From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: Re: [PATCH v4 15/26] arm64: mte: Allow user control of the tag check mode via prctl() Date: Wed, 27 May 2020 09:32:20 +0100 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 Return-path: Received: from foss.arm.com ([217.140.110.172]:33824 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387397AbgE0IcY (ORCPT ); Wed, 27 May 2020 04:32:24 -0400 Content-Disposition: inline In-Reply-To: <20200527074658.GB9887@willie-the-truck> Sender: linux-arch-owner@vger.kernel.org List-ID: 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 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 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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 709AAC433DF for ; Wed, 27 May 2020 08:32:30 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2D48E2084C for ; Wed, 27 May 2020 08:32:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Xb6BG5Sx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D48E2084C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=fnRR7XVMFd4XkuNnmFKysjR7HPhqKxAWzU8x6VFQjOI=; b=Xb6BG5SxrnQc3Z Lxa5+Frav3KjlDNerGvDnjjqExD/vmVDnMSRMIF+RLxozoylYvCVf/qWM+vOeXt0ynMSNn/+AtHig bADA7498ecTGMZBeFHbtVKuA3a+o7R+OLrlj58mPTJxXgUakEmwoZVTws2tPr11lUvgz6OUzccjJf CfChDHeiwFohCFSrOiNHwgitVxwtBuFlcO70J/ct4wan3fU+W1eYUj4qxwJYhDVF4i6YepiZ0Qq1n rAJ1yO3c/Xnr+CM8ScWmSf2JFWSrVYuiwjaFsKrnaYBD1lFx8xofcjP0OIMr/Mll0sBNXzjGt3RIU wBDtsDO5IAQaWkQRlxOg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jdrUD-0007O9-NP; Wed, 27 May 2020 08:32:29 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jdrUA-0007NH-T5 for linux-arm-kernel@lists.infradead.org; Wed, 27 May 2020 08:32:28 +0000 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 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-Disposition: inline In-Reply-To: <20200527074658.GB9887@willie-the-truck> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200527_013226_981228_4E28C2E8 X-CRM114-Status: GOOD ( 22.72 ) 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-arch@vger.kernel.org, Szabolcs Nagy , Catalin Marinas , Kevin Brodsky , linux-mm@kvack.org, Andrey Konovalov , Vincenzo Frascino , Peter Collingbourne , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel