mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 02:39:48 +00:00
![Thomas Gleixner](/assets/img/avatar_default.png)
Several people reported testing failures after setting CLOCK_REALTIME close to the limits of the kernel internal representation in nanoseconds, i.e. year 2262. The failures are exposed in subsequent operations, i.e. when arming timers or when the advancing CLOCK_MONOTONIC makes the calculation of CLOCK_REALTIME overflow into negative space. Now people start to paper over the underlying problem by clamping calculations to the valid range, but that's just wrong because such workarounds will prevent detection of real issues as well. It is reasonable to force an upper bound for the various methods of setting CLOCK_REALTIME. Year 2262 is the absolute upper bound. Assume a maximum uptime of 30 years which is plenty enough even for esoteric embedded systems. That results in an upper bound of year 2232 for setting the time. Once that limit is reached in reality this limit is only a small part of the problem space. But until then this stops people from trying to paper over the problem at the wrong places. Reported-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> Reported-by: Hongbo Yao <yaohongbo@huawei.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Boyd <sboyd@kernel.org> Cc: Miroslav Lichvar <mlichvar@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1903231125480.2157@nanos.tec.linutronix.de
165 lines
4.4 KiB
C
165 lines
4.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_TIME64_H
|
|
#define _LINUX_TIME64_H
|
|
|
|
#include <linux/math64.h>
|
|
|
|
typedef __s64 time64_t;
|
|
typedef __u64 timeu64_t;
|
|
|
|
#include <uapi/linux/time.h>
|
|
|
|
struct timespec64 {
|
|
time64_t tv_sec; /* seconds */
|
|
long tv_nsec; /* nanoseconds */
|
|
};
|
|
|
|
struct itimerspec64 {
|
|
struct timespec64 it_interval;
|
|
struct timespec64 it_value;
|
|
};
|
|
|
|
/* Parameters used to convert the timespec values: */
|
|
#define MSEC_PER_SEC 1000L
|
|
#define USEC_PER_MSEC 1000L
|
|
#define NSEC_PER_USEC 1000L
|
|
#define NSEC_PER_MSEC 1000000L
|
|
#define USEC_PER_SEC 1000000L
|
|
#define NSEC_PER_SEC 1000000000L
|
|
#define FSEC_PER_SEC 1000000000000000LL
|
|
|
|
/* Located here for timespec[64]_valid_strict */
|
|
#define TIME64_MAX ((s64)~((u64)1 << 63))
|
|
#define KTIME_MAX ((s64)~((u64)1 << 63))
|
|
#define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
|
|
|
|
/*
|
|
* Limits for settimeofday():
|
|
*
|
|
* To prevent setting the time close to the wraparound point time setting
|
|
* is limited so a reasonable uptime can be accomodated. Uptime of 30 years
|
|
* should be really sufficient, which means the cutoff is 2232. At that
|
|
* point the cutoff is just a small part of the larger problem.
|
|
*/
|
|
#define TIME_UPTIME_SEC_MAX (30LL * 365 * 24 *3600)
|
|
#define TIME_SETTOD_SEC_MAX (KTIME_SEC_MAX - TIME_UPTIME_SEC_MAX)
|
|
|
|
static inline int timespec64_equal(const struct timespec64 *a,
|
|
const struct timespec64 *b)
|
|
{
|
|
return (a->tv_sec == b->tv_sec) && (a->tv_nsec == b->tv_nsec);
|
|
}
|
|
|
|
/*
|
|
* lhs < rhs: return <0
|
|
* lhs == rhs: return 0
|
|
* lhs > rhs: return >0
|
|
*/
|
|
static inline int timespec64_compare(const struct timespec64 *lhs, const struct timespec64 *rhs)
|
|
{
|
|
if (lhs->tv_sec < rhs->tv_sec)
|
|
return -1;
|
|
if (lhs->tv_sec > rhs->tv_sec)
|
|
return 1;
|
|
return lhs->tv_nsec - rhs->tv_nsec;
|
|
}
|
|
|
|
extern void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec);
|
|
|
|
static inline struct timespec64 timespec64_add(struct timespec64 lhs,
|
|
struct timespec64 rhs)
|
|
{
|
|
struct timespec64 ts_delta;
|
|
set_normalized_timespec64(&ts_delta, lhs.tv_sec + rhs.tv_sec,
|
|
lhs.tv_nsec + rhs.tv_nsec);
|
|
return ts_delta;
|
|
}
|
|
|
|
/*
|
|
* sub = lhs - rhs, in normalized form
|
|
*/
|
|
static inline struct timespec64 timespec64_sub(struct timespec64 lhs,
|
|
struct timespec64 rhs)
|
|
{
|
|
struct timespec64 ts_delta;
|
|
set_normalized_timespec64(&ts_delta, lhs.tv_sec - rhs.tv_sec,
|
|
lhs.tv_nsec - rhs.tv_nsec);
|
|
return ts_delta;
|
|
}
|
|
|
|
/*
|
|
* Returns true if the timespec64 is norm, false if denorm:
|
|
*/
|
|
static inline bool timespec64_valid(const struct timespec64 *ts)
|
|
{
|
|
/* Dates before 1970 are bogus */
|
|
if (ts->tv_sec < 0)
|
|
return false;
|
|
/* Can't have more nanoseconds then a second */
|
|
if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
static inline bool timespec64_valid_strict(const struct timespec64 *ts)
|
|
{
|
|
if (!timespec64_valid(ts))
|
|
return false;
|
|
/* Disallow values that could overflow ktime_t */
|
|
if ((unsigned long long)ts->tv_sec >= KTIME_SEC_MAX)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
static inline bool timespec64_valid_settod(const struct timespec64 *ts)
|
|
{
|
|
if (!timespec64_valid(ts))
|
|
return false;
|
|
/* Disallow values which cause overflow issues vs. CLOCK_REALTIME */
|
|
if ((unsigned long long)ts->tv_sec >= TIME_SETTOD_SEC_MAX)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* timespec64_to_ns - Convert timespec64 to nanoseconds
|
|
* @ts: pointer to the timespec64 variable to be converted
|
|
*
|
|
* Returns the scalar nanosecond representation of the timespec64
|
|
* parameter.
|
|
*/
|
|
static inline s64 timespec64_to_ns(const struct timespec64 *ts)
|
|
{
|
|
return ((s64) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
|
|
}
|
|
|
|
/**
|
|
* ns_to_timespec64 - Convert nanoseconds to timespec64
|
|
* @nsec: the nanoseconds value to be converted
|
|
*
|
|
* Returns the timespec64 representation of the nsec parameter.
|
|
*/
|
|
extern struct timespec64 ns_to_timespec64(const s64 nsec);
|
|
|
|
/**
|
|
* timespec64_add_ns - Adds nanoseconds to a timespec64
|
|
* @a: pointer to timespec64 to be incremented
|
|
* @ns: unsigned nanoseconds value to be added
|
|
*
|
|
* This must always be inlined because its used from the x86-64 vdso,
|
|
* which cannot call other kernel functions.
|
|
*/
|
|
static __always_inline void timespec64_add_ns(struct timespec64 *a, u64 ns)
|
|
{
|
|
a->tv_sec += __iter_div_u64_rem(a->tv_nsec + ns, NSEC_PER_SEC, &ns);
|
|
a->tv_nsec = ns;
|
|
}
|
|
|
|
/*
|
|
* timespec64_add_safe assumes both values are positive and checks for
|
|
* overflow. It will return TIME64_MAX in case of overflow.
|
|
*/
|
|
extern struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
|
|
const struct timespec64 rhs);
|
|
|
|
#endif /* _LINUX_TIME64_H */
|