releases/4.20.16/perf-script-fix-crash-when-processing-recorded-stat-.patch

   1 From da0e5b7cee1cf8a699a9a6cf863ee97ab65f1fd4 Mon Sep 17 00:00:00 2001
   2 From: Tony Jones <tonyj@suse.de>
   3 Date: Sun, 20 Jan 2019 11:14:14 -0800
   4 Subject: perf script: Fix crash when processing recorded stat data
   5
   6 [ Upstream commit 8bf8c6da53c2265aea365a1de6038f118f522113 ]
   7
   8 While updating perf to work with Python3 and Python2 I noticed that the
   9 stat-cpi script was dumping core.
  10
  11 $ perf  stat -e cycles,instructions record -o /tmp/perf.data /bin/false
  12
  13  Performance counter stats for '/bin/false':
  14
  15            802,148      cycles
  16
  17            604,622      instructions                                                       802,148      cycles
  18            604,622      instructions
  19
  20        0.001445842 seconds time elapsed
  21
  22 $ perf script -i /tmp/perf.data -s scripts/python/stat-cpi.py
  23 Segmentation fault (core dumped)
  24 ...
  25 ...
  26     rblist=rblist@entry=0xb2a200 <rt_stat>,
  27     new_entry=new_entry@entry=0x7ffcb755c310) at util/rblist.c:33
  28     ctx=<optimized out>, type=<optimized out>, create=<optimized out>,
  29     cpu=<optimized out>, evsel=<optimized out>) at util/stat-shadow.c:118
  30     ctx=<optimized out>, type=<optimized out>, st=<optimized out>)
  31     at util/stat-shadow.c:196
  32     count=count@entry=727442, cpu=cpu@entry=0, st=0xb2a200 <rt_stat>)
  33     at util/stat-shadow.c:239
  34     config=config@entry=0xafeb40 <stat_config>,
  35     counter=counter@entry=0x133c6e0) at util/stat.c:372
  36 ...
  37 ...
  38
  39 The issue is that since 1fcd03946b52 perf_stat__update_shadow_stats now calls
  40 update_runtime_stat passing rt_stat rather than calling update_stats but
  41 perf_stat__init_shadow_stats has never been called to initialize rt_stat in
  42 the script path processing recorded stat data.
  43
  44 Since I can't see any reason why perf_stat__init_shadow_stats() is presently
  45 initialized like it is in builtin-script.c::perf_sample__fprint_metric()
  46 [4bd1bef8bba2f] I'm proposing it instead be initialized once in __cmd_script
  47
  48 Committer testing:
  49
  50 After applying the patch:
  51
  52   # perf script -i /tmp/perf.data -s tools/perf/scripts/python/stat-cpi.py
  53        0.001970: cpu -1, thread -1 -> cpi 1.709079 (1075684/629394)
  54   #
  55
  56 No segfault.
  57
  58 Signed-off-by: Tony Jones <tonyj@suse.de>
  59 Reviewed-by: Jiri Olsa <jolsa@kernel.org>
  60 Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  61 Tested-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
  62 Cc: Andi Kleen <ak@linux.intel.com>
  63 Cc: Jin Yao <yao.jin@linux.intel.com>
  64 Fixes: 1fcd03946b52 ("perf stat: Update per-thread shadow stats")
  65 Link: http://lkml.kernel.org/r/20190120191414.12925-1-tonyj@suse.de
  66 Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  67 Signed-off-by: Sasha Levin <sashal@kernel.org>
  68 ---
  69  tools/perf/builtin-script.c | 7 ++-----
  70  1 file changed, 2 insertions(+), 5 deletions(-)
  71
  72 diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
  73 index 5c070a600233..d8791e0e5f75 100644
  74 --- a/tools/perf/builtin-script.c
  75 +++ b/tools/perf/builtin-script.c
  76 @@ -1633,13 +1633,8 @@ static void perf_sample__fprint_metric(struct perf_script *script,
  77                 .force_header = false,
  78         };
  79         struct perf_evsel *ev2;
  80 -       static bool init;
  81         u64 val;
  82
  83 -       if (!init) {
  84 -               perf_stat__init_shadow_stats();
  85 -               init = true;
  86 -       }
  87         if (!evsel->stats)
  88                 perf_evlist__alloc_stats(script->session->evlist, false);
  89         if (evsel_script(evsel->leader)->gnum++ == 0)
  90 @@ -2305,6 +2300,8 @@ static int __cmd_script(struct perf_script *script)
  91
  92         signal(SIGINT, sig_handler);
  93
  94 +       perf_stat__init_shadow_stats();
  95 +
  96         /* override event processing functions */
  97         if (script->show_task_events) {
  98                 script->tool.comm = process_comm_event;
  99 --
 100 2.19.1
 101