[PATCH v2 1/3] arm64: mm: Add p?d_large() definitions

Nicholas Piggin npiggin at gmail.com
Tue Jul 2 12:55:12 AEST 2019

Steven Price's on July 1, 2019 7:57 pm:
> On 01/07/2019 07:40, Nicholas Piggin wrote:
>> walk_page_range() is going to be allowed to walk page tables other than
>> those of user space. For this it needs to know when it has reached a
>> 'leaf' entry in the page tables. This information will be provided by the
>> p?d_large() functions/macros.
>> For arm64, we already have p?d_sect() macros which we can reuse for
>> p?d_large().
>> pud_sect() is defined as a dummy function when CONFIG_PGTABLE_LEVELS < 3
>> or CONFIG_ARM64_64K_PAGES is defined. However when the kernel is
>> configured this way then architecturally it isn't allowed to have a
>> large page that this level, and any code using these page walking macros
>> is implicitly relying on the page size/number of levels being the same as
>> the kernel. So it is safe to reuse this for p?d_large() as it is an
>> architectural restriction.
>> Cc: Catalin Marinas <catalin.marinas at arm.com>
>> Cc: Will Deacon <will.deacon at arm.com>
>> Signed-off-by: Steven Price <steven.price at arm.com>
> Hi Nicolas,
> This appears to my patch which I originally posted as part of converting
> x86/arm64 to use a generic page walk code[1].

Hey, yeah it is, I'd intended to mark you as the author but must have
forgot to change it in git.

> I'm not sure that this
> patch makes much sense on its own, in particular it was working up to
> having a generic macro[2] which means the _large() macros could be used
> across all architectures.

It goes with this series which makes _large macros usable for archs
that define HUGE_VMAP. I posted the same thing earlier and Anshuman
noted you'd done it too so I deferred to yours (I thought it would
go via arm64 tree and that this would just allow Andrew to easily
reconcile the merge).

If your series is not going upstream this time then the changelog
probably doesn't make so much sense, so I could just send my version
to the arm64 tree.


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