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| author | David Laight <david.laight.linux@gmail.com> | 2026-08-03 10:47:01 +0100 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2026-09-10 10:40:22 -0700 |
| commit | f65d38155aef069c897a64643a03db237dd1e0c8 (patch) | |
| tree | 4cc602cb247fcf1c32e5a97b25a7fa31954fd313 | |
| parent | 5a5d26f2cfe13467166219f6bf58099326912ddb (diff) | |
| download | linux-f65d38155aef069c897a64643a03db237dd1e0c8.tar.gz linux-f65d38155aef069c897a64643a03db237dd1e0c8.zip | |
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 <david.laight.linux@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: H. Peter Anvin <hpa@zytor.com>
Link: https://patch.msgid.link/20260803094702.3852-2-david.laight.linux@gmail.com
| -rw-r--r-- | arch/x86/include/asm/div64.h | 2 |
1 files changed, 1 insertions, 1 deletions
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)); |