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| author | Peter Zijlstra <peterz@infradead.org> | 2019-08-28 17:39:46 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-09-03 08:56:14 +0200 |
| commit | db4e919d9a119b7c54eb5e5ac9bee5d3eb4cb859 (patch) | |
| tree | ebeb54ead3a2f87b0efc5e63d5715fa5ed9a1fb9 | |
| parent | Linux 5.3-rc7 (diff) | |
| download | linux-db4e919d9a119b7c54eb5e5ac9bee5d3eb4cb859.tar.xz linux-db4e919d9a119b7c54eb5e5ac9bee5d3eb4cb859.zip | |
x86/math64: Provide a sane mul_u64_u32_div() implementation for x86_64
On x86_64 we can do a u64 * u64 -> u128 widening multiply followed by
a u128 / u64 -> u64 division to implement a sane version of
mul_u64_u32_div().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/include/asm/div64.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h index 20a46150e0a8..9b8cb50768c2 100644 --- a/arch/x86/include/asm/div64.h +++ b/arch/x86/include/asm/div64.h @@ -73,6 +73,19 @@ static inline u64 mul_u32_u32(u32 a, u32 b) #else # include <asm-generic/div64.h> + +static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div) +{ + u64 q; + + asm ("mulq %2; divq %3" : "=a" (q) + : "a" (a), "rm" ((u64)mul), "rm" ((u64)div) + : "rdx"); + + return q; +} +#define mul_u64_u32_div mul_u64_u32_div + #endif /* CONFIG_X86_32 */ #endif /* _ASM_X86_DIV64_H */ |