From: Jiri Olsa <jolsa@redhat.com>
To: Jin Yao <yao.jin@linux.intel.com>
Cc: acme@kernel.org, jolsa@kernel.org, peterz@infradead.org,
mingo@redhat.com, alexander.shishkin@linux.intel.com,
Linux-kernel@vger.kernel.org, ak@linux.intel.com,
kan.liang@intel.com, yao.jin@intel.com
Subject: Re: [PATCH] perf record: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set
Date: Thu, 6 Aug 2020 21:43:57 +0200 [thread overview]
Message-ID: <20200806194357.GA539212@krava> (raw)
In-Reply-To: <20200805022937.29184-1-yao.jin@linux.intel.com>
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
>
next prev parent reply other threads:[~2020-08-06 19:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-05 2:29 [PATCH] perf record: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set Jin Yao
2020-08-06 19:43 ` Jiri Olsa [this message]
2020-08-07 6:26 ` Jin, Yao
2020-08-07 12:08 ` Arnaldo Carvalho de Melo
2020-08-07 12:09 ` Arnaldo Carvalho de Melo
2020-08-07 12:16 ` Arnaldo Carvalho de Melo
2020-08-07 12:28 ` Arnaldo Carvalho de Melo
2020-08-10 0:35 ` Jin, Yao
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