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=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 AB60DC433E0 for ; Thu, 11 Feb 2021 09:58:08 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3D6ED64E8A for ; Thu, 11 Feb 2021 09:58:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D6ED64E8A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8AA306B00A8; Thu, 11 Feb 2021 04:58:07 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 85A216B00A9; Thu, 11 Feb 2021 04:58:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 76F7C6B00AA; Thu, 11 Feb 2021 04:58:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0238.hostedemail.com [216.40.44.238]) by kanga.kvack.org (Postfix) with ESMTP id 5D99B6B00A8 for ; Thu, 11 Feb 2021 04:58:07 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 1EDDB180AD804 for ; Thu, 11 Feb 2021 09:58:07 +0000 (UTC) X-FDA: 77805536214.21.8AA047B Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf24.hostedemail.com (Postfix) with ESMTP id A86DCA0009C5 for ; Thu, 11 Feb 2021 09:58:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613037485; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type; bh=RcvQZfQlzkXbDd+sedEX6d4tNtyfERJhF6wUYmJztMg=; b=eDxt/JXAuk0au+HqC55V9ff8vVb7a0Pnx1yxAXrlgMxdQ5uFtXx3c+nYqYL4yKdS4NOY5i eMUIdjp6J9h+rwk4T9b742ezlX6+LIKZnqO7HXv0L4vXnK6CGS53njMIoUyu+v7BUksRqZ k7kv/cOpl83kZKkLxT1wjmmYGF1ylWg= 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-32-gDE4tcORO2yDBwN0hS3Apg-1; Thu, 11 Feb 2021 04:58:03 -0500 X-MC-Unique: gDE4tcORO2yDBwN0hS3Apg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A6F9085B660; Thu, 11 Feb 2021 09:58:02 +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 AE4745D9E8; Thu, 11 Feb 2021 09:58:01 +0000 (UTC) From: Florian Weimer To: linux-mm@kvack.org, linux-api@vger.kernel.org, libc-alpha@sourceware.org Subject: Are vDSO addresses special? Date: Thu, 11 Feb 2021 10:58:20 +0100 Message-ID: <87zh0bq62r.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Stat-Signature: fhuwxwetxrszzaisk5kdzcbpzz9ex8yz X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: A86DCA0009C5 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf24; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=170.10.133.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1613037485-765852 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In glibc, we have some code that copies the DT_SONAME string of the kernel vDSO into the heap, commented this way: /* Work around a kernel problem. The kernel cannot handle addresses in the vsyscall DSO pages in writev() calls. */ Is this really a problem anymore? vDSO addresses are ordinary userspace addresses, I think. (The vsyscall stuff is very different, of course, and maybe the vDSO started out the same way.) We only care about Linux 3.2 or later in glibc. 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