Re: [PATCH v9.1 07/11] tracing/probes: Add $$args meta argument for all function args

Steven Rostedt
2023-05-05T21:49:07Z

On Tue, 2 May 2023 11:18:21 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:

> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Add the '$$args' meta fetch argument for function-entry probe events. This

Hmm, couldn't we just use $args ? That would be different from $arg1,
$arg2, etc.

The $$ to me would be either the bash pid of current, or perhaps it would
be just to use a dollar sign. I don't see the precedence of $$args being a
"full expand".

-- Steve

> will be expanded to the all arguments of the function and the tracepoint
> using BTF function argument information.
>
> e.g.
> # echo 'p vfs_read $$args' >> dynamic_events
> # echo 'f vfs_write $$args' >> dynamic_events
> # echo 't sched_overutilized_tp $$args' >> dynamic_events
> # cat dynamic_events
> p:kprobes/p_vfs_read_0 vfs_read file=file buf=buf count=count pos=pos
> f:fprobes/vfs_write__entry vfs_write file=file buf=buf count=count pos=pos
> t:tracepoints/sched_overutilized_tp sched_overutilized_tp rd=rd overutilized=overutilized
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> ---