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 7 #ifndef _LINUX_TIMEKEEPER_INTERNAL_H 8 #define _LINUX_TIMEKEEPER_INTERNAL_H 9 10 #include <linux/clocksource.h> 11 #include <linux/jiffies.h> 12 #include <linux/time.h> 13 14 /** 15 * struct tk_read_base - base structure for timekeeping readout 16 * @clock: Current clocksource used for timekeeping. 17 * @mask: Bitmask for two's complement subtraction of non 64bit clocks 18 * @cycle_last: @clock cycle value at last update 19 * @mult: (NTP adjusted) multiplier for scaled math conversion 20 * @shift: Shift value for scaled math conversion 21 * @xtime_nsec: Shifted (fractional) nano seconds offset for readout 22 * @base: ktime_t (nanoseconds) base time for readout 23 * @base_real: Nanoseconds base value for clock REALTIME readout 24 * 25 * This struct has size 56 byte on 64 bit. Together with a seqcount it 26 * occupies a single 64byte cache line. 27 * 28 * The struct is separate from struct timekeeper as it is also used 29 * for a fast NMI safe accessors. 30 * 31 * @base_real is for the fast NMI safe accessor to allow reading clock 32 * realtime from any context. 33 */ 34 struct tk_read_base { 35 struct clocksource *clock; 36 u64 mask; 37 u64 cycle_last; 38 u32 mult; 39 u32 shift; 40 u64 xtime_nsec; 41 ktime_t base; 42 u64 base_real; 43 }; 44 45 /** 46 * struct timekeeper - Structure holding internal timekeeping values. 47 * @tkr_mono: The readout base structure for CLOCK_MONOTONIC 48 * @tkr_raw: The readout base structure for CLOCK_MONOTONIC_RAW 49 * @xtime_sec: Current CLOCK_REALTIME time in seconds 50 * @ktime_sec: Current CLOCK_MONOTONIC time in seconds 51 * @wall_to_monotonic: CLOCK_REALTIME to CLOCK_MONOTONIC offset 52 * @offs_real: Offset clock monotonic -> clock realtime 53 * @offs_boot: Offset clock monotonic -> clock boottime 54 * @offs_tai: Offset clock monotonic -> clock tai 55 * @tai_offset: The current UTC to TAI offset in seconds 56 * @clock_was_set_seq: The sequence number of clock was set events 57 * @cs_was_changed_seq: The sequence number of clocksource change events 58 * @next_leap_ktime: CLOCK_MONOTONIC time value of a pending leap-second 59 * @raw_sec: CLOCK_MONOTONIC_RAW time in seconds 60 * @monotonic_to_boot: CLOCK_MONOTONIC to CLOCK_BOOTTIME offset 61 * @cycle_interval: Number of clock cycles in one NTP interval 62 * @xtime_interval: Number of clock shifted nano seconds in one NTP 63 * interval. 64 * @xtime_remainder: Shifted nano seconds left over when rounding 65 * @cycle_interval 66 * @raw_interval: Shifted raw nano seconds accumulated per NTP interval. 67 * @ntp_error: Difference between accumulated time and NTP time in ntp 68 * shifted nano seconds. 69 * @ntp_error_shift: Shift conversion between clock shifted nano seconds and 70 * ntp shifted nano seconds. 71 * @last_warning: Warning ratelimiter (DEBUG_TIMEKEEPING) 72 * @underflow_seen: Underflow warning flag (DEBUG_TIMEKEEPING) 73 * @overflow_seen: Overflow warning flag (DEBUG_TIMEKEEPING) 74 * 75 * Note: For timespec(64) based interfaces wall_to_monotonic is what 76 * we need to add to xtime (or xtime corrected for sub jiffy times) 77 * to get to monotonic time. Monotonic is pegged at zero at system 78 * boot time, so wall_to_monotonic will be negative, however, we will 79 * ALWAYS keep the tv_nsec part positive so we can use the usual 80 * normalization. 81 * 82 * wall_to_monotonic is moved after resume from suspend for the 83 * monotonic time not to jump. We need to add total_sleep_time to 84 * wall_to_monotonic to get the real boot based time offset. 85 * 86 * wall_to_monotonic is no longer the boot time, getboottime must be 87 * used instead. 88 * 89 * @monotonic_to_boottime is a timespec64 representation of @offs_boot to 90 * accelerate the VDSO update for CLOCK_BOOTTIME. 91 */ 92 struct timekeeper { 93 struct tk_read_base tkr_mono; 94 struct tk_read_base tkr_raw; 95 u64 xtime_sec; 96 unsigned long ktime_sec; 97 struct timespec64 wall_to_monotonic; 98 ktime_t offs_real; 99 ktime_t offs_boot; 100 ktime_t offs_tai; 101 s32 tai_offset; 102 unsigned int clock_was_set_seq; 103 u8 cs_was_changed_seq; 104 ktime_t next_leap_ktime; 105 u64 raw_sec; 106 struct timespec64 monotonic_to_boot; 107 108 /* The following members are for timekeeping internal use */ 109 u64 cycle_interval; 110 u64 xtime_interval; 111 s64 xtime_remainder; 112 u64 raw_interval; 113 /* The ntp_tick_length() value currently being used. 114 * This cached copy ensures we consistently apply the tick 115 * length for an entire tick, as ntp_tick_length may change 116 * mid-tick, and we don't want to apply that new value to 117 * the tick in progress. 118 */ 119 u64 ntp_tick; 120 /* Difference between accumulated time and NTP time in ntp 121 * shifted nano seconds. */ 122 s64 ntp_error; 123 u32 ntp_error_shift; 124 u32 ntp_err_mult; 125 /* Flag used to avoid updating NTP twice with same second */ 126 u32 skip_second_overflow; 127 #ifdef CONFIG_DEBUG_TIMEKEEPING 128 long last_warning; 129 /* 130 * These simple flag variables are managed 131 * without locks, which is racy, but they are 132 * ok since we don't really care about being 133 * super precise about how many events were 134 * seen, just that a problem was observed. 135 */ 136 int underflow_seen; 137 int overflow_seen; 138 #endif 139 }; 140 141 #ifdef CONFIG_GENERIC_TIME_VSYSCALL 142 143 extern void update_vsyscall(struct timekeeper *tk); 144 extern void update_vsyscall_tz(void); 145 146 #else 147 update_vsyscall(struct timekeeper * tk)148 static inline void update_vsyscall(struct timekeeper *tk) 149 { 150 } update_vsyscall_tz(void)151 static inline void update_vsyscall_tz(void) 152 { 153 } 154 #endif 155 156 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */ 157