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RE: kprobe fault handling
- From: Martin Hunt <hunt at redhat dot com>
- To: "Keshavamurthy, Anil S" <anil dot s dot keshavamurthy at intel dot com>
- Cc: Jim Keniston <jkenisto at us dot ibm dot com>, "systemtap at sources dot redhat dot com" <systemtap at sources dot redhat dot com>
- Date: Tue, 07 Feb 2006 12:49:24 -0800
- Subject: RE: kprobe fault handling
- Organization: Red Hat Inc
- References: <44BDAFB888F59F408FAE3CC35AB4704102F4F1A3@orsmsx409>
On Tue, 2006-02-07 at 12:35 -0800, Keshavamurthy, Anil S wrote:
> >I just had a long chat with Richard Moore about this whole topic. I
> >agree with you on this, and I think Richard would, too.
> >
> >So unless there's a user-specified handler and that handler specifies
> >(by returning 1) that it has handled the exception,
> >kprobe_fault_handler() should run fixup_exception(), right?
> >
> >Now I'm looking, later in that function, at the code (on i386) where we
> >handle an exception while single-stepping. I don't think
> >resume_execution() is the right thing to do here. We haven't
> >successfully executed the probed instruction, and the eip still points
> >at that instruction, right? I think we're just hosed at this point.
> >Comments?
> I agree with your comments and we need a better fix.
> Currently for RHEL4 release I am inclined to remove
> DIE_PAGE_FAULT switch case as this at least improves
> the performance.
Anil. Did you read this thread, starting at
http://sources.redhat.com/ml/systemtap/2006-q1/msg00392.html
How will removing page fault handling fix our broken page fault
handling?
Martin