xref: /linux-6.15/include/linux/userfaultfd_k.h (revision 6fbd8569) 
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  *  include/linux/userfaultfd_k.h
4  *
5  *  Copyright (C) 2015  Red Hat, Inc.
6  *
7  */
8 
9 #ifndef _LINUX_USERFAULTFD_K_H
10 #define _LINUX_USERFAULTFD_K_H
11 
12 #ifdef CONFIG_USERFAULTFD
13 
14 #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
15 
16 #include <linux/fcntl.h>
17 
18 /*
19  * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
20  * new flags, since they might collide with O_* ones. We want
21  * to re-use O_* flags that couldn't possibly have a meaning
22  * from userfaultfd, in order to leave a free define-space for
23  * shared O_* flags.
24  */
25 #define UFFD_CLOEXEC O_CLOEXEC
26 #define UFFD_NONBLOCK O_NONBLOCK
27 
28 #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
29 #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
30 
31 extern int handle_userfault(struct vm_fault *vmf, unsigned long reason);
32 
33 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
34 			    unsigned long src_start, unsigned long len,
35 			    bool *mmap_changing);
36 extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
37 			      unsigned long dst_start,
38 			      unsigned long len,
39 			      bool *mmap_changing);
40 
41 /* mm helpers */
42 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
43 					struct vm_userfaultfd_ctx vm_ctx)
44 {
45 	return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
46 }
47 
48 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
49 {
50 	return vma->vm_flags & VM_UFFD_MISSING;
51 }
52 
53 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
54 {
55 	return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
56 }
57 
58 extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
59 extern void dup_userfaultfd_complete(struct list_head *);
60 
61 extern void mremap_userfaultfd_prep(struct vm_area_struct *,
62 				    struct vm_userfaultfd_ctx *);
63 extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
64 					unsigned long from, unsigned long to,
65 					unsigned long len);
66 
67 extern bool userfaultfd_remove(struct vm_area_struct *vma,
68 			       unsigned long start,
69 			       unsigned long end);
70 
71 extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
72 				  unsigned long start, unsigned long end,
73 				  struct list_head *uf);
74 extern void userfaultfd_unmap_complete(struct mm_struct *mm,
75 				       struct list_head *uf);
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 bool userfaultfd_remove(struct vm_area_struct *vma,
124 				      unsigned long start,
125 				      unsigned long end)
126 {
127 	return true;
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 #endif /* CONFIG_USERFAULTFD */
143 
144 #endif /* _LINUX_USERFAULTFD_K_H */
145