Re: [Qemu-devel] [PATCH 03/17] target/arm: Add MTE system registers

[Peter Maydell]

On Sun, 10 Feb 2019 at 01:23, Richard Henderson
<address@hidden> wrote:
>
> On 2/5/19 11:27 AM, Peter Maydell wrote:
> >> +++ b/target/arm/translate-a64.c
> >> @@ -1668,6 +1668,17 @@ static void handle_msr_i(DisasContext *s, uint32_t 
> >> insn,
> >>          s->base.is_jmp = DISAS_UPDATE;
> >>          break;
> >>
> >> +    case 0x1c: /* TCO */
> >> +        if (!dc_isar_feature(aa64_mte_insn_reg, s)) {
> >> +            goto do_unallocated;
> >> +        }
> >> +        if (crm & 1) {
> >> +            set_pstate_bits(PSTATE_TCO);
> >> +        } else {
> >> +            clear_pstate_bits(PSTATE_TCO);
> >> +        }
> >> +        break;
> > Don't we need to break the TB here or something to pick up
> > the new value of TCO when we generate code for a following
> > load or store ? (TCO is self-synchronizing so there is no
> > requirement for an ISB before it takes effect.)
>
> Actually, we already break the TB here by default.

Do we? I didn't see any code (apart from the handling
in the DAIFSet/Clear codepaths, which aren't used for TCO).

thanks
-- PMM