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.thie...@arm.com> Suggested-by: Daniel Thompson <daniel.thomp...@linaro.org> Cc: Catalin Marinas <catalin.mari...@arm.com> Cc: Will Deacon <will.dea...@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..f05b63f 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 inline void __cpu_do_idle(void) +{ + dsb(sy); + wfi(); +} + +static inline 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