From: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
[ Upstream commit 1101c872c8c7869c78dc106ae820040f36807eda ]
We received an error report that perf-record caused 'Segmentation fault'
on a newly system (e.g. on the new installed ubuntu).
(gdb) backtrace
#0 __read_once_size (size=4, res=<synthetic pointer>, p=0x14) at /root/0-jinyao/acme/tools/include/linux/compiler.h:139
#1 atomic_read (v=0x14) at /root/0-jinyao/acme/tools/include/asm/../../arch/x86/include/asm/atomic.h:28
#2 refcount_read (r=0x14) at /root/0-jinyao/acme/tools/include/linux/refcount.h:65
#3 perf_mmap__read_init (map=map@entry=0x0) at mmap.c:177
#4 0x0000561ce5c0de39 in perf_evlist__poll_thread (arg=0x561ce68584d0) at util/sideband_evlist.c:62
#5 0x00007fad78491609 in start_thread (arg=<optimized out>) at pthread_create.c:477
#6 0x00007fad7823c103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
The root cause is, evlist__add_bpf_sb_event() just returns 0 if
HAVE_LIBBPF_SUPPORT is not defined (inline function path). So it will
not create a valid evsel for side-band event.
But perf-record still creates BPF side band thread to process the
side-band event, then the error happpens.
We can reproduce this issue by removing the libelf-dev. e.g.
1. apt-get remove libelf-dev
2. perf record -a -- sleep 1
root@test:~# ./perf record -a -- sleep 1
perf: Segmentation fault
Obtained 6 stack frames.
./perf(+0x28eee8) [0x5562d6ef6ee8]
/lib/x86_64-linux-gnu/libc.so.6(+0x46210) [0x7fbfdc65f210]
./perf(+0x342e74) [0x5562d6faae74]
./perf(+0x257e39) [0x5562d6ebfe39]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x9609) [0x7fbfdc990609]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x43) [0x7fbfdc73b103]
Segmentation fault (core dumped)
To fix this issue,
1. We either install the missing libraries to let HAVE_LIBBPF_SUPPORT
be defined.
e.g. apt-get install libelf-dev and install other related libraries.
2. Use this patch to skip the side-band event setup if HAVE_LIBBPF_SUPPORT
is not set.
Committer notes:
The side band thread is not used just with BPF, it is also used with
--switch-output-event, so narrow the ifdef to the BPF specific part.
Fixes: 23cbb41c939a ("perf record: Move side band evlist setup to separate routine")
Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Jin Yao <yao.jin@xxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/20200805022937.29184-1-yao.jin@xxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/perf/builtin-record.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index a37e7910e9e90..23ea934f30b34 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1489,7 +1489,7 @@ static int record__setup_sb_evlist(struct record *rec)
evlist__set_cb(rec->sb_evlist, record__process_signal_event, rec);
rec->thread_id = pthread_self();
}
-
+#ifdef HAVE_LIBBPF_SUPPORT
if (!opts->no_bpf_event) {
if (rec->sb_evlist == NULL) {
rec->sb_evlist = evlist__new();
@@ -1505,7 +1505,7 @@ static int record__setup_sb_evlist(struct record *rec)
return -1;
}
}
-
+#endif
if (perf_evlist__start_sb_thread(rec->sb_evlist, &rec->opts.target)) {
pr_debug("Couldn't start the BPF side band thread:\nBPF programs starting from now on won't be annotatable\n");
opts->no_bpf_event = true;
--
2.25.1
