[PATCH bpf-next v2] riscv, bpf: Add kfunc support for RV64

[Björn Töpel]

Pu Lehui <pulehui at huaweicloud.com> writes:

> On 2023/2/20 22:34, Björn Töpel wrote:
>> Pu Lehui <pulehui at huaweicloud.com> writes:
>> 
>>> From: Pu Lehui <pulehui at huawei.com>
>>>
>>> As another important missing piece of RV64 JIT, kfunc allow bpf programs
>>> call kernel functions. For now, RV64 is sufficient to enable it.
>> 
>> Thanks Lehui!
>> 
>> Maybe we can reword/massage the commit message a bit? What do you think
>> about something like:
>> 
>> "Now that the BPF trampoline is supported by RISC-V, it is possible to
>> use BPF programs with kfunc calls.
>> 
>
> kfunc and bpf trampoline are functionally independent. kfunc [1], like 
> bpf helper functions, allows bpf programs to call exported kernel 
> functions, while bpf trampoline provides a more efficient way than 
> kprobe to act as a mediator between kernel functions and bpf programs, 
> and between bpf programs.
>
> In fact, it was already supported before the bpf trampoline 
> implementation, I just turned it on.

Good point. I guess my (incorrect) kfunc mental model was that
struct_ops and kfunc were tightly coupled. (Then again, w/o struct_ops
working kfunc is a bit half-working in my view.)

Fair enough. I'm still a bit confused about the commit message, but
happy with the patch.

Acked-by: Björn Töpel <bjorn at rivosinc.com>