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kernel/linux-rt-4.4.41/arch/x86/include/asm/pvclock.h 2.49 KB
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  #ifndef _ASM_X86_PVCLOCK_H
  #define _ASM_X86_PVCLOCK_H
  
  #include <linux/clocksource.h>
  #include <asm/pvclock-abi.h>
  
  /* some helper functions for xen and kvm pv clock sources */
  cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
  u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
  void pvclock_set_flags(u8 flags);
  unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
  void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
  			    struct pvclock_vcpu_time_info *vcpu,
  			    struct timespec *ts);
  void pvclock_resume(void);
  
  void pvclock_touch_watchdogs(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;
  #else
  	ulong tmp;
  #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__ (
  		"mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
  		: [lo]"=a"(product),
  		  [hi]"=d"(tmp)
  		: "0"(delta),
  		  [mul_frac]"rm"((u64)mul_frac));
  #else
  #error implement me!
  #endif
  
  	return product;
  }
  
  static __always_inline
  u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
  {
  	u64 delta = rdtsc_ordered() - src->tsc_timestamp;
  	return pvclock_scale_delta(delta, src->tsc_to_system_mul,
  				   src->tsc_shift);
  }
  
  static __always_inline
  unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
  			       cycle_t *cycles, u8 *flags)
  {
  	unsigned version;
  	cycle_t ret, offset;
  	u8 ret_flags;
  
  	version = src->version;
  	/* Make the latest version visible */
  	smp_rmb();
  
  	offset = pvclock_get_nsec_offset(src);
  	ret = src->system_time + offset;
  	ret_flags = src->flags;
  
  	*cycles = ret;
  	*flags = ret_flags;
  	return version;
  }
  
  struct pvclock_vsyscall_time_info {
  	struct pvclock_vcpu_time_info pvti;
  } __attribute__((__aligned__(SMP_CACHE_BYTES)));
  
  #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
  #define PVCLOCK_VSYSCALL_NR_PAGES (((NR_CPUS-1)/(PAGE_SIZE/PVTI_SIZE))+1)
  
  int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i,
  				 int size);
  struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu);
  
  #endif /* _ASM_X86_PVCLOCK_H */