Re: [Qemu-devel] [PATCH v2 34/68] target/arm: Convert Clear-Exclusive, Barriers

[Peter Maydell]

On Mon, 19 Aug 2019 at 22:38, Richard Henderson
<address@hidden> wrote:
>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target/arm/translate.c       | 122 +++++++++++++++--------------------
>  target/arm/a32-uncond.decode |  10 +++
>  target/arm/t32.decode        |  10 +++
>  3 files changed, 73 insertions(+), 69 deletions(-)
>
> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index e268c5168d..6489bbc09c 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -10038,6 +10038,58 @@ static bool trans_SRS(DisasContext *s, arg_SRS *a)
>      return true;
>  }
>
> +/*
> + * Clear-Exclusive, Barriers
> + */
> +
> +static bool trans_CLREX(DisasContext *s, arg_CLREX *a)
> +{
> +    if (!ENABLE_ARCH_6K) {
> +        return false;
> +    }
> +    gen_clrex(s);
> +    return true;
> +}
> +
> +static bool trans_DSB(DisasContext *s, arg_DSB *a)
> +{
> +    if (!s->thumb && !ENABLE_ARCH_7) {
> +        return false;
> +    }
> +    tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
> +    return true;
> +}
> +
> +static bool trans_DMB(DisasContext *s, arg_DMB *a)
> +{
> +    return trans_DSB(s, NULL);
> +}
> +
> +static bool trans_ISB(DisasContext *s, arg_ISB *a)
> +{
> +    /*
> +     * We need to break the TB after this insn to execute
> +     * self-modifying code correctly and also to take
> +     * any pending interrupts immediately.
> +     */
> +    gen_goto_tb(s, 0, s->base.pc_next);
> +    return true;
> +}

The guard conditions on these don't look right for the
Thumb case -- the old Thumb decoder has them exist only if
we have feature V7 or feature M. Are they really equivalent?


> diff --git a/target/arm/t32.decode b/target/arm/t32.decode
> index c8a8aeceee..18c268e712 100644
> --- a/target/arm/t32.decode
> +++ b/target/arm/t32.decode
> @@ -305,6 +305,16 @@ CLZ              1111 1010 1011 ---- 1111 .... 1000 .... 
>      @rdm
>        # of the space is "reserved hint, behaves as nop".
>        NOP        1111 0011 1010 1111 1000 0000 ---- ----
>      }
> +
> +    # Miscelaneous control

"Miscellaneous"

> +    {
> +      CLREX      1111 0011 1011 1111 1000 1111 0010 1111
> +      DSB        1111 0011 1011 1111 1000 1111 0100 ----
> +      DMB        1111 0011 1011 1111 1000 1111 0101 ----
> +      ISB        1111 0011 1011 1111 1000 1111 0110 ----
> +      SB         1111 0011 1011 1111 1000 1111 0111 0000
> +    }


Otherwise
Reviewed-by: Peter Maydell <address@hidden>

thanks
-- PMM