[dpdk-dev] BUG: eBPF missing BPF_ABS

[Stephen Hemminger]

As I mentioned in my FOSDEM talk the current DPDK eBPF handling is
not usable for packet filters. I have ported the classic BPF to eBPF code
and the generated code is not usable by DPDK.

The problem is that DPDK eBPF does not implement all the opcodes.
BPF_ABS is not implemented and must be. It is in the Linux kernel.

PCAP filter string: ip dst fosdem.org
cBPF program (6 insns):
 L0:	28 00 00 00 0c 00 00 00 ldh [12]
 L1:	15 00 00 03 00 08 00 00 jeq #0x800, L2, L5
 L2:	20 00 00 00 1e 00 00 00 ld [30]
 L3:	15 00 00 01 8c 16 16 1f jeq #0x1f16168c, L4, L5
 L4:	06 00 00 00 ff ff ff ff ret #0xffffffff
 L5:	06 00 00 00 00 00 00 00 ret #0x0
eBPF program (11 insns):
 L0:	af 00 00 00 00 00 00 00 xor r0, r0
 L1:	af 77 00 00 00 00 00 00 xor r7, r7
 L2:	bf 16 00 00 00 00 00 00 mov r6, r1
 L3:	28 70 00 00 0c 00 00 00 ldh r0, [12]
 L4:	55 00 04 00 00 08 00 00 jne r0, #0x800, L9
 L5:	20 70 00 00 1e 00 00 00 ldw r0, [30]
 L6:	55 00 02 00 8c 16 16 1f jne r0, #0x1f16168c, L9
 L7:	b4 00 00 00 01 00 00 00 mov32 r0, #0x1
 L8:	95 00 00 00 00 00 00 00 exit
 L9:	b4 00 00 00 02 00 00 00 mov32 r0, #0x2
 L10:	95 00 00 00 00 00 00 00 exit
validate: invalid opcode at pc: 3
validate: invalid opcode at pc: 5
rte_bpf_load failed: Invalid argument