include/linux/time64.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_TIME64_H
   3 #define _LINUX_TIME64_H
   4
   5 #include <linux/math64.h>
   6 #include <vdso/time64.h>
   7
   8 typedef __s64 time64_t;
   9 typedef __u64 timeu64_t;
  10
  11 #include <uapi/linux/time.h>
  12
  13 struct timespec64 {
  14         time64_t        tv_sec;                 /* seconds */
  15         long            tv_nsec;                /* nanoseconds */
  16 };
  17
  18 struct itimerspec64 {
  19         struct timespec64 it_interval;
  20         struct timespec64 it_value;
  21 };
  22
  23 /* Parameters used to convert the timespec values: */
  24 #define PSEC_PER_NSEC                   1000L
  25
  26 /* Located here for timespec[64]_valid_strict */
  27 #define TIME64_MAX                      ((s64)~((u64)1 << 63))
  28 #define TIME64_MIN                      (-TIME64_MAX - 1)
  29
  30 #define KTIME_MAX                       ((s64)~((u64)1 << 63))
  31 #define KTIME_MIN                       (-KTIME_MAX - 1)
  32 #define KTIME_SEC_MAX                   (KTIME_MAX / NSEC_PER_SEC)
  33 #define KTIME_SEC_MIN                   (KTIME_MIN / NSEC_PER_SEC)
  34
  35 /*
  36  * Limits for settimeofday():
  37  *
  38  * To prevent setting the time close to the wraparound point time setting
  39  * is limited so a reasonable uptime can be accomodated. Uptime of 30 years
  40  * should be really sufficient, which means the cutoff is 2232. At that
  41  * point the cutoff is just a small part of the larger problem.
  42  */
  43 #define TIME_UPTIME_SEC_MAX             (30LL * 365 * 24 *3600)
  44 #define TIME_SETTOD_SEC_MAX             (KTIME_SEC_MAX - TIME_UPTIME_SEC_MAX)
  45
  46 static inline int timespec64_equal(const struct timespec64 *a,
  47                                    const struct timespec64 *b)
  48 {
  49         return (a->tv_sec == b->tv_sec) && (a->tv_nsec == b->tv_nsec);
  50 }
  51
  52 /*
  53  * lhs < rhs:  return <0
  54  * lhs == rhs: return 0
  55  * lhs > rhs:  return >0
  56  */
  57 static inline int timespec64_compare(const struct timespec64 *lhs, const struct timespec64 *rhs)
  58 {
  59         if (lhs->tv_sec < rhs->tv_sec)
  60                 return -1;
  61         if (lhs->tv_sec > rhs->tv_sec)
  62                 return 1;
  63         return lhs->tv_nsec - rhs->tv_nsec;
  64 }
  65
  66 extern void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec);
  67
  68 static inline struct timespec64 timespec64_add(struct timespec64 lhs,
  69                                                 struct timespec64 rhs)
  70 {
  71         struct timespec64 ts_delta;
  72         set_normalized_timespec64(&ts_delta, lhs.tv_sec + rhs.tv_sec,
  73                                 lhs.tv_nsec + rhs.tv_nsec);
  74         return ts_delta;
  75 }
  76
  77 /*
  78  * sub = lhs - rhs, in normalized form
  79  */
  80 static inline struct timespec64 timespec64_sub(struct timespec64 lhs,
  81                                                 struct timespec64 rhs)
  82 {
  83         struct timespec64 ts_delta;
  84         set_normalized_timespec64(&ts_delta, lhs.tv_sec - rhs.tv_sec,
  85                                 lhs.tv_nsec - rhs.tv_nsec);
  86         return ts_delta;
  87 }
  88
  89 /*
  90  * Returns true if the timespec64 is norm, false if denorm:
  91  */
  92 static inline bool timespec64_valid(const struct timespec64 *ts)
  93 {
  94         /* Dates before 1970 are bogus */
  95         if (ts->tv_sec < 0)
  96                 return false;
  97         /* Can't have more nanoseconds then a second */
  98         if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
  99                 return false;
 100         return true;
 101 }
 102
 103 static inline bool timespec64_valid_strict(const struct timespec64 *ts)
 104 {
 105         if (!timespec64_valid(ts))
 106                 return false;
 107         /* Disallow values that could overflow ktime_t */
 108         if ((unsigned long long)ts->tv_sec >= KTIME_SEC_MAX)
 109                 return false;
 110         return true;
 111 }
 112
 113 static inline bool timespec64_valid_settod(const struct timespec64 *ts)
 114 {
 115         if (!timespec64_valid(ts))
 116                 return false;
 117         /* Disallow values which cause overflow issues vs. CLOCK_REALTIME */
 118         if ((unsigned long long)ts->tv_sec >= TIME_SETTOD_SEC_MAX)
 119                 return false;
 120         return true;
 121 }
 122
 123 /**
 124  * timespec64_to_ns - Convert timespec64 to nanoseconds
 125  * @ts:         pointer to the timespec64 variable to be converted
 126  *
 127  * Returns the scalar nanosecond representation of the timespec64
 128  * parameter.
 129  */
 130 static inline s64 timespec64_to_ns(const struct timespec64 *ts)
 131 {
 132         /* Prevent multiplication overflow / underflow */
 133         if (ts->tv_sec >= KTIME_SEC_MAX)
 134                 return KTIME_MAX;
 135
 136         if (ts->tv_sec <= KTIME_SEC_MIN)
 137                 return KTIME_MIN;
 138
 139         return ((s64) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
 140 }
 141
 142 /**
 143  * ns_to_timespec64 - Convert nanoseconds to timespec64
 144  * @nsec:       the nanoseconds value to be converted
 145  *
 146  * Returns the timespec64 representation of the nsec parameter.
 147  */
 148 extern struct timespec64 ns_to_timespec64(s64 nsec);
 149
 150 /**
 151  * timespec64_add_ns - Adds nanoseconds to a timespec64
 152  * @a:          pointer to timespec64 to be incremented
 153  * @ns:         unsigned nanoseconds value to be added
 154  *
 155  * This must always be inlined because its used from the x86-64 vdso,
 156  * which cannot call other kernel functions.
 157  */
 158 static __always_inline void timespec64_add_ns(struct timespec64 *a, u64 ns)
 159 {
 160         a->tv_sec += __iter_div_u64_rem(a->tv_nsec + ns, NSEC_PER_SEC, &ns);
 161         a->tv_nsec = ns;
 162 }
 163
 164 /*
 165  * timespec64_add_safe assumes both values are positive and checks for
 166  * overflow. It will return TIME64_MAX in case of overflow.
 167  */
 168 extern struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
 169                                          const struct timespec64 rhs);
 170
 171 #endif /* _LINUX_TIME64_H */