include/linux/userfaultfd_k.h - linux/kernel/git/will/linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  *  include/linux/userfaultfd_k.h
  *
  *  Copyright (C) 2015  Red Hat, Inc.
  *
  */

 #ifndef _LINUX_USERFAULTFD_K_H
 #define _LINUX_USERFAULTFD_K_H

 #ifdef CONFIG_USERFAULTFD

 #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */

 #include <linux/fcntl.h>
 #include <linux/mm.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
 #include <asm-generic/pgtable_uffd.h>
 #include <linux/hugetlb_inline.h>

 /* The set of all possible UFFD-related VM flags. */
 #define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR)

 /*
  * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
  * new flags, since they might collide with O_* ones. We want
  * to re-use O_* flags that couldn't possibly have a meaning
  * from userfaultfd, in order to leave a free define-space for
  * shared O_* flags.
  */
 #define UFFD_CLOEXEC O_CLOEXEC
 #define UFFD_NONBLOCK O_NONBLOCK

 #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
 #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)

 /*
  * Start with fault_pending_wqh and fault_wqh so they're more likely
  * to be in the same cacheline.
  *
  * Locking order:
  *	fd_wqh.lock
  *		fault_pending_wqh.lock
  *			fault_wqh.lock
  *		event_wqh.lock
  *
  * To avoid deadlocks, IRQs must be disabled when taking any of the above locks,
  * since fd_wqh.lock is taken by aio_poll() while it's holding a lock that's
  * also taken in IRQ context.
  */
 struct userfaultfd_ctx {
 	/* waitqueue head for the pending (i.e. not read) userfaults */
 	wait_queue_head_t fault_pending_wqh;
 	/* waitqueue head for the userfaults */
 	wait_queue_head_t fault_wqh;
 	/* waitqueue head for the pseudo fd to wakeup poll/read */
 	wait_queue_head_t fd_wqh;
 	/* waitqueue head for events */
 	wait_queue_head_t event_wqh;
 	/* a refile sequence protected by fault_pending_wqh lock */
 	seqcount_spinlock_t refile_seq;
 	/* pseudo fd refcounting */
 	refcount_t refcount;
 	/* userfaultfd syscall flags */
 	unsigned int flags;
 	/* features requested from the userspace */
 	unsigned int features;
 	/* released */
 	bool released;
 	/*
 	 * Prevents userfaultfd operations (fill/move/wp) from happening while
 	 * some non-cooperative event(s) is taking place. Increments are done
 	 * in write-mode. Whereas, userfaultfd operations, which includes
 	 * reading mmap_changing, is done under read-mode.
 	 */
 	struct rw_semaphore map_changing_lock;
 	/* memory mappings are changing because of non-cooperative event */
 	atomic_t mmap_changing;
 	/* mm with one ore more vmas attached to this userfaultfd_ctx */
 	struct mm_struct *mm;
 };

 extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);

 /* A combined operation mode + behavior flags. */
 typedef unsigned int __bitwise uffd_flags_t;

 /* Mutually exclusive modes of operation. */
 enum mfill_atomic_mode {
 	MFILL_ATOMIC_COPY,
 	MFILL_ATOMIC_ZEROPAGE,
 	MFILL_ATOMIC_CONTINUE,
 	MFILL_ATOMIC_POISON,
 	NR_MFILL_ATOMIC_MODES,
 };

 #define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1)
 #define MFILL_ATOMIC_BIT(nr) BIT(MFILL_ATOMIC_MODE_BITS + (nr))
 #define MFILL_ATOMIC_FLAG(nr) ((__force uffd_flags_t) MFILL_ATOMIC_BIT(nr))
 #define MFILL_ATOMIC_MODE_MASK ((__force uffd_flags_t) (MFILL_ATOMIC_BIT(0) - 1))

 static inline bool uffd_flags_mode_is(uffd_flags_t flags, enum mfill_atomic_mode expected)
 {
 	return (flags & MFILL_ATOMIC_MODE_MASK) == ((__force uffd_flags_t) expected);
 }

 static inline uffd_flags_t uffd_flags_set_mode(uffd_flags_t flags, enum mfill_atomic_mode mode)
 {
 	flags &= ~MFILL_ATOMIC_MODE_MASK;
 	return flags | ((__force uffd_flags_t) mode);
 }

 /* Flags controlling behavior. These behavior changes are mode-independent. */
 #define MFILL_ATOMIC_WP MFILL_ATOMIC_FLAG(0)

 extern int mfill_atomic_install_pte(pmd_t *dst_pmd,
 				    struct vm_area_struct *dst_vma,
 				    unsigned long dst_addr, struct page *page,
 				    bool newly_allocated, uffd_flags_t flags);

 extern ssize_t mfill_atomic_copy(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 				 unsigned long src_start, unsigned long len,
 				 uffd_flags_t flags);
 extern ssize_t mfill_atomic_zeropage(struct userfaultfd_ctx *ctx,
 				     unsigned long dst_start,
 				     unsigned long len);
 extern ssize_t mfill_atomic_continue(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 				     unsigned long len, uffd_flags_t flags);
 extern ssize_t mfill_atomic_poison(struct userfaultfd_ctx *ctx, unsigned long start,
 				   unsigned long len, uffd_flags_t flags);
 extern int mwriteprotect_range(struct userfaultfd_ctx *ctx, unsigned long start,
 			       unsigned long len, bool enable_wp);
 extern long uffd_wp_range(struct vm_area_struct *vma,
 			  unsigned long start, unsigned long len, bool enable_wp);

 /* move_pages */
 void double_pt_lock(spinlock_t *ptl1, spinlock_t *ptl2);
 void double_pt_unlock(spinlock_t *ptl1, spinlock_t *ptl2);
 ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
 		   unsigned long src_start, unsigned long len, __u64 flags);
 int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval,
 			struct vm_area_struct *dst_vma,
 			struct vm_area_struct *src_vma,
 			unsigned long dst_addr, unsigned long src_addr);

 /* mm helpers */
 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
 					struct vm_userfaultfd_ctx vm_ctx)
 {
 	return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
 }

 /*
  * Never enable huge pmd sharing on some uffd registered vmas:
  *
  * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
  *
  * - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for
  *   VMAs which share huge pmds. (If you have two mappings to the same
  *   underlying pages, and fault in the non-UFFD-registered one with a write,
  *   with huge pmd sharing this would *also* setup the second UFFD-registered
  *   mapping, and we'd not get minor faults.)
  */
 static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
 {
 	return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
 }

 /*
  * Don't do fault around for either WP or MINOR registered uffd range.  For
  * MINOR registered range, fault around will be a total disaster and ptes can
  * be installed without notifications; for WP it should mostly be fine as long
  * as the fault around checks for pte_none() before the installation, however
  * to be super safe we just forbid it.
  */
 static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
 {
 	return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
 }

 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
 {
 	return vma->vm_flags & VM_UFFD_MISSING;
 }

 static inline bool userfaultfd_wp(struct vm_area_struct *vma)
 {
 	return vma->vm_flags & VM_UFFD_WP;
 }

 static inline bool userfaultfd_minor(struct vm_area_struct *vma)
 {
 	return vma->vm_flags & VM_UFFD_MINOR;
 }

 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_FLAGS;
 }

 static inline bool vma_can_userfault(struct vm_area_struct *vma,
 				     unsigned long vm_flags,
 				     bool wp_async)
 {
 	vm_flags &= __VM_UFFD_FLAGS;

 	if ((vm_flags & VM_UFFD_MINOR) &&
 	    (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
 		return false;

 	/*
 	 * If wp async enabled, and WP is the only mode enabled, allow any
 	 * memory type.
 	 */
 	if (wp_async && (vm_flags == VM_UFFD_WP))
 		return true;

 #ifndef CONFIG_PTE_MARKER_UFFD_WP
 	/*
 	 * If user requested uffd-wp but not enabled pte markers for
 	 * uffd-wp, then shmem & hugetlbfs are not supported but only
 	 * anonymous.
 	 */
 	if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma))
 		return false;
 #endif

 	/* By default, allow any of anon|shmem|hugetlb */
 	return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
 	    vma_is_shmem(vma);
 }

 extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
 extern void dup_userfaultfd_complete(struct list_head *);

 extern void mremap_userfaultfd_prep(struct vm_area_struct *,
 				    struct vm_userfaultfd_ctx *);
 extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
 					unsigned long from, unsigned long to,
 					unsigned long len);

 extern bool userfaultfd_remove(struct vm_area_struct *vma,
 			       unsigned long start,
 			       unsigned long end);

 extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
 		unsigned long start, unsigned long end, struct list_head *uf);
 extern void userfaultfd_unmap_complete(struct mm_struct *mm,
 				       struct list_head *uf);
 extern bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma);
 extern bool userfaultfd_wp_async(struct vm_area_struct *vma);

 #else /* CONFIG_USERFAULTFD */

 /* mm helpers */
 static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
 				unsigned long reason)
 {
 	return VM_FAULT_SIGBUS;
 }

 static inline long uffd_wp_range(struct vm_area_struct *vma,
 				 unsigned long start, unsigned long len,
 				 bool enable_wp)
 {
 	return false;
 }

 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
 					struct vm_userfaultfd_ctx vm_ctx)
 {
 	return true;
 }

 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
 {
 	return false;
 }

 static inline bool userfaultfd_wp(struct vm_area_struct *vma)
 {
 	return false;
 }

 static inline bool userfaultfd_minor(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;
 }

 static inline int dup_userfaultfd(struct vm_area_struct *vma,
 				  struct list_head *l)
 {
 	return 0;
 }

 static inline void dup_userfaultfd_complete(struct list_head *l)
 {
 }

 static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
 					   struct vm_userfaultfd_ctx *ctx)
 {
 }

 static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
 					       unsigned long from,
 					       unsigned long to,
 					       unsigned long len)
 {
 }

 static inline bool userfaultfd_remove(struct vm_area_struct *vma,
 				      unsigned long start,
 				      unsigned long end)
 {
 	return true;
 }

 static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
 					 unsigned long start, unsigned long end,
 					 struct list_head *uf)
 {
 	return 0;
 }

 static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
 					      struct list_head *uf)
 {
 }

 static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
 {
 	return false;
 }

 static inline bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma)
 {
 	return false;
 }

 static inline bool userfaultfd_wp_async(struct vm_area_struct *vma)
 {
 	return false;
 }

 #endif /* CONFIG_USERFAULTFD */

 static inline bool userfaultfd_wp_use_markers(struct vm_area_struct *vma)
 {
 	/* Only wr-protect mode uses pte markers */
 	if (!userfaultfd_wp(vma))
 		return false;

 	/* File-based uffd-wp always need markers */
 	if (!vma_is_anonymous(vma))
 		return true;

 	/*
 	 * Anonymous uffd-wp only needs the markers if WP_UNPOPULATED
 	 * enabled (to apply markers on zero pages).
 	 */
 	return userfaultfd_wp_unpopulated(vma);
 }

 static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry)
 {
 #ifdef CONFIG_PTE_MARKER_UFFD_WP
 	return is_pte_marker_entry(entry) &&
 	    (pte_marker_get(entry) & PTE_MARKER_UFFD_WP);
 #else
 	return false;
 #endif
 }

 static inline bool pte_marker_uffd_wp(pte_t pte)
 {
 #ifdef CONFIG_PTE_MARKER_UFFD_WP
 	swp_entry_t entry;

 	if (!is_swap_pte(pte))
 		return false;

 	entry = pte_to_swp_entry(pte);

 	return pte_marker_entry_uffd_wp(entry);
 #else
 	return false;
 #endif
 }

 /*
  * Returns true if this is a swap pte and was uffd-wp wr-protected in either
  * forms (pte marker or a normal swap pte), false otherwise.
  */
 static inline bool pte_swp_uffd_wp_any(pte_t pte)
 {
 #ifdef CONFIG_PTE_MARKER_UFFD_WP
 	if (!is_swap_pte(pte))
 		return false;

 	if (pte_swp_uffd_wp(pte))
 		return true;

 	if (pte_marker_uffd_wp(pte))
 		return true;
 #endif
 	return false;
 }

 #endif /* _LINUX_USERFAULTFD_K_H */
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* include/linux/userfaultfd_k.h
	*
	* Copyright (C) 2015 Red Hat, Inc.
	*
	*/

	#ifndef _LINUX_USERFAULTFD_K_H
	#define _LINUX_USERFAULTFD_K_H

	#ifdef CONFIG_USERFAULTFD

	#include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */

	#include <linux/fcntl.h>
	#include <linux/mm.h>
	#include <linux/swap.h>
	#include <linux/swapops.h>
	#include <asm-generic/pgtable_uffd.h>
	#include <linux/hugetlb_inline.h>

	/* The set of all possible UFFD-related VM flags. */
	#define __VM_UFFD_FLAGS (VM_UFFD_MISSING \| VM_UFFD_WP \| VM_UFFD_MINOR)

	/*
	* CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
	* new flags, since they might collide with O_* ones. We want
	* to re-use O_* flags that couldn't possibly have a meaning
	* from userfaultfd, in order to leave a free define-space for
	* shared O_* flags.
	*/
	#define UFFD_CLOEXEC O_CLOEXEC
	#define UFFD_NONBLOCK O_NONBLOCK

	#define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC \| O_NONBLOCK)
	#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)

	/*
	* Start with fault_pending_wqh and fault_wqh so they're more likely
	* to be in the same cacheline.
	*
	* Locking order:
	* fd_wqh.lock
	* fault_pending_wqh.lock
	* fault_wqh.lock
	* event_wqh.lock
	*
	* To avoid deadlocks, IRQs must be disabled when taking any of the above locks,
	* since fd_wqh.lock is taken by aio_poll() while it's holding a lock that's
	* also taken in IRQ context.
	*/
	struct userfaultfd_ctx {
	/* waitqueue head for the pending (i.e. not read) userfaults */
	wait_queue_head_t fault_pending_wqh;
	/* waitqueue head for the userfaults */
	wait_queue_head_t fault_wqh;
	/* waitqueue head for the pseudo fd to wakeup poll/read */
	wait_queue_head_t fd_wqh;
	/* waitqueue head for events */
	wait_queue_head_t event_wqh;
	/* a refile sequence protected by fault_pending_wqh lock */
	seqcount_spinlock_t refile_seq;
	/* pseudo fd refcounting */
	refcount_t refcount;
	/* userfaultfd syscall flags */
	unsigned int flags;
	/* features requested from the userspace */
	unsigned int features;
	/* released */
	bool released;
	/*
	* Prevents userfaultfd operations (fill/move/wp) from happening while
	* some non-cooperative event(s) is taking place. Increments are done
	* in write-mode. Whereas, userfaultfd operations, which includes
	* reading mmap_changing, is done under read-mode.
	*/
	struct rw_semaphore map_changing_lock;
	/* memory mappings are changing because of non-cooperative event */
	atomic_t mmap_changing;
	/* mm with one ore more vmas attached to this userfaultfd_ctx */
	struct mm_struct *mm;
	};

	extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);

	/* A combined operation mode + behavior flags. */
	typedef unsigned int __bitwise uffd_flags_t;

	/* Mutually exclusive modes of operation. */
	enum mfill_atomic_mode {
	MFILL_ATOMIC_COPY,
	MFILL_ATOMIC_ZEROPAGE,
	MFILL_ATOMIC_CONTINUE,
	MFILL_ATOMIC_POISON,
	NR_MFILL_ATOMIC_MODES,
	};

	#define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1)
	#define MFILL_ATOMIC_BIT(nr) BIT(MFILL_ATOMIC_MODE_BITS + (nr))
	#define MFILL_ATOMIC_FLAG(nr) ((__force uffd_flags_t) MFILL_ATOMIC_BIT(nr))
	#define MFILL_ATOMIC_MODE_MASK ((__force uffd_flags_t) (MFILL_ATOMIC_BIT(0) - 1))

	static inline bool uffd_flags_mode_is(uffd_flags_t flags, enum mfill_atomic_mode expected)
	{
	return (flags & MFILL_ATOMIC_MODE_MASK) == ((__force uffd_flags_t) expected);
	}

	static inline uffd_flags_t uffd_flags_set_mode(uffd_flags_t flags, enum mfill_atomic_mode mode)
	{
	flags &= ~MFILL_ATOMIC_MODE_MASK;
	return flags \| ((__force uffd_flags_t) mode);
	}

	/* Flags controlling behavior. These behavior changes are mode-independent. */
	#define MFILL_ATOMIC_WP MFILL_ATOMIC_FLAG(0)

	extern int mfill_atomic_install_pte(pmd_t *dst_pmd,
	struct vm_area_struct *dst_vma,
	unsigned long dst_addr, struct page *page,
	bool newly_allocated, uffd_flags_t flags);

	extern ssize_t mfill_atomic_copy(struct userfaultfd_ctx *ctx, unsigned long dst_start,
	unsigned long src_start, unsigned long len,
	uffd_flags_t flags);
	extern ssize_t mfill_atomic_zeropage(struct userfaultfd_ctx *ctx,
	unsigned long dst_start,
	unsigned long len);
	extern ssize_t mfill_atomic_continue(struct userfaultfd_ctx *ctx, unsigned long dst_start,
	unsigned long len, uffd_flags_t flags);
	extern ssize_t mfill_atomic_poison(struct userfaultfd_ctx *ctx, unsigned long start,
	unsigned long len, uffd_flags_t flags);
	extern int mwriteprotect_range(struct userfaultfd_ctx *ctx, unsigned long start,
	unsigned long len, bool enable_wp);
	extern long uffd_wp_range(struct vm_area_struct *vma,
	unsigned long start, unsigned long len, bool enable_wp);

	/* move_pages */
	void double_pt_lock(spinlock_t ptl1, spinlock_t ptl2);
	void double_pt_unlock(spinlock_t ptl1, spinlock_t ptl2);
	ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
	unsigned long src_start, unsigned long len, __u64 flags);
	int move_pages_huge_pmd(struct mm_struct mm, pmd_t dst_pmd, pmd_t *src_pmd, pmd_t dst_pmdval,
	struct vm_area_struct *dst_vma,
	struct vm_area_struct *src_vma,
	unsigned long dst_addr, unsigned long src_addr);

	/* mm helpers */
	static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
	struct vm_userfaultfd_ctx vm_ctx)
	{
	return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
	}

	/*
	* Never enable huge pmd sharing on some uffd registered vmas:
	*
	* - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
	*
	* - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for
	* VMAs which share huge pmds. (If you have two mappings to the same
	* underlying pages, and fault in the non-UFFD-registered one with a write,
	* with huge pmd sharing this would also setup the second UFFD-registered
	* mapping, and we'd not get minor faults.)
	*/
	static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
	{
	return vma->vm_flags & (VM_UFFD_WP \| VM_UFFD_MINOR);
	}

	/*
	* Don't do fault around for either WP or MINOR registered uffd range. For
	* MINOR registered range, fault around will be a total disaster and ptes can
	* be installed without notifications; for WP it should mostly be fine as long
	* as the fault around checks for pte_none() before the installation, however
	* to be super safe we just forbid it.
	*/
	static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
	{
	return vma->vm_flags & (VM_UFFD_WP \| VM_UFFD_MINOR);
	}

	static inline bool userfaultfd_missing(struct vm_area_struct *vma)
	{
	return vma->vm_flags & VM_UFFD_MISSING;
	}

	static inline bool userfaultfd_wp(struct vm_area_struct *vma)
	{
	return vma->vm_flags & VM_UFFD_WP;
	}

	static inline bool userfaultfd_minor(struct vm_area_struct *vma)
	{
	return vma->vm_flags & VM_UFFD_MINOR;
	}

	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_FLAGS;
	}

	static inline bool vma_can_userfault(struct vm_area_struct *vma,
	unsigned long vm_flags,
	bool wp_async)
	{
	vm_flags &= __VM_UFFD_FLAGS;

	if ((vm_flags & VM_UFFD_MINOR) &&
	(!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
	return false;

	/*
	* If wp async enabled, and WP is the only mode enabled, allow any
	* memory type.
	*/
	if (wp_async && (vm_flags == VM_UFFD_WP))
	return true;

	#ifndef CONFIG_PTE_MARKER_UFFD_WP
	/*
	* If user requested uffd-wp but not enabled pte markers for
	* uffd-wp, then shmem & hugetlbfs are not supported but only
	* anonymous.
	*/
	if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma))
	return false;
	#endif

	/* By default, allow any of anon\|shmem\|hugetlb */
	return vma_is_anonymous(vma) \|\| is_vm_hugetlb_page(vma) \|\|
	vma_is_shmem(vma);
	}

	extern int dup_userfaultfd(struct vm_area_struct , struct list_head );
	extern void dup_userfaultfd_complete(struct list_head *);

	extern void mremap_userfaultfd_prep(struct vm_area_struct *,
	struct vm_userfaultfd_ctx *);
	extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
	unsigned long from, unsigned long to,
	unsigned long len);

	extern bool userfaultfd_remove(struct vm_area_struct *vma,
	unsigned long start,
	unsigned long end);

	extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
	unsigned long start, unsigned long end, struct list_head *uf);
	extern void userfaultfd_unmap_complete(struct mm_struct *mm,
	struct list_head *uf);
	extern bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma);
	extern bool userfaultfd_wp_async(struct vm_area_struct *vma);

	#else /* CONFIG_USERFAULTFD */

	/* mm helpers */
	static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
	unsigned long reason)
	{
	return VM_FAULT_SIGBUS;
	}

	static inline long uffd_wp_range(struct vm_area_struct *vma,
	unsigned long start, unsigned long len,
	bool enable_wp)
	{
	return false;
	}

	static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
	struct vm_userfaultfd_ctx vm_ctx)
	{
	return true;
	}

	static inline bool userfaultfd_missing(struct vm_area_struct *vma)
	{
	return false;
	}

	static inline bool userfaultfd_wp(struct vm_area_struct *vma)
	{
	return false;
	}

	static inline bool userfaultfd_minor(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;
	}

	static inline int dup_userfaultfd(struct vm_area_struct *vma,
	struct list_head *l)
	{
	return 0;
	}

	static inline void dup_userfaultfd_complete(struct list_head *l)
	{
	}

	static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
	struct vm_userfaultfd_ctx *ctx)
	{
	}

	static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
	unsigned long from,
	unsigned long to,
	unsigned long len)
	{
	}

	static inline bool userfaultfd_remove(struct vm_area_struct *vma,
	unsigned long start,
	unsigned long end)
	{
	return true;
	}

	static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
	unsigned long start, unsigned long end,
	struct list_head *uf)
	{
	return 0;
	}

	static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
	struct list_head *uf)
	{
	}

	static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
	{
	return false;
	}

	static inline bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma)
	{
	return false;
	}

	static inline bool userfaultfd_wp_async(struct vm_area_struct *vma)
	{
	return false;
	}

	#endif /* CONFIG_USERFAULTFD */

	static inline bool userfaultfd_wp_use_markers(struct vm_area_struct *vma)
	{
	/* Only wr-protect mode uses pte markers */
	if (!userfaultfd_wp(vma))
	return false;

	/* File-based uffd-wp always need markers */
	if (!vma_is_anonymous(vma))
	return true;

	/*
	* Anonymous uffd-wp only needs the markers if WP_UNPOPULATED
	* enabled (to apply markers on zero pages).
	*/
	return userfaultfd_wp_unpopulated(vma);
	}

	static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry)
	{
	#ifdef CONFIG_PTE_MARKER_UFFD_WP
	return is_pte_marker_entry(entry) &&
	(pte_marker_get(entry) & PTE_MARKER_UFFD_WP);
	#else
	return false;
	#endif
	}

	static inline bool pte_marker_uffd_wp(pte_t pte)
	{
	#ifdef CONFIG_PTE_MARKER_UFFD_WP
	swp_entry_t entry;

	if (!is_swap_pte(pte))
	return false;

	entry = pte_to_swp_entry(pte);

	return pte_marker_entry_uffd_wp(entry);
	#else
	return false;
	#endif
	}

	/*
	* Returns true if this is a swap pte and was uffd-wp wr-protected in either
	* forms (pte marker or a normal swap pte), false otherwise.
	*/
	static inline bool pte_swp_uffd_wp_any(pte_t pte)
	{
	#ifdef CONFIG_PTE_MARKER_UFFD_WP
	if (!is_swap_pte(pte))
	return false;

	if (pte_swp_uffd_wp(pte))
	return true;

	if (pte_marker_uffd_wp(pte))
	return true;
	#endif
	return false;
	}

	#endif /* _LINUX_USERFAULTFD_K_H */