From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7BA6DC5B552 for ; Mon, 9 Jun 2025 19:44:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=8A4kfNqCpnvhSbBzTBjtE+VJ2L30xs4Ao8ewlm8dEvs=; b=HNEApPXSPXXLqtuGSa+uB2OEeu +t3tTxtSGreN6ALa7iTYp1aKYmle9XUJCIucSBnuTfjIBgJ9aqXrQmwl2zpsLu9eOT4y9209GG6TH jw8Umzq4PEg1akPd4hAauTt1UjuJM/Vy2khT63gkhWnet8MnxqRX+uwJvWBWtuFGJ171yGJ1ZWDP4 26iR1nsYAztRE8193bxrzbpVJ2rP/FPI3fZtDlMLwCrZYxddDqJT7Ymkp1svCT8eFJDFwrJ16pbW5 KN/yLZYq2LEHPdEVDMTpCFTVDiD0dkejF0KNR9ZS6cuKgDWn7WDQyDzZSHX0NymWFklKuDJdLMtES BQNSeNXg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uOiQH-0000000547t-0VLl; Mon, 09 Jun 2025 19:44:45 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1uOheA-00000004xU9-1uMV; Mon, 09 Jun 2025 18:55:03 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 290694ACCA; Mon, 9 Jun 2025 18:55:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DDEAC4CEEF; Mon, 9 Jun 2025 18:55:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749495302; bh=i03d00nCfUWfOdFAfB3hz6pL/gDpm+GCWlrY8GYnNSU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=cOGXtZ0bxE5c/cKVjIahkTcrKCRAsE2Gfxn3UIhlFlFiZLaC+zKdF7VWxfKm8/ETS 6AhGs0umiRMCJ5JgdBhNOOkRxSsFWAtxF3SJIcO4BKZGFJs1ZQtGYfS9ZJ9KjnFtXu CoUuDzdDeoQNA3IJviIlNiJi7ydg2ehdcQ5OXBzI0xl+XsUGv/gmofveqW1cZVJlxj 7S5NNv/e7xF0C/H29trUyZ+4svuZFkbjIOhn5nXwrlL711gYmP+gm6Ewk+tz2CReoY NFWzzRmLR5sYfJufJHFK1j4djDnBCF+UiHFg8rnM/mFlrhQ4MNaEJcQxnaEuTEhFf3 PK9kqt1NEZKGw== Date: Mon, 9 Jun 2025 11:54:39 -0700 From: Eric Biggers To: Ingo Molnar 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: <20250609185439.GB1255@sol> References: <20250607200454.73587-1-ebiggers@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250609_115502_536876_51DEAE07 X-CRM114-Status: GOOD ( 33.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jun 09, 2025 at 09:40:40AM +0200, Ingo Molnar wrote: > > * 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. I don't think that yet another level of directories would provide much value here. The only non-arch subdirectory of lib/crc/ is "tests", so it's not like there are a lot of subdirectories that could be confused with arch names. - Eric