Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain supportto use NMI-safe methods

[H. Peter Anvin]

Linus Torvalds wrote:
> 
> 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.
> 

cs/ss you could potentially restore with sysret/sysexit, at least for
the common case.  Of course, this means more cases...

	-hpa

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