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 #include <linux/compiler.h>
  15
  16 #define UFFD_API ((__u64)0xAA)
  17 /*
  18  * After implementing the respective features it will become:
  19  * #define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | \
  20  *                            UFFD_FEATURE_EVENT_FORK)
  21  */
  22 #define UFFD_API_FEATURES (0)
  23 #define UFFD_API_IOCTLS                         \
  24         ((__u64)1 << _UFFDIO_REGISTER |         \
  25          (__u64)1 << _UFFDIO_UNREGISTER |       \
  26          (__u64)1 << _UFFDIO_API)
  27 #define UFFD_API_RANGE_IOCTLS                   \
  28         ((__u64)1 << _UFFDIO_WAKE |             \
  29          (__u64)1 << _UFFDIO_COPY |             \
  30          (__u64)1 << _UFFDIO_ZEROPAGE)
  31
  32 /*
  33  * Valid ioctl command number range with this API is from 0x00 to
  34  * 0x3F.  UFFDIO_API is the fixed number, everything else can be
  35  * changed by implementing a different UFFD_API. If sticking to the
  36  * same UFFD_API more ioctl can be added and userland will be aware of
  37  * which ioctl the running kernel implements through the ioctl command
  38  * bitmask written by the UFFDIO_API.
  39  */
  40 #define _UFFDIO_REGISTER                (0x00)
  41 #define _UFFDIO_UNREGISTER              (0x01)
  42 #define _UFFDIO_WAKE                    (0x02)
  43 #define _UFFDIO_COPY                    (0x03)
  44 #define _UFFDIO_ZEROPAGE                (0x04)
  45 #define _UFFDIO_API                     (0x3F)
  46
  47 /* userfaultfd ioctl ids */
  48 #define UFFDIO 0xAA
  49 #define UFFDIO_API              _IOWR(UFFDIO, _UFFDIO_API,      \
  50                                       struct uffdio_api)
  51 #define UFFDIO_REGISTER         _IOWR(UFFDIO, _UFFDIO_REGISTER, \
  52                                       struct uffdio_register)
  53 #define UFFDIO_UNREGISTER       _IOR(UFFDIO, _UFFDIO_UNREGISTER,        \
  54                                      struct uffdio_range)
  55 #define UFFDIO_WAKE             _IOR(UFFDIO, _UFFDIO_WAKE,      \
  56                                      struct uffdio_range)
  57 #define UFFDIO_COPY             _IOWR(UFFDIO, _UFFDIO_COPY,     \
  58                                       struct uffdio_copy)
  59 #define UFFDIO_ZEROPAGE         _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
  60                                       struct uffdio_zeropage)
  61
  62 /* read() structure */
  63 struct uffd_msg {
  64         __u8    event;
  65
  66         __u8    reserved1;
  67         __u16   reserved2;
  68         __u32   reserved3;
  69
  70         union {
  71                 struct {
  72                         __u64   flags;
  73                         __u64   address;
  74                 } pagefault;
  75
  76                 struct {
  77                         /* unused reserved fields */
  78                         __u64   reserved1;
  79                         __u64   reserved2;
  80                         __u64   reserved3;
  81                 } reserved;
  82         } arg;
  83 } __packed;
  84
  85 /*
  86  * Start at 0x12 and not at 0 to be more strict against bugs.
  87  */
  88 #define UFFD_EVENT_PAGEFAULT    0x12
  89 #if 0 /* not available yet */
  90 #define UFFD_EVENT_FORK         0x13
  91 #endif
  92
  93 /* flags for UFFD_EVENT_PAGEFAULT */
  94 #define UFFD_PAGEFAULT_FLAG_WRITE       (1<<0)  /* If this was a write fault */
  95 #define UFFD_PAGEFAULT_FLAG_WP          (1<<1)  /* If reason is VM_UFFD_WP */
  96
  97 struct uffdio_api {
  98         /* userland asks for an API number and the features to enable */
  99         __u64 api;
 100         /*
 101          * Kernel answers below with the all available features for
 102          * the API, this notifies userland of which events and/or
 103          * which flags for each event are enabled in the current
 104          * kernel.
 105          *
 106          * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
 107          * are to be considered implicitly always enabled in all kernels as
 108          * long as the uffdio_api.api requested matches UFFD_API.
 109          */
 110 #if 0 /* not available yet */
 111 #define UFFD_FEATURE_PAGEFAULT_FLAG_WP          (1<<0)
 112 #define UFFD_FEATURE_EVENT_FORK                 (1<<1)
 113 #endif
 114         __u64 features;
 115
 116         __u64 ioctls;
 117 };
 118
 119 struct uffdio_range {
 120         __u64 start;
 121         __u64 len;
 122 };
 123
 124 struct uffdio_register {
 125         struct uffdio_range range;
 126 #define UFFDIO_REGISTER_MODE_MISSING    ((__u64)1<<0)
 127 #define UFFDIO_REGISTER_MODE_WP         ((__u64)1<<1)
 128         __u64 mode;
 129
 130         /*
 131          * kernel answers which ioctl commands are available for the
 132          * range, keep at the end as the last 8 bytes aren't read.
 133          */
 134         __u64 ioctls;
 135 };
 136
 137 struct uffdio_copy {
 138         __u64 dst;
 139         __u64 src;
 140         __u64 len;
 141         /*
 142          * There will be a wrprotection flag later that allows to map
 143          * pages wrprotected on the fly. And such a flag will be
 144          * available if the wrprotection ioctl are implemented for the
 145          * range according to the uffdio_register.ioctls.
 146          */
 147 #define UFFDIO_COPY_MODE_DONTWAKE               ((__u64)1<<0)
 148         __u64 mode;
 149
 150         /*
 151          * "copy" is written by the ioctl and must be at the end: the
 152          * copy_from_user will not read the last 8 bytes.
 153          */
 154         __s64 copy;
 155 };
 156
 157 struct uffdio_zeropage {
 158         struct uffdio_range range;
 159 #define UFFDIO_ZEROPAGE_MODE_DONTWAKE           ((__u64)1<<0)
 160         __u64 mode;
 161
 162         /*
 163          * "zeropage" is written by the ioctl and must be at the end:
 164          * the copy_from_user will not read the last 8 bytes.
 165          */
 166         __s64 zeropage;
 167 };
 168
 169 #endif /* _LINUX_USERFAULTFD_H */