1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/userfaultfd_k.h
5 * Copyright (C) 2015 Red Hat, Inc.
9 #ifndef _LINUX_USERFAULTFD_K_H
10 #define _LINUX_USERFAULTFD_K_H
12 #ifdef CONFIG_USERFAULTFD
14 #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
16 #include <linux/fcntl.h>
18 #include <asm-generic/pgtable_uffd.h>
20 /* The set of all possible UFFD-related VM flags. */
21 #define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR)
24 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
25 * new flags, since they might collide with O_* ones. We want
26 * to re-use O_* flags that couldn't possibly have a meaning
27 * from userfaultfd, in order to leave a free define-space for
30 #define UFFD_CLOEXEC O_CLOEXEC
31 #define UFFD_NONBLOCK O_NONBLOCK
33 #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
34 #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
36 extern int sysctl_unprivileged_userfaultfd;
38 extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);
41 * The mode of operation for __mcopy_atomic and its helpers.
43 * This is almost an implementation detail (mcopy_atomic below doesn't take this
44 * as a parameter), but it's exposed here because memory-kind-specific
45 * implementations (e.g. hugetlbfs) need to know the mode of operation.
47 enum mcopy_atomic_mode {
48 /* A normal copy_from_user into the destination range. */
50 /* Don't copy; map the destination range to the zero page. */
51 MCOPY_ATOMIC_ZEROPAGE,
52 /* Just install pte(s) with the existing page(s) in the page cache. */
53 MCOPY_ATOMIC_CONTINUE,
56 extern int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
57 struct vm_area_struct *dst_vma,
58 unsigned long dst_addr, struct page *page,
59 bool newly_allocated, bool wp_copy);
61 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
62 unsigned long src_start, unsigned long len,
63 atomic_t *mmap_changing, __u64 mode);
64 extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
65 unsigned long dst_start,
67 atomic_t *mmap_changing);
68 extern ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long dst_start,
69 unsigned long len, atomic_t *mmap_changing);
70 extern int mwriteprotect_range(struct mm_struct *dst_mm,
71 unsigned long start, unsigned long len,
72 bool enable_wp, atomic_t *mmap_changing);
75 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
76 struct vm_userfaultfd_ctx vm_ctx)
78 return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
82 * Never enable huge pmd sharing on some uffd registered vmas:
84 * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
86 * - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for
87 * VMAs which share huge pmds. (If you have two mappings to the same
88 * underlying pages, and fault in the non-UFFD-registered one with a write,
89 * with huge pmd sharing this would *also* setup the second UFFD-registered
90 * mapping, and we'd not get minor faults.)
92 static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
94 return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
97 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
99 return vma->vm_flags & VM_UFFD_MISSING;
102 static inline bool userfaultfd_wp(struct vm_area_struct *vma)
104 return vma->vm_flags & VM_UFFD_WP;
107 static inline bool userfaultfd_minor(struct vm_area_struct *vma)
109 return vma->vm_flags & VM_UFFD_MINOR;
112 static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
115 return userfaultfd_wp(vma) && pte_uffd_wp(pte);
118 static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
121 return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
124 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
126 return vma->vm_flags & __VM_UFFD_FLAGS;
129 extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
130 extern void dup_userfaultfd_complete(struct list_head *);
132 extern void mremap_userfaultfd_prep(struct vm_area_struct *,
133 struct vm_userfaultfd_ctx *);
134 extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
135 unsigned long from, unsigned long to,
138 extern bool userfaultfd_remove(struct vm_area_struct *vma,
142 extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
143 unsigned long start, unsigned long end,
144 struct list_head *uf);
145 extern void userfaultfd_unmap_complete(struct mm_struct *mm,
146 struct list_head *uf);
148 #else /* CONFIG_USERFAULTFD */
151 static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
152 unsigned long reason)
154 return VM_FAULT_SIGBUS;
157 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
158 struct vm_userfaultfd_ctx vm_ctx)
163 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
168 static inline bool userfaultfd_wp(struct vm_area_struct *vma)
173 static inline bool userfaultfd_minor(struct vm_area_struct *vma)
178 static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
184 static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
191 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
196 static inline int dup_userfaultfd(struct vm_area_struct *vma,
202 static inline void dup_userfaultfd_complete(struct list_head *l)
206 static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
207 struct vm_userfaultfd_ctx *ctx)
211 static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
218 static inline bool userfaultfd_remove(struct vm_area_struct *vma,
225 static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
226 unsigned long start, unsigned long end,
227 struct list_head *uf)
232 static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
233 struct list_head *uf)
237 #endif /* CONFIG_USERFAULTFD */
239 #endif /* _LINUX_USERFAULTFD_K_H */