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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBImb-0000qo-49; Thu, 27 Aug 2020 14:21:41 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kBImY-0000q6-4R for linux-arm-kernel@lists.infradead.org; Thu, 27 Aug 2020 14:21:38 +0000 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 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-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200827_102138_293110_265D44BD X-CRM114-Status: GOOD ( 22.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Linux ARM , Marco Elver , Elena Petrova , Kevin Brodsky , Will Deacon , Branislav Rankov , kasan-dev , LKML , Linux Memory Management List , Alexander Potapenko , Evgenii Stepanov , Andrey Ryabinin , Andrew Morton , Vincenzo Frascino , Dmitry Vyukov Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel