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 5F5A4CCA476 for ; Tue, 7 Oct 2025 10:16:15 +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=OR1ZNI7xZniIFINBZhpOOwoWD9ICoGcUC1OGrWuFc9Y=; b=CvIUbRgLjyYDPVFaH3z8TxZUm6 iB4oJuuuD/IUhEXBvebXprNymJl4hUgJL4VXjnzcmWDyVz/BUVXuaDuRe4GkUqVuFxf0sC5weO/0x BHLwsTmF1FP1JqRV8ErOBeG6k8kqokp61sgKq11F16Iho3RRGtnr+V1PbknJF8gyAEakZBv6vUDo9 XkI+PH53uQ1CPg2GcOOAR/sGr68p4WeI0jNA+qJXC1buOEcMS9dnRxn6Sgf1Hx6OoSkoDTSjzQuC9 toqeogZR7cldTbs0sMEppLgTEJyjQ5V1TCD/SKEW9WonyVDuTitasu9miMQdAi3DFycsEK5sYBioZ pVluBTyw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v64jo-00000001mky-3cgF; Tue, 07 Oct 2025 10:16:08 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1v64jo-00000001mkm-1lWA for linux-arm-kernel@lists.infradead.org; Tue, 07 Oct 2025 10:16:08 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id D597D601DC; Tue, 7 Oct 2025 10:16:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DCDDC4CEF1; Tue, 7 Oct 2025 10:16:05 +0000 (UTC) Date: Tue, 7 Oct 2025 11:16:03 +0100 From: Catalin Marinas To: Lorenzo Pieralisi Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sascha Bischoff , Will Deacon , Thomas Gleixner , Mark Rutland , Marc Zyngier Subject: Re: [PATCH] irqchip/gic-v5: Fix GIC CDEOI instruction encoding Message-ID: References: <20251006100758.624934-1-lpieralisi@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Oct 07, 2025 at 10:58:12AM +0200, Lorenzo Pieralisi wrote: > On Mon, Oct 06, 2025 at 04:24:18PM +0100, Catalin Marinas wrote: > > On Mon, Oct 06, 2025 at 05:00:56PM +0200, Lorenzo Pieralisi wrote: > > > My only remark there is that even as the code in mainline stands with > > > GCC, it is not very clear that we rely on implicit XZR generation to > > > make sure the instruction encoding generated is correct - it looks > > > like a bit of a stretch to reuse a sysreg write with immediate value == 0 > > > to generate a system instruction write with Rt == 0b11111, it works > > > but it is a bit opaque or at least not straighforward to grok. > > > > > > Obviously the patch below improves LLVM code generation too in the process. > > > > > > I don't know what's best - I admit I am on the fence on this one. > > > > My concern is other cases where we may rely on this, so we might as well > > go with a generic approach than fixing each case individually. If that's > > the only case, I'll leave it to you and Marc do decide whichever you > > prefer. > > I will take your patch - added comments and rewrote the log for v2, with > your Suggested-by (did not give you authorship let me know if that's OK > please). That's absolutely fine. > One thing to mention, I added a Fixes: tag that goes back to the initial > GICv5 commit, I don't know whether it is fixing more than that, it does > not look like by a quick grep through kernel code but I am not sure. This would do. If we find other problems, we'll backport it. -- Catalin