diff options
| author | Zachary Amsden <zamsden@redhat.com> | 2010-08-19 22:07:29 -1000 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-10-24 10:51:24 +0200 |
| commit | 347bb4448c2155eb2310923ccaa4be5677649003 (patch) | |
| tree | 93f5592975413c00c6c647001d715324e27cf985 /arch/x86/include/asm/pvclock.h | |
| parent | ca84d1a24c376e0841f35db08dab7b829c8c0b1e (diff) | |
x86: pvclock: Move scale_delta into common header
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>
Diffstat (limited to 'arch/x86/include/asm/pvclock.h')
| -rw-r--r-- | arch/x86/include/asm/pvclock.h | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index cd02f324aa6b..7f7e577a0e39 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 pvclock_vcpu_time_info *vcpu, struct timespec *ts); +/* + * 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 */ |