Re: [PATCH 05/14] target/ppc: Implement attn instruction on BookS 64-bit processors

[Nicholas Piggin]

On Sat May 18, 2024 at 9:07 PM AEST, Richard Henderson wrote:
> On 5/18/24 11:31, Nicholas Piggin wrote:
> > +static void gen_attn(DisasContext *ctx)
> > +{
> > +#if defined(CONFIG_USER_ONLY)
> > +    GEN_PRIV(ctx);
> > +#else
> > +    gen_helper_attn(tcg_env);
> > +#endif
> > +}
>
> You forgot to check priv in system mode.
> Better as
>
>      GEN_PRIV(ctx);
> #ifndef CONFIG_USER_ONLY
>      gen_helper_attn(...)
> #endif

Good catch again.

I'm actually wrong there too, it should be treated as illegal
unless it is enabled with a system SPR, in which case it's
unprivileged (it can be inserted by external hardware debuggers
to stop the CPU and get notified).

Thanks,
Nick