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    Subject[PATCH v2 09/26] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers
    Date
    From: Andrea Arcangeli <aarcange@redhat.com>

    Implement helpers methods to invoke userfaultfd wp faults more
    selectively: not only when a wp fault triggers on a vma with
    vma->vm_flags VM_UFFD_WP set, but only if the _PAGE_UFFD_WP bit is set
    in the pagetable too.

    Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
    Signed-off-by: Peter Xu <peterx@redhat.com>
    ---
    include/linux/userfaultfd_k.h | 27 +++++++++++++++++++++++++++
    1 file changed, 27 insertions(+)

    diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
    index 38f748e7186e..c6590c58ce28 100644
    --- a/include/linux/userfaultfd_k.h
    +++ b/include/linux/userfaultfd_k.h
    @@ -14,6 +14,8 @@
    #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */

    #include <linux/fcntl.h>
    +#include <linux/mm.h>
    +#include <asm-generic/pgtable_uffd.h>

    /*
    * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
    @@ -55,6 +57,18 @@ static inline bool userfaultfd_wp(struct vm_area_struct *vma)
    return vma->vm_flags & VM_UFFD_WP;
    }

    +static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
    + pte_t pte)
    +{
    + return userfaultfd_wp(vma) && pte_uffd_wp(pte);
    +}
    +
    +static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
    + pmd_t pmd)
    +{
    + return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
    +}
    +
    static inline bool userfaultfd_armed(struct vm_area_struct *vma)
    {
    return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
    @@ -104,6 +118,19 @@ static inline bool userfaultfd_wp(struct vm_area_struct *vma)
    return false;
    }

    +static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
    + pte_t pte)
    +{
    + return false;
    +}
    +
    +static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
    + pmd_t pmd)
    +{
    + return false;
    +}
    +
    +
    static inline bool userfaultfd_armed(struct vm_area_struct *vma)
    {
    return false;
    --
    2.17.1
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