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

[Daniel Borkmann]

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.