kernel/time/vsyscall.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2019 ARM Ltd.
   4  *
   5  * Generic implementation of update_vsyscall and update_vsyscall_tz.
   6  *
   7  * Based on the x86 specific implementation.
   8  */
   9
  10 #include <linux/hrtimer.h>
  11 #include <linux/timekeeper_internal.h>
  12 #include <vdso/datapage.h>
  13 #include <vdso/helpers.h>
  14 #include <vdso/vsyscall.h>
  15
  16 static inline void update_vdso_data(struct vdso_data *vdata,
  17                                     struct timekeeper *tk)
  18 {
  19         struct vdso_timestamp *vdso_ts;
  20         u64 nsec;
  21
  22         vdata[CS_HRES_COARSE].cycle_last        = tk->tkr_mono.cycle_last;
  23         vdata[CS_HRES_COARSE].mask              = tk->tkr_mono.mask;
  24         vdata[CS_HRES_COARSE].mult              = tk->tkr_mono.mult;
  25         vdata[CS_HRES_COARSE].shift             = tk->tkr_mono.shift;
  26         vdata[CS_RAW].cycle_last                = tk->tkr_raw.cycle_last;
  27         vdata[CS_RAW].mask                      = tk->tkr_raw.mask;
  28         vdata[CS_RAW].mult                      = tk->tkr_raw.mult;
  29         vdata[CS_RAW].shift                     = tk->tkr_raw.shift;
  30
  31         /* CLOCK_REALTIME */
  32         vdso_ts         = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];
  33         vdso_ts->sec    = tk->xtime_sec;
  34         vdso_ts->nsec   = tk->tkr_mono.xtime_nsec;
  35
  36         /* CLOCK_MONOTONIC */
  37         vdso_ts         = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC];
  38         vdso_ts->sec    = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
  39
  40         nsec = tk->tkr_mono.xtime_nsec;
  41         nsec += ((u64)tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
  42         while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
  43                 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
  44                 vdso_ts->sec++;
  45         }
  46         vdso_ts->nsec   = nsec;
  47
  48         /* CLOCK_MONOTONIC_RAW */
  49         vdso_ts         = &vdata[CS_RAW].basetime[CLOCK_MONOTONIC_RAW];
  50         vdso_ts->sec    = tk->raw_sec;
  51         vdso_ts->nsec   = tk->tkr_raw.xtime_nsec;
  52
  53         /* CLOCK_BOOTTIME */
  54         vdso_ts         = &vdata[CS_HRES_COARSE].basetime[CLOCK_BOOTTIME];
  55         vdso_ts->sec    = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
  56         nsec = tk->tkr_mono.xtime_nsec;
  57         nsec += ((u64)(tk->wall_to_monotonic.tv_nsec +
  58                        ktime_to_ns(tk->offs_boot)) << tk->tkr_mono.shift);
  59         while (nsec >= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
  60                 nsec -= (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift);
  61                 vdso_ts->sec++;
  62         }
  63         vdso_ts->nsec   = nsec;
  64
  65         /* CLOCK_TAI */
  66         vdso_ts         = &vdata[CS_HRES_COARSE].basetime[CLOCK_TAI];
  67         vdso_ts->sec    = tk->xtime_sec + (s64)tk->tai_offset;
  68         vdso_ts->nsec   = tk->tkr_mono.xtime_nsec;
  69
  70         /*
  71          * Read without the seqlock held by clock_getres().
  72          * Note: No need to have a second copy.
  73          */
  74         WRITE_ONCE(vdata[CS_HRES_COARSE].hrtimer_res, hrtimer_resolution);
  75 }
  76
  77 void update_vsyscall(struct timekeeper *tk)
  78 {
  79         struct vdso_data *vdata = __arch_get_k_vdso_data();
  80         struct vdso_timestamp *vdso_ts;
  81         u64 nsec;
  82
  83         if (__arch_update_vdso_data()) {
  84                 /*
  85                  * Some architectures might want to skip the update of the
  86                  * data page.
  87                  */
  88                 return;
  89         }
  90
  91         /* copy vsyscall data */
  92         vdso_write_begin(vdata);
  93
  94         vdata[CS_HRES_COARSE].clock_mode        = __arch_get_clock_mode(tk);
  95         vdata[CS_RAW].clock_mode                = __arch_get_clock_mode(tk);
  96
  97         /* CLOCK_REALTIME_COARSE */
  98         vdso_ts         = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME_COARSE];
  99         vdso_ts->sec    = tk->xtime_sec;
 100         vdso_ts->nsec   = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
 101
 102         /* CLOCK_MONOTONIC_COARSE */
 103         vdso_ts         = &vdata[CS_HRES_COARSE].basetime[CLOCK_MONOTONIC_COARSE];
 104         vdso_ts->sec    = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
 105         nsec            = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
 106         nsec            = nsec + tk->wall_to_monotonic.tv_nsec;
 107         vdso_ts->sec    += __iter_div_u64_rem(nsec, NSEC_PER_SEC, &vdso_ts->nsec);
 108
 109         if (__arch_use_vsyscall(vdata))
 110                 update_vdso_data(vdata, tk);
 111
 112         __arch_update_vsyscall(vdata, tk);
 113
 114         vdso_write_end(vdata);
 115
 116         __arch_sync_vdso_data(vdata);
 117 }
 118
 119 void update_vsyscall_tz(void)
 120 {
 121         struct vdso_data *vdata = __arch_get_k_vdso_data();
 122
 123         if (__arch_use_vsyscall(vdata)) {
 124                 vdata[CS_HRES_COARSE].tz_minuteswest = sys_tz.tz_minuteswest;
 125                 vdata[CS_HRES_COARSE].tz_dsttime = sys_tz.tz_dsttime;
 126         }
 127
 128         __arch_sync_vdso_data(vdata);
 129 }