[PATCH 2/3] arm64/irq-gic-v3: make gic_handle_irq() cope with enter_from_kernel_mode()

[Pingfan Liu]

The call to irq_enter() originated from gic_handle_irq() has already
redundant, since arm64 has enter_from_kernel_mode() akin to
irqenter_entry().

So eliminate the call in __handle_domain_irq(). And accordingly
supplement irq_enter_rcu().

Signed-off-by: Pingfan Liu <kernelfans at gmail.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Julien Thierry <julien.thierry at arm.com>
To: linux-arm-kernel at lists.infradead.org
---
 arch/arm64/Kconfig           | 1 +
 drivers/irqchip/irq-gic-v3.c | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a6b5b7ef40ae..84ffed84158f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -201,6 +201,7 @@ config ARM64
 	select SWIOTLB
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
+	select ARCH_HAS_IRQENTRY_ENTER
 	help
 	  ARM 64-bit (AArch64) Linux support.
 
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 16fecc0febe8..a66e0b04e42b 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -654,14 +654,17 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs
 		return;
 	}
 
+	irq_enter_rcu();
 	if (gic_prio_masking_enabled()) {
 		gic_pmr_mask_irqs();
 		gic_arch_enable_irqs();
 	}
 
 	/* Check for special IDs first */
-	if ((irqnr >= 1020 && irqnr <= 1023))
+	if ((irqnr >= 1020 && irqnr <= 1023)) {
+		irq_exit_rcu();
 		return;
+	}
 
 	if (static_branch_likely(&supports_deactivate_key))
 		gic_write_eoir(irqnr);
@@ -672,6 +675,7 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs
 		WARN_ONCE(true, "Unexpected interrupt received!\n");
 		gic_deactivate_unhandled(irqnr);
 	}
+	irq_exit_rcu();
 }
 
 static u32 gic_get_pribits(void)
-- 
2.29.2