Re: [RFC PATCH net-next 2/6] x86: bpf_jit_comp: support BPF_S_ANC_SECCOMP_LD_W instruction

Xi Wang
2013-04-26T15:29:27Z

On Fri, Apr 26, 2013 at 11:11 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> 2) Calling a function potentially destroys some registers.
> %rdi,%r8,%r9 for instance, so we are going to crash very easily.
>
> I dont know, I feel a bit uncomfortable having to explain this to
> someone sending security related patches...

My old code did save these registers. But, do we really need that for
seccomp? For example, %rdi (skb) is always NULL and never used by
seccomp filters. Did I miss anything?

- xi