LXR linux/include/linux/userfaultfd

   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 */
 240