Hello,
On Thu, Feb 27, 2025 at 06:34:37PM -0800, Alexei Starovoitov wrote:
> > Hmm... would that mean a non-sched_ext bpf prog would be able to call e.g.
> > scx_bpf_dsq_insert()?
>
> Not as far as I can tell.
> scx_kfunc_ids_unlocked[] doesn't include scx_bpf_dsq_insert.
> It's part of scx_kfunc_ids_enqueue_dispatch[].
>
> So this bit in patch 3 enables it:
> + if ((flags & SCX_OPS_KF_ENQUEUE) &&
> + btf_id_set8_contains(&scx_kfunc_ids_enqueue_dispatch, kfunc_id))
>
> and in patch 2:
> + [SCX_OP_IDX(enqueue)] = SCX_OPS_KF_ENQUEUE,
>
> So scx_bpf_dsq_insert() kfunc can only be called out
> of enqueue() sched-ext hook.
>
> So the restriction is still the same. afaict.
Hmm... maybe I'm missing something:
static int scx_kfunc_ids_ops_context_sensitive_filter(const struct bpf_prog *prog, u32 kfunc_id)
{
u32 moff, flags;
// allow non-context sensitive kfuncs
if (!btf_id_set8_contains(&scx_kfunc_ids_ops_context_sensitive, kfunc_id))
return 0;
// allow unlocked to be called form all SYSCALL progs
if (prog->type == BPF_PROG_TYPE_SYSCALL &&
btf_id_set8_contains(&scx_kfunc_ids_unlocked, kfunc_id))
return 0;
// *** HERE, allow if the prog is not SCX ***
if (prog->type == BPF_PROG_TYPE_STRUCT_OPS &&
prog->aux->st_ops != &bpf_sched_ext_ops)
return 0;
/* prog->type == BPF_PROG_TYPE_STRUCT_OPS && prog->aux->st_ops == &bpf_sched_ext_ops*/
// other context sensitive allow's
So, I think it'd say yes if a non-SCX BPF prog tries to call a context
sensitive SCX kfunc.
Thanks.
--
tejun
