On Sun, Dec 19, 2021 at 09:24:37AM IST, Alexei Starovoitov wrote:
> On Sat, Dec 18, 2021 at 7:01 PM Kumar Kartikeya Dwivedi
> <memxor@xxxxxxxxx> wrote:
> >
> > On Sun, Dec 19, 2021 at 07:52:48AM IST, Alexei Starovoitov wrote:
> > > On Fri, Dec 17, 2021 at 07:20:26AM +0530, Kumar Kartikeya Dwivedi wrote:
> > > >
> > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> > > > index 965fffaf0308..015cb633838b 100644
> > > > --- a/include/linux/bpf.h
> > > > +++ b/include/linux/bpf.h
> > > > @@ -521,6 +521,9 @@ struct bpf_verifier_ops {
> > > > enum bpf_access_type atype,
> > > > u32 *next_btf_id);
> > > > bool (*check_kfunc_call)(u32 kfunc_btf_id, struct module *owner);
> > > > + bool (*is_acquire_kfunc)(u32 kfunc_btf_id, struct module *owner);
> > > > + bool (*is_release_kfunc)(u32 kfunc_btf_id, struct module *owner);
> > > > + bool (*is_kfunc_ret_type_null)(u32 kfunc_btf_id, struct module *owner);
> > >
> > > Same feedback as before...
> > >
> > > Those callbacks are not necessary.
> > > The existing check_kfunc_call() is just as inconvenient.
> > > When module's BTF comes in could you add it to mod's info instead of
> > > introducing callbacks for every kind of data the module has.
> > > Those callbacks don't server any purpose other than passing the particular
> > > data set back. The verifier side should access those data sets directly.
> >
> > Ok, interesting idea. So these then go into the ".modinfo" section?
>
> It doesn't need to be a special section.
> The btf_module_notify() parses BTF.
> At the same time it can add a kfunc whitelist to "struct module".
> The btf_ids[ACQUIRE/RELEASE][] arrays will be a part of
> the "struct module" too.
> If we can do a btf name convention then this job can be
> performed generically by btf_module_notify().
> Otherwise __init of the module can populate arrays in "struct module".
>
Nice idea, I think this is better than what I am doing (it also prevents
constant researching into the list).
But IIUC I think this btf_ids array needs to go into struct btf instead,
since if module is compiled as built-in, we will not have any struct module for
it.
Then we can concatenate all sets of same type (check/acquire/release etc.) and
sort them to directly search using a single btf_id_set_contains call, the code
becomes same for btf_vmlinux or module btf. struct module is not needed anymore.
WDYT?
> > I think then
> > we can also drop the check_kfunc_call callback?
>
> Right. Would be great to remove that callback too.
Ok, will do.
--
Kartikeya
