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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 v2 11/19] arm64: add PTE_UXN/PTE_WRITE to SWAPPER_*_FLAGS
Date: Fri, 21 Apr 2023 08:52:07 +0100	[thread overview]
Message-ID: <ZEJAp0QMdebtW3Aa@arm.com> (raw)
In-Reply-To: <20230420152917.GA2499095@e124191.cambridge.arm.com>

On Thu, Apr 20, 2023 at 04:29:17PM +0100, Joey Gouly wrote:
> On Thu, Apr 13, 2023 at 05:35:15PM +0100, Catalin Marinas wrote:
> > On Thu, Apr 13, 2023 at 12:05:05PM +0100, 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)
> > 
> > I mentioned on the previous version, I think it's better not to add the
> > PTE_WRITE here but in the users of these macros where writeable is
> > required (e.g. SWAPPER_RX_MMUFLAGS doesn't need PTE_WRITE as it has
> > PTE_RDONLY).
> 
> I didn't ignore the previous comment, I just misunderstood it and thought I
> should leave it as is.

Yeah, sorry, my comment was confusing.

> I've made the change now!

Thanks.

-- 
Catalin

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  reply	other threads:[~2023-04-21  7:53 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-13 11:04 [PATCH v2 00/19] Permission Indirection Extension Joey Gouly
2023-04-13 11:04 ` [PATCH v2 01/19] arm64/sysreg: Add ID register ID_AA64MMFR3 Joey Gouly
2023-04-13 11:14   ` Mark Brown
2023-04-13 11:25     ` Joey Gouly
2023-04-13 16:13   ` Catalin Marinas
2023-04-13 11:04 ` [PATCH v2 02/19] arm64/sysreg: add system registers TCR2_ELx Joey Gouly
2023-04-13 16:14   ` Catalin Marinas
2023-04-13 11:04 ` [PATCH v2 03/19] arm64/sysreg: update HCRX_EL2 register Joey Gouly
2023-04-13 11:20   ` Mark Brown
2023-04-13 16:14   ` Catalin Marinas
2023-04-13 11:04 ` [PATCH v2 04/19] arm64/sysreg: add PIR*_ELx registers Joey Gouly
2023-04-13 16:15   ` Catalin Marinas
2023-04-13 11:04 ` [PATCH v2 05/19] arm64: cpufeature: add system register ID_AA64MMFR3 Joey Gouly
2023-04-13 11:05 ` [PATCH v2 06/19] arm64: cpufeature: add TCR2 cpucap Joey Gouly
2023-04-13 11:25   ` Mark Brown
2023-04-13 11:05 ` [PATCH v2 07/19] arm64: cpufeature: add Permission Indirection Extension cpucap Joey Gouly
2023-04-13 11:30   ` Mark Brown
2023-04-13 11:05 ` [PATCH v2 08/19] KVM: arm64: Save/restore TCR2_EL1 Joey Gouly
2023-04-20  9:13   ` Marc Zyngier
2023-04-20 14:11     ` Joey Gouly
2023-04-13 11:05 ` [PATCH v2 09/19] KVM: arm64: Save/restore PIE registers Joey Gouly
2023-04-20  8:36   ` Marc Zyngier
2023-04-13 11:05 ` [PATCH v2 10/19] KVM: arm64: expose ID_AA64MMFR3_EL1 to guests Joey Gouly
2023-04-13 16:15   ` Catalin Marinas
2023-04-13 11:05 ` [PATCH v2 11/19] arm64: add PTE_UXN/PTE_WRITE to SWAPPER_*_FLAGS Joey Gouly
2023-04-13 16:35   ` Catalin Marinas
2023-04-20 15:29     ` Joey Gouly
2023-04-21  7:52       ` Catalin Marinas [this message]
2023-04-13 11:05 ` [PATCH v2 12/19] arm64: add PTE_WRITE to PROT_SECT_NORMAL Joey Gouly
2023-04-13 11:05 ` [PATCH v2 13/19] arm64: reorganise PAGE_/PROT_ macros Joey Gouly
2023-04-13 11:05 ` [PATCH v2 14/19] arm64: disable EL2 traps for PIE Joey Gouly
2023-04-13 16:42   ` Catalin Marinas
2023-04-13 11:05 ` [PATCH v2 15/19] arm64: add encodings of PIRx_ELx registers Joey Gouly
2023-04-18 14:02   ` Mark Brown
2023-04-13 11:05 ` [PATCH v2 16/19] arm64: enable Permission Indirection Extension (PIE) Joey Gouly
2023-04-13 11:05 ` [PATCH v2 17/19] arm64: transfer permission indirection settings to EL2 Joey Gouly
2023-04-13 11:05 ` [PATCH v2 18/19] arm64: Document boot requirements for PIE Joey Gouly
2023-04-13 11:45   ` Mark Brown
2023-04-13 16:45   ` Catalin Marinas
2023-04-13 11:05 ` [PATCH v2 19/19] KVM: selftests: get-reg-list: add Permission Indirection registers Joey Gouly
2023-04-13 16:43   ` Catalin Marinas
2023-04-13 18:04   ` Mark Brown

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