v4.19.13 snapshot.
diff --git a/arch/mips/math-emu/dp_flong.c b/arch/mips/math-emu/dp_flong.c
new file mode 100644
index 0000000..a267c2e
--- /dev/null
+++ b/arch/mips/math-emu/dp_flong.c
@@ -0,0 +1,65 @@
+/* IEEE754 floating point arithmetic
+ * double precision: common utilities
+ */
+/*
+ * MIPS floating point support
+ * Copyright (C) 1994-2000 Algorithmics Ltd.
+ *
+ *  This program is free software; you can distribute it and/or modify it
+ *  under the terms of the GNU General Public License (Version 2) as
+ *  published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ *  for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
+ */
+
+#include "ieee754dp.h"
+
+union ieee754dp ieee754dp_flong(s64 x)
+{
+	u64 xm;
+	int xe;
+	int xs;
+
+	ieee754_clearcx();
+
+	if (x == 0)
+		return ieee754dp_zero(0);
+	if (x == 1 || x == -1)
+		return ieee754dp_one(x < 0);
+	if (x == 10 || x == -10)
+		return ieee754dp_ten(x < 0);
+
+	xs = (x < 0);
+	if (xs) {
+		if (x == (1ULL << 63))
+			xm = (1ULL << 63);	/* max neg can't be safely negated */
+		else
+			xm = -x;
+	} else {
+		xm = x;
+	}
+
+	/* normalize */
+	xe = DP_FBITS + 3;
+	if (xm >> (DP_FBITS + 1 + 3)) {
+		/* shunt out overflow bits */
+		while (xm >> (DP_FBITS + 1 + 3)) {
+			XDPSRSX1();
+		}
+	} else {
+		/* normalize in grs extended double precision */
+		while ((xm >> (DP_FBITS + 3)) == 0) {
+			xm <<= 1;
+			xe--;
+		}
+	}
+
+	return ieee754dp_format(xs, xe, xm);
+}