Re: [RFC bpf-next v1 3/8] bpf, x86: no_caller_saved_registers for bpf_get_smp_processor_id()

Eduard Zingerman
2024-07-02T21:25:13Z

On Tue, 2024-07-02 at 14:11 -0700, Andrii Nakryiko wrote:

[...]

> > > > +#ifdef CONFIG_X86_64
> > > > + case BPF_FUNC_get_smp_processor_id:
> > > > + return env->prog->jit_requested && bpf_jit_supports_percpu_insn();
> > > > +#endif
> > >
> > > please see bpf_jit_inlines_helper_call(), arm64 and risc-v inline it
> > > in JIT, so we need to validate they don't assume any of R1-R5 register
> > > to be a scratch register
> >
> > At the moment I return false for this archs.
> > Or do you suggest these to be added in the current patch-set?
>
> I'd add them from the get go. CC Puranjay to double-check?

I'll give it a try.