linux-kernel - Re: [PATCH v9 07/26] arm64: ptrace: Provide definitions for PMR values

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Date:   Mon, 28 Jan 2019 09:37:37 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Julien Thierry <julien.thierry@....com>
Cc:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <daniel.thompson@...aro.org>,
        <joel@...lfernandes.org>, <christoffer.dall@....com>,
        <james.morse@....com>, <catalin.marinas@....com>,
        <will.deacon@....com>, <mark.rutland@....com>,
        Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH v9 07/26] arm64: ptrace: Provide definitions for PMR values

On Mon, 21 Jan 2019 15:33:26 +0000,
Julien Thierry <julien.thierry@....com> wrote:
> 
> Introduce fixed values for PMR that are going to be used to mask and
> unmask interrupts by priority.
> 
> The current priority given to GIC interrupts is 0xa0, so clearing PMR's
> most significant bit is enough to mask interrupts.
> 
> Signed-off-by: Julien Thierry <julien.thierry@....com>
> Suggested-by: Daniel Thompson <daniel.thompson@...aro.org>
> Acked-by: Catalin Marinas <catalin.marinas@....com>
> Cc: Oleg Nesterov <oleg@...hat.com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will.deacon@....com>
> ---
>  arch/arm64/include/asm/ptrace.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
> index fce22c4..05cf913 100644
> --- a/arch/arm64/include/asm/ptrace.h
> +++ b/arch/arm64/include/asm/ptrace.h
> @@ -25,6 +25,18 @@
>  #define CurrentEL_EL1		(1 << 2)
>  #define CurrentEL_EL2		(2 << 2)
>  
> +/*
> + * PMR values used to mask/unmask interrupts.
> + *
> + * GIC priority masking works as follows: if an IRQ's priority is a higher value
> + * than the value held in PMR, that interrupt is masked. A lower value of PMR
> + * means more IRQ priorities are masked.

Nit: It is not the priorities that are masked, but interrupts that
have a priority higher than that of PMR.

> + *
> + * To mask priorities, we clear the most significant bit of PMR.
> + */
> +#define GIC_PRIO_IRQON		0xf0
> +#define GIC_PRIO_IRQOFF		(GIC_PRIO_IRQON & ~0x80)
> +
>  /* Additional SPSR bits not exposed in the UABI */
>  #define PSR_IL_BIT		(1 << 20)
>  
> -- 
> 1.9.1
> 

Otherwise:

Acked-by: Marc Zyngier <marc.zyngier@....com>

	M.

-- 
Jazz is not dead, it just smell funny.