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From: Yisheng Xie <xieyisheng1@huawei.com>
To: Will Deacon <will.deacon@arm.com>,
	<linux-arm-kernel@lists.infradead.org>
Cc: <linux-kernel@vger.kernel.org>, <catalin.marinas@arm.com>,
	<mark.rutland@arm.com>, <ard.biesheuvel@linaro.org>,
	<sboyd@codeaurora.org>, <dave.hansen@linux.intel.com>,
	<keescook@chromium.org>, <msalter@redhat.com>,
	<labbott@redhat.com>, <tglx@linutronix.de>,
	Xiexiuqi <xiexiuqi@huawei.com>
Subject: Re: [PATCH v3 06/20] arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN
Date: Wed, 17 Jan 2018 10:58:23 +0800	[thread overview]
Message-ID: <cddbd896-2a23-1aa2-bbd8-3bc7cf5367e2@huawei.com> (raw)
In-Reply-To: <1512563739-25239-7-git-send-email-will.deacon@arm.com>

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

  reply	other threads:[~2018-01-17  2:58 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-06 12:35 [PATCH v3 00/20] arm64: Unmap the kernel whilst running in userspace (KPTI) Will Deacon
2017-12-06 12:35 ` [PATCH v3 01/20] arm64: mm: Use non-global mappings for kernel space Will Deacon
2017-12-06 12:35 ` [PATCH v3 02/20] arm64: mm: Temporarily disable ARM64_SW_TTBR0_PAN Will Deacon
2017-12-06 12:35 ` [PATCH v3 03/20] arm64: mm: Move ASID from TTBR0 to TTBR1 Will Deacon
2017-12-06 12:35 ` [PATCH v3 04/20] arm64: mm: Remove pre_ttbr0_update_workaround for Falkor erratum #E1003 Will Deacon
2017-12-06 12:35 ` [PATCH v3 05/20] arm64: mm: Rename post_ttbr0_update_workaround Will Deacon
2017-12-06 12:35 ` [PATCH v3 06/20] arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN Will Deacon
2018-01-17  2:58   ` Yisheng Xie [this message]
2017-12-06 12:35 ` [PATCH v3 07/20] arm64: mm: Allocate ASIDs in pairs Will Deacon
2017-12-06 12:35 ` [PATCH v3 08/20] arm64: mm: Add arm64_kernel_unmapped_at_el0 helper Will Deacon
2017-12-06 12:35 ` [PATCH v3 09/20] arm64: mm: Invalidate both kernel and user ASIDs when performing TLBI Will Deacon
2017-12-06 12:35 ` [PATCH v3 10/20] arm64: entry: Add exception trampoline page for exceptions from EL0 Will Deacon
2017-12-06 12:35 ` [PATCH v3 11/20] arm64: mm: Map entry trampoline into trampoline and kernel page tables Will Deacon
2017-12-06 14:32   ` Mark Rutland
2018-01-23  8:28   ` Yisheng Xie
2018-01-23 10:04     ` Will Deacon
2018-01-23 10:43       ` Yisheng Xie
2017-12-06 12:35 ` [PATCH v3 12/20] arm64: entry: Explicitly pass exception level to kernel_ventry macro Will Deacon
2017-12-06 12:35 ` [PATCH v3 13/20] arm64: entry: Hook up entry trampoline to exception vectors Will Deacon
2017-12-06 12:35 ` [PATCH v3 14/20] arm64: erratum: Work around Falkor erratum #E1003 in trampoline code Will Deacon
2017-12-06 12:35 ` [PATCH v3 15/20] arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks Will Deacon
2017-12-06 12:35 ` [PATCH v3 16/20] arm64: entry: Add fake CPU feature for unmapping the kernel at EL0 Will Deacon
2017-12-06 14:11   ` Mark Rutland
2017-12-06 12:35 ` [PATCH v3 17/20] arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 Will Deacon
2017-12-06 12:35 ` [PATCH v3 18/20] perf: arm_spe: Fail device probe when arm64_kernel_unmapped_at_el0() Will Deacon
2017-12-06 13:34   ` Mark Rutland
2017-12-06 12:35 ` [PATCH v3 19/20] arm64: mm: Introduce TTBR_ASID_MASK for getting at the ASID in the TTBR Will Deacon
2017-12-06 14:12   ` Mark Rutland
2017-12-06 12:35 ` [PATCH v3 20/20] arm64: kaslr: Put kernel vectors address in separate data page Will Deacon
2017-12-06 12:59   ` Ard Biesheuvel
2017-12-06 13:27     ` Will Deacon
2017-12-06 14:03       ` Ard Biesheuvel
2017-12-08  0:40 ` [PATCH v3 00/20] arm64: Unmap the kernel whilst running in userspace (KPTI) Laura Abbott
2017-12-11 13:23   ` Will Deacon
2017-12-11 17:59 ` Catalin Marinas
2018-01-04  5:17   ` Florian Fainelli
2018-01-04  6:50     ` Greg Kroah-Hartman
2018-01-04 18:23       ` Florian Fainelli
2018-01-04 23:27         ` Russell King - ARM Linux
2018-01-05 16:06         ` Greg Kroah-Hartman
2018-01-05 16:12           ` Ard Biesheuvel

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