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authorLinus Torvalds2020-01-27 16:47:05 -0800
committerLinus Torvalds2020-01-27 16:47:05 -0800
commite279160f491392f1345f6eb4b0eeec5a6a2ecdd7 (patch)
tree018410c41f919774f70e6350fc251556bf789944 /lib
parent534b0a8b677443c0aa8c4c71ff7887f08a2b9b41 (diff)
parentfd928f3e32ba09381b287f8b732418434d932855 (diff)
Merge tag 'timers-core-2020-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner: "The timekeeping and timers departement provides: - Time namespace support: If a container migrates from one host to another then it expects that clocks based on MONOTONIC and BOOTTIME are not subject to disruption. Due to different boot time and non-suspended runtime these clocks can differ significantly on two hosts, in the worst case time goes backwards which is a violation of the POSIX requirements. The time namespace addresses this problem. It allows to set offsets for clock MONOTONIC and BOOTTIME once after creation and before tasks are associated with the namespace. These offsets are taken into account by timers and timekeeping including the VDSO. Offsets for wall clock based clocks (REALTIME/TAI) are not provided by this mechanism. While in theory possible, the overhead and code complexity would be immense and not justified by the esoteric potential use cases which were discussed at Plumbers '18. The overhead for tasks in the root namespace (ie where host time offsets = 0) is in the noise and great effort was made to ensure that especially in the VDSO. If time namespace is disabled in the kernel configuration the code is compiled out. Kudos to Andrei Vagin and Dmitry Sofanov who implemented this feature and kept on for more than a year addressing review comments, finding better solutions. A pleasant experience. - Overhaul of the alarmtimer device dependency handling to ensure that the init/suspend/resume ordering is correct. - A new clocksource/event driver for Microchip PIT64 - Suspend/resume support for the Hyper-V clocksource - The usual pile of fixes, updates and improvements mostly in the driver code" * tag 'timers-core-2020-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits) alarmtimer: Make alarmtimer_get_rtcdev() a stub when CONFIG_RTC_CLASS=n alarmtimer: Use wakeup source from alarmtimer platform device alarmtimer: Make alarmtimer platform device child of RTC device alarmtimer: Update alarmtimer_get_rtcdev() docs to reflect reality hrtimer: Add missing sparse annotation for __run_timer() lib/vdso: Only read hrtimer_res when needed in __cvdso_clock_getres() MIPS: vdso: Define BUILD_VDSO32 when building a 32bit kernel clocksource/drivers/hyper-v: Set TSC clocksource as default w/ InvariantTSC clocksource/drivers/hyper-v: Untangle stimers and timesync from clocksources clocksource/drivers/timer-microchip-pit64b: Fix sparse warning clocksource/drivers/exynos_mct: Rename Exynos to lowercase clocksource/drivers/timer-ti-dm: Fix uninitialized pointer access clocksource/drivers/timer-ti-dm: Switch to platform_get_irq clocksource/drivers/timer-ti-dm: Convert to devm_platform_ioremap_resource clocksource/drivers/em_sti: Fix variable declaration in em_sti_probe clocksource/drivers/em_sti: Convert to devm_platform_ioremap_resource clocksource/drivers/bcm2835_timer: Fix memory leak of timer clocksource/drivers/cadence-ttc: Use ttc driver as platform driver clocksource/drivers/timer-microchip-pit64b: Add Microchip PIT64B support clocksource/drivers/hyper-v: Reserve PAGE_SIZE space for tsc page ...
Diffstat (limited to 'lib')
-rw-r--r--lib/vdso/Kconfig6
-rw-r--r--lib/vdso/gettimeofday.c204
2 files changed, 170 insertions, 40 deletions
diff --git a/lib/vdso/Kconfig b/lib/vdso/Kconfig
index 9fe698ff62ec..d883ac299508 100644
--- a/lib/vdso/Kconfig
+++ b/lib/vdso/Kconfig
@@ -24,4 +24,10 @@ config GENERIC_COMPAT_VDSO
help
This config option enables the compat VDSO layer.
+config GENERIC_VDSO_TIME_NS
+ bool
+ help
+ Selected by architectures which support time namespaces in the
+ VDSO
+
endif
diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 42bd8ab955fa..f8b8ec5e63ac 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -38,12 +38,22 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
}
#endif
-static int do_hres(const struct vdso_data *vd, clockid_t clk,
- struct __kernel_timespec *ts)
+#ifdef CONFIG_TIME_NS
+static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
+ struct __kernel_timespec *ts)
{
- const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
- u64 cycles, last, sec, ns;
+ const struct vdso_data *vd = __arch_get_timens_vdso_data();
+ const struct timens_offset *offs = &vdns->offset[clk];
+ const struct vdso_timestamp *vdso_ts;
+ u64 cycles, last, ns;
u32 seq;
+ s64 sec;
+
+ if (clk != CLOCK_MONOTONIC_RAW)
+ vd = &vd[CS_HRES_COARSE];
+ else
+ vd = &vd[CS_RAW];
+ vdso_ts = &vd->basetime[clk];
do {
seq = vdso_read_begin(vd);
@@ -58,6 +68,10 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
sec = vdso_ts->sec;
} while (unlikely(vdso_read_retry(vd, seq)));
+ /* Add the namespace offset */
+ sec += offs->sec;
+ ns += offs->nsec;
+
/*
* Do this outside the loop: a race inside the loop could result
* in __iter_div_u64_rem() being extremely slow.
@@ -67,18 +81,128 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
return 0;
}
+#else
+static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
+{
+ return NULL;
+}
+
+static int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
+ struct __kernel_timespec *ts)
+{
+ return -EINVAL;
+}
+#endif
-static void do_coarse(const struct vdso_data *vd, clockid_t clk,
- struct __kernel_timespec *ts)
+static __always_inline 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 {
+ /*
+ * Open coded to handle VCLOCK_TIMENS. Time namespace
+ * enabled tasks have a special VVAR page installed which
+ * has vd->seq set to 1 and vd->clock_mode set to
+ * VCLOCK_TIMENS. For non time namespace affected tasks
+ * this does not affect performance because if vd->seq is
+ * odd, i.e. a concurrent update is in progress the extra
+ * check for vd->clock_mode is just a few extra
+ * instructions while spin waiting for vd->seq to become
+ * even again.
+ */
+ while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) {
+ if (IS_ENABLED(CONFIG_TIME_NS) &&
+ vd->clock_mode == VCLOCK_TIMENS)
+ return do_hres_timens(vd, clk, ts);
+ cpu_relax();
+ }
+ smp_rmb();
+
+ cycles = __arch_get_hw_counter(vd->clock_mode);
+ ns = vdso_ts->nsec;
+ last = vd->cycle_last;
+ if (unlikely((s64)cycles < 0))
+ return -1;
+
+ 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;
+}
+
+#ifdef CONFIG_TIME_NS
+static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
+ struct __kernel_timespec *ts)
+{
+ const struct vdso_data *vd = __arch_get_timens_vdso_data();
+ const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
+ const struct timens_offset *offs = &vdns->offset[clk];
+ u64 nsec;
+ s64 sec;
+ s32 seq;
+
+ do {
seq = vdso_read_begin(vd);
+ sec = vdso_ts->sec;
+ nsec = vdso_ts->nsec;
+ } while (unlikely(vdso_read_retry(vd, seq)));
+
+ /* Add the namespace offset */
+ sec += offs->sec;
+ nsec += offs->nsec;
+
+ /*
+ * 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(nsec, NSEC_PER_SEC, &nsec);
+ ts->tv_nsec = nsec;
+ return 0;
+}
+#else
+static int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
+ struct __kernel_timespec *ts)
+{
+ return -1;
+}
+#endif
+
+static __always_inline int 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 {
+ /*
+ * Open coded to handle VCLOCK_TIMENS. See comment in
+ * do_hres().
+ */
+ while ((seq = READ_ONCE(vd->seq)) & 1) {
+ if (IS_ENABLED(CONFIG_TIME_NS) &&
+ vd->clock_mode == VCLOCK_TIMENS)
+ return do_coarse_timens(vd, clk, ts);
+ cpu_relax();
+ }
+ smp_rmb();
+
ts->tv_sec = vdso_ts->sec;
ts->tv_nsec = vdso_ts->nsec;
} while (unlikely(vdso_read_retry(vd, seq)));
+
+ return 0;
}
static __maybe_unused int
@@ -96,15 +220,16 @@ __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
* 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);
- }
- return -1;
+ if (likely(msk & VDSO_HRES))
+ vd = &vd[CS_HRES_COARSE];
+ else if (msk & VDSO_COARSE)
+ return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
+ else if (msk & VDSO_RAW)
+ vd = &vd[CS_RAW];
+ else
+ return -1;
+
+ return do_hres(vd, clock, ts);
}
static __maybe_unused int
@@ -117,6 +242,7 @@ __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
return 0;
}
+#ifdef BUILD_VDSO32
static __maybe_unused int
__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
{
@@ -125,20 +251,16 @@ __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
ret = __cvdso_clock_gettime_common(clock, &ts);
-#ifdef VDSO_HAS_32BIT_FALLBACK
if (unlikely(ret))
return clock_gettime32_fallback(clock, res);
-#else
- if (unlikely(ret))
- ret = clock_gettime_fallback(clock, &ts);
-#endif
- if (likely(!ret)) {
- res->tv_sec = ts.tv_sec;
- res->tv_nsec = ts.tv_nsec;
- }
+ /* For ret == 0 */
+ res->tv_sec = ts.tv_sec;
+ res->tv_nsec = ts.tv_nsec;
+
return ret;
}
+#endif /* BUILD_VDSO32 */
static __maybe_unused int
__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
@@ -156,6 +278,10 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
}
if (unlikely(tz != NULL)) {
+ if (IS_ENABLED(CONFIG_TIME_NS) &&
+ vd->clock_mode == VCLOCK_TIMENS)
+ vd = __arch_get_timens_vdso_data();
+
tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
}
@@ -167,7 +293,12 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
{
const struct vdso_data *vd = __arch_get_vdso_data();
- __kernel_old_time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
+ __kernel_old_time_t t;
+
+ if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS)
+ vd = __arch_get_timens_vdso_data();
+
+ t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
if (time)
*time = t;
@@ -181,7 +312,6 @@ static __maybe_unused
int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
{
const struct vdso_data *vd = __arch_get_vdso_data();
- u64 hrtimer_res;
u32 msk;
u64 ns;
@@ -189,27 +319,24 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
if (unlikely((u32) clock >= MAX_CLOCKS))
return -1;
- hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
+ if (IS_ENABLED(CONFIG_TIME_NS) && vd->clock_mode == VCLOCK_TIMENS)
+ vd = __arch_get_timens_vdso_data();
+
/*
* 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) {
+ if (msk & (VDSO_HRES | VDSO_RAW)) {
/*
* Preserves the behaviour of posix_get_hrtimer_res().
*/
- ns = hrtimer_res;
+ ns = READ_ONCE(vd[CS_HRES_COARSE].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 {
return -1;
}
@@ -231,6 +358,7 @@ int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
return 0;
}
+#ifdef BUILD_VDSO32
static __maybe_unused int
__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
{
@@ -239,18 +367,14 @@ __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
ret = __cvdso_clock_getres_common(clock, &ts);
-#ifdef VDSO_HAS_32BIT_FALLBACK
if (unlikely(ret))
return clock_getres32_fallback(clock, res);
-#else
- if (unlikely(ret))
- ret = clock_getres_fallback(clock, &ts);
-#endif
- if (likely(!ret && res)) {
+ if (likely(res)) {
res->tv_sec = ts.tv_sec;
res->tv_nsec = ts.tv_nsec;
}
return ret;
}
+#endif /* BUILD_VDSO32 */
#endif /* VDSO_HAS_CLOCK_GETRES */