On Mon, 21 Jan 2019 at 16:36, Julien Thierry <[email protected]> wrote:
>
> 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 <[email protected]>
> Suggested-by: Daniel Thompson <[email protected]>
> Cc: Catalin Marinas <[email protected]>
> Cc: Will Deacon <[email protected]>
> ---
> 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)
Can we drop the 'inline's from all the function definitions in .c
files? (not just in this patch)
We tend to leave that to the compiler.
> +{
> + 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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