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=-3.9 required=3.0 tests=BAYES_00,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 89733C4363A for ; Mon, 26 Oct 2020 14:34:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 399CC20780 for ; Mon, 26 Oct 2020 14:34:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kylehuey.com header.i=@kylehuey.com header.b="SFQbPyIv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1781569AbgJZOeU (ORCPT ); Mon, 26 Oct 2020 10:34:20 -0400 Received: from mail-ej1-f41.google.com ([209.85.218.41]:37913 "EHLO mail-ej1-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1780904AbgJZOdZ (ORCPT ); Mon, 26 Oct 2020 10:33:25 -0400 Received: by mail-ej1-f41.google.com with SMTP id ce10so13879991ejc.5 for ; Mon, 26 Oct 2020 07:33:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kylehuey.com; s=google; h=mime-version:from:date:message-id:subject:to:cc; bh=E/rHwyHstBtFx+2oIPLuGDkFNZ5+Epy0kc85HssH4xs=; b=SFQbPyIve02J4LqaTq6zkgkhCIEgOdzT6Qmg7jEMouLEnl1ISwPn9SuwdtPNhhrJEs ryXxIh9FfvtoBg2uxNTBY3C92pIq03vmyEm97fuZDziJPWb0mxibI4KvimqjoqyrY0E2 2MPcJTN59Yz2ZgzdGp4EPbBNhqV9f7iBxUs1rLvTXryewsSlc0eQteq+jqgtX4EB/w6B To+NWxt2h8WWtc9S7KB9WBaHqMoKMwpBEfRgxwioWpn86UnpnoRbgrCiXDe0a3eEfrs9 Ep+SQdzeD5n6l2qrVuUNvuotBCW+NxxKnJC0DTXs4jHPag/hQWT1OyW8FL0+ElRL9YmQ wkBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc; bh=E/rHwyHstBtFx+2oIPLuGDkFNZ5+Epy0kc85HssH4xs=; b=IKZ8wTOzODDJIWFBWZRB1XeVc+sDDgzgrc4YqLW0rCA+sRwB18FJ/Ue8ZWL2HawqRs MYYgAA2Swy+osBbwxH/iqJZV0394nGWrX26PeRVJznVPxk1Zv0iqmPy1UD9GZNqGqEBm Qaf4JYUq/K8WcKk3mPJjL1fCfkFm9XWQpmj/6KaSzI1ziI2kj2xBg+ci6CGSaAwg9Kdn nmoiFjikGQ9nDXoDb6HY1ylZirGK9aBfcpUd/QnIRBnTHEGn9vgdLc2tyDlSdD8AEVad zYhkRxu7t8nl7ZVhTHFZni/4/X8oZ1eb8t2l4/VXpSZc4Y8boNxIYPbgtevacrSQ9pGO x7bA== X-Gm-Message-State: AOAM5317J6AOfaURHhpvug7LAo/9fM1hwKRnePN/xFjTj600bmeJ2zTX bsz3Gs4jdjc3L+hlilOnAxLLndhk9iPD47vU0cnZhxn6jaOaXJSM X-Google-Smtp-Source: ABdhPJxZ2lGDG0TsL8425km3QyMmh8Zl1x0eua3hQt1rDFExFM1Xyzku+3GcwNv4HHtJjL/5/HWs+xFMfhmQd4WrfFs= X-Received: by 2002:a17:906:b285:: with SMTP id q5mr16495210ejz.135.1603722802857; Mon, 26 Oct 2020 07:33:22 -0700 (PDT) MIME-Version: 1.0 From: Kyle Huey Date: Mon, 26 Oct 2020 07:33:08 -0700 Message-ID: Subject: [REGRESSION] x86/debug: After PTRACE_SINGLESTEP DR_STEP is no longer reported in dr6 To: open list , "Peter Zijlstra (Intel)" Cc: Thomas Gleixner , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Linus Torvalds , "Robert O'Callahan" , Alexandre Chartre , "Paul E. McKenney" , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Joel Fernandes , Steven Rostedt , Boris Ostrovsky , Juergen Gross , Brian Gerst , Andy Lutomirski , Josh Poimboeuf , Daniel Thompson Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After resuming a ptracee with PTRACE_SINGLESTEP, in the following ptrace stop retrieving the dr6 value for the tracee gets a value that does not include DR_STEP (it is in fact always DR6_RESERVED). I bisected this to the 13cb73490f475f8e7669f9288be0bcfa85399b1f merge. I did not bisect further. I don't see any handling to ever set DR_STEP in virtual_dr6, so I think this code is just broken. Sorry for not testing this when I was CCd on the original patch series :) - Kyle