Re: [Qemu-devel] [PATCH v1 15/22] target-arm: A64: Forbid ERET to increase the EL

[Peter Crosthwaite]

On Tue, May 6, 2014 at 4:08 PM, Edgar E. Iglesias
<address@hidden> wrote:
> From: "Edgar E. Iglesias" <address@hidden>
>
> Signed-off-by: Edgar E. Iglesias <address@hidden>

Reviewed-by: Peter Crosthwaite <address@hidden>

> ---
>  target-arm/op_helper.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/target-arm/op_helper.c b/target-arm/op_helper.c
> index dd9e4fc..770c776 100644
> --- a/target-arm/op_helper.c
> +++ b/target-arm/op_helper.c
> @@ -389,6 +389,7 @@ void HELPER(exception_return)(CPUARMState *env)
>      unsigned int spsr_idx = arm64_banked_spsr_index(1);
>      uint32_t spsr = env->banked_spsr[spsr_idx];
>      int new_el, i;
> +    int cur_el = arm_current_pl(env);
>
>      if (env->pstate & PSTATE_SP) {
>          env->sp_el[1] = env->xregs[31];
> @@ -410,6 +411,10 @@ void HELPER(exception_return)(CPUARMState *env)
>          env->regs[15] = env->elr_el[ELR_EL_IDX(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;
> +        }
>          if (new_el > 1) {
>              /* Return to unimplemented EL */
>              goto illegal_return;
> --
> 1.8.3.2
>
>