Hi,
When adding test case for BPF STRUCT OPS, I got the following error
during test:
libbpf: load bpf program failed: Permission denied
libbpf: -- BEGIN DUMP LOG ---
libbpf:
R1 type=ctx expected=fp
; int BPF_PROG(test_1, struct bpf_dummy_ops_state *state)
0: (b4) w0 = -218893067
; int BPF_PROG(test_1, struct bpf_dummy_ops_state *state)
1: (79) r1 = *(u64 *)(r1 +0)
func 'test_1' arg0 type FWD is not a struct
invalid bpf_context access off=0 size=8
The error is reported from btf_ctx_access(). And the cause is
the definition of struct bpf_dummy_ops_state is separated from
the definition of test_1 function:
test_1 is defined in include/linux/bpf.h
struct bpf_dummy_ops_state;
struct bpf_dummy_ops {
int (*test_1)(struct bpf_dummy_ops_state *cb);
}
bpf_dummy_ops_state is defined in net/bpf/bpf_dummy_struct_ops.c
struct bpf_dummy_ops_state {
};
So arg0 has BTF_KIND_FWD type, and the check in btf_ctx_access() fails.
The problem can be fixed by moving the definition of bpf_dummy_ops_state
into include/linux/bpf.h or using a void * instead of
struct bpf_dummy_ops_state *. But forward declaration is possible under
STRUCT_OPS scenario, so my question is whether or not it is a known issue
and is there somebody working on this ?
Regards,
Tao
