Commit Graph

518 Commits

Author SHA1 Message Date
David Woodhouse
ca1ec8bfac timekeeping: Add clocksource read_snapshot() method and hw_cycles to snapshot
Add a read_snapshot() callback to struct clocksource which returns the
derived clocksource value while also providing the underlying hardware
counter reading and the related clocksource ID.

This allows ktime_get_snapshot_id() to populate new hw_cycles and hw_csid
fields in struct system_time_snapshot.

For clocksources that are derived from an underlying counter (e.g., Hyper-V
TSC page scales TSC to 10MHz, kvmclock scales TSC to 1GHz), this provides
atomic access to both the derived value needed for timekeeping
calculations, and the raw hardware counter needed by consumers like KVM's
master clock and the vmclock PTP driver.

[ tglx: Reworked it slightly ]

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Assisted-by: Kiro:claude-opus-4.6-1m
Link: https://patch.msgid.link/20260526230635.136914-1-dwmw2@infradead.org
Link: https://patch.msgid.link/20260529195558.202568489@kernel.org
2026-06-04 11:04:18 +02:00
Thomas Gleixner
9aebde8af6 timekeeping: Add support for AUX clock cross timestamping
Now that all prerequisites are in place add the final support for AUX
clocks in get_device_system_crosststamp(), which enables the PTP layer to
support hardware cross timestamps with a new IOTCL.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195558.097464513@kernel.org
2026-06-04 11:04:18 +02:00
Thomas Gleixner
09fb74f77e timekeeping: Prepare for cross timestamps on arbitrary clock IDs
PTP device system crosstime stamps support only CLOCK_REALTIME, which is
meaningless for AUX clocks. The PTP core hands in the clock ID already, so
prepare the core code to honor it.

 - Add a new sys_systime field to struct system_device_crosststamp which
   aliases the sys_realtime field. Once all users are converted
   sys_realtime can be removed.

 - Prepare get_device_system_crosststamp() and the related code for it by
   switching to sys_systime and providing the initial changes to utilize
   different time keepers.

No functional change intended.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.846634842@kernel.org
2026-06-04 11:04:17 +02:00
Thomas Gleixner
6c14771816 timekeeping: Add system_counterval_t to struct system_device_crosststamp
An upcoming extension to the PTP IOCTL requires to return the system counter
value and the clocksource ID to user space. get_device_system_crosststamp() has
this information already.

Extend struct system_device_crosststamp with a system_counterval_t member
and fill in the data.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.429406675@kernel.org
2026-06-04 11:04:16 +02:00
Thomas Gleixner
23c1bfa9f8 timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id()
Now that all users are converted it's possible to enable snapshotting of
CLOCK_AUX time. The underlying clocksource is the same as for all other
CLOCK variants.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.380601005@kernel.org
2026-06-04 11:04:16 +02:00
Thomas Gleixner
705e106807 timekeeping: Remove system_time_snapshot::real/boot/raw
All users are converted over to ktime_get_snapshot_id() and
system_time_snapshot::systime and ::monoraw.

Remove the leftovers.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.330029635@kernel.org
2026-06-04 11:04:16 +02:00
Thomas Gleixner
ef22786707 timekeeping: Use system_time_snapshot::systime/monoraw instead of ::real/raw
system_time_snapshot::systime provides the same information as
system_time_snapshot::real when the snapshot was taken with
ktime_get_snapshot_id(CLOCK_REALTIME).

Convert the history interpolation over to use 'systime' and 'monoraw' as
'real/raw' are going away once all users are converted.

As a side effect this is the first step to support CLOCK_AUX with
get_device_crosstime_stamp() and the history interpolation.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.024415766@kernel.org
2026-06-02 11:39:57 +02:00
Thomas Gleixner
eba302268a timekeeping: Provide ktime_get_snapshot_id()
ktime_get_snapshot() provides a snapshot of the underlying clocksource
counter value and the corresponding CLOCK_MONOTONIC_RAW, CLOCK_REALTIME and
CLOCK_BOOTTIME timestamps.

There is no usage of CLOCK_REALTIME and CLOCK_BOOTTIME at the same time and
CLOCK_BOOTTIME support was just added for the ARM64 KVM tracing mechanism,
which needs CLOCK_BOOTTIME and the underlying clocksource counter value.

ktime_get_snapshot() is also not suitable for usage with CLOCK_AUX, but
that's a prerequisite to support PTP hardware timestamping for CLOCK_AUX
steering.

As a first step, rename ktime_get_snapshot() to ktime_get_snapshot_id(),
which now takes a clockid argument to select the clock which needs to be
captured. The result is stored in system_time_snapshot::systime, which will
replace the system_time_snapshot::real/boot members once all usage sites
have been converted.

ktime_get_snapshot() is a simple wrapper which hands in CLOCK_REALTIME as
clockid argument for the conversion period. That means CLOCK_REALTIME is
now captured twice, but that redunancy is only temporary.

As all usage sites of struct system_time_snapshot has to be updated anyway,
rename the 'raw' member to 'monoraw' for clarity.

No functional change vs. current users of ktime_get_snapshot()

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195556.971591633@kernel.org
2026-06-02 11:39:57 +02:00
Ingo Molnar
f6472b1793 Merge tag 'v7.0-rc4' into timers/core, to resolve conflict
Resolve conflict between this change in the upstream kernel:

  4c652a4772 ("rseq: Mark rseq_arm_slice_extension_timer() __always_inline")

... and this pending change in timers/core:

  0e98eb1481 ("entry: Prepare for deferred hrtimer rearming")

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2026-03-21 08:02:36 +01:00
Thomas Weißschuh (Schneider Electric)
112c685f02 timekeeping: Mark offsets array as const
Neither the array nor the offsets it is pointing to are meant to be
changed through the array.

Mark both the array and the values it points to as const.

Signed-off-by: Thomas Weißschuh (Schneider Electric) <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260311-hrtimer-cleanups-v1-5-095357392669@linutronix.de
2026-03-12 12:15:54 +01:00
Thomas Weißschuh (Schneider Electric)
ba546d3d89 timekeeping/auxclock: Consistently use raw timekeeper for tk_setup_internals()
In aux_clock_enable() the clocksource from tkr_raw is used to call
tk_setup_internals(). Do the same in tk_aux_update_clocksource().  While
the clocksources will be the same in any case, this is less confusing.

Signed-off-by: Thomas Weißschuh (Schneider Electric) <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260311-hrtimer-cleanups-v1-4-095357392669@linutronix.de
2026-03-12 12:15:54 +01:00
Thomas Gleixner
9d5e25b361 timekeeping: Initialize the coupled clocksource conversion completely
Nathan reported a boot failure after the coupled clocksource/event support
was enabled for the TSC deadline timer. It turns out that on the affected
test systems the TSC frequency is not refined against HPET, so it is
registered with the same frequency as the TSC-early clocksource.

As a consequence the update function which checks for a change of the
shift/mult pair of the clocksource fails to compute the conversion
limit, which is zero initialized. This check is there to avoid pointless
computations on every timekeeping update cycle (tick).

So the actual clockevent conversion function limits the delta expiry to
zero, which means the timer is always programmed to expire in the
past. This obviously results in a spectacular timer interrupt storm,
which goes unnoticed because the per CPU interrupts on x86 are not
exposed to the runaway detection mechanism and the NMI watchdog is not
yet functional. So the machine simply stops booting.

That did not show up in testing. All test machines refine the TSC frequency
so TSC has a differrent shift/mult pair than TSC-early and the conversion
limit is properly initialized.

Cure that by setting the conversion limit right at the point where the new
clocksource is installed.

Fixes: cd38bdb8e6 ("timekeeping: Provide infrastructure for coupled clockevents")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/87bjh4zies.ffs@tglx
Closes: https://lore.kernel.org/20260303012905.GA978396@ax162
2026-03-05 17:40:46 +01:00
Miroslav Lichvar
e48a869957 timekeeping: Fix timex status validation for auxiliary clocks
The timekeeping_validate_timex() function validates the timex status
of an auxiliary system clock even when the status is not to be changed,
which causes unexpected errors for applications that make read-only
clock_adjtime() calls, or set some other timex fields, but without
clearing the status field.

Do the AUX-specific status validation only when the modes field contains
ADJ_STATUS, i.e. the application is actually trying to change the
status. This makes the AUX-specific clock_adjtime() behavior consistent
with CLOCK_REALTIME.

Fixes: 4eca49d0b6 ("timekeeping: Prepare do_adtimex() for auxiliary clocks")
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260225085231.276751-1-mlichvar@redhat.com
2026-03-04 20:05:37 +01:00
Thomas Gleixner
cd38bdb8e6 timekeeping: Provide infrastructure for coupled clockevents
Some architectures have clockevent devices which are coupled to the system
clocksource by implementing a less than or equal comparator which compares
the programmed absolute expiry time against the underlying time
counter. Well known examples are TSC/TSC deadline timer and the S390 TOD
clocksource/comparator.

While the concept is nice it has some downsides:

  1) The clockevents core code is strictly based on relative expiry times
     as that's the most common case for clockevent device hardware. That
     requires to convert the absolute expiry time provided by the caller
     (hrtimers, NOHZ code) to a relative expiry time by reading and
     substracting the current time.

     The clockevent::set_next_event() callback must then read the counter
     again to convert the relative expiry back into a absolute one.

  2) The conversion factors from nanoseconds to counter clock cycles are
     set up when the clockevent is registered. When NTP applies corrections
     then the clockevent conversion factors can deviate from the
     clocksource conversion substantially which either results in timers
     firing late or in the worst case early. The early expiry then needs to
     do a reprogam with a short delta.

     In most cases this is papered over by the fact that the read in the
     set_next_event() callback happens after the read which is used to
     calculate the delta. So the tendency is that timers expire mostly
     late.

All of this can be avoided by providing support for these devices in the
core code:

  1) The timekeeping core keeps track of the last update to the clocksource
     by storing the base nanoseconds and the corresponding clocksource
     counter value. That's used to keep the conversion math for reading the
     time within 64-bit in the common case.

     This information can be used to avoid both reads of the underlying
     clocksource in the clockevents reprogramming path:

     delta = expiry - base_ns;
     cycles = base_cycles + ((delta * clockevent::mult) >> clockevent::shift);

     The resulting cycles value can be directly used to program the
     comparator.

  2) As #1 does not longer provide the "compensation" through the second
     read the deviation of the clocksource and clockevent conversions
     caused by NTP become more prominent.

     This can be cured by letting the timekeeping core compute and store
     the reverse conversion factors when the clocksource cycles to
     nanoseconds factors are modified by NTP:

         CS::MULT      (1 << NS_TO_CYC_SHIFT)
     --------------- = ----------------------
     (1 << CS:SHIFT)       NS_TO_CYC_MULT

     Ergo: NS_TO_CYC_MULT = (1 << (CS::SHIFT + NS_TO_CYC_SHIFT)) / CS::MULT

     The NS_TO_CYC_SHIFT value is calculated when the clocksource is
     installed so that it aims for a one hour maximum sleep time.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.944763521@kernel.org
2026-02-27 16:40:08 +01:00
Thomas Gleixner
2e27beeb66 timekeeping: Allow inlining clocksource::read()
On some architectures clocksource::read() boils down to a single
instruction, so the indirect function call is just a massive overhead
especially with speculative execution mitigations in effect.

Allow architectures to enable conditional inlining of that read to avoid
that by:

   - providing a static branch to switch to the inlined variant

   - disabling the branch before clocksource changes

   - enabling the branch after a clocksource change, when the clocksource
     indicates in a feature flag that it is the one which provides the
     inlined variant

This is intentionally not a static call as that would only remove the
indirect call, but not the rest of the overhead.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.675151545@kernel.org
2026-02-27 16:40:07 +01:00
Thomas Weißschuh
e806f7dde8 timekeeping: Adjust the leap state for the correct auxiliary timekeeper
When __do_ajdtimex() was introduced to handle adjtimex for any
timekeeper, this reference to tk_core was not updated. When called on an
auxiliary timekeeper, the core timekeeper would be updated incorrectly.

This gets caught by the lock debugging diagnostics because the
timekeepers sequence lock gets written to without holding its
associated spinlock:

WARNING: include/linux/seqlock.h:226 at __do_adjtimex+0x394/0x3b0, CPU#2: test/125
aux_clock_adj (kernel/time/timekeeping.c:2979)
__do_sys_clock_adjtime (kernel/time/posix-timers.c:1161 kernel/time/posix-timers.c:1173)
do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:131)

Update the correct auxiliary timekeeper.

Fixes: 775f71ebed ("timekeeping: Make do_adjtimex() reusable")
Fixes: ecf3e70304 ("timekeeping: Provide adjtimex() for auxiliary clocks")
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260120-timekeeper-auxclock-leapstate-v1-1-5b358c6b3cfd@linutronix.de
2026-01-20 10:18:53 +01:00
Linus Torvalds
208eed95fc Merge tag 'soc-drivers-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc
Pull SoC driver updates from Arnd Bergmann:
 "This is the first half of the driver changes:

   - A treewide interface change to the "syscore" operations for power
     management, as a preparation for future Tegra specific changes

   - Reset controller updates with added drivers for LAN969x, eic770 and
     RZ/G3S SoCs

   - Protection of system controller registers on Renesas and Google
     SoCs, to prevent trivially triggering a system crash from e.g.
     debugfs access

   - soc_device identification updates on Nvidia, Exynos and Mediatek

   - debugfs support in the ST STM32 firewall driver

   - Minor updates for SoC drivers on AMD/Xilinx, Renesas, Allwinner, TI

   - Cleanups for memory controller support on Nvidia and Renesas"

* tag 'soc-drivers-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (114 commits)
  memory: tegra186-emc: Fix missing put_bpmp
  Documentation: reset: Remove reset_controller_add_lookup()
  reset: fix BIT macro reference
  reset: rzg2l-usbphy-ctrl: Fix a NULL vs IS_ERR() bug in probe
  reset: th1520: Support reset controllers in more subsystems
  reset: th1520: Prepare for supporting multiple controllers
  dt-bindings: reset: thead,th1520-reset: Add controllers for more subsys
  dt-bindings: reset: thead,th1520-reset: Remove non-VO-subsystem resets
  reset: remove legacy reset lookup code
  clk: davinci: psc: drop unused reset lookup
  reset: rzg2l-usbphy-ctrl: Add support for RZ/G3S SoC
  reset: rzg2l-usbphy-ctrl: Add support for USB PWRRDY
  dt-bindings: reset: renesas,rzg2l-usbphy-ctrl: Document RZ/G3S support
  reset: eswin: Add eic7700 reset driver
  dt-bindings: reset: eswin: Documentation for eic7700 SoC
  reset: sparx5: add LAN969x support
  dt-bindings: reset: microchip: Add LAN969x support
  soc: rockchip: grf: Add select correct PWM implementation on RK3368
  soc/tegra: pmc: Add USB wake events for Tegra234
  amba: tegra-ahb: Fix device leak on SMMU enable
  ...
2025-12-05 17:29:04 -08:00
Dan Carpenter
c7418164b4 timekeeping: Fix error code in tk_aux_sysfs_init()
If kobject_create_and_add() fails on the first iteration, then the error
code is set to -ENOMEM which is correct. But if it fails in subsequent
iterations then "ret" is zero, which means success, but it should be
-ENOMEM.

Set the error code to -ENOMEM correctly.

Fixes: 7b5ab04f03 ("timekeeping: Fix resource leak in tk_aux_sysfs_init() error paths")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Malaya Kumar Rout <mrout@redhat.com>
Link: https://patch.msgid.link/aSW1R8q5zoY_DgQE@stanley.mountain
2025-11-25 17:52:24 +01:00
Malaya Kumar Rout
7b5ab04f03 timekeeping: Fix resource leak in tk_aux_sysfs_init() error paths
tk_aux_sysfs_init() returns immediately on error during the auxiliary clock
initialization loop without cleaning up previously allocated kobjects and
sysfs groups.

If kobject_create_and_add() or sysfs_create_group() fails during loop
iteration, the parent kobjects (tko and auxo) and any previously created
child kobjects are leaked.

Fix this by adding proper error handling with goto labels to ensure all
allocated resources are cleaned up on failure. kobject_put() on the
parent kobjects will handle cleanup of their children.

Fixes: 7b95663a3d ("timekeeping: Provide interface to control auxiliary clocks")
Signed-off-by: Malaya Kumar Rout <mrout@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/20251120150213.246777-1-mrout@redhat.com
2025-11-20 16:40:48 +01:00
Thierry Reding
a97fbc3ee3 syscore: Pass context data to callbacks
Several drivers can benefit from registering per-instance data along
with the syscore operations. To achieve this, move the modifiable fields
out of the syscore_ops structure and into a separate struct syscore that
can be registered with the framework. Add a void * driver data field for
drivers to store contextual data that will be passed to the syscore ops.

Acked-by: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
2025-11-14 10:01:52 +01:00
Haofeng Li
39a9ed0fb6 timekeeping: Fix aux clocks sysfs initialization loop bound
The loop in tk_aux_sysfs_init() uses `i <= MAX_AUX_CLOCKS` as the
termination condition, which results in 9 iterations (i=0 to 8) when
MAX_AUX_CLOCKS is defined as 8. However, the kernel is designed to support
only up to 8 auxiliary clocks.

This off-by-one error causes the creation of a 9th sysfs entry that exceeds
the intended auxiliary clock range.

Fix the loop bound to use `i < MAX_AUX_CLOCKS` to ensure exactly 8
auxiliary clock entries are created, matching the design specification.

Fixes: 7b95663a3d ("timekeeping: Provide interface to control auxiliary clocks")
Signed-off-by: Haofeng Li <lihaofeng@kylinos.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://patch.msgid.link/tencent_2376993D9FC06A3616A4F981B3DE1C599607@qq.com
2025-10-20 19:56:12 +02:00
Thomas Weißschuh
762af5a2aa vdso/vsyscall: Avoid slow division loop in auxiliary clock update
The call to __iter_div_u64_rem() in vdso_time_update_aux() is a wrapper
around subtraction. It cannot be used to divide large numbers, as that
introduces long, computationally expensive delays.  A regular u64 division
is also not possible in the timekeeper update path as it can be too slow.

Instead of splitting the ktime_t offset into into second and subsecond
components during the timekeeper update fast-path, do it together with the
adjustment of tk->offs_aux in the slow-path. Equivalent to the handling of
offs_boot and monotonic_to_boot.

Reuse the storage of monotonic_to_boot for the new field, as it is not used
by auxiliary timekeepers.

Fixes: 380b84e168 ("vdso/vsyscall: Update auxiliary clock data in the datapage")
Reported-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250825-vdso-auxclock-division-v1-1-a1d32a16a313@linutronix.de
Closes: https://lore.kernel.org/lkml/aKwsNNWsHJg8IKzj@localhost/
2025-09-03 11:55:11 +02:00
Linus Torvalds
02dc9d15d7 Merge tag 'timers-ptp-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timekeeping and VDSO updates from Thomas Gleixner:

 - Introduce support for auxiliary timekeepers

   PTP clocks can be disconnected from the universal CLOCK_TAI reality
   for various reasons including regularatory requirements for
   functional safety redundancy.

   The kernel so far only supports a single notion of time, which means
   that all clocks are correlated in frequency and only differ by offset
   to each other.

   Access to non-correlated PTP clocks has been available so far only
   through the file descriptor based "POSIX clock IDs", which are
   subject to locking and have to go all the way out to the hardware.

   The access is not only horribly slow, as it has to go all the way out
   to the NIC/PTP hardware, but that also prevents the kernel to read
   the time of such clocks e.g. from the network stack, where it is
   required for TSN networking both on the transmit and receive side
   unless the hardware provides offloading.

   The auxiliary clocks provide a mechanism to support arbitrary clocks
   which are not correlated to the system clock. This is not restricted
   to the PTP use case on purpose as there is no kernel side association
   of these clocks to a particular PTP device because that's a pure user
   space configuration decision. Having them independent allows to
   utilize them for other purposes and also enables them to be tested
   without hardware dependencies.

   To avoid pointless overhead these clocks have to be enabled
   individualy via a new sysfs interface to reduce the overhead to a
   single compare in the hotpath if they are enabled at the Kconfig
   level at all.

   These clocks utilize the existing timekeeping/NTP infrastructures,
   which has been made possible over the recent releases by incrementaly
   converting these infrastructures over from a single static instance
   to a multi-instance pointer based implementation without any
   performance regression reported.

   The auxiliary clocks provide the same "emulation" of a "correct"
   clock as the existing CLOCK_* variants do with an independent
   instance of data and provide the same steering mechanism through the
   existing sys_clock_adjtime() interface, which has been confirmed to
   work by the chronyd(8) maintainer.

   That allows to provide lockless kernel internal and VDSO support so
   that applications and kernel internal functionalities can access
   these clocks without restrictions and at the same performance as the
   existing system clocks.

 - Avoid double notifications in the adjtimex() syscall. Not a big
   issue, but a trivial to avoid latency source.

* tag 'timers-ptp-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
  vdso/gettimeofday: Add support for auxiliary clocks
  vdso/vsyscall: Update auxiliary clock data in the datapage
  vdso: Introduce aux_clock_resolution_ns()
  vdso/gettimeofday: Introduce vdso_get_timestamp()
  vdso/gettimeofday: Introduce vdso_set_timespec()
  vdso/gettimeofday: Introduce vdso_clockid_valid()
  vdso/gettimeofday: Return bool from clock_gettime() helpers
  vdso/gettimeofday: Return bool from clock_getres() helpers
  vdso/helpers: Add helpers for seqlocks of single vdso_clock
  vdso/vsyscall: Split up __arch_update_vsyscall() into __arch_update_vdso_clock()
  vdso/vsyscall: Introduce a helper to fill clock configurations
  timekeeping: Remove the temporary CLOCK_AUX workaround
  timekeeping: Provide ktime_get_clock_ts64()
  timekeeping: Provide interface to control auxiliary clocks
  timekeeping: Provide update for auxiliary timekeepers
  timekeeping: Provide adjtimex() for auxiliary clocks
  timekeeping: Prepare do_adtimex() for auxiliary clocks
  timekeeping: Make do_adjtimex() reusable
  timekeeping: Add auxiliary clock support to __timekeeping_inject_offset()
  timekeeping: Make timekeeping_inject_offset() reusable
  ...
2025-07-29 14:12:52 -07:00
Markus Blöchl
67c632b4a7 timekeeping: Zero initialize system_counterval when querying time from phc drivers
Most drivers only populate the fields cycles and cs_id of system_counterval
in their get_time_fn() callback for get_device_system_crosststamp(), unless
they explicitly provide nanosecond values.

When the use_nsecs field was added to struct system_counterval, most
drivers did not care.  Clock sources other than CSID_GENERIC could then get
converted in convert_base_to_cs() based on an uninitialized use_nsecs field,
which usually results in -EINVAL during the following range check.

Pass in a fully zero initialized system_counterval_t to cure that.

Fixes: 6b2e299775 ("timekeeping: Provide infrastructure for converting to/from a base clock")
Signed-off-by: Markus Blöchl <markus@blochl.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250720-timekeeping_uninit_crossts-v2-1-f513c885b7c2@blochl.de
2025-07-22 14:25:21 +02:00
Thomas Weißschuh
380b84e168 vdso/vsyscall: Update auxiliary clock data in the datapage
Expose the auxiliary clock data so it can be read from the vDSO.

Architectures not using the generic vDSO time framework,
namely SPARC64, are not supported.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-11-df7d9f87b9b8@linutronix.de
2025-07-18 13:45:33 +02:00
Thomas Weißschuh
9b7fc3f145 vdso: Introduce aux_clock_resolution_ns()
Move the constant resolution to a shared header,
so the vDSO can use it and return it without going through a syscall.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701-vdso-auxclock-v1-10-df7d9f87b9b8@linutronix.de
2025-07-18 13:45:32 +02:00
Thomas Gleixner
a6d9638d4d Merge tag 'ktime-get-clock-ts64-for-ptp' into timers/ptp
Pull the base implementation of ktime_get_clock_ts64() for PTP, which
contains a temporary CLOCK_AUX* workaround. That was created to allow
integration of depending changes into the networking tree. The workaround
is going to be removed in a subsequent change in the timekeeping tree.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2025-07-03 14:35:53 +02:00
Thomas Gleixner
5b605dbee0 timekeeping: Provide ktime_get_clock_ts64()
PTP implements an inline switch case for taking timestamps from various
POSIX clock IDs, which already consumes quite some text space. Expanding it
for auxiliary clocks really becomes too big for inlining.

Provide a out of line version. 

The function invalidates the timestamp in case the clock is invalid. The
invalidation allows to implement a validation check without the need to
propagate a return value through deep existing call chains.

Due to merge logistics this temporarily defines CLOCK_AUX[_LAST] if
undefined, so that the plain branch, which does not contain any of the core
timekeeper changes, can be pulled into the networking tree as prerequisite
for the PTP side changes. These temporary defines are removed after that
branch is merged into the tip::timers/ptp branch. That way the result in
-next or upstream in the next merge window has zero dependencies.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250701132628.357686408@linutronix.de
2025-07-03 14:18:06 +02:00
Thomas Gleixner
7b95663a3d timekeeping: Provide interface to control auxiliary clocks
Auxiliary clocks are disabled by default and attempts to access them
fail.

Provide an interface to enable/disable them at run-time.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.444626478@linutronix.de
2025-06-27 20:13:13 +02:00
Thomas Gleixner
e6d4c00719 timekeeping: Provide update for auxiliary timekeepers
Update the auxiliary timekeepers periodically. For now this is tied to the system
timekeeper update from the tick. This might be revisited and moved out of the tick.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.382451331@linutronix.de
2025-06-27 20:13:13 +02:00
Thomas Gleixner
ecf3e70304 timekeeping: Provide adjtimex() for auxiliary clocks
The behaviour is close to clock_adtime(CLOCK_REALTIME) with the
following differences:

  1) ADJ_SETOFFSET adjusts the auxiliary clock offset
  
  2) ADJ_TAI is not supported

  3) Leap seconds are not supported

  4) PPS is not supported

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.317946543@linutronix.de
2025-06-27 20:13:13 +02:00
Thomas Gleixner
4eca49d0b6 timekeeping: Prepare do_adtimex() for auxiliary clocks
Exclude ADJ_TAI, leap seconds and PPS functionality as they make no sense
in the context of auxiliary clocks and provide a time stamp based on the
actual clock.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.253203783@linutronix.de
2025-06-27 20:13:13 +02:00
Thomas Gleixner
775f71ebed timekeeping: Make do_adjtimex() reusable
Split out the actual functionality of adjtimex() and make do_adjtimex() a
wrapper which feeds the core timekeeper into it and handles the result
including audit at the call site.

This allows to reuse the actual functionality for auxiliary clocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.187322876@linutronix.de
2025-06-27 20:13:13 +02:00
Thomas Gleixner
2c8aea59c2 timekeeping: Add auxiliary clock support to __timekeeping_inject_offset()
Redirect the relative offset adjustment to the auxiliary clock offset
instead of modifying CLOCK_REALTIME, which has no meaning in context of
these clocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.124057787@linutronix.de
2025-06-27 20:13:13 +02:00
Thomas Gleixner
e8db3a5579 timekeeping: Make timekeeping_inject_offset() reusable
Split out the inner workings for auxiliary clock support and feed the core time
keeper into it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183758.059934561@linutronix.de
2025-06-27 20:13:13 +02:00
Thomas Gleixner
60ecc26ec5 timekeeping: Provide time setter for auxiliary clocks
Add clock_settime(2) support for auxiliary clocks. The function affects the
AUX offset which is added to the "monotonic" clock readout of these clocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.995688714@linutronix.de
2025-06-27 20:13:12 +02:00
Thomas Gleixner
606424bf4f timekeeping: Add minimal posix-timers support for auxiliary clocks
Provide clock_getres(2) and clock_gettime(2) for auxiliary clocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.932220594@linutronix.de
2025-06-27 20:13:12 +02:00
Thomas Gleixner
05bc6e6290 timekeeping: Provide time getters for auxiliary clocks
Provide interfaces similar to the ktime_get*() family which provide access
to the auxiliary clocks.

These interfaces have a boolean return value, which indicates whether the
accessed clock is valid or not.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.868342628@linutronix.de
2025-06-27 20:13:12 +02:00
Thomas Gleixner
9f7729480a timekeeping: Update auxiliary timekeepers on clocksource change
Propagate a system clocksource change to the auxiliary timekeepers so that
they can pick up the new clocksource.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.803890875@linutronix.de
2025-06-27 20:13:12 +02:00
Thomas Gleixner
ffa0519baa timekeeping: Provide ktime_get_ntp_seconds()
ntp_adjtimex() requires access to the actual time keeper per timekeeper
ID. Provide an interface.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250519083026.411809421@linutronix.de
2025-06-19 14:28:23 +02:00
Anna-Maria Behnsen
22c62b9a84 timekeeping: Introduce auxiliary timekeepers
Provide timekeepers for auxiliary clocks and initialize them during
boot.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083026.350061049@linutronix.de
2025-06-19 14:28:23 +02:00
Thomas Gleixner
6168024604 timekeeping: Add clock_valid flag to timekeeper
In preparation for supporting independent auxiliary timekeepers, add a
clock valid field and set it to true for the system timekeeper.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083026.287145536@linutronix.de
2025-06-19 14:28:23 +02:00
Thomas Gleixner
8c782acd3f timekeeping: Prepare timekeeping_update_from_shadow()
Don't invoke the VDSO and paravirt updates when utilized for auxiliary
clocks. This is a temporary workaround until the VDSO and paravirt
interfaces have been worked out.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250519083026.223876435@linutronix.de
2025-06-19 14:28:23 +02:00
Anna-Maria Behnsen
926ad47516 timekeeping: Make __timekeeping_advance() reusable
In __timekeeping_advance() the pointer to struct tk_data is hardcoded by the
use of &tk_core. As long as there is only a single timekeeper (tk_core),
this is not a problem. But when __timekeeping_advance() will be reused for
per auxiliary timekeepers, __timekeeping_advance() needs to be generalized.

Add a pointer to struct tk_data as function argument of
__timekeeping_advance() and adapt all call sites.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083026.160967312@linutronix.de
2025-06-19 14:28:23 +02:00
Thomas Gleixner
c7ebfbc440 ntp: Rename __do_adjtimex() to ntp_adjtimex()
Clean up the name space. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083026.095637820@linutronix.de
2025-06-19 14:28:23 +02:00
Thomas Gleixner
5ffa25f573 ntp: Add timekeeper ID arguments to public functions
In preparation for supporting auxiliary POSIX clocks, add a timekeeper ID
to the relevant functions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083026.032425931@linutronix.de
2025-06-19 14:28:23 +02:00
Anna-Maria Behnsen
f12b45862c timekeeping: Introduce timekeeper ID
As long as there is only a single timekeeper, there is no need to clarify
which timekeeper is used. But with the upcoming reusage of the timekeeper
infrastructure for auxiliary clock timekeepers, an ID is required to
differentiate.

Introduce an enum for timekeeper IDs, introduce a field in struct tk_data
to store this timekeeper id and add also initialization. The id struct
field is added at the end of the second cachline, as there is a 4 byte hole
anyway.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083025.842476378@linutronix.de
2025-06-19 14:28:22 +02:00
Thomas Gleixner
7e55b6ba1f timekeeping: Avoid double notification in do_adjtimex()
Consolidate do_adjtimex() so that it does not notify about clock changes
twice.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250519083025.779267274@linutronix.de
2025-06-19 14:28:22 +02:00
Thomas Gleixner
506a54a031 timekeeping: Cleanup kernel doc of __ktime_get_real_seconds()
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083025.715836017@linutronix.de
2025-06-19 14:28:22 +02:00
Thomas Gleixner
990518eb3a timekeeping: Remove hardcoded access to tk_core
This was overlooked in the initial conversion. Use the provided pointer to
access the shadow timekeeper.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250519083025.652611452@linutronix.de
2025-06-19 14:28:22 +02:00