diff mbox series

[PATCHv3,2/3] arm64: entry: refactor EL1 interrupt entry logic

Message ID 20210930131708.35328-3-kernelfans@gmail.com (mailing list archive)
State New, archived
Headers show
Series arm64/irqentry: remove duplicate housekeeping of rcu | expand

Commit Message

Pingfan Liu Sept. 30, 2021, 1:17 p.m. UTC 
From: Mark Rutland <mark.rutland@arm.com>

Currently we distinguish IRQ and definitely-PNMI at entry/exit time
via the enter_el1_irq_or_nmi() and enter_el1_irq_or_nmi() helpers. In
subsequent patches we'll need to handle the two cases more distinctly
in the body of the exception handler.

To make this possible, this patch refactors el1_interrupt to be a
top-level dispatcher to separate handlers for the IRQ and PNMI cases,
removing the need for the enter_el1_irq_or_nmi() and
exit_el1_irq_or_nmi() helpers.

Note that since arm64_enter_nmi() calls __nmi_enter(), which
increments the preemt_count, we could never preempt when handling a
PNMI. We now only check for preemption in the IRQ case, which makes
this clearer.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: linux-kernel@vger.kernel.org
To: linux-arm-kernel@lists.infradead.org
---
 arch/arm64/kernel/entry-common.c | 44 ++++++++++++++++----------------
 1 file changed, 22 insertions(+), 22 deletions(-)

Comments

Mark Rutland Sept. 30, 2021, 2 p.m. UTC | #1 
On Thu, Sep 30, 2021 at 09:17:07PM +0800, Pingfan Liu wrote:
> From: Mark Rutland <mark.rutland@arm.com>
> 
> Currently we distinguish IRQ and definitely-PNMI at entry/exit time
> via the enter_el1_irq_or_nmi() and enter_el1_irq_or_nmi() helpers. In
> subsequent patches we'll need to handle the two cases more distinctly
> in the body of the exception handler.
> 
> To make this possible, this patch refactors el1_interrupt to be a
> top-level dispatcher to separate handlers for the IRQ and PNMI cases,
> removing the need for the enter_el1_irq_or_nmi() and
> exit_el1_irq_or_nmi() helpers.
> 
> Note that since arm64_enter_nmi() calls __nmi_enter(), which
> increments the preemt_count, we could never preempt when handling a
> PNMI. We now only check for preemption in the IRQ case, which makes
> this clearer.
> 
> There should be no functional change as a result of this patch.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: "Paul E. McKenney" <paulmck@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Joey Gouly <joey.gouly@arm.com>
> Cc: Sami Tolvanen <samitolvanen@google.com>
> Cc: Julien Thierry <julien.thierry@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
> Cc: Pingfan Liu <kernelfans@gmail.com>
> Cc: linux-kernel@vger.kernel.org
> To: linux-arm-kernel@lists.infradead.org

As a heads-up, you need to add your Signed-off-by tag when you post
patches from other people, even if you make no changes. See:

https://www.kernel.org/doc/html/v5.14/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin

Other than that, this looks fine to me.

Mark.

> ---
>  arch/arm64/kernel/entry-common.c | 44 ++++++++++++++++----------------
>  1 file changed, 22 insertions(+), 22 deletions(-)
> 
> diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
> index 32f9796c4ffe..5f1473319fb0 100644
> --- a/arch/arm64/kernel/entry-common.c
> +++ b/arch/arm64/kernel/entry-common.c
> @@ -219,22 +219,6 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
>  		lockdep_hardirqs_on(CALLER_ADDR0);
>  }
>  
> -static void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs)
> -{
> -	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> -		arm64_enter_nmi(regs);
> -	else
> -		enter_from_kernel_mode(regs);
> -}
> -
> -static void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
> -{
> -	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> -		arm64_exit_nmi(regs);
> -	else
> -		exit_to_kernel_mode(regs);
> -}
> -
>  static void __sched arm64_preempt_schedule_irq(void)
>  {
>  	lockdep_assert_irqs_disabled();
> @@ -432,14 +416,19 @@ asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
>  	}
>  }
>  
> -static void noinstr el1_interrupt(struct pt_regs *regs,
> -				  void (*handler)(struct pt_regs *))
> +static __always_inline void
> +__el1_pnmi(struct pt_regs *regs, void (*handler)(struct pt_regs *))
>  {
> -	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
> -
> -	enter_el1_irq_or_nmi(regs);
> +	arm64_enter_nmi(regs);
>  	do_interrupt_handler(regs, handler);
> +	arm64_exit_nmi(regs);
> +}
>  
> +static __always_inline void
> +__el1_interrupt(struct pt_regs *regs, void (*handler)(struct pt_regs *))
> +{
> +	enter_from_kernel_mode(regs);
> +	do_interrupt_handler(regs, handler);
>  	/*
>  	 * Note: thread_info::preempt_count includes both thread_info::count
>  	 * and thread_info::need_resched, and is not equivalent to
> @@ -448,8 +437,19 @@ static void noinstr el1_interrupt(struct pt_regs *regs,
>  	if (IS_ENABLED(CONFIG_PREEMPTION) &&
>  	    READ_ONCE(current_thread_info()->preempt_count) == 0)
>  		arm64_preempt_schedule_irq();
> +	exit_to_kernel_mode(regs);
> +}
> +
> +static void noinstr el1_interrupt(struct pt_regs *regs,
> +				  void (*handler)(struct pt_regs *))
> +{
> +	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
> +
> +	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> +		__el1_pnmi(regs, handler);
> +	else
> +		__el1_interrupt(regs, handler);
>  
> -	exit_el1_irq_or_nmi(regs);
>  }
>  
>  asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs)
> -- 
> 2.31.1
>
Pingfan Liu Oct. 1, 2021, 2:27 a.m. UTC | #2 
On Thu, Sep 30, 2021 at 03:00:59PM +0100, Mark Rutland wrote:
> On Thu, Sep 30, 2021 at 09:17:07PM +0800, Pingfan Liu wrote:
> > From: Mark Rutland <mark.rutland@arm.com>
> > 
> > Currently we distinguish IRQ and definitely-PNMI at entry/exit time
> > via the enter_el1_irq_or_nmi() and enter_el1_irq_or_nmi() helpers. In
> > subsequent patches we'll need to handle the two cases more distinctly
> > in the body of the exception handler.
> > 
> > To make this possible, this patch refactors el1_interrupt to be a
> > top-level dispatcher to separate handlers for the IRQ and PNMI cases,
> > removing the need for the enter_el1_irq_or_nmi() and
> > exit_el1_irq_or_nmi() helpers.
> > 
> > Note that since arm64_enter_nmi() calls __nmi_enter(), which
> > increments the preemt_count, we could never preempt when handling a
> > PNMI. We now only check for preemption in the IRQ case, which makes
> > this clearer.
> > 
> > There should be no functional change as a result of this patch.
> > 
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: "Paul E. McKenney" <paulmck@kernel.org>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Joey Gouly <joey.gouly@arm.com>
> > Cc: Sami Tolvanen <samitolvanen@google.com>
> > Cc: Julien Thierry <julien.thierry@arm.com>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
> > Cc: Pingfan Liu <kernelfans@gmail.com>
> > Cc: linux-kernel@vger.kernel.org
> > To: linux-arm-kernel@lists.infradead.org
> 
> As a heads-up, you need to add your Signed-off-by tag when you post
> patches from other people, even if you make no changes. See:
> 
> https://www.kernel.org/doc/html/v5.14/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin
> 
Oh, thanks and I realize it is a serious license issue. 

> Other than that, this looks fine to me.
> 
Thank you very much.


Regards,

	Pingfan
Marc Zyngier Oct. 1, 2021, 9:21 a.m. UTC | #3 
On Thu, 30 Sep 2021 14:17:07 +0100,
Pingfan Liu <kernelfans@gmail.com> wrote:
> 
> From: Mark Rutland <mark.rutland@arm.com>
> 
> Currently we distinguish IRQ and definitely-PNMI at entry/exit time
> via the enter_el1_irq_or_nmi() and enter_el1_irq_or_nmi() helpers. In
> subsequent patches we'll need to handle the two cases more distinctly
> in the body of the exception handler.
> 
> To make this possible, this patch refactors el1_interrupt to be a
> top-level dispatcher to separate handlers for the IRQ and PNMI cases,
> removing the need for the enter_el1_irq_or_nmi() and
> exit_el1_irq_or_nmi() helpers.
> 
> Note that since arm64_enter_nmi() calls __nmi_enter(), which
> increments the preemt_count, we could never preempt when handling a
> PNMI. We now only check for preemption in the IRQ case, which makes
> this clearer.
> 
> There should be no functional change as a result of this patch.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: "Paul E. McKenney" <paulmck@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Joey Gouly <joey.gouly@arm.com>
> Cc: Sami Tolvanen <samitolvanen@google.com>
> Cc: Julien Thierry <julien.thierry@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
> Cc: Pingfan Liu <kernelfans@gmail.com>
> Cc: linux-kernel@vger.kernel.org
> To: linux-arm-kernel@lists.infradead.org
> ---
>  arch/arm64/kernel/entry-common.c | 44 ++++++++++++++++----------------
>  1 file changed, 22 insertions(+), 22 deletions(-)
> 
> diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
> index 32f9796c4ffe..5f1473319fb0 100644
> --- a/arch/arm64/kernel/entry-common.c
> +++ b/arch/arm64/kernel/entry-common.c
> @@ -219,22 +219,6 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
>  		lockdep_hardirqs_on(CALLER_ADDR0);
>  }
>  
> -static void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs)
> -{
> -	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> -		arm64_enter_nmi(regs);
> -	else
> -		enter_from_kernel_mode(regs);
> -}
> -
> -static void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
> -{
> -	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> -		arm64_exit_nmi(regs);
> -	else
> -		exit_to_kernel_mode(regs);
> -}
> -
>  static void __sched arm64_preempt_schedule_irq(void)
>  {
>  	lockdep_assert_irqs_disabled();
> @@ -432,14 +416,19 @@ asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
>  	}
>  }
>  
> -static void noinstr el1_interrupt(struct pt_regs *regs,
> -				  void (*handler)(struct pt_regs *))
> +static __always_inline void
> +__el1_pnmi(struct pt_regs *regs, void (*handler)(struct pt_regs *))
>  {
> -	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
> -
> -	enter_el1_irq_or_nmi(regs);
> +	arm64_enter_nmi(regs);
>  	do_interrupt_handler(regs, handler);
> +	arm64_exit_nmi(regs);
> +}
>  
> +static __always_inline void
> +__el1_interrupt(struct pt_regs *regs, void (*handler)(struct pt_regs *))
> +{
> +	enter_from_kernel_mode(regs);
> +	do_interrupt_handler(regs, handler);
>  	/*
>  	 * Note: thread_info::preempt_count includes both thread_info::count
>  	 * and thread_info::need_resched, and is not equivalent to
> @@ -448,8 +437,19 @@ static void noinstr el1_interrupt(struct pt_regs *regs,
>  	if (IS_ENABLED(CONFIG_PREEMPTION) &&
>  	    READ_ONCE(current_thread_info()->preempt_count) == 0)
>  		arm64_preempt_schedule_irq();
> +	exit_to_kernel_mode(regs);
> +}
> +
> +static void noinstr el1_interrupt(struct pt_regs *regs,
> +				  void (*handler)(struct pt_regs *))
> +{
> +	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
> +
> +	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> +		__el1_pnmi(regs, handler);
> +	else
> +		__el1_interrupt(regs, handler);
>  
> -	exit_el1_irq_or_nmi(regs);

nit: spurious blank line.

>  }
>  
>  asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs)

With Mark's remark addressed,

Reviewed-by: Marc Zyngier <maz@kernel.org>

	M.
Pingfan Liu Oct. 1, 2021, 2:12 p.m. UTC | #4 
On Fri, Oct 01, 2021 at 10:21:06AM +0100, Marc Zyngier wrote:
> On Thu, 30 Sep 2021 14:17:07 +0100,
> Pingfan Liu <kernelfans@gmail.com> wrote:
> > 
> > From: Mark Rutland <mark.rutland@arm.com>
> > 
> > Currently we distinguish IRQ and definitely-PNMI at entry/exit time
> > via the enter_el1_irq_or_nmi() and enter_el1_irq_or_nmi() helpers. In
> > subsequent patches we'll need to handle the two cases more distinctly
> > in the body of the exception handler.
> > 
> > To make this possible, this patch refactors el1_interrupt to be a
> > top-level dispatcher to separate handlers for the IRQ and PNMI cases,
> > removing the need for the enter_el1_irq_or_nmi() and
> > exit_el1_irq_or_nmi() helpers.
> > 
> > Note that since arm64_enter_nmi() calls __nmi_enter(), which
> > increments the preemt_count, we could never preempt when handling a
> > PNMI. We now only check for preemption in the IRQ case, which makes
> > this clearer.
> > 
> > There should be no functional change as a result of this patch.
> > 
> > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > Cc: "Paul E. McKenney" <paulmck@kernel.org>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: Joey Gouly <joey.gouly@arm.com>
> > Cc: Sami Tolvanen <samitolvanen@google.com>
> > Cc: Julien Thierry <julien.thierry@arm.com>
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Cc: Yuichi Ito <ito-yuichi@fujitsu.com>
> > Cc: Pingfan Liu <kernelfans@gmail.com>
> > Cc: linux-kernel@vger.kernel.org
> > To: linux-arm-kernel@lists.infradead.org
> > ---
> >  arch/arm64/kernel/entry-common.c | 44 ++++++++++++++++----------------
> >  1 file changed, 22 insertions(+), 22 deletions(-)
> > 
> > diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
> > index 32f9796c4ffe..5f1473319fb0 100644
> > --- a/arch/arm64/kernel/entry-common.c
> > +++ b/arch/arm64/kernel/entry-common.c
> > @@ -219,22 +219,6 @@ static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
> >  		lockdep_hardirqs_on(CALLER_ADDR0);
> >  }
> >  
> > -static void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs)
> > -{
> > -	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> > -		arm64_enter_nmi(regs);
> > -	else
> > -		enter_from_kernel_mode(regs);
> > -}
> > -
> > -static void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
> > -{
> > -	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> > -		arm64_exit_nmi(regs);
> > -	else
> > -		exit_to_kernel_mode(regs);
> > -}
> > -
> >  static void __sched arm64_preempt_schedule_irq(void)
> >  {
> >  	lockdep_assert_irqs_disabled();
> > @@ -432,14 +416,19 @@ asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
> >  	}
> >  }
> >  
> > -static void noinstr el1_interrupt(struct pt_regs *regs,
> > -				  void (*handler)(struct pt_regs *))
> > +static __always_inline void
> > +__el1_pnmi(struct pt_regs *regs, void (*handler)(struct pt_regs *))
> >  {
> > -	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
> > -
> > -	enter_el1_irq_or_nmi(regs);
> > +	arm64_enter_nmi(regs);
> >  	do_interrupt_handler(regs, handler);
> > +	arm64_exit_nmi(regs);
> > +}
> >  
> > +static __always_inline void
> > +__el1_interrupt(struct pt_regs *regs, void (*handler)(struct pt_regs *))
> > +{
> > +	enter_from_kernel_mode(regs);
> > +	do_interrupt_handler(regs, handler);
> >  	/*
> >  	 * Note: thread_info::preempt_count includes both thread_info::count
> >  	 * and thread_info::need_resched, and is not equivalent to
> > @@ -448,8 +437,19 @@ static void noinstr el1_interrupt(struct pt_regs *regs,
> >  	if (IS_ENABLED(CONFIG_PREEMPTION) &&
> >  	    READ_ONCE(current_thread_info()->preempt_count) == 0)
> >  		arm64_preempt_schedule_irq();
> > +	exit_to_kernel_mode(regs);
> > +}
> > +
> > +static void noinstr el1_interrupt(struct pt_regs *regs,
> > +				  void (*handler)(struct pt_regs *))
> > +{
> > +	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
> > +
> > +	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
> > +		__el1_pnmi(regs, handler);
> > +	else
> > +		__el1_interrupt(regs, handler);
> >  
> > -	exit_el1_irq_or_nmi(regs);
> 
> nit: spurious blank line.
> 
OK, I will fix it.

> >  }
> >  
> >  asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs)
> 
> With Mark's remark addressed,
> 
> Reviewed-by: Marc Zyngier <maz@kernel.org>
> 
Thanks,

	Pingfan
diff mbox series

Patch

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 32f9796c4ffe..5f1473319fb0 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -219,22 +219,6 @@  static void noinstr arm64_exit_el1_dbg(struct pt_regs *regs)
 		lockdep_hardirqs_on(CALLER_ADDR0);
 }
 
-static void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs)
-{
-	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
-		arm64_enter_nmi(regs);
-	else
-		enter_from_kernel_mode(regs);
-}
-
-static void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs)
-{
-	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
-		arm64_exit_nmi(regs);
-	else
-		exit_to_kernel_mode(regs);
-}
-
 static void __sched arm64_preempt_schedule_irq(void)
 {
 	lockdep_assert_irqs_disabled();
@@ -432,14 +416,19 @@  asmlinkage void noinstr el1h_64_sync_handler(struct pt_regs *regs)
 	}
 }
 
-static void noinstr el1_interrupt(struct pt_regs *regs,
-				  void (*handler)(struct pt_regs *))
+static __always_inline void
+__el1_pnmi(struct pt_regs *regs, void (*handler)(struct pt_regs *))
 {
-	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
-
-	enter_el1_irq_or_nmi(regs);
+	arm64_enter_nmi(regs);
 	do_interrupt_handler(regs, handler);
+	arm64_exit_nmi(regs);
+}
 
+static __always_inline void
+__el1_interrupt(struct pt_regs *regs, void (*handler)(struct pt_regs *))
+{
+	enter_from_kernel_mode(regs);
+	do_interrupt_handler(regs, handler);
 	/*
 	 * Note: thread_info::preempt_count includes both thread_info::count
 	 * and thread_info::need_resched, and is not equivalent to
@@ -448,8 +437,19 @@  static void noinstr el1_interrupt(struct pt_regs *regs,
 	if (IS_ENABLED(CONFIG_PREEMPTION) &&
 	    READ_ONCE(current_thread_info()->preempt_count) == 0)
 		arm64_preempt_schedule_irq();
+	exit_to_kernel_mode(regs);
+}
+
+static void noinstr el1_interrupt(struct pt_regs *regs,
+				  void (*handler)(struct pt_regs *))
+{
+	write_sysreg(DAIF_PROCCTX_NOIRQ, daif);
+
+	if (IS_ENABLED(CONFIG_ARM64_PSEUDO_NMI) && !interrupts_enabled(regs))
+		__el1_pnmi(regs, handler);
+	else
+		__el1_interrupt(regs, handler);
 
-	exit_el1_irq_or_nmi(regs);
 }
 
 asmlinkage void noinstr el1h_64_irq_handler(struct pt_regs *regs)