When a43eec3042 ("bpf: introduce bpf_perf_event_output() helper") added
PERF_COUNT_SW_BPF_OUTPUT we ended up with a new entry in the event_symbols_sw
array that wasn't initialized, thus set to NULL, fix print_symbol_events()
to check for that case so that we don't crash if this happens again.
(gdb) bt
#0 __match_glob (ignore_space=false, pat=<optimized out>, str=<optimized out>) at util/string.c:198
#1 strglobmatch (str=<optimized out>, pat=pat@entry=0x7fffffffe61d "stall") at util/string.c:252
#2 0x00000000004993a5 in print_symbol_events (type=1, syms=0x872880 <event_symbols_sw+160>, max=11, name_only=false, event_glob=0x7fffffffe61d "stall")
at util/parse-events.c:1615
#3 print_events (event_glob=event_glob@entry=0x7fffffffe61d "stall", name_only=false) at util/parse-events.c:1675
#4 0x000000000042c79e in cmd_list (argc=1, argv=0x7fffffffe390, prefix=<optimized out>) at builtin-list.c:68
#5 0x00000000004788a5 in run_builtin (p=p@entry=0x871758 <commands+120>, argc=argc@entry=2, argv=argv@entry=0x7fffffffe390) at perf.c:370
#6 0x0000000000420ab0 in handle_internal_command (argv=0x7fffffffe390, argc=2) at perf.c:429
#7 run_argv (argv=0x7fffffffe110, argcp=0x7fffffffe11c) at perf.c:473
#8 main (argc=2, argv=0x7fffffffe390) at perf.c:588
(gdb) p event_symbols_sw[PERF_COUNT_SW_BPF_OUTPUT]
$4 = {symbol = 0x0, alias = 0x0}
(gdb)
A patch to robustify perf to not segfault when the next counter gets added in
the kernel will follow this one.
Reported-by: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-57wysblcjfrseb0zg5u7ek10@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
fb202539e6