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From: Catalin Marinas <catalin.marinas@arm.com>
To: Julien Thierry <julien.thierry@arm.com>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, peterz@infradead.org,
	will.deacon@arm.com, mingo@redhat.com, james.morse@arm.com,
	hpa@zytor.com
Subject: Re: [PATCH v2 2/2] arm64: uaccess: Implement unsafe accessors
Date: Thu, 6 Dec 2018 18:25:52 +0000	[thread overview]
Message-ID: <20181206182551.GB37411@arrakis.emea.arm.com> (raw)
In-Reply-To: <1543845318-24543-3-git-send-email-julien.thierry@arm.com>

On Mon, Dec 03, 2018 at 01:55:18PM +0000, Julien Thierry wrote:
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 07c3408..cabfcae 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -233,6 +233,23 @@ static inline void uaccess_enable_not_uao(void)
>  	__uaccess_enable(ARM64_ALT_PAN_NOT_UAO);
>  }
>  
> +#define unsafe_user_region_active	uaccess_region_active
> +static inline bool uaccess_region_active(void)
> +{
> +	if (system_uses_ttbr0_pan()) {
> +		u64 ttbr;
> +
> +		ttbr = read_sysreg(ttbr1_el1);
> +		return ttbr & TTBR_ASID_MASK;

Nitpick: could write this in 1-2 lines.

> +	} else if (cpus_have_const_cap(ARM64_ALT_PAN_NOT_UAO)) {
> +		return (read_sysreg(sctlr_el1) & SCTLR_EL1_SPAN) ?
> +				false :
> +				!read_sysreg_s(SYS_PSTATE_PAN);
> +	}

ARM64_ALT_PAN_NOT_UAO implies ARM64_HAS_PAN which implies SCTLR_EL1.SPAN
is 0 at run-time. Is this to cope with the case of being called prior to
cpu_enable_pan()?

-- 
Catalin

  reply	other threads:[~2018-12-06 18:25 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-03 13:55 [PATCH v2 0/2] uaccess: Add unsafe accessors for arm64 Julien Thierry
2018-12-03 13:55 ` [RFC PATCH v2 1/2] uaccess: Check no rescheduling function is called in unsafe region Julien Thierry
2019-01-14 12:03   ` Valentin Schneider
2019-01-15 11:48     ` Julien Thierry
2018-12-03 13:55 ` [PATCH v2 2/2] arm64: uaccess: Implement unsafe accessors Julien Thierry
2018-12-06 18:25   ` Catalin Marinas [this message]
2018-12-07  8:38     ` Julien Thierry
2018-12-10 14:59       ` Catalin Marinas
2018-12-12 17:40         ` Suzuki K Poulose
2018-12-21 14:57         ` James Morse
2018-12-21 14:57   ` James Morse

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