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Re: Dealing with the NMI mess

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On Fri, 24 Jul 2015 14:43:04 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

 
> > I'm not too familiar with how to use hw breakpoints, but I'm guessing
> > (correct me if I'm wrong) that breakpoints on code that trigger when
> > executed, but watchpoints on data trigger when accessed. Then
> > copy_from_user_inatomic() would only trigger on watchpoints (it's not
> > executing that code, at least I hope it isn't!), and those wont bother
> > us.
> 
> These things can be: RW, W, X.
> 
> Sure, hitting a user X watchpoint is going to be 'interesting', but its
> fairly easy to hit a RW one.

But do we care if we do hit one? The return from the #DB handler can
use a RET. Right?

-- Steve


> 
> Just watch an on-stack variable and get perf to copy a huge chunk of
> stack (like it does for the dwarf stuff).

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Thread

Re: Dealing with the NMI mess Steven Rostedt <rostedt@goodmis.org> - 2015-07-23 23:40 +0200
  Re: Dealing with the NMI mess Linus Torvalds <torvalds@linux-foundation.org> - 2015-07-23 23:50 +0200
    Re: Dealing with the NMI mess Andy Lutomirski <luto@amacapital.net> - 2015-07-24 00:00 +0200
      Re: Dealing with the NMI mess Linus Torvalds <torvalds@linux-foundation.org> - 2015-07-24 00:10 +0200
        Re: Dealing with the NMI mess Peter Zijlstra <peterz@infradead.org> - 2015-07-24 10:20 +0200
          Re: Dealing with the NMI mess Willy Tarreau <w@1wt.eu> - 2015-07-24 11:10 +0200
          Re: Dealing with the NMI mess Steven Rostedt <rostedt@goodmis.org> - 2015-07-24 14:00 +0200
            Re: Dealing with the NMI mess Peter Zijlstra <peterz@infradead.org> - 2015-07-24 14:50 +0200
              Re: Dealing with the NMI mess Steven Rostedt <rostedt@goodmis.org> - 2015-07-24 15:10 +0200
                Re: Dealing with the NMI mess Willy Tarreau <w@1wt.eu> - 2015-07-24 15:30 +0200
                Re: Dealing with the NMI mess Peter Zijlstra <peterz@infradead.org> - 2015-07-24 15:40 +0200
                Re: Dealing with the NMI mess Peter Zijlstra <peterz@infradead.org> - 2015-07-24 15:40 +0200
                Re: Dealing with the NMI mess Paolo Bonzini <pbonzini@redhat.com> - 2015-07-30 17:50 +0200
                Re: Dealing with the NMI mess Borislav Petkov <bp@alien8.de> - 2015-07-31 06:30 +0200
          Re: Dealing with the NMI mess Paolo Bonzini <pbonzini@redhat.com> - 2015-07-30 18:00 +0200
  Re: Dealing with the NMI mess Andy Lutomirski <luto@amacapital.net> - 2015-07-23 23:50 +0200
    Re: Dealing with the NMI mess Willy Tarreau <w@1wt.eu> - 2015-07-24 00:00 +0200
  Re: Dealing with the NMI mess Willy Tarreau <w@1wt.eu> - 2015-07-23 23:50 +0200

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