perf trace: Beautify sched_setscheduler 'policy' argument

  $ trace -e sched_setscheduler chrt -f 1 usleep 1
  chrt: failed to set pid 0's policy: Operation not permitted
     0.005 ( 0.005 ms): chrt/19189 sched_setscheduler(policy: FIFO, param: 0x7ffec5273d70) = -1 EPERM Operation not permitted
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-i5vlo5n5jv0amt8bkyicmdxh@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-trace.c

@@ -1073,6 +1073,8 @@ static size_t syscall_arg__scnprintf_getrandom_flags(char *bf, size_t size,
 	  .arg_scnprintf = { [arg] = SCA_STRARRAY, }, \
 	  .arg_parm	 = { [arg] = &strarray__##array, }
 
+#include "trace/beauty/sched_policy.c"
+
 static struct syscall_fmt {
 	const char *name;
 	const char *alias;
@@ -1304,6 +1306,8 @@ static struct syscall_fmt {
 	  .arg_scnprintf = { [1] = SCA_SIGNUM, /* sig */ }, },
 	{ .name	    = "rt_tgsigqueueinfo", .errmsg = true,
 	  .arg_scnprintf = { [2] = SCA_SIGNUM, /* sig */ }, },
+	{ .name	    = "sched_setscheduler",   .errmsg = true,
+	  .arg_scnprintf = { [1] = SCA_SCHED_POLICY, /* policy */ }, },
 	{ .name	    = "seccomp", .errmsg = true,
 	  .arg_scnprintf = { [0] = SCA_SECCOMP_OP, /* op */
 			     [1] = SCA_SECCOMP_FLAGS, /* flags */ }, },

tools/perf/trace/beauty/sched_policy.c

@@ -0,0 +1,44 @@
+#include <sched.h>
+
+/*
+ * Not defined anywhere else, probably, just to make sure we
+ * catch future flags
+ */
+#define SCHED_POLICY_MASK 0xff
+
+#ifndef SCHED_DEADLINE
+#define SCHED_DEADLINE 6
+#endif
+
+static size_t syscall_arg__scnprintf_sched_policy(char *bf, size_t size,
+						  struct syscall_arg *arg)
+{
+	const char *policies[] = {
+		"NORMAL", "FIFO", "RR", "BATCH", "ISO", "IDLE", "DEADLINE",
+	};
+	size_t printed;
+	int policy = arg->val,
+	    flags = policy & ~SCHED_POLICY_MASK;
+
+	policy &= SCHED_POLICY_MASK;
+	if (policy <= SCHED_DEADLINE)
+		printed = scnprintf(bf, size, "%s", policies[policy]);
+	else
+		printed = scnprintf(bf, size, "%#x", policy);
+
+#define	P_POLICY_FLAG(n) \
+	if (flags & SCHED_##n) { \
+		printed += scnprintf(bf + printed, size - printed, "|%s", #n); \
+		flags &= ~SCHED_##n; \
+	}
+
+	P_POLICY_FLAG(RESET_ON_FORK);
+#undef P_POLICY_FLAG
+
+	if (flags)
+		printed += scnprintf(bf + printed, size - printed, "|%#x", flags);
+
+	return printed;
+}
+
+#define SCA_SCHED_POLICY syscall_arg__scnprintf_sched_policy