netdev - Re: [RFC PATCH v2 0/8] fprobe: Introduce fprobe function entry/exit probe

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Date:   Sat, 15 Jan 2022 11:11:57 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Jiri Olsa <jolsa@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        "Naveen N . Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [RFC PATCH v2 0/8] fprobe: Introduce fprobe function entry/exit
 probe

Hi Andrii,

On Fri, 14 Jan 2022 17:02:31 -0800
Andrii Nakryiko <andrii.nakryiko@...il.com> wrote:

> On Fri, Jan 14, 2022 at 7:10 AM Jiri Olsa <jolsa@...hat.com> wrote:
> >
> > On Fri, Jan 14, 2022 at 11:47:04PM +0900, Masami Hiramatsu wrote:
> > > Hi Jiri and Alexei,
> > >
> > > On Thu, 13 Jan 2022 13:27:34 +0100
> > > Jiri Olsa <jolsa@...hat.com> wrote:
> > >
> > > > On Wed, Jan 12, 2022 at 05:01:15PM +0100, Jiri Olsa wrote:
> > > > > On Wed, Jan 12, 2022 at 11:02:46PM +0900, Masami Hiramatsu wrote:
> > > > > > Hi Jiri and Alexei,
> > > > > >
> > > > > > Here is the 2nd version of fprobe. This version uses the
> > > > > > ftrace_set_filter_ips() for reducing the registering overhead.
> > > > > > Note that this also drops per-probe point private data, which
> > > > > > is not used anyway.
> > > > > >
> > > > > > This introduces the fprobe, the function entry/exit probe with
> > > > > > multiple probe point support. This also introduces the rethook
> > > > > > for hooking function return as same as kretprobe does. This
> > > > >
> > > > > nice, I was going through the multi-user-graph support
> > > > > and was wondering that this might be a better way
> > > > >
> > > > > > abstraction will help us to generalize the fgraph tracer,
> > > > > > because we can just switch it from rethook in fprobe, depending
> > > > > > on the kernel configuration.
> > > > > >
> > > > > > The patch [1/8] and [7/8] are from your series[1]. Other libbpf
> > > > > > patches will not be affected by this change.
> > > > >
> > > > > I'll try the bpf selftests on top of this
> > > >
> > > > I'm getting crash and stall when running bpf selftests,
> > > > the fprobe sample module works fine, I'll check on that
> > >
> > > I've tried to build tools/testing/selftests/bpf on my machine,
> > > but I got below errors. Would you know how I can setup to build
> > > the bpf selftests correctly? (I tried "make M=samples/bpf", but same result)
> >
> > what's your clang version? your distro might be behind,

I'm using clang 13.0.0.

$ clang -v
clang version 13.0.0 (https://github.com/llvm/llvm-project.git d7b669b3a30345cfcdb2fde2af6f48aa4b94845d)
Target: x86_64-unknown-linux-gnu

> 
> If you have very recent Clang, decently recent pahole, and qemu, try
> using vmtest.sh. That should build the kernel with all the necessary
> kernel config options and start qemu image with that latest image and
> build selftests. And even run selftests automatically.

OK, vmtest.sh works! :)

So I got the vmtest.sh runs out with some failures. Jiri, did you talked about
these failures, or real crash?

Summary: 212/1033 PASSED, 12 SKIPPED, 14 FAILED

Thanks! 

> 
> > I'm using clang 14 compiled from sources:
> >
> >         $ /opt/clang/bin/clang --version
> >         clang version 14.0.0 (https://github.com/llvm/llvm-project.git 9f8ffaaa0bddcefeec15a3df9858fd50b05fcbae)
> >         Target: x86_64-unknown-linux-gnu
> >         Thread model: posix
> >         InstalledDir: /opt/clang/bin
> >
> > and compiling bpf selftests with:
> >
> >         $ CLANG=/opt/clang/bin/clang make
> >
> > jirka
> >
> >
> > >
> 
> [...]
> 
> > >
> > > Thank you,
> > >
> > > --
> > > Masami Hiramatsu <mhiramat@...nel.org>
> > >
> >


-- 
Masami Hiramatsu <mhiramat@...nel.org>