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Message-ID: <20241105120247.596a0dc9@gandalf.local.home>
Date: Tue, 5 Nov 2024 12:02:47 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Marco Elver <elver@...gle.com>
Cc: Kees Cook <keescook@...omium.org>, Masami Hiramatsu
<mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Andrew Morton <akpm@...ux-foundation.org>, Oleg Nesterov <oleg@...hat.com>,
linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org, Dmitry
Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com
Subject: Re: [PATCH] tracing: Add task_prctl_unknown tracepoint
On Tue, 5 Nov 2024 17:53:53 +0100
Marco Elver <elver@...gle.com> wrote:
> > > +/**
> > > + * task_prctl_unknown - called on unknown prctl() option
> > > + * @task: pointer to the current task
> > > + * @option: option passed
> > > + * @arg2: arg2 passed
> > > + * @arg3: arg3 passed
> > > + * @arg4: arg4 passed
> > > + * @arg5: arg5 passed
> > > + *
> > > + * Called on an unknown prctl() option.
> > > + */
> > > +TRACE_EVENT(task_prctl_unknown,
> > > +
> > > + TP_PROTO(struct task_struct *task, int option, unsigned long arg2, unsigned long arg3,
> > > + unsigned long arg4, unsigned long arg5),
> > > +
> > > + TP_ARGS(task, option, arg2, arg3, arg4, arg5),
> > > +
> > > + TP_STRUCT__entry(
> > > + __field( pid_t, pid )
> >
> > Why record the pid that is already recorded by the event header?
>
> To keep in style with the other "task" tracepoints above. I can
> certainly do without - it does seem unnecessary.
Hmm, new_task, pid is different than the creator. But rename is pointless
to record pid. I would get rid of it here, especially since it also creates
a hole in the event (three int fields followed by a long).
>
> To cleanup, do we want to remove "pid=" from the other tracepoints in
> this file as well (in another patch). Or does this potentially break
> existing users?
We can't from task_newtask as that's the pid of the task that's being
created. In other words, it's very relevant. The task_rename could have its
pid field dropped.
>
> > > + __string( comm, task->comm )
> >
> > I'm also surprised that the comm didn't show in the trace_pipe.
>
> Any config options or tweaks needed to get it to show more reliably?
>
> > I've
> > updated the code so that it should usually find it. But saving it here may
> > not be a big deal.
How did you start it? Because it appears reliable for me.
-- Steve
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