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    SubjectRe: [PATCH v2 06/20] ARM: LPAE: Introduce the 3-level page table format definitions
    On Fri, Nov 12, 2010 at 06:00:26PM +0000, Catalin Marinas wrote:
    > This patch introduces the pgtable-3level*.h files with definitions
    > specific to the LPAE page table format (3 levels of page tables).
    >
    > Each table is 4KB and has 512 64-bit entries. An entry can point to a
    > 40-bit physical address. The young, write and exec software bits share
    > the corresponding hardware bits (negated). Other software bits use spare
    > bits in the PTE.
    >
    > The patch also changes some variable types from unsigned long or int to
    > pteval_t or pgprot_t.
    >
    > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
    > ---
    > arch/arm/include/asm/page.h | 4 +
    > arch/arm/include/asm/pgtable-3level-hwdef.h | 78 ++++++++++++++++++
    > arch/arm/include/asm/pgtable-3level-types.h | 55 +++++++++++++
    > arch/arm/include/asm/pgtable-3level.h | 113 +++++++++++++++++++++++++++
    > arch/arm/include/asm/pgtable-hwdef.h | 4 +
    > arch/arm/include/asm/pgtable.h | 6 +-
    > arch/arm/mm/mm.h | 8 +-
    > arch/arm/mm/mmu.c | 2 +-
    > 8 files changed, 264 insertions(+), 6 deletions(-)
    > create mode 100644 arch/arm/include/asm/pgtable-3level-hwdef.h
    > create mode 100644 arch/arm/include/asm/pgtable-3level-types.h
    > create mode 100644 arch/arm/include/asm/pgtable-3level.h
    >
    > diff --git a/arch/arm/include/asm/page.h b/arch/arm/include/asm/page.h
    > index 3848105..e5124db 100644
    > --- a/arch/arm/include/asm/page.h
    > +++ b/arch/arm/include/asm/page.h
    > @@ -151,7 +151,11 @@ extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
    > #define clear_page(page) memset((void *)(page), 0, PAGE_SIZE)
    > extern void copy_page(void *to, const void *from);
    >
    > +#ifdef CONFIG_ARM_LPAE
    > +#include <asm/pgtable-3level-types.h>
    > +#else
    > #include <asm/pgtable-2level-types.h>
    > +#endif
    >
    > #endif /* CONFIG_MMU */
    >
    > diff --git a/arch/arm/include/asm/pgtable-3level-hwdef.h b/arch/arm/include/asm/pgtable-3level-hwdef.h
    > new file mode 100644
    > index 0000000..2f99c3c
    > --- /dev/null
    > +++ b/arch/arm/include/asm/pgtable-3level-hwdef.h
    > @@ -0,0 +1,78 @@
    > +/*
    > + * arch/arm/include/asm/pgtable-3level-hwdef.h
    > + *
    > + * Copyright (C) 2010 ARM Ltd.
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License version 2 as
    > + * published by the Free Software Foundation.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + * You should have received a copy of the GNU General Public License
    > + * along with this program; if not, write to the Free Software
    > + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    > + */
    > +#ifndef _ASM_PGTABLE_3LEVEL_HWDEF_H
    > +#define _ASM_PGTABLE_3LEVEL_HWDEF_H
    > +
    > +#include <linux/const.h>
    > +#include <asm/pgtable-3level-types.h>
    > +
    > +/*
    > + * Hardware page table definitions.
    > + *
    > + * + Level 1/2 descriptor
    > + * - common
    > + */
    > +#define PMD_TYPE_MASK (_AT(pmd_t, 3) << 0)
    > +#define PMD_TYPE_FAULT (_AT(pmd_t, 0) << 0)
    > +#define PMD_TYPE_TABLE (_AT(pmd_t, 3) << 0)
    > +#define PMD_TYPE_SECT (_AT(pmd_t, 1) << 0)
    > +#define PMD_BIT4 (_AT(pmd_t, 0))
    > +#define PMD_DOMAIN(x) (_AT(pmd_t, 0))
    It is really not correct to have these constants type'd as pmd_t.
    The idea behind pmd_t et.al. is to detect when normal arithmetic or
    logical operations are performed on page table entries when the
    accessors instead should be used.

    By typing these as pmd_t, it means operations need to be:

    u32 pmdval = pmd_val(foo) | pmd_val(PMD_TYE_TABLE);
    which is obviously more complicated than is needed.

    > diff --git a/arch/arm/mm/mm.h b/arch/arm/mm/mm.h
    > index 6630620..a62f093 100644
    > --- a/arch/arm/mm/mm.h
    > +++ b/arch/arm/mm/mm.h
    > @@ -16,10 +16,10 @@ static inline pmd_t *pmd_off_k(unsigned long virt)
    > }
    >
    > struct mem_type {
    > - unsigned int prot_pte;
    > - unsigned int prot_l1;
    > - unsigned int prot_sect;
    > - unsigned int domain;
    > + pgprot_t prot_pte;
    > + pgprot_t prot_l1;
    > + pgprot_t prot_sect;
    > + pgprot_t domain;

    Again, this is wrong. There's an accessor for pgprot_t typed data. This
    causes code to violate it.

    > diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
    > index 0ca33dd..7c803c4 100644
    > --- a/arch/arm/mm/mmu.c
    > +++ b/arch/arm/mm/mmu.c
    > @@ -292,7 +292,7 @@ static void __init build_mem_type_table(void)
    > {
    > struct cachepolicy *cp;
    > unsigned int cr = get_cr();
    > - unsigned int user_pgprot, kern_pgprot, vecs_pgprot;
    > + pgprot_t user_pgprot, kern_pgprot, vecs_pgprot;

    Ditto.


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