On Sun, Nov 28, 2021 at 9:41 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > On Wed, Nov 24, 2021 at 01:51:36PM -0800, Andrii Nakryiko wrote: > > On Mon, Nov 22, 2021 at 12:15 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote: > > > > > > On Thu, Nov 18, 2021 at 08:11:59PM -0800, Alexei Starovoitov wrote: > > > > On Thu, Nov 18, 2021 at 12:24:35PM +0100, Jiri Olsa wrote: > > > > > + > > > > > +DEFINE_BPF_MULTI_FUNC(unsigned long a1, unsigned long a2, > > > > > + unsigned long a3, unsigned long a4, > > > > > + unsigned long a5, unsigned long a6) > > > > > > > > This is probably a bit too x86 specific. May be make add all 12 args? > > > > Or other places would need to be tweaked? > > > > > > I think si, I'll check > > > > > > > > > > > > +BTF_ID_LIST_SINGLE(bpf_multi_func_btf_id, func, bpf_multi_func) > > > > ... > > > > > - prog->aux->attach_btf_id = attr->attach_btf_id; > > > > > + prog->aux->attach_btf_id = multi_func ? bpf_multi_func_btf_id[0] : attr->attach_btf_id; > > > > > > > > Just ignoring that was passed in uattr? > > > > Maybe instead of ignoring dopr BPF_F_MULTI_FUNC and make libbpf > > > > point to that btf_id instead? > > > > Then multi or not can be checked with if (attr->attach_btf_id == bpf_multi_func_btf_id[0]). > > > > > > > > > > nice idea, it might fit better than the flag > > > > Instead of a flag we can also use a different expected_attach_type > > (FENTRY vs FENTRY_MULTI, etc). > > right, you already asked for that - https://lore.kernel.org/bpf/YS9k26rRcUJVS%2Fvx@krava/ > > I still think it'd mean more code while this way we just use > current fentry/fexit code paths with few special handling > for multi programs > I don't see how it makes much difference for kernel implementation. Checking expected_attach_type vs checking prog_flags is about the same amount of code. The big advantage of new expected_attach_type (or prog_type) is that it will be very obvious in all sorts of diagnostics tooling (think bpftool prog show output, etc). prog_flags are almost invisible and it will be the last thing that users will think about. I'd try to minimize the usage of prog_flags overall. > > As for attach_btf_id, why can't we just > > enforce it as 0? > > there's prog->aux->attach_func_proto that needs to be set based > on attach_btf_id, and is checked later in btf_ctx_access right: if (attach_btf_id == 0) prog->aux->attach_func_proto = &special_func_model_or_proto_or_whatever_that_does_not_have_to_be_known_to_libbpf_and_outside_world_ever; ;) let's keep implementation details as internal implementation details, instead of dumping all that to UAPI > > jirka > > > > > > > > > thanks, > > > jirka > > > > > >
