linux-kernel - Re: [PATCH 3/7] arm64: Use arch_timer_read_counter instead of arch_counter_get

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Message-ID: <20190408155951.GO6139@lakrids.cambridge.arm.com>
Date:   Mon, 8 Apr 2019 16:59:51 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Russell King <linux@....linux.org.uk>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Valentin Schneider <valentin.schneider@....com>
Subject: Re: [PATCH 3/7] arm64: Use arch_timer_read_counter instead of
 arch_counter_get_cntvct

On Mon, Apr 08, 2019 at 04:49:03PM +0100, Marc Zyngier wrote:
> Only arch_timer_read_counter will guarantee that workarounds are
> applied. So let's use this one instead of arch_counter_get_cntvct.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>

Acked-by: Mark Rutland <mark.rutland@....com>

Mark.

> ---
>  arch/arm64/kernel/traps.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 8ad119c3f665..6190a60388cf 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -493,7 +493,7 @@ static void cntvct_read_handler(unsigned int esr, struct pt_regs *regs)
>  {
>  	int rt = ESR_ELx_SYS64_ISS_RT(esr);
>  
> -	pt_regs_write_reg(regs, rt, arch_counter_get_cntvct());
> +	pt_regs_write_reg(regs, rt, arch_timer_read_counter());
>  	arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
>  }
>  
> @@ -665,7 +665,7 @@ static void compat_cntvct_read_handler(unsigned int esr, struct pt_regs *regs)
>  {
>  	int rt = (esr & ESR_ELx_CP15_64_ISS_RT_MASK) >> ESR_ELx_CP15_64_ISS_RT_SHIFT;
>  	int rt2 = (esr & ESR_ELx_CP15_64_ISS_RT2_MASK) >> ESR_ELx_CP15_64_ISS_RT2_SHIFT;
> -	u64 val = arch_counter_get_cntvct();
> +	u64 val = arch_timer_read_counter();
>  
>  	pt_regs_write_reg(regs, rt, lower_32_bits(val));
>  	pt_regs_write_reg(regs, rt2, upper_32_bits(val));
> -- 
> 2.20.1
>