From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B443E155342; Mon, 9 Jun 2025 07:40:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749454845; cv=none; b=EG2cbr2UTdPN6PFh5WCtezTOKUc2gS3SuccV1ECncSUJZ4It4amoYj8zJYa0AAhK+kKCkzGFiybibvln39LVDY9BdJDceNO3o/2ZUoOlSwBgM+HqYoa+DkvCrBeQ/fEOzz7y/LVLrRTrx/1MgvRGcnS7H4J7Ciq04AHiOx+t6zI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749454845; c=relaxed/simple; bh=209nlqUCXw1v1f3VX0uAONXnvWEHs95NYNmSYw3A208=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hGqR0101xDAVE57UVjw+KYMrg3J/KU++28lIGogjp5NCOSkuxFZswbpF/WiIp6XSU7vuWkmhHNIyDnRi5Mwc+zjr8wvxhi8soPvi/YPQuQbcpe0V7awKXtmGP5ftmie2O+Ol6oA4w+EHeRzTxhgVibhv6sU5KctM4HbGwf7L4xg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gY73dLvT; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gY73dLvT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D454C4CEEB; Mon, 9 Jun 2025 07:40:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749454845; bh=209nlqUCXw1v1f3VX0uAONXnvWEHs95NYNmSYw3A208=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gY73dLvTuG20cJBz/uTBYeNpVArZbVpympdOLaTXmTkeunUr3SogtkPrwip9348ep GlTKa/1aKhnLBecgL6YOHGiyn6aWWyzDNjIomZXEgN5BhgUj0hO1mpCxdKv9aobqz4 RnoBw1oQVRZdaapyQ1FXeBDESYqX3Q0OfYu1fpREr/8jdQi513Lp7mLf63c+XEToKH LYD8l/KcwV19regOTXQOVdkfp/yPLBBpzHKzu/sXfWel7SlgoHtargDiNocTs3CBSM 6lBah99e7LOsXVUIFQVjuP75ksUm9JxSa89Qa+QLFdgswE9W8Py551smm+rsV6wroC 3VMj1AV9M7FpQ== Date: Mon, 9 Jun 2025 09:40:40 +0200 From: Ingo Molnar To: Eric Biggers Cc: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, linux-arch@vger.kernel.org, Ard Biesheuvel , "Jason A . Donenfeld" , Linus Torvalds Subject: Re: [PATCH v2 00/12] lib/crc: improve how arch-optimized code is integrated Message-ID: References: <20250607200454.73587-1-ebiggers@kernel.org> Precedence: bulk X-Mailing-List: loongarch@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250607200454.73587-1-ebiggers@kernel.org> * Eric Biggers wrote: > This series is also available at: > > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git lib-crc-arch-v2 > > This series improves how lib/crc supports arch-optimized code. First, > instead of the arch-optimized CRC code being in arch/$(SRCARCH)/lib/, it > will now be in lib/crc/$(SRCARCH)/. Second, the API functions (e.g. > crc32c()), arch-optimized functions (e.g. crc32c_arch()), and generic > functions (e.g. crc32c_base()) will now be part of a single module for > each CRC type, allowing better inlining and dead code elimination. The > second change is made possible by the first. > > As an example, consider CONFIG_CRC32=m on x86. We'll now have just > crc32.ko instead of both crc32-x86.ko and crc32.ko. The two modules > were already coupled together and always both got loaded together via > direct symbol dependency, so the separation provided no benefit. > > Note: later I'd like to apply the same design to lib/crypto/ too, where > often the API functions are out-of-line so this will work even better. > In those cases, for each algorithm we currently have 3 modules all > coupled together, e.g. libsha256.ko, libsha256-generic.ko, and > sha256-x86.ko. We should have just one, inline things properly, and > rely on the compiler's dead code elimination to decide the inclusion of > the generic code instead of manually setting it via kconfig. > > Having arch-specific code outside arch/ was somewhat controversial when > Zinc proposed it back in 2018. But I don't think the concerns are > warranted. It's better from a technical perspective, as it enables the > improvements mentioned above. This model is already successfully used > in other places in the kernel such as lib/raid6/. The community of each > architecture still remains free to work on the code, even if it's not in > arch/. At the time there was also a desire to put the library code in > the same files as the old-school crypto API, but that was a mistake; now > that the library is separate, that's no longer a constraint either. > > Changed in v2: > - Fixed build warning on architectures without any optimized CRC code > - Fixed build warning in sparc/crc32.h by removing pr_fmt > - Moved fallback definitions of crc32*_arch back into arch files > - Remove ARCH_HAS_CRC* symbols at end of series instead of beginning, > so that they're not removed until they're no longer being selected > - Slightly improved some commit messages > - Rebased onto other pending lib/crc changes > > Eric Biggers (12): > lib/crc: move files into lib/crc/ > lib/crc: prepare for arch-optimized code in subdirs of lib/crc/ > lib/crc/arm: migrate arm-optimized CRC code into lib/crc/ > lib/crc/arm64: migrate arm64-optimized CRC code into lib/crc/ > lib/crc/loongarch: migrate loongarch-optimized CRC code into lib/crc/ > lib/crc/mips: migrate mips-optimized CRC code into lib/crc/ > lib/crc/powerpc: migrate powerpc-optimized CRC code into lib/crc/ > lib/crc/riscv: migrate riscv-optimized CRC code into lib/crc/ > lib/crc/s390: migrate s390-optimized CRC code into lib/crc/ > lib/crc/sparc: migrate sparc-optimized CRC code into lib/crc/ > lib/crc/x86: migrate x86-optimized CRC code into lib/crc/ > lib/crc: remove ARCH_HAS_* kconfig symbols For the movement of the x86 bits: Acked-by: Ingo Molnar > rename {arch/s390/lib => lib/crc/s390}/crc32be-vx.c (100%) > rename {arch/s390/lib => lib/crc/s390}/crc32le-vx.c (100%) > rename arch/sparc/lib/crc32.c => lib/crc/sparc/crc32.h (60%) > rename {arch/sparc/lib => lib/crc/sparc}/crc32c_asm.S (100%) > create mode 100644 lib/crc/tests/Makefile > rename lib/{ => crc}/tests/crc_kunit.c (100%) > rename {arch/x86/lib => lib/crc/x86}/crc-pclmul-consts.h (100%) > rename {arch/x86/lib => lib/crc/x86}/crc-pclmul-template.S (100%) > rename {arch/x86/lib => lib/crc/x86}/crc-pclmul-template.h (100%) > rename arch/x86/lib/crc-t10dif.c => lib/crc/x86/crc-t10dif.h (56%) > rename {arch/x86/lib => lib/crc/x86}/crc16-msb-pclmul.S (100%) > rename {arch/x86/lib => lib/crc/x86}/crc32-pclmul.S (100%) One small namespace suggestion: wouldn't it be better to move the arch support code to lib/crc/arch/, instead of lib/crc/? That way any generic code will stand out better and architecture directories don't crowd out what is supposed to be generic code. Thanks, Ingo