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=-8.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 4A69AC433E3 for ; Thu, 27 Aug 2020 14:29:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D9522177B for ; Thu, 27 Aug 2020 14:29:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728050AbgH0O3Y (ORCPT ); Thu, 27 Aug 2020 10:29:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:52034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728029AbgH0OVh (ORCPT ); Thu, 27 Aug 2020 10:21:37 -0400 Received: from gaia (unknown [46.69.195.127]) (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 24FEC2177B; Thu, 27 Aug 2020 14:21:33 +0000 (UTC) Date: Thu, 27 Aug 2020 15:21:31 +0100 From: Catalin Marinas To: Andrey Konovalov Cc: Vincenzo Frascino , Dmitry Vyukov , kasan-dev , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Elena Petrova , Branislav Rankov , Kevin Brodsky , Will Deacon , Andrew Morton , Linux ARM , Linux Memory Management List , LKML Subject: Re: [PATCH 32/35] kasan, arm64: print report from tag fault handler Message-ID: <20200827142131.GN29264@gaia> References: <4691d6019ef00c11007787f5190841b47ba576c4.1597425745.git.andreyknvl@google.com> <20200827104816.GI29264@gaia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 27, 2020 at 02:34:31PM +0200, Andrey Konovalov wrote: > On Thu, Aug 27, 2020 at 12:48 PM Catalin Marinas > wrote: > > On Fri, Aug 14, 2020 at 07:27:14PM +0200, Andrey Konovalov wrote: > > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > > > index c62c8ba85c0e..cf00b3942564 100644 > > > --- a/arch/arm64/mm/fault.c > > > +++ b/arch/arm64/mm/fault.c > > > @@ -14,6 +14,7 @@ > > > #include > > > #include > > > #include > > > +#include > > > #include > > > #include > > > #include > > > @@ -314,11 +315,19 @@ static void report_tag_fault(unsigned long addr, unsigned int esr, > > > { > > > bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0; > > > > > > +#ifdef CONFIG_KASAN_HW_TAGS > > > + /* > > > + * SAS bits aren't set for all faults reported in EL1, so we can't > > > + * find out access size. > > > + */ > > > + kasan_report(addr, 0, is_write, regs->pc); > > > +#else > > > pr_alert("Memory Tagging Extension Fault in %pS\n", (void *)regs->pc); > > > pr_alert(" %s at address %lx\n", is_write ? "Write" : "Read", addr); > > > pr_alert(" Pointer tag: [%02x], memory tag: [%02x]\n", > > > mte_get_ptr_tag(addr), > > > mte_get_mem_tag((void *)addr)); > > > +#endif > > > } > > > > More dead code. So what's the point of keeping the pr_alert() introduced > > earlier? CONFIG_KASAN_HW_TAGS is always on for in-kernel MTE. If MTE is > > disabled, this function isn't called anyway. > > I was considering that we can enable in-kernel MTE without enabling > CONFIG_KASAN_HW_TAGS, but perhaps this isn't what we want. I'll drop > this part in v2, but then we also need to make sure that in-kernel MTE > is only enabled when CONFIG_KASAN_HW_TAGS is enabled. Do we need more > ifdefs in arm64 patches when we write to MTE-related registers, or > does this work as is? I think the in-kernel MTE for the time being should only mean CONFIG_KASAN_HW_TAGS, with a dependency on CONFIG_MTE. KASAN carries some additional debugging features but if we can trim it down, we may not need a separate in-kernel MTE option for production systems (maybe a CONFIG_KASAN_HW_TAGS_LITE). -- Catalin