linux-kernel - [PATCH] perf top: Skip side-band event setup if HAVE_LIBBPF

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Date:   Tue, 18 Aug 2020 20:30:37 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Xuefeng Li <lixuefeng@...ngson.cn>
Subject: [PATCH] perf top: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set

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@...ux 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

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.

Fixes: b38d85ef49cf ("perf bpf: Decouple creating the evlist from adding the SB event")
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
 tools/perf/builtin-top.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 994c230..7c64134 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1746,6 +1746,7 @@ 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();

@@ -1759,6 +1760,7 @@ 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");
-- 
2.1.0