From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/10108 Path: news.gmane.org!not-for-mail From: Andy Lutomirski Newsgroups: gmane.linux.kernel,gmane.linux.lib.musl.general Subject: Re: [musl] Broken vDSO on built kernel Date: Thu, 9 Jun 2016 10:40:21 -0700 Message-ID: References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1465494070 15200 80.91.229.3 (9 Jun 2016 17:41:10 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 9 Jun 2016 17:41:10 +0000 (UTC) Cc: fREW Schmidt , Linux Kernel , "musl@lists.openwall.com" To: Alexander Monakov Original-X-From: linux-kernel-owner@vger.kernel.org Thu Jun 09 19:41:01 2016 Return-path: Envelope-to: glk-linux-kernel-3@plane.gmane.org Original-Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bB3ww-0004Yt-Ci for glk-linux-kernel-3@plane.gmane.org; Thu, 09 Jun 2016 19:40:58 +0200 Original-Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932881AbcFIRkn (ORCPT ); Thu, 9 Jun 2016 13:40:43 -0400 Original-Received: from mail-oi0-f54.google.com ([209.85.218.54]:34841 "EHLO mail-oi0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932143AbcFIRkl (ORCPT ); Thu, 9 Jun 2016 13:40:41 -0400 Original-Received: by mail-oi0-f54.google.com with SMTP id s139so74977338oie.2 for ; Thu, 09 Jun 2016 10:40:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=QRPvklkQaeJ85o9O4q3IbyVoX8TK4nL4gkiPUPNSA4I=; b=WlaO6ZQlya62fakz0/VWUbYnrMgWpNKQeadFQw1OVQ4QB/4HQe39UFfKpNAnAP1haj Rtu9Cr4BInKvXqM2zoKVn+pHqC5VT4nPAgBGl6MQJFpeSjNLYN3/7+HjzDp5mbXJHL+J eY0X+ZcEnACcaqn5C4QtIYarGnuAQ4t37UZH8qKg7ys1VAatWvzbyw8u3KohXSoe1KFW Byx96Ms1F2+7tCwpl1JJWH+hy6x2DNGnKJy0eNGAMQMeRb+nPsuTEhLarnU3cEtzfE9y 4/KtB4hsd0msz5kDDEjlZPDf5pPpLvODurAu6/+VrB4Vfs7A9P7xC4eMyKb/AW36tNWJ tclg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=QRPvklkQaeJ85o9O4q3IbyVoX8TK4nL4gkiPUPNSA4I=; b=Awnk/Y0EvVxuKK+mYzEjxNOfnYG51aSfuTMLg8Goc32TIIlx5ub4HFykgQvHmRwKSW /I8ZRmWeIRuQ2xS0rW7Ft8HAsRB7t/M97V64iO+AzcPFzpWD1NlhaQUD1VXQH5ZUBehU KhXWKWpKa8P76WNYHkfJUGpnDEPRtOaWuxKZRJLr1re+sBtnDieC8uWSvtsX8ZzNBSR5 RKEp3nTeMQF0beAtbgQdYe+gXtvSEZwCeE8YLMULR2PrlH6KtwhV77tynlj1R6uSt6LB W7/hJfqivCEtqSHLqqhN1NwYj0rozvj5EkoLCg+OtihwmovdiwJ6/mFHp7yL6FKi1Yl0 IGqQ== X-Gm-Message-State: ALyK8tJ1+eexArcJ2hxTgsXR/P5um+75Wtb0v6hHXUu5FkaL6770YCOpk7I0hwVIZOYdfW81oZr1s6yzD5cRSwQi X-Received: by 10.157.11.59 with SMTP id a56mr6147225ota.128.1465494040528; Thu, 09 Jun 2016 10:40:40 -0700 (PDT) Original-Received: by 10.202.199.148 with HTTP; Thu, 9 Jun 2016 10:40:21 -0700 (PDT) In-Reply-To: Original-Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Xref: news.gmane.org gmane.linux.kernel:2239956 gmane.linux.lib.musl.general:10108 Archived-At: On Wed, Jun 8, 2016 at 2:36 PM, Alexander Monakov wrote: > On Wed, 8 Jun 2016, fREW Schmidt wrote: >> I was debugging an issue I ran into ( >> https://github.com/docker/docker/issues/23378) and after chatting with the >> folks in #musl and we triaged it down to a broken vDSO (tested by running >> `strace date` and seeing a clock_gettime call.) > > To provide a bit more detail, we've found that the vdso mappend into the > application has no dynamic symbols; Glibc ignores the vdso, so it continues to > work, but musl segfaults since the vdso is invalid. > > I'm pasting below `readelf -aW` output on the vdso dumped on the affected > system (via 'fwrite((void*)getauxval(AT_SYSINFO_EHDR), 8192, 1, stdout)'; > as you can see, there's no dynamic symbols and symbol hash tables. It may > be a toolchain bug since there was no issue with 4.6 kernel (and reportedly > there were no significant vdso changes merged into 4.7 -- the issue is seen > on Ubuntu's 4.7rc2). Hmm. The vdso64.so in /lib/firmware in that image has the same problem, so this isn't vdso2c's fault. I added this to my -next queue to help diagnose it: https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=x86/vdso&id=6436d4c1a83cbe083e54c53bb2b16efaab9b62f4 --Andy