linux-kernel - Re: perf test BPF failing on 4.15.0-rc6

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Date:   Thu, 4 Jan 2018 12:39:34 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     "Wangnan (F)" <wangnan0@...wei.com>
Cc:     Adrian Hunter <adrian.hunter@...el.com>,
        David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: perf test BPF failing on 4.15.0-rc6

Em Thu, Jan 04, 2018 at 09:37:35AM +0800, Wangnan (F) escreveu:
> 
> 
> On 2018/1/4 4:13, Arnaldo Carvalho de Melo wrote:
> > Em Wed, Jan 03, 2018 at 03:33:07PM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Wed, Jan 03, 2018 at 03:27:01PM -0300, Arnaldo Carvalho de Melo escreveu:
> > > > > Continuing investigation...
> > > > After applying the fallback patch to allow new tools to work with older
> > > > kernels:
> > > > 
> > > > [root@...icio ~]# perf test bpf
> > > > 39: BPF filter                                            :
> > > > 39.1: Basic BPF filtering                                 : Ok
> > > > 39.2: BPF pinning                                         : Ok
> > > > 39.3: BPF prologue generation                             : Ok
> > > > 39.4: BPF relocation checker                              : Ok
> > > > [root@...icio ~]# uname -a
> > > > Linux felicio.ghostprotocols.net 4.13.0-rc7+ #1 SMP Mon Sep 11 13:56:18 -03 2017 x86_64 x86_64 x86_64 GNU/Linux
> > > > [root@...icio ~]# rpm -q glibc
> > > > glibc-2.17-157.el7_3.2.x86_64
> > > > [root@...icio ~]#
> > > > 
> > > > After applying the patch below I get to, which is what I am trying to
> > > > fix now:
> > > > 
> > > > [root@...et ~]# perf test bpf
> > > > 39: BPF filter                                            :
> > > > 39.1: Basic BPF filtering                                 : Ok
> > > > 39.2: BPF pinning                                         : Ok
> > > > 39.3: BPF prologue generation                             : FAILED!
> > > > 39.4: BPF relocation checker                              : Skip
> > > > [root@...et ~]#
> > > Update the patch to the one at the end of this message to make it work
> > > with older glibcs, so that we ask for epoll_pwait() and hook into that
> > > as well().
> > > 
> > > Now checking why 39.3 fails...
> > Couldn't reproduce after fixing up some kernel build problems, the patch
> > below is all I need to have this working with both Fedora 27 and RHEL7,
> > please take a look and see if it continues to work on your systems,
> 
> It works for me. Thank you.
> 
> Since we test epoll_pwait, we'd better correct function names:

Right, that wasn't strictly needed, so I tried to restrict my changes to
focus on the fix.

Now that we agree on it, I'm doing what you suggest, to make it less
confusing.

I'm adding your Tested-by, thanks!

- Arnaldo
 
> 
> diff --git a/tools/perf/tests/bpf-script-example.c
> b/tools/perf/tests/bpf-script-example.c
> index 268e5f8..e4123c1 100644
> --- a/tools/perf/tests/bpf-script-example.c
> +++ b/tools/perf/tests/bpf-script-example.c
> @@ -31,8 +31,8 @@ struct bpf_map_def SEC("maps") flip_table = {
>      .max_entries = 1,
>  };
> 
> -SEC("func=SyS_epoll_wait")
> -int bpf_func__SyS_epoll_wait(void *ctx)
> +SEC("func=SyS_epoll_pwait")
> +int bpf_func__SyS_epoll_pwait(void *ctx)
>  {
>      int ind =0;
>      int *flag = bpf_map_lookup_elem(&flip_table, &ind);
> diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
> index 34c22cd..a8f9095 100644
> --- a/tools/perf/tests/bpf.c
> +++ b/tools/perf/tests/bpf.c
> @@ -19,13 +19,13 @@
> 
>  #ifdef HAVE_LIBBPF_SUPPORT
> 
> -static int epoll_wait_loop(void)
> +static int epoll_pwait_loop(void)
>  {
>      int i;
> 
>      /* Should fail NR_ITERS times */
>      for (i = 0; i < NR_ITERS; i++)
> -        epoll_wait(-(i + 1), NULL, 0, 0);
> +        epoll_pwait(-(i + 1), NULL, 0, 0, NULL);
>      return 0;
>  }
> 
> @@ -68,7 +68,7 @@ static struct {
>          "[basic_bpf_test]",
>          "fix 'perf test LLVM' first",
>          "load bpf object failed",
> -        &epoll_wait_loop,
> +        &epoll_pwait_loop,
>          (NR_ITERS + 1) / 2,
>          false,
>      },
> @@ -78,7 +78,7 @@ static struct {
>          "[bpf_pinning]",
>          "fix kbuild first",
>          "check your vmlinux setting?",
> -        &epoll_wait_loop,
> +        &epoll_pwait_loop,
>          (NR_ITERS + 1) / 2,
>          true,
>      },
> 
>