wireguard-linux/kernel/time/timekeeping.c, branch jd/bump-compilers

timekeeping: Fix bogus clock_was_set() invocation in do_adjtimex()

2024-08-05T14:14:14Z

The addition of the bases argument to clock_was_set() fixed up all call sites correctly except for do_adjtimex(). This uses CLOCK_REALTIME instead of CLOCK_SET_WALL as argument. CLOCK_REALTIME is 0. As a result the effect of that clock_was_set() notification is incomplete and might result in timers expiring late because the hrtimer code does not re-evaluate the affected clock bases. Use CLOCK_SET_WALL instead of CLOCK_REALTIME to tell the hrtimers code which clock bases need to be re-evaluated. Fixes: 17a1b8826b45 ("hrtimer: Add bases argument to clock_was_set()") Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/877ccx7igo.ffs@tglx

timekeeping: Add missing kernel-doc function comments

2024-06-23T17:57:30Z

Fixup the incomplete kernel-doc style comments for do_adjtimex() and hardpps() by documenting the function parameters. Reported-by: Abaci Robot Signed-off-by: Yang Li Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240607090656.104883-1-yang.lee@linux.alibaba.com Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=9301

timekeeping: Add function to convert realtime to base clock

2024-06-03T09:18:51Z

PPS (Pulse Per Second) generates a hardware pulse every second based on CLOCK_REALTIME. This works fine when the pulse is generated in software from a hrtimer callback function. For hardware which generates the pulse by programming a timer it is required to convert CLOCK_REALTIME to the underlying hardware clock. The X86 Timed IO device is based on the Always Running Timer (ART), which is the base clock of the TSC, which is usually the system clocksource on X86. The core code already has functionality to convert base clock timestamps to system clocksource timestamps, but there is no support for converting the other way around. Provide the required functionality to support such devices in a generic way to avoid code duplication in drivers: 1) ktime_real_to_base_clock() to convert a CLOCK_REALTIME timestamp to a base clock timestamp 2) timekeeping_clocksource_has_base() to allow drivers to validate that the system clocksource is based on a particular clocksource ID. [ tglx: Simplify timekeeping_clocksource_has_base() and add missing READ_ONCE() ] Co-developed-by: Thomas Gleixner Signed-off-by: Thomas Gleixner Co-developed-by: Christopher S. Hall Signed-off-by: Christopher S. Hall Signed-off-by: Lakshmi Sowjanya D Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240513103813.5666-10-lakshmi.sowjanya.d@intel.com

timekeeping: Provide infrastructure for converting to/from a base clock

2024-06-03T09:18:50Z

Hardware time stamps like provided by PTP clock implementations are based on a clock which feeds both the PCIe device and the system clock. For further processing the underlying hardwarre clock timestamp must be converted to the system clock. Right now this requires drivers to invoke an architecture specific conversion function, e.g. to convert the ART (Always Running Timer) timestamp to a TSC timestamp. As the system clock is aware of the underlying base clock, this can be moved to the core code by providing a base clock property for the system clock which contains the conversion factors and assigning a clocksource ID to the base clock. Add the required data structures and the conversion infrastructure in the core code to prepare for converting X86 and the related PTP drivers over. [ tglx: Added a missing READ_ONCE(). Massaged change log ] Co-developed-by: Thomas Gleixner Signed-off-by: Thomas Gleixner Co-developed-by: Christopher S. Hall Signed-off-by: Christopher S. Hall Signed-off-by: Lakshmi Sowjanya D Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240513103813.5666-2-lakshmi.sowjanya.d@intel.com

timekeeping: Let timekeeping_cycles_to_ns() handle both under and overflow

2024-04-08T13:03:08Z

For the case !CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE, forego overflow protection in the range (mask << 1) < delta <= mask, and interpret it always as an inconsistency between CPU clock values. That allows slightly neater code, and it is on a slow path so has no effect on performance. Suggested-by: Thomas Gleixner Signed-off-by: Adrian Hunter Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240325064023.2997-19-adrian.hunter@intel.com

timekeeping: Make delta calculation overflow safe

2024-04-08T13:03:08Z

Kernel timekeeping is designed to keep the change in cycles (since the last timer interrupt) below max_cycles, which prevents multiplication overflow when converting cycles to nanoseconds. However, if timer interrupts stop, the calculation will eventually overflow. Add protection against that. In timekeeping_cycles_to_ns() calculation, check against max_cycles, falling back to a slower higher precision calculation. In timekeeping_forward_now(), process delta in chunks of at most max_cycles. Suggested-by: Thomas Gleixner Signed-off-by: Adrian Hunter Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240325064023.2997-18-adrian.hunter@intel.com

timekeeping: Prepare timekeeping_cycles_to_ns() for overflow safety

2024-04-08T13:03:08Z

Open code clocksource_delta() in timekeeping_cycles_to_ns() so that overflow safety can be added efficiently. Suggested-by: Thomas Gleixner Signed-off-by: Adrian Hunter Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240325064023.2997-17-adrian.hunter@intel.com

timekeeping: Fold in timekeeping_delta_to_ns()

2024-04-08T13:03:08Z

timekeeping_delta_to_ns() is now called only from timekeeping_cycles_to_ns(), and it is not useful otherwise. Simplify the code by folding it into timekeeping_cycles_to_ns(). No functional change. Suggested-by: Thomas Gleixner Signed-off-by: Adrian Hunter Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240325064023.2997-16-adrian.hunter@intel.com

timekeeping: Consolidate timekeeping helpers

2024-04-08T13:03:08Z

Consolidate timekeeping helpers, making use of timekeeping_cycles_to_ns() in preference to directly using timekeeping_delta_to_ns(). No functional change. Suggested-by: Thomas Gleixner Signed-off-by: Adrian Hunter Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240325064023.2997-15-adrian.hunter@intel.com

timekeeping: Refactor timekeeping helpers

2024-04-08T13:03:08Z

Simplify the usage of timekeeping sanity checking, in preparation for consolidating timekeeping helpers. This works towards eliminating timekeeping_delta_to_ns() in favour of timekeeping_cycles_to_ns(). No functional change. Suggested-by: Thomas Gleixner Signed-off-by: Adrian Hunter Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240325064023.2997-14-adrian.hunter@intel.com