From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot0-f200.google.com (mail-ot0-f200.google.com [74.125.82.200]) by kanga.kvack.org (Postfix) with ESMTP id 51BCB6B026D for ; Wed, 22 Nov 2017 07:15:29 -0500 (EST) Received: by mail-ot0-f200.google.com with SMTP id t79so8438247ota.7 for ; Wed, 22 Nov 2017 04:15:29 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id s9si6015723oif.252.2017.11.22.04.15.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Nov 2017 04:15:28 -0800 (PST) Subject: Re: MPK: removing a pkey References: <0f006ef4-a7b5-c0cf-5f58-d0fd1f911a54@redhat.com> <8741e4d6-6ac0-9c07-99f3-95d8d04940b4@suse.cz> From: Florian Weimer Message-ID: <813f9736-36dd-b2e5-c850-9f2d5f94514a@redhat.com> Date: Wed, 22 Nov 2017 13:15:24 +0100 MIME-Version: 1.0 In-Reply-To: <8741e4d6-6ac0-9c07-99f3-95d8d04940b4@suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka , Dave Hansen , linux-x86_64@vger.kernel.org, linux-arch@vger.kernel.org Cc: linux-mm , Linux API On 11/22/2017 09:18 AM, Vlastimil Babka wrote: > And, was the pkey == -1 internal wiring supposed to be exposed to the > pkey_mprotect() signal, or should there have been a pre-check returning > EINVAL in SYSCALL_DEFINE4(pkey_mprotect), before calling > do_mprotect_pkey())? I assume it's too late to change it now anyway (or > not?), so should we also document it? I think the -1 case to the set the default key is useful because it allows you to use a key value of -1 to mean a??MPK is not supporteda??, and still call pkey_mprotect. I plan to document this behavior on the glibc side, and glibc will call mprotect (not pkey_mprotect) for key -1, so that you won't get ENOSYS with kernels which do not support pkey_mprotect. Thanks, Florian -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org