Re: [Qemu-arm] [PATCH 11/11] target-arm: Make Monitor->NS PL1 mode changes illegal if HCR.TGE is 1

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

On 15.02.2016 20:22, Peter Maydell wrote:
> If HCR.TGE is 1 then mode changes via CPS and MSR from Monitor to
> NonSecure PL1 modes are illegal mode changes. Implement this check
> in bad_mode_switch().
>
> (We don't currently implement HCR.TGE, but this is the only missing
> check from the v8 ARM ARM G1.9.3 and so it's worth adding now; the
> rest of the HCR.TGE checks can be added later as necessary.)
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Sergey Fedorov <serge.fdrv@gmail.com>

> ---
>  target-arm/helper.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index e1af9d5..93a0b63 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -5182,6 +5182,7 @@ static int bad_mode_switch(CPUARMState *env, int mode, CPSRWriteType write_type)
>  
>      switch (mode) {
>      case ARM_CPU_MODE_USR:
> +        return 0;
>      case ARM_CPU_MODE_SYS:
>      case ARM_CPU_MODE_SVC:
>      case ARM_CPU_MODE_ABT:
> @@ -5191,6 +5192,15 @@ static int bad_mode_switch(CPUARMState *env, int mode, CPSRWriteType write_type)
>          /* Note that we don't implement the IMPDEF NSACR.RFR which in v7
>           * allows FIQ mode to be Secure-only. (In v8 this doesn't exist.)
>           */
> +        /* If HCR.TGE is set then changes from Monitor to NS PL1 via MSR
> +         * and CPS are treated as illegal mode changes.
> +         */
> +        if (write_type == CPSRWriteByInstr &&
> +            (env->cp15.hcr_el2 & HCR_TGE) &&
> +            (env->uncached_cpsr & CPSR_M) == ARM_CPU_MODE_MON &&
> +            !arm_is_secure_below_el3(env)) {
> +            return 1;
> +        }
>          return 0;
>      case ARM_CPU_MODE_HYP:
>          return !arm_feature(env, ARM_FEATURE_EL2)