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