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[PATCH 10/29] 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 ae9ad2d..40b2722 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1331,6 +1331,22 @@ 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 00/29] perf tools: filtering events using eBPF programs Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 25/29] perf record: Support custom vmlinux path Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 14/29] perf tests: Enforce LLVM test for BPF test Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 18/29] perf probe: Reset args and nargs for probe_trace_event when failure Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 11/29] perf tools: Suppress probing messages when probing by BPF loading Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 13/29] perf tools: Infrastructure for compiling scriptlets when passing '.c' to --event Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 19/29] perf tools: Move linux/filter.h to tools/include Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 05/29] perf probe: Attach trace_probe_event with perf_probe_event Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 21/29] perf tools: Introduce arch_get_reg_info() for x86 Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 03/29] perf ebpf: Add the libbpf glue Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 10/29] perf tools: Attach eBPF program to perf event Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 01/29] perf probe: Try to use symbol table if searching debug info failed Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
    Re: [PATCH 01/29] perf probe: Try to use symbol table if searching  debug info failed Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-08-21 16:20 +0200
    [tip:perf/core] perf probe:   Try to use symbol table if searching debug info failed tip-bot for Wang Nan <tipbot@zytor.com> - 2015-08-22 09:00 +0200
  [PATCH 16/29] bpf tools: Load a program with different instances using preprocessor Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 07/29] perf bpf: Collect 'struct perf_probe_event' for bpf_program Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 04/29] perf tools: Enable passing bpf object file to --event Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 20/29] perf tools: Add BPF_PROLOGUE config options for further patches Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 24/29] perf tools: Use same BPF program if arguments are identical Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 23/29] perf tools: Generate prologue for BPF programs Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 02/29] perf tools: Make perf depend on libbpf Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 29/29] bpf: Introduce function for outputing data to perf event Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 12/29] perf record: Add clang options for compiling BPF scripts Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 06/29] perf record, bpf: Parse and probe eBPF programs probe points Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 27/29] perf tools: Support attach BPF program on uprobe events Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 17/29] perf tools: Fix probe-event.h include Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 28/29] tools lib traceevent: Support function __get_dynamic_array_len Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
    Re: [PATCH 28/29] tools lib traceevent: Support function  __get_dynamic_array_len Arnaldo Carvalho de Melo <acme@redhat.com> - 2015-08-21 18:10 +0200
  [PATCH 15/29] perf test: Add 'perf test BPF' Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:20 +0200
  [PATCH 08/29] perf record: Load all eBPF object into kernel Wang Nan <wangnan0@huawei.com> - 2015-08-21 12:30 +0200

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