xref: /linux-6.15/include/linux/userfaultfd_k.h (revision d83a7cb3) 
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 extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
56 extern void dup_userfaultfd_complete(struct list_head *);
57 
58 extern void mremap_userfaultfd_prep(struct vm_area_struct *,
59 				    struct vm_userfaultfd_ctx *);
60 extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
61 					unsigned long from, unsigned long to,
62 					unsigned long len);
63 
64 extern void userfaultfd_remove(struct vm_area_struct *vma,
65 			       struct vm_area_struct **prev,
66 			       unsigned long start,
67 			       unsigned long end);
68 
69 extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
70 				  unsigned long start, unsigned long end,
71 				  struct list_head *uf);
72 extern void userfaultfd_unmap_complete(struct mm_struct *mm,
73 				       struct list_head *uf);
74 
75 extern void userfaultfd_exit(struct mm_struct *mm);
76 
77 #else /* CONFIG_USERFAULTFD */
78 
79 /* mm helpers */
80 static inline int handle_userfault(struct vm_fault *vmf, unsigned long reason)
81 {
82 	return VM_FAULT_SIGBUS;
83 }
84 
85 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
86 					struct vm_userfaultfd_ctx vm_ctx)
87 {
88 	return true;
89 }
90 
91 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
92 {
93 	return false;
94 }
95 
96 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
97 {
98 	return false;
99 }
100 
101 static inline int dup_userfaultfd(struct vm_area_struct *vma,
102 				  struct list_head *l)
103 {
104 	return 0;
105 }
106 
107 static inline void dup_userfaultfd_complete(struct list_head *l)
108 {
109 }
110 
111 static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
112 					   struct vm_userfaultfd_ctx *ctx)
113 {
114 }
115 
116 static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
117 					       unsigned long from,
118 					       unsigned long to,
119 					       unsigned long len)
120 {
121 }
122 
123 static inline void userfaultfd_remove(struct vm_area_struct *vma,
124 				      struct vm_area_struct **prev,
125 				      unsigned long start,
126 				      unsigned long end)
127 {
128 }
129 
130 static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
131 					 unsigned long start, unsigned long end,
132 					 struct list_head *uf)
133 {
134 	return 0;
135 }
136 
137 static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
138 					      struct list_head *uf)
139 {
140 }
141 
142 static inline void userfaultfd_exit(struct mm_struct *mm)
143 {
144 }
145 
146 #endif /* CONFIG_USERFAULTFD */
147 
148 #endif /* _LINUX_USERFAULTFD_K_H */
149