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