Re: perf list dumps core using 5.13.0.rc2

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Wed, May 19, 2021 at 01:26:23PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Wed, May 19, 2021 at 04:57:05PM +0200, Thomas Richter escreveu:
> > Using kernel 5.13.0.rc2 command perf list dumps core on my x86
> > virtual machine:
> > 
> > [root@f34 perf]# ./perf list
> > Segmentation fault (core dumped)
> > ^C
> > [root@f34 perf]#
> > 
> > The root case this this change in file ../include/uapi/linux/perf_event.h:
> > enum perf_sw_ids {
> >         PERF_COUNT_SW_CPU_CLOCK                 = 0,
> >         ...
> >  --->   PERF_COUNT_SW_CGROUP_SWITCHES           = 11,
> > 
> >         PERF_COUNT_SW_MAX,                      /* non-ABI */
> > };
> > 
> > This change increases PERF_COUNT_SW_MAX to 12. However this
> > change is not reflected in file util/parse-events.c where data structure
> > 
> > struct event_symbol event_symbols_sw[PERF_COUNT_SW_MAX] = {
> >         ....
> > }
> > 
> > is defined and it misses the symbol name and alias for this new software

Please check and provide your Acked-by or Reviewed-by,

Thanks,

- Arnaldo

From f8b0fe090267a901aa30070351b40f5e8abc0286 Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Wed, 19 May 2021 13:50:31 -0300
Subject: [PATCH 1/1] perf parse-events: Check if the software events array
 slots are populated

To avoid a NULL pointer dereference when the kernel supports the new
entry but the tooling still hasn't added an entry for it.

This happened with the recently added PERF_COUNT_SW_CGROUP_SWITCHES
software event.

Reported-by: Thomas Richter <tmricht@linux.ibm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/parse-events.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 4dad14265b81dfb8..8c5df56121d85cb2 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -2928,9 +2928,14 @@ void print_symbol_events(const char *event_glob, unsigned type,
 	}
 
 	for (i = 0; i < max; i++, syms++) {
+		/*
+		 * New attr.config still not supported here, the latest
+		 * example was PERF_COUNT_SW_CGROUP_SWITCHES
+		 */
+		if (syms->symbol == NULL)
+			continue;
 
-		if (event_glob != NULL && syms->symbol != NULL &&
-		    !(strglobmatch(syms->symbol, event_glob) ||
+		if (event_glob != NULL && !(strglobmatch(syms->symbol, event_glob) ||
 		      (syms->alias && strglobmatch(syms->alias, event_glob))))
 			continue;
 
-- 
2.31.1