Re: [PATCH] target/arm: Correct the encoding of MDCCSR_EL0

[Peter Maydell]

On Tue, 29 Jun 2021 at 09:27, <hn...@vmware.com> wrote:
>
> Signed-off-by: Nick Hudson <hn...@vmware.com>
> ---
>  target/arm/helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index a66c1f0b9e..7267af7924 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -6330,7 +6330,7 @@ static const ARMCPRegInfo debug_cp_reginfo[] = {
>       * We don't implement the configurable EL0 access.
>       */
>      { .name = "MDCCSR_EL0", .state = ARM_CP_STATE_BOTH,
> -      .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = 1, .opc2 = 0,
> +      .cp = 14, .opc0 = 2, .opc1 = 3, .crn = 0, .crm = 1, .opc2 = 0,
>        .type = ARM_CP_ALIAS,
>        .access = PL1_R, .accessfn = access_tda,
>        .fieldoffset = offsetof(CPUARMState, cp15.mdscr_el1), },

This fixes the encoding for AArch64, but breaks it for AArch32,
where it is cp=14 opc1=0 crn=0 crm=1 opc2=0. Because this is one of
those system registers where the AArch64 and AArch32 encodings
don't match up, to fix the AArch64 encoding we need to replace
this ARM_CP_STATE_BOTH reginfo with separate reginfo for
ARM_CP_STATE_AA32 and ARM_CP_STATE_AA64, something like this:

    { .name = "MDCCSR_EL0", .state = ARM_CP_STATE_AA64,
      .opc0 = 2, .opc1 = 3, .crn = 0, .crm = 1, .opc2 = 0,
      .type = ARM_CP_ALIAS,
      .access = PL1_R, .accessfn = access_tda,
      .fieldoffset = offsetof(CPUARMState, cp15.mdscr_el1), },
    { .name = "DBGDSCRint", .state = ARM_CP_STATE_AA32,
      .cp = 14, .opc0 = 2, .opc1 = 0, .crn = 0, .crm = 1, .opc2 = 0,
      .type = ARM_CP_ALIAS,
      .access = PL1_R, .accessfn = access_tda,
      .fieldoffset = offsetoflow32(CPUARMState, cp15.mdscr_el1), },

thanks
-- PMM