Re: [PATCH bpf-next v2] bpf: Propagate memory bounds to registers in atomics w/ BPF_FETCH

[Brendan Jackman]

On Tue, 2 Feb 2021 at 00:27, Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Mon, Feb 1, 2021 at 7:00 AM Brendan Jackman <jackmanb@xxxxxxxxxx> wrote:
> > +
> > +SEC("fentry/bpf_fentry_test1")
> > +int BPF_PROG(sub, int x)
> > +{
> > +       int a = 0;
> > +       int b = __sync_fetch_and_add(&a, 1);
>
> It probably needs ENABLE_ATOMICS_TESTS ?
>
> Otherwise clang without -mcpu=v3 will complain:
> "fatal error: error in backend: Invalid usage of the XADD return value"

Ah yep of course, thanks for spotting. v3 incoming...