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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 C4870C433C1 for ; Wed, 24 Mar 2021 10:15:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 91C2D619E4 for ; Wed, 24 Mar 2021 10:15:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230445AbhCXKO5 (ORCPT ); Wed, 24 Mar 2021 06:14:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:41356 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230513AbhCXKOu (ORCPT ); Wed, 24 Mar 2021 06:14:50 -0400 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 6DFDE619FD; Wed, 24 Mar 2021 10:14:50 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lP0XI-003Uqv-B9; Wed, 24 Mar 2021 10:14:48 +0000 Date: Wed, 24 Mar 2021 10:14:47 +0000 Message-ID: <87czvokgdk.wl-maz@kernel.org> From: Marc Zyngier To: Nick Desaulniers Cc: Arnd Bergmann , Thomas Gleixner , Nathan Chancellor , Arnd Bergmann , LKML , clang-built-linux Subject: Re: [PATCH] irqchip/gic-v3: fix OF_BAD_ADDR error handling In-Reply-To: References: <20210323131842.2773094-1-arnd@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: ndesaulniers@google.com, arnd@kernel.org, tglx@linutronix.de, nathan@kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com 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 Tue, 23 Mar 2021 22:06:22 +0000, Nick Desaulniers wrote: > > On Tue, Mar 23, 2021 at 6:18 AM Arnd Bergmann wrote: > > > > From: Arnd Bergmann > > > > When building with extra warnings enabled, clang points out a > > mistake in the error handling: > > > > drivers/irqchip/irq-gic-v3-mbi.c:306:21: error: result of comparison of constant 18446744073709551615 with expression of type 'phys_addr_t' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare] > > Looks like based on CONFIG_PHYS_ADDR_T_64BIT, phys_addr_t can be u64 > or u32, but of_translate_address always returns a u64. This is fine > for the current value of OF_BAD_ADDR, but I think there's a risk of > losing the top 32b of the return value of of_translate_address() here? If the DT describes a 64bit physical address, and that the (32bit) kernel isn't built to grok these addresses, then I'd say that the kernel cannot run on this HW, and that we don't need to worry much about this case. In general, CONFIG_PHYS_ADDR_T_64BIT must be selected by the arch code if anything above 32bit can be described in the PA space. Thanks, M. -- Without deviation from the norm, progress is not possible.