Messages in this thread |  | | | Date | Fri, 16 Jul 2010 21:30:53 +0200 | | From | Andi Kleen <> | | Subject | Re: [patch 2/2] x86 NMI-safe INT3 and Page Fault |
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On Fri, Jul 16, 2010 at 11:25:19AM -0700, Linus Torvalds wrote: > On Fri, Jul 16, 2010 at 11:15 AM, Avi Kivity <avi@redhat.com> wrote: > > > > I think the concern here is about an NMI handler's code running in vmalloc > > space, or is it something else? > > I think the concern was also potentially doing things like backtraces > etc that may need access to the module data structures (I think the > ELF headers end up all being in vmalloc space too, for example). > > The whole debugging thing is also an issue. Now, I obviously am not a > big fan of remote debuggers, but everybody tells me I'm wrong. And > putting a breakpoint on NMI is certainly not insane if you are doing > debugging in the first place. So it's not necessarily always about the > page faults.
We already have infrastructure for kprobes to prevent breakpoints on critical code (the __kprobes section). In principle kgdb/kdb could be taught about honoring those too.
That wouldn't help for truly external JTAG debuggers, but I would assume those generally can (should) handle any contexts anyways.
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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