From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Frederic Weisbecker <frederic@kernel.org>,
Dan Carpenter <dan.carpenter@oracle.com>,
Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: Instrumentation and RCU
Date: Mon, 9 Mar 2020 21:18:42 +0100 [thread overview]
Message-ID: <20200309201842.GL12561@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <87mu8p797b.fsf@nanos.tec.linutronix.de>
On Mon, Mar 09, 2020 at 06:02:32PM +0100, Thomas Gleixner wrote:
> #4 Protecting call chains
>
> Our current approach of annotating functions with notrace/noprobe is
> pretty much broken.
>
> Functions which are marked NOPROBE or notrace call out into functions
> which are not marked and while this might be ok, there are enough
> places where it is not. But we have no way to verify that.
>
> That's just a recipe for disaster. We really cannot request from
> sysadmins who want to use instrumentation to stare at the code first
> whether they can place/enable an instrumentation point somewhere.
> That'd be just a bad joke.
>
> I really think we need to have proper text sections which are off
> limit for any form of instrumentation and have tooling to analyze the
> calls into other sections. These calls need to be annotated as safe
> and intentional.
So the only tool I know of that does full callchains is smatch. And in
one of my series I did prod Dan about this.
The alternative is that we bite the bullet and add a vmlinux objtool
pass. This keeps getting mentioned, so maybe it is time :/ I'd hate it,
because it will increase build time at the slowest point, but it'd get
us the coverage we need here.
next prev parent reply other threads:[~2020-03-09 20:18 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-09 17:02 Instrumentation and RCU Thomas Gleixner
2020-03-09 18:15 ` Steven Rostedt
2020-03-09 18:42 ` Joel Fernandes
2020-03-09 19:07 ` Steven Rostedt
2020-03-09 19:20 ` Mathieu Desnoyers
2020-03-16 15:02 ` Joel Fernandes
2020-03-09 18:59 ` Thomas Gleixner
2020-03-10 8:09 ` Masami Hiramatsu
2020-03-10 11:43 ` Thomas Gleixner
2020-03-10 15:31 ` Mathieu Desnoyers
2020-03-10 15:46 ` Steven Rostedt
2020-03-10 16:21 ` Mathieu Desnoyers
2020-03-11 0:18 ` Masami Hiramatsu
2020-03-11 0:37 ` Mathieu Desnoyers
2020-03-11 7:48 ` Masami Hiramatsu
2020-03-10 16:06 ` Masami Hiramatsu
2020-03-12 13:53 ` Peter Zijlstra
2020-03-10 15:24 ` Mathieu Desnoyers
2020-03-10 17:05 ` Daniel Thompson
2020-03-09 18:37 ` Mathieu Desnoyers
2020-03-09 18:44 ` Steven Rostedt
2020-03-09 18:52 ` Mathieu Desnoyers
2020-03-09 19:09 ` Steven Rostedt
2020-03-09 19:25 ` Mathieu Desnoyers
2020-03-09 19:52 ` Thomas Gleixner
2020-03-10 15:03 ` Mathieu Desnoyers
2020-03-10 16:48 ` Thomas Gleixner
2020-03-10 17:40 ` Mathieu Desnoyers
2020-03-10 18:31 ` Thomas Gleixner
2020-03-10 18:37 ` Mathieu Desnoyers
2020-03-10 1:40 ` Alexei Starovoitov
2020-03-10 8:02 ` Thomas Gleixner
2020-03-10 16:54 ` Paul E. McKenney
2020-03-17 17:56 ` Joel Fernandes
2020-03-09 20:18 ` Peter Zijlstra [this message]
2020-03-09 20:47 ` Paul E. McKenney
2020-03-09 20:58 ` Steven Rostedt
2020-03-09 21:25 ` Paul E. McKenney
2020-03-09 23:52 ` Frederic Weisbecker
2020-03-10 2:26 ` Paul E. McKenney
2020-03-10 15:13 ` Mathieu Desnoyers
2020-03-10 16:49 ` Paul E. McKenney
2020-03-10 17:22 ` Mathieu Desnoyers
2020-03-10 17:26 ` Paul E. McKenney
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