From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Alexei Starovoitov <ast@kernel.org>, paulmck <paulmck@kernel.org>,
"Joel Fernandes, Google" <joel@joelfernandes.org>,
Frederic Weisbecker <frederic@kernel.org>
Subject: Re: Instrumentation and RCU
Date: Tue, 10 Mar 2020 14:37:31 -0400 (EDT) [thread overview]
Message-ID: <799177238.23913.1583865451495.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <87d09k5aet.fsf@nanos.tec.linutronix.de>
----- On Mar 10, 2020, at 2:31 PM, Thomas Gleixner tglx@linutronix.de wrote:
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> writes:
>> ----- On Mar 10, 2020, at 12:48 PM, Thomas Gleixner tglx@linutronix.de wrote:
>>> How do you "fix" that when you can't reach the tracepoint because you
>>> trip over a breakpoint and then while trying to fixup that stuff you hit
>>> another one?
>>
>> I may still be missing something, but if the fixup code (AFAIU the code
>> performing
>> the out-of-line single-stepping of the original instruction) belongs to a
>> section
>> hidden from instrumentation, it should not be an issue.
>
> Sure, but what guarantees that on the way there is nothing which might
> call into instrumentable code? Nothing, really.
>
> That's why I want the explicit sections which can be analyzed by
> tools. Humans (including me) are really bad at it was demonstrated
> several times.
AFAIU, my in_tracer flag proposal complements yours.
The explicit sections thingy is required for early/late entry/exit code,
but does nothing to prevent "explicitly marked" safe-to-instrument kernel
code from triggering infinite recursion.
My flag proposal handles that second issue.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2020-03-10 18:37 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 [this message]
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
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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