Re: [PATCH v1 03/16] powerpc/32: move LOAD_MSR_KERNEL() into head_32.h and use it

[Christophe Leroy]

Le 11/02/2019 Ã 01:21, Benjamin Herrenschmidt a ÃcritÂ:
> On Fri, 2019-02-08 at 12:52 +0000, Christophe Leroy wrote:
> >   /*
> > + * MSR_KERNEL is > 0x8000 on 4xx/Book-E since it include MSR_CE.
> > + */
> > +.macro __LOAD_MSR_KERNEL r, x
> > +.if \x >= 0x8000
> > +       lis \r, (\x)@h
> > +       ori \r, \r, (\x)@l
> > +.else
> > +       li \r, (\x)
> > +.endif
> > +.endm
> > +#define LOAD_MSR_KERNEL(r, x) __LOAD_MSR_KERNEL r, x
> > +
>
> You changed the limit from >= 0x10000 to >= 0x8000 without a
> corresponding explanation as to why...

Yes, the existing LOAD_MSR_KERNEL() was buggy because 'li' takes a 
signed u16, ie between -0x8000 and 0x7999.

By chance it was working because until now nobody was trying to set 
MSR_KERNEL | MSR_EE.

Christophe