timekeeper_internal.h 5.3 KB

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  1. /* SPDX-License-Identifier: GPL-2.0 */
  2. /*
  3. * You SHOULD NOT be including this unless you're vsyscall
  4. * handling code or timekeeping internal code!
  5. */
  6. #ifndef _LINUX_TIMEKEEPER_INTERNAL_H
  7. #define _LINUX_TIMEKEEPER_INTERNAL_H
  8. #include <linux/clocksource.h>
  9. #include <linux/jiffies.h>
  10. #include <linux/time.h>
  11. /**
  12. * struct tk_read_base - base structure for timekeeping readout
  13. * @clock: Current clocksource used for timekeeping.
  14. * @mask: Bitmask for two's complement subtraction of non 64bit clocks
  15. * @cycle_last: @clock cycle value at last update
  16. * @mult: (NTP adjusted) multiplier for scaled math conversion
  17. * @shift: Shift value for scaled math conversion
  18. * @xtime_nsec: Shifted (fractional) nano seconds offset for readout
  19. * @base: ktime_t (nanoseconds) base time for readout
  20. * @base_real: Nanoseconds base value for clock REALTIME readout
  21. *
  22. * This struct has size 56 byte on 64 bit. Together with a seqcount it
  23. * occupies a single 64byte cache line.
  24. *
  25. * The struct is separate from struct timekeeper as it is also used
  26. * for a fast NMI safe accessors.
  27. *
  28. * @base_real is for the fast NMI safe accessor to allow reading clock
  29. * realtime from any context.
  30. */
  31. struct tk_read_base {
  32. struct clocksource *clock;
  33. u64 mask;
  34. u64 cycle_last;
  35. u32 mult;
  36. u32 shift;
  37. u64 xtime_nsec;
  38. ktime_t base;
  39. u64 base_real;
  40. };
  41. /**
  42. * struct timekeeper - Structure holding internal timekeeping values.
  43. * @tkr_mono: The readout base structure for CLOCK_MONOTONIC
  44. * @tkr_raw: The readout base structure for CLOCK_MONOTONIC_RAW
  45. * @xtime_sec: Current CLOCK_REALTIME time in seconds
  46. * @ktime_sec: Current CLOCK_MONOTONIC time in seconds
  47. * @wall_to_monotonic: CLOCK_REALTIME to CLOCK_MONOTONIC offset
  48. * @offs_real: Offset clock monotonic -> clock realtime
  49. * @offs_boot: Offset clock monotonic -> clock boottime
  50. * @offs_tai: Offset clock monotonic -> clock tai
  51. * @tai_offset: The current UTC to TAI offset in seconds
  52. * @clock_was_set_seq: The sequence number of clock was set events
  53. * @cs_was_changed_seq: The sequence number of clocksource change events
  54. * @next_leap_ktime: CLOCK_MONOTONIC time value of a pending leap-second
  55. * @raw_sec: CLOCK_MONOTONIC_RAW time in seconds
  56. * @monotonic_to_boot: CLOCK_MONOTONIC to CLOCK_BOOTTIME offset
  57. * @cycle_interval: Number of clock cycles in one NTP interval
  58. * @xtime_interval: Number of clock shifted nano seconds in one NTP
  59. * interval.
  60. * @xtime_remainder: Shifted nano seconds left over when rounding
  61. * @cycle_interval
  62. * @raw_interval: Shifted raw nano seconds accumulated per NTP interval.
  63. * @ntp_error: Difference between accumulated time and NTP time in ntp
  64. * shifted nano seconds.
  65. * @ntp_error_shift: Shift conversion between clock shifted nano seconds and
  66. * ntp shifted nano seconds.
  67. * @last_warning: Warning ratelimiter (DEBUG_TIMEKEEPING)
  68. * @underflow_seen: Underflow warning flag (DEBUG_TIMEKEEPING)
  69. * @overflow_seen: Overflow warning flag (DEBUG_TIMEKEEPING)
  70. *
  71. * Note: For timespec(64) based interfaces wall_to_monotonic is what
  72. * we need to add to xtime (or xtime corrected for sub jiffie times)
  73. * to get to monotonic time. Monotonic is pegged at zero at system
  74. * boot time, so wall_to_monotonic will be negative, however, we will
  75. * ALWAYS keep the tv_nsec part positive so we can use the usual
  76. * normalization.
  77. *
  78. * wall_to_monotonic is moved after resume from suspend for the
  79. * monotonic time not to jump. We need to add total_sleep_time to
  80. * wall_to_monotonic to get the real boot based time offset.
  81. *
  82. * wall_to_monotonic is no longer the boot time, getboottime must be
  83. * used instead.
  84. *
  85. * @monotonic_to_boottime is a timespec64 representation of @offs_boot to
  86. * accelerate the VDSO update for CLOCK_BOOTTIME.
  87. */
  88. struct timekeeper {
  89. struct tk_read_base tkr_mono;
  90. struct tk_read_base tkr_raw;
  91. u64 xtime_sec;
  92. unsigned long ktime_sec;
  93. struct timespec64 wall_to_monotonic;
  94. ktime_t offs_real;
  95. ktime_t offs_boot;
  96. ktime_t offs_tai;
  97. s32 tai_offset;
  98. unsigned int clock_was_set_seq;
  99. u8 cs_was_changed_seq;
  100. ktime_t next_leap_ktime;
  101. u64 raw_sec;
  102. struct timespec64 monotonic_to_boot;
  103. /* The following members are for timekeeping internal use */
  104. u64 cycle_interval;
  105. u64 xtime_interval;
  106. s64 xtime_remainder;
  107. u64 raw_interval;
  108. /* The ntp_tick_length() value currently being used.
  109. * This cached copy ensures we consistently apply the tick
  110. * length for an entire tick, as ntp_tick_length may change
  111. * mid-tick, and we don't want to apply that new value to
  112. * the tick in progress.
  113. */
  114. u64 ntp_tick;
  115. /* Difference between accumulated time and NTP time in ntp
  116. * shifted nano seconds. */
  117. s64 ntp_error;
  118. u32 ntp_error_shift;
  119. u32 ntp_err_mult;
  120. /* Flag used to avoid updating NTP twice with same second */
  121. u32 skip_second_overflow;
  122. #ifdef CONFIG_DEBUG_TIMEKEEPING
  123. long last_warning;
  124. /*
  125. * These simple flag variables are managed
  126. * without locks, which is racy, but they are
  127. * ok since we don't really care about being
  128. * super precise about how many events were
  129. * seen, just that a problem was observed.
  130. */
  131. int underflow_seen;
  132. int overflow_seen;
  133. #endif
  134. };
  135. #ifdef CONFIG_GENERIC_TIME_VSYSCALL
  136. extern void update_vsyscall(struct timekeeper *tk);
  137. extern void update_vsyscall_tz(void);
  138. #else
  139. static inline void update_vsyscall(struct timekeeper *tk)
  140. {
  141. }
  142. static inline void update_vsyscall_tz(void)
  143. {
  144. }
  145. #endif
  146. #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */