This is a note to let you know that I've just added the patch titled
perf top: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-top-skip-side-band-event-setup-if-have_libbpf_support-is-not-set.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 0c5f1acc2a14416bf30023f373558d369afdbfc8 Mon Sep 17 00:00:00 2001
From: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
Date: Tue, 18 Aug 2020 20:30:37 +0800
Subject: perf top: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set
From: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
commit 0c5f1acc2a14416bf30023f373558d369afdbfc8 upstream.
When I execute 'perf top' without HAVE_LIBBPF_SUPPORT, there exists the
following segmentation fault, skip the side-band event setup to fix it,
this is similar with commit 1101c872c8c7 ("perf record: Skip side-band
event setup if HAVE_LIBBPF_SUPPORT is not set").
[yangtiezhu@linux perf]$ ./perf top
<SNIP>
perf: Segmentation fault
Obtained 6 stack frames.
./perf(sighandler_dump_stack+0x5c) [0x12011b604]
[0xffffffc010]
./perf(perf_mmap__read_init+0x3e) [0x1201feeae]
./perf() [0x1200d715c]
/lib64/libpthread.so.0(+0xab9c) [0xffee10ab9c]
/lib64/libc.so.6(+0x128f4c) [0xffedc08f4c]
Segmentation fault
[yangtiezhu@linux perf]$
I use git bisect to find commit b38d85ef49cf ("perf bpf: Decouple
creating the evlist from adding the SB event") is the first bad commit,
so also add the Fixes tag.
Committer testing:
First build perf explicitely disabling libbpf:
$ make NO_LIBBPF=1 O=/tmp/build/perf -C tools/perf install-bin && perf test python
Now make sure it isn't linked:
$ perf -vv | grep -w bpf
bpf: [ OFF ] # HAVE_LIBBPF_SUPPORT
$
$ nm ~/bin/perf | grep libbpf
$
And now try to run 'perf top':
# perf top
perf: Segmentation fault
-------- backtrace --------
perf[0x5bcd6d]
/lib64/libc.so.6(+0x3ca6f)[0x7fd0f5a66a6f]
perf(perf_mmap__read_init+0x1e)[0x5e1afe]
perf[0x4cc468]
/lib64/libpthread.so.0(+0x9431)[0x7fd0f645a431]
/lib64/libc.so.6(clone+0x42)[0x7fd0f5b2b912]
#
Applying this patch fixes the issue.
Fixes: b38d85ef49cf ("perf bpf: Decouple creating the evlist from adding the SB event")
Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Xuefeng Li <lixuefeng@xxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/1597753837-16222-1-git-send-email-yangtiezhu@xxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/perf/builtin-top.c | 2 ++
1 file changed, 2 insertions(+)
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1682,6 +1682,7 @@ int cmd_top(int argc, const char **argv)
goto out_delete_evlist;
}
+#ifdef HAVE_LIBBPF_SUPPORT
if (!top.record_opts.no_bpf_event) {
top.sb_evlist = evlist__new();
@@ -1695,6 +1696,7 @@ int cmd_top(int argc, const char **argv)
goto out_delete_evlist;
}
}
+#endif
if (perf_evlist__start_sb_thread(top.sb_evlist, target)) {
pr_debug("Couldn't start the BPF side band thread:\nBPF programs starting from now on won't be annotatable\n");
Patches currently in stable-queue which might be from yangtiezhu@xxxxxxxxxxx are
queue-5.4/perf-top-skip-side-band-event-setup-if-have_libbpf_support-is-not-set.patch
