Re: [PATCH] target/arm: Set ISSIs16Bit in make_issinfo

[Peter Maydell]

On Thu, 19 Dec 2019 at 18:56, Richard Henderson
<address@hidden> wrote:
>
> During the conversion to decodetree, the setting of
> ISSIs16Bit got lost.  This causes the guest os to
> incorrectly adjust trapping memory operations.
>
> Fixes: 46beb58efbb8a2a32
> Cc: address@hidden
> Reported-by: Jeff Kubascik <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  target/arm/translate.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/target/arm/translate.c b/target/arm/translate.c
> index 2b6c1f91bf..9f0afbdb75 100644
> --- a/target/arm/translate.c
> +++ b/target/arm/translate.c
> @@ -8556,6 +8556,9 @@ static ISSInfo make_issinfo(DisasContext *s, int rd, 
> bool p, bool w)
>      /* ISS not valid if writeback */
>      if (p && !w) {
>          ret = rd;
> +        if (s->base.pc_next - s->pc_curr == 2) {
> +            ret |= ISSIs16Bit;
> +        }
>      } else {
>          ret = ISSInvalid;
>      }
> --
> 2.20.1

This is correct, and fixes the regression vs 46beb58efbb8a,
but I agree with Jeff that it's not sufficient (and in fact
we've always been reporting wrong ISS info as a result)
because of the wrong sense of the bool argument to
syn_data_abort_with_iss() in merge_syn_data_abort().

thanks
-- PMM