Re: [Qemu-devel] [PATCH v3 15/22] target-arm: A64: Forbid ERET to unimplemented ELs

["Edgar E. Iglesias" <edgar.iglesias@gmail.com>]

On Wed, May 21, 2014 at 08:06:32PM +0100, Peter Maydell wrote:
> On 19 May 2014 10:22, Edgar E. Iglesias <edgar.iglesias@gmail.com> wrote:
> > From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
> >
> > Check for EL2 support before returning to it.
> >
> > Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
> > Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> > ---
> >  target-arm/op_helper.c | 11 +++++------
> >  1 file changed, 5 insertions(+), 6 deletions(-)
> >
> > diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> > index a6eedb2..d89755a 100644
> > --- a/target-arm/op_helper.c
> > +++ b/target-arm/op_helper.c
> > @@ -411,12 +411,11 @@ void HELPER(exception_return)(CPUARMState *env)
> >          env->regs[15] = env->elr_el[1] & ~0x1;
> >      } else {
> >          new_el = extract32(spsr, 2, 2);
> > -        if (new_el > cur_el) {
> > -            /* Disallow returns to higher ELs than the current one.  */
> > -            goto illegal_return;
> > -        }
> 
> ...you just added this if() in the previous patch. Suggest
> squashing the two together.

Squashed

> 
> > -        if (new_el > 1) {
> > -            /* Return to unimplemented EL */
> > +        if (new_el > cur_el
> > +            || (new_el == 2 && !arm_feature(env, ARM_FEATURE_EL2))) {
> > +            /* Disallow return to an EL which is unimplemented or higher
> > +             * than the current one.
> > +             */
> >              goto illegal_return;
> >          }
> >          if (extract32(spsr, 1, 1)) {
> > --
> > 1.8.3.2
> >
> 
> thanks
> -- PMM