Re: [PATCH 4.4 15/50] s390/alternative: use a copy of the facility bit mask

[Greg Kroah-Hartman]

On Fri, May 04, 2018 at 09:37:20AM +0200, Jiri Slaby wrote:
> On 04/27/2018, 03:58 PM, Greg Kroah-Hartman wrote:
> > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
> > 
> > 
> > [ Upstream commit cf1489984641369611556bf00c48f945c77bcf02 ]
> > 
> > To be able to switch off specific CPU alternatives with kernel parameters
> > make a copy of the facility bit mask provided by STFLE and use the copy
> > for the decision to apply an alternative.
> ...
> > --- a/arch/s390/include/asm/facility.h
> > +++ b/arch/s390/include/asm/facility.h
> > @@ -13,6 +13,24 @@
> >  
> >  #define MAX_FACILITY_BIT (256*8)	/* stfle_fac_list has 256 bytes */
> 
> I wonder if the below (plus __test_facility) is correct in 4.4, given
> MAX_FACILITY_BIT is defined as such and not as sizeof(stfle_fac_list *
> 8) as in upstream?

I'm going to defer to Marin here, as he did the backport...
Martin?

thanks,

greg k-h