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Kan Liang fd583ad156 perf/x86: Fix spurious NMI with PEBS Load Latency event
Spurious NMIs will be observed with the following command:

  while :; do
    perf record -bae "cpu/umask=0x01,event=0xcd,ldlat=0x80/pp"
                  -e "cpu/umask=0x03,event=0x0/"
                  -e "cpu/umask=0x02,event=0x0/"
                  -e cycles,branches,cache-misses
                  -e cache-references -- sleep 10
  done

The bug was introduced by commit:

  8077eca079 ("perf/x86/pebs: Add workaround for broken OVFL status on HSW+")

That commit clears the status bits for the counters used for PEBS
events, by masking the whole 64 bits pebs_enabled. However, only the
low 32 bits of both status and pebs_enabled are reserved for PEBS-able
counters.

For status bits 32-34 are fixed counter overflow bits. For
pebs_enabled bits 32-34 are for PEBS Load Latency.

In the test case, the PEBS Load Latency event and fixed counter event
could overflow at the same time. The fixed counter overflow bit will
be cleared by mistake. Once it is cleared, the fixed counter overflow
never be processed, which finally trigger spurious NMI.

Correct the PEBS enabled mask by ignoring the non-PEBS bits.

Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 8077eca079 ("perf/x86/pebs: Add workaround for broken OVFL status on HSW+")
Link: http://lkml.kernel.org/r/1491333246-3965-1-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-04-14 10:31:39 +02:00
Documentation Linux 4.11-rc6 2017-04-11 08:42:47 +02:00
arch perf/x86: Fix spurious NMI with PEBS Load Latency event 2017-04-14 10:31:39 +02:00
block blk-mq: Restart a single queue if tag sets are shared 2017-04-07 12:40:09 -06:00
certs certs: Add a secondary system keyring that can be added to dynamically 2016-04-11 22:48:09 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-03-31 12:11:32 -07:00
drivers Merge branch 'perf/urgent' into perf/core, to pick up fixes 2017-04-12 07:28:25 +02:00
firmware WHENCE: use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:35:11 -02:00
fs Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6 2017-04-09 09:10:02 -07:00
include Linux 4.11-rc6 2017-04-11 08:42:47 +02:00
init mm: move mm_percpu_wq initialization earlier 2017-03-31 17:13:30 -07:00
ipc Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
kernel Linux 4.11-rc6 2017-04-11 08:42:47 +02:00
lib Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-04-02 09:18:59 -07:00
mm mm/mempolicy.c: fix error handling in set_mempolicy and mbind. 2017-04-08 10:57:55 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-04-05 20:17:38 -07:00
samples statx: Include a mask for stx_attributes in struct statx 2017-04-03 01:06:00 -04:00
scripts Kbuild fixes for v4.11 2017-04-05 08:37:28 -07:00
security Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
sound ALSA: hda - fix a problem for lineout on a Dell AIO machine 2017-03-31 10:58:26 +02:00
tools Merge branch 'perf/urgent' into perf/core, to pick up fixes 2017-04-12 07:28:25 +02:00
usr kbuild: initramfs cleanup, set target from Kconfig 2017-01-05 09:40:16 -08:00
virt KVM/ARM Fixes for v4.11-rc6 2017-04-05 16:27:47 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:48:52 -04:00
.mailmap mailmap: update Yakir Yang email address 2017-04-08 00:47:49 -07:00
COPYING
CREDITS MAINTAINERS: Remove old e-mail address 2017-02-13 12:24:56 -05:00
Kbuild scripts/gdb: provide linux constants 2016-05-23 17:04:14 -07:00
Kconfig
MAINTAINERS Driver core fixes for 4.11-rc6 2017-04-09 09:03:51 -07:00
Makefile Linux 4.11-rc6 2017-04-09 09:49:44 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.