Re: [Qemu-devel] [PATCH v3 04/32] target-arm: add arm_is_secure() function

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

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I suggested to combine arm_is_secure() and arm_is_secure_below_el3().
Since the code follows the v8 pseudo code my suggestion is really not a
good idea. So I apologize twice for wasting your time :)

// Sergey

12.06.2014 22:35, Greg Bellows wrote:
> To make sure I understand, you are proposing that we simply use the
> return from arm_current_pl of 3 to indicate isSecure?
>
> Fabian's code closely follows the v8 spec pseudo code.  I believe the
> case that would be omitted if we let a return of 3 mean "secure" is
> the case where we are in EL0/1 with SCR.NS=0.
>
> So, the to functions are not quite identical.  In the case of
> arm_current_pl, it returns the PL regardless of the SCR.NS bit.  In
> the case of arm_is_secure, the secure state takes into consideration
> both the PL and the SCR.NS setting.
>
>
> On 12 June 2014 12:26, Sergey Fedorov <serge.fdrv@gmail.com
> <mailto:serge.fdrv@gmail.com>> wrote:
>
>     Hi Greg,
>
>     I'm sorry, I wasn't thoughtful enough and missed that.
>     I would just suggest to combine that functions since they have a
>     common part, i.e.:
>
>         if (arm_feature(env, ARM_FEATURE_EL3)) {
>             ...
>
>     What do you think?
>
>     // Sergey
>
>     12.06.2014 20:26, Greg Bellows пишет:
>
>>     Hi Sergey,
>>
>>     I think I am missing your point.  In patch 6 arm_current_pl calls
>>     arm_is_secure.  Can you elaborate?
>>
>>     Greg
>>
>>
>>     On 11 June 2014 07:17, Sergey Fedorov <serge.fdrv@gmail.com
>>     <mailto:serge.fdrv@gmail.com>> wrote:
>>
>>         On 11.06.2014 03:54, Fabian Aggeler wrote:
>>         > arm_is_secure() function allows to determine CPU security state
>>         > if the CPU implements Security Extensions/EL3.
>>         > arm_is_secure_below_el3() returns true if CPU is in secure
>>         state
>>         > below EL3.
>>         >
>>         > Signed-off-by: Sergey Fedorov <s.fedorov@samsung.com
>>         <mailto:s.fedorov@samsung.com>>
>>         > Signed-off-by: Fabian Aggeler <aggelerf@ethz.ch
>>         <mailto:aggelerf@ethz.ch>>
>>         > ---
>>         >  target-arm/cpu.h | 38 ++++++++++++++++++++++++++++++++++++++
>>         >  1 file changed, 38 insertions(+)
>>         >
>>         > diff --git a/target-arm/cpu.h b/target-arm/cpu.h
>>         > index 903aa01..cb0da6b 100644
>>         > --- a/target-arm/cpu.h
>>         > +++ b/target-arm/cpu.h
>>         > @@ -710,6 +710,44 @@ static inline int
>>         arm_feature(CPUARMState *env, int feature)
>>         >      return (env->features & (1ULL << feature)) != 0;
>>         >  }
>>         >
>>         > +
>>         > +/* Return true if exception level below EL3 is in secure
>>         state */
>>         > +static inline bool arm_is_secure_below_el3(CPUARMState *env)
>>         > +{
>>         > +#if !defined(CONFIG_USER_ONLY)
>>         > +    if (arm_feature(env, ARM_FEATURE_EL3)) {
>>         > +        return !(env->cp15.scr_el3 & SCR_NS);
>>         > +    } else if (arm_feature(env, ARM_FEATURE_EL2)) {
>>         > +        return false;
>>         > +    } else {
>>         > +        /* IMPDEF: QEMU defaults to non-secure */
>>         > +        return false;
>>         > +    }
>>         > +#else
>>         > +    return false;
>>         > +#endif
>>         > +}
>>         > +
>>         > +/* 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_EL3)) {
>>         > +        if (env->aarch64 && extract32(env->pstate, 2, 2)
>>         == 3) {
>>         > +            /* CPU currently in Aarch64 state and EL3 */
>>         > +            return true;
>>         > +        } else if (!env->aarch64 &&
>>         > +                (env->uncached_cpsr & CPSR_M) ==
>>         ARM_CPU_MODE_MON) {
>>         > +            /* CPU currently in Aarch32 state and monitor
>>         mode */
>>         > +            return true;
>>         > +        }
>>
>>         Hi Fabian,
>>
>>         Why don't use arm_current_pl() from patch 6 to determine EL here?
>>
>>         Best regards,
>>         Sergey
>>
>>         > +    }
>>         > +    return arm_is_secure_below_el3(env);
>>         > +#else
>>         > +    return false;
>>         > +#endif
>>         > +}
>>         > +
>>         >  /* Return true if the specified exception level is running
>>         in AArch64 state. */
>>         >  static inline bool arm_el_is_aa64(CPUARMState *env, int el)
>>         >  {
>>
>>
>
>


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