5.4-stable review patch. If anyone has any objections, please let me know.
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From: Tiezhu Yang yangtiezhu@loongson.cn
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@loongson.cn Tested-by: Arnaldo Carvalho de Melo acme@redhat.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Jiri Olsa jolsa@redhat.com Cc: Mark Rutland mark.rutland@arm.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Cc: Xuefeng Li lixuefeng@loongson.cn Link: http://lore.kernel.org/lkml/1597753837-16222-1-git-send-email-yangtiezhu@loo... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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");