Re: [RFC PATCH v1] power: don't manage floating point regs when no FPU

[Christophe Leroy]

Le 11/08/2020 à 14:07, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@xxxxxxxxxx> writes:
> > There is no point in copying floating point regs when there
> > is no FPU and MATH_EMULATION is not selected.
>
> Yeah I guess you're right. I've never touched a system with neither, but
> if such a thing exists then it does seem silly to copy regs around that
> can't be used.

Yes that exists, because glibc implements floating point emulation and 
it is definitely more efficient to rely of glibc emulation than kernel one.

> >   10 files changed, 44 insertions(+), 1 deletion(-)
>
> In general this looks fine.
>
> It's a bit #ifdef heavy. Maybe some of those can be cleaned up a bit
> with some wrapper inlines?

Yes I'll try and respin, as part of a series I'm preparing to switch the 
32 bits signal code to using user_access_begin() logic and 
unsafe_put_user() and friends to reduce KUAP unlock/lock.

Christophe