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Groups > linux.kernel > #1203819

[PATCH 09/27] 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 4a8acea..f8668da 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1264,6 +1264,22 @@ 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;
 
 			/*
-- 
1.8.3.4

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[GIT PULL 00/27] perf tools: filtering events using eBPF programs Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:20 +0200
  [PATCH 23/27] perf tools: Generate prologue for BPF programs Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:20 +0200
  [PATCH 18/27] perf probe: Reset args and nargs for probe_trace_event when failure Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:20 +0200
  [PATCH 02/27] perf ebpf: Add the libbpf glue Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 07/27] perf record: Load all eBPF object into kernel Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 10/27] perf tools: Suppress probing messages when probing by BPF loading Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 20/27] perf tools: Add BPF_PROLOGUE config options for further patches Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 25/27] perf record: Support custom vmlinux path Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 16/27] bpf tools: Load a program with different instances using preprocessor Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 09/27] perf tools: Attach eBPF program to perf event Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 01/27] perf tools: Make perf depend on libbpf Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 12/27] perf tools: Infrastructure for compiling scriptlets when passing '.c' to --event Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 11/27] perf record: Add clang options for compiling BPF scripts Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 04/27] perf probe: Attach trace_probe_event with perf_probe_event Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 08/27] perf tools: Add bpf_fd field to evsel and config it Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 03/27] perf tools: Enable passing bpf object file to --event Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200
  [PATCH 13/27] perf tests: Enforce LLVM test for BPF test Wang Nan <wangnan0@huawei.com> - 2015-08-10 08:30 +0200

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