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From:   Guo Ren <guoren@kernel.org>
Date:   Fri, 22 Oct 2021 10:33:53 +0800
Message-ID: <CAJF2gTShTh5be3SxaVwAzbXTb=LZi-qfweXBvyLeg9TyKgfLNg@mail.gmail.com>
Subject: Re: [PATCH 05/15] irq: add generic_handle_arch_irq()
To:     Mark Rutland <mark.rutland@arm.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Vincent Chen <deanbo422@gmail.com>,
        Greentime Hu <green.hu@gmail.com>,
        Jonas Bonn <jonas@southpole.se>, kernelfans@gmail.com,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Russell King <linux@armlinux.org.uk>,
        Marc Zyngier <maz@kernel.org>, Nick Hu <nickhu@andestech.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul McKenney <paulmck@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Stafford Horne <shorne@gmail.com>,
        Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        vgupta@kernel.org, Will Deacon <will@kernel.org>
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On Fri, Oct 22, 2021 at 2:03 AM Mark Rutland <mark.rutland@arm.com> wrote:
>
> Several architectures select GENERIC_IRQ_MULTI_HANDLER and branch to
> handle_arch_irq() without performing any entry accounting.
>
> Add a generic wrapper to handle the commoon irqentry work when invoking
> handle_arch_irq(). Where an architecture needs to perform some entry
> accounting itself, it will need to invoke handle_arch_irq() itself.
>
> In subsequent patches it will become the responsibilty of the entry code
> to set the irq regs when entering an IRQ (rather than deferring this to
> an irqchip handler), so generic_handle_arch_irq() is made to set the irq
> regs now. This can be redundant in some cases, but is never harmful as
> saving/restoring the old regs nests safely.
Shall we remove old_regs save/restore in handle_domain_irq? It's duplicated.

>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> ---
>  kernel/irq/handle.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>
> diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
> index 221d80c31e94..27182003b879 100644
> --- a/kernel/irq/handle.c
> +++ b/kernel/irq/handle.c
> @@ -14,6 +14,8 @@
>  #include <linux/interrupt.h>
>  #include <linux/kernel_stat.h>
>
> +#include <asm/irq_regs.h>
> +
>  #include <trace/events/irq.h>
>
>  #include "internals.h"
> @@ -226,4 +228,20 @@ int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
>         handle_arch_irq = handle_irq;
>         return 0;
>  }
> +
> +/**
> + * generic_handle_arch_irq - root irq handler for architectures which do no
> + *                           entry accounting themselves
> + * @regs:      Register file coming from the low-level handling code
> + */
> +asmlinkage void noinstr generic_handle_arch_irq(struct pt_regs *regs)
> +{
> +       struct pt_regs *old_regs;
> +
> +       irq_enter();
> +       old_regs = set_irq_regs(regs);
> +       handle_arch_irq(regs);
> +       set_irq_regs(old_regs);
> +       irq_exit();
> +}
>  #endif
> --
> 2.11.0
>


-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/