linux-kernel - Re: [PATCH perf/core 2/3] selftests/bpf: Fix uprobe_sigill test for uprobe syscall error value

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Message-ID: <CAEf4BzYnr1UEk-6b73Won4HqcQ_c3Tg+zsHaBXM1P4n3LjKzAQ@mail.gmail.com>
Date: Fri, 5 Sep 2025 14:40:26 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
	Andrii Nakryiko <andrii@...nel.org>, bpf@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-trace-kernel@...r.kernel.org, x86@...nel.org, 
	Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>, 
	John Fastabend <john.fastabend@...il.com>, Hao Luo <haoluo@...gle.com>, 
	Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Alan Maguire <alan.maguire@...cle.com>, David Laight <David.Laight@...lab.com>, 
	Thomas Weißschuh <thomas@...ch.de>, 
	Ingo Molnar <mingo@...nel.org>, Jann Horn <jannh@...gle.com>, Alejandro Colomar <alx@...nel.org>
Subject: Re: [PATCH perf/core 2/3] selftests/bpf: Fix uprobe_sigill test for
 uprobe syscall error value

On Fri, Sep 5, 2025 at 1:58 PM Jiri Olsa <jolsa@...nel.org> wrote:
>
> The uprobe syscall now returns -ENXIO errno when called outside
> kernel trampoline, fixing the current sigill test to reflect that
> and renaming it to uprobe_error.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  .../selftests/bpf/prog_tests/uprobe_syscall.c | 34 ++++---------------
>  1 file changed, 6 insertions(+), 28 deletions(-)
>

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

> diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> index 5da0b49eeaca..6d75ede16e7c 100644
> --- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> @@ -757,34 +757,12 @@ static void test_uprobe_race(void)
>  #define __NR_uprobe 336
>  #endif
>
> -static void test_uprobe_sigill(void)
> +static void test_uprobe_error(void)
>  {
> -       int status, err, pid;
> +       long err = syscall(__NR_uprobe);
>
> -       pid = fork();
> -       if (!ASSERT_GE(pid, 0, "fork"))
> -               return;
> -       /* child */
> -       if (pid == 0) {
> -               asm volatile (
> -                       "pushq %rax\n"
> -                       "pushq %rcx\n"
> -                       "pushq %r11\n"
> -                       "movq $" __stringify(__NR_uprobe) ", %rax\n"
> -                       "syscall\n"
> -                       "popq %r11\n"
> -                       "popq %rcx\n"
> -                       "retq\n"
> -               );
> -               exit(0);
> -       }
> -
> -       err = waitpid(pid, &status, 0);
> -       ASSERT_EQ(err, pid, "waitpid");
> -
> -       /* verify the child got killed with SIGILL */
> -       ASSERT_EQ(WIFSIGNALED(status), 1, "WIFSIGNALED");
> -       ASSERT_EQ(WTERMSIG(status), SIGILL, "WTERMSIG");
> +       ASSERT_EQ(err, -1, "error");
> +       ASSERT_EQ(errno, ENXIO, "errno");
>  }
>
>  static void __test_uprobe_syscall(void)
> @@ -805,8 +783,8 @@ static void __test_uprobe_syscall(void)
>                 test_uprobe_usdt();
>         if (test__start_subtest("uprobe_race"))
>                 test_uprobe_race();
> -       if (test__start_subtest("uprobe_sigill"))
> -               test_uprobe_sigill();
> +       if (test__start_subtest("uprobe_error"))
> +               test_uprobe_error();
>         if (test__start_subtest("uprobe_regs_equal"))
>                 test_uprobe_regs_equal(false);
>         if (test__start_subtest("regs_change"))
> --
> 2.51.0
>