From f65d38155aef069c897a64643a03db237dd1e0c8 Mon Sep 17 00:00:00 2001 From: David Laight Date: Mon, 3 Aug 2026 10:47:01 +0100 Subject: [PATCH] x86/div64: Fix addition of large constants in mul_u64_add_u64_div_u64() Adding constants over 2^31 fails to compile because the ADD instruction only supports 32bit signed immediates. Replace the "irm" constraint with "erm" so that the compiler loads large constants into a register. Found by a patch to drivers/iio/frequency/ad9910.c [ bp: Massage commit message. ] Fixes: 6480241f31f5 ("lib: add mul_u64_add_u64_div_u64() and mul_u64_u64_div_u64_roundup()") Signed-off-by: David Laight Signed-off-by: Borislav Petkov (AMD) Reviewed-by: H. Peter Anvin Link: https://patch.msgid.link/20260803094702.3852-2-david.laight.linux@gmail.com --- arch/x86/include/asm/div64.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h index 30fd06ede751..8a2d343f977e 100644 --- a/arch/x86/include/asm/div64.h +++ b/arch/x86/include/asm/div64.h @@ -111,7 +111,7 @@ static inline u64 mul_u64_add_u64_div_u64(u64 rax, u64 mul, u64 add, u64 div) if (!statically_true(!add)) asm ("addq %[add], %[lo]; adcq $0, %[hi]" : - [lo] "+r" (rax), [hi] "+r" (rdx) : [add] "irm" (add)); + [lo] "+r" (rax), [hi] "+r" (rdx) : [add] "erm" (add)); asm ("divq %[div]" : "+a" (rax), "+d" (rdx) : [div] "rm" (div));