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