Received-SPF: pass (google.com: domain of linux-kernel+bounces-162703-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) client-ip=147.75.48.161;
Precedence: bulk
MIME-Version: 1.0
References: <20240421194206.1010934-1-jolsa@kernel.org> <20240421194206.1010934-6-jolsa@kernel.org>
 <CAEf4BzbWr9s2HiWU=7=okwH7PR8LHGFj2marmaOxKW61BWKHGg@mail.gmail.com> <Zi9NPfII8I7nWz6O@krava>
In-Reply-To: <Zi9NPfII8I7nWz6O@krava>
From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date: Mon, 29 Apr 2024 09:41:53 -0700
Message-ID: <CAEf4BzY8K6GXtdRkmo3b=ZnW=6jQZnDMtBbGOQpP8m7boTJRpg@mail.gmail.com>
Subject: Re: [PATCHv3 bpf-next 5/7] selftests/bpf: Add uretprobe syscall call
 from user space test
To: Jiri Olsa <olsajiri@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, Masami Hiramatsu <mhiramat@kernel.org>, 
	Oleg Nesterov <oleg@redhat.com>, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, 
	Andrii Nakryiko <andrii@kernel.org>, linux-kernel@vger.kernel.org, 
	linux-trace-kernel@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, 
	bpf@vger.kernel.org, Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>, 
	John Fastabend <john.fastabend@gmail.com>, Peter Zijlstra <peterz@infradead.org>, 
	Thomas Gleixner <tglx@linutronix.de>, "Borislav Petkov (AMD)" <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>, 
	Andy Lutomirski <luto@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Mon, Apr 29, 2024 at 12:33=E2=80=AFAM Jiri Olsa <olsajiri@gmail.com> wro=
te:
>
> On Fri, Apr 26, 2024 at 11:03:29AM -0700, Andrii Nakryiko wrote:
> > On Sun, Apr 21, 2024 at 12:43=E2=80=AFPM Jiri Olsa <jolsa@kernel.org> w=
rote:
> > >
> > > Adding test to verify that when called from outside of the
> > > trampoline provided by kernel, the uretprobe syscall will cause
> > > calling process to receive SIGILL signal and the attached bpf
> > > program is no executed.
> > >
> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > > ---
> > >  .../selftests/bpf/prog_tests/uprobe_syscall.c | 92 +++++++++++++++++=
++
> > >  .../selftests/bpf/progs/uprobe_syscall_call.c | 15 +++
> > >  2 files changed, 107 insertions(+)
> > >  create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall_=
call.c
> > >
> >
> > See nits below, but overall LGTM
> >
> > Acked-by: Andrii Nakryiko <andrii@kernel.org>
> >
> > [...]
> >
> > > @@ -219,6 +301,11 @@ static void test_uretprobe_regs_change(void)
> > >  {
> > >         test__skip();
> > >  }
> > > +
> > > +static void test_uretprobe_syscall_call(void)
> > > +{
> > > +       test__skip();
> > > +}
> > >  #endif
> > >
> > >  void test_uprobe_syscall(void)
> > > @@ -228,3 +315,8 @@ void test_uprobe_syscall(void)
> > >         if (test__start_subtest("uretprobe_regs_change"))
> > >                 test_uretprobe_regs_change();
> > >  }
> > > +
> > > +void serial_test_uprobe_syscall_call(void)
> >
> > does it need to be serial? non-serial are still run sequentially
> > within a process (there is no multi-threading), it's more about some
> > global effects on system.
>
> plz see below
>
> >
> > > +{
> > > +       test_uretprobe_syscall_call();
> > > +}
> > > diff --git a/tools/testing/selftests/bpf/progs/uprobe_syscall_call.c =
b/tools/testing/selftests/bpf/progs/uprobe_syscall_call.c
> > > new file mode 100644
> > > index 000000000000..5ea03bb47198
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/bpf/progs/uprobe_syscall_call.c
> > > @@ -0,0 +1,15 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +#include "vmlinux.h"
> > > +#include <bpf/bpf_helpers.h>
> > > +#include <string.h>
> > > +
> > > +struct pt_regs regs;
> > > +
> > > +char _license[] SEC("license") =3D "GPL";
> > > +
> > > +SEC("uretprobe//proc/self/exe:uretprobe_syscall_call")
> > > +int uretprobe(struct pt_regs *regs)
> > > +{
> > > +       bpf_printk("uretprobe called");
> >
> > debugging leftover? we probably don't want to pollute trace_pipe from t=
est
>
> the reason for this is to make sure the bpf program was not executed,
>
> the test makes sure the child gets killed with SIGILL and also that
> the bpf program was not executed by checking the trace_pipe and
> making sure nothing was received
>
> the trace_pipe reading is also why it's serial

you could have attached BPF program from parent process and use a
global variable (and thus eliminate all the trace_pipe system-wide
dependency), but ok, it's fine by me the way this is done

>
> jirka
>
> >
> > > +       return 0;
> > > +}
> > > --
> > > 2.44.0
> > >