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 ssize_t
mcopy_atomic(struct mm_struct
*dst_mm
, unsigned long dst_start
,
57 unsigned long src_start
, unsigned long len
,
58 bool *mmap_changing
, __u64 mode
);
59 extern ssize_t
mfill_zeropage(struct mm_struct
*dst_mm
,
60 unsigned long dst_start
,
63 extern ssize_t
mcopy_continue(struct mm_struct
*dst_mm
, unsigned long dst_start
,
64 unsigned long len
, bool *mmap_changing
);
65 extern int mwriteprotect_range(struct mm_struct
*dst_mm
,
66 unsigned long start
, unsigned long len
,
67 bool enable_wp
, bool *mmap_changing
);
70 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct
*vma
,
71 struct vm_userfaultfd_ctx vm_ctx
)
73 return vma
->vm_userfaultfd_ctx
.ctx
== vm_ctx
.ctx
;
77 * Never enable huge pmd sharing on some uffd registered vmas:
79 * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
81 * - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for
82 * VMAs which share huge pmds. (If you have two mappings to the same
83 * underlying pages, and fault in the non-UFFD-registered one with a write,
84 * with huge pmd sharing this would *also* setup the second UFFD-registered
85 * mapping, and we'd not get minor faults.)
87 static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct
*vma
)
89 return vma
->vm_flags
& (VM_UFFD_WP
| VM_UFFD_MINOR
);
92 static inline bool userfaultfd_missing(struct vm_area_struct
*vma
)
94 return vma
->vm_flags
& VM_UFFD_MISSING
;
97 static inline bool userfaultfd_wp(struct vm_area_struct
*vma
)
99 return vma
->vm_flags
& VM_UFFD_WP
;
102 static inline bool userfaultfd_minor(struct vm_area_struct
*vma
)
104 return vma
->vm_flags
& VM_UFFD_MINOR
;
107 static inline bool userfaultfd_pte_wp(struct vm_area_struct
*vma
,
110 return userfaultfd_wp(vma
) && pte_uffd_wp(pte
);
113 static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct
*vma
,
116 return userfaultfd_wp(vma
) && pmd_uffd_wp(pmd
);
119 static inline bool userfaultfd_armed(struct vm_area_struct
*vma
)
121 return vma
->vm_flags
& __VM_UFFD_FLAGS
;
124 extern int dup_userfaultfd(struct vm_area_struct
*, struct list_head
*);
125 extern void dup_userfaultfd_complete(struct list_head
*);
127 extern void mremap_userfaultfd_prep(struct vm_area_struct
*,
128 struct vm_userfaultfd_ctx
*);
129 extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx
*,
130 unsigned long from
, unsigned long to
,
133 extern bool userfaultfd_remove(struct vm_area_struct
*vma
,
137 extern int userfaultfd_unmap_prep(struct vm_area_struct
*vma
,
138 unsigned long start
, unsigned long end
,
139 struct list_head
*uf
);
140 extern void userfaultfd_unmap_complete(struct mm_struct
*mm
,
141 struct list_head
*uf
);
143 #else /* CONFIG_USERFAULTFD */
146 static inline vm_fault_t
handle_userfault(struct vm_fault
*vmf
,
147 unsigned long reason
)
149 return VM_FAULT_SIGBUS
;
152 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct
*vma
,
153 struct vm_userfaultfd_ctx vm_ctx
)
158 static inline bool userfaultfd_missing(struct vm_area_struct
*vma
)
163 static inline bool userfaultfd_wp(struct vm_area_struct
*vma
)
168 static inline bool userfaultfd_minor(struct vm_area_struct
*vma
)
173 static inline bool userfaultfd_pte_wp(struct vm_area_struct
*vma
,
179 static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct
*vma
,
186 static inline bool userfaultfd_armed(struct vm_area_struct
*vma
)
191 static inline int dup_userfaultfd(struct vm_area_struct
*vma
,
197 static inline void dup_userfaultfd_complete(struct list_head
*l
)
201 static inline void mremap_userfaultfd_prep(struct vm_area_struct
*vma
,
202 struct vm_userfaultfd_ctx
*ctx
)
206 static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx
*ctx
,
213 static inline bool userfaultfd_remove(struct vm_area_struct
*vma
,
220 static inline int userfaultfd_unmap_prep(struct vm_area_struct
*vma
,
221 unsigned long start
, unsigned long end
,
222 struct list_head
*uf
)
227 static inline void userfaultfd_unmap_complete(struct mm_struct
*mm
,
228 struct list_head
*uf
)
232 #endif /* CONFIG_USERFAULTFD */
234 #endif /* _LINUX_USERFAULTFD_K_H */