netdev - Re: [PATCH v4 bpf-next 2/4] libbpf: support libbpf-provided extern variables

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Date:   Sat, 14 Dec 2019 13:50:18 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Andrii Nakryiko <andriin@...com>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, ast@...com, daniel@...earbox.net
Cc:     andrii.nakryiko@...il.com, kernel-team@...com,
        Andrii Nakryiko <andriin@...com>
Subject: Re: [PATCH v4 bpf-next 2/4] libbpf: support libbpf-provided extern variables

[...]

> +static bool sym_is_extern(const GElf_Sym *sym)
> +{
> +	int bind = GELF_ST_BIND(sym->st_info);
> +	/* externs are symbols w/ type=NOTYPE, bind=GLOBAL|WEAK, section=UND */
> +	return sym->st_shndx == SHN_UNDEF &&
> +	       (bind == STB_GLOBAL || bind == STB_WEAK) &&
> +	       GELF_ST_TYPE(sym->st_info) == STT_NOTYPE;
> +}

Will this also match function declarations marked as extern? I've
started looking into how to handle this for the static/dynamic linking
use cases and am wondering whether it makes sense to pull in this series
and build on that?

-Toke