Re: [PATCH v2 09/16] powerpc/watchpoint: Convert thread_struct->hw_brk to an array

[Ravi Bangoria]

> > Â static void set_debug_reg_defaults(struct thread_struct *thread)
> > Â {
> > -ÂÂÂ thread->hw_brk.address = 0;
> > -ÂÂÂ thread->hw_brk.type = 0;
> > -ÂÂÂ thread->hw_brk.len = 0;
> > -ÂÂÂ thread->hw_brk.hw_len = 0;
> > -ÂÂÂ if (ppc_breakpoint_available())
> > -ÂÂÂÂÂÂÂ set_breakpoint(&thread->hw_brk);
> > +ÂÂÂ int i;
> > +
> > +ÂÂÂ for (i = 0; i < nr_wp_slots(); i++) {
>
> Maybe you could add the following that you added other places:
>
>  ÂÂÂÂstruct arch_hw_breakpoint null_brk = {0};
>
> Then do
>
>  ÂÂÂÂthread->hw_brk[i] = null_brk;

Yes that's better.

[...]

> > +static void switch_hw_breakpoint(struct task_struct *new)
> > +{
> > +ÂÂÂ int i;
> > +
> > +ÂÂÂ for (i = 0; i < nr_wp_slots(); i++) {
> > +ÂÂÂÂÂÂÂ if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk[i]),
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &new->thread.hw_brk[i]))) {
> > +ÂÂÂÂÂÂÂÂÂÂÂ __set_breakpoint(&new->thread.hw_brk[i], i);
> > +ÂÂÂÂÂÂÂ }
>
> Or could be:
>
>  ÂÂÂÂÂÂÂ if (likely(hw_brk_match(this_cpu_ptr(&current_brk[i]),
>  ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &new->thread.hw_brk[i])))
>  ÂÂÂÂÂÂÂÂÂÂÂ continue;
>  ÂÂÂÂÂÂÂ __set_breakpoint(&new->thread.hw_brk[i], i);

Sure.

[...]

> > @@ -128,8 +131,10 @@ static void do_signal(struct task_struct *tsk)
> > ÂÂÂÂÂÂ * user space. The DABR will have been cleared if it
> > ÂÂÂÂÂÂ * triggered inside the kernel.
> > ÂÂÂÂÂÂ */
> > -ÂÂÂ if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
> > -ÂÂÂÂÂÂÂ __set_breakpoint(&tsk->thread.hw_brk, 0);
> > +ÂÂÂ for (i = 0; i < nr_wp_slots(); i++) {
> > +ÂÂÂÂÂÂÂ if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
> > +ÂÂÂÂÂÂÂÂÂÂÂ __set_breakpoint(&tsk->thread.hw_brk[i], i);
> > +ÂÂÂ }
>
> thread.hwbrk also exists when CONFIG_PPC_ADV_DEBUG_REGS is selected.
>
> You could replace the #ifndef CONFIG_PPC_ADV_DEBUG_REGS by an if (!IS_ENABLED(CONFIG_PPC_ADV_DEBUG_REGS)) and then no need of an ifdef when declaring the int i;

Makes sense. Will change it.

Ravi