Hello,
On Thu, 2019-02-14 at 14:39 -0800, Y Song wrote:
> On Thu, Feb 14, 2019 at 10:33 AM Eric Leblond <eric@xxxxxxxxx> wrote:
> > Hello,
> >
> > On Wed, 2019-02-13 at 20:46 +0100, Eric Leblond wrote:
> > > Hello,
> > >
> > > I've got a simple socket filter program that seems to interrupt
> > > when
> > > calling the load_word construct. I'm seeing the first message but
> > > never
> > > the second one.
> > >
> > > The code is the following
> > >
> > > int SEC("filter") hashfilter(struct __sk_buff *skb) {
> > > __u32 nhoff = BPF_LL_OFF + ETH_HLEN;
> >
> > So it seems the problem was coming from this line. Removing
> > BPF_LL_OFF
> > fixes the problem for kernel starting 4.18.
>
> Maybe removing BPF_LL_OFF should work for all kernels?
OK, you are right. I really don't understand how it is possible but
same eBPF file without BPF_LL_OFF work on 4.17 at 4.19. Looks like
BPF_LL_OFF was just ignored in 4.17 but caused a problem on 4.19.
Thanks a lot.
BR,
> > Is this a known issue ?
> >
> > Is there something that would allow a BPF file to work
> > independently of
> > the kernel version ?
> >
> > > __u32 ip = 0;
> > > __u32 *value = NULL;
> > > #if 1
> > > char fmtrei[] = "word load\n";
> > > bpf_trace_printk(fmtrei, sizeof(fmtrei));
> > > #endif
> > > ip = load_word(skb, nhoff + offsetof(struct iphdr, saddr));
> > > #if 1
> > > char fmti[] = "work done\n";
> > > bpf_trace_printk(fmti, sizeof(fmti));
> > > #endif
> > > In 4.18 and above this is not working but older kernel were ok.
> > >
> > > Any suggestion will be appreciated.
> > >
> > > Best regards,
> >
> > BR,
> > --
> > Eric Leblond <eric@xxxxxxxxx>
> >
--
Eric Leblond <eric@xxxxxxxxx>
|