From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTP id 4214E3844054 for ; Thu, 24 Jun 2021 07:56:47 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4214E3844054 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-240-MSpkRMFXPhmifspAIEV2OA-1; Thu, 24 Jun 2021 03:56:43 -0400 X-MC-Unique: MSpkRMFXPhmifspAIEV2OA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EC467100C661; Thu, 24 Jun 2021 07:56:42 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-228.ams2.redhat.com [10.36.112.228]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E6502100EBAF; Thu, 24 Jun 2021 07:56:41 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella via Libc-alpha Subject: Re: [PATCH] x86: Copy IBT and SHSTK usable only if CET is enabled References: <20210623145419.3025540-1-adhemerval.zanella@linaro.org> <7b2557a7-9b86-7121-a366-5fee330f8364@linaro.org> <89312fbc-0fb1-8523-2c1c-c99025bb787e@linaro.org> Date: Thu, 24 Jun 2021 09:56:39 +0200 In-Reply-To: <89312fbc-0fb1-8523-2c1c-c99025bb787e@linaro.org> (Adhemerval Zanella via Libc-alpha's message of "Wed, 23 Jun 2021 21:30:06 -0300") Message-ID: <87fsx7n1ag.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, 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: Thu, 24 Jun 2021 07:56:48 -0000 * Adhemerval Zanella via Libc-alpha: > + x86_cpu_AMD_IBPB = x86_cpu_index_80000008_ebx + 12, > + x86_cpu_AMD_IBRS = x86_cpu_index_80000008_ebx + 14, > + x86_cpu_AMD_STIBP = x86_cpu_index_80000008_ebx + 15, > + x86_cpu_AMD_SSBD = x86_cpu_index_80000008_ebx + 24, Do these show up as USABLE automatically? The test suggests to me that they do. This points to a deeper problem elsewhere: new bits should not become available automatically, they must be copied over explicitly because ld.so does not know the semantics for a new bit in USABLE. Thanks, Florian