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 C491BCA5FCE for ; Thu, 1 Oct 2026 07:27:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject: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=Yn+BNDD3uVIMrlfbHqtIvEfB4qrTW1vWxSV7SfUpzfM=; b=sFXHa7qNShBLJefv/Eb+xbdn/i Whxt/69Q6XEDs69/dtema9+AMm92asz3w0sFKNUGo0O/tqbjxSjaQaqtgNENBc4rdUXj2xkotk+Xc jVU+4UBUUuo79n6BZVdUixDLH9Yc7uYzM2+iDu24q44GaUOyG3RBZheqwdBTlb/Tq02gK44gSJk4G I0+QqmgWLkGCcZ3X1p6zFJ6GOp7uBjG+SFdDOCp3WTK/qda1nNF1j8Q4jyrOylhvQmC6j2hYhcMAW YPPfKyYrYwxADL2Q9fA0VMOKGEkSNXmx+ZUIhFWljkYsy4MJ47JrguDobyeDqp3EHb0uD82+94AQE jcnNAxBw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xCBCT-00000007zgk-0F3i; Thu, 01 Oct 2026 07:27:29 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xCBCR-00000007zgQ-1veX for linux-arm-kernel@lists.infradead.org; Thu, 01 Oct 2026 07:27:27 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 70DC7601FE; Thu, 1 Oct 2026 07:27:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 832F41F000FF; Thu, 1 Oct 2026 07:27:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790839646; bh=Yn+BNDD3uVIMrlfbHqtIvEfB4qrTW1vWxSV7SfUpzfM=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=P2/aphZqkksPSqU/+moRoc+UVy5ITbdkRSYXR5ZLi7chDLk5ojqaffNC1+Nqb/ufg wK0phOBnoqb6kh0AY/49lpEGUnfmoIkmt/PcRo+dN0l9md6pAqftJuAItzVJREdjVA Uvf8uLD7XdycfIQumf51oZf7XgvgQbuDBTwUJc3LFO33Wm6IRxKUyz3Uk/EQb1IUfT OZ2qtE/9XfwYoiohbcGL8TmnWJXszOmhtmZ/QNrkaDnJUkSv9NgOBRIPphSqR9NMMl nIh9aGL9lGEGNXzIc8LOqx1c+HZZm6Nyf4KN4EcbxetPjXj5xwq6ZlNf5GsVpHn+nl 5kLi7X75MKkTw== Date: Thu, 1 Oct 2026 08:27:20 +0100 From: Will Deacon To: Linus Walleij Subject: Re: [PATCH v2 19/21] arm64: entry: The great stack switcheroo Message-ID: References: <20260918161407.2300-1-will@kernel.org> <20260918161407.2300-20-will@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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: , Cc: Mark Rutland , Vladimir Murzin , Arnd Bergmann , Catalin Marinas , linux-kernel@vger.kernel.org, Mostafa Saleh , Marc Zyngier , David Hildenbrand , Lorenzo Stoakes , Oliver Upton , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 30, 2026 at 11:36:35PM +0200, Linus Walleij wrote: > On Fri, Sep 18, 2026 at 6:15 PM Will Deacon wrote: > > > With the kernel stack pointer in SP_EL1 and the overflow stack pointer > > in SP_EL0, it is now straightforward to switch between the two on > > exception entry from EL1 by writing to SPSel. However, since exception > > entry sets PSTATE.SP to 1 (selecting SP_EL1 as the stack pointer), > > repurposing the overflow stack as a more general kernel exception stack > > would require writing to SPSel on every exception entry from the kernel. > > > > Switch things around so that the overflow stack resides in SP_EL1, with > > the kernel stack residing in SP_EL0. > > > > Signed-off-by: Will Deacon > > This patch gives me panic, and as can be seen from the review > comments need some love... Please can you share the panic message? I'll definitely be reworking this based on the review comments, but if there's a bug it would be great to see the details now! Thanks, Will