From: Matthew Wilcox <willy@infradead.org>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Kees Cook <keescook@chromium.org>,
Sri Krishna chowdary <schowdary@nvidia.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
x86@kernel.org, Dave Hansen <dave.hansen@intel.com>,
linux-kernel@vger.kernel.org, Steven Price <Steven.Price@arm.com>,
linux-mm@kvack.org, Mark Brown <Mark.Brown@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC] mm/pgtable/debug: Add test validating architecture page table helpers
Date: Thu, 25 Jul 2019 14:42:22 -0700 [thread overview]
Message-ID: <20190725214222.GG30641@bombadil.infradead.org> (raw)
In-Reply-To: <20190725213858.GK1330@shell.armlinux.org.uk>
On Thu, Jul 25, 2019 at 10:38:58PM +0100, Russell King - ARM Linux admin wrote:
> On Thu, Jul 25, 2019 at 07:39:21AM -0700, Matthew Wilcox wrote:
> > But 'page' isn't necessarily PMD-aligned. I don't think we can rely on
> > architectures doing the right thing if asked to make a PMD for a randomly
> > aligned page.
> >
> > How about finding the physical address of something like kernel_init(),
> > and using the corresponding pte/pmd/pud/p4d/pgd that encompasses that
> > address? It's also better to pass in the pfn/page rather than using global
> > variables to communicate to the test functions.
>
> There are architectures (32-bit ARM) where the kernel is mapped using
> section mappings, and we don't expect the Linux page table walking to
> work for section mappings.
This test doesn't go so far as to insert the PTE/PMD/PUD/... into the
page tables. It merely needs an appropriately aligned PFN to create a
PTE/PMD/PUD/... from.
next prev parent reply other threads:[~2019-07-25 21:42 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 6:55 [RFC] mm/debug: Add tests for architecture exported page table helpers Anshuman Khandual
2019-07-25 6:55 ` [RFC] mm/pgtable/debug: Add test validating architecture " Anshuman Khandual
2019-07-25 14:39 ` Matthew Wilcox
2019-07-25 21:38 ` Russell King - ARM Linux admin
2019-07-25 21:42 ` Matthew Wilcox [this message]
2019-07-25 21:58 ` Russell King - ARM Linux admin
2019-07-25 22:56 ` Matthew Wilcox
2019-07-26 4:47 ` Anshuman Khandual
2019-07-26 19:54 ` Matthew Wilcox
2019-07-29 8:32 ` Anshuman Khandual
2019-07-30 17:03 ` Matthew Wilcox
2019-08-05 4:35 ` Anshuman Khandual
2019-07-25 17:07 ` Catalin Marinas
2019-07-26 4:28 ` Anshuman Khandual
2019-07-25 21:54 ` Russell King - ARM Linux admin
2019-07-26 5:10 ` Anshuman Khandual
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