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Date: Tue, 8 Sep 2020 17:23:15 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Tiezhu Yang <yangtiezhu@...ngson.cn>, Arnaldo Carvalho de Melo <acme@...hat.com>, Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...hat.com>, Mark Rutland <mark.rutland@....com>, Namhyung Kim <namhyung@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Xuefeng Li <lixuefeng@...ngson.cn>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 5.8 053/186] perf top: Skip side-band event setup if HAVE_LIBBPF_SUPPORT is not set From: Tiezhu Yang <yangtiezhu@...ngson.cn> [ Upstream commit 0c5f1acc2a14416bf30023f373558d369afdbfc8 ] 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 [yangtiezhu@...ux 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@...ngson.cn> Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com> Cc: Jiri Olsa <jolsa@...hat.com> Cc: Mark Rutland <mark.rutland@....com> Cc: Namhyung Kim <namhyung@...nel.org> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Xuefeng Li <lixuefeng@...ngson.cn> Link: http://lore.kernel.org/lkml/1597753837-16222-1-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com> Signed-off-by: Sasha Levin <sashal@...nel.org> --- 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 13889d73f8dd5..c665d69c0651d 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"); -- 2.25.1
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