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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=BAYES_00,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C37CAC433E0 for ; Mon, 22 Feb 2021 10:49:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E9BF64D99 for ; Mon, 22 Feb 2021 10:49:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230189AbhBVKtY (ORCPT ); Mon, 22 Feb 2021 05:49:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:60712 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230430AbhBVKs5 (ORCPT ); Mon, 22 Feb 2021 05:48:57 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D29BC64D99; Mon, 22 Feb 2021 10:48:14 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1lE8l9-00FIdq-QM; Mon, 22 Feb 2021 10:48:12 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 22 Feb 2021 10:48:11 +0000 From: Marc Zyngier To: Mark Rutland Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, james.morse@arm.com, marcan@marcan.st, tglx@linutronix.de, will@kernel.org Subject: Re: [PATCH 5/8] arm64: irq: add a default handle_irq panic function In-Reply-To: <20210222095913.GA70951@C02TD0UTHF1T.local> References: <20210219113904.41736-1-mark.rutland@arm.com> <20210219113904.41736-6-mark.rutland@arm.com> <20210222095913.GA70951@C02TD0UTHF1T.local> User-Agent: Roundcube Webmail/1.4.11 Message-ID: <1d2c27d72b9b2cbdb83d25165a20559a@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, james.morse@arm.com, marcan@marcan.st, tglx@linutronix.de, will@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-kernel@vger.kernel.org On 2021-02-22 09:59, Mark Rutland wrote: > On Fri, Feb 19, 2021 at 11:39:01AM +0000, Mark Rutland wrote: >> If we accidentally unmask IRQs before we've registered an IRQ >> controller, handle_arch_irq will be NULL, and the IRQ exception >> handler >> will branch to a bogus address. >> >> To make this easier to debug, this patch initialises handle_arch_irq >> to >> a default handler which will panic(), making such problems easier to >> debug. When we add support for FIQ handlers, we can follow the same >> approach. > >> -void (*handle_arch_irq)(struct pt_regs *) __ro_after_init; >> +void default_handle_irq(struct pt_regs *regs) >> +{ >> + panic("IRQ taken without a registered IRQ controller\n"); >> +} > > The kbuild test robot pointed out that this should be static (likewise > with default_handle_fiq in patch 8), since it's only used within this > file, so I've updated that in my branch. > > Mark. > >> + >> +void (*handle_arch_irq)(struct pt_regs *) __ro_after_init = >> default_handle_irq; >> >> int __init set_handle_irq(void (*handle_irq)(struct pt_regs *)) >> { >> - if (handle_arch_irq) >> + if (handle_arch_irq != default_handle_irq) >> return -EBUSY; >> >> handle_arch_irq = handle_irq; >> @@ -87,7 +92,7 @@ void __init init_IRQ(void) >> init_irq_stacks(); >> init_irq_scs(); >> irqchip_init(); >> - if (!handle_arch_irq) >> + if (handle_arch_irq == default_handle_irq) >> panic("No interrupt controller found."); It also seems odd to have both default_handle_irq() that panics, and init_IRQ that panics as well. Not a big deal, but maybe we should just drop this altogether and get the firework on the first interrupt. Thanks, M. -- Jazz is not dead. It just smells funny...