perf probe: Support argument name

Set given names to event arguments. The syntax is same as kprobe-tracer,
you can add 'NAME=' right before each argument.

e.g.
  ./perf probe vfs_read foo=file

 then, 'foo' is set to the argument name as below.

  ./perf probe -l
  probe:vfs_read       (on vfs_read@linux-2.6-tip/fs/read_write.c with foo)

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100412171653.3790.74624.stgit@localhost6.localdomain6>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index bfc47ff..daf4668 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -142,9 +142,9 @@
 	OPT_CALLBACK('a', "add", NULL,
 #ifdef DWARF_SUPPORT
 		"[EVENT=]FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT"
-		" [ARG ...]",
+		" [[NAME=]ARG ...]",
 #else
-		"[EVENT=]FUNC[+OFF|%return] [ARG ...]",
+		"[EVENT=]FUNC[+OFF|%return] [[NAME=]ARG ...]",
 #endif
 		"probe point definition, where\n"
 		"\t\tGROUP:\tGroup name (optional)\n"