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[PATCH 13/31] perf tools: Attach eBPF program to perf event

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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.c ls

In this patch 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.

Signed-off-by: Wang Nan <wangnan0@huawei.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: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/n/1436445342-1402-26-git-send-email-wangnan0@huawei.com
---
 tools/perf/util/evsel.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 6fff961..5f59841 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1365,6 +1365,22 @@ retry_open:
 					  err);
 				goto try_fallback;
 			}
+
+			if (evsel->bpf_fd >= 0) {
+				int evt_fd = FD(evsel, cpu, thread);
+				int bpf_fd = evsel->bpf_fd;
+
+				err = ioctl(evt_fd,
+					    PERF_EVENT_IOC_SET_BPF,
+					    bpf_fd);
+				if (err && errno != EEXIST) {
+					pr_err("failed to attach bpf fd %d: %s\n",
+					       bpf_fd, strerror(errno));
+					err = -EINVAL;
+					goto out_close;
+				}
+			}
+
 			set_rlimit = NO_CHANGE;
 
 			/*
-- 
2.1.0

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[GIT PULL 00/31] perf tools: filtering events using eBPF programs Wang Nan <wangnan0@huawei.com> - 2015-08-29 06:30 +0200
  [PATCH 18/31] perf test: Add 'perf test BPF' Wang Nan <wangnan0@huawei.com> - 2015-08-29 06:30 +0200
    Re: [PATCH 18/31] perf test: Add 'perf test BPF' Namhyung Kim <namhyung@kernel.org> - 2015-09-02 14:50 +0200
      Re: [PATCH 18/31] perf test: Add 'perf test BPF' Wang Nan <pi3orama@163.com> - 2015-09-05 14:30 +0200
  [PATCH 12/31] perf tools: Allow filter option to be applied to bof object Wang Nan <wangnan0@huawei.com> - 2015-08-29 06:40 +0200
  [PATCH 30/31] perf tools: Fix cross compiling error Wang Nan <wangnan0@huawei.com> - 2015-08-29 06:40 +0200
  [PATCH 05/31] perf ebpf: Add the libbpf glue Wang Nan <wangnan0@huawei.com> - 2015-08-29 06:40 +0200
  [PATCH 13/31] perf tools: Attach eBPF program to perf event Wang Nan <wangnan0@huawei.com> - 2015-08-29 06:50 +0200

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