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authorWang Nan <wangnan0@huawei.com>2015-10-14 12:41:18 +0000
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-10-29 17:16:22 -0300
commit1f45b1d49073541947193bd7dac9e904142576aa (patch)
tree4e3b5fde5f432b6e7d079ec9a9835064069634df /tools/perf/util/parse-events.c
parent50f1e6d0431d3343cb506037c43ce623bd15581f (diff)
downloadop-kernel-dev-1f45b1d49073541947193bd7dac9e904142576aa.zip
op-kernel-dev-1f45b1d49073541947193bd7dac9e904142576aa.tar.gz
perf bpf: Attach eBPF filter to perf event
This is the final patch which makes basic BPF filter work. After applying this patch, users are allowed to use BPF filter like: # perf record --event ./hello_world.o ls A bpf_fd field is appended to 'struct evsel', and setup during the callback function add_bpf_event() for each 'probe_trace_event'. PERF_EVENT_IOC_SET_BPF ioctl is used to attach eBPF program to a newly created perf event. The file descriptor of the eBPF program is passed to perf record using previous patches, and stored into evsel->bpf_fd. It is possible that different perf event are created for one kprobe events for different CPUs. In this case, when trying to call the ioctl, EEXIST will be return. This patch doesn't treat it as an error. Committer note: The bpf proggie used so far: __attribute__((section("fork=_do_fork"), used)) int fork(void *ctx) { return 0; } char _license[] __attribute__((section("license"), used)) = "GPL"; int _version __attribute__((section("version"), used)) = 0x40300; failed to produce any samples, even with forks happening and it being running in system wide mode. That is because now the filter is being associated, and the code above always returns zero, meaning that all forks will be probed but filtered away ;-/ Change it to 'return 1;' instead and after that: # trace --no-syscalls --event /tmp/foo.o 0.000 perf_bpf_probe:fork:(ffffffff8109be30)) 2.333 perf_bpf_probe:fork:(ffffffff8109be30)) 3.725 perf_bpf_probe:fork:(ffffffff8109be30)) 4.550 perf_bpf_probe:fork:(ffffffff8109be30)) ^C# And it works with all tools, including 'perf trace'. Signed-off-by: Wang Nan <wangnan0@huawei.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Brendan Gregg <brendan.d.gregg@gmail.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David Ahern <dsahern@gmail.com> Cc: He Kuang <hekuang@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kaixu Xia <xiakaixu@huawei.com> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1444826502-49291-8-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/parse-events.c')
-rw-r--r--tools/perf/util/parse-events.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index d97b037..cee8c61 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -542,6 +542,7 @@ static int add_bpf_event(struct probe_trace_event *tev, int fd,
struct __add_bpf_event_param *param = _param;
struct parse_events_evlist *evlist = param->data;
struct list_head *list = param->list;
+ struct perf_evsel *pos;
int err;
pr_debug("add bpf event %s:%s and attach bpf program %d\n",
@@ -562,6 +563,11 @@ static int add_bpf_event(struct probe_trace_event *tev, int fd,
}
pr_debug("adding %s:%s\n", tev->group, tev->event);
+ list_for_each_entry(pos, &new_evsels, node) {
+ pr_debug("adding %s:%s to %p\n",
+ tev->group, tev->event, pos);
+ pos->bpf_fd = fd;
+ }
list_splice(&new_evsels, list);
return 0;
}
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