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| author | Song Liu <songliubraving@fb.com> | 2020-07-23 21:06:46 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-07-26 06:16:35 +0300 |
| commit | d4b4dd6ce7709c2d2fe56dcfc15074ee18505bcb (patch) | |
| tree | 4f13bbdfc94518efcf3f275b3fb6650f5bf52cdc | |
| parent | 5d99cb2c86775b4780c02a339a9578bf9471ead9 (diff) | |
| download | linux-d4b4dd6ce7709c2d2fe56dcfc15074ee18505bcb.tar.xz | |
libbpf: Print hint when PERF_EVENT_IOC_SET_BPF returns -EPROTO
The kernel prevents potential unwinder warnings and crashes by blocking
BPF program with bpf_get_[stack|stackid] on perf_event without
PERF_SAMPLE_CALLCHAIN, or with exclude_callchain_[kernel|user]. Print a
hint message in libbpf to help the user debug such issues.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723180648.1429892-4-songliubraving@fb.com
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a05aa7e2bab6..e51479d60285 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -7833,6 +7833,9 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, pr_warn("program '%s': failed to attach to pfd %d: %s\n", bpf_program__title(prog, false), pfd, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); + if (err == -EPROTO) + pr_warn("program '%s': try add PERF_SAMPLE_CALLCHAIN to or remove exclude_callchain_[kernel|user] from pfd %d\n", + bpf_program__title(prog, false), pfd); return ERR_PTR(err); } if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { |