include/linux/userfaultfd_k.h

   1 /*
   2  *  include/linux/userfaultfd_k.h
   3  *
   4  *  Copyright (C) 2015  Red Hat, Inc.
   5  *
   6  */
   7
   8 #ifndef _LINUX_USERFAULTFD_K_H
   9 #define _LINUX_USERFAULTFD_K_H
  10
  11 #ifdef CONFIG_USERFAULTFD
  12
  13 #include <linux/userfaultfd.h> /* linux/include/uapi/linux/userfaultfd.h */
  14
  15 #include <linux/fcntl.h>
  16
  17 /*
  18  * CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
  19  * new flags, since they might collide with O_* ones. We want
  20  * to re-use O_* flags that couldn't possibly have a meaning
  21  * from userfaultfd, in order to leave a free define-space for
  22  * shared O_* flags.
  23  */
  24 #define UFFD_CLOEXEC O_CLOEXEC
  25 #define UFFD_NONBLOCK O_NONBLOCK
  26
  27 #define UFFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
  28 #define UFFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS)
  29
  30 extern int handle_userfault(struct vm_area_struct *vma, unsigned long address,
  31                             unsigned int flags, unsigned long reason);
  32
  33 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
  34                             unsigned long src_start, unsigned long len);
  35 extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
  36                               unsigned long dst_start,
  37                               unsigned long len);
  38
  39 /* mm helpers */
  40 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
  41                                         struct vm_userfaultfd_ctx vm_ctx)
  42 {
  43         return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
  44 }
  45
  46 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
  47 {
  48         return vma->vm_flags & VM_UFFD_MISSING;
  49 }
  50
  51 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
  52 {
  53         return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
  54 }
  55
  56 #else /* CONFIG_USERFAULTFD */
  57
  58 /* mm helpers */
  59 static inline int handle_userfault(struct vm_area_struct *vma,
  60                                    unsigned long address,
  61                                    unsigned int flags,
  62                                    unsigned long reason)
  63 {
  64         return VM_FAULT_SIGBUS;
  65 }
  66
  67 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
  68                                         struct vm_userfaultfd_ctx vm_ctx)
  69 {
  70         return true;
  71 }
  72
  73 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
  74 {
  75         return false;
  76 }
  77
  78 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
  79 {
  80         return false;
  81 }
  82
  83 #endif /* CONFIG_USERFAULTFD */
  84
  85 #endif /* _LINUX_USERFAULTFD_K_H */