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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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347bb4448c
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>
54 lines
1.3 KiB
C
54 lines
1.3 KiB
C
#ifndef _ASM_X86_PVCLOCK_H
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#define _ASM_X86_PVCLOCK_H
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#include <linux/clocksource.h>
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#include <asm/pvclock-abi.h>
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/* some helper functions for xen and kvm pv clock sources */
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cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
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void pvclock_set_flags(u8 flags);
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unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
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void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
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struct pvclock_vcpu_time_info *vcpu,
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struct timespec *ts);
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/*
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* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
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* yielding a 64-bit result.
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*/
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static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
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{
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u64 product;
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#ifdef __i386__
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u32 tmp1, tmp2;
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#endif
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if (shift < 0)
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delta >>= -shift;
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else
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delta <<= shift;
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#ifdef __i386__
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__asm__ (
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"mul %5 ; "
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"mov %4,%%eax ; "
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"mov %%edx,%4 ; "
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"mul %5 ; "
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"xor %5,%5 ; "
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"add %4,%%eax ; "
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"adc %5,%%edx ; "
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: "=A" (product), "=r" (tmp1), "=r" (tmp2)
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: "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
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#elif defined(__x86_64__)
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__asm__ (
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"mul %%rdx ; shrd $32,%%rdx,%%rax"
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: "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
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#else
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#error implement me!
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#endif
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return product;
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}
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#endif /* _ASM_X86_PVCLOCK_H */
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