Re: [PATCH bpf-next v1 06/10] bpf: Implement bpf_throw kfunc

[Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>]

On Mon, Jul 17, 2023 at 9:44 AM Kumar Kartikeya Dwivedi
<memxor@xxxxxxxxx> wrote:
> > >
> > > -static void push_callee_regs(u8 **pprog, bool *callee_regs_used)
> > > +static void push_callee_regs(u8 **pprog, bool *callee_regs_used, bool force)
> > >  {
> > >       u8 *prog = *pprog;
> > >
> > > -     if (callee_regs_used[0])
> > > +     if (callee_regs_used[0] || force)
> > >               EMIT1(0x53);         /* push rbx */
> > > -     if (callee_regs_used[1])
> > > +     if (force)
> > > +             EMIT2(0x41, 0x54);   /* push r12 */
> >
> > let's make r12 push/pop explicit. In addition to push_callee_regs.
> >
>
> Ack (I'm understanding you mean adding a push/pop_r12 and using that).

I mean keep push_callee_regs() as saving bpf callee regs only and
add other helpers to save/restore r12.
Or just open code push/pop of r12.