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From: Catalin Marinas <catalin.marinas@arm.com>
To: Joey Gouly <joey.gouly@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, nd@arm.com,
	broonie@kernel.org, james.morse@arm.com, mark.rutland@arm.com,
	maz@kernel.org, oliver.upton@linux.dev, suzuki.poulose@arm.com,
	will@kernel.org, yuzenghui@huawei.com
Subject: Re: [PATCH v1 12/18] arm64: add PTE_UXN/PTE_WRITE to SWAPPER_*_FLAGS
Date: Mon, 27 Mar 2023 17:44:37 +0100	[thread overview]
Message-ID: <ZCHH9YW53of6/nQA@arm.com> (raw)
In-Reply-To: <20230309145246.22787-13-joey.gouly@arm.com>

On Thu, Mar 09, 2023 at 02:52:40PM +0000, Joey Gouly wrote:
> With PIE enabled, the swapper PTEs would have a Permission Indirection Index (PIIndex)
> of 0. A PIIndex of 0 is not currently used by any other PTEs.
> 
> To avoid using index 0 specifically for the swapper PTEs, mark them as PTE_UXN
> and PTE_WRITE, so that they map to a PAGE_KERNEL_EXEC equivalent.
> 
> Signed-off-by: Joey Gouly <joey.gouly@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> ---
>  arch/arm64/include/asm/kernel-pgtable.h | 4 ++--
>  arch/arm64/kernel/head.S                | 8 ++++----
>  arch/arm64/mm/proc.S                    | 2 +-
>  3 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
> index fcd14197756f..daf1909116f6 100644
> --- a/arch/arm64/include/asm/kernel-pgtable.h
> +++ b/arch/arm64/include/asm/kernel-pgtable.h
> @@ -104,8 +104,8 @@
>  /*
>   * Initial memory map attributes.
>   */
> -#define SWAPPER_PTE_FLAGS	(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
> -#define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
> +#define SWAPPER_PTE_FLAGS	(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED | PTE_UXN | PTE_WRITE)
> +#define SWAPPER_PMD_FLAGS	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S | PTE_UXN | PTE_WRITE)

Adding PTE_UXN is fine but we have SWAPPER_RX_MMUFLAGS which is no
longer read-only after this change. I don't think this matters much as
IIUC we only use init_pg_dir briefly before creating the proper
swapper_pg_dir.

-- 
Catalin

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  reply	other threads:[~2023-03-27 16:45 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-09 14:52 [PATCH v1 00/18] Permission Indirection Extension Joey Gouly
2023-03-09 14:52 ` [PATCH v1 01/18] arm64/sysreg: Add ID register ID_AA64MMFR3 Joey Gouly
2023-03-09 15:06   ` Mark Brown
2023-03-09 14:52 ` [PATCH v1 02/18] arm64/sysreg: add system registers TCR2_ELx Joey Gouly
2023-03-09 15:16   ` Mark Brown
2023-03-09 14:52 ` [PATCH v1 03/18] arm64/sysreg: add TCR2En to HCRX_EL2 Joey Gouly
2023-03-09 15:23   ` Mark Brown
2023-03-09 14:52 ` [PATCH v1 04/18] arm64/sysreg: add HFGxTR_EL2 bits for Permission Indirection Extension Joey Gouly
2023-03-09 15:25   ` Mark Brown
2023-03-09 14:52 ` [PATCH v1 05/18] arm64/sysreg: add PIR*_ELx registers Joey Gouly
2023-03-09 15:35   ` Mark Brown
2023-03-16 17:23   ` Mark Brown
2023-03-27 12:22     ` Catalin Marinas
2023-04-11 12:48       ` Mark Brown
2023-03-09 14:52 ` [PATCH v1 06/18] arm64: cpufeature: add system register ID_AA64MMFR3 Joey Gouly
2023-03-27 12:23   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 07/18] arm64: cpufeature: add TCR2 cpucap Joey Gouly
2023-03-27 12:58   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 08/18] arm64: cpufeature: add Permission Indirection Extension cpucap Joey Gouly
2023-03-27 13:07   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 09/18] KVM: arm64: Save/restore TCR2_EL1 Joey Gouly
2023-03-27 13:19   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 10/18] KVM: arm64: Save/restore PIE registers Joey Gouly
2023-03-27 13:20   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 11/18] KVM: arm64: expose ID_AA64MMFR3_EL1 to guests Joey Gouly
2023-03-09 16:07   ` Mark Brown
2023-03-09 16:24     ` Marc Zyngier
2023-03-09 17:04       ` Mark Brown
2023-03-10 12:29         ` Marc Zyngier
2023-03-09 16:34     ` Mark Brown
2023-03-09 14:52 ` [PATCH v1 12/18] arm64: add PTE_UXN/PTE_WRITE to SWAPPER_*_FLAGS Joey Gouly
2023-03-27 16:44   ` Catalin Marinas [this message]
2023-03-09 14:52 ` [PATCH v1 13/18] arm64: add PTE_WRITE to PROT_SECT_NORMAL Joey Gouly
2023-03-27 16:47   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 14/18] arm64: reorganise PAGE_/PROT_ macros Joey Gouly
2023-03-27 16:51   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 15/18] arm64: disable EL2 traps for PIE Joey Gouly
2023-03-09 15:50   ` Mark Brown
2023-03-09 16:27   ` Suzuki K Poulose
2023-03-09 16:38     ` Mark Brown
2023-03-27 16:59   ` Catalin Marinas
2023-03-28 10:34     ` Joey Gouly
2023-03-31 15:15       ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 16/18] arm64: add encodings of PIRx_ELx registers Joey Gouly
2023-03-27 17:07   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 17/18] arm64: enable Permission Indirection Extension (PIE) Joey Gouly
2023-03-27 17:07   ` Catalin Marinas
2023-03-09 14:52 ` [PATCH v1 18/18] arm64: transfer permission indirection settings to EL2 Joey Gouly
2023-03-27 17:08   ` Catalin Marinas
2023-03-17 16:49 ` [PATCH v1 00/18] Permission Indirection Extension Mark Brown

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