perf ftrace: Add 'trace' subcommand

This is a preparation to add more sub-commands for ftrace.  The
'trace' subcommand does the same thing when no subcommand is given.

Committer testing:

The previous mode, i.e. no subcommand and the new 'perf ftrace trace'
are equivalent:

  # perf ftrace -G check_preempt_curr sleep 0.00001
  # tracer: function_graph
  #
  # CPU  DURATION                  FUNCTION CALLS
  # |     |   |                     |   |   |   |
   25)               |  check_preempt_curr() {
   25)               |    resched_curr() {
   25)               |      native_smp_send_reschedule() {
   25)               |        default_send_IPI_single_phys() {
   25)   0.110 us    |          __default_send_IPI_dest_field();
   25)   0.490 us    |        }
   25)   0.640 us    |      }
   25)   0.850 us    |    }
   25)   2.060 us    |  }
  # perf ftrace trace -G check_preempt_curr sleep 0.00001
  # tracer: function_graph
  #
  # CPU  DURATION                  FUNCTION CALLS
  # |     |   |                     |   |   |   |
   10)               |  check_preempt_curr() {
   10)               |    resched_curr() {
   10)               |      native_smp_send_reschedule() {
   10)               |        default_send_IPI_single_phys() {
   10)   0.080 us    |          __default_send_IPI_dest_field();
   10)   0.460 us    |        }
   10)   0.610 us    |      }
   10)   0.830 us    |    }
   10)   2.020 us    |  }
  #

Signed-off-by: Namhyung Kim <[email protected]>
Tested-by: Arnaldo Carvalho de Melo <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Athira Jajeev <[email protected]>
Cc: Changbin Du <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: namhyung

tools/perf/builtin-ftrace.c

@@ -879,17 +879,7 @@ int cmd_ftrace(int argc, const char **argv)
 		.tracer = DEFAULT_TRACER,
 		.target = { .uid = UINT_MAX, },
 	};
-	const char * const ftrace_usage[] = {
-		"perf ftrace [<options>] [<command>]",
-		"perf ftrace [<options>] -- <command> [<options>]",
-		NULL
-	};
-	const struct option ftrace_options[] = {
-	OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
-		   "Tracer to use: function_graph(default) or function"),
-	OPT_CALLBACK_DEFAULT('F', "funcs", NULL, "[FILTER]",
-			     "Show available functions to filter",
-			     opt_list_avail_functions, "*"),
+	const struct option common_options[] = {
 	OPT_STRING('p', "pid", &ftrace.target.pid, "pid",
 		   "Trace on existing process id"),
 	/* TODO: Add short option -t after -t/--tracer can be removed. */
@@ -901,6 +891,14 @@ int cmd_ftrace(int argc, const char **argv)
 		    "System-wide collection from all CPUs"),
 	OPT_STRING('C', "cpu", &ftrace.target.cpu_list, "cpu",
 		    "List of cpus to monitor"),
+	OPT_END()
+	};
+	const struct option ftrace_options[] = {
+	OPT_STRING('t', "tracer", &ftrace.tracer, "tracer",
+		   "Tracer to use: function_graph(default) or function"),
+	OPT_CALLBACK_DEFAULT('F', "funcs", NULL, "[FILTER]",
+			     "Show available functions to filter",
+			     opt_list_avail_functions, "*"),
 	OPT_CALLBACK('T', "trace-funcs", &ftrace.filters, "func",
 		     "Trace given functions using function tracer",
 		     parse_filter_func),
@@ -923,7 +921,15 @@ int cmd_ftrace(int argc, const char **argv)
 		    "Trace children processes"),
 	OPT_UINTEGER('D', "delay", &ftrace.initial_delay,
 		     "Number of milliseconds to wait before starting tracing after program start"),
-	OPT_END()
+	OPT_PARENT(common_options),
+	};
+
+	const char * const ftrace_usage[] = {
+		"perf ftrace [<options>] [<command>]",
+		"perf ftrace [<options>] -- [<command>] [<options>]",
+		"perf ftrace trace [<options>] [<command>]",
+		"perf ftrace trace [<options>] -- [<command>] [<options>]",
+		NULL
 	};
 
 	INIT_LIST_HEAD(&ftrace.filters);
@@ -935,6 +941,11 @@ int cmd_ftrace(int argc, const char **argv)
 	if (ret < 0)
 		return -1;
 
+	if (argc > 1 && !strcmp(argv[1], "trace")) {
+		argc--;
+		argv++;
+	}
+
 	argc = parse_options(argc, argv, ftrace_options, ftrace_usage,
 			    PARSE_OPT_STOP_AT_NON_OPTION);
 	if (!argc && target__none(&ftrace.target))