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 4098D242D90; Tue, 10 Jun 2025 18:48:19 +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=1749581300; cv=none; b=K1s24Dcqy0tWM3KiE6Cw9bKlpgP+zhIuuZc128Bc9gRE44Y+YU1sHwVWA6UTRiqehC/76DQhAzaEZrMD2aF9RAQAHh6HJAwD4rVCGrV5nAjU6kfpQLXiUU8J4B+IszntYw4HuXWyJ/UbDvzEeCY0qaqd9hC2XmM4xKMnsqN+4RM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749581300; c=relaxed/simple; bh=fW4WUlLPzTcOGUmKEUJPh5AreVUZepIXG7py1Yrxjzw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J5fdeL4tAz0i77qjv2ivPrif6dpY94K3J/TuAVDuXMIo33I2TwfarApBIzMzg1cMDflinlFfnpJITUF41rdS+hndXpjtCfrJA5sMnRti5QLgOEdIotnS1wu/ciWMPTz1oSujgnqS3wSLeqabqq2BVyc+jQdxYQ4bnC4UDU6AY40= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N2rR2VQ8; 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="N2rR2VQ8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B537C4CEED; Tue, 10 Jun 2025 18:48:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749581299; bh=fW4WUlLPzTcOGUmKEUJPh5AreVUZepIXG7py1Yrxjzw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=N2rR2VQ8Oq9Cmc6H9eooraC/6WL6LWGn/CyQscdSYoBnxrd6j556t8Yr4T5TQT33Y KjAddPGzxn/a1xZsEPhM/wtGddhOqKWPsMgUketQdpHVnfaf6YaA4v61Gwh2iKlc4q XkImdNQGb8y/Dgab6Udgq58Wxqco3rHtvNJ/qMnxwy9JcEIqHgZDQeAJCWUxC+A3oV OL2cGfo+A5I1Vic3XRH5dNQh8oPwI4lU72wrwqRIvmCAJJGgAq2b9hXkSx0B0RmSDD yJDpesZCL8iTxUJpJJvTqXeUEjtLqkz9iTejv45bhW3iFAmqRSy59HNfkPBVXi01hH mICO2Doj48fpw== Date: Tue, 10 Jun 2025 11:47:55 -0700 From: Eric Biggers To: linux-kernel@vger.kernel.org Cc: 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: <20250610184755.GC1649@sol> References: <20250607200454.73587-1-ebiggers@kernel.org> Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org 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> On Sat, Jun 07, 2025 at 01:04:42PM -0700, 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 Applied to https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=crc-next - Eric