LXR linux/arch/x86/entry/vsyscall/vsyscall

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
   4 *  Copyright 2003 Andi Kleen, SuSE Labs.
   5 *
   6 *  Modified for x86 32 bit architecture by
   7 *  Stefani Seibold <stefani@seibold.net>
   8 *  sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany
   9 *
  10 *  Thanks to hpa@transmeta.com for some useful hint.
  11 *  Special thanks to Ingo Molnar for his early experience with
  12 *  a different vsyscall implementation for Linux/IA32 and for the name.
  13 *
  14 */
  15
  16#include <linux/timekeeper_internal.h>
  17#include <asm/vgtod.h>
  18#include <asm/vvar.h>
  19
  20int vclocks_used __read_mostly;
  21
  22DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data);
  23
  24void update_vsyscall_tz(void)
  25{
  26        vsyscall_gtod_data.tz_minuteswest = sys_tz.tz_minuteswest;
  27        vsyscall_gtod_data.tz_dsttime = sys_tz.tz_dsttime;
  28}
  29
  30void update_vsyscall(struct timekeeper *tk)
  31{
  32        int vclock_mode = tk->tkr_mono.clock->archdata.vclock_mode;
  33        struct vsyscall_gtod_data *vdata = &vsyscall_gtod_data;
  34
  35        /* Mark the new vclock used. */
  36        BUILD_BUG_ON(VCLOCK_MAX >= 32);
  37        WRITE_ONCE(vclocks_used, READ_ONCE(vclocks_used) | (1 << vclock_mode));
  38
  39        gtod_write_begin(vdata);
  40
  41        /* copy vsyscall data */
  42        vdata->vclock_mode      = vclock_mode;
  43        vdata->cycle_last       = tk->tkr_mono.cycle_last;
  44        vdata->mask             = tk->tkr_mono.mask;
  45        vdata->mult             = tk->tkr_mono.mult;
  46        vdata->shift            = tk->tkr_mono.shift;
  47
  48        vdata->wall_time_sec            = tk->xtime_sec;
  49        vdata->wall_time_snsec          = tk->tkr_mono.xtime_nsec;
  50
  51        vdata->monotonic_time_sec       = tk->xtime_sec
  52                                        + tk->wall_to_monotonic.tv_sec;
  53        vdata->monotonic_time_snsec     = tk->tkr_mono.xtime_nsec
  54                                        + ((u64)tk->wall_to_monotonic.tv_nsec
  55                                                << tk->tkr_mono.shift);
  56        while (vdata->monotonic_time_snsec >=
  57                                        (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
  58                vdata->monotonic_time_snsec -=
  59                                        ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
  60                vdata->monotonic_time_sec++;
  61        }
  62
  63        vdata->wall_time_coarse_sec     = tk->xtime_sec;
  64        vdata->wall_time_coarse_nsec    = (long)(tk->tkr_mono.xtime_nsec >>
  65                                                 tk->tkr_mono.shift);
  66
  67        vdata->monotonic_time_coarse_sec =
  68                vdata->wall_time_coarse_sec + tk->wall_to_monotonic.tv_sec;
  69        vdata->monotonic_time_coarse_nsec =
  70                vdata->wall_time_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
  71
  72        while (vdata->monotonic_time_coarse_nsec >= NSEC_PER_SEC) {
  73                vdata->monotonic_time_coarse_nsec -= NSEC_PER_SEC;
  74                vdata->monotonic_time_coarse_sec++;
  75        }
  76
  77        gtod_write_end(vdata);
  78}
  79