Re: [PATCH v2] uprobes: fix scratch register selection for rip-relative fixups

[Oleg Nesterov <oleg@redhat.com>]

On 05/02, Denys Vlasenko wrote:
>
> v2: More robust checks of vex.vvvv (32-bit mode safe),
>     simplified scratch reg selection code,
>     moved comments around as requested by Oleg.

OK, thanks. Given that this patch was acked by Jim, I am going to
apply it. I'll try to run a couple of systemtap scripts with this
patch, but unfortunately the "full" testing is simply impossible.

Denys, I'll also include your test-case into the changelog.

And,

>  static inline unsigned long *
>  scratch_reg(struct arch_uprobe *auprobe, struct pt_regs *regs)
>  {
> -	return (auprobe->def.fixups & UPROBE_FIX_RIP_AX) ? &regs->ax : &regs->cx;
> +	/* Order is important - more than one bit can be set! */

Really?

Should I remove this comment or I misread the change in riprel_analyze?

Oleg.