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From: Michael Ellerman <mpe@ellerman.id.au>
To: Steven Price <steven.price@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org
Cc: "Mark Rutland" <mark.rutland@arm.com>,
	x86@kernel.org, "Arnd Bergmann" <arnd@arndb.de>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	linux-kernel@vger.kernel.org,
	"Steven Price" <steven.price@arm.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Andy Lutomirski" <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"James Morse" <james.morse@arm.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Will Deacon" <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org, "Liang,
	Kan" <kan.liang@linux.intel.com>
Subject: Re: [PATCH v17 01/23] mm: Add generic p?d_leaf() macros
Date: Thu, 19 Dec 2019 22:43:14 +1100
Message-ID: <878sn8mtgt.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20191218162402.45610-2-steven.price@arm.com>

Steven Price <steven.price@arm.com> writes:
> Exposing the pud/pgd levels of the page tables to walk_page_range() means
> we may come across the exotic large mappings that come with large areas
> of contiguous memory (such as the kernel's linear map).
>
> For architectures that don't provide all p?d_leaf() macros, provide
> generic do nothing default that are suitable where there cannot be leaf
> pages at that level. Futher patches will add implementations for
> individual architectures.
>
> The name p?d_leaf() is chosen to minimize the confusion with existing
> uses of "large" pages and "huge" pages which do not necessary mean that
> the entry is a leaf (for example it may be a set of contiguous entries
> that only take 1 TLB slot). For the purpose of walking the page tables
> we don't need to know how it will be represented in the TLB, but we do
> need to know for sure if it is a leaf of the tree.
>
> Signed-off-by: Steven Price <steven.price@arm.com>
> Acked-by: Mark Rutland <mark.rutland@arm.com>
> ---
>  include/asm-generic/pgtable.h | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
>
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 798ea36a0549..e2e2bef07dd2 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -1238,4 +1238,24 @@ static inline bool arch_has_pfn_modify_check(void)
>  #define mm_pmd_folded(mm)	__is_defined(__PAGETABLE_PMD_FOLDED)
>  #endif
>  
> +/*
> + * p?d_leaf() - true if this entry is a final mapping to a physical address.
> + * This differs from p?d_huge() by the fact that they are always available (if
> + * the architecture supports large pages at the appropriate level) even
> + * if CONFIG_HUGETLB_PAGE is not defined.
> + * Only meaningful when called on a valid entry.
> + */
> +#ifndef pgd_leaf
> +#define pgd_leaf(x)	0
> +#endif
> +#ifndef p4d_leaf
> +#define p4d_leaf(x)	0
> +#endif
> +#ifndef pud_leaf
> +#define pud_leaf(x)	0
> +#endif
> +#ifndef pmd_leaf
> +#define pmd_leaf(x)	0
> +#endif

Any reason you made these #defines rather than static inlines?

cheers

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Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-18 16:23 [PATCH v17 00/23] Generic page walk and ptdump Steven Price
2019-12-18 16:23 ` [PATCH v17 01/23] mm: Add generic p?d_leaf() macros Steven Price
2019-12-19 11:43   ` Michael Ellerman [this message]
2019-12-20 11:48     ` Steven Price
2019-12-21 10:35       ` Michael Ellerman
2019-12-18 16:23 ` [PATCH v17 02/23] arc: mm: Add p?d_leaf() definitions Steven Price
2019-12-18 16:23 ` [PATCH v17 03/23] arm: " Steven Price
2019-12-18 16:23 ` [PATCH v17 04/23] arm64: " Steven Price
2019-12-18 16:23 ` [PATCH v17 05/23] mips: " Steven Price
2019-12-18 16:23 ` [PATCH v17 06/23] powerpc: " Steven Price
2019-12-19 11:49   ` Michael Ellerman
2019-12-20 11:53     ` Steven Price
2019-12-18 16:23 ` [PATCH v17 07/23] riscv: " Steven Price
2019-12-18 16:23 ` [PATCH v17 08/23] s390: " Steven Price
2019-12-18 16:23 ` [PATCH v17 09/23] sparc: " Steven Price
2019-12-18 16:23 ` [PATCH v17 10/23] x86: " Steven Price
2019-12-18 16:23 ` [PATCH v17 11/23] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price
2019-12-19 14:25   ` Thomas Hellström (VMware)
2019-12-20 15:35     ` Steven Price
2019-12-18 16:23 ` [PATCH v17 12/23] mm: pagewalk: Allow walking without vma Steven Price
2019-12-18 16:23 ` [PATCH v17 13/23] mm: pagewalk: Don't lock PTEs for walk_page_range_novma() Steven Price
2019-12-18 16:23 ` [PATCH v17 14/23] mm: pagewalk: fix termination condition in walk_pte_range() Steven Price
2019-12-18 16:23 ` [PATCH v17 15/23] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price
2019-12-18 16:23 ` [PATCH v17 16/23] x86: mm: Point to struct seq_file from struct pg_state Steven Price
2019-12-18 16:23 ` [PATCH v17 17/23] x86: mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price
2019-12-18 16:23 ` [PATCH v17 18/23] x86: mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price
2019-12-18 16:23 ` [PATCH v17 19/23] mm: Add generic ptdump Steven Price
2019-12-18 16:23 ` [PATCH v17 20/23] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price
2019-12-18 16:24 ` [PATCH v17 21/23] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price
2020-02-16 16:25   ` Ard Biesheuvel
2020-02-17 10:01     ` Steven Price
2020-02-17 10:16       ` Ard Biesheuvel
2019-12-18 16:24 ` [PATCH v17 22/23] arm64: mm: Display non-present entries in ptdump Steven Price
2019-12-18 16:24 ` [PATCH v17 23/23] mm: ptdump: Reduce level numbers by 1 in note_page() Steven Price

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