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From: David Laight <David.Laight@ACULAB.COM>
To: "'Andy Lutomirski'" <luto@kernel.org>
CC: Peter Zijlstra <peterz@infradead.org>,
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Subject: RE: [PATCH] LDT improvements
Thread-Topic: [PATCH] LDT improvements
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Date: Fri, 8 Dec 2017 17:29:08 +0000
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From: Andy Lutomirski
> Sent: 08 December 2017 16:48
...
> I mean: if the user CS or SS is not accessed and the LDT is RO, then
> we get #PF on the IRET instruction, I think.  Dealing with that is
> truly awful.

Any fault in-kernel on the IRET is horrid.
Doesn't really matter which one.
Same goes for the 'pop %ds' (etc) that tend to precede it.

	David