LXR linux/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/*
  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 */
  61struct 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
  95struct 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
 117struct uffdio_range {
 118        __u64 start;
 119        __u64 len;
 120};
 121
 122struct 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
 135struct 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
 155struct 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 */
 168