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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9974EB64DD for ; Mon, 7 Aug 2023 10:48:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229785AbjHGKsp (ORCPT ); Mon, 7 Aug 2023 06:48:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229934AbjHGKso (ORCPT ); Mon, 7 Aug 2023 06:48:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FC4419B0; Mon, 7 Aug 2023 03:47:54 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A6D16617A0; Mon, 7 Aug 2023 10:47:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3C07C433C7; Mon, 7 Aug 2023 10:47:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691405227; bh=UAackwL7UM7HgpYl/6xaBi50e0epZnNRDwJYOlZupq4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XTR4HktOiAPHWP3h5fhk2wD4UGXcszx/1wmiz0cTUw4hgJdMG/oBFXfBL5g8PRXDm yLyTKTnw9g7BoWrTvMncRJn8LkXHzRuxipnZVjx0vFvcXrqT4eR86TG5LTl5tNbObo xJQ/FGp3frhFh6/f8dqgOoKdt8ON2EbmmdwfHh1i08coEHUQBuFyz/x83TcE1yqtjt 7TqWEYZDHjUKH3kW5qO6/n6uSTXpZqFvYnjjmhqi5LD4LAJSCsEkKcRIcR2CCWQAgo Gs1ws/3JxfY+LKKLeFt9C8F81JN/6L0Q0raPKMl4v1iHyjfJxQnAsOOrha9B/6u7Tz 9Y1H3yabnBsiw== Received: from disco-boy.misterjones.org ([217.182.43.188] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1qSxlQ-002nFK-Gz; Mon, 07 Aug 2023 11:47:04 +0100 MIME-Version: 1.0 Date: Mon, 07 Aug 2023 11:47:04 +0100 From: Marc Zyngier To: Mark Rutland Cc: Douglas Anderson , Catalin Marinas , Will Deacon , Sumit Garg , Daniel Thompson , linux-perf-users@vger.kernel.org, ito-yuichi@fujitsu.com, Chen-Yu Tsai , Ard Biesheuvel , Stephen Boyd , Peter Zijlstra , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, kgdb-bugreport@lists.sourceforge.net, Masayoshi Mizuma , "Rafael J . Wysocki" , Lecopzer Chen , Wei Li , linux-kernel@vger.kernel.org Subject: Re: [PATCH v9 7/7] arm64: kgdb: Roundup cpus using the debug IPI In-Reply-To: References: <20230601213440.2488667-1-dianders@chromium.org> <20230601143109.v9.7.I2ef26d1b3bfbed2d10a281942b0da7d9854de05e@changeid> User-Agent: Roundcube Webmail/1.4.13 Message-ID: X-Sender: maz@kernel.org Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 217.182.43.188 X-SA-Exim-Rcpt-To: mark.rutland@arm.com, dianders@chromium.org, catalin.marinas@arm.com, will@kernel.org, sumit.garg@linaro.org, daniel.thompson@linaro.org, linux-perf-users@vger.kernel.org, ito-yuichi@fujitsu.com, wens@csie.org, ardb@kernel.org, swboyd@chromium.org, peterz@infradead.org, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, kgdb-bugreport@lists.sourceforge.net, msys.mizuma@gmail.com, rafael.j.wysocki@intel.com, lecopzer.chen@mediatek.com, liwei391@huawei.com, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On 2023-08-07 11:28, Mark Rutland wrote: > On Thu, Jun 01, 2023 at 02:31:51PM -0700, Douglas Anderson wrote: >> From: Sumit Garg >> >> Let's use the debug IPI for rounding up CPUs in kgdb. When the debug >> IPI is backed by an NMI (or pseudo NMI) then this will let us debug >> even hard locked CPUs. When the debug IPI isn't backed by an NMI then >> this won't really have any huge benefit but it will still work. >> >> Signed-off-by: Sumit Garg >> Signed-off-by: Douglas Anderson >> --- >> >> Changes in v9: >> - Remove fallback for when debug IPI isn't available. >> - Renamed "NMI IPI" to "debug IPI" since it might not be backed by >> NMI. >> >> arch/arm64/kernel/ipi_debug.c | 5 +++++ >> arch/arm64/kernel/kgdb.c | 14 ++++++++++++++ >> 2 files changed, 19 insertions(+) > > This looks fine to me, but I'd feel a bit happier if we had separate > SGIs for > the backtrace and the KGDB callback as they're logically unrelated. Well, we're a bit stuck here. We have exactly *one* spare SGI with GICv3, as we lose 8 of them to the secure side. One possibility would be to mux some of the lesser used IPIs onto two SGIs (one with standard priority, and one with NMI priority). M. -- Jazz is not dead. It just smells funny...