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 253FAC52D7C for ; Wed, 21 Aug 2024 18:19:10 +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=1CyJAdp+d/mRC7D27VN913Xs7RT0t8+cXk+D0gFMdbc=; b=4028AYBEDQS1QEqCtRzgvlJS5u 5C0mvZ78dTZ86pbIlcNu0ho1jcJW2iUpm7bdZd+7TqtJA4ej8F0m10URmZ+x5ncg7wukTJizcxTHH 786VqPf4zI6HHw1ATzLZkTKUIyOsiDqCESIxTtJwfYtk1xb0uD+ZChVeXNEU0QRmn5cuaAVD2EQMr B/pRCCLqDdPc0akC7CiBTtoFMK61TyIKYMteZgqftcvh5BjVwUN1Ocqgm15QqeZHXluC1Gj/f3NUm j+rvBKZzpAUjZiRH/pTBv+NSG+60F9ZQ22FsZL2RopVKJFlyjWs+WSob61eZ9prYke1X41oMKBEWv nSPGtSOg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sgpvA-0000000A2vS-1WL2; Wed, 21 Aug 2024 18:19:00 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sgpuQ-0000000A2n8-3jjx; Wed, 21 Aug 2024 18:18:16 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 5472360C39; Wed, 21 Aug 2024 18:18:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C128C32781; Wed, 21 Aug 2024 18:18:08 +0000 (UTC) Date: Wed, 21 Aug 2024 19:18:06 +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 , 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 v10 23/40] arm64/signal: Set up and restore the GCS context for signal handlers Message-ID: References: <20240801-arm64-gcs-v10-0-699e2bd2190b@kernel.org> <20240801-arm64-gcs-v10-23-699e2bd2190b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240821_111814_990478_A1CD55A2 X-CRM114-Status: GOOD ( 17.10 ) 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 Wed, Aug 21, 2024 at 07:03:13PM +0100, Mark Brown wrote: > On Wed, Aug 21, 2024 at 06:28:49PM +0100, Catalin Marinas wrote: > > On Thu, Aug 01, 2024 at 01:06:50PM +0100, Mark Brown wrote: > > > + /* > > > + * Push a cap and the GCS entry for the trampoline onto the GCS. > > > + */ > > > + put_user_gcs((unsigned long)sigtramp, gcspr_el0 - 2, &ret); > > > + put_user_gcs(GCS_SIGNAL_CAP(gcspr_el0 - 1), gcspr_el0 - 1, &ret); > > > + if (ret != 0) > > > + return ret; > > > Doesn't the second put_user_gcs() override the previous ret? > > No, we only set ret on error - if the first one faults it'll set ret > then the second one will either leave it unchanged or write the same > error code depending on if it fails. This idiom is used quite a lot in > the signal code. You are right, I missed that it's called 'err' in put_user_gcs(), thought it's overridden. -- Catalin