Subject: Re: [PATCH] powerpc/32: indirect function call use bctrl rather than blrl in ret_from_kernel_thread

From: Segher Boessenkool <[email-masked]>
Date: Fri, 20 Aug 2021 13:12:01 -0500

On Fri, Aug 20, 2021 at 12:18:45PM -0500, Segher Boessenkool wrote:
> On Fri, Aug 20, 2021 at 10:15:11PM +1000, Michael Ellerman wrote:
> > Christophe Leroy <[email-masked]> writes:
> > > Copied from commit 89bbe4c798bc ("powerpc/64: indirect function call
> > > use bctrl rather than blrl in ret_from_kernel_thread")
> > >
> > > blrl is not recommended to use as an indirect function call, as it may
> > > corrupt the link stack predictor.
> > 
> > Do we know if any 32-bit CPUs have a link stack predictor or similar?
> 
> 74xx do.

7450 and later, that is.  Will I ever get that right, sigh.

Segher