Re: [PATCH v3 7/8] powerpc: Enable IRQ generic entry/exit path.

[Shrikanth Hegde <sshegde@linux.ibm.com>]

On 12/29/25 10:24 AM, Mukesh Kumar Chaurasiya wrote:
> From: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
> 
> Enable the generic IRQ entry/exit infrastructure on PowerPC by selecting
> GENERIC_IRQ_ENTRY and integrating the architecture-specific interrupt
> handlers with the generic entry/exit APIs.
> 
> This change replaces PowerPC’s local interrupt entry/exit handling with
> calls to the generic irqentry_* helpers, aligning the architecture with
> the common kernel entry model. The macros that define interrupt, async,
> and NMI handlers are updated to use irqentry_enter()/irqentry_exit()
> and irqentry_nmi_enter()/irqentry_nmi_exit() where applicable.
> 
> Key updates include:
>   - Select GENERIC_IRQ_ENTRY in Kconfig.
>   - Replace interrupt_enter/exit_prepare() with arch_interrupt_* helpers.
>   - Integrate irqentry_enter()/exit() in standard and async interrupt paths.
>   - Integrate irqentry_nmi_enter()/exit() in NMI handlers.
>   - Remove redundant irq_enter()/irq_exit() calls now handled generically.
>   - Use irqentry_exit_cond_resched() for preemption checks.
>   - Remove unused code.
> 
> This change establishes the necessary wiring for PowerPC to use the
> generic IRQ entry/exit framework while maintaining existing semantics.
> 
> Signed-off-by: Mukesh Kumar Chaurasiya <mchauras@linux.ibm.com>
> ---
>   arch/powerpc/Kconfig                    |   1 +
>   arch/powerpc/include/asm/entry-common.h |  61 +--
>   arch/powerpc/include/asm/interrupt.h    | 484 +++---------------------
>   arch/powerpc/kernel/interrupt.c         |  15 +-
>   4 files changed, 72 insertions(+), 489 deletions(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 9537a61ebae0..398cef868c14 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -207,6 +207,7 @@ config PPC
>   	select GENERIC_GETTIMEOFDAY
>   	select GENERIC_IDLE_POLL_SETUP
>   	select GENERIC_IOREMAP
> +	select GENERIC_IRQ_ENTRY
>   	select GENERIC_IRQ_SHOW
>   	select GENERIC_IRQ_SHOW_LEVEL
>   	select GENERIC_PCI_IOMAP		if PCI

There is no need for GENERIC_IRQ_ENTRY. I don't see a reason why
we need to have both.

Enabling GENERIC_ENTRY which is done in next patch will enable this.
It does the same thing and one less kconfig to worry about.

This would allow some easier code refactoring IMO.

- You can keep adding code to asm/entry-common.h. This will help avoid
   moving to interrupt.h in between.

- You can add another patch as cleanup post GENERIC_ENTRY for
easier review for seccomp/ptrace.

...

- Some more ct_warning in arch/powerpc are probably not necessary
   (can be done post the series too)

- Some more cleanups can be done w.r.t to lockdep and tracing hardirq etc.
   For example in next_interrupt. I think replay soft interrupts will end
   up making irqentry_enter/exit calls which does same or similar thing.
   (can be done post the series too)

- can we move syscall_exit_prepare/ into kernel/syscall.c?
   (can be done post the series too)