FreeBSD/Linux Kernel Cross Reference
sys/x86/include/pvclock.h

     /*-
      * Copyright (c) 2014, Bryan Venteicher <bryanv@FreeBSD.org>
      * 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.
     *
     * $FreeBSD$
     */
    
    #ifndef X86_PVCLOCK
    #define X86_PVCLOCK
    
    #include <sys/types.h>
    
    #ifdef _KERNEL
    #include <sys/timetc.h>
    #endif /* _KERNEL */
    
    #define PVCLOCK_CDEVNAME                "pvclock"
    
    struct pvclock_vcpu_time_info {
            uint32_t        version;
            uint32_t        pad0;
            uint64_t        tsc_timestamp;
            uint64_t        system_time;
            uint32_t        tsc_to_system_mul;
            int8_t          tsc_shift;
            uint8_t         flags;
            uint8_t         pad[2];
    };
    
    #define PVCLOCK_FLAG_TSC_STABLE         0x01
    #define PVCLOCK_FLAG_GUEST_PASUED       0x02
    
    /*
     * 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)
                            : "" (delta), [mul_frac]"rm"((uint64_t)mul_frac));
            }
    #else
   #error "pvclock: unsupported x86 architecture?"
   #endif
           return (product);
   }
   
   #ifdef _KERNEL
   
   typedef struct pvclock_wall_clock *pvclock_get_wallclock_t(void *arg);
   
   struct pvclock_wall_clock {
           uint32_t        version;
           uint32_t        sec;
           uint32_t        nsec;
   };
   
   struct pvclock {
           /* Public; initialized by the caller of 'pvclock_init()': */
           pvclock_get_wallclock_t         *get_wallclock;
           void                            *get_wallclock_arg;
           struct pvclock_vcpu_time_info   *timeinfos;
           bool                             stable_flag_supported;
   
           /* Private; initialized by the 'pvclock' API: */
           bool                             vdso_force_unstable;
           struct timecounter               tc;
           struct cdev                     *cdev;
   };
   
   /*
    * NOTE: 'pvclock_get_timecount()' and 'pvclock_get_wallclock()' are purely
    * transitional; they should be removed after 'dev/xen/timer/timer.c' has been
    * migrated to the 'struct pvclock' API.
    */
   void            pvclock_resume(void);
   uint64_t        pvclock_tsc_freq(struct pvclock_vcpu_time_info *ti);
   uint64_t        pvclock_get_timecount(struct pvclock_vcpu_time_info *ti);
   void            pvclock_get_wallclock(struct pvclock_wall_clock *wc,
                       struct timespec *ts);
   
   void            pvclock_init(struct pvclock *pvc, device_t dev,
                       const char *tc_name, int tc_quality, u_int tc_flags);
   void            pvclock_gettime(struct pvclock *pvc, struct timespec *ts);
   int             pvclock_destroy(struct pvclock *pvc);
   
   #endif /* _KERNEL */
   
   #endif

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