Currently, the NMI handler tests if it is nested by checking the
special variable saved on the stack (set during NMI handling)
and whether the saved stack is the NMI stack as well (to prevent
the race when the variable is set to zero).

But userspace may set their %rsp to any value as long as they do
not derefence it, and it may make it point to the NMI stack,
which will prevent NMIs from triggering while the userspace app
is running. (I tested this, and it is indeed the case)

Add another check to determine nested NMIs by looking at the
saved %cs (code segment register) and making sure that it is the
kernel code segment.
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/1329687817.1561.27.camel@acer.local.homeSigned-off-by: NIngo Molnar <mingo@elte.hu>

For L1 instruction cache and L2 cache the shared CPU information
is wrong. On current AMD family 15h CPUs those caches are shared
between both cores of a compute unit.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=42607Signed-off-by: NAndreas Herrmann <andreas.herrmann3@amd.com>
Cc: Petkov Borislav <Borislav.Petkov@amd.com>
Cc: Dave Jones <davej@redhat.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/20120208195229.GA17523@alberich.amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

AMD processors will never support /dev/cpu/microcode updating so
just silently fail instead of printing out a warning for every
cpu.
Signed-off-by: NPrarit Bhargava <prarit@redhat.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/1328552935-965-1-git-send-email-prarit@redhat.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

This commit removes the reboot quirk originally added by commit
e19e074b ("x86: Fix reboot problem on VersaLogic Menlow boards").

Testing with a VersaLogic Ocelot (VL-EPMs-21a rev 1.00 w/ BIOS
6.5.102) revealed the following regarding the reboot hang
problem:

- v2.6.37 reboot=bios was needed.

- v2.6.38-rc1: behavior changed, reboot=acpi is needed,
  reboot=kbd and reboot=bios results in system hang.

- v2.6.38: VersaLogic patch (e19e074b "x86: Fix reboot problem on
  VersaLogic Menlow boards") was applied prior to v2.6.38-rc7.  This
  patch sets a quirk for VersaLogic Menlow boards that forces the use
  of reboot=bios, which doesn't work anymore.

- v3.2: It seems that commit 660e34ce ("x86: Reorder reboot method
  preferences") changed the default reboot method to acpi prior to
  v3.0-rc1, which means the default behavior is appropriate for the
  Ocelot.  No VersaLogic quirk is required.

The Ocelot board used for testing can successfully reboot w/out
having to pass any reboot= arguments for all 3 current versions
of the BIOS.
Signed-off-by: NMichael D Labriola <michael.d.labriola@gmail.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Michael D Labriola <mlabriol@gdeb.com>
Cc: Kushal Koolwal <kushalkoolwal@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/87vcnub9hu.fsf@gmail.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

Skip DMI checks for vendor specific reboot quirks if the user
passed in a reboot= arg on the command line - we should never
override user choices.
Signed-off-by: NMichael D Labriola <michael.d.labriola@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Michael D Labriola <mlabriol@gdeb.com>
Cc: Matthew Garrett <mjg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/87wr8ab9od.fsf@gmail.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

Smatch complains that we have some inconsistent NULL checking.

If "task" were NULL then it would lead to a NULL dereference
later. We can remove this test because earlier on in the
function we have:

 if (!task)
	task = current;
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Clemens Ladisch <clemens@ladisch.de>
Link: http://lkml.kernel.org/r/20120128105246.GA25092@elgon.mountainSigned-off-by: NIngo Molnar <mingo@elte.hu>

rsyslog will display KERN_EMERG messages on a connected
terminal.  However, these messages are useless/undecipherable
for a general user.

For example, after a softlockup we get:

 Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
 kernel:Stack:

 Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
 kernel:Call Trace:

 Message from syslogd@intel-s3e37-04 at Jan 25 14:18:06 ...
 kernel:Code: ff ff a8 08 75 25 31 d2 48 8d 86 38 e0 ff ff 48 89
 d1 0f 01 c8 0f ae f0 48 8b 86 38 e0 ff ff a8 08 75 08 b1 01 4c 89 e0 0f 01 c9 <e8> ea 69 dd ff 4c 29 e8 48 89 c7 e8 0f bc da ff 49 89 c4 49 89

This happens because the printk levels for these messages are
incorrect. Only an informational message should be displayed on
a terminal.

I modified the printk levels for various messages in the kernel
and tested the output by using the drivers/misc/lkdtm.c kernel
modules (ie, softlockups, panics, hard lockups, etc.) and
confirmed that the console output was still the same and that
the output to the terminals was correct.

For example, in the case of a softlockup we now see the much
more informative:

 Message from syslogd@intel-s3e37-04 at Jan 25 10:18:06 ...
 BUG: soft lockup - CPU4 stuck for 60s!

instead of the above confusing messages.

AFAICT, the messages no longer have to be KERN_EMERG.  In the
most important case of a panic we set console_verbose().  As for
the other less severe cases the correct data is output to the
console and /var/log/messages.

Successfully tested by me using the drivers/misc/lkdtm.c module.
Signed-off-by: NPrarit Bhargava <prarit@redhat.com>
Cc: dzickus@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1327586134-11926-1-git-send-email-prarit@redhat.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

We've decided to provide CPU family specific container files
(starting with CPU family 15h). E.g. for family 15h we have to
load microcode_amd_fam15h.bin instead of microcode_amd.bin

Rationale is that starting with family 15h patch size is larger
than 2KB which was hard coded as maximum patch size in various
microcode loaders (not just Linux).

Container files which include patches larger than 2KB cause
different kinds of trouble with such old patch loaders. Thus we
have to ensure that the default container file provides only
patches with size less than 2KB.
Signed-off-by: NAndreas Herrmann <andreas.herrmann3@amd.com>
Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/20120120164412.GD24508@alberich.amd.com
[ documented the naming convention and tidied the code a bit. ]
Signed-off-by: NIngo Molnar <mingo@elte.hu>

JONGMAN HEO reports:

  With current linus git (commit a25a2b84), I got following build error,

  arch/x86/kernel/vm86_32.c: In function 'do_sys_vm86':
  arch/x86/kernel/vm86_32.c:340: error: implicit declaration of function '__audit_syscall_exit'
  make[3]: *** [arch/x86/kernel/vm86_32.o] Error 1

OK, I can reproduce it (32bit allmodconfig with AUDIT=y, AUDITSYSCALL=n)

It's due to commit d7e7528b: "Audit: push audit success and retcode
into arch ptrace.h".
Reported-by: NJONGMAN HEO <jongman.heo@samsung.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

pit_expect_msb() returns success wrongly in the below SMI scenario:

a. pit_verify_msb() has not yet seen the MSB transition.

b. we are close to the MSB transition though and got a SMI immediately after
   returning from pit_verify_msb() which didn't see the MSB transition. PIT MSB
   transition has happened somewhere during SMI execution.

c. returned from SMI and we noted down the 'tsc', saw the pit MSB change now and
   exited the loop to calculate 'deltatsc'. Instead of noting the TSC at the MSB
   transition, we are way off because of the SMI.  And as the SMI happened
   between the pit_verify_msb() and before the 'tsc' is recorded in the
   for loop, 'delattsc' (d1/d2 in quick_pit_calibrate()) will be small and
   quick_pit_calibrate() will not notice this error.

Depending on whether SMI disturbance happens while computing d1 or d2, we will
see the TSC calibrated value smaller or bigger than the expected value. As a
result, in a cluster we were seeing a variation of approximately +/- 20MHz in
the calibrated values, resulting in NTP failures.

  [ As far as the SMI source is concerned, this is a periodic SMI that gets
    disabled after ACPI is enabled by the OS. But the TSC calibration happens
    before the ACPI is enabled. ]

To address this, change pit_expect_msb() so that

 - the 'tsc' is the TSC in between the two reads that read the MSB
change from the PIT (same as before)

 - the 'delta' is the difference in TSC from *before* the MSB changed
to *after* the MSB changed.

Now the delta is twice as big as before (it covers four PIT accesses,
roughly 4us) and quick_pit_calibrate() will loop a bit longer to get
the calibrated value with in the 500ppm precision. As the delta (d1/d2)
covers four PIT accesses, actual calibrated result might be closer to
250ppm precision.

As the loop now takes longer to stabilize, double MAX_QUICK_PIT_MS to 50.

SMI disturbance will showup as much larger delta's and the loop will take
longer than usual for the result to be with in the accepted precision. Or will
fallback to slow PIT calibration if it takes more than 50msec.

Also while we are at this, remove the calibration correction that aims to
get the result to the middle of the error bars. We really don't know which
direction to correct into, so remove it.
Reported-and-tested-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1326843337.5291.4.camel@sbsiddha-mobl2Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Every arch calls:

if (unlikely(current->audit_context))
	audit_syscall_entry()

which requires knowledge about audit (the existance of audit_context) in
the arch code.  Just do it all in static inline in audit.h so that arch's
can remain blissfully ignorant.
Signed-off-by: NEric Paris <eparis@redhat.com>

The audit system previously expected arches calling to audit_syscall_exit to
supply as arguments if the syscall was a success and what the return code was.
Audit also provides a helper AUDITSC_RESULT which was supposed to simplify things
by converting from negative retcodes to an audit internal magic value stating
success or failure.  This helper was wrong and could indicate that a valid
pointer returned to userspace was a failed syscall.  The fix is to fix the
layering foolishness.  We now pass audit_syscall_exit a struct pt_reg and it
in turns calls back into arch code to collect the return value and to
determine if the syscall was a success or failure.  We also define a generic
is_syscall_success() macro which determines success/failure based on if the
value is < -MAX_ERRNO.  This works for arches like x86 which do not use a
separate mechanism to indicate syscall failure.

We make both the is_syscall_success() and regs_return_value() static inlines
instead of macros.  The reason is because the audit function must take a void*
for the regs.  (uml calls theirs struct uml_pt_regs instead of just struct
pt_regs so audit_syscall_exit can't take a struct pt_regs).  Since the audit
function takes a void* we need to use static inlines to cast it back to the
arch correct structure to dereference it.

The other major change is that on some arches, like ia64, MIPS and ppc, we
change regs_return_value() to give us the negative value on syscall failure.
THE only other user of this macro, kretprobe_example.c, won't notice and it
makes the value signed consistently for the audit functions across all archs.

In arch/sh/kernel/ptrace_64.c I see that we were using regs[9] in the old
audit code as the return value.  But the ptrace_64.h code defined the macro
regs_return_value() as regs[3].  I have no idea which one is correct, but this
patch now uses the regs_return_value() function, so it now uses regs[3].

For powerpc we previously used regs->result but now use the
regs_return_value() function which uses regs->gprs[3].  regs->gprs[3] is
always positive so the regs_return_value(), much like ia64 makes it negative
before calling the audit code when appropriate.
Signed-off-by: NEric Paris <eparis@redhat.com>
Acked-by: H. Peter Anvin <hpa@zytor.com> [for x86 portion]
Acked-by: Tony Luck <tony.luck@intel.com> [for ia64]
Acked-by: Richard Weinberger <richard@nod.at> [for uml]
Acked-by: David S. Miller <davem@davemloft.net> [for sparc]
Acked-by: Ralf Baechle <ralf@linux-mips.org> [for mips]
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [for ppc]

Some firmware will access memory in ACPI NVS region via APEI.  That
is, instructions in APEI ERST/EINJ table will read/write ACPI NVS
region.  The original resource conflict checking in APEI code will
check memory/ioport accessed by APEI via general resource management
mechanism.  But ACPI NVS region is marked as busy already, so that the
false resource conflict will prevent APEI ERST/EINJ to work.

To fix this, this patch record ACPI NVS regions, so that we can avoid
request resources for memory region inside it.
Signed-off-by: NHuang Ying <ying.huang@intel.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

When suspending, there was a large list of warnings going something like:

	Device 'machinecheck1' does not have a release() function, it is broken and must be fixed

This patch turns the static mce_devices into dynamically allocated, and
properly frees them when they are removed from the system.  It solves
the warning messages on my laptop here.
Reported-by: N"Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Reported-by: NLinus Torvalds <torvalds@linux-foundation.org>
Tested-by: NDjalal Harouni <tixxdz@opendz.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@amd64.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 8a25a2fd ("cpu: convert 'cpu' and 'machinecheck' sysdev_class
to a regular subsystem") changed how things are dealt with in the MCE
subsystem.  Some of the things that got broken due to this are CPU
hotplug and suspend/hibernate.

MCE uses per_cpu allocations of struct device.  So, when a CPU goes
offline and comes back online, in order to ensure that we start from a
clean slate with respect to the MCE subsystem, zero out the entire
per_cpu device structure to 0 before using it.
Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

module_param(bool) used to counter-intuitively take an int.  In
fddd5201 (mid-2009) we allowed bool or int/unsigned int using a messy
trick.

It's time to remove the int/unsigned int option.  For this version
it'll simply give a warning, but it'll break next kernel version.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Abstract the code sequence for adding a signal handler's sa_mask to
current->blocked because the sequence is identical for all architectures.
Furthermore, in the past some architectures actually got this code wrong,
so introduce a wrapper that all architectures can use.
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

SGI UV systems print a message during boot:

	UV: Found <num> blades

Due to packaging changes, the blade count is not accurate for
on the next generation of the platform. This patch corrects the
count.
Signed-off-by: NJack Steiner <steiner@sgi.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/20120106191900.GA19772@sgi.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

It was brought to my attention that my x86 change to use NMI in
the reboot path broke Intel Nehalem and Westmere boxes when
using kexec.

I realized I had mistyped the if statement in commit
3603a251 and stuck the ')' in
the wrong spot.  Putting it in the right spot fixes kexec again.

Doh.
Reported-by: NYinghai Lu <yinghai@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/1325866671-9797-1-git-send-email-dzickus@redhat.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

The MSI restore function will become a function pointer in an
x86_msi_ops struct. It defaults to the implementation in the
io_apic.c and msi.c. We piggyback on the indirection mechanism
introduced by "x86: Introduce x86_msi_ops".

Cc: x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-pci@vger.kernel.org
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

This factors out the AMD native MMCONFIG discovery so we can use it
outside amd_bus.c.

amd_bus.c reads AMD MSRs so it can remove the MMCONFIG area from the
PCI resources.  We may also need the MMCONFIG information to work
around BIOS defects in the ACPI MCFG table.

Cc: Borislav Petkov <borislav.petkov@amd.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: stable@kernel.org       # 2.6.34+
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

both callers of device_get_devnode() are only interested in lower 16bits
and nobody tries to return anything wider than 16bit anyway.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This has not been used for some years now.  It's time to remove it.
Signed-off-by: NChris Wright <chrisw@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

If the x2apic mode is disabled for reasons like interrupt-remapping
not available etc, then we need to skip the logical cpu bringup of
apic-id's >= 255. Otherwise as the platform is in xapic mode, init/startup
IPI's will consider only the low 8-bits and there is a possibility of
re-sending init/startup IPI's to the logical cpu that is already online.

This will avoid potential reboots/unpredictable behavior etc.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/20111222014632.702932458@sbsiddha-desk.sc.intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Currently "nox2apic" boot parameter was not enabling x2apic mode if the cpu,
kernel are all capable of enabling x2apic mode and the OS handover
happened in xapic mode.

However If the bios enabled x2apic prior to OS handover, using "nox2apic"
boot parameter had no effect.

If the boot cpu's apicid is < 255, enable "nox2apic" boot parameter to
disable the x2apic mode setup by the bios. This will enable the kernel to
fallback to xapic mode and bringup only the cpu's which has apic-id < 255.

-v2: fix patch error and two compiling warning
	make disable_x2apic to be __init
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/CAE9FiQUeB-3uxJAMiHsz=uPWoFv5Hg1pVepz7aU6YtqOxMC-=Q@mail.gmail.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

On some of the recent Intel SNB platforms, by default bios is pre-enabling
x2apic mode in the cpu with out setting up interrupt-remapping.
This case was resulting in the kernel to panic as the cpu is already in
x2apic mode but the OS was not able to enable interrupt-remapping (which
is a pre-req for using x2apic capability).

On these platforms all the apic-ids are < 255 and the kernel can fallback to
xapic mode if the bios has not enabled interrupt-remapping (which is
mostly the case if the bios has not exported interrupt-remapping tables to the
OS).
Reported-by: NBerck E. Nash <flyboy@gmail.com>
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/20111222014632.600418637@sbsiddha-desk.sc.intel.comSigned-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

If the x2apic feature is not present (either the cpu is not capable of it
or the user has disabled the feature using boot-parameter etc), ignore the
x2apic MADT and SRAT entries provided by the ACPI tables.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/20111222014632.540896503@sbsiddha-desk.sc.intel.comSigned-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Currently we start with the default apic_flat mode and switch to some other
apic model depending on the apic drivers acpi_madt_oem_check() routines and
later followed by the apic drivers probe() routines.

Once we selected non flat mode there was no case where we fall back to
flat mode again.

Upcoming changes allow bios-enabled x2apic mode to be disabled by the OS
if interrupt-remapping etc is not setup properly by the bios.

We now has a case for the apic to fall back to legacy flat mode during
apic driver probe() seqeuence. Add a simple flat_probe() which allows
the apic_flat mode to be the last fallback option.
Signed-off-by: NYinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/20111222014632.484984298@sbsiddha-desk.sc.intel.comSigned-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Use raw_spin_unlock_irqrestore() as equivalent to
raw_spin_lock_irqsave().
Signed-off-by: NRobert Richter <robert.richter@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1324646665-13334-1-git-send-email-robert.richter@amd.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

The sysdev.h file should not be needed by any in-kernel code, so remove
the .h file from these random files that seem to still want to include
it.

The sysdev code will be going away soon, so this include needs to be
removed no matter what.

Cc: Jiandong Zheng <jdzheng@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: David Brown <davidb@codeaurora.org>
Cc: Daniel Walker <dwalker@fifo99.com>
Cc: Bryan Huntsman <bryanh@codeaurora.org>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: "Venkatesh Pallipadi
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>

This moves the 'cpu sysdev_class' over to a regular 'cpu' subsystem
and converts the devices to regular devices. The sysdev drivers are
implemented as subsystem interfaces now.

After all sysdev classes are ported to regular driver core entities, the
sysdev implementation will be entirely removed from the kernel.

Userspace relies on events and generic sysfs subsystem infrastructure
from sysdev devices, which are made available with this conversion.

Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
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: Chris Metcalf <cmetcalf@tilera.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <bp@amd64.org>
Cc: Tigran Aivazian <tigran@aivazian.fsnet.co.uk>
Cc: Len Brown <lenb@kernel.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Mathieu Desnoyers pointed out a case that can cause issues with
NMIs running on the debug stack:

  int3 -> interrupt -> NMI -> int3

Because the interrupt changes the stack, the NMI will not see that
it preempted the debug stack. Looking deeper at this case,
interrupts only happen when the int3 is from userspace or in
an a location in the exception table (fixup).

  userspace -> int3 -> interurpt -> NMI -> int3

All other int3s that happen in the kernel should be processed
without ever enabling interrupts, as the do_trap() call will
panic the kernel if it is called to process any other location
within the kernel.

Adding a counter around the sections that enable interrupts while
using the debug stack allows the NMI to also check that case.
If the NMI sees that it either interrupted a task using the debug
stack or the debug counter is non-zero, then it will have to
change the IDT table to make the int3 not change stacks (which will
corrupt the stack if it does).

Note, I had to move the debug_usage functions out of processor.h
and into debugreg.h because of the static inlined functions to
inc and dec the debug_usage counter. __get_cpu_var() requires
smp.h which includes processor.h, and would fail to build.

Link: http://lkml.kernel.org/r/1323976535.23971.112.camel@gandalf.stny.rr.comReported-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Turner <pjt@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

With i386, NMIs and breakpoints use the current stack and they
do not reset the stack pointer to a fix point that might corrupt
a previous NMI or breakpoint (as it does in x86_64). But NMIs are
still not made to be re-entrant, and need to prevent the case that
an NMI hitting a breakpoint (which does an iret), doesn't allow
another NMI to run.

The fix is to let the NMI be in 3 different states:

1) not running
2) executing
3) latched

When no NMI is executing on a given CPU, the state is "not running".
When the first NMI comes in, the state is switched to "executing".
On exit of that NMI, a cmpxchg is performed to switch the state
back to "not running" and if that fails, the NMI is restarted.

If a breakpoint is hit and does an iret, which re-enables NMIs,
and another NMI comes in before the first NMI finished, it will
detect that the state is not in the "not running" state and the
current NMI is nested. In this case, the state is switched to "latched"
to let the interrupted NMI know to restart the NMI handler, and
the nested NMI exits without doing anything.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Turner <pjt@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

We want to allow NMI handlers to have breakpoints to be able to
remove stop_machine from ftrace, kprobes and jump_labels. But if
an NMI interrupts a current breakpoint, and then it triggers a
breakpoint itself, it will switch to the breakpoint stack and
corrupt the data on it for the breakpoint processing that it
interrupted.

Instead, have the NMI check if it interrupted breakpoint processing
by checking if the stack that is currently used is a breakpoint
stack. If it is, then load a special IDT that changes the IST
for the debug exception to keep the same stack in kernel context.
When the NMI is done, it puts it back.

This way, if the NMI does trigger a breakpoint, it will keep
using the same stack and not stomp on the breakpoint data for
the breakpoint it interrupted.
Suggested-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

In x86, when an NMI goes off, the CPU goes into an NMI context that
prevents other NMIs to trigger on that CPU. If an NMI is suppose to
trigger, it has to wait till the previous NMI leaves NMI context.
At that time, the next NMI can trigger (note, only one more NMI will
trigger, as only one can be latched at a time).

The way x86 gets out of NMI context is by calling iret. The problem
with this is that this causes problems if the NMI handle either
triggers an exception, or a breakpoint. Both the exception and the
breakpoint handlers will finish with an iret. If this happens while
in NMI context, the CPU will leave NMI context and a new NMI may come
in. As NMI handlers are not made to be re-entrant, this can cause
havoc with the system, not to mention, the nested NMI will write
all over the previous NMI's stack.

Linus Torvalds proposed the following workaround to this problem:

https://lkml.org/lkml/2010/7/14/264

"In fact, I wonder if we couldn't just do a software NMI disable
instead? Hav ea per-cpu variable (in the _core_ percpu areas that get
allocated statically) that points to the NMI stack frame, and just
make the NMI code itself do something like

 NMI entry:
 - load percpu NMI stack frame pointer
 - if non-zero we know we're nested, and should ignore this NMI:
    - we're returning to kernel mode, so return immediately by using
"popf/ret", which also keeps NMI's disabled in the hardware until the
"real" NMI iret happens.
    - before the popf/iret, use the NMI stack pointer to make the NMI
return stack be invalid and cause a fault
  - set the NMI stack pointer to the current stack pointer

 NMI exit (not the above "immediate exit because we nested"):
   clear the percpu NMI stack pointer
   Just do the iret.

Now, the thing is, now the "iret" is atomic. If we had a nested NMI,
we'll take a fault, and that re-does our "delayed" NMI - and NMI's
will stay masked.

And if we didn't have a nested NMI, that iret will now unmask NMI's,
and everything is happy."

I first tried to follow this advice but as I started implementing this
code, a few gotchas showed up.

One, is accessing per-cpu variables in the NMI handler.

The problem is that per-cpu variables use the %gs register to get the
variable for the given CPU. But as the NMI may happen in userspace,
we must first perform a SWAPGS to get to it. The NMI handler already
does this later in the code, but its too late as we have saved off
all the registers and we don't want to do that for a disabled NMI.

Peter Zijlstra suggested to keep all variables on the stack. This
simplifies things greatly and it has the added benefit of cache locality.

Two, faulting on the iret.

I really wanted to make this work, but it was becoming very hacky, and
I never got it to be stable. The iret already had a fault handler for
userspace faulting with bad segment registers, and getting NMI to trigger
a fault and detect it was very tricky. But for strange reasons, the system
would usually take a double fault and crash. I never figured out why
and decided to go with a simple "jmp" approach. The new approach I took
also simplified things.

Finally, the last problem with Linus's approach was to have the nested
NMI handler do a ret instead of an iret to give the first NMI NMI-context
again.

The problem is that ret is much more limited than an iret. I couldn't figure
out how to get the stack back where it belonged. I could have copied the
current stack, pushed the return onto it, but my fear here is that there
may be some place that writes data below the stack pointer. I know that
is not something code should depend on, but I don't want to chance it.
I may add this feature later, but for now, an NMI handler that loses NMI
context will not get it back.

Here's what is done:

When an NMI comes in, the HW pushes the interrupt stack frame onto the
per cpu NMI stack that is selected by the IST.

A special location on the NMI stack holds a variable that is set when
the first NMI handler runs. If this variable is set then we know that
this is a nested NMI and we process the nested NMI code.

There is still a race when this variable is cleared and an NMI comes
in just before the first NMI does the return. For this case, if the
variable is cleared, we also check if the interrupted stack is the
NMI stack. If it is, then we process the nested NMI code.

Why the two tests and not just test the interrupted stack?

If the first NMI hits a breakpoint and loses NMI context, and then it
hits another breakpoint and while processing that breakpoint we get a
nested NMI. When processing a breakpoint, the stack changes to the
breakpoint stack. If another NMI comes in here we can't rely on the
interrupted stack to be the NMI stack.

If the variable is not set and the interrupted task's stack is not the
NMI stack, then we know this is the first NMI and we can process things
normally. But in order to do so, we need to do a few things first.

1) Set the stack variable that tells us that we are in an NMI handler

2) Make two copies of the interrupt stack frame.
   One copy is used to return on iret
   The other is used to restore the first one if we have a nested NMI.

This is what the stack will look like:

	  +-------------------------+
	  | original SS             |
	  | original Return RSP     |
	  | original RFLAGS         |
	  | original CS             |
	  | original RIP            |
	  +-------------------------+
	  | temp storage for rdx    |
	  +-------------------------+
	  | NMI executing variable  |
	  +-------------------------+
	  | Saved SS                |
	  | Saved Return RSP        |
	  | Saved RFLAGS            |
	  | Saved CS                |
	  | Saved RIP               |
	  +-------------------------+
	  | copied SS               |
	  | copied Return RSP       |
	  | copied RFLAGS           |
	  | copied CS               |
	  | copied RIP              |
	  +-------------------------+
	  | pt_regs                 |
	  +-------------------------+

The original stack frame contains what the HW put in when we entered
the NMI.

We store %rdx as a temp variable to use. Both the original HW stack
frame and this %rdx storage will be clobbered by nested NMIs so we
can not rely on them later in the first NMI handler.

The next item is the special stack variable that is set when we execute
the rest of the NMI handler.

Then we have two copies of the interrupt stack. The second copy is
modified by any nested NMIs to let the first NMI know that we triggered
a second NMI (latched) and that we should repeat the NMI handler.

If the first NMI hits an exception or breakpoint that takes it out of
NMI context, if a second NMI comes in before the first one finishes,
it will update the copied interrupt stack to point to a fix up location
to trigger another NMI.

When the first NMI calls iret, it will instead jump to the fix up
location. This fix up location will copy the saved interrupt stack back
to the copy and execute the nmi handler again.

Note, the nested NMI knows enough to check if it preempted a previous
NMI handler while it is in the fixup location. If it has, it will not
modify the copied interrupt stack and will just leave as if nothing
happened. As the NMI handle is about to execute again, there's no reason
to latch now.

To test all this, I forced the NMI handler to call iret and take itself
out of NMI context. I also added assemble code to write to the serial to
make sure that it hits the nested path as well as the fix up path.
Everything seems to be working fine.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Turner <pjt@google.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Linus cleaned up the NMI handler but it still needs some comments to
explain why it uses save_paranoid but not paranoid_exit. Just to keep
others from adding that in the future, document why it's not used.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

The NMI handler uses the paranoid_exit routine that checks the
NEED_RESCHED flag, and if it is set and the return is for userspace,
then interrupts are enabled, the stack is swapped to the thread's stack,
and schedule is called. The problem with this is that we are still in an
NMI context until an iret is executed. This means that any new NMIs are
now starved until an interrupt or exception occurs and does the iret.

As NMIs can not be masked and can interrupt any location, they are
treated as a special case. NEED_RESCHED should not be set in an NMI
handler. The interruption by the NMI should not disturb the work flow
for scheduling. Any IPI sent to a processor after sending the
NEED_RESCHED would have to wait for the NMI anyway, and after the IPI
finishes the schedule would be called as required.

There is no reason to do anything special leaving an NMI. Remove the
call to paranoid_exit and do a simple return. This not only fixes the
bug of starved NMIs, but it also cleans up the code.

Link: http://lkml.kernel.org/r/CA+55aFzgM55hXTs4griX5e9=v_O+=ue+7Rj0PTD=M7hFYpyULQ@mail.gmail.comAcked-by: NAndi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Turner <pjt@google.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Add event maps for Intel x86 processors (with architected PMU v2 or later).

On AMD, there is frequency scaling but no Turbo. There is no core
cycle event not subject to frequency scaling, therefore we do not
provide a mapping.
Signed-off-by: NStephane Eranian <eranian@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1323559734-3488-4-git-send-email-eranian@google.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

This patch adds the encoding and definitions necessary for the
unhalted_reference_cycles event avaialble since Intel Core 2 processors.
Signed-off-by: NStephane Eranian <eranian@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1323559734-3488-2-git-send-email-eranian@google.comSigned-off-by: NIngo Molnar <mingo@elte.hu>

Several fields in struct cpuinfo_x86 were not defined for the
!SMP case, likely to save space.  However, those fields still
have some meaning for UP, and keeping them allows some #ifdef
removal from other files.  The additional size of the UP kernel
from this change is not significant enough to worry about
keeping up the distinction:

	   text    data     bss     dec     hex filename
	4737168	 506459	 972040	6215667	 5ed7f3	vmlinux.o.before
	4737444	 506459	 972040	6215943	 5ed907	vmlinux.o.after

for a difference of 276 bytes for an example UP config.

If someone wants those 276 bytes back badly then it should
be implemented in a cleaner way.
Signed-off-by: NKevin Winchester <kjwinchester@gmail.com>
Cc: Steffen Persvold <sp@numascale.com>
Link: http://lkml.kernel.org/r/1324428742-12498-1-git-send-email-kjwinchester@gmail.comSigned-off-by: NIngo Molnar <mingo@elte.hu>