Re: [Qemu-devel] [PATCH v2 06/23] target-arm: add arm_is_secure() function

[Sergey Fedorov <serge.fdrv@gmail.com>]

On 13.05.2014 20:15, Fabian Aggeler wrote:
> arm_is_secure() function allows to determine CPU security state
> if the CPU implements Security Extensions.
>
> Signed-off-by: Sergey Fedorov <s.fedorov@samsung.com>
> Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch>
> ---
>  target-arm/cpu.h | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
>
> diff --git a/target-arm/cpu.h b/target-arm/cpu.h
> index a56d3d6..6ea0432 100644
> --- a/target-arm/cpu.h
> +++ b/target-arm/cpu.h
> @@ -640,6 +640,21 @@ static inline int arm_feature(CPUARMState *env, int feature)
>      return (env->features & (1ULL << feature)) != 0;
>  }
>  
> +/* Return true if the processor is in secure state */
> +static inline bool arm_is_secure(CPUARMState *env)
> +{
> +#if !defined(CONFIG_USER_ONLY)
> +    if (arm_feature(env, ARM_FEATURE_SECURITY_EXTENSIONS)) {

I think feature test can be safely avoided here. Without this feature
that should be no way to switch to monitor mode and to access SCR register.

> +        return ((env->uncached_cpsr & CPSR_M) == ARM_CPU_MODE_MON) ||
> +                !(env->cp15.c1_scr & 1);
> +    } else {
> +        return false;
> +    }
> +#else
> +    return false;

That is a good question how to treat user emulation: secure or
non-secure. Perhaps assuming user emulation in secure state may simplify
code in the following patches.

> +#endif
> +}
> +
>  /* Return true if the specified exception level is running in AArch64 state. */
>  static inline bool arm_el_is_aa64(CPUARMState *env, int el)
>  {

Thanks,
Sergey.