perf trace: Beautify eventfd2 'flags' arg

 61.168 ( 0.004 ms): 24267 eventfd2(flags: CLOEXEC|NONBLOCK) = 9

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-3hg8eajdzil077501c8f5jkw@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -13,6 +13,7 @@
 
 #include <libaudit.h>
 #include <stdlib.h>
+#include <sys/eventfd.h>
 #include <sys/mman.h>
 #include <linux/futex.h>
 
@@ -456,6 +457,32 @@ static size_t syscall_arg__scnprintf_open_flags(char *bf, size_t size,
 
 #define SCA_OPEN_FLAGS syscall_arg__scnprintf_open_flags
 
+static size_t syscall_arg__scnprintf_eventfd_flags(char *bf, size_t size,
+						   struct syscall_arg *arg)
+{
+	int printed = 0, flags = arg->val;
+
+	if (flags == 0)
+		return scnprintf(bf, size, "NONE");
+#define	P_FLAG(n) \
+	if (flags & EFD_##n) { \
+		printed += scnprintf(bf + printed, size - printed, "%s%s", printed ? "|" : "", #n); \
+		flags &= ~EFD_##n; \
+	}
+
+	P_FLAG(SEMAPHORE);
+	P_FLAG(CLOEXEC);
+	P_FLAG(NONBLOCK);
+#undef P_FLAG
+
+	if (flags)
+		printed += scnprintf(bf + printed, size - printed, "%s%#x", printed ? "|" : "", flags);
+
+	return printed;
+}
+
+#define SCA_EFD_FLAGS syscall_arg__scnprintf_eventfd_flags
+
 static size_t syscall_arg__scnprintf_signum(char *bf, size_t size, struct syscall_arg *arg)
 {
 	int sig = arg->val;
@@ -516,6 +543,8 @@ static struct syscall_fmt {
 	{ .name	    = "brk",	    .hexret = true,
 	  .arg_scnprintf = { [0] = SCA_HEX, /* brk */ }, },
 	{ .name	    = "connect",    .errmsg = true, },
+	{ .name	    = "eventfd2",   .errmsg = true,
+	  .arg_scnprintf = { [1] = SCA_EFD_FLAGS, /* flags */ }, },
 	{ .name	    = "fcntl",	    .errmsg = true,
 	  .arg_scnprintf = { [1] = SCA_STRARRAY, /* cmd */ },
 	  .arg_parm	 = { [1] = &strarray__fcntl_cmds, /* cmd */ }, },