On Mon, Feb 23, 2015 at 08:14:22PM +0100, Jan Kiszka wrote:
> On 2015-02-23 19:34, Gilles Chanteperdrix wrote:
> > On Mon, Feb 23, 2015 at 07:32:21PM +0100, Jan Kiszka wrote:
> >> On 2015-02-23 19:16, Jan Kiszka wrote:
> >>> On 2015-02-23 19:11, Gilles Chanteperdrix wrote:
> >>>> On Mon, Feb 23, 2015 at 07:04:25PM +0100, Gilles Chanteperdrix wrote:
> >>>>> So, finally, I propose:
> >>>>
> >>>> Mmmm. try again.
> >>>>
> >>>>>
> >>>>> static inline unsigned long ipipe_fault_entry(void)
> >>>>> {
> >>>>> unsigned long flags;
> >>>>>
> >>>>> local_irq_save(flags); /* Re-enables hw irqs */
> >>>>
> >>>> We need the explicit hard_local_irq_enable() here.
> >>
> >> And we need to fix up regs->ARM_cpsr according to flags.
> >
> > No, we have no reason to fix up regs->ARM_cpsr.
>
> do_page_fault:
> if (interrupts_enabled(regs))
> local_irq_enable();
>
> It's very valuable to study x86 on this. It may overdo some things (we
> will clean it up), but it is also very similar to ARM architecturally,
> so we can draw conclusions from that.
Ok, but it means we have to undo on exit what we did on entry,
because it is wrong to return with root stalled on a context which had
hardware irqs off.
(also note that this is the only piece of code using the PSR I bit,
mangling the bits on each exception entry/exit for only that case,
is completely overkill, better replace interrupt_enabled(regs) with
a test for the stall bit saved by ipipe_fault_entry)
--
Gilles.
_______________________________________________
Xenomai mailing list
[email protected]
http://www.xenomai.org/mailman/listinfo/xenomai
