[PATCH v2 07/13] math64: Always inline u128 version of mul_u64_u64_shr()

From: Peter Zijlstra
Date: Fri May 19 2023 - 06:34:29 EST


In order to prevent the following complaint from happening, always
inline the u128 variant of mul_u64_u64_shr() -- which is what x86_64
will use.

vmlinux.o: warning: objtool: read_hv_sched_clock_tsc+0x5a: call to mul_u64_u64_shr.constprop.0() leaves .noinstr.text section

It should compile into something like:

asm("mul %[mul];"
"shrd %rdx, %rax, %cl"
: "+&a" (a)
: "c" shift, [mul] "r" (mul)
: "d");

Which is silly not to inline, but it happens.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
include/linux/math64.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -168,7 +168,7 @@ static __always_inline u64 mul_u64_u32_s
#endif /* mul_u64_u32_shr */

#ifndef mul_u64_u64_shr
-static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
+static __always_inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
{
return (u64)(((unsigned __int128)a * mul) >> shift);
}