From: Mark Rutland <mark.rutland@arm.com>
To: Steven Price <steven.price@arm.com>
Cc: "Peter Zijlstra" <peterz@infradead.org>,
x86@kernel.org, "Arnd Bergmann" <arnd@arndb.de>,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Will Deacon" <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"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>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 01/13] arm64: mm: Add p?d_large() definitions
Date: Mon, 18 Feb 2019 14:29:52 +0000 [thread overview]
Message-ID: <20190218142951.GA10145@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <fe36ed1c-b90d-8062-f7a9-e52d940733c4@arm.com>
On Mon, Feb 18, 2019 at 02:11:40PM +0000, Steven Price wrote:
> On 18/02/2019 11:29, Peter Zijlstra wrote:
> > On Fri, Feb 15, 2019 at 05:02:22PM +0000, Steven Price wrote:
> >
> >> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> >> index de70c1eabf33..09d308921625 100644
> >> --- a/arch/arm64/include/asm/pgtable.h
> >> +++ b/arch/arm64/include/asm/pgtable.h
> >> @@ -428,6 +428,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
> >> PMD_TYPE_TABLE)
> >> #define pmd_sect(pmd) ((pmd_val(pmd) & PMD_TYPE_MASK) == \
> >> PMD_TYPE_SECT)
> >> +#define pmd_large(x) pmd_sect(x)
> >>
> >> #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS < 3
> >> #define pud_sect(pud) (0)
> >> @@ -435,6 +436,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
> >> #else
> >> #define pud_sect(pud) ((pud_val(pud) & PUD_TYPE_MASK) == \
> >> PUD_TYPE_SECT)
> >> +#define pud_large(x) pud_sect(x)
> >> #define pud_table(pud) ((pud_val(pud) & PUD_TYPE_MASK) == \
> >> PUD_TYPE_TABLE)
> >> #endif
> >
> > So on x86 p*d_large() also matches p*d_huge() and thp, But it is not
> > clear to me this p*d_sect() thing does so, given your definitions.
> >
> > See here why I care:
> >
> > http://lkml.kernel.org/r/20190201124741.GE31552@hirez.programming.kicks-ass.net
> >
>
> pmd_huge()/pud_huge() unfortunately are currently defined as '0' if
> !CONFIG_HUGETLB_PAGE and for this reason I was avoiding using them.
I think that Peter means p?d_huge(x) should imply p?d_large(x), e.g.
#define pmd_large(x) \
(pmd_sect(x) || pmd_huge(x) || pmd_trans_huge(x))
... which should work regardless of CONFIG_HUGETLB_PAGE.
> While most code would reasonably not care about huge pages in that build
> configuration, the likes of the debugfs page table dump code needs to be
> able to recognise them in all build configurations. I believe the
> situation is the same on arm64 and x86.
There's a very important distinction here between:
* section mappings, which are an archtiectural construct used in
arm64-specific code (e.g. the kernel's own page tables).
* huge mappings, which are Linux logical construct for mapping
userspace memory. These are buillt using section mappings.
The existing arm64 debugfs pagetable dump code cares about section
mappings specifically in all cases, since it is not used to dump
userspace page tables.
The existing generic code doesn't care about section mappings
specifically, because they are not generic.
Thanks,
Mark.
next prev parent reply other threads:[~2019-02-18 14:42 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-15 17:02 [PATCH 00/13] Convert x86 & arm64 to use generic page walk Steven Price
2019-02-15 17:02 ` [PATCH 01/13] arm64: mm: Add p?d_large() definitions Steven Price
2019-02-18 11:16 ` Mark Rutland
2019-02-18 11:29 ` Peter Zijlstra
2019-02-18 13:45 ` Mark Rutland
2019-02-18 14:11 ` Steven Price
2019-02-18 14:29 ` Mark Rutland [this message]
2019-02-18 15:06 ` Peter Zijlstra
2019-02-18 15:30 ` Steven Price
2019-02-18 17:04 ` Mark Rutland
2019-02-18 17:22 ` Steven Price
2019-02-15 17:02 ` [PATCH 02/13] x86/mm: " Steven Price
2019-02-15 17:02 ` [PATCH 03/13] mm: Add generic p?d_large() macros Steven Price
2019-02-18 11:14 ` Mark Rutland
2019-02-18 12:53 ` Peter Zijlstra
2019-02-18 14:20 ` Steven Price
2019-02-18 11:31 ` Peter Zijlstra
2019-02-18 14:19 ` Steven Price
2019-02-19 3:44 ` Liang, Kan
2019-02-20 13:56 ` Steven Price
2019-02-15 17:02 ` [PATCH 04/13] mm: pagewalk: Add p4d_entry() and pgd_entry() Steven Price
2019-02-15 17:02 ` [PATCH 05/13] mm: pagewalk: Allow walking without vma Steven Price
2019-02-15 17:02 ` [PATCH 06/13] mm: pagewalk: Add 'depth' parameter to pte_hole Steven Price
2019-02-18 11:23 ` Mark Rutland
2019-02-18 15:23 ` Steven Price
2019-02-20 11:35 ` William Kucharski
2019-02-20 14:10 ` Steven Price
2019-02-15 17:02 ` [PATCH 07/13] mm: pagewalk: Add test_p?d callbacks Steven Price
2019-02-15 17:02 ` [PATCH 08/13] arm64: mm: Convert mm/dump.c to use walk_page_range() Steven Price
2019-02-15 17:02 ` [PATCH 09/13] x86/mm: Point to struct seq_file from struct pg_state Steven Price
2019-02-15 17:02 ` [PATCH 10/13] x86/mm+efi: Convert ptdump_walk_pgd_level() to take a mm_struct Steven Price
2019-02-15 17:02 ` [PATCH 11/13] x86/mm: Convert ptdump_walk_pgd_level_debugfs() to take an mm_struct Steven Price
2019-02-15 17:02 ` [PATCH 12/13] x86/mm: Convert ptdump_walk_pgd_level_core() " Steven Price
2019-02-15 17:02 ` [PATCH 13/13] x86: mm: Convert dump_pagetables to use walk_page_range Steven Price
2019-02-15 17:16 ` Dave Hansen
2019-02-15 17:32 ` Steven Price
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