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/*-
* Copyright (c) 2009 Adrian Chadd
* Copyright (c) 2012 Spectra Logic Corporation
* Copyright (c) 2014 Bryan Venteicher
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <machine/cpufunc.h>
#include <machine/cpu.h>
#include <machine/atomic.h>
#include <machine/pvclock.h>
/*
* Last time; this guarantees a monotonically increasing clock for when
* a stable TSC is not provided.
*/
static volatile uint64_t pvclock_last_cycles;
void
pvclock_resume(void)
{
atomic_store_rel_64(&pvclock_last_cycles, 0);
}
uint64_t
pvclock_get_last_cycles(void)
{
return (atomic_load_acq_64(&pvclock_last_cycles));
}
uint64_t
pvclock_tsc_freq(struct pvclock_vcpu_time_info *ti)
{
uint64_t freq;
freq = (1000000000ULL << 32) / ti->tsc_to_system_mul;
if (ti->tsc_shift < 0)
freq <<= -ti->tsc_shift;
else
freq >>= ti->tsc_shift;
return (freq);
}
/*
* Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
* yielding a 64-bit result.
*/
static inline uint64_t
pvclock_scale_delta(uint64_t delta, uint32_t mul_frac, int shift)
{
uint64_t product;
if (shift < 0)
delta >>= -shift;
else
delta <<= shift;
#if defined(__i386__)
{
uint32_t tmp1, tmp2;
/**
* For i386, the formula looks like:
*
* lower = (mul_frac * (delta & UINT_MAX)) >> 32
* upper = mul_frac * (delta >> 32)
* product = lower + upper
*/
__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" ((uint32_t)delta), "1" ((uint32_t)(delta >> 32)),
"2" (mul_frac) );
}
#elif defined(__amd64__)
{
unsigned long tmp;
__asm__ (
"mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
: [lo]"=a" (product), [hi]"=d" (tmp)
: "0" (delta), [mul_frac]"rm"((uint64_t)mul_frac));
}
#else
#error "pvclock: unsupported x86 architecture?"
#endif
return (product);
}
static uint64_t
pvclock_get_nsec_offset(struct pvclock_vcpu_time_info *ti)
{
uint64_t delta;
delta = rdtsc() - ti->tsc_timestamp;
return (pvclock_scale_delta(delta, ti->tsc_to_system_mul,
ti->tsc_shift));
}
static void
pvclock_read_time_info(struct pvclock_vcpu_time_info *ti,
uint64_t *cycles, uint8_t *flags)
{
uint32_t version;
do {
version = ti->version;
rmb();
*cycles = ti->system_time + pvclock_get_nsec_offset(ti);
*flags = ti->flags;
rmb();
} while ((ti->version & 1) != 0 || ti->version != version);
}
static void
pvclock_read_wall_clock(struct pvclock_wall_clock *wc, uint32_t *sec,
uint32_t *nsec)
{
uint32_t version;
do {
version = wc->version;
rmb();
*sec = wc->sec;
*nsec = wc->nsec;
rmb();
} while ((wc->version & 1) != 0 || wc->version != version);
}
uint64_t
pvclock_get_timecount(struct pvclock_vcpu_time_info *ti)
{
uint64_t now, last;
uint8_t flags;
pvclock_read_time_info(ti, &now, &flags);
if (flags & PVCLOCK_FLAG_TSC_STABLE)
return (now);
/*
* Enforce a monotonically increasing clock time across all VCPUs.
* If our time is too old, use the last time and return. Otherwise,
* try to update the last time.
*/
do {
last = atomic_load_acq_64(&pvclock_last_cycles);
if (last > now)
return (last);
} while (!atomic_cmpset_64(&pvclock_last_cycles, last, now));
return (now);
}
void
pvclock_get_wallclock(struct pvclock_wall_clock *wc, struct timespec *ts)
{
uint32_t sec, nsec;
pvclock_read_wall_clock(wc, &sec, &nsec);
ts->tv_sec = sec;
ts->tv_nsec = nsec;
}
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