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 0CEBFC5320E for ; Thu, 22 Aug 2024 09:00:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=EFPwMWbZsxk21i+em6o1+8x08KObu0/8/gmBjEg4W5I=; b=Ag9+Ehv/0TAdvifLE2blLaQd0p nLduuwETHXWUK1ZU0Yd7dJtA3w3/tPVGJUArt8bQA8MzBLZTL4AXNR6+7t4yZuNEg6giFTa0t76l3 JiTBbKayt+7all53PFxx6mpPMuuQhfrL98ontSfZTd3Ee5j5G9y2vktaN+U8ADyuaJifgEycZc/W7 ahuJTYdBT8uSOrCIkDTDspOYY+RO3Wpkj6wkLXu6LtyWaPZSGzvLpD1YyJlQpzhWz4PjZtwqmvcLi BEG9iKPDC4bXYM6JfOmsyo0eQQoLHaNdF3gtVl9zYEjpXLaJ4v62y8ksuP/CPHOuU3pX570pjcQL4 dahtCjDQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sh3fb-0000000C9Fd-1S5T; Thu, 22 Aug 2024 08:59:51 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sh3er-0000000C94t-1jLa; Thu, 22 Aug 2024 08:59:06 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 1E17E60FE8; Thu, 22 Aug 2024 08:59:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35801C4AF0B; Thu, 22 Aug 2024 08:58:58 +0000 (UTC) Date: Thu, 22 Aug 2024 09:58:55 +0100 From: Catalin Marinas To: Mark Brown Cc: Will Deacon , Jonathan Corbet , Andrew Morton , Marc Zyngier , Oliver Upton , James Morse , Suzuki K Poulose , Arnd Bergmann , Oleg Nesterov , Eric Biederman , Shuah Khan , "Rick P. Edgecombe" , Deepak Gupta , Ard Biesheuvel , Szabolcs Nagy , Kees Cook , "H.J. Lu" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Florian Weimer , Christian Brauner , Thiago Jung Bauermann , Ross Burton , Yury Khrustalev , Wilco Dijkstra , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v11 05/39] arm64: Document boot requirements for Guarded Control Stacks Message-ID: References: <20240822-arm64-gcs-v11-0-41b81947ecb5@kernel.org> <20240822-arm64-gcs-v11-5-41b81947ecb5@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240822-arm64-gcs-v11-5-41b81947ecb5@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240822_015905_538581_5EDA5438 X-CRM114-Status: GOOD ( 12.20 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Aug 22, 2024 at 02:15:08AM +0100, Mark Brown wrote: > FEAT_GCS introduces a number of new system registers, we require that > access to these registers is not trapped when we identify that the feature > is present. There is also a HCRX_EL2 control to make GCS operations > functional. > > Since if GCS is enabled any function call instruction will cause a fault > we also require that the feature be specifically disabled, existing > kernels implicitly have this requirement and especially given that the > MMU must be disabled it is difficult to see a situation where leaving > GCS enabled would be reasonable. > > Reviewed-by: Thiago Jung Bauermann > Signed-off-by: Mark Brown Reviewed-by: Catalin Marinas