Re: [PATCH] rust: fwctl: declare cfi_encoding for fwctl_rpc_scope

[Zhi Wang <zhiw@nvidia.com>]

On Tue, 20 Oct 2026 11:04:43 +0200
Alice Ryhl <aliceryhl@google.com> wrote:

> On Tue, Oct 20, 2026 at 10:56 AM Zhi Wang <zhiw@nvidia.com> wrote:
> >
> > On Tue, 20 Oct 2026 08:28:37 +0000
> > Alice Ryhl <aliceryhl@google.com> wrote:
> >  
> > > Currently, VTable::fw_rpc_callback() takes scope as a u32,
> > > whereas C calls fwctl_ops::fw_rpc with enum fwctl_rpc_scope. With
> > > kCFI enabled, enum types are encoded distinctly from integers,
> > > causing every fw_rpc indirect call into a Rust fwctl driver to
> > > trip a CFI failure. Thus, generate fwctl_rpc_scope as a newtype
> > > with a cfi_encoding attribute and use it in fw_rpc_callback().
> > >  
> >
> > Thanks for the fix. Looks good to me.
> >
> > Reviewed-by: Zhi Wang <zhiw@nvidia.com>
> >
> > BTW: I saw this “lru_status” needs the same treatment, guess bindgen
> > will someday automatically handle this?  
> 
> I believe lru_status is already handled.
> 

Yes, lru_status is already handled.

I meant that both lru_status and fwctl_rpc_scope need explicit entries
in rust/bindgen_parameters. I was wondering whether there are plans for
bindgen to generate the newtype and matching CFI encoding automatically
for enums used in function-pointer signatures, so future additions
wouldn't need the same manual setup.

> Alice
>