Re: [RFC PATCH] arm: force flag recalculation when messing with DAIF

[Richard Henderson]

On 2/2/22 23:23, Alex Bennée wrote:
> The recently introduced debug tests in kvm-unit-tests exposed an error
> in our handling of singlestep cause by stale hflags. This is caught by
> --enable-debug-tcg when running the tests.

You could mention that PSTATE_D is used by aa64_generate_debug_exceptions.

> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> Cc: Richard Henderson <richard.henderson@linaro.org>
> Cc: Andrew Jones <drjones@redhat.com>
> ---
>   target/arm/helper-a64.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/target/arm/helper-a64.c b/target/arm/helper-a64.c
> index d6a6fd73d9..7cf953b1e6 100644
> --- a/target/arm/helper-a64.c
> +++ b/target/arm/helper-a64.c
> @@ -83,12 +83,14 @@ void HELPER(msr_i_daifset)(CPUARMState *env, uint32_t imm)
>   {
>       daif_check(env, 0x1e, imm, GETPC());
>       env->daif |= (imm << 6) & PSTATE_DAIF;
> +    arm_rebuild_hflags(env);
>   }
>   
>   void HELPER(msr_i_daifclear)(CPUARMState *env, uint32_t imm)
>   {
>       daif_check(env, 0x1f, imm, GETPC());
>       env->daif &= ~((imm << 6) & PSTATE_DAIF);
> +    arm_rebuild_hflags(env);
>   }

You could call helper_rebuild_hflags_a64 directly, since we know that we must be in a64 
state to get here.  Regardless,

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~