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Date: Mon, 15 Jun 2009 13:27:05 -0700 (PDT)
From: Linus Torvalds <torvalds@linux-foundation.org>
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To: Jeremy Fitzhardinge <jeremy@goop.org>
cc: Ingo Molnar <mingo@elte.hu>,
       Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>, mingo@redhat.com,
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Subject: Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain support
 to use NMI-safe methods
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On Mon, 15 Jun 2009, Jeremy Fitzhardinge wrote:
> 
> We have to restore the usermode %gs somewhere...

None of this is useful for user-mode return _anyway_, since you have to 
restore %cs/%ss too. At that point, you have to use iret.

			Linus