Re: [PATCH] x86/asm/entry/64: better check for canonical address

[Ingo Molnar]

* Brian Gerst <brgerst@xxxxxxxxx> wrote:

> > Btw., there's a neat trick we could do: in the HLT, MWAIT and 
> > ACPI-idle code we could attempt to set up RCX to match RIP, to 
> > trigger this optimization in the common 'irq interrupted the idle 
> > task' case?
> 
> sysret only returns to CPL3.

Indeed, an IRET ought to be pretty cheap for same-ring interrupt 
returns in any case.

Thanks,

	Ingo
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