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    Subject[PATCH 03/17] mm/nommu: fix the MAP_UNINITIALIZED flag
    Date
    We can't expose UAPI symbols differently based on CONFIG_ symbols, as
    userspace won't have them available. Instead always define the flag,
    but only repsect it based on the config option.

    Signed-off-by: Christoph Hellwig <hch@lst.de>
    ---
    arch/xtensa/include/uapi/asm/mman.h | 6 +-----
    include/uapi/asm-generic/mman-common.h | 8 +++-----
    mm/nommu.c | 4 +++-
    3 files changed, 7 insertions(+), 11 deletions(-)

    diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h
    index be726062412b..ebbb48842190 100644
    --- a/arch/xtensa/include/uapi/asm/mman.h
    +++ b/arch/xtensa/include/uapi/asm/mman.h
    @@ -56,12 +56,8 @@
    #define MAP_STACK 0x40000 /* give out an address that is best suited for process/thread stacks */
    #define MAP_HUGETLB 0x80000 /* create a huge page mapping */
    #define MAP_FIXED_NOREPLACE 0x100000 /* MAP_FIXED which doesn't unmap underlying mapping */
    -#ifdef CONFIG_MMAP_ALLOW_UNINITIALIZED
    -# define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be
    +#define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be
    * uninitialized */
    -#else
    -# define MAP_UNINITIALIZED 0x0 /* Don't support this flag */
    -#endif

    /*
    * Flags for msync
    diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
    index abd238d0f7a4..cb556b430e71 100644
    --- a/include/uapi/asm-generic/mman-common.h
    +++ b/include/uapi/asm-generic/mman-common.h
    @@ -19,15 +19,13 @@
    #define MAP_TYPE 0x0f /* Mask for type of mapping */
    #define MAP_FIXED 0x10 /* Interpret addr exactly */
    #define MAP_ANONYMOUS 0x20 /* don't use a file */
    -#ifdef CONFIG_MMAP_ALLOW_UNINITIALIZED
    -# define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be uninitialized */
    -#else
    -# define MAP_UNINITIALIZED 0x0 /* Don't support this flag */
    -#endif

    /* 0x0100 - 0x80000 flags are defined in asm-generic/mman.h */
    #define MAP_FIXED_NOREPLACE 0x100000 /* MAP_FIXED which doesn't unmap underlying mapping */

    +#define MAP_UNINITIALIZED 0x4000000 /* For anonymous mmap, memory could be
    + * uninitialized */
    +
    /*
    * Flags for mlock
    */
    diff --git a/mm/nommu.c b/mm/nommu.c
    index d8c02fbe03b5..ec75a0dffd4f 100644
    --- a/mm/nommu.c
    +++ b/mm/nommu.c
    @@ -1349,7 +1349,9 @@ unsigned long do_mmap(struct file *file,
    add_nommu_region(region);

    /* clear anonymous mappings that don't ask for uninitialized data */
    - if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
    + if (!vma->vm_file &&
    + (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) ||
    + !(flags & MAP_UNINITIALIZED)))
    memset((void *)region->vm_start, 0,
    region->vm_end - region->vm_start);

    --
    2.20.1
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