| From e9deb7c6c912d5c58532bc4a57d4223963eab9ec Mon Sep 17 00:00:00 2001 |
| From: Zachary Amsden <zamsden@redhat.com> |
| Date: Thu, 19 Aug 2010 22:07:29 -1000 |
| Subject: [PATCH] x86: pvclock: Move scale_delta into common header |
| |
| commit 347bb4448c2155eb2310923ccaa4be5677649003 upstream. |
| |
| The scale_delta function for shift / multiply with 31-bit |
| precision moves to a common header so it can be used by both |
| kernel and kvm module. |
| |
| Signed-off-by: Zachary Amsden <zamsden@redhat.com> |
| Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h |
| index daaacab..982aa32 100644 |
| --- a/arch/x86/include/asm/pvclock.h |
| +++ b/arch/x86/include/asm/pvclock.h |
| @@ -12,4 +12,42 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall, |
| struct timespec *ts); |
| void pvclock_resume(void); |
| |
| +/* |
| + * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction, |
| + * yielding a 64-bit result. |
| + */ |
| +static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift) |
| +{ |
| + u64 product; |
| +#ifdef __i386__ |
| + u32 tmp1, tmp2; |
| +#endif |
| + |
| + if (shift < 0) |
| + delta >>= -shift; |
| + else |
| + delta <<= shift; |
| + |
| +#ifdef __i386__ |
| + __asm__ ( |
| + "mul %5 ; " |
| + "mov %4,%%eax ; " |
| + "mov %%edx,%4 ; " |
| + "mul %5 ; " |
| + "xor %5,%5 ; " |
| + "add %4,%%eax ; " |
| + "adc %5,%%edx ; " |
| + : "=A" (product), "=r" (tmp1), "=r" (tmp2) |
| + : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) ); |
| +#elif defined(__x86_64__) |
| + __asm__ ( |
| + "mul %%rdx ; shrd $32,%%rdx,%%rax" |
| + : "=a" (product) : "0" (delta), "d" ((u64)mul_frac) ); |
| +#else |
| +#error implement me! |
| +#endif |
| + |
| + return product; |
| +} |
| + |
| #endif /* _ASM_X86_PVCLOCK_H */ |
| diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c |
| index b12fe8d..929047c 100644 |
| --- a/arch/x86/kernel/pvclock.c |
| +++ b/arch/x86/kernel/pvclock.c |
| @@ -74,7 +74,8 @@ static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift) |
| static u64 pvclock_get_nsec_offset(struct pvclock_shadow_time *shadow) |
| { |
| u64 delta = native_read_tsc() - shadow->tsc_timestamp; |
| - return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift); |
| + return pvclock_scale_delta(delta, shadow->tsc_to_nsec_mul, |
| + shadow->tsc_shift); |
| } |
| |
| /* |
| -- |
| 1.7.7 |
| |