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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#include <linux/mm.h>
18#include <asm-generic/pgtable_uffd.h>
19
20/* The set of all possible UFFD-related VM flags. */
21#define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR)
22
23/*
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
28 * shared O_* flags.
29 */
30#define UFFD_CLOEXEC O_CLOEXEC
31#define UFFD_NONBLOCK O_NONBLOCK
32
33#define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
34#define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
35
36extern int sysctl_unprivileged_userfaultfd;
37
38extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);
39
40/*
41 * The mode of operation for __mcopy_atomic and its helpers.
42 *
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.
46 */
47enum mcopy_atomic_mode {
48 /* A normal copy_from_user into the destination range. */
49 MCOPY_ATOMIC_NORMAL,
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,
54};
55
56extern 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);
60
61extern 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);
64extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
65 unsigned long dst_start,
66 unsigned long len,
67 atomic_t *mmap_changing);
68extern ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long dst_start,
69 unsigned long len, atomic_t *mmap_changing);
70extern int mwriteprotect_range(struct mm_struct *dst_mm,
71 unsigned long start, unsigned long len,
72 bool enable_wp, atomic_t *mmap_changing);
73
74/* mm helpers */
75static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
76 struct vm_userfaultfd_ctx vm_ctx)
77{
78 return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
79}
80
81/*
82 * Never enable huge pmd sharing on some uffd registered vmas:
83 *
84 * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
85 *
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.)
91 */
92static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
93{
94 return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
95}
96
97static inline bool userfaultfd_missing(struct vm_area_struct *vma)
98{
99 return vma->vm_flags & VM_UFFD_MISSING;
100}
101
102static inline bool userfaultfd_wp(struct vm_area_struct *vma)
103{
104 return vma->vm_flags & VM_UFFD_WP;
105}
106
107static inline bool userfaultfd_minor(struct vm_area_struct *vma)
108{
109 return vma->vm_flags & VM_UFFD_MINOR;
110}
111
112static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
113 pte_t pte)
114{
115 return userfaultfd_wp(vma) && pte_uffd_wp(pte);
116}
117
118static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
119 pmd_t pmd)
120{
121 return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
122}
123
124static inline bool userfaultfd_armed(struct vm_area_struct *vma)
125{
126 return vma->vm_flags & __VM_UFFD_FLAGS;
127}
128
129extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
130extern void dup_userfaultfd_complete(struct list_head *);
131
132extern void mremap_userfaultfd_prep(struct vm_area_struct *,
133 struct vm_userfaultfd_ctx *);
134extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
135 unsigned long from, unsigned long to,
136 unsigned long len);
137
138extern bool userfaultfd_remove(struct vm_area_struct *vma,
139 unsigned long start,
140 unsigned long end);
141
142extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
143 unsigned long start, unsigned long end,
144 struct list_head *uf);
145extern void userfaultfd_unmap_complete(struct mm_struct *mm,
146 struct list_head *uf);
147
148#else /* CONFIG_USERFAULTFD */
149
150/* mm helpers */
151static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
152 unsigned long reason)
153{
154 return VM_FAULT_SIGBUS;
155}
156
157static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
158 struct vm_userfaultfd_ctx vm_ctx)
159{
160 return true;
161}
162
163static inline bool userfaultfd_missing(struct vm_area_struct *vma)
164{
165 return false;
166}
167
168static inline bool userfaultfd_wp(struct vm_area_struct *vma)
169{
170 return false;
171}
172
173static inline bool userfaultfd_minor(struct vm_area_struct *vma)
174{
175 return false;
176}
177
178static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
179 pte_t pte)
180{
181 return false;
182}
183
184static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
185 pmd_t pmd)
186{
187 return false;
188}
189
190
191static inline bool userfaultfd_armed(struct vm_area_struct *vma)
192{
193 return false;
194}
195
196static inline int dup_userfaultfd(struct vm_area_struct *vma,
197 struct list_head *l)
198{
199 return 0;
200}
201
202static inline void dup_userfaultfd_complete(struct list_head *l)
203{
204}
205
206static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
207 struct vm_userfaultfd_ctx *ctx)
208{
209}
210
211static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
212 unsigned long from,
213 unsigned long to,
214 unsigned long len)
215{
216}
217
218static inline bool userfaultfd_remove(struct vm_area_struct *vma,
219 unsigned long start,
220 unsigned long end)
221{
222 return true;
223}
224
225static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
226 unsigned long start, unsigned long end,
227 struct list_head *uf)
228{
229 return 0;
230}
231
232static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
233 struct list_head *uf)
234{
235}
236
237#endif /* CONFIG_USERFAULTFD */
238
239#endif /* _LINUX_USERFAULTFD_K_H */