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_fault *vmf, unsigned long reason);
  31
  32 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start,
  33                             unsigned long src_start, unsigned long len);
  34 extern ssize_t mfill_zeropage(struct mm_struct *dst_mm,
  35                               unsigned long dst_start,
  36                               unsigned long len);
  37
  38 /* mm helpers */
  39 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
  40                                         struct vm_userfaultfd_ctx vm_ctx)
  41 {
  42         return vma->vm_userfaultfd_ctx.ctx == vm_ctx.ctx;
  43 }
  44
  45 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
  46 {
  47         return vma->vm_flags & VM_UFFD_MISSING;
  48 }
  49
  50 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
  51 {
  52         return vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP);
  53 }
  54
  55 #else /* CONFIG_USERFAULTFD */
  56
  57 /* mm helpers */
  58 static inline int handle_userfault(struct vm_fault *vmf, unsigned long reason)
  59 {
  60         return VM_FAULT_SIGBUS;
  61 }
  62
  63 static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
  64                                         struct vm_userfaultfd_ctx vm_ctx)
  65 {
  66         return true;
  67 }
  68
  69 static inline bool userfaultfd_missing(struct vm_area_struct *vma)
  70 {
  71         return false;
  72 }
  73
  74 static inline bool userfaultfd_armed(struct vm_area_struct *vma)
  75 {
  76         return false;
  77 }
  78
  79 #endif /* CONFIG_USERFAULTFD */
  80
  81 #endif /* _LINUX_USERFAULTFD_K_H */