linux-kernel - Re: [RFC PATCH v3 3/3] btf: Reuse libbpf code for BTF type sorting verification and binary search

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAEf4Bzbv+vgsh9_8hsy=JMojmdR_Zoq1EEzaGj0CetMN-7LmDQ@mail.gmail.com>
Date: Fri, 31 Oct 2025 09:50:56 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Donglin Peng <dolinux.peng@...il.com>
Cc: ast@...nel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org, 
	Eduard Zingerman <eddyz87@...il.com>, Alan Maguire <alan.maguire@...cle.com>, Song Liu <song@...nel.org>, 
	pengdonglin <pengdonglin@...omi.com>
Subject: Re: [RFC PATCH v3 3/3] btf: Reuse libbpf code for BTF type sorting
 verification and binary search

On Tue, Oct 28, 2025 at 7:03 PM Donglin Peng <dolinux.peng@...il.com> wrote:
>
> On Wed, Oct 29, 2025 at 2:40 AM Andrii Nakryiko
> <andrii.nakryiko@...il.com> wrote:
> >
> > On Mon, Oct 27, 2025 at 6:54 AM Donglin Peng <dolinux.peng@...il.com> wrote:
> > >
> > > The previous commit implemented BTF sorting verification and binary
> > > search algorithm in libbpf. This patch enables this functionality in
> > > the kernel.
> > >
> > > Cc: Eduard Zingerman <eddyz87@...il.com>
> > > Cc: Alexei Starovoitov <ast@...nel.org>
> > > Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
> > > Cc: Alan Maguire <alan.maguire@...cle.com>
> > > Cc: Song Liu <song@...nel.org>
> > > Signed-off-by: pengdonglin <pengdonglin@...omi.com>
> > > Signed-off-by: Donglin Peng <dolinux.peng@...il.com>
> > > ---
> > > v2->v3:
> > > - Include btf_sort.c directly in btf.c to reduce function call overhead
> > > ---
> > >  kernel/bpf/btf.c | 34 ++++++++++++++++++----------------
> > >  1 file changed, 18 insertions(+), 16 deletions(-)
> > >
> > > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > > index 0de8fc8a0e0b..df258815a6ca 100644
> > > --- a/kernel/bpf/btf.c
> > > +++ b/kernel/bpf/btf.c
> > > @@ -33,6 +33,7 @@
> > >  #include <net/sock.h>
> > >  #include <net/xdp.h>
> > >  #include "../tools/lib/bpf/relo_core.h"
> > > +#include "../tools/lib/bpf/btf_sort.h"
> >
> > I don't believe in code reuse for the sake of code reuse. This code
> > sharing just makes everything more entangled and complicated.
> > Reimplementing binary search is totally fine, IMO.
>
> Thanks. Would you be open to the approach from v2, where we place
> the common code in btf_sort.c and compile it separately rather than
> including it directly?
>

No, the code is too trivial to try to reuse it. Kernel and user space
libbpf code are run with different constraints, sharing it is
necessary evil (like for BPF CO-RE relocations), not something that
should be encouraged.

> >
> > [...]