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 E799BD59F5E for ; Wed, 6 Nov 2024 18:31:58 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4XkDM13HY0z3bgQ; Thu, 7 Nov 2024 05:31:57 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=63.228.1.57 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1730917917; cv=none; b=HOeTN/jtorz8ZSzemtaQJrgLUiF1ajRqrEhCL29s8xnF6zcTQQg6cilHBfvdw9pMupHvWQvBnBIjocTf/1QWdZGKFD1OzrU01nXzuwU85Y4J8YSpleCRTlkqGpyoLKxiNqe6jS5DnQJxhESbtIJNcmruxhMsDje8/kLQ+bHM4pvd339h+S9mAgjs2YJ+6h47HPYy33l6tcyYKcbGXRXbGgovplYHGLiMfl3kKH2s3wrHYdaEW8P/fWXixqv06zMSbYNEX90FfAfYOxHOqMqv0mCyd32GLxbwICDVut8D59z1PVIrCuip3UzHCG2rKIGw3XbywUt8wTHpeB+D6PF8eA== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1730917917; c=relaxed/relaxed; bh=aSEc3taDmu7kdFliJ+Z52GGczaVGmXnK1bD8nq8xhbs=; h=Date:From:To:Cc:Subject:Message-ID:References:Mime-Version: Content-Type:Content-Disposition:In-Reply-To; b=j5RyvO3kZ0wLAV3n1nBMWvQ84NEVutf6CJP8IfU5H+aBq+C5R/Z6R40juwaReMrzL+OjrVVgkUQHgupGehxBNwwVZP8iwE35KYre/vEYNHDbL8AqHdOVN5sKatRofvbH6M+pLzDgugMR9zjplYauCPZ1FZqI0UwtyJrhl4TDK7awR4sc6AL9eOoCqNin0Zycwi2TtG2Qp6cxQ+BlJxHgGaVoilgA+MRBkuGN6sfUSoJ4poRV7r1oscFo6Hx1wvBulNhu0H4kUhnpO8/mTbRfIzm9NPv/cFE1pVb9ZW3hitk4UTr9Kgs9xSVJwjsUpDOgoLCwQs2SE8Qvo9HYcr/l+A== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org; spf=pass (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=segher@kernel.crashing.org; receiver=lists.ozlabs.org) smtp.mailfrom=kernel.crashing.org Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org 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=lists.ozlabs.org) Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lists.ozlabs.org (Postfix) with ESMTP id 4XkDLy3Y9wz3bg1 for ; Thu, 7 Nov 2024 05:31:53 +1100 (AEDT) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 4A6ITW0E024009; Wed, 6 Nov 2024 12:29:32 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 4A6ITVEL024004; Wed, 6 Nov 2024 12:29:31 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Wed, 6 Nov 2024 12:29:31 -0600 From: Segher Boessenkool To: Nathan Chancellor Cc: Christophe Leroy , Michael Ellerman , linuxppc-dev@lists.ozlabs.org, llvm@lists.linux.dev, patches@lists.linux.dev, stable@vger.kernel.org Subject: Re: [PATCH] powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clang Message-ID: <20241106182931.GI29862@gate.crashing.org> References: <20241030-powerpc-vdso-drop-stackp-flags-clang-v1-1-d95e7376d29c@kernel.org> <884cf694-09c7-4082-a6b1-6de987025bf8@csgroup.eu> <20241106133752.GG29862@gate.crashing.org> <20241106152114.GA2738371@thelio-3990X> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241106152114.GA2738371@thelio-3990X> User-Agent: Mutt/1.4.2.3i Hi! On Wed, Nov 06, 2024 at 08:21:14AM -0700, Nathan Chancellor wrote: > > (r2 is the default for -m32, r13 is the default for -m64, it appears > > that clang does not implement this option at all, it simply checks if > > you set the default, and explodes if not). > > Not sure that I would say it has not been implemented correctly, more > that it has not been implemented in the same manner as GCC. Keith chose > not to open up support for arbitrary registers to keep the > implementation of this option in LLVM simple: LLVM claims to be compatible to GCC. It is not. This is a bug. As it is, LLVM can not be used to compile the PowerPC kernel. These flags (-mstack-protector-guard-{reg,offset}=) are there *specifically* so that the user can choose to use something different from the default. I added this (back in 2017) because the kernel needed it. Some other GCC ports (aarch64, arm, riscv, x86) have followed suit since then, btw. Segher