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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 044ECC43334 for ; Sun, 17 Jul 2022 21:01:54 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LmHb52Wl3z3cdv for ; Mon, 18 Jul 2022 07:01:53 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4LmHZf3sbPz2yT0 for ; Mon, 18 Jul 2022 07:01:29 +1000 (AEST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 26HKuGbt017693; Sun, 17 Jul 2022 15:56:16 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 26HKuFnK017690; Sun, 17 Jul 2022 15:56:15 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Sun, 17 Jul 2022 15:56:15 -0500 From: Segher Boessenkool To: Linus Torvalds Subject: Re: mainline build failure of powerpc allmodconfig for prom_init_check Message-ID: <20220717205615.GC25951@gate.crashing.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , linux-kernel , Paul Mackerras , linux-hardening@vger.kernel.org, linuxppc-dev , Sudip Mukherjee Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Jul 17, 2022 at 01:29:07PM -0700, Linus Torvalds wrote: > On Sun, Jul 17, 2022 at 1:25 PM Sudip Mukherjee > wrote: > > > > And the generated assembly still has the memset for "struct prom_args". > > Strange. That smells like a compiler bug to me. > > But I can't read powerpc assembly code - it's been too many years, and > even back when I did read it I hated how the register "names" worked. > > Maybe it was never the args array, and it was about the other fields. > Not that that makes any sense either, but it makes more sense than the > compiler turning a series of volatile accesses into a memset. Calling mem* on a volatile object (or a struct containing one) is not valid. I opened gcc.gnu.org/PR106335. Thanks for bringing this up! Segher