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// SPDX-License-Identifier: GPL-2.0
/*
* Generic userspace implementations of gettimeofday() and similar.
*/
#include <linux/compiler.h>
#include <linux/math64.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/hrtimer_defs.h>
#include <vdso/datapage.h>
#include <vdso/helpers.h>
/*
* The generic vDSO implementation requires that gettimeofday.h
* provides:
* - __arch_get_vdso_data(): to get the vdso datapage.
* - __arch_get_hw_counter(): to get the hw counter based on the
* clock_mode.
* - gettimeofday_fallback(): fallback for gettimeofday.
* - clock_gettime_fallback(): fallback for clock_gettime.
* - clock_getres_fallback(): fallback for clock_getres.
*/
#ifdef ENABLE_COMPAT_VDSO
#include <asm/vdso/compat_gettimeofday.h>
#else
#include <asm/vdso/gettimeofday.h>
#endif /* ENABLE_COMPAT_VDSO */
#ifndef vdso_calc_delta
/*
* Default implementation which works for all sane clocksources. That
* obviously excludes x86/TSC.
*/
static __always_inline
u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
{
return ((cycles - last) & mask) * mult;
}
#endif
static int do_hres(const struct vdso_data *vd, clockid_t clk,
struct __kernel_timespec *ts)
{
const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
u64 cycles, last, sec, ns;
u32 seq;
do {
seq = vdso_read_begin(vd);
cycles = __arch_get_hw_counter(vd->clock_mode);
ns = vdso_ts->nsec;
last = vd->cycle_last;
if (unlikely((s64)cycles < 0))
return clock_gettime_fallback(clk, ts);
ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
ns >>= vd->shift;
sec = vdso_ts->sec;
} while (unlikely(vdso_read_retry(vd, seq)));
/*
* Do this outside the loop: a race inside the loop could result
* in __iter_div_u64_rem() being extremely slow.
*/
ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
ts->tv_nsec = ns;
return 0;
}
static void do_coarse(const struct vdso_data *vd, clockid_t clk,
struct __kernel_timespec *ts)
{
const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
u32 seq;
do {
seq = vdso_read_begin(vd);
ts->tv_sec = vdso_ts->sec;
ts->tv_nsec = vdso_ts->nsec;
} while (unlikely(vdso_read_retry(vd, seq)));
}
static __maybe_unused int
__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
{
const struct vdso_data *vd = __arch_get_vdso_data();
u32 msk;
/* Check for negative values or invalid clocks */
if (unlikely((u32) clock >= MAX_CLOCKS))
goto fallback;
/*
* Convert the clockid to a bitmask and use it to check which
* clocks are handled in the VDSO directly.
*/
msk = 1U << clock;
if (likely(msk & VDSO_HRES)) {
return do_hres(&vd[CS_HRES_COARSE], clock, ts);
} else if (msk & VDSO_COARSE) {
do_coarse(&vd[CS_HRES_COARSE], clock, ts);
return 0;
} else if (msk & VDSO_RAW) {
return do_hres(&vd[CS_RAW], clock, ts);
}
fallback:
return clock_gettime_fallback(clock, ts);
}
static __maybe_unused int
__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
{
struct __kernel_timespec ts;
int ret;
if (res == NULL)
goto fallback;
ret = __cvdso_clock_gettime(clock, &ts);
if (ret == 0) {
res->tv_sec = ts.tv_sec;
res->tv_nsec = ts.tv_nsec;
}
return ret;
fallback:
return clock_gettime_fallback(clock, (struct __kernel_timespec *)res);
}
static __maybe_unused int
__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
{
const struct vdso_data *vd = __arch_get_vdso_data();
if (likely(tv != NULL)) {
struct __kernel_timespec ts;
if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
return gettimeofday_fallback(tv, tz);
tv->tv_sec = ts.tv_sec;
tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC;
}
if (unlikely(tz != NULL)) {
tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
}
return 0;
}
#ifdef VDSO_HAS_TIME
static __maybe_unused time_t __cvdso_time(time_t *time)
{
const struct vdso_data *vd = __arch_get_vdso_data();
time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
if (time)
*time = t;
return t;
}
#endif /* VDSO_HAS_TIME */
#ifdef VDSO_HAS_CLOCK_GETRES
static __maybe_unused
int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
{
const struct vdso_data *vd = __arch_get_vdso_data();
u64 ns;
u32 msk;
u64 hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
/* Check for negative values or invalid clocks */
if (unlikely((u32) clock >= MAX_CLOCKS))
goto fallback;
/*
* Convert the clockid to a bitmask and use it to check which
* clocks are handled in the VDSO directly.
*/
msk = 1U << clock;
if (msk & VDSO_HRES) {
/*
* Preserves the behaviour of posix_get_hrtimer_res().
*/
ns = hrtimer_res;
} else if (msk & VDSO_COARSE) {
/*
* Preserves the behaviour of posix_get_coarse_res().
*/
ns = LOW_RES_NSEC;
} else if (msk & VDSO_RAW) {
/*
* Preserves the behaviour of posix_get_hrtimer_res().
*/
ns = hrtimer_res;
} else {
goto fallback;
}
if (res) {
res->tv_sec = 0;
res->tv_nsec = ns;
}
return 0;
fallback:
return clock_getres_fallback(clock, res);
}
static __maybe_unused int
__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
{
struct __kernel_timespec ts;
int ret;
if (res == NULL)
goto fallback;
ret = __cvdso_clock_getres(clock, &ts);
if (ret == 0) {
res->tv_sec = ts.tv_sec;
res->tv_nsec = ts.tv_nsec;
}
return ret;
fallback:
return clock_getres_fallback(clock, (struct __kernel_timespec *)res);
}
#endif /* VDSO_HAS_CLOCK_GETRES */
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