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

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Date:   Fri, 8 Nov 2019 17:32:34 +0000
From:   Song Liu <songliubraving@...com>
To:     Alexei Starovoitov <ast@...nel.org>
CC:     David Miller <davem@...emloft.net>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "x86@...nel.org" <x86@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>
Subject: 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 <songliubraving@...com> wrote:
> 
> 
> 
>> On Nov 7, 2019, at 10:40 PM, Alexei Starovoitov <ast@...nel.org> 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@...nel.org>
> 
> Acked-by: Song Liu <songliubraving@...com>

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