From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D898C11D2F for ; Mon, 24 Feb 2020 15:23:34 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 736B220714 for ; Mon, 24 Feb 2020 15:23:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cbxcd3HP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 736B220714 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48R5S30Xd2zDqTd for ; Tue, 25 Feb 2020 02:23:31 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=redhat.com (client-ip=207.211.31.81; helo=us-smtp-delivery-1.mimecast.com; envelope-from=joe.lawrence@redhat.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=cbxcd3HP; dkim-atps=neutral Received: from us-smtp-delivery-1.mimecast.com (us-smtp-2.mimecast.com [207.211.31.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48R5PR3mY0zDqTd for ; Tue, 25 Feb 2020 02:21:14 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582557670; 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=jEBsfrvOwKqUt5ZlukWoSu1qTBe+MspkyGGBOY4qAmA=; b=cbxcd3HPa/j63N53QKO0tXr9i7n6FXnTscHtve0/M9QcpAvqqDEaNdT1Pciz6xAgjJkVK8 P3Sn/z84vaO8iFRrsdboYQcyeep4WYm8hTxuZaqj0pDPFbT8lt6O6f+QGiYXTY/AgCrbz/ N/K8asGXB8MwGuYPyfWkRqiuEsRdW3E= 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-301-I169pOMwMSyikq1rKcQ8lg-1; Mon, 24 Feb 2020 10:21:02 -0500 X-MC-Unique: I169pOMwMSyikq1rKcQ8lg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 480DCA0CC2; Mon, 24 Feb 2020 15:21:01 +0000 (UTC) Received: from [10.18.17.119] (dhcp-17-119.bos.redhat.com [10.18.17.119]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AC87B5C114; Mon, 24 Feb 2020 15:21:00 +0000 (UTC) Subject: Re: vdso function descriptors (VDS64_HAS_DESCRIPTORS)? To: Benjamin Herrenschmidt , Segher Boessenkool References: <20200217160852.GA9557@redhat.com> <20200223000715.GW22482@gate.crashing.org> <587a0a1765ba1264b92044f7b1f9937eb40731f1.camel@kernel.crashing.org> From: Joe Lawrence Message-ID: <885be270-7af8-490d-302c-270a6db94ffe@redhat.com> Date: Mon, 24 Feb 2020 10:20:59 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <587a0a1765ba1264b92044f7b1f9937eb40731f1.camel@kernel.crashing.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 2/24/20 5:17 AM, Benjamin Herrenschmidt wrote: > On Sat, 2020-02-22 at 18:07 -0600, Segher Boessenkool wrote: >>> >>> so I don't believe they are ever used by default -- in this case >>> V_FUNCTION_BEGIN doesn't add to the .opd section with .name, .TOC base, >>> etc. >>> >>> Manually setting VDS64_HAS_DESCRIPTORS results in a vdso64.so in which >>> binutils tools like readelf properly report functions with symbol type >>> FUNC instead of NOTYPE. >>> >>> Are there pieces of the build/etc toolchain unprepared for function >>> descriptors? I'm just trying to figure out why the code defaults to >>> unsetting them. >> >> Because direct calls are faster than indirect calls? Ben might have a >> fuller explanation, cc:ing him. > > I don't remember why :-) I think I didn't want to mess with the OPD > fixup in glibc back then. > Does it make sense to just drop the unused VDS64_HAS_DESCRIPTORS code then? -- Joe