/* $NetBSD: subr_time.c,v 1.35.4.2 2024/10/11 17:12:28 martin Exp $ */
/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
* @(#)kern_time.c 8.4 (Berkeley) 5/26/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_time.c,v 1.35.4.2 2024/10/11 17:12:28 martin Exp $");
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/kauth.h>
#include <sys/lwp.h>
#include <sys/timex.h>
#include <sys/time.h>
#include <sys/timetc.h>
#include <sys/intr.h>
/*
* Compute number of hz until specified time. Used to compute second
* argument to callout_reset() from an absolute time.
*/
int
tvhzto(const struct timeval *tvp)
{
struct timeval now, tv;
tv = *tvp; /* Don't modify original tvp. */
getmicrotime(&now);
timersub(&tv, &now, &tv);
return tvtohz(&tv);
}
/*
* Compute number of ticks in the specified amount of time.
*/
int
tvtohz(const struct timeval *tv)
{
unsigned long ticks;
long sec, usec;
/*
* If the number of usecs in the whole seconds part of the time
* difference fits in a long, then the total number of usecs will
* fit in an unsigned long. Compute the total and convert it to
* ticks, rounding up and adding 1 to allow for the current tick
* to expire. Rounding also depends on unsigned long arithmetic
* to avoid overflow.
*
* Otherwise, if the number of ticks in the whole seconds part of
* the time difference fits in a long, then convert the parts to
* ticks separately and add, using similar rounding methods and
* overflow avoidance. This method would work in the previous
* case, but it is slightly slower and assumes that hz is integral.
*
* Otherwise, round the time difference down to the maximum
* representable value.
*
* If ints are 32-bit, then the maximum value for any timeout in
* 10ms ticks is 248 days.
*/
sec = tv->tv_sec;
usec = tv->tv_usec;
KASSERT(usec >= 0);
KASSERT(usec < 1000000);
/* catch overflows in conversion time_t->int */
if (tv->tv_sec > INT_MAX)
return INT_MAX;
if (tv->tv_sec < 0)
return 0;
if (sec < 0 || (sec == 0 && usec == 0)) {
/*
* Would expire now or in the past. Return 0 ticks.
* This is different from the legacy tvhzto() interface,
* and callers need to check for it.
*/
ticks = 0;
} else if (sec <= (LONG_MAX / 1000000))
ticks = (((sec * 1000000) + (unsigned long)usec + (tick - 1))
/ tick) + 1;
else if (sec <= (LONG_MAX / hz))
ticks = (sec * hz) +
(((unsigned long)usec + (tick - 1)) / tick) + 1;
else
ticks = LONG_MAX;
if (ticks > INT_MAX)
ticks = INT_MAX;
return ((int)ticks);
}
int
tshzto(const struct timespec *tsp)
{
struct timespec now, ts;
ts = *tsp; /* Don't modify original tsp. */
getnanotime(&now);
timespecsub(&ts, &now, &ts);
return tstohz(&ts);
}
int
tshztoup(const struct timespec *tsp)
{
struct timespec now, ts;
ts = *tsp; /* Don't modify original tsp. */
getnanouptime(&now);
timespecsub(&ts, &now, &ts);
return tstohz(&ts);
}
/*
* Compute number of ticks in the specified amount of time.
*/
int
tstohz(const struct timespec *ts)
{
struct timeval tv;
/*
* usec has great enough resolution for hz, so convert to a
* timeval and use tvtohz() above.
*/
TIMESPEC_TO_TIMEVAL(&tv, ts);
return tvtohz(&tv);
}
/*
* Check that a proposed value to load into the .it_value or
* .it_interval part of an interval timer is acceptable, and
* fix it to have at least minimal value (i.e. if it is less
* than the resolution of the clock, round it up.). We don't
* timeout the 0,0 value because this means to disable the
* timer or the interval.
*/
int
itimerfix(struct timeval *tv)
{
if (tv->tv_usec < 0 || tv->tv_usec >= 1000000)
return EINVAL;
if (tv->tv_sec < 0)
return ETIMEDOUT;
if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
tv->tv_usec = tick;
return 0;
}
int
itimespecfix(struct timespec *ts)
{
if (ts->tv_nsec < 0 || ts->tv_nsec >= 1000000000)
return EINVAL;
if (ts->tv_sec < 0)
return ETIMEDOUT;
if (ts->tv_sec == 0 && ts->tv_nsec != 0 && ts->tv_nsec < tick * 1000)
ts->tv_nsec = tick * 1000;
return 0;
}
int
inittimeleft(struct timespec *ts, struct timespec *sleepts)
{
if (itimespecfix(ts)) {
return -1;
}
KASSERT(ts->tv_sec >= 0);
getnanouptime(sleepts);
return 0;
}
int
gettimeleft(struct timespec *ts, struct timespec *sleepts)
{
struct timespec now, sleptts;
KASSERT(ts->tv_sec >= 0);
/*
* Reduce ts by elapsed time based on monotonic time scale.
*/
getnanouptime(&now);
KASSERT(timespeccmp(sleepts, &now, <=));
timespecsub(&now, sleepts, &sleptts);
*sleepts = now;
if (timespeccmp(ts, &sleptts, <=)) { /* timed out */
timespecclear(ts);
return 0;
}
timespecsub(ts, &sleptts, ts);
return tstohz(ts);
}
void
clock_timeleft(clockid_t clockid, struct timespec *ts, struct timespec *sleepts)
{
struct timespec sleptts;
clock_gettime1(clockid, &sleptts);
timespecadd(ts, sleepts, ts);
timespecsub(ts, &sleptts, ts);
*sleepts = sleptts;
}
int
clock_gettime1(clockid_t clock_id, struct timespec *ts)
{
int error;
struct proc *p;
#define CPUCLOCK_ID_MASK (~(CLOCK_THREAD_CPUTIME_ID|CLOCK_PROCESS_CPUTIME_ID))
if (clock_id & CLOCK_PROCESS_CPUTIME_ID) {
pid_t pid = clock_id & CPUCLOCK_ID_MASK;
struct timeval cputime;
mutex_enter(&proc_lock);
p = pid == 0 ? curproc : proc_find(pid);
if (p == NULL) {
mutex_exit(&proc_lock);
return ESRCH;
}
mutex_enter(p->p_lock);
calcru(p, /*usertime*/NULL, /*systime*/NULL, /*intrtime*/NULL,
&cputime);
mutex_exit(p->p_lock);
mutex_exit(&proc_lock);
// XXX: Perhaps create a special kauth type
error = kauth_authorize_process(kauth_cred_get(),
KAUTH_PROCESS_PTRACE, p,
KAUTH_ARG(KAUTH_REQ_PROCESS_CANSEE_ENTRY), NULL, NULL);
if (error)
return error;
TIMEVAL_TO_TIMESPEC(&cputime, ts);
return 0;
} else if (clock_id & CLOCK_THREAD_CPUTIME_ID) {
struct lwp *l;
lwpid_t lid = clock_id & CPUCLOCK_ID_MASK;
struct bintime tm = {0, 0};
p = curproc;
mutex_enter(p->p_lock);
l = lid == 0 ? curlwp : lwp_find(p, lid);
if (l == NULL) {
mutex_exit(p->p_lock);
return ESRCH;
}
addrulwp(l, &tm);
mutex_exit(p->p_lock);
bintime2timespec(&tm, ts);
return 0;
}
switch (clock_id) {
case CLOCK_REALTIME:
nanotime(ts);
break;
case CLOCK_MONOTONIC:
nanouptime(ts);
break;
default:
return EINVAL;
}
return 0;
}
/*
* Calculate delta and convert from struct timespec to the ticks.
*/
int
ts2timo(clockid_t clock_id, int flags, struct timespec *ts,
int *timo, struct timespec *start)
{
int error;
struct timespec tsd;
if (ts->tv_nsec < 0 || ts->tv_nsec >= 1000000000L)
return EINVAL;
if ((flags & TIMER_ABSTIME) != 0 || start != NULL) {
error = clock_gettime1(clock_id, &tsd);
if (error != 0)
return error;
if (start != NULL)
*start = tsd;
}
if ((flags & TIMER_ABSTIME) != 0) {
if (!timespecsubok(ts, &tsd))
return EINVAL;
timespecsub(ts, &tsd, &tsd);
ts = &tsd;
}
error = itimespecfix(ts);
if (error != 0)
return error;
if (ts->tv_sec == 0 && ts->tv_nsec == 0)
return ETIMEDOUT;
*timo = tstohz(ts);
KASSERT(*timo > 0);
return 0;
}
bool
timespecaddok(const struct timespec *tsp, const struct timespec *usp)
{
enum { TIME_MIN = __type_min(time_t), TIME_MAX = __type_max(time_t) };
time_t a = tsp->tv_sec;
time_t b = usp->tv_sec;
bool carry;
/*
* Caller is responsible for guaranteeing valid timespec
* inputs. Any user-controlled inputs must be validated or
* adjusted.
*/
KASSERT(tsp->tv_nsec >= 0);
KASSERT(usp->tv_nsec >= 0);
KASSERT(tsp->tv_nsec < 1000000000L);
KASSERT(usp->tv_nsec < 1000000000L);
CTASSERT(1000000000L <= __type_max(long) - 1000000000L);
/*
* Fail if a + b + carry overflows TIME_MAX, or if a + b
* overflows TIME_MIN because timespecadd adds the carry after
* computing a + b.
*
* Break it into two mutually exclusive and exhaustive cases:
* I. a >= 0
* II. a < 0
*/
carry = (tsp->tv_nsec + usp->tv_nsec >= 1000000000L);
if (a >= 0) {
/*
* Case I: a >= 0. If b < 0, then b + 1 <= 0, so
*
* a + b + 1 <= a + 0 <= TIME_MAX,
*
* and
*
* a + b >= 0 + b = b >= TIME_MIN,
*
* so this can't overflow.
*
* If b >= 0, then a + b + carry >= a + b >= 0, so
* negative results and thus results below TIME_MIN are
* impossible; we need only avoid
*
* a + b + carry > TIME_MAX,
*
* which we will do by rejecting if
*
* b > TIME_MAX - a - carry,
*
* which in turn is incidentally always false if b < 0
* so we don't need extra logic to discriminate on the
* b >= 0 and b < 0 cases.
*
* Since 0 <= a <= TIME_MAX, we know
*
* 0 <= TIME_MAX - a <= TIME_MAX,
*
* and hence
*
* -1 <= TIME_MAX - a - 1 < TIME_MAX.
*
* So we can compute TIME_MAX - a - carry (i.e., either
* TIME_MAX - a or TIME_MAX - a - 1) safely without
* overflow.
*/
if (b > TIME_MAX - a - carry)
return false;
} else {
/*
* Case II: a < 0. If b >= 0, then since a + 1 <= 0,
* we have
*
* a + b + 1 <= b <= TIME_MAX,
*
* and
*
* a + b >= a >= TIME_MIN,
*
* so this can't overflow.
*
* If b < 0, then the intermediate a + b is negative
* and the outcome a + b + 1 is nonpositive, so we need
* only avoid
*
* a + b < TIME_MIN,
*
* which we will do by rejecting if
*
* a < TIME_MIN - b.
*
* (Reminder: The carry is added afterward in
* timespecadd, so to avoid overflow it is not enough
* to merely reject a + b + carry < TIME_MIN.)
*
* It is safe to compute the difference TIME_MIN - b
* because b is negative, so the result lies in
* (TIME_MIN, 0].
*/
if (b < 0 && a < TIME_MIN - b)
return false;
}
return true;
}
bool
timespecsubok(const struct timespec *tsp, const struct timespec *usp)
{
enum { TIME_MIN = __type_min(time_t), TIME_MAX = __type_max(time_t) };
time_t a = tsp->tv_sec, b = usp->tv_sec;
bool borrow;
/*
* Caller is responsible for guaranteeing valid timespec
* inputs. Any user-controlled inputs must be validated or
* adjusted.
*/
KASSERT(tsp->tv_nsec >= 0);
KASSERT(usp->tv_nsec >= 0);
KASSERT(tsp->tv_nsec < 1000000000L);
KASSERT(usp->tv_nsec < 1000000000L);
CTASSERT(1000000000L <= __type_max(long) - 1000000000L);
/*
* Fail if a - b - borrow overflows TIME_MIN, or if a - b
* overflows TIME_MAX because timespecsub subtracts the borrow
* after computing a - b.
*
* Break it into two mutually exclusive and exhaustive cases:
* I. a < 0
* II. a >= 0
*/
borrow = (tsp->tv_nsec - usp->tv_nsec < 0);
if (a < 0) {
/*
* Case I: a < 0. If b < 0, then -b - 1 >= 0, so
*
* a - b - 1 >= a + 0 >= TIME_MIN,
*
* and, since a <= -1, provided that TIME_MIN <=
* -TIME_MAX - 1 so that TIME_MAX <= -TIME_MIN - 1 (in
* fact, equality holds, under the assumption of
* two's-complement arithmetic),
*
* a - b <= -1 - b = -b - 1 <= TIME_MAX,
*
* so this can't overflow.
*/
CTASSERT(TIME_MIN <= -TIME_MAX - 1);
/*
* If b >= 0, then a - b - borrow <= a - b < 0, so
* positive results and thus results above TIME_MAX are
* impossible; we need only avoid
*
* a - b - borrow < TIME_MIN,
*
* which we will do by rejecting if
*
* a < TIME_MIN + b + borrow.
*
* The right-hand side is safe to evaluate for any
* values of b and borrow as long as TIME_MIN +
* TIME_MAX + 1 <= TIME_MAX, i.e., TIME_MIN <= -1.
* (Note: If time_t were unsigned, this would fail!)
*
* Note: Unlike Case I in timespecaddok, this criterion
* does not work for b < 0, nor can the roles of a and
* b in the inequality be reversed (e.g., -b < TIME_MIN
* - a + borrow) without extra cases like checking for
* b = TEST_MIN.
*/
CTASSERT(TIME_MIN < -1);
if (b >= 0 && a < TIME_MIN + b + borrow)
return false;
} else {
/*
* Case II: a >= 0. If b >= 0, then
*
* a - b <= a <= TIME_MAX,
*
* and, provided TIME_MIN <= -TIME_MAX - 1 (in fact,
* equality holds, under the assumption of
* two's-complement arithmetic)
*
* a - b - 1 >= -b - 1 >= -TIME_MAX - 1 >= TIME_MIN,
*
* so this can't overflow.
*/
CTASSERT(TIME_MIN <= -TIME_MAX - 1);
/*
* If b < 0, then a - b >= a >= 0, so negative results
* and thus results below TIME_MIN are impossible; we
* need only avoid
*
* a - b > TIME_MAX,
*
* which we will do by rejecting if
*
* a > TIME_MAX + b.
*
* (Reminder: The borrow is subtracted afterward in
* timespecsub, so to avoid overflow it is not enough
* to merely reject a - b - borrow > TIME_MAX.)
*
* It is safe to compute the sum TIME_MAX + b because b
* is negative, so the result lies in [0, TIME_MAX).
*/
if (b < 0 && a > TIME_MAX + b)
return false;
}
return true;
}