From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9B74D48E0C6 for ; Thu, 1 Oct 2026 07:27:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790839662; cv=none; b=WGaZFMMsLgxZxLRAVKRcXpjef/ymwLILTfceKExvhqw57FLZ2Fiwk0/YuMoTpT1HCdf/7Z0nUXwoci4qAg6igoUtrin9pLQ44ILpVRGruGaeOvwKfQ6pMMoIjYmd4NDv8A6ROSkZGpGXrBJtpzQNnh2aZ7jYH7CM2eJv/P4ok8Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790839662; c=relaxed/simple; bh=SmobSyFddogGFeY7M2R8q3FfXAqnnVco+qzB3Pyn1So=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J+NAnMzMNCxZ8HXiN70DGut6f/3MA/7ZWkNxpo35zYBF/EMlahQi9zUaOh+yVQKhvjRM1P7OJ4ZjF8z2CaexV4fz1jmVjxrXJ67G47ifQeF0xn9CML/z3M7t4MmxHc1N/UFHGeRd1yPd05IaWyVn6Occ+U6ix6yDz+mvA2HbiRw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P2/aphZq; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P2/aphZq" 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 Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Ard Biesheuvel , Ada Couprie Diaz , David Hildenbrand , Catalin Marinas , Vladimir Murzin , Mark Rutland , Mostafa Saleh , Lorenzo Stoakes , Oliver Upton , Marc Zyngier 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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