linux-kernel - Re: Dealing with the NMI mess

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Message-ID: <20150724113426.3b0d3706@gandalf.local.home>
Date:	Fri, 24 Jul 2015 11:34:26 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Willy Tarreau <w@....eu>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@...capital.net>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Brian Gerst <brgerst@...il.com>
Subject: Re: Dealing with the NMI mess

On Fri, 24 Jul 2015 17:26:37 +0200
Willy Tarreau <w@....eu> wrote:

 
> > The point is, if we trigger a #DB on an instruction breakpoint
> > while !IF, then we simply disable that breakpoint and do the RET.
> 
> Yes but the breakpoint remains disabled then. Or I'm missing
> something.

Do we care? If it was an instruction breakpoint with !IF set, then it
had to have happened in the kernel. And kgdb or whatever added it there
needs to deal with that.

There should be no instances in the kernel where we execute userspace
code with interrupts disabled.

-- Steve
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