linux-kernel - Re: [PATCH v4 1/5] ARM/ARM64: arch_timer: add macros for bits in control register

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Message-ID: <20130827112144.GG19897@arm.com>
Date:	Tue, 27 Aug 2013 12:21:44 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Will Deacon <Will.Deacon@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Daniel Lezcano <daniel.lezcano@...aro.org>
Subject: Re: [PATCH v4 1/5] ARM/ARM64: arch_timer: add macros for bits in
 control register

On Fri, Aug 23, 2013 at 05:19:05PM +0100, Sudeep KarkadaNagesha wrote:
> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
> 
> Add macros to describe the bitfields in the ARM architected timer
> control register to make code easy to understand.
> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Reviewed-by: Will Deacon <will.deacon@....com>
> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
> ---
>  arch/arm/include/asm/arch_timer.h    |  9 +++++++--
>  arch/arm64/include/asm/arch_timer.h  | 12 ++++++++----
>  include/clocksource/arm_arch_timer.h |  8 ++++++++
>  3 files changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
> index e406d57..9ef74da 100644
> --- a/arch/arm/include/asm/arch_timer.h
> +++ b/arch/arm/include/asm/arch_timer.h
> @@ -95,8 +95,13 @@ static inline void arch_counter_set_user_access(void)
>  
>  	asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl));
>  
> -	/* disable user access to everything */
> -	cntkctl &= ~((3 << 8) | (7 << 0));
> +	/* Disable user access to both physical/virtual counters/timers. */
> +	/* Also disable virtual event stream */
> +	cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
> +			| ARCH_TIMER_USR_VT_ACCESS_EN
> +			| ARCH_TIMER_VIRT_EVT_EN
> +			| ARCH_TIMER_USR_VCT_ACCESS_EN
> +			| ARCH_TIMER_USR_PCT_ACCESS_EN);
>  
>  	asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
>  }
> diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
> index 98abd47..00b09d0 100644
> --- a/arch/arm64/include/asm/arch_timer.h
> +++ b/arch/arm64/include/asm/arch_timer.h
> @@ -101,12 +101,16 @@ static inline void arch_counter_set_user_access(void)
>  {
>  	u32 cntkctl;
>  
> -	/* Disable user access to the timers and the physical counter. */
>  	asm volatile("mrs	%0, cntkctl_el1" : "=r" (cntkctl));
> -	cntkctl &= ~((3 << 8) | (1 << 0));
>  
> -	/* Enable user access to the virtual counter and frequency. */
> -	cntkctl |= (1 << 1);
> +	/* Disable user access to the timers and the physical counter. */
> +	cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
> +			| ARCH_TIMER_USR_VT_ACCESS_EN
> +			| ARCH_TIMER_USR_PCT_ACCESS_EN);
> +
> +	/* Enable user access to the virtual counter. */
> +	cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
> +
>  	asm volatile("msr	cntkctl_el1, %0" : : "r" (cntkctl));

For consistency with arm, I think we should also disable the event
stream explicitly here.

-- 
Catalin
--
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