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Wed, 1 Apr 2026 02:57:43 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-crypto@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: Aics4N9pNpZs Date: Wed, 01 Apr 2026 08:57:23 +0200 From: "Ard Biesheuvel" To: "Eric Biggers" Cc: linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Demian Shulhan" Message-Id: <232d35ea-433b-4eef-86e7-5cfb9f033bf5@app.fastmail.com> In-Reply-To: <20260331223300.GA45047@quark> References: <20260330144630.33026-7-ardb@kernel.org> <20260330144630.33026-8-ardb@kernel.org> <20260331223300.GA45047@quark> Subject: Re: [PATCH 1/5] lib/crc: arm64: Drop unnecessary chunking logic from crc64 Content-Type: text/plain Content-Transfer-Encoding: 7bit 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 > > 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.