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 [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id EE7F439DC4C9 for ; Fri, 12 Feb 2021 09:43:13 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org EE7F439DC4C9 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-271-REIGx9YRPt-YZjIT3wZXCw-1; Fri, 12 Feb 2021 04:43:10 -0500 X-MC-Unique: REIGx9YRPt-YZjIT3wZXCw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BDCF3107ACC7; Fri, 12 Feb 2021 09:43:08 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-113-131.ams2.redhat.com [10.36.113.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 629E65C3E0; Fri, 12 Feb 2021 09:43:07 +0000 (UTC) From: Florian Weimer To: "H.J. Lu via Libc-alpha" Cc: Joseph Myers , "H.J. Lu" Subject: Re: [RFC] : An API for tagged address References: <20210211173711.71736-1-hjl.tools@gmail.com> Date: Fri, 12 Feb 2021 10:43:28 +0100 In-Reply-To: (H. J. Lu via Libc-alpha's message of "Thu, 11 Feb 2021 13:39:54 -0800") Message-ID: <877dndmxj3.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 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_H3, 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: Fri, 12 Feb 2021 09:43:17 -0000 * H. J. Lu via Libc-alpha: > On Thu, Feb 11, 2021 at 12:28 PM Joseph Myers wrote: >> >> On Thu, 11 Feb 2021, H.J. Lu via Libc-alpha wrote: >> >> > An API for tagged address: >> >> Please write a longer commit message, discussing what "tagged address" is, >> which architectures have such a thing (the API should try to cover >> whatever is common between architectures as far as possible - is this >> meant to relate to AArch64 MTE, how does it relate to the MTE code we > > This API is for Intel LAM: > > https://www.phoronix.com/scan.php?page=news_item&px=Intel-LAM-Glibc#:~:text=Intel%20Linear%20Address%20Masking%20(LAM,bit%20linear%20addresses%20for%20metadata.&text=With%20LAM%20enabled%2C%20the%20processor,linear%20address%20to%20access%20memory. > > and ARM TBI: > > https://en.wikichip.org/wiki/arm/tbi Do the setters/getters change process or thread properties? The interface assumes that the tag bits are uniform across pointer types. I think that's not true, at least from a historical perspective. People complained that our protection key interfaces are too slow to be useful. Do we need to find a way to inline the tag/untag operations? Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill