From: Jiri Olsa <olsajiri@gmail.com>
To: Daniel Xu <dxu@dxuuu.xyz>
Cc: Jiri Olsa <olsajiri@gmail.com>,
linux-input@vger.kernel.org, coreteam@netfilter.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org,
linux-kselftest@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, fsverity@lists.linux.dev,
bpf@vger.kernel.org, netdev@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
cgroups@vger.kernel.org, alexei.starovoitov@gmail.com,
quentin@isovalent.com, alan.maguire@oracle.com, memxor@gmail.com
Subject: Re: [PATCH bpf-next v3 0/3] Annotate kfuncs in .BTF_ids section
Date: Sat, 13 Jan 2024 20:49:14 +0100 [thread overview]
Message-ID: <ZaLpOoi9qu1f-u5B@krava> (raw)
In-Reply-To: <nhpt647n2djmthtdkqzrfbpeuqkhfy567rt7qyqtymxejncbgr@4tpiyxy2sbcm>
On Sat, Jan 13, 2024 at 09:17:44AM -0700, Daniel Xu wrote:
> Hi Jiri,
>
> On Sat, Jan 13, 2024 at 02:57:40PM +0100, Jiri Olsa wrote:
> > On Fri, Jan 12, 2024 at 01:03:59PM -0700, Daniel Xu wrote:
> > > On Fri, Jan 12, 2024 at 05:20:39PM +0100, Jiri Olsa wrote:
> > > > On Sat, Jan 06, 2024 at 11:24:07AM -0700, Daniel Xu wrote:
> > > > > === Description ===
> > > > >
> > > > > This is a bpf-treewide change that annotates all kfuncs as such inside
> > > > > .BTF_ids. This annotation eventually allows us to automatically generate
> > > > > kfunc prototypes from bpftool.
> > > > >
> > > > > We store this metadata inside a yet-unused flags field inside struct
> > > > > btf_id_set8 (thanks Kumar!). pahole will be taught where to look.
> > > > >
> > > > > More details about the full chain of events are available in commit 3's
> > > > > description.
> > > > >
> > > > > The accompanying pahole changes (still needs some cleanup) can be viewed
> > > > > here on this "frozen" branch [0].
> > > >
> > > > so the plan is to have bpftool support to generate header file
> > > > with detected kfuncs?
> > >
> > > Yep, that's the major use case. But I see other use cases as well like
> >
> > ok, any chance you could already include it in the patchset?
> > would be a great way to test this.. maybe we could change
> > selftests to use that
>
> I haven't start working on that code yet, but I can.
>
> Here is my plan FWIW:
>
> 1. Bump minimum required pahole version up. Or feature probe for
> kfunc decl tag support. Whatever is the standard practice here.
>
> 2. Teach bpftool to dump kfunc prototypes, guarded behind a flag.
>
> 3. Flip bpftool flag on in selftest build and remove all manual kfunc
> prototypes atomically in 1 commit.
>
> I thought it'd be nicer to do it incrementally given all the moving
> pieces. But if we want to land it all at once that is ok by me too.
I think it'd be best to try the whole thing before we merge the change
to pahole.. I guess the tests changes can come later, but would be great
to try the kfunc dump and make sure it works as expected
jirka
prev parent reply other threads:[~2024-01-13 19:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-06 18:24 [PATCH bpf-next v3 0/3] Annotate kfuncs in .BTF_ids section Daniel Xu
2024-01-06 18:24 ` [PATCH bpf-next v3 3/3] bpf: treewide: Annotate BPF kfuncs in BTF Daniel Xu
2024-01-08 9:15 ` [PATCH bpf-next v3 0/3] Annotate kfuncs in .BTF_ids section Lorenz Bauer
2024-01-08 17:52 ` Daniel Xu
2024-01-12 16:20 ` Jiri Olsa
2024-01-12 20:03 ` Daniel Xu
2024-01-13 13:57 ` Jiri Olsa
2024-01-13 16:17 ` Daniel Xu
2024-01-13 19:49 ` Jiri Olsa [this message]
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