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. Signed-off-by: Jin Yao <[email protected]> --- tools/perf/builtin-record.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index b6bdccd875bc..ae97f98e2753 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -1506,6 +1506,7 @@ static int record__synthesize(struct record *rec, bool tail) return err; } +#ifdef HAVE_LIBBPF_SUPPORT static int record__process_signal_event(union perf_event *event __maybe_unused, void *data) { struct record *rec = data; @@ -1550,6 +1551,12 @@ static int record__setup_sb_evlist(struct record *rec) return 0; } +#else +static int record__setup_sb_evlist(struct record *rec __maybe_unused) +{ + return 0; +} +#endif static int __cmd_record(struct record *rec, int argc, const char **argv) { -- 2.17.1
