From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.1 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 21218 invoked from network); 25 Jan 2021 19:48:39 -0000 Received: from mother.openwall.net (195.42.179.200) by inbox.vuxu.org with ESMTPUTF8; 25 Jan 2021 19:48:39 -0000 Received: (qmail 32214 invoked by uid 550); 25 Jan 2021 19:48:37 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 32193 invoked from network); 25 Jan 2021 19:48:36 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1611604105; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=T0e01bxajqn+PVY8S3l+lrgXyyyKwXZWZMqj8U4rvaY=; b=X4MUORDV6/V3vHVsoD3gaPwA4mxK0gQomc7kqawlc4tYWlaTtihP2GZ4ErHch84/D0Glrk draFWt2TJ5XRHT5LaJG8EuGYFPqS00oLBnu5N6bmf7wDCRYKvQe/jhKPkoEUoCO+h5mwhm slRoBUqYE1v3YqbP0HMd6SW4Z0567UM= X-MC-Unique: 8IzvHbiZPpm9tP0gsaLqgA-1 From: Florian Weimer To: Markus Wichmann Cc: musl@lists.openwall.com References: <3521697.b4TYcCAa2N@omega> <20210125144236.GV23432@brightrain.aerifal.cx> <2658009.jRRjQAZNrc@omega> <20210125161512.GW23432@brightrain.aerifal.cx> <20210125193758.GC2006@voyager> Date: Mon, 25 Jan 2021 20:48:18 +0100 In-Reply-To: <20210125193758.GC2006@voyager> (Markus Wichmann's message of "Mon, 25 Jan 2021 20:37:58 +0100") Message-ID: <87tur4g5ml.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 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=fweimer@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [musl] insufficient checking in posix_spawn_file_actions_add{open,dup2} * Markus Wichmann: > Adding a getpid vDSO call would require adding the code itself, adding > the PID to the vvar page (isn't that shared among all processes?), and > adding support for finding the vDSO function into the libcs. All of that > for rather dubious performance benefits (or can you name a program that > was not fast enough because getpid() ran too slowly?) There's some discussion about this in the context of extensible rseq support, including userspace donating thread-local data for kernel use (=E2=80=9CKTLS=E2=80=9D). Reliable PID/TID/UID caching in userspace and si= gprocmask with a userspace fastpath are potential applications. Thanks, Florian --=20 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'N= eill