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From: Masami Hiramatsu <mhiramat@redhat.com>
To: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: ananth@in.ibm.com, LKML <linux-kernel@vger.kernel.org>,
	jkenisto@us.ibm.com, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 0/3][RFC] x86: Catch stray non-kprobe breakpoints
Date: Tue, 29 Jan 2008 14:29:41 -0500	[thread overview]
Message-ID: <479F7EA5.5040201@redhat.com> (raw)
In-Reply-To: <863e9df20801291008x40208609j15749fc6e39fbe47@mail.gmail.com>

Abhishek Sagar wrote:
> On 1/29/08, Masami Hiramatsu <mhiramat@redhat.com> wrote:
>> In that case, why don't you just reduce the priority of kprobe_exceptions_nb?
>> Then, the execution path becomes very simple.
> 
> Ananth mentioned that the kprobe notifier has to be the first to run.

(Hmm.. I think he has just explained current implementation:))
IMHO, since kprobes itself can not know what the external debugger
wants to do, the highest priority should be reserved for those external tools.

> It still wouldnt allow us to notice breakpoints on places like do_int3
> etc.

If you'd like to do that, my recommendation is to modify IDT directly.

>> I also like to use a debugger for debugging kprobes. that will help us.
> 
> Hmm...It would increase the code-path leading upto kprobe_handler.
> That's more territory to be guarded from kprobes.

Sure, all functions of the debugger should be marked __kprobes.
Thus it will be guarded from kprobes.

Thank you,

-- 
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com


  reply	other threads:[~2008-01-29 19:37 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-27  9:08 Abhishek Sagar
2008-01-29  6:02 ` Ananth N Mavinakayanahalli
2008-01-29 10:40   ` Abhishek Sagar
2008-01-29 13:18     ` Ananth N Mavinakayanahalli
2008-01-29 17:24       ` Abhishek Sagar
2008-01-29 15:13     ` Masami Hiramatsu
2008-01-29 18:08       ` Abhishek Sagar
2008-01-29 19:29         ` Masami Hiramatsu [this message]
2008-01-30  4:07           ` Ananth N Mavinakayanahalli

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