[mirror_qemu.git] / linux-headers / linux / userfaultfd.h

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
 *  include/linux/userfaultfd.h
 *
 *  Copyright (C) 2007  Davide Libenzi <davidel@xmailserver.org>
 *  Copyright (C) 2015  Red Hat, Inc.
 *
 */

#ifndef _LINUX_USERFAULTFD_H
#define _LINUX_USERFAULTFD_H

#include <linux/types.h>

/* ioctls for /dev/userfaultfd */
#define USERFAULTFD_IOC 0xAA
#define USERFAULTFD_IOC_NEW _IO(USERFAULTFD_IOC, 0x00)

/*
 * If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and
 * UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR.  In
 * userfaultfd.h we assumed the kernel was reading (instead _IOC_READ
 * means the userland is reading).
 */
#define UFFD_API ((__u64)0xAA)
#define UFFD_API_REGISTER_MODES (UFFDIO_REGISTER_MODE_MISSING |	\
				 UFFDIO_REGISTER_MODE_WP |	\
				 UFFDIO_REGISTER_MODE_MINOR)
#define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP |	\
			   UFFD_FEATURE_EVENT_FORK |		\
			   UFFD_FEATURE_EVENT_REMAP |		\
			   UFFD_FEATURE_EVENT_REMOVE |		\
			   UFFD_FEATURE_EVENT_UNMAP |		\
			   UFFD_FEATURE_MISSING_HUGETLBFS |	\
			   UFFD_FEATURE_MISSING_SHMEM |		\
			   UFFD_FEATURE_SIGBUS |		\
			   UFFD_FEATURE_THREAD_ID |		\
			   UFFD_FEATURE_MINOR_HUGETLBFS |	\
			   UFFD_FEATURE_MINOR_SHMEM |		\
			   UFFD_FEATURE_EXACT_ADDRESS |		\
			   UFFD_FEATURE_WP_HUGETLBFS_SHMEM |	\
			   UFFD_FEATURE_WP_UNPOPULATED |	\
			   UFFD_FEATURE_POISON |		\
			   UFFD_FEATURE_WP_ASYNC)
#define UFFD_API_IOCTLS				\
	((__u64)1 << _UFFDIO_REGISTER |		\
	 (__u64)1 << _UFFDIO_UNREGISTER |	\
	 (__u64)1 << _UFFDIO_API)
#define UFFD_API_RANGE_IOCTLS			\
	((__u64)1 << _UFFDIO_WAKE |		\
	 (__u64)1 << _UFFDIO_COPY |		\
	 (__u64)1 << _UFFDIO_ZEROPAGE |		\
	 (__u64)1 << _UFFDIO_WRITEPROTECT |	\
	 (__u64)1 << _UFFDIO_CONTINUE |		\
	 (__u64)1 << _UFFDIO_POISON)
#define UFFD_API_RANGE_IOCTLS_BASIC		\
	((__u64)1 << _UFFDIO_WAKE |		\
	 (__u64)1 << _UFFDIO_COPY |		\
	 (__u64)1 << _UFFDIO_WRITEPROTECT |	\
	 (__u64)1 << _UFFDIO_CONTINUE |		\
	 (__u64)1 << _UFFDIO_POISON)

/*
 * Valid ioctl command number range with this API is from 0x00 to
 * 0x3F.  UFFDIO_API is the fixed number, everything else can be
 * changed by implementing a different UFFD_API. If sticking to the
 * same UFFD_API more ioctl can be added and userland will be aware of
 * which ioctl the running kernel implements through the ioctl command
 * bitmask written by the UFFDIO_API.
 */
#define _UFFDIO_REGISTER		(0x00)
#define _UFFDIO_UNREGISTER		(0x01)
#define _UFFDIO_WAKE			(0x02)
#define _UFFDIO_COPY			(0x03)
#define _UFFDIO_ZEROPAGE		(0x04)
#define _UFFDIO_WRITEPROTECT		(0x06)
#define _UFFDIO_CONTINUE		(0x07)
#define _UFFDIO_POISON			(0x08)
#define _UFFDIO_API			(0x3F)

/* userfaultfd ioctl ids */
#define UFFDIO 0xAA
#define UFFDIO_API		_IOWR(UFFDIO, _UFFDIO_API,	\
				      struct uffdio_api)
#define UFFDIO_REGISTER		_IOWR(UFFDIO, _UFFDIO_REGISTER, \
				      struct uffdio_register)
#define UFFDIO_UNREGISTER	_IOR(UFFDIO, _UFFDIO_UNREGISTER,	\
				     struct uffdio_range)
#define UFFDIO_WAKE		_IOR(UFFDIO, _UFFDIO_WAKE,	\
				     struct uffdio_range)
#define UFFDIO_COPY		_IOWR(UFFDIO, _UFFDIO_COPY,	\
				      struct uffdio_copy)
#define UFFDIO_ZEROPAGE		_IOWR(UFFDIO, _UFFDIO_ZEROPAGE,	\
				      struct uffdio_zeropage)
#define UFFDIO_WRITEPROTECT	_IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \
				      struct uffdio_writeprotect)
#define UFFDIO_CONTINUE		_IOWR(UFFDIO, _UFFDIO_CONTINUE,	\
				      struct uffdio_continue)
#define UFFDIO_POISON		_IOWR(UFFDIO, _UFFDIO_POISON, \
				      struct uffdio_poison)

/* read() structure */
struct uffd_msg {
	__u8	event;

	__u8	reserved1;
	__u16	reserved2;
	__u32	reserved3;

	union {
		struct {
			__u64	flags;
			__u64	address;
			union {
				__u32 ptid;
			} feat;
		} pagefault;

		struct {
			__u32	ufd;
		} fork;

		struct {
			__u64	from;
			__u64	to;
			__u64	len;
		} remap;

		struct {
			__u64	start;
			__u64	end;
		} remove;

		struct {
			/* unused reserved fields */
			__u64	reserved1;
			__u64	reserved2;
			__u64	reserved3;
		} reserved;
	} arg;
} __attribute__((packed));

/*
 * Start at 0x12 and not at 0 to be more strict against bugs.
 */
#define UFFD_EVENT_PAGEFAULT	0x12
#define UFFD_EVENT_FORK		0x13
#define UFFD_EVENT_REMAP	0x14
#define UFFD_EVENT_REMOVE	0x15
#define UFFD_EVENT_UNMAP	0x16

/* flags for UFFD_EVENT_PAGEFAULT */
#define UFFD_PAGEFAULT_FLAG_WRITE	(1<<0)	/* If this was a write fault */
#define UFFD_PAGEFAULT_FLAG_WP		(1<<1)	/* If reason is VM_UFFD_WP */
#define UFFD_PAGEFAULT_FLAG_MINOR	(1<<2)	/* If reason is VM_UFFD_MINOR */

struct uffdio_api {
	/* userland asks for an API number and the features to enable */
	__u64 api;
	/*
	 * Kernel answers below with the all available features for
	 * the API, this notifies userland of which events and/or
	 * which flags for each event are enabled in the current
	 * kernel.
	 *
	 * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
	 * are to be considered implicitly always enabled in all kernels as
	 * long as the uffdio_api.api requested matches UFFD_API.
	 *
	 * UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER
	 * with UFFDIO_REGISTER_MODE_MISSING mode will succeed on
	 * hugetlbfs virtual memory ranges. Adding or not adding
	 * UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has
	 * no real functional effect after UFFDIO_API returns, but
	 * it's only useful for an initial feature set probe at
	 * UFFDIO_API time. There are two ways to use it:
	 *
	 * 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the
	 *    uffdio_api.features before calling UFFDIO_API, an error
	 *    will be returned by UFFDIO_API on a kernel without
	 *    hugetlbfs missing support
	 *
	 * 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in
	 *    uffdio_api.features and instead it will be set by the
	 *    kernel in the uffdio_api.features if the kernel supports
	 *    it, so userland can later check if the feature flag is
	 *    present in uffdio_api.features after UFFDIO_API
	 *    succeeded.
	 *
	 * UFFD_FEATURE_MISSING_SHMEM works the same as
	 * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem
	 * (i.e. tmpfs and other shmem based APIs).
	 *
	 * UFFD_FEATURE_SIGBUS feature means no page-fault
	 * (UFFD_EVENT_PAGEFAULT) event will be delivered, instead
	 * a SIGBUS signal will be sent to the faulting process.
	 *
	 * UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will
	 * be returned, if feature is not requested 0 will be returned.
	 *
	 * UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults
	 * can be intercepted (via REGISTER_MODE_MINOR) for
	 * hugetlbfs-backed pages.
	 *
	 * UFFD_FEATURE_MINOR_SHMEM indicates the same support as
	 * UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead.
	 *
	 * UFFD_FEATURE_EXACT_ADDRESS indicates that the exact address of page
	 * faults would be provided and the offset within the page would not be
	 * masked.
	 *
	 * UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd
	 * write-protection mode is supported on both shmem and hugetlbfs.
	 *
	 * UFFD_FEATURE_WP_UNPOPULATED indicates that userfaultfd
	 * write-protection mode will always apply to unpopulated pages
	 * (i.e. empty ptes).  This will be the default behavior for shmem
	 * & hugetlbfs, so this flag only affects anonymous memory behavior
	 * when userfault write-protection mode is registered.
	 *
	 * UFFD_FEATURE_WP_ASYNC indicates that userfaultfd write-protection
	 * asynchronous mode is supported in which the write fault is
	 * automatically resolved and write-protection is un-set.
	 * It implies UFFD_FEATURE_WP_UNPOPULATED.
	 */
#define UFFD_FEATURE_PAGEFAULT_FLAG_WP		(1<<0)
#define UFFD_FEATURE_EVENT_FORK			(1<<1)
#define UFFD_FEATURE_EVENT_REMAP		(1<<2)
#define UFFD_FEATURE_EVENT_REMOVE		(1<<3)
#define UFFD_FEATURE_MISSING_HUGETLBFS		(1<<4)
#define UFFD_FEATURE_MISSING_SHMEM		(1<<5)
#define UFFD_FEATURE_EVENT_UNMAP		(1<<6)
#define UFFD_FEATURE_SIGBUS			(1<<7)
#define UFFD_FEATURE_THREAD_ID			(1<<8)
#define UFFD_FEATURE_MINOR_HUGETLBFS		(1<<9)
#define UFFD_FEATURE_MINOR_SHMEM		(1<<10)
#define UFFD_FEATURE_EXACT_ADDRESS		(1<<11)
#define UFFD_FEATURE_WP_HUGETLBFS_SHMEM		(1<<12)
#define UFFD_FEATURE_WP_UNPOPULATED		(1<<13)
#define UFFD_FEATURE_POISON			(1<<14)
#define UFFD_FEATURE_WP_ASYNC			(1<<15)
	__u64 features;

	__u64 ioctls;
};

struct uffdio_range {
	__u64 start;
	__u64 len;
};

struct uffdio_register {
	struct uffdio_range range;
#define UFFDIO_REGISTER_MODE_MISSING	((__u64)1<<0)
#define UFFDIO_REGISTER_MODE_WP		((__u64)1<<1)
#define UFFDIO_REGISTER_MODE_MINOR	((__u64)1<<2)
	__u64 mode;

	/*
	 * kernel answers which ioctl commands are available for the
	 * range, keep at the end as the last 8 bytes aren't read.
	 */
	__u64 ioctls;
};

struct uffdio_copy {
	__u64 dst;
	__u64 src;
	__u64 len;
#define UFFDIO_COPY_MODE_DONTWAKE		((__u64)1<<0)
	/*
	 * UFFDIO_COPY_MODE_WP will map the page write protected on
	 * the fly.  UFFDIO_COPY_MODE_WP is available only if the
	 * write protected ioctl is implemented for the range
	 * according to the uffdio_register.ioctls.
	 */
#define UFFDIO_COPY_MODE_WP			((__u64)1<<1)
	__u64 mode;

	/*
	 * "copy" is written by the ioctl and must be at the end: the
	 * copy_from_user will not read the last 8 bytes.
	 */
	__s64 copy;
};

struct uffdio_zeropage {
	struct uffdio_range range;
#define UFFDIO_ZEROPAGE_MODE_DONTWAKE		((__u64)1<<0)
	__u64 mode;

	/*
	 * "zeropage" is written by the ioctl and must be at the end:
	 * the copy_from_user will not read the last 8 bytes.
	 */
	__s64 zeropage;
};

struct uffdio_writeprotect {
	struct uffdio_range range;
/*
 * UFFDIO_WRITEPROTECT_MODE_WP: set the flag to write protect a range,
 * unset the flag to undo protection of a range which was previously
 * write protected.
 *
 * UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up
 * any wait thread after the operation succeeds.
 *
 * NOTE: Write protecting a region (WP=1) is unrelated to page faults,
 * therefore DONTWAKE flag is meaningless with WP=1.  Removing write
 * protection (WP=0) in response to a page fault wakes the faulting
 * task unless DONTWAKE is set.
 */
#define UFFDIO_WRITEPROTECT_MODE_WP		((__u64)1<<0)
#define UFFDIO_WRITEPROTECT_MODE_DONTWAKE	((__u64)1<<1)
	__u64 mode;
};

struct uffdio_continue {
	struct uffdio_range range;
#define UFFDIO_CONTINUE_MODE_DONTWAKE		((__u64)1<<0)
	/*
	 * UFFDIO_CONTINUE_MODE_WP will map the page write protected on
	 * the fly.  UFFDIO_CONTINUE_MODE_WP is available only if the
	 * write protected ioctl is implemented for the range
	 * according to the uffdio_register.ioctls.
	 */
#define UFFDIO_CONTINUE_MODE_WP			((__u64)1<<1)
	__u64 mode;

	/*
	 * Fields below here are written by the ioctl and must be at the end:
	 * the copy_from_user will not read past here.
	 */
	__s64 mapped;
};

struct uffdio_poison {
	struct uffdio_range range;
#define UFFDIO_POISON_MODE_DONTWAKE		((__u64)1<<0)
	__u64 mode;

	/*
	 * Fields below here are written by the ioctl and must be at the end:
	 * the copy_from_user will not read past here.
	 */
	__s64 updated;
};

/*
 * Flags for the userfaultfd(2) system call itself.
 */

/*
 * Create a userfaultfd that can handle page faults only in user mode.
 */
#define UFFD_USER_MODE_ONLY 1

#endif /* _LINUX_USERFAULTFD_H */
Commit	Line	Data
dd873966	1	/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
c1fcf220 DDAG	2	/*
	3	* include/linux/userfaultfd.h
	4	*
	5	* Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
	6	* Copyright (C) 2015 Red Hat, Inc.
	7	*
	8	*/
	9
	10	#ifndef _LINUX_USERFAULTFD_H
	11	#define _LINUX_USERFAULTFD_H
	12
	13	#include <linux/types.h>
	14
93e0932b PX	15	/* ioctls for /dev/userfaultfd */
	16	#define USERFAULTFD_IOC 0xAA
	17	#define USERFAULTFD_IOC_NEW _IO(USERFAULTFD_IOC, 0x00)
	18
c1fcf220	19	/*
3a5eb5b4 PB	20	* If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and
	21	* UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In
	22	* userfaultfd.h we assumed the kernel was reading (instead _IOC_READ
	23	* means the userland is reading).
c1fcf220	24	*/
3a5eb5b4	25	#define UFFD_API ((__u64)0xAA)
278f064e EH	26	#define UFFD_API_REGISTER_MODES (UFFDIO_REGISTER_MODE_MISSING \| \
	27	UFFDIO_REGISTER_MODE_WP \| \
	28	UFFDIO_REGISTER_MODE_MINOR)
dc6f8d45 CH	29	#define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP \| \
dc6f8d45 CH	30	UFFD_FEATURE_EVENT_FORK \| \
3a5eb5b4	31	UFFD_FEATURE_EVENT_REMAP \| \
278f064e	32	UFFD_FEATURE_EVENT_REMOVE \| \
74c98e20	33	UFFD_FEATURE_EVENT_UNMAP \| \
3a5eb5b4	34	UFFD_FEATURE_MISSING_HUGETLBFS \| \
d4083f50 AP	35	UFFD_FEATURE_MISSING_SHMEM \| \
d4083f50 AP	36	UFFD_FEATURE_SIGBUS \| \
278f064e	37	UFFD_FEATURE_THREAD_ID \| \
327d4b7f	38	UFFD_FEATURE_MINOR_HUGETLBFS \| \
e4082063	39	UFFD_FEATURE_MINOR_SHMEM \| \
d525f73f	40	UFFD_FEATURE_EXACT_ADDRESS \| \
d0bf492f	41	UFFD_FEATURE_WP_HUGETLBFS_SHMEM \| \
da3c22c7	42	UFFD_FEATURE_WP_UNPOPULATED \| \
efb91426 DHB	43	UFFD_FEATURE_POISON \| \
efb91426 DHB	44	UFFD_FEATURE_WP_ASYNC)
c1fcf220 DDAG	45	#define UFFD_API_IOCTLS \
	46	((__u64)1 << _UFFDIO_REGISTER \| \
	47	(__u64)1 << _UFFDIO_UNREGISTER \| \
	48	(__u64)1 << _UFFDIO_API)
	49	#define UFFD_API_RANGE_IOCTLS \
	50	((__u64)1 << _UFFDIO_WAKE \| \
	51	(__u64)1 << _UFFDIO_COPY \| \
dc6f8d45	52	(__u64)1 << _UFFDIO_ZEROPAGE \| \
278f064e	53	(__u64)1 << _UFFDIO_WRITEPROTECT \| \
da3c22c7 TH	54	(__u64)1 << _UFFDIO_CONTINUE \| \
da3c22c7 TH	55	(__u64)1 << _UFFDIO_POISON)
3a5eb5b4 PB	56	#define UFFD_API_RANGE_IOCTLS_BASIC \
3a5eb5b4 PB	57	((__u64)1 << _UFFDIO_WAKE \| \
278f064e	58	(__u64)1 << _UFFDIO_COPY \| \
da3c22c7	59	(__u64)1 << _UFFDIO_WRITEPROTECT \| \
d525f73f	60	(__u64)1 << _UFFDIO_CONTINUE \| \
da3c22c7	61	(__u64)1 << _UFFDIO_POISON)
c1fcf220 DDAG	62
	63	/*
	64	* Valid ioctl command number range with this API is from 0x00 to
	65	* 0x3F. UFFDIO_API is the fixed number, everything else can be
	66	* changed by implementing a different UFFD_API. If sticking to the
	67	* same UFFD_API more ioctl can be added and userland will be aware of
	68	* which ioctl the running kernel implements through the ioctl command
	69	* bitmask written by the UFFDIO_API.
	70	*/
	71	#define _UFFDIO_REGISTER (0x00)
	72	#define _UFFDIO_UNREGISTER (0x01)
	73	#define _UFFDIO_WAKE (0x02)
	74	#define _UFFDIO_COPY (0x03)
	75	#define _UFFDIO_ZEROPAGE (0x04)
dc6f8d45	76	#define _UFFDIO_WRITEPROTECT (0x06)
278f064e	77	#define _UFFDIO_CONTINUE (0x07)
da3c22c7	78	#define _UFFDIO_POISON (0x08)
c1fcf220 DDAG	79	#define _UFFDIO_API (0x3F)
	80
	81	/* userfaultfd ioctl ids */
	82	#define UFFDIO 0xAA
	83	#define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, \
	84	struct uffdio_api)
	85	#define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, \
	86	struct uffdio_register)
	87	#define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, \
	88	struct uffdio_range)
	89	#define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, \
	90	struct uffdio_range)
	91	#define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, \
	92	struct uffdio_copy)
	93	#define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
	94	struct uffdio_zeropage)
dc6f8d45 CH	95	#define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \
dc6f8d45 CH	96	struct uffdio_writeprotect)
327d4b7f BR	97	#define UFFDIO_CONTINUE _IOWR(UFFDIO, _UFFDIO_CONTINUE, \
327d4b7f BR	98	struct uffdio_continue)
da3c22c7 TH	99	#define UFFDIO_POISON _IOWR(UFFDIO, _UFFDIO_POISON, \
da3c22c7 TH	100	struct uffdio_poison)
c1fcf220 DDAG	101
	102	/* read() structure */
	103	struct uffd_msg {
	104	__u8 event;
	105
	106	__u8 reserved1;
	107	__u16 reserved2;
	108	__u32 reserved3;
	109
	110	union {
	111	struct {
	112	__u64 flags;
	113	__u64 address;
d4083f50 AP	114	union {
	115	__u32 ptid;
	116	} feat;
c1fcf220 DDAG	117	} pagefault;
c1fcf220 DDAG	118
3a5eb5b4 PB	119	struct {
	120	__u32 ufd;
	121	} fork;
	122
	123	struct {
	124	__u64 from;
	125	__u64 to;
	126	__u64 len;
	127	} remap;
	128
	129	struct {
	130	__u64 start;
	131	__u64 end;
74c98e20	132	} remove;
3a5eb5b4	133
c1fcf220 DDAG	134	struct {
	135	/* unused reserved fields */
	136	__u64 reserved1;
	137	__u64 reserved2;
	138	__u64 reserved3;
	139	} reserved;
	140	} arg;
b89485a5	141	} __attribute__((packed));
c1fcf220 DDAG	142
	143	/*
	144	* Start at 0x12 and not at 0 to be more strict against bugs.
	145	*/
	146	#define UFFD_EVENT_PAGEFAULT 0x12
c1fcf220	147	#define UFFD_EVENT_FORK 0x13
3a5eb5b4	148	#define UFFD_EVENT_REMAP 0x14
74c98e20 CH	149	#define UFFD_EVENT_REMOVE 0x15
74c98e20 CH	150	#define UFFD_EVENT_UNMAP 0x16
c1fcf220 DDAG	151
	152	/* flags for UFFD_EVENT_PAGEFAULT */
	153	#define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */
	154	#define UFFD_PAGEFAULT_FLAG_WP (1<<1) /* If reason is VM_UFFD_WP */
278f064e	155	#define UFFD_PAGEFAULT_FLAG_MINOR (1<<2) /* If reason is VM_UFFD_MINOR */
c1fcf220 DDAG	156
	157	struct uffdio_api {
	158	/* userland asks for an API number and the features to enable */
	159	__u64 api;
	160	/*
	161	* Kernel answers below with the all available features for
	162	* the API, this notifies userland of which events and/or
	163	* which flags for each event are enabled in the current
	164	* kernel.
	165	*
	166	* Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
	167	* are to be considered implicitly always enabled in all kernels as
	168	* long as the uffdio_api.api requested matches UFFD_API.
3a5eb5b4 PB	169	*
	170	* UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER
	171	* with UFFDIO_REGISTER_MODE_MISSING mode will succeed on
	172	* hugetlbfs virtual memory ranges. Adding or not adding
	173	* UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has
	174	* no real functional effect after UFFDIO_API returns, but
	175	* it's only useful for an initial feature set probe at
	176	* UFFDIO_API time. There are two ways to use it:
	177	*
	178	* 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the
	179	* uffdio_api.features before calling UFFDIO_API, an error
	180	* will be returned by UFFDIO_API on a kernel without
	181	* hugetlbfs missing support
	182	*
	183	* 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in
	184	* uffdio_api.features and instead it will be set by the
	185	* kernel in the uffdio_api.features if the kernel supports
	186	* it, so userland can later check if the feature flag is
	187	* present in uffdio_api.features after UFFDIO_API
	188	* succeeded.
	189	*
	190	* UFFD_FEATURE_MISSING_SHMEM works the same as
	191	* UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem
	192	* (i.e. tmpfs and other shmem based APIs).
d4083f50 AP	193	*
	194	* UFFD_FEATURE_SIGBUS feature means no page-fault
	195	* (UFFD_EVENT_PAGEFAULT) event will be delivered, instead
	196	* a SIGBUS signal will be sent to the faulting process.
	197	*
	198	* UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will
	199	* be returned, if feature is not requested 0 will be returned.
278f064e EH	200	*
	201	* UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults
	202	* can be intercepted (via REGISTER_MODE_MINOR) for
	203	* hugetlbfs-backed pages.
327d4b7f BR	204	*
	205	* UFFD_FEATURE_MINOR_SHMEM indicates the same support as
	206	* UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead.
e4082063 AW	207	*
	208	* UFFD_FEATURE_EXACT_ADDRESS indicates that the exact address of page
	209	* faults would be provided and the offset within the page would not be
	210	* masked.
d525f73f CQ	211	*
	212	* UFFD_FEATURE_WP_HUGETLBFS_SHMEM indicates that userfaultfd
	213	* write-protection mode is supported on both shmem and hugetlbfs.
d0bf492f CLG	214	*
	215	* UFFD_FEATURE_WP_UNPOPULATED indicates that userfaultfd
	216	* write-protection mode will always apply to unpopulated pages
	217	* (i.e. empty ptes). This will be the default behavior for shmem
	218	* & hugetlbfs, so this flag only affects anonymous memory behavior
	219	* when userfault write-protection mode is registered.
efb91426 DHB	220	*
	221	* UFFD_FEATURE_WP_ASYNC indicates that userfaultfd write-protection
	222	* asynchronous mode is supported in which the write fault is
	223	* automatically resolved and write-protection is un-set.
	224	* It implies UFFD_FEATURE_WP_UNPOPULATED.
c1fcf220	225	*/
c1fcf220 DDAG	226	#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
c1fcf220 DDAG	227	#define UFFD_FEATURE_EVENT_FORK (1<<1)
3a5eb5b4	228	#define UFFD_FEATURE_EVENT_REMAP (1<<2)
74c98e20	229	#define UFFD_FEATURE_EVENT_REMOVE (1<<3)
3a5eb5b4 PB	230	#define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)
3a5eb5b4 PB	231	#define UFFD_FEATURE_MISSING_SHMEM (1<<5)
74c98e20	232	#define UFFD_FEATURE_EVENT_UNMAP (1<<6)
d4083f50 AP	233	#define UFFD_FEATURE_SIGBUS (1<<7)
d4083f50 AP	234	#define UFFD_FEATURE_THREAD_ID (1<<8)
278f064e	235	#define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9)
327d4b7f	236	#define UFFD_FEATURE_MINOR_SHMEM (1<<10)
e4082063	237	#define UFFD_FEATURE_EXACT_ADDRESS (1<<11)
d525f73f	238	#define UFFD_FEATURE_WP_HUGETLBFS_SHMEM (1<<12)
d0bf492f	239	#define UFFD_FEATURE_WP_UNPOPULATED (1<<13)
da3c22c7	240	#define UFFD_FEATURE_POISON (1<<14)
efb91426	241	#define UFFD_FEATURE_WP_ASYNC (1<<15)
c1fcf220 DDAG	242	__u64 features;
	243
	244	__u64 ioctls;
	245	};
	246
	247	struct uffdio_range {
	248	__u64 start;
	249	__u64 len;
	250	};
	251
	252	struct uffdio_register {
	253	struct uffdio_range range;
	254	#define UFFDIO_REGISTER_MODE_MISSING ((__u64)1<<0)
	255	#define UFFDIO_REGISTER_MODE_WP ((__u64)1<<1)
278f064e	256	#define UFFDIO_REGISTER_MODE_MINOR ((__u64)1<<2)
c1fcf220 DDAG	257	__u64 mode;
	258
	259	/*
	260	* kernel answers which ioctl commands are available for the
	261	* range, keep at the end as the last 8 bytes aren't read.
	262	*/
	263	__u64 ioctls;
	264	};
	265
	266	struct uffdio_copy {
	267	__u64 dst;
	268	__u64 src;
	269	__u64 len;
dc6f8d45	270	#define UFFDIO_COPY_MODE_DONTWAKE ((__u64)1<<0)
c1fcf220	271	/*
dc6f8d45 CH	272	* UFFDIO_COPY_MODE_WP will map the page write protected on
	273	* the fly. UFFDIO_COPY_MODE_WP is available only if the
	274	* write protected ioctl is implemented for the range
	275	* according to the uffdio_register.ioctls.
c1fcf220	276	*/
dc6f8d45	277	#define UFFDIO_COPY_MODE_WP ((__u64)1<<1)
c1fcf220 DDAG	278	__u64 mode;
	279
	280	/*
	281	* "copy" is written by the ioctl and must be at the end: the
	282	* copy_from_user will not read the last 8 bytes.
	283	*/
	284	__s64 copy;
	285	};
	286
	287	struct uffdio_zeropage {
	288	struct uffdio_range range;
	289	#define UFFDIO_ZEROPAGE_MODE_DONTWAKE ((__u64)1<<0)
	290	__u64 mode;
	291
	292	/*
	293	* "zeropage" is written by the ioctl and must be at the end:
	294	* the copy_from_user will not read the last 8 bytes.
	295	*/
	296	__s64 zeropage;
	297	};
	298
dc6f8d45 CH	299	struct uffdio_writeprotect {
	300	struct uffdio_range range;
	301	/*
	302	* UFFDIO_WRITEPROTECT_MODE_WP: set the flag to write protect a range,
	303	* unset the flag to undo protection of a range which was previously
	304	* write protected.
	305	*
	306	* UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up
	307	* any wait thread after the operation succeeds.
	308	*
	309	* NOTE: Write protecting a region (WP=1) is unrelated to page faults,
	310	* therefore DONTWAKE flag is meaningless with WP=1. Removing write
	311	* protection (WP=0) in response to a page fault wakes the faulting
	312	* task unless DONTWAKE is set.
	313	*/
	314	#define UFFDIO_WRITEPROTECT_MODE_WP ((__u64)1<<0)
	315	#define UFFDIO_WRITEPROTECT_MODE_DONTWAKE ((__u64)1<<1)
	316	__u64 mode;
	317	};
	318
278f064e EH	319	struct uffdio_continue {
	320	struct uffdio_range range;
	321	#define UFFDIO_CONTINUE_MODE_DONTWAKE ((__u64)1<<0)
d0bf492f CLG	322	/*
	323	* UFFDIO_CONTINUE_MODE_WP will map the page write protected on
	324	* the fly. UFFDIO_CONTINUE_MODE_WP is available only if the
	325	* write protected ioctl is implemented for the range
	326	* according to the uffdio_register.ioctls.
	327	*/
	328	#define UFFDIO_CONTINUE_MODE_WP ((__u64)1<<1)
278f064e EH	329	__u64 mode;
	330
	331	/*
	332	* Fields below here are written by the ioctl and must be at the end:
	333	* the copy_from_user will not read past here.
	334	*/
	335	__s64 mapped;
	336	};
	337
da3c22c7 TH	338	struct uffdio_poison {
	339	struct uffdio_range range;
	340	#define UFFDIO_POISON_MODE_DONTWAKE ((__u64)1<<0)
	341	__u64 mode;
	342
	343	/*
	344	* Fields below here are written by the ioctl and must be at the end:
	345	* the copy_from_user will not read past here.
	346	*/
	347	__s64 updated;
	348	};
	349
b3c818a4 EF	350	/*
	351	* Flags for the userfaultfd(2) system call itself.
	352	*/
	353
	354	/*
	355	* Create a userfaultfd that can handle page faults only in user mode.
	356	*/
	357	#define UFFD_USER_MODE_ONLY 1
	358
c1fcf220	359	#endif /* _LINUX_USERFAULTFD_H */