From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 C73B0304BBA; Wed, 15 Oct 2025 07:37:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760513846; cv=none; b=ju6EqBgwG1IhddvFXEayJq90848Zseu1azkj76c9eDFENbm418EzFUBPFMMIkMYDxlnO65aCDdJhjT8eRm5yRHfuyQDS/ovE5LHZeyBu+7HBr4bDQtAojeSFK4hmvwN/i1aKD5Mj+ecPscMZSk6CD+vWhlf1qjQJ34ZO9L99SRE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760513846; c=relaxed/simple; bh=usd1O1gWSARVzS39vvkdNKA/0m34I6mskKXhBcUW4JE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cjTSi33AVhOeDBqS79Ku9N6IvAhEaoCVqUNWtPx68g8b6GVSstyoMp+NsMK9wA5F2f4xHw2+CHHyWUI51Q5kSIqeoqG1MvT6WKP7zmMaCrZcZeje/zAyaGCgh4+pm6f3iepR4iV13zOILDZUn3laTNvu+/1/dVeGfHHvAfzvoxs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=MqmgDj7S; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MqmgDj7S" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=K0Byfm25HAm+hkuPU/+MWl6Aww3n7DOCSkjI/zRPF4w=; b=MqmgDj7SwmG2m7iemtBBl9O0WI ICtTPOLnsUcUEE4QyBZjiakIuKfaL+DI/SdBoajINUi8s4JFhUj8jouZ2qRnSmxvH8zv4QrAgQwJz sOml5c8u2hWLB+BaJgIfH8xYKmDE847NLIBewcea/0pgau3GjKmrVc+9OzvXNxsSM/XoMk/dz3nRg exDTpN2rGq5/7FPem/jALj6GOaYzvaUXXbxh0DYGbV0COAW1BETkq/VNK9VRhQESH23SGL/Im0QA3 aGidDeS4PVbzj8jqZEoaUBqx0iYkA5zpd+f52FuSEaKjF7v6HxMkp56PwgFA/7wBrC3VGjf5uXwY9 VQcd+Z4g==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1v8w4D-0000000A8y5-3wOB; Wed, 15 Oct 2025 07:37:03 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id A4D59300325; Wed, 15 Oct 2025 09:37:01 +0200 (CEST) Date: Wed, 15 Oct 2025 09:37:01 +0200 From: Peter Zijlstra To: Sasha Levin Cc: nathan@kernel.org, Matt.Kelly2@boeing.com, akpm@linux-foundation.org, andrew.j.oppelt@boeing.com, anton.ivanov@cambridgegreys.com, ardb@kernel.org, arnd@arndb.de, bhelgaas@google.com, bp@alien8.de, chuck.wolber@boeing.com, dave.hansen@linux.intel.com, dvyukov@google.com, hpa@zytor.com, jinghao7@illinois.edu, johannes@sipsolutions.net, jpoimboe@kernel.org, justinstitt@google.com, kees@kernel.org, kent.overstreet@linux.dev, linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-um@lists.infradead.org, llvm@lists.linux.dev, luto@kernel.org, marinov@illinois.edu, masahiroy@kernel.org, maskray@google.com, mathieu.desnoyers@efficios.com, matthew.l.weber3@boeing.com, mhiramat@kernel.org, mingo@redhat.com, morbo@google.com, ndesaulniers@google.com, oberpar@linux.ibm.com, paulmck@kernel.org, richard@nod.at, rostedt@goodmis.org, samitolvanen@google.com, samuel.sarkisian@boeing.com, steven.h.vanderleest@boeing.com, tglx@linutronix.de, tingxur@illinois.edu, tyxu@illinois.edu, wentaoz5@illinois.edu, x86@kernel.org Subject: Re: [RFC PATCH 0/4] Enable Clang's Source-based Code Coverage and MC/DC for x86-64 Message-ID: <20251015073701.GZ3419281@noisy.programming.kicks-ass.net> References: <20250829181007.GA468030@ax162> <20251014232639.673260-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-efi@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: <20251014232639.673260-1-sashal@kernel.org> On Tue, Oct 14, 2025 at 07:26:35PM -0400, Sasha Levin wrote: > This series adds support for Clang's Source-based Code Coverage to the > Linux kernel, enabling more accurate coverage measurement at the source > level compared to gcov. This is particularly valuable for safety-critical > use cases (automotive, medical, aerospace) where MC/DC coverage is required > for certification. > > Changes since previous patchset [1]: > - Rebased on v6.18-rc1 > - Adapted to lib/crypto reorganization (curve25519 exclusion moved to > lib/crypto/Makefile) > - Minor correctness fixes throughout the codebase > > The implementation has been tested with a kernel build using Clang 18+ and > boots successfully in a KVM environment with instrumentation enabled. > > [1] https://lore.kernel.org/all/20240905043245.1389509-1-wentaoz5@illinois.edu/ > > Wentao Zhang (4): > llvm-cov: add Clang's Source-based Code Coverage support > llvm-cov: add Clang's MC/DC support > x86: disable llvm-cov instrumentation > x86: enable llvm-cov support > > Makefile | 9 ++ > arch/Kconfig | 1 + > arch/x86/Kconfig | 2 + > arch/x86/crypto/Makefile | 1 + > arch/x86/kernel/vmlinux.lds.S | 2 + > include/asm-generic/vmlinux.lds.h | 36 +++++ > kernel/Makefile | 1 + > kernel/llvm-cov/Kconfig | 121 ++++++++++++++ > kernel/llvm-cov/Makefile | 8 + > kernel/llvm-cov/fs.c | 253 ++++++++++++++++++++++++++++++ > kernel/llvm-cov/llvm-cov.h | 157 ++++++++++++++++++ > lib/crypto/Makefile | 3 +- > scripts/Makefile.lib | 23 +++ > scripts/mod/modpost.c | 2 + I'm thinking I'm going to NAK this based on the fact that I'm not interested in playing file based games. As long as this thing doesn't honour noinstr I don't want this near x86. And we have kcov support, and gcov and now llvm-cov, surely 3 coverage solutions is like 2 too many?