Make File Error Chapter 8

[laikas123]

clang \ -target bpf \ -D __BPF_TRACING__ \ -I/usr/include/x86_64-linux-gnu \ -Wall \ -O2 -g -o hello.bpf.o -c hello.bpf.c bpftool net detach xdp dev lo rm -f /sys/fs/bpf/hello bpftool prog load hello.bpf.o /sys/fs/bpf/hello libbpf: prog 'ping': BPF program load failed: Invalid argument libbpf: prog 'ping': -- BEGIN PROG LOAD LOG -- 0: R1=ctx(off=0,imm=0) R10=fp0 ; void data_end = (void )(long)ctx->data_end; 0: (61) r2 = (u32 )(r1 +4) ; R1=ctx(off=0,imm=0) R2_w=pkt_end(off=0,imm=0) ; void data = (void )(long)ctx->data; 1: (61) r3 = (u32 )(r1 +0) ; R1=ctx(off=0,imm=0) R3_w=pkt(off=0,r=0,imm=0) ; if (data + sizeof(struct ethhdr) > data_end) 2: (bf) r1 = r3 ; R1_w=pkt(off=0,r=0,imm=0) R3_w=pkt(off=0,r=0,imm=0) 3: (07) r1 += 14 ; R1_w=pkt(off=14,r=0,imm=0) ; if (data + sizeof(struct ethhdr) > data_end) 4: (2d) if r1 > r2 goto pc+10 ; R1_w=pkt(off=14,r=14,imm=0) R2_w=pkt_end(off=0,imm=0) ; if (bpf_ntohs(eth->h_proto) == ETH_P_IP) 5: (69) r4 = (u16 )(r3 +12) ; R3_w=pkt(off=0,r=14,imm=0) R4_w=scalar(umax=65535,var_off=(0x0; 0xffff)) ; if (bpf_ntohs(eth->h_proto) == ETH_P_IP) 6: (55) if r4 != 0x8 goto pc+8 ; R4_w=8 7: (07) r3 += 34 ; R3=pkt(off=34,r=14,imm=0) 8: (2d) if r3 > r2 goto pc+6 ; R2=pkt_end(off=0,imm=0) R3=pkt(off=34,r=34,imm=0) ; protocol = iph->protocol; 9: (71) r1 = (u8 )(r1 +9) ; R1_w=scalar(umax=255,var_off=(0x0; 0xff)) ; if (protocol == 1) // ICMP 10: (55) if r1 != 0x1 goto pc+4 ; R1_w=1 ; bpf_printk("Hello ping"); 11: (18) r1 = 0xffff9b35a233c710 ; R1_w=map_value(off=0,ks=4,vs=11,imm=0) 13: (b7) r2 = 11 ; R2_w=11 14: (85) call bpf_trace_printk#6 cannot call GPL-restricted function from non-GPL compatible program processed 14 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 1 -- END PROG LOAD LOG -- libbpf: prog 'ping': failed to load: -22 libbpf: failed to load object 'hello.bpf.o' Error: failed to load object file make: *** [Makefile:13: hello] Error 255

The second bolded line above is what is confusing me. I even added the -g flag but that didn't make it go away..

[laikas123]

I also tried to manually load into the kernel but same issue..

[laikas123]

Solution:

Add the following line to the bottom of hello.bpf.c:

char LICENSE[] SEC("license") = "Dual BSD/GPL";