Re: [PATCH bpf-next 2/4] bpf, x64: Fix tailcall hierarchy

[Leon Hwang <hffilwlqm@gmail.com>]

On 2024/2/17 21:43, Leon Hwang wrote:
> 
> 
> On 2024/2/16 10:18, Alexei Starovoitov wrote:

[SNIP]

>>
>> In general that's better, but it feels we can do better
>> and avoid passing rax around.
>> Just access bpf_tail_call_cnt directly from emit_bpf_tail_call.
> Yes, we can do better to avoid passing rax around:
> 
> 1. At prologue, initialise percpu tail_call_cnt.
> 2. When tailcall, fetch and increment percpu tail_call_cnt.
> 
> As a result, we can remove pushing/popping rax at anywhere.
> 
> Finally, here's the diff against latest bpf-next with asm to handle
> percpu tail_call_cnt:
> 


Hi Alexei,

Should I send PATCH v2?

May I add "Suggested-by: Alexei Starovoitov <ast@kernel.org>" at PATCH
v2? Because the key idea, percpu tail_call_cnt, is suggested by you.

Thanks,
Leon