All of lore.kernel.org
 help / color / mirror / Atom feed
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

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=799177238.23913.1583865451495.JavaMail.zimbra@efficios.com \
    --to=mathieu.desnoyers@efficios.com \
    --cc=ast@kernel.org \
    --cc=frederic@kernel.org \
    --cc=joel@joelfernandes.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mhiramat@kernel.org \
    --cc=paulmck@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.