linux-kernel - Re: [PATCH 1/2] Fix perf LBR filtering

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Message-ID: <20130426075601.GB8669@dyad.programming.kicks-ass.net>
Date:	Fri, 26 Apr 2013 09:56:02 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	mingo@...nel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org, eranian@...gle.com,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/2] Fix perf LBR filtering

On Thu, Apr 25, 2013 at 07:42:11PM +0200, Andi Kleen wrote:
> There's the non cachable region tracking. But there's no guarantee a
> MMIO has to be in there, driver may still rely just on MTRRs. Also
> there may be MMIOs the kernel doesn't know about which just happen
> to be somewhere in the direct mapping.
> 
> I don't see any reliable way to detect all mmios.

Hmm.. that's unfortunate.

OK, so how about we use something like:

	 is_kernel_text() || is_module_text_address()

And bail if not; that should at least make it work for the simple case or
normal text and not be worse than what you propose for JIT stuff.
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