netdev - RE: [PATCH v2 bpf-next 10/16] bpf: Add bpf_btf_find_by_name

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Message-ID: <60887c80a74c2_12319208a0@john-XPS-13-9370.notmuch>
Date:   Tue, 27 Apr 2021 14:05:04 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     John Fastabend <john.fastabend@...il.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        davem@...emloft.net
Cc:     daniel@...earbox.net, andrii@...nel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, kernel-team@...com
Subject: RE: [PATCH v2 bpf-next 10/16] bpf: Add bpf_btf_find_by_name_kind()
 helper.

John Fastabend wrote:
> Alexei Starovoitov wrote:
> > From: Alexei Starovoitov <ast@...nel.org>
> > 
> > Add new helper:
> > 
> > long bpf_btf_find_by_name_kind(u32 btf_fd, char *name, u32 kind, int flags)
> > 	Description
> > 		Find given name with given type in BTF pointed to by btf_fd.
> > 		If btf_fd is zero look for the name in vmlinux BTF and in module's BTFs.
> > 	Return
> > 		Returns btf_id and btf_obj_fd in lower and upper 32 bits.
> > 
> > Signed-off-by: Alexei Starovoitov <ast@...nel.org>
> > ---
> 
> I'm missing some high-level concept on how this would be used? Where does btf_fd come
> from and how is it used so that it doesn't break sig-check?

aha as I look through this again it seems btf_fd can be from fd_array[] and
sig-check will pan out as well as BTF can come from any valid file.

Correct? If so lgtm at high-level.