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