From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-1.mimecast.com (us-smtp-1.mimecast.com [207.211.31.81]) by sourceware.org (Postfix) with ESMTP id 03262386F02B for ; Mon, 18 May 2020 07:19:38 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 03262386F02B Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-115-d0dBDE-5MN2cCz3OPnzl_w-1; Mon, 18 May 2020 03:19:34 -0400 X-MC-Unique: d0dBDE-5MN2cCz3OPnzl_w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D928780058A; Mon, 18 May 2020 07:19:33 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-112-142.ams2.redhat.com [10.36.112.142]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 351C98206B; Mon, 18 May 2020 07:19:33 +0000 (UTC) From: Florian Weimer To: "H.J. Lu via Libc-alpha" Subject: Re: [PATCH] x86: Move CET control to _dl_x86_feature_control [BZ #25887] References: <20200428215243.236312-1-hjl.tools@gmail.com> <20200428215243.236312-2-hjl.tools@gmail.com> <871rnjoknd.fsf@mid.deneb.enyo.de> Date: Mon, 18 May 2020 09:19:31 +0200 In-Reply-To: (H. J. Lu via Libc-alpha's message of "Sat, 16 May 2020 16:44:04 -0700") Message-ID: <87mu65g16k.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-13.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 May 2020 07:19:40 -0000 * H. J. Lu via Libc-alpha: > Here is the updated patch to use bitfields. Thanks, I like this better. > diff --git a/sysdeps/x86/cet-tunables.h b/sysdeps/x86/cet-control.h > similarity index 61% > rename from sysdeps/x86/cet-tunables.h > rename to sysdeps/x86/cet-control.h > index 5e1e42df10..3a314f9609 100644 > --- a/sysdeps/x86/cet-tunables.h > +++ b/sysdeps/x86/cet-control.h > @@ -16,14 +16,26 @@ > License along with the GNU C Library; if not, see > . */ > =20 > -/* Valid control values: > - 0: Enable CET features based on ELF property note. > - 1: Always disable CET features. > - 2: Always enable CET features. > - 3: Enable CET features permissively. > - */ > -#define CET_ELF_PROPERTY=090 > -#define CET_ALWAYS_OFF=09=091 > -#define CET_ALWAYS_ON=09=092 > -#define CET_PERMISSIVE=09=093 > -#define CET_MAX=09=09=09CET_PERMISSIVE > +#ifndef _CET_CONTROL_H > +#define _CET_CONTROL_H > + > +/* For each CET feature, IBT and SHSTK, valid control values */ Missing =E2=80=9D.=E2=80=9D at end of comment. > +enum dl_x86_cet_control > +{ > + /* Enable CET features based on ELF property note. */ > + elf_property =3D 0, > + /* Always enable CET features. */ > + always_on, > + /* Always disable CET features. */ > + always_off, > + /* Enable CET features permissively. */ Missing double space after =E2=80=9C.=E2=80=9D. > + permissive > +}; Given enum constantse are not not scoped and this is a widely-included header, I think you should include at least a =E2=80=9Ccet_=E2=80=9D prefix= in these enum constants. It's still not clear to me why CET control variables have to be in _rtld_global. Regular global variables would likely lead to clearer code, I think. _rtld_global is needed for read-write data that is shared with libc/libdl, and this does not seem to apply to CET control settings. Thanks, Florian