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From:   Mark Rutland <mark.rutland@arm.com>
To:     linux-kernel@vger.kernel.org
Cc:     aou@eecs.berkeley.edu, catalin.marinas@arm.com,
        deanbo422@gmail.com, green.hu@gmail.com, guoren@kernel.org,
        jonas@southpole.se, kernelfans@gmail.com,
        linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk,
        mark.rutland@arm.com, maz@kernel.org, nickhu@andestech.com,
        palmer@dabbelt.com, paul.walmsley@sifive.com, shorne@gmail.com,
        stefan.kristiansson@saunalahti.fi, tglx@linutronix.de,
        tsbogend@alpha.franken.de, vgupta@kernel.org,
        vladimir.murzin@arm.com, will@kernel.org
Subject: [PATCH v2 07/17] irq: add generic_handle_arch_irq()
Date:   Tue, 26 Oct 2021 10:24:54 +0100
Message-Id: <20211026092504.27071-8-mark.rutland@arm.com>
In-Reply-To: <20211026092504.27071-1-mark.rutland@arm.com>
References: <20211026092504.27071-1-mark.rutland@arm.com>
Precedence: bulk

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 common 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.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/irq.h |  1 +
 kernel/irq/handle.c | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index c8293c817646..988c225eef2d 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -1261,6 +1261,7 @@ int __init set_handle_irq(void (*handle_irq)(struct pt_regs *));
  * top-level IRQ handler.
  */
 extern void (*handle_arch_irq)(struct pt_regs *) __ro_after_init;
+asmlinkage void generic_handle_arch_irq(struct pt_regs *regs);
 #else
 #ifndef set_handle_irq
 #define set_handle_irq(handle_irq)		\
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