perf tools: Load eBPF object into kernel

This patch utilizes bpf_object__load() provided by libbpf to load all
objects into kernel.

Committer notes:

Testing it:

When using an incorrect kernel version number, i.e., having this in your
eBPF proggie:

  int _version __attribute__((section("version"), used)) = 0x40100;

For a 4.3.0-rc6+ kernel, say, this happens and needs checking at event
parsing time, to provide a better error report to the user:

  # perf record --event /tmp/foo.o sleep 1
  libbpf: load bpf program failed: Invalid argument
  libbpf: -- BEGIN DUMP LOG ---
  libbpf:

  libbpf: -- END LOG --
  libbpf: failed to load program 'fork=_do_fork'
  libbpf: failed to load object '/tmp/foo.o'
  event syntax error: '/tmp/foo.o'
                       \___ Invalid argument: Are you root and runing a CONFIG_BPF_SYSCALL kernel?

  (add -v to see detail)
  Run 'perf list' for a list of valid events

   Usage: perf record [<options>] [<command>]
      or: perf record [<options>] -- <command> [<options>]

      -e, --event <event>   event selector. use 'perf list' to list available events

If we instead make it match, i.e. use 0x40300 on this v4.3.0-rc6+
kernel, the whole process goes thru:

  # perf record --event /tmp/foo.o -a usleep 1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.202 MB perf.data ]
  # perf evlist -v
  /tmp/foo.o: type: 1, size: 112, config: 0x9, { sample_period,
  sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD, disabled: 1,
  inherit: 1, mmap: 1, comm: 1, freq: 1, task: 1, sample_id_all: 1,
  exclude_guest: 1, mmap2: 1, comm_exec: 1
  #

Signed-off-by: Wang Nan <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Brendan Gregg <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: David Ahern <[email protected]>
Cc: He Kuang <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kaixu Xia <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Zefan Li <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

1 files changed, 11 insertions, 0 deletions

diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index b819622dc7ce..b091ceb19c48 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -23,6 +23,9 @@ int bpf__unprobe(struct bpf_object *obj);
 int bpf__strerror_probe(struct bpf_object *obj, int err,
 			char *buf, size_t size);
 
+int bpf__load(struct bpf_object *obj);
+int bpf__strerror_load(struct bpf_object *obj, int err,
+		       char *buf, size_t size);
 #else
 static inline struct bpf_object *
 bpf__prepare_load(const char *filename __maybe_unused)
@@ -35,6 +38,7 @@ static inline void bpf__clear(void) { }
 
 static inline int bpf__probe(struct bpf_object *obj __maybe_unused) { return 0;}
 static inline int bpf__unprobe(struct bpf_object *obj __maybe_unused) { return 0;}
+static inline int bpf__load(struct bpf_object *obj __maybe_unused) { return 0; }
 
 static inline int
 __bpf_strerror(char *buf, size_t size)
@@ -55,5 +59,12 @@ bpf__strerror_probe(struct bpf_object *obj __maybe_unused,
 {
 	return __bpf_strerror(buf, size);
 }
+
+static inline int bpf__strerror_load(struct bpf_object *obj __maybe_unused,
+				     int err __maybe_unused,
+				     char *buf, size_t size)
+{
+	return __bpf_strerror(buf, size);
+}
 #endif
 #endif