perf top: Improve interactive key handling

Pressing any key which is not currently mapped to
functionality, based on startup command line options, displays
currently mapped keys, and prompts for input.

Pressing any unmapped key at the prompt returns the user to
display mode with variables unchanged. eg, pressing ? <SPACE>
<ESC> etc displays currently available keys, the value of the
variable associated with that key, and prompts.

Pressing same again aborts input.

Signed-off-by: Mike Galbraith <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Signed-off-by: Ingo Molnar <[e-mail]>

tools/perf/builtin-top.c

···
 	free(buf);
 }
 
-static void print_known_keys(void)
+static void print_mapped_keys(void)
 {
-	fprintf(stdout, "\nknown keys:\n");
-	fprintf(stdout, "\t[d]     select display delay.\n");
-	fprintf(stdout, "\t[e]     select display entries (lines).\n");
-	fprintf(stdout, "\t[E]     active event counter.              \t(%s)\n", event_name(sym_counter));
-	fprintf(stdout, "\t[f]     select normal display count filter.\n");
-	fprintf(stdout, "\t[F]     select annotation display count filter (percentage).\n");
-	fprintf(stdout, "\t[qQ]    quit.\n");
-	fprintf(stdout, "\t[s]     select annotation symbol and start annotation.\n");
-	fprintf(stdout, "\t[S]     stop annotation, revert to normal display.\n");
-	fprintf(stdout, "\t[w]     toggle display weighted/count[E]r. \t(%d)\n", display_weighted ? 1 : 0);
+	char *name = NULL;
+
+	if (sym_filter_entry) {
+		struct symbol *sym = (struct symbol *)(sym_filter_entry+1);
+		name = sym->name;
+	}
+
+	fprintf(stdout, "\nMapped keys:\n");
+	fprintf(stdout, "\t[d]     display refresh delay.             \t(%d)\n", delay_secs);
+	fprintf(stdout, "\t[e]     display entries (lines).           \t(%d)\n", print_entries);
+
+	if (nr_counters > 1)
+		fprintf(stdout, "\t[E]     active event counter.              \t(%s)\n", event_name(sym_counter));
+
+	fprintf(stdout, "\t[f]     profile display filter (count).    \t(%d)\n", count_filter);
+
+	if (vmlinux) {
+		fprintf(stdout, "\t[F]     annotate display filter (percent). \t(%d%%)\n", sym_pcnt_filter);
+		fprintf(stdout, "\t[s]     annotate symbol.                   \t(%s)\n", name?: "NULL");
+		fprintf(stdout, "\t[S]     stop annotation.\n");
+	}
+
+	if (nr_counters > 1)
+		fprintf(stdout, "\t[w]     toggle display weighted/count[E]r. \t(%d)\n", display_weighted ? 1 : 0);
+
 	fprintf(stdout, "\t[z]     toggle sample zeroing.             \t(%d)\n", zero ? 1 : 0);
+	fprintf(stdout, "\t[qQ]    quit.\n");
+}
+
+static int key_mapped(int c)
+{
+	switch (c) {
+		case 'd':
+		case 'e':
+		case 'f':
+		case 'z':
+		case 'q':
+		case 'Q':
+			return 1;
+		case 'E':
+		case 'w':
+			return nr_counters > 1 ? 1 : 0;
+		case 'F':
+		case 's':
+		case 'S':
+			return vmlinux ? 1 : 0;
+	}
+
+	return 0;
 }
 
 static void handle_keypress(int c)
 {
-	int once = 0;
-repeat:
+	if (!key_mapped(c)) {
+		struct pollfd stdin_poll = { .fd = 0, .events = POLLIN };
+		struct termios tc, save;
+
+		print_mapped_keys();
+		fprintf(stdout, "\nEnter selection, or unmapped key to continue: ");
+		fflush(stdout);
+
+		tcgetattr(0, &save);
+		tc = save;
+		tc.c_lflag &= ~(ICANON | ECHO);
+		tc.c_cc[VMIN] = 0;
+		tc.c_cc[VTIME] = 0;
+		tcsetattr(0, TCSANOW, &tc);
+
+		poll(&stdin_poll, 1, -1);
+		c = getc(stdin);
+
+		tcsetattr(0, TCSAFLUSH, &save);
+		if (!key_mapped(c))
+			return;
+	}
+
 	switch (c) {
 		case 'd':
 			prompt_integer(&delay_secs, "Enter display delay");
···
 		case 'z':
 			zero = ~zero;
 			break;
-		default: {
-			struct pollfd stdin_poll = { .fd = 0, .events = POLLIN };
-			struct termios tc, save;
-
-			if (!once) {
-				print_known_keys();
-				once++;
-			}
-
-			tcgetattr(0, &save);
-			tc = save;
-			tc.c_lflag &= ~(ICANON | ECHO);
-			tc.c_cc[VMIN] = 0;
-			tc.c_cc[VTIME] = 0;
-			tcsetattr(0, TCSANOW, &tc);
-
-			poll(&stdin_poll, 1, -1);
-			c = getc(stdin);
-
-			tcsetattr(0, TCSAFLUSH, &save);
-			goto repeat;
-		}
 	}
 }
 
···
 	tc.c_lflag &= ~(ICANON | ECHO);
 	tc.c_cc[VMIN] = 0;
 	tc.c_cc[VTIME] = 0;
+
 repeat:
 	delay_msecs = delay_secs * 1000;
 	tcsetattr(0, TCSANOW, &tc);