linux-kernel - [PATCH 05/15] irq: add generic_handle_arch

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Date:   Thu, 21 Oct 2021 19:02:26 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org
Cc:     aou@...s.berkeley.edu, catalin.marinas@....com,
        deanbo422@...il.com, green.hu@...il.com, guoren@...nel.org,
        jonas@...thpole.se, kernelfans@...il.com,
        linux-arm-kernel@...ts.infradead.org, linux@...linux.org.uk,
        mark.rutland@....com, maz@...nel.org, nickhu@...estech.com,
        palmer@...belt.com, paulmck@...nel.org, paul.walmsley@...ive.com,
        peterz@...radead.org, shorne@...il.com,
        stefan.kristiansson@...nalahti.fi, tglx@...utronix.de,
        torvalds@...ux-foundation.org, tsbogend@...ha.franken.de,
        vgupta@...nel.org, will@...nel.org
Subject: [PATCH 05/15] irq: add generic_handle_arch_irq()

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.

Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Marc Zyngier <maz@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.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