From a9806aa259feb2f6fd582b6342c835a3482fccc6 Mon Sep 17 00:00:00 2001
From: Julien Thierry <julien.thierry@arm.com>
Date: Thu, 31 Jan 2019 14:58:47 +0000
Subject: arm64: Unmask PMR before going idle

CPU does not received signals for interrupts with a priority masked by
ICC_PMR_EL1. This means the CPU might not come back from a WFI
instruction.

Make sure ICC_PMR_EL1 does not mask interrupts when doing a WFI.

Since the logic of cpu_do_idle is becoming a bit more complex than just
two instructions, lets turn it from ASM to C.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/kernel/process.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

(limited to 'arch/arm64/kernel')

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 6d410fc2849b..3767fb21a5b8 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -51,6 +51,7 @@
 #include <linux/thread_info.h>
 
 #include <asm/alternative.h>
+#include <asm/arch_gicv3.h>
 #include <asm/compat.h>
 #include <asm/cacheflush.h>
 #include <asm/exec.h>
@@ -74,6 +75,50 @@ EXPORT_SYMBOL_GPL(pm_power_off);
 
 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
 
+static void __cpu_do_idle(void)
+{
+	dsb(sy);
+	wfi();
+}
+
+static void __cpu_do_idle_irqprio(void)
+{
+	unsigned long pmr;
+	unsigned long daif_bits;
+
+	daif_bits = read_sysreg(daif);
+	write_sysreg(daif_bits | PSR_I_BIT, daif);
+
+	/*
+	 * Unmask PMR before going idle to make sure interrupts can
+	 * be raised.
+	 */
+	pmr = gic_read_pmr();
+	gic_write_pmr(GIC_PRIO_IRQON);
+
+	__cpu_do_idle();
+
+	gic_write_pmr(pmr);
+	write_sysreg(daif_bits, daif);
+}
+
+/*
+ *	cpu_do_idle()
+ *
+ *	Idle the processor (wait for interrupt).
+ *
+ *	If the CPU supports priority masking we must do additional work to
+ *	ensure that interrupts are not masked at the PMR (because the core will
+ *	not wake up if we block the wake up signal in the interrupt controller).
+ */
+void cpu_do_idle(void)
+{
+	if (system_uses_irq_prio_masking())
+		__cpu_do_idle_irqprio();
+	else
+		__cpu_do_idle();
+}
+
 /*
  * This is our default idle handler.
  */
-- 
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