On Thu, Mar 14, 2024 at 1:06 PM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
> >
> > > What could work and what I am proposing is to pass a list of bound
> > > maps in prog_load attributes. Then such maps can be used during the
> > > verification. For normal maps
> > >
> > > prog = prog_load(attr={.bound_maps=maps})
> > >
> > > will be semantically the same as
> > >
> > > prog = prog_load()
> > > bpf_prog_bind_map(prog, maps)
> >
> > Instead of a whole new api, let's make libbpf insert
> > ld_imm64 r0, map
> > as the first insn for this case for now.
>
> This sounds like a big hack and unnecessary complication, tbh. I'd
> like to avoid having to do this in libbpf.
>
> But I think we almost have this already supported. In BPF_PROG_LOAD
> UAPI we have fd_array property, right? I think right now we lazily
> refcnt referenced maps. But I think it makes total sense to just
> define that bpf_prog will keep references to all BPF objects passed in
> through fd_array, WDYT? Verifier will just iterate all provided FDs,
> determine kind of BPF object it is (and reject unknown ones), and then
> just take refcnts on each of them once. On prog free we'll just do the
> same in reverse and be done with it.
>
> It also can be used as a batch and single-step (in the sense it will
> be done as part of program load instead of a separate command)
> alternative for bpf_prog_bind_map(), I suppose.
fd_array approach also works. There can be map and btf fds in there.
I would only bind maps this way.
