[PATCH] powerpc: paste - Mask XERSO bit in CR

[Michael Ellerman]

Haren Myneni <haren at linux.vnet.ibm.com> writes:
>     
> NX can set 3rd bit in CR register for XER[SO] (Summation overflow)
> which is not used for paste return value. So. mask this bit to get
> proper return status.

This sounds like a bug fix, but I can't tell from the change log.

What happens if we don't merge this patch? Is it bad?

Should I add:

  Fixes: 2392c8c8c045 ("powerpc/powernv/vas: Define copy/paste interfaces")
  Cc: stable at vger.kernel.org # v4.14+


cheers

> diff --git a/arch/powerpc/platforms/powernv/copy-paste.h b/arch/powerpc/platforms/powernv/copy-paste.h
> index c9a5036..82392e3 100644
> --- a/arch/powerpc/platforms/powernv/copy-paste.h
> +++ b/arch/powerpc/platforms/powernv/copy-paste.h
> @@ -9,7 +9,8 @@
>  #include <asm/ppc-opcode.h>
>  
>  #define CR0_SHIFT	28
> -#define CR0_MASK	0xF
> +#define CR0_MASK	0xE /* 3rd bit undefined or set for XER[SO] */
> +
>  /*
>   * Copy/paste instructions:
>   *