Re: [XEN PATCH v2 4/7] xen/arm: traps: add ASSERT_UNREACHABLE() where needed

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 18 Dec 2023, Nicola Vetrini wrote:
> The statements after a call to the noreturn function 'do_unexpected_trap'
> can't be reached, thus violating MISRA C:2012 Rule 2.1
> ("A project shall not contain unreachable code.").
> ASSERT_UNREACHABLE() is used to signal that the unreachable break-s are used 
> as
> a defensive coding measure to prevent inadvertent fallthrough.
> 
> Signed-off-by: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> Changes in v2:
> - Use ASSERT_UNREACHABLE() to prevent mistakes.
> ---
>  xen/arch/arm/traps.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 3784e8276ef6..77220ba0927a 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -2152,6 +2152,7 @@ void do_trap_hyp_sync(struct cpu_user_regs *regs)
>      case HSR_EC_SVE:
>          /* An SVE exception is a bug somewhere in hypervisor code */
>          do_unexpected_trap("SVE trap at EL2", regs);
> +        ASSERT_UNREACHABLE();
>          break;
>  #endif
>      case HSR_EC_DATA_ABORT_CURR_EL:
> @@ -2171,7 +2172,7 @@ void do_trap_hyp_sync(struct cpu_user_regs *regs)
>              dump_hyp_walk(get_hfar(is_data));
>  
>          do_unexpected_trap(fault, regs);
> -
> +        ASSERT_UNREACHABLE();
>          break;
>      }
>      default:
> -- 
> 2.34.1
>