Re: [PATCH v2 1/6] linux-user/aarch64: Extend PR_SET_TAGGED_ADDR_CTRL for FEAT_MTE3

[Richard Henderson]

On 2/7/24 00:23, Peter Maydell wrote:
> > +++ b/linux-user/aarch64/target_prctl.h
> > @@ -173,21 +173,22 @@ static abi_long 
> > do_prctl_set_tagged_addr_ctrl(CPUArchState *env, abi_long arg2)
> >       env->tagged_addr_enable = arg2 & PR_TAGGED_ADDR_ENABLE;
> >
> >       if (cpu_isar_feature(aa64_mte, cpu)) {
> > -        switch (arg2 & PR_MTE_TCF_MASK) {
> > -        case PR_MTE_TCF_NONE:
> > -        case PR_MTE_TCF_SYNC:
> > -        case PR_MTE_TCF_ASYNC:
> > -            break;
> > -        default:
> > -            return -EINVAL;
> > -        }
>
> We should probably check here and reject unknown bits being
> set in arg2, as set_tagged_addr_ctrl() does; but the old
> code didn't get that right either.

This is done higher up in this function:

    if (arg2 & ~valid_mask) {
        return -TARGET_EINVAL;
    }

The rejection of ASYNC | SYNC here was either a bug in my original implementation, or the 
kernel API changed since the initial implementation in June 2020 (not worth digging to 
find out).


r~