Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy

Path	csiph.com!au2pb.net!feeder.erje.net!2.eu.feeder.erje.net!eternal-september.org!feeder.eternal-september.org!aioe.org!bofh.it!news.nic.it!robomod
From	Jeff Merkey <linux.mdb@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy
Date	Thu, 10 Dec 2015 23:30:01 +0100
Message-ID	<qEhSN-3Pc-9@gated-at.bofh.it> (permalink)
References	<qE3G9-2Ub-5@gated-at.bofh.it> <qEeBz-1xO-5@gated-at.bofh.it> <qEeLg-1Qp-3@gated-at.bofh.it> <qEgtI-2KO-23@gated-at.bofh.it>
X-Original-To	Thomas Gleixner <tglx@linutronix.de>
Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=vAdvl89gU5S+9qMR+URzRdu3NOLQweilxgkNuDPwirg=; b=Ythppi/ZjS3fDDEpKzttcSI9TkA994RZTfs6bA5D4g5QGVEO+kqPezCtmCIjXefR6l vL2W3bgcrIKiZkgvq23smUEXiFkcXS7ZNVX/gMemZ7f2ud8lpYwHdG90b4V3W548n/pS VLUzHyS/S9MU5Ikf++7Y5hm0AWWSctBVCB6nt0lVuyQIer+FEBwwa0l0qqXMT4s2RFXm MPWTdcO7mxS9Sa5ih1HKXNs/qIMDxPY7ZP9AI8XlSYFpLrNRIusKyr2xW8p6rcCGujFO CfqqhqcbqQSXWnHK99q/mYFoKtZNQqvY8wHXJ60/WjAT+vishBx/0dfHHqtCq7qScl4C lEBg==
MIME-Version	1.0
X-Received	by 10.107.34.7 with SMTP id i7mr14266488ioi.32.1449786403220; Thu, 10 Dec 2015 14:26:43 -0800 (PST)
Content-Type	text/plain; charset=UTF-8
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	35
Organization	linux.* mail to news gateway
X-Original-Cc	Andy Lutomirski <luto@amacapital.net>, LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>, X86 ML <x86@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Andy Lutomirski <luto@kernel.org>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Steven Rostedt <rostedt@goodmis.org>, Borislav Petkov <bp@alien8.de>, Jiri Olsa <jolsa@kernel.org>
X-Original-Date	Thu, 10 Dec 2015 15:26:43 -0700
X-Original-Message-ID	<CAO6TR8VW4P9KWwh_X4ckD_pCi+hkfKZ4mPAqquv6cJAm-HAy9g@mail.gmail.com>
X-Original-References	<CAO6TR8W1ViJonskb0eObG+THObpabh909ob0Oz_8LAvNMuOPmA@mail.gmail.com> <alpine.DEB.2.11.1512101942470.3623@nanos> <CALCETrUaWxqyuyE2FqCs0ULPBdKMwCPtaoneyt4yBA8r5a5=yQ@mail.gmail.com> <alpine.DEB.2.11.1512102050290.3623@nanos>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1288975

Show key headers only | View raw

I'll submit a second patch later this evening with a graceful message
when this happens.  I need to look over this code path -- its in a
very mature section of code and detecting this condition (bp not being
present) may break other code paths and subsystems ifs not done very
carefully.  The current dr7 check works and I have tested this code,
but does not print a message.



On 12/10/15, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Thu, 10 Dec 2015, Andy Lutomirski wrote:
>> On brief inspection, this smells like a microcode bug.  Can you send
>> /proc/cpuinfo output?
>>
>> If this is the issue, I'm not sure we want to be in the business of
>> working around localized microcode bugs and, if we do, then I think we
>> should explicitly detect the bug and log about it.
>
> I think we should handle such stuff gracefully. Yes, we should log it
> and we also should check what the contents of the debug registers are.
>
> If dr7 has a break point enabled w/o perf having one installed then we
> know that someone did a horrible hackery ....
>
> Thanks,
>
> 	tglx
>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Thread

[PATCH 1/1] Fix int1 recursion when no perf_bp_event is registered Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 08:20 +0100
  Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is  registered Thomas Gleixner <tglx@linutronix.de> - 2015-12-10 20:00 +0100
    Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registered Andy Lutomirski <luto@amacapital.net> - 2015-12-10 20:10 +0100
      Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is  registered Jiri Olsa <jolsa@redhat.com> - 2015-12-10 20:30 +0100
        Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is  registered Borislav Petkov <bp@alien8.de> - 2015-12-10 20:30 +0100
      Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is  registeredy Thomas Gleixner <tglx@linutronix.de> - 2015-12-10 22:00 +0100
        Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Andy Lutomirski <luto@amacapital.net> - 2015-12-10 22:10 +0100
          Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is  registeredy Thomas Gleixner <tglx@linutronix.de> - 2015-12-10 22:20 +0100
            Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 22:30 +0100
          Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 22:20 +0100
        Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 22:20 +0100
        Re: [PATCH 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-10 23:30 +0100
        Re: [PATCH v2 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-11 09:10 +0100
          Re: [PATCH v2 1/1] Fix int1 recursion when no perf_bp_event is registeredy Jeff Merkey <linux.mdb@gmail.com> - 2015-12-11 20:10 +0100

csiph-web