARY was recently
> removed on arm64.  So that's what finally makes this no longer needed,
> and we can now clean up these other cases too, right?
>

Indeed.


  parent reply	other threads:[~2026-04-01  6:57 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-30 14:46 [PATCH 0/5] crc64: Tweak intrinsics code and enable it for ARM Ard Biesheuvel
2026-03-30 14:46 ` [PATCH 1/5] lib/crc: arm64: Drop unnecessary chunking logic from crc64 Ard Biesheuvel
2026-03-31 22:33   ` Eric Biggers
2026-04-01  0:09     ` Eric Biggers
2026-04-01  6:57     ` Ard Biesheuvel [this message]
2026-03-30 14:46 ` [PATCH 2/5] lib/crc: arm64: Use existing macros for kernel-mode FPU cflags Ard Biesheuvel
2026-03-30 14:46 ` [PATCH 3/5] ARM: Add a neon-intrinsics.h header like on arm64 Ard Biesheuvel
2026-03-30 14:46 ` [PATCH 4/5] lib/crc: arm64: Simplify intrinsics implementation Ard Biesheuvel
2026-03-30 14:46 ` [PATCH 5/5] lib/crc: arm: Enable arm64's NEON intrinsics implementation of crc64 Ard Biesheuvel
2026-03-31  6:47   ` Christoph Hellwig
2026-03-31  8:20     ` Ard Biesheuvel
2026-03-31 22:41   ` Eric Biggers
2026-04-01 16:48     ` Ard Biesheuvel
2026-04-01 19:59 ` [PATCH 0/5] crc64: Tweak intrinsics code and enable it for ARM Eric Biggers
2026-04-02  8:52   ` Ard Biesheuvel
2026-04-02 23:40     ` Eric Biggers
2026-04-03  6:49       ` Ard Biesheuvel
2026-04-03 19:59         ` Eric Biggers

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