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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 71727C43461 for ; Tue, 8 Sep 2020 15:16:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C3A0E223FB for ; Tue, 8 Sep 2020 15:16:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3A0E223FB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3A6F06B0055; Tue, 8 Sep 2020 11:16:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 32FF06B005A; Tue, 8 Sep 2020 11:16:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1D0406B005C; Tue, 8 Sep 2020 11:16:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0183.hostedemail.com [216.40.44.183]) by kanga.kvack.org (Postfix) with ESMTP id 048BE6B0055 for ; Tue, 8 Sep 2020 11:16:29 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id B7D902490 for ; Tue, 8 Sep 2020 15:16:29 +0000 (UTC) X-FDA: 77240245698.24.bikes44_5f03dec270d5 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id 850011A4AA for ; Tue, 8 Sep 2020 15:16:29 +0000 (UTC) X-HE-Tag: bikes44_5f03dec270d5 X-Filterd-Recvd-Size: 2865 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf40.hostedemail.com (Postfix) with ESMTP for ; Tue, 8 Sep 2020 15:16:28 +0000 (UTC) Received: from gaia (unknown [46.69.195.48]) (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 98CA822404; Tue, 8 Sep 2020 15:16:25 +0000 (UTC) Date: Tue, 8 Sep 2020 16:16:23 +0100 From: Catalin Marinas To: Andrey Konovalov Cc: Dmitry Vyukov , Vincenzo Frascino , 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 24/35] arm64: mte: Switch GCR_EL1 in kernel entry and exit Message-ID: <20200908151622.GJ25591@gaia> References: <20200827103819.GE29264@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) X-Rspamd-Queue-Id: 850011A4AA X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Sep 08, 2020 at 03:58:07PM +0200, Andrey Konovalov wrote: > On Thu, Aug 27, 2020 at 12:38 PM Catalin Marinas > wrote: > > > > On Fri, Aug 14, 2020 at 07:27:06PM +0200, Andrey Konovalov wrote: > > > @@ -957,6 +984,7 @@ SYM_FUNC_START(cpu_switch_to) > > > mov sp, x9 > > > msr sp_el0, x1 > > > ptrauth_keys_install_kernel x1, x8, x9, x10 > > > + mte_restore_gcr 1, x1, x8, x9 > > > scs_save x0, x8 > > > scs_load x1, x8 > > > ret > > > > Since we set GCR_EL1 on exception entry and return, why is this needed? > > We don't have a per-kernel thread GCR_EL1, it's global to all threads, > > so I think cpu_switch_to() should not be touched. > > Dropping this line from the diff leads to many false-positives... I'll > leave this to Vincenzo. I wouldn't expect this to have any effect but maybe the mte_thread_switch() code still touches GCR_EL1 (it does this in the user-space support, Vincenzo's patches should move that to exception entry/return). -- Catalin