root/arch/x86/include/asm/pvclock.h

INCLUDED FROM

DEFINITIONS

1. pvclock_scale_delta
2. pvclock_get_nsec_offset
3. __pvclock_read_cycles

#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 = __native_read_tsc() - 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;
        /* Note: emulated platforms which do not advertise SSE2 support
         * result in kvmclock not using the necessary RDTSC barriers.
         * Without barriers, it is possible that RDTSC instruction reads from
         * the time stamp counter outside rdtsc_barrier protected section
         * below, resulting in violation of monotonicity.
         */
        rdtsc_barrier();
        offset = pvclock_get_nsec_offset(src);
        ret = src->system_time + offset;
        ret_flags = src->flags;
        rdtsc_barrier();

        *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 */