This patch includes the changes to make the nmi watchdog on x86_64 SMP
aware.  A bunch of code was moved around to make it simpler to read.  In
addition, it is now possible to determine if a particular NMI was the result
of the watchdog or not.  This feature allows the kernel to filter out
unknown NMIs easier.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Adds basic infrastructure to allow subsystems to reserve performance
counters on the x86 chips.  Only UP kernels are supported in this patch to
make reviewing easier.  The SMP portion makes a lot more changes.

Think of this as a locking mechanism where each bit represents a different
counter.  In addition, each subsystem should also reserve an appropriate
event selection register that will correspond to the performance counter it
will be using (this is mainly neccessary for the Pentium 4 chips as they
break the 1:1 relationship to performance counters).

This will help prevent subsystems like oprofile from interfering with the
nmi watchdog.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Misc header cleanup for nmi watchdog.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Collected NMI watchdog fixes.

- Fix call of check_nmi_watchdog

- Remove earlier move of check_nmi_watchdog to later.  It does not fix the
  race it was supposed to fix fully.

- Remove unused P6 definitions

- Add support for performance counter based watchdog on P4 systems.

  This allows to run it only once per second, which saves some CPU time.
  Previously it would run at 1000Hz, which was too much.

  Code ported from i386

  Make this the default on Intel systems.

- Use check_nmi_watchdog with local APIC based nmi

- Fix race in touch_nmi_watchdog

- Fix bug that caused incorrect performance counters to be programmed in a
  few cases on K8.

- Remove useless check for local APIC

- Use local_t and per_cpu variables for per CPU data.

- Keep other CPUs busy during check_nmi_watchdog to make sure they really
  tick when in lapic mode.

- Only check CPUs that are actually online.

- Various other fixes.

- Fix fallback path when MSRs are unimplemented
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!