443 lines
12 KiB
C
443 lines
12 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/linux/userfaultfd_k.h
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*
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* Copyright (C) 2015 Red Hat, Inc.
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*
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*/
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#ifndef _LINUX_USERFAULTFD_K_H
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#define _LINUX_USERFAULTFD_K_H
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#ifdef CONFIG_USERFAULTFD
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#include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
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#include <linux/fcntl.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <asm-generic/pgtable_uffd.h>
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#include <linux/hugetlb_inline.h>
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/* The set of all possible UFFD-related VM flags. */
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#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR)
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/*
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* CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
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* new flags, since they might collide with O_* ones. We want
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* to re-use O_* flags that couldn't possibly have a meaning
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* from userfaultfd, in order to leave a free define-space for
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* shared O_* flags.
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*/
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#define UFFD_CLOEXEC O_CLOEXEC
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#define UFFD_NONBLOCK O_NONBLOCK
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#define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
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#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
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/*
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* Start with fault_pending_wqh and fault_wqh so they're more likely
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* to be in the same cacheline.
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*
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* Locking order:
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* fd_wqh.lock
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* fault_pending_wqh.lock
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* fault_wqh.lock
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* event_wqh.lock
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*
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* To avoid deadlocks, IRQs must be disabled when taking any of the above locks,
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* since fd_wqh.lock is taken by aio_poll() while it's holding a lock that's
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* also taken in IRQ context.
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*/
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struct userfaultfd_ctx {
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/* waitqueue head for the pending (i.e. not read) userfaults */
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wait_queue_head_t fault_pending_wqh;
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/* waitqueue head for the userfaults */
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wait_queue_head_t fault_wqh;
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/* waitqueue head for the pseudo fd to wakeup poll/read */
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wait_queue_head_t fd_wqh;
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/* waitqueue head for events */
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wait_queue_head_t event_wqh;
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/* a refile sequence protected by fault_pending_wqh lock */
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seqcount_spinlock_t refile_seq;
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/* pseudo fd refcounting */
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refcount_t refcount;
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/* userfaultfd syscall flags */
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unsigned int flags;
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/* features requested from the userspace */
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unsigned int features;
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/* released */
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bool released;
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/*
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* Prevents userfaultfd operations (fill/move/wp) from happening while
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* some non-cooperative event(s) is taking place. Increments are done
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* in write-mode. Whereas, userfaultfd operations, which includes
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* reading mmap_changing, is done under read-mode.
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*/
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struct rw_semaphore map_changing_lock;
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/* memory mappings are changing because of non-cooperative event */
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atomic_t mmap_changing;
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/* mm with one ore more vmas attached to this userfaultfd_ctx */
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struct mm_struct *mm;
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};
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extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);
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/* A combined operation mode + behavior flags. */
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typedef unsigned int __bitwise uffd_flags_t;
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/* Mutually exclusive modes of operation. */
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enum mfill_atomic_mode {
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MFILL_ATOMIC_COPY,
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MFILL_ATOMIC_ZEROPAGE,
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MFILL_ATOMIC_CONTINUE,
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MFILL_ATOMIC_POISON,
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NR_MFILL_ATOMIC_MODES,
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};
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#define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1)
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#define MFILL_ATOMIC_BIT(nr) BIT(MFILL_ATOMIC_MODE_BITS + (nr))
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#define MFILL_ATOMIC_FLAG(nr) ((__force uffd_flags_t) MFILL_ATOMIC_BIT(nr))
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#define MFILL_ATOMIC_MODE_MASK ((__force uffd_flags_t) (MFILL_ATOMIC_BIT(0) - 1))
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static inline bool uffd_flags_mode_is(uffd_flags_t flags, enum mfill_atomic_mode expected)
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{
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return (flags & MFILL_ATOMIC_MODE_MASK) == ((__force uffd_flags_t) expected);
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}
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static inline uffd_flags_t uffd_flags_set_mode(uffd_flags_t flags, enum mfill_atomic_mode mode)
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{
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flags &= ~MFILL_ATOMIC_MODE_MASK;
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return flags | ((__force uffd_flags_t) mode);
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}
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/* Flags controlling behavior. These behavior changes are mode-independent. */
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#define MFILL_ATOMIC_WP MFILL_ATOMIC_FLAG(0)
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extern int mfill_atomic_install_pte(pmd_t *dst_pmd,
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struct vm_area_struct *dst_vma,
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unsigned long dst_addr, struct page *page,
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bool newly_allocated, uffd_flags_t flags);
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extern ssize_t mfill_atomic_copy(struct userfaultfd_ctx *ctx, unsigned long dst_start,
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unsigned long src_start, unsigned long len,
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uffd_flags_t flags);
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extern ssize_t mfill_atomic_zeropage(struct userfaultfd_ctx *ctx,
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unsigned long dst_start,
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unsigned long len);
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extern ssize_t mfill_atomic_continue(struct userfaultfd_ctx *ctx, unsigned long dst_start,
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unsigned long len, uffd_flags_t flags);
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extern ssize_t mfill_atomic_poison(struct userfaultfd_ctx *ctx, unsigned long start,
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unsigned long len, uffd_flags_t flags);
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extern int mwriteprotect_range(struct userfaultfd_ctx *ctx, unsigned long start,
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unsigned long len, bool enable_wp);
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extern long uffd_wp_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long len, bool enable_wp);
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/* move_pages */
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void double_pt_lock(spinlock_t *ptl1, spinlock_t *ptl2);
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void double_pt_unlock(spinlock_t *ptl1, spinlock_t *ptl2);
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ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
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unsigned long src_start, unsigned long len, __u64 flags);
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int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval,
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struct vm_area_struct *dst_vma,
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struct vm_area_struct *src_vma,
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unsigned long dst_addr, unsigned long src_addr);
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/* mm helpers */
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static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
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struct vm_userfaultfd_ctx vm_ctx)
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{
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return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
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}
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/*
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* Never enable huge pmd sharing on some uffd registered vmas:
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*
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* - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
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*
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* - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for
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* VMAs which share huge pmds. (If you have two mappings to the same
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* underlying pages, and fault in the non-UFFD-registered one with a write,
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* with huge pmd sharing this would *also* setup the second UFFD-registered
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* mapping, and we'd not get minor faults.)
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*/
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static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
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{
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return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
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}
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/*
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* Don't do fault around for either WP or MINOR registered uffd range. For
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* MINOR registered range, fault around will be a total disaster and ptes can
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* be installed without notifications; for WP it should mostly be fine as long
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* as the fault around checks for pte_none() before the installation, however
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* to be super safe we just forbid it.
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*/
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static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
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{
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return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
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}
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static inline bool userfaultfd_missing(struct vm_area_struct *vma)
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{
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return vma->vm_flags & VM_UFFD_MISSING;
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}
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static inline bool userfaultfd_wp(struct vm_area_struct *vma)
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{
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return vma->vm_flags & VM_UFFD_WP;
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}
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static inline bool userfaultfd_minor(struct vm_area_struct *vma)
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{
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return vma->vm_flags & VM_UFFD_MINOR;
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}
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static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
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pte_t pte)
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{
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return userfaultfd_wp(vma) && pte_uffd_wp(pte);
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}
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static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
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pmd_t pmd)
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{
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return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
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}
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static inline bool userfaultfd_armed(struct vm_area_struct *vma)
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{
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return vma->vm_flags & __VM_UFFD_FLAGS;
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}
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static inline bool vma_can_userfault(struct vm_area_struct *vma,
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unsigned long vm_flags,
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bool wp_async)
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{
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vm_flags &= __VM_UFFD_FLAGS;
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if ((vm_flags & VM_UFFD_MINOR) &&
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(!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
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return false;
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/*
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* If wp async enabled, and WP is the only mode enabled, allow any
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* memory type.
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*/
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if (wp_async && (vm_flags == VM_UFFD_WP))
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return true;
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#ifndef CONFIG_PTE_MARKER_UFFD_WP
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/*
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* If user requested uffd-wp but not enabled pte markers for
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* uffd-wp, then shmem & hugetlbfs are not supported but only
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* anonymous.
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*/
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if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma))
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return false;
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#endif
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/* By default, allow any of anon|shmem|hugetlb */
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return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
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vma_is_shmem(vma);
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}
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extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
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extern void dup_userfaultfd_complete(struct list_head *);
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extern void mremap_userfaultfd_prep(struct vm_area_struct *,
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struct vm_userfaultfd_ctx *);
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extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
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unsigned long from, unsigned long to,
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unsigned long len);
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extern bool userfaultfd_remove(struct vm_area_struct *vma,
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unsigned long start,
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unsigned long end);
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extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
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unsigned long start, unsigned long end, struct list_head *uf);
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extern void userfaultfd_unmap_complete(struct mm_struct *mm,
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struct list_head *uf);
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extern bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma);
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extern bool userfaultfd_wp_async(struct vm_area_struct *vma);
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#else /* CONFIG_USERFAULTFD */
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/* mm helpers */
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static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
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unsigned long reason)
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{
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return VM_FAULT_SIGBUS;
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}
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static inline long uffd_wp_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long len,
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bool enable_wp)
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{
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return false;
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}
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static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
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struct vm_userfaultfd_ctx vm_ctx)
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{
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return true;
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}
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static inline bool userfaultfd_missing(struct vm_area_struct *vma)
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{
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return false;
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}
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static inline bool userfaultfd_wp(struct vm_area_struct *vma)
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{
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return false;
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}
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static inline bool userfaultfd_minor(struct vm_area_struct *vma)
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{
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return false;
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}
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static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
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pte_t pte)
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{
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return false;
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}
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static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
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pmd_t pmd)
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{
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return false;
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}
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static inline bool userfaultfd_armed(struct vm_area_struct *vma)
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{
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return false;
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}
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static inline int dup_userfaultfd(struct vm_area_struct *vma,
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struct list_head *l)
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{
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return 0;
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}
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static inline void dup_userfaultfd_complete(struct list_head *l)
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{
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}
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static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
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struct vm_userfaultfd_ctx *ctx)
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{
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}
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static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
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unsigned long from,
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unsigned long to,
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unsigned long len)
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{
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}
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static inline bool userfaultfd_remove(struct vm_area_struct *vma,
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unsigned long start,
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unsigned long end)
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{
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return true;
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}
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static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
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unsigned long start, unsigned long end,
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struct list_head *uf)
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{
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return 0;
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}
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static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
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struct list_head *uf)
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{
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}
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static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
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{
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return false;
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}
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static inline bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma)
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{
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return false;
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}
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static inline bool userfaultfd_wp_async(struct vm_area_struct *vma)
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{
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return false;
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}
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#endif /* CONFIG_USERFAULTFD */
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static inline bool userfaultfd_wp_use_markers(struct vm_area_struct *vma)
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{
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/* Only wr-protect mode uses pte markers */
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if (!userfaultfd_wp(vma))
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return false;
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/* File-based uffd-wp always need markers */
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if (!vma_is_anonymous(vma))
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return true;
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/*
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* Anonymous uffd-wp only needs the markers if WP_UNPOPULATED
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* enabled (to apply markers on zero pages).
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*/
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return userfaultfd_wp_unpopulated(vma);
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}
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static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry)
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{
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#ifdef CONFIG_PTE_MARKER_UFFD_WP
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return is_pte_marker_entry(entry) &&
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(pte_marker_get(entry) & PTE_MARKER_UFFD_WP);
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#else
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return false;
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#endif
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}
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static inline bool pte_marker_uffd_wp(pte_t pte)
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{
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#ifdef CONFIG_PTE_MARKER_UFFD_WP
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swp_entry_t entry;
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if (!is_swap_pte(pte))
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return false;
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entry = pte_to_swp_entry(pte);
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return pte_marker_entry_uffd_wp(entry);
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#else
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return false;
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#endif
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}
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/*
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* Returns true if this is a swap pte and was uffd-wp wr-protected in either
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* forms (pte marker or a normal swap pte), false otherwise.
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*/
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static inline bool pte_swp_uffd_wp_any(pte_t pte)
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{
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#ifdef CONFIG_PTE_MARKER_UFFD_WP
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if (!is_swap_pte(pte))
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return false;
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if (pte_swp_uffd_wp(pte))
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return true;
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if (pte_marker_uffd_wp(pte))
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return true;
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#endif
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return false;
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}
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#endif /* _LINUX_USERFAULTFD_K_H */
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