tracing: fprobe-events: Log error for exceeding the number of entry args

Add error message when the number of entry argument exceeds the
maximum size of entry data.
This is currently checked when registering fprobe, but in this case
no error message is shown in the error_log file.

Link: https://lore.kernel.org/all/174055074269.4079315.17809232650360988538.stgit@mhiramat.tok.corp.google.com/

Fixes: 25f00e4 ("tracing/probes: Support $argN in return probe (kprobe and fprobe)")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: mhiramat

kernel/trace/trace_fprobe.c

@@ -1230,6 +1230,11 @@ static int trace_fprobe_create_internal(int argc, const char *argv[],
 	if (is_return && tf->tp.entry_arg) {
 		tf->fp.entry_handler = trace_fprobe_entry_handler;
 		tf->fp.entry_data_size = traceprobe_get_entry_data_size(&tf->tp);
+		if (ALIGN(tf->fp.entry_data_size, sizeof(long)) > MAX_FPROBE_DATA_SIZE) {
+			trace_probe_log_set_index(2);
+			trace_probe_log_err(0, TOO_MANY_EARGS);
+			return -E2BIG;
+		}
 	}
 
 	ret = traceprobe_set_print_fmt(&tf->tp,

kernel/trace/trace_probe.h

@@ -545,7 +545,8 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
 	C(NO_BTF_FIELD,		"This field is not found."),	\
 	C(BAD_BTF_TID,		"Failed to get BTF type info."),\
 	C(BAD_TYPE4STR,		"This type does not fit for string."),\
-	C(NEED_STRING_TYPE,	"$comm and immediate-string only accepts string type"),
+	C(NEED_STRING_TYPE,	"$comm and immediate-string only accepts string type"),\
+	C(TOO_MANY_EARGS,	"Too many entry arguments specified"),
 
 #undef C
 #define C(a, b)		TP_ERR_##a