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Subject[PATCH v10 09/25] arm64: Unmask PMR before going idle
Date
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: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/process.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
arch/arm64/mm/proc.S | 11 -----------
2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 6d410fc..3767fb2 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 @@

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.
*/
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 73886a5..3ea4f3b 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -55,17 +55,6 @@

#define MAIR(attr, mt) ((attr) << ((mt) * 8))

-/*
- * cpu_do_idle()
- *
- * Idle the processor (wait for interrupt).
- */
-ENTRY(cpu_do_idle)
- dsb sy // WFI may enter a low-power mode
- wfi
- ret
-ENDPROC(cpu_do_idle)
-
#ifdef CONFIG_CPU_PM
/**
* cpu_do_suspend - save CPU registers context
--
1.9.1
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