[PATCH v3 06/20] arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN

Yisheng Xie xieyisheng1 at huawei.com
Tue Jan 16 18:58:23 PST 2018


Hi Will,

On 2017/12/6 20:35, Will Deacon wrote:
>  config ARM64_SW_TTBR0_PAN
>  	bool "Emulate Privileged Access Never using TTBR0_EL1 switching"
> -	depends on BROKEN       # Temporary while switch_mm is reworked
>  	help
>  	  Enabling this option prevents the kernel from accessing
>  	  user-space memory directly by pointing TTBR0_EL1 to a reserved

I have a question not related to this patch itself, but to ARM64_SW_TTBR0_PAN:

What does ARM64_SW_TTBR0_PAN used for? I means is hardware support PAN, do we
still need SW_TTBR0_PAN?

And if the hardware do not support PAN, is SW_TTBR0_PAN is *must* option? or
there maybe a security risk?

Thanks
Yisheng Xie




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