include/uapi/linux/userfaultfd.h

   1 /*
   2  *  include/linux/userfaultfd.h
   3  *
   4  *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
   5  *  Copyright (C) 2015  Red Hat, Inc.
   6  *
   7  */
   8
   9 #ifndef _LINUX_USERFAULTFD_H
  10 #define _LINUX_USERFAULTFD_H
  11
  12 #include <linux/types.h>
  13
  14 #define UFFD_API ((__u64)0xAA)
  15 /* FIXME: add "|UFFD_FEATURE_WP" to UFFD_API_FEATURES after implementing it */
  16 #define UFFD_API_FEATURES (UFFD_FEATURE_WRITE_BIT)
  17 #define UFFD_API_IOCTLS                         \
  18         ((__u64)1 << _UFFDIO_REGISTER |         \
  19          (__u64)1 << _UFFDIO_UNREGISTER |       \
  20          (__u64)1 << _UFFDIO_API)
  21 #define UFFD_API_RANGE_IOCTLS                   \
  22         ((__u64)1 << _UFFDIO_WAKE)
  23
  24 /*
  25  * Valid ioctl command number range with this API is from 0x00 to
  26  * 0x3F.  UFFDIO_API is the fixed number, everything else can be
  27  * changed by implementing a different UFFD_API. If sticking to the
  28  * same UFFD_API more ioctl can be added and userland will be aware of
  29  * which ioctl the running kernel implements through the ioctl command
  30  * bitmask written by the UFFDIO_API.
  31  */
  32 #define _UFFDIO_REGISTER                (0x00)
  33 #define _UFFDIO_UNREGISTER              (0x01)
  34 #define _UFFDIO_WAKE                    (0x02)
  35 #define _UFFDIO_API                     (0x3F)
  36
  37 /* userfaultfd ioctl ids */
  38 #define UFFDIO 0xAA
  39 #define UFFDIO_API              _IOWR(UFFDIO, _UFFDIO_API,      \
  40                                       struct uffdio_api)
  41 #define UFFDIO_REGISTER         _IOWR(UFFDIO, _UFFDIO_REGISTER, \
  42                                       struct uffdio_register)
  43 #define UFFDIO_UNREGISTER       _IOR(UFFDIO, _UFFDIO_UNREGISTER,        \
  44                                      struct uffdio_range)
  45 #define UFFDIO_WAKE             _IOR(UFFDIO, _UFFDIO_WAKE,      \
  46                                      struct uffdio_range)
  47
  48 /*
  49  * Valid bits below PAGE_SHIFT in the userfault address read through
  50  * the read() syscall.
  51  */
  52 #define UFFD_BIT_WRITE  (1<<0)  /* this was a write fault, MISSING or WP */
  53 #define UFFD_BIT_WP     (1<<1)  /* handle_userfault() reason VM_UFFD_WP */
  54 #define UFFD_BITS       2       /* two above bits used for UFFD_BIT_* mask */
  55
  56 /*
  57  * Features reported in uffdio_api.features field
  58  */
  59 #define UFFD_FEATURE_WRITE_BIT  (1<<0) /* Corresponds to UFFD_BIT_WRITE */
  60 #define UFFD_FEATURE_WP_BIT     (1<<1) /* Corresponds to UFFD_BIT_WP */
  61
  62 struct uffdio_api {
  63         /* userland asks for an API number */
  64         __u64 api;
  65
  66         /* kernel answers below with the available features for the API */
  67         __u64 features;
  68         __u64 ioctls;
  69 };
  70
  71 struct uffdio_range {
  72         __u64 start;
  73         __u64 len;
  74 };
  75
  76 struct uffdio_register {
  77         struct uffdio_range range;
  78 #define UFFDIO_REGISTER_MODE_MISSING    ((__u64)1<<0)
  79 #define UFFDIO_REGISTER_MODE_WP         ((__u64)1<<1)
  80         __u64 mode;
  81
  82         /*
  83          * kernel answers which ioctl commands are available for the
  84          * range, keep at the end as the last 8 bytes aren't read.
  85          */
  86         __u64 ioctls;
  87 };
  88
  89 #endif /* _LINUX_USERFAULTFD_H */