linux-kernel - Re: [PATCH 13/15] irq: riscv: perform irqentry in entry code

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Date:   Fri, 22 Oct 2021 09:59:56 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Albert Ou <aou@...s.berkeley.edu>,
        Catalin Marinas <catalin.marinas@....com>,
        Vincent Chen <deanbo422@...il.com>,
        Greentime Hu <green.hu@...il.com>,
        Jonas Bonn <jonas@...thpole.se>, kernelfans@...il.com,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Russell King <linux@...linux.org.uk>,
        Marc Zyngier <maz@...nel.org>, Nick Hu <nickhu@...estech.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul McKenney <paulmck@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Stafford Horne <shorne@...il.com>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        vgupta@...nel.org, Will Deacon <will@...nel.org>
Subject: Re: [PATCH 13/15] irq: riscv: perform irqentry in entry code

Reviewed-by: Guo Ren <guoren@...nel.org>

On Fri, Oct 22, 2021 at 2:03 AM Mark Rutland <mark.rutland@....com> wrote:
>
> In preparation for removing HANDLE_DOMAIN_IRQ_IRQENTRY, have arch/riscv
> perform all the irqentry accounting in its entry code. As arch/riscv
> uses GENERIC_IRQ_MULTI_HANDLER, we can use generic_handle_arch_irq() to
> do so.
>
> Since generic_handle_arch_irq() handles the irq entry and setting the
> irq regs, and happens before the irqchip code calls handle_IPI(), we can
> remove the redundant irq entry and irq regs manipulation from
> handle_IPI().
>
> There should be no functional change as a result of this patch.
>
> Signed-off-by: Mark Rutland <mark.rutland@....com>
> Cc: Albert Ou <aou@...s.berkeley.edu>
> Cc: Marc Zyngier <maz@...nel.org>
> Cc: Palmer Dabbelt <palmer@...belt.com>
> Cc: Paul Walmsley <paul.walmsley@...ive.com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/riscv/Kconfig        | 1 -
>  arch/riscv/kernel/entry.S | 3 +--
>  arch/riscv/kernel/smp.c   | 9 +--------
>  3 files changed, 2 insertions(+), 11 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 740653063a56..301a54233c7e 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -63,7 +63,6 @@ config RISCV
>         select GENERIC_SMP_IDLE_THREAD
>         select GENERIC_TIME_VSYSCALL if MMU && 64BIT
>         select HANDLE_DOMAIN_IRQ
> -       select HANDLE_DOMAIN_IRQ_IRQENTRY
>         select HAVE_ARCH_AUDITSYSCALL
>         select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
>         select HAVE_ARCH_JUMP_LABEL_RELATIVE if !XIP_KERNEL
> diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
> index 98f502654edd..64236f7efde5 100644
> --- a/arch/riscv/kernel/entry.S
> +++ b/arch/riscv/kernel/entry.S
> @@ -130,8 +130,7 @@ skip_context_tracking:
>
>         /* Handle interrupts */
>         move a0, sp /* pt_regs */
> -       la a1, handle_arch_irq
> -       REG_L a1, (a1)
> +       la a1, generic_handle_arch_irq
>         jr a1
>  1:
>         /*
> diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
> index 921d9d7df400..2f6da845c9ae 100644
> --- a/arch/riscv/kernel/smp.c
> +++ b/arch/riscv/kernel/smp.c
> @@ -140,12 +140,9 @@ void arch_irq_work_raise(void)
>
>  void handle_IPI(struct pt_regs *regs)
>  {
> -       struct pt_regs *old_regs = set_irq_regs(regs);
>         unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
>         unsigned long *stats = ipi_data[smp_processor_id()].stats;
>
> -       irq_enter();
> -
>         riscv_clear_ipi();
>
>         while (true) {
> @@ -156,7 +153,7 @@ void handle_IPI(struct pt_regs *regs)
>
>                 ops = xchg(pending_ipis, 0);
>                 if (ops == 0)
> -                       goto done;
> +                       return;
>
>                 if (ops & (1 << IPI_RESCHEDULE)) {
>                         stats[IPI_RESCHEDULE]++;
> @@ -189,10 +186,6 @@ void handle_IPI(struct pt_regs *regs)
>                 /* Order data access and bit testing. */
>                 mb();
>         }
> -
> -done:
> -       irq_exit();
> -       set_irq_regs(old_regs);
>  }
>
>  static const char * const ipi_names[] = {
> --
> 2.11.0
>


-- 
Best Regards
 Guo Ren

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