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SubjectRe: [patch 00/11] x86/vdso: Cleanups, simmplifications and CLOCK_TAI support
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On 09/14/2018 03:05 PM, Thomas Gleixner wrote:
> On Fri, 14 Sep 2018, Florian Weimer wrote:
>
>> On 09/14/2018 02:50 PM, Thomas Gleixner wrote:
>>> Matt attempted to add CLOCK_TAI support to the VDSO clock_gettime()
>>> implementation, which extended the clockid switch case and added yet
>>> another slightly different copy of the same code.
>>>
>>> Especially the extended switch case is problematic as the compiler tends to
>>> generate a jump table which then requires to use retpolines.
>>
>> Does vDSO code really have to use retpolines? It's in userspace, after all.
>
> Unless you have IBRS/STIPB enabled, you need user space ratpoutine as well.

I don't think this is a consensus position, and it obviously depends on
the (sub)architecture.

Thanks,
Florian

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