This patch moves the die notifier handling to common code.  Previous
various architectures had exactly the same code for it.  Note that the new
code is compiled unconditionally, this should be understood as an appel to
the other architecture maintainer to implement support for it aswell (aka
sprinkling a notify_die or two in the proper place)

arm had a notifiy_die that did something totally different, I renamed it to
arm_notify_die as part of the patch and made it static to the file it's
declared and used at.  avr32 used to pass slightly less information through
this interface and I brought it into line with the other architectures.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: fix vmalloc_sync_all bustage]
[bryan.wu@analog.com: fix vmalloc_sync_all in nommu]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: <linux-arch@vger.kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- Introduce a wd_ops structure
- Convert the various nmi watchdogs over to it
- This allows to split the perfctr reservation from the watchdog
setup cleanly.
- Do perfctr reservation globally as it should have always been
- Remove dead code referenced only by unused EXPORT_SYMBOLs
Signed-off-by: NAndi Kleen <ak@suse.de>

All were already in some header
Signed-off-by: NAndi Kleen <ak@suse.de>

Hello,

This patch against 2.6.20-git14 makes the NMI watchdog use PERFSEL1/PERFCTR1
instead of PERFSEL0/PERFCTR0 on processors supporting Intel architectural
perfmon, such as Intel Core 2. Although all PMU events can work on
both counters, the Precise Event-Based Sampling (PEBS) requires that the
event be in PERFCTR0 to work correctly (see section 18.14.4.1 in the
IA32 SDM Vol 3b).

A similar patch for x86-64 is to follow.

Changelog:
        - make the i386 NMI watchdog use PERFSEL1/PERFCTR1 instead of PERFSEL0/PERFCTR0
          on processors supporting the Intel architectural perfmon (e.g. Core 2 Duo).
          This allows PEBS to work when the NMI watchdog is active.
signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Signed-off-by: NAndi Kleen <ak@suse.de>

While reviewing this code again I found a potential overflow of the bitmap.
The p4 oprofile can theoretically set bits beyond the reservation bitmap for
specific configurations. Avoid that by sizing the bitmaps properly.
Signed-off-by: NAndi Kleen <ak@suse.de>

A 4 core Opteron needs longer than 10 ticks for this.
Signed-off-by: NAndi Kleen <ak@suse.de>

The MSR reservation is per CPU and oprofile would only allocate them
on the CPU it was initialized on. Change this to handle all CPUs.

This also fixes a warning about unprotected use of smp_processor_id()
in preemptible kernels.
Signed-off-by: NAndi Kleen <ak@suse.de>

This reverts commit 6ebf622b and
replaces it with one that actually works.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The NMI watchdog implementation assumes that the local APIC timer interrupt is
happening.  This assumption is not longer true when high resolution timers and
dynamic ticks come into play, as they may switch off the local APIC timer
completely.  Take the PIT/HPET interrupts into account too, to avoid false
positives.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Rohit Seth <rohitseth@google.com>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For i386/x86-64.

Straight forward -- just reuse the Family 0xf code.
Signed-off-by: NAndi Kleen <ak@suse.de>

During kernel bootup, a new T60 laptop (CoreDuo, 32-bit) hangs about
10%-20% of the time in acpi_init():

 Calling initcall 0xc055ce1a: topology_init+0x0/0x2f()
 Calling initcall 0xc055d75e: mtrr_init_finialize+0x0/0x2c()
 Calling initcall 0xc05664f3: param_sysfs_init+0x0/0x175()
 Calling initcall 0xc014cb65: pm_sysrq_init+0x0/0x17()
 Calling initcall 0xc0569f99: init_bio+0x0/0xf4()
 Calling initcall 0xc056b865: genhd_device_init+0x0/0x50()
 Calling initcall 0xc056c4bd: fbmem_init+0x0/0x87()
 Calling initcall 0xc056dd74: acpi_init+0x0/0x1ee()

It's a hard hang that not even an NMI could punch through!  Frustratingly,
adding printks or function tracing to the ACPI code made the hangs go away
...

After some time an additional detail emerged: disabling the NMI watchdog
made these occasional hangs go away.

So i spent the better part of today trying to debug this and trying out
various theories when i finally found the likely reason for the hang: if
acpi_ns_initialize_devices() executes an _INI AML method and an NMI
happens to hit that AML execution in the wrong moment, the machine would
hang.  (my theory is that this must be some sort of chipset setup method
doing stores to chipset mmio registers?)

Unfortunately given the characteristics of the hang it was sheer
impossible to figure out which of the numerous AML methods is impacted
by this problem.

As a workaround i wrote an interface to disable chipset-based NMIs while
executing _INI sections - and indeed this fixed the hang.  I did a
boot-loop of 100 separate reboots and none hung - while without the patch
it would hang every 5-10 attempts.  Out of caution i did not touch the
nmi_watchdog=2 case (it's not related to the chipset anyway and didnt
hang).

I implemented this for both x86_64 and i686, tested the i686 laptop both
with nmi_watchdog=1 [which triggered the hangs] and nmi_watchdog=2, and
tested an Athlon64 box with the 64-bit kernel as well. Everything builds
and works with the patch applied.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

Change i386 nmi handler to handle 32 bit perfmon counter MSR writes cleanly.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Commit f2802e7f and its x86 version
(b7471c6d) adds nmi_known_cpu() check
while parsing boot options in x86_64 and i386.

With that, "nmi_watchdog=2" stops working for me on Intel Core 2 CPU
based system.

The problem is, setup_nmi_watchdog is called while parsing the boot
option and identify_cpu is not done yet.  So, the return value of
nmi_known_cpu() is not valid at this point.

So revert that check.  This should not have any adverse effect as the
nmi_known_cpu() check is done again later in enable_lapic_nmi_watchdog().
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

2.6.19  stopped booting (or booted based on build/config) on our x86_64
systems due to a bug introduced in 2.6.19.  check_nmi_watchdog schedules an
IPI on all cpus to  busy wait on a flag, but fails to set the busywait
flag if NMI functionality is disabled.  This causes the secondary cpus
to spin in an endless loop, causing the kernel bootup to hang.
Depending upon the build, the  busywait flag got overwritten (stack variable)
and caused  the kernel to bootup on certain builds.  Following patch fixes
the bug by setting the busywait flag before returning from check_nmi_watchdog.
I guess using a stack variable is not good here as the calling function could
potentially return while the busy wait loop is still spinning on the flag.

AK: I redid the patch significantly to be cleaner
Signed-off-by: NRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: NShai Fultheim <shai@scalex86.org>
Signed-off-by: NAndi Kleen <ak@suse.de>

Just like on x86-64, don't touch foreign CPUs' memory if the watchdog
isn't enabled at all.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

When a spinlock lockup occurs, arrange for the NMI code to emit an all-cpu
backtrace, so we get to see which CPU is holding the lock, and where.

Cc: Andi Kleen <ak@muc.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NAndi Kleen <ak@suse.de>

Even newer Thinkpads have bugs in SMM code that causes hangs with
NMI watchdog.
Signed-off-by: NAndi Kleen <ak@suse.de>

During tracking down a PAE compile failure, I found that config.h was being
included in a bunch of places in i386 code.  It is no longer necessary, so
drop it.
Signed-off-by: NZachary Amsden <zach@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Use prototypes in headers
Don't define panic_on_unrecovered_nmi for all architectures

Cc: dzickus@redhat.com
Signed-off-by: NAndi Kleen <ak@suse.de>

A kprobe executes IRET early and that could cause NMI recursion and stack
corruption.

Note: This problem was originally spotted and solved by Andi Kleen in the
x86_64 architecture. This patch is an adaption of his patch for i386.

AK: Merged with current code which was a bit different.
AK: Removed printk in nmi handler that shouldn't be there in the first time
AK: Added missing include.
AK: added KPROBES_END
Signed-off-by: NFernando Vazquez <fernando@intellilink.co.jp>
Signed-off-by: NAndi Kleen <ak@suse.de>

AK: This redoes the changes I temporarily reverted.

Intel now has support for Architectural Performance Monitoring Counters
( Refer to IA-32 Intel Architecture Software Developer's Manual
http://www.intel.com/design/pentium4/manuals/253669.htm ). This
feature is present starting from Intel Core Duo and Intel Core Solo processors.

What this means is, the performance monitoring counters and some performance
monitoring events are now defined in an architectural way (using cpuid).
And there will be no need to check for family/model etc for these architectural
events.

Below is the patch to use this performance counters in nmi watchdog driver.
Patch handles both i386 and x86-64 kernels.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

I've had good experiences with having this on by default on x86-64.
It turns nasty hangs into easier to debug oopses.

Enable the local APIC wdog by default for systems newer than 2004.

This comes from a strange compromise: according to arjan the reason
it was off by default was some old IBM systems that corrupted
registered when NMI happened in SMI. Can't remember more specific,
but >= 2004 should avoid these. It's probably overly broad
because most older systems should be ok (and the really old systems
won't be supported by the local apic watchdog anyways)
Signed-off-by: NAndi Kleen <ak@suse.de>

Making NMI suspend/resume work with SMP. We use CPU hotplug to offline
APs in SMP suspend/resume. Only BSP executes sysdev's .suspend/.resume
method. APs should follow CPU hotplug code path.

And:

+From: Don Zickus <dzickus@redhat.com>

Makes the start/stop paths of nmi watchdog more robust to handle the
suspend/resume cases more gracefully.

AK: I merged the two patches together
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Adds a new /proc/sys/kernel/nmi_watchdog call that will enable/disable the
nmi watchdog.

By entering a non-zero value here, a user can enable the nmi watchdog to
monitor the online cpus in the system.  By entering a zero value here, a
user can disable the nmi watchdog and free up a performance counter which
could then be utilized by the oprofile subsystem, otherwise oprofile may be
short a counter when in use.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Adds a new /proc/sys/kernel/nmi call that will enable/disable the nmi
watchdog.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Removes the un/set_nmi_callback and reserve/release_lapic_nmi functions as
they are no longer needed.  The various subsystems are modified to register
with the die_notifier instead.

Also includes compile fixes by Andrew Morton.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

This patch cleans up the NMI interrupt path.  Instead of being gated by if
the 'nmi callback' is set, the interrupt handler now calls everyone who is
registered on the die_chain and additionally checks the nmi watchdog,
reseting it if enabled.  This allows more subsystems to hook into the NMI if
they need to (without being block by set_nmi_callback).
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

This patch includes the changes to make the nmi watchdog on i386 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>

This makes merging easier.  They are readded a few patches later.
Signed-off-by: NAndi Kleen <ak@suse.de>

When resuming from suspend-to-RAM, the NMI watchdog detects a lockup in
ide_wait_not_busy.  Here's a screenshot of the trace taken by a digital
camera: http://www.uamt.feec.vutbr.cz/rizeni/pom/DSC03510-2.JPG

Let's touch the NMI watchdog in ide_wait_not_busy.  The system then resumes
correctly from STR.

[akpm@osdl.org: modular build fix]
Signed-off-by: NMichal Schmidt <xschmi00@stud.feec.vutbr.cz>
Acked-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make use of local_irq_enable_in_hardirq() API to annotate places that enable
hardirqs in hardirq context.

Has no effect on non-lockdep kernels.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Intel now has support for Architectural Performance Monitoring Counters
( Refer to IA-32 Intel Architecture Software Developer's Manual
http://www.intel.com/design/pentium4/manuals/253669.htm ). This
feature is present starting from Intel Core Duo and Intel Core Solo processors.

What this means is, the performance monitoring counters and some performance
monitoring events are now defined in an architectural way (using cpuid).
And there will be no need to check for family/model etc for these architectural
events.

Below is the patch to use this performance counters in nmi watchdog driver.
Patch handles both i386 and x86-64 kernels.
Signed-off-by: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

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>

Fix "signed vs unsigned" in nmi_watchdog_tick.
Signed-off-by: NJesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch replaces for_each_cpu with for_each_possible_cpu.

under arch/i386.
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

When we stop allocating percpu memory for not-possible CPUs we must not touch
the percpu data for not-possible CPUs at all.  The correct way of doing this
is to test cpu_possible() or to use for_each_cpu().

This patch is a kernel-wide sweep of all instances of NR_CPUS.  I found very
few instances of this bug, if any.  But the patch converts lots of open-coded
test to use the preferred helper macros.

Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Acked-by: NKyle McMartin <kyle@parisc-linux.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Christian Zankel <chris@zankel.net>
Cc: Philippe Elie <phil.el@wanadoo.fr>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Consolidate all kernel bug printouts to begin with the "BUG: " string.
Makes it easier to find them in large bootup logs.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix i386 nmi_watchdog that does not meet watchdog timeout condition.  It
does not hit die_nmi when it should be triggered, because the current
nmi_watchdog_tick in arch/i386/kernel/nmi.c never count up alert_counter
like this:

	void nmi_watchdog_tick (struct pt_regs * regs) {
	if (last_irq_sums[cpu] == sum) {
		alert_counter[cpu]++;		<- count up alert_counter, but
		if (alert_counter[cpu] == 5*nmi_hz)
			die_nmi(regs, "NMI Watchdog detected LOCKUP");
		alert_counter[cpu] = 0;		<- reset alert_counter

This patch changes it back to the previous and working version.

This was found and originally written by Kohta NAKASHIMA.

(akpm: also uninline write_watchdog_counter(), saving 184 byets)
Signed-off-by: NGOTO Masanori <gotom@sanori.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>