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 */
dmulu(long long a,long long b)15 static 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 */
dmuhu(long long a,long long b)24 static 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 */
__multi3(ti_type a,ti_type b)33 ti_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 }
52 EXPORT_SYMBOL(__multi3);
53
54 #endif /* 64BIT && CPU_MIPSR6 && GCC7 */
55