arch/x86/include/asm/pvclock.h

   1 #ifndef _ASM_X86_PVCLOCK_H
   2 #define _ASM_X86_PVCLOCK_H
   3
   4 #include <linux/clocksource.h>
   5 #include <asm/pvclock-abi.h>
   6
   7 /* some helper functions for xen and kvm pv clock sources */
   8 cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
   9 u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
  10 void pvclock_set_flags(u8 flags);
  11 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
  12 void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
  13                             struct pvclock_vcpu_time_info *vcpu,
  14                             struct timespec *ts);
  15 void pvclock_resume(void);
  16
  17 void pvclock_touch_watchdogs(void);
  18
  19 /*
  20  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
  21  * yielding a 64-bit result.
  22  */
  23 static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
  24 {
  25         u64 product;
  26 #ifdef __i386__
  27         u32 tmp1, tmp2;
  28 #else
  29         ulong tmp;
  30 #endif
  31
  32         if (shift < 0)
  33                 delta >>= -shift;
  34         else
  35                 delta <<= shift;
  36
  37 #ifdef __i386__
  38         __asm__ (
  39                 "mul  %5       ; "
  40                 "mov  %4,%%eax ; "
  41                 "mov  %%edx,%4 ; "
  42                 "mul  %5       ; "
  43                 "xor  %5,%5    ; "
  44                 "add  %4,%%eax ; "
  45                 "adc  %5,%%edx ; "
  46                 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
  47                 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
  48 #elif defined(__x86_64__)
  49         __asm__ (
  50                 "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
  51                 : [lo]"=a"(product),
  52                   [hi]"=d"(tmp)
  53                 : "0"(delta),
  54                   [mul_frac]"rm"((u64)mul_frac));
  55 #else
  56 #error implement me!
  57 #endif
  58
  59         return product;
  60 }
  61
  62 static __always_inline
  63 u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
  64 {
  65         u64 delta = __native_read_tsc() - src->tsc_timestamp;
  66         return pvclock_scale_delta(delta, src->tsc_to_system_mul,
  67                                    src->tsc_shift);
  68 }
  69
  70 static __always_inline
  71 unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
  72                                cycle_t *cycles, u8 *flags)
  73 {
  74         unsigned version;
  75         cycle_t ret, offset;
  76         u8 ret_flags;
  77
  78         version = src->version;
  79         /* Note: emulated platforms which do not advertise SSE2 support
  80          * result in kvmclock not using the necessary RDTSC barriers.
  81          * Without barriers, it is possible that RDTSC instruction reads from
  82          * the time stamp counter outside rdtsc_barrier protected section
  83          * below, resulting in violation of monotonicity.
  84          */
  85         rdtsc_barrier();
  86         offset = pvclock_get_nsec_offset(src);
  87         ret = src->system_time + offset;
  88         ret_flags = src->flags;
  89
  90         *cycles = ret;
  91         *flags = ret_flags;
  92         return version;
  93 }
  94
  95 struct pvclock_vsyscall_time_info {
  96         struct pvclock_vcpu_time_info pvti;
  97 } __attribute__((__aligned__(SMP_CACHE_BYTES)));
  98
  99 #define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
 100 #define PVCLOCK_VSYSCALL_NR_PAGES (((NR_CPUS-1)/(PAGE_SIZE/PVTI_SIZE))+1)
 101
 102 int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i,
 103                                  int size);
 104 struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu);
 105
 106 #endif /* _ASM_X86_PVCLOCK_H */