From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by sourceware.org (Postfix) with ESMTPS id 1046F3858C27 for ; Tue, 5 Apr 2022 14:05:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 1046F3858C27 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: sourceware.org; spf=none smtp.mailfrom=infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=jJ72nyQjgyMortAHdvw06/vFEylkSYuiFVuOxXrhPF4=; b=SwqA6RhnQVGyo1EdkB/Yf6mm02 Dl5JtcMTBnIo1saXpfrgbyE/JGZcRsHcp3NLkoWMe5//d3yTDV4wxHJK11pA2rmaZH3TltzAh7fBb XY5ctXudO1Aje6BGJCcBm0qhxr3+SocKS+h5rCtfnw9q15J3zakCAN4hvr/ZpcGT4+AjO9QioIGNn bpzyDFsBioroiBC3Em3r/UCGE5vRMoyK7fZe1MLCHbskQpxFP76afxNXjSE7JhFtksghvu4si2d1s 2how848sOs3fzXvTv6gxg+WmiLi8GH1y62pqjHtm/M3icwJ0jG8PmR6ZytAPKMB37cSF4HklVQ14q zM5YH+Mw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1nbjoD-001sCl-Ae; Tue, 05 Apr 2022 14:05:26 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id BD2953001EA; Tue, 5 Apr 2022 16:05:22 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9951B2DC78FE1; Tue, 5 Apr 2022 16:05:22 +0200 (CEST) Date: Tue, 5 Apr 2022 16:05:22 +0200 From: Peter Zijlstra To: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, gcc@gcc.gnu.org, catalin.marinas@arm.com, will@kernel.org, marcan@marcan.st, maz@kernel.org, szabolcs.nagy@arm.com, f.fainelli@gmail.com, opendmb@gmail.com, Andrew Pinski , Ard Biesheuvel , x86@kernel.org, andrew.cooper3@citrix.com, Jeremy Linton Subject: Re: GCC 12 miscompilation of volatile asm (was: Re: [PATCH] arm64/io: Remind compiler that there is a memory side effect) Message-ID: References: <20220401164406.61583-1-jeremy.linton@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.3 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, KAM_SHORT, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 05 Apr 2022 14:05:40 -0000 On Tue, Apr 05, 2022 at 01:51:30PM +0100, Mark Rutland wrote: > Hi all, > > [adding kernel folk who work on asm stuff] > > As a heads-up, GCC 12 (not yet released) appears to erroneously optimize away > calls to functions with volatile asm. Szabolcs has raised an issue on the GCC > bugzilla: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105160 > > ... which is a P1 release blocker, and is currently being investigated. > > Jemery originally reported this as an issue with {readl,writel}_relaxed(), but > the underlying problem doesn't have anything to do with those specifically. > > I'm dumping a bunch of info here largely for posterity / archival, and to find > out who (from the kernel side) is willing and able to test proposed compiler > fixes, once those are available. > > I'm happy to do so for aarch64; Peter, I assume you'd be happy to look at the > x86 side? Sure..