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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 CAAD5C433DF for ; Wed, 27 May 2020 08:32:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 911A12084C for ; Wed, 27 May 2020 08:32:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 911A12084C 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 1FE6C800B8; Wed, 27 May 2020 04:32:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 188B980010; Wed, 27 May 2020 04:32:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 05000800B8; Wed, 27 May 2020 04:32:25 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0091.hostedemail.com [216.40.44.91]) by kanga.kvack.org (Postfix) with ESMTP id DECDA80010 for ; Wed, 27 May 2020 04:32:25 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 9E9032C8B for ; Wed, 27 May 2020 08:32:25 +0000 (UTC) X-FDA: 76861832250.10.party03_4b0e60226d50 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin10.hostedemail.com (Postfix) with ESMTP id 7BA7816A4AA for ; Wed, 27 May 2020 08:32:25 +0000 (UTC) X-HE-Tag: party03_4b0e60226d50 X-Filterd-Recvd-Size: 4148 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Wed, 27 May 2020 08:32:24 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1A61F30E; Wed, 27 May 2020 01:32:24 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 995513F6C4; Wed, 27 May 2020 01:32:22 -0700 (PDT) Date: Wed, 27 May 2020 09:32:20 +0100 From: Dave Martin To: Will Deacon Cc: Catalin Marinas , linux-arch@vger.kernel.org, Szabolcs Nagy , Andrey Konovalov , Kevin Brodsky , linux-mm@kvack.org, Vincenzo Frascino , Peter Collingbourne , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4 15/26] arm64: mte: Allow user control of the tag check mode via prctl() Message-ID: <20200527083218.GS5031@arm.com> References: <20200515171612.1020-1-catalin.marinas@arm.com> <20200515171612.1020-16-catalin.marinas@arm.com> <20200527074658.GB9887@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200527074658.GB9887@willie-the-truck> User-Agent: Mutt/1.5.23 (2014-03-12) X-Rspamd-Queue-Id: 7BA7816A4AA 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 Wed, May 27, 2020 at 08:46:59AM +0100, Will Deacon wrote: > On Fri, May 15, 2020 at 06:16:01PM +0100, Catalin Marinas wrote: > > By default, even if PROT_MTE is set on a memory range, there is no tag > > check fault reporting (SIGSEGV). Introduce a set of option to the > > exiting prctl(PR_SET_TAGGED_ADDR_CTRL) to allow user control of the tag > > check fault mode: > > > > PR_MTE_TCF_NONE - no reporting (default) > > PR_MTE_TCF_SYNC - synchronous tag check fault reporting > > PR_MTE_TCF_ASYNC - asynchronous tag check fault reporting > > > > These options translate into the corresponding SCTLR_EL1.TCF0 bitfield, > > context-switched by the kernel. Note that uaccess done by the kernel is > > not checked and cannot be configured by the user. > > > > Signed-off-by: Catalin Marinas > > Cc: Will Deacon > > --- > > > > Notes: > > v3: > > - Use SCTLR_EL1_TCF0_NONE instead of 0 for consistency. > > - Move mte_thread_switch() in this patch from an earlier one. In > > addition, it is called after the dsb() in __switch_to() so that any > > asynchronous tag check faults have been registered in the TFSR_EL1 > > registers (to be added with the in-kernel MTE support. > > > > v2: > > - Handle SCTLR_EL1_TCF0_NONE explicitly for consistency with PR_MTE_TCF_NONE. > > - Fix SCTLR_EL1 register setting in flush_mte_state() (thanks to Peter > > Collingbourne). > > - Added ISB to update_sctlr_el1_tcf0() since, with the latest > > architecture update/fix, the TCF0 field is used by the uaccess > > routines. > > > > arch/arm64/include/asm/mte.h | 14 ++++++ > > arch/arm64/include/asm/processor.h | 3 ++ > > arch/arm64/kernel/mte.c | 77 ++++++++++++++++++++++++++++++ > > arch/arm64/kernel/process.c | 26 ++++++++-- > > include/uapi/linux/prctl.h | 6 +++ > > 5 files changed, 123 insertions(+), 3 deletions(-) > > Dave is working on man pages for prctl() (and I think also ptrace). I think > it would be /very/ useful for us to have some RFC patches on top of his work > adding documentation for the MTE interactions, as we found some other minor > issues/inconsistencies as a direct result of writing and reviewing the man > page for our existing interfaces. I have a local draft for the address tagging and MTE prctls already btw. I hadn't posted them yet so as to focus on nailing the "easy" stuff down ;) If I have time I'll try and get them posted today so that people can take a look before next week. Cheers ---Dave