[PATCH v1] ARM: A9: Add ARM ERRATA 764319 workaround

[Arnd Bergmann]

On Wed, May 11, 2022 at 2:23 PM Hawkins, Nick <nick.hawkins at hpe.com> wrote:
> On Tue, May 10, 2022 at 03:01:26PM +0200, Arnd Bergmann wrote:
> > > On Tue, May 10, 2022 at 1:53 PM Verdun, Jean-Marie <verdun at hpe.com> wrote:
> > >
> > > I got a little lost trying to find where the breakpoint instruction
> > > comes from that gets trapped here, but I would guess that they had to
> > > do this using an undef_hook because the ex_table approach does not
> > > work there for some reason.
> > >
> > > I would still pick the ex_table method here if that works.
>
> > IIRC, the ex_table handlers are called only for data aborts and are intended to be used to handle cases where we take a fault on a memory access (e.g.
> translation fault). In this case, we're taking an undefined instruction exception on a cp14 access and so the undef_hook is the right thing to use.
>
> Given Will's input would you like me to still use the ex_table method?

If it doesn't work, then there is no point trying. You could try
changing the exception
handling so it searches the ex_table for Undefined Instruction
exceptions as well,
but that's probably more complicated.

       Arnd