From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 003.mia.mailroute.net (003.mia.mailroute.net [199.89.3.6]) (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 0E5D0314A62; Thu, 18 Sep 2025 16:04:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.3.6 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758211452; cv=none; b=Il9QWpas0opsMNgnmb6D5FyB1mHH3CPUuEarokZXOB/7dOOPhxbaNRXDmWvc0l/nSYqIHy+Zn+4FBAIY3LqUc26iafRmowjlTxeFB5AX30rRuOptFdXf/YBfSACu02GNUNjARAFOg8nXz8GZNXLM/ZG7hazxZfiqjTtUOv3I3ro= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758211452; c=relaxed/simple; bh=3LE35nZGZq8MyMAMqGFXGW2TSB7AmNx1a4aDe+qCZPU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Yx/BqS4a3nqufeBCoPbtCI6602xVlH3cPMcRGyxiHV0suKtumXreyfcb1b52+Yg2E77Z5Y6xXH/a5mxF7rGIucqd3NXeFffoxwKkR3p7J0HdyfWcao0/5thJ73AQ5SaVe/W4AnoqBYujYu9eH+YIFPbyxNWTBboEDhYEV8jCO9c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=Mf0M1J8U; arc=none smtp.client-ip=199.89.3.6 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="Mf0M1J8U" Received: from localhost (localhost [127.0.0.1]) by 003.mia.mailroute.net (Postfix) with ESMTP id 4cSL6c3snqzlgn8k; Thu, 18 Sep 2025 16:04:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:content-type:content-type:in-reply-to :from:from:content-language:references:subject:subject :user-agent:mime-version:date:date:message-id:received:received; s=mr01; t=1758211439; x=1760803440; bh=4wzWm6RSRc1tNocFJFpFoox7 GYZLGguM76hcy5QnMFw=; b=Mf0M1J8U6wTLeu2gHoc5SUiGtJ7IvGYk8UZ6fQtQ F2HzXxFsv2wJKVo3E3itBcK5M7HBPy7vs16rMQdZNtkdtlpHUdAB6gp5zElM1tQv X44SkYoj7S3blZaRVlzHiogKzJP7RsYrM9zFM9RqFriOFHgBvgFNCVmVWHjXbnfj BCNxjhZ/nIKCSqWA5KRGlBXCj8ouY534Wu4SFzXm9YsWLm1w6mkQLx3XVjEv5N0J qYICjPTqTk8g9G9tSYHje0mRJLCaVRl0Qo98o58MrF9E6yTEcWnwOiMsYBacC9iZ WV8PxWTT8jpLUWJ3lpx2TSzx7JNYmCOfRmR8oXeNulu1CA== X-Virus-Scanned: by MailRoute Received: from 003.mia.mailroute.net ([127.0.0.1]) by localhost (003.mia [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id 6L6n7UbPW0mK; Thu, 18 Sep 2025 16:03:59 +0000 (UTC) Received: from [100.66.154.22] (unknown [104.135.204.82]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 003.mia.mailroute.net (Postfix) with ESMTPSA id 4cSL5g10BTzltKG9; Thu, 18 Sep 2025 16:03:18 +0000 (UTC) Message-ID: <1ca90ba0-7bdc-43d1-af12-bba73dd3234a@acm.org> Date: Thu, 18 Sep 2025 09:03:17 -0700 Precedence: bulk X-Mailing-List: linux-sparse@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 02/35] compiler-capability-analysis: Add infrastructure for Clang's capability analysis To: Ian Rogers , Marco Elver Cc: Peter Zijlstra , Boqun Feng , Ingo Molnar , Will Deacon , "David S. Miller" , Luc Van Oostenryck , "Paul E. McKenney" , Alexander Potapenko , Arnd Bergmann , Bill Wendling , Christoph Hellwig , Dmitry Vyukov , Eric Dumazet , Frederic Weisbecker , Greg Kroah-Hartman , Herbert Xu , Jann Horn , Joel Fernandes , Jonathan Corbet , Josh Triplett , Justin Stitt , Kees Cook , Kentaro Takeda , Lukas Bulwahn , Mark Rutland , Mathieu Desnoyers , Miguel Ojeda , Nathan Chancellor , Neeraj Upadhyay , Nick Desaulniers , Steven Rostedt , Tetsuo Handa , Thomas Gleixner , Thomas Graf , Uladzislau Rezki , Waiman Long , kasan-dev@googlegroups.com, linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-sparse@vger.kernel.org, llvm@lists.linux.dev, rcu@vger.kernel.org, Steven Rostedt References: <20250918140451.1289454-1-elver@google.com> <20250918140451.1289454-3-elver@google.com> Content-Language: en-US From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable On 9/18/25 8:58 AM, Ian Rogers wrote: > On Thu, Sep 18, 2025 at 7:05=E2=80=AFAM Marco Elver = wrote: >> +config WARN_CAPABILITY_ANALYSIS >> + bool "Compiler capability-analysis warnings" >> + depends on CC_IS_CLANG && CLANG_VERSION >=3D 220000 >> + # Branch profiling re-defines "if", which messes with the comp= iler's >> + # ability to analyze __cond_acquires(..), resulting in false p= ositives. >> + depends on !TRACE_BRANCH_PROFILING >=20 > Err, wow! What and huh, and why? Crikes. I'm amazed you found such an > option exists. I must be very naive to have never heard of it and now > I wonder if it is needed and load bearing? (+Steven) This is an old option. I think this commit introduced it: commit 52f232cb720a7babb752849cbc2cab2d24021209 Author: Steven Rostedt Date: Wed Nov 12 00:14:40 2008 -0500 tracing: likely/unlikely branch annotation tracer Bart.