Line data Source code
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 <linux/swap.h>
19 : #include <linux/swapops.h>
20 : #include <asm-generic/pgtable_uffd.h>
21 : #include <linux/hugetlb_inline.h>
22 :
23 : /* The set of all possible UFFD-related VM flags. */
24 : #define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR)
25 :
26 : /*
27 : * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
28 : * new flags, since they might collide with O_* ones. We want
29 : * to re-use O_* flags that couldn't possibly have a meaning
30 : * from userfaultfd, in order to leave a free define-space for
31 : * shared O_* flags.
32 : */
33 : #define UFFD_CLOEXEC O_CLOEXEC
34 : #define UFFD_NONBLOCK O_NONBLOCK
35 :
36 : #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
37 : #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
38 :
39 : extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);
40 :
41 : /* A combined operation mode + behavior flags. */
42 : typedef unsigned int __bitwise uffd_flags_t;
43 :
44 : /* Mutually exclusive modes of operation. */
45 : enum mfill_atomic_mode {
46 : MFILL_ATOMIC_COPY,
47 : MFILL_ATOMIC_ZEROPAGE,
48 : MFILL_ATOMIC_CONTINUE,
49 : NR_MFILL_ATOMIC_MODES,
50 : };
51 :
52 : #define MFILL_ATOMIC_MODE_BITS (const_ilog2(NR_MFILL_ATOMIC_MODES - 1) + 1)
53 : #define MFILL_ATOMIC_BIT(nr) BIT(MFILL_ATOMIC_MODE_BITS + (nr))
54 : #define MFILL_ATOMIC_FLAG(nr) ((__force uffd_flags_t) MFILL_ATOMIC_BIT(nr))
55 : #define MFILL_ATOMIC_MODE_MASK ((__force uffd_flags_t) (MFILL_ATOMIC_BIT(0) - 1))
56 :
57 : static inline bool uffd_flags_mode_is(uffd_flags_t flags, enum mfill_atomic_mode expected)
58 : {
59 : return (flags & MFILL_ATOMIC_MODE_MASK) == ((__force uffd_flags_t) expected);
60 : }
61 :
62 : static inline uffd_flags_t uffd_flags_set_mode(uffd_flags_t flags, enum mfill_atomic_mode mode)
63 : {
64 : flags &= ~MFILL_ATOMIC_MODE_MASK;
65 : return flags | ((__force uffd_flags_t) mode);
66 : }
67 :
68 : /* Flags controlling behavior. These behavior changes are mode-independent. */
69 : #define MFILL_ATOMIC_WP MFILL_ATOMIC_FLAG(0)
70 :
71 : extern int mfill_atomic_install_pte(pmd_t *dst_pmd,
72 : struct vm_area_struct *dst_vma,
73 : unsigned long dst_addr, struct page *page,
74 : bool newly_allocated, uffd_flags_t flags);
75 :
76 : extern ssize_t mfill_atomic_copy(struct mm_struct *dst_mm, unsigned long dst_start,
77 : unsigned long src_start, unsigned long len,
78 : atomic_t *mmap_changing, uffd_flags_t flags);
79 : extern ssize_t mfill_atomic_zeropage(struct mm_struct *dst_mm,
80 : unsigned long dst_start,
81 : unsigned long len,
82 : atomic_t *mmap_changing);
83 : extern ssize_t mfill_atomic_continue(struct mm_struct *dst_mm, unsigned long dst_start,
84 : unsigned long len, atomic_t *mmap_changing,
85 : uffd_flags_t flags);
86 : extern int mwriteprotect_range(struct mm_struct *dst_mm,
87 : unsigned long start, unsigned long len,
88 : bool enable_wp, atomic_t *mmap_changing);
89 : extern long uffd_wp_range(struct vm_area_struct *vma,
90 : unsigned long start, unsigned long len, bool enable_wp);
91 :
92 : /* mm helpers */
93 : static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
94 : struct vm_userfaultfd_ctx vm_ctx)
95 : {
96 : return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
97 : }
98 :
99 : /*
100 : * Never enable huge pmd sharing on some uffd registered vmas:
101 : *
102 : * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
103 : *
104 : * - VM_UFFD_MINOR VMAs, because otherwise we would never get minor faults for
105 : * VMAs which share huge pmds. (If you have two mappings to the same
106 : * underlying pages, and fault in the non-UFFD-registered one with a write,
107 : * with huge pmd sharing this would *also* setup the second UFFD-registered
108 : * mapping, and we'd not get minor faults.)
109 : */
110 : static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
111 : {
112 0 : return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
113 : }
114 :
115 : /*
116 : * Don't do fault around for either WP or MINOR registered uffd range. For
117 : * MINOR registered range, fault around will be a total disaster and ptes can
118 : * be installed without notifications; for WP it should mostly be fine as long
119 : * as the fault around checks for pte_none() before the installation, however
120 : * to be super safe we just forbid it.
121 : */
122 : static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
123 : {
124 : return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
125 : }
126 :
127 : static inline bool userfaultfd_missing(struct vm_area_struct *vma)
128 : {
129 0 : return vma->vm_flags & VM_UFFD_MISSING;
130 : }
131 :
132 : static inline bool userfaultfd_wp(struct vm_area_struct *vma)
133 : {
134 0 : return vma->vm_flags & VM_UFFD_WP;
135 : }
136 :
137 : static inline bool userfaultfd_minor(struct vm_area_struct *vma)
138 : {
139 : return vma->vm_flags & VM_UFFD_MINOR;
140 : }
141 :
142 : static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
143 : pte_t pte)
144 : {
145 : return userfaultfd_wp(vma) && pte_uffd_wp(pte);
146 : }
147 :
148 : static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
149 : pmd_t pmd)
150 : {
151 : return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
152 : }
153 :
154 : static inline bool userfaultfd_armed(struct vm_area_struct *vma)
155 : {
156 : return vma->vm_flags & __VM_UFFD_FLAGS;
157 : }
158 :
159 0 : static inline bool vma_can_userfault(struct vm_area_struct *vma,
160 : unsigned long vm_flags)
161 : {
162 0 : if ((vm_flags & VM_UFFD_MINOR) &&
163 0 : (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
164 : return false;
165 : #ifndef CONFIG_PTE_MARKER_UFFD_WP
166 : /*
167 : * If user requested uffd-wp but not enabled pte markers for
168 : * uffd-wp, then shmem & hugetlbfs are not supported but only
169 : * anonymous.
170 : */
171 : if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma))
172 : return false;
173 : #endif
174 0 : return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
175 0 : vma_is_shmem(vma);
176 : }
177 :
178 : extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
179 : extern void dup_userfaultfd_complete(struct list_head *);
180 :
181 : extern void mremap_userfaultfd_prep(struct vm_area_struct *,
182 : struct vm_userfaultfd_ctx *);
183 : extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *,
184 : unsigned long from, unsigned long to,
185 : unsigned long len);
186 :
187 : extern bool userfaultfd_remove(struct vm_area_struct *vma,
188 : unsigned long start,
189 : unsigned long end);
190 :
191 : extern int userfaultfd_unmap_prep(struct vm_area_struct *vma,
192 : unsigned long start, unsigned long end, struct list_head *uf);
193 : extern void userfaultfd_unmap_complete(struct mm_struct *mm,
194 : struct list_head *uf);
195 : extern bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma);
196 :
197 : #else /* CONFIG_USERFAULTFD */
198 :
199 : /* mm helpers */
200 : static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
201 : unsigned long reason)
202 : {
203 : return VM_FAULT_SIGBUS;
204 : }
205 :
206 : static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
207 : struct vm_userfaultfd_ctx vm_ctx)
208 : {
209 : return true;
210 : }
211 :
212 : static inline bool userfaultfd_missing(struct vm_area_struct *vma)
213 : {
214 : return false;
215 : }
216 :
217 : static inline bool userfaultfd_wp(struct vm_area_struct *vma)
218 : {
219 : return false;
220 : }
221 :
222 : static inline bool userfaultfd_minor(struct vm_area_struct *vma)
223 : {
224 : return false;
225 : }
226 :
227 : static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
228 : pte_t pte)
229 : {
230 : return false;
231 : }
232 :
233 : static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
234 : pmd_t pmd)
235 : {
236 : return false;
237 : }
238 :
239 :
240 : static inline bool userfaultfd_armed(struct vm_area_struct *vma)
241 : {
242 : return false;
243 : }
244 :
245 : static inline int dup_userfaultfd(struct vm_area_struct *vma,
246 : struct list_head *l)
247 : {
248 : return 0;
249 : }
250 :
251 : static inline void dup_userfaultfd_complete(struct list_head *l)
252 : {
253 : }
254 :
255 : static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
256 : struct vm_userfaultfd_ctx *ctx)
257 : {
258 : }
259 :
260 : static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
261 : unsigned long from,
262 : unsigned long to,
263 : unsigned long len)
264 : {
265 : }
266 :
267 : static inline bool userfaultfd_remove(struct vm_area_struct *vma,
268 : unsigned long start,
269 : unsigned long end)
270 : {
271 : return true;
272 : }
273 :
274 : static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
275 : unsigned long start, unsigned long end,
276 : struct list_head *uf)
277 : {
278 : return 0;
279 : }
280 :
281 : static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
282 : struct list_head *uf)
283 : {
284 : }
285 :
286 : static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
287 : {
288 : return false;
289 : }
290 :
291 : static inline bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma)
292 : {
293 : return false;
294 : }
295 :
296 : #endif /* CONFIG_USERFAULTFD */
297 :
298 : static inline bool userfaultfd_wp_use_markers(struct vm_area_struct *vma)
299 : {
300 : /* Only wr-protect mode uses pte markers */
301 : if (!userfaultfd_wp(vma))
302 : return false;
303 :
304 : /* File-based uffd-wp always need markers */
305 : if (!vma_is_anonymous(vma))
306 : return true;
307 :
308 : /*
309 : * Anonymous uffd-wp only needs the markers if WP_UNPOPULATED
310 : * enabled (to apply markers on zero pages).
311 : */
312 : return userfaultfd_wp_unpopulated(vma);
313 : }
314 :
315 : static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry)
316 : {
317 : #ifdef CONFIG_PTE_MARKER_UFFD_WP
318 : return is_pte_marker_entry(entry) &&
319 : (pte_marker_get(entry) & PTE_MARKER_UFFD_WP);
320 : #else
321 : return false;
322 : #endif
323 : }
324 :
325 : static inline bool pte_marker_uffd_wp(pte_t pte)
326 : {
327 : #ifdef CONFIG_PTE_MARKER_UFFD_WP
328 : swp_entry_t entry;
329 :
330 : if (!is_swap_pte(pte))
331 : return false;
332 :
333 : entry = pte_to_swp_entry(pte);
334 :
335 : return pte_marker_entry_uffd_wp(entry);
336 : #else
337 : return false;
338 : #endif
339 : }
340 :
341 : /*
342 : * Returns true if this is a swap pte and was uffd-wp wr-protected in either
343 : * forms (pte marker or a normal swap pte), false otherwise.
344 : */
345 : static inline bool pte_swp_uffd_wp_any(pte_t pte)
346 : {
347 : #ifdef CONFIG_PTE_MARKER_UFFD_WP
348 : if (!is_swap_pte(pte))
349 : return false;
350 :
351 : if (pte_swp_uffd_wp(pte))
352 : return true;
353 :
354 : if (pte_marker_uffd_wp(pte))
355 : return true;
356 : #endif
357 : return false;
358 : }
359 :
360 : #endif /* _LINUX_USERFAULTFD_K_H */
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