linux-kernel - Re: [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on error

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Message-ID: <20190321141020.641e313f@gandalf.local.home>
Date:   Thu, 21 Mar 2019 14:10:20 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Juergen Gross <jgross@...e.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Joel Fernandes <joel@...lfernandes.org>,
        He Zhe <zhe.he@...driver.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Clark Williams <williams@...hat.com>
Subject: Re: [RFC][PATCH] tracing/x86: Save CR2 before tracing irqsoff on
 error_entry

On Thu, 21 Mar 2019 11:05:06 -0700
Andy Lutomirski <luto@...capital.net> wrote:

> In the long run, I think the right solution is to rewrite even more of
> this mess in C.  We really ought to be able to put the IRQ flag
> tracing and the context tracking into C code.

And once we do that, we can work on getting the irq tracing
incorporated into a jump_label type that we could possibly enable
lockdep at start up, and then disable it later, even on production
systems! That is, to be able to turn it off and bring the system back
up to full speed.

It would also allow for irq tracing too.

Some inquiring minds have been asking about this ;-)

-- Steve