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 9B820C433EF for ; Mon, 11 Apr 2022 10:41:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=LuvALv/n7CyBhdNqYvPN6q6xhZanqwyn67QbrSmlVl0=; b=IyvAhqeMA5TOsq j+VsdAIAi8rtmGdWRXXfq2mUMbEB/SqaoWAqBQNKyuwOMi/C26yLNE6lNba47gdR8sNEvweUnn90C 8RORcHqwxEUadGjNeQ3+dysmnZQ2OakFCY0ncptx5rQtxVNW2e80MERU7/2WgrknNQy88tBctR2iE WZFsYTY9s/uOKRld+rSXYNR75aN7az6f8g6Hc6waujBaUEhu3vW5olZVXETSNdClpAK+Xs3ZSJrMB UhUULsP9qoLiHPW78EbKJVpJ23s+Vp+5+Rdu5PDt4cphrB0B4YRBRDaP1ERVaDeS0pH7j5AQ6nUso k1h5oxP2uNpj7GbMaCIA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ndrTP-008QPs-Fp; Mon, 11 Apr 2022 10:40:44 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ndrKU-008M7o-82 for linux-arm-kernel@lists.infradead.org; Mon, 11 Apr 2022 10:31:31 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3E230169C; Mon, 11 Apr 2022 03:31:29 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.9.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 974393F5A1; Mon, 11 Apr 2022 03:31:26 -0700 (PDT) Date: Mon, 11 Apr 2022 11:31:24 +0100 From: Mark Rutland To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jeremy Linton Cc: 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 , Peter Zijlstra , x86@kernel.org, andrew.cooper3@citrix.com 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-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220411_033130_369539_C90D0995 X-CRM114-Status: GOOD ( 11.07 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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. Jan Hubicka fixed this in GCC commit: aabb9a261ef060cf ("Propagate nondeterministic and side_effects flags in modref summary after inlining") ... and all my local tests look good with that applied. Compiler explorer's trunk build now has that fix, so the examples from before now look good: aarch64: https://godbolt.org/z/vMczqjYvs x86_64: https://godbolt.org/z/cveff9hq5 Jeremy, now that the real issue has been identified and fixed, I assume you'll send a revert for commit: 8d3ea3d402db94b6 ("net: bcmgenet: Use stronger register read/writes to assure ordering") ... ? Thanks, Mark. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel