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John Garry 9c880c24cb perf metricgroup: Fix for metrics containing duration_time 
Metrics containing duration_time cause a segfault:

  $ perf stat -v -M L1D_Cache_Fill_BW sleep 1
  Using CPUID GenuineIntel-6-3D-4
  metric expr 64 * l1d.replacement / 1000000000 / duration_time for L1D_Cache_Fill_BW
  found event duration_time
  found event l1d.replacement
  adding {l1d.replacement}:W,duration_time
  l1d.replacement -> cpu/umask=0x1,(null)=0x1e8483,event=0x51/
  Segmentation fault
  $

In commit c2337d6719 ("perf metricgroup: Fix metrics using aliases
covering multiple PMUs"), the logic in find_evsel_group() when iter'ing
events was changed to not only select events in same group, but also for
aliased PMUs.

Checking whether events were for aliased PMUs was done by comparing the
event PMU name. This was not safe for duration_time event, which has no
associated PMU (and no PMU name), so fix by checking if the event PMU name
is set also.

Committer testing:

Reproduced the bug, then, on a:

  $ grep -m1 ^'model name' /proc/cpuinfo
  model name	: Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz
  $

We now get:

  $ perf stat -M L1D_Cache_Fill_BW sleep 1

   Performance counter stats for 'sleep 1':

               4,141      l1d.replacement:u
       1,001,285,107 ns   duration_time:u

         1.001285107 seconds time elapsed

         0.000000000 seconds user
         0.001119000 seconds sys

  $

Detais from -v:

  Using CPUID GenuineIntel-6-8E-A
  metric expr 64 * l1d.replacement / 1000000000 / duration_time for L1D_Cache_Fill_BW
  found event duration_time
  found event l1d.replacement
  adding {l1d.replacement}:W,duration_time
  l1d.replacement -> cpu/(null)=0x1e8483,umask=0x1,event=0x51/
  Control descriptor is not initialized
  Warning:
  kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor  samples
  Warning:
  kernel.perf_event_paranoid=2, trying to fall back to excluding kernel and hypervisor  samples
  l1d.replacement:u: 4592 612201 612201
  duration_time:u: 1001478621 1001478621 1001478621

Fixes: c2337d6719 ("perf metricgroup: Fix metrics using aliases covering multiple PMUs")
Reported-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linuxarm@openeuler.org
Link: https://lore.kernel.org/r/1611159518-226883-1-git-send-email-john.garry@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2021-01-21 17:25:33 -03:00
arch xen: branch for v5.11-rc5 2021-01-20 11:46:38 -08:00
block block-5.11-2021-01-10 2021-01-10 12:53:08 -08:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto X.509: Fix crash caused by NULL pointer 2021-01-20 11:33:51 -08:00
Documentation Networking fixes for 5.11-rc5, including fixes from bpf, wireless, 2021-01-20 11:52:21 -08:00
drivers ACPI fix for 5.11-rc5 2021-01-21 11:28:30 -08:00
fs \n 2021-01-21 11:45:40 -08:00
include Networking fixes for 5.11-rc5, including fixes from bpf, wireless, 2021-01-20 11:52:21 -08:00
init Revert "init/console: Use ttynull as a fallback when there is no console" 2021-01-08 11:02:18 -08:00
ipc Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
kernel Printk fixes for 5.11-rc5 2021-01-21 11:37:22 -08:00
lib Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2021-01-17 12:16:47 -08:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm: don't put pinned pages into the swap cache 2021-01-17 12:08:04 -08:00
net Networking fixes for 5.11-rc5, including fixes from bpf, wireless, 2021-01-20 11:52:21 -08:00
samples ARM: SoC drivers for v5.11 2020-12-16 16:38:41 -08:00
scripts Kbuild fixes for v5.11 2021-01-10 13:24:55 -08:00
security dump_common_audit_data(): fix racy accesses to ->d_name 2021-01-16 15:11:35 -05:00
sound ALSA: usb-audio: Fix hw constraints dependencies 2021-01-20 21:46:45 +01:00
tools perf metricgroup: Fix for metrics containing duration_time 2021-01-21 17:25:33 -03:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt x86: 2021-01-08 15:06:02 -08:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MAINTAINERS: Update my email address 2021-01-15 23:55:16 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: dccp: move Gerrit Renker to CREDITS 2021-01-14 10:53:49 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS sound fixes for 5.11-rc5 2021-01-21 11:25:35 -08:00
Makefile Linux 5.11-rc4 2021-01-17 16:37:05 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.