Re: [PATCH bpf-next v1 0/4] Support bpf trampoline for RV64

[Pu Lehui]

On 2023/2/18 4:49, Daniel Borkmann wrote:
> On 2/16/23 10:56 AM, Björn Töpel wrote:
> > Pu Lehui <pulehui@xxxxxxxxxxxxxxx> writes:
> >
> > > BPF trampoline is the critical infrastructure of the bpf
> > > subsystem, acting as a mediator between kernel functions
> > > and BPF programs. Numerous important features, such as
> > > using ebpf program for zero overhead kernel introspection,
> > > rely on this key component. We can't wait to support bpf
> > > trampoline on RV64. Since RV64 does not support ftrace
> > > direct call yet, the current RV64 bpf trampoline is only
> > > used in bpf context.
> > >
> > > As most of riscv cpu support unaligned memory accesses,
> > > we temporarily use patch [1] to facilitate testing. The
> > > test results are as follow, and test_verifier with no
> > > new failure ceses.
> > >
> > > - fexit_bpf2bpf:OK
> > > - dummy_st_ops:OK
> > > - xdp_bpf2bpf:OK
> > >
> > > [1] 
> > > https://lore.kernel.org/linux-riscv/20210916130855.4054926-2-chenhuang5@xxxxxxxxxx/
> > >
> > > v1:
> > > - Remove the logic of bpf_arch_text_poke supported for
> > >    kernel functions. (Kuohai and Björn)
> > > - Extend patch_text for multiple instructions. (Björn)
> > > - Fix OOB issue when image too big. (Björn)
> >
> > This series is ready to go in as is.
>
> Ok.
>
> > @Palmer I'd like to take this series via the bpf-next tree (as usual),
> > but note that there are some non-BPF changes as well, related to text
> > poking.
> >
> > @Lehui I'd like to see two follow-up patches:
> >
> > 1. Enable kfunc for RV64, by adding:
> >   | bool bpf_jit_supports_kfunc_call(void)
> >   | {
> >   |         return true;
> >   | }
> >
> > 2. Remove the checkpatch warning on patch 4:
> >   | WARNING: kfree(NULL) is safe and this check is probably not required
> >   | #313: FILE: arch/riscv/net/bpf_jit_comp64.c:984:
> >   | +    if (branches_off)
> >   | +        kfree(branches_off);
> >
> >
> > For the series:
> >
> > Tested-by: Björn Töpel <bjorn@xxxxxxxxxxxx>
> > Acked-by: Björn Töpel <bjorn@xxxxxxxxxxxx>
>
> Thanks, I fixed up issue 2 and cleaned up the commit msgs while applying.
> For issue 1, pls send a follow-up.

Thank you both, will handle this.