Re: [PATCH bpf-next 1/2] arm64/ftrace,bpf: Fix partial regs after bpf_prog_run

[Jiri Olsa <olsajiri@gmail.com>]

On Wed, Jan 07, 2026 at 11:03:52AM -0500, Steven Rostedt wrote:
> On Wed,  7 Jan 2026 10:32:55 +0100
> Jiri Olsa <jolsa@kernel.org> wrote:
> 
> > diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
> > index 1621c84f44b3..177c7bbf3b84 100644
> > --- a/arch/arm64/include/asm/ftrace.h
> > +++ b/arch/arm64/include/asm/ftrace.h
> > @@ -157,6 +157,30 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
> >  	return regs;
> >  }
> >  
> 
> See my reply in the other email thread:
> 
>   https://lore.kernel.org/all/20260107105316.2b70a308@gandalf.local.home/

ah ok, thanks

jirka

> 
> -- Steve
> 
> 
> > +/*
> > + * ftrace_partial_regs_update - update the original ftrace_regs from regs
> > + * @fregs: The ftrace_regs to update from @regs
> > + * @regs: The partial regs from ftrace_partial_regs() that was updated
> > + *
> > + * Some architectures have the partial regs living in the ftrace_regs
> > + * structure, whereas other architectures need to make a different copy
> > + * of the @regs. If a partial @regs is retrieved by ftrace_partial_regs() and
> > + * if the code using @regs updates a field (like the instruction pointer or
> > + * stack pointer) it may need to propagate that change to the original @fregs
> > + * it retrieved the partial @regs from. Use this function to guarantee that
> > + * update happens.
> > + */
> > +static __always_inline void
> > +ftrace_partial_regs_update(const struct ftrace_regs *fregs, struct pt_regs *regs)
> > +{
> > +	struct __arch_ftrace_regs *afregs = arch_ftrace_regs(fregs);
> > +
> > +	if (afregs->pc != regs->pc) {
> > +		afregs->pc = regs->pc;
> > +		afregs->regs[0] = regs->regs[0];
> > +	}
> > +}