linux-toradex.git/arch/x86/kernel/nmi.c, branch v4.4.26

Merge branch 'x86/urgent' into x86/asm, before applying dependent patches

2015-07-31T08:23:35+00:00

Signed-off-by: Ingo Molnar

x86/nmi: Remove the 'b2b' parameter from nmi_handle()

2015-07-21T06:02:32+00:00

It has never had any effect. Remove it for comprehensibility.

Signed-off-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/c91fa38507760d9e54a4b8737fa6409bde896b33.1437418322.git.luto@kernel.org
Signed-off-by: Ingo Molnar

x86/nmi/64: Improve nested NMI comments

2015-07-17T10:50:11+00:00

I found the nested NMI documentation to be difficult to follow.
Improve the comments.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Steven Rostedt 
Cc: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar

x86/nmi: Enable nested do_nmi() handling for 64-bit kernels

2015-07-17T10:50:10+00:00

32-bit kernels handle nested NMIs in C.  Enable the exact same
handling on 64-bit kernels as well.  This isn't currently
necessary, but it will become necessary once the asm code starts
allowing limited nesting.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Steven Rostedt 
Cc: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Signed-off-by: Ingo Molnar

kprobes, x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation

2014-04-24T08:26:38+00:00

Use NOKPROBE_SYMBOL macro for protecting functions
from kprobes instead of __kprobes annotation under
arch/x86.

This applies nokprobe_inline annotation for some cases,
because NOKPROBE_SYMBOL() will inhibit inlining by
referring the symbol address.

This just folds a bunch of previous NOKPROBE_SYMBOL()
cleanup patches for x86 to one patch.

Signed-off-by: Masami Hiramatsu 
Link: http://lkml.kernel.org/r/20140417081814.26341.51656.stgit@ltc230.yrl.intra.hitachi.co.jp
Cc: Andrew Morton 
Cc: Arnaldo Carvalho de Melo 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: Fernando Luis Vázquez Cao 
Cc: Gleb Natapov 
Cc: Jason Wang 
Cc: Jesper Nilsson 
Cc: Jiri Kosina 
Cc: Jiri Olsa 
Cc: Jiri Slaby 
Cc: Johannes Weiner 
Cc: Jonathan Lebon 
Cc: Kees Cook 
Cc: Matt Fleming 
Cc: Michel Lespinasse 
Cc: Paolo Bonzini 
Cc: Paul E. McKenney 
Cc: Paul Gortmaker 
Cc: Paul Mackerras 
Cc: Raghavendra K T 
Cc: Rusty Russell 
Cc: Seiji Aguchi 
Cc: Srivatsa Vaddagiri 
Cc: Tejun Heo 
Cc: Vineet Gupta 
Signed-off-by: Ingo Molnar

x86/nmi: Push duration printk() to irq context

2014-02-09T12:17:22+00:00

Calling printk() from NMI context is bad (TM), so move it to IRQ
context.

In doing so we slightly change (probably wreck) the debugfs
nmi_longest_ns thingy, in that it doesn't update to reflect the
longest, nor does writing to it reset the count.

Signed-off-by: Peter Zijlstra 
Cc: Don Zickus 
Cc: Dave Hansen 
Link: http://lkml.kernel.org/n/tip-rdw0au56a5ymis1u8p48c12d@git.kernel.org
Signed-off-by: Ingo Molnar

perf/x86: Fix NMI measurements

2013-10-29T11:01:20+00:00

OK, so what I'm actually seeing on my WSM is that sched/clock.c is
'broken' for the purpose we're using it for.

What triggered it is that my WSM-EP is broken :-(

  [    0.001000] tsc: Fast TSC calibration using PIT
  [    0.002000] tsc: Detected 2533.715 MHz processor
  [    0.500180] TSC synchronization [CPU#0 -> CPU#6]:
  [    0.505197] Measured 3 cycles TSC warp between CPUs, turning off TSC clock.
  [    0.004000] tsc: Marking TSC unstable due to check_tsc_sync_source failed

For some reason it consistently detects TSC skew, even though NHM+
should have a single clock domain for 'reasonable' systems.

This marks sched_clock_stable=0, which means that we do fancy stuff to
try and get a 'sane' clock. Part of this fancy stuff relies on the tick,
clearly that's gone when NOHZ=y. So for idle cpus time gets stuck, until
it either wakes up or gets kicked by another cpu.

While this is perfectly fine for the scheduler -- it only cares about
actually running stuff, and when we're running stuff we're obviously not
idle. This does somewhat break down for perf which can trigger events
just fine on an otherwise idle cpu.

So I've got NMIs get get 'measured' as taking ~1ms, which actually
don't last nearly that long:

          -0     [013] d.h.   886.311970: rcu_nmi_enter <-do_nmi
  ...
          -0     [013] d.h.   886.311997: perf_sample_event_took: HERE!!! : 1040990

So ftrace (which uses sched_clock(), not the fancy bits) only sees
~27us, but we measure ~1ms !!

Now since all this measurement stuff lives in x86 code, we can actually
fix it.

Signed-off-by: Peter Zijlstra 
Cc: mingo@kernel.org
Cc: dave.hansen@linux.intel.com
Cc: eranian@google.com
Cc: Don Zickus 
Cc: jmario@redhat.com
Cc: acme@infradead.org
Link: http://lkml.kernel.org/r/20131017133350.GG3364@laptop.programming.kicks-ass.net
Signed-off-by: Ingo Molnar

perf/x86: Fix incorrect use of do_div() in NMI warning

2013-07-12T12:13:04+00:00

I completely botched understanding the calling conventions of
do_div().  I assumed that do_div() returned the result instead
of realizing that it modifies its argument and returns a
remainder.  The side-effect from this would be bogus numbers
for the "msecs" value in the warning messages:

	INFO: NMI handler (perf_event_nmi_handler) took too long to run: 0.114 msecs

Note, there was a second fix posted by Stephane Eranian for
a separate patch which I also botched:

	http://lkml.kernel.org/r/20130704223010.GA30625@quad

Signed-off-by: Dave Hansen 
Cc: Dave Hansen 
Link: http://lkml.kernel.org/r/20130708214404.B0B6EA66@viggo.jf.intel.com
Signed-off-by: Ingo Molnar

x86: Add NMI duration tracepoints

2013-06-23T09:52:58+00:00

This patch has been invaluable in my adventures finding
issues in the perf NMI handler.  I'm as big a fan of
printk() as anybody is, but using printk() in NMIs is
deadly when they're happening frequently.

Even hacking in trace_printk() ended up eating enough
CPU to throw off some of the measurements I was making.

Signed-off-by: Dave Hansen 
Acked-by: Peter Zijlstra 
Cc: paulus@samba.org
Cc: acme@ghostprotocols.net
Cc: Dave Hansen 
Signed-off-by: Ingo Molnar

x86: Warn when NMI handlers take large amounts of time

2013-06-23T09:52:56+00:00

I have a system which is causing all kinds of problems.  It has
8 NUMA nodes, and lots of cores that can fight over cachelines.
If things are not working _perfectly_, then NMIs can take longer
than expected.

If we get too many of them backed up to each other, we can
easily end up in a situation where we are doing nothing *but*
running NMIs.  The biggest problem, though, is that this happens
_silently_.  You might be lucky to get an hrtimer warning, but
most of the time system simply hangs.

This patch should at least give us some warning before we fall
off the cliff.  the warnings look like this:

	nmi_handle: perf_event_nmi_handler() took: 26095071 ns

The message is triggered whenever we notice the longest NMI
we've seen to date.  You can always view and reset this value
via the debugfs interface if you like.

Signed-off-by: Dave Hansen 
Acked-by: Peter Zijlstra 
Cc: paulus@samba.org
Cc: acme@ghostprotocols.net
Cc: Dave Hansen 
Signed-off-by: Ingo Molnar