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      1 /*
      2  *  include/linux/userfaultfd.h
      3  *
      4  *  Copyright (C) 2007  Davide Libenzi <davidel (at) 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 */
    168