Re: [PATCH V3 2/2] mm/mmap: Drop generic protection_map[] array

From: Christophe Leroy
Date: Thu Jun 16 2022 - 01:45:48 EST

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In reply to: Anshuman Khandual: "Re: [PATCH V3 2/2] mm/mmap: Drop generic protection_map[] array"
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Le 16/06/2022 à 06:09, Anshuman Khandual a écrit :
> Move the protection_array[] array inside the arch for those platforms which
> do not enable ARCH_HAS_VM_GET_PAGE_PROT. Afterwards __SXXX/__PXX macros can
> be dropped completely which are now redundant.
>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Acked-by: Christoph Hellwig <hch@xxxxxx>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> ---
> arch/alpha/include/asm/pgtable.h | 17 -------
> arch/alpha/mm/init.c | 21 +++++++++
> arch/arc/include/asm/pgtable-bits-arcv2.h | 18 --------
> arch/arc/mm/mmap.c | 19 ++++++++
> arch/arm/include/asm/pgtable.h | 17 -------
> arch/arm/lib/uaccess_with_memcpy.c | 2 +-
> arch/arm/mm/mmu.c | 19 ++++++++
> arch/csky/include/asm/pgtable.h | 18 --------
> arch/csky/mm/init.c | 19 ++++++++
> arch/hexagon/include/asm/pgtable.h | 27 ------------
> arch/hexagon/mm/init.c | 41 +++++++++++++++++
> arch/ia64/include/asm/pgtable.h | 18 --------
> arch/ia64/mm/init.c | 27 +++++++++++-
> arch/loongarch/include/asm/pgtable-bits.h | 19 --------
> arch/loongarch/mm/cache.c | 45 +++++++++++++++++++
> arch/m68k/include/asm/mcf_pgtable.h | 54 -----------------------
> arch/m68k/include/asm/motorola_pgtable.h | 22 ---------
> arch/m68k/include/asm/sun3_pgtable.h | 17 -------
> arch/m68k/mm/mcfmmu.c | 54 +++++++++++++++++++++++
> arch/m68k/mm/motorola.c | 19 ++++++++
> arch/m68k/mm/sun3mmu.c | 19 ++++++++
> arch/microblaze/include/asm/pgtable.h | 17 -------
> arch/microblaze/mm/init.c | 19 ++++++++
> arch/mips/include/asm/pgtable.h | 22 ---------
> arch/mips/mm/cache.c | 2 +
> arch/nios2/include/asm/pgtable.h | 16 -------
> arch/nios2/mm/init.c | 19 ++++++++
> arch/openrisc/include/asm/pgtable.h | 18 --------
> arch/openrisc/mm/init.c | 19 ++++++++
> arch/parisc/include/asm/pgtable.h | 18 --------
> arch/parisc/mm/init.c | 19 ++++++++
> arch/powerpc/include/asm/pgtable.h | 20 ---------
> arch/powerpc/mm/book3s64/pgtable.c | 24 +++-------
> arch/powerpc/mm/pgtable.c | 20 +++++++++
> arch/riscv/include/asm/pgtable.h | 20 ---------
> arch/riscv/mm/init.c | 19 ++++++++
> arch/s390/include/asm/pgtable.h | 17 -------
> arch/s390/mm/mmap.c | 19 ++++++++
> arch/sh/include/asm/pgtable.h | 17 -------
> arch/sh/mm/mmap.c | 19 ++++++++
> arch/sparc/include/asm/pgtable_32.h | 19 --------
> arch/sparc/mm/init_32.c | 19 ++++++++
> arch/sparc/mm/init_64.c | 2 +-
> arch/um/include/asm/pgtable.h | 17 -------
> arch/um/kernel/mem.c | 19 ++++++++
> arch/x86/um/mem_32.c | 2 +-
> arch/xtensa/include/asm/pgtable.h | 18 --------
> arch/xtensa/mm/init.c | 19 ++++++++
> include/linux/mm.h | 2 +-
> mm/mmap.c | 19 --------
> 50 files changed, 503 insertions(+), 489 deletions(-)
>

> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index 8ed2a80c896e..bd636295a794 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -21,26 +21,6 @@ struct mm_struct;
> #endif /* !CONFIG_PPC_BOOK3S */
>
> /* Note due to the way vm flags are laid out, the bits are XWR */
> -#ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
> -#define __P000 PAGE_NONE
> -#define __P001 PAGE_READONLY
> -#define __P010 PAGE_COPY
> -#define __P011 PAGE_COPY
> -#define __P100 PAGE_READONLY_X
> -#define __P101 PAGE_READONLY_X
> -#define __P110 PAGE_COPY_X
> -#define __P111 PAGE_COPY_X
> -
> -#define __S000 PAGE_NONE
> -#define __S001 PAGE_READONLY
> -#define __S010 PAGE_SHARED
> -#define __S011 PAGE_SHARED
> -#define __S100 PAGE_READONLY_X
> -#define __S101 PAGE_READONLY_X
> -#define __S110 PAGE_SHARED_X
> -#define __S111 PAGE_SHARED_X
> -#endif
> -
> #ifndef __ASSEMBLY__
>
> #ifndef MAX_PTRS_PER_PGD
> diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
> index d3b019b95c1d..de76dd4d447c 100644
> --- a/arch/powerpc/mm/book3s64/pgtable.c
> +++ b/arch/powerpc/mm/book3s64/pgtable.c
> @@ -551,25 +551,11 @@ unsigned long memremap_compat_align(void)
> EXPORT_SYMBOL_GPL(memremap_compat_align);
> #endif
>
> -/* Note due to the way vm flags are laid out, the bits are XWR */
> -static const pgprot_t protection_map[16] = {
> - [VM_NONE] = PAGE_NONE,
> - [VM_READ] = PAGE_READONLY,
> - [VM_WRITE] = PAGE_COPY,
> - [VM_WRITE | VM_READ] = PAGE_COPY,
> - [VM_EXEC] = PAGE_READONLY_X,
> - [VM_EXEC | VM_READ] = PAGE_READONLY_X,
> - [VM_EXEC | VM_WRITE] = PAGE_COPY_X,
> - [VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY_X,
> - [VM_SHARED] = PAGE_NONE,
> - [VM_SHARED | VM_READ] = PAGE_READONLY,
> - [VM_SHARED | VM_WRITE] = PAGE_SHARED,
> - [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
> - [VM_SHARED | VM_EXEC] = PAGE_READONLY_X,
> - [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_X,
> - [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_X,
> - [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X
> -};
> +/*
> + * Generic declaration in (include/linux/mm.h) is not available
> + * here as the platform enables ARCH_HAS_VM_GET_PAGE_PROT.
> + */
> +extern pgprot_t protection_map[16];
>
> pgprot_t vm_get_page_prot(unsigned long vm_flags)
> {
> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
> index e6166b71d36d..780fbecd7bf6 100644
> --- a/arch/powerpc/mm/pgtable.c
> +++ b/arch/powerpc/mm/pgtable.c
> @@ -472,3 +472,23 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
> return ret_pte;
> }
> EXPORT_SYMBOL_GPL(__find_linux_pte);
> +
> +/* Note due to the way vm flags are laid out, the bits are XWR */
> +pgprot_t protection_map[16] = {

Was const previously, now back to non const ? Maybe due to a conflict
with linux/mm.h ? At least it should be __ro_after_init.

> + [VM_NONE] = PAGE_NONE,
> + [VM_READ] = PAGE_READONLY,
> + [VM_WRITE] = PAGE_COPY,
> + [VM_WRITE | VM_READ] = PAGE_COPY,
> + [VM_EXEC] = PAGE_READONLY_X,
> + [VM_EXEC | VM_READ] = PAGE_READONLY_X,
> + [VM_EXEC | VM_WRITE] = PAGE_COPY_X,
> + [VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY_X,
> + [VM_SHARED] = PAGE_NONE,
> + [VM_SHARED | VM_READ] = PAGE_READONLY,
> + [VM_SHARED | VM_WRITE] = PAGE_SHARED,
> + [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
> + [VM_SHARED | VM_EXEC] = PAGE_READONLY_X,
> + [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_X,
> + [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_X,
> + [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X
> +};
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 2254c1980c8e..65b7f3d9ff87 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -420,11 +420,11 @@ extern unsigned int kobjsize(const void *objp);
> #endif
> #define VM_FLAGS_CLEAR (ARCH_VM_PKEY_FLAGS | VM_ARCH_CLEAR)
>
> -#ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
> /*
> * mapping from the currently active vm_flags protection bits (the
> * low four bits) to a page protection mask..
> */
> +#ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
> extern pgprot_t protection_map[16];
> #endif
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index e66920414945..012261c8efb8 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -102,25 +102,6 @@ static void unmap_region(struct mm_struct *mm,
> * x: (yes) yes
> */
> #ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
> -pgprot_t protection_map[16] __ro_after_init = {
> - [VM_NONE] = __P000,
> - [VM_READ] = __P001,
> - [VM_WRITE] = __P010,
> - [VM_WRITE | VM_READ] = __P011,
> - [VM_EXEC] = __P100,
> - [VM_EXEC | VM_READ] = __P101,
> - [VM_EXEC | VM_WRITE] = __P110,
> - [VM_EXEC | VM_WRITE | VM_READ] = __P111,
> - [VM_SHARED] = __S000,
> - [VM_SHARED | VM_READ] = __S001,
> - [VM_SHARED | VM_WRITE] = __S010,
> - [VM_SHARED | VM_WRITE | VM_READ] = __S011,
> - [VM_SHARED | VM_EXEC] = __S100,
> - [VM_SHARED | VM_EXEC | VM_READ] = __S101,
> - [VM_SHARED | VM_EXEC | VM_WRITE] = __S110,
> - [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = __S111
> -};
> -
> pgprot_t vm_get_page_prot(unsigned long vm_flags)
> {
> return protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];

Next message: Yu Zhao: "Re: [PATCH v9 28/69] mm/mmap: reorganize munmap to use maple states"
Previous message: Yong Wu: "[PATCH v2 5/5] iommu/mediatek: Remove a unused "mapping" which is only for v1"
In reply to: Anshuman Khandual: "Re: [PATCH V3 2/2] mm/mmap: Drop generic protection_map[] array"
Next in thread: hch@xxxxxxxxxxxxx: "Re: [PATCH V3 2/2] mm/mmap: Drop generic protection_map[] array"
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