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 /*
  15  * If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and
  16  * UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR.  In
  17  * userfaultfd.h we assumed the kernel was reading (instead _IOC_READ
  18  * means the userland is reading).
  19  */
  20 #define UFFD_API ((__u64)0xAA)
  21 #define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_EXIT |            \
  22                            UFFD_FEATURE_EVENT_FORK |            \
  23                            UFFD_FEATURE_EVENT_REMAP |           \
  24                            UFFD_FEATURE_EVENT_REMOVE |  \
  25                            UFFD_FEATURE_EVENT_UNMAP |           \
  26                            UFFD_FEATURE_MISSING_HUGETLBFS |     \
  27                            UFFD_FEATURE_MISSING_SHMEM)
  28 #define UFFD_API_IOCTLS                         \
  29         ((__u64)1 << _UFFDIO_REGISTER |         \
  30          (__u64)1 << _UFFDIO_UNREGISTER |       \
  31          (__u64)1 << _UFFDIO_API)
  32 #define UFFD_API_RANGE_IOCTLS                   \
  33         ((__u64)1 << _UFFDIO_WAKE |             \
  34          (__u64)1 << _UFFDIO_COPY |             \
  35          (__u64)1 << _UFFDIO_ZEROPAGE)
  36 #define UFFD_API_RANGE_IOCTLS_BASIC             \
  37         ((__u64)1 << _UFFDIO_WAKE |             \
  38          (__u64)1 << _UFFDIO_COPY)
  39
  40 /*
  41  * Valid ioctl command number range with this API is from 0x00 to
  42  * 0x3F.  UFFDIO_API is the fixed number, everything else can be
  43  * changed by implementing a different UFFD_API. If sticking to the
  44  * same UFFD_API more ioctl can be added and userland will be aware of
  45  * which ioctl the running kernel implements through the ioctl command
  46  * bitmask written by the UFFDIO_API.
  47  */
  48 #define _UFFDIO_REGISTER                (0x00)
  49 #define _UFFDIO_UNREGISTER              (0x01)
  50 #define _UFFDIO_WAKE                    (0x02)
  51 #define _UFFDIO_COPY                    (0x03)
  52 #define _UFFDIO_ZEROPAGE                (0x04)
  53 #define _UFFDIO_API                     (0x3F)
  54
  55 /* userfaultfd ioctl ids */
  56 #define UFFDIO 0xAA
  57 #define UFFDIO_API              _IOWR(UFFDIO, _UFFDIO_API,      \
  58                                       struct uffdio_api)
  59 #define UFFDIO_REGISTER         _IOWR(UFFDIO, _UFFDIO_REGISTER, \
  60                                       struct uffdio_register)
  61 #define UFFDIO_UNREGISTER       _IOR(UFFDIO, _UFFDIO_UNREGISTER,        \
  62                                      struct uffdio_range)
  63 #define UFFDIO_WAKE             _IOR(UFFDIO, _UFFDIO_WAKE,      \
  64                                      struct uffdio_range)
  65 #define UFFDIO_COPY             _IOWR(UFFDIO, _UFFDIO_COPY,     \
  66                                       struct uffdio_copy)
  67 #define UFFDIO_ZEROPAGE         _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
  68                                       struct uffdio_zeropage)
  69
  70 /* read() structure */
  71 struct uffd_msg {
  72         __u8    event;
  73
  74         __u8    reserved1;
  75         __u16   reserved2;
  76         __u32   reserved3;
  77
  78         union {
  79                 struct {
  80                         __u64   flags;
  81                         __u64   address;
  82                 } pagefault;
  83
  84                 struct {
  85                         __u32   ufd;
  86                 } fork;
  87
  88                 struct {
  89                         __u64   from;
  90                         __u64   to;
  91                         __u64   len;
  92                 } remap;
  93
  94                 struct {
  95                         __u64   start;
  96                         __u64   end;
  97                 } remove;
  98
  99                 struct {
 100                         /* unused reserved fields */
 101                         __u64   reserved1;
 102                         __u64   reserved2;
 103                         __u64   reserved3;
 104                 } reserved;
 105         } arg;
 106 } __packed;
 107
 108 /*
 109  * Start at 0x12 and not at 0 to be more strict against bugs.
 110  */
 111 #define UFFD_EVENT_PAGEFAULT    0x12
 112 #define UFFD_EVENT_FORK         0x13
 113 #define UFFD_EVENT_REMAP        0x14
 114 #define UFFD_EVENT_REMOVE       0x15
 115 #define UFFD_EVENT_UNMAP        0x16
 116 #define UFFD_EVENT_EXIT         0x17
 117
 118 /* flags for UFFD_EVENT_PAGEFAULT */
 119 #define UFFD_PAGEFAULT_FLAG_WRITE       (1<<0)  /* If this was a write fault */
 120 #define UFFD_PAGEFAULT_FLAG_WP          (1<<1)  /* If reason is VM_UFFD_WP */
 121
 122 struct uffdio_api {
 123         /* userland asks for an API number and the features to enable */
 124         __u64 api;
 125         /*
 126          * Kernel answers below with the all available features for
 127          * the API, this notifies userland of which events and/or
 128          * which flags for each event are enabled in the current
 129          * kernel.
 130          *
 131          * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
 132          * are to be considered implicitly always enabled in all kernels as
 133          * long as the uffdio_api.api requested matches UFFD_API.
 134          *
 135          * UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER
 136          * with UFFDIO_REGISTER_MODE_MISSING mode will succeed on
 137          * hugetlbfs virtual memory ranges. Adding or not adding
 138          * UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has
 139          * no real functional effect after UFFDIO_API returns, but
 140          * it's only useful for an initial feature set probe at
 141          * UFFDIO_API time. There are two ways to use it:
 142          *
 143          * 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the
 144          *    uffdio_api.features before calling UFFDIO_API, an error
 145          *    will be returned by UFFDIO_API on a kernel without
 146          *    hugetlbfs missing support
 147          *
 148          * 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in
 149          *    uffdio_api.features and instead it will be set by the
 150          *    kernel in the uffdio_api.features if the kernel supports
 151          *    it, so userland can later check if the feature flag is
 152          *    present in uffdio_api.features after UFFDIO_API
 153          *    succeeded.
 154          *
 155          * UFFD_FEATURE_MISSING_SHMEM works the same as
 156          * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem
 157          * (i.e. tmpfs and other shmem based APIs).
 158          */
 159 #define UFFD_FEATURE_PAGEFAULT_FLAG_WP          (1<<0)
 160 #define UFFD_FEATURE_EVENT_FORK                 (1<<1)
 161 #define UFFD_FEATURE_EVENT_REMAP                (1<<2)
 162 #define UFFD_FEATURE_EVENT_REMOVE               (1<<3)
 163 #define UFFD_FEATURE_MISSING_HUGETLBFS          (1<<4)
 164 #define UFFD_FEATURE_MISSING_SHMEM              (1<<5)
 165 #define UFFD_FEATURE_EVENT_UNMAP                (1<<6)
 166 #define UFFD_FEATURE_EVENT_EXIT                 (1<<7)
 167         __u64 features;
 168
 169         __u64 ioctls;
 170 };
 171
 172 struct uffdio_range {
 173         __u64 start;
 174         __u64 len;
 175 };
 176
 177 struct uffdio_register {
 178         struct uffdio_range range;
 179 #define UFFDIO_REGISTER_MODE_MISSING    ((__u64)1<<0)
 180 #define UFFDIO_REGISTER_MODE_WP         ((__u64)1<<1)
 181         __u64 mode;
 182
 183         /*
 184          * kernel answers which ioctl commands are available for the
 185          * range, keep at the end as the last 8 bytes aren't read.
 186          */
 187         __u64 ioctls;
 188 };
 189
 190 struct uffdio_copy {
 191         __u64 dst;
 192         __u64 src;
 193         __u64 len;
 194         /*
 195          * There will be a wrprotection flag later that allows to map
 196          * pages wrprotected on the fly. And such a flag will be
 197          * available if the wrprotection ioctl are implemented for the
 198          * range according to the uffdio_register.ioctls.
 199          */
 200 #define UFFDIO_COPY_MODE_DONTWAKE               ((__u64)1<<0)
 201         __u64 mode;
 202
 203         /*
 204          * "copy" is written by the ioctl and must be at the end: the
 205          * copy_from_user will not read the last 8 bytes.
 206          */
 207         __s64 copy;
 208 };
 209
 210 struct uffdio_zeropage {
 211         struct uffdio_range range;
 212 #define UFFDIO_ZEROPAGE_MODE_DONTWAKE           ((__u64)1<<0)
 213         __u64 mode;
 214
 215         /*
 216          * "zeropage" is written by the ioctl and must be at the end:
 217          * the copy_from_user will not read the last 8 bytes.
 218          */
 219         __s64 zeropage;
 220 };
 221
 222 #endif /* _LINUX_USERFAULTFD_H */