Re: [PATCH v3 bpf-next 14/18] bpf: Compare BTF types of functions arguments with actual types

On Nov 8, 2019, at 9:28 AM, Song Liu [off-list ref] wrote:

quoted

On Nov 7, 2019, at 10:40 PM, Alexei Starovoitov [off-list ref] wrote:

Make the verifier check that BTF types of function arguments match actual types
passed into top-level BPF program and into BPF-to-BPF calls. If types match
such BPF programs and sub-programs will have full support of BPF trampoline. If
types mismatch the trampoline has to be conservative. It has to save/restore
all 5 program arguments and assume 64-bit scalars. If FENTRY/FEXIT program is
attached to this program in the future such FENTRY/FEXIT program will be able
to follow pointers only via bpf_probe_read_kernel().

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Acked-by: Song Liu <redacted>

One nit though: maybe use "reliable" instead of "unreliable"

+struct bpf_func_info_aux {
+	bool reliable;
+};
+

+	bool func_proto_reliable;

So the default value 0, is not reliable. 

Thanks,
Song