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=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 BB58DC433E1 for ; Tue, 9 Jun 2020 14:16:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5BAD20801 for ; Tue, 9 Jun 2020 14:16:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730149AbgFIOQ3 (ORCPT ); Tue, 9 Jun 2020 10:16:29 -0400 Received: from foss.arm.com ([217.140.110.172]:43088 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730095AbgFIOQZ (ORCPT ); Tue, 9 Jun 2020 10:16:25 -0400 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 01A661FB; Tue, 9 Jun 2020 07:16:24 -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 BD27A3F66F; Tue, 9 Jun 2020 07:16:22 -0700 (PDT) Date: Tue, 9 Jun 2020 15:16:20 +0100 From: Dave Martin To: "Michael Kerrisk (man-pages)" Cc: linux-man@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Will Deacon , Catalin Marinas , Amit Daniel Kachhap , Mark Rutland Subject: Re: [PATCH v2 5/6] prctl.2: Add PR_PAC_RESET_KEYS (arm64) Message-ID: <20200609141620.GC25945@arm.com> References: <1590614258-24728-1-git-send-email-Dave.Martin@arm.com> <1590614258-24728-6-git-send-email-Dave.Martin@arm.com> <1084d017-54f3-475c-be1b-aabc801d9a71@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1084d017-54f3-475c-be1b-aabc801d9a71@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-man-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org On Tue, Jun 09, 2020 at 01:36:42PM +0200, Michael Kerrisk (man-pages) wrote: > Hello Dave, > > I've applied this patch (manually, because 4/6 is not yet applied). > I have a question below. > > On 5/27/20 11:17 PM, Dave Martin wrote: > > Add documentation for the PR_PAC_RESET_KEYS ioctl added in Linux > > 5.0 for arm64. > > > > Signed-off-by: Dave Martin > > Cc: Will Deacon > > Cc: Catalin Marinas > > Cc: Amit Daniel Kachhap > > Cc: Mark Rutland > > > > --- > > > > Since v1: > > > > * Clarify explicitly that PR_PAC_RESET_KEYS is redundant when combined > > with execve(). > > > > * Move error condition details into the prctl description, to avoid > > excessive duplication while keeping keeping related pieces of text > > closer together. > > > > * In lieu of having a separate man page to cross reference for detailed > > guidance, cross-reference the kernel documentation. > > > > * Add safety warning. This is deliberately vague, pending ongoing > > discussions with libc folks. > > --- > > man2/prctl.2 | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 80 insertions(+) > > > > [...] > > > +.IP > > +.B Warning: > > +Because the compiler or run-time environment > > +may be using some or all of the keys, > > +a successful > > Things got a bit garbled here. I think the next few lines should have been > at the end. > > +.IP > > +For more information, see the kernel source file > > +.I Documentation/arm64/pointer\-authentication.rst > > +.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed > > +(or > > +.I Documentation/arm64/pointer\-authentication.txt > > +before Linux 5.3). > > +.B PR_PAC_RESET_KEYS > > +may crash the calling process. > > +The conditions for using it safely are complex and system-dependent. > > +Don't use it unless you know what you are doing. > > I applied the following change after your patch; is it okay? > > .IP > .B Warning: > Because the compiler or run-time environment > may be using some or all of the keys, > a successful Looks fine, execpt that I think you need to move the .B PR_PAC_RESET_KEYS line here also. Thanks ---Dave > +may crash the calling process. > +The conditions for using it safely are complex and system-dependent. > +Don't use it unless you know what you are doing. > .IP > For more information, see the kernel source file > .I Documentation/arm64/pointer\-authentication.rst > @@ -1020,9 +1023,6 @@ For more information, see the kernel source file > .I Documentation/arm64/pointer\-authentication.txt > before Linux 5.3). > .B PR_PAC_RESET_KEYS > -may crash the calling process. > -The conditions for using it safely are complex and system-dependent. > -Don't use it unless you know what you are doing. > .\" prctl PR_SET_PDEATHSIG > .TP > .BR PR_SET_PDEATHSIG " (since Linux 2.1.57)" > [...]