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| author | Adrian Hunter <adrian.hunter@intel.com> | 2024-03-25 08:40:21 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2024-04-08 15:03:08 +0200 |
| commit | fcf190c369149c3b04539797cedf28741eb14164 (patch) | |
| tree | 9a2860f6c895ca93b5247686cd47b0617f778f2c /kernel/time/clocksource.c | |
| parent | e809a80aa0bcf802f99407c23fd6be6fd4eb250a (diff) | |
timekeeping: Make delta calculation overflow safe
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 <tglx@linutronix.de>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240325064023.2997-18-adrian.hunter@intel.com
Diffstat (limited to 'kernel/time/clocksource.c')
0 files changed, 0 insertions, 0 deletions