1// SPDX-License-Identifier: GPL-2.0
2#include <linux/export.h>
3
4#include "libgcc.h"
5
6/*
7 * GCC 7 & older can suboptimally generate __multi3 calls for mips64r6, so for
8 * that specific case only we implement that intrinsic here.
9 *
10 * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82981
11 */
12#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) && (__GNUC__ < 8)
13
14/* multiply 64-bit values, low 64-bits returned */
15static inline long long notrace dmulu(long long a, long long b)
16{
17	long long res;
18
19	asm ("dmulu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
20	return res;
21}
22
23/* multiply 64-bit unsigned values, high 64-bits of 128-bit result returned */
24static inline long long notrace dmuhu(long long a, long long b)
25{
26	long long res;
27
28	asm ("dmuhu %0,%1,%2" : "=r" (res) : "r" (a), "r" (b));
29	return res;
30}
31
32/* multiply 128-bit values, low 128-bits returned */
33ti_type notrace __multi3(ti_type a, ti_type b)
34{
35	TWunion res, aa, bb;
36
37	aa.ti = a;
38	bb.ti = b;
39
40	/*
41	 * a * b =           (a.lo * b.lo)
42	 *         + 2^64  * (a.hi * b.lo + a.lo * b.hi)
43	 *        [+ 2^128 * (a.hi * b.hi)]
44	 */
45	res.s.low = dmulu(aa.s.low, bb.s.low);
46	res.s.high = dmuhu(aa.s.low, bb.s.low);
47	res.s.high += dmulu(aa.s.high, bb.s.low);
48	res.s.high += dmulu(aa.s.low, bb.s.high);
49
50	return res.ti;
51}
52EXPORT_SYMBOL(__multi3);
53
54#endif /* 64BIT && CPU_MIPSR6 && GCC7 */
55