Commit a9806aa2 authored by Julien Thierry's avatar Julien Thierry Committed by Catalin Marinas
Browse files

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: default avatarJulien Thierry <julien.thierry@arm.com>
Suggested-by: default avatarDaniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 133d0518

arch/arm64/kernel/process.c

+45 −0
Original line number Diff line number Diff line
@@ -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.

 */

arch/arm64/mm/proc.S

+0 −11
Original line number Diff line number Diff line
@@ -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

CRA Git | Maintained and supported by SUSTech CRA and CCSE