1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/userfaultfd_k.h
5 * Copyright (C) 2015 Red Hat, Inc.
9 #ifndef _LINUX_USERFAULTFD_K_H
10 #define _LINUX_USERFAULTFD_K_H
12 #ifdef CONFIG_USERFAULTFD
14 #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
16 #include <linux/fcntl.h>
18 #include <linux/swap.h>
19 #include <linux/swapops.h>
20 #include <asm-generic/pgtable_uffd.h>
21 #include <linux/hugetlb_inline.h>
23 /* The set of all possible UFFD-related VM flags. */
24 #define __VM_UFFD_FLAGS (VM_UFFD_MISSING | VM_UFFD_WP | VM_UFFD_MINOR)
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
33 #define UFFD_CLOEXEC O_CLOEXEC
34 #define UFFD_NONBLOCK O_NONBLOCK
36 #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
37 #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
39 extern vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason);
41 /* A combined operation mode + behavior flags. */
42 typedef unsigned int __bitwise uffd_flags_t;
44 /* Mutually exclusive modes of operation. */
45 enum mfill_atomic_mode {
47 MFILL_ATOMIC_ZEROPAGE,
48 MFILL_ATOMIC_CONTINUE,
49 NR_MFILL_ATOMIC_MODES,
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))
57 static inline bool uffd_flags_mode_is(uffd_flags_t flags, enum mfill_atomic_mode expected)
59 return (flags & MFILL_ATOMIC_MODE_MASK) == ((__force uffd_flags_t) expected);
62 static inline uffd_flags_t uffd_flags_set_mode(uffd_flags_t flags, enum mfill_atomic_mode mode)
64 flags &= ~MFILL_ATOMIC_MODE_MASK;
65 return flags | ((__force uffd_flags_t) mode);
68 /* Flags controlling behavior. These behavior changes are mode-independent. */
69 #define MFILL_ATOMIC_WP MFILL_ATOMIC_FLAG(0)
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);
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,
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,
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);
93 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
94 struct vm_userfaultfd_ctx vm_ctx)
96 return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
100 * Never enable huge pmd sharing on some uffd registered vmas:
102 * - VM_UFFD_WP VMAs, because write protect information is per pgtable entry.
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.)
110 static inline bool uffd_disable_huge_pmd_share(struct vm_area_struct *vma)
112 return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
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.
122 static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
124 return vma->vm_flags & (VM_UFFD_WP | VM_UFFD_MINOR);
127 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
129 return vma->vm_flags & VM_UFFD_MISSING;
132 static inline bool userfaultfd_wp(struct vm_area_struct *vma)
134 return vma->vm_flags & VM_UFFD_WP;
137 static inline bool userfaultfd_minor(struct vm_area_struct *vma)
139 return vma->vm_flags & VM_UFFD_MINOR;
142 static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
145 return userfaultfd_wp(vma) && pte_uffd_wp(pte);
148 static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
151 return userfaultfd_wp(vma) && pmd_uffd_wp(pmd);
154 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
156 return vma->vm_flags & __VM_UFFD_FLAGS;
159 static inline bool vma_can_userfault(struct vm_area_struct *vma,
160 unsigned long vm_flags)
162 if ((vm_flags & VM_UFFD_MINOR) &&
163 (!is_vm_hugetlb_page(vma) && !vma_is_shmem(vma)))
165 #ifndef CONFIG_PTE_MARKER_UFFD_WP
167 * If user requested uffd-wp but not enabled pte markers for
168 * uffd-wp, then shmem & hugetlbfs are not supported but only
171 if ((vm_flags & VM_UFFD_WP) && !vma_is_anonymous(vma))
174 return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) ||
178 extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
179 extern void dup_userfaultfd_complete(struct list_head *);
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,
187 extern bool userfaultfd_remove(struct vm_area_struct *vma,
191 extern int userfaultfd_unmap_prep(struct mm_struct *mm, unsigned long start,
192 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);
197 #else /* CONFIG_USERFAULTFD */
200 static inline vm_fault_t handle_userfault(struct vm_fault *vmf,
201 unsigned long reason)
203 return VM_FAULT_SIGBUS;
206 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
207 struct vm_userfaultfd_ctx vm_ctx)
212 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
217 static inline bool userfaultfd_wp(struct vm_area_struct *vma)
222 static inline bool userfaultfd_minor(struct vm_area_struct *vma)
227 static inline bool userfaultfd_pte_wp(struct vm_area_struct *vma,
233 static inline bool userfaultfd_huge_pmd_wp(struct vm_area_struct *vma,
240 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
245 static inline int dup_userfaultfd(struct vm_area_struct *vma,
251 static inline void dup_userfaultfd_complete(struct list_head *l)
255 static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
256 struct vm_userfaultfd_ctx *ctx)
260 static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *ctx,
267 static inline bool userfaultfd_remove(struct vm_area_struct *vma,
274 static inline int userfaultfd_unmap_prep(struct mm_struct *mm,
275 unsigned long start, unsigned long end,
276 struct list_head *uf)
281 static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
282 struct list_head *uf)
286 static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
291 static inline bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma)
296 #endif /* CONFIG_USERFAULTFD */
298 static inline bool userfaultfd_wp_use_markers(struct vm_area_struct *vma)
300 /* Only wr-protect mode uses pte markers */
301 if (!userfaultfd_wp(vma))
304 /* File-based uffd-wp always need markers */
305 if (!vma_is_anonymous(vma))
309 * Anonymous uffd-wp only needs the markers if WP_UNPOPULATED
310 * enabled (to apply markers on zero pages).
312 return userfaultfd_wp_unpopulated(vma);
315 static inline bool pte_marker_entry_uffd_wp(swp_entry_t entry)
317 #ifdef CONFIG_PTE_MARKER_UFFD_WP
318 return is_pte_marker_entry(entry) &&
319 (pte_marker_get(entry) & PTE_MARKER_UFFD_WP);
325 static inline bool pte_marker_uffd_wp(pte_t pte)
327 #ifdef CONFIG_PTE_MARKER_UFFD_WP
330 if (!is_swap_pte(pte))
333 entry = pte_to_swp_entry(pte);
335 return pte_marker_entry_uffd_wp(entry);
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.
345 static inline bool pte_swp_uffd_wp_any(pte_t pte)
347 #ifdef CONFIG_PTE_MARKER_UFFD_WP
348 if (!is_swap_pte(pte))
351 if (pte_swp_uffd_wp(pte))
354 if (pte_marker_uffd_wp(pte))
360 #endif /* _LINUX_USERFAULTFD_K_H */