linux-kernel - Re: [PATCHv3 bpf-next 5/7] selftests/bpf: Add uretprobe syscall call from user space test

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Date: Fri, 26 Apr 2024 11:03:29 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Oleg Nesterov <oleg@...hat.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, linux-kernel@...r.kernel.org, 
	linux-trace-kernel@...r.kernel.org, linux-api@...r.kernel.org, x86@...nel.org, 
	bpf@...r.kernel.org, Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, 
	John Fastabend <john.fastabend@...il.com>, Peter Zijlstra <peterz@...radead.org>, 
	Thomas Gleixner <tglx@...utronix.de>, "Borislav Petkov (AMD)" <bp@...en8.de>, Ingo Molnar <mingo@...hat.com>, 
	Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCHv3 bpf-next 5/7] selftests/bpf: Add uretprobe syscall call
 from user space test

On Sun, Apr 21, 2024 at 12:43 PM Jiri Olsa <jolsa@...nel.org> wrote:
>
> 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@...nel.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_callc
>

See nits below, but overall LGTM

Acked-by: Andrii Nakryiko <andrii@...nel.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.

> +{
> +       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") = "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 test

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