[PATCH v3 0/5] ARM: Remaining PREEMPT_RT bits

[Bryan Brattlof]

On November 10, 2025 thus sayeth Sebastian Andrzej Siewior:
> this is the last batch I have to enable PREEMPT_RT on the ARM
> architecture.
> Last time I posted them there was some discussion about making the
> branch predictor hardening worse. I redid it hoping it improved now and
> does not make it worse.
> 
> Is this okay now?
> 
> v2…v3: https://lore.kernel.org/all/20251103101545.760243-1-bigeasy@linutronix.de
>   - Collected tags.
> 
> v1…v2: https://lore.kernel.org/all/20251029155918.503060-1-bigeasy@linutronix.de
>   - Allow to enable jump-labels on UP. The UP build does not involve
>     stop_machine(). Reworked by Arnd.
> 
>   - Instead of forbidding HAVE_GUP_FAST with HIGHPTE enabled just
>     disable HIGHPTE on PREEMPT_RT. As Arnd explained, HIGHPTE is rarely
>     needed.
> 
>   - Don't let ARCH_SUPPORTS_RT depend on HAVE_POSIX_CPU_TIMERS_TASK_WORK
>     which in turn depends on !KVM. Since KVM has been removed from ARM
>     it is sufficient to unconditionally allow ARCH_SUPPORTS_RT. Noted
>     by Arnd.
> 
> Sebastian Andrzej Siewior (3):
>   ARM: mm: fault: Move harden_branch_predictor() before interrupts are
>     enabled
>   ARM: Disable HIGHPTE on PREEMPT_RT kernels
>   ARM: Allow to enable RT
> 
> Thomas Gleixner (1):
>   ARM: Disable jump-label on PREEMPT_RT
> 
> Yadi.hu (1):
>   ARM: mm: fault: Enable interrupts before invoking __do_user_fault()
> 
>  arch/arm/Kconfig    |  5 +++--
>  arch/arm/mm/fault.c | 16 ++++++++++------
>  2 files changed, 13 insertions(+), 8 deletions(-)

Thank you Sebastian!

There are quite a few systems which use 32b processors and need 
PREEMPT_RT. Thank you for doing this. 

Acked-by: Bryan Brattlof <bb at ti.com>

~Bryan