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1 /*
2 * include/linux/userfaultfd_k.h
3 *
4 * Copyright (C) 2015 Red Hat, Inc.
5 *
6 */
7
8 #ifndef _LINUX_USERFAULTFD_K_H
9 #define _LINUX_USERFAULTFD_K_H
10
11 #ifdef CONFIG_USERFAULTFD
12
13 #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
14
15 #include <linux/fcntl.h>
16
17 /*
18 * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
19 * new flags, since they might collide with O_* ones. We want
20 * to re-use O_* flags that couldn't possibly have a meaning
21 * from userfaultfd, in order to leave a free define-space for
22 * shared O_* flags.
23 */
24 #define UFFD_CLOEXEC O_CLOEXEC
25 #define UFFD_NONBLOCK O_NONBLOCK
26
27 #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
28 #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
29
30 extern int handle_userfault(struct vm_fault *vmf, unsigned long reason);
31
32 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
33 unsigned long src_start, unsigned long len);
34 extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
35 unsigned long dst_start,
36 unsigned long len);
37
38 /* mm helpers */
39 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
40 struct vm_userfaultfd_ctx vm_ctx)
41 {
42 return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
43 }
44
45 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
46 {
47 return vma->vm_flags & VM_UFFD_MISSING;
48 }
49
50 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
51 {
52 return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
53 }
54
55 #else /* CONFIG_USERFAULTFD */
56
57 /* mm helpers */
58 static inline int handle_userfault(struct vm_fault *vmf, unsigned long reason)
59 {
60 return VM_FAULT_SIGBUS;
61 }
62
63 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
64 struct vm_userfaultfd_ctx vm_ctx)
65 {
66 return true;
67 }
68
69 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
70 {
71 return false;
72 }
73
74 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
75 {
76 return false;
77 }
78
79 #endif /* CONFIG_USERFAULTFD */
80
81 #endif /* _LINUX_USERFAULTFD_K_H */