Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 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);
59extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
60 unsigned long dst_start,
61 unsigned long len,
62 bool *mmap_changing);
63extern ssize_t mcopy_continue(struct mm_struct *dst_mm, unsigned long dst_start,
64 unsigned long len, bool *mmap_changing);
65extern int mwriteprotect_range(struct mm_struct *dst_mm,
66 unsigned long start, unsigned long len,
67 bool enable_wp, bool *mmap_changing);
68
69/* mm helpers */
70static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
71 struct vm_userfaultfd_ctx vm_ctx)
72{
73 return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
74}
75
76/*
77 * Never enable huge pmd sharing on some uffd registered vmas:
78 *
79 * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
80 *
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.)
86 */
87static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
88{
89 return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
90}
91
92static inline bool userfaultfd_missing(struct vm_area_struct *vma)
93{
94 return vma->vm_flags & VM_UFFD_MISSING;
95}
96
97static inline bool userfaultfd_wp(struct vm_area_struct *vma)
98{
99 return vma->vm_flags & VM_UFFD_WP;
100}
101
102static inline bool userfaultfd_minor(struct vm_area_struct *vma)
103{
104 return vma->vm_flags & VM_UFFD_MINOR;
105}
106
107static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
108 pte_t pte)
109{
110 return userfaultfd_wp(vma) && pte_uffd_wp(pte);
111}
112
113static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
114 pmd_t pmd)
115{
116 return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
117}
118
119static inline bool userfaultfd_armed(struct vm_area_struct *vma)
120{
121 return vma->vm_flags & __VM_UFFD_FLAGS;
122}
123
124extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
125extern void dup_userfaultfd_complete(struct list_head *);
126
127extern void mremap_userfaultfd_prep(struct vm_area_struct *,
128 struct vm_userfaultfd_ctx *);
129extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
130 unsigned long from, unsigned long to,
131 unsigned long len);
132
133extern bool userfaultfd_remove(struct vm_area_struct *vma,
134 unsigned long start,
135 unsigned long end);
136
137extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
138 unsigned long start, unsigned long end,
139 struct list_head *uf);
140extern void userfaultfd_unmap_complete(struct mm_struct *mm,
141 struct list_head *uf);
142
143#else /* CONFIG_USERFAULTFD */
144
145/* mm helpers */
146static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
147 unsigned long reason)
148{
149 return VM_FAULT_SIGBUS;
150}
151
152static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
153 struct vm_userfaultfd_ctx vm_ctx)
154{
155 return true;
156}
157
158static inline bool userfaultfd_missing(struct vm_area_struct *vma)
159{
160 return false;
161}
162
163static inline bool userfaultfd_wp(struct vm_area_struct *vma)
164{
165 return false;
166}
167
168static inline bool userfaultfd_minor(struct vm_area_struct *vma)
169{
170 return false;
171}
172
173static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
174 pte_t pte)
175{
176 return false;
177}
178
179static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
180 pmd_t pmd)
181{
182 return false;
183}
184
185
186static inline bool userfaultfd_armed(struct vm_area_struct *vma)
187{
188 return false;
189}
190
191static inline int dup_userfaultfd(struct vm_area_struct *vma,
192 struct list_head *l)
193{
194 return 0;
195}
196
197static inline void dup_userfaultfd_complete(struct list_head *l)
198{
199}
200
201static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
202 struct vm_userfaultfd_ctx *ctx)
203{
204}
205
206static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
207 unsigned long from,
208 unsigned long to,
209 unsigned long len)
210{
211}
212
213static inline bool userfaultfd_remove(struct vm_area_struct *vma,
214 unsigned long start,
215 unsigned long end)
216{
217 return true;
218}
219
220static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
221 unsigned long start, unsigned long end,
222 struct list_head *uf)
223{
224 return 0;
225}
226
227static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
228 struct list_head *uf)
229{
230}
231
232#endif /* CONFIG_USERFAULTFD */
233
234#endif /* _LINUX_USERFAULTFD_K_H */