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From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 4/4] arm64: Use a variable to store non-global mappings decision
Date: Wed, 6 Nov 2019 12:12:36 +0000	[thread overview]
Message-ID: <20191106121236.GA4544@sirena.co.uk> (raw)
In-Reply-To: <20191106102428.GE21133@arrakis.emea.arm.com>


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On Wed, Nov 06, 2019 at 10:24:28AM +0000, Catalin Marinas wrote:
> On Tue, Nov 05, 2019 at 09:48:54PM +0000, Mark Brown wrote:

> > +        /*
> > +         * If know now we are going to need KPTI then use non-global
> > +         * mappings from the start, avoiding the cost of rewriting
> > +         * everything later.
> > +         */
> > +        arm64_use_ng_mappings = kaslr_requires_kpti();

> This really needs to be done before map_kernel() and map_mem() in
> paging_init(). Tested this series and most of the linear map does not
> have the nG bit when it should (/sys/kernel/debug/kernel_page_tables).

Hrm, right.  That was getting hidden in the other noise in the diffs
(I've been mainly checking that I was getting similar page tables
between the various configurations in hetrogenous systems).  It looks
like anywhere paging_init() is too late, the reordering you suggest
still leaves some stray non-global mappings.  I've moved it to the start
of setup_arch() which seems early enough.

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      reply	other threads:[~2019-11-06 12:12 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-05 21:48 [PATCH v6 0/4] E0PD support Mark Brown
2019-11-05 21:48 ` [PATCH v6 1/4] arm64: Add initial support for E0PD Mark Brown
2019-11-05 21:48 ` [PATCH v6 2/4] arm64: Factor out checks for KASLR in KPTI code into separate function Mark Brown
2019-11-05 21:48 ` [PATCH v6 3/4] arm64: Don't use KPTI where we have E0PD Mark Brown
2019-11-05 21:48 ` [PATCH v6 4/4] arm64: Use a variable to store non-global mappings decision Mark Brown
2019-11-06 10:24   ` Catalin Marinas
2019-11-06 12:12     ` Mark Brown [this message]

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