Re: [PATCH v2] selftests/ftrace: adjust offset for kprobe syntax error test

[Steven Rostedt <rostedt@goodmis.org>]

On Sat, 30 Nov 2024 01:56:21 +0530
Hari Bathini <hbathini@linux.ibm.com> wrote:

> In 'NOFENTRY_ARGS' test case for syntax check, any offset X of
> `vfs_read+X` except function entry offset (0) fits the criterion,
> even if that offset is not at instruction boundary, as the parser
> comes before probing. But with "ENDBR64" instruction on x86, offset
> 4 is treated as function entry. So, X can't be 4 as well. Thus, 8
> was used as offset for the test case. On 64-bit powerpc though, any
> offset <= 16 can be considered function entry depending on build
> configuration (see arch_kprobe_on_func_entry() for implementation
> details). So, use `vfs_read+20` to accommodate that scenario too.
> 
> Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>

Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Shuah,

Can you take this through your tree?

Thanks,

-- Steve

> ---
> 
> Changes in v2:
> * Use 20 as offset for all arches.
> 
> 
>  .../selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc      | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
> index a16c6a6f6055..8f1c58f0c239 100644
> --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
> +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_syntax_errors.tc
> @@ -111,7 +111,7 @@ check_error 'p vfs_read $arg* ^$arg*'		# DOUBLE_ARGS
>  if !grep -q 'kernel return probes support:' README; then
>  check_error 'r vfs_read ^$arg*'			# NOFENTRY_ARGS
>  fi
> -check_error 'p vfs_read+8 ^$arg*'		# NOFENTRY_ARGS
> +check_error 'p vfs_read+20 ^$arg*'		# NOFENTRY_ARGS
>  check_error 'p vfs_read ^hoge'			# NO_BTFARG
>  check_error 'p kfree ^$arg10'			# NO_BTFARG (exceed the number of parameters)
>  check_error 'r kfree ^$retval'			# NO_RETVAL