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=-8.2 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 735DCC4741F for ; Thu, 5 Nov 2020 17:30:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 020432083B for ; Thu, 5 Nov 2020 17:30:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731560AbgKERal (ORCPT ); Thu, 5 Nov 2020 12:30:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:60582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725862AbgKERal (ORCPT ); Thu, 5 Nov 2020 12:30:41 -0500 Received: from gaia (unknown [2.26.170.190]) (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 5C3DF206B6; Thu, 5 Nov 2020 17:30:37 +0000 (UTC) Date: Thu, 5 Nov 2020 17:30:34 +0000 From: Catalin Marinas To: Andrey Konovalov Cc: Will Deacon , Vincenzo Frascino , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , Andrew Morton , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 32/43] arm64: mte: Switch GCR_EL1 in kernel entry and exit Message-ID: <20201105173033.GF30030@gaia> References: <5d9ece04df8e9d60e347a2f6f96b8c52316bfe66.1604531793.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5d9ece04df8e9d60e347a2f6f96b8c52316bfe66.1604531793.git.andreyknvl@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 05, 2020 at 12:18:47AM +0100, Andrey Konovalov wrote: > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > index 14b0c19a33e3..cc7e0f8707f7 100644 > --- a/arch/arm64/kernel/mte.c > +++ b/arch/arm64/kernel/mte.c > @@ -23,6 +23,8 @@ > #include > #include > > +u64 gcr_kernel_excl __ro_after_init; > + > static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) > { > pte_t old_pte = READ_ONCE(*ptep); > @@ -123,6 +125,23 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag) > > void __init mte_init_tags(u64 max_tag) > { > + static bool gcr_kernel_excl_initialized = false; > + > + if (!gcr_kernel_excl_initialized) { > + /* > + * The format of the tags in KASAN is 0xFF and in MTE is 0xF. > + * This conversion extracts an MTE tag from a KASAN tag. > + */ > + u64 incl = GENMASK(FIELD_GET(MTE_TAG_MASK >> MTE_TAG_SHIFT, > + max_tag), 0); > + > + gcr_kernel_excl = ~incl & SYS_GCR_EL1_EXCL_MASK; > + gcr_kernel_excl_initialized = true; > + } > + > + /* Enable the kernel exclude mask for random tags generation. */ > + write_sysreg_s(SYS_GCR_EL1_RRND | gcr_kernel_excl, SYS_GCR_EL1); Same question as on a previous patch. Is SYS_GCR_EL1 written on the other registers via cpu_enable_mte()? -- Catalin