Re: [RFCv3 00/19] x86/ftrace/bpf: Add batch support for direct/tracing attach

Andrii Nakryiko
2021-06-21T06:46:24Z

On Sun, Jun 20, 2021 at 8:47 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Sun, Jun 20, 2021 at 9:57 AM Yonghong Song <yhs@fb.com> wrote:
> > >
> > > ah right, should have checked it.. so how about we change
> > > trampoline code to store ip in ctx-8 and make bpf_get_func_ip(ctx)
> > > to return [ctx-8]
> >
> > This should work. Thanks!
>
> +1
> and pls make it always inline into single LDX insn in the verifier.
> For both mass attach and normal fentry/fexit.

Yep.

And we should do it for kprobes (trivial, PT_REGS_IP(ctx)) and
kretprobe (less trivial but simple from inside the kernel, Masami
showed how to do it in one of the previous emails). I hope BPF infra
allows inlining of helpers for some program types but not the others.