Messages in this thread | | | Date | Thu, 6 Aug 2020 21:43:57 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf record: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set |
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On Wed, Aug 05, 2020 at 10:29:37AM +0800, Jin Yao wrote: > 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
hum, I recall discussing the same issue, I thought it was already fixed :-\ in any case:
Acked-by: Jiri Olsa <jolsa@redhat.com>
thanks, jirka
> > 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 <yao.jin@linux.intel.com> > --- > 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 >
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