Re: [PATCH] MIPS Kprobes: Support branch instructions probing

[Maneesh Soni <manesoni@cisco.com>]

On Thu, Oct 13, 2011 at 03:11:38PM +0530, Ananth N Mavinakayanahalli wrote:
> On Thu, Oct 13, 2011 at 02:37:49PM +0530, Maneesh Soni wrote:
> 
> ...
> 
> I know nothing of MIPS internals, but...
>  
> >  static int __kprobes kprobe_handler(struct pt_regs *regs)
> > @@ -239,8 +531,13 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
> >  			save_previous_kprobe(kcb);
> >  			set_current_kprobe(p, regs, kcb);
> >  			kprobes_inc_nmissed_count(p);
> > -			prepare_singlestep(p, regs);
> > +			prepare_singlestep(p, regs, kcb);
> >  			kcb->kprobe_status = KPROBE_REENTER;
> > +			if (kcb->flags & SKIP_DELAYSLOT) {
> > +				resume_execution(p, regs, kcb);
> > +				restore_previous_kprobe(kcb);
> > +				preempt_enable_no_resched();
> > +			}
> >  			return 1;
> >  		} else {
> >  			if (addr->word != breakpoint_insn.word) {
> > @@ -284,8 +581,15 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
> >  	}
> > 
> >  ss_probe:
> > -	prepare_singlestep(p, regs);
> > -	kcb->kprobe_status = KPROBE_HIT_SS;
> > +	prepare_singlestep(p, regs, kcb);
> > +	if (kcb->flags & SKIP_DELAYSLOT) {
> > +		kcb->kprobe_status = KPROBE_HIT_SSDONE;
> > +		if (p->post_handler)
> > +			p->post_handler(p, regs, 0);
> > +		resume_execution(p, regs, kcb);
> 
> You are missing a preempt_disable_no_resched() here.
> 
ok.. you meant preempt_enable_no_resched(). Will add it in the next
version. Thanks for pointing it out.

Thanks
Maneesh