Re: [PATCH] x86/asm/entry/32: Restore %ss before SYSRETL if necessary

[H. Peter Anvin]

On 04/23/2015 03:29 PM, Andy Lutomirski wrote:
>>
>> Yes, the NULL SS is a special thing in 64-bit mode.  I agree that
>> context-switching it is probably the way to go; it should be cheap
>> enough.  We might even be able to conditionalize it on an X86_BUG_ flag.
> 
> I still don't see why context switches are a better place than just
> before sysret, but I could be convinced.
> 

Because there are way more sysrets than context switches, and Linux is
particularly sensitive to system call latency, by design.

	-hpa

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