Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote:
> > + if (!emit(p, BPF_STX_MEM(BPF_H, BPF_REG_6, BPF_REG_8,
> > + offsetof(struct nf_hook_state, hook_index))))
> > + return false;
> > + /* arg2: struct nf_hook_state * */
> > + if (!emit(p, BPF_MOV64_REG(BPF_REG_2, BPF_REG_6)))
> > + return false;
> > + /* arg3: original hook return value: (NUM << NF_VERDICT_QBITS | NF_QUEUE) */
> > + if (!emit(p, BPF_MOV32_REG(BPF_REG_3, BPF_REG_0)))
> > + return false;
> > + if (!emit(p, BPF_EMIT_CALL(nf_queue)))
> > + return false;
>
> here and other CALL work by accident on x84-64.
> You need to wrap them with BPF_CALL_ and point BPF_EMIT_CALL to that wrapper.
Do you mean this? :
BPF_CALL_3(nf_queue_bpf, struct sk_buff *, skb, struct nf_hook_state *,
state, unsigned int, verdict)
{
return nf_queue(skb, state, verdict);
}
- if (!emit(p, BPF_EMIT_CALL(nf_hook_slow)))
+ if (!emit(p, BPF_EMIT_CALL(nf_hook_slow_bpf)))
?
If yes, I don't see how this will work for the case where I only have an
address, i.e.:
if (!emit(p, BPF_EMIT_CALL(h->hook))) ....
(Also, the address might be in a kernel module)
> On x86-64 it will be a nop.
> On x86-32 it will do quite a bit of work.
If this only a problem for 32bit arches, I could also make this
'depends on CONFIG_64BIT'.
But perhaps I am on the wrong track, I see existing code doing:
*insn++ = BPF_EMIT_CALL(__htab_map_lookup_elem);
(kernel/bpf/hashtab.c).
> > + prog = bpf_prog_select_runtime(prog, &err);
> > + if (err) {
> > + bpf_prog_free(prog);
> > + return NULL;
> > + }
>
> Would be good to do bpf_prog_alloc_id() so it can be seen in
> bpftool prog show.
Thanks a lot for the hint:
39: unspec tag 0000000000000000
xlated 416B jited 221B memlock 4096B
bpftool prog dump xlated id 39
0: (bf) r6 = r1
1: (79) r7 = *(u64 *)(r1 +8)
2: (b4) w8 = 0
3: (85) call ipv6_defrag#526144928
4: (55) if r0 != 0x1 goto pc+24
5: (bf) r1 = r6
6: (04) w8 += 1
7: (85) call ipv6_conntrack_in#526206096
[..]
