tracing/user_events: Use print_format_fields() for trace output

Currently, user events are shown using the "hex" output for "safety"
reasons as one cannot trust user events behaving nicely. But the hex
output is not the only utility for safe outputting of trace events. The
print_event_fields() is just as safe and gives user readable output.

Before:
         example-839     [001] .....    43.222244:
00000000: b1 06 00 00 47 03 00 00 00 00 00 00              ....G.......
         example-839     [001] .....    43.564433:
00000000: b1 06 00 00 47 03 00 00 01 00 00 00              ....G.......
         example-839     [001] .....    43.763917:
00000000: b1 06 00 00 47 03 00 00 02 00 00 00              ....G.......
         example-839     [001] .....    43.967929:
00000000: b1 06 00 00 47 03 00 00 03 00 00 00              ....G.......

After:

         example-837     [006] .....    55.739249: test: count=0x0 (0)
         example-837     [006] .....   111.104784: test: count=0x1 (1)
         example-837     [006] .....   111.268444: test: count=0x2 (2)
         example-837     [006] .....   111.416533: test: count=0x3 (3)
         example-837     [006] .....   111.542859: test: count=0x4 (4)

Link: https://lore.kernel.org/linux-trace-kernel/[email protected]

Cc: Masami Hiramatsu <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Beau Belgrave <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

kernel/trace/trace_events_user.c

@@ -22,8 +22,9 @@
 #include <linux/highmem.h>
 #include <linux/init.h>
 #include <linux/user_events.h>
-#include "trace.h"
 #include "trace_dynevent.h"
+#include "trace_output.h"
+#include "trace.h"
 
 #define USER_EVENTS_PREFIX_LEN (sizeof(USER_EVENTS_PREFIX)-1)
 
@@ -1198,11 +1199,7 @@ static enum print_line_t user_event_print_trace(struct trace_iterator *iter,
 						int flags,
 						struct trace_event *event)
 {
-	/* Unsafe to try to decode user provided print_fmt, use hex */
-	trace_print_hex_dump_seq(&iter->seq, "", DUMP_PREFIX_OFFSET, 16,
-				 1, iter->ent, iter->ent_size, true);
-
-	return trace_handle_return(&iter->seq);
+	return print_event_fields(iter, event);
 }
 
 static struct trace_event_functions user_event_funcs = {