Re: [Qemu-devel] [PATCH 4/6] target-arm: Implement MDCR_EL2.TDRA traps

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

On 05.02.2016 19:45, Peter Maydell wrote:
> Implement trapping of the "debug ROM" registers, which are controlled
> by MDCR_EL2.TDRA for EL2 but by the more general MDCR_EL3.TDA for EL3.
>
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

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

> ---
>  target-arm/helper.c | 27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 18e85fd..8c2adbc 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -402,6 +402,24 @@ static CPAccessResult access_tdosa(CPUARMState *env, const ARMCPRegInfo *ri,
>      return CP_ACCESS_OK;
>  }
>  
> +/* Check for traps to "debug ROM" registers, which are controlled
> + * by MDCR_EL2.TDRA for EL2 but by the more general MDCR_EL3.TDA for EL3.
> + */
> +static CPAccessResult access_tdra(CPUARMState *env, const ARMCPRegInfo *ri,
> +                                  bool isread)
> +{
> +    int el = arm_current_el(env);
> +
> +    if (el < 2 && (env->cp15.mdcr_el2 & MDCR_TDRA)
> +        && !arm_is_secure_below_el3(env)) {
> +        return CP_ACCESS_TRAP_EL2;
> +    }
> +    if (el < 3 && (env->cp15.mdcr_el3 & MDCR_TDA)) {
> +        return CP_ACCESS_TRAP_EL3;
> +    }
> +    return CP_ACCESS_OK;
> +}
> +
>  static void dacr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value)
>  {
>      ARMCPU *cpu = arm_env_get_cpu(env);
> @@ -3774,12 +3792,15 @@ static const ARMCPRegInfo debug_cp_reginfo[] = {
>       * accessor.
>       */
>      { .name = "DBGDRAR", .cp = 14, .crn = 1, .crm = 0, .opc1 = 0, .opc2 = 0,
> -      .access = PL0_R, .type = ARM_CP_CONST, .resetvalue = 0 },
> +      .access = PL0_R, .accessfn = access_tdra,
> +      .type = ARM_CP_CONST, .resetvalue = 0 },
>      { .name = "MDRAR_EL1", .state = ARM_CP_STATE_AA64,
>        .opc0 = 2, .opc1 = 0, .crn = 1, .crm = 0, .opc2 = 0,
> -      .access = PL1_R, .type = ARM_CP_CONST, .resetvalue = 0 },
> +      .access = PL1_R, .accessfn = access_tdra,
> +      .type = ARM_CP_CONST, .resetvalue = 0 },
>      { .name = "DBGDSAR", .cp = 14, .crn = 2, .crm = 0, .opc1 = 0, .opc2 = 0,
> -      .access = PL0_R, .type = ARM_CP_CONST, .resetvalue = 0 },
> +      .access = PL0_R, .accessfn = access_tdra,
> +      .type = ARM_CP_CONST, .resetvalue = 0 },
>      /* Monitor debug system control register; the 32-bit alias is DBGDSCRext. */
>      { .name = "MDSCR_EL1", .state = ARM_CP_STATE_BOTH,
>        .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = 2, .opc2 = 2,